• Journal of the Korean Society of Safety
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• v.21 no.5 s.77
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• pp.46-52
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• 2006

The purpose of this paper is to investigate the removal efficiency of fine dusts as the configuration condition of machinery and equipments in Clean Room and to analyze the flowing behaviors of fine dusts as the layout of Clean Room. The layout of the Clean Room was classified into side layout type, 2 center line type and center concentration type layout, and the flow rates used in this research were 0.22m/s, 0.44m/s and 0.80m/s. Dust removal efficiency as layout change was decreased 37% for side layout type, 31% for 2 center line type and 20% for center concentration type layout at the flow rate of 0.22m/s, compared with the state without machinery and equipments in Clean Room. The efficiency was decreased 42% for side layout type, 22% for 2 center line type and 8% for center concentration type layout at the flow rate of 0.44m/s, and decreased 20% for side layout type, 18% for 2 center line type and 10% for center concentration type layout at the flow rate of 0.80m/s. According to the result of dust removal behavior, $0.3{\mu}m,\;1{\mu}m\;and\;3{\mu}m$ dust except for $5{\mu}m$ showed the higher change of the behavior in side layout type than in center concentration type layout due to the change of air flow. It was confirmed that removal behavior depends on the layout of machinery and equipments as the dust size decreases.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.21 no.5
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• pp.623-629
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• 2020

This study examined the airflow field around a gun port on the flight condition of gunfire to verify the aircraft performance and safety effects and gun gas rate, path according to the options of diverter configuration. The gun port diverter not only effectively lowered the heat generated by gunfire but also effectively discharged the gun gas upwards. The path of gun gas can be changed according to its configuration. According to the optional configuration of the rear-gun-port diverter, the flow rate, path, and pressure of the gun gas were analyzed during gunfire. An analysis of the internal velocity distribution and the temperature change of the gun port revealed a rapid decrease in flow rate through the rear diverter according to the option configuration. The forward flow rate showed a similar tendency with little change. This ensures that the gun gas generated during gunfire has a sufficient flow distance from the aircraft surface, regardless of the rear gun port diverter's optional configuration. The flow stagnation of gun gas according to the option configuration of diverter had a great influence on the internal temperature rise of a gun port.

• Fire Science and Engineering
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• v.33 no.1
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• pp.50-59
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• 2019

Experimental and numerical studies on the fire characteristics according to the distance between the fire source and sidewall under the over-ventilated fire conditions. A 1/3 reduced ISO 9705 room was constructed and spruce wood cribs were used as fuel. Fire Dynamics Simulator (FDS) was used for fire simulations to understand the phenomenon inside the compartment. As a result, the mass loss rate and heat release rate were increased due to the thermal feedback effect of the wall in the compartment fire compared to the open fire. As the distance between the fire source and sidewall was reduced, the major fire characteristics, such as maximum mass loss rate, heat release rate, fire growth rate, temperature, and heat flux, were increased despite the limitations of air entrainment into the flame. In particular, a significant change in these physical quantities was observed for the case of a fire source against the sidewall. In addition, the vertical distribution of temperature was changed considerably due to a change in the flow structure inside the compartment according to the distance between the fire source and sidewall.

• The KSFM Journal of Fluid Machinery
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• v.18 no.4
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• pp.30-35
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• 2015

This study analyzed the variations in the performance and operation of a 200 kW class micro gas turbine according to performance degradation of compressor and turbine. An in-house code, developed by the present authors and presented in the first part of these series of papers, were used for the analysis. The degradation of compressor and turbine were simulated by modifications in the their performance maps: mass flow rate, pressure ratio and efficiency were decreased from the reference values. Firstly, the variations in the operating conditions (air flow rate, pressure ratio) were predicted for the full load condition. Then, the same analysis were performed for a wide partial load operating range. The change in engine's performance (power output and efficiency) due to the component degradation was predicted. In addition, the change in the compressor surge margin, which is an important indicator for safe engine operation, was evaluated.

• Proceedings of the SAREK Conference
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• 2005.11a
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• pp.129-134
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• 2005

The behavior of whole system is affected by a minor change of system in the hydronic radiant floor heating system. Under partial load condition, the change of system resistance causes overflow of supply water. This unexpected effect is the cause of several problems in the heating system. In this study, we find some factors were validated with several computer simulations. After validation of this result, several conceptual solutions are evaluated to prevent overflow.

• Korean Institute of Interior Design Journal
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• v.24 no.6
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• pp.221-228
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• 2015

This study aims to define concepts on Hospital Design Focused on System to respond to the development and change by comparing general design methods of the General hospital architecture in Korea and analyze elements suitable to concepts on Hospital Design Focused on System in the General hospital architecture through examining the transformation of General hospitals in Korea. Essential architectural elements composing the Hospital Design Focused on System are as follows. First of all, the elements which can react to development of hospital architecture are HOSPITAL STREET and site situation. Secondly, core, equipment shaft, column, MAIN STREET and air handling unit room are elements of great importance as the location of these elements determines the dimensions and scale of the space which hospital functions are assigned to. Third, the area in regard to the rate of change is formed by MAIN STREET, which is the primary element, and envelope. The depth between MAIN STREET and envelope is defined as space depth. The flexible area is determined depending on this space depth and thus how to set up this flexible area determines the degree of readiness in responding to the change.

