• 대한소아치과학회지
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• 제31권2호
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• pp.273-279
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• 2004

최근에 소개된 single high-intensity LED 중합기는 이전의 LED 중합기에 비해 높은 광도를 가지며 짧은 중합시간에 적절한 물성을 가질 수 있다고 한다. 본 연구는 single high-intensity LED 중합기의 중합성능을 평가하기 위하여 거리에 따른 중합도를 조사하였다. Mylar strip사이에 복합레진(Filtek Z250)을 넣고 압접시켜 만든 얇은 필름형 시편을 LED 중합기(Elipar Freelight 2, 10초), 플라스마 중합기(Flipo, 6초)와 할로겐 중합기 (XL3000, 20초)를 사용해 0mm, 2mm, 4mm, 6mm에서 광도를 측정하고 중합시켰다. 중합된 시편을 Fourier Transform Infrared Spectrometer(FTIR)를 이용해 중합도를 측정한 후 다음과 같은 결론을 얻었다. 1. 모든 중합기에서 거리가 증가할수록 유의하게 광도가 감소하였으며 LED중합기의 경우 6mm에서 다른 중합기에 비해 가장 많은 광도 감소율을 보였다(p<0.05). 2. 모든 중합기에서 거리가 증가함에 따라 4mm까지는 중합도가 감소하였지만 유의한 차이는 보이지 않았다(p>0.05). 하지만 4mm와 6mm사이에서는 모든 중합기에서 유의하게 감소하였다(p<0.05). 3. 각 거리에 따른 중합기간의 중합도 차이는 0mm, 2mm, 4 mm에서 LED중합기가 다른 중합기보다 유의하게 높은 중합도를 보였으며 (p<0.05) 플라스마 중합기와 할로겐 중합기 사이에서는 유의한 차이가 없었다. 하지만 6 mm에서는 모든 중합기 사이에 유의한 차이를 보이지 않았다(p>0.05).

• Restorative Dentistry and Endodontics
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• 제21권2호
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• pp.652-663
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• 1996

The purpose of this study was to evaluate the tensile bond strength to tooth structure of composite resin and glass ionomer cement according to filling methods and light curing units. In this study, two class V cavities were prepared on the buccal surface of each tooth of 140 extracted human molars, and they were randomly assigned into 3 experimental groups with 40 teeth and control group with 20 teeth. And then, each experimental groups subdivided into 2 groups(A,B) according to light curing units. The cavities of each group were filled with the CLEARFIL FII self curing resin(Control Group), Z-100 light curing resin(Group 1), Vitremer$^{TM}$ light curing glass ionomer cement(Group 2) and Z-100 light curing resin over the Vitrebond$^{TM}$ liner(Group 3). And subdivided A Group used Argon Laser(SPECTRUM$^{TM}$, U.S.A.), B Group used XL 1,000 curing light (3M, U.S.A.). The specimens underwent temperature changed from $5^{\circ}C$ to $55^{\circ}C$ five hundred times. After thermocycling, specimens were stored in 100% relative humidity at $37^{\circ}C$ for 24 hours. And then, the tensile bond strength of specimens were calculated with Universal Testing Machine(AGS-100A, Japan). The results were as follows : 1. Among the experimental groups, the group 2-B showed the highest tensile bond strength ($18.89{\pm}7.80$) and the group 1-A showed the lowest tensile bond strength ($11.68{\pm}2.28$). There was significant difference between group 2-B and group 1-A(p<0.01). 2. Between the light curing units, the XL 1,000 unit showed higher tensile bond strength ($16.63{\pm}3.20$) than that of the Argon Laser unit ($13.73{\pm}2.30$). There was significant difference between XL 1,000 and Argon Laser(p<0.01). 3. About filling methods and materials, the group 2 showed the highest tensile bond strength ($17.56{\pm}1.89$) and the group 1 showed the lowest tensile bond strength($13.03{\pm}1.90$). There was significant difference between group 2 and group 1,3(p<0.01). In conclusion, the results showed that the glass-ionomer cement that cured by XL 1,000 light curing unit demonstrated significantly higher tensile bond strength than other curing unit and filling methods.

• Journal of Ginseng Research
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• 제25권3호
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• pp.127-129
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• 2001

새로운 미생물 오염도 검사방법인 ATP-bioluminescence 방법을 인삼분말에 적용한 결과 인삼분말에 오염된 세균수가 약 10,000 CFU/g 이상인 경우에는 세균수가 증감함에 따라 ATP의 양이 비례적으로 증가하였다. 그러나 세균수가 10,000 CFU/g 이하일때는 ATP 의 증가 및 결과의 상관성이 인정되지 않았다. 따라서 이 방법은 세균의 오염도가 높은 인삼 분말($\geq$10,000 CFU/g) 에서 신속하게 미생물을 측정하여 제품의 품질을 관리하는데 유용한 방법이 될 수 있을 것으로 생각된다.

