• Proceedings of the Korean Institute of IIIuminating and Electrical Installation Engineers Conference
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• 2005.05a
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• pp.30-37
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• 2005

태양광 채광시스템은 자연광의 유입이 어려운 공간에 주광을 유입하기 위하여 개발된 장치로써 에너지를 절약하고 인간의 쾌적성을 향상시키는 등 지속가능한 건축을 위해 도입 및 확대가 크게 기대 되는 장치이다. 이에 본 연구는 기존에 본 연구실에서 개발된 시스템의 문제점을 보완하고 개선하여 건축물 적용시의 채광성능을 평가하는데 연구목적이 있다. 본 시스템의 설치는 2004년 10월 25일 (주) 동아산전과의 공동작업으로 설치되었으며, 수원에 있는 K대학 공과대학 5층 옥상 파라펫에 설치하였다. 평가실험은 2005년 4월 5일 9시30분부터 15시30분까지 청천공 상태에서 실시하였고, 총32개의 측정점을 선정하여 주광조도비로 채광성능을 평가하였다. 실험결과, 반사거울을 설치 시 창이 있을 경우 실내의 주광조도비는 평균 20.3[%] 상승하였고 창을 제거할 경우 실내의 주광조도비는 평균 38.2[%]정도 상승하여 채광학적으로 유효한 것으로 분석되었다. 따라서 본 시스템은 건축물의 실내 및 옥외의 음영진 곳에서 유용하게 사용될 수 있음이 입증되었다.

• Journal of IKEEE
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• v.12 no.3
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• pp.131-137
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• 2008

A silicon Fabry-Perot tunable thermo-optic filter for WDM using the thin film silicon coating is proposed and experimented. The filter is implemented by using the CMP process and polishing both sides of the commercial silicon wafer with normal thickness of 100${\mu}m{\pm}$1%. The filter also has 2-layer or 3-layer dielectrics thin film coating mirror which are alternated ${\lambda}$/4 layers of $SiO_2$($n_{low}$=1.44) and a-Si($n_{high}$=3.48) for the central wavelength of 1550nm by RF sputtering. The experiment shows that FSR is 3.61nm and FWHM is 0.56nm and the finesse is 6.4 for 2-layer mirror with the reflection of 61%, and that FSR is 3.36nm and FWHM is 0.13nm and the finesse is 25.5 for 3-layer mirror with the reflection of 89%. According to thermo-optic effect, the transmitted central wavelength of 1549.73nm at $23^{\circ}C$ is shifted to 1550.91nm at $30^{\circ}C$ and 1553.46nm at $60^{\circ}C$ for 2-layer mirror, and the transmitted central wavelength of 1549.83nm at $23^{\circ}C$ is shifted to 1550.92nm at $30^{\circ}C$ and 1553.07nm at $60^{\circ}C$ for 3-layer mirror.

• Korean Journal of Optics and Photonics
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• v.4 no.2
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• pp.206-211
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• 1993

We carried out the second harmonic generation of low power CW laser diode with maximum power of 30 mW in $LilO_3$ crystals. We used a ring enhancement cavity to increase the second harmonic conversion efficiency. The ring enhancement cavity was Composed of two flat mirrors and two concave mirrors. The focal length of concave mirrors was 25 mm, and 5 mm long and 10 mm long $LilO_3$ crystals were used. We measured the second harmonic power according to the pumping power and compared with theoretical value. We obtained 397 nm second harmonic power of about $6.6{\mu}W$ in 10 mm long $LilO_3$ crystal with the fundumental 794 nm pumping power of 28 mW.

• Korean Journal of Optics and Photonics
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• v.7 no.4
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• pp.370-374
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• 1996

A Superstructure Grating(SSG) Distributed-Bragg-Reflector(DBR) laser has a broad tuning range with a good mode suppression ratio. However, gaps of channel are observed in the wavelength-tuning characteristics of an SSGDBR laser which employs linearly-chirped DBR mirrors. We found by numerical simulation that the gaps may be attributed to the nonuniform reflection-peak heights of a linearly-chirped DBR mirrors. We propose a nonlinearly chirped grating DBR mirror structure that makes reflection-peak heights almost uniform. Therefore a nonlinearly chirped grating structure can be employed in an extended tuning range semiconductor laser to achieve gap-free tuning and low threshold current operation simultaneously.

