• 한국국방경영분석학회지
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• 제31권2호
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• pp.1-12
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• 2005

Defense firms' excess profitability by shifting common overhead costs from non-defense sector to defense sector in the award of cost reimbursement type of defense contracts is a widespread conclusion in prior researches. In this paper, we reviewed cost-shifting incentives in defense-contracting firms and extended the analysis of McGowan and Vendrzyk(2002) by applying modified model to Korea Defense Contracts. We formulated six hypotheses to test the relation of cost-shifting and excess profitability regarding market openness, auditing system, ranking in defense contracts, and firm types(sole defense contractors, sole non-defense contractors, and defense and non-defense mixed contractors). But, we could not find any evidence that defense firms shifted costs from non-defense sector to defense sector for the period 1997-2002. The results suggest that the excess profitability of Korea defense firms may not be from the cost-shifting but from other reasons.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제10권10호
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• pp.4681-4702
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• 2016

Recently, Massive energy consumption in Cloud Storage System has attracted great attention both in industry and research community. However, most of the solutions utilize single method to reduce the energy consumption only in one aspect. This paper proposed an energy effective gear-shifting mechanism (E2GSM) in Cloud Storage System to save energy consumption from multi-aspects. E2GSM is established on data classification mechanism and data replication management strategy. Data is classified according to its properties and then be placed into the corresponding zones through the data classification mechanism. Data replication management strategies determine the minimum replica number through a mathematical model and make decision on replica placement. Based on the above data classification mechanism and replica management strategies, the energy effective gear-shifting mechanism (E2GSM) can automatically gear-shifting among the nodes. Mathematical analytical model certificates our proposed E2GSM is energy effective. Simulation experiments based on Gridsim show that the proposed gear-shifting mechanism is cost effective. Compared to the other energy-saved mechanism, our E2GSM can save energy consumption substantially at the slight expense of performance loss while meeting the QoS of user.

• 자원ㆍ환경경제연구
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• 제33권2호
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• pp.113-133
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• 2024

태양광과 풍력을 중심으로 한 변동성 재생발전(VRE)은 탄소중립 달성의 주요수단이지만 높은 변동성과 불확실성으로 인해 전력공급의 안정성을 훼손시킨다. 에너지저장장치(ESS)는 수요이전을 통해 재생발전의 출력제한을 경감시킬 뿐만아니라 보조서비스 제공을 통해 안정적인 전력시스템 운영에 기여할 수 있다. 본 연구는 VRE로 인한 문제점이 점점 본격화되는 상황에서 ESS자원을 수요이전 기능과 예비력 제공기능 간에 어떻게 분배하는 것이 전력공급 효율성 최대화에 기여할 수 있는지 분석한다. 분석모형으로 재생발전의 변동성과 불확실성을 현실적으로 모의할 수 있는 확률적 전력시스템 최적화 모형을 적용하였다. 분석시점은 2023년과 2036년으로 설정하여 재생발전 보급수준별 ESS 최적자원분배 전략과 편익을 분석하였다. 분석결과는 크게 다음의 3가지로 요약가능하다. 첫째, ESS는 수요이전과 예비력 제공 모두에 탁월한 기능을 제공하며, 예비력 가격이 높게 설정될수록 수요이전 기능은 제한하고 예비력 제공에 집중함을 확인할 수 있었다. 둘째, 재생발전 출력제한은 필요예비력에 대한 대체재 역할을 하며, 예비력 가격 수준이 높아질수록 출력제한은 증가하고 필요예비력은 감소하는 것이 비용 합리적이다. 셋째, 기회비용이 반영된 합리적인 예비력 가격이 적용될 경우 ESS는 가까운 미래에 경제성을 확보할 수 있으며, ESS의 경제성은 재생발전 비중이 높을수록 더 커짐을 확인할 수 있었다. 본 연구는 전력공급 자원이 효율적으로 분배될 수 있는 가격기능이 바로 설때 비용 효율적인 전력부문 저탄소 전환이 가능함을 시사한다.

• 조명전기설비학회논문지
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• 제16권2호
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• pp.38-44
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• 2002

전력변환기와 같은 비선형 부하의 사용증가는 전력시스템에 고조파를 발생시킨다. 고조파를 포함하는 전류와 전압은 전기설비에 고장과 오동작을 일으키게된다. 위상조정 변압기는 고조파 발생원이 병렬로 설치되어 있는 곳에 설치하면 고조파 문제를 효과적으로 해결할 수 있다. 본 논문에서는 EDSA고조파 분석 프로그램을 사용하여 고조파를 제거하기 위한 위상조정 변압기의 효과를 분석하고 검증하였다.

• 전력전자학회논문지
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• 제19권5호
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• pp.470-474
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• 2014

This study proposes an improved synchronization control scheme for a low-cost 400Hz power supply for a no-break power transfer system. In the case of aircraft applications, the 400Hz power supply called ground power units is accepted and used as the external electrical power system during stopovers on ground. A momentary break in the supply occurs when shifting from one power source to another. To allow shifting without a break in the supply, the two power sources are momentarily connected in parallel. The proposed synchronization control is achieved by connecting an existing synchronization bus to the voltage zero-crossing signal of a generator power with discrete logic ICs and analog circuits. Therefore, unlike expensive controllers, such as DSP and CAN, the proposed control scheme is rather simple and may decrease operational cost. The practical feasibility of the proposed control scheme is proven by experimental results.

