• Journal of the Institute of Electronics Engineers of Korea TC
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• 제44권10호
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• pp.13-19
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• 2007

Location awareness is one of the key functions to build U-city. Recently, many of works for location-aware systems are emerging to commercially apply to on-going large-scale apartment complex. As dwellers or cars being attached with active tags are moving in the U-city complex, the active tags periodically broadcast their own identifiers mu routers fixed along the street or in a building use those information to calculate location of thorn. There are several issues to be considered for such an environment. In this paper we propose i) a new architecture for location-aware system considering such issues ii) technical issues to implement it using active tags, and iii) a mathematical analytic model to investigate overall performance and verify it by comparing with actual experimental results. Through mathematical analysis, we can show that it is more efficient for the routers to send location signals than the tags do. We also show that there are several additional services available in the apartment complex. We conduscted several experiments hi a real ease parking lot to show that our system can locate the location of dwellers or cars.

• Journal of the Korean Chemical Society
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• 제51권1호
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• pp.21-30
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• 2007

A multiwavelength spectrophotometric titration method was applied to study protolytic constants of four water-soluble vitamins, folic acid(vitamin B9 or B0), thiamine(vitamin B1), riboflavin(vitamin B2) and pyridoxal (vitamin B6) in binary ethanol-water mixtures at 25oC and an ionic strength of 0.1M NaNO3. The protolytic equilibrium constants, spectral profiles, concentration diagrams and also the number of components has been calculated from the curve fitting of the pH-absorbance data with appropriate mass balance equations by an established factor analysis model. DATAN program was used for determination of acidity constant and SPECFIT program was used for calculation of standard deviations and partial correlation coefficients. A glass electrode calibration procedure based on the four parameter equation pH=α+SpcH+JH+[H+]+ JOH-Kw/[H+] based on the Gran,s plots was used to obtain pH-readings in the concentration scale (pcH). The effect of the solvent on the protolytic constants was discussed.

• Journal of the Computational Structural Engineering Institute of Korea
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• 제30권1호
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• pp.17-22
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• 2017

In this study, we designed the metallic reception part of a patch antenna using the phase field design method. The design object function is formulated with the S-parameter value which represent the return loss so that it is targeted to maximize radiation efficiency at a target frequency. The initial model of a patch antenna was designed via the ordinary theory based approach and its performance was enhanced by changing the structural configuration of the metallic part using the phase field design method combined with the double well potential functions. The final shape was proposed by removing the gray scale area along the structural boundary by employing a cut-off method. The proposed shape shows that the radiation efficiency at target frequency is significantly improved compared with the initial patch shape. The finite element analysis and optimization precess was performed using the commercial package COMSOL and Matlab programming.

• Journal of the Computational Structural Engineering Institute of Korea
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• 제29권5호
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• pp.471-482
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• 2016

In this study, we focused on a speed-up of KIESSI-3D program, which is based on FE-IE techniques, by introducing a p-version dynamic infinite element method. In order to evaluate performance of the KIESSI-3D, numerical analyses for eight real-scale SSI problems are carried out. We considered three types of KIESSI-3D numerical models whose radii of near-field soil region($r_0$)are 1.2, 1.5, and 3.0 times of basemat radius of structure(R). In addition, SSI analyses using the SASSI2010 program are carried out used for comparison of accuracy and runtime against those of the KIESSI-3D. Numerical results show that the KIESSI-3D model of $r_0=1.2R$ is enough to give accurate solution. In view of the computing speed, the new KIESSI-3D was up to 25 times faster than the old KIESSI-3D.

• Journal of the Society of Naval Architects of Korea
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• 제52권6호
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• pp.452-459
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• 2015

It is important to use bench test results in the design process of anti-rolling tanks. Traditional bench tester is usually designed to perform only roll motions about a fixed axis and relatively small so that the viscous effects may not be neglected. Novel bench tester which could adjust the motion center to realize the coupled motion of sway and roll has been devised and manufactured therefore, large scaled bench tester could be utilized for designing the passive anti-rolling tanks. The time history of the reference signal from the rotation sensor of the bench tester have been recorded and processed to determine the phase angle to derive the Response Amplitude Operator(RAO) of the stabilized ship. The breadth of ART tank model should be large up to 2 m to diminish viscous scale effect and the vertical position of the tank can be varied with the ship's center of motion. The periods and the amplitude of roll motion can be varied from 1.5 sec to 5 sec and up to ±20°, respectively. The components of the tester was expressed in three dimensional digital mockup (DMU) and assembled together in the CAD space. The final configuration of the bench tester has been determined by confirming the smooth operation of the moving parts without interference through the animation in CAD space. New analytic logic are introduced for the determination of hydrodynamic moment and phase difference due to fluid motion in ART and verified through the test. The developed bench tester is believed to be effective and accurate for the verification of stabilization effect of ART taking into the consideration of the sway effect in the design stage.

