• 대한치과보철학회지
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• 제34권2호
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• pp.246-265
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• 1996

After adjusting glazed surface of laminate veneer porcelain by reduction in the clinical procedure, an additional polishing procedure is required to smoothen the roughened surface by reduction, as it is difficult to glaze it again in the furnace. In this study, four kinds of laminate veneer porcelain were ground with diamond points as done in the clinical procedure. The adjusted porcelain surface was polished with Durawhite stone, Ceramiste points, Exa cerapol, Porcelain polishing wheel, Diamond polishing paste. The degree of surface roughness was evaluated with SEM and profilometer at each step, The self glazed surface and the glazed surface with glazing powder were compared with the polished surface and surface roughness of four kinds of laminate veneer porcelain according to the polishing method and step were obserbed. The following results were obtained : 1. There was no difference in the average surface roughness Ra value and the surface roughness obserbed under SEM according to the polishing methods and steps used, among the four kinds of laminate veneer porcelain including Colorlogic, Exelco, Vintage, and Vitadur alpha product. 2. Due to porosities, the surface in the course of polishing by polishing instruments was rougher than the glazed surface, evaluated with a SEM. 3. Insta-Glaze diamond polishing paste has no statistical difference with self glazed group 1, although it has a lower value in average surface roughness Ra value. 4. Group 2 which was glazed with galzing powder was lowest in view of SEM, but it revealed higher surface roughness Ra value than group 1, the glazed surface and group 8, polished by diamond polishing paste, due to surface waveness. 5. Proper surface smoothness could not be in the surface roughness analysis of SEM and profilometer by Shofu laminate polishing kit composed of Diamond point, Durawhite stone and Ceramiste points. Based on the results of this study, the following conclusions can be drawn. We obtain low surface roughness than glazed surface by polishing instruments, but not perfect results clinically. In order to obtain a perfect clinical result or a surface smoothness comparable to glazed porcelain there is a need for further improvement of porcelain materials, condensa-tion techniques, polishing instruments and polishing methods. Furthermore card should be taken not to breakdown the glazed surface during the clinical and laboratory procedure.

• 한국농공학회논문집
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• 제59권6호
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• pp.29-37
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• 2017

In this study, we analyzed the impacts of land surface characteristics on spatially and temporally distributed soil moisture values at the Yongdam and Soyang-river dam watersheds in 2014 and 2015. The soil moisture, NDVI (Normalized Difference Vegetation Index) and temperature values at the spatio-temporal scales were estimated using satellite-based MODIS (MODerate Resolution Imaging Spectroradiometer) products. Then the Pearson correlations between soil moisture and land surface characteristics (NDVI, temperature and DEM-digital elevation model) were estimated and analyzed, respectively. Overall, the monthly soil moisture values at the time step were highly influenced by the precipitation amounts. Also, the results showed that the soil moisture has the strong correlation with DEM while the temperature was inversely correlated with the soil moisture. However the monthly correlations between NDVI and soil moisture were highly varied along the time step. These findings indicated that water loss near the land surface are highly occurred by soil and plant activities as evapotranspiration and infiltration during the no/less precipitation period. But the high precipitation amounts reduce the impacts of land surface characteristics because of saturated condition of land surface. Thus these results demonstrated that soil moisture values are highly correlated with land surface characteristics. Our findings can be useful for water resources/environmental management, agricultural drought, etc.

