Didik Wahjudi - Academia.edu (original) (raw)
Papers by Didik Wahjudi
Jurnal Teknik Mesin Universitas Kristen Petra, Apr 1, 2000
Makalah ini membahas bagaimana memodelkan dan memvalidasi suatu sistem pengatur ketinggian air. S... more Makalah ini membahas bagaimana memodelkan dan memvalidasi suatu sistem pengatur ketinggian air. Sistem terdiri dari sebuah tangki tunggal, sensor ketinggian muka air, pompa, driver pompa dan elemen-elemen perubah ADC dan DAC. Pemodelan sistem keseluruhan disusun dari pemodelan elemen-elemen yang diturunkan secara emperik. Validasi atas pemodelam sistem ini dilakukan dengan cara membandingkan kurva respon dari model persamaan sistem secara keseluruhan dan kurva respon riel dari hasil pengukuran. Pemodelan sistem ini menunjukkan hasil yang cukup baik. Kata kunci : pemodelan, kontrol tinggi permukaan air, Algoritma PID, visualisasi.
Corrosion rate can be reduced by adding inhibitor and inhibition efficiency is a measure if its a... more Corrosion rate can be reduced by adding inhibitor and inhibition efficiency is a measure if its ability to suppress corrosion. The result of the immersion tests show that the inhibition efficiencies are different on each environment. Addition of 50 ppm of ascorbic acid results in the highest efficiency for NaC1 and CaCO3 environment while for Ca SO4 environment needs 100 ppm. Abstract in Bahasa Indonesia : Pemberian inhibitor dapat mengurangi laju korosi dan kemampuannya untuk menginhibisi diukur dari efisiensinya. Hasil penelitian menunjukkan bahwa efisiensi inhibisi berbeda-beda pada lingkungan yang berbeda. Penambahan inhibitor yang paling efisien untuk lingkungan NaCl dan CaCO3 dalah 50 ppm asam askorbat sedangkan untuk lingkungan CaSO4 adalah 100 ppm asam askorbat. Kata kunci : laju korosi, efisiensi inhibisi, asam askorbat.
Dimensi Utama Teknik Sipil
ABSTRACT: Property plays important role in economy business activities. In 2013 property grows by... more ABSTRACT: Property plays important role in economy business activities. In 2013 property grows by 800,000 units per year, while the supply capacity is only 300,000 units per year. This fact makes the property growth become more interesting. This growth is supported by the middle class growth that reaches 100 million people in 2013 and is estimated to be 141 million people in 2020. Previous research is done on one residential area. This research aims to develop a residential satisfaction measurement model of middle class residential customers in Surabaya-Sidoarjo. This study is different from the previous one in that this research conducts survey on 3 residential complexes and utilizes more comprehensive model. 226 respondents from 3 residential areas in Surabaya-Sidoarjo were collected. The implication of this study is to give the information about the variables that are significant, the level of satisfaction of the consumers on those variables, and improvement priority for develope...
Jurnal Teknik Mesin, 2021
Kendaraan bermotor sebagai alat transportasi saat ini menjadi salah satu kebutuhan penting untuk ... more Kendaraan bermotor sebagai alat transportasi saat ini menjadi salah satu kebutuhan penting untuk manusia. Jumlah sepeda motor terus meningkat setiap tahunnya. Hal ini menyebabkan sampah atau limbah berupa komponen yang telah rusak dari sebuah kendaraan juga terus meningkat. Saat ini, beberapa bentuk dari limbah tersebut dapat dilakukan recycle agar materialnya dapat dimanfaatkan kembali. Beberapa komponen yang telah rusak sebenarnya masih dapat digunakan lagi dengan beberapa proses seperti repair, refurbish atau remanufaktur. Proses remanufaktur adalah salah satu recovery option paling tinggi dalam mengolah limbah atau sampah. Dalam melakukan perancangan proses remanufaktur untuk komponen otomotif, perlu adanya pemilihan komponen yang akan dijadikan objek. Setelah pemilihan objek, maka dibuat serangkaian proses yang harus ada di dalam proses remanufaktur komponen otomotif seperti disassembly, cleaning, inspection, recondition, dan reassembly. Tahap akhirnya adalah membuat gambar ran...
