• 대한산업공학회지
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• 제35권1호
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• pp.58-72
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• 2009

The main activities of container terminals are to load container freights to vessels, discharge them from vessels, and store them in the storage yard. Container terminals make many operational plans to execute these functions effectively. If the plans do not consider enough the loads of related resources, they may have low actualities. This study discusses the optimal yard planning model which considers various resources, such as the storage yard, yard cranes, internal vehicles, and travel lanes, in container terminals. The model determines the groups and amounts of containers which are stored in each storage block by using the resource profile. The yard planning problem is represented to the multi-commodity minimal cost flow problem and is formulated to the linear programming model. In order to explain the application of the mathematical model, the numerical examples are presented. Additionally, the relationship between the average load ratio and the relocation ratio is discussed.

• Asian-Australasian Journal of Animal Sciences
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• 제24권4호
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• pp.532-539
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• 2011

The objective of this study was to determine age-related changes in the percentage content of edible and non-edible components in broiler chickens. The experimental materials comprised 240 Ross 308 chicks (sex ratio 1:1) raised to 10 weeks of age and fed standard diets ad libitum. Starting from the first week of rearing, every 7 days 10 males and 10 females were selected randomly for slaughter and post-slaughter analysis. The data obtained were verified statistically. The percentage content of edible components increased and the percentage content of non-edible parts decreased as the chicks grew older. In broilers aged 1 week and 10 weeks, edible components accounted for 47.0% and 66.4% total body weight, respectively. The share of muscle tissue increased considerably over this period, from 30.9% total body weight in week 1 to 52.4% in week 10. An increase in the percentage of skin and subcutaneous fat was observed for the first three weeks only, while the percentage content of giblets (in contrast to the remaining edible parts) decreased with age. For non-edible parts, the share of bones diminished by 2.5% and the proportion of slaughter offal reduced by 13.8%. A rising tendency was noted with respect to feathers and abdominal fat, while the content of the remaining offal decreased.

• 대한기계학회논문집
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• 제16권1호
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• pp.175-179
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• 1992

본 연구에서는 LPG 기관을 천연가스 이용기관으로 변경하고자 할 때 발생하는 출력 감소를 보안하기 우하여, 공기연료 혼합비 조절, 점화시기조절, 과급효과 방법에 의한 출력향상 효과를 파악하였다.

• 한국환경과학회지
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• 제14권1호
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• pp.15-22
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• 2005

Natural gas possesses several characteristics that make it desirable as an engine fuel; 1)lower production cost, 2)abundant commodity and 3)cleaner energy source than gasoline. Due to the physics characteristics of natural gas, the volumetric efficiency and flame speed of a natural gas engine are lower than those of a gasoline engine, which results in a power loss of $10-20{\%}$ when compared to a normal gasoline engine. This paper describes the results of a research to improve the performance of a natural gas engine through the modification and controls of compression ratio, air/fuel ratio, spark advance and supercharging and method of measuring flame propagation velocity. It emphasizes how to improve the power characteristics of a natural gas engine. Combustion characteristics are also studied using an ion probe. The ion probe is applied to measure flame speed of gasoline and methane fuels to confirm the performance improvement of natural gas engine combustion characteristics.

• 한국경영과학회지
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• 제22권2호
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• pp.13-29
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• 1997

This paper considers a new routing problem, successive max-min connection ratio problem (SMCRP), arised in circuit telecommunication networks such as SONET and WDM optical transport network. An optimization model for SMCRP is established based on link-flow formulation. It's first optimization process is an integral version of maximum concurrent flow problem. Integer condition does not give the same connection-ratio of each node-pair at an optimal solution any more. It is also an integral multi-commodity flow problem with fairness restriction. In order to guarantee fairness to every node-pair the minimum of connection ratios to demand is maximized. NP- hardness of SMCRP is proved and a heuristic algorithm with polynomial-time bound is developed for the problem. Augmenting path and rerouting flow are used for the algorithm. The heuristic algorithm is implemented and tested for networks of different sizes. The results are compared with those given by GAMS/OSL, a popular commercial solver for integer programming problem.n among ferrite-pearlite matrix, the increase in spheroidal ratio with increasing fatigue limitation, 90% had the highest, 14.3% increasing more then 70%, distribution range of fatigue.
ife was small in same stress level. (2) $\sqrt{area}_{max}$ of graphite can be used to predict fatigue limit of Ductile Cast Iron. The Statistical distribution of extreme values of $\sqrt{area}_{max}$ may be used as a guideline for the control of inclusion size in the steelmaking.

