• Proceedings of the Korean Society of Soil and Groundwater Environment Conference
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• 2003.04a
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• pp.283-286
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• 2003

국내의 12개소 저산출 우물을 대상으로, 외국의 유정들에서의 산출량 증대를 위하여 많이 사용되고있는 인공수압파쇄 방법을 적용하여 산출성 증대 효과를 검증하였다. 12개소에 대하여 수압파쇄시험 전후로 양수 시험을 실시하여 투수성 증대 등의 효과와 비양수량을 정량적으로 평가한 결과, 비양수량의 경우 전체적으로 평균 약 45%의 증가하였으며 투수량계수 또한 약 26%가 증가하였다. 이러한 결과는 인공수압파쇄 방법이 대수층내 열극의 생성 혹은 확장 및 균열내의 막힘(clog) 물질 제거를 통해 투수성을 상당히 개선시킨 것으로 평가된다. 특히, 현재까지의 시험 결과, 퇴적암류 지역에서 보다 화성암류 지역에서의 시험 결과가 양호하게 나타났다. 화성암 지역에서 개발된 홍천에서의 사례를 볼 때, 고압의 주입을 통하여 상부 및 하부의 파쇄대가 확장 연결되고, 이들 파쇄 열극에 부착된 광물학적, 생물학적 막힘 물질이 제거되면서 산출성이 증대되는 것으로 나타났다.

• Environmental engineer
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• v.24 s.254
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• pp.54-59
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• 2007

본 기술은 각종 산업시설과 환경 기초 시설로부터 대기중으로 배출되는 악취 및 휘발성 유기화합물(Volatile Organic Chemicals; VOC)을 미생물의 분해 작용을 활용하여 제거하는 장치로 오염 물질의 분해과정에서 미생물의 과다생장에 의한 악취 및 휘발성 유기화합물 제거장치의 막힘현상을 미생물 고정화 담체의 교반과 살수과정을 통해 담체표면의 생물막을 효과적으로 제거하는 방법을 이용하여 오염 가스속에 함유되어 있는 악취 및 휘발성 유기화합물을 효율적으로 제거할 수 있는 기술이다. 특히, 미생물 담체의 교반 장치는 미생물 고정화 담체를 교반시켜 생물막을 탈리 시킴으로써 미생물의 생장에 의한 막힘 현상과 이로 인한 압력 손실 증가와 악취 및 휘발성 유기화합물의 제거성능의 저하를 근본적으로 해결할 수 있다.

• Membrane Journal
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• v.29 no.1
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• pp.18-29
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• 2019

The dead-end ultrafiltration (UF) of BSA protein solution was performed to investigate the defouling effects of natural convection instability flow (NCIF) induced in membrane module. The permeate fluxes were measured according to the inclined angles ($0{\sim}180^{\circ}$) of membrane module with respect to gravity, and analyzed using the blocking filtration model. NCIF are more induced as the inclined angles increased from $0^{\circ}$ to $180^{\circ}$, and the induced NCIF enhances flux. Comparing the fluxes at $0^{\circ}$ inclined angle (no NCIF induction) and $180^{\circ}$ (maximum NCIF induction), the flux enhancements by NCIF induction are increased about 5 times in the short-term UF operation (2 hours) and about 17 times in the long-term operation (20 hours). As applying the blocking filtration model, it is more suitable to analyze the flux results by using the intermediate blocking model in the early times of UF operation within 15 minutes and then thereafter times by using the cake filtration model. NCIF induced at $180^{\circ}$ inclined angle reduces the intermediate blocking fouling at about 67% in the early times operation and thereafter the cake layer fouling at about 99.9%. The main defouling mechanism of NCIF induced in the membrane module is suppress the formation of protein cake layer.

• Membrane Journal
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• v.29 no.6
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• pp.329-338
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• 2019

The constant-pressure and constant-flux membrane filtration experiments of alumina colloidal solution are performed to investigate defouling effect of the natural convection instability flow (NCIF) induced in membrane module. The permeate flux at constant-pressure and the transmembrane pressure (TMP) at constant-flux experiments are measured by changes the inclined angle (0, 90 and 180°) of membrane module to the gravity, and flux results are analyzed by using the blocking filtration model. NCIF are more induced as the inclined angles increased from 0° to 180°, and the maximum induced NCIF at 180° angle enhances flux to 2.8 times and reduces TMP to 85% after two-hour operation. As a result of analyzing flux data by applying the blocking filtration model, it is more reasonable to analyze them by using the intermediate blocking model within 15-minute operation time and then thereafter times by using the cake filtration model. The induced NCIF at 180° angle reduces the intermediate blocking fouling at 52% in the early operation time of 15-minute and thereafter the cake layer fouling at 93%. The main membrane fouling control mechanism of NCIF induced in membrane module is evaluated as suppressing the formation of the cake layer of particulate colloidal materials on membrane surface.

