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A Cavity-Backed Traveling Wave Antenna for Tri-Band GPS Applications
Yonghyun Yoon,Byungje Lee IEEE 2016 IEEE antennas and wireless propagation letters Vol.15 No.-
<P>A cavity-backed tri-band antenna is proposed for the global positioning system (GPS) operating at 1176.45 MHz (L5 band), 1227.60 MHz (L2 band), and 1575.42 MHz (L1 band). The right-hand circular polarization (RHCP) of the proposed antenna is achieved by feeding a cross-type traveling wave antenna at one end and by terminating with a load at the other end. Without using the complicated feed network or the dual-fed structure, the proposed single-feed RHCP antenna gives wide impedance bandwidth (VSWR < 2), wide axial ratio (AR < 3 dB) bandwidth, and high RHCP gain (> 4 dBic).</P>
윤용현(Yonghyun Yoon) 한국정보전자통신기술학회 2019 한국정보전자통신기술학회논문지 Vol.12 No.4
본 논문에서는 자율주행자동차를 지원하기 위한 전방향성 특성의 이중대역 안테나를 제안한다. 제안된 안테나는 4G/LTE 대역 (1,710~2,170MHz)과 5G/NR 대역 (3,400~3,700MHz)을 동시에 지원하기 위한 50Ω의 단일급전이 이용된 새로운 구조의 이중대역 평판 모노폴(Dual-band Planar Monopole) 안테나의 특징을 가진다. 이중대역 특성을 위해 평판 모노폴 안테나에 측면 방사체를 추가 한 후 슬릿을 통하여 목표 성능에 최적화 되었다. 평판 모노폴 구조는 LTE 대역에서 동작하며, 동일 급전을 사용하는 모노폴 구조에 추가된 측면 방사체와 함께 5G NR 대역에서 동작을 한다. 제안된 안테나는 96.0mm의 지름을 갖는 접지면 위에 38.5 × 36.0 × 1.0[mm³]의 크기로 설계되었다. 제작과 측정결과로부터 LTE 대역의 1,710~2,170MHz와 5G NR 대역의 3,400~3,700MHz에 대하여 VSWR 2:1 이하를 만족하였으며, 해당 주파수 대역에서 각각 1,480~2,260MHz와 3,310~3,930MHz의 넓은 임피던스 대역폭을 얻을 수 있었다. 또한 무반사 챔버의 측정결과로부터 제안된 평판 모노폴 안테나의 이득과 전방향성 방사패턴(Omni-directional Radiation Pattern)을 확인하였다. In this paper, a dual-band antenna is proposed for the autonomous vehicle as well as omni-directional. The proposed antenna operates in the 4G/LTE band (1,710~2,170MHz) and 5G/NR band (3,400~3,700MHz). In order to obtain the dual-band operation, the planar monopole antenna is proposed as the novel structure with single port of the 50ohm. To give the properties of dual-band, an additional antenna element with slit was added to the planar monopole antenna, and then a structural adjustment parameter was optimized for achieving the target performance in bands. The planar monopole antenna in the LTE band acts as the coupled feed for the added parasitic radiator in the 5G NR band. The proposed antenna has 38.5 × 36.0 × 1.0[mm³] on a ground with diameter of 96mm. From the fabrication and measurement results, the impedance bandwidth (VSWR<2) of the proposed antenna covers 1,480~2,260MHz (LTE band: 1,710~2,170MHz) and 3,310~3,930MHz (5G NR band: 3,400~3,700MHz). The proposed planar monopole antenna also obtained the measured gain and radiation pattern of omni-directional radiation pattern in the anechoic chamber.
CFD를 활용한 토르크 컨버터의 편평화와 유체 성능 유지 양립의 달성
윤정석(Jungsuk Yoon),장한별(Hanbyul Jang),윤용훈(Yonghyun Yoon),최종윤(Jongyun Choi) 한국자동차공학회 2015 한국자동차공학회 학술대회 및 전시회 Vol.2015 No.11
According to increasing the minimization requirement of vehicle parts, the minimization requirement for torque converter of the auto transmission is also increasing. But the minimization of torque converter has technical issue to be to secure fluid performance about reducing of fluid domain. In this study, the flat torus was considered as minimization of torque converter and the countermeasure is proposed to reduce the fluid performance degradation by flattened torus. The fluid performance of torque converter was confirmed by using CFD analysis data, and results of CFD analysis was modified by experiment data. By results of CFD analysis, the cause of fluid performance degradation for flat torus was to be analyzed and the new torus shape was proposed to able to satisfy the both torus minimization and securing fluid performance.
