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- 저자 : 송윤석(Yun Seok Song) (검색결과 13 건)
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자외선 차단제가 악안면 실리콘의 색변화에 미치는 영향에 관한 연구
송윤석,임주환,조인호,Song, Yun-Seok,Lim, Ju-Hwan,Cho, In-Ho 대한치과보철학회 1999 대한치과보철학회지 Vol.37 No.3
The color change of maxillofacial silicone has been attributed to certain environmental factors such as exposure to the UV component of natural sunlight, wetting and drying of the elastomer and surface abrasion resulting from the application and removal of cosmetics. The purpose of this study was to evaluate the color change of maxillofacial silicone (Silastic MDX4-4210) according to type of pigment (cadmium yellow, titanium white, cosmetic red), and UV absorber application method after 200, 400, and 600 hours of 350nm UV light irradiation. The results were as follows. 1. According to type of pigments, after 200 hours cosmetic red showed significantly larger color change than cadmium yellow and titanium white, and after 400 and 600 hours color change significantly decreased in the order of cosmetic red, cadmium yellow, and titanium white (p<0.05). 2. In the cadmium yellow group, after 200 hours, the non-treatment group showed significantly larger color change, but after 400 and 600 hours, color change significantly decreased in the order of non-treatment, surface application and mixed group (p<0.05). 3. In the titanium white group, there was no significant color change difference between the three groups after 200 and 400 hours, but after 600 hours, the mixed group showed significantly smalt or color change than the non-treatment and surface application groups (p<0.05). 4. In the cosmetic red group, there was significant decrease in color change in the order of non-treatment, surface application and mixed group (p<0.05). From the results above, the effect of UV light absorber differed according to the type of pigment, but mixing UV light absorber with maxillofacial silicone is thought to give superior resistance against UV light irradiation in the long run.
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알칼리와 열처리에 의한 임플란트의 표면 특성 및 골유착 안정성에 관한 연구
송윤석,조인호,Song, Yun-Seok,Cho, In-Ho 대한치과보철학회 2008 대한치과보철학회지 Vol.46 No.5
생체 활성 재료는 생체 내에서 자가적으로 인회석 층 (apatite layer)을 형성하여, 골과의 생화학적 결합이 가능해야 한다. 알칼리와 열처리를 통하여 생체 활성 표면을 얻을 수 있는 것으로 보고되고 있다. 본 실험에서는 알칼리 및 열처리를 시행한 임플란트들의 안정성을 평가하고자 하였다. 실험군의 분류로 1군은 대조군인 선반 가공 임플란트군, 2, 3군은 $60^{\circ}C$, 5 M의 NaOH 용액에 24시간 처리한 후, 각각 대기 중 및 진공 상태 $600^{\circ}C$에서 1시간 동안 열처리하였다. 처리된 시편은 FESEM, XPS, TF-XRD 및 AFM을 이용하여 표면 특성을 관찰하고, 임플란트의 안정성을 위해 공진 주파수와 페리오테스트 및 역 토오크를 측정하고, 골유착 안정성에 관한 차이를 비교 분석하여 다음과 같은 결과를 얻었다. 1. 표면 특성: 알칼리 및 열처리를 시행한 2, 3군은 비슷한 양상의 거친 표면을 보여주었다. 알칼리 처리를 시행한 2군과 3군에서 1군과는 달리 높은 함량의 나트륨 이온이 검출되었으며, 결정구조 분석 결과 2군에서 예추석 (antase)과 금홍석 (rutile)이 혼재된 상태로 금홍석이 우세한 양상을 보여주었다. 2. 공진 주파수 분석: 군간 비교에서 12주에 2군이 1, 3군에 비해 통계적으로 유의하게 높은 측정치를 보였다. 주간 비교시, 1, 2군은 4주 이후에 유의한 증가를 보여주었고, 3군은 2주와 4주에서 각각 유의한 증가를 보여주었다 (P < .05). 3. 페리오테스트 분석: 주간 비교에서 1, 2군은 4주 이후에 유의하게 감소를, 3군은 2주와 4주에서 각각 유의한 감소를 보여주었다 (P< .05). 4. 역 토오크 분석: 군간 비교에서는 2, 4, 8주에서는 2군이 1, 3군에 비해 유의하게 높은 측정값을 보여주었다. 주간 비교에서는 1, 3군은 4주, 12주에서 유의한 증가를 보여주었고, 2군은 4주부터 유의한 증가를 보여주었다 (P < .05). 이상의 결과로 볼 때, 알칼리 및 대기 중 열처리를 통해서 적절한 결정 구조의 산화막을 가진 생체 활성화된 무정형의 나트륨 티탄산염 층을 얻을 수 있었고, 알칼리 및 진공 상태 열처리만으로도 나트륨이 함유된 생체 활성화된 표면을 얻을 수 있었다고 사료된다. 또한 이런 처리 과정으로 형성된 표면층들은 임플란트의 초기 골유착에 도움을 줄 수 있는 유용한 방법 중 하나라고 사료된다. Statement of problem: Bioactive materials must have the ability to spontaneously form a bone like apatite layer on their surface and induce direct biochemical bonding to bone. A simple chemical treatment via alkali and heat has been revealed to induce bioactivity in titanium. Purpose: The purpose of this study was to evaluate the surface characteristics and stability of alkali and heat treated implants. Material and methods: Specimens were divided into three groups; group 1 was the control group with machined surface implants, groups 2 and 3 were treated with alkali solutions and heat treated in the atmosphere and vacuum conditions respectively. The surface characteristics were observed with FESEM, XPS, TF-XRD and AFM. Stability was evaluated with the resonance frequency analysis, periotest and removal torque values. One-way ANOVA and Duncan test were used for statistical analysis. Results: 1. Groups treated with alkali and heat showed similar characteristics. Groups 2 and 3 showed high compositions of Na ions on the surface with sub-micron sized pores compared to group 1. Group 2 showed mixed compositions of anatase and rutile with superior contents of rutile. 