• 상하수도학회지
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• 제23권2호
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• pp.175-180
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• 2009

This study was conducted to improve biological degradation efficiency of toluene as a model volatile organic compound (VOC) using yeast Candida tropicalis and to suggest an effective method for bioreactor operation. The yeast strain was immobilized with polyethylene glycol (PEG), alginate, and powdered activated carbon (PAC). The yeast-immobilized polymer media were used as fluidized materials in an airlift bioreactor. Polymer media without PAC were also made and operated in another airlift bioreactor. The two bioreactors showed toluene removal efficiencies ranging 80-96% at loading rates of $10-35 g/m^3-hr$, and the bioreactor containing the polymer media with PAC achieved higher removal efficiency. Protein contents in the liquid phase showed that the bioreactor using the yeast-immobilized polymer media with PAC had a higher rate of microbial growth initially than that without PAC. In addition, the microbial growth rate inside of the polymer media with PAC was five times higher than that without PAC. Consequently, the polymer media containing the yeast strain and PAC could enhance removal efficiencies for VOCs, and the immobilization method improve microbial activity and stability for a long-term operation of biological systems.

• Journal of Microbiology and Biotechnology
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• 제11권6호
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• pp.964-972
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• 2001

The kinetics of copper ion biosorption by Pseudomonas stutzeri cells immobilized in alginate was investigated. During the first few minutes of the metal uptake, the copper biosorption was rapid and then became progressively slower until an equilibium was rapid, and then became progressively slower until an equilibrium was reached. At a biomass concentration of 100g/l, the copper biosorption reaction reached approximately 90% of the equilibrium position within 30 min. A Freundich-type adsorption isotherm model was constructed based on kinetics with different amounts of biomass. When using this model, the experimental values only agreed well with the predicted values in a solution containing less than 200 mg/l Cu(II). Desorption of the bound copper ions was achieved using electrolytic solutions of HCl, $H_2SO_4$, EDTA, and NTA (0.1 or 0.5 M). Metal desorption with 0.1 M NTA allowed the reuse of the biosorbent for at least ten consecutive biosorption/desorption cycles, without an apparent decrease in its metal biosorption capability. A packed-bed column reactor of the immobilized biomass removed approximately 95% of the metal in the first 30 liter of wastewater [containing 100 mg/l Cu(II)] delivered at a rate of 20 L/day, and, thereafter, the rate gradually decreased.

• 한국환경과학회지
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• 제6권1호
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• pp.61-67
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• 1997

미생물에 의한 흡착법으로 중금속을 효과적으로 제거, 회수할 수 있다. 알콜 발효 후 부산물로 생성되는 폐 Saccharomyces cerevisiae는 비교적 가격이 저렴하고, 중금속 생체흡착에 유용한 자원으로 이용될 수 있다. 생체흡착 실험에 사용된 미생물은 부유 및 alginate에 고정화된 S. cerevisiae로 수행하였다. 회분식 실험에서 생체흡착량은 Pb > Cu > Cd의 순으로 이루어졌다. Pb 이온의 흡착 평형은 Freundlich와 Langinuir 모델로 설명하였고, Freundlich 모델이 실험자 료와 잘 부합되었다 고정화된 S. cerevisiae를 이용한 혼합용액( Pb, Cu, Cr 및 Cd )흡착 실험에서 각 중금속들은 선택적 흡착 특성을 나타내었다. 고정화 미생물을 고정층 반응기에 충진하여 혼합 중금속 용액의 생체흡착 실험을 수행한 결과 Pb 이온이 가장 많이 흡착을 하였다. 고정화된 미생물에 흡착된 Pb의 탈착실험에서 0.1M의 HCI 및 $H_2SO_4$가 효과적이었다.

