• 한국해양공학회지
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• 제32권1호
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• pp.21-27
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• 2018

The design and analysis of a quayside mooring system for safe mooring of Prelude FLNG under extreme environmental conditions were carried out. The design of the mooring system considered the yard operation conditions and maximum wind speed during a typhoon. In order to secure the mooring safety of Prelude FLNG under an extreme environment, a special steel structure was designed between the quay and Prelude FLNG to maintain the distance from the quay to a certain extent to avoid a collision with the inclined base. The mooring safety was also ensured by installing additional new parts on the quay. A mooring analysis and mooring safety review were performed with more rigorous modeling considering the nonlinearity of the mooring rope and fender. In order to secure additional safety of the mooring system under extreme environmental conditions, a safety assessment was conducted on the failures of the mooring components proposed in the marine mooring guidelines. Based on the results of the mooring analysis, it was confirmed that the Prelude FLNG can be safely moored even under the extreme conditions of typhoons, and a worst case scenario analysis verified that the mooring system design was robust enough. The proposed mooring analysis and design method will provide a basis for the safe mooring of ultra-large floating offshore structures of similar size in the future.

• 정보학연구
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• 제10권2호
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• pp.37-45
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• 2007

The multiple-ability which the structure and the physical properties which the carbon or scull tube are unique show the applicability is superior in the plane indication element which is an indispensability of information communications apparatus, the stubbornness memory element, 2nd change of air and the rough copy dosage [khay] plaque seater, the hydrogen store material and the chemical sensor back and it has the possibility which will pass over the limit which the element of existing has. from the present paper it compared in the steel and only 10 the boat it did and it analyzed against an energy storage space voluntary application and developmental apply the carbon or scull tube trend in order about under researching the effective energy storage element it could be appeared, the technique of the strong carbon nano tube. 1. The hazard which embodies the energy storage element which uses the carbon or scull tube it follows in the function which stands and CNT of the structure which is various is necessary. 2. CNT fabrications of each one must precede possible not only must be each Cabinet conference circumstances quality gain and loss. 3. The structural control of syntheses, length controls, diameter controls and the metal - CNT junction control backs of quality CNT must precede. Applies the hereafter carbon or the scull tube in the various element with the primary preceding base technique for the structural plan technique of the carbon or scull tube to be certainly established, it does, secondarily the various element functional control technique which uses the carbon or scull tube is researched and will do.

• Journal of Advanced Marine Engineering and Technology
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• 제39권5호
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• pp.536-541
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• 2015

Copper has been used extensively as an electric wire or as a base material in various types of machineries owing to its good electrical and thermal conductivity and good fabricating property, as well as its good corrosion resistance compared to iron. Furthermore, the copper-nickel alloy has significant corrosion resistance in severely corrosive environments. Although, cupro-nickel alloy shows better corrosion resistance than the brass and bronze series, this alloy also corroded in severely corrosive environments, including aggressive chloride ions, dissolved oxygen, and condition of fast flowing seawater. In this study, and annealing treatment at various annealing temperatures was carried out on the cupro-nickel (Cu-10%Ni) alloy, and the effects of annealing were investigated using electrochemical methods, such as measuring the polarization and impedance behaviors under flowing seawater conditions. The corrosion resistance increased by annealing compared to non heat treatment in the absence of flowing seawater. In particular, the sample annealed at $200^{\circ}C$ exhibited the best corrosion resistance. The impedance in the presence of flowing seawater showed higher values than in the absence of flowing seawater. Furthermore, the highest impedances was observed in the sample annealed at $800^{\circ}C$, irrespective of the present of flowing seawater. Consequently, the corrosion resistance of cupro-nickel (Cu-10%Ni) alloy in a severely corrosive environment can be improved somewhat by annealing.

