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.

사각형 여과 집진기 충격기류 탈진시스템의 기초 연구

박승욱 ( Cheng Xu Piao ),김태형 ( Tae Hyeung Kim ),양준호 ( Jun Ho Yang ),이효우 ( Xiao Yu Li ),하현철 ( Hyun Chul Ha ),정재훈 ( Jae Hun Jung ) 한국산업위생학회 2008 한국산업보건학회지 Vol.18 No.2

Bag-filter system has been widely used in industrial field to remove the particulate matters from the exhaust gas. The cylindrical type of bag-filter has been generally used. But it has many shortcomings. The reattachment of separated particles on the surface of bags could result in high pressure drop of bag-filter system and subsequent decrease of air flow rate since the cylindrical type bag-filter system should have the upward flow pattern. In addition, the supply of very high pressure pulse air jet to remove particulate matters on the surface of filter could result in a frequent rupture of bags. To overcome these shortcomings of the cylindrical type, the rectangular type was developed in the developed countries and imported to Korea. But, there was not many design data available to understand the mechanisms. Thus, the fundamental experiments were conducted in this study to get some ideas about the pulse jet cleaning of rectangular type bag filter system. The experimental factors are as follows; pulse distance, pulse duration, pulse interval, pulse pressure and pulse nozzle type. Experiments followed the factorial design method. With the shorter pulse distance, the distribution of pressure drops was relatively not uniform while the particulate removal efficiency was higher. With the longer duration of pulsing and the more number of pulse nozzle, the removal efficiency was higher and the pressure drop distribution was more uniform.

자연환기용 공장창호의 빗물유입 저감대책에 관한 실험적 연구

박승욱 ( Cheng Xu Piao ),김태형 ( Tae Hyeung Kim ),하현철 ( Hyun Chul Ha ),허영빈 ( Rong Bin Xu ) 한국산업위생학회 2010 한국산업보건학회지 Vol.20 No.3

Windows are widely used for natural ventilation of the various buildings. Especially high level windows as a part of industrial ventilation systems, play a crucial role in natural ventilation. Compared to mechanical ventilation system, natural ventilation has the advantage of lower installation and operating costs. In general, high level windows for industrial buildings have three types; louver type, 45° open type and 90° open type. Based on previous studies, it was found that the louver type and 45° open type are very effective in reducing rainwater penetration, but they did not have enough ventilation efficiencies. Preliminary tests were performed with the various types of windows. It was found that a 90˚ open double layer type window was the best among those which tested in our preliminary tests. Simulated rain was used to estimate the amount of rain penetrated through windows and to observe the paths of rain penetration. Various 90˚ open windows were tested to find the windows with minimum rain penetration and maximum ventilation efficiency.

카트리지 필터 여과집진기 충격기류시스템의 최적탈진조건에 관한 실험적 연구

박승욱 ( Cheng Xu Piao ),하현철 ( Hyun Chul Ha ),김성준 ( Sung Joon Kim ) 한국산업보건학회 2015 한국산업보건학회지 Vol.25 No.4

Objectives: Many types of dust collector are used for industrial ventilation, with the most common types being the cylinder bag filter system, rectangular bag filter system and cylinder type cartridge filter system. The cylinder type cartridge bag filter, which has more filtering area than other types of bag filter, can increase the pulse time and extend the useful lifeof the filter. This can save operational costs and installation area. Materials: This study used cylinder type cartridge bag filter equipment and tested the impact of vibration level and filter pressure with different pulse jet cleaning conditions. The final, cleaning efficiency was calculated through input dust mass and cleaning dust mass Conclusions: Two optimum cleaning condition groups were found. The first condition group was 3 kgf/cm2 pulse pressure, 15 cm pulse distance, 0.2 s pulse time with an H-10 type nozzle. The second condition group was 3 kgf/cm2 pulse pressure, 15 cm pulse distance, 0.3 s pulse time with an H-10 type nozzle.

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.