Yonghyun, Lee,Minhyuk, Kim,Jisoo, Kim,Nayeon, Choi,Seungsang, Yoon,Seongtaek, Park ASCONS 2021 INTERNATIONAL JOURNAL OF EMERGING MULTIDISCIPLINAR Vol.5 No.4
Background/Objectives: This study was conducted to review and verify the effectiveness of the increase in express trains and train volume, which are currently being introduced step by step, through big data analysis, and to suggest additional new alternatives. Methods/Statistical analysis: Therefore, this study used papers and various statistical data to improve congestion on Seoul Subway Line 9 for service diagnosis and evaluation of the current Seoul Subway Line 9, and derived results through R, an open source. Findings: As a result of the analysis, direct trains connecting Gayang and Dangsan, residential areas, to Yeouido and Sinnonhyeon, business-intensive areas, are operated to minimize commuting congestion. Improvements/Applications: The results of this study are expected to be used as useful guidelines for planning not only subway lines 9 but also other subway lines.
Business Groups and Corporate Social Responsibility : Evidence from Korea
Yoon K. Choi,Seung Hun Han,Yonghyun Kwon 한국재무학회 2018 한국재무학회 학술대회 Vol.2018 No.05
This study examines the effect of business group structure on the performance of corporate social responsibility (CSR) in Korean firms using the Korea Economic Justice Institute’s (KEJI) index as a proxy for CSR ratings. We find that chaebol affiliation, the existence of a professional corporate foundation for CSR activities, and firm- and group-level financial donations is positively related to CSR performance. However, family firms, family-controlled business groups, and the existence of individual family owners are associated negatively with CSR performance. Overall, our results suggest that internal capital markets in business groups can improve CSR performance through internal resource allocation, potentially through corporate foundations, although family control can weaken the positive effect. This study contributes to the literature by examining the influence of business groups’ group-wide management (i.e., ‘spillover effect’ within the group) on CSR performance, consistent with the efficient internal capital market hypothesis of business groups.
Lee, Yonghyun,Kim, Jeongyun,Kim, Hyunjeong,Kang, Sookjin,Yoon, Jeong‐,Hyun,Kim, Dae‐,Duk,Kim, Young Mi,Jung, Yunjin Wiley Subscription Services, Inc., A Wiley Company 2012 journal of pharmaceutical sciences Vol.101 No.5
<P><B>Abstract</B></P><P>To develop a colon‐specific prodrug of celecoxib, a cyclooxygenase‐2 selective inhibitor, which could improve cardiovascular toxicity and therapeutic effectiveness for chemoprevention of colorectal cancer, aspart‐1‐yl celecoxib (A1C) or aspart‐4‐yl celecoxib (A4C), succinyl celecoxib (SC), and <I>N</I>‐succinylaspart‐1‐yl celecoxib (SA1C) or <I>N</I>‐succinylaspart‐4‐yl celecoxib (SA4C) were prepared and evaluated as a prodrug with such beneficial properties. On incubation with the small intestinal contents while SC, SA1C, and SA4C were stable, A1C and A4C were degraded to liberate celecoxib. In the cecal contents, the other conjugates except for SC and SA4C were cleaved to release celecoxib. These results suggest the colon‐specific delivery and activation of SA1C. On oral administration of SA1C or celecoxib, no SA1C was detected in the blood and urine, indicating the limited absorption of SA1C. SA1C delivered a much greater amount of celecoxib to the large intestine while keeping the plasma concentration of celecoxib at much lower level, which is consistent with no change of the serum level of 6‐ketoprostaglandin F<SUB>1α</SUB> whose decrease is associated with the cardiovascular toxicity of celecoxib. Moreover, SA1C administered orally supplied a greater concentration of celecoxib for the whole colonic tissue. Taken together, SA1C may be a colon‐specific prodrug of celecoxib with improved therapeutic properties. © 2012 Wiley Periodicals, Inc. and the American Pharmacists Association J Pharm Sci 101:1831–1842, 2012</P>