• Steel and Composite Structures
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• 제21권4호
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• pp.863-882
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• 2016

This study aims to introduce a new bracing system by which even super-wide frames with large openings can be braced. The proposed system, hereafter called Cable-Pulley Brace (CPB), is a tension-only bracing system with a rectilinear configuration. In CPB, a wire rope passes through a rectilinear path around the opening(s) and connects the lower corner of the frame to its opposite upper one. CPB is a secondary load resisting system with a nonlinear-elastic hysteretic behavior due to its initial pre-tension load. As a result, the required energy dissipation would be provided by the MRF itself, and the main intention of using CPB is to contribute to the initial and post-yield stiffness of the whole system. Using a stiffness calibration technique, optimum placement of the CPBs is discussed to yield a uniform displacement demand along the height of the structure. A displacement-based design procedure is proposed by which the MRF with CPB can be designed to achieve a uniform distribution of inter-story drifts with predefined values. Obtained results indicated that CPB leads to significant reductions in maximum and residual deformations of the MRF at the expense of minor increase in the maximum base shear and developed axial force demands in the columns. In the case of a typical 5-story residential building, compared to SMRF system, CPB system reduces maximum amounts of inter-story and residual drifts by 35% and 70%, respectively. Moreover, openings of the frame are not interrupted by the CPB. This is the most appealing feature of the proposed bracing system from architectural point of view.

• International Journal of Concrete Structures and Materials
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• 제9권1호
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• pp.89-118
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• 2015

The geometric nonlinearity of off-diagonal bracing system (ODBS) could be a complementary system to covering and extending the nonlinearity of reinforced concrete material. Finite element modeling is performed for flexural frame, x-braced frame and the ODBS braced frame system at the initial phase. Then the different models are investigated along various analyses. According to the experimental results of flexural and x-braced frame, the verification is done. Analytical assessments are performed in according to three dimensional finite element modeling. Nonlinear static analysis is considered to obtain performance level and seismic behaviour, and then the response modification factors calculated from each model's pushover curve. In the next phase, the evaluation of cracks observed in the finite element models, especially for RC members of all three systems is performed. The finite element assessment is performed on engendered cracks in ODBS braced frame for various time steps. The nonlinear dynamic time history analysis accomplished in different stories models for three records of Elcentro, Naghan and Tabas earthquake accelerograms. Dynamic analysis is performed after scaling accelerogram on each type of flexural frame, x-braced frame and ODBS braced frame one by one. The base-point on RC frame is considered to investigate proportional displacement under each record. Hysteresis curves are assessed along continuing this study. The equivalent viscous damping for ODBS system is estimated in according to references. Results in each section show the ODBS system has an acceptable seismic behaviour and their conclusions have been converged when the ODBS system is utilized in reinforced concrete frame.

• Journal of Advanced Marine Engineering and Technology
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• 제24권6호
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• pp.70-77
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• 2000

In this paper, the effect of solution and age heat treatment to the corrosion behavior for the Ti-6Al-4V alloy were studied by cyclic polarization methods. Ti-6Al-4V was solution heat treated at $1,066^{\circ}C$ and $966^{\circ}C$ for 5 hours, and followed by age heat treated at $650^{\circ}C$, $600^{\circ}C$ and $550^{\circ}C$ with 1, 2, 4, 8 and 16 hours under vacuum environment. Test solution was 3.5% NaCl with temperature $25^{\circ}C$. The obtained results were as follows: 1. Base metal was exhibited higher electrical charge than that of solution and aged material. With decrease of solution-treatment temperature from 1066 to $966^{\circ}C$, the electrical charge was increased due to softening of micro structure. 2. The corrosion resistance of specimen that solution treated at $966^{\circ}C$ for 5 hours and age heat treated at 650, 660 and $550^{\circ}C$ were increased with increase of aging time to 4, 8 and 16 hours respectively, and then decreased. 3. In case of 316L stainless steel, measured charge and corrosion potential was 0.0627 coulomb and -614 mV respectively. Corrosion resistance of Ti-6Al-4V was higher than that of 316L.

• 자원ㆍ환경경제연구
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• 제21권1호
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• pp.129-156
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• 2012

본 연구는 다목적댐 운영을 통한 안정적인 수자원 공급이 국가경제에 기여하는 경제적 파급효과를 분석한다. 분석을 위해 17개 주요 다목적댐이 고려되며, 다목적댐에서 공급되는 수자원을 여름과 겨울로 구분하여 별도의 생산요소로 포함하는 연산가능 일반균형모형(computable general equilibrium model: CGE)을 2007년을 기준연도로 하여 구축한다. 분석 내용은 다목적댐 용수 공급의 양적 측면과 안정적 용수 공급 측면을 구분하여, 전자에 대해서는 수자원 수요 충족에 따른 경제적 파급효과를 분석하고, 후자에 대해서는 수자원 공급의 불확실성 감소에 따른 리스크 프리미엄을 추정한다. 분석 결과, 다목적댐이 운영되지 않을 경우에 수자원을 집약적으로 투입하는 농림수산 및 수도 산업의 생산과 농림수산 산출물이 중간재로 많이 사용되는 음식료 산업의 생산이 크게 감소하는 것으로 나타났으며, 철강과 전기전자 등의 산업들은 대체로 생산이 증가하는 것으로 나타났다. GNP는 벤치마크 해 대비 0.22~0.68% 감소하는 것으로 분석되었다. 한편 리스크 프리미엄은 상대적 위험회피 척도 값을 0.5~3.0의 범위에서 고려할 때 약 40억 원~240억 원의 범위를 갖는 것으로 나타났다.

