• 상하수도학회지
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• 제24권1호
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• pp.93-101
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• 2010

Reverse osmosis (RO) membranes have been widely used for desalination as well as water and wastewater treatment facilities. Cleaning process is important to maintain stable operation as well as prevention of membrane fouling. Purpose of this research is to analyze electrostatistic and chemical characteristics after cleaning of RO membrane against $SiO_2$ scale. Four RO membranes of polyamide are used and examined about effect of chemical cleaning. EDTA (ethylene diamine tetraacetic acid) and SDS (sodium dodecil sulfate) and NaOH are applied for cleaning process after operation in synthetic water. Then, cleaning was performed with chemicals such concentration as 6hr, 12hr and 24hr, respectively. As a result, transmittances of FT-IR of four membranes are compared at each cleaning concentration. Ta/Tv shows difference of chemical composition between new membrane and cleaning membrane after cleaning. Type B of RO membrane is turned out to be most vulnerable to cleaning among four membranes. In terms of zeta potential, new membrane has -16 mV to +6 mV on pH while scaled membrane has -18 mV to 2 mV. However, it changed -23mV to 0.9 mV after cleaning. In comparison with existing salt rejection of RO membranes after cleaning, the rejection of the membranes goes down 0.7% maximum. Though cleaning changes the characteristics of membrane surface, it does not greatly affect salt rejection. pH is a critical factor to flux change in PA (polyamide) membrane.

• Environmental Engineering Research
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• 제23권4호
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• pp.474-484
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• 2018

The cleaning efficiency of reverse osmosis (RO) membranes inevitably fouled by organic foulants depends upon both chemical (type of cleaning agent, concentration of cleaning solution) and physical (cleaning time, flowrate, temperature) parameters. In attempting to determine the optimal procedures for chemical cleaning organic-fouled RO membranes, the design of experiments concept was employed to evaluate key factors and to predict the flux recovery rate (FRR) after chemical cleaning. From experimental results and based on the predicted FRR of cleaning obtained using the Central Composite Design of Minitab 17, a modified regression model equation was established to explain the chemical cleaning efficiency; the resultant regression coefficient ($R^2$) and adjusted $R^2$ were 83.95% and 76.82%, respectively. Then, using the optimized conditions of chemical cleaning derived from the response optimizer tool (cleaning with 0.68 wt% disodium ethylenediaminetetraacetic acid for 20 min at $20^{\circ}C$ with a flowrate of 409 mL/min), a flux recovery of 86.6% was expected. Overall, the results obtained by these experiments confirmed that the equation was adequate for predicting the chemical cleaning efficiency with regards to organic membrane fouling.

• 한국염색가공학회지
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• 제2권3호
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• pp.43-50
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• 1990

The purpose of this paper is to investigate the dyes solubility of dry cleaning solvents among the current domestic products. The dyes were experimented in following way; 1) The flow rate of dyes by paper chromatography method. 2) The color difference & the absorbance of solvents between the dyed fabrics before and after dry cleaning. From the experiment, following results were obtained. 1. In paper chromatography methods, the flow rate of dyes in the disperse dyes was bigger while flow was not shown in the direct dyes & acid dyes. 2. The more the number of times on dry cleaning in dyed fabrics was, the higher the absorbance of solvents was shown. The results were showed following order, PerchloroethyleneHydrocarbon> Fluorocabon. 3. The color difference between before & after dry cleaning on dyed fabrics showed bigger in disperse dyes.

• Korean Chemical Engineering Research
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• 제54권4호
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• pp.548-554
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• 2016

Damascene 구조를 갖는 반도체소자의 구리금속배선 식각공정에서 배선재료에 의해서 발생되는 구리 식각잔류물을 제거하기 위해 oxalic acid (OA), lactic acid (LA) 및 citric acid (CA)의 카르복시산 함유된 반수계 혼합세정액을 제조하고 특성을 분석하였다. 카르복시산은 pH에 따라 카르복실기와 구리이온들과의 다양한 복합체를 형성하며 세정특성의 변화를 준다. 카르복시산들이 함유된 각각의 세정액의 세정특성평가결과 10 wt% CA를 함유한 반수계 세정액의 식각잔류물 세정특성은 pH 2에서 7까지의 영역에서 가장 낮은 구리 식각률을 보였으며 pH 2에서 4까지 구리에 대한 구리산화물의 가장 높은 식각 선택도를 나타내었으나 pH 5에서 7 범위에서는 10 wt% LA가 함유된 세정액이 더 높은 선택도를 보였다. 따라서 표면세정효과는 pH에 따라 변화하며 적절한 카르복시산을 사용함이 요구된다. CA가 함유된 세정액의 경우에 CA 농도와 구리에 대한 구리산화물의 식각 선택도의 증가특성을 보이며 CA가 5 wt%이상 함유된 경우에는 세정 후 구리배선의 표면이 88 %이상의 금속구리로 분석되어 구리산화물로 구성된 식각 잔류물의 제거에 효과적임을 알 수 있었다.

