• Korean Journal of Optics and Photonics
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• v.17 no.6
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• pp.537-543
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• 2006

A method of estimating the distance using single zoom camera limits a distance range(only optical axis) in field of view. So, in this paper, we propose a method of estimating the distance information in Stereoscopic display using the stereo zoom lens module for estimating the distance in the wide range. The binocular stereo zoom lens system is composed using a horizontal moving camera module. The left and right images are acquired in polarized stereo monitor for getting the conversion and estimating a distance. The error distance is under 10mm which has difference between optically a traced distance and an estimated distance in left and right range $(0mm{\sim}500mm)$ at center. This presents the system using a function of the zoom and conversion has more precise distance information than that of conversion control. Also, a method of estimating a distance from horizontal moving camera is more precise value than that from toe-in camera by comparing the error distance of the two camera methods.

• The Journal of the Korea Contents Association
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• v.11 no.4
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• pp.11-17
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• 2011

This paper aims to realize the information of a subject existing in a still image with objective values. To attain the goal, this research takes the vanishing point that a 2D still image has as the basis and recomposes the still image into a 3D image using a 3D program. Also, in order to set up the axis of the camera necessary to recompose a 3D image, this paper used the lens angle of view that the image has and floor patterns as well. The 3D image completed in this way can measure the size and distance of all subjects in the floor patterns if the size value of a particular reference subject is known, and through this, it can be possible to acquire basic information of a subject that can be either a criminal or a clue in the images of CCTVs or some criminal scene.

• Journal of Korean Society for Geospatial Information Science
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• v.7 no.1 s.13
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• pp.53-63
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• 1999

For the close range digital photogrammetry, multi-step procedures should be embodied in an integrated system. However, it is hard to construct an Integrated system through conventional procedural processing. Using Object Oriented Programming(OOP), photogrammetric processings can be classified with corresponding subjects and it is easy to construct an integrated system lot digital photogrammetry as well as to add the newly developed classes. In this study, the equation of 3-dimensional mathematic model is developed to make an immediate calibration of the CCD camera, the focus distance of which varies according to the distance of the object. Classes for the input and output of images are also generated to carry out the close range digital photogrammetric procedures by OOP. Image matching, coordinate transformation, dirct linear transformation and bundle adjustment are performed by producing classes corresponding to each part of data processing. The bundle adjustment, which adds the principle coordinate and focal length term to the non-photogrammetric CCD camera, is found to increase usability of the CCD camera and the accuracy of object positioning. In conclusion, classes and their hierarchies in the digital photogrammetry are designed to manage multi-step procedures using OOP and close range digital photogrammetric process is implemented using CCD camera in an integrated System.

• Korean Journal of Optics and Photonics
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• v.5 no.1
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• pp.166-172
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• 1994

The fiber optic receiver, ETRI APD-FET 1.0, is developed for the application of optical communication. This fiber optic receiver includes PD sub-module and pre-amplifier case. A single lens system is introduced for the PD sub-module. The sub-module consists of the avalenche photodiode(APD), GRIN rod lens, and a single mode fiber. The above components are enclosed into the stainless steel 304L housings. By bevelling the fiber end, the single mode fiber provides less than ~ 28 dB of optical return loss. The area of image focus is controlled by adjusting the length of spacer located in-between the fiber and the GRIN rod lens. The laser welding technique is applied to achieve the maximum coupling efficiency for the joining of each housing. In the pre-amplifier case, GaAs FET pre-amplifier workes for photocurrent amplification and the thermister is mounted to control the APD bias. The performance of ETRI APD-FET1.0 shows the sensitivity of - 30.3 dBm at $10^{-10}$ BER(bit error rate) and 2.5 Gbps optical random signal of $2^{23}-1$ word length. The fiber optic receiver is one of the essensial parts of the transmission module for B-ISDN. Also, the above optical packaging technology will be adapted for the developement of 10 Gbps transmission application 2.5 Gbps 5 Gbps

• Korean Journal of Optics and Photonics
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• v.19 no.2
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• pp.140-143
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• 2008

The integrated external cavity laser has been fabricated with a 1550 nm FP-LD, an optical filter, a micro ball lens and accurate ceramic blocks using a micro-block stacking (MBS) technique. The integrated external cavity laser module whose size is only $2.0{\times}2.1{\times}0.7\;mm^3$ has been mounted on the TO-CAN package. For the case of the 1.8% transmission filter, the single mode characteristic has been obtained with the optical power of -27.1 dBm and the SMSR of 31.7 dB.

