• 대한전자공학회:학술대회논문집
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• 대한전자공학회 1999년도 추계종합학술대회 논문집
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• pp.1049-1052
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• 1999

As the Internet traffic increases, the demand for higher performance routers continues to grow, and it makes switch chips more complex. To make matters worse, these chips also need to handle high-level services. In this paper, we introduce an efficient verification methodology that can support real network traffics to satisfy the verification requirement of real complex situation even at the early design phase of switch chips.

• 전기학회논문지
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• 제61권9호
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• pp.1300-1305
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• 2012

A triaxial Blumlein pulse forming line has been designed to generate a pulse whose voltage is ~300 kV, pulse duration is ~5 ns, and rise time is ~500 ps. It turns out, however, that the rise time of the pulse becomes much longer than 500 ps due to parasitic inductances and capacitances existing inside the system. A peaking switch has been developed to shorten the rise time of the pulse from Blumlein pulse forming line. In the peaking switch, a wedge-shaped dielectric material (MC 901 nylon) is employed to surround the electrode on the antenna side. This shape inhibits an abrupt change of the output impedance, thereby minimizing the reflection of the output pulse. Experimental results show that the peaking switch is capable of improving the rise time of the pulse at a level of 500 ps.

• 전기학회논문지
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• 제62권4호
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• pp.467-473
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• 2013

The addition of disconnect switches to a distribution feeder or the replacement of the manual switches with the automatic switches do, in general, increase reliability by decreasing the duration of the outage of many to the customers on the feeder and reducing the outage section. However, the improvement of reliability in power distribution system causes an increase of the investment cost, for example, replacement costs, labor costs, and so on. For this reason - the balance between investment and reliability improvement - many studies about the appropriate level of investment have been conducted. In this paper, we suggest the algorithm for determining the reasonable switch automation rate in the power distribution system. We evaluate the customer interruption cost and reliability for several cases - these cases relate with the switch automation rate - in the domestic metropolitan power distribution system, estimate the effectiveness of changing the manual switch to automatic switch quantitatively. These results can help the determining on the disconnect switch's automation rate.

• 대한산업공학회지
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• 제26권1호
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• pp.54-65
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• 2000

The objective of this study is to evaluate the operator performance relating to hand switches with two or three buttons in the main control rooms of nuclear power plants. Based on the comparative analysis of the nuclear power plants, two different subjective workload-rating scales were used to evaluate the performance of 48 operators: the Overall Workload(OW) and National Aeronautics and Space Administration Task Load Index (NASA TLX). The survey questions consisting of the eight-items were asked to evaluate the operating experiences for the two different switch types. The OW scales ratings were applied to measure the workload of the switch-related tasks. The ratings revealed that signal detection tasks caused less workload in the three-buttoned-switch operators than the other switch group. However, in the switch operation tasks, the switch types did not show statistically significant effects on workload level. The NASA TLX scale ratings were performed based on detailed task scenarios that assumed the accident of small break loss of coolant, what we call, the small LOCH. The NASA TLX was administered to three different task groups: the reactor, the turbine, and the electric operator groups. Based on the NASA TLX, the two-buttoned switch groups showed higher workload than those with the three-buttoned switches. However, a statistically significant difference was found only in the reactor operator groups. When the current switch type was assumed to be changed for the other type, all of the three-buttoned switch groups were predicted to have higher workload than the other switch groups, respectively. The implications of these findings were discussed.

• ETRI Journal
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• 제43권5호
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• pp.799-811
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• 2021

This paper considers a challenging problem: to simultaneously optimize the cost and the quality of service in opaque wavelength division multiplexing (WDM) networks. An optimization problem is proposed that takes the information including network topology, traffic between end nodes, and the target level of congestion at each link/ node in WDM networks. The outputs of this problem include routing, link channel capacities, and the optimum number of switch ports locally added/dropped at all switch nodes. The total network cost is reduced to maintain a minimum congestion level on all links, which provides an efficient trade-off solution for the network design problem. The optimal information is utilized for dynamic traffic in WDM networks, which is shown to achieve the desired performance with the guaranteed quality of service in different networks. It was found that for an average link blocking probability equal to 0.015, the proposed model achieves a net channel gain in terms of wavelength channels (𝛾_w) equal to 35.72 %, 39.09 %, and 36.93 % compared to shortest path first routing and 𝛾_w equal to 29.41 %, 37.35 %, and 27.47 % compared to alternate routing in three different networks.

