• Journal of the Korea Society for Simulation
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• v.23 no.4
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• pp.51-64
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• 2014

Small and medium Enterprises (SMEs), which have a manufacturing method of small quantity batch production produce goods using a general-purpose equipment and attached auxiliary tools. Many previous studies have focused on finding the effective resource allocations for improving the firms' productivity. It is very important for SMEs to keep costs low in assigning jobs to each resource, because they should meet the future uncertain demand of consumers under the limited budget. Using the concept of salvage cost, this paper proposes how to effectively allocate the tasks to main resources in the production process. The salvage cost is defined that purchasing cost minus decrease in value by workload, the method considering this is expected to reduce total purchasing costs during business period. To validate the effect of the proposed method, we proceed the real case study targeting on S company, PCB manufacturer to compare purchase amounts and its costs between the allocation proposed based salvage cost and current allocation method of current S company. As a results, In short-term (3 year) business period, salvage allocation have remarkable superior outcome to existing method, but gradually have cancelled out the effects in long-term (8 year) plans. Unlike the cycle allocation method, there exists the idle-equipments in allocation based salvage value. we additionally analyze the profits with respect to rental strategy of them during business period.

• Journal of Korean Society of Forest Science
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• v.97 no.6
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• pp.641-649
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• 2008

This study was conducted to evaluate the productivity and the operational costs of the Chuncheon Tower-yarder, a skyline yarding system used in Korea. Detailed time study data were collected from 4 thinning sites in Japanese larch (Larix leptolepis) stands; one site for uphill yarding and three sites for downhill yarding. This study derived regression models to estimate the average cycle time (sec.) for uphill and downhill yarding. The average yarding cost was $12,844won/m^3$ for uphill yarding, while downhill yarding cost was $13,221won/m^3$. The average yarding time was 239 sec/cycle for uphill yarding, while downhill average yarding time was 274 sec/cycle. We found that uphill yarding productivity was higher when the operation system was examined under the same work conditions (i.e. standardized comparison) except yarding directions for both uphill yarding and downhill yarding.

• Asia-Pacific Journal of Business Venturing and Entrepreneurship
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• v.14 no.3
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• pp.185-199
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• 2019

Korea's facility horticulture has developed remarkably in a short period of time. However, in order to secure international competitiveness in response to unfavorable surrounding conditions such as high operating costs and market opening, it is necessary to diagnose the problems of facility horticulture and prepare countermeasures through analysis. The purpose of this study was to analyze the case of leading farmers by introducing information and communication technology (ICT) in hydroponic cultivation agriculture and horticulture, and to examine how agricultural technology utilizing smart farm and big data of facility horticulture contribute to farm productivity. Crop growth information gathering and analysis solutions were developed to analyze the productivity change factors calculated from hydroponics tomato farms and strawberry farms. The results of this study are as follows. The application range of the leaf temperature was verified to be variously utilized such as house ventilation in the facility, opening and closing of the insulation curtain, and determination of the initial watering point and the ending time point. Second, it is necessary to utilize water content information of crop growth. It was confirmed that the crop growth rate information can confirm whether the present state of crops is nutrition or reproduction, and can control the water content artificially according to photosynthesis ability. Third, utilize EC and pH information of crops. Depending on the crop, EC values should be different according to climatic conditions. It was confirmed that the current state of the crops can be confirmed by comparing EC and pH, which are measured from the supplied EC, pH and draining. Based on the results of this study, it can be confirmed that the productivity of smart farm can be affected by how to use the information of measurement growth.

