• 한국철도학회:학술대회논문집
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• 한국철도학회 2003년도 춘계학술대회 논문집
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• pp.376-381
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• 2003

This study is focused on the dynamic response of curved bridge when the rubber tired AGT vehicles is running with alternative articulations. For the analytic approach, there is necessary for the three dimensional vehicle model with 11 degree of freedom and the three dimensional curved bridge model by means of finite element method. It can be described by conventional Lagrangian formula with respect to the dynamic interactions between vehicles and its met bridge. The formula is implemented by Fortran language on the simulation program designated BADIA II(Bridge-AGT Dynamic Interaction Analysis II). The solutions of the formula are derived by Newmark- ${\beta}$ method. The BADIA II is for the dynamic interactions between vehicle and curved bridge in terms of the roughness of running surface and guide rail. The applicability of the BADIA II is verified in terms of displacement and modal frequency. This study is described that the dynamic interactive behaviors between the rubber tired AGT vehicle and curved bridge in terms of the radius of curvatures of curved bridge, vehicle articulations, vehicle speeds, vehicle weights, flatness of running surface and roughness of guide rail using BADIA II.

• Current Optics and Photonics
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• 제5권5호
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• pp.576-582
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• 2021

Dichroic beam-splitter (DBS) with polarization-maintaining took an important role in the free space quantum telecommunication tests on the Micius satellite of China. In this presentation, we designed and prepared a 50 layer polarization-maintaining DBS coating by a dual ion beam sputtering deposition (Dual-IBS) method. In order to solve a stress problem, an 18 layer special anti-reflection (AR) coating with similar physical thickness ratio was deposited on the backside. By stress compensation, the surface flatness RMS value of the DBS sample decreased from 0.341 λ (@632.8 nm) to 0.103 λ while beam splitting and polarization maintaining properties were almost kept unchanged. Further, we discussed the mechanism of film stress and stress compensation by equation deduction and found that total stress had a strong relationship with the total physical thickness and the ratio of layer materials.

• 한국세라믹학회지
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• 제48권4호
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• pp.312-315
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• 2011

The effect of slurry composition and wafer flatness on a material removal rate (MRR) and resulting surface roughness which are evaluation parameters to determine the CMP characteristics of the on-axis 6H-SiC substrate were systematically investigated. 2-inch SiC wafers were fabricated from the ingot grown by a conventional physical vapor transport (PVT) method were used for this study. The SiC substrate after the CMP process using slurry added oxidizers into slurry consisted of KOH-based colloidal silica and nano-size diamond particle exhibited the significant MRR value and a fine surface without any surface damages. SiC wafers with high bow value after the CMP process exhibited large variation in surface roughness value compared to wafer with low bow value. The CMPprocessed SiC wafer having a low bow value of 1im was observed to result in the Root-mean-square height (RMS) value of 2.747 A and the mean height (Ra) value of 2.147 A.

• Radiation Oncology Journal
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• 제9권1호
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• pp.131-141
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• 1991

국내에서 처음으로 사용되는 CLINAC 1800에서 발생된 15MV X-선의 특성을 구하기 위하여 3 Dimensional water Phantom Dosimetry system)를 이용하여 방사선 치료에 근간이 되는 심부선량 백분율(POD), 최대 조직 비율(TMR), 편평도(beam profile), 대칭도, Wedge인자 등을 측정하였고 선량계산을 위하여 출력 인자들을 구하였다. 1. 선축상 최대치 지점(Dmax)은 SSD 100cm일때 조사면이 $10\times10cm^2$에서 $3.0\pm0.1$ cm이였고 $4\times4cm^2,\;35\times35cm^2$에서 각각 $3.1\pm0.1\;cm,2.2\pm0.1$ cm으로 조사면이 넓어지면서 측정치가 표면에 가까워지는 결과를 보였다. 2. 조직표면 선량(Surface Dose)는 SSD 100cm일때 조사면이 $10\times10cm^2$에서 $15.5\%$이였고 $4\times4cm^2,\;35\times35cm^2$에서 각각 $9.8\%\;,51.2\%$로 조사면이 넓어지면서 표면 선량은 증가하는 결과를 보였다. 3. 심부선량 백분율(PDO)은 SSD 100cm에서 측정하였고 조사면이 $10\times10cm^2$이고 10cm depth에서 $76.8\%$이였고 $80\%,\;50\%$ 선량의 깊이는 각각 $9.1\pm0.1\;cm,19.9\pm0.2\;cm$으로 측정되었다. 4. 최대조직비율(TMR)은 심부선량 백분율(PDD)로부터 계산하였고 측정값과의 차이는 $10\times10cm^2$ 조사면에서 평균 $1\;%$ 이내의 오차를 보였다. 5. 대칭도(symmetry)와 편평도(flatness)는 조사면 $10\times10cm^2$일때 각각 $0.73\%,\;2.72\%$이였다. 6. 출력인자(output factor)는 $10\times10cm^2$ 기준 조사면에서 흡수선량을 1로 하였을때 $4\times4cm^2,\;35\times35cm^2$ 조사면에서는 각각 0.927, 1.087로 측정되었는데 조사면이 증가할수록 흡수량이 증가하는 결과를 보였다. 7. Wedge factor는 $15^{\circ}\;30^{\circ}\;45^{\circ}\;60^{\circ}$를 10cm깊이에서 측정하였는데 0.825, 0.099, 0.560, 0.457로 각각 측정되었고 아크릴 0.4 mm Tray의 투과율은 0.976이였다. 8. 15 MV X-선에 의한 납벽층의 반가층 두께는 13 mm였고 Cerrobend의 반가층은 15.5 mm으로 측정되었다.

