We-min Chow - Academia.edu (original) (raw)
Papers by We-min Chow
Production Planning & Control, 1999
Recent information technological advances have led to the workflow system that provides an effect... more Recent information technological advances have led to the workflow system that provides an effective technical solution for productivity improvement and business process reengineering. Workflow is a network of activities, also commonly known as a business process, defined for a specific business objective. The fundamental principle of workflow technology is the separation of business process from (software) applications and data. This implies a flexible, adaptable system that can support dynamic business changes. This flexibility, however, is not built upon complexity. Instead, the system should be easily modified for a new business environment. On the other hand, a good workflow system facilitates individual tasks, and collectively the entire business process by providing accurate inputs (data, forms tools) and effective routing control. Workflow technology has a wide range of applications and, when appropriately implemented, can increase productivity, reduce operating costs, improve response to customer...
Assembly Line Design, 2020
Journal of Manufacturing Systems, 1990
... 17. Connections in Electronic Assemblies, Anthony J. Bilotta Page 7. 18. Automation for Press... more ... 17. Connections in Electronic Assemblies, Anthony J. Bilotta Page 7. 18. Automation for Press Feed Operations: Applications and Economics, Edward Walker 19. Nontraditional Manufacturing Processes, Gary F. Benedict 20. ...
Bakalářská práce se zabývá návrhem montážní linky s použitím koncepce One Piece Flow ve společnos... more Bakalářská práce se zabývá návrhem montážní linky s použitím koncepce One Piece Flow ve společnosti SOPO, s.r.o. Je zde představena problematika výrobního systému, jeho automatizace a optimalizace pomocí štíhlé výroby. V práci je také popsána teorie montáže a ergonomie montážní linky. Byla provedena analýza současné montážní linky a na základě jejích výsledků byla pomocí principů One Piece Flow navržena nová, optimalizovaná montážní linka. Tato nová montážní linka zabezpečí lepší prostorové využití, zkrácení průběžné doby výroby, zvětšení flexibility výroby a zlepšení ergonomie práce.The subject of this bachelor thesis is design of an assembly line with implementation of One Piece Flow in company SOPO, ltd. Topics of production systems are discussed, including its automation and optimization by using Lean production principles. In this bachelor thesis the theory of assembly and ergonomics of assembly line is described. The analysis of current assembly line was performed and based on its results new optimized assembly line was designed by using principles of One Piece Flow. New assembly line will provide better spatial use, reduction of manufacturing lead time, increase of production flexibility and better ergonomics of work
Transportation Research Record, 1976
When an incident occurs on a roadway, traffic performance is usually evaluated by means of either... more When an incident occurs on a roadway, traffic performance is usually evaluated by means of either the shock wave analysis or the queuing analysis. In this paper, a comparison of these two approaches is given under the assumption that there exists a unique flow-density relationship. It is shown that the two methods of evaluating the performance give the same result if the traffic density is not time dependent.
Highway Research Record, 1973
TWO MODELS WERE USED TO FIND THE OPTIMAL LOCATIONS FOR SERVICE FACILITIES ALONG A FREEWAY. THE FI... more TWO MODELS WERE USED TO FIND THE OPTIMAL LOCATIONS FOR SERVICE FACILITIES ALONG A FREEWAY. THE FIRST ONE IS A SIMULATION MODEL CALLED FREEQ. FOR A GIVEN ACCIDENT OR INCIDENT ON THE FREEWAY, FREEQ CAN BE EMPLOYED TO GENERATE ALL NECESSARY INFORMATION, SUCH AS TOTAL TRAVEL TIME AND INDIVIDUAL AVERAGE TRAVEL TIME ON THE FREEWAY, PROVIDED THAT THE DEMAND PATTERN AND THE PHYSICAL CONFIGURATION OF THE FREEWAY ARE KNOWN. BASED ON THESE RESULTS, AN OPTIMIZATION MODEL IS USED TO SEARCH FOR THE BEST LOCATIONS FOR SERVICE FACILITIES SO THAT THE TOTAL DELAY TIME CAUSED BY THE ACCIDENT OR INCIDENT OR THE RESPONSE TIME OF THE SERVICE UNIT IS MINIMIZED. THE EAST-SHORE FREEWAY IN THE SAN FRAN- CISCO BAY AREA WAS CHOSEN TO BE THE STUDY AREA. THUS, A NUMERICAL PROBLEM IS ALSO GIVEN.
