• 전기학회논문지
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• 제66권12호
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• pp.1830-1835
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• 2017

8200 Series Electric Locomotives are mostly imported from overseas due to aging and uncertainty of source technology, and it's the maintenance cost is increasing. We are analyzed life cycle costs based on international standards such as IEC 60300-3-3 and IEC62278. The main conversion system of the 8200 series electric locomotive is closely related to vehicle operation and is one of the subsystems requiring frequent maintenance. In this paper, the life cycle cost of the main conversion unit in 8200 series electric locomotive is analyzed based on the maintenance manual. As a result of analysis, maintenance cost of GTO module and control device is relatively high, and it is confirmed that the cost increases according to the useful life.

• 한국항공운항학회지
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• 제25권3호
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• pp.135-142
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• 2017

As PED(Personal Electronic Device) market has been rapidly grown, the demand on Lithium battery, which is most commonly used power source of PED, also has been increased. Dew to this trend, the amount of Lithium battery air transportation is also increasing. However, it should be treated very carefully because Lithium is one of very explosive metal. So ICAO, IATA and civil aviation agencies try to enhance the safety of Lithium battery air transportation by aircraft certification and operating regulations. To enhance in-flight safety, the aircraft for transporting Lithium battery should equip certified fire extinguishing system. But recent studies find that Halon, currently used extinguishing agent, is not effective on extinguishing Lithium battery fire. Besides, there is no certified Halon replacement for air use and no acceptable specific minimum performance standard(MPS) for Lithium battery fire. For this issue, a study on characteristics and establishing MPS of Lithium battery fire is needed for safe air transportation of Lithium battery.

• JSTS:Journal of Semiconductor Technology and Science
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• 제16권2호
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• pp.204-209
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• 2016

The analyses on self-heating effect in 7 nm node non-rectangular Bulk FinFET device were performed using 3D device simulation with consideration to contact via and pad. From self-heating effect simulation, the position where the maximum lattice temperature occurs in Bulk FinFET device was investigated. Through the comparison of thermal resistance at each node, main heat transfer path in Bulk FinFET device can be determined. Self-heating effect with device parameter and operation temperature was also analyzed and compared. In addition, the impact of interconnects which are connected between the device on self-heating effect was investigated.

• International Journal of Fluid Machinery and Systems
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• 제7권1호
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• pp.1-6
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• 2014

The propellant acquisition vane (PAV) is a key part of a vane type surface tension propellant management device (PMD), which can manage the propellant effectively. In the present paper, the fluid transportation behaviors for five PAVs with different sections were investigated by using microgravity drop tower test. Further, numerical simulation for the propellant flow in a PMD under microgravity condition was also carried out based on VOF model, and showed the similar flow pattern for PAVs to the experiment. It is noted that the section geometry of PAVs is one of the main factors affecting the fluid transportation behavior of PMD. PAVs with bottom length ratio of 5/6 and 1/2 have larger propellant transportation velocity. Based on the experiments, there were two stages during the process of propellant transportation under microgravity environment: liquid relocation and steady transportation stage. It is also recognized that there is a linear correlation between liquid transportation velocity and relative time's square root. Those results can not only provide a guideline for optimization of new vane type PMDs, but also are helpful for fluid control applications in space environment.

• 대한공업교육학회지
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• 제32권1호
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• pp.117-133
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• 2007

이 연구는 중등학교 학생들에게 비행의 원리를 이해하고 항공 기술 분야에 흥미를 가질 수 있도록 하기 위해 학교 현장에 적용 가능한 교수-학습 자료인 학습용 풍동의 힘 측정 장치를 개발하였다. 연구의 내용은 학습용 풍동의 힘 측정 장치 개발과 실험으로 이루어져 있다. 이 연구에서 얻은 주요 결과를 정리하면 다음과 같다. 공과대학 기계계열 학과나 항공연구소 등에서 사용하는 고가의 Load cell을 이용한 장치 대신에 지렛대 원리를 활용한 간단한 구조이다. 종합된 하나의 장치로 양력, 항력 및 유체 저항 비교 실험이 가능하다. 에어포일 받음각에 따른 양력 계수는 실험값과 이론값이 전체적으로 비슷한 경향성을 갖으며, 실속 현상은 실험값이 이론값보다 더 큰 받음각에서 나타났다. 에어포일 받음각에 따른 항력 계수는 실험값과 이론값이 전체적으로 비슷한 경향성을 갖으며, 실험값은 이론값에 비해 항력 계수의 증가 비율이 완만하게 증가하였다.

