• 한국건설순환자원학회논문집
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• 제8권3호
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• pp.356-364
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• 2020

본 연구에서는 광촉매를 혼입한 모르타르의 방오성능을 평가하기 위해 메틸렌 블루를 이용한 실험 연구를 수행하였다. 실험 시편은 시멘트 중량대비 2.5%, 5.0%, 7.5% 및 10.0%의 광촉매를 혼입하여 모르타르 시편을 제작하였고, 시편 표면에 스크래치 형태로 조도를 설정하였다. 표면 조도는 3가지로 조도가 없는 경우, 조도가 작은 경우(중간 조도), 조도가 큰 경우(거친 조도)로 설정하였다. 모르타르 시편 제작 후 24시간 동안 자외선램프 조사와 12시간 동안 메틸렌 블루 컨디셔닝 용액에 침지 하는 전처리 과정을 진행하였다. 실험챔버에 전처리가 완료된 모르타르 시편을 배치 후 48시간 동안 자외선램프를 조사하였고 시간에 따라 메틸렌 블루 수용액의 색 변화를 분광측색계를 이용하여 측정하였다. 광촉매의 혼입량이 증가할수록 메틸렌 블루 색 변화는 증가하는 경향을 나타내며 이는 방오성능이 증가하는 것을 의미한다. 반면에 표면조도가 증가할수록 메틸렌 블루 용액의 색 변화는 뚜렷한 경향은 나타내지 않으며 표면의 광촉매 분포가 일정하지 않기 때문이다.

• Journal of Korean Dental Science
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• 제5권2호
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• pp.60-67
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• 2012

Purpose: To test the apical leakage prevention performance of three different materials through protein leakage procedures using bovine serum albumin (BSA) and Bradford protein reagent. Materials and Methods: A total of 60 human single-rooted teeth were divided into 4 groups, and conventional root canal filling was done. The root was cut 3 mm from the apex, and a cavity was formed. Proroot MTA (MTA), Fuji II LC (GI), Fuji II LC with XP bond (GIA), and Caviton (CA) were used as experimental materials to fill the cavity in a retrograde filling manner. The extent of BSA leakage was then measured with a ultraviolet visible spectrophotometer 24, 48, and 72 hours after filling. Result: After 24 hours, among the 15 teeth of each group, 2 in MTA, 4 in GI, 3 in GIA, and 7 in CA showed leakage. After 48 hours, 3 in MTA, 5 in GI, 5 in GIA, and 10 in CA had leakage and discoloration. After 72 hours, among the 15 teeth of each group, 3 in MTA, 6 in GI, 5 in GIA, and 10 in CA showed leakage. The leakage in the CA group was greater than that in the MTA group at 48 and 72 hours based on Fisher's exact test (P=0.025), and the difference was statistically significant. Similarly, the leakage in the CA group was greater than that in the MTA group over time based on the Kaplan-Meier survival estimate (P=0.011), and the difference was statistically significant. Conclusion: Glass ionomer, glass ionomer after adhesive application, and MTA all showed leakage. Caviton showed greater leakage compared to MTA 48 and 72 hours after filling, and the difference was statistically significant; thus suggesting that Caviton is not appropriate as retrograde filling material considering its sealing ability.

• 대한화학회지
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• 제44권2호
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• pp.120-126
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• 2000

2-PhenyI-4H,5H-3-methyl-3-thiazolinium perchlorate(PTP)유도체들의 가수분해속도상수를 수용액에서 자외선 분광법으로 측정하여 넓은 pH 범위에서 적용될 수 있는 속도식을 구하였다. pH에 따른 속도상수의 변화, 가수분해 생성물의 확인, 일반염기 및 치환기 효과 등을 바탕으로 반응 메카니즘을 제안하였다. 즉 pH 4.0 이하에서는 물분자의 첨가가 일어나 가수분해가 진행되며, pH 9.0 이상에서는 전형적인 Michael type의 반응이 일어나며, pH $4.5{\sim}8.0$ 사이에서는 이들 두 반응이 경쟁적으로 일어남을 알았다.