• Journal of the Society of Naval Architects of Korea
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• 제52권6호
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• pp.471-477
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• 2015

When a ship sails in a seaway, the resistance on a ship increases due to incident waves and winds. The magnitude of added resistance amounts to about 15–30% of a calm-water resistance. An accurate prediction of added resistance in waves, therefore, is essential to evaluate the performance of a ship in a real sea state and to design an optimum hull form from the viewpoint of the International Maritime Organization (IMO) regulations such as Energy Efficiency Design Index (EEDI) and Energy Efficiency Operational Indicator (EEOI). The present study considers added resistance problem of AFRAMAX-class tankers with the conventional bow and Ax-bow shapes. Added resistance due to waves is successfully calculated using 1) a three-dimensional time-domain seakeeping computations based on a Rankine panel method (three-dimensional panel) and 2) a commercial CFD program (STAR-CCM+). In the hydrodynamic computations of a three-dimensional panel method, geometric nonlinearity is accounted for in Froude-Krylov and restoring forces using simple wave corrections over exact wet hull surface of the tankers. Furthermore, a CFD program is applied by performing fully nonlinear computation without using an analytical formula for added resistance or empirical values for the viscous effect. Numerical computations are validated through four degree-of-freedom model-scale seakeeping experiments in regular head waves at the deep towing tank of Hyundai Heavy Industries.

• Journal of the Korea Society of Computer and Information
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• 제19권8호
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• pp.187-196
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• 2014

This study analyzed whether the factors of studying resilience of high school students had a control effect on self-efficacy and academic achievements depending on the degree of stress. For this purpose, this study set the cause and effect model and the research hypothesis through literature and then conducted a survey of 292 people of high school students in G metropolitan city. The analysis of this study showed that recognition ability and communication skill, which are the factors of studying resilience, had different effects on self-efficacy and academic achievements depending on the degree of stress. It has great significance that if the stress level of the high school students is lower, self-efficacy and academic achievements are higher. Therefore, this study suggested how to inspire the academic achievements based on the results of this analysis.

• Journal of the Earthquake Engineering Society of Korea
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• 제6권6호
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• pp.41-48
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• 2002

This study is on the structural control experiment for a small scale three-story building structure employing on active mass damper subjected to earthquake loading. $\mu$-synthesis controllers, which belong to robust control strategies, were designed and their performance were experimentally verified. Frequency-dependent weighting functions corresponding to disturbance input and controlled output were defined and combined to produce optimal $\mu$-synthesis controllers. The experiment result shows 60-70% reduction in RMS responses under the band-limited white noise excitation and 30-45% reduction in peak responses under the scaled earthquake excitations. Good agreement was obtained between the simulations based on the identified mathematical model and experimental results. And the simulations for the system with uncertainties show that the designed controllers are robust within a specified range of uncertainties.

• Journal of the Korean Society of Clothing and Textiles
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• 제34권7호
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• pp.1184-1196
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• 2010

Several applications of body scanning technology have been commercialized or are currently under development. The virtual fit from 3D scans is most advanced form of virtual try-on. This article is an analysis of the comparison of user preferences for domestic versus foreign 3D virtual try-on systems. For this study, domestic i-Fashion Mall (www.ifashionmall.co.kr) and a Canadian company, My Virtual Model (www.mvm.com) were selected as the most representative online retailers that offer a virtual try-on system. The respondents were comprised of 70 Korean female college students in the age group 20-29. A five point Likert scale was used to evaluate the degree of the preference of virtual avatar and try-on images. T-test, cross table, and a chi-square independence test were conducted for data analysis. The results are as follow. 1. The representation about current looks according to each virtual fit image indicates that MVM is more accurate than i-Fashion Mall. 2. About decision confidence, respondents have decision confidence in i-Fashion Mall in the case of the avatar image; however, respondents have confidence in MVM or the fit image. 3. There were no significant differences in among waist size groups in accuracy, trust of each avatar image, while there were significant differences among waist size groups in the accuracy and trust of each virtual fit image. 4. About ease of use, respondents answered that i-Fashion Mall is superior to MVM. 5. The respondents prioritized the ‘fitting report’ of i-Fashion Mall and ‘Weight loss’ of MVM over other functionalities.

• Health Policy and Management
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• 제24권1호
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• pp.71-84
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• 2014

Background: Informal care is increasingly recognized as placing a significant burden on the lives of family caregivers. The purpose of this study is to investigate factors related to family caregivers' burden with the community-dwelling disabled elderly under the long-term care insurance system, using the Stress Process Model developed by Pearlin (1990). Methods: Total 1,233 family caregivers with the disabled elderly, using the long-term care services in their home from May to June 2009, completed questionnaires finally. The questionnaire of this study consists of a total of 32 questions, including 11 questions related to background and context, 17 questions related to objective stressors, and 4 questions related to coping resourses. Family caregivers' burden is measured by the Korean Revised Caregiving Appraisal Scale (K-RCAS, Cronbach's alpha=0.86). To investigate factors related to family caregivers' burden, multiple regression analysis was conducted. Results: The average score of caregivers' burden was 22.0 (${\pm}6.12$). In multiple regression analysis, there were statistically significant factors affecting on the family caregivers' burden, that are related to background and context (region, living status, education level, relationship with beneficiary), objective stressors (duration of caregiving), coping resourses (caregiver's health status). Conclusion: This study found that family caregivers experience a considerable burden. The findings suggest that policies must be taken to relieve family caregivers of their duties temporarily, and to support them with counselling and education.