• 한국공작기계학회:학술대회논문집
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• 한국공작기계학회 2005년도 춘계학술대회 논문집
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• pp.138-143
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• 2005

The important problem in the high speed spindles is to reduce and minimize the thermal effect by the motor and ball bearings. Thermal characteristics according to the bearing preload and hollow shaft cooling are studied for the spindle with the oil mist lubrication and high frequency motor. Temperature distribution and thermal deformation according to the spindle speed, preload and flow rate are measured by thermocouple and gap sensor. Temperature distribution and thermal deformation are analyzed by using the finite element method. The results of analysis are compared with the measured data. This paper show that the suitable preload and hollow shaft cooling are very effective to minimize the thermal effect by the motor and ball bearings. This study indicates that temperature distribution and thermal deformation of the high speed spindle system can be estimated reasonably by using the three dimensional model through the finite element method and supports thermal optimization and more effective cooling method.

• 한국공작기계학회논문집
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• 제14권6호
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• pp.31-36
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• 2005

Use of the high frequency motor spindles are increasing for the high speed machine tools recently. The important problem in the high speed spindles is to reduce and minimize the thermal effect by the motor and ball hearings. Thermal characteristics according to the bearing preload and spindle cooling are studied for the spindle with the oil mist lubrication and high frequency motor. Temperature distribution and thermal displacement according to the spindle speed, preload and flow rate are measured. Temperature distribution and thermal displacement of the high speed spindle system can be estimated reasonably by using the three dimensional model through the finite element method. The results of analysis are compared with the measured data. This study supports thermal optimization and find out more effective cooling condition. This paper show that the suitable preload and spindle cooling are very effective to minimize the thermal effect by the motor and ball bearings.

• 한국환경보건학회지
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• 제27권2호
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• pp.30-36
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• 2001

This review begins with a brief expression of aerosol capture mechanism of fibrous filter(s) and performance of particulate removing respirators. The more complicated and detailed discussion is not included in this articles. Filtration efficiency and pressure drop are introduced as quality factor ( $q_{F}$) and the way in which filtration efficiency varies with particle size is discussed. Quality factors fro filters recently certified in USA were found to be very higher than those of filters made in Korea, China and USA filters certified with old certified standards. Electrically charged filters are widely used because they have high filtration efficiency and low pressure drop, but their efficiency decreases sharply at the condition occurring wet and oil mist. A discussion is given of respirator leakage through face seal and filter media with fit testing and total inward leakage testing. Since fit factor (FF) refers to the reciprocal of the fraction of the total air entering a respirator through face seal leakage , the degree of fitting performance for respirators is expected with FF. Because respirators made in Korea had generally lower FFs than respirators made in USA, it is necessary to develope respirators that fit properly for Koreans or establish regulations for fit testing.g.

• 한국초전도ㆍ저온공학회논문지
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• 제3권1호
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• pp.64-68
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• 2001

An experimental study on the Joule-Thomson cryocooler with the mixed refrigerant (MR) is described in this paper, J-T refrigeration experiment was performed with a single stage regular air-conditioning compressor The mixed refrigerant in the experiment was composed of 75% mol fraction of $N_2$. 30% moi fraction of CH$_4$. 30% moi fraction of $C_2$H$_{6}$. 10% mot fraction of $C_3$H$_{8}$ and 15% mot fraction of iso-C$_4$H$_{10}$. Oil mist in the MR stream could be eliminated completely by the glass microfiber filter. Since a single stage compressor that had been designed thor R22 is not appropriate for high Pressure ratio of the mixed refrigerant especially during the transient period. two modifications were incorporated to regular J-T refrigeration cycle. First. a Portion of the MR was by-passed at the inlet of the heat exchanger and transferred directly to 7he suction of the compressor in the modified system. Second, a buffer volume was Prepared to change the mass flow rate of refrigerant. The pressure ratio in J-T expansion device was relieved at the beginning of the operation due to the by-Pass scheme. but it gradually decreased during the transient Process as some of the MR component condensed at low temperature. The buffer volume at the suction side was used to increase the MR gas density in the system after the transient cool-down period. Form the experiment with the modified system, the refrigerator could reach the lowest temperature of -152$^{\circ}C$ without cooling load. and about -15$0^{\circ}C$ with 5 W of cooling load . . . .

• 해양환경안전학회지
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• 제18권3호
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• pp.279-285
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• 2012

LNGC 주기관의 크랭크 챔버 내 유증기 폭발 방지를 위해 기존의 이산화탄소 가스인젝터가 부착된 오일미스트 감지기 외에 불활성가스 시스템을 설치할 필요가 있다. 특히, LNGC 선박은 액체질소를 손쉽게 확보할 수 있는 장점이 있기 때문에 액체질소를 이용한 불활성가스 시스템을 도입하기 위한 설계 기초 단계로서 해석적 연구를 시행하였다. 또한 액체질소 최소 소모량 시스템을 개발하기 위하여 층상류 모델을 적용하였으며, 층상류 흐름에 미치는 유로관경, 포화압력과 선박동요에 따른 배관 기울기 등의 영향에 대해서도 조사하였다. 또한 질소와 같은 극저온 유체들과 여기에 사용된 예측 모델과의 비교 검토를 통하여 극저온 유체에 대해서도 모델의 유효성을 검증하였으며, 액체질소 불활성가스 시스템의 액체질소를 가스로 상변환 시키는데 소요되는 가열기의 열부하도 예측할 수 있었다.

