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초음파 영상 장치에서 직교 쳐프 신호를 이용한 동시 다중 송신집속 기법
정영관,송태경 대한의용생체공학회 2002 의공학회지 Vol.23 No.1
Receive dynamic focusing with an array transducer can provide near optimum resolution only in the vicinity of transmit focal depth. A customary method to increase the depth of field is to combine several beams with different focal depths, with an accompanying decrease in the frame rate. In this Paper. we Present a simultaneous multiple transmit focusing method in which chirp signals focused at different depths are transmitted at the same time. These chirp signals are mutually orthogonal in a sense that the autocorrelation function of each signal has a narrow mainlobe width and low sidelobe levels. and the crossorelation function of any Pair of the signals has values smaller than the sidelobe levels of each autocorrelation function. This means that each chirp signal can be separated from the combined received signals and compressed into a short pulse. which is then individually focused on a separate receive beamformer. Next. the individually focused beams are combined to form a frame of image. Theoretically, any two chirp signals defined over two nonoverlapped frequency bands are mutually orthogonal In the present work. however, a tractional overlap of adjacent frequency bands is permitted to design more chirp signals within a given transducer bandwidth. The elevation of the rosscorrelation values due to the frequency overlap could be reduced by alternating the direction of frequency sweep of the adjacent chirp signals We also observe that the Proposed method provides better images when the low frequency chirp is focused at a near Point and the high frequency chirp at a far point along the depth. better lateral resolution is obtained at the far field with reasonable SNR due to the SNR gain in Pulse compression Imaging .
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벤처기업 지정제도의 문제점과 개성방안 - 중부권의 벤처기업 설문조사를 중심으로 -
정영관,권오인 한국기업경영학회 2000 기업경영연구 Vol.7 No.2
This study investigates the existing rules to authorize the venture business and actual conditions of them. The questionnaire about authority of venture business was done in Daejon and chungchong province. We focused on One hundred and fourteen firm`s result of one hundred and twenty. These questionnaires consist of these - 8 general things, 2 respondents` characteristic, 5 venture business, 5 conditions of investment business, 5 patent rights. This paper was taken as a questionnaire research, getting information directly. Analyzing the answers, some points of issue and reform measures were presented. 1. We can find complexity and inconvenience in authorizing venture business. Therefore authority system must be simple and useless paper less. 2. To authorize the venture business, it must be invested by venture capital just after foundation in seven years. but this term must be longer to ten. 3. Except for old stocks, just new ones was accepted to work out the rate of investment. But in the rate of venture capital, accepting old stocks will be considered. 4. In proportion to total circulation income, research and development price make it stay in 5 percent of it. 5. Research and Development price was approved only through attached enterprise research institute. the other ways will be taken. 6. In estimated standard, profit, growth, safety and productivity will be considered in addition to total circulation price. 7. After valuation of venture business, the problems can be solved by instruction of technology and management.
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麻鎬燮,孫英模,金義庚,鄭永觀 慶尙大學校 1990 論文集 Vol.29 No.1
This study was carried out to estimate and evaluate the public function of forest resoruces, such as soil runoff control, landslide control, head-wsater conservation. purification of air (O? production and CO? purification ), sanitary andoutdoor recreation andwildlife protection for the forest land of 6.500.000 ha in Korea. The results obtaiend were as follows; 1 The function of soil runoff control was estimated to b e1.970million m?.its monetary value was appraised at 3.814.5 billion wons. 2.The function of landslide control was estimated to be 37.876 thousand m?its monetary value was appraised at 73.3 billion wons. 3. The function of head-water conservation was estimated to be 25.507million tons, its monetary value was appraised at 3.571.0 billion wons. 4.The production fo O? in the forest land was estimated to be 78.600 thousand tons,its monetary value was appraised at 3.930.0billion wons. 5.The volume of CO? absorbed in the forest land was estimated to be 94.320 thousand tons,its monetary value appraised at 2.204.3 billion wons. 6.The monetary value of outdoor recreation was appraised at 1.162.5 billion wons. 7.The phytoncide emmited in the forest land was estimated to be 1.954 thousand tons,the function of forest bath using phytoncide was appraised at 1.953.9 billion wons. 8.The monetary value of the functions of wildife protection, control of harmful insect control of tree growth and loss control of timber qality was appraised at 327 1 billion wons. In conclusion, the value of public functions of forest is more 23 times than that of the econmic function. production value of forest products, and comes to 14% of GNP. And also, the function of air purification.and and soil conservation has value than those of others. Particulary, it takes a more great deal of effort achiving the various works such as erosion control, establishment of recreation forest. management of reserved natural forest and afforestation of street tree for increasing of public functions.
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