• Proceedings of the Korean Nuclear Society Conference
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• 1999.05a
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• pp.104-104
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• 1999

The local heat transfer coefficient is experimentally investigated for the reflux condensation in a countercurrent flow between the steam-air mixture and the condensate. A single vertical tube has a geometry which is a length of 2.4m, inner diameter of 16.56mm and outer diameter of 19.05mm and is made of stainless steel. Air is used as a noncondensible gas. The secondary side is installed in the form of coolant block around vertical tube and the heat by primary condensation is transferred to the coolant water. The local temperatures are measured at 15 locations in the vertical direction and each location has 3 measurement points in the radial direction, which are installed at the tube center, at the outer wall and at the coolant side. In three different pressures, the 27 sets of data are obtained in the range of inlet steam flow rate 1.348 -3.282kg/hr, of inlet air mass fraction 11.8 -55.0%. The local heat transfer coefficient increases as the increase of inlet steam flow rate and decreases as the decrease of inlet air mass fraction. As an increase of the system pressure, the active condensing region is contracted and the heat transfer capability in this region is magnified. The empirical correlation is developed represented with the 165 sets of local heat transfer data. As a result, the Jacob number and film Reynolds number are dominant parameters to govern the local heat transfer coefficient. The rms error is 17. 7% between the results by the experiment and by the correlation.

• Nuclear Engineering and Technology
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• v.31 no.5
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• pp.486-497
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• 1999

The local heat transfer coefficient is experimentally investigated for the reflux condensation in a countercurrent flow between the steam-air mixture and the condensate, A single vertical tube has a geometry which is a length of 2.4m, inner diameter of 16.56mm and outer diameter of 19.05mm and is made of stainless steel. Air is used as a noncondensible gas. The secondary side has a shape of annulus around vertical tube and the lost heat by primary condensation is transferred to the coolant water. The local temperatures are measured at 11 locations in the vertical direction and each location has 3 measurement points in the radial direction, which are installed at the tube center, at the outer wall and at the coolant side. In three different pressures, the 27 sets of data are obtained in the range of inlet steam flow rate 1.348∼3.282kg/hr, of inlet air mass fraction 11.8∼55.0%. The investigation of the flooding is preceded to find the upper limit of the reflux condensation. Onset of flooding is lower than that of Wallis' correlation. The local heat transfer coefficient increases as the increase of inlet steam flow rate and decreases as the increase of inlet air mass fraction. As an increase of the system pressure, the active condensing region is contracted and the heat transfer capability in this region is magnified. The empirical correlation is developed by 165 data of the local heat transfer. As a result, the Jacob number and film Reynolds number are dominant parameters to govern the local heat transfer coefficient. The rms error is 17.7% between the results by the experiment and by the correlation.

• Proceedings of the Korea Institute of Fire Science and Engineering Conference
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• 1998.11a
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• pp.73-76
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• 1998

To use glazing systems protected by automatic sprinklers as fire barriers in building compartmentation, fire endurance tests of these systems have been performed by several research workers. Most of the tests concerned the types of glasses and sprinklers, sprinkler water flow rate, and sprinkler activation time. Horizontal side wall sprinklers and window glazing systems with a vertical center mullion were mainly applied in the tests. In the study, full-scale fire endurance tests were carried out to verify the ability of large glazing systems divided by a horizontal mullion and protected by pendent vertical sprinklers. The result shows that the protrusive length of the horizontal mullion, which is perpendicular to the glass surface, is the main parameter that determines the fire resistance rating of the systems. The mullion obstructs the water flow in the glass.

• Journal of the Korean Institute of Landscape Architecture
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• v.30 no.2
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• pp.63-69
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• 2002

The Second Namsan Tunnel required renovation. The landscape design was conducted as part of the comprehensive programs for renovation. The landscape design covered site analysis, design development, a working drawing and a maintenance plan. In May of 2001, the Second Namsan Tunnel was renovated and reopened to traffic. The tunnel was recreated as a new type of tunnel with function and beauty. The entrance and retaining wall of the tunnel has public character. Users are greatly affected by the entrance and retaining walls along roads. The landscape architect had to find new materials and methods to improve the environment and to combine artwork with the entrance and walls of the tunnel. The surface of the tunnel entrance and retaining walls are artistically treated with ceramic tiles and paint. Various regional characteristics and cultural meaning are symbolically expressed. Or the tunnel entrance from the Joong-gu side, entitled "Glory of the Future", the hibiscus symbolizes the bright and glorious future of Korea. On the retaining walls, entitled "Hope", the promising Joong-gu is symbolized through image of Korean magpies, mountains, rocks, roses, winds and nature. As for the tunnel entrance from the Yongsan-gu side, entitled "Vivid Spirit", pine trees symbolize the Koreans′strong will and an enterprising spirit. On the retaining walls, entitled "Lively Motions", Yongsan-gu is symbolized through image of pigeons, mountains, rocks, roses, winds and clear skys. The entrance and retaining wall of the Second Namsan Tunnel, whose surfaces are treated with tiles and paint with artistic value, would create an atmosphere using large-scale wall paintings. In this artwork, users would perceive a unique sense of place through the symbolic images of the vertical planes of the tunnel.

