• 의료ㆍ복지 건축 : 한국의료복지건축학회 논문집
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• 제3권4호
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• pp.59-68
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• 1997

This study is intended to review the Nucleus System of standard hospitals in U.K. The research is focused on the theoretical background, contents of Nucleus System, and the operational problems through the survey of sample hospitals. The contents of research include the development history of standardization, outlines, aimes, advantages, the data of Nucleus system, and the study-visits of sample hospitals. The conclusion could be summarized as follows ; 1) The form of standard hospitals is compact and low-rise the major movements are horizontal. The standard plans of the functional dpartments are unified as cruciform with $15m{\times}15m$ module. 2) The Nulceus System has been developed. The hospitals have 3 stories maximum and courtyards for natural light & ventilation. 3) The advantages of Nucleus System includes reduction of design & construction period, the buildability due to the repetitive construction, and the running cost. And the disadvantages are mentioned as the lack of storage, staff accomodation, pantry, and sanitary facilities. 4) Sample hospitals provide human scale, possibilities of growth & change, and curing environment from art decoration & artificial lake. 5) In case of Korean situation, even the minimum standardization such as hospital design guidelines should be developed in near future.

• Restorative Dentistry and Endodontics
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• 제26권6호
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• pp.492-498
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• 2001

The purpose of this study was to evaluate four different composite resins in vitro for microleakage in Class II box type restorations that have gingival margins apical to the cementoenamel junction. Forty caries free extracted human molars were used in this study. The Class II cavities were prepared 1.0mm below cementoenamel junction with a #701 carbide bur. The teeth were randomly divided into four groups, each group comprising 20 treated cavities according to adhesives and filling materials ; Group 1: Scotchbond Multipurpose/Z 100. Group 2: Ariston Liner/Ariston pHc, Group 3: One Step/Pyramid, Group 4: Prime & Bond NT/SureFil. To simulate the clinical situation during restoration placement, a restoration template was fabricated and composite resin was filled using a three sited light-curing incremental technique. The specimens were stored in the 100% humidity for 7 days prior to thermocycling. The specimens were immersed in 2% methylene blue dye solution for 24 hours and then embeded in transparent acrylic resin and sectioned mesiodistally with a diamond wheel saw. The degree of marginal leakage was scored under the stereomicroscope($\times$20) and the data were analyzed by Kruskal Wallis test and Mann Whitney test. (omitted)

• 한국진공학회:학술대회논문집
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• 한국진공학회 2000년도 제18회 학술발표회 논문개요집
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• pp.213-213
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• 2000

Direct laser vaporization of transition-metal(Co, Ni)/graphite composite pellet produced single wall carbon naotubes(SWNT) in the condensing vapor in a heated flow cylinder-type tube furnace, Transition metal/graphite composite pellet target was made by mixing graphite, Co, and Ni in 98:1:1 atomic weight ratios, pressing the mixed powder, and curing it. The target was placed in a tube furnace maintained at 1200$^{\circ}C$ and Ar inert collision gas continuously flowed into the tube. The 2nd harmonic, 532nm wavelength light from Nd-YAG laser was used to vaporize the tube. The carbon nanotubes produced by the laser vaporization were accumulated on quartz tube wall. The raw carbon nanotube materials were purified with surfactants(Triton X-100) in a ultrasonicator. These carbon nanotubes were analyzed using SEM, XRD, and Raman spectroscopic method. The carbon nanotube growth on the Ni-patterned Si substrate was investigated by the CVD process. Transition-metal, Ni and CH4 gas were used as a catalyst and a reactant gas, respectively. The structure and the phonon frequencies of the carbon nanotubes formed on the patterned Si substrate were measured by SEM and Raman spectrometer.

• Restorative Dentistry and Endodontics
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• 제38권3호
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• pp.105-112
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• 2013

While it is reasonably well known that certain dental procedures increase the temperature of the tooth's surface, of greater interest is their potential damaging effect on the pulp and tooth-supporting tissues. Previous studies have investigated the responses of the pulp, periodontal ligament, and alveolar bone to thermal irritation and the temperature at which thermal damage is initiated. There are also many in vitro studies that have measured the temperature increase of the pulp and tooth-supporting tissues during restorative and endodontic procedures. This review article provides an overview of studies measuring temperature increases in tooth structures during several restorative and endodontic procedures, and proposes clinical guidelines for reducing potential thermal hazards to the pulp and supporting tissues.

