• 한국정보통신학회:학술대회논문집
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• 한국정보통신학회 2013년도 추계학술대회
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• pp.361-364
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• 2013

기존의 DC-DC 부스트 변환기에서 사용되는 non-overlapping gate driver는 dead-time이 고정되어 있기 때문에 body-diode conduction loss 또는 charge-sharing loss가 발생하는 문제점을 가지고 있다. 이러한 손실을 줄이기 위해 사용된 기존의 적응제어 방식의 경우는 CCM 동작 시 전력트랜지스터가 동시에 on이 되는 구간이 발생하여 시스템 효율이 감소하는 문제점이 있다. 따라서 본 논문 에서는 이러한 문제점을 해결할 dead-time 적응제어 기능과 power switching 기능을 갖는 DC-DC 부스트 변환기를 설계 하였다. CMOS 0.35um 공정을 사용하였고, 2.5V 입력으로 3.3V의 출력전압을 얻으며, 스위칭 주파수는 500kHz 이다. 부하전류 150mA일 때 가장 높은 95.3%의 효율을 얻었다. 설계된 회로의 칩 면적은 $1720um{\times}1280um$이다.

• 한국전자파학회논문지
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• 제19권2호
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• pp.174-180
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• 2008

전원을 on/off하는 스위칭 방식을 이용한 펄스 증폭기는 입력 신호를 변조하는 방식에 비해 효율 및 잡음 특성이 우수하며, 입력단에 별도의 펄스 변조기가 필요 없어 회로가 간단하다. 현재 스위칭 방식의 펄스 증폭기는 스위칭 회로의 특성 상 rise 시간에 비해 fall 시간이 길어지는 단점이 있다. 본 논문에서는 fall 시간을 개선한 스위칭 회로를 제안하였다. 펄스 증폭기에 제안한 스위칭 회로를 적용하여 측정한 결과, 펄스 출력이 27 dBm에서 rise/fall 시간이 각각 5.7 ns, 21.9 ns인 결과를 얻었다.

• Journal of Communications and Networks
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• 제15권1호
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• pp.45-53
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• 2013

Multi-hop cellular networks (MCNs), which reduce the transmit power, mitigate the inter-cell interference, and improve the system performance, have been widely studied nowadays. The relay selection scheme is a key technique that achieves these advantages, and inappropriate relay selection causes frequent relay switchings, which deteriorates the overall performance. In this study, we analyze the conditions for relay switching in MCNs and obtain the expressions for the relay switching rate and relay activation time. Two mobile-based relay selection schemes are proposed on the basis of this analysis. These schemes select the relay node with the longest relay activation time and minimal relay switching rate through mobility prediction of the mobile node requiring relay and available relay nodes. We compare the system performances via simulation and analyze the impact of various parameters on the system performance. The results show that the two proposed schemes can obtain a lower relay switching rate and longer relay activation time when there is no reduction in the system throughput as compared with the existing schemes.

• 한국위성정보통신학회논문지
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• 제10권4호
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• pp.71-76
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• 2015

본 연구는 LTE, 5G의 무선 통신네트워크망에서 효율적으로 무선에너지하비스팅과 데이터 전송 실시하기 위한 시스템 모델을 제시한다. 수신 된 신호의 파워를 타임 스위칭(Time Switching)과 파워 스플릿팅(Power Splitting) 기법을 통해 우리가 원하는 무선에너지하비스팅 효율과 데이터 전송률을 만족시키기 위한최적의 타암 & 파워 비율을 찾는다. 그래서 최적의 시간 & 파워 비율을 선정함으로써 우리는 효율적으로 데이터 전송과 에너지하비스팅이 가능하다. 또 이상적인 수신기와 제안한 시스템 모델의 비교를 통해 성능 분석을 실시하고, 앞으로의 연구방향을 제시한다.

