• Proceedings of the KIPE Conference
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• 전력전자학회 2011년도 전력전자학술대회
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• pp.388-389
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• 2011

본 논문에서는 서버용 전원 장치의 DC-DC단에 사용되는 디지털 전압 모드 제어기를 설계한다. 서버용 전원 장치는 2차 측에 고전류가 흐르는 사양으로 인하여 부하 전류에 따라 출력 인덕턴스 변화를 가지게 되며, hold-up time 규제를 만족하기 위하여 입력 전압의 변동 범위를 가진다. 이와 같은 조건은 제어기를 설계하는데 제약을 작용하게 되어 고정 이득을 가지는 방식에서는 최적화된 부하 변동 특성을 얻기 힘들다. 이와 같은 문제점을 해결하기 위하여 제어기의 이득 조정 기법을 제안하고 실험을 통하여 검증한다.

• 한국전산유체공학회:학술대회논문집
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• 한국전산유체공학회 2001년도 추계 학술대회논문집
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• pp.58-62
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• 2001

Aparallel computing environment was constructed based on Windows 2000 operating system. This cluster was configured using Fast-Ethernet system to hold up together the clients within a network domain. For the parallel computation, MPI implements for Windows such as MPICH.NT.1.2.2 and MP-MPICHNT.1.2 were used with Compaq Visual Fortran compiler which produce a well optimized executives for x86 systems. The evaluation of this cluster performance was carried out using a preconditioned Navier-Stokes code for the 2D analysis of a compressible and viscous flow around a compressor blade. The parallel performance was examined in comparison with those of Linux clusters studied previously by changing a number of processors, problem size and MPI libraries. The result from the test problems presents that parallel performance of the low cost Fast-Ethernet Windows cluster is superior to that of a Linux cluster of similar configuration and is comparable to that of a Myrinet cluster.

• Proceedings of the KSME Conference
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• 대한기계학회 2007년도 춘계학술대회A
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• pp.885-890
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• 2007

Fast Fourier Transformation(FFT) is one of the most useful way to analyze response signal for the purpose of grasping the dynamic characteristics of system. Vibration test using impact hammer is typical and simple experimental method widely used for catching hold of dynamic peculiar characters and modal behaviors of system. In this thesis, impact testing module for NI-PXI equipment is developed. The analyzing and visualizing module are developed with LabVIEW tool. A user can see quickly and easily modal shape of system after analyzing acquired data. This developed module will be expected to build up more convenient and serviceable measurement system.

• Journal of the Korean Operations Research and Management Science Society
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• 제1권1호
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• pp.127-138
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• 1976

Economists have become interested in the centralization and decentralization of planning, in the linking up of models into a homogenous model system, and in multi-level planning. In this study, Input/Output techniques used for explaining the resource allocation mechanisms to be more rational through detailed specifications of a large organization's objectives and explicit linking of centralization and decentralization to such objectives. Also the application of mathematical methods to the higher levels of planning in the optimal allocation resources can't fully describe the actual practice of planning. On the other hand, 1-0 techniques are standard in economic analysis and planning. However, the application procedures to the armed forces hold only when their assumptions are met and when their solutions are convergent. So, it is of limited applicability.

• Journal of Applied Reliability
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• 제11권4호
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• pp.357-369
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• 2011

Eco-robot for collecting recycling products is the machine which collects non-industrial wastes such as cans, PET bottles and etc. to reuse them as recycling resources. This eco-robot is operated in the condition that it should compress and hold various products without knowing their geometric shapes and material properties. For this reason reliability problems like malfunction or failure. comes to emerge, but the reliability test conditions to assess its performance and durability have not been founded yet. Therefore in this research failure mechanism of the eco-robot was analyzed and life test equipment which can reproduce actual usage conditions was developed. The compression levels in the life test were determined by measuring the crushing force acting on test products and Furthermore the test specimens which have equivalent shape and material properties with those of cans and PET bottles were proposed by simulating the deformation characteristics so that the actual compression conditions were set up in the test.

