• Magazine of the Korean Society of Agricultural Engineers
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• v.42 no.6
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• pp.72-82
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• 2000

Many lot of books introduce the methods to calculate the time of concentration, and these are described as various forms of formulas. There are few formulas appropriate for our basin characteristics Therefone, there are problems to make excessive or less estimation when these formulas are used. To solve these problems, comparison of formulas and sensitivity analysis for them were made with converting parameters. Finally, Time of concentration was estimated to derive Application limits for 3 watersheds by standardized formulas. In the case of input parameters analysis, SCS formula has the highest value by the length, Kerby by the height and SCS by the slope, respectively, while Kraven formula has the lowest value among them. Concerning the relative sensitivity by Taylor series, the time of concentration showed the constant effect while increasing of the length and slope, and the length was more sensitive than the slope in parameters. Finally the standardization formula developed in this study was applied to derive application limits for 3 watersheds(total 17 subbasins). In this case, Rziha(8 subbasins) and SCS(9 subbasins) formulas were the most similar to observed data of total 17 subbasins respectively. Application limits were about 300~500$\textrm{km}^2$ area, 30~60km length and under 0.01 slope for Rziha formula and about 100~200$\textrm{km}^2$ area, 10~30km length, and over 0.01 slope for SCS formula, respectively.

• Structural Engineering and Mechanics
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• v.46 no.1
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• pp.19-37
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• 2013

The optimum design of base isolation system considering model parameter uncertainty is usually performed by using the unconditional response of structure obtained by the total probability theory, as the performance index. Though, the probabilistic approach is powerful, it cannot be applied when the maximum possible ranges of variations are known and can be only modelled as uncertain but bounded type. In such cases, the interval analysis method is a viable alternative. The present study focuses on the bounded optimization of base isolation system to mitigate the seismic vibration effect of structures characterized by bounded type system parameters. With this intention in view, the conditional stochastic response quantities are obtained in random vibration framework using the state space formulation. Subsequently, with the aid of matrix perturbation theory using first order Taylor series expansion of dynamic response function and its interval extension, the vibration control problem is transformed to appropriate deterministic optimization problems correspond to a lower bound and upper bound optimum solutions. A lead rubber bearing isolating a multi-storeyed building frame is considered for numerical study to elucidate the proposed bounded optimization procedure and the optimum performance of the isolation system.

• Wind and Structures
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• v.5 no.2_3_4
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• pp.277-290
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• 2002

A two dimensional discrete vortex method (DIVEX) has been developed at the Department of Aerospace Engineering, University of Glasgow, to predict unsteady and incompressible flow fields around closed bodies. The basis of the method is the discretisation of the vorticity field, rather than the velocity field, into a series of vortex particles that are free to move in the flow field that the particles collectively induce. This paper gives a brief description of the numerical implementation of DIVEX and presents the results of calculations on a recent suspension bridge deck section. The results from both the static and flutter analysis of the main deck in isolation are in good agreement with experimental data. A brief study of the effect of flow control vanes on the aeroelastic stability of the bridge is also presented and the results confirm previous analytical and experimental studies. The aeroelastic study is carried out firstly using aerodynamic derivatives extracted from the DIVEX simulations. These results are then assessed further by presenting results from full time-dependent aeroelastic solutions for the original deck and one of the vane cases. In general, the results show good qualitative and quantitative agreement with results from experimental data and demonstrate that DIVEX is a useful design tool in the field of wind engineering.

• Nuclear Engineering and Technology
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• v.52 no.6
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• pp.1131-1136
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• 2020

Xenon behaves differently in molten salt reactors (MSRs) compared to solid fuel reactors. This behavior needs exploring due to the large reactivity effect of the ¹³⁵Xe isotope, given the current interest in MSR power plant development for commercial deployment. This paper focuses on select topics in xenon transport, reviews relevant past works, and proposes specific research questions to advance the state of the art in each of the focus areas. Specifically, the paper discusses the issue of xenon solubility in MSRs, the behavior of particulates circulating in MSR fuel salt and its influence on the xenon transport, the possibility of ionization of xenon atoms which changes its effective size and thus affects its mass transport, and finally the issue of circulating void fraction and how it is measured. This work presents specific recommendations for MSR designers to research the limits of Henry's law validity, circulating particulate scrubbers, validity of mass transport coefficients in high radiation fields, and the effects of pump speed on circulating void fraction.

• Proceedings of the KSME Conference
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• 2003.04a
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• pp.2095-2100
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• 2003

This Experimental study concerns the characteristics of vortex flow in a concentric annulus with a diameter ration of 0.52, whose outer cylinder is stationary and inner one is rotating. Pressure losses and skin-friction coefficients have been measured for fully developed flow of bentonite-water solution(5%) when the inner cylinder rotates at the speed $0{\sim}400rpm$. The results of present study reveal the relation of the bulk flow Reynolds number Re and Rossby number $R_o$ With respect to the skin friction coefficients. The effect of rotation on the skin friction coefficient is significantly dependent on the flow regime. In all flow regime, the skin friction coefficient is increased by the inner cylinder rotation. The critical (bulk flow) Reynolds number $Re_c$ decreases as the rotational speed increases. Thus, the rotation of the inner cylinder promotes the onset of transition due to the excitation of Taylor vortices.

