• Journal of Korean Association for Spatial Structures
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• v.17 no.1
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• pp.49-58
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• 2017

The result of the previous work leads to the idea that the inner area of the hyperbolic shell generator should be minimized for the cooling tower with higher first natural frequency. In this study the inner area of the hyperbolic shell generator was graphically established under varying height of the throat and angle of the base lintel. From the graph, several shell geometries were selected and analysed in the aspect of the natural frequency. Three representative towers reinforced differently due to different first natural frequencies were analysed non-linearly and evaluated using a damage indicator based on the change of natural frequencies. The results demonstrated that the damage behaviour of the tower reinforced higher due to a lower first natural frequency was not necessarily advantageous than the others.

• Journal of Korean Association for Spatial Structures
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• v.12 no.3
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• pp.97-104
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• 2012

In the design procedure of the cooling tower the form-finding of the shell is the most important process, because the shape of the shell determines the sensitivity of dynamic behaviour of the whole tower against wind excitation. In engineering practice, geometric parameters of the shell are generally determined based on natural frequency analysis. 32 cooling tower shell geometries were selected through variation of the geometric parameters of an existing cooling tower shell. They were evaluated based on the first natural frequency. From the result three representative cooling towers are selected for the analysis of the structural behaviour by means of linear FE-method. As a result, a hyperbolic rotational shell with the small radius overall will yield the shell geometry with a higher first natural frequency and thus a wind-insensitive structure.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.17 no.9
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• pp.369-374
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• 2016

Cooling towers have been installed on rooftops or outside of buildings and widely applied to control the indoor temperature in residential areas and buildings. However, the noise and vibration resulting from their operation may cause problems in adjacent buildings. The purpose of this study is to measure the noise and vibration of an industrial cooling tower located adjacent to industrial plants and to investigate its influence on the surroundings according to an authorized evaluation standard. Further, in order to measure the effect of the vibration of the tower on the precision equipment inside the plant, an experiment is conducted to measure the vibration of the ground in the plant and the targeted precision equipment. The measurement results indicate that the noise in the cooling tower is 4 to 9 dB(A) higher than the maximum level defined in the standard of 68dB(A). The effect of the vibration of the tower on the precision equipment is comparatively minimal, because that in the supporting frame of the building is weaker than that on the floor where the precision equipment is located. The vibration of the floor on.

• International Journal of Air-Conditioning and Refrigeration
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• v.13 no.2
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• pp.99-106
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• 2005

Falling film heat transfer has been widely used in many applications in which heat and mass transfer occur simultaneously, such as evaporative coolers, cooling towers, absorption chillers, etc. In such cases, it is desirable that the falling film spreads widely on the surface to form a thin liquid film to enlarge contact surface and to reduce the thermal resistance across the film and/or the flow resistance to the vapor stream over the film. In this respect, hydrophilic treatment of the surface has been tried to improve the surface wettability by decreasing the contact angle between the liquid and the surface. However, the hydrophilic treatment was found not very effective to increase the surface wettedness of inclined surfaces, since the liquid flow forms rivulet patterns instead of a thin film as it flows down the inclined surface and accelerates gradually by the gravity. In this work, a novel method is suggested to improve the surface wettedness enormously. In this work, the surface is treated to have a thin hydrophilic porous layer on the surface. With this treatment, the liquid can spread widely on the surface by the capillary force resulting from the porous structure. In addition to this, the liquid can be held within the porous structure to improve surface wettedness regardless of the surface inclination. The experiment on the evaporative cooling of inclined surfaces has been conducted to verify the effectiveness of the surface treatment. It is measured that the latent heat transfer increases almost by $80\%$ at the hydrophilic porous layer coated surface as compared with the untreated surface.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.16 no.4
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• pp.349-354
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• 2004

Scale is formed when hard water is heated or cooled in heat transfer equipments such as heat exchangers, condensers, evaporators, cooling towers, boilers, and pipe walls. When the scale deposits in a heat exchanger surface, it is conventionally called fouling. The objective of the present study is to analyze the process of the fouling formation in a heat exchanger according to different types of water using visualization techniques. In order to experimentally investigate the formation of the fouling, this study built a lab-scaled heat exchanging system. Using the visualization techniques of Scanning Electron Microscopy (SEM) and X-Ray diffraction method, the three dimensional configurations of the fouling formation could be successfully obtained. Based on the experimental results, it was found that the configurations of the fouling formation were different when using tap water compared to river water.

• Proceedings of the Korea Society of Environmental Toocicology Conference
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• 2003.10a
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• pp.152-152
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• 2003

The majority of the SKYBIO will be used in the treatment of water in food processing plants, swimming pools and cooling towers, in the manufacture fabric softeners in Australia. Most will eventually be released into domestic sewage system as a consequence of product use. The SKYBIO is not readily biodegradable (0% over 28 days), and is expected to have a low partition coefficient and high water solubility (285 g/L), all indicating that the material would be mobile in both aquatic and terrestrial compartment. The PEC/PNEC ratio for the aquatic environment is 56. This value is significantly greater than 1, indicating an immediate concern to the aquatic compartment. However as a consequence of it's cationic character, the SKYBIO will be expected to associate to negatively charged organic matter in soil and sediment.

