• Journal of Korean Society of Environmental Engineers
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• v.36 no.10
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• pp.679-684
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• 2014

Many burial sites were constructed to suppress the spread of foot and mouth disease during outbreak. Defected burial sites were removed when leachate leak is presumed and carcasses were moved to the circular storage tanks. However, carcasses were not decomposed possibly due to low water content, low microbial activities, and poor mixing. In this research, storage tank containing carcasses in it was modified to bioreactor to accelerate stabilization. Liquids with nutrients were added and circulated to maintain the optimum water content while extraneous microorganisms were augmented. Settlement was used as the primary index for assessing stabilization rate, and the consolidation theory was utilized to estimate the expected final settlement. 30% of carcasses is expected to be decomposed and removed from the storage tank for five years of bioreactor operation.

• Journal of Korean Association for Spatial Structures
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• v.5 no.3 s.17
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• pp.101-107
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• 2005

An analytic study on the bond stress between steel tube and concrete in concrete filled steel(CFT) tublar column is presented in this paper. Recently buildings need members which are enhanced durability and ductility. Concrete filled tublar column system is proposed as alternative plan. In this paper, ABAQUS/Standard Version 5.8 which is identified as usefulness for finite element analysis and has various element library is used. The variables in this study are the location and type of shear-connector. The modeling ell contact problem practiced by Contact Pair and Contact Pressure method. In the step of physical bond, it is practiced by Change friction option. After yielding of models, analytic results is less than that of experimental results.

• Journal of the Korea Convergence Society
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• v.10 no.1
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• pp.1-6
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• 2019

In this paper, we have studied a direction finding method of the radio signal by comparing the phase difference and its pattern from the uniform circular array antenna. In the phase comparison direction finding, if the length of the antenna baseline is longer than 0.5 wavelength of the incident signal, azimuth ambiguity occurs in which two or more azimuth angles are calculated in the same phase difference. The azimuthal ambiguity is removed by fusing the phase difference of the 5 antennas. The developed ambiguity elimination technology reduces the azimuth error where the antenna baseline is shorter than 1.236 wavelength in the uniform circular array with five antennas. This algorithm is very useful for the design of direction finder of an electronic information system.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2010.06a
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• pp.224-224
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• 2010

야금학적 정련은 태양전지 소재인 실리콘의 저가화를 통한 태양전지의 단가를 낮추는데 유망한 공정이다. 이중에서도 실리콘의 전자빔정련은 고순도의 실리콘 정련에 효과적인 기술이다. 본 연구에서는 전자빔용융법을 이용하여 실리콘 정련을 수행하였으며, 제조된 실리콘의 미세구조 및 분순물농도를 측정하였다. 고진공의 챔버 하부에 수냉동도가니가 위치해있고, 상부에 100 kW출력의 전자총이 설치되었다. 실리콘은 분쇄 및 세척과 같은 전처리 없이 수냉동도가니에 250g 이 장입되었다. 전자빔때턴은 소프트웨어를 통한 헌혈, 나선형의 경로(path)와 원형의 형상(Shape)이 결합하여 원형패턴과 나선형패턴의 형상으로 실리콘에 조사되었다. 전자빔의 출력을 15 kW로 실리콘을 용융하였고 분당 0.5 kW의 속도로 서냉하였다. 제조된 실리콘은 지름 100 mm, 높이 25 mm의 버튼형상이었으며, 횡방향으로 절단하여 미세구조와 불순물거동을 분석하였다. 미세구조는 광학현미경 (OM) 과 전자현미경 (SEM)을 통하여 관찰하였고 불순물거동은 유도결합플라즈마 분광분석기(ICP-AES) 을 통하여 분석하였다. 장입된 실리콘의 초기순도는 99.5 %이고, 전자빔정련 공정 후 99.996 %까지 향상되었다. 전자빔패턴을 이용한 고순도 실리콘의 정련은 태양전지 소재 개발에 유망한 기술로 활용될 것이다.

