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고속 디지털 신호 전송선로에서의 Crosstalk 에 관한 연구
김세영,장상건,남상식,박항구,신연강 대한전자공학회 1994 전자공학회논문지-A Vol.31 No.8
The prediction of crosstalk in one of important problems in estimating the EMC of a system for high speed digital signal transmission. Crosstalk curves are shown in terms of characteristic impedance of lines spacing between lines and rise time of pulse by using general multiple coupled transmission line equation and harmonic-balance method. The coupled symmetrical two-line on dielectric material epoxy-glass FR 4(${\varepsilon}_r$), is fabricated to measure crosstalk occuring at the near end and far end of the passive line. The inter-line is inserted to reduce crosstalk between two microstrip lines. The simulation results and the measurement results are shown and found to be very close.
ROM 기반의 실시간 자바가상기계를 위한 메모리 할당기법
김세영,양희재 경성대학교 공학기술연구소 2004 공학기술연구지 Vol.11 No.-
On embedded real-time system with a single processor and no virtual memory, fixed-size memory allocation scheme is used to solve external memory fragmentation and predictability of the computation time problem. The scheme can be applied to embedded Java virtual machine with heap memory as in simpleRTJ for example. Fixed-size memory allocation scheme has an advantage that makes memory management system simple and reduces runtime overhead. We found, however, there are some problems in simpleRTJ adopting the scheme. Firstly it searches memory in linear fashion to find a free space which causes an unpredictable delay. This is a critical problem for real-time guarantee. Additionally, when array and string is allocated in the heap, it uses real size, not fixed-size. So fixed-size memory allocation scheme cannot take its advantage in this case. In this paper we have reconstructed the object, method frame and allocation scheme for the best use of the advantage of fixed-size memory allocation scheme.
自然科 學習資料의 開發 : 現代 科學敎育에의 接近을 爲한 資料 Materials to Approach for Modern Science Education
金世榮,崔守安,崔福源 부산교육대학교 과학교육연구소 1981 科學敎育硏究 Vol.6 No.-
This studies describes how to develop and avail learning materials to approach for modern science education. The materials consist of three parts biology, chemistry, and earth-science, in primary school science. Part of biology has been covered in detail "Growth of Plants" (2-1), "Life cycle of Plants" (3-1), "Environments and Plants" (4-1). Earth-Science's part covered a "Circulation of Atmosphare and Water" (5-1), and chemistrie's part provide fat in nourishment and digestion in "Human Body" (6-2) unit. This developed materials are inexpensive to keep and are convenient subjects for children's learning. They may study products of science, fumdamental principle for science and scientific thought.
직접 변환 수신기를 위한 Six Port에서의 I와 Q채널의 생성
김세영,김낙명,김영완,Kim Seayoung,Kim Nak-Myeong,Kim Young-Wan 대한전자공학회 2004 電子工學會論文誌-TC (Telecommunications) Vol.41 No.6
직접 변환 방식 수신기법은 SDR기반 미래 광대역 또는 다중 대역 무선통신 시스템을 위한 중요한 해의 하나로 인식되고 있다. 본 논문에서는 광대역의 대역폭을 가지면서도 시스템의 유연성을 극대화할 수 있도록 SDR기반 직접 변환 수신기에 적용가능한 I 및 Q 신호의 생성에 관하여 연구하였다. 먼저 실제의 SDR 기반 통신 환경을 고려한 직접 변환 SDR 시스템을 모델링하고, 수신기에서의 위상 오류의 영향을 분석하며 이에 따른 I/Q 채널의 준최적 재생 알고리즘을 제안하였다. 제안된 알고리즘은 실시간 early-late compensator 구조를 통하여 송신단과 수신단의 위상 오류를 실시간으로 보정하고 랜덤한 채널 잡음환경에서도 보다 안정된 성능을 유지하게 한다. 컴퓨터 시뮬레이션을 통하여, $45{\~}55$도의 랜덤 위상 오류가 난 경우, 제안된 시스템은 기존 시스템과 비교하여 약 4dB이상의 성능 개선이 있음을 확인하였다. The development of direct receiver techniques is expected to be a solution for future wideband or multi-band wireless systems based on software defined radio. In this Paper, we study the regeneration of I and Q signals for the SDR based direct conversion receiver, so that we can handle a wide bandwidth and maintain maximal flexibility in system utilization. After modeling the basic system considering the real wireless communication environment, and studying the impact of imperfect phase imbalance on the performance of a direct conversion receiver, we propose a suboptimal I and Q signal regeneration algorithm for the system. The proposed algerian regenerates I and Q signals using a real time early-late compensator which effectively estimates phase imbalances and gives feedback in a directreceiver. The proposed algorithm is shown to mitigate the impact of AWGN and improves performance especially at low SNR channel condition. According to the computer simulation, the BER performance of the proposed system is at least about 4 dB better than conventional systems under $45{\~}55$ degrees random phase errors.
金世榮,卞斗源 건국대학교 1987 論文集 Vol.25 No.1
The vegetation along the Hongchon riverside was surveyed over four times from May to June 1984 and May 1986. The results obtained are as follows ; Vascular plants of this area consisted of 55 varieties, 350 species, 248 genera and 78 families (herbs 281 sp, tree 124 sp.). Aquatic plants was 6 species, 5 families. The vegetations of riverside showed Phragmites commuins, Cyperaceae, Salix fracilistyla and Artemisia princeps var. orientalis communities, but Perisicaria nodosa not exits. The gravel and sand of riverside composed of communities likes Pursatila chinensis, Chilidonium major, Oenothera odorata, Equistum arvense and Alopecurus amurensis. The bank, meadow and farm land along riverside skewed chiefly Spiraea prumifolia, Rosa multiflora, Celastrus orbiculatus, Agrimonia pilosa, Hunulus japonicus, Trifolium repens, securineca suffruticosa, Ixeris dentate, Miscanthus sinensis, Arundinlela hirta and Digitalia sanguinalis. On the watered ground plot of riverside observed Quercus dentate, Pinus densiflora mixed forest and afforested Abies hollophylla. The distribution of vegetation is paralleled with the bank and rivers stream. The height of ground have in fenced on the vegetational components. The average degree of green naturality in the investigated area was 6.93 and so the vegetation of these area was well preserved.