• Wind and Structures
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• 제27권2호
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• pp.137-147
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• 2018

Heavy damages to properties with attendant losses were frequently caused by tornadoes in recent years. This natural hazard is one of the most destructive wind events that must be fully studied and well understood in order to keep the safety of structures and infrastructure facilities. On June 23, 2016, a severe tornado, which is an Enhanced Fujita (EF) 4 storm, occurred in the rim of a coastal city named as Yancheng in China. Numerous low-rise buildings as well as facilities (e.g., transmission towers) were destroyed or damaged. In this paper, damages to structures and infrastructure facilities by the severe tornado are reviewed. The collapses of residential buildings, industrial structures and other infrastructure facilities are described. With an overview of the damages, various possible mechanisms of the collapse are then discussed and utilized to reveal the initiation of the damage to various facilities. It is hoped that this paper can provide a concise but comprehensive reference for the researchers and engineers to help understand the tornado effects on structures and expose the vulnerabilities that need to be improved in current wind-resistant design practices.

• 한국복합재료학회:학술대회논문집
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• 한국복합재료학회 2003년도 춘계학술발표대회 논문집
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• pp.113-116
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• 2003

The investigation of delamination growth behavior in hybrid composite material such as FRMLs should be considered delamination growth rate, dA_D/da$ using the delamination shape factor, $f_S$ instead of traditional fracture mechanics parameters. The main objective of this study is to evaluate the relationship between delamination element (i. e. delamination width, b, delamination contour, c, delamination shape factor, $f_S$ and delamination growth rate, dA_D/da$) and delamination growth in FRMLs under cyclic bending moment. The delamination shape formed along the fatigue crack between aluminum layer and glass fiber/epoxy layer are measured by scanning method. The details of study are as follow : ⅰ) Relationship between crack length, a and delamination width, b. ⅱ) Variation of delamination growth rate, dA_D/da$ was attendant on delamination shape factors, $f_{S1}$, $f_{S2}$, $f_{S3}$. The test result indicated the delamination growth behavior depends in delamination element such as delamination width, b, delamination shape factors, $f_{S1}$, $f_{S2}$, $f_{S3}$.

• 유통과학연구
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• 제18권10호
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• pp.39-52
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• 2020

Purpose: This study aims to find out the relationship between the impact of Korean crew on airline service quality in the global aviation market, which is the representative of the face-to-face sales and can help in the face-to-face market of aviation services. Research design, data: The survey was conducted for about a month from March 1 to April 6, 2020, and a total of 300 copies were used in the analysis of the results. To verify the hypothesis, data was analyzed using the statistical package program SPSS 18.0, and frequency analysis, exploratory factor analysis, correlation analysis, and multiple regression analysis were performed. Results: It is a study on the sales of face-to-face service of crews of global airlines. Non-verbal elements in airline service face-to-face sales have been shown to have a significant impact on service quality. Conclusions: In the face-to-face service sales of global airlines, communication has been shown to affect service quality. A face-to-face sale using mother tongue means important. The better the flight attendant's linguistic face-to-face selling ability, the more positive on the airline's quality of service. It suggests that the communication skills of managers in the aviation service market are important for repurchase.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2003년도 추계학술대회
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• pp.1876-1881
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• 2003

When a projectile travels at high speed underwater, supercavitating flow arises, in which a huge cavity is generated behind the projectile so that only the nose, i.e., the cavitator, of the projectile is wetted, while the rest of it should be surrounded by the cavity. In that case, the projectile can achieve very high speed due to the reduced drag. Furthermore if the nose of the body is shaped properly, the attendant pressure drag can be maintained at a very low value, so that the overall drag is also reduced dramatically. In this study, shape optimization technique is employed to determine the optimum cavitator shape for minimum drag, given certain operating conditions. Shape optimization technique is also used to solve the potential flow problem for any given cavitator, which is a free boundary value problem having the cavity shape as unknown a priori. Analytical sensitivities are derived for various shape parameters in order to implement a gradient-based optimization algorithm. Simultaneous optimization technique is proposed for efficient cavitator shape optimization, in which the cavity and cavitator shape are determined in a single optimization routine.

• 한국자동차공학회논문집
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• 제4권3호
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• pp.211-219
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• 1996

In a small high-speed D. I. diesel engine, the injected fuel spray into the atmosphere of the high temperature is burnt by go through the process of break up, atomization, evaporation and process of ignition. These process are important to decide the emission control and the rate of fuel consumption and out put of power. Especially, in the case of injected fuel spray impinging on the wall of piston cavity, the geometry of piston cavity gives great influence the ignitability of injected fuel and the flame structure. Ordinary, the combustion chamber of driving engine have unsteady turbulent flow be attendant on such as the change of temperature, velocity and pressure. So the analysis of spray behavior is difficult. In this study, the spray was impinged on the wall of 3 types of piston cavity such as Dish, Toroidal, Re-entrant type, in order to analyze the combustion process of impinging spray precisely and systematically. And hot wire probe was used for analyze non-steady flow characteristics of impinging spray, and to investigate the behavior of spray, the aspects of concentration c(t), standard deviation σ(t) and variation factor(vf) was measured with the lapse of time.

