원심력 필터 재생기능을 갖춘 오일 미스트 여과 집진장치 개발

김태형 ( Tae Hyeung Kim ),서정윤 ( Jeoung Yoon Seo ),하현철 ( Hyun Chul Ha ),김종철 ( Jong Cheul Kim ),조진호 ( Jin Ho Cho ) 한국산업위생학회 2005 한국산업보건학회지 Vol.15 No.3

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 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 soled. 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.

주물 공단 용해공정의 송풍기 및 백필터 관리 실태

김태형 ( Tae Hyeung Kim ),하현철 ( Hyun Chul Ha ),정춘화 ( Chun Hwa Jeoung ),서정윤 ( Jeoung Yoon Seo ),박승욱 ( Cheng Xu Piao ),양준호 ( Jun Ho Yang ),이효우 ( Xiao Yu Li ) 한국산업위생학회 2007 한국산업보건학회지 Vol.17 No.3

18 Local exhaust ventilation systems in 10 melting companies located in an industrial complex were tested to know the status of maintenance. Test items were fan flowrates, fan static pressures, rotational speeds and differential pressures of bag filters. Only 22% of the tested fans has more than 80% flowrate efficiency. 44% of the fans has lower than 60% efficiency. The performance of the fans are not in a good status. For the fans with lower than 60% efficiency, the analysis shows that the lower flowrate might be caused by the degradation of fan performance. On the other hand, for the fan s with higher than 60% efficiency, the main cause of flowrate reduction might be too much pressure losses due to clogging of filter bags. The degradation of fans usually lead the reduction of hood capture efficiency, resulting in the increase of contaminant concentrations in workplace. To keep fans in good status, self inspections should be periodically conducted. This inspection should include the measurements of flowrate and pressures. The most important thing to be performed is the initial test of local exhaust ventilation system because the initial test data should be used to know the level of system degradation.

자동차 조립 공장의 검차라인 환기 방안

김태형 ( Tae Hyeung Kim ),하현철 ( Hyun Chul Ha ),박승철 ( Seung Chul Park ),김종철 ( Jong Chul Kim ) 한국산업보건학회 2004 한국산업보건학회지 Vol.14 No.1

방해기류 존재시 추적자 가스법을 이용한 푸쉬풀 후드 효율 평가

김태형 ( Tae Hyeung Kim ),하현철 ( Hyun Chul Ha ),강호경 ( Ho Gyung Kang ) 한국산업위생학회 2006 한국산업보건학회지 Vol.16 No.3

A push pull hood system is frequently applied to control contaminants evaporated from an open surface tank. Efficiency of push pull hood system is affected by various parameters, such as, cross draft, vessel shapes, tank surface area, liquid temperature. A previous work assisted by flow visualization technique qualitatively showed that a strong cross draft blown from the pull hood to push slot could destroy a stable wall-jet on the surface of tank, resulting in the abrupt escape of smoke from the surface. In this study, the tracer gas method was applied to determine the effect of cross-draft on the capture efficiency qualitatively. A new concept of capture efficiency was introduced, that is, linear efficiency. This can be determined by measuring the mass of tracer gas in the duct of pull hood while the linear tracer source is in between push slot and pull hood. By traversing the linear tracer source from the push slot to the pull hood, it can be found where the contaminant is escaped from the tank. Total capture efficiency can be determined by averaging the linear efficiencies. Under the condition of cross-draft velocities of 0, 0.4, 0.75, 1.05 and 1.47m/s, total capture efficiencies were measured as 97.6, 95.4, 94.6, 92.7 and 70.5% respectively. The abrupt reduction of efficiency with cross-draft velocity of 1.47m/s was due to the destruction of tank surface wall-jet by the countercurrent cross-draft. The same phenomenon was observed in the previous flow visualization study. As an alternative to overcome this abrupt efficiency drop, the 20% increase of hood flow rates was tested, resulting in 20% efficiency increase.

