• 대한환경공학회지
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• 제38권11호
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• pp.627-634
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• 2016

본 연구에서는 탄소폼 흡착소재를 이용하여 산업도금폐수로부터 중금속을 흡착 제거한 후 탈착용액을 이용하여 제거된 중금속을 용출하고 회수하는 과정의 특성을 평가해 보고자 하였다. 용액의 조성에 따른 복합 중금속의 탈착 특성을 살펴본 결과 증류수 조건에서는 용출이 관측되지 않았으며, 탈착용액으로 HCl과 $H_2SO_4 $를 이용한 경우 높은 중금속 농도를 나타내었다. 탈착 용액을 이용함과 더불어 물리적 기술인 초음파 처리를 이용한 경우 중금속의 용출이 증진되는 것을 확인하였으며, 초음파 장치의 출력이 높고 반응 시간이 길수록 효율도 증가하는 것으로 나타났다. 탄소폼 흡착소재를 구리도금 세척수 처리에 적용시켜본 결과 200 반응기부피(Bed volume) 동안 안정적인 제거 성능을 나타내었으며, 흡착된 구리는 탈착용액을 이용하여 용출시킨 후 직류 전원 장치를 이용하여 회수할 수 있었다. 또한 구리가 회수된 탈착용액은 재이용 효율은 84.2%로 나타났다.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2001년도 The 6th International Symposium of East Asian Resources Recycling Technology
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• pp.259-263
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• 2001

There are several steps such as slicing, lapping, chemical etching and mechanical polishing in the silicon wafer production process. The chemical etching step is necessary to remove damaged layer caused In the slicing and lapping steps. The typical etching liquor is the acid mixture comprising nitric acid, acetic acid and hydrofluoric acid. At present, the waste acid is treated by a neutralization method with a high alkali cost and balky solid residue. A solvent extraction method is applicable to separate and recover each acid. Acetic acid is first separated from the waste liquor using 2-ethlyhexyl alcohols as an extractant. Then, nitric acid is recovered using TBP(Tri-butyl phosphate) as an extractant. Finally hydrofluoric acid is separated with the TBP solvent extraction. The expected recovered acids in this process are 2㏖/l acetic acid, 6㏖/1 nitric acid and 6㏖/l hydrofluoric acid. The yields of this process are almost 100% for acetic acid and nitric acid. On the other hand, it is important to recover and reuse the metal values contained in various industrial wastes in a viewpoint of environmental preservation. Most of industrial products are made through the processes to separate impurities in raw materials, solid and liquid wastes being necessarily discharged as industrial wastes. Chemical methods such as solvent extraction, ion exchange and membrane, and physical methods such as heavy media separation, magnetic separation and electrostatic separation are considered as the methods for separation and recovery of the metal values from the wastes. Some examples of the application of solvent extraction to the treatment of wastes such as Ni-Co alloy scrap, Sm-Co alloy scrap, fly ash and flue dust, and liquid wastes such as plating solution, the rinse solution, etching solution and pickling solution are introduced.

• Journal of Korean Dental Science
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• 제7권2호
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• pp.49-57
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• 2014

