전력선 채널에서의 DS/SSMA BPSK 코릴레이션 수신기 성능에 관한 연구

강병권,조창길,조관,이재경,황금찬,Kang, Byeong-Kwon,Cho, Chang-Gil,Cho, Kwan,Lee, Jae-Kyeong,Whang, Keum-Chan 한국통신학회 1992 韓國通信學會論文誌 Vol.17 No.9

본 논문에서는 전력선 채널에서 DS/SSMA BPSK 통신 시스템의 전형 및 하드리미팅 상관 수신기의 성능을 분석하였다. Chan의 잡음 모델을 이용하여 전력전에서 발생하는 강한 임펄스성 잡음을 배경 잡음에 대한 임펄스성 잡음의 전력 스펙트럼 밀도비 $(N_1/N_b)$, 데이터 폭에 대한 임펄스성 잡음 폭의 비(f). 임펄스성 잡음의 발생주기에 대한 임펄스 잡음 폭 (DF)등의 파라미터로 모델링하여, 각 파라미터 변화에 따른 시스템의 성능을 분석하고, 다중접속 간섭 잡음을 가우시안 근사화하여 각 수신기의 다중접속 능력을 평가하였다. 분석 결과 $N_1/N_b$가 작고 f가 1에 가까운 경우 전형 상관 수신기의 성능이 더 우수했으나, $N_1/N_b$가 증가함에 따라 하드리미팅 상관 수신기가 비트 오율 및 다중 접속 능력면에서 전형 상관 수신기보다 더 우수한 성능을 나타냈다. In this paper, the performance of linear and hard-limiting correlation receivers for DS/SSMA BPSK power line communication system is analyzed. Strong impulsive noise of power line is modeled with Chan's noise model, and the performance of both receivers is analyzed in terms of parameters such as ratio of power spectrum density of impulsive noise to that background noise, ratio in impulsive noise width th that of data bit, and interarrival time of impulsive noise. And also multiple access capacity is evaluated with Gaussian approximation of multiple access interference. The results of this analysis reveal that the performance of linear correlation receiver is superior to that of hard-limiting correlation receiver when $N_1/N_b$ is small and is close to 1. But the BER and the multiple access capacity of hard-limiting correlation receiver becomes better in comparison with linear correlation receiver as $N_1/N_b$ increases.

돼지설사 원인균 E. coli의 생육저해에 대한 유산균의 효과

姜國熙,成文喜,方泰瑛,龍球淵,林讚洙 成均館大學校 科學技術硏究所 1985 論文集 Vol.36 No.1

E. coli A_2 diarrhea causing bacteria of pigs was anaerobically inoculated with 10^5/ml into prereduced YS medium (10% reconstituted skim milk+0.1% yeast extract), and then lactic acid bacteria were inoculated with 10^5/ml and 10^7ml into previous inoculated samples of E. coli A_2. Inoculated samples cultured at 37℃, were tested to determine changes in viable numbers of organisms and pH. The experimental results are summerized as follows: 1. In the mixed culture medium of 10^5/ml E. coli A_2 and L. casei YIT9018, E. coli A_2 decreased after 36 hours from incubation. 2. In the mixed culture medium of 10^5/ml E. coli A_2 and L. acidophilus, E. coli A_2 drastically decreased after 24 hours from incubation and was almost disappeared after 72 hours from incubation. 3. In the mixed culture medium of 10^5/ml E. coli A_2 and L. bulgaricus, E. coif A_2 drastically decreased after 24 hours from incubation and was almost disappeared after 72 hours from incubation. 4. In the mixed culture medium of 10^5/ml E. coli A_2 and Str. thermophilus, E. coli A_2 decreased after 12 hours from incubation. 5. When the pH value of the mixed culture, was, 4. 5 below, E. coli A_2 decreased.

