• 한국환경과학회지
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• 제11권10호
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• pp.1133-1140
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• 2002

The growth and extent of the local pressure field at any point is of primary importance as it supplies the driving force for the local wind circulation which causes a medium-range transport of air pollutants. The local pressure field is produced by the variation of temperature in the lower layers of the atmosphere, and is called the thermal wave. The thermal wave is influenced by the difference in the diurnal variations between two regions with different surface condition, for example land and sea. This difference produces the land- and sea-breeze phenomenon, and brings corresponding variations in the form of the thermal wave. Daytime temperature over the inland area (Daegu) was higher than that of the coastal area (Busan). The temperature difference reached about 5~6$^{\circ}C$ in the late afternoon(30-31 May 1999). The low pressure system of Daegu was most fully developed at the time. In this study, we investigated the possibility of thermal low onset around Daegu in summer with an analytical model. The topography effect was neglected in the model. We could predict a thermal low-pressure of about 3.4hPa at Daegu with wide flat land surface, when the inland area is about 6K warmer than the coastal area temperature. The pressure decrease is somewhat less than the observed value(4~5 hPa).

• 한국지열·수열에너지학회논문집
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• 제19권2호
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• pp.1-7
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• 2023

In this study, in order to reduce the amount of infiltration generated from windows among the heat loss generated in the building, energy shutters were installed on the windows to conduct experiments on the change in internal temperature and amount of infiltration due to the pressure difference between the environmental chamber and the pressure box. As a result of the experiment, when the pressure difference was 0Pa, the initial temperature of the pressure box of window was higher than that of the pressure box of the energy shutter, but when the pressure difference occurred, the internal temperature of the pressure box of the energy shutter was higher. In addition, the amount of infiltration of the energy shutter was lower than that of the windows in all experimental conditions, and it was concluded that the reduction rate of the infiltration load (of the energy shutters) could be reduced by 53.3% compared to that of the windows.

• 한국전산유체공학회지
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• 제4권2호
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• pp.57-66
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• 1999

Numerical Analysis has been done for the supersonic off-design jet flow due to the pressure difference between the jet and the ambient fluid. The difference of pressure generates an oblique shock or an expansion wave at the nozzle exit. The waves reflect repeatedly on the center axis and the sonic surface in the shear layer. The pressure difference is resolved across these reflected waves. In this paper, the axi-symmetric Navier-Stokes equation has been used with the κ-ε turbulence model. The second order TVD scheme with flux limiters, based on the flux vector split with the smooth eigenvalue split, has been used to capture internal shocks and other discontinuities. Numerical calculations have been done to analyze the off-design jet flow due to the pressure difference. The variation of pressure along the flow axis is compared with an experimental result and other numerical result. The characteristics of the interaction between the shock cell and the turbulence mixing layer have been analyzed.

• The Journal of Korean Physical Therapy
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• 제32권2호
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• pp.75-79
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• 2020

Purpose: This study analyzed the immediate effects of intra-abdominal pressure with visual feedback on the muscle activation of the upper trapezius and sternomastoid during natural inspiration and forced inspiration in individuals with costal respiration. Methods: The eighteen individuals with upper costal breathing pattern participated in this study. Surface electromyography was used to analyze the muscle activity of the upper trapezius and sternomastoid during natural inspiration and forced inspiration before and after intra-abdominal pressure. Results: A significant difference in muscle activation was observed with the muscle type, inspiration type, and test session (p<0.05). The muscle activities of the sternomastoid and upper trapezius decreased significantly during forced inspiration after intra-abdominal pressure training (p<0.05). On the other hand, there was no significant difference during natural inspiration in both muscles (p>0.05). A comparison of the difference between the pre-test and post-test during forced inspiration revealed the upper trapezius to be significantly larger than the sternomastoid (p<0.05). No significant difference was noted during natural inspiration (p>0.05). Conclusion: The intra-abdominal pressure has positive effects on correcting the breathing patterns in individuals with costal respiration.

• 설비공학논문집
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• 제24권9호
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• pp.679-684
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• 2012

This paper aims to evaluate performances of ventilation and insulation of 6types PVS(Passive ventilation skin) by numerical simulation. The results are as follows. 1) The result of Performance of ventilation by pressure difference, it was shown that the amount of ventilation changed bigger under 1Pa and amount of ventilation increased according to increase opening area (${\alpha}A$). Although same opening area of PVS, it can predict that pressure differences cause ventilation differences. 2) In case of same opening area of PVS, however, it was changed the amount of ventilation each types of PVS that is distinguished opening area by flow coefficient. 3) Dynamic U-value that represents performance of insulation PVS was similar change upper ${\alpha}A40\;cm^2/m^2$, great change in casse of 0.1 Pa pressure difference. In case of ${\alpha}A10\;cm^2/m^2$, it was changed bigger under 0.3 Pa pressure difference, ${\alpha}A20\;cm^2/m^2$ of PVS was changed under 0.2 Pa pressure difference.