• 한국정보통신학회논문지
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• 제20권3호
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• pp.583-589
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• 2016

VOCs(Volatile Organic Compounds)의 대부분은 유해물질로 대기 오염뿐만 아니라 지구 온난화의 원인물질로 작용하고 있다. 이로 인해 VOCs는 국가마다 배출을 줄이기 위해 정책적으로 관리되고 있다. 특히, 주유소에서 발생하는 유증기는 발암물질인 벤젠 등 인체에 유해하며 환경부에서 연료 주유 시 발생하는 휘발성 유기화합물을 회수할 수 있도록 유증기 회수장치 설치를 의무화하고 있다. 최근에는 기존의 유증기 처리 방식을 발전시켜 폭발이나 화재 등을 방지하기 위하여 유증기를 냉각시켜 현장에서 바로 회수하도록 하고 있다. 본 논문에서는 이러한 위험성이 존재하는 액화기의 상태를 실시간으로 모니터링 할 수 있도록 유증기 액화장치에 센서를 부착하여 액화기 측정 정보를 모니터링 할 수 있는 모니터링 서버 및 안드로이드 기반의 모니터링 앱 어플리케이션을 개발하여 원격관리 서비스 모델을 제시하고자 한다.

• 공업화학
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• 제28권2호
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• pp.193-197
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• 2017

본 연구에서는 대형 직화구이 음식점으로부터 배출되는 유증기 및 미세먼지 제거를 위해 습식 플라즈마 전기집진 공정을 적용할 경우, 집진공정 후단에서 나오는 잔여 오존을 활용하여 제거되지 않은 아세트알데히드와 오존을 제거함으로써 복합악취를 저감할 수 있는 오존 산화 촉매 공정을 개발하였다. 망간산화물 기반 촉매는 분말 촉매 제조 후 압출하여 펠렛 형태로 성형하였으며, 성형촉매 상에서 아세트알데히드와 오존 모두 높은 제거율을 나타낼 수 있도록 최적 조건을 도출하고자 하였다. 제조한 $Mn_2O_3$와 $CuMnO_x$ 촉매는 각각의 성능을 평가하였으며, 이 두 가지 촉매를 2단으로 적용하였을 때 공간속도 $10,000h^{-1}$, 반응온도 $100^{\circ}C$인 조건에서 아세트알데히드는 85% 이상, 오존은 100% 저감시킬 수 있었다.

• 한국기후변화학회지
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• 제6권4호
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• pp.311-318
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• 2015

Emission characteristics from charbroiling of four different meats (beef, port, duck and chicken) in a pilot-scale cooking facility were investigated in this study. The analyzed air pollutants include gaseous species (CO, NO, $SO_2$, $NH_3$ and PAHs) as well as particulate matters (TSP, $PM_{10}$, $PM_{2.5}$ and black carbon). The emission factors of $PM_{10}$ and PAHs were in the range of 3~47 g-PM/kg-meat and 0.6~11.41 mg-PAHs/kg-meat, respectively, depending on the type of a meat. In addition, the results also revealed that the high ratio of $PM_{2.5}$ to TSP in a meat charbroiling should be considered to design and to operate air pollution control devices.

• 한국입자에어로졸학회지
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• 제17권4호
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• pp.115-123
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• 2021

The emission gas from meat grilled restaurants has unpleasant odor and sticky particulate matters (PM) in form of oil mist. This affects the residents living nearby. In oder to decrease the odor and PM, electrostatic precipitators (ESP) were installed at several restaurants by support of Seoul metropolitan government and emission characteristics of PM and odor were investigated. The removal efficiency of odor and PM at before- and after-ESP was that total hydrocarbon (THC), NH₃, H₂S, acetaldehyde, butyraldehyde were not much decreased. Total suspended particles (TSP) emitted from the vent was below the value of 7 mg/m³ regardless of the concentration of before-ESP and removal efficiency was in the range of 64 ~ 86%. The ratio of PM_1.0 to PM₁₀ of emission gas was over 0.9. So it was revealed that most PM of emission gas was PM1.0. The PM concentration in the air of the street near the vent was higher than another street due to the emission gas and the PM of indoor air of restaurant grilling meats was measured very high compared to outdoor air. So it needs more powerful ventilation of indoor air.

• 산업경영시스템학회지
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• 제45권3호
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• pp.104-114
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• 2022

The purpose of using coolant in machining is both to increase a tool life and also to prevent product deformation and thus, stabilize the surface quality by lubricating and cooling the tool and the machining surface. However, a very small amount of cutting mist should be used because chlorine-based extreme pressure additives are used to generate environmental pollutants in the production process and cause occupational diseases of workers. In this study, medical titanium alloy (Ti-6Al-7Nb) was subjected to a processing experiment by selecting factors and levels affecting cutting power in the processing of the Aerosol Dry Lubrication (ADL) method using vegetable oil. The machining shape was a slot to sufficiently reflect the effect of the cutting depth. As for the measurement of cutting force, the trend of cutting characteristics was identified through complete factor analysis. The factors affecting the cutting force of ADL slot processing were identified using the reaction surface analysis method, and the characteristics of the cutting force according to the change in factor level were analyzed. As the cutting speed increased, the cutting force decreased and then increased again. The cutting force continued to increase as the feed speed increased. The increase in the cutting depth increased the cutting force more significantly than the increase in the cutting speed and the feed speed. Through the reaction surface analysis method, the regression equation for predicting cutting force was identified, and the optimal processing conditions were proposed. The cutting force was predicted from the secondary regression equation and compared with the experimental value.