• 터널과지하공간
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• 제7권4호
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• pp.323-333
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• 1997

A rock mass is usually classified by the results of geological survey and laboratory tests on rock specimens in order to obtain the adequate properties for the numerical analysis. For these purposes a rock mass strength is estimated based on the empirical criterion proposed by Hoek and Brown and a modulus of deformation is taken with the empirical relations developed by Bieniawski, Serafim and Pereira. In addition, the $K_o$ value which is the ratio of the horizontal stress to the vertical stress is one of the most important input data in the numerical analysis. Its role on a tunnel stability analysis could be verified with the numerical results taken by a finite difference code or a distinct element code. However, a deduced value used to be applied for the $K_o$ value in most of tunnel designs, even though the patterns of stress tensor are variable with regions and depths. Thus in situ stresses were measured by a hydraulic fracturing technique on several tunnel sites and applied directly to the tunnel design for the enhancement of its precision. With those informations on in situ stresses, the safe design should be obtained economically on the road or subway tunnels.

• 한국가구학회지
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• 제28권1호
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• pp.16-26
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• 2017

In today's aging society, stable residential environment is essential for the elderly living alone to be able to do activities of daily living without restrictions and cherish a satisfactory quality of life. We developed a safe and convenient multifunctional sofa by removing complex combinations and decomposing processes of the multifunctional transformable furniture, appropriate for the use by elderly living alone. We deduced the 4 main keywords and details related to the purpose of sofa by analyzing the users' physical and mental characteristics through literature review and by using 24-hour scheduling, interviews, and actual measurement. Finally, by applying this to furniture planning, we designed 4 different types of multifunctional sofa system. Production was done in cooperation with AND Co. for 2 weeks using materials, colors and adhesives selectively chosen with careful consideration of their effects on the physical, mental aspects of the user to give optimal comfortability.

• 한국실내디자인학회논문집
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• 제19권5호
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• pp.234-242
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• 2010

In order to make an effective use of spatial resources in the city, detailed environmental plan strategies based on 'culture' are needed. An integral part of city spaces-'underground space' serves as one of the spatial resources with much effective usage potentials. Hence, 'underground space' needs cultural vitality. The purpose of this study is to propose an thorough indoor environmental plan guideline for the cultural vitality of 'underground space'. The methods used to conduct research include precedent study reviews and survey. Through this research, following conclusions are drawn. First, to promote cultural vitality at the 'underground space', it must be transformed into the cultural public place to be utilized for cultural activities by residents. Second, the 'underground space' requires 'concept of eco-friendly space for clean environment'. Third, 'safe environment' concept must be installed in the 'underground space' to promote the cultural vitality. Fourth, the 'underground space' requires 'complex/block level network plans between cultural spaces in addition to horizontal/vertical walking network between cultural environments in ground level and underground spaces. Fifth, the 'underground space' requires underground public cultural space plan through 'reasonable underground development with considerations of the facilities related to education, culture and history'. Sixth, 'public cultural space plan for various cultural spaces' and 'supply of space for cultural activities for residents and design plan for mutual culture exchange' are necessary.

• 한국실내디자인학회논문집
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• 제23권3호
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• pp.181-192
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• 2014

Recently, urban mixed-use commercial facilities have been required to raise a safe environment in public areas. So, this study focuses on analyze planning factors selected through the precedent research for Pedestrian safety and environment of urban mixed-use commercial facilities. The first purpose of this study is to analyse the applicative estimation of environmental plan to support pedestrians in public space of urban mixed-use commercial facilities in Seoul. And the second purpose of this study is to propose the directions of environmental planning for creating a pedestrian-friendly environment in public space of urban mixed-use commercial facilities. In order to accomplish this purpose, the environmental planning factors for supporting pedestrians and guidelines for disabled shown in the precedent studies are drawn. A survey of research subjects are 4 urban mixed-use commercial facilities located in downtown Seoul. And then a questionnaire survey is performed on architecture and interior design students to evaluate the importance. As a result of the study, the following conclusion are drawn. The pedestrian-friendly environment in urban mixed-use commercial facilities requires planning to strengthen accessibility, supporting and safety of public space.

• Journal of Welding and Joining
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• 제34권5호
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• pp.41-46
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• 2016

Welding is an absolutely essential component of industries such as the automotive industry, the construction industry and even the aviation industry. Although it is a widespread technology it is still characterized by lots of uncertainties. This still requires well experienced and highly skilled workforce to design and perform safe welding processes. The early knowledge of distortion and residual stresses is almost an issue which is influenced mainly by the welding parameters and the fixture design. But more and more engineers want to know as well final properties of the assembled components. With the beginning of the computer age in the 1970s and 1980s last century, the numerical prediction of manufacturing processes using FEM was gradually getting better and has established itself in the industry since the 1990s as a standard tool. Unlike in metal casting and forming industry, however, the everyday use of FEM- simulation tools for welding processes eked out a shadowy existence for a long time. This paper will give a short classification of welding simulation types and a structured overview on the technical questions. Selected case studies and the benefits achieved through simulations with the software Simufact welding are discussed. Finally an outlook on future developments will be given.

