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대용량 텍스트 데이터베이스를 위한 효율적인 2단계 합성 요약 화일 방법
유재수(Yoo Jae Soo),강형일(Kang Hyung Il) 한국정보처리학회 1997 정보처리학회논문지 Vol.4 No.4
In this paper, we propose a two-level hybrid signature file method(THM) to efficiently deal with large text database that use a term discrimination concept. In addition, we apply Yoo's clustering scheme to the two-level hybrid signature file method. The clustering scheme groups similar signatures together according to the similarity of the highly discriminatory terms so that we may achieve better performance on retrieval. The space-time analytical model of the proposed two-level hybrid method is provided. Based on the analytical model and experiments, we compare it with the existing methods, i.e., the bit-sliced method(BM), the two-level method(TM), and the hybrid method(HM). As a result, we show that THM achieves the best retrieval performance in a large database with 100,000 records when the number of matching records is less than 160.
알카리성 부여제 도포에 의한 중성화된 콘크리트의 알카리성 회복성능에 관한 실험적 연구
김무한,권영진,강석표,유재강,이강우 충남대학교 산업기술연구소 2000 산업기술연구논문집 Vol.15 No.1
Concrete is the most commonly used material in construction field and it is the permanent construction material with respect to civil property. But, if concrete loses its alkalinity by CO2 gas, it loses its structural characteristics and results in total collapse in construction field. Therefore. it is needed to be studied the alkali-recovery performance by alkalization agent on carbonated concrete by accelerated carbonation test. In this paper, we investigate recovery performance by impregnating alkalization agent in carbonated concrete, then we evaluate alkali maintenance performance by pH survey in each kinds of finishing materials. The results of this paper can be summarized as follows. 1)Carbonated concrete under pH 10 was recovered its alkalinity to pH 11 at first stage by spreading alkalization agent on its outer surface. 2)After spreading alkalization agent, there is a difference due to types of moreover effect of anti-rust paint and ordinary cement paste were excellent.
柳康熙 충주대 산업과학기술연구소 1999 産業科學論文集 Vol.7 No.1
This paper presents frequency difference detector method which can be used in frequency locking the wavelength of a local VCO laser diode to the reference wavelength fed from OFDM network. The basic structure of the proposed frequency difference detector is based on the master-slave configuration. The optical signals from the reference master laser source and local slave VCO laser are heterodyned on a photo detector, resulting in the microwave output signal corresponding to the difference frequency between two input optical signals. The output electrical difference signal is then compared to the microwave reference frequency through the mixer and OP amplifier as a frequency difference detector. The final difference signal output is filtered and integrated by the integrating loop filter for the frequency locking, and it is delivered to the current source of local VCO laser diode causing its output wavelength change corresponding to the input difference signal. Through experiments with the calculated parameters, we confirmed that the frequency difference detector simply develops an error component that is proportional to the frequency difference between heterodyned optical signals and a reference 1.5GHz microwave oscillator. The achieved locking range of the VCO laser diode is around ± 200 MHz.
광 부호분할 다중접속 가입자 전송망에서의 잡음영향 연구
유강희 忠州大學校 2007 한국교통대학교 논문집 Vol.42 No.-
Noise characteristics of the frequency domain optical CDMA system has been analyzed for the system performance. It is found that the excess intensity noise is the important factor in case of the high power optical input signal at the receiver. As a result, the suppression of the excess intensity noise is very important to design the stable frequency domain optical CDMA system compare to the suppression of the other noises such as thermal() noise, shot() noise and spontaneous emission beat() noise. This paper describes the calculated result of the noise analysis.
유강희 한국교통대학교 2017 한국교통대학교 논문집 Vol.52 No.-
In last few years, the increasing use of LEDs in illumination system make the emergence of Visible Light Communication(VLC), in which wireless data communication is performed by transmitting through the visible band of light. In this paper, wireless communication system using LED’s for car-tocar communication is introduced and the transmission performance are analyzed for the link. In particular, horizontal seperation between two cars and reflection from the neighbor car make the transmission performance degradation. The delay time between line of sight signal and reflected signal caused inter-symbol interference. Performance analysis such as noise of optical receivers, signal to noise ratio, inter-symbol inteference and maximum transmission speed due to horizontal seperation as well as reflection are calculated. This paper described the details of the simulation results.
평행 결합 λ/4 마이크로 스트립 선로를 이용한 2.488 ㎓ 대역통과 여파기의 설계 및 제작
柳康熙 충주대 2001 한국교통대학교 논문집 Vol.36 No.2
This paper describes the realization details of the 2.488GHz bandpass filler using parallel coupled λ/4 microstrip lines. A bandpass filter using parallel coupled microstrip lines is analyzed in terms of admittance inverter in equivalent circuit as well as even/odd mode characteristic impedances. The designed bandwidth of 10% at the center frequency of 2.488GHz is realized by using super-compact CAD optimization. Measured results of the fabricated bandpass filter is in good agreement with the simulation data, but the measured attenuation is slightly higher than those of the designed value.
유강희 韓國交通大學校 2013 한국교통대학교 논문집 Vol.48 No.-
This paper describes the procedure to get full mesh connectivity in WDM ring networks. The number of wavelengths as well as maximum hop numbers are calculated for both odd and even number of nodes on the ring to get full mesh connectivity. Using matrix approach, optimal wavelength assignment algorithm for the full mesh connectivity is presented. Additional work presented is the performance comparison among several types of WDM ring networks such as fiber-mesh, WDM-XC, WDM-ADM. We observe the trade-off between link cost and node cost in WDM ring networks for the performance comparison.
UASB에 의한 有機性 廢水處理의 溫度影響에 관한 硏究
姜龍太,崔廷宇,全裕燦 東亞大學校 海洋資源硏究所 1991 硏究論文集 Vol.4 No.1
The purpose of this research was to investigate the effects of temperatures on the wastewater treatment. The experimental results used synthetic wastewater showed that removal efficiency of UASB ranged from 83 to 93 percents within a temperature ranges of 20 to 35℃, which indicated that the removal rates decreased approximately 2 or 3 percent as the temperatures reduced at intervals of 5℃. The production of waste sludge was a little, on the other hand, the treatment efficiency of it was very high. Obtained from this experimentation the values of temperature characteristic term(θ), Q?? and activated energy(E??) were 1.053, 1.69 and 9349cal/mole, respectively. We could find out the size and concentration of granular sludge decreased in proportion to the reduction of temperature, and a filamentous bacteria of Methanothrix spp. was prevailed more than a bacteria of other species in the granules.