• 천문학회보
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• 제39권2호
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• pp.100.2-100.2
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• 2014

The DOTIFS is a new multi-object Integral Field Spectrograph (IFS) planned to be designed and built by the Inter-University Center for Astronomy and Astrophysics, Pune, India, (IUCAA) for cassegrain side port of the 3.6m Devasthal Optical Telescope (DOT) being constructed by the Aryabhatta Research Institute of Observational Sciences, Nainital. (ARIES) It is a multi-integral field unit (IFU) spectrograph which has 370-740nm wavelength coverage with spectral resolution R~1200-2400. Sixteen IFUs with microlens arrays and fibers can be deployed on 8 arcmin field. Each IFU has $8.7^{{\prime}{\prime}}{\times}7.4^{{\prime}{\prime}}$ field of view with 144 spaxel elements. 2304 fibers coming from IFUs are dispersed by eight identical spectrographs with all refractive and all spherical optics. In this work, we show optical design of the DOTIFS spectrograph. Expected performance and result of tolerance and thermal analysis are also shown. The optics is comprised of f=520mm collimator, broadband filter, dispersion element and f=195mm camera. Pupil size is determined as 130mm from spectral resolution and budget requirements. To maintain good transmission down to 370nm, calcium fluoride elements and high transmission optical glasses have been used. Volume Phase Holographic grating is selected as a dispersion element to maximize the grating efficiency and to minimize the size of the optics. Detailed optics design report had been documented. The design was finalized through optical design review and now ready for order optics.

• 한국기계가공학회지
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• 제21권1호
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• pp.90-94
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• 2022

Metal 3D-printing technology enables the manufacture of complex features or internal structures, which is not possible in fabrication by conventional cutting methods. The most successful types of metal 3D printing have been powder bed diffusion and directed energy deposition, which use laser heads exploiting high-power laser sintering metal powder. In this study, a cost-effective optical design was proposed for a 2-kW-level fiber laser head. Only two commercial lenses, a beamsplitter and a window, are used in the laser head, satisfying the technological requirements. According to the optical design, the spot size was 2.54 mm, and the stand-off distance from the laser head was 295 mm. The intensity distribution was Gaussian. Thus, smooth power sintering was possible without any laser spot marks. Monte Carlo analysis was employed to verify the consistency of the optical performance under conventional assembly tolerance.

• 의료ㆍ복지 건축 : 한국의료복지건축학회 논문집
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• 제29권1호
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• pp.7-19
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• 2023

Purpose: Mobility impairment persons are all people who experience mobility difficulties in their daily lives, which makes up about 30% of the population in Seoul Metropolitan City; this number is expected to increase with population aging. As the number of mobility impairment persons in need of vision correction increases, it is necessary to create the Universal Design guidelines and to provide the foundation to access convenience facilities at the entrance of optical shops, a health and medical institution. Methods: Of the 2,282 optical shops located in Seoul, 252 optical shops were chosen for data collection of actual photos, from April 10, 2022 to September 4, 2022. Based on the photographs, the height difference between the entrance and the sidewalk, safety handles, and opening and closing methods of entrances were investigated, as these factors correspond to the accessibility and the mobility of the mobility impairment persons. Results: Of the 252 optical shops surveyed, 114 (45.2%) have resolved the problems of height difference through improving horizontal accessibility (61) or using ramps (53). 36 (14.3%) optical shops chose automatic doors for opening and closing methods of the entrance. Implications: The rate of installation of access convenience facilities for the entrance of optical shops is slightly lower than the rate of installation of ramps, surveyed by the Ministry of Health and Welfare. It is necessary to apply the Universal Design to access convenience facilities for the entrance of optical shops for not only the mobility impairment persons but all people, regardless of age or ability, to conveniently access healthcare services.

• 한국통신학회논문지
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• 제25권3A호
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• pp.443-450
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• 2000

Although designing a virtual topology for all-optical WDM wide-area networks has been extensively studied and several algorithms have been proposed, these algorithms assumed error-free communication between two nodes. However, noises from optical amplifiers and optical cross-connects can degraded the signal, resulting in a nonzero bit-error rate. In this paper, we investigate the effect of physical limitations on the virtual topology design. We show that for side-area all-optical networks where transmission distance is fairly long, virtual topology design algorithm that can determine the locations of opto-electronic(OE) and electro-optic(EO) conversions to set up a connection request with a high BER in a multihop manner.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2000년도 추계종합학술대회 논문집(1)
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• pp.473-476
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• 2000

WDM is a very promisinig technique for the realization of future All-Optical networks. WDM gives an advantage of high rate transmission without delay for Electronic/optical conversion. But the available number of wavelengths is limited by technical restriction. so the efficient optical path routing and wavelength assignment is needed. this paper is concerned with the efficient design of WDM optical transport networks. RWA assumes that the connection demands between node pairs are given. the objective of RWA is to minimize the number of wavelengths. these design consider the static routing and wavelength assignment in the network of arbitrary topology. To solve these problems, this paper proposes some heuristic algorithms.