Proceedings. 1986 IEEE International Conference on Robotics and Automation
This paper describes the development considerations and logic of an automated storage and retriev... more This paper describes the development considerations and logic of an automated storage and retrieval system (AS/RS). The system is used as a material handling system for a class of manufacturing assembly lines. First defined is the manufacturing environment from which the design objective and constraints are derived. Queueing and simulation models are employed to identify the key performance parameters, to evaluate design alternatives, and to compare different dispatching rules. Both hardware and software design concept and parameters are briefly reviewed. A work-in-process management policy and a line design concept associated with AS/RS are introduced.
Performance Evaluation, 1983
Evaluation of closed queueing networks with product form solutions is very time-consuming if the ... more Evaluation of closed queueing networks with product form solutions is very time-consuming if the population sizes or the network size is large. This paper provides an analysis of an approximation technique, based upon mean value analysis which requires considerably less computation time, and yet achieves a high degree of accuracy. The approximates are unique in some feasible regions. Error analysis and illustrative examples are provided.
Computer Compacts, 1983
An approximation technique to solve central server queueing models with a priority dispatching ru... more An approximation technique to solve central server queueing models with a priority dispatching rule is described in this paper. This technique reduces the problem size by aggregating 1/O activities and combining different classes into a smaller number of classes, so that the reduced problem can be solved numerically in a rather short time. In 14 different cases of numerical examples considered, throughputs and mean CPU queue sizes calculated by the approximation differ from simulation results by less than 15 percent.
Transportation Science, 1976
This study is concerned with the analysis of a stationary emergency service system, and includes ... more This study is concerned with the analysis of a stationary emergency service system, and includes the application of this analytic procedure to the Los Angeles Freeway Surveillance and Control Project. The stationary emergency service system is interpreted as an ordinary queuing system and is approximated by an M/G/∞ model. In conjunction with queuing theory, dynamic programming is used to determine the best locations for service facilities, the optimal number of service vehicles at each service location, and the service area covered by an individual service location.
Production Planning & Control, 1991
Abstract It is not an uncommon problem that a finished product cannot be delivered to its custome... more Abstract It is not an uncommon problem that a finished product cannot be delivered to its customer due to order change. In many real-life applications, such as rack-mounted computer products, it is possible to reconfigure a product by altering the combination of its components. Therefore, an inventory item, resulting from a cancelled order, can be handled in one of two ways: (1) keep the product in storage for a future order; or (2) send the product back to the manufacturing Door for reconfiguration in accordance with a new order A wise decision can be made by evaluating the trade-off between the inventory cost and the conversion cost. This paper presents an optimization procedure for achieving the minimum-cost solution. The problem is formulated by a quadratic programming model. Under a fairly general condition, the problem can be converted into a standard capacitated transportation problem and, therefore, can be solved efficiently. The cost structure, problem formulation, and solution technique arc disc...
Production Planning & Control, 1990
Production Planning & Control, 1999
Date-related system failure for many organizations may become reality at Year 2000. No matter how... more Date-related system failure for many organizations may become reality at Year 2000. No matter how hard a company has been trying to fix the system errors, there is no guarantee for problem free systems. Y2K-induced failures may cause loss of business, legal and safety issues. A contingency plan therefore is necessary. This paper discusses a contingency planning process, including planning principles, methodology and plan management.
Journal of the ACM, 1980
The cycle time distribution of a cyclic queue with two exponential servers is derived. Results sh... more The cycle time distribution of a cyclic queue with two exponential servers is derived. Results show that when the population size N is large enough, the cycle time distribution is not sensitive to the ratio of service rates and asymptotically approaches an Erlangian distribution. If service rates are identical, however, the cycle time has an exact Erlangian distribution for any N .
International Journal of Production Research, 1994
Abstract This paper discusses an audit plan, based on a continuous sampling technique, queuing th... more Abstract This paper discusses an audit plan, based on a continuous sampling technique, queuing theory and sequential analysis. For a given test operation, if all tested products can successfully pass the operation, only a portion of the arrivals will be tested, that is the process is in an audit mode. However, once a failure occurs, all subsequent products must be tested (i.e. in a screen mode) until K consecutive good products are observed. In this case, the operation will return back to the audit mode. The portion of the products to be tested is determined by the arrival process and the capacity of the test operation. If the test capacity is below the arrival rate, line congestion may occur owing to line screening triggered by a product failure. The degree of congestion is measured by the level of work in process and the actual throughput. Furthermore, products may bypass the test operation under the audit plan. One must carefully estimate the escape rate. Finally, it is always desirable to detect proce...
