• Electrical & Electronic Materials
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• v.12 no.8
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• pp.10-17
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• 1999

본 논문에서는 최근 초고주파영역에서 우수한 고출력 특성을 갖는 것으로 알려진 AlGaN-GaN high-electron mobility transistor(HEMT's)의 최근 기술동향과 함께 응용가능성 및 한계에 대하여 검토하였다. GaN는 약 3.4eV 정도의 큰 밴드갭을 갖는 까닭에 200V 이상의 높은 항복전압을 갖는다. 또한 AlGaN와 이종접합을 형성하는 경우 piezoelectric field에 의하여 1$\times$10\ulcornercm\ulcorner 이상의 높은 밀도의 2DEG(two-dimensional electron gas)의 형성이 가능하고, 상온 전자이동도가 1,200$\textrm{cm}^2$/V-s 이상으로서 초고주파 고출력 전자소자의 구현에 필요한 물성을 갖추고 있다. 현재 cutoff frequency fT가 60GHz이상, maximum frequency fmax가 150GHz 이상의 소자가 개발되었으며, 3W/cm 이상의 cw(continuous wave) 전력밀도가 보고된바 있다. 또한 열전도도가 큰 새로운 기판이 개발되고, heat dissipation을 개선하기 위한 새로운 소자구조가 개발됨에 따라 보다 높은 전력밀도를 갖는 단위소자 또는 MMIC(monolithic microwave integrated circuits)의 구현가능성이 높아지고 있다.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.22 no.52
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• pp.323-335
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• 1999

Spinal injuries are common these days and are increasing due to the increasing sports activities, auto-related accidents, and occupational incidences. Most of spinal injuries of strain and sprain are associated with trauma and resulted in loss of optimal musculoskeletal system in spinal column area. Some of these injuries requires surgical treatments. Fortunately, some people with spinal disorder are achieving outstanding results with the chiropractic care which utilizes muscle stimulation and strengthening, traction therapy, and spinal adjustments. These treatments using chiropractic table can ease pain by restoring alignment, improving mobility, and relieving pain and stiffness in neck and spinal areas. The purpose of this study was thus to gather the comprehensive information about spinal injuries, to define the specific dimensions, and to recommend functions of chiropractic table specially suited for Korean. This study was an integrated approach in applying the concepts of biomechanical correction of the musculoskeletal system. Also, this study was to utilize a knowledge of physics, ergonomics, and rehabilitation to the development of spine cure medicine.

• Journal of the Korean Institute of Telematics and Electronics D
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• v.35D no.12
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• pp.53-58
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• 1998

A buried channel poly-Si TFT (BCTFT) for application of high performance integrated circuits has been proposed and fabricated. BCTFT has unique features, such as the moderately-doped buried channel and counter-doped body region for conductivity modulation, and the fourth terminal entitled back bias for preventing kink effect. The n-type and p-type BCTFT exhibits superior performance to conventional poly-Si TFT in ON-current and field effect mobility due to moderate doping at the buried channel. The OFF-state leakage current is not increased because the carrier drift is suppressed by the p-n junction depletion between the moderately-doped buried channel and the counter-doped body region.

• Bulletin of the Korean Chemical Society
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• v.28 no.6
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• pp.995-998
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• 2007

Pentacene moiety has been widely studied in Organic Thin-Film Transistor (OTFT) device as a channel layer because of high carrier mobility. In this study, we have fabricated vertical type Organic Static Induction Transistors (SITs) using pentacene, 6,13-Dinaphthalen-1-ly-Pentacene (1-DNP, 3), and 6,13-Dinaphthalen-2- ly-Pentacene (2-DNP, 4). 1-DNP and 2-DNP have same naphtyl group with pentacene, but different linked position and spatial arrangement. We have checked the static characteristics of materials in vertical type SITs device. We found that pentacene has as on/off ratio of 14.56, 1-DNP and 2-DNP shows as on/off ratio of 36.58 and 6.61 at VDS = 2V in SIT, respectively.