• Proceedings of the Korean Vacuum Society Conference
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• 2010.08a
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• pp.38-38
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• 2010

낮은 세기의 레이저와 정지한 전자가 반응하면 전자는 레이저 전기장 세기에 비례하여 가속되며 레이저의 파장과 같은 파장의 빛을 낸다. 반면, 레이저의 세기가 일정 수준을 넘으면 전자의 속도가 빛의 속도에 가까워지게 되어 가속이 둔화되는 현상이 나타나며, 더 이상 전기장의 세기와 가속도가 비례하지 않게 된다. 이러한 비선형적인 전자의 운동이 레이저 기본 파장의 조화파(harmonic)를 발생시키는데, 이를 상대론적 비선형 톰슨 산란(relativistic nonlinear Thomson scattering, RNTS)이라고 한다. 단일 전자를 가정한 경우 RNTS에 의해 아토초($10^{-18}$ 초) 길이의 X선 펄스가 발생하는 것이 시뮬레이션 연구를 통해 잘 알려졌다. [1] 그러나, 실제 실험에서 적용할 수 있는 것은 단일 전자가 아니라 고체, 플라즈마, 전자 빔 등의 전자 덩어리이다. 전자덩어리를 구성하는 각각의 전자가 아토초 펄스를 발생시더라도 각각의 펄스 간에 결맞음(coherence) 조건이 맞지 않으면 아토초 펄스는 발생되지 않는다. 또한, 강한 세기의 펄스를 얻는데도 결맞음은 중요하다. 이 연구에서는 결맞음 조건으로 얇은 타깃에 대한 거울 반사 조건, 즉 레이저가 얇은 타깃에 입사되며 거울의 반사 조건을 만족하는 위치에 검출기(detector)를 위치시키는 방법을 제안하였다. 박막이 충분히 얇을 경우 각각의 전자에 대하여 레이저가 발사되어 타깃에 맞고 검출되기까지의 시간이 거의 일치하게 된다. 거울 반사 조건에 의한 아토초 펄스 발생은 particle-in-cell 방법을 통한 시뮬레이션으로 검증되었다. 결맞음 조건을 위한 얇은 타깃으로는 박막과 나노선 배열(nanowire array)을 사용하였다. 전자들 간의 쿨롱(Coulomb) 힘은 결맞음이 유지되는 것을 방해하는데, 박막에 비해 나노선 배열이 쿨롱 힘의 영향을 적게 받기 때문에 결맞음이 더 잘 유지된다.

• Journal of Biomedical Engineering Research
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• v.23 no.4
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• pp.287-293
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• 2002

For non-contact nerve stimulations using time varying magnetic field, high amplitude current pulses have to be applied to a magnetic nerve stimulation coil. To increase the magnetic stimulation frequency we have to increase both power supply capacity and cooling capacity of the magnetic nerve stimulator. To alleviate these problems. we propose a new magnetic nerve stimulation coil design methods. Utilizing magnetic mirror effect of a ferro-magnetic plate attached to a magnetic stimulation coil. we have improved efficiency of the stimulation coil. We have analyzed magnetic mirror effect for various kinds of stimulation coils using the finite element method, and we present experimental results obtained with several kinds of stimulation coils.

• Korean Journal of Optics and Photonics
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• v.22 no.1
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• pp.30-34
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• 2011

A novel alignment method that can be used for aligning the collimating mirror employed in a monochromator is described. In most of the spectrometer industry, the alignment of optical components such as a focusing mirror, a grating and a collimating mirror has been performed manually so far. In this paper, we use a matchedfilter based image correlation technique for measuring the accurate image position which is used for aligning the collimating mirror. The experimental results show that with the proposed scheme automatic alignment can be completed within 10 seconds.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.12 no.11
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• pp.5110-5116
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• 2011

In this paper, multiplexing automation system will be proposed for the automobile electromotive mirror using CAN(Controller Area Network) protocol which has been known that it has a high reliability on the signal in the various network protocols. To do this, a master controller and two (input/output) slave controllers (H/W) are being made and application layer (S/W) is being programmed for effective going and communicating between subsystems. The possibility of the effectiveness of application and control ability will be shown when the system has minimum electrical lines by testing the experimental systems which was made up of the automobile electromotive mirror.

• The Transactions of the Korea Information Processing Society
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• v.4 no.12
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• pp.3063-3068
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• 1997

In this paper, we have extended the generalization back-propagation algorithm to multi-layer polynomial higher order neural networks. The purpose of this paper is to describe various pattern recognition using polynomial higher-order neural network. And we have applied shift position T-C test pattern for invariant pattern recognition and measured generalization by mirror symmetry problem. simulation result shows that the ability for invariant pattern recognition increase with the proposed technique. Recognition rate of invariant T-C pattern is 90% effective and of mirror symmetry problem is 70% effective when the proposed technique is utilized. These results are much better than those by the conventional methods.

• The Journal of the Acoustical Society of Korea
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• v.20 no.3
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• pp.91-97
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• 2001

Since the new field information of target signal is important in the development and verification of active sonar system, experimental method and simulation technique are widely used in order to analyze the detail characteristics of target scattered echoes. Therefore, in this paper, the scale target experiment is performed to develope and Improve the target signal simulation model. Since the experimental results show that the specular reflection is the major component among scattering mechanisms, the target signal simulation model based on the Geometric Optics Theory (GOT) is developed. Complex target is separated into simple shapes, known as canonical shape. The contribution from individual canonical shapes are summed with proper phase and amplitude to produce the target strength of the whole complex body. Simulated target signal is compared with the experimental results and discussed.