• Journal of Wind Energy
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• v.13 no.4
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• pp.50-57
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• 2022

Renewable energy is emerging as a way for the government to carry out its 2030 carbon-neutral policy. In this regard, the demand for wind turbine generators for renewable energy is increasing. As a result of restrictions due to civil complaints, offshore wind power generators are actively being developed. At this time, offshore wind power generation has higher maintenance costs, material costs, and installation costs compared to onshore wind power generation. So, an economic evaluation that calculates imports and costs is an important task. The levelized cost of energy (LCOE) is an economic evaluation index used in the energy field. In this paper, based on AEP calculated by windpro, the LCOE calculated by the wind power cost estimation model published in the NREL Economic Analysis Report, installing one 15 MW unit and installing one 20 MW unit and seven units were reviewed and analyzed. As a result, AEP was calculated as 0.140($/Kwh) for the installation of a single 15 MW, 0.142($/Kwh) for the installation of a single 20 MW, and 0.119 ($/Kwh) for the installation of a 20 MW farm. Therefore, it was confirmed that the installation of the single 20 MW was more economical than the installation of the single 15 MW and the installation of the 20 MW farm was most economical.

• Korean Chemical Engineering Research
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• v.55 no.6
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• pp.762-766
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• 2017

Energy recovery device (ERD) is used to save energy consumption in seawater reverse osmosis processes. However, small-scale ERDs (<$100m^3/d$) are hardly observed in seawater desalination market. In South Korea, most of seawater desalination plants for drinking water production are small-scaled and have been operated in island areas or on ships. Thus, the effect of ERDs for these small-scale SWRO processes should not be neglected. In this work, the small-scale SWRO processes are designed and analyzed in terms of energy consumption with/without ERD. The realistic efficiencies of high pressure pumps are considered for the energy analyses. The unit cost of electricity depending on the application place (e.g., inland and island areas, on ships) is investigated to calculate the energy cost for unit water production in various SWRO applications classified by plant capacity, application place, and the installation of ERD. As a result, the energy cost can be saved up to $1,640.4KRW/m^3$ when ERD is applied, and the saving effect increases at smaller plants on ships. In conclusion, the development of small-scale ERDs are necessary because small-scale SWRO processes are dominant in Korean seawater desalination market, and the electricity saving effect becomes higher at smaller-scaled system.

• 제어로봇시스템학회:학술대회논문집
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• 2004.08a
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• pp.1859-1864
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• 2004

An effective methodology is reported for the optimal design of multisite batch production/transportation and storage networks under uncertain demand forecasting. We assume that any given storage unit can store one material type which can be purchased from suppliers, internally produced, internally consumed, transported to or from other plant sites and/or sold to customers. We further assume that a storage unit is connected to all processing and transportation stages that consume/produce or move the material to which that storage unit is dedicated. Each processing stage transforms a set of feedstock materials or intermediates into a set of products with constant conversion factors. A batch transportation process can transfer one material or multiple materials at once between plant sites. The objective for optimization is to minimize the probability averaged total cost composed of raw material procurement, processing setup, transportation setup and inventory holding costs as well as the capital costs of processing stages and storage units. A novel production and inventory analysis formulation, the PSW(Periodic Square Wave) model, provides useful expressions for the upper/lower bounds and average level of the storage inventory. The expressions for the Kuhn-Tucker conditions of the optimization problem can be reduced to two sub-problems. The first yields analytical solutions for determining lot sizes while the second is a separable concave minimization network flow subproblem whose solution yields the average material flow rates through the networks for the given demand forecast scenario. The result of this study will contribute to the optimal design and operation of large-scale supply chain system.

• Journal of Korean Institute of Industrial Engineers
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• v.39 no.5
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• pp.422-428
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• 2013

In many cases, an $\bar{X}$ control chart which is based on the performance variable is used in industrial fields. However, if the performance variable is too costly or impossible to measure and a less expensive surrogate variable is available, the process may be more efficiently controlled using surrogate variables. In this paper, we propose a model for the economic design of a VSI (Variable Sampling Interval) $\bar{X}$ control chart using a surrogate variable that is linearly correlated with the performance variable. The total average profit model is constructed, which involves the profit per cycle time, the cost of sampling and testing, the cost of detecting and eliminating an assignable cause, and the cost associated with production during out-of-control state. The VSI $\bar{X}$ control charts using surrogate variables are expected to be superior to the Shewhart FSI (Fixed Sampling Interval) $\bar{X}$ control charts using surrogate variables with respect to the expected profit per unit cycle time from economic viewpoint.