• Journal of Bio-Environment Control
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• v.33 no.1
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• pp.37-44
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• 2024

This study was conducted to validate the growth and productivity of cucumber hydroponics using coir as the medium, different types of nutrient solutions and formal methods, in order to select the most efficient cultivation method. The nutrient solutions consisted of culture solution (S) and raw water (W), the planting methods were rockwool cube seedlings (RC), rockwool plug seedlings (RP), and slab directly seedlings (DS). The reference date was set the sowing date. The initial growth showed a significant increase in the culture solution treatment, the differences among treatments decreased as the growth period lengthened. There was no apparent correlation between the planting methods and growth, but different results were observed among the same planting methods depending on nutrient solution used. Similarly, productivity followed a similar trend, with significantly higher harvest in the culture solution treatment during the initial harvest period of 6-8 weeks after sowing, but the harvest gap among treatments were diminished in the after period. The cumulative harvest was significantly higher in the culture solution treatment due to the initial difference in harvest quantity. Plant growth and fruit productivity exhibited a similar trend, showing a linear relationship. There was no correlation among the planting methods, but direct seedling with the culture solution showed the highest initial growth and harvests due to stable nutrient and moisture supply in the initial root zone. Therefore, it is believed that direct seeding method on the culture solution medium would be most advantageous for plant growth and productivity. Additionally, it is expected to contribute to cost effectiveness from an economic perspective through simplification of the cultivation process, labor costs and production cost reduction

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.21 no.6
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• pp.225-229
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• 2011

Most of the silicon cutting methods using the multi-wire with the slurry injection have been used for wafers of the crystalline solar cell. But the productivity of slurry injection cutting type falls due to low cutting speeds. Also, the direct contact with the metal wire and silicon block increases the concentration of metallic impurities in the wafer's surface. In addition, the abrasive silicon carbide (SiC) generates pollutants. And production costs are rising because it does not re-use the worn wire. On the other hand, the productivity of the cutting method using the diamond coated wire is about 2 times faster than the slurry injection cutting type. Also, the continuous cutting using the used wire of low wear is possible. And this is a big advantage for reduced production costs. Therefore, the cutting method of the diamond coated wire is more efficient than the slurry injection cutting technique. In this study, each cutting type is analyzed using the surface characteristics of the solar wafer and will describe the effects of the manufacturing process of the solar cell. Finally, we will suggest improvement methods of the solar cell process for using the diamond cutting type wafer.

• Asian Pacific Journal of Cancer Prevention
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• v.14 no.4
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• pp.2533-2540
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• 2013

Background: Although screening is necessary where gastric cancer is particularly common in Asia, the performance outcomes of mass screening programs have remained unclear. This study was conducted to evaluate cost-effectiveness outcomes of the national cancer screening program (NCSP) for gastric cancer in South Korea. Materials and Methods: People aged 40 years or over during 2002-2003 (baseline) were the target population. Screening recipients and patients diagnosed with gastric cancers were identified using the NCSP and Korea Central Cancer Registry databases. Clinical outcomes were measured in terms of mortality and life-years saved (LYS) of gastric cancer patients during 7 years based on merged data from the Korean National Health Insurance Corporation and National Statistical Office. We considered direct, indirect, and productivity-loss costs associated with screening attendance. Incremental cost-effectiveness ratio (ICER) estimates were produced according to screening method, sex, and age group compared to non-screening. Results: The age-adjusted ICER for survival was 260,201,000-371,011,000 Korean Won (KW; 1USD=1,088 KW) for the upper-gastrointestinal (UGI) tract over non-screening. Endoscopy ICERs were lower (119,099,000-178,700,000 KW/survival) than UGI. To increase 1 life-year, additional costs of approximately 14,466,000-15,014,000 KW and 8,817,000-9,755,000 KW were required for UGI and endoscopy, respectively. Endoscopy was the most cost-effective strategy for males and females. With regard to sensitivity analyses varying based on the upper age limit, endoscopy NCSP was dominant for both males and females. For males, an upper limit of age 75 or 80 years could be considered. ICER estimates for LYS indicate that the gastric cancer screening program in Korea is cost-effective. Conclusion: Endoscopy should be recommended as a first-line method in Korea because it is beneficial among the Korean population.

