• Journal of the Korea Institute of Information and Communication Engineering
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• v.13 no.5
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• pp.996-1002
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• 2009

The EDCA scheme in IEEE 802.11 MAC protocols was adopted to support QoS of each traffic. The impact of legacy DCF stations on EDCA voice service is studied using extensive simulations. The maximum number of voice sessions are obtained in cases that IEEE 802.11b and IEEE 802.11a physical layers are used.

• Proceedings of the KIEE Conference
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• summer
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• pp.7-10
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• 2004

This paper illustrates some case studies of reliability evaluation of iEEE MRTS using the tie line constrained equivalent assisting generator model(TEAG) for reliability evaluation of NEAREST. The proposed TEAG is able to supply the information for reliability evaluation of interconnected power systems. It is important that interconnection between power systems can provide the improved levels of reliability. Therefore, It is expected that the TEAG model developed in this study will provide some solution to many problems for interconnected power systems. The characteristics and validity of this developed TEAG considering transmission systems are introduced by case study of IEEE MRTS.

• Journal of Applied Reliability
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• v.8 no.3
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• pp.145-154
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• 2008

인공위성은 지상 시스템과는 달리 극한 발사환경 및 우주환경에 노출되고, 운용 중 수리가 불가능하며, 임무 실패에 따른 위험비용이 매우 크기 때문에 고신뢰성, 고비용의 부품, 장비 및 시스템을 채택하여 개념설계단계에서부터 신뢰성을 관리한다. 신뢰성 관리의 주요 목적은 설계변경 및 개발 사이클의 반복을 최소화하고, 개발비용을 절감하며, 시스템의 신뢰성을 향상시키기 위한 것으로서, 대부분의 우주시스템 개발 프로젝트에서는 제품보증(Product Assurance) 활동의 일환으로 수행된다. 제품보증 업무는 크게 품질보증, 신뢰성 관리, EEE 부품관리, 재료 및 공정(Material & Process) 관리, 오염관리, 소프트웨어 품질보증 등으로 구분되지만, 포괄적인 의미의 신뢰성 관리 범주에 이를 모두 포함시키기도 한다. 인공 위성의 개발과정에서 기술성능지표 중 하나로서 중점 관리되고 있는 시스템 신뢰성 관리의 세부기법, 프로세스, 개선 필요사항 등에 대하여 살펴보고자 한다.

• Steel and Composite Structures
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• v.22 no.1
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• pp.13-24
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• 2016

In the present paper, glass fibers are substituted partially with monofilament fishnet and polyester matrix for making the composites. The composite specimens were prepared in accordance with ASTM for analyzing the flexural strength and dynamic mechanical properties. Furthermore, machinability revealed the interaction of glass fiber and partial substituted monofilament fishnet fiber with the matrix. Fiber pullouts on the fractured specimen during the physical testing of the composites are also investigated by COSLAB microscope. The results reveal that the fishnet based composites have appreciably higher flexural properties. Furthermore, the glass fiber, woven roving and fishnet composite has more storage modulus and significant mechanical damping. The composite specimens were fabricated by hand lay-up method. Hence, these composites are the possible applications to develop the value added products. The results of this study are presented.

• Journal of Hospice and Palliative Care
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• v.14 no.2
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• pp.71-80
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• 2011

The growth of the aging population in Korea will challenge health and social services. As Korean society changes, the U.S. models of end-of-life care and geriatric care for frail older adults may have increasing relevance for the Korean healthcare system. This article reviews three U.S. models of care for frail older adults: hospice and palliative care, the Program for All-Inclusive Care for the Elderly (PACE), and the transitional care model. We describe the strengths and limitations of each model and discuss ways in which these models could be adapted for the Korean healthcare system.

• Proceedings of the KIEE Conference
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• 2006.07b
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• pp.633-634
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• 2006

The current unbalance occurs in an induction motor with the supply of unbalanced voltage. Existence of an current unbalance occurs by various problems at the time of driving by in crease of the noise not to mention output decrease of a motor by increase of a loss. We confirmed how current unbalance occurred by a voltage unbalance because a slip came to change by the driving situation of a subordinate as for the induction motor. We confirmed that case to run to a low slip in a ratio of the same voltage unbalance rate brought a high current unbalance rate.

• Proceedings of the Korea Information Processing Society Conference
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• 2016.04a
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• pp.818-819
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• 2016

지오코딩(Geocoding)은 자연어로 표현된 주소를 컴퓨터가 인지 가능한 (x,y) 좌표로 변환하는 과정이며, 지리정보 분석 등 다양한 영역의 필수적인 전처리 과정에서 사용된다. 현재 국내 주소를 지오코딩하는 API를 제공하는 서비스 프로바이더는 다수 존재하나, 성능 향상의 여지가 남아있는 현황이다. 본 연구에서는 지오코딩 위치정확도의 향상을 위해 Euclidean/Edit distance 기반 앙상블(Ensemble) 지오코딩 알고리즘(EEE-Geocoding)을 제안하였다. 화학물질 보유 업체 5569개소의 주소를 토대로 제안 기법에 대한 성능평가 실험을 진행하였으며, 평가결과는 0.99 precision, 0.87 recall, 0.92 F1 score 이었다.

• Journal of international Conference on Electrical Machines and Systems
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• v.3 no.1
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• pp.98-104
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• 2014

This paper presents the performance analysis of a sliding mode based hybrid controller for three phase voltage source inverter. The main objective of this analysis is to observe the effectiveness of the controller for fault ride through (FRT) capability improvement of the distributed generations (DG). The performance of the conventional PI based cascaded controller is also presented for comparison purpose.

• Aerospace Engineering and Technology
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• v.1 no.2
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• pp.173-178
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• 2002

Traditionally, for space program whose operation environment is severe, high reliability parts, that is class s microcircuit, JANS level semiconductor, and ER passive parts, are reliable choices. But in some case, we must use 'Non-standard Part' which is not verified as high reliability standard part. To use 'Non-standard Part' in space application, the manufacturer should qualify the part and screen potential week part from the flight lot. In this technical memo, I introduce the flight part verification process for KOMPSAT 1 and KOMPSAT 2 program.

• Proceedings of the KIEE Conference
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• 2007.07a
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• pp.152-153
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• 2007

industrial site has led to a growing concern for harmonic distortion and the resulting impacts on system equipment and operation. Harmonic current is generated by the operation of non-linear load, it means that voltage and current waveforms exhibit a non-linear relationship. Harmonics cause increase losses in the customer and utility power system components. This paper describes application of instantaneous active and reactive theory for the compensation of harmonic currents in three-phase non-linear load.