• Journal of Advanced Marine Engineering and Technology
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• v.33 no.6
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• pp.867-872
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• 2009

In centrifugal oil filters particles are forced to move toward the filter casing wall by centrifugal force in the rotating oil flow and the particles are trapped and removed on the filter paper installed at the wall. In the present study, flow field of oil and particle motion in a centrifugal oil filter has been numerically calculated in order to estimate the filtering efficiency for various operating conditions. Fluent code was used for the numerical calculations. Uncoupling the oil flow and the particle motion and the use of particle tracking trajectory enabled the estimation of filtering efficiency for various particle sizes, particle density and the filter rotational speed. Higher filtering efficiency was observed for heavier and larger particles as well as higher filter rotational speed. For the typical case of the particle density of $6000kg/m^3$ and the particle size of $10{\mu}m$ at 3500 RPM, the calculated filtering efficiency per passage was 0.31.

• Journal of KSNVE
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• v.14 no.1
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• pp.18-23
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• 2004

균열 현상은 모든 필터에서 발생하였다. 1997년 9월 원심 압축기 B에서 발생한 지나친 진동현상으로 여러 필터 중 한 필터가 부서져 임펠러 흡입부로 빨려 들어갔다. 1997년 10월 기동중에 선회실속 문제가 임펠러에서 발생하였고, 이 원인은 임펠러 eye가 부분적으로 막혔기 때문이었다. 압축기 입구와 출구의 전체 유량과 압력 상태는 정상이었기 때문에 어떠한 서지현상도 anti-surge 시스템에 의해서 감지되지 않았다. 고장상태를 진단함으로써 압축기의 재가동을 방지하여 필터들이 부서졌다는 것을 확인하게 되었다. 이번 기계 점검과정을 통하여 원격진단의 중요성을 확인하였으며, 이에 회사는 원격서비스(remote service) 계약을 체결하여 현재 원격 진단 서비스 점검이 계약 기간에 따라 정기적으로 이루어지고 있다. 이와 같이 기계에 대한 정기적인 점검을 실시하는 목적은 기계의 결함이나 고장문제를 조기에 발견함으로써 중대한 고장으로의 진행을 사전에 예방하거나 또는 최소화하는데 있다.

• The KSFM Journal of Fluid Machinery
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• v.6 no.2 s.19
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• pp.15-22
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• 2003

Comprehensive study on a centrifugal blower for air-purifier involving a few physical filters for percolation process has been accomplished for an optimal design of the air handling system. The filtering media causes a flow resistance for induced flows by a rotating impeller. The present methodology is to adopt PIV system for velocity measurements and wind tunnel connected with an anechoic chamber for total performance test of the blower. Trial prototypes for the blades of a rotor and casing are presented for satisfaction of both flow rate and noise level set by design objectives. Tapered blades with a special casing for a fan show good performance data. The results of velocity fields also explain the reason of improvements of the blower performance.

• Journal of Life Science
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• v.27 no.7
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• pp.754-759
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• 2017

The 100 l culture system was made on the basis of LED light, and Nannochloropsis oculata was cultured in f/2 medium at light intensity ($100{\mu}mol/m^2/s$), culture temperature ($20^{\circ}C{\pm}1^{\circ}C$) and LD cycle (12hr). As a result, the maximum biomass of 1.07 g/l was cultured as a result of 100 l mass culture at $100{\mu}mol/m^2/s$ and 24 mg/l nitrate concentration in LED blue (475 nm). The extraction was carried out using sonicator, homogenizer and chemical method 0.5M HCl shredding method. The contents of chlorophyll a, chlorophyll b and carotenoid were 1.6, 0.5 and 0.3 mg/g cell. When using homogenizer, it was measured at 1.0, 0.6 and 0.2 mg/g cell. The chemical breakdown method of 0.5M HCl, chlorophyll a, b, and carotenoid contents were measured as 0.9, 0.8, 0 mg/g cell. The highest amount of biomass during the distruption time was measured at 3.6 mg/g cell at 15 min disintegration and acetone, 3.6 mg/g cell of acetone, methanol, and ethanol were measured as effective solvents. Concentration was measured by using microfilter, disk type continuous centrifuge and tubular type continuous centrifuge were 16.0, 1.1 and 0.5 g/l, respectively. Four kinds of equipment such as hot air dryer, vacuum dryer, spray dryer and freeze dryer were tested to optimize the drying process. As a result, the recovery rates of spray dryer and freeze dryer were 80% and 60%.