• 한국전기전자재료학회논문지
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• 제33권1호
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• pp.25-30
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• 2020

Oxide (SiO₂)/Metal(Ag)/Oxide(SiO₂, ITO, ZnO) multilayer films were fabricated using a magnetron sputtering technique at room temperature on Si (p-type, 100) and a glass substrate. The electrical and optical properties of the asymmetric multilayer films depended on the thickness of the mid-layer film and the type of oxide in the bottom layer. As the metal layer becomes thicker, the sheet resistance decreases. However, the transmittance decreases when the metal layer exceeds a threshold thickness of approximately 10~12 nm. In addition, the sheet resistance and transmittance change according to the type of oxide in the bottom layer. If the oxide has a large resistivity, the overall sheet resistance increases. In addition, the anti-reflection effect changes according to the refractive index of the oxide material. The optical and electrical properties of multilayer films were investigated using an ultraviolet visible (UV-Vis) spectrophotometer and a 4-point probe, respectively. The optimum structure is SiO₂ (30 nm)/Ag (10 nm)/ZnO (30 nm) multilayer, with the highest FOM value of 7.7×10^-3 Ω^-1.

• Current Photovoltaic Research
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• 제8권1호
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• pp.33-38
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• 2020

Single-phased SnS thin films have been prepared by RF magnetron sputtering at various deposition pressures. The effect of deposition pressure on the structural and optical properties of polycrystalline SnS thin films was studied using X-ray diffraction (XRD), field-emission scanning electron microscopy (FE-SEM), X-ray photoelectron spectroscopy (XPS) and ultraviolet-visible-near infrared (UV-Vis-NIR) spectrophotometer. The XRD analysis revealed the orthorhombic structure of the SnS thin films oriented along the (111) plane direction. As the deposition pressure was increased from 5 mTorr to 15 mTorr, the intensity of the peak on the (111) plane increased, and the intensity decreased under the condition of 20 mTorr. The binding energy difference at the Sn 3d_5/2 and S 2p_3/2 core levels was about 324.5 eV, indicating that the SnS thin film was prepared as a pure Sn-S phase. The optical properties of the SnS thin films indicate the presence of direct allowed transitions with corresponding energy band gap in the rang 1.47-1.57 eV.

• 대한소아치과학회지
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• 제25권4호
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• pp.797-810
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• 1998

The purpose of this study was to develop a new way of delivery system of chlorhexidine using self-curing acrylic resin. Different preparations of chlorhexidine, such as chlorhexidine varnish($Chlorzoin^{(R)}$) and chlorhexidine diacetate crystalline, were mixed into self-curing acrylic resin with different methods. Every resin plate was made and was immersed in 100ml of distilled water individually, and kept in an incubator at $37^{\circ}C$. Solution(0.8ml) was collected from the each container at every 24 hours, and the amount of released chlorhexidine in the solution was measured in an ultraviolet spectrophotometer at 255nm. Flexural strength of all of the resin plates in the Experiment 2-A and 2-B were measured using Instron at the end of the experimental periods. The results were as follows: 1. It was found that chlorhexidine was released from the experimental groups in the Experiment 1, 2-A, and 2-B. And the release of chlorhexidine from all of the experimental groups showed a pattern of sustained-release preparation. 2. It seemed likely that a condition of "dryness" reduced a release of chlorhexidine from the chlorhexidine varnish. 3. It may be stated that a method of "chlorhexidine diacetate mix" with the polymer be more efficient than a method of "Chlorzoin mix" with the monomer. 4. Although it was evident that a flexural strength of the acrylic resin plates be reduced by a mix of either Chlorzoin or chlorhexidine diacetate crystalline, it seemed likely that the resin plates except Group 4 and 5 in the Experiment 2-B may be usable in the clinical situation.

• 한국안광학회지
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• 제13권3호
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• pp.73-77
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• 2008

목적: 본 논문은 저온열처리로 비결정 또는 결정 ZnO 박막의 UV emission 가능하다는 것이다. 방법: 화학적 용액법을 이용하여 소다-라임-실리카 유리 위에 100, 150, 200, 250 및 $300^{\circ}C$로 열처리하여 비정질 및 나노 결정질 ZnO 박막을 제조하였으며, 박막의 성장 특성 및 광학적 특성을 X-선 회절 분석법, 자외선-가시광선-근적외선 분광법 및 발광분석법을 통하여 분석하였다. 결과: $100^{\circ}C{\sim}200^{\circ}C$에서 60분간 열처리된 박막은 비정질 특성을 나타내고 있었으며, $250^{\circ}C$ 및 $300^{\circ}C$로 열처리된 박막에서는 ZnO 결정상이 나타났다. 비정질 ZnO 박막의 PL분석에 의하면 매우 강한 Near-band-edge emission이 나타났으며, Green emission은 거의 검출되지 않았다. 결론: 앞으로는 저온에서 ZnO 광전자소자를 쉽게 제조할 수 있을 것이다.

