• Transactions of the Korean Society of Mechanical Engineers B
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• v.29 no.12 s.243
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• pp.1299-1306
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• 2005

The suitable pressure regulator modeling at each opening ratio and pressure ratio is very important to obtain reliable results, especially in small scale pipeline network analysis such as a pressure regulator system. And it is needed to confirm both whether temperature recovery is achieved after passing by the pressure regulator's narrow neck and how much amount of low temperature area that can cause condensate accumulation is distributed by various PCV models and driving conditions. In this research, the numerical model resembling P company pressure regulator that is used widely for high pressure range in commercial, is adopted as the base model of CFD analysis to investigate pressure regulator's flow characteristics at each pressure ratio and opening ratio. And it is also introduced to examine pressure regulator's critical flow characteristics and possibility of condensation or freezing at each pressure ratio and opening ratio. Additionally, the comparison between the results of CFD analysis and the results of analytic solution obtained by compressible fluid-dynamics theory is attempted to validate the results of CFD modeling in this study and to estimate the accuracy of theoretical approach at each pressure ratio and opening ratio too.

• Journal of Korean Association for Spatial Structures
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• v.13 no.1
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• pp.51-57
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• 2013

There can be diverse causes in the destruction of a large space structure by strong wind such as characteristics of construction materials and changes in internal and external wind pressure of the structure. To evaluate the wind pressure of roof against the large space structure, wind pressure experiment is performed. However, in this wind pressure experiment, peak internal pressure coefficient is set according to the opening of the roof in Korea wind code. In this article, it was tried to identify the change of internal pressure coefficient and the characteristics of wind pressure coefficient acting on the roof by two kinds of opening on the side of the structure with Hyperbolic Paraboloid Spatial Structures roof. When analyzing internal pressure coefficient according to roof shape, it was found that minimum (52%) and maximum (30%~80%) overestimation was made comparing to partial opening type proposed in the current wind load. It is judged that evaluation according to the opening rate of the structure should be made to evaluate the internal pressure coefficient according to load.

• Journal of the Korean Solar Energy Society
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• v.32 no.4
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• pp.51-58
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• 2012

This study aims to analyze characteristics of Cell surface temperature and generated power performance for improving PV(Photovoltaic) system condition according to the cell opening ratio of transparent crystal PV system at Spandrel of curtain-wall. For this purpose, alternatives were classified for eight different cases that opening ratio of transparent crystal PV system varied from 0% to 70%, which was used by simulation tool, EnergyPlus. As results, it turned out that increasing opening ratio of transparent crystal PV system led higher PV surface temperature, back-sheet type was thus the most advantageous for decreasing surface temperature, annual generating efficiency, and annual accumulated generating power. Consequently, blocking off air space from outside insolation can advantageously keep to be better condition for generated power performance.

• The Transactions of the Korean Institute of Electrical Engineers B
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• v.51 no.10
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• pp.560-567
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• 2002

This paper presents the calculation of opening characteristics for puffer GCB with the equations of the flow field and the motion of the driving mechanism. To obtain the stroke curve, the motion equation is solved simultaneously with the Euler equations. For a given Piston location, the flow field is solved. The pressure inside the Puffer chamber is then used to calculate the moving velocity and the new position of the piston. The FVFLIC method is employed to solve the axisymmetric Euler equations and the motion equation is solved by the Runge-Kutta method. The method is applied to the puffer GCB model and the stroke curve and the pressure rise in puffer chamber under no load condition are compared with the measured ones.

• 유체기계공업학회:학술대회논문집
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• 2000.12a
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• pp.259-264
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• 2000

The functions of the plug valve are the control of flow rate as well closing and opening pipe lines. Analyses on the flow characteristics in plug valve port are required to improve the performance and safety at severe operating conditions such as high-pressure and high-temperature. In this study, numerical analyses are carried out with varying the opening rate (fraction of the full open to close) of the valve and the shapes of valve Uk: straight, convex, concave and mixed shapes. The parameters influencing the flow characteristics in the valve are the discharge coefficient( $C_v$) and the resistance coefficient( K). Therefore, the distributions of static pressure, velocity vector and stream lines are investigated, and $C_v$ and K are calculated in each opening rate and shape. In case of full open, the static pressure passed through the valve port has almost been recovered. However, in case of other opening rates, the pressure does not permanently regained due to pressure drop leading to loss. This phenomenon in each shape of the valve shows the different behaviors. Calculation results show that the mixed shape has the best flow attribute.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.30 no.7
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• pp.11-19
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• 2002

Inflating characteristics of the parachute canopies have been experimentally investigated with the objective of measuring the parachute opening parameters such as canopy filling time and the peak opening force using scaled parachute models. A device has been made and tested to eject a model parachute into a wind tunnel flow and to measure the drag force acting on it. The force-time histories and the peak opening force are obtained, and these comparative aerodynamic characteristics were analyzed and discussed, including the effect of forebody wake. The opening of the ringslot parachute model appeared to be faster than that of the available similar data by about 10~40%, and fair to good agreement was obtained for the reefed ribbon parachute.

