자유면대수층에서 필터층이 취수량 및 우물효율에 미치는 영향에 대한 실험적 연구

송재용,이상무,최용수,정교철 대한지질공학회 2017 지질공학 Vol.27 No.4

This study evaluated a model unconfined aquifer comprising a sand or gravel layer, a filter layer, a pumping well, and an observation well. The model was employed in step drawdown tests and then used to assess the permeability of each test tank. The optimal yield and well efficiency were then calculated. Evaluation of yield by step in sand layer filters of equal thickness gave optimized watering rates of 22.03 L/min in the double filter and 19.71 L/min in the single filter. The double filter’s yield was 115.0% that of the single filter. A comparison of double and single filters, each 10 cm thick, showed the double filter to have a maximum yield of 182.7%. Yields for the gravel layer were 73.56 L/min for a double filter and 65.47 L/min for a single filter of the same thickness; the former value is 112.3% of that of the latter. Comparison of double and single filters with 10-cm-thick gravel layers revealed that the double filter had a maximum yield of 160.9%. Results for sand wells showed the double filter to have a maximum efficiency of 70.4% and the single filter to have a minimum efficiency of 37.1%. Gravel-layer well efficiencies were >66.5% for both double and single filters (each 30 cm thick), but only 22.5% for a 10-cm-thick single filter. This study confirms that permeability improved as the filter material became thicker; it also shows that a double filter has a higher yield and well efficiency than a single filter. These results can be applied to the practical design of wells. 본 연구는 자유면대수층 즉, 충적대수층에서 필터층의 영향을 평가하기 위하여 수행하였다. 시험을 위해 모래층 및 자갈층으로 구성된 충적대수층에 필터층, 양수정, 관측정을 각각 설치한 모형시험장치를 제작하였다. 제작된 모형시험장치를 이용해 단계양수시험을 수행하였으며, 각 시험조별 투수특성을 확인하고 적정양수량 및 우물효율을 산정하였다. 모래층에서 단계별 양수량 분석을 통한 적정양수량 평가결과, 동일한 필터 두께를 가진 경우 이중필터는 22.03 L/min이며, 단일필터는 19.71 L/min로단일필터에 비해 이중필터가 115.0% 양수량이 증대되는 것으로 평가되었다. 이중필터와 필터층 두께가 10 cm인 단일필터와 비교하면 이중필터에서 182.7%의 양수량 증대효과가 있는 것으로 분석되었다. 자갈층의 적정양수량 평가결과, 동일한 필터 두께를 가진 경우 이중필터는 73.56 L/min이며, 단일필터는 65.47 L/min로 단일필터에 비해 이중필터가 112.3% 양수량이 증대되는것으로 평가되었다. 이중필터와 자갈층에서 필터층 두께가 10 cm인 단일필터를 비교하면 이중필터에서 160.9%의 양수량 증대효과가 있는 것으로 분석되었다. 모래층 우물효율을 분석한 결과 이중필터에서 최대 70.4%, 단일필터에서 최소 37.1%를 보이며, 자갈층에서는 필터재 두께가 30 cm인 이중필터와 단일필터에서 66.5%의 높은 우물효율을 보이나 필터재 두께가 10 cm인단일필터에서는 22.5%로 낮게 평가되었다. 본 연구를 통해 필터재가 두꺼울수록 투수특성이 개선되는 것을 확인하였으며, 이중필터가 단일필터에 비해 양수량 및 우물효율이 상대적으로 높은 것으로 평가되었다. 이와 같은 결과는 우물설계에 실질적으로 활용이 가능할 것으로 판단된다.

