• 한국펄프종이공학회:학술대회논문집
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• 한국펄프종이공학회 1999년도 추계학술발표논문집
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• pp.194-204
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• 1999

The use of genetically cloned xylanase acquired from Bacillus strearthermophillus improves bleachability for oak kraft pulps. Combination of xylanase(X). oxygen(O), ozone(Z). peroxide(P), alkaline extraction(Eo. Eop), and chlorination(C/D, D) have been tested in a variety of bleaching sequences. The effectiveness of xylanase pre-treatment(XO) and post-treatment(OX) in oxygen bleaching is mainly compared. With xylanase treatment the brightness increase by 1.5-2.1% ISO in OZEP, OZEoP, OZEopP and OPZP sequences. There is only numerically difference of brightness gains between OX and XO sequences. With xylanase treatment chemical requirements for bleaching decrease by 42.6-48.6% in OC/DEoD sequence and 47.9-54.7% as active chlorine in OC/DEopD sequence at the same brightness. the reduction of bleaching chemicals is higher in XO sequence than those in OX sequence. Following xylanase treatment the viscosity increases from 11.7-12.0 mPa·s to 12.4-13.5 mPa·s and the brightness stability is considerably improved however the difference of effectiveness between XO and OX sequence is not present. Compared to tensile index vs tear index, the physical properties are similar for TCF bleaching sequences with and without xylanase treatments. However in OC/DEoD and OC/DEopD sequences the physical properties decrease with xylanase treatment. There is no difference in the physical properties between XO and OX sequences. COD, BOD and color of bleaching effluents increase slightly with xylanase treatment, however the discharge of COD end-load into environmental impact decrease.

• Elastomers and Composites
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• 제22권3호
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• pp.195-203
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• 1987

본(本) 연구(硏究)는 기능성(機能性) elastomer 개발(開發)의 일환(一環)으로서 1-chlorobutadiene-butadiene copolymer(CB-BR)의 수가교(水架橋)에 의(依)한 기능성(機能性)의 향상(向上)에 그 목적(目的)을 두었으며 가교제(架橋劑)로서 3-aminopropyltriethoxysilane을 이용(利用)하여 CB-BR의 활성염소(活性鹽素)와의 용액반응(溶液反應)을 속도론적(速度論的)으로 해석(解析)하였다. 그리고 APS와 CB-BR을 실제공정(實際工程)에서 배합(配合)하여 수중가교반응(水中架橋反應)을 진행(進行)시켜 이에 따른 물성(物性) 검토(檢討)를 하므로써 다음과 같은 결론(結論)을 얻었다. 1. CB-BR은 용액계(溶液系)에서 APS와 용이(容易)하게 반응(反應)하며 이때의 반응(反應) 속도상수(速度常數) 및 활성화(活性化)에너지는 다음과 같다. 2. CB-BR+APS 수가교체(水架橋體)의 최적(最適) press 조건(條件)은 $150^{\circ}C{\cdot}20$분(分)이고 이들 가교체(架橋體)의 물성(物性)을 고무탄성체(彈性體) 이론(理論)에 의하여 가교진행(架橋進行)의 타당성(妥當性)을 검토(檢討)한 결과 이론치(理論値) q=1에 근접(近接)함을 알았다.

• Restorative Dentistry and Endodontics
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• 제45권4호
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• pp.47.1-47.11
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• 2020

Objectives: The aim of this study was to assess the physicochemical properties, cytotoxicity and penetration into dentinal tubules of ChlorCid^TM Surf (3% sodium hypochlorite [NaOCl] with surfactant) in comparison to ChlorCid^TM (3% NaOCl without surfactant). Materials and Methods: The physicochemical properties evaluated were pH, surface tension, free available chlorine (FAC) and contact angle. Cytotoxicity was evaluated in L929 fibroblasts exposed to the solutions by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide and neutral red assays. Assessment of penetration into dentinal tubules was performed by staining single-rooted permanent human teeth with crystal violet (n = 9), which were irrigated with the solutions and analyzed in cervical, middle and apical segments. Data were analyzed by one-way analysis of variance (ANOVA) and Tukey's post-test, 2-way ANOVA and Bonferroni's post-test or t-test (α = 0.05). Results: ChlorCid^TM Surf and ChlorCid^TM FAC values were close to those indicated by the manufacturer. ChlorCid^TM Surf showed lower surface tension and contact angle on dentin, and higher pH than ChlorCid^TM (p < 0.05). The penetration of ChlorCid^TM Surf was higher in cervical and middle segments, compared with ChlorCid^TM (p < 0.05). There was no difference in irrigant cytotoxicity (p > 0.05). Conclusions: ChlorCid^TM Surf showed lower surface tension, lower contact angle on root canal dentin, higher penetration into dentinal tubules and more alkaline pH, compared with ChlorCid^TM. However, both solutions showed similar cytotoxicity and FAC content.

• Journal of Dairy Science and Biotechnology
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• 제41권4호
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• pp.203-210
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• 2023

Bacterial contamination negatively affects the quality, functionality, and safety of dairy products. Adherent populations of bacteria, referred to as biofilms, grow on the surfaces of dairy processing equipment and are the primary cause of dairy contamination. In addition, microorganisms present in the farm environment and dairy factory can contaminate the Clear-In-Place (CIP) line through raw milk transport pipes; therefore, exhaustive management is required. In dairy manufacturing facilities, biofilm formation is controlled using CIP systems that primarily require sodium hydroxide and nitric acid. However, the leakage or incomplete removal of these potently active compounds can be harmful to humans. In the present study, we compared the eradication of Escherichia coli and other bacteria using commercially available combinations of sodium hypochlorite (NaClO) and citric acid, which are recognized by the Korean Ministry of Food and Drug Safety (MFDS) as food disinfectants. When considered in the CIP system of the field manufacturing process, E. coli was not detected (compared to detection before treatment), and other bacteria were detected at 0-32 culture-forming units (CFU)/cm². The residual amount of chlorine ions after CIP treatment was similar to that in tap water, and there was no significant difference in the overall components of the fermented dairy products. Therefore, the NaClO/citric acid CIP system can be safely applied in dairy manufacturing processes.