• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2002년도 하계학술대회 논문집 Vol.3 No.2
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• pp.908-911
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• 2002

Recently deep interests and attraction have been paid on the generation of ozone, which is widely used to remove bed smell and to clear water. In this paper the silent discharge and ozone generation characteristics of various typed discharge chambers were investigated experimentally. Dielectric of $Al_2O_3$ was embedded in the cylindrical type of discharge chamber to improve the ozone generation rate and to stabilize the silent discharge mode of operation. Discharge current and ozone concentration depend strongly on the applied voltage and frequency.

• 전기학회논문지
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• 제64권1호
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• pp.90-98
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• 2015

In this paper, an advanced teaching-learning based optimization(TLBO) method for the magnetic levitation controller of Maglev transportation system is proposed to optimize the control performances. An attraction-type levitation system is intrinsically unstable and requires a delicate control. It is difficult to completely satisfy the desired performance through the methods using conventional methods and intelligent optimizations. In the paper, we use TLBO and clonal selection algorithm to choose the optimal control parameters for the magnetic levitation controller. To verify the proposed algorithm, we compare control performances of the proposed method with the genetic algorithm and the particle swarm optimization. The simulation results show that the proposed method is more effective than conventional methods.

• 대한기계학회논문집
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• 제15권5호
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• pp.1620-1634
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• 1991

본 연구에서는 전기/자기 및 기계적 요소들이 복합되어 이루어진 자기부상 시 스템의 설현을 위한 기초단계로서 제어동역학(controlled dynamics) 측면에 입각한 모 델식을 본드선도 기법을 이용하여 보다 조직적으로 유도한다. 우선, 자속흐름 확장 및 자속 유출량을 고려하여 부상 시스템을 모델링하고 차량/레일 및 2차 현가(second ary suspension)장치를 포함한 자기부상 시스템을 모델링한다. 다음, 지지 및 안내 방향의 동역학을 동시에 고려한 2차원 자기부상 시스템을 본드선도의 다접점 필드(mu- ltiport field) 개념을 이용하여 모델링한다. 끝으로, 본드선도 기법으로 모델링된 2차원 자기부상 시스템의 안정도와 성능을 향상시키기 위하여 LOG/LTR(linear quadra- tic Gaussian control with loop transfer recovery) 제어시스템을 설계한다. LQG/ LTR 제어방법은 Doyle과 Stein에 의해 인성(stability-robustness) 문제와 주파수역 성능을 설계시에 직접 고려할 수 있는 강력한 선형 다변수 제어시스템 설곕방법으로 현재 널리 사용되고 있다.

• Journal of international Conference on Electrical Machines and Systems
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• 제3권3호
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• pp.312-316
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• 2014

This paper describes a turnout without movable parts for magnetically levitated vehicles with hybrid magnets, which have been studied by the authors in place of streetcars. Their low construction cost and low maintenance is key to their practical use. Magnetic levitation systems using forces of attraction can generate guidance force automatically, but the damping force against lateral motion is negligible. However, the lateral damping characteristic was improved by using divided iron type magnets and rails. Using this turnout without movable parts will facilitate smooth direction switching.

• 전기학회논문지
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• 제66권4호
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• pp.701-708
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• 2017

This paper proposes an optimum design method using Teaching-Learning-based optimization for the fuzzy PID controller of Magnetic levitation rail-guided vehicle. Since an attraction-type levitation system is intrinsically unstable, it is difficult to completely satisfy the desired performance through the conventional control methods. In the paper, a fuzzy PID controller with fixed parameters is applied and then the optimum parameters of fuzzy PID controller are selected by Teaching-Learning optimization. For the fitness function of Teaching-Learning optimization, the performance index of PID controller is used. To verify the performances of the proposed method, we use a Maglev model and compare the proposed method with the performance of PID controller. The simulation results show that the proposed method is more effective than conventional PID controller.

• 전력전자학회:학술대회논문집
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• 전력전자학회 2003년도 춘계전력전자학술대회 논문집(2)
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• pp.824-827
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• 2003

Recently, Development of Rare Earth Permanent magnet with the high remanence, high coercivity allow the design of brushless motors with very high efficiency over a wide speed range. Cogging torque is produced in a permanent magnet by magnetic attraction between the rotor mounted permanent magnet and the stator teeth. It is an undesired effect that contributes to the machines output ripple, vibration, and noise. This cogging torque can be reduced by variation of magnet arc length, airgap length, magnet thickness, shifting the magnetic pole and varying the radial shoe depth and etc. In this paper, Some airgap length and magnet arc that reduce cogging torque are found by FEM(Finite element method). The SPM type of high-capacity BLDC motor is optimized as a sample model.

• 한국정밀공학회지
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• 제20권2호
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• pp.25-32
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• 2003

Molding properties of etched surface pattern are presented. Injection molding has given attention on improving dimensional accuracy and productivity. However, the molding of etched surface pattern on plastic parts is not researched relatively for its additional values, which can meet design function and customer's attraction. Specimens, whose surface patterns are made by print-type etching, are investigated. The molding properties of surface pattern are estimated with roughness deviation of surface pattern on part and mold. The etching properties are related to physical properties of plastic materials and surface roughness of etched pattern. Also, flow mark and gate location can give influence on surface pattern molding. The experimental result can contribute to good molding of surface pattern in injection molding.

• 대한전기학회논문지
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• 제45권3호
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• pp.407-414
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• 1996

In this paper we consider the variable structure control for a class of discrete-time uncertain multivariable systems where the nominal system is linear. Discrete-time switching dynamics are introduced so that a new type of state trajectories called sliding mode may exist on the sliding surface by state feedback. The quantitative analysis for the matched uncertainties will show that every response of the system with the proposed switching dynamics is bounded within small neighborhoods of the state-space origin. Also, by the similarity transformation it will be shown that the eigenvalues of the closed-loop systems are composed of those of the subsystems which govern the range-space dynamics and null-space dynamics. It will be also shown that ideal sliding mode can be obtained in the absence of uncertainties due to one-step attraction to the sliding surface regardless of initial position of states. (author). 12 refs., 2 figs.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1999년도 하계학술대회 논문집 A
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• pp.354-356
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• 1999

Through the Standard of MCCB, the Adjustable Type Instant Trip Unit should NO trip at -20% of each current from $5{\times}In$ to $10{\times}In$ and trip +20% of those. In this paper, we obtain the attraction force between Fixing Magnet and Moving Armature. So we first made some samples. do experiments of weight, and simulated the modelling by 3D Maxwell S/W. With values of experiment and simulated values, we do design instant trip springs by using the ADAMS S/W of kinematic simulation. Finally we product the 250A Adjustable Instant Trip Unit, and it is very useful to our customers.

• 복식
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• 제43권
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• pp.109-124
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• 1999

This study was aimed to analyze consumer's wearing attitude and the purchase behavior of jeans and the jean manufacturer's marketing strategies. Subjects were 448 male and female in their teens twenties and thirties living in Seoul. Data were obtained by self-administered questions and analyzed by SAS package. The main findings of this research are as follows: factors of fashion pursuit famous brand pursuit sexual attraction pursuit practicality pursuit. 2. In analysis between jeans wearing attitude type of information source purchase behavior and demographic characteristics showed signicficant difference partially. 3. The most influential design of jeans purchase was a fitting factor. The consumers preferred low price shops in downtown and colledge area and department store because of it's variety of jean goods. So the market segmentation and the brand positioning method according to consumers' wearing attitude and purchase behavior should be concerned properly in maketing strategy design include product and advertising strategy.