• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 2004년도 ICCAS
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• pp.1838-1842
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• 2004

Gain and phase margins of a first order plus delayed time (FOPDT) process controlled by generalized predictive controller (GPC) are related to the control parameters ${\lambda}$ (control move suppression parameter) and ${\alpha}$ (smoothing filter coefficient) and the normalized delay of the process. Variation ranges of gain and phase margins are determined. It is shown that the margins cannot be assigned independently for a wide range of variation and the range is narrowing by increase of the normalized delay of the process. And finally curves are given to use for adjustment of the controller parameters in order to obtain a specific pair of gain and phase margins.

• 전력전자학회:학술대회논문집
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• 전력전자학회 1998년도 Proceedings ICPE 98 1998 International Conference on Power Electronics
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• pp.374-379
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• 1998

This paper proposes a control method for three-phase PWM rectifier using only single current sensor in DC link. A PWM modulation strategy for reconstructing three phase current from the DC link current is given. The states of the rectifier switch are modified so that all phase currents can be reconstructed in a switching period although one of active vectors is applied only for a short time. Therefore, a novel current control using an adjustment scheme of the modulation signal for a three-phase PWM rectifier will be discussed, and verified with the experimental results.

• 한국ITS학회 논문지
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• 제11권2호
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• pp.39-47
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• 2012

본 연구에서는 수도권을 중심으로 구축 운영 중에 있는 ITS 무선통신 인프라인 UTIS를 활용하여 긴급차량 우선신호제어 시스템을 개발하였다. 신호교차로에서 긴급차량의 연속주행과 일반차량의 제어지체를 최소화하는 긴급차량 우선신호제어 시스템 구현을 위해 긴급차량의 진행방향(직/좌)을 사전에 파악이 가능하도록 하였으며, 긴급차량 우선신호 제어 방식을 현시삽입과 현시조정 모드로 구분하여 개발하였다. 또한, 시스템에 대한 현장 적용 가능성을 평가하기 위해 CORSIM 모형의 RTE 기능 활용을 통해 HILS 기반의 평가 시스템을 구성하여 EVP 제어 효과에 대한 검증을 수행하였다. 본 연구를 통해 개발된 긴급차량 우선신호제어 시스템은 기 구축된 ITS 인프라를 활용한 것으로 현장 적용 시 경제적이고 효율적인 구축이 가능할 것으로 기대된다.

• 조명전기설비학회논문지
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• 제28권5호
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• pp.115-121
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• 2014

The intrinsic simplicity, ruggedness, and simple power electronic drive requirement of a Switched Reluctance Motor(SRM) make it possible to use in many commercial adjustable speed application. The simple magnetic circuit results in a high efficiency drive and low temperature rise, and the drive system provides a good drive characteristics. This paper is provides two phase 4/3 SRM that is similar to two phase 6/3 SRM as aspect to magnetic structure. Although 6/3 SRM does not experience any flux reversal as the flux is in the same direction whether phase A or B is excited, but two phase 4/3 SRM experiences a flux reversal in small part of stator yoke. The flux reversal in two phase 4/3 SRM could be relieved by an adjustment of stator yoke structure. The magnetic analysis and design considerations of the two phase 4/3 SRM have been obtained by the finite element method analysis (FEM).

• Journal of applied mathematics & informatics
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• 제7권1호
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• pp.237-245
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• 2000

In this paper, we consider to the adjustment weighting procedure in the two phase sampling scheme. In general, the unit nonresponses may be occured in the final survey operation. When the unit nonresponse be generated in survey, it is able to use the auxiliary variable for estimating of interest variable. In this viewpoint, we use the two kinds level of auxiliary variable, $X_{1k}$ and $X_{2k}$ for the calibration procedure. We proprose the two-step Newton's method in the calibration estimation procedure for the two phase sampling.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2011년도 정기총회 및 추계학술대회 논문집
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• pp.1511-1516
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• 2011

The maintenance of the turnout is composed of signal field and track field on business, the electrical and mechanical field on system. adjustment and maintenance carry forward through coordination with these fields. In the case of turnout equipment used in a first phase of Seoul-Busan high-speed train, it is treated by classifying as mechanical adjustments and electrical adjustments. Mechanical adjustment is conducted with focus on fine adjustment to meet maintenance standards limits(1mm or less) about interval of basic rail and tongue rail about each part of track transition equipment. This refers to mechanical adjustments performed mainly with physical changes and movement characteristics between basic rail and tongue rail by considering the overall environment surrounding track side of section installed track transition equipment. However, these series of maintenance are conducted in state that high-speed train is not in the process from 1 am to 4 am at night, but common workers for maintenance are not familiar with the operation and checking about various situation, and the workers are even insufficient. Maintenance training using mixed reality is conducted in the place of business, we tried to overcome several problems of safety and time reduction through this training.