• 감성과학
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• 제10권3호
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• pp.393-402
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• 2007

본 연구는 제품디자인에 관련한 소비자의 선호와 감성이미지를 파악하여 선호감성이미지를 확인하고 이를 충족시키는 제품디자인요소를 추론하여 소비자가 원하는 디자인을 제공할 수 있는 가장 근본적인 가정인 제품디자인선호-감성이미지-디자인요소의 인과구조를 통해 소비자 감성 지향적 디자인방향에 대한 지침을 제공하고자 한다. 이를 위해 남성용면도기를 연구대상물로 선정하였고, 감성이미지단어들을 추출하기 위한 파일로트 테스트(pilot test)와, 감성이미지단어항목과 선호도를 측정하기 위해 의미차이법을 이용하여 설문을 구성하여 조사, 분석하였다. 결과에 따르면 남성용면도기 디자인전략으로는 소비자들은 남성용면도기제품을 "고급스럽고, 예쁘며, 안정적인" 감성이미지가 높을수록 선호하는데 이 이미지를 충족시키기 위해서는 "바디가 호형도 다각형도 아니고 재질이 스틸이고, 버튼이 푸시형이며, 재질이 스틸, 컬러는 갈색이 아닌 컬러"인 디자인요소가 디자인요소들간에 trade-off관계를 고려하여 조합되어져야한다. 본 연구는 이론적으로는 선호도-감성이미지-디자인요소의 인과 구조에 대한 연구에 기초를 제공하고 실무적으로는 소비자 감성 지향적 디자인을 전망할 수 있는 디자인 프로세스를 제공한다.

• Journal of Welding and Joining
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• 제28권5호
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• pp.51-57
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• 2010

Brittle microstructure created in a heat affected zone (HAZ) during the welding of low alloy steel can be eliminated by post-weld heat treatment (PWHT). If the PWHT is not possible during a repair welding, the controlled bead depositions of multi-pass welding should be applied to obtain tempering effect on the HAZ without PWHT. In order to anticipate and control the tempering effect during the temper bead welding, the definition of temperature curve obtained from the analytical solution was suggested in this research. Because the analytical solution for heat flow is expressed as a mathematical equation of weld parameters, it may be effective in anticipating the effect of each weld parameter on the tempering in HAZ during the successive bead depositions. The reheating effect by the successive bead layer on the brittle coarse grained HAZ formed by earlier bead deposition was estimated by comparing the overlapped distance between the temperature curves in the HAZ. Three layered weld specimens of SA508 base metal with A52 filler were prepared by controlling heat input ratio between layers. The tempering effect anticipated by using the overlapped distance between the temperature curves was verified by measuring the micro-hardness distribution in the HAZ of prepared specimens. The temperature curve obtained from analytical solution was expected as a good tool to find optimal temper bead welding conditions.

• 대한기계학회논문집A
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• 제40권7호
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• pp.667-672
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• 2016

본 연구에서는 SS400에 대해 레이저-아크 하이브리드 용접을 이용하여 맞대기 용접을 실시하였다. 맞대기 용접시 입열에 직접적으로 영향을 미치는 레이저 출력, 용접 전류 및 속도를 변화시켜 실험을 실시하였다. 이를 통해, 결함 없이 원 패스 관통 용접이 이루어지고, 미려한 비드가 형성되는 최적의 맞대기 용접 조건을 도출하였다. 용접부의 기계적 및 조직적 특성을 파악하기 위해 레이저 및 아크 영역에 대해 경도측정 및 미세조직 관찰을 실시하였다. 또한 모재와 용접 시험편의 강도를 비교하기 위해 인장강도 실험을 실시하였으며, 결과적으로 두 시험편의 인장강도 값은 유사하게 나타나는 것을 확인할 수 있었다.