In-bok Lee - Academia.edu (original) (raw)

Papers by In-bok Lee

Journal of Animal Environmental Science

Life Cycle Assessment (LCA) has been used to assess the environmental impact of livestock industr... more Life Cycle Assessment (LCA) has been used to assess the environmental impact of livestock industries since it was adopted as a standard method in 2006. However, many studies have simplified the environmental assessment factor for a simple assessment. Simplified LCA cannot be used in business/policy decisions because results can be overestimated and underestimated, ignoring interactions between environmental assessment elements. Therefore, it is necessary to review literatures that apply evaluation methods that take into account various environmental assessment factors. In this study, we selected and reviewed literatures on livestock-related LCA studies over the past five years. Environmental assessment factors by literature were considered and classified. Finally, we evaluated the applicability of comprehensive LCA research in the domestic livestock industry through a literature containing a number of factors.

Agriculture

The internal rearing environment of livestock houses has become an important issue in the last fe... more The internal rearing environment of livestock houses has become an important issue in the last few years due to the rapid increase in meat consumption. As the number of days of heat waves increase continuously, problems caused by abnormal weather changes steadily occurred. Thus, the main goal of this study is to develop a technology that can automatically calculate heat stress for livestock by considering weather forecast data. Specifically, a web-based heat stress forecasting system for the evaluation of heat stress in broilers was developed. The field experiments were carried out at the selected broiler house to measure and analyze the external weather, the internal environment, and the ventilation flow rate of fans used in tunnel ventilation. The developed model was validated by comparing the field and simulated thermal environment values. Based on a reliable model, Land-Atmosphere Modeling Package (LAMP) weather forecast data was used to show the stress index on the internal rea...

When livestock facilities in Korea have been changed larger and denser, rearing conditions have b... more When livestock facilities in Korea have been changed larger and denser, rearing conditions have been getting worse and the productivity of animal production have been decreased. Especially in the cold season, the minimized ventilation has generally been operated to save energy cost in Korea resulting in very poor environmental condition and high mortality. While the stability, suitability, and uniformity of the rearing condition are the most important for high productivity, the ventilation configuration is the most important to improve the rearing condition seasonally. But, it is so difficult to analyze the internal air flow and the environmental factors by conducting only field experiment because the weather condition is very unpredictable and unstable as well as the structural specification can not be easily changed by the researchers considering cost and labor. Accordingly, an aerodynamic computer simulation was adopted to this study to overcome the weakness of conducting field e...

Sustainability

This work aims at using the Computational Fluid Dynamic (CFD) approach to study the distributed m... more This work aims at using the Computational Fluid Dynamic (CFD) approach to study the distributed microclimate in the leaf boundary layer of greenhouse crops. Understanding the interactions in this microclimate of this natural habitat of plant pests (i.e., boundary layer of leaves), is a prerequisite for their control through targeted climate management for sustainable greenhouse production. The temperature and humidity simulations, inside the greenhouse, were performed using CFD code which has been adapted to simulate the plant activity within each mesh in the crop canopy. The air temperature and air humidity profiles within the boundary layer of leaves were deduced from the local surrounding climate parameters, based on an analytical approach, encapsulated in a Used Defined Function (UDF), and dynamically linked to the CFD solver, a work that forms an innovative and original task. Thus, this model represents a new approach to investigate the microclimate in the boundary layer of lea...

Agronomy

To utilize the energy in the thermal effluent, many attempts have been made to use the thermal ef... more To utilize the energy in the thermal effluent, many attempts have been made to use the thermal effluent for agricultural facilities such as greenhouses. As the first step, it is important to estimate the energy loads of the greenhouse for deciding a suitable scale for the heating and cooling. Then, it is available to estimate the energy efficiency of the thermal effluent heat pump system installed in the greenhouse. Therefore, the main objectives of this study were to design and validate an energy model of the experimental greenhouse growing Irwin mangoes and to estimate the annual and maximum energy loads using building energy simulation (BES). Field experiments were conducted in a multi-span plastic-covered greenhouse growing Irwin mangoes to measure the internal environments of the greenhouse and crop characteristics. The energy exchange model of the greenhouse considering crop, cladding, heat pump was developed using BES. The BES model was validated using the data measured at fi...