• 통합자연과학논문집
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• 제7권1호
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• pp.39-44
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• 2014

The results of the synoptic meteorological analysis showed that when the cold and dry continental high pressure was extended, heavy snow occurred at dawn when the upper atmosphere cooled. In particular, when the continental high pressure was extended and the upper pressure trough passed through, heavy snow occurred due to the convergence region formed in the west coast area, sometimes in the inland of the Honam area. In addition, it was verified that the changes in the humidity coefficients in the upper and lower layers are important data for the determination of the probability, start/end and intensity of heavy snow. However, when the area was influenced by the middle-latitude low pressure, the heavy snow was influenced by the wind in the lower layer (925 hPa and 850 hPa), the equivalent potential temperature, the convergence field, the moisture convergence and the topography. In Case 2010 (30 December 2010), OSTIA had the best numerical simulation with diverse atmospheric conditions, and the maximum difference in the numerically simulated snowfall between NCEP/NCAR SST and OSTIA was 20 cm. Although there was a regional difference in the snowfall according to the difference in the SST, OSTIA and RTG SST numerical tests, it was not as significant as in the previous results. A higher SST led to the numerical simulation of larger snowfall, and the difference was greatest near Buan in the west coast area.

• Physical Therapy Rehabilitation Science
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• 제12권2호
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• pp.155-160
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• 2023

Objective: The purpose of this study is to confirm a comparison of bag weight and applied location change on plantar pressure and gait parameters (stride time, stride length, cadence) of the 20s students. Design: One group cross-sectional design Methods: The subjects were measured in each condition. Each condition was no carrying a bag, carrying a 3kg bag, and a 6kg bag on the right shoulder, and walked on the gait analyzer. After the location of the bag was changed, measured when a 3kg backpack and a 6kg backpack was each carried on the back while walking. Results: There was a statistically significant difference in plantar pressure according to bag weight when carried on the right shoulder (p<0.05). As a result of the post-hoc analysis, carrying a 6kg bag was a significant difference between no carrying a bag and carrying a 3kg bag (p<0.05). There was no statistically significant difference in changes in stride time, stride length, and cadence. There was no statistically significant difference in plantar pressure and gait parameters according to backpack weight. Conclusions: As a result of this study, it is thought that it will be possible to present a method for the application of the correct bag on location and weight in 20s students, and to prevent and reduce muscle musculoskeletal system diseases caused by incorrect bag wearing.

• 한국해안해양공학회지
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• 제15권4호
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• pp.242-248
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• 2003

안벽구조물로 널리 쓰이는 케이슨구조의 신뢰성설계를 위한 위상각 고려방법을 제안하였다. 기존의 방법에서는 위상차를 고려하였기 때문에 토압의 합력이 물리적으로 발생 가능한 이상의 값이 산출되어 파괴확률이 과다 평가되는 문제가 발생하지만 제안방법은 위상각을 고려하기 때문에 토압합력의 합리적인 산정이 가능하며 결과적으로 파괴확률 산정의 정확도를 높일 수 있게 되었다. 실규모의 케이슨 설계사례를 통해 기존방법과 제안방법에 의한 신뢰성해석 결과를 수치적으로 비교 평가하였다.

• 한국문헌정보학회지
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• 제31권3호
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• pp.209-237
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• 1997

본 연구의 목적은 연구기관에 소속된 전임연구자들이 자신의 연구를 수행하는 과정에서 받는 시간압박감의 정도에 따라 정보탐색행태에 특징적 차이를 나타나는지를 밝히고자 한 것이다. 결론을 요약하면, 연구자들은 연구에서 받는 시간압박감의 정도에 따라 정보검색시스템의 효율성중에서 정확성, 재현성, 다양성에 대하여 중요시하는 정도에 차이를 나타내고 있으며, 주요 이용자료 중에서는 하술지. 단행본, 연구보고서에서 차이를 나타내고 있다. 정보원의 유형에서는 기록정보원과 인간정보원 모두에서 중요시하는 정도에 차이를 나타내고 있다. 한편, 연구자들은 연구수행과정에서 받는 시간압박감에 따라 자료수집사용시간, 탐색전략수립시간 정보탐색방법, 정보탐색정도에서도 뚜렷한 차이를 나타내고 있는 것으로 밝혀졌다.

• 한국환경보건학회지
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• 제32권3호
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• pp.222-226
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• 2006

Smoking of tobacco cigarettes is associated with a rise in blood pressure together with increase in heart rate. This study was aimed to examine the acute effect of tobacco and non-tobacco cigarette smoking on the blood pressure and heart rate by randomized crossover study. In the results, systolic/diastolic blood pressure and heart rate changes after smoking were significantly different between male and female group. Blood pressure and heart rate were elevated after smoking, but statistical significance for the difference was identified only in the female group. Because Non-tobacco smoke made from leaves of E. ulmoides has no nicotine, its effect on blood pressure and heart rate was negligible. Remarkable difference of heart rate changes in women was observed between tobacco cigarette smoking group and non-tobacco cigarette smoking group.