• Restorative Dentistry and Endodontics
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• v.26 no.1
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• pp.86-94
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• 2001

기존의 광중합기는 높은 광강도를 제공함으로써 광중합 복합레진을 최대한 단축된 시간내의 중합을 목표로 하였다. 이러한 높은 광강도는 복합레진의 중합깊이, 중합률면에서는 우수하나 중합 반응속도가 빠름으로 인해 중합시 응력 발생이 높아진다는 일련의 보고가 있다. 최근에는 광중합 속도를 늦춤으로써 변연적합도 및 중합시 응력 발생을 낮추는 새로운 중합방법들이 제시되고 있다. 이에 본 실험에서는 광조사 강도의 변화가 광중합 복합레진의 중합반응 과정에 미치는 영향 및 중합된 복합레진의 중합률에 대한 영향을 분석하고자 하였다. 5개의 혼합형 광중합 복합레진 (Z-100, Spectrum, Z-250, Clearfil AP-X, P-60)을 사용하였으며 중합시 적용된 광조사 강도에 따라 6개의 실험군으로 정의하였다. 실험군과 이에 따른 광조사 방법은 다음과 같다. 1군은 110mW/$\textrm{cm}^2$로 40초 중합, 2군 210mW/$\textrm{cm}^2$로 40초 중합, 3군 410mW/$\textrm{cm}^2$로 40초 중합, 4군 620mW/$\textrm{cm}^2$로 40초 중합, 5군 110mW/$\textrm{cm}^2$로 10초 중합 후 1분 뒤 620mW/$\textrm{cm}^2$로 30초 중합, 6군 210mW/$\textrm{cm}^2$로 10초 중합 후 1분 뒤 410mW/$\textrm{cm}^2$로 30초 중합하였다. 광중합시 중합 반응 양상에 관한 분석은 시차주사 열계량기를 이용하여 37$^{\circ}C$ 항온상태에서 10분간의 열흐름곡선을 기록하였다. 기록된 열흐름곡선에서 중합 반응시 나타나는 중합열 및 최대 중합열에 이르는 시간을 기록하여 중합반응 속도를 측정하였다. 중합된 복합레진의 중합률은 Fourier Transform Infrared Spectrometer(FTIR)를 이용하였으며 2mm 두께의 복합레진 하방에서의 중합률을 측정하였다. 측정된 결과는 ANOVA 및 Student-Newman-Keuls 방법을 이용하여 유의성을 검증하였다. 실험결과 다음과 같은 결론을 얻었다. 1. 광중합 복합레진 중합시 광조사 강도가 증가할수록 중합열은 증가하였으나 통계적 유의성은 보이지 않았다 (p>0.05). 2. 최대 중합열에 이르는 시간은 광조사 강도가 증가할수록 단축되었다. 이단계 중합방법을 사용한 경우 중합반응 속도를 감소시킬 수 있음을 보였다. 3. 광조사 강도가 증가할수록 중합률은 증가하였다. 이단계 중합방법을 사용한 경우 연속적인 고광강도를 사용한 경우와 유사한 높은 중합률을 보였다. 4. 중합률면에서 광중합복합레진의 중합시 400mW/$\textrm{cm}^2$ 이상의 광강도가 필요한 것으로 나타났다.

• Journal of the Korean Vacuum Society
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• v.7 no.3
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• pp.229-236
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• 1998

In this paper, thin films of Polyimide (PI) were fabricated by vapor deposition polymerization method (VDPM) of dry processes. The film's properties with curing temperature and electrical properties were studies. The synthesis of hexafluoroisopropyliden-2,2-bis[phthalic anhydride](6FDA) and 4, 4'-diamino diphenyl ether (DDE) was carried out by vapor deposition polymerization(VDP) with the same deposition rate. The evaporation temperature of 6FDA and DDE were $214^{\circ}C$ and $137^{\circ}C$, respectively, so as to preserve balance of stoichiometry. The polymic acid (PAA) made by VDPM were changed to PI by thermal curing. The uniformity and density of PI thin films were increased according to increasing curing temperature. The relative permittivity and dissipation loss factor were 3.7 and 0.008 at the frequency of 100Hz~200KHz, respectively, for the fabricated in the curing temperature of $300^{\circ}C$. Also, the resistivity was about 1.05$\times$$ 10^{15}$$\Omega$cm at $30^{\circ}C$.

