• International Journal of Korean Welding Society
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• 제3권2호
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• pp.15-23
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• 2003

A genetic algorithm was applied to an arc welding process to determine near optimal settings of welding process parameters which produce good weld quality. This method searches for optimal settings of welding parameters through systematic experiments without a model between input and output variables. It has an advantage of being able to find optimal conditions with a fewer number of experiments than conventional full factorial design. A genetic algorithm was applied to optimization of weld bead geometry. In the optimization problem, the input variables were wire feed rate, welding voltage, and welding speed, root opening and the output variables were bead height, bead width, penetration and back bead width. The number of level for each input variable is 8, 16, 8 and 3, respectively. Therefore, according to the conventional full factorial design, in order to find the optimal welding conditions, 3,072 experiments must be performed. The genetic algorithm, however, found the near optimal welding conditions from less than 48 experiments.

• Computers and Concrete
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• 제1권1호
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• pp.15-30
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• 2004

In this study, a design process for reinforced concrete structures using the nonlinear FEM analysis is developed. Instead of using the nonlinear analysis to evaluate the required performance after design process, the nonlinear analysis is applied before designing the reinforcement arrangement inside the RC structures. An automatic reinforcement generator for computer aided reinforcement agreement is developed for this purpose. Based on a nonlinear FEM program for analyzing the reinforced concrete structure, a smart fictitious material model of steel, is proposed which can self-adjust the reinforcement to the required amount at the cracking location according to the load increment. Using this tool, the reinforcement ratio required at design load level can be decided automatically. In this paper, an example of RC beam with opening is used to verify the proposed process. Finally, a trial design process for a real size underground RC LNG tank is introduced.

• 대순사상논총
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• 제47집
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• pp.1-37
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• 2023

본고에서는 한국근대의 신종교를 어떻게 이해할 것인가 하는 문제의식에서 출발한다. 신종교는 민족종교 혹은 민중종교의 성격을 지닌다. 그것은 조선사회가 근대의 역사적 전환기를 맞이하여 고취시킨 민족의식의 산물이다. 당시에 조선은 중국처럼 사회진화론의 발전사관속에 전통의 중건(重建)과 근대의 전환(轉換)과 같은 양단의 칼날에 직면해있었다. 전통의 중건은 반제국주의에 따른 민족의 계몽을 고양하는 역사적 사명감에 달려있다면 근대의 전환은 반봉건주의에 따른 민생의 계도와 민중의 교화를 도모하는 시대적 절박감에 달려있다. 본고에서는 이러한 역사적 전환기에 등장했던 신종교에 주목하고 특히 대순사상의 세계관을 집중적으로 조명한다. 그 중심적 논제 중의 하나로서 개벽의 선험주의적(先驗主義的) 문제를 집중적으로 논의한다. 대순사상의 진리는 민생을 계도하고 민중을 교화하는 현실적 인식의 종교적 차원을 지닌다. 개벽의 과정은 대순의 진리를 향해 천하대순(天下大巡)의 존재론적 시계를 확보하고 천지공사(天地公事)의 인식론적 세계를 설정하며 후천개벽(後天開闢)의 가치론적 경계에 도달하는 과정이다. 이들 삼중의 영역의 연결고리는 우주의 무궁무한적(無窮無限的) 시공간성을 천지의 틀 속에 후천의 시공간적 개벽으로 경험하는 선험주의적 노선을 특징으로 한다. 그 속에서 인간은 자신의 유한한 생명력에서 우주의 무한한 생명력을 만끽하고자 하였다. 따라서 대순사상은 후천의 개벽과 같은 선험주의적 통로를 통해 현실적 삶을 극복하고 선경과 같은 자각의식의 경계를 지향할 수 있는 것이다. 이는 초월적 관념의 세계를 추구하기보다는 현실적 세계에 참여하여 실천하려는 것이며, 따라서 소극적인 출세주의적(出世主義的) 경향보다는 적극적인 입세주의적(入世主義的) 경향을 지닌다. 결론적으로 말해, 후천의 개벽으로 특징짓는 대순사상의 진리에는 유토피아(Utopia)의 이상적 염원이나 디스토피아(Dystopia)의 현실적 혐오보다는 앞으로 희망과 기대를 갈구하는 넥스토피아(Nextopia)의 미래적 조망이 담겨있다.