유기산 완충용액의 포화도가 상아질의 탈회에 미치는 영향

강혜실,이찬영 大韓齒科保存學會 2004 Restorative Dentistry & Endodontics Vol.29 No.5

The purpose of this study is to compare and to evaluate the effects of the degree of saturation on the progression of artificial root caries lesion. A total of 8 human premolars without any defects and cracks selected and the cementum were removed and the teeth were cleaned with ultrasonic device and pumice without fluoride. Each tooth was sectioned into 6 pieces and they were ground with #800 sandpaper until they had a thickness of 200 ㎛. Specimens were applied with nail vanish except for the 2-3 mm window area after application of bonding agent. Under the constant pH, the specimens were divided into 6 groups (degree of saturation: 0.1415, 0.1503, 0.1597, 0.1676, 0.1771. 0.1977). Each group was immersed in acid buffer solution for 1, 2, 3, 5 days under controlled temperature (25℃) and imbibed in water and examined using the polarizing microscope. The results were as follows 1. Although the degree of saturation of demineralization solution decreased, the depth of penetration in the dentin was constant. 2. Erosion was observed on the surface of all the teeth in the group Ⅰ, Ⅱ. In the group Ⅲ, Ⅳ, Ⅴ, surfaces were not changed. The teeth in the group Ⅵ showed the more mineralized surface but not the shape of the dentinal tubules distinctively. 3. In all groups, the lesion progressed rapidly at the first day of the experiment, but increased gradually as time elapsed.

CR-39 플라스틱飛跡檢出器에 의한 ^7Li(p, ^4He)^4He 核反應의 斷面積 測定

姜榮浩,安燦基,金道聖 慶北大學校 1984 論文集 Vol.37 No.-

The ^7Li(p,^4He)^4He reaction is used for in searches of universal abundance of Li, nuclear energy stages of ^8Be, and final step of p-p fusion cycle. In this work, we have detected and identified ^3He and ^4He from the ^6Li(p,^3He)^4He reaction and ^4He from the ^7Li(p,^4He)^4He reaction by the energy dependence of the etch pit diameter of the chemically etched tracks in CR-39. The target was 12㎍/㎠ thin film of natural lithium evaporated in the 10㎛/㎠ carbon backing. The target thickness was measured by Rutherford scattering of proton particles. For proton energies between 148keV and 462keV, differential cross section, angular distribution, and total cross section were measured. The results were compared with the previous measurements and Gamow-Diagram.

Back-Propagation Algorithm 상에서의 성능에 미치는 Parameters 분석에 관한 연구

강수연,박찬호,이현수 慶熙大學校 1994 論文集 Vol.23 No.-

신경망에서 가장 많이 사용되고 있는 알고리즘 중의 하나가 역전파(Back-Propagation) 알고리즘이다. 역전파 알고리즘에서 문제해결에 본질적인 영향을 주는 몇가지 요인들이 존재한다. 본 연구에서는 이 몇가지 요인들이 각각의 응용 문제의 해를 얻는데 미치는 영향을 시뮬레이션 결과를 통해 알아보고 이를 분석및 고찰 하였다. 고려 대상의 요인들로써는 learning rate, momentum, weight 초기값, 은닉 유니트수를 들 수 있다. 응용 문제 대상은 XOR 문제와 8*8 dot alphanumeric font 학습으로 하였다. Back-Propagation is one of algorithms that are currently used in neural network. It has some factors that basically affect on solving problems. On this paper, we analyze and investigate several learning parameters that effect on solutions of each application problems through simulation result. Considered factors are learning rate, momentum, initial weight values and the number of hidden units. Applied problems are XOR learning and 8*8 dot alphanumeric font learning.

