광원의 종류에 따른 콤포짓트레진의 중합도

윤태호,이용근,임범순,김철위 대한치과기재학회 2001 대한치과재료학회지 Vol.28 No.1

콤포짓트레진의 중합도와 속도는 광원의 종류와 광조사 시간에 따라 영향을 받는다. 현재 할로겐 램프를 중합에 많이 사용하고 있으나 전구의 수명이 짧고, 시간경과에 따라 광선의 출력이 감소하므로 중합도는 낮아져 물성이 감소하고 수복물이 실패할 가능성도 높다. 이를 개선하기 위하여 콤포짓트레진 중합에 사용할 수 있는 LED (blue light emitting diode) 와 플라즈마 아크 기술이 소개되었다. 이 실험에서는 3 종의 광원(할로겐 램프, LED 및 플라즈마 아크) 에서 광조사시간을 달리하여 광에너지의 총량을 변화하는 조건으로 점주도가 서로 다른 3 종의 콤포짓트레진에서 깊이에 따른 중합도를 측정하여 각 광원의 효율성을 상호 비교하였다. 할로겐 램프, LED 및 플라즈마 아크 조사기로 광에너지 총량이 각각 8J/㎤와 16J/㎤ 이 되도록 중합하고 표면에서 1, 2, 3 및 4mm 위치에서 100㎛ 의 두께로 절단하였다. 시편 두께가 50~70㎛ 가 되도록 연마하고 FT-IR 로 표준기선법에 따라 중합직후의 중합도를 측정하였다. 중합방법 및 광조사 부위에서 깊이에 따른 평균 중합도를 계산하여 3 원 분산분석 및 Scheffe 의 방법에 따라 유의수준 0.05 에서 검정하였다. 이 실험에서 다음과 같은 결과를 얻었다. 재료, 깊이 및 광조사 시간 모두 전환율에 유의한 영향을 주었다(p〈0.01). 3 종 광원의 표층에서 1mm 깊이에서의 중합도는 저점도(RVN) 〉중점도(Z25) 〉응축형 콤포짓트레진(SRF) 순이었다(p〈0.05). 3종 광원의 중합도는 유의한 차이를 볼 수 없었다(p〉0.05). 3종의 조사광원 모두에서 광에너지 총량을 2배로 증가한 경우, 중합도는 2mm 깊이까지는 유의한 차이가 없었으나(p〉0.05), 3mm 부터는 광에너지 총량 증가에 따라 유의하게 증가하였다(p〈0.05).

洛東江 河口에 인접한 南海岸 海成沖積土의 工學的 特性

尹忠燮,尹龍喆 慶尙大學校 1996 論文集 Vol.35 No.1

This study was carried out to find engineering properties of the alluvial soil in tidal land of the south coast. The main results are as follows; 1. The engineering properties at any deposit depth is estimated as follows; W?=-0.005Z²+1.14Z+42(%) q?= 0.291Z+0.26(t/㎡) C?= 0.133Z+0.32(t/㎡) P?= 0.788Z+0.153(t/㎡) P?= 0.526+0.5(t/㎡) 2. The relationships among the properties of soil are follows; r?=0.013(183-w?)(g/㎤) C?= 1.24(C?-0.008)(㎏/㎠) C?= 0.742(e?-0.683) C?= 0.015(w?-14.13) C?= 0.013(w?-6.2)

