FADAC-OFDM: Frequency-Asynchronous Distributed Alamouti-Coded OFDM

Bong-seok Kim,Kwonhue Choi IEEE 2015 IEEE Transactions on Vehicular Technology VT Vol.64 No.2

<P>We propose frequency-asynchronous distributed Alamouti-coded orthogonal frequency-division multiplexing (FADAC-OFDM). The proposed scheme effectively mitigates the intercarrier interference (ICI) due to frequency offset (FO) between two distributed antennas. The transmitter side of the proposed scheme transmits each of the two subslots in Alamouti code through two remote subcarriers symmetric to the center frequency and is referred to as space-frequency reversal schemes by Wang et al. or Choi. The receiver side of the proposed scheme is significantly different from the conventional scheme or the scheme proposed by Wang et al. in that it performs two discrete Fourier transform (DFT), each of which is synchronized to each transmit antenna's carrier frequency. The decision variables are generated by performing a simple linear combining with the same complexity as that of the conventional Alamouti code. The derivation shows that in flat-fading channels, the dominant ICI components due to FO cancel each other during the combining process. The proposed scheme achieves almost the same performance as the ideal Alamouti scheme, even with large FO. To use this ICI self-cancellation property for selective fading channels or in cases with timing offset (TO) between two transmit antennas, the total subcarriers are divided into several subblocks, and the proposed scheme is applied to each subblock. For mildly selective channels or cases with practically small TO, the proposed scheme achieves significantly improved performance compared with the conventional space-frequency Alamouti-coded OFDM.</P>

안정된 광 솔리톤 전송영역에 대한 연구

최봉수,이명우,서동선,김석진 明知大學校 産業技術硏究所 1995 産業技術硏究所論文集 Vol.14 No.-

We numerically investigate stable propagation regimes of 10 ㎓ train of optical solitons with 17.6 ps widths to determine the acceptable variations of periodic amplifier gain(△G), dispersion(△D), and initial chirp(C), as a function of the amplification period LP. We fine that, when LP = 25 km, the acceptable variations are △G = ±4%, △D= ±12%, and C= -0.36 ∼ 0.39. The variations decrease as the amplification period LP increases.

태권도 우수선수들의 정신력 특성

최상진,조옥성,백우석,이갑철,고봉수 한국스포츠리서치 2004 한국 스포츠 리서치 Vol.15 No.2

The purpose of this study was to investigate the mental toughness of Taekwondo players and to suggest way of performance enhancement using Loehr's Psychological Performance Inventory. Subjects were 188 Taekwondo elite players. Each factor's mean and standard deviation of Mental Toughness were calculated, and ANOVA were used for statistical analyses of the difference of mean. The results are as follow;: 1. On the level of self-confidence, it shows that the man players is higher than the woman players (school career F=5.846, P<.05: sex distinction F=8.876, P<.01). 2. On the level of attention control, it shows that the woman players is higher than the man players (school career F=4.483, P<.05: sex distinction F=9.814, P<.01). 3. On the level of visual and imagery control, it shows that the man players is higher than the woman players (school career F=7.790, P<.01: sex distinction F=5.000. P<.05). 4. On the level of arousal control, motivation, positive energy and attitude control, it was not significant difference according to the sexual and school career.

공작기계 주축계의 오일에어윤활특성에 관한 연구

김석일,최대봉 한국항공대학 항공문제연구소 1992 航空問題硏究所 硏究誌 Vol.2 No.-

최근 오일에어윤활방법은 고속용 구름베어링에 대한 효과적인 윤활방법의 하나로서 많은 주목을 받고 있다. 본 연구에서는 공작기계의 생산성과 가공정밀도를 향상시키기 위한 노력의 일환으로 오일에어윤활방법에 기초를 둔 공작기계용 고속주축계를 개발하였다. 그리고 개발된 고속주축계의 성능을 평가하기 위한 일련의 윤활실험을 수행하였다. 특히 공작기계 주축계의 고속화에서 고려해야 할 윤활조건과 구조설계조건을 도출하기 위해서 공급유량, 주축회전수, 그리고 주축계의 구조가 베어링의 온도상승, 베어링의 온도분포, 그리고 주축계의 마찰토오크에 미치는 영향을 고찰하였다. Recently the oil-air lubrication method has attracted special interest as one of the effective lubrication methods for a high-speed rolling bearing. In this study, the high speed spindle system of machine tools based on the oil-air lubrication method is developed to reduce the machining time and to improve the machining accuracy. And a lubrication experiment for evaluating the performance of the developed spindle system is carried out. Especially, in order to establish the lubrication and structural design conditions related to the development of a high-speed spindle system, the effects of oil supply rate, rotational spindle speed and spindle system structure on the bearing temperature rise, bearing temperature distribution and frictional torque are investigated.

금붕어, Carassius auratus의 성 성숙에 따른 Connexin 43 mRNA 발현량의 변화

최철영,김봉석 한국어병학회 2003 한국어병학회지 Vol.16 No.2

Connexin(Cx) is an important and essential protein in induction of oocyte maturation, which is present in almost all mammalian tissues except circulating blood cells and adult skeletal muscles. In this study, goldfish Cx43 cDNA sequence is available in GenBank under the accession number B078505. Homology analyses using the GenBank and EMBL general database searches indicated that goldfish Cx43 cDNA has a high homology iwth carp Cx43(95.1% identity), zebrafish Cx43(90.5% identity), and chicken Cx43(81.9% identity). Goldfish Cx43 is similar to the Cx family in its general features, and all the typical Cx consensus sequences are also foud. Moreover, significantly increased Cx43 transcripts were observed in mature goldfish(GSI; 18.3∼21.7) pituitary and ovary when compared with immature goldfish(GSI; 4.9∼6.0). Cx43 transcripts were weakly detected in both liver and kidney of immature and mature goldfish. There is possible that Cx43 activity was relation to oocyte maturation in the goldfish.