International Journal of Agricultural and Biological Engineering, 2015

Greenhouse Building Energy Simulation (BES) models were developed to estimate the energy load usi... more Greenhouse Building Energy Simulation (BES) models were developed to estimate the energy load using TRNSYS (ver. 16, University of Wisconsin, USA), a commercial BES program. Validation was conducted based on data recorded during field experiments. The BES greenhouse modeling is reliable, as validation showed 5.2% and 5.5% compared with two field experiments, respectively. As the next step, the heating characteristics of the greenhouses were analyzed to predict the maximum and annual total heating loads based on the greenhouse types and target locations in the Republic of Korea using the validated greenhouse model. The BES-computed results indicated that the annual heating load was greatly affected by the local climate conditions of the target region. The annual heating load of greenhouses located in Chuncheon, the northernmost region, was 44.6% higher than greenhouses in Jeju, the southernmost area among the studied regions. The regression models for prediction of maximum heating lo...

The tracer gas method has an advantage that can estimate total and local ventilation rate by trac... more The tracer gas method has an advantage that can estimate total and local ventilation rate by tracing air flow. However, the field measurement using tracer gas has disadvantages such as danger, inefficiency, and high cost. Therefore, the aim of this study was to evaluate ventilation rate in pig house by using the thermal distribution data rather than tracer gas. Especially, LMA (Local Mean Age), which is an index based on the age of air theory, was used to evaluate the ventilation rate in pig house. Firstly, the field experiment was conducted to measure micro-climate inside pig house, such as the air temperature, CO2 concentration and wind velocity. And then, LMA was calculated based on the decay of CO2 concentration and air temperature, respectively. This study compared between LMA determined by CO2 concentration and air temperature; the average error and root mean square error were 3.76 s and 5.34 s. From these results, it was determined that thermal distribution data could be used for estimation of LMA. Finally, CFD (Computational fluid dynamic) model was validated using LMA and wind velocity. The mesh size was designed to be 0.1 m based on the grid independence test, and the Standard k-ω model was eventually chosen as the proper turbulence model. The developed CFD model was highly appropriate for evaluating the ventilation rate in pig house.

Jarq-japan Agricultural Research Quarterly, 2000

Natural ventilation system modifications were evaluated using a computational fluid dynamics (CFD... more Natural ventilation system modifications were evaluated using a computational fluid dynamics (CFD) numerical model (code: Fluent Version 4.5). Wind speed and direction, side vent opening size and location, roof vent opening type, and number of spans were examined in terms of ventilation rates and airflow distribution. For the side vent located at 2.5 m above the floor with a west wind of 2.5 m/s, 59% of the incoming air through the side vent was predicted to move out through the first roof vent opening without reaching distant areas in the greenhouse, resulting in high inside air temperatures. The air mainly moved in through the side vent and fourth roof vent openings for an cast wind of 0.5 m/s while the third and fourth roof openings were the only predicted inlets of airflow for an east wind of 2.5 m/s. The hinged open roof multi-span greenhouses were predicted to have significantly higher natural ventilation rates than the double polyethylene-covered multi-span greenhouses for al...

Biosystems Engineering, 2019

Due to the cold stress experienced by pigs, and the increased energy load during winters and the ... more Due to the cold stress experienced by pigs, and the increased energy load during winters and the changes from winter to spring and summer to autumn, it is difficult to provide sufficient ventilation in pig houses. These factors can result in a poor internal environment. Therefore, fundamental measures to increase the ventilation rate and a corresponding analysis of the effects were needed to improve internal rearing environment. Due to the characteristics of invisible air, it was difficult to analyse the aerodynamic characteristics inside a pig house by field experiment. Computational fluid dynamics (CFD) has been used to overcome such limitations for the last 30 years. In this study, environmental monitoring (air temperature, humidity, etc.) in a commercial pig house were conducted to identify environmental problems. After this, CFD validated models were designed and evaluated to find effective solutions, by changing the conditions of the pig house air inlets and outlets (air buffer space, inlet duct, and exhaust fan). Compared with the conventional ventilation system of the experimental pig house, adjusting the hole spacing of the inlet duct and installing a roofechimney exhaust fan did not significantly improve the rearing environment. However, when an air buffer space was installed just before the location of the inlet on the sidewall, the air temperature flowing through the air buffer space increased making it possible to supply more than twice the external air to the pig house, while maintaining the air temperature distribution at the height of the animal-occupied zone.

