• 한국재료학회지
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• 제11권1호
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• pp.55-60
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• 2001

고 에너지 (1.5 MeV) 이온 주입된 Boron의 농도와 silicon 기판의 초기 산소 농도의 변화에 따라 silicon기판에 형성된 결정 결함 및 금속 불순물의 Gettering 효율에 대하여 DLTS(Deep Level Transient Spectroscopy), SIMS(Secondary ion Mass Spectroscopy), BMD(Bulk Micro-Defect) analysis 및 TEM (Transmission Electron Microscopy)을 이용하여 연구하였다. 이온 주입 전후의 DLTS 결과를 확산로 및 RTA를 이용한 열처리 전후의 DLTS 결과와 비교할 때 이온 주입 전 시편에서 볼 수 있는 공공에 의한 깊은 준위는 열처리 온도의 증가에 따라 금속 불순물과 관련된 깊은 준위로 천이함을 알 수 있다. 또한 고온 열처리의 경우, 초기 산소 농도가 높을수록 깊은 준위의 농도가 감소함을 볼 때 초기 산소 농도가 높을 수록 gettering 효율 측면에서 유리한 것으로 사료된다

• The Journal of Advanced Prosthodontics
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• 제16권3호
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• pp.174-188
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• 2024

PURPOSE. The purpose of this study was to investigate the effects of surface treatments, liquids, and aging on color, translucency, and surface properties of monolithic ceramics. MATERIALS AND METHODS. Lithium disilicate (LDS) and zirconia-reinforced lithium silicate (ZLS) ceramics (n = 135 each) were cut and divided into three groups [crystallization+glaze (single stage), crystallization-glaze (two stages), and crystallization-polish (two stages)]. One sample from each group was examined using scanning electron microscopy (SEM). Remaining samples were divided into four subgroups (distilled water, coffee, grape juice, and smoothie) (n = 11 each), stored for 12 d in the respective liquids, and thermally aged. One sample from each subgroup was analyzed using SEM. The color, gloss, and roughness values of the samples were analyzed after surface treatment (initial) and storage under different liquids+aging conditions. The initial data and both the aged data and data change values were analyzed using robust two- and three-way analyses of variance. RESULTS. The glazed groups exhibited smoother surfaces. Ceramic type and ceramic-surface treatment interactions affected the initial translucency parameter (TP) (P < .001) and the initial and aged roughness values (P ≤ .001). Surface treatment type affected the color change (P < .001), and ceramic type affected the aged TP values (P < .001). Type of ceramic, surface treatment, and their interactions affected both the initial and aged gloss (P ≤ .001) and TP change values (P ≤ .015). Surface treatment type and ceramic-surface treatment interactions affected the gloss change values (P ≤ .001). CONCLUSION. Although both ceramics and all surface treatments are clinically applicable, crystallization-glaze is recommended. When gloss and smoothness are important or when translucency is important, ZLS or LDS may be preferred, respectively.

• Asian Pacific Journal of Cancer Prevention
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• 제16권17호
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• pp.7795-7801
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• 2015

The aim of the present research was to establish primary characteristics of electron beams for a Varian 2100C/D linear accelerator with recently developed PRIMO Monte Carlo software and to verify relations between electron energy and dose distribution. To maintain conformity of simulated and measured dose curves within 1%/1mm, mean energy, Full Width at Half Maximum (FWHM) of energy and focal spot FWHM of initial beam were changed iteratively. Mean and most probable energies were extracted from validated phase spaces and compared with related empirical equation results. To explain the importance of correct estimation of primary energy on a clinical case, computed tomography images of a thorax phantom were imported in PRIMO. Dose distributions and dose volume histogram (DVH) curves were compared between validated and artificial cases with overestimated energy. Initial mean energies were obtained of 6.68, 9.73, 13.2 and 16.4 MeV for 6, 9, 12 and 15 nominal energies, respectively. Energy FWHM reduced with increase in energy. Three mm focal spot FWHM for 9 MeV and 4 mm for other energies made proper matches of simulated and measured profiles. In addition, the maximum difference of calculated mean electrons energy at the phantom surface with empirical equation was 2.2 percent. Finally, clear differences in DVH curves of validated and artificial energy were observed as heterogeneity indexes were 0.15 for 7.21 MeV and 0.25 for 6.68 MeV. The Monte Carlo model presented in PRIMO for Varian 2100 CD was precisely validated. IAEA polynomial equations estimated mean energy more accurately than a known linear one. Small displacement of R50 changed DVH curves and homogeneity indexes. PRIMO is a user-friendly software which has suitable capabilities to calculate dose distribution in water phantoms or computerized tomographic volumes accurately.