• 한국도서관정보학회지
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• 제40권1호
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• pp.253-274
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• 2009

효율성은 산출물의 가치와 그 산출물의 생산과정에서 소요되는 투입물가치의 비율로 나타낸다. DEA모형은 효율성을 여러 가지 투입물의 가중평균에 대한 산출물 가중평균의 비율로 표시하며, 특정 의성결정단위의 효율성을 유사한 투입 산출구조를 가지는 준거집단과 비교함으로써 상대적인 측면에서 측정하는 방법이다. 본 연구는 DEA모형을 이용하여 국립대학도서관의 효율성과 효율성 개선에 관한 분석을 시도하였다. 투입변수로는 직원수, 시설면적, 예산, 장서량을 사용하였고, 산출변수로는 자료실이용자수, 대출책수, 상호대차이용건수를 사용하였다. 그 결과 전국 26개의 국립대학도서관 중 효율적인 도서관은 2007년, 2006년, 2005년에 각각 10개, 9개, 9개로 나타났다. 또한 비효율적인 국립대학도서관의 경우 투입물을 줄이고, 산출물을 늘여야 할 정보들을 제시하였다.

• 자원ㆍ환경경제연구
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• 제9권2호
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• pp.349-371
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• 2000

Data Envelopment Analysis model is a linear programming based technique for measuring the relative performance of organizational units where the presence of multiple inputs and outputs makes comparison difficult. A common measure for relative efficiency is weighted sum of outputs divided by weighted sum of inputs. DEA model allows each unit to adopt a set of weight that shows it in the most favorable light in comparison to the other unit. In this paper, we present the mathematical background and characteristics of DEA model, and give a short case study where we apply the DEA model to evaluate the relative efficiencies of 51 global electricity companies. The technical efficiency and scale efficiency are also to be investigated. Generating capacity and the number of employees are used for input data, and revenue, net profit and electricity sales are used for output data. We find that the companies with 100% relative efficiency are only 9 among 51 electricity companies. And the technical and scale efficiency of KEPCO is 98.7% and 78.89%, respectively. This means that the inefficiency of KEPCO is caused by the scale inefficiency. The analysis shows that the employees should be decreased by 15% at minimum to get the 100% efficiency. The result suggests that KEPCO needs the structural reform to improve the efficiency.

• 대한임상검사과학회지
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• 제53권4호
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• pp.326-332
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• 2021

면봉을 사용한 샘플링 방법은 의학, 생태학, 생명공학, 법의학 및 오염 정도 모니터링 시스템과 같은 다양한 연구 분야에서 유용하다. 샘플링에서 채취 시약은 중요한 요소 중 하나이다. 시료를 장기간 보관해야 하는 경우에는 시료 채취 키트와 시료 보관 온도가 매우 중요하다. 이 연구의 목적은 별도의 배지 없이, 세 가지 채취 시약과 세 가지 보관 온도가 살아있는 세균의 생균 수에 미치는 영향을 확인하는 것이다. 대표적인 환경 세균으로 E. coli와 S. aureus를 선정하였다. 증류수(DW), 멸균된 인산염 완충액(PBS), Tris-EDTA (TE) 버퍼를 채취 시약으로 사용하여 샘플링한 후, 22, 4, -70℃에서 보관을 진행했다. 각 채취시약 및 보관 온도가 시료에 미치는 영향은 RLU와 CFU로 결과로 비교하였다. -70℃ 보관 온도와 TE 버퍼를 사용할 때 CFU와 RLU 값은 다른 조건에서보다 일정하게 유지되는 경향이 보였다. 따라서 이 연구는 시료가 채취 직후 -70℃에서 보관되어야 하며, 채취 시약으로 TE 버퍼와 함께 사용하는 것이 좋다는 것을 시사한다.

• Structural Engineering and Mechanics
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• 제90권3호
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• pp.287-299
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• 2024

Composite skew plates are aesthetically appealing light weight structural units finding wide applications in floors and roofs of commercial buildings. Although bending and vibration characteristics of these units have received attention from researchers but the domain of first and progressive failure has not been explored. Confident use of these plates necessitates comprehensive understanding of their failure behavior. With this objective, the present paper uses an eight noded isoparametric finite element together with von-Kármán's approach of nonlinear strains to study first ply and progressive failure up to ultimate damage of skew plates being subjected to uniform surface pressure. Parameters like skew angles, laminations and boundary conditions are varied and the results are practically analyzed. The novelty of the paper lies in the fact that the stiffness matrix of the damaged plate is calculated by considering material degradation locally only at failed points at each stage of first and progressive failure and as a result, the present outputs are so close to experimental findings. Interpretation of results from practical angles and proposing the relative performances of the different plate combinations in terms of ranks will be of much help to practicing engineers in selecting the best suited plate option among many combinations.