• Archives of Plastic Surgery
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• 제35권1호
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• pp.48-55
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• 2008

Purpose: We measured linear distances, angles and inclinations on the cast models of the noses, and compared these indirect measurements with the direct measurements obtained from the nose in order to validate the accuracy of the indirect anthropometry using the cast model. Methods: Subjects were 50 males and 50 females, medical students in twenties(mean 27.1 years). Cast models were made from the alginate impression material and the plaster. In direct anthropometry, 16 linear, 7 angular, and 2 inclination measurements between 11 landmarks on the nose were obtained using sliding caliper, spreading caliper, and fabric tape measure. At the same time, the same measurements were obtained from the cast models of the same people. Total 25 measurements were compared, and tested by the independent t-test of SPSS. Results: The standard values of Korean nose in twenties were obtained. 24 measurements except the columellar labial angle were not statistically different between the indirect anthropometry and the direct anthropometry. Conclusion: Indirect anthropometry on the cast model of the nose revealed no significant difference from the anthropometric measurement statistically, accounting for 24 in 25 measurements(96%). There are two possible reasons that caused the difference of columellar labial angle between direct and indirect anthropometry. First, the columellar labial angle could be decreased by protrusion of the lips which resulted from contracting mouth in which an drinking straw had been applied on the mouth corner for patients' respiration during making cast model. Second, it is generally known that the columellar labial angle could be measured larger when soft tissues were pressed by protractor in direct anthropometry. Using a drinking straw with greater diameter, and scheming respiration through the nostrils that patients don't feel discomfort, the more accurate data would be obtained from the indirect anthropometry using the cast models of the noses.

• Advances in Traditional Medicine
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• 제7권3호
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• pp.254-260
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• 2007

Alstonia scholaris (Family: Apocynaceae) has been indicated for the treatment of various diseases, one among which is wound healing. The purpose of this study is to investigate the wound healing effect and antioxidant role of Alstonia scholaris leaves in animal models. The ethanol and aqueous extracts of Alstonia scholaris (EEAS, AEAS respectively) were tested against excision, incision and dead space wound models to evaluate the wound healing activity. In excision wound model, treatment was continued till the complete healing of wound, in incision and dead space wound models, the treatment was continued for 10 days. For topical application, 5% w/w ointment of EEAS and AEAS were prepared in 2% sodium alginate. For oral administration, EEAS was suspended in distilled water using Tween 80 and AEAS was dissolved in distilled water. The wound healing was assessed by the rate of wound contraction, period of epithelialisation, skin breaking strength, granulation strength, dry granulation tissue weight, hydroxyproline, collagen and histopathology of granulation tissue. Malondialdehyde level was also estimated to evaluate the extent of lipid peroxidation. AEAS and EEAS significantly promoted wound healing activity in all the wound models studied. Increase in the rate of wound contraction, skin breaking strength, granulation strength, dry granulation tissue weight, hydroxyproline and collagen, decrease in the period for epithelialisation and increased collagenation in histopathological section were observed with EEAS and AEAS treated groups. EEAS and AEAS also significantly decreased the levels of lipid peroxidation. The present study is suggestive that EEAS and AEAS promote wound healing activity.

• Restorative Dentistry and Endodontics
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• 제41권1호
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• pp.6-11
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• 2016

Objectives: The purpose of this in vitro study was to evaluate the accuracy of working length (WL) determination of four electronic apex locators (EALs), namely, Root ZX (RZX), Elements diagnostic unit and apex locator (ELE), SybronEndo Mini Apex locator (MINI) and Propex pixi (PIXI) using Stainless steel (SS) and nickel-titanium (NiTi) hand files. The null hypothesis was that there was no difference between canal length determination by SS and NiTi files of 4 EALs. Materials and Methods: Sixty extracted, single rooted human teeth were decoronated and the canal orifice flared. The actual length (AL) was assessed visually, and the teeth were embedded in an alginate model. The electronic length (EL) measurements were recorded with all four EALs using SS and NiTi files at '0.5' reading on display. The differences between the AL and EL were compared. Results: The results obtained with each EAL with SS and NiTi files were compared with AL. A paired sample t test showed that there was a statistical significant difference between EAL readings with SS and NiTi files for RZX and MINI (p < 0.05). The accuracy of RZX, ELE, MINI and PIXI within ${\pm}0.5 mm$ of AL with SS/NiTi files were 93.3%/70%, 90%/91.7%, 95%/68.3%, and 83.3%/83.3%, respectively. Conclusions: The results of this study indicate that Root ZX was statistically more accurate with NiTi files compared to SS files, while MINI was statistically more accurate with SS files compared to NiTi files. ELE and PIXI were not affected by the alloy type of the file used to determine WL.