International Journal of Production Research, 1988
Job assignment is a well-known problem in manufacturing lines. Line management tries to maximize ... more Job assignment is a well-known problem in manufacturing lines. Line management tries to maximize line productivity by assigning a given crew a set of predefined line jobs. However, problems may arise because of abnormal conditions such as absenteeism, workstation failure, parts shortage, or unevenly distributed work-in-process. This report considers a dynamic job-assignment policy making use of online information for assignment. This policy attempts to achieve a good skill match between jobs and operators, and to eliminate unnecessary assignments. To fulfill this policy, a two-part assignment program is proposed: an algorithm for job matching and a set of ad hoc rules. The matching algorithm is well established in literature, but the ad hoc rules are application-dependent. Discussion here concentrates on the ad hoc rules and online data collection.
IIE Transactions, 1986
An automated storage/retrieval system is a material handling system that can be used to pick and ... more An automated storage/retrieval system is a material handling system that can be used to pick and to deliver materials in a direct access fashion. An M/G/1 queueing model is used to study the system performance under a first-come-first-served dispatching rule. More detailed studies for different dispatching rules have been done by simulation. A number of cases with different hardware characteristics and workloads have been investigated. Conclusion is drawn based upon the results obtained from analysis as well as numerical experiments.
IIE Transactions, 1995
This paper discusses operation procedures for use in a multi-product test environment, where iden... more This paper discusses operation procedures for use in a multi-product test environment, where identical products are tested simultaneously by the same test equipment. When a failure occurs during a test, at least two different procedures may be invoked: (1) replace the faulty product and re-start the test; (2) continue the test without replacing the faulty product. The first approach increases the total test time whereas the latter reduces test capacity by testing faulty products. In this paper, both of the cases will be analyzed by using stochastic models. As a result of this analysis, a composite policy, a mixture of the two, will be proposed. The criterion for test policy selection is to maximize throughput without sacrificing quality. It is shown that an approximate optimal solution can be characterized by the ratio of the test time to the number of products under the test.
IBM Systems Journal, 1978
... is the link between the simulation com-ponent and the analytic part, and has the purpose ofbu... more ... is the link between the simulation com-ponent and the analytic part, and has the purpose ofbuilding pa-rameters to ... analytic The analytic part of the performance model of MVS-which we component call PMOD-is a multiclass Central Server queuing network Model (CSM) of ...
Production Planning & Control, 1999
Recent information technological advances have led to the workflow system that provides an effect... more Recent information technological advances have led to the workflow system that provides an effective technical solution for productivity improvement and business process reengineering. Workflow is a network of activities, also commonly known as a business process, defined for a specific business objective. The fundamental principle of workflow technology is the separation of business process from (software) applications and data. This implies a flexible, adaptable system that can support dynamic business changes. This flexibility, however, is not built upon complexity. Instead, the system should be easily modified for a new business environment. On the other hand, a good workflow system facilitates individual tasks, and collectively the entire business process by providing accurate inputs (data, forms tools) and effective routing control. Workflow technology has a wide range of applications and, when appropriately implemented, can increase productivity, reduce operating costs, improve response to customer...
Assembly Line Design, 2020
Journal of Manufacturing Systems, 1990
... 17. Connections in Electronic Assemblies, Anthony J. Bilotta Page 7. 18. Automation for Press... more ... 17. Connections in Electronic Assemblies, Anthony J. Bilotta Page 7. 18. Automation for Press Feed Operations: Applications and Economics, Edward Walker 19. Nontraditional Manufacturing Processes, Gary F. Benedict 20. ...
Bakalářská práce se zabývá návrhem montážní linky s použitím koncepce One Piece Flow ve společnos... more Bakalářská práce se zabývá návrhem montážní linky s použitím koncepce One Piece Flow ve společnosti SOPO, s.r.o. Je zde představena problematika výrobního systému, jeho automatizace a optimalizace pomocí štíhlé výroby. V práci je také popsána teorie montáže a ergonomie montážní linky. Byla provedena analýza současné montážní linky a na základě jejích výsledků byla pomocí principů One Piece Flow navržena nová, optimalizovaná montážní linka. Tato nová montážní linka zabezpečí lepší prostorové využití, zkrácení průběžné doby výroby, zvětšení flexibility výroby a zlepšení ergonomie práce.The subject of this bachelor thesis is design of an assembly line with implementation of One Piece Flow in company SOPO, ltd. Topics of production systems are discussed, including its automation and optimization by using Lean production principles. In this bachelor thesis the theory of assembly and ergonomics of assembly line is described. The analysis of current assembly line was performed and based on its results new optimized assembly line was designed by using principles of One Piece Flow. New assembly line will provide better spatial use, reduction of manufacturing lead time, increase of production flexibility and better ergonomics of work
Transportation Research Record, 1976
When an incident occurs on a roadway, traffic performance is usually evaluated by means of either... more When an incident occurs on a roadway, traffic performance is usually evaluated by means of either the shock wave analysis or the queuing analysis. In this paper, a comparison of these two approaches is given under the assumption that there exists a unique flow-density relationship. It is shown that the two methods of evaluating the performance give the same result if the traffic density is not time dependent.