• Composites Research
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• v.36 no.2
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• pp.69-79
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• 2023

Oil-water separation is a critical process for several industrial applications, including oil production, wastewater treatment, food processing, and environmental area such as marine oil spills. The separation efficiency of oil-water mixtures can be influenced by various factors such as mixture composition, oil and water conditions, and the separation technology used. Over the years, various technologies have been developed to separate water and oil by physical, chemical and biological methods. This paper presents an overview of the various methods and technologies available for oil-water separation, including gravity separation, centrifugal separation, and separation using adsorbents, filters. The strengths and limitations of each method are discussed, along with recent research trends and future prospects. Furthermore, this paper aims to provide direction for future research and industrial application of sustainable and environmentally friendly oil-water separation technologies. In conclusion, we provide a comprehensive overview of recent oil-water separation technologies that will be beneficial to researchers and industrialists in the field of oil-water separation.

• Proceedings of the Korean Society of Developmental Biology Conference
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• 2003.10a
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• pp.119-119
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• 2003

분만후 젖소의 자궁내 미생물상을 조사하고 미생물로부터 분리한 Lipopolysaccharide를 적용하여 소의 번식효율 증진에 기여하고자 분만후 젖소의 도축장 유래 자궁을 채취하여 혐기적 상태에서 균분리 동정을 실시하였다. 균분리 동정을 위하여, 시료를 1cm$\times$1cm로 채취하여 혐기상태에서 거품이 생길 때까지 vortexing한 후 균액 300$\mu l$를 뽑아 혐기배지에 도말하였고 도말한 plate는 $37{\circ}C$ 혐기chamber에서 24시간 배양하였다. 혐기배지에서 자란 균의 colony를 따서 Mac, BHI+B, BHI 배지에 배양한 후 Gram stain을 실시하였다. BHI 배지에서 자란 균의 colony를 따서 BUA+B 배지에 계대배양하였고 BUA+B 배지에서 자란 균중에 가장 마지막으로 자란 균을 따서 An-IF에 넣고 탁도를 63%T로 맞춘 후 An micro plate에 100$\mu l$씩 분주하였다. 분주한 plate를 $37{\circ}C$ 혐기 chamber에서 20~24시간 동안 배양한 후 Biolog를 실시하였다. 시료의 UV측정을 위하여 Sonic Processor로 세포를 분쇄하였고 분쇄한 세포를 $4{\circ}C$에서 10,000rpm으로 10분간 원심분리한 후 상층액을 분리하여 0.45$\mu m$ 필터로 여과한 다음 여과액을 취하여 UV로 standard(E.coli O26 B6 LPS)와 sample(10배 및 20배 희석액)을 측정하였다. (중략)

• Proceedings of the Korean Geotechical Society Conference
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• 2004.03b
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• pp.684-691
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• 2004

Various researches have been undertaken to develope a method of enhancing consolidation. This study investigated the effect of ultrasound on consolidation through a series of laboratory experiments. The tests were conducted using a specially designed and fabricated equipments which can apply ultrasonic energy on a soil sample at consolidation test. Specimens were prepared using a centrifuge facility, and test conditions included ultrasonic power and treatment time. The results of the study show that the effect of ultrasonic energy on consolidation is significant. The degree of significance varies with the test conditions. It could be concluded that the study showed potential application of ultrasound to enhance consolidation.