• The Korean Journal of Zoology
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• v.32 no.4
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• pp.305-313
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• 1989

The present investigation aims at inquiring into a possible target for the heat inactivation of SCK tumor cells by comparing the kinetics of cell survival, rate of protein synthesis, and DNA polymerase activity in the presence of heat protector or heat sensitirer. A possible conclusion to be drawn from the present experiment is that there is no direct correlation between cell death and decrease in the rate of protein synthesis, but that the loss of DNA polvmerase $\beta$ activity correlates quite well with cell inactivation. Thus, protein degrada-tion and/or abnormal protein synthesis causes cell inactivation innireuv, possibly by altering the cellular environment which in turn affects the DNA polymerase $\beta$ activity. Accordingly, further studies, dealing with the correlation between changes in the cellular environment and DNA polymerase $\beta$ activity, are needed to set insight into a possible target for the heat inactivation of cells. 본 연구는 열보호제 또는 열증감제의 존재하에서 세포 생존곡선, 단백질 합성률, DNA 중합효소 $\beta$의 활성변화를 비교 검토함으로써 SCK 종양세포가 열에 의해서 불활성화될 때의 표적이 무엇인지를 밝혀보기 위해서 수행되었다. 본 실험의 결과로 추정하건대 열에 의한 세포치사는 단백질 합성률의 변화와는 직접적인 연관성이 없으나, DNA 중합효소 $\beta$의 활성도와는 밀접한 연관성이 있음을 알 수 있다. 즉, 단백질의 분해 또는 비정상적인 단백질의 합성이 세포의 환경을 변화시키고 이것이 DNA 중합효소 $\beta$의 활성에 영향을 미침으로써 간접적으로 세포의 치사를 초래할 것으로 짐작할 수 있다. 따라서, 세포의 열불화성화의 표적을 좀더 분명히 밝히기 위해서는 세포의 환경변화와 DNA 중합효소 $\beta$의 활성과의 관계를 추구하는 연구가 수행되어야 할 것으로 사료된다.

• Elastomers and Composites
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• v.39 no.4
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• pp.281-285
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• 2004

In this paper, the simple way to evaluate the value of the activation energy for the overall rate of free radical polymerization by using DSC thermograms was studied using free radical polymerization or butylacrylate as a model. Activation ehergies were determined at heating rates of 1, 2, 5, and $10^{\circ}C/min$ by applying the multiple scanning-rate methods of Kissinger, Osawa, and half-width methods as well as the single rate method of Barrett. The value of the overall activation energy measured was closely matched with the values calculated from individual data. This work also demonstrated that the use of the isoconversional method was a simple and effective way to estimate the activation energy for the overall free radical polymerization.

• Journal of the korean academy of Pediatric Dentistry
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• v.30 no.4
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• pp.707-714
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• 2003

Plasma Arc Curing(PAC) units operate at relatively high intensity and claimed to result in optimum properties of composite resin in a short curing time, so the interest of pediatric dentists about PAC units have been increased recently. But PAC units used for polymerizing restorative resins produce heat during operation. The purpose of this study was to evaluate temperature transmission through dentin of various depths using two types of PAC units(Flipo, Q-Lux plasma 100). The results from the present study can be summarized as follows : 1. When PAC be used continuously, temperature on tip was increased as curing times, and Q-Lux showed greater temperature rising(p<0.001). 2. Compared temperature transmission as dentin depth, temperature rising rate was decreased as dentin thickened(0.5, 1.0, 1.5, 2.0mm)(p<0.05). 3. Compared temperature transmission as resin depth, temperature rising rate was also decreased as resin thickened(1.0, 2.0mm)(p<0.05).

• Journal of the korean academy of Pediatric Dentistry
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• v.32 no.4
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• pp.604-610
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• 2005

This study was to evaluate the effects of several light curing units on the microleakage of composite resin restorations in primary teeth. The types of curing units were traditional low intensity halogen light(Optilux 360), plasma arc light(Filpo) low heat plasma arc light(Aurys) and high intensity LED(Freelight 2). After preparing cavities on sound primary teeth, cavities were filled with composite resin(Z100) using the same resin bond agent(Scotchbond Multi-Purpose) and were cured with each curing light system. After storing each specimen in sterile water for 24 hours, thermal circulation was done 1,000 times followed by pigmentation using 2% methylene blue solution. Each specimen was sliced and the degree of pigmentation was graded. When microleakage is graded, the average of Aurys was 0.95 which was the lowest and Freelight 2(1.05), Filpo(1.25), Optilux 360(1.30) followed. But values were not shown statistically significant difference (P>0.05). The results suggest that the newly developed curing units which has advantage in children by decreasing discomfort and procedure time can increase the microleakage of the composite resin.

• 대한치과보철학회:학술대회논문집
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• 1995.12a
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• pp.51-52
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• 1995

• 대한치과보철학회:학술대회논문집
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• 1997.11a
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• pp.55-55
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• 1997

• Polymer Science and Technology
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• v.13 no.5
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• pp.596-605
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• 2002

• Polymer(Korea)
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• v.35 no.3
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• pp.244-248
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• 2011

Poly(2,6-dimethyl-1,4-phenylene ether) (PPE) was synthesized by oxidative polymerization using various Cu(I)-amine catalyst system. The effects of catalyst/monomer ratio, different amine ligand, and the content of 2,4,6-trimethylphenol (TMP) additive on the polymer yield and molecular weight were investigated by using gel permeation chromatography. The catalytic activity of various Cu-amine systems on the 2,S-dimethylphenol (DMP) polymerization was monitored and compared each other through oxygen-uptake experiment. In addition, the effect of catalyst removal using aqueous EDTA on the thermal stability of the prepared polymer was elucidated by thermogravimetric analysis.