• Proceedings of the Korean Society of Crop Science Conference
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• 1999.11a
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• pp.102-144
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• 1999

The major problems of food crop cultivation in Korea are low yield of most crops except rice. inefficient cultivation techniques for aged farmers. and low international competibility. Therefore, development of cultivation techniques of food crops should aim the yield. quality improvement, labor reduction and production cost. The primary issue for increasing the yield of soybean, barely and wheat is to reduce the yield gap between the farmer's yield and recommended ones of experiment station. More advanced cultivation techniques needs to be developed. and/or the conventional breeding methods to be reconsidered. The newly developed labor-saving mechanized technique needs to reduce labor hours , and the cost of agricultural implements and machineries. In other words the labor-saving mechanized technique should be developed based on the improvement of total farming system as well as systemic fundamental innovation of cultural methods. The efficiency of solar energy use in food production of Korea in 1997 is as low as $0.52{\%}$ so there is much room to increase yield. It is recommendable that the concept of food Production should be changed to energy Producing efficiency Per unit area basis from volume and weight of food materials. Moreover, introduction of resonable cropping system is needed to increase yield of main crops, farmer's income, solar energy use efficiency, and decrease of land service expenditure. Current cropping system emphasized on economic crops. especially in vegetables , is not desirable for resonable use of arable land. stability of agricultural management and staple food crop self-sufficiency ratio. It is desirable to increase food crops . that are energy of carbohydrate and protein rich and land dependent crops. in cropping system. And the agronomist should develop the cultural methods to replace food crops for food self-sufficiency and stable farming management instead of economic crops in current cropping system. Low-input and environmentally-sound crop cultivation techniques, especially nitrogen-reducing culture technique which is directly related to food crop quality, also needs to be developed urgently. The extended cultivation of corn in upland and barely and wheat in lowland as a feed stuffs is recommended to prevent further decrease of food self-sufficiency ratio, which is mainly caused by the high reliance on imported feed grain. It is also considered that the calculation and presentation methods of standard agricultural income needs to be improved. The current calculation method uses unit land area of 10a regardless of crop kinds , characteristics of agricultural management and cultivation scale. So, it is apt to lead misunderstanding of farm income value. Therefore. it should show an income of average farmers for certain number of years. Research and developing system for food producing is not desirable because they are conducted currently individual crop and mono-culture basis. But actual agricultural income is usually earned by cropping system including upland and lowland. For example. the barley and wheat is usually cultivated in double cropping system. The cooperation among research institutes such as university agribusiness. government and farmers is indispensible. The public information and education on importance and consumption habit of food crops is necessary in Korean society to increase food self-sufficiency through nationwide cooperation.

• Asian-Australasian Journal of Animal Sciences
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• v.12 no.8
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• pp.1246-1250
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• 1999

Rabbits (48) of Soviet chinchilla (24) and White giant (24) were fed from 6 weeks to 12 weeks of age intensively on either of four isonitrogenous - isocaloric diets containing 0 ($D_1$), 5($D_2$), 10($D_3$) and 20($D_4$) percent raw neem seed kernel cake (NSKC), respectively as per NRC (1977) requirements in a Randomized block design and slaughtered at the end to find out differences in their carcass traits due to NSKC feeding. Dietary treatment had no significant effect on weight of edibles and inedibles and their percentages and dressing percentage in terms of carcass, carcass with pluck and carcass with pluck and head. Similarly, the meat-bone ratio of various primal cuts and overall carcass, yield of edibles per unit of inedibles and eye muscle area were not influenced due to the dietary variations. Chemical composition of fresh meat, and organoleptic evaluation of cooked meat with and without salt did not vary significantly due to incorporation of NSKC in the diets. The rabbits fed 20% NSKC ($D_4$) though consumed more (p<0.05) DM and DE per kg meat production, the intake of crude protein and total digestible nutrients was similar with other dietary treatments. Feed cost per unit meat production was, however, lower on 5 and 10% NSKC containing diets by 7.75 and 12.56%, respectively, as compared to deoiled ground nut cake containing control diet. It appears that NSKC could be used as a wholesome vegetable protein supplement upto 10% in diet of rabbits without any adverse effect on commercial carcass traits.

