• Proceedings of the KIPE Conference
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• 2013.07a
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• pp.20-21
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• 2013

본 논문에서는 양방향 충전기용 DC/DC 컨버터와 같이 입력전압과 출력전압이 가변하는 제어시스템에서 비시변 시비율 전달함수를 구현하여 제어특성을 개선하고자 한다. 기존제어기 설계에 의해 설계된 이득을 사용하여 제어를 행할 경우 입력전압의 변동에 따라 제어특성이 가변한다. 전압제어기의 각 이득을 시비율의 역수를 취하여 변화함으로서 전체 제어블록에서 시비율 항을 등가적으로 제거할 수 있는 방법이다. 따라서 본 논문에서 제안된 비시변 시비율 전담함수를 양방향 충전기용 DC/DC컨버터에 적용하여 PSIM을 이용한 시뮬레이션과 실험을 통해 타당성과 우수성을 검증하였다.

• Proceedings of the KIEE Conference
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• 2006.07b
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• pp.933-934
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• 2006

본 논문에서는 새로운 양방향 ZVS PWM Sepic/Zeta 컨버터를 제안한다. 제안한 컨버터는 PWM 제어가능한 컨버터로서 입력과 출력전압의 극성이 같은 비반전 컨버터의 특징을 지니며 DC 전압의 전달함수가 양방향 모두 M=D/(1-D)로 동일하다. 또한 각방향으로 전력전달시 다이오드와 병렬로 연결된 MOSFET가 다이오드의 'ON'시 동시에 'ON'되어 Sychronous Rectifier로 동작하므로 도통손을 저감하였으며, Auxiliary Resonant Commutated Pole를 사용하여 저감된 스위칭 손실을 갖는 특성을 지니고 있다. 또한 Transformer 버전이 존재하므로 입력과 출력사잉에 전기적 절연을 필요로 하는 실제응용에 유용하게 사용할 수 있다.

• 한국정보통신설비학회:학술대회논문집
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• 2005.08a
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• pp.180-183
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• 2005

광주파수에서 대역을 나누어주는 광필터를 이용하여, 기존의 2 코어를 이용한 단방향 광통신을 1 코어를 이용한 양방향 통신으로 전환하여 광선로 절감효과를 얻을 수 있다. 그러나 그런 양방향 통신에서 CWDM (coarse wavelength-division multiplexing) 광채널들에 대한 채널 감시가 요구된다. 정확한 정보전달을 위하여 광원의 특성을 모니터하고, 또한 보드의 신호 레벨에서 감시를 통하여 신호의 오전달을 감시한다. 본 발표논문에서는 광선로 절감에 따른 CWDM 광채널의 성능 개선을 위한 감시기술에 대하여 설명하고, 망교체시에 다른 선로에 영향을 최소로 하는 적절한 감시기술을 설명한다.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.18 no.5
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• pp.1149-1154
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• 2014

To observe the tunneling phenomenon of oxide semiconductor transistor, The Indium-gallum-zinc-oxide thin film transistors deposited on SiOC as a gate insulator was prepared. The interface characteristics between a dielectric and channel were changed in according to the properties of SiOC dielectric materials. The transfer characteristics of a drain-source current ($I_{DS}$) and gate-source voltage ($V_{GS}$) showed the ambipolar or unipolar features according to the Schottky or Ohmic contacts. The ambipolar transfer characteristics was obtained at a transistor with Schottky contact in a range of ${\pm}1V$ bias voltage. However, the unipolar transfer characteristics was shown in a transistor with Ohmic contact by the electron trapping conduction. Moreover, it was improved the on/off switching in a ambipolar transistor by the tunneling phenomenon.

• The Journal of Society for e-Business Studies
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• v.27 no.2
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• pp.175-192
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• 2022

Artificial intelligence-based natural language processing technology is playing an important role in helping users write English-language documents. For academic documents in particular, the English proofreading services should reflect the academic characteristics using formal style and technical terms. But the services usually does not because they are based on general English sentences. In addition, since existing studies are mainly for improving the grammatical completeness, there is a limit of fluency improvement. This study proposes an automatic academic English editing methodology to deliver the clear meaning of sentences based on the use of technical terms. The proposed methodology consists of two phases: misspell correction and fluency improvement. In the first phase, appropriate corrective words are provided according to the input typo and contexts. In the second phase, the fluency of the sentence is improved based on the automatic post-editing model of the bidirectional recurrent neural network that can learn from the pair of the original sentence and the edited sentence. Experiments were performed with actual English editing data, and the superiority of the proposed methodology was verified.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.40 no.1
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• pp.183-186
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• 2015

