• 한국정밀공학회지
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• 제19권10호
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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.

• 설비공학논문집
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• 제19권12호
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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.

• 설비공학논문집
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• 제29권12호
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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.

• 수산해양기술연구
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• 제53권3호
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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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• 제38권2호
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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.

• 한국산학기술학회논문지
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• 제16권3호
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• pp.1600-1604
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• 2015

현대 주택이 고기밀 고단열로 건축되기 때문에 에너지 절감의 이점이 있는 반면 오염된 공기로 인한 많은 부작용이 발생하고 있다. 이런 부작용을 해결하기 위해 환기장치를 사용하여 실내 공기 환경을 개선하고 있다. 본 연구에서는 폐열회수 환기장치의 일종인 히트파이프를 사용하여 작동유체 충진량 및 환기량에 따른 히트파이프의 환기성능을 시험적으로 평가하였다. 본 연구에서 사용된 히트 파이프는 환기장치에 적용이 가능하도록 분리형으로 제작되었다. 작동유체는 R22이고 유체의 충진량은 40~55(%vol.)로 5(%vol.) 단위로 충진 하였다. 환기량은 전면풍속을 기준으로 0.3~1.5m/s로 0.3 m/s 간격으로 바꿔 가며 측정하였다. 시험결과 최대 효율을 가지는 냉매 충진량이 환기량에 따라 다름을 알 수 있었고, 실험 결과 분석을 통하여 분리형 히트파이프의 환기량에 따른 최적 냉매 충진량을 찾을 수 있었다.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2000년도 추계학술대회 논문집
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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.

• 설비공학논문집
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• 제1권2호
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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.

• 한국건축시공학회:학술대회논문집
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• 한국건축시공학회 2008년도 춘계 학술논문 발표대회
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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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• 제2권1호
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• pp.19-25
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• 1970

이 연구는 다봉속내에서의 인접유로간의 냉각재 혼합류를 실험적으로 다룬 것이다. 실험은 19봉속내의 사각형 유로와 삼각형 유로간의 혼합류를 단상 유동과 공기-물 이상 유동에 물질 전달량을 측정하여 얻고 있다. 실험결과는 단상 유동에서 낮은 혼합률을, 공기-물 이상 유동에서 큰 혼합률을 얻고 있으며 공기-물 유동에서의 혼합률은 공기 체적률의 증가에 따라 감소되고 있음을 나타내고 있다. 공기-물 이상 유동에서의 높은 혼합률은 공기류에 의한 충분한 교란효과 때문인 것 같다.