• Journal of Communications and Networks
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• 제8권2호
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• pp.228-233
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• 2006

Survivability is a very important requirement for the deployment of broadband networks because out of service links can affect volumes of traffic even if it is a very short time. And the data paths of broadband networks, which are critical for traffic engineering, are always necessary to be well protected. The procedure of protection or restoration for a path is initiated when failure is detected within the working path. In order to minimize the influence on transmission quality caused by the failure of links and to provide a definite time for the recovery from the failure, the protection switching time (PST) should be carefully considered in the path arrangement. Several researches have been devoted to construct the protection and restoration schemes of data paths over dense wavelength division multiplexing (DWDM) networks, however, there was rare research on the design of data paths with guaranteed protection switching time. In this paper, the PST-guaranteed scheme, which is based on the concept of short leap shared protection (SLSP), for the arrangement of data paths in DWDM networks is proposed. The proposed scheme provides an efficient procedure to determine a just-enough PST-guaranteed backup paths for a working path. In addition to selecting the PST-guaranteed path, the network cost is also considered in a heuristic manner. The experimental results demonstrate that the paths arranged by the proposed scheme can fully meet the desired PST and the required cost of the selected path is competitive with which of the shared path scheme.

• Journal of the Korean Data and Information Science Society
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• 제26권4호
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• pp.997-1006
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• 2015

In industrial quality control, when engineers use VSI control procedure they should consider both required time to signal and switching behaviors together in the case of production process changed. Up to the present, many researchers have studied fixed sampling interval (FSI) chart and variable sampling interval (VSI) chart in the points of average number of samples to signal (ANSS) and average time to signal (ATS). However, ANSS and ATS do not provide any switching information between different sampling intervals of VSI schemes. In this study, performances of two sampling intervals VSI chart and three sampling intervals VSI chart are evaluated and compared. The numerical results show that ANSS and ATS values of two sampling intervals VSI chart and three sampling interval VSI chart are similar regardless the amount of shifts. However, the values of switching behaviors including ANSW are less efficient in three sampling intervals VSI charts than in two sampling intervals VSI chart.

• 대한전자공학회논문지
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• 제17권6호
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• pp.86-92
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• 1980

다단스위칭 회로를 구성하고 있는 트랜지스터의 스위칭 동작을 베이스전압과 단위 스텝 응답함수의 특성을 고려하여 해석 하였으며 트랜지스터의 축적시간을 고려하면 트랜지스터를 시간지연소자로 간주할 수 있다고 보고 이를 이용하여 IC화 할 수 있는 시간지연 회로 및 발진회로를 제시하였다.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1996년도 하계학술대회 논문집 C
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• pp.1547-1549
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• 1996

The electrical and optical switching characteristics of gold-doped silicon p-i-n diodes have been investigated. The device shows a dark switching voltage of about 500 V. The switching voltage decreases rapidly when the illumination level is increased. The differential sensitivity of optical gating over linear region is $d(V_{Th}/V_{Tho})/dP_{Ph}$=0.25/uW. The turn-on delay time and the turn-on rise time decrease with increasing optical pulse power. The turn-off delay and the fall time are negligible.

• Communications for Statistical Applications and Methods
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• 제25권1호
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• pp.29-42
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• 2018

We combine the integer-valued GARCH(1, 1) model with a generalized regime-switching model to propose a dynamic count time series model. Our model adopts Markov-chains with time-varying dependent transition probabilities to model dynamic count time series called the generalized regime-switching integer-valued GARCH(1, 1) (GRS-INGARCH(1, 1)) models. We derive a recursive formula of the conditional probability of the regime in the Markov-chain given the past information, in terms of transition probabilities of the Markov-chain and the Poisson parameters of the INGARCH(1, 1) process. In addition, we also study the forecasting of the Poisson parameter as well as the cumulative impulse response function of the model, which is a measure for the persistence of volatility. A Monte-Carlo simulation is conducted to see the performances of volatility forecasting and behaviors of cumulative impulse response coefficients as well as conditional maximum likelihood estimation; consequently, a real data application is given.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2009년도 춘계학술대회 논문집
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• pp.63-64
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• 2009

Optical bounce during switching in the fringe field switching (FFS) mode using a liquid crystal (LC) with positive dielectric anisotropy has been observed. According to the analysis, it occurs at two positions which are center and edge of the pixel electrode, which decreases decaying response time. The former is major and mainly associated with increase in twist angle instantaneously during switching off resulted from decrease in tilt angle near by LC molecules at center. This paper discusses the origin of such optical bounces.