• 한국의학물리학회지:의학물리
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• 제9권2호
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• pp.65-71
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• 1998

1 cm 아크릴 판과 SSD 가 9MeV 전자선의 측방선량분포 및 깊이선량분포에 미치는 영향을 평가하여 아크릴 판을 전자선치료에서 에너지 저하체로 사용하는 타당성이 있는가를 분석하는 것이 목적이다 .Varian Clinac-2100C 에서 발생되는 9MeV 전자선을 7MeV로 저하시키기 위해 lcm 두께의 아크릴 판을 이용하였다. 아크릴 판은 엑스선 표적에서 65.4cm에 있는 전자선응용장치 상단에 두었으며, 조사면의 크기는 SSD 100cm 에서 l0$\times$10cm로 하였다. 100cm, 105cm, 110cm의 세 가지 SSD에 대해 선축상 깊이선량분포와 최대선량점깊이 (1.4cm) 에서 가로방향과 세로방향의 측방선량분포를 3D 물팬톰을 이용하여 측정하였다. 깊이선량분포에서는 최대선량점과 85% 선량점 ,50% 선량점 깊이와 표면에서 평균에너지, 실비정과 표면에서 최빈에너지를 비교하였다. 측방선량분포 측정으로부터 평탄도, 피넘브러폭, 실조사면크기를 비교하였다. 참조를 위한 목적에서 9MeV 전자선도 측정하였다. SSD가 l00cm 에서 l10cm로 증가함에 따라 7MeV 전자의 표면선량율이 85.5% 에서 82.2% 로 감소하였고, 선량증가영역을 제외하고는 깊이선량분포는 SSD에 영향을 받지 않았다. 평탄도는 7MeV가 4.7% 에서 10.4% 로 변하여 9MeV 의 1.4% 에서 3.5% 로 변한 것에 비하여 심하게 변하였다. 피넘브러폭은 7MeV 가 1.52cm 에서 3.03cm 로 증대하여 9MeV 의 1.14 cm에서 1.63cm로 증대된 것에 비해 심하게 변하였다. 7 MeV 전자선의 실조사면크기는 10.75cm에서 12.85 cm로 증대하여 9MeV 전자선의 10.32cm 에서 11.46cm 로 증대하는 것에 비해 심하게 변하였다. 가상선원표면거리는 7 MeV, 9MeV 각각에 대해 49.8cm,88.5cm였다. 에너지 저하체를 이용하는 경우에도 그렇지 않은 경우와 마찬가지로 SSD가 멀어져도 선량증가영역을 제외하고는 깊이선량분포는 변하지 않았다. 에너지 저하체를 사용하면 그렇지 않은 경우에 비해 SSD 가 증가하면 평탄도가 허용범위를 넘어 나빠지고, 피넘브러 폭은 넓어지며 조사면 크기가 더 심하게 커진다. 가상선원표면거리는 현저하게 짧아졌다. 결론적으로 전자선치료에서 특히 먼 SSD 에서 에너지 저하체를 이용하지 않는 것이 바람직하다고 생각된다.