生物膜 ?過裝置에 의한 下水處理에 관한 硏究

姜龍太,全裕燦,趙奉衍 東亞大學校 1986 東亞論叢 Vol.23 No.1

This study, through the filtration experiment by biofilm, was explained the operation for each processes in its system, and were investigated the actual(filtration experiment by biofilm) applicational propriety for the existing headloss quation and the correlation of factors. The results of the experiment are the following. 1. When the raw water quality was reached to standars of the treated water quality in about a week, the average removal rates of SS, BOD and COD were 92%, 91% and 74%, respectively. 2. In case that the experimental conditions were water quantity, 0.67㎥/day, BOD 100㎎/ℓ, oxygen absorption efficiency, 16%, air quantity was 15N㎥ and showed high BOD removal rate. 3. The backwashing water quantity was required the twice or the three times of the packed volume. 4. When thd BOD loading was less then 5 ㎏/㎥·day, the BOD removal rate showed more than 95%. 5. The headloss of this experiment was approximated to the value obtained from substiting the filtration Model Ⅰ for the Kang's headloss equation corrected for the Kozeny-Carman's.

액체-고체 순환유동층에서 액상의 반경 방향 혼합 및 액체-고체 Chaotic 흐름 거동

강석환,이찬기,송평섭,강용,김상돈,김승재 한국화학공학회 2004 Korean Chemical Engineering Research(HWAHAK KONGHA Vol.42 No.2

직경이 0.102m이고 높이가 3.5m인 액체-고체 순환유동층의 상승관에서 압력요동 및 액체의 반경 방향 혼합 특성을 고찰하였다. 상승관에서 얻은 압력요동을 해석하기 위하여 chaos 이론을 도입하였다. 액체 유속, 유동입자의 크기 그리고 고체 유동입자의 순환속도가 연속액상의 반경방향 분산계수 및 압력요동의 위상공간투영과 상관차원에 미치는 영향을 결정하였다. 본 연구의 결과 액상의 반경방향 분산계수는 유동입자의 크기와 순환속도가 증가함에 따라 증가하였으며 액상의 유속이 증가함에 따라 감소하였다. 상승관에서 압력요동의 위상공간투영은 유동입자의 크기가 고체 유동입자의 순환속도가 증가함에 따라 점점 분산되고 복잡하게 되었으나, 액체유속이 증가함에 따라서는 위상공간에서 궤적의 분산이 다소 감소하는 경향을 나타내었다. 압력요동의 상관차원은 유동입자의 크기와 고체 순환속도가 증가함에 따라 증가하였으나, 액체의 유속이 증가함에 따라서는 큰 변화가 없었다. 본 연구의 결과는, 상승관에서 액상의 반경 방향 혼합 특성 압력요동 측정함으로써 실시간으로 예측하는 것을 가능하게 하여 실제공정에 응용함으로써 그 실용적 측면이 크다고 하겠다. Characteristics of pressure fluctuations and liquid dispersion in the radial direction were investigated in the riser of a liquid-solid circulating fluidized bed whose diameter was 0.102m and 3.5m in height. The concept of chaos theory was employed to analyze the pressure fluctuations obtained in the riser. Effects of liquid velocity, particle size, and solid circulation rate on the liquid radial dispersion coefficient and phase space portraits and correlation dimension of pressure fluctuations were determined. It was found that the radial dispersion coefficient of liquid phase increased with increasing particle size or solid circulation rate, but decreased with increasing liquid velocity. The attractor in the phase space portraits became more scattered and complicated with increasing particle size or solid circulation rate, but it became somewhat less scattered with increasing liquid velocity. The correlation dimension of pressure fluctuations increased with increasing particle size or solid circulation rate, but it did not change considerably with increasing liquid velocity. The results of this study enable us to predict the characteristics of liquid radial dispersion by means of the pressure fluctuations for the practical applications.