• Korean Institute of Interior Design Journal
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• no.21
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• pp.121-128
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• 1999

The purpose of this study is to provide practical guide for the Preference of exterior design in Apartment. The data is collected through questionnaire survey including observations and interviews. The sample consists of 229. The data is analyzed by using SPSS-PC. The major findings are as follows. (1) Most of residents recognize the importance of exterior design of apartments. (2) Most of residents are satisfied with the exterior design such as building form, color, and material and not satisfies with environment of apartments. (3) The most preferred color of Apartment is white as primary color and green as secondary color. (4) The most preferred color pattern is vertical type as facade, horizontal type as the back wall, super graphic and geometrical type as the side wall. (5) The preferred exterior images are modern, simple, and unique style.

• Transactions of the Korean Society of Mechanical Engineers
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• v.17 no.2
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• pp.458-466
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• 1993

Natural convection in trapezoidal sections of cavity was numerically investigated using a Finite Volume Method. Temperatures of the upper inclined and lower horizontal walls are constant, with vertical side walls being insulated. When the top wall is hotter than the bottom one, a single cell of stratified flow field is obtained and heat transfer occurs only by conduction. For the colder top wall, bifurcation solutions are obtained for the higher Rayleigh numbers, while unique solutions for lower values. Flow structure is strongly dependent on the configuration and the Rayleigh number.

• Transactions of the Korean Society of Mechanical Engineers
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• v.19 no.3
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• pp.741-750
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• 1995

The turbulent buoyancy-driven flow in 2-dimensional enclosed cavities heated from the vertical side is numerically calculated for both cases of a Rayleigh number of 5*10$^{10}$ for air and 2.5*10$^{10}$ for water. Three different turbulence models are considered : standard k-.epsilon. model of Ozoe and low-Reynolds-number model of Lam and Bremhorst, and another low-Reynolds-number model of Davidson. The results indicate that the use of low-Reynolds number models is recommended for the indoor airflow computation, and the results from Davidson model are reasonably close to the reported experimental data. A sensitivity study shows that the amounts of wall-heat transfer and the velocity profiles with the Lam and Bremhorst model largely depend on the choice of the wall function for .epsilon..

• Korean Institute of Interior Design Journal
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• no.32
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• pp.47-54
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• 2002

This study attempts to analyze the characteristics of interior design of the apartments in Busan that people will reside since 2001 and to find out the effects of minimalism in the interior space. The companies which are in construction of the apartments of more than 50 Pyung were selected, and the design of the living rooms of their model houses were analyzed in terms of the floor plans, architectural elements, furniture and lightings. The results reveals that the living rooms of the newly-distributed apartments in Busan show similar design characteristics without distinctive differences among the companies. The new trends provide a flexible wall which makes it possible to manipulate the number of rooms according to the family preference, art-wall design in one-side of the walls and a coffered ceiling design, which can be interpreted to be closely related to the concept of minimalism with expression of simple horizontal and vertical lines, exclusive use of decorative forms, colors and materials, and use of natural materials

• Journal of the Korean Geosynthetics Society
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• v.11 no.4
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• pp.27-35
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• 2012

Facings of mechanically stabilized earth retaining walls have function to fix the reinforcement and prevent backfill loss, but the walls are lack of structural rigidity capable of resisting applied loads. The reinforced subgrade with rigid wall was developed to have the structural functions under train loading. Though it has lots of advantages such as small deformation after construction, its negative side effects of economics and difficult construction were mainly mentioned and not practically used. To apply it for railroad subgrade, this study focus on the construction cost down and the enhancement of constructability without functional loss. To do so, the behaviors of reinforced subgrade with rigid wall were evaluated with the change of the vertical spacing and length of reinforcement. Small scale model tests (1/10 scale) and 3 m full scale tests were performed to evaluate deformation characteristics of reinforced subgrade under simulated train loading. Even though it uses short reinforcement, it showed small horizontal displacement of wall and plastic settlement of subgrade. Also, it was verified that not only 30 cm but also 40 cm of vertical spacing of reinforcement had good performance in serviceability aspects.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.19 no.3
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• pp.194-204
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• 2007

A numerical analysis and hydraulic experiments were undertaken to investigate the head loss occurring when a flow passes through vertical perforated walls. The numerical analysis applied continuity, momentum and energy equations to the control volumes that were set near the perforated wall. Non-dimensional equations were then derived to calculate both upstream depth and head loss for the given values of downstream depth and velocity. The hydraulic experiments were performed with several single and triple perforated plates varying their opening ratios and intervals. The numerical results with the single plates were compared with the experimental results, and it was shown that the contraction coefficient of the vertical line jet formed after the perforated plates relies on downstream Froude number as well as opening ratio. Based on the experimental results, empirical formulas were formulated. Finally, the formulas were applied to the triple plates sequentially from downstream side to upstream side, and it was found that in general the predicted values nicely agreed with the experimental results.