상아질에 적용된 재 습윤제가 미세인장 결합강도에 미치는 영향

강희영,조영곤,김종욱,박병철,유상훈,진철희,최희영,기영재 大韓齒科保存學會 2004 Restorative Dentistry & Endodontics Vol.29 No.2

This study investigated that the effect of rewetting agent on dentinal microtensile bond strength (μTBS). Human molars were sectioned to expose the superficial dentin surfaces. Samples were divided into two groups according to type of adhesives-Single Bond (S) and One-Step (0)], and again subdivided into five groups by different dentin surface treatment-dry for 15s (D) , blot dry (BD) or dry for 15s, and rewet with different rewetting agents[distil1ed water (DW), Gluma Desensitizer (GD) and Aqua-Prep (AP)]for 30s. After application of adhesive, composite resin was built up on the bonding surface. Each tooth was sectioned to obtain stick with 1mm^(2) cross sectional area and the μTBS was determined by EZ test. In the S group, the mean μTBS of GD, AP and BD group was significantly higher than that of DW and D group (p < 0.05). In the 0 group, the mean μTBS of AP, GD, BD and DW group was significantly higher than that of D group (p < 0.05). The data suggested that Gluma Desensitizer and Aqua-Prep could be successfully used as rewetting agents, and Distilled water could be acceptable in aceton based adhesive system only.

자가 산부식 프라이머의 적용시간이 상아질의 미세인장 결합강도에 미치는 영향

조영곤,이영곤,김종욱,박병철,김종진,최희영,진철희,유상훈 大韓齒科保存學會 2004 Restorative Dentistry & Endodontics Vol.29 No.5

This study evaluated the influence of application time of self-etching primers on microtensile bond strength (μTBS) to dentin using three self-etching primer adhesive systems. Dentin surfaces were exposed from forty-eight human molars. They were conditioned with three self-etching primers (Clearfil SE Bond [SE], Unifil Bond [UF], Tyrian SPE + One Step Plus [TY]) and different primining times (10s, 20s, 30s and 40s). Composite resins were bonded to dentin surfaces and specimens were made. μTBS was tested and statistically compared using by one-way ANOVA and Tukey's Test. The results of this study presented that priming time for 10s in SE and UF groups and for 30s and 40s in TY group was highly decreased μTBS to dentin.

법랑질 접착에 대한 습윤 효과

고근호,조영곤,진철희,유상훈,김종욱,박병철,기영재,최희영,김종진 大韓齒科保存學會 2004 Restorative Dentistry & Endodontics Vol.29 No.3

This study evaluated the microleakage and interfacial gap between enamel and composite resin under the dry and wet condition of the enamel surface, V shaped class 5 cavities were prepared on the occlusal portion of extracted human molars. Samples were divided into three groups: D group (air dry for 10-15s), BD group (blot dry with moist cotton pellet), and DR group (air dry for 10-15s and rewet with Aqua-Prep F for 20s). Cavities were filled using Aelitefil composite resin after applied One-Step. Microleakage was tested by 2% methylene blue dye solution and the data were statistically analysed by Kruskal-Wallis test and Mann-Whitney test. Also Enamel-resin interface was observed under SEM. Group BD showed statistically lower microleakage than group D (p〈0.05). but there was no statistically significant difference between group BD and DR (p)0.05). At the enamel-resin interface, group D showed the gap of 2 ㎛ thickness, but group BD and DR showed close adaptation. In conclusion, the use of blot dry and rewetting agent (Aqua-Prep F) resulted in decreased microleakage and improved adhesion between enamel and resin when using One-Step.

복합레진의 지연충전이 미세인장 결합강도에 미치는 영향

박현식,조영곤,박병철,김종욱,최희영,김종진,진철희,유상훈,기영재 大韓齒科保存學會 2004 Restorative Dentistry & Endodontics Vol.29 No.3

The purpose of this study was to evaluate the effect of immediate or delayed composite resin filling on dentinal microtensile bond strength (μTBS) after applied the adhesive. The coronal dentin of human third molars was exposed. Single-Bond or One-Step was applied on the dentin surfaces, and composite resin were constructed immediately (group 1) or 5 min., 10 min., 15 min., 20 min. and 30 min. (groups 2-6) after an adhesive was applied. The specimens were sectioned and made bar-shaped. Each surface area of them was about l ㎟. The RBS test was performed by EZ test. The results were analysed by One-way ANOVA and Tukey's test at 95 % significance level. The results suggested that the μTBS of Single-Bond to dentin was decreased when the composite resin was constructed 20 min. and 30 min. after Single-Bond was applied. But the μTBS of One-Step was not affected by delayed composite resin filling.

일반화지수분포와 지수화 지수분포를 이용한 유한고장 소프트웨어 신뢰성장 모형에 관한 비교 연구

김희철 남서울대학교 2007 남서울대학교 논문집 Vol.13 No.4

Finite failure NHPP models presented in the literature exhibit either constant, monotonic increasing or monotonic decreasing failure occurrence rates per fault. In this paper, Goel‘s generalized and the exponentiated exponential distribution reliability model which maked out efficiency substituted for Gamma and weibull model (2 parameter shape illustrated by Gupta and Kundu ) was reviewed. Algorithm to estimate the parameters used to maximum likelihood estimator and bisection method, model selection based on SSE for the sake of efficient model, was employed. Analysis of failure using real data set for the sake of proposing shape parameter of the generalized exponential distribution and the exponentiated exponential distribution reliability model was employed. Key words : exponentiated exponential distribution, NHPP, SSE

지수가중이동평균관리도를 이용한 제조공정관리 실증분석

김희철 남서울대학교 2008 남서울대학교 논문집 Vol.14 No.2

From the subdivision of this quality process analysis, basic plan needs the side of the quality control. In this paper, we discuss process analysis using exponentially weighted moving average chart. In advance, setting the level of quality, the weight selected and determine the management changes using the exponentially weighted moving average chart. Weight to the quality of pre-conditions for the exponentially weighted moving average chart for the official results shall determine the change serious situation occurs outside the lower limit or upper limit, About that time, quality error look to claim, believe a new quality to be applied.Key Words : Exponentially Weighted Moving Average Chart, Manufacturing Process Management data, Process Analysis.