광조사 방법에 따른 치과용 심미수복재의 중합수축

윤태호,이용근,임범순,김철위 대한치과기재학회 2000 대한치과재료학회지 Vol.27 No.4

Dental resin composites were introduced commercially in the mid-1960s for the restoration of anterior teeth. Since their advent, resin composites have undergone significant development, which continues to improve the longevity and application of resin composite restorations. Despite the development of new dentin-bonding agents, no system is currently available that completely withstands the formation of contraction gaps at the cementum/dentin-restoration junction, due to the unavoidable polymerization shrinkage of the resin composite during setting, therefore, a major aim of this study was to minimize or control the polymerization shrinkage of composites allowing flow of resin during setting reaction. A thermal dilatometer (DIL 402C, TASC 414/3A Controller, Netzche, Germany) was used to measure and compare conventional continuous cure and pulse cure polymerization shrinkage of seven light curing dental composites and three compomers. For conventional cure, restorative material were polymerized for 2 minutes using VIP (Bisco, U.S.A.) with 400 ㎽/㎠ intensity. After then, further polymerization was allowed for next 12 minutes that total 14 minutes of shrinkage was measured. For pulse cure, material was pre-polymerized irradiating light for 5 seconds with 200 ㎽/㎠ and post-ploymerized 3 minutes later with 400 ㎽/㎠ for 2 minutes. 9 minutes were allowed for further polymerization that total 14 minutes of shrinkage was measured. Polymerization shrinkage ranged from 3.758 ㎛/㎜ (SYC) to 6.897 ㎛/㎜ (P60) for conventional cure and 4.026 ㎛/㎜ (FLT) to 6.996 ㎛/㎜ (SRF) for pulse cure. The highest difference between the two methods was found at EAN (2.713 ㎛/㎜), followed by F20 and CRA which showed significant differences of 2.133, 1.274 ㎛/㎜ respectively (p<0.05). The least difference was found at SYC (0.489 ㎛/㎜). Universal resin composite group showed the highest polymerization shrinkage (6.514±0873 ㎛/㎜), and flowable composite showed the least shrinkage (4.139 ㎛/㎜). Packable composite showed 5.090±1.906 ㎛/㎜, and compomers showed 6.129±2.652 ㎛/㎜.

정보통신시장에서 다양한 혁신상품 수용의도간 연관성에 관한 연구 : 컨버전스 서비스를 중심으로 Focused on Convergence Services

김용철,주영혁,윤석훤 정보통신정책학회 2005 정보통신정책연구 Vol.12 No.1

정보통신시장에서는 유무선통합, 통방융합 추세로 인해 다양한 혁신상품들이 출시되고 있다. 본 연구에서는 한 소비자가 갖고 있는 다양한 혁신상품의 수용의도를 파악하여, 특정 혁신상품의 수용의도에 다른 혁신상품의 수용의도가 미치는 영향을 파악하였다. 연구 결과, 통방융합 혁신상품의 수용의도에 유무선통합 혁신 상품의 수용의도가 영향을 미치는 것으로 나타났다. 이를 통해 혁신상품 목표고객 선정에 대한 전략적 시사점과 수용의도를 기반으로 한 소비자 혁신성 연구의 가능성이라는 이론적 시사점이 도출되었다. Recently, there have been so many innovative services introduced in information and communication market according to the development of ICT and the convergence of related industry. In this article, the authors examine the impact of adoptions of related innovative services on adoption of a innovative service in the view of adoption intention. Predictions are developed and tested using survey data(n=800) from professional marketing research firm. Result shows that adoption of each innovative service is significantly influenced by adoptions of other innovative services. This research has implication for targeting of innovative services strategically and measuring of consumer innovativeness practically.