Recently, the demand for the safety and the information delivery system in the ship increases. The deployment of the wireless sensor networks instead of using the built-in wired networks or the setup of the new wired networks is more desirable than the deployment of the wired networks in a ship after its final production since it can reduce the cost and the time of the brand new wired networks by deforming some of the internal structure of the ship. In this paper, the shipboard signal propagation measurement system based on the signature sequence-two way slave mode are designed and its measurement data are analysed after measuring the signal propagation characteristics. Consequently, it is expected that the reliable and cost-effective signal measurement system for the deployment of the shipboard wireless networks can be built.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.42 no.1
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• pp.64-76
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• 2017

Routing in mobile ad hoc networks (MANETs) is highly challenging because of the dynamic nature of network topology. AntHocNet is a bio-inspired routing protocol for MANETs that mimics the foraging behavior of ants. However, unlike many other MANET routing protocols, the paths constructed in AntHocNet are unidirectional, which requires a separate path setup if a route in the reverse direction is also required. Because most communication sessions are bidirectional, this unidirectional path setup approach is often inefficient. Moreover, AntHocNet suffers from looping problems because of its property of multiple paths and stochastic data routing. In this paper, we propose a modified path setup procedure that constructs bidirectional paths. We also propose solutions to some of the looping problems in AntHocNet. Simulation results show that performance is significantly enhanced in terms of overhead, end-to-end delay, and delivery ratio when loops are prevented. Performance is further improved, in terms of overhead, when bidirectional paths setup is employed.

• Proceedings of the KIPE Conference
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• 2016.07a
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• pp.245-246
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• 2016

본 논문에서는 지능형 반도체 변압기를 구성하는 양방향 DC-DC Dual Active Brldge(DAB) 컨버터의 소신호 모델과 전달함수의 분석을 통해 컨버터의 안정도와 동작 특성을 파악하고, 이를 통해 동 특성 및 정상상태의 안정성을 향상시킬 수 있는 제어기 설계 방안을 제안한다.

• Proceedings of the KIPE Conference
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• 2014.07a
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• pp.307-308
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• 2014

듀얼 액티브 브릿지 컨버터는 고전력 전달에 유용한 절연형 양방향 컨버터이다. 듀얼 액티브 브릿지 (DAB) 컨버터의 가장 간단한 제어 방식은 고주파 변압기의 일차단과 이차단의 위상 차이를 통해 전달 전력을 제어하는 위상천이변조 (PSM) 방식이다. 그러나 위상 변동 방식을 이용하면 경부하 상황에서 소프트 스위칭이 이루어지지 않으며 순환 전류 또한 크게 발생하여 변환 효율이 낮아지게 된다. 본 논문에서는 위상 및 듀티가 변동된 컨버터의 최적 동작점을 파악하기 위한 DAB 컨버터의 운용 특성 연구를 수행하였다. 컨버터의 위상과 듀티에 따른 동작 파형, 경계 조건, RMS 전류, 소프트스위칭의 여부 등이 분석되었다.

• The Journal of Korea Institute of Information, Electronics, and Communication Technology
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• v.14 no.1
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• pp.56-69
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• 2021

In this paper, the PV system with a link to the commercial system needs some advantages like small capacity, high power factor, high reliability, low harmonic output, maximum power operation of solar cell, and low cost, etc. as well as the properties of inverter. To transfer the PV energy of photovoltaic power generation system to the system and load, it requires PCS in both directions. The purpose of this paper is to confirm the stable power supply through the load leveling by presenting the PCS considering ESS of photovoltaic power generation. In order to achieve these purpose, 5 step process of operation mode algorithm were used according to the solar insolation amount and load capacity and the controller for charging/ discharging control was designed. For bidirectional and effective energy transfer, the bidirectional converter and battery at DC-link stage were connected and the DC-link voltage and inverter output voltage through the interactive inverter were controlled. In order to prove the validity of the suggested system, the simulation using PSIM was performed and were reviewed for its validity and stability. The 3[kW] PCS was manufactured and its test was conducted in order to check this situation. In addition, the system characteristics suggested through the test results was verified and the PCS system presented in this study was excellent and stronger than that of before system.