• 치위생과학회지
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• 제20권4호
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• pp.187-199
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• 2020

Background: Korean dental hygienists perform various tasks under the supervision of dentists in addition to the tasks listed in the law. Many meaningful studies have been conducted to determine the actual tasks of dental hygienists, but these studies did not show common results due to the differences in research methods or designs. Hence, this study aimed to review the reported data on the tasks of dental hygienists in Korea and to clarify them based on a systematic literature review. Methods: For the literature search, the COre, Standard, and Ideal model presented by the National Library of Medicine was referenced. Seven databases were searched for literatures published in Korea, including PubMed, and Google Scholar. Of the 352 studies found using key words, titles, and abstracts, 46 were finally extracted based on the first and second exclusion criteria. After confirming the tasks of Korean dental hygienists in 46 literatures, 136 tasks were listed and calculated as appearance rate in the literature. Results: The most common tasks in 46 studies were fluoride application (67.2%), radiography (65.4%), scaling (65.4%), sealant (60.7%), patient management and counseling (56.7%), tooth-brushing education (52.2%), impression taking with alginate (50.1%), and making temporary crowns (47.9%). The most mentioned tasks of dental hygienists in public health centers were fluoride application (100%), sealant (100%), oral health education (71.4%), public oral health program evaluation (71.4%), school fluoride mouth-rinsing program (71.4%), water fluoridation (57.1%), tooth-brushing education (57.1%), school oral health programs (57.1%), and public elderly oral health programs (57.1%). Conclusion: This study showed that Korean dental hygienists had 136 tasks by reviewing 46 related studies and that the main job of Korean dental hygienists was oral disease prevention including scaling, sealant, and fluoride application.

• 대한소아치과학회지
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• 제51권1호
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• pp.55-65
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• 2024

This study aimed to assess the accuracy of tooth widths, intermolar widths, and arch lengths acquired through two intraoral scanners, including iTero Element Plus Series (Align Technology, Santa Clara, CA, USA) and Trios 4 (3Shape, Copenhagen, Denmark), specifically on mixed dentition. A total of 30 subjects were divided into 2 groups, each undergoing both alginate impressions and intraoral scanning using either the iTero or Trios scanner. The plaster models were measured with a caliper, while the digital models were measured virtually. In the iTero group, all tooth width measurements exhibited differences compared to the plaster values, except for maxillary left lateral incisors (p = 0.179), mandibular right (p = 0.285), and left (p = 0.073) central incisors. The Trios group did not display significant differences in any of the tooth width measurements. Intermolar width comparisons for both groups indicated differences, except for mandibular primary canine to primary canine values (p = 0.426) in the iTero group. Regarding arch length, the mandibular anterior, maxillary right, and left arch lengths in the iTero group demonstrated larger caliper values than those of iTero. Conversely, in the Trios group, all parameters showed smaller caliper values, especially in upper anterior, maxillary right, mandibular right, and mandibular left arch lengths with significance (p = 0.027, 0.007, 0.003, and 0.047, respectively). Despite the differences between the two groups, digital models might be clinically suitable alternatives for plaster models. Pediatric dentists should carefully assess these differences, as a comprehensive evaluation would result in precise orthodontic treatment planning and favorable outcomes for young patients with mixed dentition.