• 소성∙가공
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• 제17권7호
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• pp.511-516
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• 2008

A drawbead die for the experimental determination of drawbead forces was newly introduced in this paper. While the conventional Nine's drawbead die inevitably includes effects of a blank holding force on the measured drawbead forces, the new drawbead die excludes it by removing the blank holder contact in the dieface. Therefore, the new drawbead die can provide more realistic drawbead forces without considering somewhat arbitrary effect of blank holder with the computational procedure of forming process. The drawbead opening force and restraining force obtained by adopting the two experimental dies were compared for the validation of accuracy in the FEM simulation of automotive fender forming process. The compared section strains and draw-ins confirmed that the present drawbead die provides better drawbead forces for an accurate FEM simulation of sheet metal forming process.

• 한국기계가공학회지
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• 제6권2호
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• pp.41-46
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• 2007

Butterfly valves are commonly used as control valves in applications where the pressure drops required of the valves relatively low. As the shutoff valve (on/off service) or throttling valves (for flow or pressure control), the higher order and the better precision of butterfly valves are required. The it's more and more essential to know the flow characteristic around the valve. Due to the fast progress of the flow visualization and numerical technique, it becomes possible to observe the flows around a valve and to estimate the performance of a valve. Researching these results did not gave only access to understand the process of the valve flows at different valve opening angles, but also was made to determine the accuracy of the employed method. Furthermore, the results of the three-dimensional analysis can be used in the design of butterfly valve in the industry.

• 한국기계가공학회지
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• 제2권1호
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• pp.22-31
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• 2003

The compressive residual stress, which is induced by shot peening process, seems to be an Important factor in increasing the fatigue strength. And then it was showed that residual stress was disappearenced at the high temperature. The fatigue charateristic investigation of a SUP9 spring steel processed shot peening is performed by considering the high temperature service conditions in the range of room temperature through $180^{\circ}C$ in the range of stress ratio of 0.3 by means of opening mode displacement. The fatigue resistance characteristics and fracture strength at high temperature is considerable lower than that of room temperature in the early stage and stable of fatigue crack growth region.

• Fibers and Polymers
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• 제6권1호
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• pp.42-48
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• 2005

The effects of opening, carding, and repeated drawings on single fiber and bundle cotton characteristics were stud­ied by employing $Mantis^{\circledR}$, $AFIS^{\circledR}$ and HVI Testers. Some of the significant changes in single fiber properties were found to be due to process parameters as well as the changes in the fiber crimps, parallelness of fibers within HVI beards, and the actual changes in the tensile properties of the fibers. The study showed that the HVI test data taken just prior to spinning had the highest correlation with the yam tensile properties. Based on the study results, we point out the potential of HVI for future quality and process control in spinning by recommending a set of expanded HVI output that is more scientific and compre­hensive for the future control needs.

• 한국해양공학회지
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• 제18권4호
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• pp.59-64
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• 2004

Functional requirements and design parameters were not clarified in the early design process. Design axiom shows some difficulty for larger system designs, such as the butterfly valve, which is basically carried out by an incremental and iterative process. A numerical analysis was carried out on fluid flows in a butterfly valve, by using ANSYS-FLOTRAN. Characteristics of the butterfly flows at different valve disk opening angles, with a uniform incoming velocity, were investigated. The entire analysis is decomposed to satisfy the independence axiom. This paper resolves the problems associated with the establishment of a systematic design process.

• 한국안전학회지
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• 제10권3호
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• pp.11-20
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• 1995

In recent years, the study on the high efficiency of the internal combustion engine has been mainly proceeding. In this study, we developed rotary valve to achieve the improvement of volumetric efficiency and to be simple construction. And then made a comparative analysis between rotary and poppet valve. In this experiment, rotary valve enlarged the flow area of valve port to minimize the resistance of the fluid flow and to flow smoothly in intake and exhaust process. Indeed, valve timing was controlled properly lest positive pressure in exhaust process should affect intake process. Motoring and firing experiments were using engine speed and air-fuel ratio as the principle parameter and the full opening of throttle valve and minimum spark advance for best torque (MBT) as engine operating variables.

• 한국군사과학기술학회지
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• 제19권2호
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• pp.145-154
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• 2016

In this paper, a pneumatic device for the deployment performance verification of canards deployed by inertia has been designed and the performance of the pneumatic device has been proven through analysis and tests. The pneumatic conveying process, orifice opening process and piston movement process of the pneumatic device were investigated by using numerical methods. The orifice diameter, pressure in a pressure tank and type of gas were regarded as the main design parameters of the pneumatic device. The error rate between analysis and test results under the same conditions was within 4 %. The accuracy of numerical methods used in this study were validated.