• Journal of the Institute of Electronics Engineers of Korea SD
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• v.37 no.4
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• pp.38-44
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• 2000

In this paper, we have been fabricated λ/2 phase plates lot an optical pick-up using a blue violet laser diode by employing proton exchange and wet etching in LiNbO$_{3}$. Their functions and fabrication processes are described in detail. It is established the optimal fabrication conditions through the experimental results. The device characteristics are measured by the Mach-zender interferometer which is composed of the optical components and 632.8nm He-Ne laser. The measured phase error was ＋5$^{\circ}$~ -6$^{\circ}$(within 3%). This phase plate could be applied an useful device to improve the resolution and the stability of the optical pick-up which has a blue violet laser diode as an optical source.

• Proceedings of the KIEE Conference
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• 1996.07a
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• pp.157-159
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• 1996

For the optimal design of the induction heating cooker, precise and accurate analysis of the magnetic field inside the jar must be achieved first. Until now, design methods based on experience has been used in industry field. But this takes a lot of trial and error, high cost and also long development time. So the analysis of the magnetic field distribution is very important. In this paper the magnetic field inside the induction heating cooker is analyzed by using axisymmetrical FEM(finite element method). And the method of the coil location design for the optimal heat source distribution using sensitivity analysis is developed. In addition, the shielding effect of the non-axisymmetrical 3-D ferrite structure used in induction heating cooker is also analyzed by the integral method.

• JSTS:Journal of Semiconductor Technology and Science
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• v.14 no.4
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• pp.478-483
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• 2014

We propose a new method which can extract the information about the electronic traps in the semi-insulating GaN buffer of AlGaN/GaN heterostructure field-effect transistors (HFETs) using a simple test structure. The proposed method has a merit in the easiness of fabricating the test structure. Moreover, the electric fields inside the test structure are very similar to those inside the actual transistor, so that we can extract the information of bulk traps which directly affect the current collapse behaviors of AlGaN/GaN HEFTs. By applying the proposed method to the GaN buffer structures with various unintentionally doped GaN channel thicknesses, we conclude that the incorporated carbon into the GaN back barrier layer is the dominant origin of the bulk trap which affects the current collapse behaviors of AlGaN/GaN HEFTs.

• Proceedings of the KIPE Conference
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• 2001.07a
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• pp.417-421
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• 2001

In this paper, a novel design method of variable motor inetia in Induction motor drive system is proposed. The inertia of a load and a motor are estimated by using RLS (Recursive Least Square) algorithm. The speed controller is designed by Kharitonove theory of motor. The effectiveness of the proposed scheme is verified with simulation and experiments results.

• Proceedings of the KIPE Conference
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• 2014.07a
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• pp.89-90
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• 2014

Recently, one of the switching rectifiers, Power Factor Correction Circuit is often applied in rectification stage to get high efficient conversion of AC-DC SMPS However, it becomes important to select optimal semiconductor switch as well as to design optimal rectifier for achieving higher power conversion. We performed experiments with MOSFET, SiC and GaN FET that are widely used in 600 W Interleaved CRM PFC and include the data in this report. The results are presented for discrete semiconductor and integrated implementations of interleaved CRM PFC.

• Journal of Electrical Engineering and Technology
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• v.8 no.5
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• pp.1131-1137
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• 2013

This paper introduces novel a two-phase permanent magnet BLDC (PMBLDC) motor with both an asymmetric tooth and an auxiliary tooth in order to improve the dead point, efficiency and torque ripple. To calculate the merits of introducing each of the asymmetric tooth and the auxiliary tooth, characteristic analysis is performed respectively using finite element method (FEM). To maximize performance, we propose a novel model which combines the asymmetric tooth and the auxiliary tooth. To maximize the efficiency of the novel model, an optimal design is processed using the Kriging method and a genetic algorithm. Finally, an experiment is used to confirm the initial and optimal design results.

• Proceedings of the Korea Contents Association Conference
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• 2011.05a
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• pp.385-386
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• 2011

본 연구의 목적은 전자식별 체계를 식품인증에 적용해 농식품의 안전성, 기능성을 인증하고 농식품 품질인증 마크와 연동한 효과적인 식품인증 방안을 제시하는 것이다. 또한 전자인증 기술을 활용해 농식품 품질을 손쉽게 확인하고, 주요 식품정보를 언제, 어디서나 활용할 수 있는 방안을 제시하고자 한다. 최근 모바일 기술을 활용한 QR코드 기반의 전자인증이 여러 사업 분야에서 사용되고 있는데, 이를 식품인증에 적용하여 식품인증의 효과성, 효율성, 편의성을 증진시킬 것으로 기대한다. 또한, 본 연구를 통하여 물류, 제조, 생산, 유통 산업에서 활용하고 있는 전자인증 체계(RFID, 바코드, QR코드 등)를 식품인증에 적용하여 식품상품의 정보를 손쉽게 확인하고 식품 정보조회를 통해 식품 품질을 검사하는데 사용할 수 있을 것으로 기대한다.

• 한국정보통신설비학회:학술대회논문집
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• 2003.08a
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• pp.362-366
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• 2003

LG전자/정보통신에서는 날로 심화되고 있는 통신 경쟁 및 시장개방 환경 하에서 경쟁력 확보하고, 교환기 시스템이 운용자 및 가입자에게 다양하고 안정된 시스템을 제공하기 위하여, 보다. 효과적으로 교환기를 운용하기 위한 유지보수 작업을 꾸준히 추진 시행하고 있다. 향후 3세대 또는 4세대 이동통신으로 전환시 급속한 기술적 발전과 고객에 대한 마인드 변화로 인한 장비 제조업체의 보다. 경쟁력 있는 유지보수 방법이 적용 되어야 할 것이다. 본 논문에서는 2세대 이동통신망 교환기 시스템을 대상으로 한 수년간의 유지보수 경험을 토대로 이동통신망 교환기의 유지보수 중요성에 대하여 기술하고, 향후 이동통신망이 진화되는 과정에서 교환기 유지보수의 고려사항 및 효율적 유지보수 방안을 제시하고자 한다.

• Journal of Information Management
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• v.27 no.2
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• pp.95-121
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• 1996

The purpose of this study is to investigate a theoretical background of digital libraries and current projects on building digital libraries. It begins by describing the shift of paradigm and the concept of digital libraries. The paper continues by summarizing the principles and technology of building digital libraries. It also includes current projects of US, UK, Japan, and National Central Library, KAIST, LG Sangnam Library in Korea.

• Korean Membrane Journal
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• v.5 no.1
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• pp.1-9
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• 2003

Due to the increasing intelligence, the increasing connectivity, and always-on characteristics energy needs for the portable electronics cannot be managed by the state-of-art battery technology. Micro fuel cell fuelled by aqueous methanol is gaining lots of interest from the new energy storage developers since it has the potential to offer the longer operation time to the portable electronic devices. Although the technical barriers to the commercialization exit, it is expected that the micro fuel cell technology bring huge benefits to the current energy storage market once it matures. In the article, benefits, challenges and market players of the direct methanol fuel cell arena is briefly reviewed.