• 보존과학연구
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• 통권31호
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• pp.43-57
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• 2010

This study intends to provide quantitative data about the extraction characteristics of major elements of earthenware by executing soaking test of cleaning agents. It aims at providing basic data for the stability assessment when applying the cleaning agents for conserving earthenware. The data will be extracted from the analysis of co-relationship between the physical characteristics and the ion extraction characteristics. XRD analysis displayed that AT-1, AT-2 and AT-3 which did not generate mullite were fired at lower than 1,000 whereas AT-3 and AT-5 that included mullite were higher than 1,000. The degree of absorption was AT-4 > AT-2 > AT-1 > AT-3 > AT-5 in order and the correlation between the degree of absorption and firing temperature of earthenware displayed a positive correlation. Extraction amount of oxalic acid which was used for the removing iron oxide was AT-1 > AT-2 AT-4 > AT-3 > AT-5 in order. and the ion extraction data displayed that there is a positive correlation with absorption level. However AT-1 and AT-2 which were fired at lower temperature showed that there was no correlation between the ion extraction characteristics and absorption level. Ion extraction of citric acid produced little amount compared with the one of oxalic acid, yet it caused less damage to earthenware than oxalic acid when it applied. The result of ion extraction level in the absorption test displayed that Fe had higher level than in Si, Al from the test for both oxalic acid and citric acid. Based on the regression analysis of the data from the previous studies, the physical characteristics of the earthenware and ion extraction level, further studies will be conducted on the predicting technique on the extraction characteristics of major elements of earthenware samples for the conservation in future.

• 한국안광학회지
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• 제15권4호
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• pp.347-353
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• 2010

목적: 소프트콘택트렌즈 관리용액에 의한 balafilcon A 재질의 실리콘 하이드로겔렌즈에 부착된 지방 침전물 제거효과를 비교하였다. 방법: Balafilcon A 재질의 실리콘 하이드로겔렌즈를 실험실 조건에서 oleic acid, oleic acid methyl ester, cholesterol이 포함된 식염수에 담가 24시간 동안 오염시켰다. 오염된 콘택트렌즈는 식염수로 헹구어준 후 계면활성세척액, 알콜 성분이 포함된 세척액 및 다목적용액으로 각각 세척하였고, 반복적인 오염과 세척효과를 관찰하기 위해서는 오염과 세척과정을 14회 반복하였다. 초음파의 지방침전물 세척 효과를 관찰하기 위하여 오염된 렌즈에 초음파처리를 한 후 처리하지 않은 렌즈와 비교하였다. 지방침전물은 methanol:chloroform (1:1, v/v) 용액으로 추출하고 고성능액체크로마토그래피로 분석하여 정량하였다. 결과: 실리콘 하이드로겔렌즈의 지방세척효과는 알콜성분을 함유한 세척액이 계면활성세척액 및 다목적용액보다 높았으며, 초음파를 함께 처리해준 경우에는 세척 효과가 상승하였다. 콘택트렌즈 관리용액으로 세척한 후에도 지방침전물은 완전히 제거되지 않아 오염과 세척을 반복한 경우 지방 침전물의 양은 지속적으로 증가하였다. 결론: 실리콘 하이드로겔렌즈에 부착되는 지방 침전물에 대한 소프트 콘택트렌즈용 관리용액의 세척효과는 만족할 수준에 미치지 못하기 때문에 실리콘 하이드로겔렌즈의 지방 침전물 제거에 적합한 세척액의 개발이 필요할 것으로 사료된다.

• Korean Chemical Engineering Research
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• 제40권6호
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• pp.769-777
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• 2002