Journal of Biosystems Engineering, 2010

In order to optimize an agricultural tractor clutch mechanism system, its structural static and k... more In order to optimize an agricultural tractor clutch mechanism system, its structural static and kinematic mechanism were analyzed. The operating force of the mechanical tractor clutch system is currently not appropriate to drive comfortably. So it is needed to reduce the clutch operating force by applying advanced engineering design techniques. In the present study, an optimization technology is applied to the design of tractor clutch systems to reduce the operating force. As a result of the optimization using 2 link-angles and 1 link-length which are the main design variables of the clutch linkage system, the maximum pushing force of the maximum clutch pedal was found 182.8N, 14% decreased compared to the existing clutch system. The effectiveness of the optimum design is certified by menas of an experiment.

Protected horticulture and Plant Factory, 2016

Korean government has planned to increase the productivity of horticultural crops and to expand s... more Korean government has planned to increase the productivity of horticultural crops and to expand supply smart greenhouse for energy saving by modernization of horticultural facilities based on ICT in policy. However, the diversity and linkages of monitoring and control are significantly insufficient in the agricultural sector in the current situation. Therefore, development of a service system with smart-farm based on the internet of things(IoT) for intelligent systemization of all the process of agricultural production through remote control using complex algorithm for diverse monitoring and control is required. In this study, domestic and international research trend related to ICTbased horticultural facilities was briefly introduced and limits were analyzed in the domestic application of the advanced technology. Finally, future core technologies feasible to graft in agricultural field were reviewed.

Computers and Electronics in Agriculture, 2017

To study natural ventilation for agricultural buildings, OpenFOAM, an open source CFD code, enabl... more To study natural ventilation for agricultural buildings, OpenFOAM, an open source CFD code, enables to develop tools that automate complex simulation procedures for nonprofessional CFD users. Prior to developing such tools, this paper investigates the accuracy of simulated air velocity in three test buildings according to different mesh sizes and turbulence models. The computed results, that were obtained using 13 different mesh sizes and 4 different k-e turbulence models, were qualitatively and quantitatively compared to wind tunnel measurements by two validation metrics. The results showed that the smaller mesh size leads to slightly higher simulation accuracy, but an increase in the number of meshes above a certain level did not improve the simulation accuracy due to the problem of solution convergence. The mesh size larger than 0.25 m at building walls was appropriate for the standard k-e model and the RNG k-e model, while a small mesh size of 0.125 m was preferable for the low Re k-e model. The simulation results, especially obtained from the RNG k-e model, were highly influenced by whether the solution converged showing the relative error of on average 6.4% higher in the oscillatory solutions, while those from the low Re k-e model were more dependent on the mesh size.

Journal of The Korean Society of Agricultural Engineers, 2015

Recently, the Korean government announced a new development plan for a large-scale greenhouse com... more Recently, the Korean government announced a new development plan for a large-scale greenhouse complex in reclaimed lands. Wind environments of reclaimed land are entirely different from those of inland. Many standard books for ventilation design didn't include qualitative standard for natural ventilation. In this study, natural ventilation rates were analyzed to suggest standard for ventilation design of venlo type greenhouse built on reclaimed land. CFD (Computational Fluid Dynamics) simulation models were designed according to the number of spans, wind conditions and vent openings. The wind profile at a reclaimed land was designed using ESDU (Engineering Sciences Data Unit) code. Using the designed CFD simulation model, ventilation rates were computed using mass flow rate and tracer gas decay method. Additionally computed natural ventilation rates were evaluated by comparing with ventilation requirements. As a result of this study, ventilation rates were decreased with increasing of the number of spans. Ventilation rates were linearly increased with increasing of wind speed. When the wind speed was 1.0 m•s-1 , only side vent was open and wind direction was 45°, homogeneity of ventilation rate at 0∼1 m height is the worst. Finally, chart for computing natural ventilation rate was suggested. The chart was expected to be used for establishing standard of ventilation design.

