• 한국안전학회지
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• 제23권4호
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• pp.59-66
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• 2008

Recently, the deterioration of reinforced concrete structures, primarily due to corrosion of steel reinforcement, has become a major concern. Chloride-induced deterioration is the most important deterioration phenomenon in reinforced concrete structures in harsh environments. For the realistic prediction of chloride penetration into concrete, a mathematical model was developed in which the effects of diffusion, chloride binding and convection due to water movement can be taken into account. The aim of this research was to reach a better understanding on the physical mechanisms underlying the deterioration process of reinforced concrete associated with chloride-induced corrosion and to propose a reliable method for estimating these effects. Chloride concentrations coming from de-icing salts are significantly influenced by the exposure conditions such as salt usage, ambient temperature and repeated wet-dry cycles.

• Journal of Mechanical Science and Technology
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• 제18권7호
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• pp.1187-1195
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• 2004

The objective of this study is to investigate the effects of fuel temperature on the spray characteristics of a dual-orifice type swirl injector used in a gas turbine. The major parameters affecting spray characteristics are fuel temperature and injection pressure entering into the injector. In this study, the spray characteristics of a dual-orifice type swirl injector are investigated by varying fuel temperature from - 30$^{\circ}C$ to 120$^{\circ}C$ and injection pressure from 0.29 to 0.69 ㎫. Two kinds of fuel having different surface tension and viscosity are chosen as atomizing fluids. As a result, injection instability occurs in the low fuel temperature range due to icing phenomenon and fuel property change with a decrease of fuel temperature. As the injection pressure increases, the range of kinematic viscosity for stable atomization becomes wider. The properties controlling the SMD of spray is substantially different according to the fuel temperature range.

• 한국기계가공학회지
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• 제18권1호
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• pp.52-58
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• 2019

Due to icing and snow, power transmission lines have asymmetric cross sections, and their motion becomes unstable. At this time, the vibration caused by the wind is called galloping. If galloping is continuous, short circuits or ground faults may occur. It is possible to prevent galloping by installing spacers between transmission lines. In this study, the transmission line is modeled as a mass-spring-damper system by using RecurDyn. To analyze the dynamic behavior of the transmission line, the damping coefficient is derived from the free vibration test of the transmission line and Rayleigh damping theory. The drag and lift coefficient for modeling the wind load are calculated from the flow analysis by using ANSYS Fluent. Galloping simulations according to spacer stiffness and interval are carried out. It is found that when the stiffness is 100 N/m and the interval around the support is dense, the galloping phenomenon is reduced the most.

• 한국가스학회지
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• 제21권5호
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• pp.83-88
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• 2017

이 논문은 자동차의 전자제어 에어컨에서 발생하는 고장사례에 대한 논문이다. 첫 번째 사례에서, 원인은 에어컨 릴레이 내부에 서지 전압 역류 방지용으로 사용된 다이오드가 에어컨이 OFF 되었을 때 다이오드의 단락으로 인해, 서지 전압을 흡수하지 못해 퓨즈가 반복적으로 끊어진 것을 확인하였다. 두 번째 사례에서, 원인은 핀 써모센서 내부의 단선으로 인해 에어컨을 제어하지 못함으로써 이베퍼레이터의 동결현상이 발생한 것을 확인하였다. 세 번째 사례에서, 원인은 운전석 앞쪽의 크래쉬 패드 하단에 있는 와이어링의 에어컨 핀센서 핀과 연결되는 배선이 차체와의 간섭으로 인해, 피복이 벗져져 단락(short)현상에 의해 에어컨 스위치와 핀센서가 소손되어 에어컨이 작동하지 않는 것을 확인하였다. 따라서, 이러한 고장 현상을 철저하게 확인하고 개선하여 최적의 시스템을 유지할 수 있도록 하여야 한다.

• Wind and Structures
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• 제22권2호
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• pp.253-272
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• 2016

The paper concerns with the method and results of wind tunnel investigations of the Strouhal number (St) of a stationary iced cable model of cable-supported bridges with respect to different angles of wind attack. The investigations were conducted in the Climatic Wind Tunnel Laboratory of the Czech Academy of Sciences in $Tel{\check{c}}$. The methodology leading to the experimental icing of the inclined cable model was prepared in a climatic section of the laboratory. The shape of the ice on the cable was registered by a photogrammetry method. A section of an iced cable model with a smaller scale was reproduced with a 3D printing procedure for subsequent aerodynamic investigations. The St values were determined within the range of the Reynolds number (Re) between $2.4{\cdot}10^4$ and $16.5{\cdot}10^4$, based on the dominant vortex shedding frequencies measured in the wake of the model. The model was oriented at three principal angles of wind attack for each of selected Re values. The flow regimes were distinguished for each model configuration. In order to recognize the tunnel blockage effect the St of a circular smooth cylinder was also tested. Good agreement with the reported values in the subcritical Re range of a circular cylinder was obtained. The knowledge of the flow regimes of the airflow around an iced cable and the associated St values could constitute a basis to formulate a mathematical description of the vortex-induced force acting on the iced cable of a cable-supported bridge and could allow predicting the cable response due to the vortex excitation phenomenon.

• 수산해양교육연구
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• 제11권1호
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• pp.24-42
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• 1999

I have studied historical transition process of fisheries industries, fisheries Institute in abreast of developing fisheries industries of west coast of Korea since 1910 year with regard to the Gogunsan Is. The results were summarized as follows. In 1910 year, fishery industry has been carried out shifting fishing gear e.g set-net in shallow waters, small stow net, small seine net adapting to the tophorgrapical feature, shape of coast, oceanic condition, however, the fishing gear and fishing method were undeveloped, so that, Japanese fishermen had been exploited fisheries resources penetrating the fishing ground. Most important species were lot of captured croaker, cod, spanish mackeral, sea abream, herring in coastal sea. nowaday, squid, anchovy, shrimp, crab, pompret were much captured. The species were captured in 18 century were not captured. It is rarely than that period. Fishereis aquatic culture had been not farmed till 1960 year, but sea laver, shrimp, crab, had been breeded 1970 year also, the fresh water fish e.g. eel, cat-fish had been breeded activately. The fisheries processing industry were composed of salt. icing, dry, method. the salted fish industry had been prevailed at Gangyng, Kwangchon, Kunsan, Julpo comparatively. The fisheries institute had been established at Kunsan at first, but institute established in other region had been abolished in a short time. This phenomenon was related with development of fisheries resources. The western coast fisheries industries had been wasted of decreasing of fisheries resources, variation of environment. Accordingly, the study of preserving the marine resources. educated man power who engaged in fisheries field have to accomplish. Sea was dying with reason of loss of mud in west coast factory waste, waste of life the increase of accident of sea polluted, each illegal fishing industry physical and chemical reason etc. in this respect, Kusan maritime college, fisheries developing agency, institute have to take important role for developing fishing industry.