• International Journal of Highway Engineering
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• v.4 no.4 s.14
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• pp.23-39
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• 2002

This study dealt with developing a new approach for finding properties which might represent rut resistance characteristics of asphalt mixture under static loading. Two aggregates, a normal asphalt (pen 60-80) and 5 polymer-modified asphalts were used in preparation of 12 dense-graded mixtures. Marshall mix design was used in determination of OAC and each mixture at the OAC was prepared for a newly-developed Kim test on Marshall specimen (S=10cm) and gyratory specimen (S=15cm), and for wheel tracking test. Kim test used Marshall loading frame and specimens were conditioned for 30min at $60^{\circ}C$ before loading through Kim tester an apparatus consisting of a loading column and a specimen and column holder Diameter (D) of column was 3cm and 4cm with each column having different radius (r) of round cut at the bottom. The static load was applied at 50mm/min in axial direction of the specimen, not in diametral direction. The maximum load ($P_{max}$) and vertical deformation (y) at $P_{max}$ point were obtained from the test. A strength value was calculated based on the $P_{max}$ r, D and y by using the equation $K_D = 4P_{max}/{\pi}(D-2(r-\sqrt{2ry-y^2}))^2$ and is defined as the deformation strength ($kgf/cm^2$). The values of $P_{max}$/y and $K_I=K_D/y$ were also calculated. In general the leading column diameter and radius of round cut were significant factors affecting $K_D$ and $P_{max}$ values while specimen diameter was not. The statistical analyses showed the $K_D$ had the best correlation with rut depth and dynamic stability. The next best correlation was found from $P_{max}$ which was followed by $P_{max}$/y and $K_I$ in order.

• Proceedings of the Korean Society of Tribologists and Lubrication Engineers Conference
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• 2001.06a
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• pp.162-177
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• 2001

The hydrolysis rates of seven kinds of polyol ester base oils 〔POEs〕 of different branch shape were investigated by using a simple apparatus under mild acidic condition. Seven polyol ester base oils were made of poly hydric alcohols of two-four valence, normal or branched fatty acids of different carbon number. p-Toluene sulfonic acid was used as acid catalyst to accelerate the rate of hydrolysis. Partial esters and fatty acid produced by sequential hydrolysis of POEs were identified and their concentrations were determined by calibrated-internal standard method using Gas Chromatography. The rate constants of each step in sequential hydrolysis were determined by the least square method from rate equation and the concentration of each component, were compared with one another. It was shown that the rate of hydrolysis of POEs was strongly affected by whether molecular structure of fatty acid was straight chain or branch chain and which position was branched. The hydrolysis stability for all the POEs can be reasonably explained by using a steric hindrance effect anticipated fi:om their molecular structures affecting as water molecule makes an attack on the carbonyl carbon of POEs.

• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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• v.10 no.3
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• pp.139-144
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• 2005

To investigate the long-term variation of water qualities, we have daily monitored physio-chemical characteristics of surface water in the Geum River estuary from June 1996 to April 2004. We found that the water qualities were determined by three dominant factors : 1. fluvial input from Geum River ($28.3\%$), 2. chemical processes such as nitrification and phosphate addition originated from sediment resuspension and domestic sew- age input ($18.6\%$), 3. biological processes such as nutrient consumption by primary producers ($13.5\%$). The factor 1 (fluvial input) effectively affected the water quality of the estuary particularly during the normal or low river discharge. The factor 2 (chemical processes) and the factor 3 (biological processes) showed distinct seasonal differences due to their relative strengths of biological activities. The factor 3 was a governing parameter during the period of spring algal bloom in 2004. For the spring period, an empirical equation derived from the multi-regression analyses showed that the in-situ chlorophyll-a distributions in the estuarine water were successfully simulated by the phosphate concentrations and N/P ratios. Therefore we suggest that phosphate functions as a limiting factor for the primary productivity in the Geum River estuary for the dry season, especially during spring.

