• Journal of the Earthquake Engineering Society of Korea
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• v.3 no.3
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• pp.33-44
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• 1999

An energy balance procedure is developed to incorporate the effects of earthquake duration which involves the effect of cyclic loading and the corresponding cumulative plastic deformation. Particular emphasis is given to the flexural failure of non-seismically designed columns of reinforced concrete frames. For this, conceptual strength deterioration models for columns, governed by concrete, anchorage failure and longitudinal steel fracture due to low-cycle fatigue, are proposed. It is evident that the energy-based method has good agreement with the experimental data and is able to predict the failure mode.

• Progress in Superconductivity and Cryogenics
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• v.17 no.3
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• pp.41-46
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• 2015

Recently, the development of the HTS power cable is actively promoted. As the length of HTS power cable increases, there have been many efforts to develop large capacity cryocooler. Among the various cryocooler, the Brayton refrigerator is the most competitive for HTS power cable. The Brayton refrigerator is composed of recuperative heat exchangers, a compressor, and a cryogenic turbo expander. In these components, the cryogenic turbo expander is a part to decrease the temperature and it is the most significant component that is closely related with overall system efficiency. It rotates with high speed using a high-pressure helium or neon gas at cryogenic temperature. This paper describes the design of a 10 kW class Brayton refrigeration cycle and the cryogenic turbo expander. Flow and structural analysis are performed for the rotating impeller and nozzle to verify the efficiency and the design performance.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2007.11a
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• pp.41-44
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• 2007

Ground test facility for the hypersonic propulsion system was designed, constructed and performance test was conducted. The design point was selected using quasi，1-Dimensional CFD analysis before the conceptual design for construction of hypersonic facility After that, specific designs for performance and components were completed using unit analysis CFD code and performance tests were conducted for the various operation conditions.

• Korean Journal of Computational Design and Engineering
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• v.8 no.4
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• pp.222-230
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• 2003

Artificial intelligence has been used in the configuration design stage of high-speed train. The traction system of a high-speed train is composed of transformers, motor blocks, and traction motors of which locations and number in the trainset should be determined in the early stage of the train conceptual design. Components of the traction system are heavy parts in the train, so it gives strong influence to the top speeds and overall train configuration of high-speed trains. Top speeds have been predicted using the neural network with the associated data of the traction system. The neural networks have been learned with data sets of many commercially operated high-speed trains, and the predicted results have been compared with the actual values. The configuration design of the train set of a high-speed train determines the basic specification of the train and layout of the traction system. The neural networks is a useful design tool when there is not sufficient data for the configuration design and we need to use the existing data of other train for the prediction of trainset in development.

• Corrosion Science and Technology
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• v.4 no.5
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• pp.201-206
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• 2005

Starting with the meaning of the word quality, diverse concepts connoted by the term are examined. Instead of a bathtub curve, the desirable shape of a failure rate covering the entire life of a good product, which might be called hockey-stick line, is introduced. From the hockey-stick line and the definition of reliability, two measurements are extracted. The terms r-reliability (failure rate) and durability (product life) are explained. The conceptual analysis of failure mechanics explains that reliability technology pertains to design area. The desirable shape of hazard rate curve of electronic items, hockey-stick line, clarifies that Mean-Time-to-failure (MTTF) as the inverse of failure rate can be regarded a nominal life. And Bx life, different from MTTF, is explained. Reliability relationships between components and set products are explained. Reshaped definitions of r-reliability and durability are recommended. The procedure to improve reliability and the reasons for failing to identify failure mode are clarified in order to search right solutions. And generalized Life-Stress failure model is recommended for the calculation of acceleration factor.

• Proceedings of the CALSEC Conference
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• 2004.02a
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• pp.355-377
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• 2004

Mobile business, noticed as a constructive alternative for e-commerce and e-business, has been diversely defined and conceptualized. This study develops a comprehensive framework for the sake of clearing such a havoc of conceptual deluge. The framework for the comprehensive understanding of e-business (including m-business) consists of two dimensions： connectivity and mobility. These two dimensions represent to overcome the constraints of time and place in business transactions, respectively. Various cases for each combination of these two components are explained for clear understanding of this framework. By this framework, we can understand the value that Location-Based Service (LBS) brings anew to e-business services.

