• 한국진공학회지
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• 제18권6호
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• pp.453-458
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• 2009

SiOC 박막을 BTMSM과 산소의 혼합가스를 사용하여 CVD 방법으로 증착하였다. 박막의 특성은 가스 유량비에 따라서 변하였다. 유전상수는 MIS 구조를 이용하여 C-V 측정법에 의하여 얻었다. 결합의 말단을 구성하는 Si-$CH_3$ 결합 사이의 공간효과에 의해서 기공이 만들어지며, 기공의 형성에 의해서 박막의 두께가 증가하였다. 그러나 분극의 감소에 의해서 만들어지는 SiOC 박막은 두께가 감소하면서 유전상수도 감소되었다. 열처리 후 유전상수는 수산기의 기화에 의해서 감소되었다. 박막의 두께는 분극의 감소에 의한 유전상수의 감소와 연관이 있었다. 굴절률은 박막의 두께에 반비례하는 경향성이 있으며, 박막의 두께와 굴절률의 경향성은 열처리 후에도 변하지 않았다.

• 한국광학회지
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• 제9권3호
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• pp.162-167
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• 1998

CF4 이온빔보조증착법으로 굴절률이 유리보다 낮은 SiOxFy 박막을 제작하고 광학적, 구조적 및 화학적 특성을 연구하였다. End-Hall 이온총의 양극전압의 간소에 따라 SiOxFy 박막의 굴절률은 1.455까지 변하였으며, 이온빔 전류밀도의 증가에 따라서 굴절률은 1.462에서 1.430까지 변하였다. XPS와 FT-IR 분석으로부터 SiOxFy 박막의 F양이 증가함에 따라 Si-O 결합은 파수가 높은 쪽으로 이동하였고, F이 약 8.5at.%인 SiOxFy 박막은 OH 결합이 매우 감소하였으여, 박막 표면의 F이 H2O와 결합하여 탈착되는 것을 알았다. SiOxFy 박막의 응력은 0.3GPa 이하의 압축응력이었으며, 결정구조는 비정질이었다. SiOxFy 박막의 응용으로서 SiOxFy 박막과 흡수층 Si 박막을 이용하여 2층 반사방지막을 제작하였다.

• 한국콘텐츠학회논문지
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• 제13권2호
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• pp.431-439
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• 2013

본 연구의 목적은 위험을 반영하여 지역별 아파트 투자성과를 분석하고 지역별 특성의 존재유무를 검증하는 것이다. 분석을 위해 지역별 아파트 투자성과를 장단기로 나누어 분석하였다. 자료수집기간은 2002년부터 2012년의 10년간이며 대상지역은 서울의 강남 북과 6개 광역시이다. 성과평가를 위해 만기 5년의 국민주택1종 채권수익률을 무위험수익률로 사용하고 임대수익계산을 위해서는 만기1~2년 정기예금금리를 사용하였다. 분석결과, 장기투자성과 시에는 서울과 인천은 지역특성이 존재하지 않아 트레이너지표를 사용하여 평가하였으며 지방광역시는 지역특성이 존재하여 젠센지표로 평가하였다. 또 단기성과평가시에는 모든 지역에서 지역특성이 존재하는 것으로 나타나 젠센지표를 사용하여 평가하였다. 모든 지역에서 지역특성이 작용하는 단기 성과평가 결과는 단순수익률로 평가한 결과와 전혀 다른 것으로 나타났다. 따라서 단순 수익률로 성과평가를 할 경우에는 성과에 대한 인식을 왜곡할 수 있음이 드러났다.

• Restorative Dentistry and Endodontics
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• 제26권4호
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• pp.316-325
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• 2001

The purpose of this study was to evaluate the effect of adhesive curing timing on the direction of polymerization shrinkage of light-curing composite resin. In this study, the curing times of adhesive and composite resin were measured by differential scanning calorimeter(DSC). 28 extracted human molars were embedded in clear resin and box-type cavities were prepared. Based on DSC data, the experimental teeth were divided into 4 groups. Group 1: no bond; Group 2: late curing; Group 3: Intermediate curing; Group 4: Early curing. After treating with adhesive, the buccal cavities were filled with Z-100 hybrid composite resin and the lingual ones were filled with AEliteflo flowable composite resin. The depressions at the surface were measured by surface profilometer, then the specimens were embedded in clear resin and sectioned. Impressions were obtained and used to get epoxy resin replicas. The epoxy replicas were gold-coated and observed under SEM. Average Maximum Gap(AMG), Gap Proportion(GP), Average Marginal Index(AMI) were used to compare the shrinkage gap of each group. The results were statistically analyzed using the Kruskal-Wallis One Way ANOVA, Student-Newman-Keuls method. The results of this study were as follows. 1. Average Maximum Gap, Gap Proportion, Average Marginal Index and depression at the surface or Z-100 hybride composite resin were smaller than those of AEliteflo flowable composite resin(P<0.05). 2. When the bonding between composite resin and tooth structure was strong, the shrinkage gap was small, and depression at the surface was deep(P<0.05). 3. In the well-bonded group, light-curing composite resin shrank toward bonded cavity wall, not toward light source. The result suggested that the direction of polymerization shrinkage was affected by the quality of bonding in the dentin-resin interface. The strong was the bonding between composite resin and tooth structure, the smaller was the gap and the deeper was the depression at the surface. Then the flow to compensate the polymerization shrinkage proceeded from surface to bonded cavity wall.