Seminar Nasional Teknik Mesin IV: Study Kasus …
Jurnal Teknik Mesin, 2004
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fportfolio.petra.ac.id
PT X merasa perlu untuk mempertahankan keunggulannya sebagai produsen kemasan plastik yang bermut... more PT X merasa perlu untuk mempertahankan keunggulannya sebagai produsen kemasan plastik yang bermutu dan harganya bersaing. Namun hal ini tidak mudah tercapai. Kondisi yang saat ini perlu diperbaiki adalah sering terjadinya gangguan pada proses produksi. Pada ...
An academic directory and search engine.
Jurnal Teknik Mesin, 2004
fportfolio.petra.ac.id
Optimasi kualitas warna minyak goreng dilakukan dengan mengadakan eksperimen menggunakan sampel m... more Optimasi kualitas warna minyak goreng dilakukan dengan mengadakan eksperimen menggunakan sampel minyak goreng dengan berat 98 gram dan zat pemutih 2 gram, yang terdiri dari bleaching earth dan carbon active. Variabel yang mempengaruhi warna minyak goreng ada tiga, ...
Jurnal Teknik Mesin, 2004
In attempt to increase the quality of SR-24-type iron rods several constraints are often faced. O... more In attempt to increase the quality of SR-24-type iron rods several constraints are often faced. One of the problems is the high variability of yield strength quality characteristic. A research of influential factors and ideal composition of materials that can minimize quality variability is needed. To solve the above problem Taguchi method is used in designing the experiment. The superiority of this method is the ability to minimize variability of response and the efficiency of experiment. First steps that is taken is choosing control and noise factors and determining the levels. Then, the orthogonal matrix for experiment is built. Data analysis are done by optimizing signal-to-noise ratio, analysis of means, and analysis of variance. Result of analysis of SNR and mean give a conclusion that Carbon content of 0.1 %, Silicon content of 0.15 %, and Mangan content of 0.5 % are sufficient composition of additive material that will minimize variability level of yield strength. Abstract i...
E3S Web of Conferences, 2019
Electrical Discharge Machining (EDM) is one of the most common non-conventional machining process... more Electrical Discharge Machining (EDM) is one of the most common non-conventional machining processes used in the manufacturing of die and mold. In the process of EDM, practitioners usually face a problem, which is how to shorten process time and determine the point where the current should be changed so that the resulted surface roughness is not too high due to the use of large current at the beginning of the process. The purpose of this study is to determine the point when to change (reduce) the current in order to obtain the desired surface roughness and shortest processing time. From analysis of data, experiment was obtained some regression equations, those are: average surface roughness (Ra = 5424 + 0.698 I) which is used to find the final current to obtain the desired final surface roughness, peaks to valleys average roughness (Rz = 5.73 + 3.418 I) which is used to find the changing point for initial currentand duration of processing time (t =103.164 + 0.4714 I) which is used to...
Operations Research Perspectives, 2015
In this study we develop a model that optimizes the price for new and remanufactured short life-c... more In this study we develop a model that optimizes the price for new and remanufactured short life-cycle products where demands are time-dependent and price sensitive. While there has been very few published works that attempt to model remanufacturing decisions for products with short life cycle, we believe that there are many situations where remanufacturing short life cycle products is rewarding economically as well as environmentally. The system that we model consists of a retailer, a manufacturer, and a collector of used product from the end customers. Two different scenarios are evaluated for the system. The first is the independent situation where each party attempts to maximize his/her own total profit and the second is the joint profit model where we optimize the combined total profit for all three members of the supply chain. Manufacturer acts as the Stackelberg leader in the independently optimized scenario, while in the other the intermediate prices are determined by coordinated pricing policy. The results suggest that (i) reducing the price of new products during the decline phase does not give better profit for the whole system, (ii) the total profit obtained from optimizing each player is lower than the total profit of the integrated model, and (iii) speed of change in demand influences the robustness of the prices as well as the total profit gained.
