• Journal of Korean Society of Coastal and Ocean Engineers
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• v.29 no.6
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• pp.305-314
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• 2017

Ocean wave energy harvesting is still too expensive despite developing a variety of wave energy converter (WEC) devices. For the cost-effective wave energy harvesting, it can be an effective measure to use existing breakwaters or newly installed breakwaters for both wave control and energy harvesting purposes. In this study, we investigated the functionality of both breakwater and wave-power generator for the oscillating water column (OWC)-type wave energy converter (WEC) installed in a pneumatic floating breakwater, which was originally developed as a floating breakwater. In order to verify the performance of the breakwater as a WEC, the air flow velocity from air-chamber to WEC has to be evaluated properly. Therefore, air flow velocity, wave transformation and motion of floating structure was numerically implemented based on BEM from linear velocity potential theory without considering the compressibility of air within the chamber. Air pressure, meanwhile, was assumed to be fluctuated by the motions of structure and the water level change within air-chamber. The validity of the obtained values can be determined by comparing the previous results from the numerical analysis for different shapes. Based on numerical model results, wave transformation characteristics around OWC system mounted on the fixed and floating breakwaters, and motions of the structure with air flow velocities are investigated. In summary, all numerical results are almost identical to the previous research considering air compressibility. Therefore, it can be concluded that this analysis not considering air compressibility in the air chamber is more efficient and practical method.

• Journal of the Korean Society for Marine Environment & Energy
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• v.16 no.4
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• pp.239-247
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• 2013

Recently renewable energy such as offshore wind energy takes a higher interest due to the depletion of fossil fuel and the environmental pollution. This paper deals with multi-body dynamics (MBD) analysis technique for offshore wind turbine system considering aerodynamic loads and Thevenin equation used for determination of electric generator torque. Dynamic responses of 5MW offshore wind turbine system are evaluated via the MBD analysis, and the system is the horizontal axis wind turbine (HAWT) which generates electricity from the three blades horizontally installed at upwind direction. The aerodynamic loads acting on the blades are computed by AeroDyn code, which is capable of accommodating a generalized dynamic wake using blade element momentum (BEM) theory. In order that the characteristics of dynamic loads and torques on the main joint parts of offshore wind turbine system are simulated similarly such an actual system, flexible body modeling including the actual structural properties are applied for both blade and tower in the multi-body dynamics model.

• Korean Journal of Human Ecology
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• v.6 no.2
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• pp.133-144
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• 1997

Clothing is considered as a means of self-projection in the childhood and children show clear preference on their own favorite clothing on which their latent identity is reflected. Changing sex-role identity, in particular, in the modern complex society specially affects the clothing behavior of children. The purpose of this study is to investigate the clothing behavior of children in conjunction with sen-role identity and home environment variables. This study will provide fundamental information on the clothing behavior in the childhood and be of help in selecting appropriate clothing in accordance with the variation of sex-role identity. Necessary information for this study was obtained through a questionaire. 'Bem sex-role identity inventory' was used to investigate the effect of sex-role identity and the clothing behavior was studied in conjunction with the factors of conformity, dependence, aesthetics and interest. The subjects of investigation are composed of three hundred male and female elementary school students in the 5th and 6th grades. For the statistical analysis of the collected data, percentage(%), mean value(M), standard deviation(SD) and Pearson's correlation coefficient were calculated and t-test, $x^2$-test, and Duncan's multiple range test were performed. The results form this study are as follows : 1. Sex-role identity shows a little difference according to gender, order of a birth and standard of living. This small difference is shown to be statistically insignificant. 2. In clothing behavior in connection with the sex-role identity, statistically significant trend was not found in typical sex-role identity group. However, clothing behavior in modernistic sex-role identity group exhibits statistically significant results in the factors of dependence, aesthetics and interest at the level of P<.001. 3. As concerns the clothing behavior in connection with gender, boy students show statistically more significant tendency in aesthetics and interest than girls do. However, boy students show statistically more significant tendency in aesthetics than girls do in connection with the standard of living. Although the clothing behavior associated with the level of parents education, mother's age and existence of mother's job shows a little difference in mean values, statistically significant trend was not detected. 4. Clothing behavior of the children shows a meaningful correlation between the factors. 5. Through 3-dimensional variables analysis, it is found that there is no mutual interaction between gender, sex-role identity and standard of living on the clothing behavior. The results from MCA supplementary analysis reveal that there is difference according to the gender, sex-role identity and standard of living.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.26 no.4
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• pp.225-243
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• 2014

