• Proceedings of the KIPE Conference
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• 2017.07a
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• pp.82-83
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• 2017

본 논문에서는 수 kW급 이상을 위한 3상 전류원 3스위치 푸쉬풀 컨버터를 제안한다. 제안하는 컨버터는 무손실 스너버를 이용하여 모든 다이오드의 ZCS 턴오프와 스위치의 ZVS 턴온 및 턴오프를 성취한다. 무손실 스너버는 작은 정격을 가지며 메인회로와 무관하게 동작하는 장점이 있다. 5kW급 시작품으로부터 제안한 컨버터의 타당성 및 성능을 검증하였다.

• Proceedings of the KIPE Conference
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• 2012.07a
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• pp.179-180
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• 2012

본 논문에서는 3상 양방향 푸시풀 컨버터의 최적 PWM 기법을 제안한다. 제안하는 DAPWM 기법은 모든 스위치 ZVS 턴온을 성취하며 낮은 턴 오프 전류를 갖는 특징이 있다. 또한 동일한 승 강압 게이트 신호 발생 패턴으로 모드전환에 따른 과도상태를 최소로 할 수 있다. 기존 스위칭 방식들과의 성능을 비교하고 5kW급 시작품을 통해 제안한 방식의 타당성 및 성능을 검증하였다.

• The Journal of the Convergence on Culture Technology
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• v.6 no.4
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• pp.179-186
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• 2020

Wongyo Lee KwangSa (1705~1777) is a scholar and artist who represented an era in the period of change and revival of Korean culture and art in the 18th century. In 1755 (31st Yeongjo), he was transferred to Sinjido due to the Naju Byeokseo Incident, and died in exile for a total of 23 years. He tried to correct the problems of the flow of calligraphy in common writing and the flow of calligraphy in the Joseon Dynasty, and wrote 『Wonkyo Seogyeol』. By realizing an original artistic state that is evaluated as having completed the 'Dongguk Jinche', which is a unique and subjective and self-conscious calligraphic flow of the Korean people who wants to reestablish the essence of calligraphy, it has had an absolute influence on the Honam area. Wonkyo's calligraphy aesthetics are developed into the beauty of ChanggyeongBalsog based on Shimjin of Yangminghak, Yanggangmi of Power of controlling all the stands of brush hair, and Vitality of Push out the brush with all your might. He recognized free sculpting and energetic, muscular strokes as the key to calligraphy, and suggested honing the old tombstones written in JeonYe. Vibrant stroke means that Cheongi naturally permeates in the midst of Samgwa and Gilgok, and the brush is operated with Push out the brush with all your might of Power of controlling all the stands of brush hair. These calligraphy aesthetics radiated sinchae with geungol and singi, and were expressed in Wongyo font, full of vitality as a living creature, pursuing the unique pilgrimage and pilgrimage unique to our nation, revealing the true nature of nature.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.22 no.12
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• pp.1060-1068
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• 2011

In this paper, Current-Mode Class-D(CMCD) RF Power Amplifier(PA) is designed and implemented at 900 MHz. Conventional CMCD PA has output parallel resonator to reconstruct a fundamental frequency component of the output signal. However the resonator can be removed by connecting inverse class-F PAs because even-harmonic components can be removed by CMCD PA's push-pull structure. Using load-pull, inverse class-F PA with GaN transistors is designed, and CMCD PA with the inverse class-F PA is implemented. The CMCD PA has 64.5 % drain efficiency, 34.2 dBm output power. Comparing with the drain efficiency of a CMCD PA with parallel resonator, the CMCD with the inverse class-F technology has 13.6 % improved drain efficiency.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.16 no.7
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• pp.4878-4883
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• 2015

The IP Multimedia Subsystem(IMS) is a framework that provides access to the content of Internet and Telecom services anytime and anywhere with guaranteed Quality of Service(QoS) and manageability by separating control functions from bearer and services. The Service Delivery Platform(SDP) provides common interfaces and protocols to deploy existing or new services in an efficient way. Therefore SDP over IMS plays a role of bridge between established network and new IMS network by simplifying the interaction among application services. In order to enrich the multimedia network communication, we try to deploy the Push-to-talk over Cellular(PoC) service which is considered as the outstanding and distinguished half-duplex Voice over IP(VoIP) application service among deployable candidate services over mobile network. In this paper we investigate the advantages of PoC service and PoC architecture firstly, and then focus on the its practical implementation for the prototype to validate the feasibility of its deployment and realization.

• Journal of Advanced Navigation Technology
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• v.21 no.1
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• pp.66-71
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• 2017

This paper describes implementation of a 165 MHz, 5 kW RF high power amplifier (HPA) for particle accelerator applications. The HPA consists of a drive amplifier for main amplifiers driving, sixteen 600 W class-AB push-pull power amplifier pallets and Wilkinson power divider/combiner using lumped LC components, which are divided/combined power amplifier pallet outputs. To detected the amplifier circuit of normal and reflected output power conditions, we used a bidirectional coupler. To radiate heat of main power amplifier, we were used an water-cooled copper plates to go through a water for radiation of heat. The HPA of center frequency 165 MHz has archived an efficiency of 62.5 % at 5 kW of power level experimentally.

