• 한국산학기술학회논문지
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• 제8권6호
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• pp.1579-1582
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• 2007

본 연구는 광촉매를 이용, 수용액내 유기오염물질 분해 성능을 비교하여 난분해성 오염물질을 분해하는 최적의 조건을 찾는 것으로 반응기 내부의 광원의 파장에 따른 세기와 광촉매 물질의 상태에 따라 고찰하였다. 그 결과, $500^{\circ}C$에서 30동안 소성한 실리카 비드가 가장 뛰어난 반응성을 나타냄을 알 수 있었다.

• Journal of Power Electronics
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• 제14권3호
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• pp.432-443
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• 2014

In order to improve the output efficiency of solar cells and to extend the life span of batteries, the input currents of converters are required to be continuous. If low output voltage ripple is required at the same time, it is obvious that the application of basic two-order converters (such as Buck and Boost derived converters) will not be good enough. In this paper, a lot of non-isolated push-pull converters (NIPPCs) with continuous current will be introduced due to their lower current stress, higher efficiency and better EMC performance. By decomposing the converters into push-pull cells, inductor and free-wheeling diodes, two families of NIPPCs based on single inductor and coupled inductor separately are systematically generated. Furthermore, characteristics analyses for some of the generated converters are also shown in this paper. Finally, two prototypes based on the corresponding typical topologies are built in the lab to verify the theoretical outcomes.

• 한국미생물·생명공학회지
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• 제24권5호
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• pp.619-623
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• 1996

Some physical and physiological properties of di-D-fructofuranose dianhydrideIII (DFAIII), as a new sweetener, were investigated via in vitro experiments. The disaccharide was prepared by decomposing inulin with inulin fructotransferase (depolymerizing) from Arthrobacter sp. A-6. DFAIII had more excellent heat and acid stability than sucrose. This was one of the most desirable properties especially for the oligomer types of sweetener. DFAIII showed the least pH drop in the Streptococcus mutans culture, compared with the other saccharides examined. This indicates that the sugar will be fairly effective for preventing dental caries. The saccharide also had a selective Bifidus growth-promoting effect in PYF medium. Whereas, E. coli did not show growth promotion in the DFAIII-containing medium. In the co-culture of Bifidus longum and E. coli in the BL medium, Bifidus longum had a selective growth while the growth of E. coli appeared rather to be inhibited.

• 한국방재학회:학술대회논문집
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• 한국방재학회 2008년도 정기총회 및 학술발표대회
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• pp.439-442
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• 2008

Diffraction of multi-directional random waves passing semi-infinite breakwater is investigated by using analytic solution derived by Penny and Prices(1952). An irregylarity of period and incident angle of waves and regular periods for regular waves are considered in addition by expanding from the past study which used only monochromatic wave in general. The Bretschneider-Mitsuyasu frequency spectrum and Mitsuyasu directional spectrum are used for incident waves. And diffraction of multi-directional random waves is reappeared by decomposing numerical results of several monochromatic waves which have variable period and incident angle. Analytic solution on the diffraction of regular waves and multi-directional random waves calculated in this study.

• 연구논문집
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• 통권24호
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• pp.81-96
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• 1994

To investigate failure mechanisms observed in carbon-phenolic thermal insulators, differential equations which govern the decomposition process in a deformable anisotropic porous solid are derived for three-dimensional axisymmetric constructions. The governing equations not only couple the material deformation with pore pressure, but also couple pressure and temperature, which means that heat convected by the pyrolysis gases is properly accounted for. Then the Bubnov-Galerkin finite element method is applied to these equations to transform them into a semidescrete finite element system. A thermal insulation liner in the cowl region under typical operating conditions is analyzed to find a mechanism for plylift. The results from the structural analysis show across-ply failure in the cowl zone. The mechanism for plylift is hypothesized as a sequential procedure : 1) the across-ply failure which is the precursor to plylift and 2) the local fiber buckling caused by generation of excessive in-plane compressive stress. To prevent plylift, the across-ply stress can be reduced by using appropriate material ply angles in cowl zone design.

