• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.18 no.1
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• pp.24-30
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• 2006

Three liquid cooling heat exchangers for cooling of telecommunication equipment were designed and their cooling performances were tested. The liquid cooling heat exchangers had twelve rectangular channels $(5\times3 mm)$ with different flow paths of 1, 4, and 12. Silicon rubber heaters were used to provide heat flux to the test section. Heat input was varied from 75 to 400 W, while flow rate and inlet temperature of working fluid were altered from 1.2 to 4.0 liter/fin and from 15 to 3$30^{\circ}C$, respectively. The 4-path heat exchanger showed lower and more uniform average inner temperatures between heaters and the surface of heat exchanger than those of the others. To obtain optimal distribution of working fluid to each channels of liquid cooling heat exchangers, 2-3-2 and 4-3 type tube distributors were designed, and their distribution performances of working fluid were numerically and experimentally investigated. The distributor of the 2-3-2 type showed superior distribution performance compared with those of the 4-3 type distributor.

• Wind and Structures
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• v.25 no.2
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• pp.101-129
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• 2017

Local transient extreme wind loads caused by group tower-related interference are among the major reasons that lead to wind-induced damage of super-large cooling towers. Four-tower arrangements are the most commonly seen patterns for super-large cooling towers. We considered five typical four-tower arrangements in engineering practice, namely, single row, rectangular, rhombic, L-shaped, and oblique L-shaped. Wind tunnel tests for rigid body were performed to determine the influence of different arrangements on static and dynamic wind loads and extreme interference effect. The most unfavorable working conditions (i.e., the largest overall wind loads) were determined based on the overall aerodynamic coefficient under different four-tower arrangements. Then we calculated the one-, two- and three-dimensional aerodynamic loads under different four-tower arrangements. Statistical analyses were performed on the wind pressure signals in the amplitude and time domains under the most unfavorable working conditions. On this basis, the non-Gaussian distribution characteristics of aerodynamic loads on the surface of the cooling towers under different four-tower arrangements were analyzed. We applied the Sadek-Simiu procedure to the calculation of two- and three-dimensional aerodynamic loads in the cooling towers under the four-tower arrangements, and the extreme wind load distribution patterns under the most unfavorable working conditions in each arrangement were compared. Finally, we proposed a uniform equation for fitting the extreme wind loads under the four-tower arrangements; the accuracy and reliability of the equation were verified. Our research findings will contribute to the optimization of the four-tower arrangements and the determination of extreme wind loads of super-large cooling towers.

• Journal of the Microelectronics and Packaging Society
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• v.23 no.3
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• pp.37-41
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• 2016

In this paper, we introduced a near infrared fluorescence imaging system that has long working distance and analyzed on the effects of measurement variables such as gain, exposure time, working distance, magnification. Fluorescence signal intensity is growing up according to exposure time and magnification increasing, and it is getting stronger according to increase of gain, but the background signal intensity is getting stronger together. It causes low SBR. Due to a laser irradiation method, laser intensity distribution of the introduced system is not uniform and it makes fluorescence signal weak. So, we proposed a solution.

• Structural Engineering and Mechanics
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• v.70 no.4
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• pp.479-497
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• 2019

In the current code design, the use of a uniform internal pressure coefficient of cooling towers as internal suction cannot reflect the 3D characteristics of flow field inside the tower body with different ventilation rate of shutters. Moreover, extreme weather such as heavy rain also has a direct impact on aerodynamic force on the internal surface and changes the turbulence effect of pulsating wind. In this study, the world's tallest cooling tower under construction, which stands 210m, is taken as the research object. The algorithm for two-way coupling between wind and rain is adopted. Simulation of wind field and raindrops is performed iteratively using continuous phase and discrete phase models, respectively, under the general principles of computational fluid dynamics (CFD). Firstly, the rule of influence of 9 combinations of wind speed and rainfall intensity on the volume of wind-driven rain, additional action force of raindrops and equivalent internal pressure coefficient of the tower body is analyzed. The combination of wind velocity and rainfall intensity that is most unfavorable to the cooling tower in terms of distribution of internal pressure coefficient is identified. On this basis, the wind/rain loads, distribution of aerodynamic force and working mechanism of internal pressures of the cooling tower under the most unfavorable working condition are compared between the four ventilation rates of shutters (0%, 15%, 30% and 100%). The results show that the amount of raindrops captured by the internal surface of the tower decreases as the wind velocity increases, and increases along with the rainfall intensity and ventilation rate of the shutters. The maximum value of rain-induced pressure coefficient is 0.013. The research findings lay the basis for determining the precise values of internal surface loads of cooling tower under extreme weather conditions.

• Journal of Yeungnam Medical Science
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• v.13 no.2
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• pp.324-346
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• 1996

