• Proceedings of the KIPE Conference
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• 2003.07a
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• pp.31-35
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• 2003

본 논문에서는 이중접속 방식의 멀티스텝 인버터를 인 용한 대용량 STATCOM에 관하여 동작원리 및 제어 방식을 기술하기로 한다. 기존의 12-스텝 인버터에 상간 변압기 및 간단한 보조회로를 이용하여 출력전압의 파형을 36-스텝으로 개선하였다. 이러한 방식의 인버터는 10Mvar$\~$30Mvar급 전후의 STATCOM에 적용하면 경제적이다. 2KVA급 STATCOM 시작품의 실험결과로부터 제안한 방식의 타당성을 입증하였다.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2002.07b
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• pp.1016-1018
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• 2002

Poly[bis (3,5-di-t-butyl-1,2-phenylene-1,2-thenylene)-1,4-phenylene-bis(11-oxyundecanylphenyl urethane)] (PV-PU) consisting of alternating a confined phenylenevinylene and a nonconjugated urethane segment in the main chain was synthesized by multistep, photoluminescence of PV-PU is emitted in the blue region with a maximum intensity at about 337 nm.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2002.07b
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• pp.1010-1012
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• 2002

3,3'-di-benzothiazole-4,4-biphenol(DBTB), 3,3',5,5'-tetra-benzothiazole-4,4'- biphenol(TBTB), 5,5'-methy lene-bis(2-(2'-hydroxyphenyl) benzothiazole derivatives were synthesized by multistep. PL of DBTB and TBTB were dramatically shift 47nm and 75nm respectively longer wavelength than the emission of 2-(2'-hydroxyphenyl)-benzothiazole(HBT) because of intramolecular extened $\pi$-conjugate system but methylene-bis-benzothiazole derivatives do not occur at Wavelength-shift.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.27 no.4
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• pp.458-465
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• 2003

The main objective of the research is to develop a research code solving transient incompressible Navier-Stokes equation. In this research code, Adams-Bashforth method was applied to the convective terms of the navier stokes equation and the splitted equations were discretized spatially by finite element methods to solve the complex geometry problems easily. To reduce the divergence on the boundaries of pressure poisson equation due to the unsuitable pressure boundary conditions, multi step approximation pressure boundary conditions derived from the boundary linear momentum equations were used. Simulations of Lid Driven Flow and Flow over Cylinder were conducted to prove the accuracy by means of the comparison with results of the previous workers.

• Journal of the Korean Society for Precision Engineering
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• v.15 no.4
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• pp.15-26
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• 1998

Full car model is needed for investigating as a entire dynamics of vehicle. In this study, 7DOF of full car model's dynamics is selected. This paper proposes the output feedback controller based on optimal control theory. Input data and output data from the optimal controller are used for neural network system identification of the suspension system. To do system identification, neural network which has robustness against nonlinearities and disturbances is adapted. This study uses back-propagation algorithm to train a multil-layer neural network. After obtaining a neural network model of a suspension system, a neuro-controller is designed. Neuro-controller controls suspension system with off-line learning method and multistep ahead prediction model based on the neural network model and a neuro-controller. The optimal controller and the neuro-controller are designed and then, both performances are compared through. For simulation, sinusoidal and rectangular virtual bumps are selected.

• Proceedings of the Korean Society of Soil and Groundwater Environment Conference
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• 2002.09a
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• pp.175-178
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• 2002

The purpose of this research is to evaluate the effect of microemulsion on the remediation of soil contaminated with organic materials. The laboratory tests were conducted to confirm the ability of microemulsion as remediation agent and compare remediation efficiency in microemulsion process with soil washing. In the test, pyrene was used as organic contaminant and alkylpolyethoxylates(C$_4$E$_1$) was used as surfactant. Microemulsion in the $C_4$E$_1$-water-decane mixture was formed in the range of 22 and 48$_{o}$ C at surfactant contents V=55%. Extraction was completed within 30 min and about 90% pyrene was removed. Seperation of pyrene with oil phase lowering temperature was sufficient for application in a multistep process.s.

• Publications of The Korean Astronomical Society
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• v.8 no.1
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• pp.137-151
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• 1993

We have calculated the astronomical almanac 1994 and simulated the trajectory of a satellite orbit considering all perturbative forces with various initial conditions. In this work, Gauss Jackson multistep integration method has been used to calculate our basic equation of motion with high numerical accuracy. It has beer. found that our results agree well with the Astronomical Almanac Data distributed by JPL of NASA and the orbit simulations have been carried out with fast speed, stability and excellent round-off error accumulation, comparing with other numerical methods. In order to be carried out our works on almanac and orbit calculations easily by anyone who uses a personal computer, we have made a computer program on graphical user interface to provide various menus for detail works selected by a mouse.

• Journal of the Korean Institute of Telematics and Electronics
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• v.25 no.3
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• pp.269-275
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• 1988

In this paper, a high efficiency motor drive system which improves the multi-step response of PM step motors by reducing the transition time of the motor drive current, is studied by designing a dual-voltage drive circuit. The designed drive circuit eventually prevents the motor from decreasing drive torque while the stepping rate is increased. The method of designing a dual-voltage drive circuit with the motor specifications is suggested in order to improve the response of step rate and drive efficiency. Also, despite improving the power efficiency on motor driving, the response characterstics suggested by the motor manufacture's specifications are satisfied without any special deficiency.

• Proceedings of the IEEK Conference
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• 2001.06a
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• pp.69-72
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• 2001

Blind equalization of transmission channel is important in communication areas and signal processing applications because it does not need training sequence, nor does it require a priori channel information. Recently, Tong et al. proposed solutions for this problem exploit the diversity induced by antenna array or time oversampling, leading to the second order statistics techniques, fur example, subspace method, prediction error method, and so on. The linear prediction error method is perhaps the most attractive in practice due to the insensitive to blind equalizer length mismatch as well as for its simple adaptive filter implementation. Unfortunately, the previous one-step prediction error method is known to be limited in arbitrary delay. In this paper, we induce the optimal delay, and propose the adaptive blind equalizer with multi-step linear prediction using RLS-type algorithm. Simulation results are presented to demonstrate the proposed algorithm and to compare it with existing algorithms.

• Asian Pacific Journal of Cancer Prevention
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• v.15 no.24
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• pp.10543-10555
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• 2015

Breast cancer primary prevention is a high research priority due to the high psychological and economic costs. The disease is a multistep process and several risk factors have been recognized. Over the past three decades numerous studies have investigated the association of lifestyle with breast cancer, showing independent effects of various factors. We report here a summary of the present state of knowledge on the role of lifestyle patterns, such as physical activity, diet, smoking, hormone therapy, and experience of psychological stress in the modulation of breast cancer in women, and discuss commonly accepted biological mechanisms hypothesized as responsible for the associations. The findings indicate that regular physical activity of moderate to vigorous intensity is probably linked with the decreased breast cancer risk among postmenopausal females and suggestive for a decrease of the risk in premenopausal women. In contrast, the consumption of high-fat diet, alcohol intake, and use of combined estrogen and synthetic progestagen hormonal therapy may increase the risk. Epidemiological findings dealing with a role of smoking and experience of psychological stress are conflicting.