• Structural Monitoring and Maintenance
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• 제5권3호
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• pp.363-377
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• 2018

The proper functioning of critical points on transport infrastructure is decisive for the entire network. Tunnels and bridges certainly belong to the critical points of the surface transport network, both road and rail. Risk management should be a holistic and dynamic process throughout the entire life cycle. However, the level of risk is usually determined only during the design stage mainly due to the fact that it is a time-consuming and costly process. This paper presents a simplified quantitative risk analysis method that can be used any time during the decades of a tunnel's lifetime and can estimate the changing risks on a continuous basis and thus uncover hidden safety threats. The presented method is a decision support system for tunnel managers designed to preserve or even increase tunnel safety. The CAPITA method is a deterministic scenario-oriented risk analysis approach for assessment of mortality risks in road tunnels in case of the most dangerous situation - a fire. It is implemented through an advanced risk analysis CAPITA SW. Both, the method as well as the resulting software were developed by the authors' team. Unlike existing analyzes requiring specialized microsimulation tools for traffic flow, smoke propagation and evacuation modeling, the CAPITA contains comprehensive database with the results of thousands of simulations performed in advance for various combinations of variables. This approach significantly simplifies the overall complexity and thus enhances the usability of the resulting risk analysis. Additionally, it provides the decision makers with holistic view by providing not only on the expected risk but also on the risk's sensitivity to different variables. This allows the tunnel manager or another decision maker to estimate the primary change of risk whenever traffic conditions in the tunnel change and to see the dependencies to particular input variables.

• Korean Chemical Engineering Research
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• 제52권6호
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• pp.750-754
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• 2014

초고농도 과산화수소 제조를 위한 투과증발 공정의 정량적 위험성 분석을 수행하였다. 잠재적 주요 사고는 분해반응에 따른 폭발 및 화재이며 실험실 규모일 때 사고결과는 카테고리 3에 속하는 것으로 판단된다. 대상공정에서 분해반응이 일어나는 과정을 사건트리 형태로 모델링하고 사고원인들의 확률함수를 유사사건 발생빈도 자료를 근거로 설정하였다. 구축된 모델을 사용하여 사고율을 계산한 결과, 수용 가능한 위험수준, 즉 사고빈도가 $10^{-4}/yr$ 이하가 되려면 추가 안전장치가 필요한 것으로 파악되었다. 이를 위해 방호계층분석을 적용한 결과, 촉매반응을 막기 위한 본질적 안전설계, 과열을 막기 위한 SIF (safety instrumented function), 그리고 분해반응이 일어나더라도 폭발로 이어지지는 것을 막는 릴리프 시스템이 요구되었다. 제안된 방법은 과산화수소 농축을 포함한 다양한 화학공정의 안전관리시스템 개발에 기여할 수 있을 것으로 기대된다.

• 문화기술의 융합
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• 제4권3호
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• pp.247-252
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• 2018

환경의 문제는 전세계적으로 인류가 꼭 해결해야 할 문제로 급박하게 다가오고 있다. 특히 우리나라는 중국과의 지정학적인 위치로 인한 대기, 해양 오염의 직접적인 피해를 입고 있으며, 국내적으로도 공기, 물, 토양, 기상 등으로 인한 수많은 오염 가능성에 노출되어 있다. 이런 상황 속에서 국가 환경관련 관리 도메인/서비스(시스템) 간 연계성 단절로 인해 환경오염이나 재해 발생시 신속한 원인 규명 및 상황 대처 능력이 취약하고, 중복 투자 발생 등의 과제를 안고 있다. 스마트 환경재해 관리를 위한 서비스 플랫폼 개발은 국가 차원의 스마트 환경재해 관리 및 환경관련 계측 및 자동측정 데이터의 국가적인 표준 프로토콜 정의를 통하여 융복합적인 스마트 환경관리를 통해 환경재해를 조기에 감지하고, 신종 복합 환경재해를 예측할 수 있는 방안이 될 것이다.

• Steel and Composite Structures
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• 제36권4호
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• pp.383-398
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• 2020

This paper investigates the progressive collapse behavior of 3D steel-framed gravity buildings under fires with a cooling phase. The effect of fire protections and bracing systems on whether, how, and when a gravity building collapses is studied. It is found that whether a building collapses or not depends on the duration of the heating phase, and it may withstand a "short-hot" fire, but collapses under a mild fire or a "long-cool" fire. The collapse time can be conservatively determined by the time when the temperature of steel columns reaches a critical temperature of 550 ℃. It is also found that the application of a higher level of fire protection may prevent the collapse of a building, but may also lead to its collapse in the cooling phase due to the delayed temperature increment in the heated members. The tensile membrane action in a heated slab can be resisted by a tensile ring around its perimeter or by tensile yielding lines extended to the edge of the frame. It is recommended for practical design that hat bracing systems should be arranged on the whole top floor, and a combination of perimeter and internal vertical bracing systems be used to mitigate the fire-induced collapse of gravity buildings. It is also suggested that beam-to-column connections should be designed to resist high tensile forces (up to yielding force) during the cooling phase of a fire.

