• Journal of the Optical Society of Korea
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• 제5권2호
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• pp.39-42
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• 2001

A new method of switching mode in AFLC cell is proposed for faster switching time and higher contrast ratio. In this mode the ″dark″ state is obtained by applying negative full voltage while the ″bright″ state is achieved by applying positive full voltage to the cell. The switching time is reduced to 100 $mutextrm{s}$ for the cell whose switching time is 22 ms when operated in conventional mode. The contrast ratio is also improved vastly with this method. The possibility of achieving gray scale was shown in this mode of operation.

• Journal of Electrical Engineering and Technology
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• 제12권2호
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• pp.632-642
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• 2017

This paper presents an improved approach towards reducing the switching loss of insulated gate bipolar transistors (IGBTs) for a medium-capacity-class power conditioning system (PCS). In order to improve the switching performance, the switching operation is analyzed, and based on this analysis, an improved switching method that reduces the switching time and switching loss is proposed. Compared to a conventional gate drive scheme, the switching loss, switching time, and delay are improved in the proposed gate driving method. The performance of the proposed gate driving method is verified through several experiments.

• 대한전기학회논문지:전력기술부문A
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• 제52권12호
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• pp.713-721
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• 2003

This paper analyzes the switching overvoltage occurred on 345kV underground power cable system as well as combined transmission system using EMTP. Cable length and closing time, preinsertion resistance have effect on switching overvoltage. Therefore, this paper analyzes the switching overvoltage occurred on conductor and sheath with change of those parameters. Specially, the cross bonding position becomes discontinuity point because of the difference between surge impedance of metal sheath and that of lead cable. Thus, the transmission and the reflection of traveling wave complexly occur at this connection point. According to these influences, voltage between sheath and earth as well as voltage between joint boxes rise. Time to crest point of switching overvoltage is longer than lightning overvoltage. Even though the voltage induced by switching surge is smaller than lightning surge, that voltage may have serious effect on the metal sheath. Therefore, this paper also analyses the reduction effect of switching overvoltage when the preinsertion resistance of circuit breaker is considered.

• 한국의류학회지
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• 제25권8호
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• pp.1512-1523
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• 2001

The purposes of this study were to examine the effect of switching barrier perception on store loyalty in apparel product purchasing to classify the factors of switching barrier perception, and additionally ot identify differences of store loyalty and switching barrier perception according to demographic characteristics. The questionnaire was administered to 300 women shopped in a department store in Gwang-ju city during February 10-23, 2001. Data collected from 261 women were analyzed by using frequency, factor analysis, ANOVA, Duncan-test, regression analysis by SPSS for windows PC program. The results were as follows; 1. The consumer’s perceived switching barrier was composed of three factors; economic psychological, time factor. 2. There was significant difference in store loyalty according to consumer’s age, occupation, education level. and income. 3. There was significant differences in economic. time switching barrier perception according to consumers’age, occupation education level, and income. There was significant difference in psychological switching barrier perception according to consumers’ occupation education level, and income. 4. The swiching barrier perception significantly infulenced on the store loyalty.

• 항공우주시스템공학회지
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• 제9권1호
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• pp.12-18
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• 2015

The inter-conversion between different control laws in flight has a lot of risk. The SWM(Switching Mechanism) including logic and stand-by mode is designed to analyze the transient response of aircraft during inter-conversion between different control laws, based on the in-house software for non-real-time and real-time simulation. The SWM applies the fader logic of TFS(Transient Free Switch) to minimize the transient response of an aircraft during the inter-conversion, and applies the reset '0' type of the stand-by mode to prevent surface saturation due to integrator effect in the disengaged flight control law. The transition time is also important to minimize the objectionable transient response in the inter-conversion, as well as the transition control law design. This paper addresses the results of non-real-time simulation for the characteristics of transient response to different transition time to select the adequate transient time, and the real-time pilot evaluation, using SSWM(Software Switching Mechanism) and HSWM(Hardware Switching Mechanism), which is met for Level 1 flying qualities and assures safety of flight.