A survey was conducted to study attitudes of physician, nurse and patient towards physician's and nurse's uniform, from March 1 to March 31, 1996. The study population was 130 physicians and 147 nurses engaged in Yeungnam University Medical Center and 211 inpatients of Yeungnam University Medical Center. A questionnaire method was used to collect data. The following are summaries of findings: In the respect of physician's uniform, both physicians and nurses preferred other type of gown to the traditional coat-typed one and especially, nurses preferred more than physicians. Patients showed no difference in the preference of the traditional one and other form of gown as a whole but those who had higher educational level preferred other form of gown(p<0.01). Regarding the color of physician's gown, 73.6% of physicians and nurses liked white color, and 86.3% of the patients also liked the white color. Male physicians preferred the white color more than female physicians and nurses(p<0.01). Patients showed no meaningful difference for the color. The opinion of insisting on wearing a necktie when physician see patients was given by male physicians, physicians of fifty or more, physicians working in the field of medicine and professors, which showed significantly higher percentage than other groups(p<0.01). In the group of patiens， the same opinion was given by female, the group of sixty or more, the group of elementary school graduates or less and people residing in other cities and counties more than male, the group of other ages, the group of having higher educational level and people of Taegu city(p<0.01). It tended to agree wearing casual wear of physician during the working time of weekend and holiday as a whole. Younger physicians showed significantly higher preference for it(p<0.05). Regarding the nurse's uniform, both physicians and nurses preferred trousers, and 96% of the nurses did. Especially, nurses who were forty years old or more and who served at outpatient department and administrative and aid parts expressed 100 percent partiality to trousers. For the patients, those who had lower educational level preferred skirt and those who had higher educational level preferred trousers. As to the color of nurse's gown, 46.7% of the physicians and nurses liked white color. The physicians preferred white and nurses preferred other color(p<0.01). Of the patients, 79.1% liked white color. Regarding the wearing cap, 95.9% of the nurses replied it didn't have to wear the cap. The nurses who were fifty or more and who served at outpatient department and special parts gave whole answers of not having to wear the cap. On the other hand, 77.7% of the patients answered nurse had to wear the cap. From the above findings, it would be advisable to give a change to the forms and colors of the gowns to match with the trend and sense of the time instead of insisting on the traditional typical ones.

• Proceedings of the KSR Conference
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• 2011.10a
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• pp.1298-1302
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• 2011

The present study deals with the results of a thermo-fluid analysis applied to the cooling plate of the water cooling system developed for IGBT stacks, which was designed to keep the power semi-conductors from over heating problems. The cooling plate is to absorb a maximum quantity of 10kW from 4 IGBTs which are to be placed on both sides of the cooling plate, 2 IGBTs of them on each surface. For the analysis, Adina of CFD Program was used and an analysis was conducted to obtain the knowledges on heat and mass flow at both the plate and fluid flow inside. For the simulation, the operational conditions of a temperature difference of $15^{\circ}C$ for the working fluid and a uniform heat flux of about 92000 $W/m^2$ on the surface in contact with an IGBTs.

• Transactions of Materials Processing
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• v.14 no.4 s.76
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• pp.375-383
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• 2005

The shear spinning process, where the plastic deformation zone is localized in a very small portion of the workpiece, shows a promise for increasingly broader application to the production of axially symmetric parts. In this paper, the three components of the working force are calculated by a newly proposed deformation model in which the spinning process is understood as shearing deformation after uniaxial yielding by bending, and shear stress, $\tau_{rz}$, becomes k, yield limit in pure shear, in the deformation zone. The tangential force are first calculated and the feed force and the normal force are obtained by the assumption of uniform distribution of roller pressure on the contact surface. The optimum contact area is obtained by minimizing the bending energy required to get the assumed deformation of the blank. The calculated forces are compared with experimental results. A comparison shows that theoretical prediction is reasonably in good agreement with experimental results

• Transactions of Materials Processing
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• v.7 no.5
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• pp.489-495
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• 1998

Spinning is a chipless forming method for producing axially symmetric parts by using axial-radial motions of a spinning roller. This process has still some advantages in such a view point that a variety of complex shapes which can not be formed in a press can be easily spun at a low cost although it is one of the oldest forming methods for spinning mainly cookware parts for a long time. This study is to investigate the optimum roller path in order to obtain the maximum spinnability in producing cylindrical cups of Aluminum(A1050-H16) sheet metal. Working conditions applicable to any size of blank were predetermined through preliminary spinning tests. 9 types of roller path were proposed and experiments were carried out. The modified involute curve was shown to give the maximum drawing ration and more uniform quality of spun cups as compared with other results of this study. in addition thickness distribution and dimensional accuracy of spun cups were examined and discussed.

• Journal of Advanced Marine Engineering and Technology
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• v.29 no.1
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• pp.25-33
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• 2005

When a circular tube with uniform heat generation within the wall was placed in a cross flow, heat flows by conduction in the circumferential direction due to the asymmetric nature of the fluid flow around the perimeter of the circular tube The circumferential heat flow affects the wall temperature distribution to such an extent that. in some cases, significantly different results may be obtained for geometrically similar surfaces. In the present investigation, the effect of circumferential wall heat conduction is investigated for forced convection around circular tube in cross flow of air and water Two-dimensional temperature distribution $T_w(r,{\theta})$ is calculated through the numerical analysis. The difference between one-dimensional and two-dimensional solutions is demonstrated on the graph of local heat transfer coefficients. It is observed that the effect of working fluid is very remarkable.

• Journal of Families and Better Life
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• v.18 no.2
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• pp.15-27
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• 2000

This study puts an emphasis on the importance clothing and its reuse, dealing with the unmarried women workers who will be main domestic consumers. Questionnaire survey method was used in this research. The sample was taken from 546 unmarried women workers. The major findings are summarized as follows, it was found that Factor I was the cause of unplanned clothing management, Factor II was the cause of clothing modification and body type changes and Factors III was the cause of fashionmongering. Second, it was shown that as for experiences in hoarded clothing recycling disposition behavior subjective social strate had the high level, the group of sale and technical jobs / self-employed jobs had the higher level than the group of specialized skil / management jobs, the group in office-going and leaving clothing had the higher level than the group of people in separate uniform as working dress and the group of those experienced in environmental education had the high level.