• 한국지능시스템학회:학술대회논문집
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• 한국퍼지및지능시스템학회 1998년도 The Third Asian Fuzzy Systems Symposium
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• pp.75-79
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• 1998

It is well known that traveling salesman problem (for short, TSP) is one of mot important problems for optimization, and almost all optimization problems result in TSP. This paper describes on an effective solution of TSP using genetic algorithm. The features of our method are summarized as follows : (1) By using division and unification method, a large problem is replaced with some small ones. (2) Smoothing method proposed in this paper enables us to obtain a fine approximate solution globally. Accordingly, demerits caused by division and unification method are decreased. (3) Parallel operation is available because all divided problems are independent of each other.

• 보건행정학회지
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• 제13권3호
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• pp.129-147
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• 2003

This study is to grasp a trend of profitability classified by characteristics of hospitals and to analyze related factors. Subjects are 145 hospitals which have gotten the standardization audit by Korean Hospital Association during 1998-200l. Profitability was measured in the aspect of operation profit rate with operating margin to gross revenue as proxy variables. Independent variables were classified by general factors (ownership, number of beds, period of establishment, competition), financial factors (liabilities to total assets, current ratio, fixed ratio, total asset turnover, inventories turnover), and factors related to patient treatment (average length of stay, bed occupancy rate, new outpatient ratio, admission ratio of outpatients, number of patients per specialist, personnel costs per adjusted inpatient, administrative costs per adjusted inpatient). Hierarchical multiple regression analysis model was used in this study. As a result of hierarchical multiple regression analyzation of operating margin to gross revenue, adjustive $R^2$ of general factors was relatively more powerful. The factors had significant effect on operating margin to gross revenue were ownership(+), number of beds(+), competition(+), current ratio(+), fixed ratio(+), total asset turnover(+), personnel costs per adjusted inpatient(-).

• 한국멀티미디어학회논문지
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• 제2권4호
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• pp.438-450
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• 1999

본 논문에서는 멀티미디어 데이터의 저작권 보호를 위하여 압축된 비디오 신호에 디지털 워터마크를 삽입하는 방법을 제안하였다. MPEG-2 등과 같이 DCT와 움직임 보상 부호화 방식으로 압축된 비트스트림에서, 움직임 벡터를 이용하여 오브젝트를 추출하고 각 오브젝트에 대역확산 기법을 사용하여 독립적인 워터마크 정보를 삽입하는 방식을 사용하였다. 제안된 방식은 프레임마다 워터마크 정보가 다르게 삽입될 뿐 아니라 평균 조작 또는 통계적인 분석과 같은 공격 방식에도 강인성을 보인다.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2011년도 제42회 하계학술대회
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• pp.652-653
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• 2011

수요반응(DR : Demand Response)은 스마트 그리드(Smart Grid)를 구성하는 핵심 요소 중 하나이다. 본 논문에서는 스마트 그리드 환경 하에서 ISO(Independent System Operator)의 수요자원시장에 참여함과 동시에 말단 수용가들을 대상으로 다수의 DR 프로그램을 운영하는 LA(Load Aggregator)사업자의 DR자원 운영 시스템에 대한 전반적인 개념 및 흐름에 대하여 기술하였다. 또한, 스마트 그리드 하에서 LA사업자의 DR자원 운영 시스템 설계 중 LA사업자의 DR자원 최적배분 전략에 대한 개념 및 예시를 제시하였다.

• 한국군사과학기술학회지
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• 제16권3호
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• pp.340-347
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• 2013

Weapon effect is a key issue throughout the life cycle of weapon systems. Only when weapon effect is considered properly, Effects Based Operation(EBO), Effects Based Acquisition(EBA), and Effects Based Development(EBD) could be possible. Because the transfer of weapon effect technologies is restricted in most foreign counties, independent development is necessary. In this paper, framework of weapon effects calculator for hardened targets is proposed to meet the own development needs. It is designed focusing on running time, validation and expandibility by adoption of modular architecture. Required technologies for each module are identified, and unclassified ones are summarized.

• Journal of Power Electronics
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• 제9권6호
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• pp.835-844
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• 2009

In this paper a new buck-boost type DC-DC converter is presented. Its voltage gain is positive, all active elements operate under soft-switching condition independent of loading, magnetic isolation and self output short-circuit protection exist, and very fast dynamic operation is achievable by a simple bang-bang controller. This converter also exhibits appropriate PFC characteristics since its input current is inherently proportional to the source voltage. When the voltage source is off-line, it is sufficient to add an inductor after the rectifier, then near unity power factor is achievable. All essential guidelines to design the converter as a DC-DC and a PFC regulator are presented. Simulation and experimental results verify the developed theoretical analysis.

• Journal of Power Electronics
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• 제18권4호
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• pp.1223-1234
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• 2018

In this paper, a new three-port multidirectional DC-DC converter is proposed for integrating an energy storage system (ESS) to a bipolar DC microgrid (BPDCMG). The proposed converter provides a voltage-balancing function for the BPDCMG and adjusts the charge of the ESS. Thanks to the multi-functional operation of the proposed converter, the conversion stages of the system are reduced. In addition, the efficiency and weight of the system are improved. Therefore, this converter has a significant capability when it comes to use in portable BPDCMGs such as electric DC ships. The converter modes are analyzed and small-signal models of the converter in each of the independent modes are extracted. Finally, comprehensive simulation studies are carried out and a BPDCMG laboratory prototype is implemented in order to verify the performance of the proposed voltage balancer using the burst mode control scheme.

• Journal of Electrical Engineering and Technology
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• 제8권6호
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• pp.1337-1344
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• 2013

This paper presents a simplified modulation strategy for the three-leg VSI fed two-winding induction motor. The strategy provides independent unbalanced voltage control for the main and auxiliary windings. This make the motor can be reversed rotation through the range of motor speed operation without limitation of voltage boost of the auxiliary winding. To study the advantages of the proposed drive, the experimental results such as voltage stresses, hysteresis band of the currents in locus, and also acoustic noise levels of the three-leg VSI are compared with those of the conventional two-leg topology. The results obviously show that the proposed technique achieves superior performance compared with the traditional scheme in case of dramatic increase of DC bus utilization, effective reduction of harmonic voltages content, and also significant enhancement of motor efficiency.

• Journal of Advanced Marine Engineering and Technology
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• 제31권7호
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• pp.872-880
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• 2007

The development of a Marine Engine Room Simulator system for training and research is described. Development objectives of the system are for both student training, research and development work. The system includes a distributed server/client architecture for 1 to 1, or 1 to many client simulation operation through OPC server, complete separation of visual elements from the controlling routines and the ability to work on the mathematical model independent of the controller and visual systems. A graphical user interface for the man-machine interface has been developed and the mathematical model has been updated. Various engine room operational situations can be simulated. The use of marine engine room simulator for training of sea going engineers and its competency for STCW-95 is discussed.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2002년도 추계학술대회논문집
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• pp.1000-1003
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• 2002

For high density optical storage, there should be a high NA objective lens and a shorter wavelength laser diode. To secure the disc tilt margin related to the coma aberration, moreover, it's difficult to apply the tilt compensation mechanism into the portable PC. In this paper, we proposed the 3-axis asymmetry pickup actuator with high efficiency symmetric magnetic circuit, which consisted of the top cover type inner yoke for high magnetic flux density, the coil stack unit for the 3-axis independent operation and vertically polarized magnets. This newly suggested actuator features DVD-RAM recording, we achieved the high focus & track AC sensitivity and the greatly stabilized system.