• 대한방사선치료학회지
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• 제28권1호
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• pp.7-16
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• 2016

목 적 : 변형 근치적 유방절제술(modified radical mastectomy, MRM)후 흉벽에 전자선 치료를 받는 환자에게 3D-bolus와 step-bolus를 각각 적용하여 유용성을 비교 평가하였다. 대상 및 방법 : 본 연구는 광자선과 전자선을 이용한 역하키스틱법 방식으로 치료계획이 수립된 총 6명의 유방암 환자를 대상으로 하였다. 전방흉벽에 대한 전자선 처방선량은 회당 180 cGy로 3D 프린터(CubeX, 3D systems, USA)로 제작된 3D-bolus와 본원에서 자체 제작한 기존의 stepbolus를 적용하였다. 3D-bolus와 step-bolus에 대한 표면선량은 GAFCHROMIC EBT3 film (International specialty products, USA)을 이용하여, bolus의 다섯 측정지점(iso-center, lateral, medial, superior, and inferior)에 대한 선량 값을 통해 비교 분석하였다. 또한 3D-bolus와 step-bolus 적용에 따른 치료계획을 각각 수립하여 그 결과를 비교하였다. 결 과 : 표면선량은 3D-bolus 적용 시 평균 179.17 cGy이고 step-bolus는 172.02 cGy였다. 처방선량 180 cGy에 대한 평균 값의 오차율은 3D-bolus 적용 시 -0.47%이고 step-bolus는 -4.43%였다. 측정지점 iso-center에서의 오차율은 3D-bolus 적용 시 최대 2.69%의 차이를 보였고, step-bolus는 5.54%였다. 치료의 오차범위는 step-bolus에서 약 6%이고, 3D-bolus는 약 3%였다. 치료계획을 통해 비교한 흉벽의 평균 표적선량은 0.3%로 큰 차이를 나타내지 않았다. 그러나 폐와 심장의 평균 표적선량은 step-bolus에 비해 3D-bolus에서 -11%와 -8%로 감소하였다. 결 론 : 본 연구 결과로 볼 때 흉벽에 대한 피부표면의 접촉면이 고려된 3D-bolus는 step-bolus에 비하여 환자 피부에 잘 밀착되고, 정밀한 흉벽두께 보상이 가능하기 때문에 선량 균일성이 향상됨을 확인하였다. 또한 흉벽에 대한 선량은 동일하지만 인접장기의 선량을 감소시켜 정상조직을 더 많이 보호함으로써 3D-bolus가 임상적으로 유용한 보상체로 사용될 것으로 사료된다.

• 한국소성가공학회:학술대회논문집
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• 한국소성가공학회 2009년도 추계학술대회 논문집
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• pp.254-258
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• 2009

In this paper, the low frequency vibration forming system is developed for micro-patterns formation on the metal substrate. many researchers have studied about micro-forming technologies such as micro deep drawing, press forming, forging, extrusion etc. for the formation of precise micro-patterns on the surface of metal substrates, multi-step forming process must be used to improve qualifies of the deformed patterns. Since the low frequency vibration forming system could easily deform the surface of metal substrates, several steps of multi-step forming process should be removed by using the low frequency vibration forming system. In order to find optimal process conditions, we have carried out low frequency vibration forming process with varying the vibration frequency from 110Hz to 500Hz.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2009년도 추계학술대회 논문집
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• pp.275-275
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• 2009

CdTe(331)/Si(211) and CdTe(400)/Si(100) thin films have been grown by MOCVD(metal organic chemical vapor deposition) system for large scale of IFPAs(IR focal plane arrays). We have investigated the effect of various growth parameters on the surface morphology and structural quality. Single crystalline CdTe(331) films were grown by two stage growth method - low temperature buffer layer step and high temperature growth step. In other case, single crystal of CdTe(400) films were grown on a few atomic layer thickness of GaAs which is grown on Si(100) substrate by molecular beam epitaxy. The crystalline quality of the films was analyzed by X-ray diffraction. The surface morphology and crystal structure of CdTe films were characterized by optical microscope.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2016년도 제50회 동계 정기학술대회 초록집
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• pp.306.2-306.2
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• 2016

