• ICROS
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• v.21 no.4
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• pp.21-26
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• 2015

지능형 시스템의 수요가 증가하면서 영상인식의 중요성이 부각되고 있다. 사람이 직접 물체 인식 과정을 모델링하는 방식을 넘어 최근에는 기계학습을 이용하여 이를 자동화하는 방법이 주를 이루고 있다. 그 중 딥러닝은 빅데이터를 활용하는 각종 분야에서 놀라운 성능을 보이며 기계학습 수준을 한 단계 진화시킨 기술로 평가 받고 있으며 영상 인식의 다양한 분야에서 응용되고 있다. 본 글에서는 딥러닝을 이용한 물체 검출 기법의 동향을 살펴보고 이를 차량 전면부 인식에 적용한 사례를 소개한다.

• Proceedings of the Korea Water Resources Association Conference
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• 2020.06a
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• pp.331-331
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• 2020

급격한 산업화와 도시화로 인한 도시유역의 불투수면의 증가와 이에 따른 배수능력의 저하로 인해 도시 물순환의 왜곡이 발생하였다. 따라서 과거 도시 물관리 기법의 한계가 나타났으며 이를 위해 저영향개발 기법 등과 같은 도시 물관리 기법의 패러다임이 변화하였다. 본 연구에서는 저영향개발 기법에서 도시유역 내 활용이 유용한 침투형 시설 중 투수블럭에 대한 물순환 성능평가를 실외실험을 통해 분석하였다. 성능평가 실험은 부산대학교 양산캠퍼스 한국 GI&LID 센터 내 투수블록 뿐만 아니라 블록 하부 골재층까지 설치가 가능하도록 되어있어 실제 현장과 유사한 환경을 구축이 가능한 2.4×10.9×0.4 (m) 규모의 주차장형 LID 실증시험시설을 활용하였다. 인공강우 분사를 위한 실외 인공강우모사 장치 크기는 2×2(m)으로 본 시험을 위하여 5개의 인공강우모사 장치를 연결하여 활용하였으며, 본 시험장치는 강우를 공급하기 위한 수조와 펌프, 일정한 유량을 유입하기 위한 유량계, 강우를 분사하기 위한 노즐, 인공강우가 실제 강우와 같이 자유낙하 하도록 구현하기 위한 오실레이터 등으로 구성되었다. 시험대상인 틈새투수블록은 석재블록 규격 400×600×100 mm이며 재질은 받침안정층(흙), 투수블록(화강석)으로 구성되어 있다. 실험의 시나리오는 시험체에 강우강도 30mm/hr, 50mm/hr, 100mm/hr에 해당하는 양을 1시간 동안 유입하여 시험 시작 후, 강우지속시간, 표면유출지속시간, 표면유출량을 1분 단위로 측정. 시험체에 유공관이 설치된 경우에는 침투유출지속시간, 침투유출량도 함께 1분 단위로 측정하였으며 각 강우강도별로 측정하고, 1회 측정 후, 각 시험별 시험 대상체의 조건을 같게 하기 위한(하부 지반의 건조) 약 3일 이후(상황에 따라 변동 가능) 시험하였다. 본 실험의 결과, 강우강도가 30 mm/hr와 50 mm/hr인 경우에는 화강석 틈새투수블록포장에서 지표 유출이 발생하지 않았으며, 강우강도 100 mm/hr의 경우 260 L의 지표 유출이 발생하여, 불투수표면 대비 84%의 지표유출 저감률을 보여줌으로서 투수블럭에 물순환 성능에 대한 효과를 분석하였다.