• Communications for Statistical Applications and Methods
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• 제22권5호
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• pp.519-530
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• 2015

The geometric chart has proven more effective than Shewhart p or np charts to monitor the proportion nonconforming in high-quality processes. Implementing a geometric chart commonly requires the assumption that the in-control proportion nonconforming is known or accurately estimated. However, accurate parameter estimation is very difficult and may require a larger sample size than that available in practice in high-quality process where the proportion of nonconforming items is very small. Thus, the error in the parameter estimation increases and may lead to deterioration in the performance of the control chart if a sample size is inadequate. We suggest adjusting the control limits in order to improve the performance when a sample size is insufficient to estimate the parameter. We propose a linear function for the adjustment constant, which is a function of the sample size, the number of nonconforming items in a sample, and the false alarm rate. We also compare the performance of the geometric charts without and with adjustment using the expected value of the average run length (ARL) and the standard deviation of the ARL (SDARL).

• 한국과학교육학회지
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• 제39권3호
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• pp.321-335
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• 2019

본 연구는 학생 경험이 과학 자기효능감 향상에 어떻게 영향을 주었는지를 탐색하여, 이를 바탕으로 과학 자기효능감 향상 과정에 대한 구조적 모형을 제안하였다. 본 연구에는 자연계열 고등학생 25명이 연구에 참여하였다. 근거이론에 의한 면담 자료의 코딩을 통해 과학 자기효능감과 관련된 10개의 범주를 도출하고 패러다임 분석을 통해 과학 자기효능감 향상 과정 모형을 개발하였다. 연구 결과, '과학 학습에 대한 기대감'을 가진 학생들이 자연계열을 선택하여 과학을 학습하는 과정에서 '과학 학습에 대한 개인 역량'과 '외부에서의 영향'의 맥락 작용을 통해 과학 자기효능감의 향상이 이루어지며, '내재적 불안 요인'과 '외재적 요인'의 중재적 조건을 받으며, 도입, 향상, 조절, 결과의 4단계를 순환하는 것을 알 수 있었다. 이때 중심현상은 '과학 자기효능감 향상'이다. 본 연구 결과는 교육현장에서 학생의 과학 자기효능감에 영향을 주는 교수전략 개발에 필요한 기초 정보를 제공한다.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 1997년도 한국자동제어학술회의논문집; 한국전력공사 서울연수원; 17-18 Oct. 1997
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• pp.1864-1866
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• 1997

Uncertainties in the aerodynamic coefficients or time delay effects in implementing an autopilot algorithm can make a Flight Control System(FCS) unstable. When a FCS enters unstable state, the actuator or sensor limiters in FCS make the unstable system not diverge but be in the state of stable limit cycle. If an autopilot recognize the FCS to be in the stable limit cycle phenomenon, it woudl be better to adjust autopilot gains to stabilize the FCS. A novel method to stabilize a FCS using parameter estimation and maintenance of given phase margin is proposed. The method is applied to roll control loop and verified its performance.

• 전력전자학회:학술대회논문집
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• 전력전자학회 2010년도 하계학술대회 논문집
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• pp.536-537
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• 2010

If DC voltage adjustment can be controlled very easily, it is much more effective rather than AC in transmission efficiency. The main reason why DC is more effective than AC, DC has the same role as the 70[%] of AC whenever the same power send. In addition, AC streams the surface of electrical wire, but DC streams overall of electrical wire. Digital load, which is operated by DC, has increased in modern times. The step of convert of AC-DC has to be reduced. When we turn the dispersed AC-DC converters into the concentrated AC-DC converter, it can improve the effective of the whole system. Further more, if digital society develops more than now and the time of electric vehicle comes, the need of DC will increase much more than these days. This paper suggests that DC output of distributed power source and high efficient 3 phase PWM converter can control the adjustment of output voltage, harmonic restraint, power factor improvement and dump power.