• 한국산학기술학회논문지
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• 제19권8호
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• pp.385-391
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• 2018

전복 양식은 산업 측면에서 단기간에 급성장을 이루어온 반면, 전복의 수급 및 가격 전망에 대한 연구는 많지 않은 편이다. 또한 연구를 통해 개발된 모형도 적합성과 예측력이 낮은 문제점을 안고 있다. 모형상의 문제 해결을 위해서는 전복 치패 입식량, 양성 물량, 출하량 간의 시차 및 연계성을 유지하면서 동시에 기대 가격 변동에 의해 치패가 입식되고, 양성되어 출하되는 생물학적 공급 모형을 구축할 필요가 있다. 본 연구에서는 전체적인 전복 수급전망 모형에서 핵심적인 부분인 전복의 양성 물량 결정 모형 설정을 위해 양성 물량에 영향을 미치는 주요 변수를 확인하고, 이들 변수와 양성 물량 간의 인과 관계를 검증하였다. 양성 물량에는 치패 입식량과 전복 산지 가격을 물미역 가격으로 나눈 전복 상대 가격이 큰 영향을 미치는 것으로 나타났다. 또한 설정된 모형의 적합성 판별을 위해 양성 물량의 실제 관측치와 추정치를 연도별로 비교한 결과 모형의 적합성이 높은 것으로 판명되었다.

• 산업공학
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• 제23권2호
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• pp.126-138
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• 2010

Marine equipment makers today face a multitude of challenges including the needs of an internal system for easy management of their business processes and a collaboration system to streamline communications with the parent company, increasing product complexity and heightened requirements for information technology. In this research, a BPM-ERP system called Biz $Tower^{(R)}$ was implemented based on cloud computing for especially, small and medium marine equipment makers to standardize and visualize the entire business process from order placement to release. This system also provides their parent company with visibility into the status of orders and user can easily access the system on the web at a low price through cloud computing service. Thus far, this paper demonstrates the applicability of Biz $Tower^{(R)}$ to improve management visibility, process performance, and collaboration with the parent company for small and medium marine equipment makers.

• 한국연소학회지
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• 제13권1호
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• pp.17-22
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• 2008

A partly implicit/quasi-explicit method is introduced for the solution of detailed chemical kinetics with stiff source terms based on the standard fourth-order Runge-Kutta scheme. Present method solves implicitly only the stiff reaction rate equations, whereas the others explicitly. The stiff equations are selected based on the survey of the chemical Jaconian matrix and its Eigenvalues. As an application of the present method constant pressure combustion was analyzed by a detailed mechanism of hydrogen-air combustion with NOx chemistry. The sensitivity analysis reveals that only the 4 species in NOx chemistry has strong stiffness and should be solved implicitly among the 13 species. The implicit solution of the 4 species successfully predicts the entire process with same accuracy and efficiency at half the price.

• Asian-Australasian Journal of Animal Sciences
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• 제12권7호
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• pp.1116-1122
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• 1999

Raising dairy cattle for milk production has been promoted and supported by the Thai government in recent years. The extent to which dairy farmers in southern Thailand use the practices recommended by government officers is not known and was investigated in this study. With dairy farming in southern Thailand mainly concentrated in the Phatthalung province, the entire population of dairy farmers in this province was studied. A total of 114 dairy farmers were studied by personal interviews. The results showed that the farmers varied widely in their use of the practices for dairy production in southern Thailand. The study identified that the major problems in dairy production in southern Thailand were low rates of conception to artificial insemination, the high price of feedstuffs and a shortage of roughage in the dry summer months.

• Journal of Biosystems Engineering
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• 제25권1호
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• pp.63-70
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• 2000

In Korea, researches for year-round leaf vegetables production system are in progress and the most of them are focused on environment control. Automation technologies for harvesting , transporting and grading need to be developed. This study was conducted to develop harvesting process automation system profitable to a competitive price. 1. Manipulator and end-effector are to be designed and fabricated , and fuzzy logic controller for controlling these are to be composed. 2. The entire system constructed is to be evaluated through a performance test. A robot system for harvesting a lettuce was developed. It was composed of a manipulator with 20DOF (degrees of freedom) an end-effector, a lettuce feeding conveyor , an air blower , a machine vision device, 6 photoelectric sensors and a fuzzy logic controller. A fuzzy logic control was applied to determined appropriate grip force on lettuce. Leaf area index and height index were used as input parameters, and voltage was used as output parameter for the fuzzy logic controller . Success rate of the lettuce harvesting system was 93.06% , and average harvesting time was about 5 seconds per lettuce.

