• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2003년도 춘계학술대회 논문집
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• pp.1362-1365
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• 2003

On this study. we improved the efficiency applying algorithm that is repeatedly using orthogonal array in discrete design space and filling a defect of gradient method in continuous design space. we showed optimal ply angle that maximized buckling strength of CFRP laminated composite plate without a hole and with a hole by each aspect ratio. In the case of CFRP laminated composite plate without a hole, we confirmed the reliance and efficiency of algorithm in comparison with the result optimization achievement repeatedly using statistical orthogonal array of experimental design.

• Current Optics and Photonics
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• 제1권6호
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• pp.573-578
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• 2017

Position estimation of a sound source based on time difference of arrival at an array of three acousto-optic sensors is introduced. Each sensor consists of a Mach-Zehnder interferometer including a sensing part in one arm that is a piece of fiber surrounded by membrane in order to enhance the acousto-optic effect. Estimation error of a recorded gunshot sound signal was evaluated with the theoretically calculated values for two different locations.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2003년도 추계학술대회
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• pp.1660-1665
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• 2003

On this study, we improved the efficiency applying algorithm that is repeatedly using orthogonal array in discrete design space and filling a defect of gradient method in continuous design space. we showed optimal ply angle that maximized 1st natural frequency of CFRP laminated composite cantilever plate by each aspect ratio. A finite element analysis on the CFRP laminated composite cantilever plate using orthogonal array is carried out, and the results are compared with those obtained by modal testing.

• 한국소음진동공학회논문집
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• 제13권6호
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• pp.423-429
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• 2003

On this study. we improved the efficiency applying algorithm that is repeatedly using table of orthogonal array in discrete design space and filling a defect of gradient method in continuous design space. we showed optimal ply angle that maximized 1st natural frequency of CFRP laminated composite plate without a hole and with a hole by each aspect ratio. In the case of CFRP laminated composite plate without a hole, we confirmed the reliance and efficiency of algorithm in comparison with the result of optimization achievement repeatedly using statistical table of orthogonal array of experimental design and the BFGS optimal design method.

• 한국광학회지
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• 제33권6호
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• pp.245-251
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• 2022

타일형 결맞음 빔결합 연구를 위하여 시드 공유형 다채널 광섬유 레이저 및 출력단, 다중 빔 정렬 기술을 개발하였다. 광섬유 레이저는 7개의 채널을 갖고, 각각의 채널당 출력 10 W 이상으로 시드, 전치 증폭기, 광 분배기, 주 증폭기로 구성된 master oscillator power amplifier 구조이다. 레이저 빔 시준 및 정렬을 위하여 틸팅 기능이 가능한 출력단을 개발하였다. 출력단은 채움값을 높이기 위하여 원통형 구조로 제작하였으며, 광섬유 엔드캡의 결합이 가능하게 하였고, 출력단 내부에 PZT를 장착하여 틸팅 기능을 구현하였다. 다중 채널 레이저의 각 채널 빔을 표적의 한 점으로 정렬하기 위하여 stochastic parallel gradient decent (SPGD) 알고리즘을 적용하였다. SPGD 알고리즘을 이용한 PZT 제어를 통해 다중 빔 정렬을 성공적으로 구현하였다. 다중 빔 정렬 기술을 이용한 결맞음 빔결합 기술 개발이 기대된다.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2004년도 춘계 학술발표회 제16권1호
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• pp.644-647
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• 2004

Modulus of rupture (MOR) and flexural toughness in hybrid fiber reinforced cement pastes mixed with micro-fiber (carbon fiber) and macro-fiber (steel fiber) and replaced with silica fume according to the fixed ratio were researched. Reinforcing efficiency in specimens were estimated by two factors, such as strengthening factor $(F_s)$ and toughening factor $(F_t)$, which were calculated from the analysis of variance (ANOVA) of the response values, such as MOR and absorbtion energy $(W_0)$. According to the experimental design by the fractional orthogonal array, nine hybrid fibrous reinforced paste series and one non-reinforced control paste were manufactured. Specimens of each series were tested by the INSTRON Inc. 8502(model) equipment in three-points bending and then measured the load-deflection response relationships. Considerable strengthening of cement pastes resulted in' the case of other factors without carbon fiber and toughening of cement pastes about all factors showed high. Based on the significance of factors related to response values from ANOVA, following assessments were available; $F_s$ or MOR: silica fume $\gg$ steel fiber $\gg$ carbon fiber; $F_t\;or\;W_0$: steel fiber > carbon fiber > silica fume. Optimized composition condition was estimated by steel fiber of $1.5\%$, carbon fiber of $0.5\%$ and silica fume $7.5\%$ in side of strengthening and steel fiber of $1.5\%$, carbon fiber of $0.75\%$ and silica fume $7.5\%$ in side of toughening.

• 한국해양공학회지
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• 제37권1호
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• pp.31-37
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• 2023

In this study, a fiber chain was developed to replace a steel chain using high-modulus polyethylene DM20. The pick count, wrapping count, and inner length were selected as the main design variables of the fiber chain and were analyzed to increase the breaking strength. Orthogonal array experiments were conducted, and the results were analyzed with respect to the breaking strength. The analysis revealed that the pick count and wrapping count had meaningful effects at significance levels within 5%. The main effect analysis revealed that a smaller pick count, larger wrapping count, and longer inner length caused the breaking strength to increase. With the wrapping count fixed at 1, a pick count less than -0.65, and an inner length greater than 0.38, the breaking strength was calculated to be greater than 300 kN. These results are expected be important factors in the derivation of an optimal combination of design variables to attain a fiber chain with a targeted strength.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2005년도 창립60주년 기념 추계 학술대회
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• pp.153.2-153.2
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• 2005

• ETRI Journal
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• 제38권1호
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• pp.9-17
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• 2016

We demonstrate a time- and wavelength-division multiplexed passive optical network system employing a vertical-cavity surface-emitting laser array-based optical line terminal transceiver and a tunable bidirectional optical subassembly-based optical network terminal transceiver. A packet error-free operation is achieved after a 40 km single-mode fiber bidirectional transmission. We also discuss an arrayed waveguide grating, a photo detector array based on complementary metal-oxide-semiconductor photonics technologies, and low-cost key devices for deployment in access networks.

• Current Optics and Photonics
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• 제6권5호
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• pp.479-488
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• 2022

To account for the internal thermal effects of solid-state lasers, a method using a back propagation (BP) neural network integrated with a particle swarm optimization (PSO) algorithm is developed, which is a new wavefront distortion correction technique. In particular, by using a slab laser model, a series of fiber pumped sources are employed to form a controlled array to pump the gain medium, allowing the internal temperature field of the gain medium to be designed by altering the power of each pump source. Furthermore, the BP artificial neural network is employed to construct a nonlinear mapping relationship between the power matrix of the pump array and the thermally induced wavefront aberration. Lastly, the suppression of thermally induced wavefront distortion can be achieved by changing the power matrix of the pump array and obtaining the optimal pump light intensity distribution combined using the PSO algorithm. The minimal beam quality β can be obtained by optimally distributing the pumping light. Compared with the method of designing uniform pumping light into the gain medium, the theoretically computed single pass beam quality β value is optimized from 5.34 to 1.28. In this numerical analysis, experiments are conducted to validate the relationship between the thermally generated wavefront and certain pumping light distributions.