• 시스템엔지니어링학술지
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• 제19권1호
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• pp.29-38
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• 2023

Independent Safety Assessment (ISA) is a third-party assessment that is to confirm that the system satisfies the safety requirements in the defined operational context. The process of this assessment often brings about many complex arguments that should be supported by evidence and justification. The communication between arguments and evidence is of the most importance in the context of safety case. This study illustrates how NOR-STA can be used for ISA process, showing the effective structure of safety compliance. The study outlines the steps to breaks down the top goal into many elements such as arguments, sub-goals, justification, context and assumptions. It concludes that the evidence-based safety conformance process utilizing NOR-STA provides a more effective and systematic representation of the independent safety assessment process in conformance cases.

• 대한조선학회논문집
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• 제43권5호
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• pp.611-618
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• 2006

Recently, cryogenic butterfly valves for LNG carriers are actively developed by ship equipment companies. The dual core structure unlike usual butterfly valve has both translation and gyration motions of the disk of the valve assembly. Especially, the ship equipment companies can not have overcome 2D design method; in addition, even though 2 years of development has passed, the drawing cannot be secured. In this research, for the cryogenic butterfly valves and the product design, 3D design method was introduced and DMU(Digital Mockup) was applied to complement the problems in 2D design and investigate application possibility of 3D design method.

• 한국분말재료학회지
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• 제15권1호
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• pp.31-36
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• 2008

In this study, the bottom-up powder metallurgy and the top-down severe plastic deformation (SPD) techniques for manufacturing bulk nanomaterials were combined in order to achieve both full density and grain refinement without grain growth of rapidly solidified Al-20 wt% Si alloy powders during consolidation processing. Continuous equal channel multi-angular processing (C-ECMAP) was proposed to improve low productivity of conventional ECAP, one of the most promising method in SPD. As a powder consolidation method, C-ECMAP was employed. A wide range of experimental studies were carried out for characterizing mechanical properties and microstructures of the ECMAP processed materials. It was found that effective properties of high strength and full density maintaining nanoscale microstructure are achieved. The proposed SPD processing of powder materials can be a good method to achieve fully density and nanostructured materials.

• Advances in Computational Design
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• 제3권1호
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• pp.35-47
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• 2018

Design of settlement space is a complicated process while reasonable spatial layout bears great significance on the development and resource allocation of a settlement. The study proposes a weighted L-system generation algorithm based on CA (Cellular Automation) model which tags the spatial attributes of cells through changes in their state during the evolution of CA and thus identifies the spatial growth mode of a settlement. The entrance area of the Caidian Botanical and Animal Garden is used a case study for the model. A design method is proposed which starts from the internal logics of spatial generation, explores possibility of spatial rules and realizes the quantitative analysis and dynamic control of the design process. Taking a top-down approach, the design method takes into account the site information, studies the spatial generation mechanism of settlements and further presents a engine for the generation of multiple layout proposals based on different rules. A optimal solution is acquired using GA (Genetic Algorithm) which generates a settlement spatial layout carrying site information and dynamically linked to the surround environment. The study aims to propose a design method to optimize the spatial layout of the complex settlement system based on parametric generation.

• 한국분말재료학회지
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• 제14권1호
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• pp.26-31
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• 2007

Manufacturing bulk nanostructured materials with least grain growth from initial powders is challenging because of the bottle neck of bottom-up methods using the conventional powder metallurgy of compaction and sintering. In this study, bottom-up type powder metallurgy processing and top-down type SPD (Severe Plastic Deformation) approaches were combined in order to achieve both real density and grain refinement of metallic powders. ECAP (Equal Channel Angular Pressing), one of the most promising processes in SPD, was used for the powder consolidation method. For understanding the ECAP process, investigating the powder density as well as internal stress, strain distribution is crucial. We investigated the consolidation and plastic deformation of the metallic powders during ECAP using the finite element simulations. Almost independent behavior of powder densification in the entry channel and shear deformation in the main deformation zone was found by the finite element method. Effects of processing parameters on densification and density distributions were investigated.

• KIEAE Journal
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• 제11권2호
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• pp.67-74
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• 2011

Recently environmental regulations like the Kyoto Protocol, adopted in 1997, required the reduction of the greenhouse gas of 5.2% up to 1990's emissions and 13th General Assembly in 2007, held in Bali of India, have agreed to duty reduction even in developing countries in 2013. Korean government needs research on climate change and greenhouse gas management, such as carbon emissions calculation system and the introduction of greenhouse gas reduction program. Using Top-Down approach with method of IPCC, greenhouse gas emissions from energy, transportation, agriculture, land use and forest, and waste was calculated. Total amount from Shiheung-City in 2007 was about 3,299.581 tons of greenhouse gas $CO_2$. By sectors, the total greenhouse gas emissions in the energy sector mostly accounted for 78 percent, 12 percent from transportation, 6 percent of waste, the landuse/forest sector, 4% of the greenhouse gas emissions. Approximately 5,401,618 tons of the greenhouse gas $CO_2$ was total amount from Ansan-City in 2007. The share of energy sector greenhouse gas emissions was the highest portion of 79 % and 14 percent of transportation, 4% from the waste sector, 3 % from landuse/forest sector.

