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TiO₂ 첨가가 Mn - Zn Ferrites의 자기적 특성에 미치는 영향
박종원(J. W. Park),한영호(Y. H. Han),이상효(S. H. Lee) 한국자기학회 1999 韓國磁氣學會誌 Vol.9 No.6
Mn-Zn ferrites에 TiO₂가 첨가될 때 전력손실, 밀도, 초기투자율, 저항, 그리고 미세구조의 변화를 고찰하였다. 첨가량이 증가함에 따라 밀도는 증가했지만, 초기투자율은 감소하였다. TiO₂의 첨가에 따라 electron hopping을 일으키는 활성화에너지와 전기저항이 증가하였다. 1150 ℃에서 소결한 TiO₂를 1.5 wt% 첨가한 시편은 1 ㎒, 25 mT, 80 ℃에서 83 ㎽/㎤의 전력손실을 나타내었다. 그러나 1200 ℃에서 소결할 때는 과대입성장이 발생하여 같은 측정 조건에서 1168 ㎽/㎤의 전력손실을 얻었다. The effect of TiO₂ addition has been studied on the power loss, density. initial permeability, resistivity, and microstructure of Mn-Zn ferrites. TiO₂ addition increased the density of sintered body and decreased of the initial permeability. Activation energy for electron hopping as well as electrical resistivity increased with TiO₂ addition. The toroidal core sintered at 1150℃ with 1.5 wt% of TiO₂ demonstrated the power loss of 83 ㎽/㎤ at 1 ㎒, 25 mT, 80℃. However, the same specimen sintered at 1200℃ lead to the power loss, 1168 ㎽/㎤ at 1 ㎒, 25 mT, 80℃ and developed an exaggerated grain growth.
NTC 써미스터가 내장된 항온 제어용 소형 열전 냉각 모듈 제조
박종원,최정철,황창원,최승철,Park J. W.,Choi J. C.,Hwang C. W.,Choi S. C. 한국마이크로전자및패키징학회 2004 마이크로전자 및 패키징학회지 Vol.11 No.3
NTC 써미스터를 내장시킨 소형의 열전 냉각 모듈을 제작하고 LD와 같은 광통신부품에 적용하기 위한 온도제어 및 항온유지 특성을 분석하였다 BiTe계 열전반도체 21쌍으로 구성된 열전 모듈은 크기 $7.2 mm{\times}9 mm{\times}2.2 mm$이고, 내장된 써미스터의 빠른 응답속도로 인해 정밀온도제어가 가능하다. 열전 모듈은 성능 지수(Z) $2.5{\times}10^{-3}$/K, 300 K에서 최대 온도차(${\Delta}T_{max}$) 72 K, 최대 흡열량($Q_{max}$) 2.2W 값을 나타내었으며 온도 제어 정밀도는 대기 중에서 ${\pm}0.1^{\circ}C$내였다. 이는 광통신 부품의 작동 환경 안정성을 확보할 수 있는 항온제어용 소형 열전 모듈로서 적용이 가능하다. NTC thermistor embedded miniature thermoelectric module was fabricated for the precise temperature control of optical communication device such as laser diode (LD). The miniature thermoelectric module ($7.2 mm{\times}9 mm{\times}2.2 mm$) consists of 21 BiTe thermoelectric couples, the operating temperature is precisely controlled by embedded thermistor with quick response. The figure-of-merit (Z), maximum temperature difference (${\Delta}T_{max}$), maximum cooling capacity ($Q_{max}$) of the miniature thermoelectric module were $2.5{\times}10^{-3}$/K, 72 K, 2.2 W respectively and temperature could be controlled in range of ${\pm}0.1^{\circ}C$ accuracy in air. The fabricated miniature thermoelectric module is suitable for applications of the optical communication packaging.
과다 예압을 받는 테이퍼롤러 베어링의 수명단축효과에 대한 실험적 연구
박종원(J. W. Park),김형의(H. E. Kim),김종억(J. E. Kim),심양진(Y. J. Sim),정원욱(W. U. Jung) 대한기계학회 2009 대한기계학회 춘추학술대회 Vol.2009 No.11
Tapered roller bearings are core component for rotating machine that endure axial and radial load simultaneously. Especially tapered roller bearings used for input and output shaft of transmission the life shortening effect as excessive axial pre-load, which can be occurred in assembly line of transmission, was frequently reported in that case. In this study, we derived the equation for the life of tapered roller bearing in case of excessive pre-load by accelerated life test. DOE method and FEA was used for designing the accelerated life test condition. The derived life equation of tapered roller bearing calculated longer life than the exited L₁? bearing life equation. Because we analyzed the accelerated life test results with Weibull distribution. The result of this study will be helpful to predict the life of tapered roller bearing in case of excessive pre-load and design that kind of rotating machines.
파워스티어링 호스의 필드고장 재현을 통한 누유경로 파악
박종원(J. W. Park),이기천(G. C. Lee),김형의(H. E. Kim),임영한(Y. H. Lim),이종황(J. H. Lee),정원욱(W. W. Jeong) 유공압건설기계학회 2009 유공압건설기계학회 학술대회논문집 Vol.2009 No.11
Generally, a leakage in a high pressure hose assembly can be determined if hydraulic fluid falls down through fitting which is swaged with a rubber hose. This study tried to visualize leakage, which is considered a failure occurring often in the hydraulic system. In the case of methods which verify leakage paths in the power steering hydraulic system equipped with a high pressure hose assembly, three types of leakage paths, which could be seen by cutting the swaging part, were generally found. However, it was difficult to find out leakage paths by using power steering oil. In this study, four methods, including the thermal burn image method, the hole drilling method of fitting metal, the white paint infiltration method, and the fluorescent infiltration method, were tried to introduce. Reappearance test methods in the high pressure hose assembly, which include a hole drilling, a white paint infiltration, and a fluorescent infiltration method, can be applied to find the failure mode and to approve the test before the mass production of the high pressure hose. Finally, we found the leakage path of the power steering hose by the fluorescent infiltration method and that can be useful to modify and old system.