As the economic matters are involved, applying the WEC, which is used for controlling waves as well as utilizing the wave energy on existing breakwater, is preferred rather than installing exclusive WEC. This study examines the OWC mounted on a pressurized air chamber floating breakwater regarding the functionality of both breakwater and wave-power generation. In order to verify the performance as a WEC, the velocity of air flow from pressurized air chamber to WEC has to be evaluated properly. Therefore, numerical simulation was implemented based on BEM from linear velocity potential theory as well as Boyle's law with the state equation to analyze pressurized air flow. The validity of the obtained values can be determined by comparing the previous results from numerical analysis and empirically obtained values of different shapes. In the actual numerical analysis, properties of wave deformation around OWC system mounted on fixed type and floating type breakwaters, motions of the structure with air flow velocities are investigated. Since, the wind power generating system can be hybridized on the structure, it is expected to be applied on complex power generation system which generates both wind and wave power energy.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.46 no.5
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• pp.368-375
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• 2018

In the present study, aerodynamic load analysis for a floating off-shore wind turbine was conducted to examine the effect of periodic platform motion in the direction of 6-DOF on rotor aerodynamic performance. Blade-element momentum method(BEM) was used for a numerical simulation, the unsteady airload effects due to the flow separation and the shed wake were considered by adopting a dynamic stall model based on the indicial response method. Rotor induced downwash was estimated using the momentum theory, coupled with empirical corrections for the turbulent wake states. The periodic platform motions including the translational motion in the heave, sway and surge directions and the rotational motion in the roll, pitch and yaw directions were considered, and each platform motion was applied as a sinusoidal function. For the numerical simulation, NREL 5MW reference wind turbine was used as the target wind turbine. The results showed that among the translation modes, the surge motion has the largest influence on changing the rotor airloads, while the effect of pitch motion is predominant for the rotations.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.22 no.1
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• pp.117-124
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• 2009

The p-convergent boundary element method has been proposed to analyze two-dimensional potential problem on the basis of high order Legendre shape functions that have different property comparing with the shape functions in conventional boundary element method. The location of nodes corresponding to high order shape function are not defined along the boundary, called by nodeless node, similar to the p-convergent finite element method. As the order of shape function increases, the collocation point method is used to solve linear simultaneous equations. The collocation patterns of p-convergent boundary element method consist of non-symmetric hierarchial or symmetric non-hierarchical. As the order of shape function increases, the number of collocation point increases. The singular integral that appears in p-convergent boundary element has been calculated by special numeric quadrature technique and semi-analytical integration technique. The L-shape domain problem including singularity in the vicinity of reentrant comer is analyzed and the numerical results show that the relative error is smaller than $10^{-2}%$ range as compared with other results in literatures. In case of same condition, the symmetric p-collocation point pattern shows high accuracy of solution.

• Journal of the Korean Society of Marine Environment & Safety
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• v.22 no.1
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• pp.82-89
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• 2016

In this study, we proposed a pier of pontoon-type, "Very Large Floating Structure" (VLFS), with the length of 500m, breadth of 200 m and height of 2 m in Yeosu domestic port. Since this structure ought to endure wave loads for long periods at sea, it is essential to analyze the wave response characteristics. Direct-method is used to analyze the fluid-structure problem and the coupled motion of equation is used to obtain response results. The structural part is calculated by using finite element method (FEM) and the fluid part is analyzed by using boundary element method (BEM). Dynamic responses caused by the elastic deformation and rigid motion of structure are analyzed by numerical calculation. To investigate response characteristics of the pier in regular waves, several factors such as the wavelength, water depth, wave direction and flexural rigidity of structure are considered. As a result, wave response of pier changed at the point of $L/{\lambda}$ 1.5 and represented the torsional phenomenon according to the various incident waves. And the responses showed increasing tendency as the water depths increase at the incident point in case of $L/{\lambda}=8.0$ and peak point of vertical displacement amplitude moved from side to side as the flexural rigidity of structure changes.