전산유체역학을 이용한 용접흄농도 간접적 예측가능성 연구

박승욱,김태형,서정윤,허영빈,임정호,강대웅,하현철,Piao, Cheng Xu,Kim, Tae Hyeung,Seo, Jeoung Yoon,He, Rong Bin,Lim, Jung Ho,Kang, Dae Woong,Ha, Hyun Chul 한국산업보건학회 2009 한국산업보건학회지 Vol.19 No.4

There are various methods for welding fume control. These methods can be divided into local exhaust system, general ventilation system and integrated control system. With the general ventilation system, we should have a good prediction tool for testing various appropriate control options. But, until now there are not many studies about how to predict the welding fume concentrations. Especially, the prediction of welding fume concentration is not a very easy task because welding fume is the particulate matters. In this study, we tried to measure $CO_2$ concentrations and welding fume concentrations in a small single room with a small ventilation opening. Using commercially available CFD (Computational Fluid Dynamics) software, we tried to predict $CO_2$ concentrations under the exactly same conditions. Then, we tried to compare the numerical $CO_2concentrations$ with the experimental results to know whether we could predict $CO_2$ concentrations. Then we tried to compare $CO_2$ concentrations with experimental welding fume concentrations to know whether we can use the numerical $CO_2concentrations$ to predict the welding fume concentration indirectly.

개방조 후드가 설치된 도금작업장의 방해기류 측정

송세욱 ( Se Wook Song ),김태형 ( Tae Hyeung Kim ),하현철 ( Hyun Chul Ha ),홍좌령 ( Jwa Ryung Hong ) 한국산업위생학회 2004 한국산업보건학회지 Vol.14 No.3

Open surface tanks are used in a variety of industrial processes, such as picking and plating. Push-pull ventilation system is often the best and most energy efficient way to remove any contaminant which evaporates from the open surface tanks. Existing design guidelines are based on experimental and numerical works which is cannot easily be extended to different operating conditions. Contaminant removal efficiency of push-pull ventilation could be affected by various parameters, such as vessel shape, room location, cross draft, etc. Especially, the velocity of cross draft might be one of influencing factors for the effective ventilation. To account for the effect of cross draft in case of over 0.4m/s, a flow adjustment of ±20% should be designed into the push and +20% into the pull flow system. For effective design and installation of push-pull system, we must be consider the magnitude of Cross draft velocity. However, the cross draft velocity of workplace installed push-pull ventilation system were not measured yet. In this paper, we measured the cross draft and door/window face velocities in 8 surface treatment shops in which the push-pull type open surface tanks are generally used. Two-directional hot-wire anemometer was used to measure the velocities after checking the main direction of flow by using smoke-tube. The experiments were performed in both winter and summer since the flow patterns and the velocities were thought to show the quite different seasonal variations. Mean cross draft velocities of winter and summer were measured as 0.60m/s and 0.62m/s, respectively, which is over the operating range, 0.4m/s. In addition, the face velocities through doors and windows were measured as 1.38m/s and 1.79m/s, respectively. The measured cross draft velocity is somewhat higher than 0.4m/s which is recommended for the push-pull hood by ACGIH design guideline. This high cross draft velocity could destroy the hood flow in the push-pull hood system. Thus, it is imperative that the ACGIH design guide line should be modified in the near future.

푸시풀 후드시스템의 방해기류 방향 및 세기의 영향에 관한 수치적 연구

이효우 ( Xiao Yu Li ),김태형 ( Tae Hyeung Kim ),박승욱 ( Cheng Xu Piao ),하현철 ( Hyun Chul Ha ) 한국산업위생학회 2008 한국산업보건학회지 Vol.18 No.2