• Proceedings of the KWS Conference
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• 2009.11a
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• pp.21-21
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• 2009

현장의 GMA 용접기는 일반적으로 용접기 본체로부터 와이어 송급장치까지의 거리가 약 50m 정도 떨어져 있고 송급장치로부터 토치까지의 거리는 약 3~5m 정도이다. 특히 국산 GMA 용접기의 와이어 송급장치는 DC 모터의 일종인 프린트모터를 사용하고 있으며 제어기는 오픈루프 제어를 하고 있다. 따라서 와이어 송급속도의 변동을 보상할 수 있는 어떤 수단도 장착되어 있지 않다. 또한 송급장치와 토치간 와이어를 안내하는 케이블 도관의 마찰 때문에 토치 끝단에서의 와이어 송급속도가 불규칙해질 수밖에 없다. 용접 시 와이어 송급속도의 순간적인 변동 때문에 용접부의 전류 파형이 매우 불규칙해지고 이 때문에 용융된 용적이 용융풀로 이행하지 못하고 스패터로 비산하는 현상을 발생시킨다. 본 연구에서는 이를 해결하고자 국산 SCR 용접기 및 인버터 용접기와 호환 가능한 디지털 제어형 와이어 송급장치와 Push-Pull 용접 토치를 개발하였다. 또한, 개발된 시스템을 이용하여 정 역 방향 제어기술을 적용하였고 아크 발생 시의 스패터 최소화 공정을 제안하였다. 실험은 SM490A 강재를 사용하여 BOP(Bead On Plate) 용접을 실행하였다. 용접 중 LabVIEW를 이용하여 아크 발생 초기 전류, 전압 그리고 와이어 송급속도를 측정하였고, 고속 카메라를 이용하여 용접현상을 분석하였다. 본 연구를 통해 아크 발생 초기의 스패터를 최소화하는 공정을 도출할 수 있었다. 용접공정 변수인 아크 발생 초기의 와이어 송급속도, 와이어의 역송급 진행거리 그리고 역송급 판단 시점의 용접 전류 값은 실험을 통해 얻을 수 있었다. 또한, 이 연구를 통해 개발된 시스템의 성능을 평가하였다.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.20 no.10
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• pp.1994-2000
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• 2016

Technology that can determine the location of individuals is required in a variety of applications such as location based control, a personalized advertising. Missing-child prevention and support for field trips, and applications such as push events based on the user's location is endless. In particular, the technology that can determine the location without interruption in the indoor and outdoor spaces have been studied a lot recently. Because emphasizing on accuracy of the positioning, many conventional research have constraints such as using of additional sensing devices or special mounting devices. The algorithm proposed in this paper has the purpose of performing the positioning only with standard equipment of the smart phone that has the most users. In this paper, sensor Fusion with GPS, WiFi Radio Map, Accelerometer sensor and Particle Filter algorithm is designed and implemented. Experimental results of this algorithm shows superior performance than the other compared algorithm. This could confirm the possibility of using proposed algorithm on actual environment.

• Journal of Information Technology Services
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• v.16 no.1
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• pp.99-118
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• 2017

Growing importance of online security on certification, many of the web-related security technology introduced day by day. Especially, using smart certificate (USIM) is recognized as one of the most safe and convenient method for the security of public certificate. The purpose of this study is to find the factors that affect the Intention of switching to smart certificate for the general public who use public certificate service. Based on migration theory, this study determined the relationship between pull factors, push factors and mooring factors which can affect the intention of switching to smart certificate. To empirically analyze the proposed hypothesis, the statistical analysis were conducted based on the response from 350 public certificate service users using SPSS 22.0 and Smart PLS 2.0. The results of this study can be summarized as follows. First, system quality, one of the pull factors has positive influence on perceived ease of use. On the other hand, the other pull factor, service quality has positive influence on both perceived ease of use and perceived usefulness. Second, push factors, user experience and information security awareness have positive influence on perceived ease of use only. Third, mooring factor, switching cost does not have influence on switching intention while perceived usefulness has positive influence on. The results of this research can be used for whom has interest to the switching intention of public certificate service for online security and provide the proper understanding about smart certificate service mechanism.

• Journal of Navigation and Port Research
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• v.32 no.6
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• pp.473-479
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• 2008

Recently the trade patterns of the entire economy are rapidly changing on development of IT. The field of port logistics is enforcing a competitiveness through preliminary offer of information and a batch process for improving the structure of logistics management which is apparently high cost and the low efficiency since 1990. But a previous EDI is insufficient in process ability. Bemuse it costs for the purchasing and maintenance of the expensive communication devices which is operated on the VAN environment. A web based EDI operating on an open network environment is needed to improve these problems and to handle transaction efficiently among many and unauthorized personals. Therefore, this study is willing to present a new web based model of the pull process which extracts the data when the receiver is needed to improve the push process which is transmitting data unilaterally.