• 전자공학회논문지A
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• 제32A권10호
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• pp.64-72
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• 1995

In this paper, atmospheric turbulence and absorption under clear weather condition, which affect the optical satellite up-link communication between geo-satellites and earth station, were studied. In case of the up-link communication, the received optical power is weakened by pointing loss caused by beam tilt which is the main effect of turbulent atmosphere. This pointing loss directly has relation to the diameter of optical transmitting antenna. From the inverse proportion of the pointing and spaced loss, it is the regions where the diameter of transmitting antenna increases abruptly and the efficient design of transmitting antenna is impossible. In case of using channel coding, it was shown that the peak value of diameter moved to the lower regions of elevation angle with increasing the coding gain and its width was also decreased. In case of considering both coding gain and transmission rate on the design of transmitting antenna, it was known that more coding gain was necessary as transmission rate was increased.

• Journal of the Optical Society of Korea
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• 제13권3호
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• pp.341-348
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• 2009

We report the development of full-field swept-source optical coherence tomography (SS-OCT) in the wavelength range of 815-870 nm using a unique combination of super-luminescent diode (SLD) as broad-band light source and acousto-optic tunable filter (AOTF) as a frequency-scanning device. Some new applications of full-field SS-OCT in forensic sciences and engineering materials have been demonstrated. Results of simultaneous topography and tomography of latent fingerprints, silicon microelectronic circuits and composite materials are presented. The main advantages of the present system are completely non-mechanical scanning, wide-field, compact and low-cost.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2003년도 춘계학술대회논문집
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• pp.1165-1169
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• 2003

This paper presents an approach to optimally design the air-bearing surface (ABS) of the optical flying head for near-field recording technology (NFR). NFR is an optical recording technology using very small beam spot size by overcoming the limit of beam diffraction. One of the most Important problems in NFR is a head disk interface (HDI) issue over the recording band during the operation. A multi-criteria optimization problem is formulated to enhance the flying performances over the entire recording band during the steady state. The optimal solution of the slider, whose target flying height is 50 nm, is automatically obtained. The flying height during the steady state operation becomes closer to the target values than those fur the initial one. The pitch and roll angles are also kept within suitable ranges over the recording band. Especially, all of the air-bearing stiffness are drastically increased by the optimized geometry of the air bearing surface.

• 제어로봇시스템학회논문지
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• 제17권3호
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• pp.218-222
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• 2011

This paper proposes a single-joint optical torque sensor with one body structure. Conventional optical torque sensors consist of three parts, two plates and an elastic structure. They have slightly slipping problem between plates and elastic structure due to the manufacturing tolerance. Since the order of measurement range of optical sensor is about ten micrometers, the slipping problem causes large measurement error, especially in the case of vibrational or high speed plant. This problem does not occur in the proposed design due to the one body structure. The proposed sensor has advantage of low cost, light weight, and small size. And it is easy to design and manufacture. Simulation works that analysis of stress and strain are performed accurately. To demonstrate the performance of proposed sensor, experiments were implemented to compare with a commercial force/torque sensor (ATI Mini45).

• 한국컴퓨터정보학회논문지
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• 제22권11호
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• pp.31-37
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• 2017

In this paper, we propose efficient design and construction of an infrared wide angle optical system with low distortion utilizing a high resolution detector for automobile application. The operational convenience and the recognition ability have been improved significantly by applying the high resolution uncooled thermal detector with wide angle optical design. The active ahtermalization mechanism is implemented so that the adjustment of the optical component of the system is to be made automatically according to the temperature change by motorized control. The modulation transfer function (MTF) is about 50% at the Nyquist frequency close the diffraction limit. The distortion is less than 5% at the edge field. As a result, a high-resolution uncooled thermal optical system with wide field of view (FOV) is assembled, aligned and its performance is tested successfully.