• 농촌계획
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• 제19권4호
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• pp.203-212
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• 2013

The aging of farm households has caused serious problems such as productivity slowdown and aggravated income polarization in South Korea. Urban-to-rural migration has been recently suggested as a measure to attenuate the aging of rural population and other related problems. The inflow of migrants for farming can have a substantial effect on agriculture and rural communities while the natural adjustment of rural population caused by birth and death is slow. This paper forecasts population distribution of different provinces using the Origin-Destination (OD) analysis, taking into account both the size and directions of migration. In the analysis, nodes where the migration takes place are divided by the industrial sectors (agriculture and non-agriculture), regions, and ages. The results of a ten-year forecast shows that the aging of total population in most provinces will be intensified, but the portion of people over sixty will decrease in the agricultural sector. This finding implies that migration into rural areas, when occurring by a large extent, can mitigate the aging process and attendant problems.

• 한국농공학회지
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• 제45권3호
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• pp.103-115
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• 2003

This study examines groundwater movement system analysis and movement forecast algorithm using finite element method. The target is Cheongha-myeon area, Bukgu, Pohang-city which has many difficulties in water supply during drought period. From the comparison of the differences between obtained values by WINFlOW model and observed values, it is thought that groundwater head distribution under steady flow is reflected well at the level of reliability Groundwater movement of study area shows stable pattern from western watershed to eastern coastal area while flow path is dense and steep in the center of the coastal area. The results of particle tracing for each well show a comparatively straight line from the western boundary side to the observation position at the upper area of the well, and are analyzed as it diffuses according to getting closer to the coast at the lower area of the well. The result of effect circle examination attendant on pumping amount in study area shows variation tendency that groundwater head decreases at the side and the lower area more than at the upper area of the well when groundwater flows from west to east(coast). As mentioned above, satisfactory results of groundwater movement analysis using WINFlOW model, two dimensional groundwater movement analysis model, are obtained through the great decrease of physical uncertainty of groundwater movement system.

• 한국분말재료학회지
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• 제5권1호
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• pp.15-21
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• 1998

The effect of $\alpha$/$\beta$ phase on the mechanical properties and contact damage of silicon nitrides $Si_3N_4$) was investigated. Silicon nitride materials were prepared from two starting powders, at selective increasing hot-pressing temperatures to coarsen the microstructures: (i) from relatively coarse $\alpha$-phase powder, essentially equiaxed $\alpha$-$Si_3N_4$ grains, with limited, slow transformation to $\beta$-$Si_3N_4$ grain; (ii) from relatively fine $\alpha$-phase powder, a more rapid transformation to $\beta$-$Si_3N_4$, with attendant grain elongation. The resulting micro-structure thereby provided a spectrum of $\alpha$/$\beta$ phase ratios, grain sizes, and grain shapes. Fracture strength, hardness, and toughness were measured, and contact damage and strength degradation after indentation were investigated by Hertzian indentation using spherical indenter. A brittle to ductile transition in $Si_3N_4$ depended on $\alpha$/$\beta$ phase ratio as well as grain size. Silicon nitride with elongated $\beta$ grains showed a superior, contact damage resistance.

• Perspectives in Nursing Science
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• 제6권1호
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• pp.77-83
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• 2009

The number of nurses per bed at acute-stage hospitals is quite low in Korea compared with other OECD countries. In order to prevent the degradation of the quality of inpatient nursing services due to insufficient nurse staffs, the national health insurance introduced the differentiated nursing care fee system. This did not work as a motive for inducing the employment of nursing staff due to insufficient cost compensation. Because of insufficient nursing staff, family members have to stay with the patient or patients have to hire a personal care attendant. This increases the burden and cost to families. For the activation of hospitals without guardians, there should be policies for raising additional nursing staff such as standardizing jobs among nursing staff, particularly between nurses and nursing assistants, setting adequate standards of staffing in nursing according to medical service, substantiating the cost of nursing under the differentiated nursing care fee system, improving the medical fee system of hospitals without guardians including health insurance payment, supplying nursing staff stably through improving their working conditions such as providing child rearing services and salary increase, clarifying the qualification of personal care attendants working at acute.stage hospitals, developing indexes for assessing the quality of nursing care services, and monitoring for the management of uniform quality.

• 한국직업건강간호학회지
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• 제16권2호
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• pp.222-231
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• 2007

Purpose: This study aims to suggest political alternatives for nursing care costs for PCAs to provide qualitative medical benefit for patients with occupational disease by investigating present situation and problems of the nursing care cost system of Korea's Industrial Accident Compensation Insurance. Methods: Data was collected from 6 workers' accident medical corporation and 275 nurses affiliated with Korea labor welfare corporation using self reported questionnaire. Result: Research results were as follows; Character of nursing care cost of the Korea's Industrial accident Compensation Insurance changed as if it aims to support for living expenses for the family; As possible problems which could be caused under current system, administrative problems, decrease of service quality were made as objects of criticism. Some patients did not make every effort in rehabilitation to be beneficiaries continuously. Some patients were supplied with whole one PCA or all-night PCA even though they did not need as much caring as such. Conclusion: The research suggested that PCAs payment system improvement is necessary, and the presented nurses' opinion for the improvement method could be applied for policy making.