• Asian-Australasian Journal of Animal Sciences
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• v.14 no.11
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• pp.1621-1627
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• 2001

Steers and heifers (N=490) were produced between 1991 and 1996 by reciprocal fiillsib backcross and $F_1$ crosses from Angus and Brahman to compare characteristics of carcass and palatability traits between Bos indicus and Bos taurus inheritance. Carcasses of 3/4Angus were heavier, fatter (p<0.05), more tender and higher in other palatability attributes (p<0.01) than those of 3/4Brahman. Reciprocal effects of parental cross breeds were found on some traits. Within 3/4Brahman inheritance group, Brahman sired progeny produced heavier and fatter carcasses with better palatability (p<0.05) than progeny with Brahman as a dam breed. Estimates of heritability were intermediate to high in most carcass and palatability traits. Genetic correlations of tenderness with marbling score (MARB), sarcomere length (SARC), fragmentation index (FRAG) and calpastatin activity (CALP) were moderate to high, suggesting potential use of the tenderness-influencing factors as indirect selection criteria to improve palatability attributes. MARB and SARC that were best predictors of tenderness explained 3.07 to 5.85% and 4.32 to 8.24% of variation in tenderness, respectively. However, there was no tenderness-influencing factor to dominantly explain large portion of variation in tenderness.

• Journal of The Korean Society of Integrative Medicine
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• v.7 no.4
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• pp.141-150
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• 2019

Purpose : This study examined the hand function and visual motor integration capabilities in 30 children with developmental disabilities. The children were divided into an experimental group (n=20) that received digital sensory perception training and a control group (n=10) that did not receive this training. Methods : Training was conducted a total of 12 times for six weeks, for 50 minutes a day, twice a week, for the experimental group. The Jebsen-Taylor Hand Function Test was used to determine the hand function before and after the intervention, and the Beery VMI-6 was performed to identify the visual motor integration capability. Results :After the intervention, the ability to perform hand functions and visual motor interaction increased significantly in the experimental group but not in the control group. Digital sensory training therefore had a positive effect on the hand function and visual motor integration in children with developmental disabilities. Conclusion : A digital sensory perception training program is an arbitration method that can positively improve the hand function and visual motor integration ability in children with developmental disabilities.

• Management & Information Systems Review
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• v.6
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• pp.89-115
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• 2001

Recently, administrators of Korean university are struggling to survive against rapidly changing environment. But, the customer service of university organizations are generally recognized inferior to those of business service. Thus, the measuring of service quality is the beginning of works to improve customer service in university. SERVQUAL is known the most generalized scale to measure service quality. After SERVQUAL was published as a measure of perceived service quality by PZB(1985), several arguments have been made against its validity and the other measures have been suggested by Tears(1993), Cronin and Taylor(1992). Therefore, this paper reviews about SERVQUAL controversies. Also, this paper analyzed the dimensions of service quality and its relevant concepts. For this empirical study, 288 respondents drawn from university student in Pusan area are collected and 5 hypotheses are analyzed by using regression analysis. The results of empirical study are as follows. (1) three dimensions of service quality(specialty, reliability, tangiables) are perceived from factor analysis. (2) dimensions of service quality are related to the overall service quality and customer satisfaction, especially specialty is varified as the most important dimension. (3) customer satisfaction affects repurchase intention and word-of-mouth effect positively. In conclusion, however this study have a few limitations about sampling and questionnaire, offers some strategic directions for improving the service quality of university organizations.

• Hwankyungkyoyuk
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• v.23 no.1
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• pp.50-63
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• 2010

This study is a qualitative case study aiming at understanding and finding out influential factors and barriers when school teachers choose Environmental Education as their Creative Discretionary Activities. To do this, this study focuses on the process of two teachers' choices of the Creative Discretionary Activities in two other elementary schools. The results of this research are follows. Two teachers' choices are affected by several influential factors, divided into external factors and internal factors. External influential factors include culture of school and education, media, chief education officers, parents and school. Internal influential factors are teachers' value and philosophy of education, teachers' experiences, teachers' capacity. These influential factors' forces aren't the same with each other. These influential factors, are influenced by educational, social, national, local, and school level indicated by Taylor et al's (1974) classification criterion. Especially, however, Korea's particular educational environment focusing on university entrance examination strongly affects teachers' choice. School factors also has a big strong effect on teachers' choice. Among others internal actors are the most serious influential factor affecting on teachers' choice.

• Transactions of the Korean hydrogen and new energy society
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• v.27 no.6
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• pp.727-736
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• 2016

Numerical simulations of n-heptane spray characteristics in a constant volume combustion chamber under diesel engine like conditions with increasing ambient gas density ($14.8-142kg/m^3$) and ambient temperature (800-1000 K) respectively were performed to understand the non-vaporizing and vaporizing spray behavior. The effect of fuel temperature (ranging 273-313 K) on spray characteristics was also simulated. In this simulation, spray modeling was implemented into ANSYS FORTE where the initial spray conditions at the nozzle exit and droplet breakups were determined through nozzle flow model and Kelvin-Helmholtz/Rayleigh-Taylor (KH-RT) model. Simulation results were compared with experimentally obtained spray tip penetration result to examine the accuracy. In case of non-vaporizing condition, simulation results show that with an increment of the magnitude of ambient gas density and pressure, the vapor penetration length, liquid penetration length and droplet mass decreases. On the other hand vapor penetration, liquid penetration and droplet mass increases with the increase of ambient temperature at the vaporizing condition. In case of lower injection pressure, vapor tip penetration and droplet mass are increased with a reduction in fuel temperature under the low ambient temperature and pressure.