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A TWA Optical Receiver with Hybrid Integrated InP Detector
Hyeon Cheol Ki,Carl S.P. Chun,Joy Laskar,Nan Marie Jokerst,Martin A.Brooke,Yong-Sun Yoon,Jin Yeong Kang,Dong Sung Ma 한국정보과학회 1999 Journal of Electrical Engineering and Information Vol.4 No.6
To investigate the usefulness and feasibility of the TWA structure for low cost wide band system applications we designed a TWA optical receiver using low cost commercial process. The measured results show it is possible to achieve 18 ㎓ bandwidth with 7㏈ gain using low cost GaAs MESFET process with 20 ㎓ cut-off frequency. We also try, for the first time, the operation of an hybrid integrated OEIC using a fabricated TWA optical receiver and a thin film photo-detector 50㎛ in diameter. These results demonstrate that it is feasible to applicate TWA for the low cost wide band systems and to hybrid integrate wide band MMIC with thin film detectors for inexpensive high speed OEICs.
Micromachined lens microstages for two-dimensional forward optical scanning
Park, Hyeon-Cheol,Song, Cheol,Jeong, Ki-Hun The Optical Society 2010 Optics express Vol.18 No.15
<P>This work presents a novel approach for a miniaturized optical scanning module based on lateral and piston motion of two commercial lenses by MEMS actuation. Two aspheric glass lenses of 1 mm diameter are assembled on two electrostatically actuated microstages moving along perpendicular axes to tilt optical path. The compact integration secures the effective beam aperture of 0.6 mm within the device width of 2 mm. The lens mass provides high-Q motions at low operating voltages of DC 5 V and AC 10 V, i.e., the lateral angle of 4.6 degrees at 277 Hz and the vertical angle of 5.3 degrees at 204 Hz. The device can provide a new direction for miniaturizing laser scanning based endoscopes or handheld projectors.</P>
Stents versus coronary-artery bypass grafting for left main coronary artery disease.
Seung, Ki Bae,Park, Duk-Woo,Kim, Young-Hak,Lee, Seung-Whan,Lee, Cheol Whan,Hong, Myeong-Ki,Park, Seong-Wook,Yun, Sung-Cheol,Gwon, Hyeon-Cheol,Jeong, Myung-Ho,Jang, Yangsoo,Kim, Hyo-Soo,Kim, Pum Joon,S Massachusetts Medical Society 2008 The New England journal of medicine Vol.358 No.17
<P>BACKGROUND: Several studies have compared the treatment effects of coronary stenting and coronary-artery bypass grafting (CABG). However, there are limited data regarding the long-term outcomes of these two interventions for patients with unprotected left main coronary artery disease. METHODS: We evaluated 1102 patients with unprotected left main coronary artery disease who underwent stent implantation and 1138 patients who underwent CABG in Korea between January 2000 and June 2006. We compared adverse outcomes (death; a composite outcome of death, Q-wave myocardial infarction, or stroke; and target-vessel revascularization) with the use of propensity-score matching in the overall cohort and in separate subgroups according to type of stent. RESULTS: In the overall matched cohort, there was no significant difference between the stenting and CABG groups in the risk of death (hazard ratio for the stenting group, 1.18; 95% confidence interval [CI], 0.77 to 1.80) or the risk of the composite outcome (hazard ratio for the stenting group, 1.10; 95% CI, 0.75 to 1.62). The rates of target-vessel revascularization were significantly higher in the group that received stents than in the group that underwent CABG (hazard ratio, 4.76; 95% CI, 2.80 to 8.11). Comparisons of the group that received bare-metal stents with the group that underwent CABG and of the group that received drug-eluting stents with the group that underwent CABG produced similar results, although there was a trend toward higher rates of death and the composite end point in the group that received drug-eluting stents. CONCLUSIONS: In a cohort of patients with unprotected left main coronary artery disease, we found no significant difference in rates of death or of the composite end point of death, Q-wave myocardial infarction, or stroke between patients receiving stents and those undergoing CABG. However, stenting, even with drug-eluting stents, was associated with higher rates of target-vessel revascularization than was CABG.</P>
디지털 제어 방식의 APC 기능을 갖는 1.25Gb/s 버스트-모드 광 송신기
기현철(Hyeon Cheol Ki) 대한전자공학회 2007 電子工學會論文誌-SD (Semiconductor and devices) Vol.44 No.12
본 논문에서는 Gb/s 동작과 같은 고속 동작에 적합한 새로운 버스트-모드 광 송신기 구조를 제시하였다. 이 구조로써 디지털적으로 제어되는APC 회로를 포함하는 EPON용 버스트-모드 광 송신기를 상용 0.8m BiCMOS 기술을 이용하여 제작하였다. 제작된 광 송신기는 1.25Gb/s에서 잘 동작했고 53.3㎰의 지터, 191㎰의 상승시간 및 258㎰의 하강시간을 갖는 양호한 아이패턴을 보였다. APC 기능의 특성을 파악하기 위해 외부 전압 VREF를 증가시키며 출력광의 전력을 측정했다. 광 전력은 0.293mW/V의 비율로 VREF에 선형적으로 비례하였다. In this paper, we proposed a new burst-mode optical transmitter structure which is suitable for high data rate operation such as Gb/s operation. With this structure we made a 1.25Gb/s burst-mode optical transmitter including a digitally controlled APC circuit for EPON systems using commercial 0.8m BiCMOS technology. It well functioned at 1.25Gb/s and showed good eye patterns with 53.3㎰ jitter, 191㎰ rise time and 258㎰ fall time. To characterize the APC function we measured optical output power as increasing external voltage VREF . The optical power is linearlyproportional to VREF at the rate of 0.293mW/V.
A new mid-late maturing rice variety「Subo」with a good grain quality and for direct seeding
Man-Kee Baek,Woon-Chul Shin,Jong-Cheol Ko,Bo-Kyeong Kim,Jeong-Kwon Nam,Ki-Yeong Kim,Mun-Sik Shin,Ki-Yong Ha,Hyeon-Su Park,Hyeon-Jung Kang,So-Hyun Baek,Young-Jun Mo,Jae-Kwon Ko,Woo-Jae Kim,Young-Bok Le 한국육종학회 2013 한국육종학회 심포지엄 Vol.2013 No.07
‘Subo’ is a new japonica rice variety developed by a cross breeding between HR21124-B-59 and HR19567-B-70-3 having a good Phenotype with a multi-resistance and high yield elite line. The new variety developed for direct seeding by the rice breeding team in Rice Breeding and Cultivation Research Division, Department of Rice and Winter Cereal Crop, NICS, RDA in 2012. The heading date of this variety is August 13 and earlier than that of check variety, Nampyeongbyeo, by two days. ‘Subo’ has 72cm of culm length and 104 spikelets per panicle in direct seeding cultivation. This variety showed resistance to bacterial leaf blight and rice stripe virus and have germinating ability in sumerged soil conditions. The milled rice of this variety exhibits translucent and very clear non-glutinous endosperm. ‘Subo’ has much better palatability of cooked rice than that of Nampyeongbyeo. The whole grain rate of milled rice are 86.9% and milled rice recovery of are 74.6%. The yield of ‘Subo’ in direct seeding cultivation is 5.55MT/ha in milled rice. ‘Subo’ could be adaptable to the southern part plain area of Pyeongtaek and southwestern in Korea.