Nonionic surfactant/water/탄화수소 오일/alcohol의 4성분계 시스템에서 12종의 조성물을 제조하여 물성 평가를 수행한 결과, 30.5-31.1 dyne/cm의 낮은 표면장력의 값과, 1.6-7.2 c.p.의 낮은 점도의 물성을 보여 산업용 세정제로서의 기본 물성을 보여주었다. 이들 조성물들이 안정한 단일상으로 존재하는 온도의 범위는 alcohol/surfactant(A/S)비의 증가에 따라 감소되는 경향을 보이고 있으나, 전체적으로는 계면활성제의 hydrophilic lipophilic balance(HLB) 값에 크게 영향을 받고 있으며, HLB 값이 높을수록 안정하게 존재하는 온도 영역이 증가되는 경향을 보여주고 있다. 그리고 각각의 조성물에 물의 함량을 증가 시켜 안정한 단일상이 유지되는 물의 최대 함유량을 측정한 결과 HLB 값이 낮은 계면활성제를 사용하였을 경우 HLB 값이 6.4인 비이온 계면활성제를 사용할 경우 22.1%까지도 물을 함유할 수 있었고, 물의 양이 증가됨에 따라서 단일상으로 존재하는 온도영역은 좁아졌다. 오염원으로 플럭스 제조에 사용되는 abietic acid에 대한 세정 효율을 UV/Visable Spectrophotometer와 FT-IR Spectrometer와 같은 분석기기를 이용하여 검토하여 본 결과, 비이온 계면활성제의 HLB 값이 낮을수록 높은 세정 효율을 보여주어, W/O microemulsion의 경우 비이온 계면활성제에 따른 세정력의 변화가 매우 큼을 확인 할 수 있었다. 그러나 A/S의 비가 증가에 따른 세정효율의 차이는 별다른 경향을 보이지 않았다. 또한 산업세정에 있어서 중요한 세정 요소로 작용하는 변수인 온도 변화와 초음파 주파수의 변화에 따른 세정효율을 측정한 결과, 온도가 높을수록 그리고 초음파의 주파수가 낮을수록 높은 세정력을 보여주었다. 세정 공정 중 린스조에서의 유분 오염물이 함유된 린스액의 유수분리 효율을 측정한 결과, HLB 값이 6.4인 비이온 계면활성제를 사용한 시스템의 경우 $25^{\circ}C$ 이상에서 85% 이상의 높은 제거 효율을 보여, 효율적인 세정 및 관리가 가능한 것으로 판단되었다.

• 한국식품영양학회지
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• 제25권2호
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• pp.398-406
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• 2012

The acid value of the oil extracted from the three kinds of 15 fried foods ranged from 0.89 to 3.92, the peroxide value ranged 10.0~57.14 meg/kg. Among the samples, popcorn chicken contained the highest crude fat content, showing $6.64{\pm}0.26(%)$, while the french-fries showed $2.87{\pm}0.31(%)$, which was the lowest. The content of the trans fatty acid per 100 g of the foods were; the fried foods: 0.02~0.06 g. The french-fries contained the lowest saturated fatty acid per 100 g of the foods, showing 0.41~1.55 g, while the popcorn chicken showed the highest content, 1.16~3.43 g. The fried foods contained the highest linoleic acid content. Further, fried foods exhibited safe levels of trans fat content. The "School Zone", which sells snacks, candies, chocolates flow, was not detected in the saccharin. Cookies, candies, chocolate was not detected in the tar colors. Aerobic plate count were ranged from 0~4,700 cfu/g in cookies, Salmonella test came out negative.

• 한국인쇄학회지
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• 제15권2호
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• pp.117-130
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• 1997

Studies have been conducted to explore thermal imidization of polyamic acid. Aromatic polyimides are well recognized as high temperature linear polymers, and polyimide are used as structural materials, fibers, and adhesive. Two different kinds of polyimide were prepared by theimidization of polyamic acid which were synthesized from 2,2-bis[4-(4-aminophenoxy)phenyl]- hexafluoropropane, 2,2-bis [4-(4-aminophenxy)phenyl] - hexamethylpropane and caprolactam and pyromelliti dianhydride under N-Methly-pyrrolidinone solvent. Polyamic acids were converted to polyimides containing imide bond by thermal imidization. The weight 50% loss temperatures of polyimide by TGA thermogram were recorded in the range of 700 ~ 720$^{\circ}$C in nitrogen gas. According, as a results, we conclued polyamic acid were cycliation after H2O molecule separationed, and this polyimide film could be used for Printed Circuit Boand.

• The Journal of Korean Physical Therapy
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• 제9권1호
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• pp.147-156
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• 1997

The purpose of this study is to determine the difference of reduction in lactic acid of blood in the course of time 1)whoa applying the blood cleaning therapy during recovery after anaerobic exercise, 2)when applying the massage during recovery after anaerobic exercise, and 3)while taking a rest during recovery after anaerobic exercise, respectively. The subject of this study consists of 30 men who are divided into three groups such as group 1(n=10) for the blood cleaning therapy, group 2(n=10) for the massage and group 3(n=10) for rest. The blood-gathering was performed over four times ; during rest, immediately after unaerobic exercise, and at 10 and 15 minutes during recovery. The results were summarized as fellows. 1. There was reduction in lactic acid when applying the blood cleaning therapy during recovery after anaerobic exercise. And remarkable differences were shown from immediately after exercise to at 10 and 15 minutes during recovery(p<0.01 and p<0.001, respectively). 2. There was also reduction in lactic acid when applying the massage during recovery after anaerobic exercise. No difference wan shown from immediately after exercise to at 10 minutes during recovery. However a remarkable difference was shown from immediately after exercise to at 15 minutes during recovery(p<0.05). 3. The rest group which took a rest during recovery after anaerobic exercise did not show any difference from immediately after exercise to at 10 and 15 minutes during recovery.