• 전기학회논문지
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• 제60권5호
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• pp.1068-1072
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• 2011

Hydrogen Fuel Cell Vehicle(HFCV) is system that uses electrical energy of fuel cell stack to main power source, which is different system with other vehicles that use high-voltage, large-current. Isolation performance of this system which is connected with electrical fire and electrical shock is important point. Isolation resistance of electric installation is divided according to working voltage, it follows criterion more than $100{\Omega}$/VDC (or $500{\Omega}$/VAC) about system operation voltage in a hydrogen fuel cell vehicle. Although measurement of isolation resistance in a hydrogen fuel cell vehicle is two methods, it uses mainly measurement by megger. However, the present isolation resistance measurement system that is optimized to use in electrical facilities is unsuitable for isolation performance estimation of a hydrogen fuel cell vehicle because of limit of maximum short current and difference of measurement resolution. Therefore, this research developed the isolation resistance measurement system so that may be suitable in isolation performance estimation of a hydrogen fuel cell vehicle, verified isolation performance about known resistance by performance verification of laboratory level about developed system, and executed performance verification through comparing results of developed system by performance verification of vehicle level with ones of existing megger. Developed system is judged to aid estimation and upgrade of isolation performance in a hydrogen fuel cell vehicle hereafter.

• 한국정밀공학회지
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• 제33권12호
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• pp.1015-1020
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• 2016

An advantage of electric vehicles is that they are environmentally sustainable because they do not emit exhaust gases, such as $CO_2$ or Nox. A disadvantage is the low power performance of the motor and battery source, necessitating a reduction in the weight of the vehicle to increase efficiency. Another disadvantage is that the rechargeable battery enables an electric vehicle to only run for a limited number of miles before requiring electric charging. To solve these problems, the hybrid vehicle has been developed by combining environmental sustainability with the high performance of a conventional internal combustion engine. In this study, an electric UTV (Utility Terrain Vehicle) was transformed into a hybrid vehicle system by outfitting the vehicle with a drive auxiliary power system including a 125 cc internal combustion engine. This modification enabled us to extend the range of the hybrid UTV from 50km to 100km per one electric charging.

• 자동차안전학회지
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• 제14권2호
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• pp.45-50
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• 2022

The vehicle motion in urban environment is determined by surrounding traffic flow, which cause understanding the flow to be a factor that dominantly affects the motion planning of the vehicle. The traffic flow in this urban environment is accessed using various urban infrastructure information. This paper represents a color recognition algorithm for traffic lights to perceive traffic condition which is a main information among various urban infrastructure information. Deep learning based vision open source realizes positions of traffic lights around the host vehicle. The data are processed to input data based on whether it exists on the route of ego vehicle. The colors of traffic lights are estimated through pixel values from the camera image. The proposed algorithm is validated in intersection situations with traffic lights on the test track. The results show that the proposed algorithm guarantees precise recognition on traffic lights associated with the ego vehicle path in urban intersection scenarios.

• 한국음향학회지
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• 제33권3호
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• pp.153-162
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• 2014

경험적 음향하중 예측 방법은 우주 발사체 상단 페어링에 가해지는 음향하중을 예측하는 방법으로 상사성 원리를 기반으로 한 제트 실험 데이터를 기반으로 한다. 대표적인 경험적 예측기법인 DSM-II(Distributed Source Method-II)는 제트 화염 축을 따라 소음원을 배치하는 방법이다. 그러나 이러한 경험적 예측 모델은 자유제트 실험 결과를 기반으로 하였기 때문에 실제 상황에 존재하는 충돌 소음원을 고려하기 어렵다는 한계가 있다. 따라서 본 논문에서는 기존 예측 방법에 충돌 소음원을 추가 배치함으로써 충돌 제트 효과를 반영하는 예측 방법을 제안하였다. 이를 위하여 소음원의 위치, 스펙트럼, 세기, 방향성 특징을 고려하였으며 KSR-III(Korean Sounding Rocket-III) 로켓에 대한 음향 하중 예측 결과를 기존 예측 방법 및 실험 결과와 비교하였다.

• 대한조선학회논문집
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• 제56권5호
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• pp.464-471
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• 2019

The acoustic power is a major acoustical characteristic of an underwater vehicle and could be measured in a reverberant water tank. In order to obtain accurate measurement results, the acoustic field formed by the sound source should be investigated quantitatively in the reverberant water tank. In this research, the acoustic field of a reverberant water tank containing an underwater sound source has been analyzed by using an acoustic radiosity method one of the numerical analysis methods suitable for the acoustic analysis of the highly diffused space. The source level of the underwater sound source and acoustical properties of the water tank input to the numerical analysis have been estimated by applying the reverberant tank plot method through a preliminary experiment result. The comparison of the numerical analysis result with that of the experiment has verified the accuracy of the acoustic radiosity method.

