• Journal of Advanced Research in Ocean Engineering
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• v.2 no.2
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• pp.86-98
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• 2016

In this study, after the installation of a subsea pipeline, backfilling was performed in the trenched area. During these operations, a stability problem in the subsea pipeline occurred. The pipeline was directly impacted by environmental loading such as waves and currents that were caused by backfill material when scouring or sediment transport and siltation was carried out. Therefore, this study reviewed whether trenching was necessary, and conducted research into an indigenous seabed property that contains granular soil. A study of cohesive soil was also conducted in order to cross-correlate after calculating the values of the critical Shields parameter relevant to elements of the external environment such as waves and current, and the shear Shields parameter that depends on the actual shearing stress. In case of 1), sedimentation or erosion does not occur. In the case of 2), partial sedimentation or erosion occurs. If the case is 3), full sedimentation or erosion occurs. Therefore, in the cases of 1) or 2), problems in structural subsea pipeline stability will not occur even if partial sedimentation or erosion occurs. This should be reflected particularly in cases with granular and cohesive soil when a reduction in shear strength occurs by cyclic currents and waves. In addition, since backfilling material does not affect the original seabed shear strength, a set-up factor should be considered to use a reduced of the shear strength in the original seabed.

• Korean Journal of Environment and Ecology
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• v.37 no.6
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• pp.464-472
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• 2023

Middle-aged women experience a lot of physical and mental stress during their developmental cycle. This stress reduces the quality of life because it leads to chronic pain and disease. Forest therapy is attracting attention as an alternative to this. Forest therapy refers to improving human health through the therapeutic elements of forests. Accordingly, this study was conducted to determine whether a sensory insight-based forest therapy program was effective in reducing stress in middle-aged women. For this purpose, middle-aged women who wanted to participate in the forest therapy program were recruited, 20 each were randomly assigned to an experimental group and a control group, and pre- and post-tests were conducted. The forest therapy program consisted of 8 sessions of 6 hours based on sense and insight. The forest therapy program was held at Saryeoni Forest in Jeju, and the measurement tools were compared by measuring perceived stress, leisure satisfaction, and stress index through pulse wave testing. The results of the study showed that the forest therapy program lowered stress and improved leisure satisfaction.

• Journal of Power Electronics
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• v.12 no.4
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• pp.528-537
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• 2012

This paper presents an interleaved resonant converter with a parallel-series transformer connection in order to achieve ripple current reduction at the output capacitor, zero voltage turn-on for the active switches, zero current turn-off for the rectifier diodes, less voltage stress on the rectifier diodes, and less current stress on the transformer primary windings. The primary windings of the two transformers are connected in parallel in order to share the input current and to reduce the root-mean-square (rms) current on the primary windings. The secondary windings of the two transformers are connected in series in order to ensure that the transformer primary currents are balanced. A full-wave diode rectifier is used at the output side to clamp the voltage stress of the rectifier diode at the output voltage. Two circuit modules are operated with the interleaved PWM scheme so that the input and output ripple currents are reduced. Based on the resonant behavior, all of the active switches are turned on under zero voltage switching (ZVS), and the rectifier diodes are turned off under zero current switching (ZCS) if the operating switching frequency is less than the series resonant frequency. Finally, experiments with a 1kW prototype are described to verify the effectiveness of the proposed converter.

• Korean Journal of Social Welfare
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• v.64 no.4
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• pp.285-310
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• 2012

This study examined the causal relationship of between stressors and depression using the wave 1~4 of Korean Welfare Panel Study by social stress theory. According to the result, the level of depression and depressed group was decreased in the course of time. As a panel regression analysis, Factors affecting the reduction of depression was upward of the income hierarchy, increase the satisfaction of family and social relationships, and residential satisfaction. Based on the results, the author suggested that social work policies and intervention direction should decrease social stress factors with causality to depression of the men in baby boom generation.

• Journal of the Korean Society of Marine Environment & Safety
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• v.29 no.7
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• pp.992-1001
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• 2023

OWEC (Overtopping Wave Energy Converter) is a wave power generation system using the wave overtopping. The performance and safety of the OWEC are affected by wave characteristics, such as wave height, period. To mitigate this issue, optimal OWEC designs based on wave characteristics must be investigated. In this study, the environmental conditions along the Ulleungdo coast were used. The hydraulic efficiency of the OWEC was calculated using SPH (Smoothed Particle Hydrodynamics) by comparing 4 models that changed the substructure. As a result, it was possible to change the substructure. Through design optimization, a new truss-type structure, which is a substructure capable of carrying the design load, was proposed. Through a case study using member diameter and thickness as design variables, structural safety was secured under allowable stress conditions. Considering wave load, the natural frequency of the proposed structure was compared with the wave period of the relevant sea area. Harmonic response analysis was performed using wave with a 1-year return period as the load. The proposed substructure had a reduced response magnitude at the same exciting force, and achieved weight reduction of more than 32%.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.22 no.3
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• pp.536-545
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• 2021