Mattress/Filter 채움재의 공극률에 따른 하천수질 개선효과

고진석(Ko Jin Seok),이승윤(Lee Sung Yun),허창환(Heo Chang Hwan),지홍기(Jee Hong Kee) 대한토목학회 2006 대한토목학회논문집 B Vol.26 No.1B

산업활동으로 인해서 발생하는 제강슬래그와 최근 선진국에서 환경개선 및 오염방지를 위한 용도로 활용하고자 활발히 연구되고 있는 제올라이트 등의 다공성 재료를 오염된 하천의 정체수역에 설치하여 저비용으로 수질을 개선시킬 수 있는 기법은 폐기물의 재이용 측면과 하천수질개선 측면에서 매우 필요하다. 현재 제철소에서 발생하는 부산물인 제강슬래그의 화학적 성분은 주로 CaO, SiO₂, Al₂O₃, Fe₂O₃ 등으로 이루어져 있으며, 침전유발물질 및 흡착성물질이 함유되어 있다. 제강슬래그는 다공질 형태의 비표면적을 가지고 있어서 정화용 필터나 흡착재로 이용하기에 좋은 이점을 지니고 있다. 그리고 제올라이트는 양이온 교환특성, 흡착특성, 촉매특성, 탈수 및 재흡수특성 등의 이점을 지니고 있어서 축산농가의 환경개선, 도시의 생활하수의 처리, 공업폐수 처리, 음료수 수질개선, 방사성폐기물 처리 및 방사성 물질의 오염방지 등에 응용되고 있다. 그러므로 제강슬래그나 제올라이트를 Mattress/Filter의 채움재 및 수질정화용 여재로 활용함으로써 수질개선 등 효과를 동시에 얻을 수 있다. 본 연구에서는 제강슬래그와 제올라이트가 정체수역에 설치되는 Mattress/Filter시스템의 채움재로 활용할 때 공극률에 따른 수질개선효과를 파악하기 위하여 공극률을 38.6%인 p1, 45.8%인 P2 및 49.8%인 P3로 변화시켜 각각의 유입수와 유출수의 pH, DO, T-N, T-P 등을 측정하여 비교하였다. 수질개선에 사용된 Mattress/Filter시스템은 오염된 하천수가 Mattress/Filter시스템의 공극사이를 통과하면서 채움재에 형성된 다공질에 의한 여과작용과 생물막에 의한 접촉작용, 흡착작용 및 생물분해작용 등을 촉진시키는 기능을 가지고 있음을 알 수 있었다. 제강슬래그 및 제올라이트를 채움재로 사용한 Mattress/Filter 시스템은 쉽게 생물막을 형성시키고 유기물의 흡착을 촉진시켜 오염물질을 정화하는데 필요한 자정작용의 효과를 증대시키고 수질개선을 촉진시킬 수 있는 자연환경에서 하천정화에 이용될 수 있는 시스템임을 확인할 수 있었다. Water quality improvement in mattress/filter system using porous material like slag from industrial activity and zeolite that has been studied for environment improvement and pollution abatement is very useful in polluted stagnant stream channel. Slag is consisted of CaO, SiO₂, Al₂O₃ and Fe₂O₃. Slag with large specific surface area of porosity has been used such as sludge settling and adsorptive materials. Because slag is porous, it can be used for purification filter. As slag is used as filled materials of mattress/filter system and the system has good advantages for the waste water treatment, water recycling, and the improvement of water quality at the same time and so on. Because zeolite has much advantage of cation exchange, adsorption, catalyst and dehydration characteristics, It is used for environment improvement of livestock farms, treatment of artificial sewage and waste water, improvement of drinking water quality, radioactive waste disposal and radioactive material pollution control. In this study, according to verifying effects of water quality improvement of fill materials by porosity that 38.6%, 45.8% and 49.8% respectively in the stagnant stream channel, water quality monitoring of inflow and outflow was conducted on pH, DO, BOD, COD, SS, T-N and T-P. Mattress/filter system was able to accelerate water quality improvement by biofilter as waste water flows through gap of mattress/filter fill materials and by contact catalysis, absorption, catabolism by biofilm. Mattress/filter system used slag and zeolite forms biofilm easily and accelerates adsorption of organic matter. As a result, mattress/filter system increases water self-purification and accelerates water quality improvement available for stream water clean-up.