• 한국대기환경학회지
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• 제24권3호
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• pp.275-283
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• 2008

Since mobile source is a major source of VOCs, quantifying emissions from motor vehicles is an important factor to control VOCs in atmosphere. In this study, in order to evaluate tailpipe VOCs emissions from motor vehicles, mass emissions of non-methane volatile organic compounds from 45 vehicles were determined. Measurements were made on a chassis dynamometer using CVS-75 mode and speed specific drive modes. Target VOCs are 53 compounds determined as the volatile ozone precursors. The individual VOCs composition of vehicle emission and emission rates were also determined. In case of gasoline vehicles, VOCs emission from over 80,000 km vehicles were about 46% larger than less 80,000 km vehicles. The difference in benzene and toluene according to driving mileage was 44% and 26% respectively. The composition of VOCs were different by fuel type. The order of VOCs composition was paraffins>aromatics>olefins in gasoline vehicle emissions, paraffins>olefins>aromatics in light duty diesel vehicle emissions. The VOCs emissions were decreased as vehicle speed increasing. These results will be used to calculate total VOCs emissions from automobiles in the future.

• 한국정밀공학회지
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• 제22권8호
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• pp.143-150
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• 2005

To verify applicability of multi-dimensional spectral analysis (MDSA) fur noise source identification two different approaches which are frequency response and coherent function have been investigated. The coherence function approach appears able to separate the correlated system when the noise sources were coherent. In this study, we identify contribution of structure-borne-noise of vehicle HVAC system using MDSA method. Firstly, to identify the applicability of MDSA method, 4-inputs of vehicle HVAC system were the signals measured by accelerometers attached on the selected noise sources which were composed of blower, evaporator, heater and duct. While 1-output which was driver's position sound was the SPL signals measured by a remote microphone, when the blower motor was operating. We identify efficiency of systems modeled with four Inputs/single output through ordinary coherence function (OCF) and partial coherence function (PCF). As a result of experiment, the blower accounted for $62-88\%$ of the overall level of sound energy density. Also, according to the analysis of acoustic signal and vibration signals measurement, an investigation of the noise source identification in the vehicle HVAC is presented. With the sound intensity method, the major sources of the vehicle HVAC radiation are verified. Also the method of improving the noise reduction is proposed by attaching damping patch access to blower motor and noise reduction is verified.

• 한국전산유체공학회지
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• 제18권1호
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• pp.58-62
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• 2013

Personal Rapid Transit (PRT) is the emerging personal transport vehicle operating on the loop automatically. The PRT system utilize the electrical power from super capacity or battery, it is important to manage the power or energy. In this regards, the management of high temperature occurred by the operation of system is significantly important to prevent from serious damage of component. In this study, we studied the adequate shape of underbody which can reduce the heat accumulation by pickup coil and condenser using natural air cooling. We suggested the additional air pathway, air inlet and flow separator to decrease the temperature of the heat source components. It was found that suggested system can decrease the temperature of PRT under body by 16% during the static mode and by 10% during the running mode at 30km/h. It is expected that the findings of this study will feed into final design of newly built Korean PRT vehicle.

• Journal of Power Electronics
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• 제19권2호
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• pp.403-412
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• 2019

Aiming at the problems of large dv/dt and di/dt in traditional single-ended converters and high electromagnetic interference (EMI) noise levels, a single-ended isolated converter using the secondary resonance technique is proposed in this paper. In the proposed converter, the voltage stress of the main power switch can be reduced and the voltage across the output diode is clamped to the output voltage when compared to the conventional flyback converter. In addition, the peak current stress through the main power switch can be decreased and zero current switching (ZCS) of the output diode can be achieved through the resonance technique. Moreover, the EMI noise coupling path and an equivalent model of the proposed converter topology are presented through the operational principle of the proposed converter. Analysis results indicate that the common mode (CM) EMI noise and the differential mode (DM) EMI noise of such a converter are deduced since the frequency spectra of the equivalent controlled voltage sources and controlled current source are decreased when compared with the traditional flyback converter. Furthermore, appropriate parameter selection of the resonant circuit network can increase the equivalent impedance in the EMI coupling path in the low frequency range, which further reduces the common mode interference. Finally, a simulation model and a 60W experimental prototype of the proposed converter are built and tested. Experimental results verify the theoretical analysis.

• 전력전자학회논문지
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• 제7권6호
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• pp.587-595
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• 2002

최근 배터리, 태양전지, 연료전지 등의 전원으로 구동되는 전기자동차에 대한 관심이 커지고 있다. 그런데, 이와 같은 전원들의 단위전지 전압은 자동차의 인버터를 구동하기에는 너무 낮기 때문에 수많은 단위전지를 직렬로 연결하여 사용해야하며, 이로 인해 전원의 구조가 복잡해지는 문제가 있다. 본 논문에서는 전기자동차의 응용을 위해 비교적 낮은 전원전압을 충분히 높은 안정된 직류 링크전압으로 바꾸어주는 고효율 대용량 승압 컨버터를 제안하고 그 설계기준과 실험결과를 제시한다.