• 한국전자파학회논문지
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• 제15권5호
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• pp.461-466
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• 2004

본 논문에서는 스위칭 소자를 사용한 새로운 형태의 편파 다이버시티 개구 결합 원편파 패치 안테나를 제안하였다. 제안된 안테나의 구조는 정사각형 패치의 모서리를 왜곡시킨 단일 패치이며, 급전은 전력 분배기 형태의 마이크로스트립 급전에 Schottky 다이오드를 삽입시킨 형태이다. 스위칭 소자인 Schottky 다이오드는 급전의 전력 분배 지점에서 $\lambda$/4 떨어진 위치에 삽입하였으며, Schottky diode의 ON/OFF 동작으로 방사체인 패치의 급전이 변화를 이루어 좌$.$우 선회 원편파로 변화되는 구조로 설계하였다. 스위칭 동작에 의해 측정되어진 안테나의 3 dB 축비 대역폭은 약 2 %로 측정되어졌다.

• ETRI Journal
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• 제11권4호
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• pp.75-83
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• 1989

The diffusion mechanism of Si in GaAs was investigated using different diffusion sources based on the Si-Ga-As ternary phase equilibria. The Si profiles are measured with secondary ion mass spectrometry and differ significantly for sources taken from the different phase fields in the ternary phase diagram. Neutral As vacancy diffusion is proposed for acceptor Si diffusion anneals using a Ga - Si - GaAs source. Donor Si diffusion using As - rich sources and a Si -GaAs tie line source shows concentration dependent diffusion behavior. Concentration dependent diffusion coefficients of donor Si for As - rich source diffusion were found to be related to net ionized donor concentration and showed three regimes of different behavior: saturation regime, intermediate regime,and intrinsic regime. Ga vacancies are proposed to be responsible for donor Si diffusionin GaAs: $Si_Ga^+V_Ga^-$ (donor Si -acceptor Gavacancy) complex for the extrinsic regime and neutral $V_G$a, for the intrinsic regime.The Si - GaAs tie line source resulted in two branch profiles, intermediate between the As - rich and the Ga - rich source diffusion cases.

• 대한전자공학회논문지
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• 제20권3호
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• pp.40-44
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• 1983

원판형 마이크로스트립 패치를 기본 소자로 하여 준 대수 주각형 광대역 마이크로스트립 안테나를 설계한다. 각 방사소자들은 종단이 개방된 주급전 마이크로스트립 선로상에서 정합선로를 통하여 직열 급전된다. 설계 제작된 안테나의 정재파비는 주파수 2.72∼3.43GHz 범위내에서 약 2.3이하로 됨이 실험적 결과로 나타났다.

• 한국컴퓨터정보학회논문지
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• 제21권2호
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• pp.97-103
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• 2016

This paper deals with the cycle time minimization problem that determines the productivity in printed circuit board (PCB) with n components using the m placement machines. This is known as production cycle time determination problem (PCTDP). The polynomial time algorithm to be obtain the optimal solution has been unknown yet, therefore this hard problem classified by NP-complete. This paper gets the initial assignment result with the machine has minimum unit placement time per each component firstly. Then, the balancing process with reallocation from overhead machine to underhead machine. Finally, we perform the swap optimization and get the optimal solution of cycle time $T^*$ within O(mn) computational complexity. For experimental data, the proposed algorithm can be obtain the same result as integer programming+branch-and-bound (IP+B&B) and B&B.