• Proceedings of the Acoustical Society of Korea Conference
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• spring
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• pp.395-398
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• 1999

본 연구에서는 초음파현미경에서 다중의 동작주파스를 사용하여 얻어진 영상을 합성하여 깊이분해능이 개선된 초음파영상을 복원하는 방법을 연구하였다. 실험을 위하여 중심주파수가 5MHz이고 비대역폭이 $35\%$인 초음파변환기를 사용하여 초음파현미경을 구성하였다. 시편은 알루미늄을 이용하여 표면에 깊이가 $100{\mu}m$이고 지름이 2mm인 원형결함을 제작하였다. 실험결과, 동작주파수가 5MHz인 단일 주파수를 사용하여 얻어진 영상에서 결함이 존재하는 면과 그렇지 않은 면에 대한 콘트라스트가 0.098로 나타났다. 반면에 동작주파수를 $4.4MHz\~5.6MHz$ 범위에서 200kHz씩 변화시키면서 획득한 데이터를 합성하여 얻어진 영상에서 결함이 존재하는 면과 그러하지 않은 면에 대한 영상 콘트라스트가 0.398로 나타났다. 따라서 초음파현미경에서 다중의 동작주파수를 사용한 경우, 피사체의 깊이 변화에 대한 영상의 콘트라스트가 단일주파수를 사용한 경우에 비하여 개선되어 나타났으며 깊이분해능이 향상되었다. 앞으로의 과제는 초음파현미경에서 음향렌즈의 집속도 변화에 대한 적절한 동작주파수의 동작범위와 영상의 분해능과의 관계에 대한 연구가 계속되어져야 한다고 본다.

• Journal of the Korean Society for Marine Environment & Energy
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• v.19 no.4
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• pp.341-348
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• 2016

Micro-algae, one of the biological resources for alternative energy, has been heavily studied. Among various methods to analyze the status of the micro-algae including counting, screening, and flocculation, the flocculation approach has been widely accepted in many critical applications such as red tide removal study or microalgae resource study. To characterize the flocculation status of the micro-alga. A traditional optical modality, i.e., photospectrometry, measuring the optical density of the flocs has been frequently employed. While this traditional optical method needs shorter time than the counting method in flocculation status analysis, it has relatively lower detection accuracy. To address this issue, a novel real-time micro-algae flocculation analysis method based on the lens-free shadow imaging technique (LSIT) is introduced. Both single cell detection and floc detection are simultaneously available with a proposed lens-free shadow image, confirmed by comparing the results with optical microscope images. And three shadow parameters, e.g., number of flocs, effective area of flocs, and maximum size of floc, enabling quantification of the flocculation phenomenon of micro-alga, are firstly demonstrated in this article. The efficacy of each shadow parameter is verified with the real-time flocculation monitoring experiments using custom developed cohesive agents.

• Korean Journal of Optics and Photonics
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• v.5 no.2
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• pp.304-310
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• 1994

The use of thermally expanded core (TEe) fibers fabricated by thermal diffusion of dopants such as $GeO_{2}$ in hybrid fiber components has an advantage of eliminating lenses for collimation and focusing. An electric furnace is fabricated to heat the fibers locally for the core expansion. We observed an expansion of the mode size at $1.3\mu\textrm{m}$ wavelength by 27% after treating a section of single mode optical fiber at $1250^{\circ}C$ for 10 hours. hours.

• Proceedings of the Optical Society of Korea Conference
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• 2000.02a
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• pp.218-219
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• 2000

정보화 사회의 발전과 더불어 디스플레이는 CRT의 고성능화와 병행해 각종 평판 디스플레이의 전개와 실용화가 진행되어 왔다. TV용은 CRT (cathod ray tube)방식이 시장의 90% 이상을 차지하고 있으며, 앞으로도 연간 약 3%의 성장이 예상된다. CRT는 많은 공간 소비와 높은 소비전력 유해파 등으로 인하여 가정용 TV의 경우 PDP가 컴퓨터 모니터는 LCD방식이 디스플레이 시장의 주역을 담당하고 있으며, 그 성능, 비용, 용도에 따라 나뉘어 빠른 비율로 성정해 갈 것으로 예상된다. 이러한 여러 가지 평판 디스플레이들은 특성에 따라 EL과 FED는 10인치 이하의 소형 디스플레이에 주로 사용되어 지며, LCD는 10인치 이하에서부터 30인치까지의 소·중형, CRT는 10인치 이상 40인치 이하의 중·대형에 사용되어 지고, PDP는 30인치 이상의 대형 디스플레이에 사용된다. 대형 PDP나 LCD는 휘도를 높이고 양질의 영상 표현을 위해서는 cell-gap의 균일성이 요구되어 진다. cell-gap의 측정은 제품이 거의 완성 단계 있을 때 이루어져야 함으로 비접촉식이 필연적이며, 실시간 적이어야만 가능하다. (중략)

• Korean Journal of Optics and Photonics
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• v.10 no.3
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• pp.201-207
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• 1999

The fiber-optical confocal scanning interference microscope with a simple configuration was constructed with a 4-port fiber-optic coupler, and the new method based on the phase shifting method was proposed for surface profiling by the system. In the method, the height of a specimen was determined from the phase of confocal beam. It was verified experimentally that the method was applicable to even the confocal interference microscope with a long-wavelength source and a low NA objective, and that the scanning time could be drastically reduced compared with the conventional method. Finally, it was found that our method is less sensitive to the variation of surface reflectivity than the conventional method.