공장창호의 환기특성에 관한 연구

박승욱 ( Cheng Xu Piao ),김태형 ( Tae Hyeung Kim ),하현철 ( Hyun Chul Ha ),허영빈 ( Rong Bin Xu ) 한국환경과학회 2011 한국환경과학회지 Vol.20 No.5

Industrial natural ventilation systems consist of gravity ventilator, the high/low windows and doors. Especially, the high windows play an important role in the industrial natural ventilation systems. Generally speaking, industrial high windows are divided into 3 types; louver type, 45° open type and 90° open type. This study was numerically and experimentally conducted. Three types of windows were tested to know the ventilation characteristics and estimate the ventilation efficiencies. Numerically, computational fluid dynamics software (AIR PAK Ver. 2.0) was used to observe the flow characteristics inside the industrial building and the concentration contours generated by the tracer gas method. Experimentally, the flow visualization technique and the tracer gas method were applied with the model building to characterize the flow pattern inside the model building and to estimate the ventilation efficiencies with the different windows. It was found that 90° open type window was most effective for the discharge of pollutants from the industrial building. On the other hand, the louver type window was found to be less effective than any other windows.

주물공정 악취·분진 동시 처리를 위한 여과 집진장치 개발연구

허영빈 ( Rong Bin Xu ),김태형 ( Tae Hyeung Kim ),하현철 ( Hyun Chul Ha ),박승욱 ( Cheng Xu Piao ) 한국환경과학회 2014 한국환경과학회지 Vol.23 No.8

Foundry has an important economic value in the industry. However, the generation of air pollutants like particulate and odor are serious. Due to the unavoidable usage of molding sand, particulate occurs in almost all the processes. That accounts for the majority of respirable dust in the size less than 10 ㎛. As well as particulate, over 22 species of odor-causing gases and VOCs including hydrogen sulfide and ammonia are occurred. Therefore, the development of equipment that can simultaneously remove TVOC and particulate is regarded as an essential research. In this study, the spraying absorbent system was connected with the shear bag filter for the purpose to remove TVOC and particulate simultaneously. Maximization of process efficiency for the affective factors like the powder combination and injection method is conducted. The experiment was performed at the de-molding process of one foundry plant. Through these devices, the removal efficiency of more than 95% for TVOC was achieved with the absorbent that composed by 800 mesh Activated carbon (80%) and 300 mesh zeolite (20%). Also, the durability and economic evaluation were assessed. In the result of Durability assessment, the available recovery to maintain the deodorizing effect at 90% was counted to 350 degree.

밀폐공간 질식재해 자료 분석을 통한 질식재해 요인 분석 (2005-2015)

이정완 ( Jung Wan Lee ),김태형 ( Tae Hyeung Kim ),하현철 ( Hyun Chul Ha ),박승욱 ( Cheng Xu Piao ),안광석 ( Kwangseog Ahn ) 한국산업보건학회 (구 한국산업위생학회) 2016 한국산업보건학회지 Vol.26 No.4

Objectives: Despite recent efforts to prevent suffocation disasters, a number of confined space accidents still happen and each year deaths continue to occur. There have been insufficient studies on the dangers of various potential disaster sites, such as manholes, septic tanks, reactors, and other tanks according to type, characteristics, task-specific disasters, equipment specific disasters, etc. The purpose of this study was to analyze recent suffocation disasters based on place and properties. Methods: In this study, we analyzed confined space accident cases from 2005 to 2015 in Korea and grouped them by type, size, monthly occurrence, continuous service period, accident location, person-specific group, age, employment, structural work and subcontracting work. We studied examples of accidents developed in other countries. Results: (1) We reviewed confined-space accident statistics, compared legal standards and analyzed cases of suffocation accidents in the United States and Japan. (2) Using a case study report from the Korea Occupational Safety & Health Agency, we specified confined-space accident statistics based on place, person-specific group, age, employment, structural work and subcontracting work. As a result we generated some precautions about confined-space accidents for the prevention of such accidents. Conclusions: Conclusions: Statistical analysis of recent suffocation disaster cases was performed to establish improvement measures, compare practices from developed countries, and develop precautionary measures accordingly. In this study, we presented the causes of disaster that occur in a confined space and proposed related preventive measures.

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.

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.