• Journal of the Korean Society for Precision Engineering
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• v.19 no.10
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• pp.221-226
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• 2002

As environmental restriction has continuously become more strict, machining technology has emphasized on development of environment-friendly technologies. In cutting technology, it has been well recognized that cutting fluids might have undesirable effects on workers health and working environment and, hence, recently there have been numerous attempts to minimize harmful effects of cutting fluids on environments. To minimize the use of cutting fluids in machining, conventional cutting fluids have been replaced with the technologies of pressurized cold air and minimum quantity lubrication (MQL). Compared with milling, turning is continuous cutting process, where tools are continuously heated up and lack of lubricity could lead to tool wear and deteriorated surface roughness. In this work, it has been investigated how tool wear and surface roughness could be affected by cutting conditions, supply and cooling methods. The experimental results show that MQL technology is able to minimize conventional cutting fluids.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.19 no.12
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• pp.811-820
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• 2007

A Study on the optimal design of the AIG(Ammonia Injection Grid) to improve the performance of DeNOx facilities in the HRSG(Heat Recovery Steam Generator) was performed using the CFD analysis. On the basis of the flow analysis results in the case that the AIG in the HRSG was not installed, the numerical analyses according to the positions of AIG, injection angles of nozzle and the control of ammonia injection quantity were carried out. The standard deviation according to factors was calculated for quantitative comparison. As the results, the AIG in the HRSG should be installed in the position that the uniform flow field shows through the exact flow analysis in the previous of the AIG design and installation. In the case the AIG has already been installed and non uniform flow distribution shows, it is recommended that flow correction device or KoNOx catalyst should be used. Otherwise, the control of ammonia injection angle or the ammonia injection quantity using the velocity profile analysis is demanded to accomplish the optimal performance.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.29 no.12
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• pp.663-672
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• 2017

Building information modeling (BIM) technology based on 3D modeling has been applied to the entire domestic construction industry since 2010. It can calculate quantity take-off considering construction productivity at design phase. Based on this, it is possible to improve the reliability of construction cost prediction of design phase in the process of cost estimation. However, Building Information Level (BIL) defined by Ministry of Land, Infrastructure and Transport and Public Procurement Service does not seem to offer doable environment due to the lack of detailed application items. By calculating construction cost that meets Construction Cost Estimate Accuracy by American Association of Cost Engineers (AACE) through quantity take-off and cost estimation based on 3D modeling of BIM technology, a BIL improvement proposal at design phase for Mechanical Contracts and Construction is provided here. Results showed that properties including outline and minimum specification of the main equipment, internal main piping, and internal main duct should be defined from the intermediate design phase to have reliable cost estimation.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.53 no.3
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• pp.302-307
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• 2017

An electric steam boiler equipped with a condensate recovery system, which stores the condensate generated after using steam in steam washers, steam cookers, steam irons, and steam cleaners in a condensate tank and supplies compressed air to the condensate tank so that the condensate is recovered to the boiler by the pressure of the compressed air, was studied. In the results of this study, the heat energy balance between the quantity of the heat generated by the non-metallic surface heating element and the quantity of the heat absorbed by the water was good in a range of ${\pm}5%$. In addition, the heat transfer rate increased in proportion to the electric power of the surface heating element heater, the waste heat energy was normally recovered by the recovery of the condensate of the steam boiler equipped with the high compression waste heat recovery system, and the recovery rate of the waste heat exhibited 23%.

• Journal of Biosystems Engineering
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• v.38 no.2
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• pp.81-86
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• 2013

