• Journal of Advanced Marine Engineering and Technology
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• 제19권1호
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• pp.45-53
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• 1995

Temperature distribution on flank face in orthogonal turning with cutting tool of high speed steel is studied by using a finite element method and experiments. Experiments are carried out to verify the validity of the temperature measurement by using a thermoelectric couple junction imbedded in a cutting tool of high speed steel. Good agreement is obtained between the analytical results and the experimental ones for the temperature distributions on flank face of cutting tool with high speed steel. The analytical results show that the temperature on the top flank face of a tool is higher because of the difference of the friction velocity on each face of the tool.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2006년도 추계학술대회 논문집
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• pp.1259-1263
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• 2006

The inter-coach spacing is one of the most important sources of the aero-acoustic noise of a high-speed train. When fluid at high speed flows over an open cavity, such as the inter-coach spacing, large acoustic pressure fields inside the cavity are produced by fluid/structure interactions at the downstream end of the cavity. In this study experiments were performed to investigate the characteristics the aero-acoustic noise generation from the inter-coach spacing of a high-speed train. Results of the measurement confirmed that the noise generated from the gap between mud-flaps are strongly dependent on the size of the gap.

• 한국정밀공학회지
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• 제12권10호
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• pp.102-112
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• 1995

Temperature distribution on the rake face and flank face in orthogonal turning with cutting tool of high speed steel is studied by using a finite element method and experiments. Experiments are carried out to verify the validity of the temperature measurement by using a thermoelectric couple junction imbedded in a cutting tool of high speed steel. Good agreement is obtained between the analytical results and the experimental ones for the temperature distributions on both the rake face and flank face of cutting tool with high speed steel. The analytical results show that the temperature on the top flank face of a tool is higher than it on the top rake face of the tool because of the difference of the friction velocity on each face of the tool.

• 한국분무공학회지
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• 제27권2호
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• pp.84-93
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• 2022

To implement carbon-neutrality in transportation sectors until 2050, hydrogen is considered a promising fuel for internal combustion engines because hydrogen does not contain carbon itself. Although hydrogen does not emit CO₂ emission from its combustion process, the low energy density in a volume unit hinders the adoption of hydrogen. Therefore, the understanding of hydrogen jet behavior and measurement of equivalence ratio must be conducted to completely implement the high-pressure hydrogen direct injection. The main objective of this research is feasibility test of hydrogen local equivalence ratio measurement by laser-induced breakdown spectroscopy (LIBs). To visualize the macroscopic structure of hydrogen jet, high-speed schlieren imaging was conducted. Moreover, LIBs has been adopted to validate the feasibility of hydrogen local equivalence ratio measurement. The hydrogen injection pressure was varied from 4 MPa to 8 MPa and injected in a constant volume chamber where the ambient pressure was 0.5 MPa. The increased injection pressure extends the vertical penetration of hydrogen jet. Due to the higher momentum supply when the injection pressure is high, the hydrogen has easily diffused in all directions. As the laser trigger timing has delayed, the low hydrogen atomic emission was detected due to the longer mixture formation time. Based on equivalence ratio measurement results, LIBs could be applied as a methodology for hydrogen local equivalence ratio measurement.

• 한국산학기술학회논문지
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• 제20권12호
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• pp.237-246
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• 2019

전기기계식 제동장치(EMB : Electro Mechanical Brake)는 자동차 및 철도차량의 차세대 제동장치로서 현재 연구가 활발히 진행되고 있다. 현재의 고속열차용 제동장치는 공압 실린더를 이용하여 제동 압부력을 발생시키나 전기기계식 제동장치 (EMB)에서는 전기 모터 및 기어와의 조합을 통하여 압부력을 발생시킨다. 본 연구에서는 고압부력 발생이 가능한 EMB 구동 메커니즘을 제안하고, 해당 메커니즘을 만드는 기구장치 중 핵심부품인 기어 및 샤프트 부품들에 대한 구조 및 진동해석을 수행하였다. 한편 모델에 대한 동적 진동해석 결과 압부력이 가해진 상태에서 외부가진이 주어졌을 때 부재의 최대 응력이 항복강도 이내임이 확인되었다. 또한, 구조해석 결과 모터샤프트의 축 직경을 최대한 크게하는 설계가 강도 상 유리함을 확인하였으며, 기어와 편심샤프트를 고정하는 볼트에서 큰 전단응력이 발생할 수 있음을 확인하였다. 한편 해석모델의 메커니즘을 재현할 수 있는 시험장치를 제작하여 가장 취약한 부위인 고정 볼트부의 변형률을 구동 토크가 가해진 상태에서 측정하였다. 변형률 측정결과는 해석결과와 오차가 10% 이내로서, 해석모델의 정확도를 검증할 수 있었다.