Purpose: To evaluate the effect of different surface treatment methods (yttria-tetragonal zirconia polycrystal [Y-TZP] primers, air-abrasion, and tribochemical surface treatment) on the shear bond strength between (Y-TZP) ceramics and etch-and-rinse non-10-methacryloyloxydecyl dihydrogen phosphate (MDP)-containing resin cements. Materials and Methods: Y-TZP ceramic surfaces were ground flat with 600-grit silicone carbide abrasives paper and then divided into seven groups of ten. They were treated as the following: untreated (control), Monobond Plus (IvoclarVivadent), Z-PRIME Plus (Bisco Inc.), ESPE Sil with CoJet (3M ESPE), air-abrasion, Monobond Plus with air-abrasion, and Z-PRIME Plus with air-abrasion. The surface of Y-TZP specimens was analyzed under a scanning electron microscope (SEM). Non-MDP-containing cements were placed on the surface-treated Y-TZP specimens. After thermocycling, shear bond strength test was performed. Bond strength values were statistically analyzed using one-way analysis of variance and Student-Newman-Keuls multiple comparison test (P<0.05). Result: The Z-PRIME Plus treatment in combination with air-abrasion produced the highest bond strength ($14.94{\pm}1.70MPa$) followed by Monobond Plus combined with air-abrasion ($10.70{\pm}1.71MPa$), air-abrasion ($10.47{\pm}1.60MPa$), ESPE Sil after CoJet treatment ($10.38{\pm}0.87MPa$), Z-PRIME Plus application ($10.00{\pm}1.70MPa$), and then Monobond Plus application ($9.25{\pm}0.86MPa$). The control ($6.70{\pm}1.49MPa$) indicated the lowest results (P<0.05). The SEM results showed different surface morphologies according to surface treatment methods compared with the Y-TZP control. Conclusion: The shear bond strength between the Y-TZP ceramic and the non-MDP-containing resin cement was the greatest when the surface was treated with air-abrasion and MDP-containing Z-PRIME Plus primer.

• 농업과학연구
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• 제11권2호
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• pp.201-206
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• 1984

효과적(效果的)이고 용이(容易)하게 사용할 수 있는 한국잔디(Zoysia japonica Steud.) 종자(種子)의 발아(發芽) 촉진방법(促進方法)을 모색(摸索)코자 sodium hypochlorite(SH)용액(溶液)을 사용하여 종피처리(種皮處理)한 결과(結果)는 다음과 같다. 1. 종자(種子)를 4%의 SH용액(溶液)에 2시간(時間) 침지처리(浸漬處理)한 후(後) 8시간(時間) 수세(水洗)한 결과(結果) KOH처리(處理)에 비(比)하여 발아촉진효과(發芽促進效果)가 좋았다. 2. SH처리(處理) 후(後) 수세시간(水洗時間)에 따라서 발아율(發芽率)에 차이(差異)가 있었으나 대체로 4~8시간(時間)의 수세(水洗)가 가장 효과적(效果的)이었다. 3. SH처리(處理) 후(後) GA를 처리(處理)함으로써 발아(發芽)가 더욱 촉진(促進)되었으나 무처리구(無處理區)에서는 GA처리(處理)에 의한 발아촉진효과(發芽促進效果)가 인정(認定)되지 않았다. 4. SH처리(處理)는 KOH처리(處理)에 비(比)하여 균유(菌類)의 종자감염율(種子感染率)을 크게 감소(減少)시켰다. 5. SH처리(處理)는 한국잔디 종자(種子)의 발아촉진(發芽促進)을 위해서 KOH처리법(處理法)에 비(比)하여 쉽게 준비(準備)할 수 있고, 안정성(安定性)이 있으며, 취급(取扱)하기 쉬운 효과적(效果的)인 종피처리방법(種皮處理方法)이라고 생각된다.

• 한국치위생학회지
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• 제10권5호
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• pp.819-829
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• 2010