푸쉬-풀 환기시스템은 도금조와 같이 흡인해야 할 거리가 상대적으로 긴 경우에 많이 사용되고 있다. 그러나, 창문이나 출입문을 통한 방해기류가 푸쉬-풀 환기시스템의 오염물질 제어효율을 심각하게 훼손시키고 있다고 추측하고 있으나 이에 대한 세부적인 연구가 부족한 상태에 있다. 따라서, 본 연구에서는 전산유체역학(Computational fluid dynamics)을 이용하여 푸쉬-풀 환기시스템에서의 방해기류의 방향과 세기가 흡인효율에 어떠한 영향을 미치는지에 대해 평가해 보았다. 선형흡인효율(Linear capture efficiency) 방법을 이용하여 푸쉬-풀 환기시스템에서 가상의 개방조에서 발생한 오염물질이 푸쉬-풀 시스템에 의하여 포집되지 못하고 누출되는 구역이 어딘지를 찾아낼 수 있었다. 전산유체역학 컴퓨터시뮬레이션은 AIRPAK2.1 (FLUENT CODE) 소프트웨어를 사용하였다. 푸쉬-풀 후드시스템에 방해기류가 강하게 작용하면 상대적으로 강한 와류가 발생하는데, 일반적인 난류모델인 κ-ε모델은 와류현상을 충분히 보여주지 못한 반면에 RNG 모델을 사용했을 때 실험결과를 적절히 모사해낼 수 있었다. RNG 모델을 이용하여 세가지 방향, 즉 푸쉬에서 풀 방향으로, 풀에서 푸쉬 방향으로 그리고 그에 수직되는 방향으로 방해기류가 있을 때의 푸쉬-풀 환기시스템의 흡인효율을 분석하였다. 방해기류가 0.25m/s이하일 때에는 흡인효율이 거의 떨어지지 않았으나, 방해기류가 0.6m/s에서 흡인효율이 40-70%로 떨어짐을 알 수 있었다. 따라서, 방해기류를 감소시킬 수 있는 방안에 대해서도 연구를 해야 되겠지만, 방해기류 존재하에서 충분한 흡인 효율을 유지할 수 있는 푸쉬-풀 후드설계기준에 대한 연구도 필요할 것으로 판단된다.

자연환기 벤틸레이터 환기유량 산정

하현철(Hyun-Chul Ha),김태형(Tae-Hyeung Kim),정계수(Gye-Soo Jung) 대한설비공학회 2002 대한설비공학회 학술발표대회논문집 Vol.2002 No.-

공기분사노즐이 부착된 용접 토치를 이용한 용접흄 제어효율 평가

변세환 ( Sea Hwan Byun ),김태형 ( Tae Hyeung Kim ),하현철 ( Hyun Chul Ha ),김종철 ( Jong Cheul Kim ),강호경 ( Ho Gyung Kang ) 한국산업보건학회 2004 한국산업보건학회지 Vol.14 No.1

사각형 여과집진기 충격기류 시스템의 최적탈진조건에 관한 실험적 연구

박승욱 ( Cheng Xu Piao ),김태형 ( Tae Hyeung Kim ),이효우 ( Xiao Yu Li ),하현철 ( Hyun Chul Ha ),정재훈 ( Jae Hun Jung ) 한국산업위생학회 2008 한국산업보건학회지 Vol.18 No.3

Cylindrical bag filter system with pulse jet cleaning has been the most common device to control particle laden exhaust gas from the various industrial processes. But, it has many shortcomings due to particle reattachment and frequent bag rupture. In recent years, rectangular type bag filter system has been developed to overcome the problems associated with the cylindrical system. However, not many studies about the rectangular system were not done, compared to the cylindrical system. In this study, the optimum pulse jet cleaning conditions were thus tested by the series of experiments. The factors tested in this study are pulse distance, pulse pressure, pulse duration, the number of holes for pulsing and bag materials. A single bag (1,500mmL×50mmW×300mmH) system and a multi-bags (3 bags in a row) were tested separately. The highest removal efficiency with a single bag system was found at the conditions with pulse distance of 10cm, pulse pressure of 3kg/cm2,pulse duration of 0.3s, pulse jet number of 6 and Polyester bag. With the multi-bags system, the best cleaning conditions were found at the bag interval of 20cm with the simultaneous pulsing and the bag interval of 15cm with the serial pulsing.