• Membrane Journal
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• v.18 no.1
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• pp.7-25
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• 2008

Sodium dodecyl sulfate, which was anionic surfactant, at a concentration higher than its critical micellar concentration was added to calcium solution for forming micelles. Then aggregates were formed by adsorption or binding of calcium ions on the surface of micelles, and gathering between them, and then rejected by two kinds of ceramic membranes to remove calcium ions. As result, rejection rates of calcium were higher than 99.98%. And in our experimental range the higher TMP trended to increase the resistance of membrane fouling ($R_f$), total permeate volume ($V_T$), dimensionless permeate flux ($J/J_o$) and permeate flux (J) because TMP was driving force. And we investigated effects of $N_2$-back-flushing time and filtration time, that was back-flushing period, during periodic $N_2$-back-flushing on ceramic membranes. As result, optimal BTs for NCMT-623l ($0.07{\mu}m$ pore size) and NCMT-7231 membrane ($0.10{\mu}m$) were 10 sec and 15 sec, respectively. Also, optimal FT was 5 min for both membranes, and the frequent $N_2$-back-flushing could decrease membrane fouling effectively. Then, the optimal conditions resulting from our experiments for synthetic calcium solution were applied to groundwater using as washing process of soymilk package. As result, rejection rates of calcium were higher than 99.98%.

• Membrane Journal
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• v.24 no.3
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• pp.201-212
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• 2014

This study was performed to discover the optimum operation conditions for the advanced water treatment using the ceramic membrane, introduced the first in the nation at the Y water treatment plant (WTP). The result of investigation to find the optimum operation conditions which can continue preserving the filtration performance as well as satisfying both the economics and the water quality is as follows. In the ordinary water quality condition of the Y WTP, the optimum filtration time(the backwash period), which can minimize the production of backwash waste and preserve the membrane performance was examined to be 4.0 hours on basis of institution capacity ($16,000m^3/day$). Examining the recovery rate of TMP from the chemical cleaning (CIP) discovered that the inorganic contaminants, which cause membrane fouling, such as iron, manganese, aluminum, were removed through the acidic cleaning using citric acid, whereas the membrane recovery rate was found to be low. But, on the other hand, the TMP was recovered to the initial value from the alkali cleaning using the NaOCl. Therefore, the main contaminant causing the fouling was determined to be hydrophilic organic compound( biopolymer). The membrane recovery rate is highly influenced by the temperature of the cleaning chemical. That is, the rate increased with increasing temperature.

• Membrane Journal
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• v.18 no.3
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• pp.241-249
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• 2008

This study is to concentrate vanadium in Jeju groundwater using reverse osmosis processes, and to utilize the concentrate for vanadium water. Groundwater samples were taken from Wahyul, Ayum, and Seogwipo groundwater wells with different in vanadium content each other. Their vanadiuln concentrations were 31.8, 44.5, and 53.0 ppb, respectively. The rejection coefficients of every component in groundwater were increased with the increase of TMP At the TMP of $8 kg_f/cm^2$, the rejection coefficients of vanadium, sodium, potassium, aluminium, iron, and barium were $97.4%{\sim}99.0%,\;97.7%{\sim}97.8%,\;98.0%{\sim}98.3%,\;94.8%{\sim}97.5%,\;88.0%{\sim}96.4.0%$, and $97.9{\sim}98.0%$, respectively. And those of magnesium, calcium, chromium, mauganese, and strontium in three groundwater were more than 99.0% at the same TMP. It was possible that vanadium contents of Wahyul, Ayum and Seogwipo groundwater were concentrated into 58.6, 118.9, and 165.1 ppb, respectively, by 6 stages treatment at the recovery ratio of 15%. And these concentrated water (vanadium water) did not exceed the permissible drinking water standards.

• Korean Journal of Food Science and Technology
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• v.50 no.3
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• pp.297-307
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• 2018

The aim of this study was to develop a seasoning paste fermented by Aspergillus oryzae and Bacillus subtilis using three edible insects: Tenebrio molitor larvae, Gryllus bimaculatus, and Bombyx mori pupa. No significant changes in pH and titratable acidity were observed between the insect pastes and soybean control during a 5-week fermentation process. The amino nitrogen was 0.35-0.50% (w/w) in the early stage of the fermentation and increased to 0.72-0.78%. The total nitrogen was 2.36-3.62% (w/w) in the early stage and was preserved during the fermentation period. Free amino acids of the insect pastes were similar to those in soybean paste. In general, the fermented insect pastes showed a lower flavor and color than soybean paste but B. mori pupa-fermented paste did not show any significant difference in preference from soybean. Glutamate, aspartate, lysine, phenylalanine, arginine, and serine were found to affect taste preference. It was possible to ferment edible insect protein to produce a fermented seasoning paste like Korean doenjang.

