• 전력전자학회:학술대회논문집
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• 전력전자학회 2015년도 추계학술대회 논문집
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• pp.217-218
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• 2015

Two axial flux permanent magnet (AFPM) machines using soft magnetic composite (SMC) and lamination steel are studied. Generally stator cores of AFPM machines are manufactured using SMC because AFPM machines need 3 dimensional core structures. However, SMC cores have very disadvantages in magnetic properties. Especially permeability value is much lower than that of lamination steel, so magnetic field density is also lower. In terms of core losses, SMC cores have much larger loss values than lamination steel cores because SMC core can't be laminated. In this study, AFPM machine was designed using laminated steel, and iron losses in two machines using SMC and laminated steel were studied. Simulations were carried out by a commercial 3-D FEM tool.

• 전력전자학회:학술대회논문집
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• 전력전자학회 2015년도 추계학술대회 논문집
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• pp.115-116
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• 2015

Grid voltage variation is usually happened but existing PV inverter dose not consider this variation before inverting into AC power. This inverting is a cause of unnecessary losses. This paper proposes that DC-link should be changed for removing those losses. Furthermore, maximum efficiency tracking control algorithm with variable DC-link voltage is proposed and verified by simulation and experiment.

• Smart Structures and Systems
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• 제25권3호
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• pp.385-391
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• 2020

In this paper, a new passive lossless snubber circuit with energy transfer capability is proposed. The proposed lossless snubber circuit provides Zero-Current Switching (ZCS) condition for turn-on instants and Zero-Voltage Switching (ZVS) condition for turn-off instants. In addition, its diodes operate under soft switching condition. Therefore, no significant switching losses occur in the converter. Since the energy of the snubber circuit is transferred to the output, there are no significant conduction losses. The proposed snubber circuit can be applied on isolated and non-isolated converters. To verify the operation of the snubber circuit, a boost converter using the proposed snubber is implemented at 70W. Also, the measured conducted Efficiency Electromagnetic Interference (EMI) of the proposed boost converter and conventional ones are presented which show the effects of proposed snubber on EMI reduction. The experimental results confirm the presented theoretical analysis.

• 한국추진공학회:학술대회논문집
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• 한국추진공학회 2008년도 제31회 추계학술대회논문집
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• pp.388-392
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• 2008

액체로켓엔진의 시험 및 운용에 있어서 사고의 예방과 피해의 축소는 중대한 과제이다. 본 논문은 엔진사고가 일어나는 과정의 각 단계를 정의하였고, 사고 예방 및 위험감소 방안을 결함제거, 비상상황이 사고로 발전하는 것을 막기 위한 사고위험요인 제거, 그리고 사고가 발생하였을 때 피해 축소 및 사고원인파악과 재발방지 부분으로 나누어 고찰하였다. 본 논문에서 제시된 방안들은 실제 엔진의 시험과 운용 시에 적용되어 사고의 위험도를 감소시키는데 이용될 수 있다.

• 산업경영시스템학회지
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• 제22권49호
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• pp.11-21
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• 1999

The purpose of this study is to present the method to select optimal size for the industrial products which are closely related to human's body size. For this purpose, human factors such as body characteristics, body features, and preference in product selection which needs to be considered in setting standards were analyzed. This analysis is to select optimal size to minimize losses caused by the difference of size between demand by the customers and supply from the manufacturers. Using loss function, repetitive calculation process algorithm by using bisearch method was applied in selecting the sizes of demand and supply which minimize the total expected losses. For cumulative normal distribution probability, IMSL routine DNORDF was used. In case study, comparison has been made between the result which was calculated using presented algorithm and the results calculated by the process currently used by KS and ISO by measuring aged women's body size in human factors side and sorting them through the factor analysis and cluster analysis for feature factor extraction. Thus, they can be used as a basis for establishing industrial product standards.

• Journal of Magnetics
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• 제18권3호
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• pp.297-301
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• 2013

Flux-reversal machine (FRM) is cost effective and suitable for mass production due to its simple structure. However, there is a notable permanent magnet flux leakage which deteriorates the performance. To compensate this drawback with a design method, an Inset-Permanent-Magnet-Type FRM (ITFRM) has been proposed. The ITFRM has permanent magnets perpendicular to the stator teeth surface, and thus, is much more difficult to demagnetize. In this paper, we deal with the iron losses and irreversible permanent magnet demagnetization characteristics of the ITFRM according to various design variables and driving conditions. To analyze the characteristics, a two-dimensional finite-element method (2D-FEM) considering nonlinear analysis of permanent magnets is used. As a result, we propose the design variables that have the largest effects on the iron losses and irreversible magnet demagnetization.

• 한국광학회지
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• 제12권2호
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• pp.98-102
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• 2001

포화흡수체$Cr^{4+}:YAG$와 유기염료 박막을 사용한 $1.06{\mu}m$ Nd:YAG 공진기에서 수동 큐스위칭 동작시 나타나는 포화흡수체의 포화특성을 분석하였다. 정상모드와 수동 큐스위칭 레이저의 문턱에너지 차이로 광손실을 측정하여 큐스위칭 동작에서 나타나는 포화흡수체의 포화투과도와 불포화 기저상태 밀도수를 분석하였다.

• 한국지하수토양환경학회지:지하수토양환경
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• 제19권6호
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• pp.30-36
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• 2014

The objective of this study is to estimate soil loss in the buffer zone of Guem river with future climate change simulation. Revised Universal Soil Loss Equation (RUSLE) model was used for the estimation of soil loss at the buffer zone of Guem river. As results of simulations, the area of the maximum soil loss potential was estimated as the Cheongsung-myeon Okchun-gun Chungcheongbuk-do. The soil losses were estimated to be 106.67 and 103.00 ton/ha/yr for the 2020 segi (2015-2025) and 2040 segi (2035-2045) in the Cheongsung-myeon area, respectively. Also, the estimated average values of soil losses in the Cheongsung-myeon with future climate change was 110.78 ton/ha/yr.

• Journal of information and communication convergence engineering
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• 제17권1호
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• pp.8-13
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• 2019

Smart Farming has been regarded as an important application in information and communications technology (ICT) fields. Selecting crops for cultivation at the pre-production stage is critical for agricultural producers' final profits because over-production and under-production may result in uncountable losses, and it is necessary to predict crop production to prevent these losses. The ITU-T Recommendation for Smart Farming (Y.4450/Y.2238) defines plan/production consultation service at the pre-production stage; this type of service must trace crop production in a predictive way. Several research papers present that machine learning technology can be applied to predict crop production after related data are learned, but these technologies have little to do with standardized ICT services. This paper clarifies the relationship between agricultural consultation services and predicting crop production. A prediction scheme is proposed, and the results confirm the usability and superiority of machine learning for predicting crop production.

• 정보보호학회논문지
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• 제6권3호
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• pp.3-10
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• 1996

ATM 망과 같은 초고속 네트워크에서 전송 에러의 주요 원인은 과잉밀집 상태에 있어서의 버퍼 오버플로우이며 이로 인해 셀손실을 야기한다. 본 논문은 이러한 문제를 줄이기 위해 연속적인 셀손실을 회복할 수 있는 방법을 제안하며 이 방법은 18개의 연속적인 셀손실을 회복할 수 있다. 또한 인터리빙 기법을 이용한 FEC 기법의 수치적인 성능 분석을 하였으며 이 결과 셀 손실율을 상당히 절감할 수 있었다.