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장현호,백준혁,Chang, Hyunho,Baek, Junhyeck 한국재난정보학회 2021 한국재난정보학회 논문집 Vol.17 No.3
연구목적: 고속도로 구간의 소통상태 정보제공에 있어 신뢰성 있는 혼잡속도 지표는 핵심이다. 본 연구는 비집계 구간속도 자료를 이용하여 개별 고속도로 구간의 소통상태를 결정하기 위한 순응형 혼잡속도 지표를 제시하는데 그 목적이 있다. 연구방법: 교통류의 상태는 전형적으로 비혼잡 상태, 혼재 상태, 혼잡 상태로 구분된다. 개별 차량의 속도를 이용하여 교통류 상태를 계층화함으로써 도로구간별 혼잡속도 지표를 산정하는 방법론을 개발하였다. 도로구간별 혼잡속도는 혼재상태와 혼잡상태의 차량 속도분포를 이용하여 결정된다. 분석결과: 도로구간별 혼잡속도는 미국과 유럽의 혼잡속도 기준인 48.28 ~ 66.0 kp와 유사하게 분석되었다. 이는 도로구간별로 혼잡 경계속도가 다를 수 있음을 의미한다. 결론: 본 연구에서 제시된 방법론과 혼잡지표는 빅 데이터 시대의 고속도로 구간별 맞춤형 실시간 소통정보제공 및 교통혼잡 비용의 산정에 효율적으로 활용될 수 있을 것으로 기대된다. Purpose: A reliable indicator of congested traffic speed is essential in providing the information of traffic flow states about motorway sections. The aim of this study is to propose an adaptive indicator of congested speed which is employed for deciding the traffic flow states for individual motorway sections using disaggregated section-based speed data. Method: Typically, the state of traffic flow is categorized into the three: uncongested, mixed, congested states. A method, presented in this study, was developed for identifying boundary speed values of road sections through categorizing the three traffic flow states with individual vehicular speed values. The boundary speed state of each road segment is determined using the speed distributions of mixed and congested traffic states. Result: Analysis results revealed that boundary speed values between mixed and congested states for road sections were similar to those of US and EU criteria (i.e., 48.28~66.0 kph). This indicates that boundary speed values could be different according to road sections. Conclusion: It is expected that the method and indicator, proposed in this study, could be efficaciously used for providing ad-hoc real-time traffic states and computing traffic congestion costs for motorway sections in the era of big data.
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.
석정환,한희정,백준혁,장원주,김헌,Seok, Jung-Hwan,Han, Jung-Hee,Baek, Jun-Hyuk,Chang, Won-Joo,Kim, Huhn 한국금형공학회 2017 한국금형공학회지 Vol.11 No.3
Drones can be manipulated in a variety of ways. One of the most common controller is joystick method. But joystick controller uses both hands and takes a long time to learn. Particularly, in the case of 8-character flight, it is necessary to use both front and rear flight (pitch), left and right flight (Roll), and body rotation (Yaw). Joystick controller has limitations to intuitively control it. In particular, when the main body rotates, the viewpoint of the forward direction is changed between the drones and the user, thereby causing a mental rotation problem in which the user must control the rotating state of the drones. Therefore, we developed a motion matching controller that matches the motion of the drones and the controller. That is, the movement of the drone and the movement of the controller are the same. In this study, we used a gyro sensor and an acceleration sensor to map the controller's forward / backward, left / right and body rotation movements to drone's forward / backward, left / right, and rotational flight motion. The motor output is controlled by the throttle dial at the center of the controller. As the motions coincide with each other, it is expected that the first drone operator will be able to control more intuitively than the joystick manipulator with less learning.
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.
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.
레이저 최대 허용 노출에서의 피부 온도 상승에 관한 연구
신성선 ( Seong Seon Shin ),김재영 ( Jae Young Kim ),장경민 ( Kyung Min Jang ),백준혁 ( Joon Hyuck Baek ),양승진 ( Seung Jin Yang ),박종락 ( Jong Rak Park ) 조선대학교 공학기술연구원 2015 공학기술논문지 Vol.8 No.2
Simulations of the absorption of laser pulses and the temperature rise in human tissues were executed for long (pulse width: 100 ms, beam diameter: 0.61 mm) and short (pulse width: 5 ns, beam diameter: 0.33 mm) pulse conditions at 532-nm, 809-nm, 905-nm, and 1064-nm wavelengths. Correlations between maximum temperature rise and maximum permissible exposure recommended by laser safety standards were investigated and discussed in terms of the correction factor CA defined in the laser safety standards.