Abstract. The Increased number of mobile phone users has an impact on increasing electronic waste... more Abstract. The Increased number of mobile phone users has an impact on increasing electronic waste (E-Waste) without being offset by the act of product recovery management. Remanufacturing is one way to overcome this. Remanufacturing is a process to return used products to general aesthetics and operating standards. This paper aims to design a mobile phone remanufacturing process in Indonesia. Indonesia is a developing country where the mobile usage is quite high. The mobile phones are chosen because it is one of the biggest e-waste takers of late. Several factories were visited in this study. This research uses a qualitative survey, which is carried out in mobile phone factories and service centers. From this research, a design has been made to remanufacture the process on mobile phones. The manufacturing plant verifies the design in order to obtain the input of the real constraints which will happen when the remanufacturing process is done. The steps in the process of remanufacturi...
Proceedings of the International Conference on Business and Engineering Management (ICONBEM 2021), 2021
Firms conduct activities to satisfy the need of their customers. However, some activities do not ... more Firms conduct activities to satisfy the need of their customers. However, some activities do not add value to customers. Authors propose some approaches to identify and reduce these wastes. By reducing waste, it is expected that the firm competitiveness will increase. One method to tackle waste is to use a failure mode and effect analysis (FMEA) approach. This study aims to modify the existing model to reduce waste on a make-to-order company. The authors propose criteria to assess the severity, occurrence, and detection of the 21 identified wastes. Using the waste priority numbers (WPN), these 21 wastes are classified into six high priority wastes, four medium priority wastes, and 11 low priority wastes. Countermeasures for the high priority and medium priority wastes are identified through a discussion with the company's management. The management evaluates how effective the countermeasures by using the same scoring scales for severity, occurrence, and detection. The proposed countermeasures can reduce the waste priority numbers significantly. From the assessment results, ten waste modes with high and medium priorities get good results because the average WPN values decreased from 125.9 to 26.8. The highest WPN value drops from 213 to 40. The highest CPN value also reduces from 445 to 110. The impact of the implemented countermeasures can be observed and get a positive response from the company's management.
Pelaksanaan tujuan proses magang di PT. X meliputi: tujuan umum dan tujuan khusus.Tujuan umum yai... more Pelaksanaan tujuan proses magang di PT. X meliputi: tujuan umum dan tujuan khusus.Tujuan umum yaitu melakukan pembaharuan modul pelatihan mekanik dengan menyesuaikan format dan penambahan troubleshooting yang ditentukan oleh PT. X. Selain itu, tujuan khusus dari pemagangan di PT.X ini ialah melakukan improvement pada nilai visual quality index (VQI). Fokus perbaikan dilakukan pada mesin 34 dengan menurunkan nilai VQI-NC loose end dari 6 point (data dari week 41 2017 – week 9 2018) menjadi 3 point. Perbaikan yang diselesaikan dilakukan dengan metode A3 diagram. Metode ini bertujuan untuk melihat dari penyebab, target, analisa mesin, implementasi perbaikan, standarisasi, dan melakukan training. Pencapaian setelah dilakukan perbaikan data yang diambil dari week 10 2018 – week 20 2018 nilai VQI-NC loose end turun menjadi 3 point. Hasil yang didapatkan setelah dilakukan perbaikan sesuai dengan target yang telah ditentukan. Sehingga dari hasil perbaikan tersebut dilakukan standarisasi dan...
Salah satu cara yang sering digunakan untuk meningkatkan jumlah produksi atau kecepatan produksi ... more Salah satu cara yang sering digunakan untuk meningkatkan jumlah produksi atau kecepatan produksi adalah dengan mengadopsi teknologi baru. Hal yang sama dilakukan oleh PT. Surabaya Wire yang memproduksi kawat bendrat. Perusahaan ini mengadopsi teknologi pressure die untuk menggantikan teknologi konvensional. Perbandingan yang dilakukan antara lain dalam hal kemampuan perpindahan panas, umur die, dan kapasitas produksi. Untuk mendukung perbandingan, data yang diambil adalah temperatur keluaran kawat, kecepatan penarikan kawat, data hasil produksi, dan downtime. Dari perbandingan yang dilakukan, hasil yang didapatkan dianalisis secara finansial untuk mengetahui apakah proyek ini menguntungkan atau tidak. Hasil analisis finansial menunjukkan peningkatan keuntungan sebesar 15% dari penggunaan pressure die dan didapatkan IRR sebesar 24% dan 113% untuk 2 asumsi keuntungan yang berbeda untuk tiap kg kawat yang diproduksi.