• Industrial Engineering and Management Systems
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• v.13 no.3
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• pp.304-318
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• 2014

It is necessary for a retailer to improve responsiveness to uncertain customer demand in product sales. In order to solve this problem, this paper discusses an optimal operation for a 2-stage-ordering-production system consisting of a retailer and a manufacturer. First, based on the demand information estimated at first order time $t_1$, the retailer determines the optimal initial order quantity $Q^*_1$, the optimal advertising cost $a^*_1$ and the optimal retail price $p^*_1$ of a single product at $t_1$, and then the manufacturer produces $Q^*_1$. Next, the retailer updates the demand information at second order time $t_2$. If the retailer finds that $Q^*_1$ dissatisfies the demand indicated by the demand information updated at $t_2$, the retailer determines the optimal second order quantity $Q^*_2$ under $Q^*_1$ and adjusts optimally the advertising cost and the retail price to $a^*_2$ and $p^*_2$ at $t_2$. Here, decision-making approaches for two situations are made-a decentralized supply chain (DSC) whose objective is to maximize the retailer's profit and an integrated supply chain (ISC) whose objective is to maximize the whole system's profit. In the numerical analysis, the results of the optimal decisions under DSC are compared with those under ISC. In addition, supply chain coordination is discussed to adjust the unit wholesale price at each order time as Nash Bargaining solutions.

• Journal of KIISE
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• v.43 no.9
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• pp.998-1007
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• 2016

In recent years, the cost of automotive ECU (Electronic Control Unit) has accounted for more than 30% of total car production cost. However, the complexity of testing and debugging an automotive ECU is increasing because automobile manufacturers outsource automotive ECU production. Therefore, a large amount of cost and time are spent to localize faults during testing an automotive ECU. In order to solve these problems, we propose a fault localization method in memory for developers who run the integration testing of automotive ECU. In this method, memory is partitioned by utilizing memory map, and fault-suspiciousness for each partition is calculated by utilizing memory update information. Then, the fault-suspicious region for partitions is decided based on calculated fault-suspiciousness. The preliminary result indicated that the proposed method reduced the fault-suspicious region to 15.01(%) of memory size.

• Korean Journal of Organic Agriculture
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• v.26 no.1
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• pp.99-128
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• 2018

The cultivation area of rice as staple grains is decreasing in the domestic situation in Korea. Import volume of a duty in foreign rice is 409,000 tons for a year regardless increasing of production per unit area and decreasing of rice consumption. The total stock of rice is increasing cumulatively despite the effort for production mediation of rice. Therefore, maintenance of cultivation area and reduction of production are necessary for national foodstuffs security problems. Development of environment-friendly and low-carbon technology as alternative of global warming and aging of farm labor power is very important responsibility for descendants with creation of sustainable agriculture environment. As alternative for demand and supply stabilization of rice from all angles, first stage: extension of environment-friendly cultivation area as 17% Jeollanam-do level with maintenance of cultivation area under the present circumstances, second stage: extension of environment-friendly cultivation area as 25%, third stage: extension of environment-friendly cultivation area as 35%. From above mentioned scenario, reduction of rice production (60,000 tons), increases of production cost (59,200,000,000 Won), and reduction of income (201,500,000,000 Won) are estimated in first stage. Reduction of rice production (90,000 tons), increases of production cost (122,100,000,000 Won), and reduction of income (313,700,000,000 Won) are estimated in second stage. Reduction of rice production (380,000 tons), increases of production cost (222,000,000,000 Won), and reduction of income (464,500,000,000 Won) are estimated in third stage. From analysis results for partial tillage in transplanting cultivation complex (10ha), rice production is decreased 1.3~1.5 ton by complex. Production cost of rice is decreased and increases of income cultivation type. Gradual extension of environment-friendly agriculture and low-carbon partial tillage could be expected for environment maintenance of the territorial integrity, confidence of consumer, and high-efficiency of low-cost.

• Industrial Engineering and Management Systems
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• v.6 no.1
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• pp.11-21
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• 2007

The PDCA (Plan, Do, Check and Act) cycle is often used in the field of quality management. Recently, business environments have become more competitive, and the due time of products has shortened. In a short production run process, to increase efficiency of management, the necessity for distinguishing the PDCA design that starts with PLAN and the CAPD design that starts with CHECK has been clarified. Starting from Duncan (1956), there have been a number of papers dealing with the economic design of control charts from the viewpoint of production run. Some authors (Gibra, 1971; Ladany and Bedi, 1976; etc.) have studied the economic design for finite-length runs; other authors (Crowder, 1992; Del Castillo and Montgomery, 1996; etc.) have studied the economic design for short runs. However, neither the PDCA nor the CAPD design of control charts has been considered. In this paper, both the PDCA and CAPD designs of the $\bar{\x}$ chart are defined based on Del Castillo and Montgomery's design (1996), and their mathematical formulations are shown. Then from an economic viewpoint, the optimal values of the sample size per each sampling, control limits width, and the sampling interval of the two designs are studied. Finally, by numerically analyzing the relations between the key parameters and the total expected cost per unit time, the comparisons between the two designs are considered in detail.