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근해역 양광시험을 위한 HDPE Pipe의 구조특성 연구
이재환(Jae-Hwan Lee),윤치호(Chi-Ho Yoon) 한국해양공학회 2011 韓國海洋工學會誌 Vol.25 No.6
The mining of imitated manganese noodles in 1000 m of seawater is planned for 2012. Thus, it is necessary to prepare the lifting pipes to be used for the test. Because of storage and expense constraints, flexible and economic HOPE pipe is being considered, making it necessary to test the structural safety. Material, pressure-chamber tests and finite element analysis of HOPE pipe for the 1000-m depth were performed. The tangential stiffness of HOPE was obtained through tension and three-point bending material tests and used for a structural analysis. FEA results show that the current sample pipe segment is safe for 1000 m of water pressure, and the stress result is also within the safe value. From the current results, the HOPE pipe seems to be acceptable only for the currently suggested constraints. However, more numerical and pressure tests need to be considered by applying additional physical conditions such as gravitational and hydrodynamic loads, external and internal fluid pressure, axial force induced ship motion, and heavy pump pressure to determine future usage.
임펄스 가진에 의한 근해역 통합채광시험 양광시스템의 파이프 동적 과도응답 해석
조규남,김민,박용찬,윤치호,Cho, Kyu-Nam,Kim, Min,Park, Yong-Chan,Yoon, Chi-Ho 한국전산구조공학회 2007 한국전산구조공학회논문집 Vol.20 No.2
본 논문에서는 극한 해상상태나 돌발적인 환경하중에서 양광시스템의 진수와 인양이 이루어질 때 발생할 수 있는 파이프의 점핑현상과 이에 의해 유발되는 파이프의 장력변화 및 위해도를 위한 해석기법을 제시하였다. 동적 과도응답 해석은 본 논문에서 제시된 기법에 의하여 여러 가지 형식의 임펄스에 대해 수행되어졌으며, 해석을 위한 모델로 KT-Submarine에서 사용하고 있는 '세계로호' 양광시스템의 진수, 인양 시스템을 선정하였다. 결과적으로 양광시스템관련 해상작업을 위한 지침이 제시되었다. 정성적인 해석기법의 검증과 비교를 위하여 ROV진수 시 발생 가능한 케이블장력 과도응답을 해석하였으며 이를 통하여, 본 연구에서 시도한 수학적 모델링과 이상화된 임펄스에 대한 파이프의 과도 응답과정이 충분한 정성적인 기초자료를 제공해 줄 수 있다는 점을 파악하였다. A finite element analysis scheme is proposed to assess the dynamic response due to impulse excitation of ocean mining pipe system. Transient dynamic response analysis based on the proposed scheme was carried out for various types of impulses, and the magnitude of cable tension induced by impulse was discussed by using a model of 'Segero', a special purpose ship of KT-Submarine as well as ROV carrier 'Onnuri' A qualitative, prospective guideline for the relevant marine operation is obtained.
화학환원법을 이용한 은 코팅 구리 분말 제조 시 환원제의 영향 및 전기비저항 특성
안종관 ( Jong Gwan Ahn ),윤치호 ( Chi Ho Yoon ),김동진 ( Dong Jin Kim ),조성욱 ( Sung Wook Cho ),박제신 ( Je Shin Park ) 대한금속·재료학회 2010 대한금속·재료학회지 Vol.48 No.12
Silver coated copper powders were prepared by a chemical reduction method with controlling the deposition process variables such as the feeding rate of the silver ionic solution and concentration of the reductants at room temperature. The characteristics of the products were evaluated by scanning electron microscope (SEM), X-ray diffractometer (XRD), atomic absorption spectrophotometer (AA) and a 4 probe resistivity measurement system. The optimum condition of the preparation of Ag coated Cu powders was at 0.05 M of potassium sodium tartrate and 2 ml/min of the feeding rate of the silver ionic solution. Our method successfully produced dense, uniform, and well-dispersed Ag coated Cu powder of 2~2.5 μm witha silver layer of 100~200 nm. Additionally, we found that thespecific resistivity of the 30 wt.% Ag coated Cu powder was similar to that of pure silver, so that the composite powder could be used as an alternative electromagnetic shielding material for silver.