Jurnal Teknik Mesin Universitas Kristen Petra, Apr 1, 2000
Makalah ini membahas bagaimana memodelkan dan memvalidasi suatu sistem pengatur ketinggian air. S... more Makalah ini membahas bagaimana memodelkan dan memvalidasi suatu sistem pengatur ketinggian air. Sistem terdiri dari sebuah tangki tunggal, sensor ketinggian muka air, pompa, driver pompa dan elemen-elemen perubah ADC dan DAC. Pemodelan sistem keseluruhan disusun dari pemodelan elemen-elemen yang diturunkan secara emperik. Validasi atas pemodelam sistem ini dilakukan dengan cara membandingkan kurva respon dari model persamaan sistem secara keseluruhan dan kurva respon riel dari hasil pengukuran. Pemodelan sistem ini menunjukkan hasil yang cukup baik. Kata kunci : pemodelan, kontrol tinggi permukaan air, Algoritma PID, visualisasi.
Corrosion rate can be reduced by adding inhibitor and inhibition efficiency is a measure if its a... more Corrosion rate can be reduced by adding inhibitor and inhibition efficiency is a measure if its ability to suppress corrosion. The result of the immersion tests show that the inhibition efficiencies are different on each environment. Addition of 50 ppm of ascorbic acid results in the highest efficiency for NaC1 and CaCO3 environment while for Ca SO4 environment needs 100 ppm. Abstract in Bahasa Indonesia : Pemberian inhibitor dapat mengurangi laju korosi dan kemampuannya untuk menginhibisi diukur dari efisiensinya. Hasil penelitian menunjukkan bahwa efisiensi inhibisi berbeda-beda pada lingkungan yang berbeda. Penambahan inhibitor yang paling efisien untuk lingkungan NaCl dan CaCO3 dalah 50 ppm asam askorbat sedangkan untuk lingkungan CaSO4 adalah 100 ppm asam askorbat. Kata kunci : laju korosi, efisiensi inhibisi, asam askorbat.
Dimensi Utama Teknik Sipil
ABSTRACT: Property plays important role in economy business activities. In 2013 property grows by... more ABSTRACT: Property plays important role in economy business activities. In 2013 property grows by 800,000 units per year, while the supply capacity is only 300,000 units per year. This fact makes the property growth become more interesting. This growth is supported by the middle class growth that reaches 100 million people in 2013 and is estimated to be 141 million people in 2020. Previous research is done on one residential area. This research aims to develop a residential satisfaction measurement model of middle class residential customers in Surabaya-Sidoarjo. This study is different from the previous one in that this research conducts survey on 3 residential complexes and utilizes more comprehensive model. 226 respondents from 3 residential areas in Surabaya-Sidoarjo were collected. The implication of this study is to give the information about the variables that are significant, the level of satisfaction of the consumers on those variables, and improvement priority for develope...
Jurnal Teknik Mesin, 2021
Kendaraan bermotor sebagai alat transportasi saat ini menjadi salah satu kebutuhan penting untuk ... more Kendaraan bermotor sebagai alat transportasi saat ini menjadi salah satu kebutuhan penting untuk manusia. Jumlah sepeda motor terus meningkat setiap tahunnya. Hal ini menyebabkan sampah atau limbah berupa komponen yang telah rusak dari sebuah kendaraan juga terus meningkat. Saat ini, beberapa bentuk dari limbah tersebut dapat dilakukan recycle agar materialnya dapat dimanfaatkan kembali. Beberapa komponen yang telah rusak sebenarnya masih dapat digunakan lagi dengan beberapa proses seperti repair, refurbish atau remanufaktur. Proses remanufaktur adalah salah satu recovery option paling tinggi dalam mengolah limbah atau sampah. Dalam melakukan perancangan proses remanufaktur untuk komponen otomotif, perlu adanya pemilihan komponen yang akan dijadikan objek. Setelah pemilihan objek, maka dibuat serangkaian proses yang harus ada di dalam proses remanufaktur komponen otomotif seperti disassembly, cleaning, inspection, recondition, dan reassembly. Tahap akhirnya adalah membuat gambar ran...
