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조성욱(Sungwook Jo),임경일(kyungil Lim),김윤섭(Yoonsub Kim),김정하(Jungha Kim) 한국자동차공학회 2015 한국자동차공학회 부문종합 학술대회 Vol.2015 No.5
There are many problems that generating path to traking UGV(Unmanned Ground Vehicle) in the real time in addition, most of path generation algorithm dose not take into account the kinematic characteristics of the vehicle. It is essential that path generation based to Scenario according to tracking situation. in this paper, we proposed that recognition of preceding vehicle and available overtaking path generation and path planning in restricted environment(ex. Highway). we used to LiDAR sensors, creates a path to overtake the preceding vehicle by update of obstacle in the global map based on grid. In consideration of the minimum distance(d1) can overtaking the preceding vehicle according to the entrance speed of the vehicle. minimum distance(d1) was used determined to start node. path planning is determined to judgment of overtaking about avoidance path generation, traking of front vehicle. we applied to TLPA<SUP>*</SUP> algorithm, generates overtaking path. TLPA<SUP>*</SUP> algorithm was defined by Suboptimality bound throught restrict to(∈) re-search area. using a TLPA<SUP>*</SUP> algorithm was more faster existing path generation algorithm therefore, using to LiDAR sensors, traking a front vehicle and updates position of current vehicle and obstacle and overtaking path in global map. finally, we proposed that fast and safety generating path of overtaking and path planning.
강섬유의 구조적 파라미터에 따른 콘크리트의 전자파 차폐효과 분석
조성희(Sunghui Jo),조경용(Kyeongyong Cho),노영훈(Yeong-Hoon Noh),이남곤(Namkon Lee),김성욱(Sungwook Kim),육종관(Jong-Gwan Yook) 한국전자파학회 2021 한국전자파학회논문지 Vol.32 No.6
강섬유는 콘크리트에 함유될 경우, 다양한 건축학적 장점이 있어 자주 쓰이는 소재이며, 이는 도전율이 큰 물질이기에 건축물의 전자파 차폐효과를 증가시키는 역할을 한다. 이에 본 논문에서는 강섬유 보강 콘크리트의 차폐효과를 강섬유의 구조적 파라미터에 따라 분석하였다. Jonscher 모델을 이용하여 콘크리트의 등가 유전율을 추출하였고, 전자기 시뮬레이션 툴을 이용하여 해당 콘크리트를 모델링하였으며, 강섬유의 방향, 개수, 길이에 따른 전자기적 특성을 분석하였다. 그 결과, 강섬유의 구조적 파라미터에 따른 입사파의 편파, 차폐효과의 레벨, 그리고 공진 주파수의 인과관계를 도출하였다. Steel fiber is a material frequently used when contained in concrete because of its various architectural advantages, and it plays a role in increasing the electromagnetic shielding effectiveness (SE) of the building owing to its high conductivity. Thus, this study analyzed the SE of the steel fiber reinforced concrete (SFRC) according to the structural parameters of the steel fiber. The equivalent permittivity of concrete was extracted using the Jonscher model; The concrete was modeled using the electromagnetic simulation tool, and the electromagnetic properties were analyzed according to the orientation, number, and length of the steel fiber. Thus, depending on the structural parameters of the steel fiber, the causal relationship of the polarization of the incident wave, level of the SE, and resonance frequency was derived.