• 한국약용작물학회지
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• 제6권3호
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• pp.198-203
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• 1998

작약 분주묘의 크기에 따른 생육과 품질을 조사하여 재배법 개선의 기초자료로 활용코자 1994년 10월부터 3개년간 의성에서 의성작약을 공시하여 수행한 시험 연구 결과는 다음과 같다. 1. 작약의 분주묘 크기가 클수록 출현을 및 활착율은 높은 경향이 었으며 지상부 생육도 양호하었다. 2. 소묘$(30{\sim}50g)$재배의 지하부 수량은 1,921kg/10a이었으나 중묘$(60{\sim}80g)$는 2,304kg, 대 묘$(60{\sim}80g)$는 2,674kg으로서 각각 30%, 39% 증수되어 재식종묘 크기가 클수록 증수 되었다. 3. 분주묘 크기별 뿌리 굵기 10mm이상의 상품량은 소묘재배가 1,406kg/10a인데 비하여 중묘는 1,554kg/10a, 대묘는 1,769kg/10a으로 중묘와 대묘 재배시 상품율은 각각 11%, 26%높았다. 4. 분주묘 크기별 소득은 소묘가 1,133천원/10a인 데 비하여 중묘나 대묘는 각각 28%, 48% 증가 되었고 노두 생산량도 분주묘가 클수록 증수되었다.

• Journal of Plant Biotechnology
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• 제36권4호
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• pp.301-308
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• 2009

Higher agricultural commodity prices are a particular concern for food importing countries like Korea that has a very low self-sufficiency ratio. Korean people eat approximately 4.5 million metric tons of rice each year, which is met without a problem by domestic production. The domestic production of corn and soybean which are important raw materials for commercial food processing and livestock feed is only minimal. Demands of corn and soybean in Korea are approximately 7.2 million and 1.3 million metric tons per year, respectively. Since Korean consumers are reluctant to accept biotech (GM) foods, Korean food processors are fighting an up-hill battle in purchasing non-biotech (non- GM) crops which are becoming scarce.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2008년도 추계학술대회A
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• pp.1563-1565
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• 2008

Hydrophobic plastic plates employing nano surface features are injection molded using thermoplastic materials. A variotherm molding process is devised for filling the nano pores and releasing the molded nano features from the master. The size of the molded nano surface features are about 100nm in diameter and 200nm in height. The size of the molded plate is about 30mm x 30mm and the thickness is 1mm. As molding materials, Polypropylene, PMMA, COC and PC are employed, which are all typical commodity thermoplastic materials. The mold temperature(stamper temperature) is investigated as a major processing parameter for molding high aspect ratio nano surface features. Almost fully molded nano features are fabricated above a certain level of mold temperature depends on the employing material. The contact angles on the injection molded plates are measured to estimate the hydrophobicity and found to have higher contact angle up to 180% compared to the blank plate with no surface features.

• 한국지열·수열에너지학회논문집
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• 제13권3호
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• pp.16-22
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• 2017

It has become important for unutilized energy to be used for air conditioning of building. Economic evaluation on energy system by using treated sewage water as heat source, which is one of unutilized energy, was performed. The floor area of the subject building and the distance between heat source equipment and sewage treatment plant was assumed $30,000m^2$ and 200m. Absorption chiller-heater system was used for comparing to the energy efficient system, and payback period method was applied to carry out economic evaluation. Although the operating cost of this system is reduced compared to general heat source system, the ratio is not meaningful compared to the initial investment cost increase, and payback period was calculated to be about 36.1 years. However, when calculated based on the 2014 rate of electricity and city gas, it will be greatly reduced to 3.1 years. International commodity prices are constantly changing, and therefore national policy on the spread of unutilized energy should be maintained.

• Human Ecology Research
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• 제53권3호
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• pp.309-318
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• 2015

This study investigates to investigate the ageing effect on household demand for clothing, food, housing and medical care commodities in Korea using a demand system model. The cross-sectional and time-series data from Statistics Korea on urban household expenditures and age projection analyzed household demands of consumption commodities. The household head age and elderly population ratio were employed for proxy variables of ageing. Ageing variable elasticities of commodity demands were estimated. Study results show that ageing variables significantly influenced on a household demand for commodities; clothing and food consumption decreases; however, housing and medical care consumption increases with ageing. The elasticities of total consumption expenditures and price variables were estimated in the demand analysis; these two variables significantly impacted almost all of the household consumption for the studied commodities. This study provides an opportunity to examine how ageing influences household consumption for clothing, food, housing and medical care commodities as Korean society experiences a rapid ageing. It is also meaningful that this study conducted a quantitative measuring of the household demands for commodities that was different from past research on the household consumption expenditures for commodities.