• 한국기계가공학회지
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• 제17권6호
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• pp.16-23
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• 2018

A polymer porous sheet, which can be applied to diverse wearable devices, has some advantages such as light-weight, high flexibility, high elongation, and so many others. In order to fabricate a porous sheet, water-soluble particles like sugar were utilized frequently, and there has been great advances. However, with our best knowledge, there are not enough reports on the mechanical behavior of porous sheets having different porosity. So, in this work, we tried to find out the relationship between porosity and mechanical deformation of a porous sheet. The process parameters such as a particle size, sheet thickness and PDMS mixing ratio with curing agent were analyzed on the effect of increasing the porosity of a sheet. Also, mechanical deformation of a sheet was tested using a tensile experiment. Through the experimental results, we make a conclusion that a highly porous sheet with thin thickness has high flexibility, and it deformed nearly double elongation comparing to worst one among nine cases.

• 대한치과의사협회지
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• 제57권3호
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• pp.162-168
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• 2019

Composite resin restorations in posterior teeth are increasing due to the aesthetic needs of patients and the development of materials. This trend will accelerate in line with domestic insurance policies. However, resin composites generate stresses due to their contraction during the polymerization process. To reduce the polymerization shrinkage stress of resin composites, incremental layering technique has been recommended for decades. This technique reduces stress at the cavity wall interface and allows a more efficient light curing of the material. Bulk-fill resin composites have been designed to simplify the restorative technique because they can be placed into cavities in a single increment of 4-5mm. The simplification of the operative procedures is desirable in clinical daily practice. In this context, bulk-fill resin composites are an attractive alternative for posterior restorations. However, a clearer understanding of the clinical performance of this relatively new class of materials in comparison to conventional resin composites is required. Based on previous studies, the aim of the current review was to present the clinical criteria for the use of bulk-fill composites in direct restorations of posterior teeth.

• 대한치과기공학회지
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• 제43권1호
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• pp.1-5
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• 2021

Purpose: To perform a comparative study on curing shrinkage according to the thickness of photopolymerization resin. Methods: Stainless steel molds of 2, 4, and 6 mm heights were prepared. The 2, 4, and 6 mm-height molds were classified as the 2H, 4H, and 6H groups, respectively. A photopolymerization resin was injected into the stainless steel mold. Photopolymerization was carried out using a photopolymer machine. During photopolymerization, the wavelength and intensity of 400~405 nm were set to 10, the highest intensity among 1~10. Photopolymerization was performed for 30 min per specimen (each group=10). The inner and outer areas of the specimen were measured. The data were analyzed using one-way ANOVA and Kruskal-Wallis H test (α=0.05). Results: In terms of the inner and outer diameters of the photopolymerization resin specimen, the 2H group contracted the most, whereas the 6H group contracted the least. A statistically significant difference was found between the groups (p<0.05). Conclusion: The amount of light irradiation of the photopolymerization resin must be adjusted according to the thickness.

• Restorative Dentistry and Endodontics
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• 제26권5호
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• pp.409-417
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• 2001

상아질접착제의 광조사가 상아질접착에 미치는 영향을 알아보기 위하여 in vitro에서 접착실험을 하였다. 120개의 발거된 소의 전치 협면 상아질을 노출시키고 산 부식 한 다음 self-priming형 상아질접착제 Prime&Bond$^{\circledR}$NT (Dentsply DeTrey, GmbH, Konstanz, Germany)를 도포 하였으며 600 mW/$\textrm{cm}^2$의 일반광도 또는 1930 mW/$\textrm{cm}^2$의 초고광도 광조사를 각각 20초 및 3초간 시행한 군과 시행하지 않은 군으로 나누어 복합레진 첨가후 광조사하였다. 접착제에 대한 광조사를 시행하지 않은 경우에는 복합레진 첨가 후 초고광도로 3초, 6초 및 12초간 광조사하였다. 접착양상 평가를 위해 만능시험기로 전단접착강도를 측정하고 파단면을 입체 현미경으로 관찰한 바를 일원 및 이원 변량분석법과 카이제곱검사법으로 통계 분석하여 다음과 같은 결과를 얻었다. 1. 상아질접착제를 광조사한 군이 광조사하지 않은 군에 비해 유의하게 높은 전단접 착강도를 나타내었다 (p<0.05). 2. 일반 광도 및 초고광도 광조사에 따른 전단접착강도에는 유의한 차이가 나타나지 않았다 (p>0.05). 3. 상아질접착제를 광조사하지 않고 복합레진 첨가 후 초고광도로 광조사한 군간에 조사시간에 따른 전단접착강도에는 유의 한 차이가 나타나지 않았다 (p>0.05). 4. 파단면 관찰 결과, 모든 군에서 접착계면에서의 파절을 포함하는 혼합파단양상이 가장 많이 나타났으며 군간에는 유의한 차이가 없었다 (p>0.05).