• Proceedings of the Korean Information Science Society Conference
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• 1999.10b
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• pp.304-306
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• 1999

사이버 강의 스크립트를 정의하고, 이 스크립트의 문법을 etf(Ewha Tag Format)라 명칭하였다. 그리고 사이버 강의 스크립트를 자바 웹 서버 상에서 효과적으로 처리할 수 있도록 자바 웹 서버를 설계 구현하였다. 사이버 강의 스크립트란 강의록, 문제출제, 문제 평가, 숙제 제출, 자료실, 토론방 등의 가상대학 환경을 편리하게 구축하기 위해서 데이터베이스 및 파일의 접근을 웹 환경의 스크립트만을 사용하여 구현할 수 있도록 정의한 것이다. 강의 시스템은 사용자에게 정형화된 포맷이 많이 쓰이기 때문에 스크립트로 정형화된 형태의 인터페이스가 적합하며, 실제적인 구현이 자바로 이루어지기 때문에 확장의 범위가 크다. 웹 서버는 이러한 etf 스크립트를 사용자에게 제공하기 위한 스크립트 엔진을 포함하고 있어야 하는데, 이러한 스크립트 엔진이 웹 서버와 어떻게 상호작용 하는가에 따라 성능이 좌우된다. 상호 작용하는 방법에는 스크립트 엔진이 웹 서버 자체에 포함된 경우, 스크립트 엔진을 수행하는 독립적인 프로세스를 띄워서 스크립트를 처리하는 방법, 스크립트 엔진만을 포함하여 처리하는 별도의 서버를 두어 처리를 전환하는 방법이 있다. 따라서 본 논문에서는 자바 웹 서버 상에서 엔진을 여러방법으로 연동하고 성능을 비교하여 보다 효과적인 처리 방안을 제안하고자 한다.

• Journal of Korean Society of Steel Construction
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• v.19 no.5
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• pp.515-526
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• 2007

In this study, the models and methods for the safety assessment of Steel-Concrete Hybrid Cable-Stayed Bridge, which consists of steel composite girder and concrete girder erected by the FCM(Free Cantilever Method) and FSM(Full Staging Method) are proposed for the assurance of structural safety and the prevention against bridge collapse during construction. By the structural reliability approach that reasonably considers the uncertainties associated with the resistance and the load effect, the resistance and the load distribution characteristics of Steel-Concrete Hybrid Cable-Stayed Bridgeare defined and the strength limit state equations of permanent structures and temporary structures during construction are suggested. An AFOSM algorithm and MCS technique are used for the reliability analysis of cables, pylons, girders, steel-concrete conjunction part and temporary bents. Also, component reliability analyses are performed at the construction stages based on the structural system model. To demonstrate their rationality and practicality, the proposed models and approaches are applied to a real bridge. The sensitivity analyses of main parameters are performed in order to identify the critical factors that control the safety of similar bridges. As a result, it may be stated that the proposed models could be implemented as a rational and practical approach for the safety assessment of Steel-Concrete Hybrid Cable-stayed bridges erected by FCM and FSM during construction.

• Applied Chemistry for Engineering
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• v.16 no.6
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• pp.809-814
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• 2005

In this work, the thermal properties of epoxy coating system on the liner plate in the containment structure of nuclear power plants had been examined by irradiation and design basis accident (DBA) conditions. The effect of immersion in hot water on adhesion strength of the coating system had been also studied. The glass transition temperature ($T_g$) and thermal stability of ET-5290/carbon steel A 32 epoxy coating systems were measured by DSC and TGA analyses, respectively. Contact angle measurements were used to determine the effect of immersion on the surface energetics of epoxy coating system, with a viewpoint of surface free energy. Adhesion tests were also executed to evaluate the adhesion strength at interfaces between carbon steel plate and epoxy resins. As a result, it was found that the irradiation led to an improvement of internal crosslinked structure in cured epoxy systems, resulting in significantly increasing the thermal stability, as well as the $T_g$. Also, the immersion in hot water made a role in the post-curing of epoxy resins and increased the mechanical interlocking of the network system, resulting in increasing the adhesion strength of the epoxy coating system.