• Proceedings of the KSR Conference
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• 한국철도학회 2005년도 춘계학술대회 논문집
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• pp.109-114
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• 2005

Fiber optic sensors hold a great potential for structural monitoring due to their stability and durability. This paper deals with the applicability of long-gage deformation fiber optic sensors to prestressed concrete structures. Two sets of 3 m long-gage sensors are attached to the prestressed concrete girder with parallel topology. Using the quadratic regression of measured deformations over the length of sensors it is possible to extrapolate the deflection of the girder. The static response based on the developed method is compared with the results using conventional strain gages and LVDTs.

• Journal of Microbiology
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• 제43권2호
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• pp.179-182
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• 2005

The inefficiency of in vivo gene transfer using currently available vectors reflects a major hurdle in cancer gene therapy. Both viral and non-viral approaches that improve gene transfer efficiency have been described, but suffer from a number of limitations. Herein, a fiber-modified adenovirus, carrying the small peptide ligand on the capsid, was tested for the delivery of a transgene to cancer cells. The fiber-modified adenovirus was able to mediate the entry and expression of a $\beta$-galactosidase into cancer cells with increased efficiency compared to the unmodified adenovirus. Particularly, the gene transfer efficiency was improved up to 5 times in OVCAR3 cells, an ovarian cancer cell line. Such transduction systems hold promise for delivering genes to transferrin receptor overexpressing cancer cells, and could be used for future cancer gene therapy.

• Korean Journal of Cognitive Science
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• 제14권2호
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• pp.27-35
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• 2003

The present study, focusing on the stress-shift constructions, examines the tendency of young children to give wrong wide scope interpretation in language acquisition and questions the validity of the guess pattern hypothesis argued by Grodzinsky & Reinhart (1993). According to the hypothesis, children know that they have to construct a reference-set, keep two representations in working memory, and check whether the interpretation needed in the given context justifies selection of competing reference sets, but their working memory is not big enough to hold the materials needed to complete the execution of this task. Hence they give up and resort to a guess. 1 carried out an experiment of 16 Korean children aged 3;9 to 6;2 to find out whether children have more difficulty in the interpretation of stress-shift constructions than of constructions with a nuclear stress, and therefore perform the interpretation of the former by guessing. Assuming that the tendency is caused by a deficiency in contextual computation rather than reference set computation, I try to explain it in terms of pragmatic considerations.

• Journal of the Korean Society for Heat Treatment
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• 제10권4호
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• pp.232-236
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• 1997

A rectangular type circulating fluidized bed (CFB) with an internal nozzle and two partition walls was proposed. In this modified CFB, an internal nozzle and two slanted partition walls were additionally set in the riser. This cold mode apparatus was made of acrylic resin; the riser was 1500mm high and $1000{\times}1000mm^2$ in the cross sectional area, the internal nozzle was 200mm high and 10mm in the inner diameter, and the partition wall was 7mm thick. Glass beads of $91{\mu}m$ in the mean diameter were employed as bed materials. In the cold mode by using the proposed CFB with an internal nozzle, it was possible to change the particle hold up by changing the gas flow ratio of the nozzle to the total(Qn/Qt). It was found that the inflection point which devided the bed structure between the dense and the dilute phase in the riser varied with Qn/Qt.

• Bulletin of the Society of Naval Architects of Korea
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• 제20권1호
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• pp.29-33
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• 1983

The loading condition, of a ship, especially a multi-purpose cargo carrier, in service, is often changed. Then, the prediction of natural frequency changes is necessary to provide measures for prevention of ship vibrations. In this paper a simplified method for the above purpose is presented. The bases of the method are analytical solutions for the lateral vibrations of uniform Timoshenko beams carrying a concentrated mass and the Dunkerley's formula. In this method a ship in the standard ballast condition is reduced to a uniform Timoshenko beam having same system parameters as those of the midship section. To investigate the validity of the proposed method, numerical calculations are carried out for a 46,000 DWT bulk carrier and compared with detailed calculations based on the finite difference method. Even in cases those the cargoes in a hold, length of which is about 13% of the ship's length, are reduced to a concentrated mass, the proposed method gives results of several percent differences from the detailed calculations up to the six-noded mode.