시차주사열량분석기를 이용한 치과용 접착시멘트의 경화기전 및 반응열에 관한 연구

김철위,이용근,윤태호,김효종,남세진 大韓齒科器材學會 2000 대한치과재료학회지 Vol.27 No.3

The working time of dental cement has a close relation with the setting time, where the setting reaction can be said as the result of the chemical reaction between cement liquid and powder. The purpose of this experiment was to investigate the setting characteristics and setting rate of dental cements by measuring the exothermic heat(Joule/gram) from the setting reaction at specified times using a differential scanning calorimeter (Differential Scanning Calorimeter, DSC 204, TASC 414/3A Controller, Netzche, Germany). Graphs of time-exothermic heat at 37℃ isothermal condition, showing the setting reaction of dental cements were plotted. Three types of luting cements studied were zinc-phosphate cement (ZPC), polycarboxylate cement (PCC), and glass ionomer cement (GIC). The effects of powder-liquid ratio on the setting characteristics of cements were also included. The amount of heat (calory) released per one gram of cement was calculated at each specified time, and was analyzed. ANOVA and Scheff's multiple comparison test (p=0.05) were used for statistical analysis using SPSS/PC+. The setting rate of cement was not constant during the setting reaction, and different setting characteristics were observed depending on the type of cement and powder/liquid ratio. Generally, 70∼90% of the setting reaction, measured by the exothermic heat release, occurred within 5 minutes after mixing. The exothermic heat released by ZPC was very high immediately after mixing, and the duration of the heat release was prolonged compared with other cements. The exothermic heat release of PCC finished most rapidly. It was generally observed that the amount of heat release (rise in temperature) per one gram of cement was highest for ZPC, followed by GIC, and then PCC. However, heat release during the first 2∼5 minutes after mixing was highest for GIC, followed by ZPC and then PCC. According to the Scheff's multiple comparison test, the duration of the total setting reaction did not show any significant difference among the cements(p>0.05), and also among the different power/liquid ratio groups(p>0.05). It was observed that more heat was released with the lower powder/liquid ratio than the higher powder/liquid ratio.

서울시 정수장의 필요 소독능 관리 현황

염철민,조순행,윤제용 대한상하수도학회 2002 상하수도학회지 Vol.16 No.4

This study was designed to evaluate the disinfection performance in water treatment plants (WTPs, n=16) in Seoul. Disinfection requirement based on the SWTR (Surface Water Treatment Rule) of the U.S. (0.5-log and 1.5-log Giardia removal) was applied in estimating the disinfection performance of WTPs in Seoul. The water treatment process or unit steps used for this evaluation includes inlet pipe line, flocculation basin, sedimentation basin, clearwell, and storage tank. The major results are as follows. First, it was found that all WTPs in Seoul meet a virus removal criteria (4-log removal). Second, the baffling factors (T_10/T) in treatment processes used for this evaluation which was selected by Seoul Water Works were found 1.0 for inlet pipe line, 0.2 for flocculation basin, 0.7 for sedimentation basin, and 0.5 for clearwell, respectively. Since the selection of right baffle factors (T_10/T) is critically important, further rationalization is required in this process. Residual chlorine concentration in clearwell varied from 0.4 to 1.0mg/L. Third, for the disinfection criteria of 3-log Giardia inactivation, almost all of disinfection data which were provided by Seoul Water Works can meet the CT requirement even at worst water quality condition. However, if disinfection criteria is strengthened to 4-log Giardia inactivation, then only 38% of disinfection data can meet the CT requirement. Rational disinfection criteria need to be developed, based on the occurrence of Giardia or other indicating microorganisms occuring in source water. Fourth, significant improvement of disinfection performance in 2001 at all WTPs in Seoul was made as compared to that of 1999 year.

국내 주요 상수원수와 처리수에서 HAAs 생성 특성

염철민,최유식,변석종,조순행,윤제용 대한상하수도학회 2002 상하수도학회지 Vol.16 No.2

This study was conducted to investigate the haloacetic acid (HAAs) formation characteristics in raw and treated water in Korea. The raw and treated water from the five major rivers were examined to measure the HAAs concentrations and compared those with literature values. Major findings are as follows. First, average HAAs concentration of treated water (collected from three water treatment plants) in Korea appeared to be 62.5±66.7㎍/L (n=7) and this level is higher than the average trihalomethanes (THMs) concentration (13.2±12.9㎍/L, n=6933) reported recently. Second, the average formation potential of TCAA and DCAA after three days was found as 103±74㎍/L (n=14) and 76±36㎍/L (n=14), respectively. As this result was applied to US-EPA developed model equation for TCAA and DCAA formation, dissolved organic matter (DOM) in Korea has a tendency to produce more TCAA and DCAA as compared to US. This phenomenon was especially notable in DCAA. The sum of weight percentage of TCAA and DCAA which are individual component of HAAS was composed of 80% of HAAs.