• 한국컴퓨터정보학회논문지
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• 제21권6호
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• pp.47-53
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• 2016

This paper deals with the capacity constrained time slot assignment problem(CTSAP) that a satellite switches to traffic between $m{\times}n$ ground stations using on-board $k{\leq}_{min}\{m,n\}$ k-transponders switching modes in SS/TDMA time-division technology. There was no polynomial time algorithm to solve the optimal solution thus this problem classified by NP-hard. This paper suggests a heuristic algorithm with O(mn) time complexity to solve the optimal solution for this problem. Firstly, the proposed algorithm selects maximum packet lengths of $\({mn \atop c}\)$ combination and transmits the cut of minimum packet length in each switching mode(MSMC). In the case of last switching mode with inefficient transmission, we applies a compensation strategy to obtain the minimum number of switching modes and the minimum makespan. The proposed algorithm finds optimal solution in polynomial time for all of the experimental data.

• 전기전자학회논문지
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• 제24권4호
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• pp.950-953
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• 2020

시변 신호의 1차 시간 미분을 추정하기 위해서 [1]에서 점근적 수렴 특성을 갖는 스위칭 미분기(switching differentiator)[1]가 제안되었으며, 그것의 고차 미분 추정으로 확장한 고차 스위칭 미분기(higher-order switching differntiaor, HOSD)가 [2]에서 제안되었다. 하지만 HOSD의 경우 n차 미분까지 추정한다면 결정해야 할 상수들의 개수가 2n개이므로 HOSD를 설계하는 데 있어서 다수의 설계상수를 결정해야 한다는 어려움이 있다. 본 논문에서는 HOSD의 점근적 추종 성능은 유지하면서 결정해야 할 설계 상수들의 개수를 줄이는 방법과 다양한 모의실험으로 구해진 최적의 설계 상수 값들을 제시한다. 시변 함수들의 시간 도함수를 추정하는 모의실험을 통해서 제시된 방법의 유효성을 보인다.

• 대한기계학회논문집A
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• 제26권8호
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• pp.1534-1544
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• 2002

The TDCSA(Time Delay Control with Switching Action) method, which consists of Time Delay Control(TDC) and a switching action of sliding mode control(SMC), has been proposed as a promising technique in the robust control area, where the plant has unknown dynamics with parameter variations and substantial disturbances are preset. When TDCSA is applied to the plant with saturation nonlinearity, however, the so-called windup phenomena are observed to arise, causing excessive overshoot and instability. The integral element of TDCSA and the saturation element of a plant cause the windup phenomena. There are two integral effects in TDCSA. One is the integral effect occurred by time delay estimation of TDC. Other is the integral term of an integral sliding surface. In order to solve this problem, we have proposed an anti-windup scheme method for TDCSA. The stability of the overall system has been proved for a class of nonlinear system. Experiment results show that the proposed method overcomes the windup problem of the TDCSA.

• 한국정보과학회:학술대회논문집
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• 한국정보과학회 2003년도 가을 학술발표논문집 Vol.30 No.2 (1)
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• pp.286-288
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• 2003

본 논문에서는 real-time환경에서 abnormal task를 자동 검출하여 시스템 overload 및 오 동작을 사전에 검출할 수 있는 방안을 제안한다. 본 논문에서 제안한 방안은 context switching이 발생하는 시점에서 각task들의 cpu 점유율 및 context switching 횟수를 분석하여 비정상적으로 높은 cpu 점유율을 가지는 task와 과도한 context switching을 일으켜 시스템에 overload를 주는 task들을 자동으로 검출한다. 이들 이용하여 신뢰성 있는 real-time시스템 설계 및 구현을 지원할 수 있다.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 1986년도 한국자동제어학술회의논문집; 한국과학기술대학, 충남; 17-18 Oct. 1986
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• pp.184-187
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• 1986

A time-division-mutiplexed switching system is implemented for connecting various computers and terminals in the laboratory environment.