• Proceedings of the Korean Society For Composite Materials Conference
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• 2002.05a
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• pp.177-180
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• 2002

3-D 원형 브레이드 복합재료의 물리적인 물성을 계산하기 위해서는 실제와 같은 단위구조의 모델링과 이를 통한 RVE(Representative Volume Element)의 구현이 필수적이다. 실제적인 내부구조 모델링을 위해 단위구조를 2가지로 나누었으며, 실의 경로를 3차원 스플라인으로 적합시켰다. 구현한 내부구조를 통하여 공정변수와 구조변수와의 관계를 고찰하였다.

• Proceedings of the Korea Electromagnetic Engineering Society Conference
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• 2000.11a
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• pp.394-398
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• 2000

프로브로 급전되는 패치 안테나의 경우 급전점에서 급격히 변하는 전류 성분들이 존재하게 되는데, 이러한 성분들은 패치와 프로브간의 연속성을 보장해 줄 수 있는 attachment mode를 사용하여 정확하게 표현될 수 있다. 본 논문은 프로브 급전 구조를 정확하게 모델링할 수 있는 attachment mode를 사용하여 Radome이 올려진 원형 마이크 로스트립 안테나를 해석하여 임피던스, 반사계수, 및 이득 변화의 영향을 분석하였다.

• Proceedings of the Optical Society of Korea Conference
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• 2003.02a
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• pp.36-37
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• 2003

원형 미소공진기는 Q값이 매우 큰 공진모드가 존재할 수 있어, 광집적회로 등의 초저문턱 미소공진기 레이저에 적용되는 연구가 활발하게 수행되고 있고, 광통신용 Add／Drop Filter, 전-광 (electrical to optical) 직접 변환소자 등의 광소자 분야에 활용하려는 연구가 진행되고 있다. 한편 미소공진기 연구는 원형에서 더 나아가 square, quadrupole, spiral, mismatched two cavities등으로 확장되고 있다. (중략)

• Journal of the Institute of Convergence Signal Processing
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• v.6 no.4
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• pp.198-205
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• 2005

In this paper, the miniaturization of aperture-coupled RHCP patch antenna for the GPS system is treated. Circularly polarization characteristics is implemented by truncating diagonal corners of the square patch. Antenna size is reduced by inserting four uniform slits at the patch edges, which was equivalently lengthened the surface current by meandering it, This antenna uses aperture-coupled feeding structure with crossed-slot shape in order to give easy miniaturization of RHCP patch antenna. Simulated and measured results show that $42.7\%$ lower antenna size is obtained, and also $56\%$ lower -10dB bandwidth and $38.5\%$ lower 3dB AR bandwidth are obtained. when the proposed design scheme is applied to a commercial GPS antenna structure, $42.9\%$ lower patch size and $56\%$ lower 3dB AR bandwidth compared to commercial antenna at the same frequency are obtained.

• Land and Housing Review
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• v.2 no.1
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• pp.47-52
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• 2011

Recent advances of technology in materials science have made it easy to respond to user's needs on high performance steel in civil and building structures. The high-performance and high-strength steel are required for large scale structure and high-rise building to have high-strength, high fracture toughness and better weldability etc. Therefore development of 600MPa class steel for mega structure is necessary. high strength steels, however, may have mechanical properties that are significantly different from those of the conventional steels. The application of high-strength steels to building structures should be reviewed as to whether inelastic behavior equivalent to that of conventional steels can be attained or not. This study researched the structural behavior of high strength circular tubes compression and under flexure. Three column tests and three flexural tests were carried out. The suitability of existing design formulae(KBC 2009) and the structural behavior were investigated through these columns and beams with various types.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.32 no.3A
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• pp.139-148
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• 2012

Circular concrete-filled tubes (CFTs) are composite members, which consists of a steel tube and concrete infill. CFTs have been used as building columns and bridge piers due to several advantages such as their strength-to-size efficiency and facilitation of rapid construction. Extensive experimental studies about CFT have been conducted for past decades. However experimental results alone are not sufficient to support the engineering of these components. Complementary advanced numerical models are needed to simulate the behavior of CFT to extend the experimental research and develop predictive tools required for design and evaluation of structural systems. In this study, a finite element modeling technique for CFT was developed. The confinement effects, and behavior of CFT subjected various types of loading predicted by the proposed finite element model for CFT were verified by comparing with test results.