• 대한소아치과학회지
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• 제29권4호
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• pp.529-538
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• 2002

불소의 항우식 작용에 대해서는 논란의 여지가 없으며, 소아치과 임상에서 다량의 불소를 함유하고 있는 글라스 아이오노머는 이러한 이유로 선호되고 있다. 유리된 불소가 인접 법랑질의 항우식 효과에 미치는 영향을 평가하기 위하여 in situ 모형을 제작하고, 불소의 침투 경로와 범위 그리고 재광화 정도를 평가하기 위하여 미세 경도 측정법, 편광 현미경 관찰 및 전자 탐침 미소 분석 (EPMA, Electron Probe Micro-Analysis)을 시행하였다. 전통적인 글라스 아이오노머인 Fuji $IX^{(R)}$과 불소를 포함하지 않은 복합 레진인 $Z-100^{(R)}$을 선정하여 미세 경도치의 변화를 분석한 결과, 복합레진에 비해 글라스 아이오노머에 의한 재광화가 가속화됨을 알 수 있었다. 편광 현미경 소견의 변화를 관찰한 결과 구강내 환경에서도 초기 법랑질 우식증이 재광화될 수 있음을 확인하였고, 이러한 과정은 불소에 의해 촉진될 수 있음을 재삼 확인하였다. 전자 탐침 미소 분석 (EPMA) 관찰 결과, 구강내 환경에서 병소 본체 크기 감소를 관찰할 수 있었으며 불소에 의해 가속화됨을 확인하였다. 불소 분포 관찰 결과 농도가 기저부에서 증가하였으며 이는 기저부가 항우식 작용에 중요한 역할을 하는 것으로 생각되었다. 이상의 결과를 종합해 볼 때, 초기 법랑질 우식증은 구강내 환경에서 타액에 의해 재광화될 수 있으며, 이러한 과정은 인접치아에 충전된 글라스 아이오노머로부터 유리된 불소에 의해 더욱 가속화될 수 있음을 알 수 있었다. 글라스 아이오노머로부터 유리된 불소는 병소 본체 기저부에 침착되어 항우식 작용에 중요한 역할을 한다고 판단되며 이를 위해서는 건전 표층의 존재가 매우 중요한 것으로 사료된다.

• 천문학회보
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• 제37권1호
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• pp.92.2-92.2
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• 2012

Previous simulations posed a problem that they used reduced ion to electron mass ratios to save computation time. It was assumed that ion and electron dynamics are sufficiently separated, but it was not clearly verified. In this study, we examine the effect of ion to electron mass ratios on the generation of ion holes by ion beam driven instability. Ion holes are generated via electron holes in an applied electric field with the given initial condition. First, the ion acoustic instability is excited and nonlinearly develops. After the ion acoustic instability nonlinearly develops, the ion two-stream instability is excited and develops into ion holes. This implies that the previously suggested ion beam driven instability is strongly affected by the coupling between ions and electrons and the ion to electron mass ratio is important on the development of the instability. The energy transition and detail variation is different as reduced mass ratio under the same observation value based on FAST satellite. Although, the parameters are rescaled by conserving the kinetic energy to obtain the proper results, the nonlinear evolution is not perfectly identical.

• 한국축산식품학회지
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• 제42권3호
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• pp.411-425
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• 2022

Semi-dried restructured sausages are restructured meat products with a high nutritional and economic value. However, excessively long drying times can have negative effects on the energy consumption, texture, and sensory properties of semi-dried restructured sausages. The objective of this study was to investigate the effects of different water contents on the drying and physicochemical characteristics of semi-dried restructured sausages. Sausages were prepared with different initial moisture contents (0%-50%) and drying time (0-580 min). The drying characteristics, including the drying rate, effective moisture diffusivity, and water activity of sausage were significantly improved as the initial moisture content was increased. When the initial moisture content of the sausage was 50%, physicochemical properties, such as color, porosity, shear force, and volatile basic nitrogen, were improved the most along with the decreased drying time. Scanning electron microscopy data showed greater porosity and pore size in sausages with the increase of initial moisture content. Collectively, our data suggest that an increase in the initial moisture content of semi-dried restructured sausages improves their drying characteristics and physicochemical properties.

• 대한기계학회논문집A
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• 제40권1호
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• pp.23-31
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• 2016

본 연구에서는 연성 금속재료의 판상형 인장 시편에 대한 동적 물성을 측정하기 위한 인장형 홉킨슨 바(TSHB, Tensile split Hopkinson bar)의 수정 방법에 대해 논의하고, 이를 이용하여 고순도 알루미늄 단결정 및 멀티결정재의 동적 물성을 측정하였다. 시편의 초기 미세조직 및 결정학적 방위는 전자후방 산란회절(EBSD, Electron backscattered diffraction) 분석을 통하여 측정하였으며, 동적 변형 후 파단 형상을 광학 현미경을 통하여 확인하였다. 고속인장 변형 중 시편 내부에 발생하는 변형 분포는 디지털 이미지 상관(DIC, Digital image correlation) 기법을 이용하여 측정하였다. 이를 통해 동적 변형 중 나타나는 알루미늄의 거시적인 소성 변형과 결정학적 방위 및 미세 조직과의 상관관계에 대해 논의하였다.