유한요소법을 이용한 수직형 롤러 분쇄기용 테이블 라이너의 내구 해석에 관한 연구

최형모,이경영,조석수,이선봉 三陟大學校 産業科學技術硏究所 2002 産業科學技術硏究論文集 Vol.7 No.1

Vertical roller mill, which perform the grinding and parting blending of raw material, is the one of the important machine to produce ordinary portland cement. The table liner belonged to the vertical roller is mill the one of the main parts influencing its grinding efficiency. The life of table liner is estimatede to 4×107cycles in the design stage, but at the field, when its operating time reaches to 4×106 ~ 8×106 cycles, the fracture of table liner being to be found. The fracture of table liner commences from the outside edge of grinding path contacting with the grinding roller. Its maintenance normally take 30% of the total maintenance costs of the roller mill. Therefore, this study shows the clarification of the reasons occuring the fatal destruction of the table liner by fatigue fracture analysis utilizing fracture mechanics and by FEM using ANSYS 5.6.

사후분해 시체에 대한 법의학적 접근

최영식,이상용,김유훈,조갑래,이봉우,양경무,정낙은,서중석,이한영,이원태,강현욱 大韓法醫學會 2000 대한법의학회지 Vol.24 No.2

Disposal of a homicide victim by dismemberment is rare, but individual cases are on record in most major medicolegal departments. Recognition of postmortem mutilation may be of importance in the interpretation of certain murders committed by sexual perverts and other mentally deranged individuals and sometimes performed for the sole reason of easier disposal of the body. Postmortem dismemberment is usually readily recognizable as such; The edges of the injuries are dry and lack evidence of bleeding. The joints may be disarticulated without fracture, or the use of an axe or saw may be evident from examination of bones. Parallel horizontal or oblique furrows in the bone surface are caused by skipping of the saw prior to establishing depth. Such patterns on the bone may assist in identifying the particular saw involved. So we report 25 dismembered corpses that autopsied in National Institute of Scientific Investigation. This paper can help in attempting to establish not only the first criminal investigation steps but also the medicolegal approach methods in unidentified and dismembered deaths.

후하소뇌동맥 동맥류에 의해 유발된 안면경련

최석근,이봉암,고준석,임영진,김국기,김태성 경희대학교 2004 慶熙醫學 Vol.20 No.1

가시오가피의 부위별 물 추출물이 흰쥐의 혈관이완반응에 미치는 영향

姜奉錫,金亨煥,安德均,崔湖榮 대한본초학회 2001 大韓本草學會誌 Vol.16 No.2

In this study we have examined the actions of water extract of Eleutherococus senticosus (Rupr. et Maxim.) Maxim. (ESH), Stem, Root bark (RB) and Root xylem (RX) in isolated thoracic and abdominal aorta assay. To compare the vasodilation effect, put. ESH, Stem, RB and RX into them which vessels were precontracted by 5-hydroxytryptamine (5-HT). We found out the thoracic aorta segments were responded to ESH with a dose-dependent vasodilation. The 5-HT induced contraction at 10-4M were relaxed after addition of the 2.0 ㎎/㎖ ESH as 32.1% (Stem), 34.9% (RX) and 87.2% (RB). The 5-HT induced vasocontraction at 10^-4M were vasodilated such as 87.2% in thoracic aorta and 89.0% in abdominal aorta with 2.0㎎/㎖ ESH. Addition of 2.0㎎/㎖ ESH in thoracic aorta which was precontracted by the 5-HT at 10-4M were come out differently 0% (water fraction), 53.8% (butanol fraction) and 96.6% (ethyl acetate fraction). The 5-HT induced contraction at 10-4M with and without endothelium were inhibited by 87.2% and 87.8% after addition of the ESH (2.0 ㎎/㎖). In conclusion, ESH-induced relaxation in the isolated rat thoracic aorta and abdominal aorta were come out be dose-dependent relaxation, and ESH's ethyl acetate fraction was showed the potent vasodilation effect.

건강질단 질병 유소견자들의 순천향구미병원 외래이용에 영향을 미치는 요인

김진석,우극현,함정오,유재영,최태성,하봉구,윤성용 순천향의학연구소 2002 Journal of Soonchunhyang Medical Science Vol.8 No.1

Background ; The purpose of routine health screening of employee is not only to detect worker's disease at early stage but also to provide early appropriate health service. But, majority of patients who diagnosed by routine health screening haven't underwent health service utilization. Soonchunhyang Kumi Hospital had been provide total occupational health service in kumi industrial estate including health screening, worker interview at workplace by occupational nurses and doctors. Object ; We want to know how much proportion of patient who are diagnosed by routine health screening had visited Soonchunhyang Kumi hospital out-patient clinic and factors influencing such health care service utilization. Method ; Initial study subject were 189 workers who had proved to have hypertension, diabetes mellitus, hyperlipidemia in routine health screening which performed during year of 2000. Among those, 160 workers who had finished questionnaire were selected for final study subject. We investigate whether they had visited health services or not, if they had, what kind of health care facility they visited, and other factors which influencing their health service utilization. Result ; Among 160 workers, 59(36.9%) had visited Soonchunhyang Kumi hospital, 47(29.4%) had visited other health care facility, and 54(33.8%) had not went to any health care facility. Factors which influencing Soonchunhyang Kumi hospital utilization is sex, job, staff's support to hospital visit during worktime, history of medical consultation about health screening result.