• 한국시스템다이내믹스연구
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• 제11권3호
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• pp.61-86
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• 2010

This research analyzed on the future energy society of Korea in 2030 using system thinking approach. Key uncertainty factors determining the future energy society were analyzed in a multi disciplinary view point such as politics, economy, society, ecology and technology. Three causal loop diagrams for the future energy system in Korea and related policy leverages were shown as well. 'Global economic trends', 'change of industrial structure' and 'energy price' were identified as key uncertainty factors determining the Korean energy future. Three causal loop diagrams named as 'rate of energy self－sufficiency and alternative energy production', 'economic activity and energy demand' and 'Excavation of new growth engines' were developed. We integrated those causal loop diagrams into one to understand the entire energy system of the future, proposed three strategic scenarios(optimistic, pessimistic and most likely) and discussed implications and limits of this research.

• 제어로봇시스템학회논문지
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• 제12권12호
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• pp.1184-1190
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• 2006

Most chemical companies try to maximize their energy efficiencies due to high oil price and reinforcement of environmental regulation. An individual factory continuously has tried to reduce energy consumption or carbon dioxide discharge for high profit. Nevertheless, it is found that waste heat is disposed with forms of low or medium pressure steams. It can be improved by the aspect of entire industrial complex. Therefore, we have developed a steam network optimization method using Steam Networking Matrices(SNMs) in this research. Results from an illustrative example show that energy consumption can be reduced by optimizing steam exchange networks.

• Journal of Magnetics
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• 제22권1호
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• pp.14-22
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• 2017

The NMR's probe consists of the static magnetic field generator (magnetic source) and the RF coil. It is very strict for the homogeneity of the static magnetic field intensity of the magnetic source, so the cost of the magnetic source is more expensive in the entire nuclear magnetic resonance instrument. The magnetic source generally consists of electromagnet, permanent magnet and superconducting magnet. The permanent magnet basically needs not to spend on operation and maintenance and its cost of manufacture is much cheaper than the superconducting magnet. Therefore, the permanent magnet may be the only choice for the static magnetic field device if we want to use the magnetic resonance instrument as an analyzer for production by reducing price. A new probe magnet was developed on the basis of the permanent magnet ring in this paper to provide a technological way for reducing the manufacturing cost, weight and volume of the existing nuclear magnetic resonance instrument (including MRI) probe.

• Journal of Communications and Networks
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• 제18권4호
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• pp.658-669
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• 2016

The tremendous increase in mobile data traffic coupled with fierce competition in wireless industry brings about spectrum scarcity and bandwidth fragmentation. This inevitably results in asymmetric-valued long term evolution (LTE) spectrum allocation that stems from different timing for twice improvement in capacity between competing operators, given spectrum allocations today. This motivates us to study the economic effects of asymmetric-valued LTE spectrum allocation. In this paper, we formulate the interactions between operators and users as a hierarchical dynamic game framework, where two spiteful operators simultaneously make spectrum acquisition decisions in the upper-level first-price sealed-bid auction game, and dynamic pricing decisions in the lower-level differential game, taking into account user subscription dynamics. Using backward induction, we derive the equilibrium of the entire game under mild conditions. Through analytical and numerical results, we verify our studies by comparing the latest result of LTE spectrum auction in South Korea, which serves as the benchmark of asymmetric-valued LTE spectrum auction designs.

• 대한전기학회논문지:전력기술부문A
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• 제55권4호
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• pp.156-162
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• 2006

Transmission zones can be defined based on LMPs. Each zone consists of nodes with similar LMPs, and zonal price is determined by average nodal prices in each zone.[1] Network reduction is still important for the analysis of zonal systems under electricity market environments, even though the computing capability of computer system can deal with entire power systems. The Similarity Index is a good performance measure for the network reduction.[2] It can be applied to the network reduction between zones categorized by the nodal prices. This paper deals with a novel network reduction method between zones based on the similarity Index. Line admittances of reduced network were determined by using the least square method. The proposed method was verified by IEEE 39 bus test system.