Dentin hypersensitivity (DH) is defined as short and sharp pain caused by external stimuli such as heat, vaporization, contact, osmotic pressure, and chemical stimulation in a normal tooth, rather than due to disease or tooth damage. Its solution is to block the flow of dentinal fluid by physically blocking the dentinal tubule. Of these treatments, fluoride and oxalate type for hypersensitivity can only have a temporary effect. Resins should be used with a suitable bonding system and they may cause hypersensitivity symptoms after treatment. Overcoming these limitations, there is a need for method that can effectively treat dental hypersensitivity lasting long without any side effects. For this reason, experiments with 200 plant extracts as candidates for dentin hypersensitivity, Buddleja officinalis was considered as a candidate for present study. The purpose of this study is to confirm whether the ethanol extract of Buddleja officinalis is effective to protect enamel and dentin by coating tooth surface and resistance to acid or alkali even after tooth coating.

A TiO2/CNT nanohybrid photocatalyst is synthesized via sol-gel route, with titanium (IV) isopropoxide and multi-walled carbon nanotubes (MWCNTs) as the starting materials. The microstructures and phase constitution of the nanohybrid TiO2/CNT (0.005wt%) samples after calcination at 450oC, 550oC and 650oC in air are compared with those of pure TiO2 using field-emission scanning electron microscopy and X-ray diffraction, respectively. In addition, the photocatalytic activity of the nanohybrid is compared with that of pure TiO2 with regard to the degradation of methyl orange under visible light irradiation. The TiO2/CNT composite exhibits a fast grain growth and phase transformation during calcination. The nanocomposite shows enhanced photocatalytic activity under visible light irradiation in comparison to pure TiO2 owing to not only better adsorption capability of CNT but also effective electron transfer between TiO2 and CNTs. However, the high calcination temperature of 650oC, regardless of addition of CNT, causes a decrease in photocatalytic activity because of grain growth and phase transformation to rutile. These results such as fast phase transformation to rutile and effective electron transfer are related to carbon doping into TiO2.

본 연구는 공동기술개발의 성과결정요인으로 파트너 특성과 관리과정 특성이 공동기술개발의 성과에 미치는 영향을 분석하였으며, 나아가 파트너 특성 및 관리과정 특성과 공동기술개발 성과와의 관계에서 지식흡수역량의 조절효과에 대하여 연구하였다. 이를 위하여 기술개발 업무와 관련이 있는 대기업과 중소기업의 기업부설연구소 및 공공기관인 정부 출연 연구기관과 관리기관의 연구원들을 대상으로 설문조사를 실시하였으며, 387명을 대상으로 실증분석하였다. 실증분석 결과 첫째, 파트너 특성의 기술개발역량과 공동기술개발경험이 모두 공동기술개발 성과에 유 의한 정(+)의 영향을 미쳤다. 이는 공동기술개발 파트너의 선정과정에서 주관기관은 기술개발경험과 필 요기술의 전문성을 보유한 파트너를 선호한다는 것이다. 둘째, 관리과정 특성에서는 목표의 명확성과 원 활한 의사소통이 공동기술개발성과에 유의한 정(+)의 영향을 미쳤다. 이는 공동기술개발의 목표가 구체 적이고 측정 가능해야 하고, 연구원들 간의 원활한 의사소통이 전제되어야만 공동기술개발 성과를 높일 수 있다는 것이다. 셋째, 독립변수와 조절변수간의 상호작용 효과를 분석한 결과, 공동기술개발경험과 지 식흡수역량 간의 관계에서 상호작용 효과가 있다. 즉, 지식흡수역량이 높을수록 파트너 특성의 공동기술 개발경험이 성과에 더욱 긍정적인 영향을 미쳤다.

In this study, the control of microstructure for increasing surface roughness of Al with an electro-chemical reaction and a post treatment is systematically investigated. The Al specimen is electro-chemically treated in an electrolyte. In condition of the post treatment at 100oC for 10 min, a change of the surface microstructure occur at 50V (5 min), and a oxidized layer is at 400V, to which lead a decreasing surface roughness. The minimum temperature of the post treatment for a change of microstructure is 80oC. Moreover, in the condition of 300V (5 min), the electro-chemical reaction is followed by the post treatment at 100oC, the critical enduring time for the change of microstructure is 3 min. The longer post treatment time leads to the rougher surface. The treated Al specimen demonstrate better heat release ability owing to the higher surface roughness than the non-treated Al.

This study aimed to investigate the association between carotid artery calcification (CAC) on panoramic radiograph and intima-media thickeness (IMT) measured on ultrasound. Panoramic radiographs which were taken from dental patients aged 50 years and older who visited for dental treatment were screened for the presence of CAC. The study group was composed of seven patients (four males and three females, average age 74.4±4.2 yrs) with CAC detected on panoramic radiographs, and the control group eleven patients (seven males and four females, average age 64.5±10.1 yrs) without CAC. All the patients underwent carotid ultrasonography to measure carotid IMT. The IMT was compared between the groups by nonparametric analysis of covariance (ANCOVA). The range of IMT of the study group was 1.10~2.0 mm, while that of the control group 0.60~1.10 mm. The mean of IMT was 1.50±0.34 mm in the study group and 0.85±0.14 mm in the control group, and there was statistically significant difference between the two groups (p<.01). In conclusion, CAC detected on panoramic radiograph might have an association with atherosclerosis