• 한국표면공학회지
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• 제51권2호
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• pp.126-132
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• 2018

SnS thin films with different substrate temperatures ($150 {\sim}300^{\circ}C$) as process parameters were grown on soda-lime glass substrates by RF magnetron sputtering. The effects of substrate temperature on the structural and optical properties of SnS thin films were investigated by X-ray diffraction (XRD), Raman spectroscopy (Raman), field-emission scanning electron microscopy (FESEM), energy dispersive X-ray spectroscopy (EDS), and Ultraviolet-visible-near infrared spectrophotometer (UV-Vis-NIR). All of the SnS thin films prepared at various substrate temperatures were polycrystalline orthorhombic structures with (111) planes preferentially oriented. The diffraction intensity of the (111) plane and the crystallite size were improved with increasing substrate temperature. The three major peaks (189, 222, $289cm^{-1}$) identified in Raman were exactly the same as the Raman spectra of monocrystalline SnS. From the XRD and Raman results, it was confirmed that all of the SnS thin films were formed into a single SnS phase without impurity phases such as $SnS_2$ and $Sn_2S_3$. In the optical transmittance spectrum, the critical wavelength of the absorption edge shifted to the long wavelength region as the substrate temperature increased. The optical bandgap was 1.67 eV at the substrate temperature of $150^{\circ}C$, 1.57 eV at $200^{\circ}C$, 1.50 eV at $250^{\circ}C$, and 1.44 eV at $300^{\circ}C$.

• 한국염색가공학회지
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• 제22권1호
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• pp.71-76
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• 2010

In this study the optimum dyeing conditions and blocking effect of UV deodorization efficiency of Ligustrum japonicum Thunb were investigated. Colorants were water-extracted from Ligustrum japonicum Thunb fruit and freeze-drided to obtain colorants powder. The effects of dye concentration, dyeing temperature, dyeing time, and the number of dipping count were studied. Fastness to dry cleaning, rubbing, perspiration, and light were measured according to KS K 0644, KS K 0650, KS K 0715 and KS K 0700, respectively. In order to examine the dyeability according to dyeing conditions, reflectance of fabrics were measured by using UV/VIS spectrophotometer. The bath ratio was 1:20. Dyeing concentration was 100, 200, 300, 400 and 500% on the weight of fiber. Dyeing time was 20, 40, 60, and 80 minutes. Dyeing temperature was 20, 40, 60, 80, and $100^{\circ}C$. The infrared high pressure dying machine was used. As dyeing concentration increased, dye adsorption increased up to 400% and it slowed down. Dye uptake was increased with raising themperature up to $80^{\circ}C$ and it slowed down. Dye adsorption occurred rapidly at first 20 minutes and then it slowed down and reached almost maximum dye uptake at 60 min. Dye uptake increased by repeated dyeing. Therefore, it is considered that optimum dyeing condition is 400%(o.w.f.), $80^{\circ}C$, 60 min. And repeated dyeing improves dye uptake. Color fastness to dry cleaning and rubbing was good, but light fastness and perspiration fastness was not good. Blocking effect of ultraviolet radiation and deodorization efficiency was good.

• 대한소아치과학회지
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• 제25권2호
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• pp.259-267
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• 1998

For more than two decades, many investigators have tried a variety of methods for delivering antimicrobial agents to the oral cavity with the objective of eliminating mutans streptococci. In the belief that the effectiveness of chemotherapy might be improved by a more effective delivery system, the intention of the present study was to exploit a new drug delivery system delivering chlorhexidine to the oral cavity. The vehicle delivering chlorhexidine tested in this study was self-curing acrylic resin(polymethyl methacrylate). The powder of the acrylic resin was polymerized with the 5 different liquid preparations, in which $Chlorzoin^{(R)}$ was mixed with five different monomer/Chlorzoin ratios immediately prior to the polymerization, in a stainless steel mold ($40mm{\times}40mm{\times}2mm$). A total of 50 cured resin specimens were divided into 5 groups according to the different monomer preparations. Every specimen was soaked in an airtight container filled with distilled water (100 ml) and then kept in an incubator at $37^{\circ}C$. The solutions (0.8 ml) were collected from the container at every 24 hours, and the amount of released chlorhexidine in the solutions was measured in an ultraviolet spectrophotometer at 250nm. The container was refilled with distilled water every after measurement. This procedure was repeated for 14 days. It was found that chlorhexidine was continuously released from all of the 50 specimens during the experimental period. And it was noted that the pattern of chlorhexidine release was a type of sustained-release preparation, that is, the amount of the released chlorhexidine at the first day in all 5 groups was high (p<0.0001), and then the release was decreased during the rest of the experimental period (p<0.001).