Computed Radiography에서 Additional Filtration Material에 따른 Radiation Dose와 Image Quality의 변화

권순무(Soon-Mu Kwon),조형욱(Hyung-Wook Cho),강영한(Yeong-Han Kang),김부순(Boo-Soon Kim),김정수(Jung-Su Kim) 대한방사선과학회(구 대한방사선기술학회) 2014 방사선기술과학 Vol.37 No.4

필터는 저에너지 X선을 흡수함으로써 평균에너지를 증가시키고, 환자의 피폭선량을 감소시키는 작용을 한다. 본 연구는 Mo과 W 등의 재질이 디지털 방사선영상장치인 CR에서도 사용이 가능한지 SNR, FOM, histogram 등의 영상평가와 선량 측정을 통해 확인하였다. 또한 필터의 재질에 따른 선질측정과 함께 관전압의 변화에 따른 적합한 필터 조합을 찾아보았다. 피부입사선량은 Mo필터가 Cu필터에 비해 42~56%까지 선량 경감효과가 있었고, 투과선량도 Mo필터가 Cu필터보다 1.5배 정도 높게 나타났다. 영상 평가에서 W은 필터로 사용함에 부적절하였으나, Mo은 80 kVp 이상의 관전압에서 영상의 질을 저하시키지 않으면서 선량을 감소시킬 수 있는 필터로 충분히 사용할 수 있음을 확인하였다. 2.0 mmAl+0.1 mmMo은 관전압이 높아질수 록 2.0 mmAl + 0.2 mmCu와 histogram width가 거의 같아서, 비교적 높은 관전압인 80, 100, 120 kVp에서는 Mo필터의 사용이 가능하다. 2.0 mmAl + 0.1 mmMo의 SNR은 2.0 mmAl + 0.2 mmCu와 2.0 mmAl+0.1 mmCu 의 SNR과도 큰 차이가 나지 않았다. 따라서 디지털 방사선 영상 중 80 kVp 이상을 이용하는 일반촬영에서 Cu를 대신하여 Mo을 필터로 사용하면 Cu에 비해 영상의 질을 저하시키지 않으면서 환자의 피폭선량을 크게 감소시킬 수 있으므로, 실제 임상의 흉부 촬영 및 고관전압 촬영 등에 충분히 적용할 수 있다고 본다. Filter absorbs low-energy X-ray to increase the average energy and reduces patient exposure dose. This study investigates if the materials of Mo and W could be used for the digital imaging device CR by con-ducting image assessment and dose measurement of SNR, FOM and histogram. In addition, measurement of beam quality was conducted depending on the material of the filter, and at the same time, a proper combination of filters was examined depending on the change in tube voltage (kVp). In regard to en-trance skin dose, Mo filter showed the dose reduction by 42∼56%, compared to Cu filter. Moreover, Mo filter showed higher transmission dose by around 1.5 times than that of Cu filter. In image assessment, it was found that W was unsuitable to be used as a filter, whereas Mo could be used as a filter to reduce dose without decline in image quality at the tube voltage of 80 kVp or higher. As tube voltage increased, 2.0 mm Al+0.1 mm Mo almost had a similar histogram width to that of 2.0 mm Al+0.2 mm Cu. Therefore, Mo filter can be used at relatively high tube voltage of 80 kVp, 100 kVp and 120 kVp. The SNR of 2.0 mm Al+0.1 mm Mo did not show any significant difference from those of 2.0 mm Al+0.2 mm Cu and 2.0 mm Al+0.1 mm Cu. As a result, if Mo filter is used to replace Cu filter in general radiography, where 80 kVp or higher is used for digital radiation image, patient exposure dose can be reduced significantly with-out decline in image quality, compared to Cu filter. Therefore, it is believed that Mo filter can be applied to chest X-ray and high tube voltage X-ray in actual clinical practice.