• 아동학회지
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• 제28권2호
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• pp.19-37
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• 2007

In this study of the relative effectiveness of constructivist and non-constructivist approaches to shadow activity for young children, 59 children in two kindergarten classes were assigned to constructivist or non constructivist conditions. Each group participated in 12 units covering shadow search, shadow making, changing shadow size, changing shadow position, and shadow disappearance. Analysis of covariance of differences between the mean scores of the two groups on the posttests of shadow concepts and scientific attitudes revealed that the children in the constructivist group performed better than the children in the non-constructivist group. This confirms the constructivist approach to shadow activities as good science activities for young children by promoting their active experimentation using reasoning about light to foster spatio-causal relations construction.

• Restorative Dentistry and Endodontics
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• 제22권1호
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• pp.267-277
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• 1997

The purpose of this study was to evaluate the shear bond strength of light-cured glass ionomer cements to dentin surface according to curing time induced by argon laser. In this study, 160 extracted human molars with sound crown were used. The dentin surface of these teeth were exposed with high speed diamond bur under water spray and polished with 120, 320, 400, 800, 1200 grits sand paper. 160 extracted human molars were randomly assigned into four groups (control, experimental 1, 2 & 3) with 40 teeth each. Control group used a visible light curing unit, XL 1000(3M Co., U.S.A) and experimental groups used argon laser($SPECTRUM^{TM}$). And then each group subdivided into two groups (A, B) according to filling materials. Subdivided A group used Fuji II LC(GC Co., Japan), B group used Vitremer(3M Co., U.S.A). The curing units and curing time of each group were as follows : Control group : visible light, 40 seconds Experimental group 1 Experimental group 2 Experimental group 3 : argon laser, 10 seconds : argon laser, 20 seconds : argon laser, 30 seconds The glass ionomer cements were bonded to dentin surface of each specimen. The specimens were stored in 100% relative humidity at 37"c for 7days. And then, the shear bond strength were measured by universal testing machine(Shimatzu Co. Japan) at crosshead speed of 5mm/min and 100kg in full scale and analyzed statistically. The following results were obtained : 1. Experimental group 2-A showed the highest shear bond strength with $9.87{\pm}1.24$ kgf and control group B showed the lowest shear bond strength with $4.08{\pm}0.78$ kgf(P<0.01). 2. The Fuji II LC showed higher shear bond strength with $9.49{\pm}1.24$ kgf than that of the Vitremer with $4.23{\pm}1.24$ kgf. There was significant difference between Fuji II LC and Vitremer(p<0.01). 3. There was no significant differences among experimental groups according to curing time induced by argon laser. 4. There was no significant differences between control group and experimental groups according to curing units.

• Journal of Korean Biological Nursing Science
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• 제23권4호
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• pp.339-346
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• 2021

Purpose: To determine the extent of environmental contamination and the effect of disinfection around patients with carbapenem-resistant Enterobacteriaceae (CRE) using adenosine triphosphate (ATP) measurements and microbial culture tests. Methods: The subjects of this study were 10 patients hospitalized in a single room due to CRE from April 13 to 21, 2021. One hundred and sixty samples were collected using cotton swabs from the patients' environment including the surface and drain of sinks and toilet seats before and after disinfection of the room after discharge. Twenty-one samples were collected from the nurses' personal digital assistants (PDAs), keyboards, and computer mice before disinfection. The relative light units (RLUs) and CRE colony-forming units (CFU) of 181 samples were measured using ATP test equipment and chrome agar plates, respectively. Results: The highest RLUs were measured at the sink drains before and after disinfection. Four CRE samples from the sink drains (2), sink surface (1), and toilet bowl (1) before disinfection were cultured. Based on the failure criteria (≥ 250 RLU/cm² and ≥ 1 CFU/100 cm²), 90 % and 50 % of the samples from the drain exceeded the failure criteria before and after disinfection, respectively. In the culture tests, CRE was not detected after disinfection. Conclusion: According to the RLU and CFU measurements of drain samples, disinfection was not effective. Thus, improvements in the disinfection methods of drains, as well as more efficient and systematic environmental decontamination and disinfection evaluation tools, are needed to accurately evaluate the effectiveness of disinfection in various places.