• 한국도로학회논문집
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• 제11권2호
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• pp.75-83
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• 2009

충격흡수시설의 충돌거동은 보통 0.4초 미만의 짧은 순간에 일어나므로 삼차원의 매우 복잡한 거동을 수치적으로 계산한다는 것은 쉽지 않다. 따라서 새로운 충격흡수시설을 개발할 때 특별한 설계단계를 거치지 않고 실물차량 충돌시험에만 의존하고 있는 실정이다. 충돌시험에서 탑승자 안전도를 평가하기 위해서 계측기를 통해 가속도와 각속도를 추출하여 계산하고 있으며 고속카메라를 이용해 차량과 충격흡수시설의 충돌거동을 촬영한다. 하지만 고속카메라 영상의 활용범위는 제한적으로 사용되고 있으며, 탑승자 안전도 분석이나 충격흡수시설의 에너지소산 메커니즘을 분석하기위해 활용된 사례가 없다. 본 연구에서는 계측기로부터 획득한 데이타와 고속카메라 영상분석을 통해 추출된 데이타를 비교해 적합성 여부를 판단하고 탑승자 안전도 해석이나 충돌거동을 분석 에 활용할 수 있는 방안을 모색하였다.

• 대한인간공학회지
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• 제29권4호
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• pp.541-546
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• 2010

The gesture 'Flick' is the most fundamental and important part for efficient interactions in the touch screen that are being extensively applied to mobile phones. This study investigated users' satisfaction of the flick operation in representative touch phones, and measured their performances with established three measures: gap between finger and initial cursor, the number of moved lists per 0.2 seconds, and the number of moved lists after ten continuous flicks. The measurement was performed with high speed camera and motion analysis software. The flick movement in mobile phone with high users' satisfaction showed that the gap between finger and cursor positions was less and the speed reached high within 0.6 seconds quickly and then was drastically slow down. Especially, maximal and common time intervals between continuous flicks were measured with an experiment. Based on the evaluation and measurement, several design guidelines for efficient flick performances were suggested.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2004년도 추계학술대회 논문집
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• pp.934-939
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• 2004

The Korea high-speed rail, based on the French design. It also implements new concept to increase the strength of bridge deck by adding an impact factor (dynamic intensity factor) in static load. In order to assure the dynamic stability, SYSTRA and Jeseph Penzien, a professor in CEC (the US) conducted a dynamic stability review on design phase. Analyzing the review results, they developed design criteria for dynamic behavior. This study deal with operating PSC box GIRDER equipped with measurement equipment or measured data of Seoul $\∼$ Taejeon, P.S.C BOX GIRDER bridge and steel comsition bridge equipped with measurement equipment based on structual knowledge about configuration of measuring sensor, response analysis of structure when train runs was performed by using measured data of PSC box girder to directly compare with design criteria. moreover, the dynamic stability with comparison of high-speed rail construction criteria was reviewed and analyzed based on historical records.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2003년도 춘계학술대회 논문집 전기기기 및 에너지변환시스템부문
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• pp.435-437
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• 2003

Recently, as the road capacity reaches the limit and environmental problems becomes serious, there is gradually increased a need for railroad vehicles that are environment-friendly and have time regularity, reliability and safety. Accordingly, in addition to conventional railroad vehicles, lots of vehicles are being newly developed. We developed the hardware and software of the measurement system for on-line test and evaluation of korean hish speed train. The software controls the hardware of the measurement data and acts as interface between users and the system hardware. In this paper, we is studied for electric apparatus performance of railway vehicle using sensor. In order to this test is developed signal conversion system. Using this system, we obtained important result for pantograph voltage, battery voltage, axle speed, and running speed.

• 대한기계학회논문집B
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• 제28권2호
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• pp.230-237
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• 2004

This paper suggests and demonstrates a novel flow measurement technique: tunable AC thermal anemometry that allows simple integration, robust measurement, and extremely high accuracy. The principle and simple theoretical analysis of the technique are presented. To find the optimal condition at which the phase lag becomes most sensitive to flow speed change, the phase lag was measured scanning the heating frequency from 1 to 100 Hz, while the flow speed of ethanol was increased stepwise from 0 to 40 mm/s. The sensitivity of phase lag depended on the heating frequency and the flow speed. It was possible to measure the flow speed of 0.7 mm/s with the resolution of 0.1 mm/s at 4 Hz.