• 전력전자학회논문지
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• 제26권3호
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• pp.205-213
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• 2021

Due to the advantage of reducing the voltage applied to the switch semiconductor, the input series and output parallel combination is widely used in systems with high input voltage and large output current. On the other hand, the LLC converter is widely used as a high-efficiency power converter, and when connected by ISOP combination, there is a possibility that input voltage imbalance may occur due to a mismatch of passive devices. To avoid damaging the switching device, this study analyzed the DC-link voltage imbalance of a high-capacity supply using an ISOP LLC converter. In addition, the case where DC-link unbalance control was applied and the case not applied was analyzed respectively. Based on this analysis, an initial start-up algorithm was proposed to prevent input power semiconductor device damage due to DC-link over-voltage. The effectiveness of the proposed algorithm has been verified through simulations and experiments.

• 전기학회논문지
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• 제67권5호
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• pp.688-694
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• 2018

The transition section of the overhead rigid conductor rail (ORCR) consists of a direct induction device and a limit point to prevent the power supply failure and failure of the electric railway vehicle pantograph due to the difference of the uplift in the catenary line. In T-Bar transition section, a twin simple catenary is mostly installed between the overhead catenary system (OCS) in the ground section and the ORCR in the underground section. In this paper, we compare and analyze the possibility of replacing the twin simple catenary with heavy simple catenary. The reliability of numerical analysis results was confirmed by comparing field test with numerical results. Comparing the numerical results of the twin simple catenary with the heavy simple catenary in the transition section, the difference uplift is 5.9[mm] on average. When applying heavy simple catenary instead of twin simple catenary, the slight difference of uplift can be compensated by adjusting the height of hanger-ear or support bracket.

• 한국응급구조학회지
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• 제26권1호
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• pp.87-99
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• 2022

Purpose: This study aimed to provide basic data for the improvement of the standards related to the performance improvement of the firefighting equipment standards for special ambulances. Methods: Among the domestic firefighting equipment standards, the special ambulance standard was compared with the NFPA 1917 standard for the United States automobile ambulance 2019 and European Union European standard EN 1789 medical vehicle and its equipment, a road ambulance. Results: Anti-skid performance based on indoor noise standards, performance standards for interior lights, seat belt warning device, child car seat fixing device, safety handle, auxiliary footrest, and flooring materials should be supplemented. Conclusion: It is necessary to strengthen the production and performance standards for improvement to a level corresponding to the national standards, such as the United States and European Union.

• 한국정보통신학회:학술대회논문집
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• 한국정보통신학회 2012년도 춘계학술대회
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• pp.535-538
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• 2012

최근 ITS(Intelligent Transportation System)와 관련된 연구들이 활발하게 진행되면서 정보화 사회에 알맞은 차세대 교통정보 체계를 구축하는데 일조하고 있다. 도로상의 차량 속도 및 교통 정보를 실시간으로 감지할 수 있는 시스템을 구축하여 운전자에게 정보를 제공함으로써 전체 교통 상황의 흐름에 좋은 영향을 끼칠 수 있다. 본 연구에서는 각기 다른 근원지로부터 제공되는 실시간 교통 정보를 가공하여 보다 신뢰적인 실시간 교통정보를 제공하는 알고리즘을 개발하고 이를 적용하는 플랫폼 구축에 관한 연구이다.

• 한국정보통신학회논문지
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• 제15권8호
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• pp.1642-1646
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• 2011

본 논문에서는 컨테이너화물 안전수송에 사용되는 ConTracer장치에 활용할 2.45GHz 및 GPS 통합 안테나 보드를 설계 및 검증하고자 한다. 설계된 통합 안테나 보드는 컨테이너 도어에 적용하고자 컨테이너 도어에 해당되는 모형 모델링하여 철재물에 대한 RF 영향에 대해 시뮬레이션 하여 그 결과를 반영하여 2.45GHz 안테나와 GPS 안테나를 설계하였다. 본 논문에서는 컨테이너 도어 부분만 모델링하여 컨테이너 환경에 초점을 맞춰 최적의 안테나 파라미터들의 성능이 구현될 수 있도록 2.45GHz 안테나와 세라믹 재질로 만든 GPS 안테나를 통합 보드로 제작하여 그 특성을 검증하였다.