• Proceedings of the KSR Conference
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• 2006.11b
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• pp.689-694
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• 2006

Wireless LAN is getting more popularity and plays a main role in electronic and telecommunication field. Wireless LAN is more convenient than wired LAN when mobility is required, and are sometimes the only feasible choice. Wireless LAN can also pose a significant security risk when not properly installed and maintained. Thus, this paper studies real-time message transmission using existing mobile telecommunication network and describes considerations and procedures when introducing wireless LAN concept and wireless LAN systems. It also studies integrated wired and wireless networking including wireless LAN bridge and AP technology of International Organization for Standardization, and especially real-time dynamic image data transmission in a moving train.

• Journal of the Korean housing association
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• v.10 no.3
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• pp.213-220
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• 1999

The purpose of this study was to find the degree of satisfaction of the Korean elderly with their existing residential environment and their propensity to move. The data were collected through interviews and structured questionnaires. The subjects were 1,200 nationwide elderly over the age of 60 selected by probability sampling proportionate to size. cluster and random sampling method. The data were analyzed with frequency. percentage. and $X^2$-test using the SAS package. The major findings were as follows: Most subjects were satisfied with their housing environment and had no intention of moving. The subjects were highly satisfied with their residential environment. did not tend to move. This result does not necessarily mean that there is no need for better housing and no need to design elderly housing in Korea. It implies the need for community integrated housing development with flexible service system.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• 1999.10a
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• pp.357-361
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• 1999

Currently, many research projects are focusing on automation of various equipment such as cranes and AGV's for automated container terminals. However, for more productivity of these terminals, integration of the required equipment is most crucial as proved in Computer Integrated Manufacturing (CIM). The integration requires information exchange via a type of network interconnecting various pisces of equipment. In order to better design such networks, this paper presents the requirements, available protocols, and basic network structure for an communication network in an automated crane terminal

• Proceedings of the Korea Institutes of Information Security and Cryptology Conference
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• 2003.12a
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• pp.625-633
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• 2003

무선랜은 현재 무선 네트워크에서 매우 중요한 역할을 차지하며, 앞으로의 차세대 무선 통합네트워크에서 또한 그 비중이 매우 높아 질 것이다 특히 핫스팟과 같은 공중망서비스의 확산으로 무선 인터넷 등의 차세대 정보 컨텐츠 산업의 중요한 매체로 부각되고 있다. 이에 부합하여 무선랜 서비스에 있어 사용자의 프라이버시(Privacy) 및 접근제어(Access Control), 인증(Authentication), 과금(Accounting), 빌링(Billing) 등의 다양한 보안 문제가 중요한 이슈로 대두되고 있다. 본 논문에는 공중 무선랜에서의 이동성이 고려된 인증 모델을 여러 국제 표준에 맞추어 제안하고, 그에 대한 검증 결과를 함께 제시한다. 제안된 모델은 상호 연동성 및 호환성을 보장하기 위해 Diameter를 기반 기술로 사용하였다.

• Proceedings of the Korean Information Science Society Conference
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• 2003.04d
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• pp.632-634
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• 2003

본 논문은 기존에 제안되어 있는 RSVP와 Mobile If물 바탕으로 무선 이동환경에서 QoS 보장과 단말의 이동성을 동시에 지원할 수 있는 통신미들웨어 플랫폼을 설계하고 개발한다. 목표시스템은 마이크로소프트사의 Windows CE 운영체제를 기반으로 하며, Windows CE 운영체제 및 PDA 하드웨어 시스템의 제한된 자원과 프로그래밍 API 지원에 따른 문제점을 해결한다. 이동환경에서의 RSVP를 위한 미들웨어상의 통신 모듈을 개발하고 Mobile IP 모듈과 연동하기 위한 방법을 설계하고 구현한다. 802.11b 무선랜 기반의 실험망을 구축하고, 개발된 PDA용 통신 미들웨어 플랫폼의 기능과 성능을 검증하고 그 활용방안을 제시한다.

• International conference on construction engineering and project management
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• 2005.10a
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• pp.1042-1047
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• 2005

A web-based camera (webcam) is expected to enhance construction operation monitoring. However, webcams are often installed outside a building because their mobility is limited by cable wiring, which makes it difficult to monitor construction operations inside the building. If a webcam is integrated with emerging wireless communication technologies, construction professionals may be able to monitor interior construction operations using webcams without getting network cables wired on a congested and dynamic construction job site. However, one may concern that wireless communication may not be fast enough to transport all webcam images seamlessly. This paper presents an investigation as to the observation error of webcam images when a limited amount of images are delivered.