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다중입출력 시스템에서 적응형 섭동을 이용한 기회적 프리코딩
남태환,안선회,이경천,Nam, Tae-Hwan,An, Sun-hoe,Lee, Kyungchun 한국정보통신학회 2019 한국정보통신학회논문지 Vol.23 No.12
본 논문에서는 MIMO (Multiple-Input Multiple Output, 다중입출력) 시스템을 위한 적응형 섭동을 이용한 기회적 프리코딩(Adaptive Perturbation-aided Opportunistic Precoding) 방식을 제안한다. 제안 프리코딩 방식에서는 MIMO 시스템을 위한 프리코딩 행렬을 생성할 때 랜덤한 섭동 뿐 아니라 사용자로부터 받은 전송률 정보에 의해 결정되는 적응적 변화값을 함께 이용한다. 이전 시간의 랜덤 섭동이 전송속도를 상승시켰을 경우 적응형 섭동을 이전 랜덤 섭동과 동일하게 하고, 그렇지 않을 경우 이전 랜덤한 섭동 값의 음의 값에 해당하는 값을 적용시킨다. 또한 전송 속도 최적화를 위해 스케줄링에서 현재 생성된 프리코딩 행렬 뿐 아니라 메모리에 저장된 최근 프리코딩 행렬 정보도 함께 이용한다. 모의실험 결과에서 기존 프리코딩 방식에 비해 제안한 섭동 기반 기회적 프리코딩 방식이 높은 전송속도를 얻으며, 특히 사용자의 수가 적은 환경에서 전송 속도 이득이 큰 것을 확인할 수 있다. In this paper, we propose an adaptive-perturbation-aided opportunistic precoding (APOP) scheme for multiple-input multiple-output (MIMO) systems. To update a precoding matrix in MIMO systems, the proposed algorithm produces a random perturbation in each time slot. Then the additional adaptive perturbation is also applied, which depends on the reports of achievable data-rates from users. If the prior random perturbation increased the data rate, the adaptive perturbation is set to be the same as the prior random perturbation, otherwise the negative value of the prior random perturbation is applied for adaptive perturbation. Furthermore, to enhance the achievable data rates, the information on the stored precoding matrices in the memory as well as the currently generated precoding matrix is used for scheduling. Simulation results show that compared to conventional opportunistic precoding schemes, higher data rates are achieved by the proposed APOP scheme, especially when there are a relatively small number of users.
칼만필터의 적응형모델 기법을 이용한 광역상수도 시스템의 수요예측 모델 개발
한태환,남의석 한국조명전기설비학회 2001 조명·전기설비학회논문지 Vol.15 No.2
본 논문에서는 광역상수도 시스템의 취·송수 설비의 최적운영계획에 필수적으로 요구되는 시간 단위 용수 수요량 예측을 위하여 칼만 필터에 의한 수요 예측 모델 구축 및 배수패턴 해석 기법을 제안하고, 기존 시스템의 실 데이터를 이용하여 시뮬레이션 수행 결과 제안된 기법의 유용성이 검증되었다. 광역상수도 시스템에서 취·송수 설비의 최적운영계획 수립을 위해서는 예측 시간 범위를 최소 하루 단위 이상으로 유지해야 한다. 따라서, 제안된 기법에서는 기존의 시간별 실적데이터의 시계열에 의한 예측을 이용하는 것이 아니라 모델로부터 예측된 일 수요량에 배수패턴을 곱하여 24시간의 시간별 용수 수요량을 예측한다. 일 수요량 예측을 위한 칼만 필터 모델은 입력변수의 통계적 분석에 의해 모델 구조 최적화가 효과적으로 구현되고 배수패턴은 데이터 Granulization에 의해 얻어진다. Kalman Filter model of demand for residental water and consumption pattern wore tested for their ability to explain the hourly residental demand for water in metro-politan distribution system. The daily residental demand can be obtained from Kalman Filter model which is optimized by statistical analysis of input variables. The hourly residental demand for water is calculated from the daily residental demand and consumption pattern. The consumption pattern which has 24 time rates is characterized by data granulization in accordance with season kind, weather and holiday. The proposed approach is applied to water distribution system of metropolitan areas in Korea and its effectiveness is checked.
여과매체용 (FeNiCr)_80P_20 비정질 합금의 자기적 특성과 내식성
林鐘完,南宮廷,金文哲,盧泰奐 대한금속재료학회 2002 대한금속·재료학회지 Vol.40 No.12
With the object of developing a ferromagnetic filtering media used in electromagnetic filtering process of iron & steel industries, addition effects of Cr and Ni on magnetic properties and corrosion resistance for Fe_80P_20 amorphous ribbon alloy have been investigated. In (FeCr)_80P_20 ternary alloys, the soft magnetic properties and corrosion resistance were largely enhanced upon Cr addition of about 5 at%, although considerable decrease in saturation magnetization occurred. However the corrosion rate was thought to be still high for practical use. If the Fe was substituted by some Ni to form a quarternary Fe-Ni-Cr-P alloys, decrease of the saturation magnetization was strongly suppressed. Moreover the soft magnetic properties and corrosion resistance were improved to a great extent as compared to Fe_75Cr_5P_20 amorphous alloy. For Fe_75Ni_5Cr_5P_20 amorphous alloy, the values of B_10, M_s and H_c were 6.9 kG, 110 emu/g and 0.24 Oe, respectively. The corrosion rate was measured to be very low(less than 0.2 ㎜/ yr) in 5 wt% HCl solution(room temperature) and 2 wt% NaOH solution(60℃). The good soft magnetic properties and corrosion resistance of Fe_75Ni_5Cr_5P_20 amorphous alloy were attributed to the decrease in saturation magnetostriction and more active formation of CrO_X(OH)_(3-2x)·nH_2O passive films by the combined addition of Ni and Cr.
조형곤,민경현,남태환,나승주,박재형,정세영 대한약학회 2008 Archives of Pharmacal Research Vol.31 No.7
New basal insulin formulation was designed and their structural characteristics were investigated in vitro and biological activities in type 1 diabetic rats. Zinc-crystallized insulin was physically loaded into hydrophobically modified glycol chitosan (HGC) nanoparticles by a dialysis method. The series of insulin-HGC formulations were prepared with different feed weight ratio of insulin to HGC from 0.5:1 to 4:1. The loading contents of insulin and size distribution of insulin-HGCs were characterized, and blood glucose responses were investigated in streptozotocin-induced diabetic rats after single subcutaneous injection of regular insulin and insulin-HGCs. The highest loading efficiency and content were obtained in insulin-HGC when a 1:1 feed weight ratio of insulin to HGC was employed. The hydrodynamic diameter of insulin-HGC nanoparticles were in the range of 200 to 500 nm with narrow size distribution. Insulin-HGC effectively sustained insulin release up to 40% within 12 hours followed by a slower controlled release. Insulin-HGC showed an extended blood glucose lowering effect up to 24 h and provided normal blood glucose levels after oral glucose (1.5 g/kg) load at 24 hours post-injection while regular insulin showed severe hypoglycemia. The prolonged time action profiles and low variability of insulin-HGC formulation resulted in improved blood glucose control in diabetic rats and fulfilled a pattern desirable of a basal insulin.