• 소성∙가공
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• 제21권3호
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• pp.202-206
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• 2012

Marking is a process that engraves letters or a pattern onto the surface of sheet metal. During marking, it is important to set the proper working conditions for clarity of the letters. In this study a simple case for forming circular protrusions by half-piercing and embossing was initially attempted to determine the working conditions which gave good results with respect to shape accuracy. Corner-radius and flatness of circular protrusions made under several experimental conditions were measured and compared. It is shown that the precision of protrusions by half-piercing is superior to that of embossing, and the clearance between punch and die exerts a strong influence on the shape accuracy rather than the penetration percentage into the thickness of the sheet metal. The marking dies for "SNUT" letters, as an example, by applying the above results were manufactured with four different clearances. The working variables for the experiment were clearance and marking depth. For the very shallow depth of 0.1mm the letters were not clearly read. Letters marked under other conditions were easily distinguished with increasing marking depth. It was confirmed that the half-piercing technique with proper values of the working variables gives good quality for the marking of sheet metal.

• 한국정밀공학회지
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• 제23권6호
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• pp.174-179
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• 2006

The curing characteristics of a photocurable resin are critical factors that often decide the ultimate resolution and structural sharpness of a final product fabricated by microstereolithography$(\mu-STL)$. In this study, we investigated the curing characteristics of the FA1260T photopolymer under a visible laser light of 42nm wavelength. Modification of the curing property of the FA1260T is attempted to reduce the cure depth $(D_c)$ by adding a radical quencher to the resin. Also, an organic solvent was used to reduce the resin viscosity for an improvement of the flatness of the liquid surface during layer-by-layer curing. As a result, the minimum $D_c$ has been reduced over a factor of 3 with no abrupt increase. Samples of three dimensional microstructures fabricated using the modified FA1260T are presented.

• 한국정보통신학회논문지
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• 제14권1호
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• pp.213-224
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• 2010

본 논문에서는 보정 영상을 프로젝터가 표현할 수 있는 범위로 콘트라스트(contrast)를 조절하여 주는 요소(scaling factor)를 적용하여 색 보정영상을 획득하는 방법을 제안한다. 이 조절 요소는 입력영상과 사용된 표면의 평균 밝기를 이용하여 계산하였다. 또한 사용된 프로젝터 및 카메라의 특성화 과정에서 오는 오차와 부정확성을 해결하기 위하여 프로젝터와 카메라 양단간의 관계를 적용한다. 실험 결과에서 제안한 색 보정 방법이 임의의 표면으로 입력된 다양한 영상에 대하여 밝기를 유지하면서 클리핑 결함은 감소되어 화질이 개선된 것을 확인하였다.

• E2M - 전기 전자와 첨단 소재
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• 제8권3호
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• pp.340-351
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• 1995

Electrical, physical and optical properties of Aluminum(Al), Copper(Cu) thin films were investigated in order to establish the optimum sputtering parameters in Liquid Crystal Display (LCD) panel applications. DC-magnetron sputtered film on coming 7059 samples were fabricated with variations of deposition power densities, deposition pressures and substrate temperatures. Low resistivity films(AI;2.80 .mu..ohm.-cm, Cu:1.84 .mu..ohm-cm),which lower than the reported values, were obtained under sputtering parameters of power density(250W), substrate temperature(450-530.deg. C) and 5*10$\^$-3/ Torr deposition pressure. Expected columnar growth and stable grain growth of both films was observed through the Scanning Electron Microscope(SEM) micrographs. Dependency of the applicable defect-free film density upon depositon power and temperature was also characterized. Not too noticable variations in X-ray diffraction patterns were remarked under the alterations of sputtering parameters. High optical reflectivities of Al, Cu films, approximately 70-90 %, showed high degree of surface flatness.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2002년도 학술대회지
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• pp.815-818
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• 2002

The elliptic relaxation model(ERM) with the inhomogeneous correction intermediate between near wall with and far from the wall. The source of the ERM usually was appled quasi-homogeneous pressure-strain correlation in homogeneous situations. This formulation was easily applied to the linear model or non-linear pressure-strain model. It is observed that the boundary conditions of the relaxation operator dominate the homogeneous pressure-strain model in the near wall region. While looking at high-Reynolds number flows, it was found necessary to modify the effect of the relaxation operator throughout the log region by accounting for gradients of the flatness variable and turbulent length scales. These effects are kinematic blocking of the wall normal velocity fluctuation and pressure reflections from the surface. This model is wall distances and unit vectors which make the model applicable to flows boundary by a complex geometry. Inhomogeneous correction model is computed inertial and non-inertial channel flow These are compared DNS(Kim et at., Kristofffrsen & Andersson) for channel flow. The present model could be predicted well for rotating flows.