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양희주,김진태,김필환,이찬우 한국철도학회 1998 한국철도학회 학술발표대회논문집 Vol.- No.-
This paper describes the evaluation methods and criteria used to verify running performance of railway vehicle, and shows results of vehicle dynamics simulation and nunning performance tests for New Mugunghwa Coaches that were designed and manufactured by DHI in 1997. Through running performance test of New Mugunghwa Coaches, Vibration, Ride Comfort were measured on the condition of service operation. As a results, each simulation and test results meet the criteria proposed by Korean National Railroad(KNR) and Korea Railroad Research Institute(KRRI).
LED 광을 이용한 그림자 무아레 방법의 감도 향상 및 모바일 전자 기판의 변형 측정
양희주,주진원 한국마이크로전자및패키징학회 2019 마이크로전자 및 패키징학회지 Vol.26 No.4
Electronic substrates used in a mobile device is composed of various materials, and when the temperature is changed during manufacturing or operating, thermal deformation and stress concentration occur due to the difference in thermal expansion coefficient of each material. The shadow moiré technique is a non-contact optical method that measures shape or out-of-plane displacement over the entire area, but it is necessary to overcome the Talbot effect for high sensitivity applications. In this paper, LED light sources of various wavelengths was used to overcome the Talbot effect caused in the shadow moiré technique. By using the phase shift method, an experimental method to retain the measurement sensitivity within 10 μm/fringe was proposed and evaluated, and this method is applied to the thermal deformation measurement of the mobile electronic substrate. In the case of using white light, there were several areas that could not be measured due to the Talbot effect, but in the case of using blue LED light, it was shown that a precise moiré pattern with a sensitivity of 6.25 μm/fringe could be obtained in most areas. 모바일 기기로 사용되는 전자기판은 여러 가지 다양한 재료로 구성되어 있으며, 제조시나 사용 환경에서 온도가 변하면 각 재료의 열팽창 계수의 차이로 인하여 변형과 응력집중이 발생하게 된다. 그림자 무아레 방법은 비접촉으로전체 영역에 걸친 면외변위를 측정하는 광학적 방법이지만 고감도 적용을 위해서는 탈봇 현상의 극복이 필요하다. 본 논문에서는 그림자 무아레 기법에서 발생하는 탈봇 현상을 극복하기 위하여 다양한 파장의 LED 광원을 이용하고, 파장의변화가 탈봇 거리에 미치는 영향에 대해 연구하였다. 위상 이동법을 이용함으로써 10 μm/fringe 이내의 측정 감도를 확보할 수 있는 실험방법을 제안하고 이를 평가하였으며, 이 방법을 모바일 회로 기판의 열변형 측정에 적용하였다. 백색광을 사용한 경우에서는 탈봇 현상으로 인하여 측정이 불가능한 영역이 여러 군데 존재하였으나, 파란색 LED 광을 사용한경우에는 대부분의 영역에서 감도 6.25 μm/fringe의 정밀한 무아레 무늬를 얻어낼 수 있음을 확인하였다.
양희주,임용규,김진태,오형식,오택렬 한국철도학회 2000 한국철도학회 학술발표대회논문집 Vol.- No.-
This paper presents the results of vehicle dynamics simulation for development of single axle bogie for freight vehicle. Those results consists of hunting stability, ride comfort and curving performance such as derailment ratio, unloading ratio. Dynamic behaviors of vehicle having single axle bogie is carried out using the multi-body dynamics simulation program(VAMPIRE). The results of analysis meet the criteria proposed by Korean National Railroad(KNR) and Korea Railroad Research Institute(KRRI).
그림자 무아레 측정에서 LED광원의 파장에 따른 측정 정확도 평가
양희주(Heejoo Yang),주진원(Jinwon Joo) 대한기계학회 2018 대한기계학회 춘추학술대회 Vol.2018 No.12
The shadow moire method is used to measure semiconductor deformation. For high sensitivity measurements, the limitation of measurement due to Talbot effect must be solved. In this study, we investigated the changes in the Moire measurement using the light sources of various spectra, and examined whether there are other problems caused by changing the wavelength. As a result, the measurable range was extended using the blue LED, which has a larger Talbot distance than other light sources.
양희주 ( Hee-joo Yang ),주진원 ( Jin-won Joo ) 충북대학교 산업과학기술연구소 2019 산업과학기술연구 논문집 Vol.33 No.1
The shadow moire method is a measurement using a new periodic interference pattern caused by the interference of two gratings. Therefore, the visibility of Moire patterns is very important. In the measurement using a metal specimen, a dark image is obtained because of the light entering the camera due to the regular reflection. It is difficult to confirm moire patterns in these images. Therefore, in this paper, we induced scattered reflection by applying artificial roughness through spraying of matte white paint. In addition, we proposed a method to minimize the distortion caused by spraying. This spray method was applied to the specimen of the mirror to solve the visual degradation due to the specular reflection. The flat specimens made in this way were found to have significantly less distortion than the metal specimens. These flat specimens will enhance the reliability of the study as a basis for the development of high sensitivity shadow moire measurements. In addition, the plastic deformation and the application of the spray method were used to make specimens with arbitrary deformation that could be measured with micro deformation. If plastic thermal deformation is used, both excessive deformation and micro deformation can be realized. In the case of applied paint spraying, the manufacturing process is cumbersome, but it is possible to fabricate a deformation more micro than that of a specimen by using thermal deformation of plastic.
양희주(Yang Hee-Joo),우관제(Woo Kwan-Je),이강운(Lee Kang-Wun),성재호(Seong Jae-Ho) 한국철도학회 2009 한국철도학회 학술발표대회논문집 Vol.2009 No.11월
The ride comfort means the level of comfort for passenger on the train from vibration caused by external force such as track irregularity, train speed. the manner in which the passenger experiences ride comfort differs depending on the frequency and amplitude of the vibrations. the airspring is one of the suspension parts of railway vehicle and play an important rule to improve the ride comfort. To get soft vertical stiffness of the air spring, every air spring has the auxiliary air reservoir. the orifice is fitted in the air feed connection between the air spring and the auxiliary air reservoir, which provides damping control of the vertical oscillation of car-body. This paper presents the result of wedge test to show the damping performance of vibration of the railway vehicle by the difference of orifice diameter.
양희주 ( Hee-joo Yang ),주진원 ( Jin-won Joo ) 충북대학교 산업과학기술연구소 2018 산업과학기술연구 논문집 Vol.32 No.1
The greatest limitation of the shadow moire method is that when the sensitivity becomes high to microns, the visibility of the moire pattern is very low due to the Talbot effect. For high sensitivity and reliable deformation measurement, it is necessary to increase the Tabot distance of moire pattern. In this paper, experiments for various experimental conditions were performed, and the change of the visibility and the Talbot distance of moire pattern were evaluated The experimental results show that the visibility and distance of the moire pattern are affected not only by the sensitivity and incident angle of the moire condition but also by the observation angle. The moire pattern for the reference grating, the light source, and the distance L of the camera was not significantly affected by the measurement of slope of the speciment, but the slope was found to be significantly larger as the distance Z between the reference grating and the specimen increased.