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레이저 흡수에 의해 발생하는 열 효과의 빔 직경 및 흡수 계수 의존성
장경민 ( Kyungmin Jang ),백준혁 ( Jun-hyeok Baek ),양승진 ( Seung-jin Yang ),정재훈 ( Jae Hoon Jung ),권민기 ( Min-ki Kwon ),박종락 ( Jong-rak Park ) 조선대학교 공학기술연구원 2016 공학기술논문지 Vol.9 No.2
The thermal effects induced by pulsed laser absorption in an optical medium were simulated. In particular, the dependences of maximum temperature increase and decay time constant on the laser beam diameter and the medium absorption coefficient were investigated. The maximum temperature increase showed the inverse square dependence on the laser beam diameter, and the decay time constant was found to be almost independent of the laser beam diameter for relatively large absorption coefficients. As the absorption coefficient increased, the maximum temperature increase increased and the decay time constant decreased. The maximum temperature increase was directly proportional to the absorption coefficient, and the decay time constant was found to be almost independent of the absorption coefficient for relatively small laser beam diameters.
레이저 흡수에 의해 발생하는 열 효과의 펄스 폭 의존성
장경민 ( Kyungmin Jang ),양승진 ( Seung Jin Yang ),백준혁 ( Jun Hyeok Baek ),김재영 ( Jae Young Kim ),정재훈 ( Jae Hoon Jung ),권민기 ( Min Ki Kwon ),박종락 ( Jong Rak Park ) 조선대학교 공학기술연구원 2016 공학기술논문지 Vol.9 No.1
We investigated the thermal effects induced by pulsed laser absorption in an optical medium. In particular, the dependences of maximum temperature increment and decay time constant on the laser pulse width were examined. As the laser pulse width was increased, the maximum temperature increment was decreased and the decay time constant was increased. It was found that the temporal behaviors of the temperature increment could be predicted by the convolution of the response function of the system with a very short laser pulse and a square pulse function corresponding to the laser pulse width.
남승화(SeungHwa Nam),장경민(KyungMin Jang),서송원(SongWon Seo),정필규(PilGyu Jeong),정은상(EunSang Jung),권세진(Sejin Kwon) 한국추진공학회 2020 한국추진공학회 학술대회논문집 Vol.2020 No.11
본 연구에서는 전산유체역학을 이용하여 155 mm 고체연료 램제트 포탄을 설계하였다. 필요한 기본 매개변수들을 설정하였으며 이를 이용하여 초기 수치를 결정하였다. 전산수치해석을 이용하여 성능을 고려한 경사면 각도를 정하였고 충격파 위치가 Cowl lip에 중첩되게 하는 2단 경사면을 가지는 흡입구를 설계하였다. 연료 그레인은 HTPB에 AP파우더 15 wt.%, Al 파우더 5 wt.%가 혼합된 형태로 구성되어 있다. 연료 그레인의 연소 반응식을 이용해 연소실 전산수치해석을 진행하였으며 요구추력이 발생함을 확인하였다. In this study, a 155 mm solid fuel ramjet projectile was designed using computational fluid dynamics. Set the necessary parameters required for the design, and the initial values were determined using them. The inclination angle considering the performance was determined and designed the supersonic inlet with a two-stage slope that superimposed the shock wave on the cowl lip using computational fluid dynamics. The fuel grain consists of a mixture of HTPB with 15 wt.% AP powder and 5 wt.% Al powder. Computational fluid dynamics of the combustion chamber was carried out using the species reaction of the fuel grain, and it was confirmed that the required thrust was created.
LED와 태양광 하이브리드 광원을 이용한 광생물 반응기용 도광판 설계 및 제작
임현철,양승진,백준혁,김재영,장경민,김종태,정상화,박종락,Lim, Hyon-Chol,Yang, Seung-Jin,Baek, Jun-Hyeok,Kim, Jae-Young,Jang, Kyungmin,Kim, Jongtye,Jeong, Sanghwa,Park, Jong-Rak 한국광학회 2016 한국광학회지 Vol.27 No.2
In this paper, we report the results of a study on the design and fabrication of a light-guiding plate (LGP) using a hybrid light-emitting diode (LED) and sunlight source that can be applied to a photobioreactor. LGP patterns for the LED source were designed and engraved on an LGP, together with previously reported patterns for a sunlight source. A control system for the hybrid LGP was designed to maintain the output photon flux density (PFD) from the LGP at a constant value. When the target value of the output PFD was set to $70{\mu}E/(m^2{\cdot}s)$, the error range of the output PFD was found to be within ${\pm}2%$. 본 논문에서는 광생물 반응기의 조명 시스템에 적용할 수 있는 LED(Light-Emitting Diode)와 태양광 하이브리드 광원을 이용한 도광판의 설계 및 제작 결과에 대해 보고한다. LED용 도광판 패턴을 설계하고 기존에 보고된 태양광용 도광판에 함께 중첩하여 가공하였다. 하이브리드 도광판의 출력 PFD(Photon Flux Density)를 일정하게 유지시켜주기 위한 제어 시스템을 제작하였으며, 출력 PFD 목표값을 $70{\mu}E/(m^2{\cdot}s)$로 설정하였을 경우 오차범위 ${\pm}2%$ 이내에서 제어가 이루어짐을 확인하였다.
레이저의 피부 흡수에 의해 발생하는 축 방향 변위의 펄스 폭 의존성에 관한 연구
양승진 ( Seungjin Yang ),백준혁 ( Junhyeok Baek ),김재영 ( Jaeyoung Kim ),장경민 ( Kyungmin Jang ),박종락 ( Jongrak Park ) 조선대학교 공학기술연구원 2015 공학기술논문지 Vol.8 No.3
In this study, simulations of the axial displacement generated in human tissues by pulsed laser absorption were executed. The temporal width of the laser pulse was varied from 1 ns to 1000 ns, while the pulse energy and the beam diameter were set to 9.6 mJ and 0.5 mm, respectively. It was found that the magnitude of the axial displacement decreased as the laser pulse width increased. When the laser pulse width was ~500 ns, the magnitude of the axial displacement dropped to half of that for the 1-ns pulse width. The magnitude of the axial stress was also examined and found to be rapidly reduced with the increase of the laser pulse width.