납노출지표와 적혈구내 protein kinase C 활성도의 연관성

황규윤,황보영,안현철,김용배,리갑수,이성수,안규동,이병국 大韓産業醫學會 2001 대한직업환경의학회지 Vol.13 No.4

목적 : Protein kinase C는 칼슘-인지질 의존형인산화 효소로 'H VJ'tfO에서 납에 의하여 활성화되지만, 납에 노출된 인체내에서 그 영향을 평가한 경우는 얼다. 본 연구의 목적은 납에 직업적으로 노출되는 근로자를 대상으로 납 노출이 적혈구막의 단백질내에서 PKC 활성에 의한 인산화 수준에 영향을 주는지 알아보고자 하였다. 방법 : 1998년부터 국내 납 근로자를 대상으로 납에 의한 건강 영향조사가 4년간의 코호트 연구로 실행하였다. 1차년도에 630명의 납 근로자와 135명의대조군이 조사되었고 이들중 본 연구에서는 직업적노출이 되는 사업장에 근무하는 212명의 근로자를대상하였다. 156명의 남자와 56명의 여자 근로자를 대상으로 인구학적, 과거병력, 직업력 등을 구조화된 설문과 면접으로 조사되었고 납 노출 평가는 혈중 납농도 및 ZPP, 경골중 납농도를 측정하였다. PKC의 활성도는 적혈구막 단백질내 PKC 의존형인산화 수준으로 평가하였다. 적혈구막 단백질인spectrin과 band 4.9의 후인산화수준을 측정하여각 납 노출지표(혈중 납, ZPP, 경골중 납. 노출기간)와의 관련성은 다중회귀분석을 이용하였다. 결과 : 조사대상자의 평균(SD) 연령은39.1(10.0)세, 근무기간은 8.1(6.5)년 이었으며, 경골중 납농도는 범위가 0.8에서 290.8 trg Pb/gbone mineral로 평근(SD) 34.4(35.2) rig Pb/gbone mineral이었다. 적혈구막 단백질의 후인산화수준은 개인간 변이가 매우 컸으며, spectrin은 평균(SD) 540 7(304.1), band 4.9 SfkDa는198.6(78.2), 48 kDa는 247.7(83.3) PSL이었다.경골중 납농도와 노출 기간은 이들 후인산화 수준과역상관성을 보였으나(p(0.05), 혈중 납 농도와 ZPP는 상관성이 없었다(p)0.05). 가능성 있는 혼란변수를 통제한 상태에서도 경골중 납 농도와 노출기간은 이들 후인산화수준과 유의한 회귀계수를 나타내었다. 결론 : 만성적 납 노출에 의하여 적혈구내 PKC활성도는 영향을 받아 증가되어있는 것으로 평가되어 적혈구막 단백질의 인산화수준은 납의 노출지표로 이용될 수 있을 것이다. 납의 신경독성은 부분적으로 PKC의 활성도왁 관련되어 있을 기전을 배제하기 어렵기 때문에 PfC 활성도와 신경행동학적 기능과의 관련성 평가가 진행되어야 할 것이다. Objectives : Protein kinase C(PKC) , a calcium and phospholipid dependent enzyme, is activated by lead in vitro at picomolar concentrations. However, the effect of lead on PKC has never been studied in a human population. The purpose of the study was to evaluate whether lead exposure was associated with PKC mediated-phosphorylation in erythrocytes among lead workers. Methods : Two hundred and twelve lead workers were studied. To determine the levels of phosphorylation ir vivo, an in vivo back phosphorylation technique was used by adding PKC and γ-32P to preparations of erythrocyte membranes. We measured back phosphorylations of erythrocyte membrane proteins, spectrin, and 52 kDa and 48 kDa, as an indirect measure of PKC activation if vivo. Results : The mean(SD) age and exposure duration was 39.1(10.0) years and 8.1(6.5) years, respectively. Tibial lead ranged from 0.8 to 290.8 μg Pb/g bone mineral with a mean (SD) of 34.4(35.2) μg Pb/g bone mineral. The means(SD) of back phosphorylation levels of the three proteins were 540.7(304.1), 198.6(78.2), and 247.7(83.3) photostimulated luminescence units (PSL), respectively, by phosphoimager. After adjustment for potential confounding factors, tibial lead and exposure duration were significantly and inversely associated with back phosphorylation levels. One unit of increase in tibial lead (1 μg Pb/g bone mineral) is associated with a decline in spectrin, band 4.9 52 kDa, and band 4.9 48 kDa back phosphorylation levels by 1.4(p〈0.05), 0.34(p〈0.05), and 0.47(p〈0.01), respectively However, there were no associations between the back phosphorylation levels and either blood lead or ZPP levels. Conclusions : These findings suggest that the PKC activity in erythrocytes is increased by chronic lead exposure and that erythrocyte membrane protein phosphorylation may be a biomarker of lead exposure.