Highway Research Record, 1973
TWO MODELS WERE USED TO FIND THE OPTIMAL LOCATIONS FOR SERVICE FACILITIES ALONG A FREEWAY. THE FI... more TWO MODELS WERE USED TO FIND THE OPTIMAL LOCATIONS FOR SERVICE FACILITIES ALONG A FREEWAY. THE FIRST ONE IS A SIMULATION MODEL CALLED FREEQ. FOR A GIVEN ACCIDENT OR INCIDENT ON THE FREEWAY, FREEQ CAN BE EMPLOYED TO GENERATE ALL NECESSARY INFORMATION, SUCH AS TOTAL TRAVEL TIME AND INDIVIDUAL AVERAGE TRAVEL TIME ON THE FREEWAY, PROVIDED THAT THE DEMAND PATTERN AND THE PHYSICAL CONFIGURATION OF THE FREEWAY ARE KNOWN. BASED ON THESE RESULTS, AN OPTIMIZATION MODEL IS USED TO SEARCH FOR THE BEST LOCATIONS FOR SERVICE FACILITIES SO THAT THE TOTAL DELAY TIME CAUSED BY THE ACCIDENT OR INCIDENT OR THE RESPONSE TIME OF THE SERVICE UNIT IS MINIMIZED. THE EAST-SHORE FREEWAY IN THE SAN FRAN- CISCO BAY AREA WAS CHOSEN TO BE THE STUDY AREA. THUS, A NUMERICAL PROBLEM IS ALSO GIVEN.
Proceedings. 1986 IEEE International Conference on Robotics and Automation
This paper describes the development considerations and logic of an automated storage and retriev... more This paper describes the development considerations and logic of an automated storage and retrieval system (AS/RS). The system is used as a material handling system for a class of manufacturing assembly lines. First defined is the manufacturing environment from which the design objective and constraints are derived. Queueing and simulation models are employed to identify the key performance parameters, to evaluate design alternatives, and to compare different dispatching rules. Both hardware and software design concept and parameters are briefly reviewed. A work-in-process management policy and a line design concept associated with AS/RS are introduced.
Performance Evaluation, 1983
Evaluation of closed queueing networks with product form solutions is very time-consuming if the ... more Evaluation of closed queueing networks with product form solutions is very time-consuming if the population sizes or the network size is large. This paper provides an analysis of an approximation technique, based upon mean value analysis which requires considerably less computation time, and yet achieves a high degree of accuracy. The approximates are unique in some feasible regions. Error analysis and illustrative examples are provided.
Computer Compacts, 1983
An approximation technique to solve central server queueing models with a priority dispatching ru... more An approximation technique to solve central server queueing models with a priority dispatching rule is described in this paper. This technique reduces the problem size by aggregating 1/O activities and combining different classes into a smaller number of classes, so that the reduced problem can be solved numerically in a rather short time. In 14 different cases of numerical examples considered, throughputs and mean CPU queue sizes calculated by the approximation differ from simulation results by less than 15 percent.
Transportation Science, 1976
This study is concerned with the analysis of a stationary emergency service system, and includes ... more This study is concerned with the analysis of a stationary emergency service system, and includes the application of this analytic procedure to the Los Angeles Freeway Surveillance and Control Project. The stationary emergency service system is interpreted as an ordinary queuing system and is approximated by an M/G/∞ model. In conjunction with queuing theory, dynamic programming is used to determine the best locations for service facilities, the optimal number of service vehicles at each service location, and the service area covered by an individual service location.