• 한방재활의학과학회지
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• 제19권4호
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• pp.135-150
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• 2009

Objectives : Osteoporosis is the most common metabolic disease of the bone, and one of the most important public health problems around the world. Obesity rate gradually increases as women grow older. The purpose of the study was to investigate the changes between bond mineral density(BMD) and body mass index(BMI) according to sex and age. Methods : We measured the bone mineral density(BMD) of lumber spine(L2-L4) and femoral neck in 10000 normal adult, using dual energy X-ray absorptiometry (DEXA; DPX-alpha). and also measured the body mass index(BMI) in 9810 normal adult. then we analysed the changes of BMD and BMI according to sex and age. Results : 1. As getting older, male's T-score of lumbar spine(L2-L4) was slowly decreased. On the other hand, female's T-score of lumbar spine was sharply dropped after 46 years old. 2. As getting older, male's T-score of femoral was slowly decreased. On the other hand, female's T-score of femoral was sharply dropped after 49 years old. 3. Irrespective of age, male's BMI keep up the extent within a definite period of numerical value. As getting older, female's BMI continued its upward trend. Conclusions : Much more attention should be needed for female patient suffering from osteoporosis and obesity than male.

• 대한치과교정학회지
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• 제43권2호
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• pp.96-100
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• 2013

Objective: To evaluate the effects of contamination by either blood or a hemostatic agent on the shear bond strength (SBS) of orthodontic buttons. Methods: We used 45 freshly extracted, non-carious, impacted third molars that were divided into 3 groups of 15. Each tooth was etched with 37% phosphoric acid gel for 30 s. Human blood or the blood stopper agent was applied to the tooth surface in groups I and II, respectively. Group III teeth were untreated (controls). Orthodontic buttons were bonded to the teeth using light-curing composite resin. After bonding, the SBS of the button was determined using a Universal testing machine. Any adhesive remaining after debonding was assessed and scored according to the modified adhesive remnant index (ARI). ANOVA with post-hoc Tukey's test was used to determine significant differences in SBS and Fisher's exact test, to determine significant differences in ARI scores among groups. Results: ANOVA indicated a significant difference between groups (p < 0.001). The highest SBS values were measured in group III ($10.73{\pm}0.96$ MPa). The SBS values for teeth in groups I and II were significantly lower than that of group III (p < 0.001). The lowest SBS values were observed in group I teeth ($4.17{\pm}1.11$ MPa) (p < 0.001). Conclusions: Contamination of tooth surfaces with either blood or hemostatic agent significantly decreased the SBS of orthodontic buttons. When the contamination risk is high, it is recommended to use the blood stopper agent when bonding orthodontic buttons on impacted teeth.

• 펄프종이기술
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• 제47권4호
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• pp.115-126
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• 2015

In this study, we investigated influence of ground calcium carbonate (GCC) modified by washless multilayering of polyelectrolytes on paper quality. Three layers of polyelectrolytes (cationic starch/anionic polyacrylamide/cationic starch) were formed on the surface of GCC using laboratory inline washless polyelectrolytes multilayering system, which was called inline LbL GCC. Base papers were prepared with untreated GCC or inline LbL GCC using a laboratory handsheet former. These handsheets were coated with rod coater, and then printed by black ink. Properties of base paper and fold crack of coated paper were evaluated. Base paper with inline LbL GCC showed much higher mechanical strength in terms of tensile index, strain, internal bond strength, and folding endurance. The fold crack of coated paper with inline LbL GCC occurred more frequently compared to coated paper with untreated GCC. This might be due to highly improved internal bond strength of base paper, which resulted in smaller delamination that played a role of stress dissipation. It would be recommended to design a proper coating layer in order to prevent fold crack.

