신경망을 이용한 서명 인식

李相範,姜成德,徐泳圭 단국대학교 1992 論文集 Vol.26 No.-

Recently, many algorithms for the image pattern recognition using the neural network have been proposed. In this paper, the characteristic parameters of signature pattern can be extracted by using discrete consine transform. The neural network is implemented with back propagation, generalized delta rule which is able to learn multi-layer perceptron among the various model and it is applied to the signature verification system as pattern classifier. Through the experimentation, the input of signature pattern which has N=16, is transformed with 2-dimension discrete cosine transform, and the characteristic parameters is applied to 3-layer perceptron neural network model. The experimental result shows the signature verification could be possible to verify them and the applied algorithms of neural network model could be applied to the signature verification.

인덕터 피킹에 의한 광대역 증폭기의 균일이득 특성분석에 관한 연구

강경일,한경희,이영철 慶南大學校 附設 工業技術硏究所 1993 硏究論文集 Vol.11 No.-

정보통신의 대용량 전송과 고속처리 능력의 요구에 따라, 균일이득을 갖는 광대역증폭기를 설계할 필요가 있다. 본 논문에서는 주파수대역(0.1~1㎓)에서 최대 균일이득을 갖는 광대역 증폭기를 설계 하고자, 쌍극자 트랜지스터의 고주파 등가회로에서 캐패시턴스의 영향을 감소시키고 주파수대역을 확장시키는 인덕터 피킹회로를 부가시켰으며, 컴퓨터 시뮬레이션에 의하여 인덕터 피킹효과를 분석하였다. 그 결과 귀환저항과 귀환인덕터를 갖는 증폭모듈이 최대균일 이득을 갖으며, 100-1000㎒에서 약 1.6㏈의 이득오차임을 알 수 있었다. According to the demands of the large capacity and high speed processing in communication system, it is very necessary to design the flat gain wide-band amplifier. In this papers, to design the wide-band amplifier with flat gain over the frequency band(0.1-1.0㎓), we analysis the effects of capacitance on BJT high-frequency equivalent circuit. We insert the inductor peaking element to the amplifier to decrease the effects of capacitance and to expand the frequency range. And we analyzed the various inductor peaking effects by computer simulation. As a result, feedback inductor with resistor shows the maximum flat gain and about 1.6dB gain variation at 0.1-1.0㎓.

Aspergillus nidulans로부터 분획한 Protoplasts의 Reversion에 관하여

姜明奎,梁永基,李榮河 충남대학교 자연과학연구소 1984 忠南科學硏究誌 Vol.11 No.2

The processes of reversion of Aspergillus nidulans protoplasts fractionated at varing digestion periods have been investigated. The early-produced protoplasts showed higher enzyme (CMCase and β-glucosidase) activities and protein contents than the late-produced protoplasts. Similar tendencies were also observed in the reversion frequencies of the fractionated protoplasts. The reversion frequency of protoplasts isolated with 1hr-digestion was approximately 90 times higher than that of protoplasts isolated with 6hr-digestion. In liquid medium stabilized osmotically with 0.6M (NH_4)_2SO_4, two major reversion patterns of protoplasts were found. In the first, normal hyphae were directly formed from protoplasts. In the second, chains of yeast-like budding cells were produced from protoplasts and eventually normal hyphae were developed from the terminal cell of budding chain or the opposite side of the protoplasts. The proportion ratio of direct formation of normal hyphae to yeast-like forms during the processes of reversion was greatest in protoplasts isolated with 1hr-digestion and decreased in proportion to increasing digestion periods. It is suggested that the processes of reversions of A. nidulans protoplasts are related to the activities of physiological metabolism of heterogeneous protoplasts originated in highly differentiated parent mycelium.

전력증폭기의 혼변조왜곡 개선에 관한 연구

강경일,이영철,김영진 慶南大學校 附設 工業技術硏究所 1994 硏究論文集 Vol.12 No.-

본 논문에서는 전력증폭기의 제3차 혼변조특성을 개선하기 위하여 전방귀환방식의 선형화 과정에 대하여 논의하였다. 혼변조특성을 Volterra함수에 의하여 분석하였으며, 850∼890MHz의 주파수 범위에서 설계된 전방 귀환 전력증폭기의 혼변조마진은 최대 -54dBc로서 양호한 특성을 얻을 수 있었다. In this Papers, we studied the Feedforward linear Power Amplifier to improve the third order intermodulation distortion (IMD3) of Power Amplifier. Intermodulation distortion was analyzed by Volterra function, and we designed Feedforward Power Amplifier and it shows good intermodulation margin about -54dBc in 850 ∼890 MHz.

고속 디지틀 정보용 광 수신 증폭기 설계

강경일,이영철 慶南大學校 附設 工業技術硏究所 1992 硏究論文集 Vol.10 No.-

정보 전송양의 증가에 의하여 Giga bps급의 고속 광통신시스템의 발전이 가속되고 있으므로 본 논문에서는 InGaAs PIN 포토다이오드와 GaAs MESFET에 의한 고속 광 수신 전치증폭기를 설계하였다. 설계된 전치증폭기의 주파수 대역폭은 950㎒, 이득은 중간대역에서 51.5㏈ 감도는 ??에서 -27.7㏈m 을 보였다. SPICE에 의하여 분석한 이론값과 설계한 증폭기의 주파수 응답특성이 일치함을 알 수 있었다. The increasing demand for transmission system has accelerated the development of Giga bps optical communication systems. In this paper, high speed optical preamplifier with InGaAs PIN-photodiode and GaAs MESFET is designed. The measured result of the designed preamplifier shows a 950㎒ bandwidth, 51.5㏈ at mid frequency and -27.7㏈m at ??. Theoretical prediction which is analyzed by SPICE agree well with the frequency response of designed preamplifier.

