• Membrane Journal
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• v.16 no.1
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• pp.51-58
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• 2006

The permeation experiments were carried out for the submerged membrane module equipped with self-designed rotating disks in order to determine the effect of fouling reduction and the optimum operating conditions as a function of operating time. Kaolin and bentonite particles were used to prepare various concentrations of feed solution. Every experiment was continued until 60 minutes at various rotating disk speeds up to 120 rpm. The suction pressure for kaolin solutions decreased to 28% by using rotating disk to decrease the fouling. Also, the optimum permeation flux decreased as kaolin concentration increased, and became 60 to 70 LMH for 0.4 wt% of kaolin solution. The suction pressure for bentonite experiment approached to 0 mmHg at 30 LMH and above 80 rpm rotating disk speed.

• Membrane Journal
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• v.29 no.4
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• pp.216-222
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• 2019

In this study, permeation experiments were conducted using naturally circulating spherical beads, backwashable plate membrane and the air supplied from the bottom of the MBR. The activated sludge solution was maintained at 8,000 mg/L of MLSS and compared transmembrane pressure (TMP) with respect to FR (filtration and relaxation), FR/BW (filtration and relaxation/backwashing), SFCO (sinusoidal filtration continuous operation) and SFCO/BW (sinusoidal filtration continuous operation/backwashing). As the backwashing flux decreased from 47 to $14L/m^2{\cdot}hr$, the TMP increased generally, but the TMP of FR system increased significantly comparing with SFCO. In addition, the backwashing method reduced more TMP comparing to the cleaning method using spherical beads, and it was confirmed that the operation method using the spherical beads and the backwashing simultaneously is more effective than each method.

• Journal of Korean Society of Water and Wastewater
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• v.17 no.4
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• pp.559-566
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• 2003

From this research, the performances of a sludge reduction in the sewage sludge aerobic digestion was experimented by using a sludge pretreatment and membrane bioreactor. The submerged plate membrane was used as the solid-liquid separation membrane. After drawing small amounts of sludge in a bioreactor and then doing the alkaline treatment and ozone treatment, the sludge was sent to back to the reactor. The HRT in the reactor was set as 5 days and the operation in the reactor was carried out at the DO of 1mg/L on average. After 100 days of operation in the reactor, it was shown that the reduction efficiency of total solids was more than 83%. Most of volatile solids were removed through mineralization, and the considerable portion of the non-volatile solids was dissolved and then flowed out with the effluent. Only about 16.3% of total solids in the sludge was accmulated in the reactor even without the loss of volatile fraction. Also, by deriving nitrification and denitrification in one reactor simultaneously, more than 90% of nitrogen removal effect was realized and the experiment was run smoothly without fouling of membrane, even in the high concentration of MLSS. Based on this experiment, sludge can be reduced considerably at a low HRT by these two newly suggested approach.

• Journal of Welding and Joining
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• v.13 no.3
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• pp.8-17
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• 1995

LNG를 저장할 수 있는 탱크는 주로 지상식이거나 반지하식이며 그 용량은 매우 다양하다. 우리나라에서는 지상식 탱크가 평택 인수기지에 10만m$^{3}$급 Membrane Type 6기가 건설되었고 1기는 거의 완성단계이며, 현재 추가로 건설 중인 3기를 포함하면 총 10기의 탱크를 확보하게 된다. 또한 제2인수기지인 인천에도 동급 으로서 9%Ni강을 사용하는 Double Wall Type LNG 탱크 3기를 건설 중이다. 전세계적 으로 볼 때 LNG 저장 탱크의 78%는 지상식으로 Double Wall Type 또는 Membrane 저장 탱크 형식을 취하고 있으나, 최근에는 안전성 측면, 토지 가격의 상승, 토지의 합리적 이용 측면 등을 감안하여 LNG 탱크를 지하화, 대형화하는 추세이다. 본고에서는 Fig. 1과 같은 구조의 Double Wall Type LNG 저장탱크 중 초저온의 LNG에 직접 접하는 저 온용 재료(9%니켈강)로 만들어지는 내조 용접에 대해서 중점적으로 논하기로 하며, 특히 9% 니켈강 Shell Plate Horizontal Joint에 채용되는 Automatic Submerged ARC 용접에 대해 실제 현장 용접 시공상태를 나타내고자 한다.

• Membrane Journal
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• v.15 no.2
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• pp.114-120
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• 2005

The purpose of this study is to obtain practical information about membrane coupled $ A_2O$ system for muncipal wastewater treatment. A flat-plate microfiltration (MF) module with a pore size $0.25\;{\mu}m$ was submerged into the aeration basin and treated water was filtrated through the membrane by continuous suction with low pressure. The system was operated with synthetic wastewater to find operational parameters of internal recycle ratio and maximum MLSS showing best water quality and long-term stability. The internal recycle was defined as type 1 for aerobic to anoxic tank and type 2 for anoxic to anaerobic tank, respectively When the flux was maintained at $0.015\;m^3/m^2/hr$ (15 LMH) with 2Q type 1 internal recycle ratio, the optimal operational setting were 10 internal recycle ratio for type 2 and maximum MLSS of 11,000 mg/L among tested conditions. At this condition, removal efficiencies of BOD, CODcr, T-N and T-P showed $97.3\%,\;94.2\%,\;64.0\%,\;63.0\%$, respectively.