Transmission-Type Polarization-Insensitive Polarization Plane Excitation
Ryu, Uh-Chan,Jo, Songhyun,Choi, Sungwook,Lee, Seul-Lee,Jeong, Jun Hyeok,Jeong, Sun Jae,Christian, Nouaze Joseph,Kim, Jihoon,Kang, Hyun Wook,Nam, Seung Yun American Scientific Publishers 2017 Journal of Nanoscience and Nanotechnology Vol.17 No.11
<P>In optical communications, light polarization of optical signals is randomly varied during the signal transmission, and system performances can be deteriorated by polarization-dependent loss and gain or polarization-mode dispersion. Polarization scrambling that actively changes the state of polarization (SOP) using a polarization modulation method is often utilized to reduce polarization-related impairments. To make use of polarization-dependent routing devices during the transmission, however, scrambled or depolarized light should be polarized and then scrambled again after passing through the routing devices. Here, we suggest a novel polarization-insensitive polarization plane excitation scheme that enables transmission-type polarization-dependent routing elements to exploit their polarization-dependent routing functions irrespective of the SOP and degree of polarization of an input beam. The proposed scheme is composed of a polarization beam splitter (PBS) for a polarization-diversified loop, two half-wave plates (HWPs) and two 45 degrees Faraday rotators (FRs) for irreciprocal polarization transformation. We could make unpolarized light selectively excite one of the two principal axes of a polarization-dependent element using the polarization decomposition/superposition property of the polarization-diversified loop and the irreciprocal nature of optical Faraday rotation. The operation principle of the proposed scheme is explained using the polarization evolution of light passing through the PBS, FRs, and HWPs that comprise the scheme. The theoretically predicted operation was experimentally verified by utilizing a long-period fiber grating (LPFG) inscribed on high birefringence fiber (HBF) as a polarization-dependent element. The LPFG written on HBF has polarization-dependent loss bands at two resonance wavelengths. By controlling the four waveplates, one of the two loss bands of the LPFG could be selected even for unpolarized input light.</P>
Wavelength-Switchable Erbium-Doped Fiber Ring Laser Using Inline Fiber Bragg Grating Filter
Lee, Seul-Lee,Park, Kyongsoo,Jo, Songhyun,Choi, Sungwook,Jeong, Jun Hyeok,Jeong, Sun Jae,Christian, Nouaze Joseph,Kim, Jihoon,Lee, Yong Wook American Scientific Publishers 2017 Journal of Nanoscience and Nanotechnology Vol.17 No.10
<P>Here, we propose a wavelength-switchable erbium-doped fiber (EDF) ring laser by harnessing the unique switching feature of an inline fiber Bragg grating (FBG) filter based on a polarization-diversified loop. The inline filter consists of a four-port polarization beam splitter, three quarter-wave plates (QWPs), and two FBGs with different Bragg wavelengths. By adjusting the orientation angles of the three QWPs, this inline filter can select one of the two different resonances of the two FBGs. The proposed laser is composed of EDF pumped by a 980 nm laser diode, a wavelength-division multiplexing coupler, an optical isolator, a 3 dB optical coupler, and the inline FBG filter. At a special combination of the orientation angles of the three QWPs, one of the two reflection spectra of two FBGs could be chosen and thus the lasing wavelength of the proposed laser, which corresponds to the Bragg wavelength of the selected FBG, could be switched by adjusting the QWP angles. The fabricated ring laser accomplished stable and uniform lasing at each Bragg wavelength or switching operation between two wavelengths at proper QWP angle sets.</P>
IN 738LC 합금의 미세조직 열화와 물성의 상관성 연구
유정훈,주성욱,신기삼,허성강,이재현,김의현,정진성,장성호,송기욱,하정수,Yoo Junghoon,Jo Sungwook,Shin Keesam,Hur Sungkang,Lee Je-Hyun,Kim Eui-Hyun,Jung Jine-sung,Chang Sungho,Song Geewook,Ha Jeongsoo 한국재료학회 2004 한국재료학회지 Vol.14 No.1
IN 738LC, the major material for gas-turbine for power generation, was heat treated at $750^{\circ}C$, $850^{\circ}C$, $950^{\circ}C$ for 1000, 2000, and 4000 hrs and the microstructural evolution and mechanical properties were examined using optical microscope, XRD, SEM/EDS. The results showed ${\gamma}$', the main strengthening elements in this alloy, was about 300 nm in size and was about 56% by area fraction in as-cast samples. The area fraction of ${\gamma}$' peaked at 2000 hours at $750^{\circ}C$. The average diameter of the ${\gamma}$' which was about 300 nm at ascast specimen increased to about 1 $\mu\textrm{m}$ after heat treatment at $950^{\circ}C$ for 4000 hrs. Carbides were formed at dendrite, cell or grain boundaries which was ascribed to the segregation caused by solute redistribution during solidification. It was found that MC type carbides formed at low temperature, whereas carbides of $M_{23}$ /$C_{ 6}$/ type formed at higher temperature or at longer degradation. The hardness and impact energy decreased as the heat treatment temperature or time of retention increased, which was inaccrodance with the area fraction of ${\gamma}$'.