2. Resonance frequency analysis : The ISQ of group 2 showed significantly higher values than that of groups 1 and 3 at 12 weeks. The ISQ of groups 1 and 2 showed significant increase after 4 weeks, and the ISQ of group 3 increased significantly after 2 and 4 weeks respectively (P < .05). 3. Periotest: The PTV of groups 1 and 2 showed significant decrease after 4 weeks, and the PTV of group 3 showed significant decrease after 2 and 4 weeks respectively (P < .05). 4. Removal torque analysis: The removal torque value of group 2 was significantly higher than those of groups 1 and 3 at 2, 4 and 8 weeks. The removal torque values of groups 1 and 3 showed increase at 4 and 12 weeks, but the removal torque value of group 2 showed increase after 4 weeks (P < .05). Conclusion: An oxide layer with appropriate crystal structure and amorphous sodium titanate layer can be obtained on titanium implants through alkali and heat treatment in the atmosphere, and even alkali and heat treatment in vacuum conditions, provided a bioactive surface containing sodium. These surface layers can be considered to be effective for enhancement of osseointegration and reduction of healing period for implant treatment.
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수분을 함유한 바이오디젤 에멀젼 연료 액적의 연소 특성 연구
송윤석(Yun Seok Song),임영찬(Young Chan Lim),서현규(Hyun Kyu Suh) 한국연소학회 2022 한국연소학회지 Vol.27 No.2
This study conducted droplet combustion experiments on diesel, palm oil, and canola oil containing water to compare and analyze droplet combustion characteristics. This experiment was performed depending on the changes in various droplet diameters of 1.387 ~ 1.731 mm of diesel(D100), biodiesel(BDC100 and BDP100), and water emulsion diesel and biodiesel(D-W, BDC-W, and BDP-W) to compare combustion behaviors such as ignition delay, micro-explosion, flame extinction and lifetime. As a result of the experiments, viscosity makes micro-explosions strong, and strong micro-explosions have the effect of reducing flame extinction time and lifetime. The difference between a micro-explosion and ignition delay with diesel emulsion fuel and biodiesel emulsion fuel is considered to be the difference in properties between the two fuels. The emulsion fuels had a great influence on micro-explosion, flame extinction, and lifetime depending on the viscosity of the fuel. However, diesel emulsion fuels with weak micro-explosion showed increasing ignition delay due to the high latent heat of the water. Based on this, it plans to conduct experiments on the effect of the difference in fuel viscosity on combustion behavior.
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이창민(Chang-Min Lee),윤린(Rin Yun),문현만(Hyeun-Man Moon),송윤석(Yoon-SeoK Song),최동규(Dong-Guo Choi) 대한설비공학회 2010 대한설비공학회 학술발표대회논문집 Vol.2010 No.11
The theoretical modelling for designing of the MVR(mechanical vapor recompression) and the TVR(thermal vapor recompression) in the chemical process has been conducted in the present study. The steam compressing process in the MVR is modelled as the polytropic process, and the other losses for the bearing, sealing, and gear parts are all considered in calculating the actual power consumption. The designing of the nozzle in the steam jet ejector for the TVR is carried out by applying the model, which was developed through the conservation laws of mass and energy. The sizes of the ejector is determined by the semi-empirical models. This model is applied to design the actual sized MVR and the TVR in the chemical process.
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이창민(Chang-Min Lee),윤린(Rin Yun),문현만(Hyeun-Man Moon),송윤석(Yoon-Seok Song),최동규(Dong-Guo Choi) 대한기계학회 2011 대한기계학회 춘추학술대회 Vol.2011 No.5
MVR의 경우 압축과정을 폴리트릭픽과정으로 가정하여 이론적 모델링을 수행하였고, 그 성능은 제작사에서 제공된 성능곡선을 사용하여 평가하였다. TVR의 해석 및 설계에 있어서는 노즐과 디퓨저를 포함한 내부에 유체유동에 대한 보존방정식을 적용하여 분석하였다. 이를 통해 노즐과 목, 그리고 디퓨저의 크기를 결정할 수 있었다. MVR와 TVR의 이론적 모델링은 3개회사의 설계자료와 그 성능 및 에너지 및 질량수지를 비교하여 검증하였고, 본 모델의 실용적 적용을 위해 GUI 설계 툴을 개발하였다. 본 툴을 활용해 MVR과 TVR의 물질 및 에너지수지와 이들의 세부 설계규격을 결정할 수 있다. The MVR was theoretically modeled by assuming the process as the polytropic process, and the performance of the MVR was estimated by using the performance-curve provided by the manufactures. The TVR was investigated by applying the conservation equations to the movement of the fluids inside the TVR. The size of the nozzle and diffuser can be determined. The theoretical MVR and TVR modeling was verified by comparing the results from the model with the available design data. Besides, the GUI program was developed for the practical usage of the modeling. The mass and energy balance information, and the specifications for the MVR and TVR can be available by using the GUI tool.
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