• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.16 no.6
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• pp.530-537
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• 2004

In recent years, carbon dioxide among natural refrigerants has gained consider-able attention as an alternative refrigerant due to its excellent thermophysical properties. However, few investigations have been performed to develop useful correlations of heat trans-fer coefficients and pressure drop during evaporation of carbon dioxide. This study is aiming at providing the characteristics of heat transfer and pressure drop during the evaporation process of carbon dioxide. Heat is provided by a direct heating method to the test section, which was made of a seamless stainless steel tube with an inner diameter of 7.53 mm, and a length of 5.0 m. Experiments were conducted at saturation temperatures of -4 to 2$0^{\circ}C$, heat fluxes of 12 to 20 ㎾/$m^2$ and mass fluxes of 200 to 530 kg/$m^2$s. A comparison of different heat transfer correlations applicable to evaporation of carbon dioxide has been made. Based on the experiments for evaporation heat transfer and pressure drop, new correlations were developed. The newly developed empirical correlations for the heat transfer and pressure drop show average absolute deviations of 15.3% and 16.2%, respectively.

• Research in Community and Public Health Nursing
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• v.15 no.3
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• pp.397-407
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• 2004

Purpose: In Korea, as the number of hypertensive worker grows, identifying the level of health promoting life style practice and related factors in hypertensive workers is becoming more and more important. Method: The subjects of this study were 195 hypertensive male workers in Korea. The data was collected during 3 months ranging from August 2003 to October 2003. The data was analyzed by descriptive statistics. t-test, ANOVA. Pearson's correlation coefficient and stepwise multiple regression by SAS 8.1 program. Results: It was found that there were significant differences between age, religion, medication, perceived health status, perceived benefits, internal health locus of control, powerful other health locus of control and health promoting life style practice. The most significant factor affecting the health promoting life style practice was internal health locus of control. The combination of internal health locus of control, specific self-efficacy, powerful other health locus of control, general self-efficacy accounted for 51.0% of the health promoting life style practice. Conclusion: The level of health promoting life style practice was very low, so it is urgent to manage and care for hypertensive male workers continuously and systemically with occupational health nurses. Based on the above results, cognitive perceptual characteristics should be considered when developing health education programs for hypertensive workers.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.15 no.11
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• pp.1019-1025
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• 2004

The X-band 10${\times}$10 waveguide slot array antenna for SAR is designed, fabricated and measured. The array antenna is designed using the equivalent circuit model based on the field distribution of the dominant mode, TE$\sub$10/, and EM simulation. The method to decide optimum angle of the centered inclined slot(coupling slot) and the optimum of offset of the longitudinal slot(radiating slot) is provided. The designed antenna structure is EM simulated and fabricated. The measured return loss bandwidth is 180 MHz at 9.15 GHz , the side lobe level is below -25 dB, HPBW is about 9$^{\circ}$, and the gain is 25.5 dB. These results are similar to the simulation data.

• Journal of the Korean Society of Clothing and Textiles
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• v.36 no.10
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• pp.1117-1124
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• 2012

This study was a preliminary study to investigate the influence of surface morphology and characteristics on the self-cleaning of substrates. PI film was treated by $O_2$ plasma to modify the surface; in addition, AFM and Fe-SEM were employed to examine the morphological changes induced on a PI film treated by $O_2$ plasma and surface energies calculated from measured contact angles between several solutions and PI film based on the geometric mean and a Lewis acid base method. The surface roughness of PI film treated by $O_2$ plasma increased with the duration of the $O_2$ plasma on PI film due to the increased surface etching. The contact angle of film treated by $O_2$ plasma decreased with the increased treatment time in water and surfactant solution; in addition, the surface energy increased with the increased treatment times largely attributed to the increased portion on the polar surface energy of PI film. The coefficient of the correlation between surface roughness and surface polarity such as contact angle and surface energy was below 0.35; however, it was over 0.99 for the contact angle and surface energy.