• 사물인터넷융복합논문지
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• 제6권1호
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• pp.97-102
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• 2020

사물인터넷 환경에서 다중 객체의 스위치 제어는 고전압을 구동하기 위해 레벨 시프터가 있는 여러 솔리드 스테이트 구조로써 낮은 ON 저항과 양방향 릴레이 MOS 스위치를 통합했으며 외부 직렬 논리 제어에 의해 독립적으로 제어되어야 한다. 이 장치는 의료용 초음파 이미지 시스템, 잉크젯 프린터 제어 등의 IoT 기기뿐만 아니라, 켈빈 4 단자 측정을 사용한 PCB 개방 / 단락 및 누출 테스트 시스템과 같은 저전압 제어 신호에 의한 고전압 스위칭 제어가 필요한 응용 제품에 사용하도록 설계되었다. 이 논문에서는 FPGA (Field Programmable Gate Array) 테스트 패턴 생성을 사용한 아날로그 스위치 제어 블록의 구현 및 검증에 대하여 고찰하였다. 각 블록은 Verilog 하드웨어 설명 언어를 사용하여 구현된 후 Modelsim에 의해 시뮬레이션 되고 FPGA 보드에서 프로토타입화 되어 적용되었다. 제안된 아키텍처는 IoT 환경에서 여러개의 개체들을 동시에 제어하여야 하는 분야에 적용할 수 있으며 유사 형태의 IC를 테스트하기 위해 제안된 패턴 생성 방법을 적용할 수 있다.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2015년도 제49회 하계 정기학술대회 초록집
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• pp.55-55
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• 2015

Today, engineers are facing new set of challenges that are quite different from the conventional ones. Information technologies are rapidly commoditizing while the paths beyond the current roadmaps became uncertain as various technologies have been pushed to their limits. Along with these changes in IT ecosystems, grand challenges such as global security, health, sustainability, and energy increasingly require trans-disciplinary solutions that go beyond the traditional arenas in STEM (Science, Technology, Engineering and Mathematics). Addressing these needs is shifting engineering education and research to a new paradigm where the emphasis is placed on the consilience for holistic and system level understanding and the convergence of technology with AHSD (arts, humanities, social science, and design). At the center of this evolutionary convergence, nanotechnologies are enabling novel functionalities such as bio-compatibility, flexibility, low power, and sustainability while on a mission to meet scalability and low cost for smart electronics, u-health, sensing networks, and self-sustainable energy systems. This talk introduces the efforts of convergence based on the emerging nano technology tool sets in the newly launched School of Integrated Technology and the Yonsei Institute of Convergence Technology at Yonsei International Campus. While the conventional devices have largely depended upon the inherent material properties, the newer devices are enabled by nanoscale dimensions and structures in increasingly standardized and scalable fabrication platform. Localized surface plasmon resonance in 0 dimensional nano particles and structures leads to subwavelength confinement and enhanced near-field interactions enabling novel field of metal photonics for sensing and integrated photonic applications [1,2]. Unique properties offered by 1 dimensional nanowires and 2 dimensional materials and structures can enable novel electronic, photonic, nano-bio, and biomimetic applications [3-5]. These novel functionalities offered by the emerging nanotechnologies are continuously finding pathways to be part of smart systems to improve the overall quality of life.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2015년도 제49회 하계 정기학술대회 초록집
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• pp.61.1-61.1
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• 2015

Nanoscale semiconductor plasma processing has become one of the most challenging issues due to the limits of physicochemical fabrication routes with its inherent complexity. The mission of future and emerging plasma processing for development of next generation semiconductor processing is to achieve the ideal nanostructures without abnormal profiles and damages, such as 3D NAND cell array with ultra-high aspect ratio, cylinder capacitors, shallow trench isolation, and 3D logic devices. In spite of significant contributions of research frontiers, these processes are still unveiled due to their inherent complexity of physicochemical behaviors, and gaps in academic research prevent their predictable simulation. To overcome these issues, a Korean plasma consortium began in 2009 with the principal aim to develop a realistic and ultrafast 3D topography simulator of semiconductor plasma processing coupled with zero-D bulk plasma models. In this work, aspects of this computational tool are introduced. The simulator was composed of a multiple 3D level-set based moving algorithm, zero-D bulk plasma module including pulsed plasma processing, a 3D ballistic transport module, and a surface reaction module. The main rate coefficients in bulk and surface reaction models were extracted by molecular simulations or fitting experimental data from several diagnostic tools in an inductively coupled fluorocarbon plasma system. Furthermore, it is well known that realistic ballistic transport is a simulation bottleneck due to the brute-force computation required. In this work, effective parallel computing using graphics processing units was applied to improve the computational performance drastically, so that computer-aided design of these processes is possible due to drastically reduced computational time. Finally, it is demonstrated that 3D feature profile simulations coupled with bulk plasma models can lead to better understanding of abnormal behaviors, such as necking, bowing, etch stops and twisting during high aspect ratio contact hole etch.