일반품질연구 : 말콤 볼드리지 모형을 이용한 2차 의료기관의 전사적 품질관리와 성과 간의 인과관계 연구
권준덕 ( June Duk Kwon ),윤치호 ( Chi Ho Yoon ),오현종 ( Hyun Jong Oh ),박범규 ( Beom Gyu Park ),김양균 ( Yang Kyun Kim ) 한국품질경영학회 2015 품질경영학회지 Vol.43 No.1
Purpose: The purpose of this study is to lay groundwork for future research on the outcomes of national quality awards for secondary-care healthcare organizations. Methods: For this study, a secondary-care hospital was selected through a convenience sampling method and all of its organizational members participated in complete enumeration survey using 109 survey questions derived from the MBNQA criteria for healthcare through structural equation modeling (SEM) Results: As a result, Leadership was shown to drive Foundation and Direction, which affect System that creates Results with 12 hypotheses supported out of 18 hypotheses established. Conclusion: The findings of this study will provide valuable implications to the top management of secondary- care hospitals for self-examining quality management and promoting sustainable competitiveness.
환형관내 고 액- 2상 유동의 압력손실 변화특성에 대한 연구
우남섭(Nam-Sub Woo),한상목(Sang-Mok Han),황영규(Young-Kyu Hwang),윤치호(Chi-Ho Yoon),김영주(Young-Ju Kim) 대한기계학회 2007 대한기계학회 춘추학술대회 Vol.2007 No.5
Field measurements have revealed that the pressure drop over a borehole during drilling of a slim oil well or a well with a long reach can depend significantly on the rotation speed of the drill pipe. An accurate prediction of the annular frictional pressure drop is therefore important for conditions where the annular clearance is small. An experimental study was carried out to study solid-liquid two phase flow in a slim hole annulus. Annular velocities of carrier fluids varied from 0.2 ㎧ to 1.5 ㎧. The carrier fluids which were utilized included tap water and CMC water solutions. Pressure drops and average flow rates were measured for the parameters such as inner-pipe rotary speed, carrier fluid velocity, hole inclination and particle injection rate. For both water and CMC solutions, the higher the concentration of the solid particles is, the larger the pressure gradients become.
김영주(Young-Ju Kim),한상목(Sang-Mok Han),황영규(Young-Kyu Hwang),윤치호(Chi-Ho Yoon) 대한기계학회 2008 대한기계학회 춘추학술대회 Vol.2008 No.11
The screw-feeders are used at gathering the minerals at the seafloor, transportation of the sewage, and at the beverage industry. This study was carried out to study solid-liquid mixture hydraulic transport of solid particles in a horizontal and inclined screw-feeders with rotating. This study is about the amount of the alteration amount of the material transportation for regular transportation. In this study a clear acrylic pipe was used in order to observe the movement of solid particles. Relates to the angle, rpm and ratio of pitch ; finding the optimum condition and knowing about designing the screw feeders shape. As a result, we found the suitable rpm and a suitable angle. According to the experiment, the best rpm and angle are 100-200rpm and 10°, respectively.
안쪽축이 회전하는 경사 환형관내 고-액 2상 유동에 관한 연구
한상목(Sang-Mok Han),우남섭(Nam-Sub Woo),황영규(Young-Kyu Hwang),서병택(Byung-Taek Seo),윤치호(Chi-Ho Yoon),김영주(Young-Ju Kim),이동길(Dong-Kil Lee) 대한기계학회 2006 대한기계학회 춘추학술대회 Vol.2006 No.11
An experimental study was carried out in order to study 2-phase hydraulic transport of solid particles by water in an inclined slim hole annulus with rotating inner cylinder. In this study a clear acrylic pipe was used in order to observe the movement of solid particles. Annular velocities varied from 0.3 ㎧ to 2.0 ㎧. The mud systems which were utilized included fresh water and CMC solutions. Main parameters considered in the study were inner-pipe rotary speed, fluid flow regime and particle injection rate. Pressure drops and average flow rates were measured in the Reynolds number range of 10² < Re < 10⁴. For both water and 0.2% CMC solutions, the higher the concentration of the solid particles is, the larger the pressure gradients become.