The most general photocatalyst, TiO2 and WO3, are acknowledged to be ineffective in range of visible light. Therefore, many efforts have been directed at improving their activity such as: band-gap narrowing with non-metal element doping and making composites with high specific surface area to effectively separate electrons and holes. In this paper, the method was introduced to prepare a photo-active catalyst to visible irradiation by making a mixture with TiO2 and WO3. In the TiO2-WO3 composite, WO3 absorbs visible light creating excited electrons and holes while some of the excited electrons move to TiO2 and the holes remain in WO3. This charge separation reduces electron-hole recombination resulting in an enhancement of photocatalytic activity. Added Ag plays the role of electron acceptor, retarding the recombination rate of excited electrons and holes. In making a mixture of TiO2-WO3 composite, the mixing route affects the photocatalytic activity. The planetary ball-mill method is more effective than magnetic stirring route, owing to a more effective dispersion of aggregated powders. The volume ratio of TiO2(4) and WO3(6) shows the most effective photocatalytic activity in the range of visible light in the view point of effective separation of electrons and holes.

This paper introduces an effect of a preparing -Ag composite on its mechanical properties and microstructure. In present study, -Ag was prepared by reduction-deposition route and wetting dispersive milling method, respectively. Two type of Ag powders (nano Ag and micron Ag size, respectively) were dispersed into powder during wetting dispersive milling in D.I. water. Each sample was sintered at for 2hr in atmosphere, and then several mechanical tests and analysis of microstructure were carried out by bending test, hardness, fracture toughness and fracture surface microstructure. As for microstructure, the Ag coated showed homogeneously dispersed Ag in in where pore defect did not appear. However, -nano Ag and -micro Ag composite appeared Ag aggregation and its pore defect, which carried out low mechanical property and wide error function value.

was successfully formed on a Ti specimen by MAO (Micro-Arc-Oxidation) method treated in electrolyte. This study deals with the influence of voltage and working time on the change of surface microstructure and phase composition. Voltage affected the forming rate of the oxidized layer and surface microstructure where, a low voltage led to a high surface roughness, more holes and a thin oxidized layer. On the other hand, a high voltage led to more dense surface structure, wider surface holes, a thick layer and fewer holes. Higher voltage increases photocatalytic activity because of better crystallization of the oxidized layer and good phase composition with anatase and rutile , which is able to effectively separate excited electrons and holes at the surface.

MAO(Micro-Arc Oxidation) method was used to make surface on 6063 Al specimen. This study was focused on an influence of voltage, density of electrolyte and a period of treatment on the change of surface microstructure by using SEM(Scanning Electron Microscope), EDS(Energy Dispersive X-ray Spectroscopy). The microstructure shows higher roughness and thicker oxidized layer with increase of voltage and maintaining period of treatment. The density of electrolyte affected a formation of more dense surface and increase of a oxidized layer.

A carbon doped (C-) photocatalyst, which shows good photocatalytic activity to Ultraviolet irradiation and visible irradiation, was successfully prepared by co-grinding of with ethanol or Activated Carbon(C), followed by heat treatment at in air for 60 min. Ethanol and C were used as a representative agent of liquid and solid for carbon doping. Their influence on improving photocatalytic ability and carbon doping degree was studied with degradation of methyl orange and XPS analysis. The product prepared by co-grinding of with Ethanol had Ti-C and C-O chemical bonds and showed higher photocatalytic activity than the product prepared by co-grinding of with C, where just C-O chemical bond existed. As a result, mechanochemical route is useful to prepare a carbon doped photocatalyst activating to visible irradiation, where the solid-liquid operation is more effective than solid-solid operation to obtain a carbon doped .

해기직업에 대한 안정이 없으면 인적요인에 의한 해양안전도 크게 개선되지 않을 것으로 판단된다. 따라서 해기직업 진입단계에서 부터 은퇴하기까지 생애에 걸쳐 해기사의 직업경로를 개발함으로써 보다 장기적이고 안정적인 해기직업 생활과 해양안전을 확보할 수 있을 것이다. 이를 위해 해기직업 경로모델을 설정하고 해기교육기관 진입자, 해상근무자, 육상근무자 2,830명을 대상으로 설문조사를 실시하여 가설을 검증하였다. 직업경로에 따른 행동요인 분석 결과, 첫째, 해기교육기관 진입자들에게 교육환경 개선과 해기직업생활에 대한 충분한 정보를 전달하고 둘째, 소득수준과 같은 경제적 요인은 해기직업 진입자에게는 동기요인이 되지 못하며 셋째, 적정 시기에 육상근무를 위한 하선유도가 해기직업의 매력화와 파생적인 장기승선 효과를 기대할 수 있으며 넷째, 해기면허체계를 단순화시켜 조기에 상위면허를 취득함으로써 상위직책에 근무할 수 있는 기회를 제공할 필요가 있다.

A visible-light photoactive photocatalyst was synthesized successfully by means of cogrinding of anatase- in ambient, followed by heat-treatment at in air environment. In general, it is well known that the grinding-operation induces phase transformation of a- to rutile . This study investigates the influence of the amount of gas on the phase transformation rate of a- and enhancement of visible-light photocatalytic activity, and also examines the relation between the photocatalytic activity and the period of grinding time. The phase transformation rate of a- to rutile is retarded with the amount of NH3 injected. And the visible-light photocatalytic activity of samples, was more closely related to the period of grinding time than amount injected, which means that the doping amount of nitrogen into more effective to mechanical energy than amount injected. XRD, XPS, FT-IR, UV-vis, Specific surface area (SSA), NOx decomposition techniques are employed to verify above results more clearly.