• Journal of Power Electronics
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• 제3권1호
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• pp.17-23
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• 2003

A new three-phase soft-switching active front-end inverter is presented. The topology consists of a quasi-resonant PWM boost converter with an additional resonant branch, which provides low loss at high frequency operation. This leads to a high conversion efficiency and a remarkable reduction in the siBe of the input inductor. To synchronise the PWM pattern with the resonance cycle, a modified space vector modulation with asymmetrical PWM pattern is used. A high power factor can be achieved for both power flow directions. Due to a new control strategy the converter features a low content of harmonics in the line currents even for distorted line voltages.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2006년도 추계학술대회 논문집
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• pp.954-963
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• 2006

PRT(Personal Rapid Transit) is alternation mode of auto and advanced transportation system as future transportation mode cope with the situation caused by increasing traffic demand, vehicle, environment, energy problem. but there is no place where PRT is operated therefore it is necessary of study on application of PRT The purpose of this study is putting into shape of fundamental notion and role of PRT as transit system and studying of domestic application possibility We expect that PRT make transit will make variety and be able to connect with mass transportation facility, have a connection between trunk line and branch line, be a effective local transportation system within CBD, be a transportation system within leisure complex. This study focus on connection with mass transportation facility in the middle of 5 type, we class as. and we investigate application of PRT by process of making a choice applicable case area

• 대한전기학회:학술대회논문집
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• 대한전기학회 2005년도 제36회 하계학술대회 논문집 C
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• pp.2386-2388
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• 2005

As anti-crash and pre-crash systems in vehicles become more extensively used, the need for high performance short-range radars is playing an increasing role. This paper presents the design of a micromachined, ultra-wideband beamformer centered at 24 GHz for automotive short-range radar systems. This beamformer is a Butler matrix designed using ultra-wideband transmission-line couplers, which consist of a multilayered structure that exhibits wider bandwidth compared to conventional microstrip branch-line couplers. The circuit has been designed on a quartz substrate, and to achieve the desired coupling, lines suspended on BCB layers located at specific parts of the circuit were used, achieving a three metal layered structure in form of wide microstrips, that give low loss and a wideband response. In this paper the design and fabrication procedure of the proposed beamformer are fully described.

• 전력전자학회:학술대회논문집
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• 전력전자학회 2001년도 Proceedings ICPE 01 2001 International Conference on Power Electronics
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• pp.146-150
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• 2001

A new three-phase soft-switching active front-end inverter is presented. The topology consists of a quasi-resonant PWM boost converter with an additional resonant branch, which provides low loss at high frequency operation. This leads to a high conversion efficiency and a remarkable reduction in the size of the input inductor. To synchronise the PWM pattern with the resonance cycle, a modified space vector modulation with asymmetrical PWM pattern is used. A high power factor can be achieved for both power flow directions. Due to a new control strategy the converter features a low content of harmonics in the line currents even for distorted line voltages.

• 국제학술발표논문집
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• The 6th International Conference on Construction Engineering and Project Management
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• pp.28-29
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• 2015

The tire production facility is a large-scale construction with the complexity of a manufacturing process. The process utilities should be wide-ranging as an effective arrangement of them is highly important. All the necessary information should be clarified together with the manufacturer at the basic planning stage, and this design should be developed to comply with the local culture and regulations. It is important to carry out more advanced engineering in terms of process, cost and quality, even if it is difficult to standardize due to the cultural and geographical conditions and regulations. The key point is to reflect all the given conditions and make a clear design during the design stage, to eliminate the problems after the construction has begun. Another key point is the delivery system, which must be totally managed from the initial design stage until the construction stage by proven companies. Flexibility, quick action, and single responsibility will be the fundamental features in all the steps of the project.

• 국제초고층학회논문집
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• 제12권3호
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• pp.241-249
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• 2023

Azabudai Hills is located in the area connecting Kamiyacho on the Hibiya Line and Roppongi 1-chome on the Nanboku Line, and was planned as a district with three skyscrapers arranged around a plaza. Based on the concept of a "Modern Urban Village", the project integrates a variety of urban functions, including offices, residences, a hotel, an international school, commercial and cultural facilities. The construction of the 64-story and 330-meter-high, "A block" was extremely difficult due to its large scale and diverse uses. This paper presents a case study of DX challenges to improve productivity and ensure quality, as well as the resulting benefits and future challenges.