• Journal of Computational Design and Engineering
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• 제3권1호
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• pp.63-70
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• 2016

Deep drawing is a forming process in which a blank of sheet metal is radially drawn into a forming die by the mechanical action of a punch and converted to required shape. Deep drawing involves complex material flow conditions and force distributions. Radial drawing stresses and tangential compressive stresses are induced in flange region due to the material retention property. These compressive stresses result in wrinkling phenomenon in flange region. Normally blank holder is applied for restricting wrinkles. Tensile stresses in radial direction initiate thinning in the wall region of cup. The thinning results into cracking or fracture. The finite element method is widely applied worldwide to simulate the deep drawing process. For real-life simulations of deep drawing process an accurate numerical model, as well as an accurate description of material behavior and contact conditions, is necessary. The finite element method is a powerful tool to predict material thinning deformations before prototypes are made. The proposed innovative methodology combines two techniques for prediction and optimization of thinning in automotive sealing cover. Taguchi design of experiments and analysis of variance has been applied to analyze the influencing process parameters on Thinning. Mathematical relations have been developed to correlate input process parameters and Thinning. Optimization problem has been formulated for thinning and Genetic Algorithm has been applied for optimization. Experimental validation of results proves the applicability of newly proposed approach. The optimized component when manufactured is observed to be safe, no thinning or fracture is observed.

• KIEAE Journal
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• 제8권2호
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• pp.65-70
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• 2008

Recently, there has been growing interest in barrier-free design which makes safe and convenient space for every pedestrian, not only the non-disabled but also the disabled. The purpose of this study is to suggest the data on the pavement materials of barrier-free pedestrian environment in view of universal design. In order to this, the research is focused on evaluating the visual preference and preference factors for pavement scenery, which can be changed by pavement materials. And this research is also comparing the visual preference and preference factors of the disabled with that of the non-disabled. A multi-regression analysis method is adopted to analyse the correlation between the visual preference for pavement scenery and preference factors in this study. The result of this analysis is as follows. Firstly, there are some differences of visual preference for the pavement material between the disabled and the non-disabled. Secondly, independent variables influencing on preference are similar between two groups. Thirdly, there are some differences in the priority of preference between the disabled and the non-disabled. This study will contribute to the field of barrier-free design and sustainable development projects in order to maximize the human being's satisfaction.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1999년도 하계학술대회 논문집 F
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• pp.2597-2600
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• 1999

Semiconductor devices can be series stacked for the application of high voltage switching. It can provide high reliability and long lifetime by the safe design with a reasonable margin. The equal voltage distribution at solid-state switches in series should be guaranteed. Static and dynamic voltage division, over current protection must be considered carefully in the design stage. A fast switching thyristor is a good candidate for the high power pulse applications. A high voltage switching module is designed and tested. Its specifications are working voltage of 70 kV, switching pulse width of 120${\mu}s$, peak switching current of 220A, maximum repetition rate of 200pps. The module can be series connected to get higher working voltage. This paper presents the design details and the test results are compared with expected circuit simulations.

• 전산구조공학
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• 제7권1호
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• pp.83-90
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• 1994

국내의 설계지진은 상대적으로 작은규모 이지만 일점고정 연속교에 있어서는 지진시 교축방향의 고정지점에 상부구조의 모든 관성력이 집중됨에 따라 그 교각과 기초구조에는 상당히 큰 교축방향 수평력이 작용하게 된다. 기존의 교량의 내진설계 방법에서는 교각의 비탄성거동에 의존하는 수정응답계수를 사용하여 교각의 설계하중을 낮추어 설계에 사용하고 있으나 이는 교각의 비탄성거동으로 인한 손상과 그에 따른 큰 상부구조의 변위를 초래할 가능성이 있다. 본 연구에서는 내진분리베어링이 설치된 교량의 비선형 동적 방법을 제시하고 대표적인 내진분리베어링인 lead-rubber 베어링을 고정받침대신 사용하였을 경우 국내 설계 응답스펙트럼에 상응하는 지반운동하에서 교량의 응답특성을 살펴보았다. 내진분리베어링이 설치된 교량의 비선형 동적해석을 통해 1초이하 주기의 교량에 있어서 lead-rubber 베어링의 사용은 상당한 교축방향의 수평력 감소효과를 가져오며 상부구조의 수평변위도 그리 크지 않음을 보였다. 따라서 교량의 내진설계시 내진분리베어링의 사용으로 경제성과 내진안전성을 동시에 얻을 수 있을 것이다.

• 한국해양공학회지
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• 제29권4호
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• pp.309-316
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• 2015

Lifting lugs are frequently used in shipyards to transport and turn over the blocks of ships and offshore structures. With the development of shipbuilding technology, blocks have increased in size, and block management technology has assumed a more important role in shipbuilding to enhance the productivity. For the sake of economics, as well as the safe design of a lug structure, a more rational design procedure based on a rigorous structural analysis is needed. This study investigated the strength characteristics of T-type lugs, considering the influence of blocks on which lugs are attached, by varying the in-plane and out-of-plane load direction. In this paper, the ultimate strength is also addressed for cases that include or do not include blocks in the strength analysis. In the present results, when there was a load acting in the normal direction to the block surface, the strength characteristics became poor, and the ultimate strength decreased. This paper ends by describing the need for further study to develop a more rational design for a lug structure.