Filter- and Denuder-Based Organic Carbon Correction for Positive Sampling Artifacts

황인조,나광삼 한국대기환경학회 2017 Asian Journal of Atmospheric Environment (AJAE) Vol.11 No.2

This study describes (1) the impact of positive sampling artifacts caused by not only a filter-based sampling, but also a denuder-based sampling in the determination of particle-phase organic carbon (POC), (2) the effect of sample flow rate on positive artifacts, and (3) an optimum flow rate that provides a minimized negative sampling artifact for the denuder-based sampling method. To achieve the goals of this study, four different sampling media combinations were employed: (1) Quartz filteralone (Q-alone), (2) quartz filter behind quartzfiber filter (QBQ), (3) quartz filter and quartz filter behind Teflon filter (Q-QBT), and (4) quartz filter behind carbon-based denuder (Denuder-Q). The measurement of ambient POC was carried out in an urban area. In addition, to determine gas-phase OC (GOC) removal efficiency of the denuder, a Teflon filter and a quartz filter were deployed upstream and downstream of the denuder, respectively with varying sample flow rates: 5, 10, 20, and 30 LPM. It was found that Q-alone sampling configuration showed a higher POC than QBQ, Q-QBT, and Denuder- Q by 12%, 28%, and 23%, respectively at a sample flow rate of 20 LPM due to no correction for positive artifact caused by adsorption of GOC onto the filter. A lower quantity of GOC was collected from the backup quartz filter on QBQ than that from Q-QBT. This was because GOC was not in equilibrium with that adsorbed on the front quartz filter of QBQ during the sampling period. It is observed that the loss of particle number and mass across the denuder increases with decreasing sample flow rate. The contribution of positive artifacts to POC decreased with increasing sample flow rate, showing 29%, 25%, and 22% for 10, 20, and 30 LPM, respectively. The 20 LPM turns out to be the optimum sample flow rate for both filter and denuderbased POC sampling.

여과재 표면처리 방식에 따른 백필터의 탈진 및 먼지배출 특성

박현설,김동수,조희주,심준목,Zainul Alim Ali Murtadlo,조철희 한국대기환경학회 2022 한국대기환경학회지 Vol.38 No.6

This study was conducted to investigate the effect of surface treatment of filter media on the performance of bag filters. To this end, four bag filters were prepared using the different filter media made by four different surface treatment methods. Both surface and cross-sectional structures of each filter medium were examined, and the basic filtration properties of the filter media were tested. Based on the test results of the filter media, the cleaning and dust emission performance of each bag filter was evaluated using a bag filter test unit, followed by repeated filtration-cleaning cycles under dust loading conditions. As a result, the bag filters made of calendered and singed filter media with low pressure drop had cleaning intervals 3 times longer than bag filters made of membrane-laminated media. The singed filter bag, whose medium has a very porous inner structure, showed a very high concentration of dust emission which is 10 times higher than those of other bags. In addition, for the membrane-coated filter media, the pore structure of the membrane greatly affected the pressure loss of the filter media and the cleaning performance of bag filters. Among the filters tested in this work, the bag filter made of the calendered filter medium showed the best performance in terms of cleaning interval and dust emission due to the characteristics of surface and cross-sectional structure of the medium.