• Analytical Science and Technology
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• v.33 no.3
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• pp.134-142
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• 2020

Twenty-one allergy-induced aromatic material in children's products were analyzed using gas chromatography mass spectrometer(GC-MSD). The analytes were extracted using an automatic Soxhlet extractor, centrifuged for 10 minutes in a fast freezing centrifuge, and the supernatant was filtered with a syringe filter and then transferred into a 2 mL vial and injected in a split mode. In the established condition, the calibration curve showed linearity with a determination coefficient of 0.9981 or more. Sensitivity was 0.3145 ~ 1.6757, which showed a fairly wide range of sensitivity for each substance. The detection limit of the device was 0.0016 ~ 0.0423 ㎍/mL and the maximum detection limit was less than 0.05 ㎍/mL. The method detection limit ranged from 0.0030 ~ 0.0589 ㎍/mL. In addition, the limit of quantification ranged from 0.0096 to 0.1876 ㎍/mL, with precision ranging from 0.41 to 10.49 % and accuracy ranging from 83 to 116 %. The analytical method developed in this study was applied to commercial products.

• Proceedings of the KAIS Fall Conference
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• 2012.05a
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• pp.367-370
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• 2012

본 연구는 하나의 장치 내에서 "싸이클론-관성충돌-여과포 집진"이라는 다단 제진 단계가 동시에 이루어져 입경 분포별로 순차적인 제진이 가능한 멀티 집진기의 처리가스 제어 효율을 극대화시킬 수 있는 기류 흐름을 얻기 위한 최적화 설계 조건을 검토하는 것이다. 우선 1단계 제진 과정인 원심력을 이용하여 조대입자의 유선 이탈을 촉진시킬 수 있는 사이클론 유동을 최적화시키기 위한 집진기 입구 형상 설계 검토를 위해 수치 해석적 연구를 수행하였다. 그 결과, 멀티집진기 입구 형상을 일반적인 설계 방식인 접선 유입식으로만 설계한 것에 비해 선회류를 한번 더 가속화시킬 수 있는 가이드 베인을 추가로 설계한 경우 선회류의 pitch가 짧고 강하게 형성되어 사이클론부에서 조대입자의 유선 이탈을 촉진시키는데 매우 효과적인 것으로 예측되었다. 단, 사이클론부 하단 벤츄리 형상으로 인해 약 4~5 m/s의 강한 하향 흐름이 호퍼 하단까지 형성되고 있어 탈리 분진의 재비산 문제가 발생할 가능성이 크므로 벤츄리 형상 설치 유무에 대한 영향도 추가적으로 연구가 필요할 것으로 판단된다.

• Journal of Korean Society of Occupational and Environmental Hygiene
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• v.15 no.3
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• pp.166-175
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• 2005

Health effects associated with metal working fluid (MWF) exposures include dermatitis, respiratory disease, hypersensitive pneumonitis, and asthma. Frequently, occupational exposures to MWFs are controlled by ventilating an enclosure with an air cleaning unit that includes a fan preceded by various kinds of filtration. There are several kinds of air cleaning units used in machining centers. But the associated troubles have hindered from efficiently using these devices. The main problem is the relatively short period of filter replacement. The reason is that the air cleaning units usually do not have the de-oiling systems, thus leading the earlier clogging of filters and reducing the flow rate of hood. Thus, the first stage of study was conducted to overcome this problem by developing the new oil mist collector equipped with the easy de-oiling system. The principle of de-oiling is that the centrifugal force generated by spinning the drum covered by filter fabric separates oils from the filter fabric. It would be very similar to the spin-dry laundry. By adopting this de-oiling technique, the problems associated with the conventional oil mist collectors could be solved. Several tests/analyses were performed to make the lab-scale oil mist collector. The collection efficiencies and the de-oiling efficiencies of commercially available filter fabrics were tested. Subsequently, the endurance test were conducted by observing SEM photos of filter fabrics and measuring tensile strength/expansion coefficient after spinning the filter drum for 20 minutes at the different rotation speeds. By doing these experiments, the most appropriate filter fabric and rotation speed/duration were selected. Finally, the new oil mist collector was designed. In the near future, this device must be tested in the real machining center.