• Membrane and Water Treatment
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• v.1 no.4
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• pp.273-282
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• 2010

Treatment and reuse of industrial wastewater is becoming a major goal due to water scarcity. This may be carried out using membrane separation technology in general and reverse osmosis (RO) in particular. In the current study, polyamide (FT-30) membrane was employed for treatment of wastewater obtained from Faraman industrial zone based in Kermanshah (Iran). The effects of operating conditions such as transmembrane pressure, cross flow velocity, temperature and time on water flux and rejection of impurities including COD by the membrane were elucidated. The aim was an improvement in membrane performance. The results indicate that most of the chemical substances are removed from the wastewater. In particular COD removal was increased from 64 to around 100% as temperature increased from 15 to $45^{\circ}C$. The complete COD removal was obtained at transmembrane pressure of 20 bars and cross flow velocity of 1.5 m/s. The treated wastewater may be reused for various applications including makeup water for cooling towers.

• The Magazine of the Society of Air-Conditioning and Refrigerating Engineers of Korea
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• v.15 no.1
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• pp.67-81
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• 1986

냉각탑, 밀폐식냉각탑, 증발식응축기는 증발식냉각기의 분류에 속한다. 열은 증발에 의해 제거되어, 중력에 따라 유하하는 수 film으로 부터 충전물, 또는 밀폐식냉각탑, 증발식응축기의 관군상을 흐르는 공기에 전달된다. 따라서 공기측에서의 열과 물질의 이동프로세스는 기본적으로는 동일하다. 각 형식에서의 차이는 냉각되는 유체측에서의 열저항의 형태가 다르다는 점이다. 이 무저항은 냉각탑에서는 아주 작으나 다른 두 경우에 있어서는 계산상 고려하지 않으면 안된다. 이 논문은 이들 세 형식에 대해 통일된 이론을 적용할 수 있다는 것을 보여주기 위한 것이다. 그러므로 열 및 물질이동저항의 계산을 위한 식에 대해 논의하고 있다. 또한 복잡성을 피하기 위해, Merkel의 근사식을 공기측의 열 및 물질이동계산에 이용하였다.

• Wind and Structures
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• v.27 no.1
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• pp.11-27
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• 2018

The straight-cone steel cooling tower is a novel type of structure, which has a distinct aerodynamic distribution on the internal surface of the tower cylinder compared with conventional hyperbolic concrete cooling towers. Especially in the extreme weather conditions of strong wind and heavy rain, heavy rain also has a direct impact on aerodynamic force on the internal surface and changes the turbulence effect of pulsating wind, but existing studies mainly focus on the impact effect brought by wind-driven rain to structure surface. In addition, for the indirect air cooled cooling tower, different additional ventilation rate of shutters produces a considerable interference to air movement inside the tower and also to the action mechanism of loads. To solve the problem, a straight-cone steel cooling towerstanding 189 m high and currently being constructed is taken as the research object in this study. The algorithm for two-way coupling between wind and rain is adopted. Simulation of wind field and raindrops is performed with continuous phase and discrete phase models, respectively, under the general principles of computational fluid dynamics (CFD). Firstly, the rule of influence of 9 combinations of wind sped and rainfall intensity on flow field mechanism, the volume of wind-driven rain, additional action force of raindrops and equivalent internal pressure coefficient of the tower cylinder is analyzed. On this basis, the internal pressures of the cooling tower under the most unfavorable working condition are compared between four ventilation rates of shutters (0%, 15%, 30% and 100%). The results show that the 3D effect of equivalent internal pressure coefficient is the most significant when considering two-way coupling between wind and rain. Additional load imposed by raindrops on the internal surface of the tower accounts for an extremely small proportion of total wind load, the maximum being only 0.245%. This occurs under the combination of 20 m/s wind velocity and 200 mm/h rainfall intensity. Ventilation rate of shutters not only changes the air movement inside the tower, but also affects the accumulated amount and distribution of raindrops on the internal surface.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.13 no.12
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• pp.5676-5683
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• 2012

In this study, numerical analysis was performed on three shapes of heat transfer plates (chevron, wave and dimple type), which are currently used as fillers of cooling towers. Results show that heat transfer rates per consumed power were larger for enhanced plates as compared with that of plain plate. Highest heat transfer coefficient was obtained for wave shape followed by chevron and dimple shape. For wave shape, cross corrugations induced significant mixing of fluids, which enhanced the heat transfer. Friction factor yielded a similar trend with the heat transfer coefficient. However, heat transfer rate and pressure drop per sheet was the largest for chevron shape, due to the largest heat transfer area per sheet.