충적우물에서 필터층 변화에 따른 투수특성, 적정양수량 및 장기적 안정성에 대한 연구

송재용,이상무,최용수,김기준,정교철 대한지질공학회 2018 지질공학 Vol.28 No.1

This study was carried out to evaluate the effects of various filter conditions on unconfined aquifer (alluvial aquifer). We made model test device which has filter layer, pumping well and observation well which consist of sand layer and gravel layer to test. Step drawdown test and long term pumping tests were carried out using the device. The permeability characteristics of each test group were confirmed and the optimal yield was calculated. As a result of comparing the optimal yield of double filter and single filter in sand, dual-filter SD-300 was valued at 216.8 % higher final optimal yield than singlefilter SS-300. Comparing the dual filter SD-300 and the single filter SS-100 with a thin filter layer, dual-filter SD-300 was valued at 709.2% higher final optimal yield than single-filter SS-300. As a result of analysis of optimal yield change over time, It was confirmed that the ratio of optimal yield of single filter and dual filter increase over time. In order to evaluate the long-term change in water intake efficiency, we considered the point at which the initial optimal yield was reduced by 50%. The dual filter SD-300 is about 351.1% higher than SS-300, which is the same thickness filter, and about 579.0% higher than SS-100. From these results, Assuming that the point at which the initial quantity of water intake is reduced to 50% is the well life, double filters are expected to increase their lifespan by about 3.5 times over single filters of the same thickness and by about 5.8 times over typical single filter. These results can be used to design wells to river bank filtration or filtered seawater. In addition, it is possible to clarify the effect of the double filter through the comparison with the future field test results. 본 연구는 자유면대수층 즉, 충적대수층에서 다양한 필터조건에 따른 영향을 평가하기 위하여 수행하였다. 시험을 위해 모래층 및 자갈층으로 구성된 충적대수층에 필터층, 양수정, 관측정을 각각 설치한 모형시험장치를 제작하였다. 제작된 모형시험장치를 이용해 단계 및 장기양수시험을 수행하였으며, 각 시험조별투수특성을 확인하고 적정양수량을 산정하였다. 모래층에서 수행한 이중필터와 단일필터의 적정양수The Journal of Engineering Geology pISSN : 1226-5268 eISSN : 2287-7169 Vol. 28, No. 1, March, 2018, pp. 101-115 https://doi.org/10.9720/kseg.2018.1.101 RESEARCH ARTICLE량을 비교하면, 이중필터인 SD-300은 동일두께의 단일필터인 SS-300에 비해 최종 적정양수량이 216.8% 높게 평가되었다. 이중필터 SD- 300과 필터층 두께가 얇은 단일필터 SS-100을 비교하면, 이중필터인 SD-300은 SD-100에 비해 최종 적정양수량이 709.2% 높게 나타났다. 시간경과에 따른 적정양수량의 변화를 분석한 결과, 이중필터와 단일필터의 적정양수량 비는 시간이 경과할수록 증대됨을 확인하였다. 장기적인 취수효율의 변화를 평가하기 위하여 초기 적정양수량이 50% 저감되는 시점을 검토한 결과, 이중필터인 SD-300은 동일두께 단일필터인SS-300 대비 약 351.1% 높은 값을 보이며, SS-100 대비 약 579.0% 높은 값을 보인다. 이러한 결과를 볼 때, 초기 양수량이 50%로 저하되는 지점을 우물 수명으로 가정하면, 이중필터는 동일두께의 단일필터 대비 약 3.5배, 일반적인 단일필터 대비 약 5.8배의 수명 증대가 예상된다. 이와같은 결과는 강변여과수나 해변여과수를 활용하기 위한 우물설계에 활용될 수 있을 것이다. 또한, 향후 수행될 현장실증시험 성과와의 상호비교를 통해 이중필터 효과에 대한 보다 명확한 규명이 가능할 것으로 판단된다.

디지털 방사선장치에서 흉부검사 시 복합 부가filter 사용의 유용성에 관한 연구

김신구(Shin-Ku Kim),김상현(Sang-Hyun Kim),대창민(Chang-Min Dae),민관홍(Kwam-Hong Min) 대한영상의학기술학회 2016 대한영상의학기술학회 논문지 Vol.2016 No.1