• Journal of the Korean GEO-environmental Society
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• v.14 no.1
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• pp.43-51
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• 2013

Recently, engineering problems such as long-term settlement, differential settlement, and the resultant structural damage, have been frequently reported at construction sites. Use of Sand Compaction Piles(SCP) and Granular Compaction Piles(GCP) are good at remedying existing problems, improving bearing capacity and promoting consolidation. However, such compaction piles have the potential for clogging, which would limit their usability. Investigations into the potential for clogging in SCP, GCP, and GCP mixed with sand has not been thoroughly conducted and is the objective of this current study. Large scale direct shear tests were performed on sections of SCP, GCP, and sand mixed GCP to evaluate bearing capacity. Discrete Element Method analyses were conducted with PFC3D and Finite Element Analyses were conducted with MIDAS GTS to propose an algorithm to help reduce clogging in the granular compaction piles. Results from the large scale direct shear test and multiple simulations suggest a 70% gravel and 30% sand mixing ratio to be optimal for bearing capacity and reducing clogging.

• Journal of Korean Society of Environmental Engineers
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• v.28 no.2
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• pp.207-215
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• 2006

This study evaluated the effect of ultrasonic irradiation on reducing membrane fouling for the treatment of chemically treated leachate and biologically treated leachate. The experiments on improvement of membrane flux according to the membrane types(MF and UF) and membrane materials were performed with changing frequency(40 kHz and 120 kHz) and intensity(200 W and 400 W) of ultrasound in ultrasonic membrane separation apparatus which ultrasound can be periodically irradiated. Additionally, the effect of dual frequency ultrasound which 40 kHz md 120 kHz are irradiated simultaneously was evaluated. The improvement of membrane flux by periodical ultrasound irradiation was higher in microfiltration(MF) membrane than in ultrafiltration(UF) membrane. It was sustained more in the MF membrane of polyvinylidene fluoride(PVDF) than in that of polysulfon(PS). Ultrasonic improvement of membrane flux was different depending on the characteristics of target wastewater. It was sustainably maintained without reclogging using dual frequency ultrasound although the improvement of membrane flux was lower.

• Membrane Journal
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• v.15 no.1
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• pp.52-61
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• 2005

Permeate flux decline in a microfiltration was analyzed by measuring the permeability of bentonite colloidal solution through polyethylene capillary membranes. The flux decline with time was due to the growth of cake layer on the membrane surface and to the pore blocking by particles. As the time approaches to steady state, the permeate flux is almost controlled by the cake filtration model. Faster flux decline at high trans-membrane pressure was attributed to the formation of denser packed cake layer and pore blocking. The ratio of permeate flux to the initial permeate flux, J/J₁, decreased with increasing the trans-membrane pressure, from 45% for 0.5 kg/sub f//㎠ to 38% for 2.0 kg/sub f//㎠. In comparing the ratio of each fouling component to the total fouling for the 0.5 kg/sub f//㎠ TMP condition, complete blocking was 23.4%, standard blocking was about 14.6% and cake filtration was 62.0%, respectively. Permeate flux through the membrane increases with cross flow velocity, and the effect of the variation of velocity is more significant at 1.0 kg/sub f//㎠ rather than at 2.0 kg/sub f//㎠ of the operation pressure. Permeate flux for the membrane having the average pore diameter of 0.34 ㎛ was higher than that for the membrane of 0.24 ㎛ pore size, with the higher flux with the low concentration of feed. On the operation using the membrane of 0.34 ㎛ pore, the pore blocking in the low concentration of 200 ppm is negligible relative to the pore blocking in the 1000 ppm feed.

• Journal of the Korean Institute of Gas
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• v.8 no.1 s.22
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• pp.7-12
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• 2004

In the quality control of the aerosol skincare products containing powders, it is essential to guarantee that the contents in the bottle can be completely used without leakage or clogging of the nozzle. In this paper, the clogging caused by powder was investigated and the clogging can be effectively removed by emulsifying the contents containing powder with the LPG using a proper surfactant. And the spraying test shows that the contents in the bottle are completely propelled to outside by LPG when properly emulsified by POE(40) HCO.

• Resources Recycling
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• v.31 no.6
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• pp.36-43
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• 2022

The general screen used to separate the particle size of recycled aggregate has restrictions when dealing with moisturized materials because of the blockage phenomenon. Therefore, in this study, to improve the separation efficiency of the conventional screen, the excellence of additional vibrating device based on spring was decided by a simulation experiment based on the discrete element method (DEM). The motion characteristic was investigated by analyzing the displacement, amplitude, and strain angle based on the spring design. Further, the particle motion was simulated by applying spring motion. The material flow and separation efficiency of the screen applied spring were confirmed as 9.2 kg/s and 97 %, respectively. Consequently, the improvement in the screen applied with blockage prevention spring was confirmed by comparing with the conventional screen.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.29 no.1 s.232
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• pp.139-150
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• 2005

The present study has numerically investigated two-dimensional laminar flow over a circular cylinder with a uniform planar shear, where the free-stream velocity varies linearly across the cylinder. Numerical simulations using the immersed boundary method are performed for the ranges of $50{\le}Re{\le}160,\;K{\le}0.2$, and B=0.1 and 0.05 where Re, K and B are the Reynolds number, the non-dimensionalized velocity gradient and the blockage ratio, respectively. Results show that the flow depends significantly on B as well as Re and K. It is found, especially, that the blockage effect accounts for some causes of apparent discrepancies among previous studies on the flow. With increasing K, the vortex shedding frequency and the mean drag stay nearly constant or slightly decrease whereas the mean lift, acting from the higher-velocity side to the lower, increases linearly. Flow statistics as well as instantaneous flow fields are presented to identify the characteristics of the flow and then to understand the underlying mechanism.