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균형상살 검출 알고리즘에서 검출과 관련된 설계변수의 민감도 해석 몇 최적화
고병규,김광훈,손권,Ko, B.K.,Kim, K.H.,Son, K. 대한의용생체공학회 2011 의공학회지 Vol.32 No.1
This study suggested an optimized algorithm for detecting the loss of balance(LOB) in the seated position. And the sensitivity analysis was performed in order to identify the role of each design variable in the algorithm. The LOB algorithm consisted of data processing of measured signals, an internal model of the central nervous system and a control error anomaly(CEA) detector. This study optimized design variables of a CEA detector to obtain improved values of the success rate(SR) of detecting the LOB and the margin time(MT) provided for preventing the falling. Nine healthy adult volunteers were involved in the experiments. All the subjects were asked to balance their body in a predescribed seated posture with the rear legs of a four-legged wooden chair. The ground reaction force from the right leg was measured from the force plate while the accelerations of the chair and the head were measured from a couple of piezoelectric accelerometers. The measured data were processed to predict the LOB using a detection algorithm. Variables S2, h2 and hd are related to the detector: S2 represents a data selecting window, h2 a time shift and hd an operating period of the LOB detection algorithm. S2 was varied from 0.1 to 10 sec with an increment of 0.1 sec, and both h2 and hd were varied from 0.01 to 1.0 sec with an increment of 0.01 sec. It was found that the SR and MT were increased by up to 9.7% and 0.497 sec comparing with the previously published case when the values of S2, h2 and hd were set to 4.5, 0.3 and 0.2 sec, respectively. Also the results of sensitivity analysis showed that S2 and h2 had considerable influence on the SR while these variables were not so sensitive to the MT.
시간 지원 데이타베이스 관리 시스템의 설계 Issue에 관한 연구
김광훈(K H Kim),김한경(H K Kim),백수기(S K Paik) 한국정보과학회 1988 한국정보과학회 학술발표논문집 Vol.15 No.1
최근의 데이타베이스 응용 분야에 있어서 시간에 따른 정보의 변화를 유지관리할 필요성이 대두되고 대용량의 기억장치 가격의 급속한 감소와 함께 이의 이용 기술이 향상되면서 시간 주기에 따라 실세계의 상태에 대한 변경과정을 표현하는 시간 지원 데이타베이스(Temporal Database)에 관심이 집중되고 있으며, 이러한 요구를 만족시키기 위한 여러 방법들이 연구되고 있다. 따라서 본 논문에서는 시간 지원 데이타베이스에 있어서의 시간의 개념과 이에 따른 데이타베이스의 분류를 소개하고, 이러한 데이타베이스 관리 시스템의 설계를 구현하는데 고려해야 하는 Isseue들, 즉 설계 접근 방법, Query 언어의 선택 방법, 데이타의 Versioning 방법, 그리고 기억 영역의 구조 등에 관하여 기술한다. 또한 데이타베이스에 있어서의 새로운 시간 개념인 Revision을 제안하고 이를 적용한 데이타베이스에 관해서도 기술한다.
김광훈(K. H. Kim),문병영(B. Y. Moon),김병수(S. B. Kim) 한국정밀공학회 2004 한국정밀공학회 학술발표대회 논문집 Vol.2004 No.10월
Weatherstrip seals protect passengers form noise, dust, rain and wind out of the vehicle. The more contact area between a body frame and a weatherstrip, the higher efficiency of sealing. A weatherstrip is a sort of an elastomer. Mechanical properties of the weatherstrip is obtained by uniaxial tension test. In this study, nonlinear finite element(FE) analysis is performed to obtain displacements and contact shapes of the weatherstrip. The FE model is developed by using Ogden-foam formulation. In the results of nonlinear FE analysis, the most valuable deformation of the weatherstrip occurred when displacement control value reaches 7.2㎜. Severe deformation is observed as the displacement control value become more increased.
김광훈(K. H. Kim),박정길(J. K. Park),김수한(S. H. Kim),손권(K. Son) 대한기계학회 2008 대한기계학회 춘추학술대회 Vol.2008 No.5
The purpose of this study is to investigate the effect of the position and direction of biting force on non-carious cervical lesion of a premolar. A three dimensional finite element model was constructed from the micro-CT pictures of a normal extracted human maxillary second premolar. A notch-shaped lesion cavity was made at the cervical area of the FE model and filled with conventional hybrid and flowable resin, respectively. Biting force of 200 N was applied on the upper third of the palatal cusp in force directions: vertical(0°), 20° and 40° slanting angles. The increased in slanting angle caused higher stress at the restored lesion and the loading angle was more effective factor for reducing the stresses than the loading position. This means that changing the biting force direction of a patient with non-carious cervical lesions is recommended for enhancing durability of the restoration.