Production Planning & Control, 1991
Abstract It is not an uncommon problem that a finished product cannot be delivered to its custome... more Abstract It is not an uncommon problem that a finished product cannot be delivered to its customer due to order change. In many real-life applications, such as rack-mounted computer products, it is possible to reconfigure a product by altering the combination of its components. Therefore, an inventory item, resulting from a cancelled order, can be handled in one of two ways: (1) keep the product in storage for a future order; or (2) send the product back to the manufacturing Door for reconfiguration in accordance with a new order A wise decision can be made by evaluating the trade-off between the inventory cost and the conversion cost. This paper presents an optimization procedure for achieving the minimum-cost solution. The problem is formulated by a quadratic programming model. Under a fairly general condition, the problem can be converted into a standard capacitated transportation problem and, therefore, can be solved efficiently. The cost structure, problem formulation, and solution technique arc disc...
Production Planning & Control, 1990
Production Planning & Control, 1999
Date-related system failure for many organizations may become reality at Year 2000. No matter how... more Date-related system failure for many organizations may become reality at Year 2000. No matter how hard a company has been trying to fix the system errors, there is no guarantee for problem free systems. Y2K-induced failures may cause loss of business, legal and safety issues. A contingency plan therefore is necessary. This paper discusses a contingency planning process, including planning principles, methodology and plan management.
Journal of the ACM, 1980
The cycle time distribution of a cyclic queue with two exponential servers is derived. Results sh... more The cycle time distribution of a cyclic queue with two exponential servers is derived. Results show that when the population size N is large enough, the cycle time distribution is not sensitive to the ratio of service rates and asymptotically approaches an Erlangian distribution. If service rates are identical, however, the cycle time has an exact Erlangian distribution for any N .
International Journal of Production Research, 1994
Abstract This paper discusses an audit plan, based on a continuous sampling technique, queuing th... more Abstract This paper discusses an audit plan, based on a continuous sampling technique, queuing theory and sequential analysis. For a given test operation, if all tested products can successfully pass the operation, only a portion of the arrivals will be tested, that is the process is in an audit mode. However, once a failure occurs, all subsequent products must be tested (i.e. in a screen mode) until K consecutive good products are observed. In this case, the operation will return back to the audit mode. The portion of the products to be tested is determined by the arrival process and the capacity of the test operation. If the test capacity is below the arrival rate, line congestion may occur owing to line screening triggered by a product failure. The degree of congestion is measured by the level of work in process and the actual throughput. Furthermore, products may bypass the test operation under the audit plan. One must carefully estimate the escape rate. Finally, it is always desirable to detect proce...
International Journal of Production Research, 1988
Job assignment is a well-known problem in manufacturing lines. Line management tries to maximize ... more Job assignment is a well-known problem in manufacturing lines. Line management tries to maximize line productivity by assigning a given crew a set of predefined line jobs. However, problems may arise because of abnormal conditions such as absenteeism, workstation failure, parts shortage, or unevenly distributed work-in-process. This report considers a dynamic job-assignment policy making use of online information for assignment. This policy attempts to achieve a good skill match between jobs and operators, and to eliminate unnecessary assignments. To fulfill this policy, a two-part assignment program is proposed: an algorithm for job matching and a set of ad hoc rules. The matching algorithm is well established in literature, but the ad hoc rules are application-dependent. Discussion here concentrates on the ad hoc rules and online data collection.
IIE Transactions, 1986
An automated storage/retrieval system is a material handling system that can be used to pick and ... more An automated storage/retrieval system is a material handling system that can be used to pick and to deliver materials in a direct access fashion. An M/G/1 queueing model is used to study the system performance under a first-come-first-served dispatching rule. More detailed studies for different dispatching rules have been done by simulation. A number of cases with different hardware characteristics and workloads have been investigated. Conclusion is drawn based upon the results obtained from analysis as well as numerical experiments.
IIE Transactions, 1995
This paper discusses operation procedures for use in a multi-product test environment, where iden... more This paper discusses operation procedures for use in a multi-product test environment, where identical products are tested simultaneously by the same test equipment. When a failure occurs during a test, at least two different procedures may be invoked: (1) replace the faulty product and re-start the test; (2) continue the test without replacing the faulty product. The first approach increases the total test time whereas the latter reduces test capacity by testing faulty products. In this paper, both of the cases will be analyzed by using stochastic models. As a result of this analysis, a composite policy, a mixture of the two, will be proposed. The criterion for test policy selection is to maximize throughput without sacrificing quality. It is shown that an approximate optimal solution can be characterized by the ratio of the test time to the number of products under the test.
IBM Systems Journal, 1978
... is the link between the simulation com-ponent and the analytic part, and has the purpose ofbu... more ... is the link between the simulation com-ponent and the analytic part, and has the purpose ofbuilding pa-rameters to ... analytic The analytic part of the performance model of MVS-which we component call PMOD-is a multiclass Central Server queuing network Model (CSM) of ...