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Load-Measuring Pot Bearing with Built-In Load Cell —Part I: Design and Performance

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Engineering（科研） 2013年第11期5卷 856-864页

作者： Jeong-Rae Cho Young Jin Kim jong-won kwark Sung Yong Park won jong Chin Byung-Suk Kim Structural Engineering Research Division Korea Institute of Construction Technology Goyang-Si Korea

This paper presents the underlying principle and the results of various performance evaluations for a load-measuring pot bearing with built-in load cell. The pot bearing composed of a pot made of steel in which an elastomer disk is inserted is a bearing supporting larger loads than the elastomeric bearing and accommodating rotational movement. Owing to a Poisson’s ratio close to 0.5, elastomer withstands hydrostatic pressure when confined in a rigid body. Accounting for this principle, the vertical load applied on the pot bearing can be obtained by converting the pressure acting on the elastomer. Therefore, a load-measuring pot bearing is developed in this study by embedding a load cell exhibiting remarkable durability in the base plate of the bearing. The details for the insertion of the load cell in the base plate of the pot were improved through finite element analysis to secure sufficient measurement accuracy. The evaluation of the static performance of the pot bearing applying these improved details verified that the bearing exhibited sufficient accuracy for the intended measurement purpose. The dynamic performance evaluation results indicated that accurate measurement of the dynamic load was also achieved without time lag.

关键词： Bridge Bearing Pot Bearing Load-Measuring Load Cell

Load-Measuring Pot Bearing with Built-In Load Cell —Part II: Fatigue Performance and Experimental Temperature Correction

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Engineering（科研） 2013年第11期5卷 881-886页

作者： Jeong-Rae Cho Young Jin Kim jong-won kwark Sung Yong Park won jong Chin Byung-Suk Kim Structural Engineering Research Division Korea Institute of Construction Technology Goyang-Si Korea

This paper presents the results of fatigue performance tests performed up to 10 million cycles on a load-measuring pot bearing with built-in load cell to verify its field applicability and proposes an empirical temperature correction formula. In Part I of this work, various measurement performances of the load-measuring pot bearing were evaluated through static and dynamic loading tests. Bridge bearings are subjected to the effect of fatigue caused by the repeated application of moving loads and exposed to harsh site conditions including cold and hot weathers differently to laboratory conditions. Accordingly, the durability of the load-measuring pot bearing with built-in load cell shall be secured and the environmental effects like temperature shall be minimized for its application on field. This study conducted fatigue tests up to 10 million cycles on a load-measuring pot bearing with the capacity of 1000 kN to examine eventual degradation of the measurement accuracy with respect to the number of fatigue loading cycles. In addition, the experimental temperature correction procedure is proposed to obtain the temperature correction formula enabling to correct the effect of temperature on the load measurement.

关键词： Pot Bearing Load-Measuring Load Cell Fatigue Temperature Correction

Comparison of Measured and Dynamic Analysis Vertical Accelerations of High-Speed Railway Bridges Crossed by KTX Train

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Engineering（科研） 2013年第9期5卷 756-763页

作者： Hyejin Yoon won jong Chin Jeong-Rae Cho Jae Yoon Kang jongwon kwark Structural Engineering Research Division Korea Institute of Construction Technology Goyang South Korea

Since high-speed railway bridges are subjected to cyclic loading by the continuous wheel loads traveling at high speed and regular spacing, their dynamic behavior is of extreme importance and has significant influence on the riding safety of the trains. To secure the riding safety of the trains, advanced railway countries have limited the vertical acceleration of the bridge slab below critical values at specific frequency domains. Since these limitations of the vertical acceleration constitute the most important factors in securing the dynamic safety of the bridges, these countries have opted for a conservative approach. However, the Korean specifications limit only the size of the peak acceleration without considering the frequency domain, which impede significantly rational evaluation of the high-speed railway bridges in Korea. In addition, the evaluation of the acceleration without consideration of the frequency domain is the cause of disagreement between the dynamic analysis and measurement results. This study conducts field monitoring and dynamic analysis on high-speed railway bridges to gather the acceleration signals and compare them. Significant difference in the size of the vertical acceleration was observed between the measured and dynamic analysis accelerations when discarding the frequency domain as done in the current specifications. The comparison of the accelerations considering only low frequencies below 30 Hz showed that the dynamic analysis reflected accurately the measured vertical acceleration.