Seminar Nasional Teknik Mesin IV: Study Kasus …
Jurnal Teknik Mesin, 2004
An academic directory and search engine.
fportfolio.petra.ac.id
PT X merasa perlu untuk mempertahankan keunggulannya sebagai produsen kemasan plastik yang bermut... more PT X merasa perlu untuk mempertahankan keunggulannya sebagai produsen kemasan plastik yang bermutu dan harganya bersaing. Namun hal ini tidak mudah tercapai. Kondisi yang saat ini perlu diperbaiki adalah sering terjadinya gangguan pada proses produksi. Pada ...
An academic directory and search engine.
Jurnal Teknik Mesin, 2004
fportfolio.petra.ac.id
Optimasi kualitas warna minyak goreng dilakukan dengan mengadakan eksperimen menggunakan sampel m... more Optimasi kualitas warna minyak goreng dilakukan dengan mengadakan eksperimen menggunakan sampel minyak goreng dengan berat 98 gram dan zat pemutih 2 gram, yang terdiri dari bleaching earth dan carbon active. Variabel yang mempengaruhi warna minyak goreng ada tiga, ...
Jurnal Teknik Mesin, 2004
In attempt to increase the quality of SR-24-type iron rods several constraints are often faced. O... more In attempt to increase the quality of SR-24-type iron rods several constraints are often faced. One of the problems is the high variability of yield strength quality characteristic. A research of influential factors and ideal composition of materials that can minimize quality variability is needed. To solve the above problem Taguchi method is used in designing the experiment. The superiority of this method is the ability to minimize variability of response and the efficiency of experiment. First steps that is taken is choosing control and noise factors and determining the levels. Then, the orthogonal matrix for experiment is built. Data analysis are done by optimizing signal-to-noise ratio, analysis of means, and analysis of variance. Result of analysis of SNR and mean give a conclusion that Carbon content of 0.1 %, Silicon content of 0.15 %, and Mangan content of 0.5 % are sufficient composition of additive material that will minimize variability level of yield strength. Abstract i...
E3S Web of Conferences, 2019
Electrical Discharge Machining (EDM) is one of the most common non-conventional machining process... more Electrical Discharge Machining (EDM) is one of the most common non-conventional machining processes used in the manufacturing of die and mold. In the process of EDM, practitioners usually face a problem, which is how to shorten process time and determine the point where the current should be changed so that the resulted surface roughness is not too high due to the use of large current at the beginning of the process. The purpose of this study is to determine the point when to change (reduce) the current in order to obtain the desired surface roughness and shortest processing time. From analysis of data, experiment was obtained some regression equations, those are: average surface roughness (Ra = 5424 + 0.698 I) which is used to find the final current to obtain the desired final surface roughness, peaks to valleys average roughness (Rz = 5.73 + 3.418 I) which is used to find the changing point for initial currentand duration of processing time (t =103.164 + 0.4714 I) which is used to...
Operations Research Perspectives, 2015
In this study we develop a model that optimizes the price for new and remanufactured short life-c... more In this study we develop a model that optimizes the price for new and remanufactured short life-cycle products where demands are time-dependent and price sensitive. While there has been very few published works that attempt to model remanufacturing decisions for products with short life cycle, we believe that there are many situations where remanufacturing short life cycle products is rewarding economically as well as environmentally. The system that we model consists of a retailer, a manufacturer, and a collector of used product from the end customers. Two different scenarios are evaluated for the system. The first is the independent situation where each party attempts to maximize his/her own total profit and the second is the joint profit model where we optimize the combined total profit for all three members of the supply chain. Manufacturer acts as the Stackelberg leader in the independently optimized scenario, while in the other the intermediate prices are determined by coordinated pricing policy. The results suggest that (i) reducing the price of new products during the decline phase does not give better profit for the whole system, (ii) the total profit obtained from optimizing each player is lower than the total profit of the integrated model, and (iii) speed of change in demand influences the robustness of the prices as well as the total profit gained.