• 한국임상수의학회지
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• 제18권1호
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• pp.55-60
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• 2001

Immunohistochemical and Electron Microscopical Studies on the Initial Skin Lesions Induced Experimentally by Very Virulent Strain of Marek\`s Disease Virus in Chickens Marek\`s disease virus (MDV), which is an avian herpesvirus, causes malignant CD3+CD4+CD8-T cell lymphomas at many sites including visceral organs, muscles, peripheral nerves and skin. In the early skin lesions induced by MDV, corelationship between the translational activity of MDV early gene, pp38 and demonstration of MDV particles in the lymphoid cells are not well studied. Therefore, skin biopsies taken at weekly intervals for 2 weeks from the same specific-pathogen free chicknes inoculated with Md/5 MDV were examined immunohistochemically and electron microscopically. In the skin biopsies sampled at 1 week and 2 weeks post inoculation (PI), feather follicle epithelium (FFE) exhibited usually strong positive reaction for pp38, whereas only few lymphoblasts, which were infiltrated around FFE revealed positive reaction. Electron microscopically, small lymphocytes were detectable in the dermis and subcutaneous skin tissues sampled at 1 week PI. The number of small lymphocytes was increased and pleomorphic lymphoblasts, which were medium to large in size were scattered among the small lymphocytes at 2 weeks PI. Some of lymphoblasts revealed degenerative and necrotic changes. FFE contained a lot of MDV particles in the nucleus including mature and immature ones. Infrequently, immature virus particles were observed not only in the degenerative and necrotic lymphoblasts, but also rarely in the health lymphoblasts. From the present results, spontaneous MDV activation including translational activity of MDV pp38 gene and formation of MDV particles was occurred in the lymphoblasts of early MD skin lesions.

• Journal of Periodontal and Implant Science
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• 제43권6호
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• pp.269-275
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• 2013

Purpose: In this study, the effect of calcium sodium phosphosilicate (NovaMin) desensitizing agent, which is a powder-based system, and hydroxyethyl methacrylate and glutaraldehyde (Gluma desensitizer), which is liquid-based system, on dentinal tubule occlusion was analyzed by scanning electron microscope. The effects of the above two along with one control group were compared to determine the more effective method of sealing the dentinal tubules after initial application. Methods: Twenty specimens were allocated to each of 3 groups: Control, Gluma desensitizer, and NovaMin. Two additional samples were also prepared and treated with Gluma and NovaMin; these samples were longitudinally fractured. The specimens were prepared from extracted sound human premolars and were stored in 10% formalin at room temperature. The teeth were cleaned of gross debris and then sectioned to provide one to two dentin specimens. The dentin specimens were etched with 6% citric acid for 2 minutes and rinsed in distilled water. Control discs were dried, and the test discs were treated with the desensitizing agents as per the manufacturer's instructions. The discs as well as longitudinal sections were later analyzed under the scanning electron microscope. The proportions of completely occluded, partially occluded, and open tubules within each group were calculated. The ratios of completely and partially occluded tubules to the total tubules for all the groups was determined, and the data was statistically analyzed using nonparametric tests and statistical significance was calculated. Results: NovaMin showed more completely occluded tubules ($0.545{\pm}0.051$) while Gluma desensitizer showed more partially occluded tubules ($0.532{\pm}0.075$). The differences among all the groups were statistically significant ($P{\leq}0.05$). Conclusion: Both materials were effective in occluding dentinal tubules but NovaMin appeared more promising in occluding tubules completely after initial application.

• 한국대기환경학회지
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• 제33권4호
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• pp.370-376
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• 2017

This study was performed to investigate whether the decomposition process of $SF_6$ using an electron beam is economically reasonable when applied to the actual field. To do this, electron beam experiment and economic analysis were conducted. The experiment conditions are initial concentration of 1% of $SF_6$, 1 mA of input energy and 15 mA of flow rate with $H_2$ as an additive which were obtained from our previous research. As a result, removal efficiency of $SF_6$ was 90% for 8 hours continuously. In addition, economic analysis shows positive results in terms of using $SF_6$ decomposition process using electron beam. According to the analysis, the revenue is approximately 1.66 billion won in the first year and 3 billion won in the second year.