Objectives : The purpose of this study was to examine factors affecting the effective demand of workers for dental treatment in a bid to provide some information on the improvement of oral health. Methods : The subjects in this study were 255 workers who were engaged in the pharmaceutical industry. A self-administered survey was conducted, and the collected data were analyzed by a spss(statistical package for the social science) win 12.0 program to find out their demographic characteristics, oral health awareness, oral health behavior and factors for the choice of a dental institution. Results : 1. Concerning the level of oral health awareness, 47.0 percent were at a low level(0 to three scores), and 35.2 percent were at an intermediate level(four to six scores). 2. As to oral health behavior involving a daily mean toothbrushing frequency, they brushed their teeth 2.65 times per day on the average. The most widely utilized oral hygiene supply was mouth rinse. Regarding oral health status, 53.7 percent weren't in good dental health, and just 23.0 percent got a dental checkup on a regular basis. 45.8 percent of those who didn't get a dental checkup cited time constraints as the reason. 26.0 percent received oral health education, and 91.4 percent were aware of the necessity of a corporate incremental dental care system. 3. Marital status, age and the reliability of dental institutions made differences to their choice of a dental institution. 4. As for the relationship between oral health awareness and the factors for the choice of a dental institution, oral health awareness had a statistically significant positive correlation to the reliability of dental institutions. Conclusions : The above-mentioned findings suggest that oral health education enables workers to have a correct knowledge on oral health, to change their own oral health behavior and to make the right choice of a dental institution in consideration of their oral characteristics. They should be urged to get a regular dental checkup not to develop chronic oral diseases so that they couldn't have to receive first-aid dental treatment. To promote the oral health of workers, oral health care personnels available should be utilized, and the incremental dental care system should be more vitalized to cut down on their effective demand for dental treatment.

• 치위생과학회지
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• 제19권4호
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• pp.288-293
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• 2019

Background: Dental caries is one of several prevalent oral diseases caused by dental plaque biofilms. This study evaluated the anti-cariogenic effects of a bamboo salt (BS) and sodium fluoride (NaF) mixture on oral bacteria. Methods: The effects of several mixtures of NaF and BS on acid production, growth, and adhesion to glass beads of Streptococcus mutans, and their anti-cariogenic properties were investigated. The growth of S. mutans was measured according to optical density at 3, 6, 9, 12, 15, 18, and 24 hours after treatment using spectrophotometry at a wavelength of 600 nm, while pH was measured using a pH meter. Adhesion of S. mutans was measured according to the weight of glass beads from each group before and after incubation. Gene expression was measured using real-time polymerase chain reaction. Acid production and growth patterns of S. mutans were compared using repeated measures analysis of variance, followed by Scheffe's post-hoc test. The Kruskal-Wallis test was used to compare adhesion, followed by the Mann-Whitney test. Gene expression in the experimental and control samples was compared using the Student's t-test. Results: Growth, acid production, and adhesion of S. mutans were inhibited in all experimental groups. Expression of gft and fructosyltransferase in S. mutans was inhibited in all groups. A mixture of NaF and BS significantly reduced growth, acid production, adhesion, and gene expression of S. mutans compared with the other groups. Conclusion: Results of the present study demonstrated that a mixture of NaF and BS was useful as a mouth rinse in preventing dental caries.

• 대한치과교정학회지
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• 제47권5호
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• pp.306-312
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• 2017

Objective: The purpose of this study was to examine the effect of commercially available fluoride-containing oral rinses on the corrosion behavior of titanium alloys, which are the main components of orthodontic miniscrews. Methods: Four commercially available oral rinses (solution A, pH 4.46/260 ppm fluoride; solution B, pH 4.41/178 ppm fluoride; solution C, pH 6.30/117 ppm fluoride; and solution D, pH 4.17/3.92 ppm fluoride) were tested on titanium alloy (Ti-6Al-4V) circular plates, and saline was used as the control. The open-circuit potential and potentiodynamic polarization of these materials were measured. Thereafter, all samples were evaluated under a field-emission scanning electron microscope. Results: Among the tested oral rinses, except solution D, the more the fluoride content was, the greater was the corrosion potential downtrend; the corrosion resistance of the titanium alloy sample was also lowered significantly (p < 0.05). Field-emission scanning electron microscopic analysis of the surface morphology of the titanium alloy samples revealed that all samples had some defects, crevices, or pitting after exposure to the oral rinses than before treatment. In particular, the samples in solution A showed the most changes. Conclusions: Commercially available oral rinses having a high fluoride concentration and a low pH may reduce the corrosion resistance of titanium alloys used in dental appliances such as orthodontic titanium miniscrews and brackets.

