• 대한기계학회:학술대회논문집
• /
• 대한기계학회 2001년도 추계학술대회논문집B
• /
• pp.54-58
• /
• 2001

The measurement method of the spectral emissivity by using hemispherical mirror which has an inclined observation hole is studied. This method is useful in measuring the spectral emissivity of the solid material both conductor and non-conductor. In this study, the effective reflectivity of the hemispherical mirror is also measured for calculating the spectral emissivity of materials. The effective reflectivity measured is 0.9.

• 대한기계학회논문집B
• /
• 제27권6호
• /
• pp.789-795
• /
• 2003

It is studied that the measuring method of the spectral emissivity by using hemispherical mirror with an inclined observation hole. The in-service calibration method of mirror reflectivity is also dealed with. It is possible to apply this method on measuring emissivity of conductor or non-conductor.

• 한국정밀공학회:학술대회논문집
• /
• 한국정밀공학회 1996년도 춘계학술대회 논문집
• /
• pp.24-28
• /
• 1996

Mirror-like polishing system of hemisphericall high-speed precision bearing for digital VTR drum was developed. Mechamism of the polishing process was analyzed in the view point of polishing contact range and contact length between the tool and the workpiece surface. It was suggested that the two stage polishing process adoptiong the diamond grinding wheel and polishing tool instead of multistage lapping processes, which enables the mass production of the bearing by reduction of polishing time.

• Journal of Welding and Joining
• /
• 제21권7호
• /
• pp.65-70
• /
• 2003

Thermal emissivity is generally affected by surface situation of material such as roughness. In this study, the effect of surface roughness on measuring thermal emissivity is experimented. And emissivity measurement method and equipment using hemisperical mirror is also reviewed. As the result of this research, thermal emissivity increased as long as increasing surface roughness. So, surface roughness is a essential check point when we measure the emissivity.

• 한국공작기계학회:학술대회논문집
• /
• 한국공작기계학회 1996년도 춘계학술대회 논문집
• /
• pp.124-131
• /
• 1996

The use of small hemispherical high-speed precision bearing has increased drastically these days in the field of computer disk driver, highteech devices as well as communication and electronic device drivers. It was suggested that the new polishing process adopting the diamond grinding wheel and polishing tool instead of multi stage lapping processes, which enables the mass production of the bearing by reduction of polishing time. Polishing mechanism was analysed and the results were applied to the design and manufacturing of the polishing system. Experiments for selection of optimal polishing conditions were carried out using the polishing system.

• 한국산업융합학회 논문집
• /
• 제4권1호
• /
• pp.35-40
• /
• 2001

A spectral measurement system for reflection and transmission properties by using an optical fiber and an ellipsoidal mirror was newly developed. The hemispherical reflectance and transmittance spectra of several heating resisting ceramics materials were measured from visible to middle infrared region. The directional characteristics of reflection and transmission were also investigated in consideration of the absorptance. The measured data were analyzed by using a four flux model of radiation transfer, The radiation properties could be estimated by the obtained scattering and absorption coefficient spectra.

• 한국전산유체공학회:학술대회논문집
• /
• 한국전산유체공학회 2009년 춘계학술대회논문집
• /
• pp.170-175
• /
• 2009

Shock focusing is related with explosive release of shock wave energy on a narrow spot in a short duration of time triggering a spontaneous high pressure near the focal point. It is well known that reflection of planar incident shock wave from the metallic concave mirror such as ellipsoidal, paraboloidal or hemispherical cavities will focus on a focal point. We intend to improve the computational results using a wave propagation algorithm and to resolve the mushroom-like structure. For computation of the concave cavity flow, it is not easy to use a single-block mesh because of the many singular points in geometry and coordinates. We have employed a uniform Cartesian-grid method for the wave propagation algorithm.

• 정보저장시스템학회논문집
• /
• 제2권4호
• /
• pp.224-229
• /
• 2006

There has been studied flow to minimize the spot size to increase data capacity. Optical data storage devices are being developed near practical limits with wavelength and NA of 405nm and 0.85. There has been studied many types of next generation storage devices such as blu-ray multilayer system, probe based data storage and holographic data storage. Among these data storage devices, solid immersion lens(SIL) based near field recording (NFR) has been widely studied. In this system, SIL is the key component that focuses the laser beam with a very small size which enables ultra high data capacity. Therefore, optical performance evaluation system is required for SIL assembly. In this dissertation, a simple and accurate SIL assembly measurement method is proposed with wedge plate lateral shearing interferometer(LSI). Wedge plate LSI is cheaper than commercialized interferometer, robust to the vibration and the moving distance for phase shifting is large that is order of micrometer. We designed the thickness, wedge angle, material, surface quality and wavelength of wedge plate as 1mm, 0.02degree, fused silica, lamda/10(10-5) and 405nm, respectively. Also, we confirmed simulation and experimental results with quantitative analysis. This simple wedge plate LSI can be applied to different types of SIL such as solid immersion mirror(SIM), hemispherical, super-hemispherical and elliptical SIL.

• 한국컴퓨터그래픽스학회논문지
• /
• 제26권3호
• /
• pp.133-142
• /
• 2020

본 연구는 1대의 프로젝터를 이용하여 360도 파노라마를 구현할 수 있는 방법을 하드웨어적인 부분과, 투사 될 사전왜곡 이미지 제작 부분에 대해 기술하고 있다. 관람객의 위치에 따라 발생하는 그림자를 최소화하기 위하여 공간의 중앙 천정에 프로젝터와 반사경을 설치하는 방법을 제안하고 있다. 유니티 엔진 가상공간에서 프로젝터 및 반구 반사경의 위치를 전시공간과 동일하게 설정한 후, 프로젝터를 가상 카메라로 간주하고 환경을 렌더링하여 프로젝터를 이용하여 투사할 때 사용할 사전왜곡 이미지를 생성하였다. 스크린에 투사할 이미지를 가상공간의 벽면에 맵핑시켜 놓은 뒤 레이트레이싱 기법을 이용하여 가상 카메라에 가상 촬영 (레이 트레이싱)하는 방식으로 사전 왜곡 이미지를 제작 하였다. 본 기법의 특징은 사전왜곡 이미지 생성에 사용자가 최소한으로 개입한다는 것이다. 사전왜곡 이미지를 가상 카메라와 동일한 위치에 설치된 프로젝터에서 반구형 반사경에 투사하면 반구경 거울에 의해 이미지가 사방으로 반사되어 원통형 또는 사각방 모양의 파노라마 스크린에 360도로 투영된다.