• Polymer(Korea)
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• v.36 no.1
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• pp.98-103
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• 2012

Poly(2,6-dimethyl-1,4-phenylene ether) (PPE) was synthesized using $Cu(NO_2)_2{\cdot}3H_2O$ or CuCl catalyst with various amounts of ligand and base in several different solvent systems. CuCl/1-methylimidazole/ammonium hydroxide was found to be an effective catalyst system which showed the highest polymer yield and molecular weight. The effects of catalyst/monomer ratio, different amine ligands, and the content of mono-functional reagent 2,4,6-trimethylphenol (TMP) additive on the polymer yield and molecular weight were investigated. Among the co-solvent systems used in this polymerization, chloroform/methanol 9/1(v/v) gave the highest polymer yield and molecular weight ($\overline{M_n}$ 55 K, $\overline{M_w}$ 92 K, PDI 1.7). The catalytic activity between CuCl and CuI was compared by oxygen-uptake experiments and the formation of sideproduct, 5,5'-tetramethyl-4,4'-diphenoquinone (DPQ), was analyzed by ultraviolet spectroscopy.

• 한국생물공학회:학술대회논문집
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• 2003.10a
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• pp.475-475
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• 2003

• Proceedings of the Membrane Society of Korea Conference
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• 2004.11a
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• pp.294-297
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• 2004

• Proceedings of the Membrane Society of Korea Conference
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• 2003.07a
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• pp.7-10
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• 2003

Factors affecting filtration performance were investigated in a Sequencing Batch Reactor (SBR) coupled with a submerged microfiltration module. Special bioreactors for aerobic and anoxic phases, respectively, were specifically designed in order to differentiate tile effect of Dissolved oxygen (DO) from that of mixing intensity on membrane filterability. DO concentration as well as mixing intensity proved to have a major influence on the membrane performance regardless of the SBR phase. A higher DO concentration resulted in a slower rise in TMP, corresponding to less membrane fouling.

• Clean Technology
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• v.7 no.3
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• pp.179-185
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• 2001

Some companies are trying to develop the microfiltration membranes because most of them used as a prefilter is imported in Korea. However, they are faced with much difficulty such as characterization of membrane and controlling of pore size on development. In this study, a microfiltration membrane developed by a company was evaluated for applicability to use as a prefilter before reverse osmosis membrane process in production of ultra pure water. The optimum feed pressure for the raw water was obtained at 0.2 to 0.4 atm. At that time, turbidity of the treated water was 0.4 NTU and flux was 6,000 to $9,000L/m^2/hr$. In case of the conventionally treated water, it showed the very stable flux and turbidity at 90% of recovery rate. The chemical cleaning was helpful to reduce the TMP for treated water. The turbidity was improved from 0.3 NTU to 0.1 NTU after chemical cleaning.

• Proceedings of the Korean Vacuum Society Conference
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• 2015.08a
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• pp.102.2-102.2
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• 2015

진공 시스템의 기저상태를 지배하는 것은 대부분의 경우 용기 내면에 수십 단원자 층 정도로 흡착되어 있는 물이다. 용기 압력이 10-9 mbar 대가 될 때까지는 잔류기체의 90% 이상이 수분이고 압력을 10분의 1로 떨어뜨리려면 10배의 시간이 더 필요하다는 소위 1/t 법칙은 광범위한 흡착에너지를 가지는 물분자의 표면방출 특성으로 잘 설명되어진다. 용기가열 등 적극적인 표면처리를 하지 않고 전형적인 압력변화 양상은 그대로 유지하면서 절대적인 시간을 줄이는 가장 직접적인 방법은 물 배기속도를 가능한 한 높이는 것이지만 대부분의 고진공 펌프들에서 물배기속도만 더 증가하도록 만드는 것은 쉽지 않다. 크라이오 워터펌프(CWP: cryo-water pump)는 바로 이런 고민을 제대로 해결할 수 있는 유일한 실용적인 방안이라고 말할 수 있다. 다른 기체분자들의 배기는 일단 염두에 두지 않고 물배기만을 열심히 해서 배기시간을 단축하고 도달 진공도를 낮추는 것을 목표로 하는 장치가 CWP이다. CWP는 모든 기체에 반응하는 정통적인 크라이오 펌프에 비해 훨씬 간단하고 저렴하게 만들 수 있으면서도 진공 시스템에 큰 영향을 미칠 수 있지만 그동안은 물배기의 필요성에 대한 인식이 미흡하고, 또 부수적이고 추가적인 비용이 드는 것으로 생각되어 주목을 받지 못했지만 디스플레이와 반도체 산업을 필두로 물분압을 낮추고 생산수율을 높이는 것에 점점 더 관심이 높아지면서 CWP에 대한 수요도 높아지고 있다. CWP의 물배기는 아주 단순한 응축현상에 의존하므로 물리적으로 이해하고 성능을 예측하는 것이 직관적이지만 사용용도에 따라 물 이외의 기체분자들은 잘 통과시키면서 물배기는 최대화하는 최적설계가 요구되거나 터보분자펌프(TMP)와 같이 이질적인 고진공펌프와 조합하여 사용하는 경우 기체 온도 의존성을 고려해야 하는 등 까다로운 점이 있다. 본 보고에서는 CWP+TMP로 구성된 복합진공배기시스템을 설계하면서 CWP만의 물배기성능과 복합 시스템의 물 및 알곤 배기성능을 예측하고, 두 펌프의 상호관계에 대해 분석하며, 실제 만들어진 복합배기시스템을 사용하여 실험적으로 구한 물 및 알곤 배기속도 측정결과에 대해서도 간단하게 논의하려고 한다.