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비대칭 신호점에 의한 부호화된 16-QAM의 이동 무선 채널에서의 BER 성능 개선에 관한 연구
김태헌,하덕호 한국전자파학회 1997 한국전자파학회논문지 Vol.8 No.2
The purpose of this paper is to propose an improvement method of BER for coded 16QAM over Rayleigh fading channel. To overcome the BER degradation due to the fading under mobile communication, we apply trellis coded modulation technique which is efficient to get a coding gain without the expansion of bandwidth. Especially, to minimize the burst error which are the main factor of the BER degradation for mobile communication systems, we apply interleaving/deinterleaving method to the studying system. Also we apply asymmetric signal mapping methods to this TCM scheme. From the computer simulation, BER performance of asymmetric case has achieved about 1 dB improvement of about $10^{-4}$, compared to the traditional symmetric case.
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레일레이 페이딩 환경하에서 밀러부호화 기법에 의한 16-QAM 통신방식의 성능개선
김태헌,하덕호 한국전자파학회 1998 한국전자파학회논문지 Vol.9 No.3
The purpose of this paper is to propose an improvement method of BER for coded 16-QAM under Rayleigh fading channel. To overcome the BER degradation due to the fading under mobile communication, we apply delay modulation technique which is efficient to get both a coding gain and approximately one-half those needed by Manchester coding on bandwidth requirements. Especially, the delay modulation scheme is insensitive to the $180^{\circ}$phase ambiquity common to NRZ-L and Manchester coding schemes. From the computer simulation, BER performance of our scheme has achieved about 3.8 dB improvement of about $10^{-4}$, compared to Manchester coded 16-QAM.
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저출산수준과 강한 남아선호관이 사회에 미치는 영향 -성.연령별 인구 구조의 변화를 중심으로-
김태헌 한국인구학회 1993 한국인구학 Vol.16 No.2
Korea fertility level has dropped since the 1960's and speed of decline has accelerated in the 1980's. In the resuls, the growth rate reached to less then 1 percent in 1990 and will be $\ulcorner$0 $\lrcorner$ percent growth in 2021. The total population will increase to 50, 586 thousand persons in 2021 then will decrease. With the rapid fertility decline the age structure of Korean population has changed : while the proportion of child population aged 0-14 is decreasing sharply, that of old-age population aged 65 and over is increasing. Because of the recent increase of sex ratio at birth, the sex structure among the young generation has been destorted; the sex ratio at age 0-4 was as high as high as 112.0 in 1990. The effects of these population phenomena on Korean society are the followings: 1) Old age dependency ratio is increasing rapidly and continuously and will be about 40.0 from the 2050's. 2) Because of the rapid decline of the number of births, the absolute number of the major labour force at age 25-34 will decrease after around 2000 and then from the 2010's become less than that in 1990. 3) Since the large fertility defferentials by womens's educational level have continued and the relation between the educational levels of mothers and children are very strong, level has dropped among higher educated women first when the average fertility level has declined in Korea, the average educational level of the children is may be expected to be relatively low and then the future productivity is will be also low, which causes the decline of 'quality of population. 4) When the high sex ratio at birth (over 110 since 1986) continues, number of brides will be short by over 20 percent from the 2010s, which will bring various kinds of social prblems. Therefore, the counter measures in concrete to relieve the heavy problems are recommended as follows: 1) The extention of the birth intervals, which helps to drop the population growth rate at the same level of number of children per women. 2) The positive supports for out-migrants, which helps to reduce the population size without any destortion of age-sex structure. 3) The defferent supports of family planning for the higher and lower classes, which helps to reduce the gaps between different ferility levels of the classes and to keep and improve the quality of population. 4)population education for both students and adults, which helps to minimize the gap between the private and public requirements.
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디지틀 신호처리기의 효율적 설계를 위한 고수준 논리 합성
김태헌,정주흥,안치득,Kim, Tae-Heon,Jeong, Ju-Heung,An, Chi-Duk 한국전자통신연구원 1992 전자통신동향분석 Vol.7 No.3
본 고에서는 디지틀 신호 처리기의 효율적 설계를 위해 필수적으로 요구되는 고수준 논리 합성 문제를 다룬다. Behavioral representation으로부터 structural representation으로의 변환은 복잡도의 문제로 인해 제한적으로 연구되어 온 분야로서 최근 VHDL의 표준화에 따라 많은 연구가 요구되고 있다. 본 고에서는 기존의 제안된 방법을 중심으로 VHDL과의 관계 그리고 앞으로의 전망 등에 대해 논한다.
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만성 신부전증을 동반한 협심증 환자에서 심폐바이패스를 사용하지 않는 관상동맥우회술 -3예 보고-
김태헌,김기봉 대한흉부심장혈관외과학회 1999 Journal of Chest Surgery Vol.32 No.9
Since the first report of coronary artery bypass grafting (CABG) in patients with end-stage renal disease in 1974, numerous reports have documented the feasibility of CABG in patients with chronic renal diseases. Patients with chronic renal failure often have comorbid disorders such as hypertension, and diabetes mellitus, each with their own complications and associated impact on both short and long-term survivals. In addition, infection and sepsis have been identified as significant causes of morbidity and mortality in most series of patients with end-stage renal disease undergoing cardiac surgical procedure. As a result of these and other factors such as perioperative volume and electrolyte disturbances, patients with chronic renal failures are at an increased risk of complication and mortality after CABG. We report 3 cases of "Off-pump" CABG in the chronic renal failure patients. patients.
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