• 동력기계공학회지
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• 제8권3호
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• pp.44-51
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• 2004

Effect of corrosion characteristics in relation to loaded stress in the welded zone of A5083-H116 aluminum alloy, in the seawater was studied. The corrosion experiment was performed for 120 hours on the specimens in the natural seawater tank with four steps of the loaded stress. The corrosion crack, corrosion rate, electrode potential, current, and corrosion pattern, etc. were examined for the specimens with the elapse of the immersion time. The main result derived from this study is the crack growth length is increased with the increasing loaded stress. The electrode potential and the corrosion current are decreased rapidly in the early stage of the corrosion, and then decreased gradually and stabilized eventually with the elapse of the immersion time. The test condition of the longer crack growth tends to show the higher corrosion rate. Corrosion pattern of the welded zone indicates that the depth and width of the pitting become increasing with the increasing loaded stress.

• Ocean and Polar Research
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• 제24권1호
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• pp.1-18
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• 2002

Seasonal variation in global transport calculated from an ocean general circulation model (OGCM) has been assessed through the comparison with observational estimates. The OGCM based on the GFDL MOM1.1 has honzontal grid interval of 10 and 21 verticle levels, and was integrated for 31 years forced by climatological wind stress, freshwater flux, and heat flux with restoring. General features of the world ocean circulation are well reproduced, which include the western boundary currents such as the Kuroshio and the Agulhas Current, the Equatorial Current system, the Antarctic Circumpolar Current, and the Weddell Sea gyres. Also well resolved is the remarkable seasonal variation in the depth-integrated flows in the northern Indian Ocean due to the monsoonal wind. Monthly variation is found to be dominant in the transport of the Antarctic Circumpolar Current through the Drake Passage in accordance with observational estimates. It has been shown that the mid-latitude depth-integrated flows obey the Sverdrup relation, except for some regions such as continental shelf regions where the interaction between stratification and bottom topography is critical.

• 한국초전도ㆍ저온공학회논문지
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• 제1권1호
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• pp.33-37
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• 1999

The fast current and field ramp-up experiment was done with the superconducting magnet that is made of three non-insulated strand CICC (Cable-In- Conduit Conductor). The shunt the unbalanced current magnet enabled the unbalanced current measurement which is believed to be associated with the loop current. To explain the generation of the loop current during the current ramp up. the steady-state three strand loop current model was proposed. This model gives an explanation for the relation between the loop current and the twist geometry of the strands. According to this model. The twisr geometry and the surface contact resistance of the strand has significant influence on the generation of the loop current especially in the large superconducting magnet.

• 한국컴퓨터산업학회논문지
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• 제2권4호
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• pp.435-442
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• 2001

최근에 인터넷상에서 정보이용이 급증함에 따라 멀티미디어 정보를 효율적으로 관리하고 검색하기 위한 여러 가지 방법들이 제안되고 있다. 따라서 본 논문에서는 SRR(Semantic Reference Relation)과 DRR(Direct Reference Relation)을 이용한 새로운 그룹화 방법을 제안한다. 제안된 방법은 MDI(Multimedia Document Informations)를 멀티미디어 객체 클러스터로 간주하여 그룹화 한다. 제안된 방법의 성능을 알아보기 위하여 1000개의 멀티미디어 문서데이터를 테스트하며, 그 결과 제안된 방법의 성능이 보다 효율적임을 보인다.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2006년도 춘계학술발표회 논문집(I)
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• pp.570-573
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• 2006

It is proposed that the electromechanical relation of the conductive materials with high electrical resistance may be used to estimate the current stress of prestressing tendons. To choose the best conductive material to this end, we studied the electromechanical relations of carbon fibers and metalic heat wires experimentally. It is found that the relation of carbon fibers can be modelled by a parabolic(or hyperbolic) function in the early stage of deformation. Metallic heat wires show a consistent linear relation during loading and unloading in the elastic deformation and are suitable for this purpose. We propose a new kind of prestressing tendons whose stress can be monitored.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 1996년도 춘계학술대회 논문집
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• pp.252-255
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• 1996

Superconducting current lead is one of the promising applications of the oxide high-Tc superconductors, because they have the advantage of decreasing heat conduction to low temperature region, comparing with a conventional cooper alloy lead. High critical current density is a key factor for the applications such as current lead. (Bi,Pb)$_2$Sr$_2$Ca$_2$Cu$_3$O$\_$x/ high Tc superconductor haute been investigated in terms of critical current density. Bi-2223 superconducting current lead made by CIP and solid state sintering process. Bi-2223 current lead that heat treated at 836$^{\circ}C$ for 240 h in 1/13 P$\_$O$_2$/ had over 150 A/$\textrm{cm}^2$ of critical current density at 77K. We knew that the superconducting properties of tube type current leads were better than rods type of them. And we investigated the relation of Bi-2223 formation and heat treatment condition by XRD and SEM analysis.