여행사 고객 서비스 품질 특성 요인분석에 관한 연구

김희철 남서울대학교 2007 남서울대학교 논문집 Vol.13 No.3

The survey study on the influence factor Analysis of quality service elements for 285 customer service of a tourist agency carry out. In this survey, element of quality customer service(such as reliability, responsiveness, assurance, empathy etc.,) is considered. The purpose of this study is to examine element of quality customer service and to investigate the important factors affected by that. The results have processed through the analysis are summarized as follows. First, the determinative variables, such as reliability, assurance have had a positive influence, but elements of responsiveness and empathy have had a negative effected on that. Second, in factor analysis, power of explaining with 1 factor( unique duty of tourist agency) have had 19.8 %, power of explaining with 2 factor( members duty of the staff of tourist agency ) have had 12.6 %, the 3 factor( elements of customer service ) is 11.7 %. the 4 factor( elements of interest ) is 11 %, the 3 factor( elements of request and profit ) is 10 %. This results suggest that main element customer service of a tourist agency is factors such the unique duty of tourist agency, members duty of the staff of tourist agency, elements of customer service Keyword : Influence factor , Quality service, Determinative variable, Service of a tourist agency.

곡선회귀모형을 이용한 경제활동인구 통계분석 및 예측에 관한 연구

김희철 남서울대학교 2012 남서울대학교 논문집 Vol.18 No.1

In this study, to analyze changes in the economically active population from January 2005 to March 2012 monthly statistical analysis of the economically active population were predicted using a cubic curve regression model and logistic growth model predictions have been compared to the model, preferably a relatively can be seen. The value of the coefficient of determination than the other models for the value of third-order model predictions and also the values ​​of explanatory power appeared significantly smaller than the other models appear cubic curve model appears to have an efficient model. Predict the future in terms of the time the third model or logistic growth curve model predictions were higher than those of the model with logistic growth model is almost similar to the model a slightly higher predictive logistic models are being evaluated. Thus, an average cubic curve model has the highest logistic model owing to the small two models to use for an average of preparedness is required and the standard deviation and variance ie, a scatter diagram of the cubic curve model has the highest logistic model is relatively small If you want to use these models because the variation is necessary for preparedness. Therefore, we want to identify the economically active population, these forecasting methods when used as prior information of the future population, economic activity will help identify environmental patterns could be applied. Future patterns of these economically active population by environment approach or repair parts for the repair estimate and test approach is expected. Key Words : Curve Regression Model, Coefficient of Determination, Mean Squared Error

고층건물 수직구조요소의 축소량 산출에 관한 연구

김희철,정은호 慶熙大學校 1997 論文集 Vol.26 No.-

An estimation of shortening in vertical members for the steel structure is not difficult to predict because of its characteristics of deformation. However. it is not easy to estimate the quantity of shortening for the concrete and composite structural systems. Total shortening of both concrete and composite vertical members should be obtained by separating the instantaneous elastic shortening and inelastic shortening caused of inelastic behavior of creep and shrinkage. The main purpose of estimating the total shortening of vertical structural members is to compensate the differential shortening between adjacent members. Differential shortening has to be estimated so that it can be ascertained whether the differential shortening effects are significant or not. If they are significant to effect other structural members, in the design of joints, and in architectural features so as to produce smaller differential effects. Column Shortening Calculation Program(CSCP) was developed to predict the shortening amount of vertical structural members. The developed program can estimate both elastic and inelastic shortening of reinforced concrete members. The verification CSCP was accomplished by comparing the results to the other program developed by Portland Cement Association(PCA).

아파트 전세가격지수의 통계분석 및 예측에 관한 연구

김희철 남서울대학교 2011 남서울대학교 논문집 Vol.17 No.2

In this study, changes in apartment rental price index to analyze the February 2005 to September 2011 monthly rental price index, using the results of apartment rental price index is an average over a large apartment in a small apartment with high but variation range compared to the big show a higher number of small differences in the more than a large fluctuation appears, this highly compact and charter price index formation was higher in the past in recent years an increasingly large and small apartment appear highly similar or smaller than the increasingly large trends have shown that appear significantly higher. And large and small apartment rental prices are not the same exponent was found to average together. Apartment rental prices eventually predict the future, rather than a large apartment in a small apartment rental prices than a large mini's showing more and more drastically than in a small charter price formation is predicted to rise by more. This paper into the apartment, the seller, and marketing professionals with the information prior to their advantage this predict the future pattern of apartment rental prices might help identify environmental think you are feeding. The charter price index future with the environment approach to pattern and estimate repairs and repairs to the black part is expected to approach. Key Words :Monthly Rental Price Index, Explanatory Power, Levene Test for Equal Variances