Niobium oxide thin films were synthesized by reactive rf magnetron sputtering. The target was metallic niobium with 2 inch in diameter and the substrate was n-type Si wafer. To control the surface properties of the films, Nb oxide thin films were obtained at various mixing ratios of argon and oxygen gases. Nb oxide thin films were analyzed with alpha step, scanning electron microscopy (SEM), X-ray diffraction (XRD), and X-ray photoelectron spectroscopy (XPS). The result of alpha step showed that the thickness of Nb oxide thin films were decreased with increasing the oxygen gas ratios. SEM images showed that the granular morphology was formed at 0% of oxygen gas ratio and then disappeared at 20 and 75% of oxygen gas ratio. The amorphous Nb oxide was observed by XRD at all films. The oxidation state of Nb and O were studied with high resolution Ni 2p and O 1s XPS spectra. And the change in the chemical environment of Nb oxide thin films was investigated by XPS with Ar+ sputtering.

• Tribology and Lubricants
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• 제11권2호
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• pp.15-23
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• 1995

A zero-load slider is composed of two outside rails which produce a lift force pushing up the slider from the disk surface and a wide reverse step region which produces a suction force attracting the slider to the disk surface. In this paper, the flying characteristics of zero-load sliders are obtained by using an optimization technique. In the pressure calculation module, the FIFD scheme is used to solve the modified Reynolds equation. The BFGS method and a line search algorithm is employed to predict the static flying attitude. To investigate the effect of the geometric- parameters of zero-load sliders on the flying characteristics, recess depth, front step width, rail width, and taper height are varied and the corresponding flying attitudes are obtained. Simulation results demonstrate that recess depth and rail width have significant influences on the flying characteristics.

• 한국소성가공학회:학술대회논문집
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• 한국소성가공학회 2003년도 춘계학술대회논문집
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• pp.278-282
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• 2003

There is a strong industrial demands for the development of light-vehicle to improve fuel efficiency. It is more effective to reduce weight of the parts directly driven by an automobile engine. So the saving in weight of wheels which is operated by an automobile engine improve fuel efficiency more than other parts. There are many step of sheet metal forming in fabricating automotive wheel, so that it is difficult to design process and tools of multi-stage stamping. Traditionally, design process and tools have depended on the experience of skilled workers and it has done by trial and error methods. However, it needs too much costs and time. Taguchi methods has an advantage of the number of required experiments and reliability compared with trial and error method. In this study, Taguchi methods and response surface methods are applied to design process and tools of automotive wheel. As a result, the principal variables are selected and process conditions are optimized.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 1995년도 추계학술대회 논문집
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• pp.191-194
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• 1995

The business of manufacturing is increasingly becomeing time-compresssing, precise and long-life oiented, owing to various needs form the consumers and harsh global competition. with the emergence of the layer laminate maunfacturing methods, it is possible to prototypes directly from 3D CAD and additive process, the production time and cost have shortened dramatically. However there are some problems like surface-step, dimensional deviation and warp. A newly developed powder casting is suitable for rapid-manufacturing metallic tools. Powder casting can serve as a promising repid tooling method because of high density charateristics and low dimensional shrinkage below 0.1% during sintering and infiltration. By this process, we have realized significant time savings bypassing the wait for prototype tooling and cost savings eliminating the expense of conventional prototype tooling process.

• 대한관절경학회지
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• 제2권1호
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• pp.93-96
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• 1998

We treated 10 cases of the medial malleolar fracture of the ankle by open reduction and internal fixation from June 1997 to December 1997. After the rigid internal fixation, we measured the gap of the fracture site and the step off of the articular surface by special instrument under the ankle arthroscopy whether it was reduced anatomically or not. And we tried to know the necessity of the arthroscopically assisted reduction and fixation in the medial malleolar fracture of the ankle. Under the arthroscopic view, all 10 cases were anatomically reduced as less than 1 mm of gap of the fracture site and less than 1mm of step off of the articular surface after open reduction and internal fixation in the medial malleolar fractures. In conclusion, through the arthroscopic management, it has advantage in finding and treating the accompanying intraarticular lesion, but also has disadvantage in setting the arthroscope and prolonging the operation time.