• 한국정보처리학회논문지
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• 제6권2호
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• pp.347-356
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• 1999

본 논문에서는 한국어 명사의 의미 개념의 계층을 생성하기 위한 시소러스 구성 방법과 시소러스를 구축하기 위한 개발 시스템을 구현하였다. 기존의 시소러스 구축에 있어서 나타나는 계층 설정의 비객관성 및 작업속도 문제, 비구조성, 비일관성 등의 문제를 해결하기 위하여 상향식과 하향식 방법을 혼합 적용하는 다단계 구축 방법을 사용한다. 온라인 전자 사전의 뜻풀이 문을 이용하여 객관성을 유지하고, 기존 시소러스의 기본 모델을 참조하여 비구조성과 비일관성의 문제를 해결한다. 또한 방대한 양의 표제어를 포함하는 시소러스를 빠른 시간 내에 구축하기 위하여 클라이언트/서버 환경의 개발 도구를 구현하여 여러 사람이 다중 입력 작업을 할 수 있도록 하였다.

• 로봇학회논문지
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• 제16권2호
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• pp.94-102
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• 2021

This study addresses a method for 3D reconstruction using acoustic data with heterogeneous sonar devices: Forward-Looking Multibeam Sonar (FLMS) and Profiling Sonar (PS). The challenges in sonar image processing are perceptual ambiguity, the loss of elevation information, and low signal to noise ratio, which are caused by the ranging and intensity-based image generation mechanism of sonars. The conventional approaches utilize additional constraints such as Lambertian reflection and redundant data at various positions, but they are vulnerable to environmental conditions. Our approach is to use two sonars that have a complementary data type. Typically, the sonars provide reliable information in the horizontal but, the loss of elevation information degrades the quality of data in the vertical. To overcome the characteristic of sonar devices, we adopt the crossed installation in such a way that the PS is laid down on its side and mounted on the top of FLMS. From the installation, FLMS scans horizontal information and PS obtains a vertical profile of the front area of AUV. For the fusion of the two sonar data, we propose the probabilistic approach. A likelihood map using geometric constraints between two sonar devices is built and a monte-carlo experiment using a derived model is conducted to extract 3D points. To verify the proposed method, we conducted a simulation and field test. As a result, a consistent seabed map was obtained. This method can be utilized for 3D seabed mapping with an AUV.

• 한국도로학회논문집
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• 제19권5호
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• pp.107-115
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• 2017

PURPOSES : The piezoelectric energy road analysis technology using a three-dimensional finite element method was developed to investigate pavement behaviors when piezoelectric energy harvesters and a new polyurethane surface layer were installed in field conditions. The main purpose of this study is to predict the long-term performance of the piezoelectric energy road through the proposed analytical steps. METHODS : To predict the stresses and strains of the piezoelectric energy road, the developed energy harvesters were embedded into the polyurethane surface layer (50 mm from the top surface). The typical type of triaxial dump truck loading was applied to the top of each energy harvester. In this paper, a general purpose finite element analysis program called ABAQUS was used and it was assumed that a harvester is installed in the cross section of a typical asphalt pavement structure. RESULTS : The maximum tensile stress of the polyurethane surface layer in the initial fatigue model occurred up to 0.035 MPa in the transverse direction when the truck tire load was loaded on the top of each harvester. The maximum tensile stresses were 0.025 MPa in the intermediate fatigue model and 0.013 MPa in the final fatigue model, which were 72% and 37% lower than that of the initial stage model, respectively. CONCLUSIONS : The main critical damage locations can be estimated between the base layer and the surface layer. If the crack propagates, bottom-up cracking from the base layer is the main cracking pattern where the tensile stress is higher than in other locations. It is also considered that the possibility of cracking in the top-down direction at the edge of energy harvester is more likely to occur because the material strength of the energy harvester is much higher and plays a role in the supporting points. In terms of long-term performance, all tensile stresses in the energy harvester and polyurethane layer are less than 1% of the maximum tensile strength and the possibility of fatigue damage was very low. Since the harvester is embedded in the surface layer of the polyurethane, which has higher tensile strength and toughness, it can assure a good, long-term performance.

• 기록학연구
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• 제56호
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• pp.147-182
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• 2018

무형문화유산은 형태가 없는 문화유산을 말한다. 급격한 사회의 변화와 더불어 무형문화유산의 보존은 더욱 중요해졌다. 무형문화유산은 사람을 통해 전승된다. 그러나 온전히 사람의 기억에 의존하여 무형문화유산을 보존할 수는 없다. 무형문화유산은 끊임없이 변화하고 이를 기록에 담아 보존하고 전승해야 한다. 이에 현재 무형문화유산 기록화의 현황을 파악하고 한계를 분석하였다. 그리고 그 대안으로 전수교육관에서의 무형문화유산 기록화를 제안한다. 전수교육관에서의 무형문화유산 기록화는 첫 번째, 현재의 행정기관 위주의 하향식 기록화의 한계를 극복하고 두 번째, 전승자와 보유단체의 관점이 담긴 기록화를 가능하게 한다. 세 번째로 무형문화유산 공동체의 역사와 정체성이 반영된 깊이 있는 무형문화유산 기록화를 할 수 있다. 네 번째, 무형문화유산의 전승성, 변이성, 지역성을 살려 기록화할 수 있다. 다섯 번째, 이러한 전수교육관 기반의 무형문화유산 기록화는 전수교육관 활성화에 기여할 수 있다. 무형문화유산법 제정과 국립무형유산원의 개원 이후 무형문화유산에 관한 제도, 정책뿐만 아니라 무형문화유산 기록관리도 빠르게 고도화되었으며, 기록에 대한 인식 또한 높아졌다. 변화에 힘입어 무형문화유산의 전승과 교육이 이루어지고 있는 가장 생생한 현장인 전수교육관에 주목하여 무형문화유산 기록의 기반을 마련하는 방안을 제시하였다.