• Journal of Nutrition and Health
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• v.23 no.3
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• pp.170-178
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• 1990

The aim of the study was to investigate prevalence of obesity among housewives residing in apartments in Taegu city and any relationship of obesity with various factors. Hundred three housewives aged 30-49 years living in apartments (over 30 pyung) were interviewed for socio-economic status, food habit, food intake by a convenient questionnaire, and daily activity by the 24-hour recall. Their weight, height and triceps skinfold thickness were measured. The results were summarized as follows: 1) The percentages of subjects and their spouses with college and higher education were as much as 53.6% and 83.5%, respectively. The commonest family size was four members with two children. 2) The percentages of subjects classified as underweight, normal, overweight, and obesity according to relative body weight(RBW) were 4.9, 44.7, 24.3 and 26.2, respectively. Twenty four percent belonged to obese group according to body mass index(BMI$\geq$25). 3) Food habit score was 12.4 points in average and judged 'good'. The average of daily energy intake was 2247㎉ which corresponded to 112% of RDA and intakes of nutrients except iron exceeded RDA. The means of food habit score and energy intake were not significantly different among 4 groups. 4) Multiple regression analysis was tested to explain a relationship between fatness and various factors. The equation, BMI=25.216+(0.836$\times$family size)-(0.309$\times$education, years)-(0.00503$\times$household work time, minutes), indicates that fatness of housewives was related with family size(+), educational level(-) and household work time(-). These relationships were statistically significant(p<0.001) and R2 (coefficient of determination) was 0.237.

• Journal of the Korean Geotechnical Society
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• v.29 no.12
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• pp.35-44
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• 2013

In this study, a particle method without using grid was applied for analysing large deformation problems in soil flows instead of using ordinary finite element or finite difference methods. In the particle method, a continuum equation was discretized by various particle interaction models corresponding to differential operators such as gradient, divergence, and Laplacian. Soil behavior changes from solid to liquid state with increasing water content or external load. The Mohr-Coulomb failure criterion was incorporated into the particle method to analyze such three-dimensional soil behavior. The yielding and hardening behavior of soil before failure was analyzed by treating soil as a viscous liquid. First of all, a sand column test without confining pressure and strength was carried out and then a self-standing clay column test with cohesion was carried out. Large deformation from such column tests due to soil yielding or failure was used for verifying the developed particle method. The developed particle method was able to simulate the three-dimensional plastic deformation of soils due to yielding before failure and calculate the variation of normal and shear stresses both in sand and clay columns.

• Journal of the Korea Society of Computer and Information
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• v.25 no.6
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• pp.25-33
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• 2020

In this paper, the purpose is to verify the impact of performance expectations, effort expectations, social impact, individual innovation and perceived value on the intent of use and the behavior of use. Used Unified Theory of Acceptance and Use of Technology (UTAUT) to verify the applicability of this model in China, and established the research model by adding two new variables to UTAUT according to the situation of the Chinese market. To achieve this goal, 345 questionnaires were collected for experienced music creators using artificial intelligence nuggets in China by means of Internet research. The collected data were analyzed through frequency analysis, factor analysis, reliability analysis, and structural equation analysis through SPSS V. 22.0 and AMOS V 22.0. The verification of the hypotheses presented in the research model identified the decisive influence factors on the use of artificial intelligence music acceptance by Chinese users. The study is innovative in that it attempts to verify the applicability of UTAUT in the Chinese context. In the construction of the user acceptance model of AI music, three influencing factors will have an effect on users' intentions, and according to the degree of effect, from largest to smallest, they are respectively Perceived Innovativeness, Performance Expectancy and Effort Expectancy. This paper will also provide some management advices, i.e. improving the utility and usability of AI music, encouraging users with individual innovativeness, developing competitive and attractive pricing policies, increasing publicity, and prioritizing word-of-mouth advertising.

• Journal of the Korea institute for structural maintenance and inspection
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• v.23 no.3
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• pp.17-24
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• 2019

Carbon Fiber Reinforced Polymers(CFRP) has widely utilized as a material for rehabilitation because of its light-weight, deformability and workability. Because CFRP is brittle material whereas steel is ductile, it is inappropriate to apply conventional design approach for steel reinforcement. For ductile material, the behavior of combined elements is on average of that of unit element due to the stress redistribution between elements after yielding. Therefore, the mean value of the stress of combined elements is equal to that of unit element and the standard variation is smaller. Therefore, although the design value can increase, it is used as constant value because it is conservative and practical approach. However, for brittle material, the behavior of combined elements is governed by the weaker element because no stress redistribution is expected. Therefore, both the mean value and standard variation of the stress of combined elements decreases. For this reason, the design value would decrease as the number of element increases although it is eventually converged. In this paper, in brittle material, it is verified that the combination of unit element with normal distribution results in combined element with weibull distribution, so the modifying equation of mechanical properties is proposed with respect to the area load applied.