국내 상수원수의 유기물 특성에 따른 소독부산물 생성능

염철민,변석종,조순행,윤제용 대한상하수도학회 2003 상하수도학회지 Vol.17 No.1

This study was conducted to investigate the characteristics of disinfection by-products formation potential (DBPFPs) of dissolved organics. Dissolved organics in raw water were separated into two fractions ((1) hydrophilic and (2) hydrophobic) for the measurement of DBPs. Three types of DBPs (trihalomethanes (THMs), haloacetic acids (HAAs), and total organic halides (TOX)) were measured at 3days and 7days incubation time. Sample waters were collected from the Han River and the Wonchun Reservoir. Two major findings are as follows. First, THMFPs/DOC, HAAFPs/DOC and TOXFPs/DOC in the hydrophilic organic component had a level of lower value than those of the hydrophobic organic component. Brominated THMs and bominated HAAs were not found in the chlorinated hydrophobic organic component. Second, the magnitude of HAAFPs/DOC were higher than that of THMFPs/DOC in both hydrophilic and hydrophobic organic components. This results support the reported observation that HAAs formations were higher than that of THMs in chlorinated drinking water. THMFPs and HAAFPs comprised 53-91% of TOXFP.

치과용 저금계 합금의 조성 및 열처리에 따른 경도 및 변색에 관한 연구

김철위,김명국,백기석,이용근,윤태호 대한치과기재학회 2000 대한치과재료학회지 Vol.27 No.1

Discoloration of dental alloys results from several reasons such as chemical tarnish, precipitation of chromatic substance on the alloy surface. In this study, the discoloration of 20 kinds of dental casting alloys was measured after immersion in various solutions, and the results were analyzed by the composition of the alloys and solutions. The effects of constitutional elements of the alloys on the color and discoloration of alloys were evaluated also. Cast specimens were polished with #400 silicons carbide paper, and were washed and dried. Vickers hardness of the alloys specimens was measured before and after heat treatment. Color of specimens was measured with the Spectrophotometer (Minolta CM-3500d, Japan.) with the CIELAB scale. Illumination C was used with SCE. Five kinds of aqueous solutions of HP (10% H₂O₂), NS (5% Na₂S), NC (5% NaCL), AS (mucin-added artificial saliva) and SF (10% SnF₂) were used, and the specimens were immersed at 37℃ for one and three days. ΔE* of the mostly discolored alloy for three days in HP was very high as 26.6, 10.27 in NS, 7.88 in AS, 4.23 in SF, and 4.18 in NC. Multiple regression analysis among CIE L*, a*, b* before immersion and the alloy composition showed that each CIE L*, a*, b* was negatively correlated with palladium content, and R value was -0.623, -0.365, -0.674 respectively. Multiple regression analysis among ΔE*, ΔL*, Δa*, and Δb* after there days and the alloy composition showed that silver was positively correlated with ΔE* (R = 0.510, p<0.01), and CIE L* was influenced by silver and copper content, CIE a* was influenced by copper and indium content, CIE b* was influenced by silver content (p<0.01). VHN number was 146.00∼347.60 before heat treatment, and 161.20∼331.20 after heat treatment.