• Journal of the Korean Society for Industrial and Applied Mathematics
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• v.15 no.3
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• pp.223-231
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• 2011

During spray coating, especially in an air plasma spray (APS), pores, cracks, and splat boundaries are developed and those factors exert influence on thermomechanical properties such as elastic modulus, thermal conductivity, and coefficient of thermal expansion. Moreover, the thermo mechanical properties are crucial elements to determine the thermoelastic characteristics, for instance, temperature distribution, displacements, and stresses. Two types of thermal barrier coating (TBC) model, the dense and porous microstructures, are taken into account for the analysis of microstructural characterizations. $TriplexPro^{TM}$-200 system was applied to prepare TBC samples, and the METECO 204 C-NS powder is adopted for the relatively porous microstructure and METECO 204 NS powder for the dense microstructure in the top coat of TBCs. Governing partial differential equations were derived based on the thermoelastic theory and approximate estimates for the thermoelastic characteristics were obtained using a finite volume method for the governing equations.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.27 no.2
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• pp.227-235
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• 2003

The WSGG-based narrow band model was employed to solve the radiative transfer equations along isothermal and non-isothermal paths through $CO_2-H_2O-N_2$ gas mixtures at 1 atm. When the WSGGM is applied for arbitrary gas mixtures by considering the multiplication property of transmissivity in overlapping bands, the number of gray gases is significantly increased. To reduce the computation time, three different regrouping methods for the gray gases are tested in obtaining the mean absorption coefficient for each gray gas group. Among them, the regrouping method by minimizing the regrouping error shows the best results. For the isothermal media, 10 gray gases show fairly good agreement with the results by statistical narrow band(SNB) model which are regarded as reference solutions. For non-isothermal media, 20 gray gases show good agreement with reference solutions.

• International Journal of Aeronautical and Space Sciences
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• v.13 no.2
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• pp.221-228
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• 2012

An active compensation method for the deformation of composite structures using additional controllable metal parts is proposed, and its feasibility is experimentally investigated in a simulated space environment. Composite specimens are tested in a vacuum chamber, which is able to maintain pressure on the order of 10-3 torr and interior temperature in the range of ${\pm}30^{\circ}C$. The displacement-measuring interferometer system, which consists of a heterodyne HeNe laser and an interferometer, is used to measure the displacement of the whole structure. Meanwhile, the strain of the composite part and temperature of both parts are measured by fiber Bragg grating sensors and thermistors, respectively. The displacement of the composite structure is maintained within a tolerance of ${\pm}1{\mu}m$ by controlling the elongation of the metal part, which is bonded to the end of the composite part. Also, the possibility of fiber Bragg grating sensors as control input sensors is successfully demonstrated using a proper corrective factor based on the specimen temperature gradient data.

• Journal of Fashion Business
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• v.18 no.6
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• pp.208-221
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• 2014

The purpose of this study was to investigate the effects of the hair style, and perceiver's generation on the perception of a high schoolgirl's image. A quasi-experimental method by questionnaire was used. The subjects were 253 high schoolgirls and their mothers living in Jinju. The data were analyzed by using frequency, factor analysis, Cronbach's alpha-reliability coefficient, three-way ANOVA, and Duncan's multiple ranges test. The high schoolgirl's image was derived in five dimensions by factor analysis: schoolgirl look, prettiness, individuality, activeness, and cuteness. In the image based on the hair length, it was assessed that the short cut and the bobbed hair styles looked more like school girls. And the short cut and long hair styles were considered as showing individuality. On the other hand, the bobbed hair style was assessed as cuter than styles of other lengths. For the bangs, the short bangs were found to more school-girl look and cuter than the long bangs. The mother group, whose ages were older than that of the other group, evaluated that the stimulative pictures had more school-girl look, individuality, prettiness, activeness and cuteness, compared to how the school girl group evaluated. It was shown that the generation gap produced different opinions about the stimulative pictures. Therefore hair style, bangs style, and difference in generations were found to be the variables affecting perception of high school girl image.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2005.05a
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• pp.236-240
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• 2005

This paper deals with friction-induced vibration of disc brake system under constact friction coefficient. A linear, finite element model to represent the floating caliper disc brake system is proposed. The complex eigenvalues are used to investigate the dynamic stability and in order to verify simulations which are based on the FEM model, The comparison of experimental and analytical results shows a good agreement and the analysis indicates that mode coupling due to friction force and geometric instability is responsible fur disc brake squeal. And the Front brake system reduced the squeal noise using design of experiment method(DOE). This helped to validate the FEM model and establish confidence in the simulation results. Also they may be useful during real disk brake model.

• International Journal of Highway Engineering
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• v.2 no.3
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• pp.145-153
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• 2000

Pavement evaluation is a fundamental component for rational pavement management. Optimal rehabilitation method and the priority of rehabilitation should be based on the evaluation data. Some types of pavement condition index are needed for objective evaluation of Pavement condition and management of road network. In this study a expressway concrete pavement condition index model is developed through regression analysis that correlates panel rating with distress measurement from the test sections. The derived condition index can be used for network level PMS for the expressway concrete pavement. Correlation coefficient of the model was 0.68. The selected independent variables were International Roughness Index, crack and area of patching.