비선형 파라메터를 이용한 마이크로파 발진기 위상 잡음 해석에 관한 연구

강진래,이영철 경남대학교 공업기술연구소 2001 硏究論文集 Vol.19 No.-

본 논문은 HEMT의 비선형 등가소자에 의한 마이크로파 발진기의 위상잡음에 미치는 영향에 대해서 분석하였다. 능동소자의 비선형 등가회로에서 비선형 커패시턴스 Cgs, Cgd를 중심으로 발진기의 위상잡음에 미치는 영향을 최적화 시켰으며, 마이크로파 발진기가 저 위상잡음을 가지도록 병렬귀환의 유전체 공진발진기를 설계하고 마이크로파 샘플링 위상 검파를 이용한 고안정 위상동기 발진기를 설계하여 분석한 결과, 실제 제작하여 측정된 위상잡음은 -80.33dBc@10KHz 및 -95dBc@100KHz으로 이론값과 실험 값이 매우 근접함을 알 수 있었다. With the nonlinear equivalent circuits of microwave HEMT, we analyzed the most affected nonlinear elements to the phase noise of microwave oscillator are capacitance between gaffe to source and gate to drain. the nonlinear elements of capacitances of Cgs and Cgd, have been optimized to reduce the phase noise of microwave oscillator by analysing of scattering parameters of device. The designed microwave oscillator, Dielectric-resonant microwave oscillator of high quality and low phase noise, is phase locked loop adapted the microwave sampling phased locked oscillator and shows a good agreement to the measured phase noise of -80.33dBc and -9565c offset frequency of 10KHz and 100KHz at 13.25GHz respectively.

신장질환이 동반된 고혈압 환자에서 칼승길항제 Felodipine의 효과

신영태,정민수,이순구,김성숙,이강욱 大韓臨床藥理學會 1993 臨床藥理學會誌 Vol.1 No.1

유기용제 중독에 의한 중추신경장애 1예

강성규,이경용,정호근,이영진 大韓産業醫學會 1992 대한직업환경의학회지 Vol.4 No.1

We report a case of demyelinating lesion in central nervous system in a 38-year-old female patient who suffered from muscle weakness and disability of standing by herself. She worked for 10 hours in a day at the small footwear factory about 1 year in 1990. Physical examinations showed normal except increased DTRs in the elbows and knees. Clinical laboratory findings were within normal limits. Brain CT and EMC findings were normal. But, brain MRI showed small multiple high signal intensity area on T2 weighted image in right frontal white matter, right fronto-parietal periventricular white matter with localized atrophy in genu and rostrum of corpus callosum. There were no ventilation system in the factory. By the evaluation of work environment 1½ months later, high concentration of toluene, MEK, n-hexane, MIBK, acetone and cyclohexane were detected. We suppose her demyelinating lesion was caused by toluene alone or mixed solvents with toluene and others.

活性汚泥 微生物의 分離 및 同定

강명규,배정옥,이기종,이영하 忠南大學校環境問題硏究所 1993 環境硏究 Vol.11 No.-

To investigate the microfloral composition in activated sludge, more than six hundred bacterial and fungal strains isolated from influent sewage, return sludge and aeration tank of an activated sludge sewage treatment plant were identified to the genus level. During the holding period in the aeration tank development of diverse heterotrophic microbial populations occurred and bacterial and fungal numbers in the aeration tank were 10- to 100-fold higher than in the influent sewage and return sludge. A large number of Gram-negative rods, particularly Pseudomonas, Flavobacterium, Enterobacter, Klebsiella, and Alcaligenes were found to be the dominant genera in the aeration tank. The species of filamentous fungi Trichoderma, Aspergillus, Rhizopus and Lepiomitus, and various yeasts were frequently associated with activated sludge. The most commonly found yeast genera were Candida, Geotrichum, Saccharomyces, Torulopsis and Rhodotorula.

촉매 코팅방법에 따른 기능성 여과포의 NO 제거 반응 특성

강민필,송윤섭,이효송,김상도,박영옥,황택성,이영우 한국화학공학회 2002 Korean Chemical Engineering Research(HWAHAK KONGHA Vol.40 No.6

NO_x와 먼지 동시 제거용 기능성 여과포 개발의 일환으로 V_2O_5/TiO_2계열의 상용촉매를 사용하여 P-84, Nomex, PTFE 여과포에 코팅하였다. 사용된 코팅 방법은 Sol-gel법, Spray법 그리고 Dip코팅 방법이었으며 코팅방법이 여과포의 NO_x 제거반응에 미치는 영향을 조사하였다. NO_x 제거반응실험은 여과포의 작동온도에 맞는 100-250℃의 반응온도범위에서, 공간속도 5,000hr^-1, 산소농도 6%, NH_3/NO 몰비는 1.0의 조건하에서 수행되었다. 본 연구에서 시도된 세 가지 코팅 방법 중 촉매량의 조절 및 균일한 코팅이 용이한 Sol-gel법에 의해 제조된 기능성여과포가 가장 좋은 NO_x 전환율을 나타냈다. A series of fabric filters including P-84, Nomex and PTFE were coated with a commercial V_2O_5/TiO_2 catalyst as an effort to develop a functional fabric filter of simultaneous removal of dust and NO_x. The coating methods employed are solgel coating method, spray coating method and dip coating method, and the effects of coating method on NO_x removal performance of functional fabric filter were investigated. Experimental conditions are as follows: the temperatures of 100-250℃ which are the normal operating temperature range of fabric filters, the space velocity of 5,000hr^-1, the oxygen concentration of 6%, and the NH_3/NO ratio of 1.0. Results showed that the sol-gel coating method gave the best NO_x removal performance mainly due to its ability in controlling the amount of catalyst and uniform coating.