• IE interfaces
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• v.17 no.4
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• pp.397-406
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• 2004

It is widely known that labor costs are continuously and rapidly growing in terms of the raw cost of products in Korea. The increased labor costs are degrading the competitiveness of dairy industry sector as in the other major industrial fields. Furthermore, the number of dairy farms is constantly decreasing while that of dairy cattle is increasing. Thus, mechanized and/or automated stockbreeding management systems are crucially required to support professional stockbreeding management, as well as to enhance the productivity of the sector. Hence this paper develops an IIS (Integrated Information System) for dairy cattle stockbreeding management. IIS is composed of five application modules and associated utility programs. The five modules are individual stock management, milking management, feeding management, propagation management, and disease management. The utility programs are involved in stock farm accounting, and handy unloading of individual stock data into a personal data acquisition device. Compared with existing foreign products, the developed system takes advantages of various stock body measurement data such as body weight, body temperature, milk conductivity, milking amount, and the number of walking steps. All the measured data are transmitted into a programmable logic controller that monitors and controls measurement devices. The transmitted data are finally aggregated into an integrated database located in the main personal computer. The integrated data are analyzed and reformed in the five modules of IIS, then, used for providing farmers with various farm states and information through application module scenes. Hence, IIS keeps the each module work in a systematic and compatible manner, while supervising the whole stockbreeding management system.

• Current Photovoltaic Research
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• v.4 no.3
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• pp.124-129
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• 2016

Recently industry has voiced a need for optimally designing the production process of low-cost, high-quality ingots by improving productivity and reducing production costs with the Czochralski process. Crystalline defect control is important for the production of high-quality ingots. Also oxygen is one of the most important impurities that influence crystalline defects in single crystals. Oxygen is dissolved into the silicon melt from the silica crucible and incorporated into the crystalline a far larger amount than other additives or impurities. Then it is eluted during the cooling process, there by causing various defect. Excessive quantities of oxygen degrade the quality of silicone. However an appropriate amount of oxygen can be beneficial. because it eliminates metallic impurities within the silicone. Therefore, when growing crystals, an attempt should be made not to eliminate oxygen, but to uniformly maintain its concentration. Thus, the control of oxygen concentration is essential for crystalline growth. At present, the control of oxygen concentration is actively being studied based on the interdependence of various factors such as crystal rotation, crucible rotation, argon flow, pressure, magnet position and magnetic strength. However for methods using a magnetic field, the initial investment and operating costs of the equipment affect the wafer pricing. Hence in this study simulations were performed with the purpose of producing low-cost, high-quality ingots through the development of a process to optimize oxygen concentration without the use of magnets and through the following. a process appropriate to the defect-free range was determined by regulating the pulling rate of the crystals.

• Clean Technology
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• v.12 no.3
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• pp.182-189
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• 2006

In this study, high speed machining is evaluated with regard to economical and environmental effects. Considering environmental loads, machining costs are analyzed with the mathematical models of machining economics and cutting fluid loss. Data from the tool life experiments of high speed milling and turning are used for the analysis. The analysis of high speed milling shows that the machining cost decreases as increasing the cutting speed. In turning process, the cooling method using cutting fluid shows the minimum machining cost. Considering both machining and environmental costs, cooling method using cold air is superior to other methods.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.39 no.1
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• pp.73-80
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• 2016

This study focuses on the formation of input release lots in a semiconductor wafer fabrication facility. After the order-lot pegging process assigns lots in the fab to orders and calculates the required quantity of wafers for each product type to meet customers' orders, the decisions on the formation of input release lots should be made to minimize the production costs of the release lots. Since the number of lots being processed in the wafer fab directly is related to the productivity of the wafer fab, the input lot formation is crucial process to reduce the production costs as well as to improve the efficiency of the wafer fab. Here, the input lot formation occurs before every shift begins in the semiconductor wafer fab. When input quantities (of wafers) for product types are given from results of the order-lot pegging process, lots to be released into the wafer fab should be formed satisfying the lot size requirements. Here, the production cost of a homogeneous lot of the same type of product is less than that of a heterogeneous lot that will be split into the number of lots according to their product types after passing the branch point during the wafer fabrication process. Also, more production cost occurs if a lot becomes more heterogeneous. We developed a multi-dimensional dynamic programming algorithm for the input lot formation problem and showed how to apply the algorithm to solve the problem optimally with an example problem instance. It is necessary to reduce the number of states at each stage in the DP algorithm for practical use. Also, we can apply the proposed DP algorithm together with lot release rules such as CONWIP and UNIFORM.