Abstract. The Increased number of mobile phone users has an impact on increasing electronic waste... more Abstract. The Increased number of mobile phone users has an impact on increasing electronic waste (E-Waste) without being offset by the act of product recovery management. Remanufacturing is one way to overcome this. Remanufacturing is a process to return used products to general aesthetics and operating standards. This paper aims to design a mobile phone remanufacturing process in Indonesia. Indonesia is a developing country where the mobile usage is quite high. The mobile phones are chosen because it is one of the biggest e-waste takers of late. Several factories were visited in this study. This research uses a qualitative survey, which is carried out in mobile phone factories and service centers. From this research, a design has been made to remanufacture the process on mobile phones. The manufacturing plant verifies the design in order to obtain the input of the real constraints which will happen when the remanufacturing process is done. The steps in the process of remanufacturi...
Proceedings of the International Conference on Business and Engineering Management (ICONBEM 2021), 2021
Firms conduct activities to satisfy the need of their customers. However, some activities do not ... more Firms conduct activities to satisfy the need of their customers. However, some activities do not add value to customers. Authors propose some approaches to identify and reduce these wastes. By reducing waste, it is expected that the firm competitiveness will increase. One method to tackle waste is to use a failure mode and effect analysis (FMEA) approach. This study aims to modify the existing model to reduce waste on a make-to-order company. The authors propose criteria to assess the severity, occurrence, and detection of the 21 identified wastes. Using the waste priority numbers (WPN), these 21 wastes are classified into six high priority wastes, four medium priority wastes, and 11 low priority wastes. Countermeasures for the high priority and medium priority wastes are identified through a discussion with the company's management. The management evaluates how effective the countermeasures by using the same scoring scales for severity, occurrence, and detection. The proposed countermeasures can reduce the waste priority numbers significantly. From the assessment results, ten waste modes with high and medium priorities get good results because the average WPN values decreased from 125.9 to 26.8. The highest WPN value drops from 213 to 40. The highest CPN value also reduces from 445 to 110. The impact of the implemented countermeasures can be observed and get a positive response from the company's management.
Pelaksanaan tujuan proses magang di PT. X meliputi: tujuan umum dan tujuan khusus.Tujuan umum yai... more Pelaksanaan tujuan proses magang di PT. X meliputi: tujuan umum dan tujuan khusus.Tujuan umum yaitu melakukan pembaharuan modul pelatihan mekanik dengan menyesuaikan format dan penambahan troubleshooting yang ditentukan oleh PT. X. Selain itu, tujuan khusus dari pemagangan di PT.X ini ialah melakukan improvement pada nilai visual quality index (VQI). Fokus perbaikan dilakukan pada mesin 34 dengan menurunkan nilai VQI-NC loose end dari 6 point (data dari week 41 2017 – week 9 2018) menjadi 3 point. Perbaikan yang diselesaikan dilakukan dengan metode A3 diagram. Metode ini bertujuan untuk melihat dari penyebab, target, analisa mesin, implementasi perbaikan, standarisasi, dan melakukan training. Pencapaian setelah dilakukan perbaikan data yang diambil dari week 10 2018 – week 20 2018 nilai VQI-NC loose end turun menjadi 3 point. Hasil yang didapatkan setelah dilakukan perbaikan sesuai dengan target yang telah ditentukan. Sehingga dari hasil perbaikan tersebut dilakukan standarisasi dan...
Salah satu cara yang sering digunakan untuk meningkatkan jumlah produksi atau kecepatan produksi ... more Salah satu cara yang sering digunakan untuk meningkatkan jumlah produksi atau kecepatan produksi adalah dengan mengadopsi teknologi baru. Hal yang sama dilakukan oleh PT. Surabaya Wire yang memproduksi kawat bendrat. Perusahaan ini mengadopsi teknologi pressure die untuk menggantikan teknologi konvensional. Perbandingan yang dilakukan antara lain dalam hal kemampuan perpindahan panas, umur die, dan kapasitas produksi. Untuk mendukung perbandingan, data yang diambil adalah temperatur keluaran kawat, kecepatan penarikan kawat, data hasil produksi, dan downtime. Dari perbandingan yang dilakukan, hasil yang didapatkan dianalisis secara finansial untuk mengetahui apakah proyek ini menguntungkan atau tidak. Hasil analisis finansial menunjukkan peningkatan keuntungan sebesar 15% dari penggunaan pressure die dan didapatkan IRR sebesar 24% dan 113% untuk 2 asumsi keuntungan yang berbeda untuk tiap kg kawat yang diproduksi.