• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2005년도 춘계학술대회논문집
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• pp.567-571
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• 2005

The slender rectangular cantilever beam has vef interesting to study dynamic behaviors of the harmonic base excitation of a cantilever beam shows many nonlinear dynamics due to unstability , energy transfer and mode coupling. Nonlinear phenomenon shows superharmonic, subharmonic, super subharmonic and chaotic motions of the cantilever beam. Experimental observation and verification of these phenomenon carry much importance for the theoretical study as well as in it self. In the experimental cantilever beam, the chaotic motions of the beam appear as a pink noise signal in FFT analysis and as a torus structure in the oscilloscope analyzed to eventually give information of chaotic motions of the cantilever beam.

• 한국전자파학회논문지
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• 제13권5호
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• pp.475-483
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• 2002

적응형 전치왜곡 선형화기를 안정화하기 위한 구조를 제안한다. 증폭기 궤환 루프에 의한 출력 신호의 루프 지연을 보상하기 위해 지연 제어 회로를 추가하고, 적응 앨거리즘으로 사용된 RLS 앨거리즘이 갖는 수치적 불안정성을 완화하기 위하여 Yang의 앨거리즘을 도입한다. 이 방법을 다항식형 전치왜곡기를 이용한 선형화기에 적용하고 모의실험을 통하여 그 효용성을 확인한다.

• 한국응용과학기술학회지
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• 제28권1호
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• pp.1-5
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• 2011

In this study, We investigated the properites of nano-emulsions containing hydrogenated lecithin prepared by high pressure homogenizer. The size of droplet of emulsions prepared by homogenizer at various rpm (rotation per minute) was not measured due to the unstability of emulsions, however, the size of droplet of nano-emulsions prepared by high pressure homogenizer was around 300 nm and the appearance of emulsions was bluish. The stability of emulsions with various lecithin concentration was tested against time. POV (Peroxide value) of emulsions were plotted against time. POVs of emulsions prepared with an egg lecithin and a soy lecithin were increased with time, however, POV of emulsion with Lecinol S-$10^{(R)}$ was kept constant within 60 hours and at $60^{\circ}C$. In consumer test, the nano-emulsion showed higher affinity regardless of skin type. Both of irritation scores of emulsions were similar.

• 동력기계공학회지
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• 제11권2호
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• pp.72-76
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• 2007

Since the magnetic bearing system has unstability inherently it is necessary to measure the displacement for stable operation. Normally the displacement measurement is implemented by using sensors. The sensor for the displacement measurement is selected by precision, installation space, effect of magnetic field and response speed. And the cost of displacement measurement sensor also is considered. At the cost the hall effect sensor has a large advantage comparing with the others. Therefore this study concern about the basis experimental test for the displacement measurement of the magnetic bearing system that uses the hall effect sensor coupled with a tiny permanent magnet. The experimental results confirm the validity and practicability for this displacement measurement sensor.

• 한국전산유체공학회지
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• 제10권4호통권31호
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• pp.24-31
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• 2005

A dynamic simulation on the missile staging system is conducted with numerical techniques. Both Euler equations and Navier-Stokes equations are numerically solved respectively. The dynamic simulation of two moving bodies is fully integrated into the computational fluid dynamics solution procedure. The Chimera grid scheme is applied in this simulation for unsteady supersonic flow analysis with dynamic modeling. The objective of the study is to investigate the problem pertaining to possible unstability in missile staging. In addition, the computational comparison between in viscid and viscid flow solvers is also performed in this study.

• 한국경영과학회:학술대회논문집
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• 한국경영과학회 1998년도 추계학술대회 논문집
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• pp.67-70
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• 1998

The computational speed of interior point method of linear programming depends on the speed of Cholesky factorization to solve AΘA$^{T}$ $\Delta$y=b. If the coefficient matrix A has dense columns then the matrix AΘA$^{T}$ becomes a dense matrix. This causes Cholesky factorization to be slow. The Schur complement method is applied to treat dense columns in many implementations but suffers from its numerical unstability. We study efficient implementation of Schur complement method. We achieve improvements in computational speed and numerical stability.rical stability.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2006년 학술대회 논문집 정보 및 제어부문
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• pp.354-356
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• 2006

In this paper, the position control performance of networked control systems is analyzed when time delay through the network is considered. Integrating a control system into a network has great advantages over the traditional control system which uses point to point connection: it allows remarkable reduction in wiring, makes it easy to install and maintain the system, and improves compability. However, a networked control system has the critical defect that network uncertainties, such as time delay, can degrade the control system's performance. Therefore, the major concern of a networked control system is analyzing the effect of network uncertainties. This paper is concerned with PID controller performance for stability region, critical stability region and unstability region under the time delay in the Controller Area Network.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 1996년도 한국자동제어학술회의논문집(국내학술편); 포항공과대학교, 포항; 24-26 Oct. 1996
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• pp.543-546
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• 1996

We propose a new visual tracking system for grasping which can find grasping points of an unknown polygonal object. We construct the system with the image prediction technique and Extended Kalman Filter algorithm. The Extended Kalman Filter(EKF) based on the SVD can improve the accuracy and processing time for the estimation of the nonlinear state variables. By using it, we can solve the numerical unstability problem that can occur in the visual tracking system based on Kalman filter. The image prediction algorithm can reduce the effect of noise and the image processing time. In the processing of a visual tracking, we can construct the parameterized family and can found the grasping points of unknown object through the geometric properties of the parameterized family.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2005년도 추계 학술발표회 제17권2호
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• pp.459-462
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• 2005

Recently, interest grew on the quality of aggregates following the diminution of primary resources from river and the growing construction demand which exhausted high-quality sand sources around large cities and incited the use of low grade aggregates like shore sand and sea sand that can be supplied in natural state. Moreover, the most sensitive aspect highlighted by the unstability of aggregate supply is the quality. The extreme insufficiency of quality criteria about the materials currently used as substitute aggregates and about concrete mixed with such materials is also critical. This study investigated influence of qualities of concrete which is using mixed crushed sand and natural sand

• 대한가정학회지
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• 제38권6호
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• pp.117-133
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• 2000

The purpose of this study was to examine the effect of perceived economic stress & marital conflict on the quality of life under economic crisis in Korea. Data were collected from 236 couples during May and June 1998, when the Korean economy was under the control of International Monetary Fund (IMF). Many couples reported the unstability of job and the experience of economic strain events. However, the perceived level of marital conflict and the quality of life were not so bad. Husbands perceived economic stress and quality of life higher than wives did. The path analysis showed gender difference in the perceived economic stress as well as in the indirect effect of economic strain events on the quality of life through economic stress and marital conflict. In addition, family income directly affected the quality of life for husbands, but not for wives.