목 적 : 본 연구에서는 디지털 방사선장치에서 흉부검사시 Al과 Cu를 이용한 부가filter의 사용이 영상화질과 선량감소에 미치는 영향을 알아보고 적합한 부가filter의 유용성에 대해 알아보고자 하였다. 대상 및 방법 : X-선 장비를 이용하여 부가filter를 사용하지 않은 상태부터 Al 1mm, 2mm, Cu 0.1mm, 0.2mm, 0.3mm와 Al 1mm와 Cu 0.1mm, 0.2mm, 0.3mm을 각각 더한 filter와 Al 2mm에 Cu 0.1mm, 0.2mm, 0.3mm을 더한 filter에 60kVp 부터 10kVp씩 올려 120kVp까지의 조사선량을 측정하였다. 물리적 평가를 위해 DIGRAD 팬텀으로 ROI 값을 설정하여 SNR과 CNR을 구하고 실제 임상에서의 사용을 위해 Chest Phantom에 Focus-to-Image Receptor Distance(FID)를 180cm로 고정하고 자동노출조건 (Automatic Exposure Control ; AEC)을 이용하여 SNR과 CNR 값을 비교, 분석하였다. 결 과 : 조사선량 측정 결과 부가filter를 사용하지 않은 경우 가장 조사선량이 높았고 Cu 0.3mm + Al 2mm를 사용했을 때 가장 선량값이 낮았으며 부가filter를 사용하지 않은 상태를 제외하고는 Al 1mm에서 선량값이 가장 높았다. DIGRAD phantom을 이용한 물리적 평가에서는 SNR 값은 30.22~35.99로 전체적으로 비슷했으나 60kVp에서는 Al 1mm에서 37.13으로 가장 높았다. 그러나 다른 관전압에서는 모든 filter에서 값이 비슷하게 나타났다. CNR 값은 4.60~7.81로 전체적으로 비슷했으나 관접압이 증가할수록 CNR 값이 낮아졌다. 흉부팬텀을 이용한 영상평가에서는 Lung 과 Heart, Subdiaphragm 모두 Cu filter만 사용했을 때보다 Al을 섞어 사용하였을 때 SNR 이 높은 양상을 보였고, CNR 은 Lung과 Heart 에서는 Al을 제외하고는 kVp가 올라갈수록 값이 낮아졌다. Subdiaphragm에서는 60kVp에서만 값이 높았고, 60kVp를 제외한 나머지 값들은 비슷한 양상을 보였다. 결 론 : 부가filter를 사용하면 우수한 영상화질 얻을 수 있고 환자가 받는 피폭선량 또한 줄일 수 있다. Al 이나 Cu filter의 독립적 사용보다는 Al 과 Cu filter를 적절히 사용하여 관전압, 검사부위에 따라 적절한 부가filter의 두께의 사용이 필요할 것으로 사료된다. Purpose : In this study, when using Al and Cu additional filter which is the one of the methods of dose reduction, evaluated the physical evaluation and the optimization of Chest image. Materials and Methods : Using the X-ray device with a state that does not use an additional filter, Al 1mm 2mm, Cu 0.1mm, 0.2mm, 0.3mm and Al 1mm added Cu 0.1mm, 0.2mm, 0.3mm and Al 2mm added Cu 0.1mm 0.2mm, 0.3mm ,measured the radiation dose up to 120kVp from 60kVp by 10kVp. Using by DIGRAD phantom for physical evaluation, ROI value was set for gaining SNR and CNR compared analyzed the SNR and CNR. Focus-to-Image receptor Distance (FID) is fixed to 180cm and used the automatic Exposure control. Results : In a dosimetry, the result of radiation dose showed the lowest when using Cu0.3mm+Al2mm filter. The radiation dose was the highest when using Al 1mm filter except using non-filter. In a physical evaluation using DIGRAD phantom, the value of SNR had generally similar about 30.22 to 35.99, at 60kVp, it was the highest value 37.13 at Al 1mm. However, in other tube voltage, the values in all the filters become equally apparent. CNR value was 4.60 to 7.81, but showed generally similar. CNR value has dropped whereas tube voltage is increased. When evaluating the image using with the Chest phantom, in Lung, Heart, Subdiaphragm, SNR showed the higher when using Cu + Al than using Cu filter only. In the case of CNR, in Lung and heart the higher the KvP, the lower result has shown. In Subdiaphragm, CNR was high at 60kVp only, except 60kVp, the other results were similar Conclusion : With the additional filter, not only lowering the radiation dose, but also good image quality can be obtained. And the dose the patient received can be reduced. Rather than using Al or Cu filter independently, it is considered to use the appropriate mixed Al and Cu filter in accordance with tube voltage.