• 한국정보통신학회:학술대회논문집
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• 한국해양정보통신학회 2004년도 춘계종합학술대회
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• pp.595-598
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• 2004

본 연구에서는 패턴인식과 영상압축을 목적으로 다치영상의 형태론적 형상분해법을 제안하였다. 다치영상내에 포함된 형상들을 직접적으로 기술하는 방법은 데이터 압축과 계산시간의 측면에서 그 효과를 기대할 수 없다. 따라서 본 연구에서는 2진수로 표현되는 화소 값을 그레이 코드로 변환한 다음, 그레이 코드로 변환된 화소들 중에서 특정비트가 1인 화소들만을 선택해서 얻은 8개의 비트평면 영상에 포함된 형상을 형태론적 멀티모드 형상분해 알고리즘을 적용하여 분해하였다.

• Journal of Power Electronics
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• 제10권6호
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• pp.724-732
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• 2010

This paper presents an effective rotor current controller for variable-speed stand-alone doubly fed induction generator (DFIG) systems feeding an unbalanced three-phase load. The proposed current controller is developed based on proportional plus two resonant regulators, which are tuned at the positive and negative slip frequencies and implemented in the rotor reference frame without decomposing the positive and negative sequence components of the measured rotor current. In addition, the behavior of the proposed controller is examined in terms of control performance and stability with respect to rotor speed variations, i.e., slip frequency variations. Simulations and experimental results are shown to validate the robustness and effectiveness of the proposed control method.

• 전기학회논문지
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• 제61권1호
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• pp.162-167
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• 2012

In power quality monitoring, it is very important to detect disturbances (sag, swell, transient, and interruption) accurately. In this paper, a detection method for power quality disturbances by combining the filter bank system and adaptive filter is proposed. To decompose power signal, binary tree structured filter bank system is designed. In the filter bank system, the fundamental filter bank(QMF bank) is used as a module in each decomposing level. An adaptive filter is used to improve the detection accuracy of disturbances for each subband signal. In the adaptive filter, the measure of estimated error change is used to detect singular points of power quality disturbances. Computer simulations were performed on synthetic signals which have disturbances to assess the performance of the proposed method.

• 대한원격탐사학회:학술대회논문집
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• 대한원격탐사학회 2003년도 Proceedings of ACRS 2003 ISRS
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• pp.1268-1271
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• 2003

In the edge detection of RS image, the useful detail losing and the spurious edge often appear. To solve the problem, we use the dyadic wavelet to detect the edge of surface features by combining the edge detecting with the multi-resolution analyzing of the wavelet transform. Via the dyadic wavelet decomposing, we obtain the RS image of a certain appropriate scale, and figure out the edge data of the plane and the upright directions respectively, then work out the grads vector module of the surface features, at last by tracing them we get the edge data of the object therefore build the RS image which obtains the checked edge. This method can depress the effect of noise and examine exactly the edge data of the object by rule and line. With an experiment of a RS image which obtains an airport, we certificate the feasibility of the application of dyadic wavelet in the object edge detection.

• Asia pacific journal of information systems
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• 제9권1호
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• pp.193-209
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• 1999

Developing Information Systems is a process of decomposing the entire systems into sub systems and identifying a hierarchical structure among the sub systems. Diagrammatic representation of hierarchy is an essential part of systems development since the identified hierarchical structures are usually presented in diagrams. The main goal of this research is to identify the most effective ways of representing system structures using diagrams. In order to achieve the main goal, this study performed three phases of research. In the first step, a theoretical model was constructed to conceptually explain users' comprehension on diagrams. Then visual factors of diagrammatic representations were identified based on the diagrams used in systems development. Finally, three consecutive experiments were conducted to identify the impacts of visual factors on the level of users' comprehension. The results indicate that familiarity and affordance of diagrams affect the degree of comprehension about the diagrams, which is in turn influenced by the complexity of tasks and the types of hierarchies. This paper concludes with the limitations of the study results and implications in the development of information systems.