• Korean Journal of Agricultural and Forest Meteorology
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• v.3 no.1
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• pp.55-70
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• 2001

It was unusual crop weather for 1998 and 1999 compared with normal in Korea. The consecutive days of the optimum ripening period for rice plant that had daily mean temperature 21~23$^{\circ}C$ for 40 days after flowering, increased with long anomalies in 1998~99. The air temperature during ripening period was much higher than the optimum temperature and lower sunshine hour than norm in the local adaptability tests of newly developed rice lines during those years. In response of rice cultivation to warming and cloudy weather during crop season, the yield shall be decreased. Most scientists agree that the rate of heating is accelerating and temperature change could become increasingly disruptive. Weather patterns should also become more erratic. Agrometeorologists could be analyzed yearly variations of temperature, sunshine hour and rainfall pattern focused on transient agroclimate change for last a decade. Rice agronomists could be established taking advantage of real time agricultural meteorology information system for fertilization, irrigation, pest control and harvest. Also they could be analyzed the characteristics of flowering response of the recommended and newly bred rice cultivars for suitable cropping plan such as cultural patterns and sowing or transplanting date. Rice breeders should be deeply considered introducing the characteristics of basic vegetative type of flowering response like Togil rices as prospective rice cultivars corresponding to global warming because of the rices needed higher temperature at ripening stage than japonica rices, photoperiod-sensitive and thermo-sensitive ecotypes.

• Journal of Korea Foundry Society
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• v.20 no.3
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• pp.181-187
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• 2000

There are two types of vacuum die casting, one is known as the chill block method, and the other is the valve block method. Efficiency of the valve block method is better than the chill block method. However purchasing and maintaining cost of the former one is very high, the latter method is popular in many small and medium die casting shops. Simple evacuation system using chill vent was prepared to investigate the effect of the air pressure, hose length and chill vent type on the pressure change in die cavity in this study. The rate of evacuation was influenced by the evacuation method, chill vent condition and hose length. Evacuation time became longer and vacuum level lower when evacuating cavity via chill vent. It took a longer time to evacuate the cavity when a longer hose was used. Vacuum level in the cavity also decreased with increase in hose length.

• Journal of Korean Society for Atmospheric Environment
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• v.26 no.1
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• pp.69-76
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• 2010

While increased use of motor cycles in the recent years for various demands could worsen air quality, only few studies have been conducted on estimation of emission factors and characterization of emissions from motorcycle. In this study, emissions from selected six models of motorcycle based on largest market share and production rate were investigated. To investigate gaseous and carbonaceous air pollutants, such as carbon monoxide (CO), total hydrocarbon (THC), nitrogen oxide ($NO_x$), elemental carbon (EC) and organic carbon (OC), total 124 motorcycles between 2003 and 2007 model year were tested with regulatory driving conditions, such as CVS-40 and CVS-47 mode. These motorcycles were further sub-categorized based on their displacement (< 50 cc, 50~150 cc, and $\geq$ 150 cc), type of stroke (2- and 4 strokes) and model year (2003~2005 and 2006~2007). Tested motorcycles with recent model year (2006~2007) exhibited less emissions of regulatory gaseous and carbonaceous air pollutants compared to old model year (2003~2005). Chemical analysis showed that CO present in highest concentration followed by THC and $NO_x$ for all tested motorcycles. Interestingly, two strokes motorcycle produced higher THC emission but less CO and $NO_x$ than those of four strokes. For all types of displacement and stroke, emission factors (gram per kilometer) of THC and CO except $NO_x$ with recent model year (2006~2007) showed decreased trend compared to old model year (2003~2005). In addition to this, due to mixed combustion between gasoline fuel and lubricant, two strokes motorcycle showed OC > EC emission trend.

• 연구논문집
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• s.24
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• pp.41-48
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• 1994

This experimental study deals with the extinguishiment characteristics of an oil pool flame using the water spray. The water through the six different atomizers is ejected over the freely burning pool flame in the quiescent surrounding air. Injection direction is vertical to the surface of oil in a small tank with a diameter of 100mm and a height of 10mm. In order to estimate quantitatively the extinction, the burning rate as well as the effective water flux are measured. The effective water flux is the amount of the water which reach the pool from the nozzle. The burning rate with the water spray increases until the injection pressure increases to reach some value, which gives the maximum burning rate, while the effective water flux without the flame decreases or does not change according to increasing of the injection pressure. This maximum burning rate is greater than 2.5 times of burning rate of the fire without the water spray. As a matter of the extinguishiment, it is found that the water drops of which size is too small can not extinguish the fire because too small drops does not reach the fuel surface.