Journal of The Korean Society of Agricultural Engineers, 2013

Recently, damage occurrence by wind erosion has been increasing in society. In times past, such p... more Recently, damage occurrence by wind erosion has been increasing in society. In times past, such problems only took place in desert area ; however, in recent years, the wind erosion problem is spreading out to agricultural land. Wind erosion in agricultural land can cause loss of loam soils, the disturbance of the photosynthesis of the crop fields and serious economic losses. To overcome the mentioned problems, installation of windbreak fence can be recommended which function as disturbing strong wind and wind erosion. However, there is still no proper guideline to install the windbreak fence and the installation used to rely on the intuition of the workers due to the lack of related studies. Therefore, this study measured the aerodynamic resistance of screens of the windbreak fence using the apparatus for testing screens. The apparatus for testing screens was designed to measure pressure loss around the screen. Measured pressure loss by wall friction compensated for pressure loss to calculate the aerodynamic resistance of screens. The result of pressure loss by regression analysis derived the aerodynamic coefficient of Darcy-Forchheimer equation and power law equation. The aerodynamic resistance was constant regardless of the overlapped shape when the screen was overlapped into several layers. Increasing the number of layers of the screen, internal resistance increased significantly more, and pressure loss caused by the screen also increased linearly when the wind speed was certain conditions, but permeability had no tendency. In the future, the results of this study will be applied to the computational fluid dynamics simulation. The simulation models will be also validated in advance by wind tunnel experiments. It will provide standard of a design for constructing windbreak fence.

Journal of The Korean Society of Agricultural Engineers, 2014

Pig chronic wasting disease, including porcine reproductive and respiratory syndrome (PRRS) and p... more Pig chronic wasting disease, including porcine reproductive and respiratory syndrome (PRRS) and postweaning multisystemic wasting syndrome (PMWS), have made a continuous economic damage in pig farms. Airborne spread of livestock viruses are an important spread factor which is difficult to analyze due to invisible airflow and limitation of measurement. The objective of this study is to analyze airborne disease spread between buildings in the experimental pig farm by means of field experiment and computational fluid dynamics (CFD). The field experiments were conducted to capture airborne virus using air sampler and teflon filter along multi points in the experimental pig farm. The samples were tested in terms of virus detection resulting in positive reaction for PRRS and PCV-2 viruses, which can be a firm evidence of airborne virus spread. The CFD simulation model was developed by considering complex topography, wind conditions, building arrangement, and ventilation systems and was used to analyze airborne virus spread according to different wind conditions. The CFD computed result showed a possibility of airborne virus spread via livestock aerosol from infected pig house to neighboring pig houses according to wind directions. The CFD simulation technique is expected to provide significant data for estimating and making a counterplan against airborne disease spread.

Bioproduction in East Asia: Technology Development & Opportunities, 2003

The aerodynamic study on ventilation of agricultural buildings has not been active because of dif... more The aerodynamic study on ventilation of agricultural buildings has not been active because of difficulties in conducting field experiment. An engineering approach like aerodynamic analysis should be performed to design and manage the system systematically and scientifically. Moreover, this technology can contribute greatly to the development of overall HVAC system of agricultural buildings suitable for seasonal climates of Korea. This paper introduces the newest scientific and engineering technologies of aerodynamics that can be used to improve or develop structural and ventilating designs. Typical technologies of aerodynamics are large-sized wind tunnel, particle image velocimetry (PIV) technology, and computational fluid dynamics (CFD).