• 대한소아치과학회지
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• 제33권3호
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• pp.510-521
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• 2006

본 연구는 총생에 영향을 미치는 중요한 요소가 무엇인지 알아보기 위해 시행하였으며 총생군 50명(남녀 각 25명)과 정상 교합군 40명(남녀 각 20명)에서 상하악 모형을 제작하여 이를 3D model로 변환하였으며 컴퓨터 상에서 치아의 근원심폭경과 악궁의 길이 변연길이, 견치간 폭경, 구치간 폭경을 계측 및 분석하여 다음과 같은 결론을 얻었다. 1. 치아크기 분석시 상악에서는 측절치와 제1,2소구치에서 총생군의 치아가 더 크게 나타났으며(P<0.05) 나머지 치아의 크기 및 치아크기합계에서는 차이가 없었다(P>0.05). 2. 하악에서는 중절치와 견치 및 제 1,2 소구치의 크기 그리고 치아크기합계에서 군간에 차이가 관찰되었다(P<0.05). 3. 악궁에 대한 평가시 상악에서는 악궁 변연길이와 구치간 폭경은 총생군에서 더 작았고 견치간 폭경은 총생군에서 더 컸으며 (P<0.05), 악궁의 장경에 있어서는 차이가 없었다(P>0.05). 4. 하악에서는 악궁 변연길이는 총생군에서 더 작았으나(P<0.05), 악궁의 장경 및 구치간 폭경, 견치간 폭경에서는 차이가 인정되지 않았다(P>0.05). 5. ALD와 각 변수간의 상관관계를 분석한 결과 상악에서는 악궁 변연길이와$({\gamma}=-0.348)$ 구치간 폭경 $({\gamma}=-0.343)$, 소구치크기와$({\gamma}=-0.335)$ 비교적 높은 상관관계를 보였고 하악에서는 치아크기합계를$({\gamma}=-0.454)$ 비롯한 모든 치아크기와 높은 상관관계를 보였다. 6. 석고모형 계측치와 삼차원모형 계측치를 비교한 결과 석고모형에 비해 삼차원모형 계측치가 좀더 크게 계측되었으며 (P<0.05), 오차의 범위는 0.01-0.47mm이었다. 7 검사자내의 오차를 분석하기 위해 상관분석을 시행한 결과 석고모형 계측시 보다 삼차원모형 계측치의 재현도가 높음을 알 수 있었다(P<0.05). 이상의 결과를 종합하여 볼때, 총생이 존재할 때 상악에서는 큰 치아와 좁은 악궁이 복합적으로 기여하며 하악에서는 치아 크기가 더 중요한 요소로 작용하는 것으로 생각된다. 또한 본 연구에서 사용된 삼차원모형은 현재 적절하게 사용가능하지만 향후 개선 보완이 필요할 것으로 사료된다.

• 유기물자원화
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• 제10권2호
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• pp.100-116
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• 2002

농작물에 영양분을 공급하거나 식물의 생장촉진, 식물 병원균의 억제 등을 위하여 토양에 미생물이 투입된다. 대표적인 예가 질소고정 공생세균과 Pythium, Rhizobium 등이다. 이들이 투입되어 성공적으로 작용하려면 생존하여 충분한 밀도로 집략을 형성하여야 한다. 이들의 생존과 집략화에 미치는 영향은 생물적인 인자와 비생물적 인자에 의해 좌우된다. 생물적 인자중에서 중요한 것은 포식과 경쟁, 비생물적 인자 중에서 중요한 것은 물의 장력 유기탄소, 무기영양분(N, P), pH 등이다. 토양의 토성과 소공극 분포도 투입된 미생물의 생존과 활착에 중요한 역할을 담당한다. 또한 미생물에 대한 토양생태계의 선택성은 접종 세포 개체군의 활착에 있어서 중요하다. 예를 들면 항생제의 사용에 의한 토착미생물의 제어, 계면활성제를 분해하는 Psendomonas종을 투입하는 경우이다. 투입미생물의 활착을 증진시키기 위하여 이탄, 점토 등의 수송체를 동시에 첨가할 수 있는데 이들은 투입미생물에게 보호적인 미소서식지를 만듦으로서 토양중에서 세균을 보호할 수 있다. 또한 세균이나 공업용 효소를 부동화시키기 위한 수송체로서 유기성 중합체가 사용되고 있다. 이러한 물질들의 예를 들면 아질산칼륨, agarose, k-carrageenan 등이다. 이들도 미소서식처를 제공하므로서 투입미생물의 활착을 돕는 역할을 한다.