• 대한영양사협회학술지
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• 제10권4호
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• pp.381-389
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• 2004

The purpose of this study was to investigate effectiveness of sanitization on raw vegetables not heated in foodservice operations. Microbiological examinations of food materials and cooked food with leek Gukgalli were performed in 2 HACCP-implemented foodservices (A and B) appointed by Food and Drug Administrations, and in 2 other foodservices (C and D) not implemented HACCP. 'Washing and sanitizing raw vegetables' were monitored as CCP at A and B foodservices but only washing has been done in pre-preparation at C and D foodservices. Aerobic plate counts of received leek in A and B foodservices were above $10^7$ CFU/g indicating very poor microbiological quality. After sanitization treatment (soaking for 5 minutes in chlorine water: chlorine density 50〜100 ppm), its aerobic plate counts decreased to 7.06×$10^5$ CFU/g (A foodservice) and 4.31×$10^5$ CFU/g (B foodservice), coliform and faecal coliform were not detected. With this result, the effect of microbial reduction by sanitizer was conformed. But, the conditions of leek were still not acceptable by microbiological standards for ready-to-eat foods. After three more times of rinse has been done, the microbial conditions of leek became acceptable. In C and D foodservices, aerobic plate counts of leek showed decreasing trends by 2〜4 times of washings but microbiological quality of leek after pre-preparation were unacceptable by microbiological standards for ready-to-eat foods (C foodservice: 3.58×$10^5$ CFU/g, D foodservice: 1.29×$10^9$ CFU/g). For the prevention of foodborne illness, sanitizing raw vegetables should be performed during pre-preparation of non-heated foods.

• Journal of Periodontal and Implant Science
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• 제44권3호
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• pp.134-140
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• 2014

Purpose: Triphala is a combination of three medicinal plants, extensively used in Ayurveda since ancient times. Triphala mouthwash is used in the treatment of periodontal diseases because of its antimicrobial and antioxidant properties. The aim of this study is to compare the efficacy of triphala mouthwash with 0.2% chlorhexidine in hospitalized periodontal disease patients. Methods: In this double-blind, randomized, multicenter clinical trial, 120 patients were equally divided into three groups. Patients in group A were advised to rinse their mouths with 10 mL of distilled water, group B with 0.2% chlorhexidine, and group C with triphala mouthwash for 1 minute twice daily for two weeks. The plaque index (PI) and the gingival index (GI) were recorded on the first and the fifteenth day. Results: There was no significant difference when the efficacy of triphala was compared with 0.2% chlorhexidine in hospitalized patients with periodontal disease. However, a statistically significant difference was observed in PI and GI when both group B and group C were compared with group A and also within groups B and C, after 15 days (P<0.05). Conclusions: The triphala mouthwash (herbal) is an effective antiplaque agent like 0.2% chlorhexidine. It is significantly useful in reducing plaque accumulation and gingival inflammation, thereby controlling periodontal diseases in every patient. It is also cost effective, easily available, and well tolerable with no reported side effects.

• Restorative Dentistry and Endodontics
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• 제31권2호
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• pp.119-124
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• 2006

본 연구는 새로이 개발된 근관세정제 (MTAD)가 근관 충전이 이루어지고 난 치근단 누출에 미치는 영향을 평가해 보고자 하였다. 일반적인 방법의 근관 성형과 세정 그리고 충전을 시행하는데 있어 실험군 들에서는 NaOCl만, NaOCl과 EDTA, NaOCl과 MTAD를 사용하였고 10일 동안 표준전극과 시편 근관 내에 위치시킨 실험전극 사이의 전기저항을 측정하여 시간에 따른 치근단 누출의 변화를 비교 평가하였다. 실험결과 측정 시간 30분에서 7일 사이에서 smear layer 제거한 군들 (Group 4와 5)에서 제거하지 않은 군(Group 3)에서 보다 적은 치근단 누출을 보였지만 통계학적인 유의성있는 차이를 나타내지는 않았다 실험군들 사이에서 모든 시간 대에 걸쳐 치근단 누출의 유의성 있는 차이를 관찰할 수 없었다.