• 한국세라믹학회지
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• 제48권4호
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• pp.263-268
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• 2011

ZnO hexagonal rods grown in aqueous solution can be changed into a tubular shape by two-step aging in the course of the growing process. In the first step, hexagonal ZnO rods is grown by aging at $90^{\circ}C$ under a highly supersaturated aqueous solution giving rise to a fast precipitation rate. Meanwhile, during the second step aging at $60^{\circ}C$ in the same aqueous solution, the hexagonal polar face (001) having higher surface energy than (010) side planes dissolves to minimize surface energy. Hence the flat (001) face changes to a craterlike face and the hexagonal rod length of ZnO decreases at an initial-stage of this step aging. The formation of the (101) wedge-type faces is ascribed to the resultant of competitive reactions between the dissolution of polar face minimizing the surface energy which is a dominant reaction at the initial stage and the precipitation reaction dissipating supersaturation. At a later stage of the second-step the reaction rates of these two processes in the aqueous solution become similar and the overall reaction is terminated.

• 한국항해항만학회:학술대회논문집
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• 한국항해항만학회 2012년도 춘계학술대회
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• pp.388-389
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• 2012

현재 해상풍력 발전 타워는 강구조로 제작되고 있으며, 발전용량의 증가에 따라 타워 구조체 또한 장대화 되는 추세이다. 강조조물의 특성상 좌굴에 취약하며, 장대화 됨에 따라 세장비가 증가하여, 좌굴 및 진동에 취약한 특성을 보이게 된다. 본 연구에서는 신형식 구조체인 이중관-콘크리트 합성 구조(DSCT; Double Skinned Composite Tubular)를 적용한 해상풍력 타워를 제시하고 요구 성능을 만족하는 최적 단면 설계를 제시하였다. 관은 섬유보강 합성수지 (FRP; Fiber Reinforce Polymer)와 강재를 적용한 경우를 고려하였으며, 모두 요구 성능을 만족하였다.

• 대한조선학회논문집
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• 제41권6호
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• pp.48-55
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• 2004

Loads on offshore structures are largely transferred to the bracing members in the form of axial forces. The detrimental effects of imperfections on compressive strength are well recognized. Damage in the members of offshore structures would significantly affect the compressive behavior of the members. As a result, such damages may also affect the ability of the structure to withstand the functional and environmental loads. It is important to be able to assess the residual strength of damaged members quickly and accurately. This will help operators to make the decision whether the member has to be repaired or not. In this study, a series of calculation is performed to study the effects of different parameters on the behavior of such damaged members under axial load. And the results of analysis are compared with those of experiment.

• 국제초고층학회논문집
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• 제3권3호
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• pp.215-221
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• 2014

Ultra-high strength concrete and high tensile steel are becoming very attractive materials for high-rise buildings because of the need to reduce member size and structural self-weight. However, limited test data and design guidelines are available to support the applications of high strength materials for building constructions. This paper presents significant findings from comprehensive experimental investigations on the behaviour of tubular columns in-filled with ultra-high strength concrete at ambient and elevated temperatures. A series of tests was conducted to investigate the basic mechanical properties of the high strength materials, and structural behaviour of stub columns under concentric compression, beams under moment and slender beam-columns under concentric and eccentric compression. High tensile steel with yield strength up to 780 MPa and ultra-high strength concrete with compressive cylinder strength up to 180 MPa were used to construct the test specimens. The test results were compared with the predictions using a modified Eurocode 4 approach. In addition, more than 2000 test data samples collected from literature on concrete filled steel tubes with normal and high strength materials were also analysed to formulate the design guide for implementation in practice.

• 대한기계학회논문집A
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• 제24권5호
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• pp.1331-1342
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• 2000

In power generation systems a variety of structural components typically operate at high temperature and pressure. Therefore a life assessment methodology accounting for gradual creep fracture is increasingly needed for these components. The most critical defects in such structure are generally found in the form of semi-elliptical surface cracks in the welded tubular joints. Therefore the analysis of a semi-elliptical surface crack in a plate or a shell is an important problem in engineering fracture mechanics. On this background, via shell/line-spring finite element analyses of such surface cracks in the welded T and L joints under various loadings, we investigate J-integral along the crack front We first develop T and L joints auto mesh generation program providing ABAQUS input file composed of shell/line-spring finite elements. We then further develop a T and L joints life assessment program based on the experimental creep crack growth law and auto mesh generation program in a graphical user interface format Finally the remaining life of T and L joints for various analytical parameters are assessed using the developed life assessment program.

