• Proceedings of the KIEE Conference
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• 1998.11a
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• pp.100-102
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• 1998

This paper presents technique to control blower at constant air volume rate using V/F Control. Especially, this control method have not pressure sensors to measure because of using torque-speed relation based on the fan laws. Therefore, this technique is very simple and practical.

• Journal of the Korean Society for Aviation and Aeronautics
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• v.23 no.2
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• pp.21-31
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• 2015

The world air transport industry has grown steadily with quantitative expansion. The volume of air transport in the world is skyrocketing with the open-sky trend. Air passengers from or to South Korea has shown 5% of annual growth for the last couple of decades which caused South Korea now ranking in 18th in the World for air transport market size. Quantitative expansion of Air transport affects in policy making of air transport operators, such as airports, airlines or authorities, directly and indirectly. Especially, Aviation Safety field should be supported by policy regime with the growth of air transport volume, assured resources for continuous monitoring is standing out as a vital factor. This study is to estimate social costs caused by aviation accidents and investment costs for aviation safety by airports, airlines and authorities as operators. Estimated investment costs for aviation safety verified by comparing and analysing them. Precedent studies were reviewed to refer research methodology to calculate aviation accident costs and safety costs of operators. Safety costs of operators was calculated with literature researches and interview surveys among professionals of each operators in rational range.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.1 no.2
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• pp.116-127
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• 1989

Research on reheating cooling cycle and its practical application have been made to prevent unequalized distribution of temperature and humidity of room due to lack of supply air volume and dewdrops on supply diffusers to be taken place as a result of lower temperature of supply air than that of dew point of room air in cooling cycle of constant air volume, single duct, single zone and draw-through fan type. In view of the fact that human body is insensitive to humidity, it is possible not only to construct the complete non-reheating cooling cycle by increasing the humidity point allowable with the deduction of occupant's sense of pleasantness minimizing, but also to get cooling cycle decreasing the reheating quantity if the humidity exceeds the point allowable. In addition, it is possible to save maximum 8% in electric energy for cooling in cooling system by constructing non-reheating cooling cycle instead of reheating cooling cycle and by increasing the relative humidity of room from 50% to 65% in case efficiency and air pressure of cooling system are low. It is also possible to get an optimum cooling cycle by determining the room humidity in consideration of pleasantness of occupants and conservation rate of electric energy if the cooling capacity, efficiency and total pressure of cooling equipment are fixed.

• Transactions of the Korean Society of Automotive Engineers
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• v.4 no.6
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• pp.187-195
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• 1996

Because an alternative refrigerant(HFC-134a) is being used instead of CFC-12 for automotive air-conditioning system, newly designed air-conditioning components are necessary due to changes in characteristics. Optimum design scheme for receiver dryer in an automotive air-conditioning system is described with emphases upon the volume of desiccant and container. The volume of the container, that is manufactured based on the study, is reduced down to one half of the existing receiver dryers.

• Journal of the Korean Society for Aviation and Aeronautics
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• v.22 no.1
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• pp.136-144
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• 2014

This paper studied what kind of effects were made through Open Sky agreement on Korea-China air transport market. To analyze the effects on air transport markets brought by liberalization, this paper studied transport volume, number of airlines, passenger and cargo and routes from 2000 to 2012 Korea-China aviation statistics. Liberalization of shandong and Hainan Provinces agreed in 2006 caused significant differences in frequencies, transport volume, and the number of routes for both passenger and cargo services between 2007 and 2008, as well as statistically significant effects. The analysis on the effect of Korea-China Open skies Agreement between 2000 and 2012 was no difference because the global financial crisis in September 2008.

• Journal of the Korean Society of Safety
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• v.18 no.1
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• pp.14-18
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• 2003

The structural development of air-water bubble plumes has been measured under different condition on air flow rate in a cylindrical bath. The time-averaged structure of plumes has been measured with an oscilloscope and an electro-conductivity probe. The temperature of bubbles was also obtained by a thermal-infrared camera. Gas volume fraction and bubble frequency were high since bubbles concentrated on the nozzle. In general, their axial and radial values tended to decrease with increasing distance. Bubble temperature reached water temperature within a short time. The present study showed that thermal equilibrium between bubbles and water was completed before bubbles flow became stable.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.24 no.6 s.177
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• pp.1520-1528
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• 2000

This study presents a method for determining bearing stiffness and damping coefficients of air-lubricated slider bearing, and shows influences of air-bearing surface geometry(recess depth, crown an d pivot location) on flying attitude and dynamic characteristics. To derive the dynamic lubrication equation, the perturbation method is applied to the generalized lubrication equation which based on linearized Boltzmann equation. The generalized lubrication equation and the dynamic lubrication equation are converted to a control volume formulation, and then, the static and dynamic pressure distributions are calculated by finite difference method. The recess depth and crown of the slider show significantly influence on flying attitude and dynamic characteristics comparing with those of pivot location.

• Journal of the Korean Society for Aviation and Aeronautics
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• v.19 no.4
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• pp.111-116
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• 2011

Incheon International Airport is becoming a hub in the Northeast Asia region since its opening in 2001. Along with an increasing volume of air traffic, demands for airspace are also increasing significantly. In particular, air traffic delays have been growing rapidly due to an increasing volume of air traffic, specially flying to Europe through China. And therefore, there should be an alternative protocol to prevent flight delays. The main purpose of this study is to review current West Sea Airways of G597/Y64 which contains highly potential problems and to evaluate the efficacy of double-tracked airways in the west sea area.

• Proceedings of the Korea Concrete Institute Conference
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• 2003.11a
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• pp.48-53
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• 2003

The steel slag, a by-product which is produced on the process of manufacturing steel by refining pig iron is mainly used as road materials after aging it. It is necessary to age steel slag for long time in air because the reaction with water and free-CaO in steel slag could make the volume expanded. Due to this reason it prevents steel slag from being used as aggregate of concrete. But steel slag used in this study is controled by a air-jet method which rapidly cools substance melted at a high temperature. Rapid cooling prevents from generating of free-CaO in steel slag. In this study, it was investigated that steel slag manufactured by air-jet method affects on concrete in the freezing and thawing. As results of this study, concrete mixed with steel slag was worse in the freezing and thawing than concrete mixed with sand in spite of using air entraining agent. To obtain durability of concrete in the freezing and thawing, it is desirable to mix 50% of steel slag in concrete per unit weight of volume.

• Proceedings of the KSME Conference
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• 2000.04b
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• pp.19-24
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• 2000

The objective of this study is to develope a computer simulation model and estimate theoretically the transient performance characteristics of heat exchangers in an automotive air-conditioning system. To do that, the mathematical modelling of heat exchangers, such as evaporator and condenser, is presented first of all. For detail calculation, evaporator and condenser are divided into many sub-sections. Each sub-section is an elemental volume for transient modelling. The elemental volume is assumed to consist of three components, refrigerant, tube with fin, and air, and various properties including temperatures of three components are determined step along sub-sections. The properties of refrigerant R134a and air are calculated directly in the program. The heat transfer coefficients and pressure drop in single or two phase are also calculated by suitable empirical correlations. The overall tendencies of the simulation results were agreed well with those of actual situation.