• Korean Management Science Review
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• v.16 no.2
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• pp.33-49
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• 1999

The management of enterprise knowledge has been increasingly important because knowledge emerges as the new basis of competition in postcapitalist society. One of the key issues in knowledge management is to put knowledge into a repository where it can be easily stored, reused, and recreated. This paper proposes a model repository and the corresponding knowledge management framework. The emphases of model repository is on abstraction knowledge in the form of schematic models. Two major benefits are model independence and model integration. A metaschema is constructed according to six conceptual components: separate unit, external link, internal link, separate unite descriptor, link descriptor, and composite descriptor, which can be applied for a variety of models. A prototype system with a case illustrates the practical usefulness of model repository for knowledge management.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2004.10a
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• pp.171-174
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• 2004

Superalloys with many strengthening alloying elements are frequently used in powder form to alleviate harmful effects of alloy segregation. HIP (hot isostatic pressing) and DB (diffusion bonding) as a form of solid-state bonding process is often used to make turbine components, such as integrated turbine rotors. HIP/DB process requires many technical overcomes related to dimensional changes as well as microstructural control. In this research, HIP/DB process for nickel base superalloys, Udimet 720, were investigated with a view to control the dimensional change during the consolidation process. Simple disc-shaped cans were used to select the conceptual die design for the control of the dimensional change especially in radial direction. The change in the shape of consolidated shape was investigated using commercial FE code with constitutive equations for low temperature plasticity and creep deformation.

• Proceedings of the Korean Vacuum Society Conference
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• 2011.02a
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• pp.397-397
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• 2011

In a low aspect ratio (LAR) tokamak reactor with a superconducting toroidal field (TF) coil, the radial build of TF coil and the shield play a key role in determining the size of a reactor. For self-consistent determination of the reactor components and physics parameters, a system analysis code is coupled with one-dimensional radiation transport code. Conceptual design study of a compact superconducting LAR tokamak reactor with aspect ratio less than 2.5 was conducted and the optimum radial build was identified. It is shown that the use of an improved shielding material and high temperature superconducting magnets with high critical current density opens up the possibility of a fusion power plant with compact size and small re-circulating power simultaneously at low aspect ratio, and that by using an inboard neutron reflector instead of breeding blanket, tritium self-sufficiency is possible with outboard blanket only and thus compact sized reactor is viable.

• Proceedings of the Korean Society for Emotion and Sensibility Conference
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• 2002.05a
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• pp.342-347
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• 2002

한국인 20대 여성 얼굴을 대표하는 30개 얼굴의 감성 형용사 평정을 통해 아름다운 얼굴의 감성 특징을 파악하였다. 얼굴 감성을 나타내는 14개 형용사 평정에 대해 주성분 분석을 실시한 결과 얼굴 감성은 샤프 요인과 소프트 요인으로 나뉘며, 사람들이 소프트한 느낌보다 샤프한 느낌을 지닌 얼굴을 더 아름답다고 느끼는 것으로 나타났다. 아름다운 얼굴의 감성 특징 검증을 위해 얼굴 합성법을 이용하여 합성한 이미지에 대해 얼굴 미모와 감성 형용사 평정을 실시하였다. '상위 평균' 이미지는 '전체 평균' 이미지보다, 전체 평균과 상위 평균의 얼굴 특징 차이를 50% 과장한 '상위+50' 이미지는 '상위 평균' 이미지보다 유의미하게 더 아름다운 것으로 평정되었다. 합성 얼굴의 감성 평정 결과 '전체 평균' 이미지는 소프트 감성에서 높은 평정을 받았으며, '상위 평균' 이미지는 샤프 감성, '상위150'이미지는 두 감성 요인을 모두 지니는 것으로 나타났다. 이러한 결과는 샤프 혹은 소프트 중 하나의 감성 요인이 두드러진 얼굴보다 두 가지 감성 요인 모두에서 높은 평정을 받은 얼굴을 더욱 아름답다고 지각하는 것을 암시한다.