• 농촌계획
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• 제26권4호
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• pp.67-79
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• 2020

As globalization, international cooperation has grown in importance. In accordance with this trend, Korea has been receiving high demands from international organizations about expanding the scale of Official Development Assistance(ODA) in line with its improved national status. In addition, in the economic aspect of Korea, the ODA project is expected to provide new growth opportunities in the mid- to long-term by promoting cooperation with developing countries. Uganda is an area with high strategic value due to good agricultural conditions and favorable geographical conditions. The poultry industry is a business that is generally carried out to the Ugandan, but due to economic problems such as initial investment cost, most of them have raised poultry on a small scale which is not enough for main income. This paper proposes the construction and operation plan of adapting to small poultry farms in the village-intensive type to sustainable income for residents in Uganda through ODA project in Korea's agricultural technology. The economic feasibility was analyzed from the long-term perspective when the initial construction cost was supported or not and the poultry species ratio was adjusted in terms of initial and operating costs. Economic analysis was performed using Net Present Value(NPV) method. As of after 10 years, when operating in the form of shifting kuroiler to layers, it was estimated to earn about 700,000 ugx more than when only kuroiler is raised, and it is able to reduce about 14 million ugx from the initial cost than when only raising layers. As of 20 years, the most profitables scenario was the breeding of 100 kuroilers and 400 layers methods. however, this case was anlayzed to be unsuitable for Uganda farmers, with initial costs more than three times higher than the shifting method of the kuroiler to layers. If the initial construction cost is supported by ODA project, the initial investment cost can be recovered in the first year with the shifting method, whereas raising only layers take two years to recoup the cost. In the meantime, when studying livestock industry in Uganda, it was examined by relying on statistical data, but this paper is meaningful in that it predicted how much it is economically effective based on field experience.

• 한국정보디스플레이학회:학술대회논문집
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• 한국정보디스플레이학회 2006년도 6th International Meeting on Information Display
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• pp.1283-1286
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• 2006

A holding latch with level shifting function is proposed for power and cost effectiveness with low temperature polycrystalline silicon technology on the glass backplane. Layout area and power consumption of the proposed circuit are reduced by 10% and 52% compared with those of the typical structure which combines a static D-latch and a cross coupled level shifter for 2.2" qVGA panel, respectively.

• 한국BIM학회 논문집
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• 제7권3호
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• pp.40-48
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• 2017

It only takes one failed project to wipe out an entire year's profit, when the projects are not managed efficiently. Additionally, escalating costs of materials and a competitive local construction market make subcontractors a challenge. Subcontractors have finite resources that should be allocated simultaneously across many projects in a dynamic manner. Significant scheduling problems are posed by concurrent multi-projects with limited resources. The objective of this thesis is to identify the effect of productivity changes on the total cost resulting from shifting crews across projects using a descriptive model. To effectively achieve the objective, this study has developed a descriptive cost model for a subcontractor with multi-resources and multi-projects. The model was designed for a subcontractor to use as a decision-making tool for resources allocation and scheduling. The model identified several factors affecting productivity. Moreover, when the model was tested using hypothetical data, it produced some effective combinations of resource allocation with associated total costs. Furthermore, a subcontractor minimizes total costs by balancing overtime costs, tardiness penalties, and incentive bonus, while satisfying available processing time constraints.

• 제어로봇시스템학회논문지
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• 제14권3호
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• pp.301-306
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• 2008

Drivers are becoming more fatigued and uncomfortable with increase in traffic density, and this condition can lead to slower reaction time. Consequently, they may face the danger of traffic accidents due to their inability to cope with frequent gear shifting. To reduce this risk, some drivers prefer automatic transmission (AT) over manual transmission (MT). The AT offers more superior drivability and less shifting shock than the MT; therefore, the AT market share has been increasing. The AT is controlled by an electronic control unit (ECU), which provides better shifting performance. The transmission control unit (TCU) is a higher-value-added product, so the companies that have advanced technologies end to evade technology transfer. With more cars gradually using the ECU, the TCU is expected to be faster and more efficient for organic communication and arithmetic processing between the control systems than the l6-bit controller. In this paper, the model of an automatic transmission vehicle using MATLAB/Simulink is developed for the Hardware in-the-Loop (HIL) simulation with a 32-bit embedded system, and also the AT control logic for shifting is developed by using MATLAB/Simulink. The developed AT control logic, transformed automatically by real time workshop toolbox, is loaded to a 32-bit embedded system platform based on Freescale's MPC565. With both vehicle model and 32-bit embedded system platform, we make the HIL simulation system and HIL simulation of AT based on real time operating system (RTOS) is performed. According to the simulation results, the developed HIL simulator will be used for the performance test of embedded system for AT with low cost and effort.

• Industrial Engineering and Management Systems
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• 제11권2호
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• pp.170-175
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• 2012

In this paper, a procedure using a genetic algorithm (GA) and a heuristic local search (HLS) is proposed for solving facility rearrangement problem (FRP). FRP is a decision problem for stopping/running of facilities and integration of stopped facilities to running facilities to maximize the production capacity of running facilities under the cost constraint. FRP is formulated as an integer programming model for maximizing the total production capacity under the constraint of the total facility operating cost. In the cases of 90 percent of cost constraint and more than 20 facilities, the previous solving method was not effective. To find effective alternatives, this solving procedure using a GA and a HLS is developed. Stopping/running of facilities are searched by GA. The shifting the production operation of stopped facilities into running facilities is searched by HLS, and this local search is executed for one individual in this GA procedure. The effectiveness of the proposed procedure using a GA and HLS is demonstrated by numerical experiment.