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A study on the dynamic behavior of the Korean next-generation high-speed train
Jeon, Chang-Sung,Kim, Young-Guk,Park, Joon-Hyuk,Kim, Seog-Won,Park, Tae-Won Professional Engineering Publishing Ltd 2016 Proceedings of the Institution of Mechanical Engin Vol. No.
<P>This study describes the dynamic behavior of the HEMU-430X, the Korean next-generation high-speed train. The HEMU-430X was initially analyzed using VAMPIRE, a computer program that is used to examine the dynamics of railway vehicles, based on which it was expected to sway strongly at its tail end. This hunting motion was expected to disappear when the position of the yaw damper was changed. The dynamic behavior of the HEMU-430X was assessed in an on-track test performed using the protocols in the EN14363 standard and measuring the carbody, bogie and axle accelerations; the HEMU-430X was found to satisfy the safety criterion. The hunting motion appeared at speeds of 150, 350 and 387km/h, and countermeasures such as changing the position of the yaw damper, installing carbody dampers, and increasing the damping coefficient of the yaw damper installed on the motor car containing the driver's cab were taken in order to reduce the vibrations. Ultimately, the highest test speed achieved was 421.4km/h. Subsequently, it was found that the critical speed tended to decrease with mileage. This was attributed to excessive lateral damping and a revised design was proposed to solve this problem.</P>
인공근육용 압전복합재료 작동기의 섬유배향각이 총유효 모멘트(M<SUP>E</SUP>)에 미치는 영향
김철웅(Cheol-Woong Kim),이성혁(Sung-Hyuk Lee),남인창(In-Chang Nam),윤광준(Kwang-Joon Yoon) 대한기계학회 2005 대한기계학회 춘추학술대회 Vol.2005 No.11
Due to the diversified use of recent Piezoelectric Zirconate Titanate Composite Actuator (PZTCA), various PZTCAs with the different ply orientation of the fiber layer have been applied. For this reason, the applicable bending moment equation is necessary even though the fiber layer ply orientation and the laminate configuration are changed. The aim of this research is to evaluate the relationship between the total effective moment (M<SUP>E</SUP>) and Bernoulli-Euler bending moment (M) when the ply orientations of UD CFRP are changed. In conclusion, 1) As the performance test results by the CFRP ply orientation, the performance of [0] and [90] were stable. However, while the performance of [+45] was suddenly decreased after 5 hours. 2) The change of M<SUP>E</SUP> by the CFRP ply orientation was evaluated. As the CFRP ply orientation was increased form [0] to [+60], the M<SUP>E</SUP> were gradually decreased. However, they became a little bit increased from [+60] to [90]. 3) After the change of M by the CFRP ply orientation was evaluated it was found that M<SUP>E</SUP>=2.2M was valid for just [0] and that there was a relationship between M<SUP>E</SUP> and M according to the ply orientation.
朴昌宣,金鍾贊,朴相俊,權赫茂 忠南大學校 産業技術硏究所 1992 산업기술연구논문집 Vol.7 No.1
The purpose of this study is to obtain basic infotmation on the wettability of pure-Al/Al₂O₃, Al-alloy/Cu, Al-alloy/Ni and Al-12%Si/Al₂O₃systems, by using the Sessile drop method. The wettability of Al alloy-melt on Al₂O₃increases with increasing temperature from 750℃ to 850℃ for Al-12%Si-y% (Cu, Zn and Mg) (y:0∼2)/Al₂O₃system, the contact angle decreases with increasing Cu, Zn and Mg content. The wettability of Al alloy on Cu and Ni-palte is better than that on Al₂O₃-plate : this is attributed to the interfacial reaction between the Al aiioy and the metal substrate.
정석찬,한태창,서범수,조장혁,주경준 한국경영과학회 1998 한국경영과학회 학술대회논문집 Vol.- No.1
CITIS(Contractor Integrated Technical Information Service) is a contractor's developed service to provide electronic access and/or delivery of contractually required information. CITIS satisfies one of the major CALS objectives to furnish a single-entry point for authorized access to contractor-generated Contract Data Requirement List(CDRL) data. A critical requirement for the practical implementation of the CITIS concept is the ability to access multiple existing heterogeneous databases in a fashion transparent to the CITIS user. In this paper, we will propose a prototype system model for CITIS, and discuss the system architecture of proposed CITIS system as a global information management system for distributed and heterogeneous local information systems. Furthermore, we will discuss about the required server module and using-scenario of proposed CITIS system.