• 대한전기학회논문지:전력기술부문A
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• 제51권10호
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• pp.525-533
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• 2002

It is common to install multiple lines in the same route. Recently, excessive sheath circulating current was partially measured in underground cable systems of KEPCO. Especially, the installation type, unbalance section length between joint boxes and zero sequence current by distribution cable have an effect on the rising of sheath circulating current in the underground transmission system. If excessive current flows in sheath, sheath loss which is reduced the transmission capacity is produced. This paper describes the relation analysis of sheath circulating current and burying types. And also, a detailed analysis on rising cause and characteristic of sheath circulating current by considering various unbalanced conditions presents using analysis and measurement regarding cable systems which have the problem of excessive sheath circulation current.

• 한국해안해양공학회지
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• 제4권1호
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• pp.26-33
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• 1992

파-흐름의 공존장에서 실트질 점토의 부상특성을 연구하기 위해 조파수조에 흐름발생장치를 설치하며 파낭만 존재하는 경우, 순류 및 역류가 존재하는 경우에 대해서 장적물의 부상실험을 하였다. 역류가 작용할 때가 순류가 작용할 때보다 부상량이 훨씬 많았는데 이는 역류가 작용할 때는 저면에 난류성분이 발달하지만, 순류가 작용할 때는 진동류 효과가 감소하기 때문이다. 파-흐름의 공존장에서 실트질 점토의 부상양계저면전단응력은 $ au$$_{c}$~0.045 N/$m^2$인 것으로 추정되었다. 초기부상률과 저면전단응력과의 관계식 및 초기부상률과 측정된 유의파고와의 관계식이 도출되었는데, 초기부상률과 저면전단응력과의 관계는 상당히 분산되어 나타났으나, 초기부상률과 측정된 유의파고와의 관계는 상관성이 양호하게 나타났다. 파동하에서 장적물의 농도가 거의 평형상태에 도달했을 때에 농도의 연직경사로부터 산정된 장적물의 연직확산계수는 저면에서 수심의 1/2 지점까지는 지수형태로 증가하는 양상을 나타냈으나, 그 이상부터는 수심에 관계없이 거의 일정하게 나타났다.다.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1996년도 하계학술대회 논문집 A
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• pp.376-378
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• 1996

This paper presents a new PFC control method which replaces a fast line current measurement with a filtered load current measurement. Using the power balance relation between the input and the output of the boost converter. the input current can be described as the function of load current. Thus the PWM signal which effects the switching control of the boost converter is generated using the PFC input voltage, the PFC output voltage and the load current as input variables. By using a filter between the bridge rectifier and a dc-to-dc converter, the input voltage of the dc-to-dc converter is forced to always maintain above zero volt. Then the input current traces a sinewave in phase. The proposed scheme accomplishes a very high power factor and a low harmonic distortion of the line current. The validity of this scheme is demonstrated through simulation.

• 한국세라믹학회지
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• 제31권12호
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• pp.1449-1458
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• 1994

A new analytical model which can discribe the relationship between the bridging stress and the crack opening displacement was proposed to investigate the microstructural effect on the R-curve behavior in a polycrystalline alumina. The crack opening displacement according to the distance behind the stationary crack tip was measured using in-situ fracture technique in an SEM, and then used for a fitting procedure to obtain the distribution of bridging stress. The current model and an empirical power law relation were introduced into the fitting procedure. The results indicated that the bridging stress function and R-curve computed by the current model were consistent with those computed by the power law relation. The microstructural factor, e.g., the distribution of grain size, was also found to be closely related to the bridging stress. Thus, this model explained well the interaction effect between the distribution of bridging stress and the local-fracture-controlling microstructure, providing important information for the systematic interpretation of microfracture mechanism including R-curve behavior of a monolithic alumina.