• Journal of Korean Dental Science
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• 제8권2호
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• pp.49-56
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• 2015

Purpose: The effect of accelerated aging on color stability of various dual-cured self-adhesive resin cements were evaluated in this study. Materials and Methods: Color stability was examined using three different brands of dual-cured self-adhesive resin cements: G-CEM LinkAce (GC America), MaxCem Elite (Kerr), and PermaCem 2.0 (DMG) with the equivalent color shade. Each resin cement was filled with Teflon mold which has 6 mm diameter and 2 mm thickness. Each specimen was light cured for 20 seconds using light emitting diode (LED) light curing unit. In order to evaluate the effect of accelerated aging on color stability, color parameters (Commission Internationale de l'Eclairage, CIE $L^*$, $a^*$, $b^*$) and color differences (${\Delta}E^*$) were measured at three times: immediately, after 24 hours, and after thermocycling. The $L^*$, $a^*$, $b^*$ values were analyzed using Friedman test and ${\Delta}E^*$ values on the effect of 24 hours and accelerated aging were analyzed using t-test. These values were compared with the limit value of color difference (${\Delta}E^*=3.7$) for dental restoration. One-way ANOVA and Scheff's test (P<0.05) were performed to analyze each ${\Delta}E^*$ values between cements at each test period. Result: There was statistically significant difference in comparison of color specification ($L^*$, $a^*$, $b^*$) values after accelerated aging except $L^*$ value of G-CEM LinkAce (P<0.05). After 24 hours, color difference (${\Delta}E^*$) values were ranged from 2.47 to 3.48 and $L^*$ values decreased and $b^*$ values increased in all types of cement and MaxCem Elite had high color stability (P<0.05). After thermocycling, color change's tendency of cement was varied and color difference (${\Delta}E^*$) values were ranged from 0.82 to 2.87 and G-CEM LinkAce had high color stability (P<0.05). Conclusion: Color stability of dual-cured self-adhesive resin cements after accelerated aging was evaluated and statistically significant color changes occurred within clinically acceptable range.

• 대한소아치과학회지
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• 제36권3호
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• pp.348-357
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• 2009

본 연구는 유구치 상아질의 각기 다른 부위(표층부, 심층부, 치경부)에서 복합레진 접착제의 접착강도를 비교, 평가하기 위하여 임상에서 흔히 사용하고 있는 서로 다른 4종의 접착방식(3-step total etch: 1군, 2-step total etch: 2군, 2-step self-etch: 3군, all-in-one: 4군)을 적용하고 복합 레진 ($Light-Core^{TM}$ Core Build-Up Composite)을 적층한 후, 미세인장접착강도를 비교하였을 때 다음과 같은 결과를 얻었다. 1. 접착방식간의 비교에서 레진의 접착방식에 따른 상아질 각 부위에서의 미세인장접착강도는 제 1군이 표층부에서 뚜렷이 높았으나(p<0.05) 2, 3, 4군은 부위에 따른 차이가 없었다. 2. 부위별 미세인장접착강도를 비교하여 보았을 때 상아질 표층부에서의 미세인장접착강도는 레진의 접착 방식간에 차이가 없었으나, 심층부에서는 2군, 3군, 4군 및 1군의 순으로 나타났고(p<0.05), 치경부에서는 2군과 3군이 1군과 4군에 비하여 현저히 높았다(p<0.05).