关键词： High-Speed Railway Bridge Vertical Acceleration Dynamic Response

Highly Stable Silicon–Carbon–Nitrogen Composite Anodes from Silsesquiazane for Rechargeable Lithium-Ion Battery

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Journal of Materials Science & Technology 2016年第3期32卷 195-199页

作者： Yong Seok Kim Yong L.Joo Young-Je kwark School of Chemical & Biomolecular Engineering Cornell University Department of Organic Materials and Fiber Engineering Soongsil University

Herein, we developed novel silicon-carbon-nitrogen （SiCN） composites synthesized by pyrolyzing silsesquiazane polymer as an anode material for rechargeable lithium-ion batteries. Among variable pyrolysis temperatures of 700 ℃, 1000 ℃ and 1300 ℃, the SiCN composites prepared at 1000 ℃ showed the highest capacity with outstanding battery cycle life by cyclic voltammetry and electrochemical impedance spectroscopy. Such good battery and electrochemical performances should be attributed to a proper ratio of carbon and nitrogen or oxygen in the SiCN composites. Furthermore, our SiCN electrode possessed better lithium ion conductivity than pure silicon nanoparticles. This work demonstrates that polymer-derived composites are among the promising strategies to achieve highly stable silicon anodes for rechargeable batteries.

关键词： Polymer-derived ceramics Silsesquiazane Lithium ion battery Lithium ion conductivity

Computation of Impact Factor of High-Speed Railway Bridge by KTX Train Riding Test

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Engineering（科研） 2013年第9期5卷 751-755页

作者： Hyejin Yoon won jong Chin Jae Yoon Kang jongwon kwark Eui-Seung Hwang Department of Civil Engineering Kyung Hee University Goyang South Korea Structural Engineering Research Division Korea Institute of Construction Technology Goyang South Korea

The design live load of railway is divided into common railway and high-speed railway separately inKorea. Accordingly, the Korean design specification of railway specifies the impact factor for common railway and high-speed railway respectively. The impact factor for high-speed railway is based on Eurocode. Since the impact factor criteria inKoreawere established by adopting those of the Eurocode and without dedicated investigation relying on research results reflecting the domestic circumstances, thorough examination should be implemented on these criteria. Therefore the evaluation of impact factor based on field tests is required. Both dynamic and static vertical displacements are necessary to compute the impact factor. The dynamic response can be obtained from the measurement of deflection of the bridge slab crossed by the firstKoreahigh-speed train (KTX, Korea Train eXpress) running at high-speed. The main difficulties encountered are in obtaining static response because static response corresponds to the response of the bridge when the train remains immobile on the bridge or crosses the bridge at speed slower than5 km/hr. This study introduces the static response derived by applying the moving average method on the dynamic response signal. To that goal, field measurements was conducted under train speeds of5 km/hr and ranging from100 km/hr to300 km/hr on Yeonjae Bridge located in the trial section of the Gyeonbu High-Speed Railway Line before its opening. The validity of the application of the moving average method is verified from comparison of measured static response and derived static response by moving average method. Moreover, evaluation is conducted on the impact factor computed for a bridge crossed by the KTX train running at operational speed.

关键词： High-Speed Railway Dynamic Response Impact Factor Moving Average Method

高能多普勒超声的血流分布是否有助于预测甲状腺恶性病变?

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国际医学放射学杂志 2010年第3期 287-287页

作者：刘双 H.J. Moon J.Y. kwark M.J. Kim E.J. Son E.K. Kim Department of Radiology Research Institute of Radiological Science Yonsei University College of Medicine250 Seongsanno

摘要目的回顾性评价高能多普勒超声成像(US)检测甲状腺肿物内血管分布的能力,并比较血流分布与灰阶可疑征象联合应用是

关键词：血流分布征象甲状腺粒子肉内分泌腺恶性病变多普勒超声