• Journal of Korean Society of Steel Construction
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• v.27 no.1
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• pp.119-129
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• 2015

Due to reduced self weight and alleviated wind effect, the multi-column wind towers that consist of a number of circular tubes as vertical members interconnected with horizontal brace members can be a substitute for the large-scale single cylinder wind towers. It is critical to guarantee strengths of tubular joints where vertical and horizontal members are structurally connected in order to make the whole multi-column system behave as a single tower structure. In this study, strength evaluation has been conducted for T-type tubular joints that are applicable in multi-column towers. Four of available design codes, i.e., AISC, Eurocode3, ISO 19902, CIDECT have been investigated and predictor equations in the considered design codes were validated and discussed through parametric numerical study on slenderness ratios of chords and braces at joints.

• Journal of the Korea institute for structural maintenance and inspection
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• v.19 no.1
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• pp.53-61
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• 2015

This paper reports the test results of the floating floor system used to reduce the floor noise of apartment buildings. Recently, many soft resilient materials placing between the reinforced concrete slab and finishing mortar are used. The resilient material should not only reduce the floor impact sound vibration from the floor but also support the load on the floor. Thus, even if soft resilient materials satisfy the maximum limitation of light-weight impact sound and heavy-weight impact sound, these materials may not support the load on the floor. The experimental program involved conducting sixteen sound insulation floating floor specimens. Three main parameters were considered in the experimental investigation: resilient materials, loading location, and layers of floor. Experimental results indicated that the stiffness of resilient material significantly influenced on the structural behavior of floating floor system. In addition, the deflection of the floating concrete floor loaded at the side or coner of the specimen was greater than that of the floor loaded at the center of the specimen. However, the aerated concrete did not effect on the cracking strength of floating floor system.

• The Journal of the Korea Contents Association
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• v.17 no.5
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• pp.624-632
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• 2017

Automatic butterfly identification using images is one of the interesting research fields because it helps the related researchers studying species diversity and evolutionary and development process a lot in this field. The performance of the butterfly species identification system is dependent heavily on the quality of selected features. In this paper, we propose color intensity (CI) entropy by using the distribution of color intensities in a butterfly image. We show color intensity entropy can increase the recognition rate by 10% if it is used together with previously suggested branch length similarity entropy. In addition, the performance comparison with other features such as Eigenface, 2D Fourier transform, and 2D wavelet transform is conducted against several well known machine learning methods.

• Journal of the Korean Society for Railway
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• v.14 no.2
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• pp.143-150
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• 2011

This paper presents a preliminary study for air-tightness evaluation of vacuum tube structures for super-speed tube railway systems. The formula for flow rate of the air caused by the pressure difference of the inside and outside of the tube structure is derived based on Darcy's law. A test is then performed to measure the air-permeability of concrete with various compressive strengths, the result of which is used for analytical simulation of the air intrusion for a tube structure with a preliminarily defined section. It has been shown that concrete with the compressive strength of at least more than 50MPa is recommended for effective operation and maintenance of the vacuum pump systems, as the air-permeability of concrete is inversely proportional to the exponent of its compressive strength.

• Journal of the Korea institute for structural maintenance and inspection
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• v.16 no.1
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• pp.99-109
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• 2012

This study aimed to develop a Structural Health Monitoring System for steel beams in the manner of suggesting and verifying a theoretical formula for displacement estimation using strain gauges, and estimating the loading points and magnitude. According to the results of this study, it was found that when a load of 160kN (56% of the yield load) was applied, the error rate of the deflection obtained with a strain gauge at the point of maximum deflection compared to the deflection measured with a displacement meter was within 2%, and that the estimates of the magnitude and points of load application also showed the error rate of not more than 1%. This suggests that the displacement and load of steel beams can be measured with strain gauges and further, it will enable more cost-effective sensor designing without displacement meter or load cell. The Structural Health Monitoring System program implemented in Lab VIEW gave graded warnings whenever the measured data exceeds the specified range (strength limit state, serviceability limit state, yield strain), and both the serviceability limit state and strength limit state could be simultaneously monitored with strain gauge alone.