10th International Livestock Environment Symposium (ILES X), 2018

Thermal stress of livestock has been issued due to recent climate change trends and this causes r... more Thermal stress of livestock has been issued due to recent climate change trends and this causes reproductive disorders, decreased feed consumption, immunosuppression, and increased mortality of animals. Concept of THI has been widely used to quantitatively evaluate the degree of thermal stress for animals, however use of this concept is restricted for animals living in the enclosed facilities such as mechanically ventilated broiler houses. In this study, time-based internal energy flow and variation trends of temperature and humidity were analyzed based on BES technique. Local weather data, insulation characteristics of building materials, heat and moisture generation rate from broilers according to age, algorithm of ventilation operation were adopted for boundary condition of the model to accurately compute THI values inside the mechanically ventilated broiler house. From the BES computation, excess frequency of THI threshold in Jeju city was highest on the assumption that air conditioning equipments were not installed. When general raising density (39 kg m-2) was adopted, total 2,191 hours were exceeded. Excess hours of THI threshold were strongly related to the cumulative air temperature (R 2 =0.87).

IEEE Access

A digital twin has recently received considerable attention in various industry domains. The digi... more A digital twin has recently received considerable attention in various industry domains. The digital twin replicates physical objects (e.g., people, objects, spaces, systems, and processes) in the real world into digital objects in the digital world. It also provides various simulations to solve problems in the real world or to improve situational operations. Therefore, the digital twin is a convergence of various technologies, such as advanced machine-learning algorithms, data analytics, super-resolution visualization and modeling, and simulation. Because the digital twin is a complicated technology, a step-by-step implementation that includes many technology elements should be considered to create a digital twin model. In this study, implementation layers are introduced to guide practical implementations of the digital twin. In addition, technology elements were suggested for the presented implementation layers. Because the suggested technology elements include clear technology definitions, various application domains (e.g., energy, transportation, logistics, environment, manufacturing, and smart cities) can easily utilize the introduced implementation layers and technology elements according to the intended purpose. Furthermore, this paper describes the evolution of digital twins. Digital twin technology has evolved continuously since 2002, when the digital twin concept was first introduced. In the described evolution levels, we show the future aspects of digital twin technology, according to the technological evolution direction. Therefore, the digital twin model can be efficiently created by considering the evolution direction and future aspects by using the suggested digital twin evolution levels. INDEX TERMS Digital twin, digital twin technology evolution, implementation layer, technology elements.

Computers and Electronics in Agriculture, 2022

• Aerodynamic environment in a fattening pig house simulated using CFD. • Three-dimensional image... more • Aerodynamic environment in a fattening pig house simulated using CFD. • Three-dimensional image models were developed for inputting in a virtual space. • A VR simulator was developed to visualise the aerodynamic environment in a fattening pig house. In this study, a virtual reality (VR) simulator to visualise the aerodynamic environment of a fattening pig house was developed as educational materials for farmers and consultants. The aerodynamic environments inside a fattening pig house were firstly analysed according to various environmental conditions using computational fluid dynamics (CFD). Using the validated CFD model (Kim et al., 2019), the aerodynamic environment inside the fattening pig house was analysed with 54 cases of environmental conditions in winter and 60 cases of environmental conditions in summer. And then, the VR simulator was developed by visualising the CFD-computed data of aerodynamic environments in virtual space. The three-dimensional fattening pig house models were designed following the CFD-computed cases, and the three-dimensional pig model was developed with real shape and texture. The virtual space was organized by arranging the three-dimensional image models of the fattening pig house and fattening pig. A C language-based code was also used to extract the CFD-computed results for developing visualisation of the aerodynamic environment inside the fattening pig house. Visualisation was realized using contour plot, two-dimensional vector flow, and smoke effect in the virtual space. In the case of the contour plot, a scalar of air temperature, relative humidity, and gas concentration were expressed using color on the active plane. A two-dimensional vector flow represented two-dimensional flows on the active plane. From streamline data, the smoke effect was developed to describe the airflow from the air inlet. In this study, a tablet-shaped user interface (UI) was created so that the user can directly select the desired cases. Through a performance test, the optimal number of frames was determined. Finally, the VR simulator was developed to effectively describe the aerodynamic environments inside the fattening pig house. [ FROM AUTHOR] Copyright of Computers & Electronics in Agriculture is the property of Elsevier B.V. and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full . (Copyright applies to all s.)