• Earthquakes and Structures
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• 제10권2호
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• pp.367-388
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• 2016

Eccentrically braced frames (EBFs) represent an attractive lateral load resisting steel system to be used in areas of high seismicity. In order to assess the likely damage for a given intensity of ground shaking, fragility functions can be used to identify the probability of exceeding a certain damage limit-state, given a certain response of a structure. This paper focuses on developing a set of fragility functions for EBF structures, considering that damage can be directly linked to the interstorey drift demand at each storey. This is done by performing a Monte Carlo Simulation of an analytical expression for the drift capacity of an EBF, where each term of the expression relies on either experimental testing results or mechanics-based reasoning. The analysis provides a set of fragility functions that can be used for three damage limit-states: concrete slab repair, damage requiring heat straightening of the link and damage requiring link replacement. Depending on the level of detail known about the EBF structure, in terms of its link section size, link length and storey number within a structure, the resulting fragility function can be refined and its associated dispersion reduced. This is done by using an analytical expression to estimate the median value of interstorey drift, which can be used in conjunction with an informed assumption of dispersion, or alternatively by using a MATLAB based tool that calculates the median and dispersion for each damage limit-state for a given set of user specified inputs about the EBF. However, a set of general fragility functions is also provided to enable quick assessment of the seismic performance of EBF structures at a regional scale.

• 한국정보디스플레이학회:학술대회논문집
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• 한국정보디스플레이학회 2004년도 Asia Display / IMID 04
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• pp.1058-1061
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• 2004

Recently, According to companies of TFT LCD are making large sized products more and more. In the vortex of Products with a monitor and LCD TV is applied in a technique of a high viewing angle(FFS, IPS, VA). Also, as a high luminance, high speed response time, high degree of a color purity, and so on are continuing to develop a high performance, it is necessary to improve a specific character of high luminance that apply to LCD TV as a LCD BLU. Because a LCD panel for TV usually has a lower resolution that compare to a monitor, the structure of present backlight system can't put out its power even though it has a merit in transmission. Therefore, the examination of improvement about the high luminance direct typed BLU for LCD TV that presupposes several uses of CCFL(Cold Cathode Fluorescent Lamp) or EEFL(External Electrode Fluorescent Lamp)is actively being progressed. Although it is necessary to increase the number of lamps for applying high performance by the direct type, in this case, because we can design the character of luminance for adoption of high performance. We can satisfy with a level of luminance for LCD TV. Accordingly, we analyzed a change of the number of CCFL, mechanical and optical character to produce the direct typed backlight in 32inches spec. Consequently, we achieved luminance of 6597nit,which was including polarization film, and secured the standard for LCD TV.

• 한국방사성폐기물학회:학술대회논문집
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• 한국방사성폐기물학회 2004년도 학술논문집
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• pp.261-267
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• 2004

처분시스템 설계 시 기초 자료로 사용되는 국내 사용후핵연료의 발생량, 특징 및 연소이력 등의 현재 및 향후 현황을 파악하였다. 2055년까지 PWR 및 CANDU 사용후핵연료 발생량은 각각 20,500 및 14,800MTU로 나타났다.$17{\times}17$ 핵연료 집합체의 사용후핵연료 발생량비율은 2003년 기준으로 전체대비 60%를 점유하는 것으로 나타났으며, 2012년 이후부터는 .$16{\times}16$ KSFA 사용후핵연료 발생량이 .$17{\times}17$ 핵연료를 능가하기 시작하여 최종시점인 2055년에는 70% 정도를 점유할 것으로 보인다. 사용후핵연료의 평균 연소도는 90년대 후반에는 36GWD/MUT 정도, 2000년대 초반에는 40GWD/MTU를 나타냈으며, 2000년대 중ㆍ후반부터는 45GWD/MTU를 초과할 것으로 보인다. 따라서, 현재는 1997년에 선정한 제원을 기준 핵연료 제원으로 사용하되, 2010년을 기점으로 기준핵연료를 .$16{\times}16$ KSFA 4.5w/o, 55GWD/MTU로 반영하는 것이 타당해 보인다.