• 대한통합의학회지
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• 제9권1호
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• pp.23-31
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• 2021

Purpose : To compare the immediate effects of air stacking maneuver using resuscitator bags and balloons. Methods : Twenty healthy young adults participated in this study. Forced vital capacity (FVC) and peak cough flow (PCF) tests were performed at pre-intervention, and then, the maximum insufflation capacity (MIC), forced expiratory volume in 1 s (FEV1), FEV1/FVC, peak expiratory flow (PEF), and peak cough flow (PCF) were measured using the air stacking maneuver via resuscitator bags and balloons. Interventions were randomly performed, and a 40-min break was provided between interventions. The evaluation process in this study was conducted in accordance with the guidelines of the American Thoracic Society (ATS) 2019. To compare the three outcomes measured at pre-and post-interventions, repeated measures analysis of variance was performed. Results : A significant difference was found in the MIC, FEV1, PEF, and PCF after the air stacking maneuver using resuscitator bags and balloons, whereas no significant difference was observed between resuscitator bags and balloons. Conclusion : No significant difference was found in the immediate effect of the air stacking maneuver using resuscitator bags and balloons in this study. Air stacking maneuver using balloons can increase the success rate of the techniques by providing visual feedback on the amount of air insufflation when performed with balloon blowing exercise. Balloons are cheaper and easier to buy compared to manual resuscitator bags; therefore, education on the air stacking maneuver using balloons will have a positive effect on pulmonary rehabilitation.

• 대한기계학회논문집
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• 제7권3호
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• pp.328-334
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• 1983

The turbulent hydrogen-air diffussion flame was studied experimentally and theoretically. Laser Doppler anemometer was used to measure the velocity field in the flame. Two mathematical models for the combustion reaction term, which are infinite rate model and finite rate to be derived eddy break-up model, were tested by comparing predictions with experimental data for coaxial turbulent diffusion flame. The agreement between the predictions and the data is, on the whole, very good in the case of employing the finite rate model rather than the infinite rate model. But, it was shown that the finite rate model was practically applicable to the predictions of the turbulent diffussion flame structure.

• 한국식품과학회지
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• 제25권5호
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• pp.521-525
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• 1993

계면에서의 단백질 흡착 기작을 연구하기 위하여 여러 단백질의 A/W 계면에서의 흡착이 조사되었다. BSA intermediates들의 흡착결과는 단백질 2차, 3차 구조가 계면에서의 흡착기작에 영향끼친 것을 나타냈으며, succinylated ${\beta}-lactoglobulin$의 흡착에서는 순 음전하의 증가가 정전기적 상호작용에 영향끼침을 보여 주었다. 또한 ${\beta}-casein$의 흡착은 물 구조를 파괴하는 chaotropic 염 존재하에서 흡착속도가 떨어지는 것을 시사했다.

• 설비공학논문집
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• 제19권7호
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• pp.529-536
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• 2007

The perforated type element for a heat recovery ventilation system has been studied to improve the performance. Four holes of diameter of 6mm are punched out for each flow channel to break the boundary layer development and increase the turbulence. KS cooling and heating conditions and test procedures are applied for study. The efficiencies are compared to those of the typical element with smooth surface. For cooling operations, the temperature, latent and enthalpy efficiencies increase 2.5%, 18% and 8%, respectively. For heating operations, the temperature, latent and enthalpy efficiencies increase 3%, 5% and 3.2%, respectively.

• 설비공학논문집
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• 제8권1호
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• pp.99-109
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• 1996

Experimental investigations are carried out for the characteristics of bubble rise in the Miniature Two-Phase closed Thermosyphon(MTPCT) with a thin wire insert. The working fluids applied as experimental media are of three kinds: water, methanol, and ethanol. The effects of combination of the inclination with diametric ratio $\alpha$(=d$_{0}$/D$_{I}$) on rising velocity of a large bubble in the thermosyphon are explicitly analyzed. The realm of a movable bubble and the critical value of $\alpha$ are iteratively pursued to interpret the region Figures-of-Break, rooted in the governing physics relations, according to the application of working fluid. Experimental results are compared with those of analysis and critical ranges for $\alpha$ and D$_{I}$ were ascertained from comparisons.isons.

• 한국표면공학회지
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• 제32권3호
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• pp.336-339
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• 1999

Photo-excited $TiO_2$ surface has a strong ability to induce various chemical reactions. Our study concentrates mainly on the utilisation of light energy to induce reactive radicals for environmental protection application. For instance, we have successfully used TiO$_2$ to break down foul smelling substances in air. In order to retain and separate the $TiO_2$ catalyst from the reactants and products, $TiO_2$ was immobilised by fixing onto various substrates. $TiO_2$ catalyst coated onto glass, wall paper and painted panel was found to show significant deodorising effect. The deodorising effect continues as long as$TiO_2$ is exposed to light irradiation.

