• Journal of the Computational Structural Engineering Institute of Korea
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• v.30 no.1
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• pp.17-22
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• 2017

In this study, we designed the metallic reception part of a patch antenna using the phase field design method. The design object function is formulated with the S-parameter value which represent the return loss so that it is targeted to maximize radiation efficiency at a target frequency. The initial model of a patch antenna was designed via the ordinary theory based approach and its performance was enhanced by changing the structural configuration of the metallic part using the phase field design method combined with the double well potential functions. The final shape was proposed by removing the gray scale area along the structural boundary by employing a cut-off method. The proposed shape shows that the radiation efficiency at target frequency is significantly improved compared with the initial patch shape. The finite element analysis and optimization precess was performed using the commercial package COMSOL and Matlab programming.

• Korean Journal of Optics and Photonics
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• v.30 no.6
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• pp.219-225
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• 2019

In an infrared optical system, using a cooled detector generates a phenomenon called a narcissus, in which the focal-plane array cooled to very low temperatures is reflected at the lens surface and detected. The narcissus can be removed by non-uniformity correction of the detector pixel, so narcissus is generally ignored in infrared optics. However, non-uniformity correction reduces the sensitivity of the system. Also, as the housing temperature varies due to an environmental temperature change, or a lens is moved for focusing or athermalization purposes, a narcissus may occur even after non-uniformity correction. To minimize such a narcissus, the amount of the effect must be controlled in the lens-design stage. In this paper we designed a midinfrared optical system and analyzed the narcissus by setting the lens surface reflectance to 1%. In addition, the design was divided into stages of an initial design, an improved design, and a minimum design, and the narcissus was improved to about 56% of that in the initial design.

• Proceedings of the Korean Institute Of Construction Engineering and Management
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• autumn
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• pp.246-249
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• 2003

we classified major changes into changes based on design deficiency, changes based on the different conditions between job site and contract documents, and changes based on the Owner's need. Then we compare and analyzed applicable regulations for supervision and work performance status at the site, and elicit problems of supervision performance based on mutual contradiction in regulations, bringing up a similar example. Based on the above, we brought up a way of improvement for the elicited problem, comparing and analyzing the laws/contract provisions/instructions related with the changes and the work performance at the jobsite, and verified through interviews with professionals of various fields for the improvement. Finally this study could elicit a way of improvement in the supervision work in conjunction with changes in civil works.

• Journal of Practical Engineering Education
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• v.15 no.3
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• pp.635-640
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• 2023

Creating New Value Through Digital Transformation Across Industries Worldwide: A Focus on Transitioning from CAD to BIM Design in the Construction Sector with the Implementation of Mandatory BIM Design by 2025 by the Ministry of Land, Infrastructure, and Transport in South Korea. Challenges and Proposed Methodology for Enhancing Efficiency in BIM Design in the Civil Engineering Field of Underground Infrastructure, and Nurturing BIM Design Experts.

• Construction Engineering and Management
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• v.10 no.5
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• pp.60-65
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• 2009

• 전기의세계
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• v.17 no.1
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• pp.32-47
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• 1968

이글은 전호에 연결되는 글로써 다음과 같이 구성되어 있다. 1. 부재강도 2. 전선배치 3. 기초계산 4. 풍압에 관한 근자의 연구 5. 우리나라 송전선로의 설계개선점 6.결언

• 건축구조
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• v.15 no.3
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• pp.57-65
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• 2008

• 한국도로학회지:도로
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• v.10 no.4
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• pp.68-73
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• 2008

• Journal of the Korea Institute of Military Science and Technology
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• v.1 no.1
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• pp.219-226
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• 1998

군 위성통신 시스템의 생존성 향상을 위한 대전자전기능 설계기법으로 Dehop/Rehop 중계기를 사용하는 FH-FDMA 위성통신방식 설계구조를 제안하고 성능을 분석하였다. Dehop/Rehop방식은 적의 재밍조건하에서 필수적 통신링크를 보장하는 설계기법으로 Bent-Pipe방식에서의 Power Robbing, Hard-limiter에 의한 소신호 감쇄 등이 거의 없으며 광대역 도약으로 항재밍 능력의 개선이 가능하다. 본 연구에서는 75bps-2048kbps의 LDR/MDR/HDR 데이터 전송이 가능한 중계기 구조를 설계하고, SHF대역에서 도약대역폭에 따른 항재밍 성능분석과 Bent-Pipe방식 대비 Dehop/Rehop방식의 채널별 항재밍 성능분석결과 9-l0㏈내외의 성능개선이 가능함을 보였다.

• Proceedings of the KIEE Conference
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• 2005.10b
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• pp.514-516
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• 2005

압전 구동기(Piezo actuator)는 수 나노미터 수준의 위치정밀도와 고분해능을 가지고 있으나 비선형 특성인 히스테리시스(Hysteresis)는 정상상태에서 위치 오차를 발생하는 주요 원인이 된다. 현재까지 히스테리시스를 보상하기 위해 피 프 포워드 제어 방법, Pl 제어 방법, $H_{\infty}$제어 방법 등이 연구되어 왔지만 저주파 대역의 외란(disturbance)까지 고려하여 시스 템을 주파수 영역에서 설계, 분석하는 방법에 대한 연구는 미흡하였다. 본 논문은 압전 구동기의 위치 제어를 위한 제어기의 설계와 이를 주파수 영역에서 분석하는 내용을 다룬다. 제어기의 설계는 히스테리시스를 보상하기 위해 극점 배치 방법과 외란 관측기(Disturbance observer)를 기본으로 하였으며 적분제어를 적용하여 시스템 민감도(sensitivity)를 개선하였다. 시뮬레이션과 실험을 통하여 설계한 제어기가 히스데리시스에 대한 보상과 민감도의 개선에 효율적임을 검증하였다.