필터 종류에 따른 Semi-volatile 화합물 이행 특성

김정열,신창호 한국연초학회 1997 한국연초학회지 Vol.19 No.2

Semivolatile components in mainstream smoke of cigarette attached the different type filter were analysed. Based on the main peak of GC profile, benzene, toluene, acetic acid, limonene, acetamide, pyridine, nicotine, phenol, pyrrole, and furfuryl alcohol were identified. The amount delivered of semivolatile components by each filter was evaluated with the ratio of areas of sample vs area% of ISTD. By comparing dual and triple filter to mono filter, the delivery amounts were 52% benzene, 62% toluene and 74% benzene, 84% toluene, respectively. The delivery amount of limonene which was known of tobacco taste component, were 52%, and 93% by dual and triple filter, respectively. Also, delivery amounts of acetic acid which was one of acidic compounds in smoke, were 86% and 83% by dual and triple filter, respectively. When adding the same amount of active carbon, the amounts delivered of vapour phase such as benzene and toluene by dual filter were lower than that of triple filter. But the delivery amounts of acetic acid and phenol by dual filter were higher than that of triple filter. This results assume that the pH of active carbon in filter affect to the adsorption or absorption of triacetin during filter making process.

Filter- and Denuder-Based Organic Carbon Correction for Positive Sampling Artifacts

Hwang, InJo,Na, Kwangsam Korean Society for Atmospheric Environment 2017 Asian Journal of Atmospheric Environment (AJAE) Vol.10 No.2

This study describes (1) the impact of positive sampling artifacts caused by not only a filter-based sampling, but also a denuder-based sampling in the determination of particle-phase organic carbon (POC), (2) the effect of sample flow rate on positive artifacts, and (3) an optimum flow rate that provides a minimized negative sampling artifact for the denuder-based sampling method. To achieve the goals of this study, four different sampling media combinations were employed: (1) Quartz filter-alone (Q-alone), (2) quartz filter behind quartz-fiber filter (QBQ), (3) quartz filter and quartz filter behind Teflon filter (Q-QBT), and (4) quartz filter behind carbon-based denuder (Denuder-Q). The measurement of ambient POC was carried out in an urban area. In addition, to determine gas-phase OC (GOC) removal efficiency of the denuder, a Teflon filter and a quartz filter were deployed upstream and downstream of the denuder, respectively with varying sample flow rates: 5, 10, 20, and 30 LPM. It was found that Q-alone sampling configuration showed a higher POC than QBQ, Q-QBT, and Denuder-Q by 12%, 28%, and 23%, respectively at a sample flow rate of 20 LPM due to no correction for positive artifact caused by adsorption of GOC onto the filter. A lower quantity of GOC was collected from the backup quartz filter on QBQ than that from Q-QBT. This was because GOC was not in equilibrium with that adsorbed on the front quartz filter of QBQ during the sampling period. It is observed that the loss of particle number and mass across the denuder increases with decreasing sample flow rate. The contribution o f positive arti facts to POC decreased with increasing sample flow rate, showing 29%, 25%, and 22% for 10, 20, and 30 LPM, respectively. The 20 LPM turns out to be the optimum sample flow rate for both filter and denuder-based POC sampling.

단일동조 수동고조파필터 설계시의 동조계수() 및 양호도()값 연구

차한주,조영식 대한전기학회 2010 전기학회논문지 P Vol.59 No.1

This paper presents how to decide on tuning factor() and quality factor() values in design of single-tuned passive harmonic filters. Tuning factor() and quality factor() values have to consider before decision on circuit parameters of passive filters. A Study on these two value has not been scarcely performed and only experienced values has been used in passive harmonic filter design by far. As a experienced value, in cases of 5th and 7th filter, tuning factor() is about 0.94 and 0.96 respectively and quality factor() is, in all cases of, 50. If Single-tuned passive harmonic filter will be off-tuned, performance of filter will be decreased steeply and occur to parallel resonance between system reactance and filter capacitance. Therefore During the operation, In order not to off-tuning, Filter must be tuned at former order than actual tuning order. This is the same that total impedance of filter must have a reactive impedance. In this paper, Tuning factor() is decided via example of real system and using the bode-plot and then performance of filters confirmed by filter current absorbtion rate. And Quality factor() decided using the bode plot in example system and then performance of filters confirmed by filter current absorbtion rate also, which makes a calculated filter parameters to satisfy IEEE-519 distortion limits. Finally, Performance of the designed passive harmonic filter using the tuning factor() and quality factor() values, decided in this paper is verified by experiment and shows that 5th, 7th, 9th, 11th and 13th current harmonic distortions are decreased within IEEE-519 distortion limits, respectively.