스펙트럼 변이를 이용한 Soft Decision 기반의 음성향상 기법
최재훈(Jae-Hun Choi),장준혁(Joon-Hyuk Chang),김남수(Nam-Soo Kim) 大韓電子工學會 2010 電子工學會論文誌-SP (Signal processing) Vol.47 No.5
본 논문에서는 비정상적인 배경 잡음 환경에서 음성향상을 위한 신호의 스펙트럼 변이 (Spectral Deviation)을 적용한 Soft Decision 기반의 잡음전력 수정 기법을 제안한다. 기존의 Soft Decision 기반의 잡음전력 추정에 있어서 잡음신호의 정상성(Stationarity)을 가정한 스무딩 파라미터를 사용하여 잡음전력을 추정하고 갱신하였지만, 잡음신호의 주파수적인 특성이 상대적으로 빠르게 변하는 비정상적인 환경에서는 강인하지 못한 단점을 가지게 된다. 본 논문에서는 신호의 스펙트럼 변이를 추정하여 정상적인 잡음 환경과 비정상적인 잡음 환경에 따라 적응적으로 잡음전력을 추정하고 갱신하여 잡음신호에 의해 오염된 음성신호를 향상시킨다. 제안된 알고리즘은 다양한 배경 잡음 환경에서 객관적인 음질측정 방법인 ITU-T P.862 perceptual evaluation of speech quality (PESQ)에 의해서 평가되었으며, 기존의 Soft Decision 기반의 음성 향상 기법과 비교하여 보다 향상된 성능을 보여주었다 In this paper, we propose a new approach to noise estimation incorporating spectral deviation with soft decision scheme to enhance the intelligibility of the degraded speech signal in non-stationary noisy environments. Since the conventional noise estimation technique based on soft decision scheme estimates and updates the noise power spectrum using a fixed smoothing parameter which was assumed in stationary noisy environments, it is difficult to obtain the robust estimates of noise power spectrum in non-stationary noisy environments that spectral characteristics of noise signal such as restaurant constantly change. In this paper, once we first classify the stationary noise and non-stationary noise environments based on the analysis of spectral deviation of noise signal, we adaptively estimate and update the noise power spectrum according to the classified noise types. The performances of the proposed algorithm are evaluated by ITU-T P. 862 perceptual evaluation of speech quality (PESQ) under various ambient noise environments and show better performances compared with the conventional method.
( Joon Hyuk Suh ),( Moo Yeol Hyun ),( Yong Hee Lee ),( Kwang Ho Yoo ),( Hee Su Kim ),( Beom Joon Kim ),( Myeung Nam Kim ),( Chang Kwon Hong ) 대한피부과학회 2014 대한피부과학회 학술발표대회집 Vol.66 No.2
Background: Platelet rich plasma(PRP) is widely used for hair growth treatment. However, the mechanisms of PRP and combination of growth factors are not fully understood yet. In an effort to develop new therapies to enhance hair growth, we screened PRP and combination of growth factors of it Objectives: We investigate the growth factors in PRP and compare the effect on hair growth between PRP and combination of growth factors Methods: We examined the effect of PRP and combination growth factors which mixed in different ratio on human dermal papilla cells and C57BL6/J mice using western blot analysis, real-time PCR and immunocytochemistry. Also, we did organ cultures of combining different growth factors for measuring hair length. Results: Combination of EGF and PDGF-AA (1:1 ratio) induced synergistic hair growth and anagen induction activity by regulation of hair growth-related signaling pathways and molecules in hDPCs and C57BL6/J mice model. Conclusion: Combination of EGF and PDGF-AA (1:1 ratio) can be further pharmaceutically developed as a therapeutic material against hair loss and alopecia in human.
Global Soft Decision Employing Support Vector Machine For Speech Enhancement
Joon-Hyuk Chang,Q-Haing Jo,Dong Kook Kim,Nam Soo Kim IEEE 2009 IEEE signal processing letters Vol.16 No.1
<P>In this letter, we propose a novel speech enhancement technique based on global soft decision incorporating a support vector machine (SVM). Global soft decision in the proposed approach is performed employing the probabilistic outputs of the SVM rather than the conventional Bayes' rule. Actually, global speech absence probability (GSAP) is determined by the sigmoid function based on key parameters estimated by the model-trust minimization algorithm of the SVM output. Improved results are obtained in terms of speech quality measures for various types of noise and at different signal-to-noise ratio (SNR) levels when the proposed SVM is adopted in the global soft decision for speech enhancement.</P>