This study was conducted to investigate the effect of agarwood (Thymelaeaceae) inhalation using an electric incense burner on stress and brain waves. Sixteen participants were included in the study during the period from September 2019 to April 2020. Participant recruitment was undertaken by the 'H' center. This paper focused on stress reduction and compared the differences in stress and brain waves before and after agarwood inhalation using an electric incense burner. Electroencephalography was measured by a 19 Channel, Brainmaster Discovery, and analyzed using a NeuroGuide, LORETA (Brain Mapping). The analysis of technical statistics was carried out using SPSS/WIN 21.0 and the Wilcoxon signed-rank test. The study observed that the stress response index was reduced by a significance level of 0.01 in patients with anxiety, depression, and somatization disorders after agarwood inhalation. Secondly, alpha waves were increased by a significance level of 0.05, in 18 out of 19 regions measured, except FP 1. The difference after agarwood inhalation was the most significant in the region that affects emotion. Thirdly, a LORETA analysis found that alpha waves were increased in the brain region (BA 40) predominantly responsible for memory and emotion. This result clarifies that agarwood inhalation using an electric incense burner reduced stress and had a positive effect on brain waves and hence, has potential as an alternative therapy.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2008.04a
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• pp.33-41
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• 2008

Architectural acoustics design of Namsadang exclusive use theaters should be designed to utilize variously to performance space that can fill flavor and taste of Namsadang performance of the Namsadang six yards. Also, analyze special quality that is sound enemy who follow in sound-absorbing materials fare arrangement of innards that is design material of architectural acoustics laying stress on tradition, use purpose and disappointment size that Namsadang exclusive use theaters seeks on the basis of specific space theme that is experience, disappointment form, seat and passageway Wall and ceiling etc. research and sound and meaning of a character wave motion powerful engineering phenomenon and reduction reverberation loss that is happened from indoor manufacturing thing reduction SCALE model of oval structure research and background of AL composition absorbing material of perforate 25% to heighten acoustic absorptivity of practical use internal organs sound absorption material emir quality sound-absorbing materials insert and layer of air most suitable reverberation time of Namsadang exclusive use theaters that 2.2m volume is $42,218\;m^3$ to become 1.2Sec architectural acoustics design do.

• The Journal of the Korea Contents Association
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• v.19 no.3
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• pp.500-509
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• 2019

The study looked at the effect of body food on stress reduction and NK cell activity in improving natural healing for nurses, and examined whether it is effective in preventing and curing human health. The study was conducted for 30 days on 22 nurses who currently worked for more than a year at a general hospital in Gyeonggi Province. Stress measurements were conducted through pulse wave measuring instrument, and blood tests were conducted on the activity of NK cells. Treatment of collected data was performed by Paired t-testing through the Stat program SPSS 21 and providing body food suitable for the physical quality of participants after the classification of the body based on the internal diameter of the emperor and scholarship. Studies have shown that the effect on reducing the stress of body food has significant positive effects and that body food is effective for the activity of NK cells. This study has the following significance: First, the main health threat factor for modern people is the increased resistance of natural healing through body food to stress, which has the potential to prevent disease. Second, immunodeficiency in disease prevention and treatment is very important, which can increase the natural healing power of the human body by increasing the activity of NK cells through body food.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.4 no.2
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• pp.63-71
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• 1992

A solution method is developed for computing the bed shear stress driven by combined wave and current flow on a natural mobile coastal beach. An empirical equation is introduced to determine the shape of ripples formed on the natural sandy beach. The model being based on the Prandtl's mixing length theory, the effect of arbitrarily-angled interaction is included in the estimation of current velocity reduction and all numerical integrations are expressed by explicit approximate equations to improve the computation speed. In addition the computed sediment transport rates were compared with the measured values reported in literature. using the refined bottom friction model considering the ripple formation.

• Journal of Environmental Science International
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• v.25 no.9
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• pp.1269-1281
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• 2016

This study evaporative cooling system a heat wave climate change and reduction of the inside and outside thermal environment change research. Measurement items included micro meteorological phenomena and measured comfort indices. A micro meteorograph of temperature, relative humidity, surface temperature, and the comfort indices of WBGT, UTCI, and PMV were measured. The difference in inside and outside temperatures were compared for different land types, with the largest difference found in Type A ($4.81^{\circ}C$), followed by Type B ($4.40^{\circ}C$) and Type C ($3.12^{\circ}C$). Relative humidity was about 10.43% higher inside due to water injection by the evaporative cooling system. Surface temperature was inside about $6.60^{\circ}C$ higher than the outside all types. WBGT were Type A ($3.50^{\circ}C$) > Type B ($2.71^{\circ}C$) > Type C ($1.88^{\circ}C$). UTCI was low heat stress inside than outside all types. PMV was analysed Type C for inside predicted percentage of dissatisfied 75%, other types was percentage of dissatisfied 100% by inside and outside. Correlation analysis between land cover type and temperature, surface temperature, pmv, utci. T-test analysed inside and outside temperature difference was significant in all types of land.