• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 1993년도 추계학술대회 논문집
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• pp.357-362
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• 1993

In this study low priced laser measurement system was made, so its reliability was investigated Intensity distribution of laser beam measured by devised system and FFT analyzer and their results were examined for proving reliability of devised system. Transmitted laser beam intensity on photodiode changed by eccentrically rotating of disk cam and motor speed. To get results, photodiode and devised amplifier were used for changing voltage. After that, response signal was calculated by signal analysis program. It was found that the vibration of disk cam could be measured by the intensity distribution of laser beam and the same tendency was obtained by FFT. Change of motor speed effected the distribution of laser beam,which was obtained by devised system. Also linear distribution was got by sensitive balancing switch on amplifier according to the transmission of laser beam on photodide.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2001년도 춘계학술대회논문집E
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• pp.720-726
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• 2001

Two-dimensional, angle-resolved LDV(Laser Doppler Velocimetry) measurements of the turbulent rotating flow field in a confined cylinder have been performed. The configurations of interest are flows between a rotating upper disk with a rod attached by a disk or impeller(${\theta}= 90^{\circ},\;45^{\circ}$) and a stationary lower disk in a confined cylinder. The mean flow velocity as well as the turbulent intensity of the flow field have been measured. The results show that the flow is strongly dependent on the position of the impellers or the disk, negligibly affected by the Reynolds number in turbulent flow. It is observed that the mixing effect of the axial flow impeller(${\theta}= 45^{\circ}$) is better than that of the radial flow impeller(${\theta}= 90^{\circ}$) or a disk.

• 한국광학회:학술대회논문집
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• 한국광학회 2001년도 하계학술발표회
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• pp.108-109
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• 2001

• Journal of Welding and Joining
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• 제29권1호
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• pp.90-98
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• 2011

Al-Si coated Boron steel and Zn coated DP steel were welded using DISK laser and the microstructure and hardness of the weld were investigated. Full penetration was obtained, when the welding speed was lower than 4m/min. In the specimen welded with laser power of 3 kW and welding speed of 2 m/min, the hardness was the highest in the heat affect zone in the boron steel (HAZ-B) and that of the heat affect zone in the DP steel (HAZ-D) was lower than HAZ-B. The hardness of fusion zone was in between those of HAZ-B and HAZ-D. The decreased hardness from each HAZ to base metal(BM) could be explained that ferrite contents increases when access to the BM. The variation of hardness in the welds could be explained by the difference of microstructure, that is, full martensite in HAZ-B, mixture of martensite and bainite in the fusion zone, and the mixture of martensite, ferrite and bainite in HAZ-D.

• E2M - 전기 전자와 첨단 소재
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• 제8권2호
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• pp.229-236
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• 1995

Multimedia has created a system environment that needs a combination of diverse peripherals, faster I/O, and easier configuration. The sheer volume of data one can expect with multimedia hardware and applications storage systems of higher capacity and faster data transfer rate. Unlike the magneto-optical(MO)disk technology which uses bias magnetic field in writing, both the reading and the writing in the phase change (PC) technology are performed only by laser light. In PC optical media, an active layer is reversibly converted between amorphous state and crystalline state by changing irradiation conditions of focused laser beam. Thus, as compared with MO disk, the PC disk has such great advantages that signals can be reproduced by change of reflectance of laser beams in the same manner as the compact disc. The reflectivity of a phase-change spot can be altered in a single pass under the head only through modulation of laser power. The principles and the current status of phase-change optical recording media combined with possible applications are discussed in the present article.

• 한국광학회지
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• 제3권4호
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• pp.227-233
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• 1992

분할디스크형 글라스레이저 증폭기를 개발하기 위하여 이를 해석 설계할 수 있는 시뮬레이션 코드를 작성했다. 레이저매질에서의 열부하를 감소시키고, 플래시램프의 방사스펙트럼과 레이저글라스의 흡수 스펙트럼 간의 결합효율을 높이기 위해서는 전류밀도를 2000-4000A/$\textrm{cm}^{2}$로 유지하여 단파장에서의 방사에너지를 줄여야 한다. 디스크 증폭기에서 같은 부피를 갖는 매질을 3등분하여 냉각표면적을 3배로 늘렸을 때 온도상승치는 30% 정도로 떨어졌다. 단면펌핑 분할 디스크형 증폭기의 설계에서는 각 글라스 간의 $Nd^{3+}$ 도핑율에 차등을 주어야 하고 플래시램프 앞에 있는 매질의 흡수계수 $\alpha$ 와 두께 d의 곱인 $\alpha$d가 0.26 전후가 적절하다는 것을 알았다.

• 한국정밀공학회지
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• 제19권11호
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• pp.211-220
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• 2002

Optical disk drives read information by replacing a laser beam on the disk track. As information has become larger, the more accurate position control of a laser beam is necessary. In this paper, we report the analysis and fabrication of the micro mirror for optical disk drivers. A coupled simulation of gas flow and structural displacement of the micro mirror using the Finite-Element-Method is applied to this. The mirror was fabricated by using MEMS technology. Especially, the process using the lapping and polishing step after the bonding of the mirror and electrode plates was employed for the Process reliability. The mirror size was 2.5mm${\times}$3mm and it needed about 35V for displacement of 3.2 ${\mu}$.

• 동력기계공학회지
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• 제13권1호
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• pp.33-38
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• 2009

In this study, the nose of cam in the automobile engine was modelled into circular disk to analyze the torsional vibration of the cam shaft. The distance between disks was fixed, but the diameter of disks was changed. The torsional vibration of the cam shaft was studied experimentally by the motion of the modelled disk with changing the disk diameter. And the sizes of the modelled disk were selected not to show the natural frequencies over all the experimental ranges. The torsional vibration meter used in this study has a laser system with non-contact measurement method, which can measure both torsional angular vibration velocity and torsional angular vibration displacement simultaneously. The Experimental analysis shows that the characteristics of the torsional vibration in the horizontal rotating shaft can be considerably affected by the arrangement of the modelled disks.

• 대한기계학회논문집B
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• 제26권5호
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• pp.675-684
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• 2002

Two-dimensional, angle-resolved LDV(Laser Doppler Velocimetry) measurements of the turbulent rotating flow field in a confined cylinder have been performed. The configurations of interest are flows between a rotating upper disk with a rod attached by a disk or impeller($\theta$ = 45$^{\circ}$, 90$^{\circ}$) and a stationary lower disk in a confined cylinder. The mean flow velocity as well as the turbulent intensity of the flow field have been measured. The results show that the flow is strongly dependent on the position of the impellers or the disk, negligibly affected by the Reynolds number in turbulent flow. It is observed that the mixing effect of the axial flow impeller($\theta$ = 45$^{\circ}$) is better than that of the radial flow impeller($\theta$ = 90$^{\circ}$) or a disk.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2001년도 춘계학술대회논문집D
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• pp.589-595
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• 2001

The present study conducted heat transfer analysis in multi-layer of CD-R. It is necessary to analyze heat transfer during the recording process to find optimum power and write strategy in CD-R. This study investigated effects of several parameters such as recording speed, laser power, layer thickness and thermal property. The calculated results presented temperature distribution in the multi-layer and detailed information of recording characteristics. Optimum laser power was estimated, comparing an optimum mark length with the calculated mark lengths. The results showed that the optimum laser power was influenced significantly by the layer thickness and the thermal properties of the dye.