Purpose: Recently, domestic and abroad consumption of mushroom has been increasing. Especially, oyster mushroom has been the most consumed product, sharing one third of the mushroom market. The air temperature differences between relative positions of the mushroom farms were needs to be minimal. However, in reality, the air temperature differences ranged from 2 to $5^{\circ}C$. Because of this, the mushrooms are non-uniform growth as well as decrease in both quality and quantity. Although air circulators have been employed by oyster mushroom farms to minimize air temperature differences, no experiments have been performed to illustrate the effect of the air circulators. Methods: This experiment is designed to analyze the effect of the air circulation by constructing a prototype air circulator and measuring the air temperature when the circulator was position at different heights (50 cm, 150 cm, 200 cm) from the floor in the center. Result: The horizontal plane air temperature of the first growing bed when the air circulator was installed 50cm above the floor in the center, once not using the air circulators and the other time using the air circulators, yielded the air temperature differences of $8.6^{\circ}C$ and $1.8^{\circ}C$ and deviations of 2.82 and 0.60, respectively. The third growing bed's air temperature differences were $10.0^{\circ}C$, $1.6^{\circ}C$ and deviations 3.28, 0.64, each respectively. These outcomes proved that the use of air circulators minimized the air temperature difference and deviation. The use of air circulators helped minimize the air temperature differences and the derivations in oyster mushroom farm. Conclusion: The use of air circulators helped balance the air temperature distribution in oyster mushroom farm.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.16 no.3
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• pp.1600-1604
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• 2015

As modern houses are constructed with high-density and high-insulation, there is benefit to reduce energy consumption, but there are many side effects raised from polluted air. To solve the problem, a ventilation system is used to improve a indoor air quality. In this research, we experimentally estimate ventilation performance of HRV(heat recovery ventilator) with heat-pipe according to working fluid filling quantity and ventilation. Heat-pipe used in this study was designated separately to be applied to a ventilation system. The working fluid was R22, which was filled from 40 to 55 (%vol.) by 5(%vol.). Ventilation based on the front velocity was measured from 0.3 m/s to 1.5 m/s by 0.3 m/s intervals. Refrigerant filling quantity with the highest efficiency was found to depend on the ventilation. From this study the optimal refrigerant filling quantity in accordance with the ventilation of the detachable heat pipes was found experimentally.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2000.11a
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• pp.793-797
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• 2000

The environmental problems by using coolant demanded the new cooling methods. As one of them the studies on the dry grinding with compressed cold air have been done. The cooling method using compressed cold air was effdve thmugh going down the temperature of compressed air supplied below $-25^{\circ}C$ and inneasing the amount of mmpresd cold air, but had not enough cooling effect due to the low performance of lubrication. Therefore, the cooling methods using MQL(Minimum Quantity Lubrication) or mist newly were suggested. These two methods can satisfy both cooling effect and lubrication with only small amount of coolant, also has the benefit in the point of decreasing the envimnmental pollution. This paper focused on analyzing the grindmg characteristics of the cooling method using mid. The generated heat and grinding force of the cooling method using mist were compared with them of coolant and compressed cold air. And them grinding test according to the temperature of compressed cold air, mist spray amount and mist supply direction were done.

• 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.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2008.05a
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• pp.83-86
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• 2008

The concrete used most in construction materials. There is an overcrowded iron dimensions use of the concrete at time of the other concrete theory on the reinforcing rod back which did congestion and compares it with this, and there are more few dimensions of the aggregate than concrete, and quantity of aggregate passage is superior in mortar than concrete. If a volume rate of the aggregate writes mortar than concrete against this, therefore, unit amount increases, and quantity of paste increases and quantity of dry shrinkage than increase concrete. However, I let I regulate lay priest distribution of the aggregate, and the results rates increase and reduce unit amount and decrease quantity of dry shrinkage, and separation resistance and the gap passage characteristics are judged because it can be it in a substitute document of very superior concrete. I came to carry out the study that I watched to let I was useful a little more and do the improvement repair of a become building wall body, a basement pillar and repair reinforcement of the assistant in the reinforcing rod back, the old age when I made congestion here. I regulated lay priest distribution of the aggregate in the study and regulated substitution rate of the aggregate (40%, 50%, 60%) and divided W/C 30%, 40% standards and produced mortar and I compared quantity of air by this, slump, compression robbery and showed it this time.

• Nuclear Engineering and Technology
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• v.2 no.1
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• pp.19-25
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• 1970

A study was conducted on the coolant mixing between water flowing in two adjacent subchannels. Measurements were made of the quantity of mass transferred between a larger rectangular channel and a smaller triangular channel in a 19-rod fuel bundle under the conditions of single phase flow and air-water two-phase flow. The results of the experiments showed that the low mixing rate appears in single phase flow, and high mixing rate was measured in air-water two-phase flow Mixing rate decreases with the increasing of air void fraction during the air-water flow. It seems that the high mixing rate in the air-water flow was caused due to adequate agitation of the chaotic air void.