• 대한화학회지
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• 제55권5호
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• pp.733-740
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• 2011

Multiple regression analysis was used for the calculation of pKa values of 15 substituted benzaldoximes by using various types of descriptors as parameters. These descriptors are based on quantum mechanical treatments. They were derived by employing semi-empirical calculation represented by the PM3 model and an Abinitio method expressed by Hartree-Fock(HF) model performed at the 6-311 G(d, p) level of theory. The parameters tested for their ability to represent the variations observed in the experimental pKa(s) are atomic and structural properties including Muliken charges on the atoms of hydroxyl group and C=N bond, the angle $C_6-C_1-C_7$, and length of O-H bond. Molecular properties are also used like energies of HOMO and LUMO, hardness(${\eta}$), chemical potential(${\mu}$), total energy(TE), dipole of molecule(DM), and electrophilicity index(W). The relation between pKa values and each of these parameters of the studied compounds is investigated. Depending on these relations, two sets of parameters were constructed for comparison between the PM3 and HF methods. The results obtained favor the Abinitio method for such applications although both models proved to have high predictive power and have sufficient reliability to describe the effect of substituents on pKa values of benzaldoxime compounds under consideration which is clear from the values of correlation coefficient $R^2$ obtained and the consistency between the experimental and the calculated values.

• Bulletin of the Korean Chemical Society
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• 제27권5호
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• pp.718-724
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• 2006

The heterogeneous association behaviour of various concentration binary mixtures of mono alkyl ethers of ethylene glycol with ethyl alcohol were investigated by dielectric measurement in benzene solutions over the entire concentration range at 25 ${^{\circ}C}$. The values of static dielectric constant $\epsilon_0$ of the mixtures were measured at 1 MHz using a four terminal dielectric liquid test fixture and precision LCR meter. The high frequency limiting dielectric constant $\epsilon_\infty$ values were determined by measurement of refractive index $n_D$ ($\epsilon_\infty\;=\;n_D\;^2$). The measured values of $\epsilon_0$ and $\epsilon_\infty$ were used to evaluate the values of excess dielectric constant $\epsilon^E$, effective Kirkwood correlation factor $g^{eff}$ and corrective correlation factor $g_f$ of the binary polar mixtures to obtain qualitative and quantitative information about the H-bond complex formation. The non-linear behaviour of the observed $\epsilon_0$ values of the polar molecules and their mixtures in benzene solvent confirms the variation in the associated structures with change in polar mixture constituents concentration and also by dilution in non-polar solvents. Appearance of the maximum in $\epsilon^E$ values at different concentration of the polar mixtures suggest the formation of stable adduct complex, which depends on the molecular size of the mono alkyl ethers of ethylene glycol. Further, the observed $\epsilon^E$ < 0 also confirms the heterogeneous H-bond complex formation reduces the effective number of dipoles in these polar binary mixtures. In benzene solutions these polar molecules shows the maximum reduce in effective number of dipoles at 50 percent dilutions. But ethyl alcohol rich binary polar mixtures in benzene solvent show the maximum reduce in effective number of dipoles in benzene rich solutions.

• 대한치과교정학회지
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• 제48권4호
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• pp.245-252
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• 2018

Objective: We aimed to perform in-vitro evaluation to compare 1) shear bond strength (SBS), adhesive remnant index (ARI), and color change between self-etched and acid-etched primers; 2) the SBS, ARI and color change between direct and indirect bonding; and 3) the enamel roughness (ER) between 12-blade bur and aluminum oxide polisher debonding methods. Methods: Seventy bovine incisors were distributed in seven groups: control (no bonding), direct (DTBX), and 5 indirect bonding (ITBX, IZ350, ISONDHI, ISEP, and ITBXp). Transbond XT Primer was used in the DTBX, ITBX, and ITBXp groups, flow resin Z350 in the IZ350 group, Sondhi in the ISONDHI group, and SEP primer in the ISEP group. SBS, ARI, and ER were evaluated. The adhesive remnant was removed using a low-speed tungsten bur in all groups except the ITBXp, in which an aluminum oxide polisher was used. After coffee staining, color evaluations were performed using a spectrophotometer immediately after staining and prior to bonding. Results: ISONDHI and ISEP showed significantly lower SBS (p < 0.01). DTBX had a greater number of teeth with all the adhesive on the enamel (70%), compared with the indirect bonding groups (0-30%). The ER in the ITBX and ITBXp groups was found to be greater because of both clean-up techniques used. Conclusions: Direct and indirect bonding have similar results and all the primers used show satisfactory adhesion strength. Use of burs and polishers increases the ER, but polishers ensure greater integrity of the initial roughness. Resin tags do not change the color of the teeth.