• Journal of the Korean Home Economics Association
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• v.30 no.2
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• pp.1-20
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• 1992

The purpose of this study was to investigate(Ⅰ) the effect of a masculine-feminine image in women's suit on the perception of the wearer's occupational characteristics and suitability of the clothing for certain occupations, and (2) the effect of perceiver's sex, sex-role attitudes, and occupation on the perception formed by the function of clothing cues. The research design of the study consisted of 2(pink and navy blue colors) × 4(masculine and feminine forms) factorial design of a suit. The experimental materials developed for this study were a set of stiuli and 2 response scales. The stimuli consisted of 8 drawings of woman's clothing made by systematic manipulations of 2 independent variables(color and form) in drawings of suit. The dependent variables were the perceptions of the wearer's occupational characteristics and suitability of the masculine or feminine clothing for certain occupations. Occupational characteristics were measured with a 7-point semantic differential scale composed of 21 bipolar adjectives. Perception of ccupational suitability was assessed with 12 items of 5-point Likert type questions. In addition, the Bem Sex-role Inventory was used to assess perceiver's sex-role attitudes. The subjects consisted of 393 men and 389 women, whose occupations were classified as professionals, secondary school teachers, and white-collar workers. They were randomly assigned to one of 8 suit. The data were analyzed by factor analysis, MANOVA, ANOVA, Mean and S.D. Three factors emerged to account for the perception of occupational characteristics. These factors were given the titles of (1) activity, (2) potency, and (3) evaluation factors. The activity factor was the largest, including 9 adjectives. Differences in the form of the suit had effects on potency and evaluation for both sexes, while it also had some effect on activity for women. The color of the suit had some effect on evaluation for both sexes. Strong effects of color and form on the suit were seen in perception of occupational suitability for the occupations of attorney(masculine) and secretary(feminine). On suitability for secondary school teaching occupation, the effects of color and form of suit differed by sex of the subjects. Perceiver's sex-role attitudes and occupation paritally influenced the perception of the wearer's occupational characteristics and suitability of the clothing for certain occupations. In summary, a masculine-feminine image of clothing had a significant effect on the perception of occupational characteristics as well as on suitability of the clothing for certain occupations. Thus, the results of the study support the implicit personality theory on person perception and also the stereotypes of sex-roles on the perception of occupational suitability.

• Journal of the Korean Home Economics Association
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• v.30 no.2
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• pp.21-34
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• 1992

The purpose of this study was to investigate (1) the effect of a masculine-feminine image in women's blouse·skirt on the perception of the wearer's occupational characteristics and suitability of the clothing for certain occupations, and (2) the effect of perceiver's sex, sex-role attitudes, and occupation on the perception formed by the function of clothing cues. The research design of the study consisted of 2(skirt color) × 2(blose color) × 3(masculine-feminine blouse forms) factorial desing of a blouse·skirt set. The experimental materials developed for this study were a set of stimuli and 2 response scales. The stimuli consisted of 12 drawings of woman's clothing made by systematic manipulations of 2 independent variabels (color and form) in drawings of blouse-skirt. The dependent variables were the perceptions of the wearer's occupational characteristics and suitability of the masculine or feminine clothing for certain occupations. Occupational characteristics were measured with a 7-point semantic differential scale composed of 21 bipolar adjectives. Perception of occupational suitability was assessed with 12 items of 5-point Likert type questions. In addition, the Bem Sex-role Inventory was used to assess perceiver's sex-role attitudes. The subjects consisted of 393 men and 389 women, whose occupations were classified as professionals, secondary school teachers, and white-collar workers. The data were analyzed by factor analysis, MANOVA, ANOVA, Mean and S.D. Three factors emerged to account for the perception of occupational characteristics. These factors were given the titles of (1) activity, (2) potency, and (3) evaluation factors. The activity factor was the largest, including 9 adjectives and accounting for 33.3% of the variance in blouse-skirt. On the blouse-skirt set, the form of the blouse had an effect on activity and evaluation for both sexes, while the color of the skirt had an effect on evaluation for both sexes as well as on potency for men. Strong effect of color and form on blouse·skirt were seen in perception of occupational suitability for the occupations of attorney(masculine) and secretary(feminine). On suitability for secondary school teaching occupations, the effects of color and form of blouse·skirt differed by sex of the subjects. Male subjects determined suitability by the color of the blouse, while female subjects determinied suitability on the basis of the form of the blouse. Perceiver's sex-role attitude and occupation partially influenced the perception of the wearer's occupational characteristics and suitability of the clothing for certain occupations.