• Asian-Australasian Journal of Animal Sciences
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• v.32 no.3
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• pp.405-412
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• 2019

Objective: This experiment was conducted to determine the chemical composition, digestible energy (DE) and metabolizable energy (ME) contents of corn germ meals (CGM) and to develop equations to predict the corresponding energy contents based on the chemical characteristics of individual CGM. Methods: Sixty-six barrows (initial body weight = $51.3{\pm}4.6kg$) were allotted to 11 diets including a basal diet and 10 CGM test diets in a completely randomized design. In the test diets, CGM was included in replacement of 30% of the energy-providing ingredients in the basal diet, resulting in a final inclusion rate of 29.1%. Each diet was fed to 6 barrows housed in individual metabolism crates for a 7-d acclimation period followed by a 5-d total but separate collection of feces and urine. Results: Considerable variation was observed in acid-hydrolyzed ether extract, ether extract, ash, calcium (Ca) and total phosphorus contents among the CGM samples. On dry matter (DM) basis, the DE and ME contents of the CGM ranged from 10.22 to 15.83 MJ/kg and from 9.94 to 15.43 MJ/kg, respectively. The acid detergent fiber (ADF) contents were negatively correlated with the DE and ME contents of CGM samples. The best-fit prediction equations for the DE and ME values (MJ/kg DM) of the 10 CGM were: DE = 26.85-0.28 insoluble dietary fiber (%)-17.79 Ca (%); ME = 21.05-0.43 ADF (%)-11.40 Ca (%). Conclusion: The chemical compositions of CGM vary depending on sources, particularly in ether extract and Ca. The DE and ME values of CGM can be predicted based on their chemical composition in growing pigs.

• Korean Journal of Culture and Social Issue
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• v.24 no.1
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• pp.49-62
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• 2018

The purpose of this study is to examine the effect of distress tolerance on subjective well-being and the mediating effect of experiential avoidance in the relationship between distress tolerance and subjective well-being. We conducted an online survey a total of 285 normal adults in the nation from October 21 to 24, 2015. The questionnaire was composed of a distress intolerance index, a concise measure of subjective well-being, and acceptance action questionnaire. And questionnaires were distributed and retrived by an online survey company. Collected data has been analyzed by the structural equation modeling. The correlation analysis showed that distress tolerance was positively correlated with subjective well-being, while negatively with experiential avoidance. Also, the verification of mediating effects of experiential avoidance in the relation between distress tolerance and subjective well-being indicated that experiential avoidance partly mediated the relationship at a meaningful level. Additionally, deflection correction bootstrap analysis was used to verify indirect effects and its results revealed that the mediating effect going from distress tolerance to subjective well-being passing through experiential avoidance was statistically significant. That is, distress tolerance not only influences subjective well-being directly but also influences indirectly through experiential avoidance. Finally, significance and limitations of this study were discussed along with the suggestions for further research.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.29 no.5A
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• pp.467-475
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• 2009

Existing studies have suggested Universal Curve only for supplemental damping by damper. Therefore net damping has been determined by means of arithmetic summation between intrinsic, aero-damping of cable and supplemental damping of damper. However linear combination approach by means of the arithmetic summation is not enough theoretical background. So validity of this approach should be verified in order to design adequate cable-damper system by engineers. This study establishes governing differential equation which can consider intrinsic, aero-damping and supplemental damping as well. And also analysis method is solved by combination of muller method and successive iteration method. Consequently, this study succeeds in verification for validity of linear combination approach. As a result of this study, linear combination approach is limitedly effective in case of low stiffness and optimum damping coefficient of damper, short distance from support to damper, lower vibration mode, low aero-damping, and normal windy environment. Whereas this study will be effective in case of opposite conditions, and existing studies or linear combination approach occur to further error. Meaning of this study presents exact solution for net damping of cable-damper system, and verifies linear combination approach by means of the analysis method. In the future, if monitoring of optimum damping coefficient of a damper against aero-damping is feasible on time, algorithm of this study will be available for control of cable and semi-active damper system such as magneto-rheological damper.