• 한국정보통신설비학회:학술대회논문집
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• 한국정보통신설비학회 2009년도 정보통신설비 학술대회
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• pp.221-224
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• 2009

In this paper, we deal with the development of an optimal design program for a dual-band of 0.92 GHz and 2.45 GHz with shorting pin and slot by using evolution strategy. the optimal shorting pin, coaxial feed and H-shaped patch are determined by using an optimal design program based on the evolution strategy. To achieve this, an interface program between a commercial EM analysis tool and the optimal design program is constructed for implementing the evolution strategy technique that seeks a global optimum of the objective function through the iterative design process consisting of variation and reproduction. The resonance frequencies of the dual-band antenna yielded by the optimal design program are 0.92 GHz and 2.45 GHz that show a good agreement to the design target values.

• 한국정보통신학회:학술대회논문집
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• 한국해양정보통신학회 2000년도 춘계종합학술대회
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• pp.489-492
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• 2000

This paper describes a new transient voltage suppressor(TVS) with a low insertion loss and a very wide frequency bandwidth to protect antenna circuit from transient voltages. Conventional protection devices have some problems such as low frequency bandwidth and high insertion loss. In order to improve these limitations, a coaxal type TVS, which consists of a gas tube is developed. The performance of the proposed transient voltage suppressor is tested by using a combination surge generator specified in IEC 61000-4-5 standard and by using a network analyzer of 40 MHz ∼ 5GHz bandwidth. From the experimental results, it is confirmed that the proposed TVS has an enough protection performance in low insertion loss and in wide frequency bandwidth

• 한국항해항만학회:학술대회논문집
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• 한국항해항만학회 1993년도 춘계학술발표회
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• pp.53-64
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• 1993

This study aims to measure the reflection loss and the material constants of the fabricated samples for electromagnectic wave absorber precisely and easily by using 20mm$\Phi$coaxial tube with the end-short-type. The authors have estabilished the extraction algorithm of material constants by one port method and proved that the results of the experiments coincided with the calculated ones. On the basis of the above results the validity of the proposed measuring method is confirmed. This measurement method could be used effectively for the design of microwave absorbe and for its evaluation.

• Journal of Communications and Networks
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• 제8권4호
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• pp.432-441
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• 2006

As the community antenna television (CATV) networks becomes ubiquitous, instead of constructing an entirely new broadband network infrastructure, it has emerged as one of the rapid and economic technologies to interconnecting heterogeneous network to provide broadband access to subscribers. How to support ubiquitous real-time multimedia applications, especially in a heavy traffic environment, becomes a critical issue in modern CATV networks. In this paper, we propose a time guaranteed and efficient upstream minislots allocation algorithm for supporting quality-of-service (QoS) traffic over data over cable service interface specification (DOCSIS) CATV networks to fulfill the needs of realtime interactive services, such as video telephony, video on demand (VOD), distance learning, and so on. The proposed adaptive fast expansion algorithm and the loading statistics with dynamic swapping algorithm have been shown to perform better than that of the multimedia cable network system (MCNS) DOCSIS.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2001년도 하계학술대회 논문집 C
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• pp.1771-1773
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• 2001

This paper deals with the numerical estimation of the bubble behavior and the partial discharge(PD) initiation voltage basis of electric field calculation with the coaxial coil layer-to-cylindrical electrode system for the simulation of high temperature superconducting coils. The theoretical results of bubble behavior and the PD initiation voltages showed fairly good agreements with the experimental results.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2010년도 춘계학술대회 논문집
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• pp.35-35
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• 2010

This paper illustrates the use of electric field computation to optimize the design of high voltage composite bushing. In the bushing, a high electric stress occurred between field shaper and central conductor by the closely space. Also coaxial cylindrical shield has a great height along the axis to control an electric field. Consequently, all the potentials are raised axially along the field shaper and electric stress is concentrated on a part of the surface of the FRP tube near the upper end of the field shaper. Maxwell 2D simulator based on the boundary element method was also introduced in order to verify the reliability of the polymer bushing. The optimized design uses internal elements for electric stress grading at critical parts of the bushing.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2008년도 추계학술대회 논문집 Vol.21
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• pp.215-216
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• 2008

Using the extensional vibration mode of PZT ring, a piezopump is successfully made. The PZT ring is polarized with thickness direction. The traveling extensional wave along the circumference of the ring is obtained by dividing two standing waves which are temporally and spatially phase shifted by 90 degrees from each other. The proposed piezopump is consisted of coaxial cylindrical shells that are bonded piezoelectric ceramic ring.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2003년도 하계종합학술대회 논문집 II
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• pp.1185-1188
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• 2003

This paper describes a design for a 2.5Gb/s serial data link CMOS transceiver based on the InfiniBand$^{TM}$ specification. The transceiver chip integrates data serializer, line driver, Tx PLL, deserializer, clock recovery, and lock detector. The designed transceiver is fabricated in a 0.25 ${\mu}{\textrm}{m}$ CMOS mixed-signal, 1-poly, 5-metal process. The first version chip occupies a 3.0mm x 3.3mm area and consumes 450mW with 2.5V supply. In 2.5 Gbps, the output jitter of transmitter measured at the point over a 1.2m, 50Ω coaxial cable is 8.811ps(rms), 68ps(p-p). In the receiver, VCO jitter is 18.5ps(rms), 130ps(p-p), the recovered data are found equivalent to the transmitted data as expected. In the design for second version chip, the proposed clock and data recovery circuit using linear phase detector can reduce jitter in the VCO of PLL.L.

• 한국전자파학회:학술대회논문집
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• 한국전자파학회 2002년도 종합학술발표회 논문집 Vol.12 No.1
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• pp.328-331
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• 2002

Hyperthermia용 안테나의 성능은 안테나의 임피던스매칭과 안테나 주위 조직의 SAR 분포에 의해서 결정된다. 본 논문에서는 FDTD 해석법을 이용하여 Coaxial-Slot 안테나를 계단형(stair-caseing)으로 근사화하여 분석하였고, 가열 특성을 개선시킬 수 있는 Hyperthermia용 안테나를 설계하였다. 또한 팁으로부터 슬롯 중심까지의 거리( $L_{ts}$ )와 슬롯 폭을 변화시키면서 hyperthermia 안테나의 공진 특성을 분석하였고 계단형 모델로 근사화된 안테나에서 간에 유기 되는 SAR 1g 평균 첨두치를 계산하였다. 본 논문에서 제안하는 안테나의 SAR 값은 1g 평균 첨두치는 180.7 W/kg으로 나타났고 최대 온도는 상승량은 8.6$^{\circ}C$로 나타났다.

• 대한기계학회논문집
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• 제7권3호
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• pp.328-334
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• 1983

The turbulent hydrogen-air diffussion flame was studied experimentally and theoretically. Laser Doppler anemometer was used to measure the velocity field in the flame. Two mathematical models for the combustion reaction term, which are infinite rate model and finite rate to be derived eddy break-up model, were tested by comparing predictions with experimental data for coaxial turbulent diffusion flame. The agreement between the predictions and the data is, on the whole, very good in the case of employing the finite rate model rather than the infinite rate model. But, it was shown that the finite rate model was practically applicable to the predictions of the turbulent diffussion flame structure.