• Journal of the Korean Society of Clothing and Textiles
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• v.45 no.5
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• pp.770-787
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• 2021

This study examines the types of cotton, silk, and woollen products imported from Japan during the port-opening period and explores the characteristics of import trade related to these textile products. Data were obtained from the Japanese trade statistics published by the Japanese government between the late 19^th and the early 20^th centuries. Several key findings were made from these data. First, at least 24 types of cotton fabrics, 13 silk fabrics, and 16 woollen fabrics imported from Japan were identified. Several types of weaves that can be found in the present day were also identified. Second, the total import of textiles during the port-opening period made up 33.7% of the total imports from Japan, indicating that textiles were an important aspect of import trade with Japan. The value of textile imports from Japan tended to increase overall during this time. Cotton fabrics and silk fabrics showed a tendency to increase continuously, while woollen fabrics showed a trend of gradual increase over repeating periods of increase and decrease. It is apparent from examining the ratio of Japanese and foreign products that cotton fabrics, silk fabrics, and woollen fabrics show different characteristics.

• Journal of Korean Neurosurgical Society
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• v.66 no.2
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• pp.172-182
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• 2023

Objective : The blood-brain barrier (BBB) is an obstacle for molecules to pass through from blood to the brain. Focused ultrasound is a new method which temporarily opens the BBB, which makes pharmaceutical delivery or removal of neurodegenerative proteins possible. This study was demonstrated to review our BBB opening procedure with magnetic resonance guided images and find specific patterns in the BBB opening. Methods : In this study, we reviewed the procedures and results of two clinical studies on BBB opening using focused ultrasound regarding its safety and clinical efficacy. Magnetic resonance images were also reviewed to discover any specific findings. Results : Two clinical trials showed clinical benefits. All clinical trials demonstrated safe BBB opening, with no specific side effects. Magnetic resonance imaging showed temporary T1 contrast enhancement in the sonication area, verifying the BBB opening. Several low-signal intensity spots were observed in the T2 susceptibility-weighted angiography images, which were also reversible and temporary. Although these spots can be considered as microbleeding, evidence suggests these are not ordinary microbleeding but an indicator for adequate BBB opening. Conclusion : Magnetic resonance images proved safe and efficient BBB opening in humans, using focused ultrasound.

• Journal of Korean Association for Spatial Structures
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• v.8 no.3
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• pp.53-63
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• 2008

In this study, the reverberation characteristics of coupled spaces were investigated using a scale model. Two rooms were connected through an acoustically transparent opening known as an aperture. The acoustic characteristics of the coupled room by varying three parameters, the aperture opening size, the absorption ratio between the two rooms and the locations of the secondary room, were measured and analysed. The results indicated that a reverberant secondary room, produced large variations of the acoustics in the main room and an absorptive secondary room was effective to provide systematic control of the acoustics in the main room. The reverberant secondary room should be located at the rear of the stage and the aperture opening ratio over 6.25% produced large variations of the acoustics in the main room. However, the aperture opening ratio over 25% had no effect on variations of the acoustics in the main room. The absorptive secondary room should be located at the rear of the audience areas and the aperture opening ratio over 3.13% produced large variations of the acoustics in the main room.

• KIEAE Journal
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• v.11 no.5
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• pp.107-117
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• 2011

This paper aims to analyze architectural planning factors that could contribute to reductions in electricity consumption in the household of apartments, to apply energy saving methods at the design phase. These six architectural planning factors were orientation, building type (flat, tower block), standard floor access type (corridor access type, stair case type, EV hall access type), household location (floor), household opening type (one side opening, right angle opening, two sides opening or three sides opening), and bay on the facade (one bay, two bays, three bays, four bays), and these were derived from literature review. Household electricity consumption data were gathered from 2168 households with a total area of 135~150$m^2$ of 6 apartment complexes over 1000 households in Seoul. The annual characteristics of electricity consumption according to architectural planning factors were analyzed. And, variances between groups with respect to the mean of summer, winter, and annual electricity consumption according to each architectural planning factors were analyzed using ANOVA and t-test. The results showed that an annual electric energy saving of over 1000kWh was facilitated by these planning factors. In addition, high energy efficiency architectural planning factors based on the analysis were as follows: southwest orientation, flat type, corridor access type and staircase type, household loation below the 20th floor, two sides opening and three sides opening, and 2 bays and 3 bays.