• 전기학회논문지
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• 제64권2호
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• pp.268-275
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• 2015

This paper proposes a method of switching to improve power loss for the single-phase three-level NPC inverter. The conventional switching methods, which are called as the bipolar and unipolar switching methods, are used for single phase inverters using three-level topology. However, these switching method have disadvantage in the power loss. Because all of the switch are operated. To reduce the power loss of the three-level NPC inverter, clamp switching method is introduced in this paper. This way, one of the lag is fixed that switching loss is reduced. This paper analyzes and compares power losses of unipolar method and clamp method. The validity of the power loss analysis is verified through the simulation and experimental results.

• Journal of Power Electronics
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• 제16권1호
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• pp.173-181
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• 2016

In this paper, a new technique for harmonic optimization in cascaded H-bridge 7-level inverters is proposed. The suggested strategy is based on minimizing an objective function which simultaneously optimizes the converter utilization and Total Harmonic Distortion (THD). The Switch Utilization Ratio (SUR) is formulized for both the phase and line-line voltages of a 7-level inverter and is considered in the final objective functions. Based upon the SUR formula, utilization ratio enhancement will reduce the value of feeding DC links, which improves the efficiency and lifetime of the circuit components due to lower voltage stresses and losses. In order to achieve more effective solution in different modulation indices, it is assumed that the DC sources can be altered. Experimental validation is presented based on a three-phase 7-level inverter prototype.

• 한국인터넷방송통신학회논문지
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• 제10권5호
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• pp.245-249
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• 2010

현재 차량에서 일반적으로 많이 쓰이고 있는 변속 스위치의 방법은 전위차를 신호로하는 접촉식이다. 접촉식은 신호전달에 있어서 정확한 방식의 하나이지만 장시간 사용 시 접촉면의 노후화로 인하여 수명이 짧아진다. 비 접촉 방식으로 사용될 수 있는 자기센서를 사용 한다면 접촉면의 노후화를 해결 할 수 있다. 본 논문에서는 자기센서의 특징을 살려서 비 접촉식 방법으로 차량용 변속스위치에 적용 하여 기존 접촉식 방법의 문제를 해결하였다. 센서 출력 전압은 가변적인 전위차를 가지는데 스위치의 각동에 따라 통상 0mV에서 150mV의 값을 가진다. 본 연구에서는 5개의 상태 신호에 대한 두 개의 사인 신호를 사용 하였다.

• 한국컴퓨터정보학회논문지
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• 제8권3호
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• pp.100-106
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• 2003

ATM망은 개방형 통신망에서 다양한 서비스 와 QOS를 지원하며 대역폭 확장을 통한 망 자원의 효율성과 융통성을 제공한다. 그러나 이런 트래픽 들에 대한 품질 서비스에 대한 연구가 많이 진행되고 있으나 트래픽 보안을 안전성 검사는 연구대상 부분이 많이 존재한다. 본 논문에서는 ATM FORUM 보안그룹에서 정한 ATM Security Specification 1.1 중심으로 보안서비스 개념을 소개하고 외부망에서 내부망으로 들어오는 패킷들을 보안을 위한 안정성기준으로 효율적으로 처리하는 스위치와 결합한 방화벽처리 루틴 및 CAC 루틴을 소개한다. 패킷들의 안전성 등급을 분류처리 하기 위하여 SSC(Special Service Cell)를 도입한다. 본 논문에서는 스위치 처리량, 셀 지연등을 위한 시뮬레이션 시나리오을 제안한다.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2007년도 춘계학술대회 논문집 전기기기 및 에너지변환시스템부문
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• pp.187-193
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• 2007

This paper presents the Efficiency Characteristic of Three-Level Converter. Three-Level DC/DC Converter Presented in this paper is used a phase shift control with a flying capacitor in the primary side to achieve ZVS for the outer switch. This converter reduces the voltage stress across the main switch to half of input voltage. This paper analyses the loss of each component and the various losses for efficiency variation. The result of the analysis are verified using 3kW prototype.