• Current Optics and Photonics
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• 제2권5호
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• pp.413-421
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• 2018

We propose a novel methodology based on the multiplication function to improve the signal-to-noise ratio (SNR) for vibration detection in a phi optical time-domain reflectometer system (phi-OTDR). The extreme-mean complementary empirical mode decomposition (ECEMD) is designed to break down the original signal into a set of inherent mode functions (IMFs). The multiplication function in terms of selected IMFs is used to determine a vibration's position. By this method, the SNR of a phi-OTDR system is enhanced by several orders of magnitude. Simulations and experiments applying the method to real data prove the validity of the proposed approach.

• Korean Journal of Chemical Engineering
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• 제35권11호
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• pp.2164-2171
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• 2018

Heavy duty diesel vehicles deteriorate urban air quality by discharging a large volume of air pollutants such as soot and nitrogen oxides. In this study, a newly introduced auxiliary device a fuel activation device (FAD) to improve the combustion efficiency of internal engines by utilizing the cavitation effect was closely investigated by the fluid flow mechanism via a numerical analysis method. As a result, the FAD contributed to fuel atomization from the injection nozzle at lower inlet pressure by reducing the pressure energy. The improved cavitation effect facilitated fuel atomization, and ultimately reduced pollutant emission due to the decrease in fuel consumption. The axial velocity along the flow channel was increased 8.7 times with the aid of FAD, which improved the primary break-up of bubbles. The FAD cavitation effect produced 1.09-times larger turbulent bubbles under the same pressure and fuel injection amount than without FAD.

• 한국안전학회지
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• 제9권1호
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• pp.100-109
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• 1994

In this study, it is investigated that the possibility of the numerical simulation for the incineration of the hazardous material, crbon tetrachloride($CCl_4$). A 3-dimensional numerical technology is applied for turbulent reacting flows of the full-scale Dow Chemical incinerator. The calculations are made by a CRAY-2S, super computer. The major parameters considered in this study are kiln revolution rate (rpm), filling ratio of the solid waste(f), burner Injection velocity and angle, and turbulent air jets for swirl. And the employed turbulent reaction model is the eddy break-up model which is a kind of fast chemistry model assuming general equilibrium and used for a premixed flame. The calculated flow fields are presented and discussed. 1) The presence of turbulent air nozzles for swirl gives rise to visible increase of the convective motion over the region of the solid waste. This implies the possibility to enhance the mixing of the waste with the surrounding all and thereby to reduce thermal and species stratification, which were reported in a large rotary kiln operation. 2) Considering that the location of the recirculation region has a strong relation with the heating rate of the solid waste, the control of the recirculation region by the burner injection angle Is quite desirable in the sense of the flexible design of the rotary kiln incinerator for a carbon tetrachloride. 3) Finally, it is found that the eddy break-up model Is not suitable for carbon tetrachloride($CCl_4$) because this model is not incorporated the flame inhibition trend due to the presence $CCl_4$compound.

• 대기
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• 제27권2호
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• pp.119-131
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• 2017

We present and discuss the Tropopause Folding Turbulence Detection (TFTD) algorithm for the Korean Communication, Ocean, Meteorological Satellite (COMS) which is originally developed for the Tropopause Folding Turbulence Product (TFTP) from the Geostationary Operational Environmental Satellite (GOES)-R. The TFTD algorithm assumes that the tropopause folding is linked to the Clear Air Turbulence (CAT), and thereby the tropopause folding areas are detected from the rapid spatial gradients of the upper tropospheric specific humidity. The Layer Averaged Specific Humidity (LASH) is used to represent the upper tropospheric specific humidity calculated using COMS $6.7{\mu}m$ water vapor channel and ERA-interim reanalysis temperature at 300, 400, and 500 hPa. The comparison of LASH with the numerical model specific humidity shows a strong negative correlation of 80% or more. We apply the single threshold, which is determined from sensitivity analysis, for cloud-clearing to overcome strong gradient of LASH at the edge of clouds. The tropopause break lines are detected from the location of strong LASH-gradient using the Canny edge detection based on the image processing technique. The tropopause folding area is defined by expanding the break lines by 2-degree positive gradient direction. The validations of COMS TFTD is performed with Pilot Reports (PIREPs) filtered out Convective Induced Turbulence (CIT) from Dec 2013 to Nov 2014 over the South Korea. The score test shows 0.49 PODy (Probability of Detection 'Yes') and 0.64 PODn (Probability of Detection 'No'). Low POD results from various kinds of CAT reported from PIREPs and the characteristics of high sensitivity in edge detection algorithm.