• 수산해양기술연구
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• 제50권2호
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• pp.202-213
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• 2014

The sea cucumber, Apostichopus japonicus, is becoming an important aquaculture species in China, Japan and Korea. The purpose of this study is to evaluate the biological performance of a tubular type of subsurface cage for sea cucumber grow-out by in-situ tests. The cage structure was constructed of PP (polypropylene) frames and PP tubes (${\phi}130mm{\times}24pieces$). A set of tests were conducted at a depth of 15 m near Seosaeng, Ulsan, Korea for 295 days (23 July, 2012 to 13 May, 2013). A total of 155 sea cucumbers were used and fed a mixed diet containing mud, mineral, wheat, fish meal, etc (3% of their body weight). At the end of the experiments, sea cucumber showed a higher survival rate in feed shelter (77.14%) rather than no feed shelter (64.71%). The specific growth rate (SGR) of sea cucumbers in feed condition (0.04% $day^{-1}$) was higher than that of no feed culture animals (-0.49% $day^{-1}$) during total experimental periods. The result was able to find a no significance difference in survival rate but a significance difference in SGR under feed and no feed treatments.

• 한국전산구조공학회논문집
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• 제25권1호
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• pp.109-116
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• 2012

새로운 형태의 교량 거더인 CFTA(Concrete filled and tied tubular steel arch) 거더의 비선형 거동에 대해 고찰한 후, CFTA 거더의 대량 공장 생산시 콘크리트 충진 불량으로 발생할 수 있는 결함인 거더 안의 빈 공간을 탐지하는 새로운 방법을 제안하였다. CFTA 거더 안의 비대칭성 콘크리트 충진 불량 결함을 구조물의 대칭 거동을 이용하여 탐색하였으며, 수치해석과 실험을 통해 제안된 방법을 검증하였다. 제안된 방법을 수치적으로 검증하기 위해 3차원 유한요소모델을 사용하였으며, 실험적으로 검증하기 위해 CFTA거더의 정적 실험자료를 사용하였다.

• Environmental Analysis Health and Toxicology
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• 제13권3_4호
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• pp.87-94
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• 1998

The use of cisplatin is limited by severe side effects such as renal toxicity. Our platinum-base drug discovery is aimed at developing drugs capable of diminishing toxicity and improving antitumor activity. We synthesized new Pt (II) complex analogue [Pt (cis-DACH)(DPPP)]. 2NO$_3$ (PC) containing cis-1,2-diaminocyclohexane as a carrier ligand and 1,3-bis(diphenylphosphino) propane as a leaving group. Furthermore, nitrate was added to improved the solubility. In this study, its structure was determined and its antitumor activity against SKOV-3 and NIH-OVCAR-3 human ovarian adenocarcinoma, and in vitro cytotoxicity was determined against primary cultured rabbit kidney proximal tubular and renal cortical cells of human kidney using colorimetric MTT assay. PC demonstrated acceptable antitumor activity against SKOV-3 and NIH-OVCAR-3 human ovarian adenocarcinoma and significant activity as compared with that of cisplatin. The toxicity of PC was found quite less than that of cisplatin using MTT and $^3$H-thymidine uptake tests in rabbit proximal tubular cells and human kidney cortical cells. PC was used for human cortical tissue in 7 weeks hitoculture by the glucose-consumption tests. We determined that the new platinum drug has lower nephrotoxicity than cisplatin. Based on these results, this novel platinum (II) complex compound (PC) represent a valuable lead in the development of a new anticancer chemotherapeutic agent capable of improving antitumor activity and low nephrotoxicity.

• 약학회지
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• 제42권5호
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• pp.494-499
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• 1998

As part of a drug discovery program to discover more effective platinum-based anticancer drugs, a series of platinum complexes of 1,2-bis(diphenylphosphino)ethane(1,2-diaminopro pane)platinum(II)dinitrate (KHPC-070) has been evaluated in vitro against various tumor cell lines and normal kidney cells. The structure of this new compound was determined by elemental analysis, infrared spectroscopy (IR) and $^{13}carbon$ nuclear magnetic resonance (NMR). With the use of nine tumor cell lines, KHPC-070 exhibited a comparable cytotoxic to cisplatin. The cytotoxicity of KHPC-070 in normal cells was quite less than that of cisplatin using 3-(4.5-dimethylthiazol-2-yl)-2,5-diphenyl-tetrazolium bromide (MTT) and [$^3H$]-thymidine uptake tests in rabbit renal proximal tubular cells and human renal cortical cells. Based on these results, KHPC-070 is considered to have more selective cytotoxicity toward cancer cells than normal human/rabbit kidney cells.

• Steel and Composite Structures
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• 제20권3호
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• pp.487-500
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• 2016

In order to investigate the flexural bearing capacity of panel zone of diaphragm-through joint between concrete filled square steel tubular column and steel beam, four specimens were tested under static tension loads to study the mechanical properties and bearing capacity of diaphragm-through joints with a failure mode of panel zone. Finite element models of these specimens were developed to simulate the test and compare the predicted failure modes, load-displacement curves and bearing capacities with the experimentally observed. It was found that the tensile load from the steel beam flange is mainly shared by the square steel tube and the diaphragm. The diaphragm plastic zone appears along the cross-section lines enclosed by the square steel tube and the influence of steel beam web on the plastic zone of the steel tube is significant and cannot be neglected. Computational models of yield lines on square steel tube and diaphragm are established based on the distribution pattern of the plastic zone, and an analytical method for the evaluation of the bearing capacity of the joint is proposed. The theoretical results and the experimental data are compared and found in good agreement.