• Journal of the Korean Society of Costume
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• v.31
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• pp.165-188
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• 1997

This study aims at 1) examining the perceived importance of clothing norms 2) examining relationship between perceptions of clothing norms clothing behavior and psycho-logical variables-ego identity(uniqueness and self acceptance) and sex role identity and 3) ascertaining any significant differences in the level of the perceived importance of clothing norms among variables-sex role identity and the uniqueness in psychological variables-and which variables are influencingon perception of clothing norms. The perception of cloth in norms inventory clothing norms inventory clothin behavior inventory ego identity in-ventory and the Bem Sex Role Inventory were administered to 620 college students. Sex role identity was classified into androgynous mas-culine feminine and undifferentiated type. Subjects were asked to rate each statement on the clothing norms under two kinds of instructions: their attitudes(TATT) and their beliefs about the expectations of others toward clothing norms(TBEO). 1) The scores of 3 TBEO of the students were higher than the scores of TATT. But the scores of TBEO concerning modesty of students were lower than the scores of TATT. Discrepancy scores of TATT and TBEO of the students were revealed significances differently according to clothing norms. males lower and higher class students had more free attitudes to the norms concerning genaral clothing attitudes. Females and higher class students had less free attitudes to the clothing norms concerning modesty. Females and lower and higher class students had more free attitudes to the norms concening sex-role related clothing attitudes but male students had less free to the sex-role related clothing norms. 2) Significant negative correlations between each variable of clothing norms and conform-ity-individuality were found. But negative correlations between those variables of the males and lower class students were higher than the correlations of the female and higher class students and the former had more posi-tive relationships with clothing norms and con-formity as compared with the latter. And sig-nificant positive correlations between each variable of clothing norms and modesty were found. But positive correlations between those variables of the males females and higher class students were higher than the correlations of the lower class students and the latter had less positive relationship with clothing norms and modesty as compared with the former. 3) Significant negative correlations between clothing norms and uniqueness were found in the subjects groups. The females and lower class students had more negative relationships with clothing norms and uniqueness as compared with the male and higher class students. Significant positive correlations be-tween uniqueness and conformity-individuality were found in all subjects groups, Therefore the higher uniqueness the student have the less they perceive theimportance of clothing norms and the more they have individuality. Significant positive correlations between sex-role related(higher class) general(female) clothing norms and self acceptance were found. but significant negative correlations be-tween campus style(higher class) general(female) clothing norms and self acceptance were found. But significant negative correlations be-tween campus style(males lower class, higher class) clothing norms and self acceptance were found. Clothing norms therfore related posi-tively or negatively with self acceptance ac-cording to the subjects groups. And significant negative correlations between conformity in-dividuality and self acceptance was found in higher class students. 4) The female masculine groups and the masculine groups of lower class revealed high scores than the scores of andrgynous group and undifferentiated group in clothing norms concerning modesty. And the feminine group revealed high scores in conformity-individu-ality than the scores of the masculine group. Male masculine and feminine group revealed high scores in clothing norms concerning cam-pus style than the scores of the androgynous group. The masculine group and feminine group of the lower classes revealed high scores in general clothing norms than the scores of the androgynous group. 5) The most influencing variables on the clothing norms were sex conformity-individu-altiy and masculine-feminine variables in the right order. The general clothing norms and clothing norms concerning modesty were influened by the sex role identity but the sex role related clothing norms and clothing norms concerning campus style were influenced by the ego identity. 6) Based on the sum scores of the uniqueness each group of the subjects was separately segmened into "high medium and low" groups. By the analysis of variances sig-nificant differences in discrepancy scores of TBEO and TATT among 3 uniqueness level groups were found on all clothing norms variables in all students three clothing norms variables in male and female students and one clothing norms variable in lower and higher students and in each clothing norms variable the mean discrepancy scores of the high uniqueness group were higher than those of the other groups. The findings indicated that the differences in the discrepancy score mainly contributed to the results of correla-tions described above.bed above.