空氣拳銃 擊發時 心拍數 變化에 관한 硏究

康燦金 단국대학교 1986 論文集 Vol.20 No.-

The result of investigation into the variation of the number of heart beating. The score rate by points and the point of impact by the position at firing an air rifle for the male shooter of B high school in Seoul has come out as the following. 1. The comparison of the score rate by points. In the a group. There were three who scored more than 20% from the total points 600.In the B group, on the other hand, there was only one. The rate of high gore in an average was in the A group that has many long experienced shooter, and of low score was in the B group. 2. The comparison of the point of inpact by the position. The shooters from A group K.K. N.,L.S.S., made 20%, 25.4% in the direction of 6~7o'clock, P.K.H.l8.3% in 4~5 0'clcrk, L.J.Y.21.7% in 7~8. From the B group, on the other hand, in the same direction of 7~8, K.M.H., H.S.W., K.S.K. made the same direction with 18.6,18.3,23.3%.The reason of uneven formation of the point of impact is the work of the individualities of the shooters. 3. The variation of the number of heart-beating at firing by the score, P.K.M. from the A group had faster heart beating while he was gaining in high score, others' heart beating, on the other hand were irregular. The reason can be interpreted as the shooters were selected without consideration for the synthetic aptitude.

TDI계 수분산성 폴리우레탄 접착제의 특성에 Diisocyanate의 구조가 미치는 영향

강승구,송봉근,이재흥,박찬조,류해일 한국공업화학회 2003 공업화학 Vol.14 No.3

수년 전부터 많은 연구자들에 의해 폴리우레탄의 수용화, 수분산화의 연구가 수행되어 왔다. 그럼에도 불구하고 폴리우레탄의 특성에 디이소시아네이트가 구조에 미치는 영향에 대한 연구는 많이 진행되지 않았고 또한 미흡한 상태이다. 따라서 번 연구에서는 디이소시아네이트의 형태와 함량 변화에 따른 폴리우레탄의 특성을 연구하였다. 폴리우레1탄 수분산체(PUD)는 poly(tetramethylent ether) glycol (PTMG), isophorone diisocyanate (IPDI), toluene 2,4-diisocyanate (TDI), dimethylol propionic acid (DMPA), trethylamine (TEA) 등을 사용하여 제조하였다. 제조한 폴리우레탄 수분산체(PUD)의 구조를 FT-IR을 이용하여 확인하였다. 폴리우레탄 수분산체의 특성은 DSC, gel permeation chromatography (GPC), particle analyzer, universal testing machine (UTM) 등을 사용하여 측정하였다. 폴리우레탄 수분산체(PHD)에서 입자크기는 IPDI 함량이 증가할수록 작아지는 경향을 나타내었으며, 유리전이온도(Tg)는 IPDI 함량이 증가할수록 조금씩 낮아지는 경향을 나타내었다. 또한, 폴리우레탄 수분산체(PUD)의 접착세기 변화에서는 [NCO]/[OH] 몰비를 1.2로 유지되도록 하면서 합성에 관여하는 [NCO] 양에 해당하는 [TDI]/[IPDI] 몰비를 변화시켜 얻은 폴리우레탄 수분산체의 접착세기는 [TDI][IPDI] 몰비가 50/50일때 좋은 집착세기를 나타내었다. 또한 [NCO]/[OH] 몰비를 1.6으로 일정하게 유지되도록 하고 [TDI]/[IPDI] 몰비를 변화시켜 얻은 폴리우레탄 수분산체의 접착세기는 [TDI]/[IPDI] 몰비가 75/25일 때 좋은 접착세기를 나타내었다. Aqueous polyurethane dispersions (PUD) has been investigated by many researchers for a long time. However, relatively little systematic work has been reported, in detail, on the effect of structure of the diisocyanate on the properties of polyurethane. This work describes the properties of polyurethane in relation to the variation of diisocyanate type and contents. Aqueous polyurethane dispersions (PUD) were prepared from the poly(tetramethylene ether) glycol (PTMG), toluene 2,4-diisocyanate (TDI), isophorone diisocyanate (IPDI), dimethyol propionic acid (DMPA), and triethylamine (TEA). Differential scanning calorimetry (DSC), FT-IR, GPC, universal testing machine (UTM), and particle analyzer were utilized to characterize the physical and mechanical properties of PUD according to diisocyanate type and contents. As the content of IPDI in PUD increased, the particle size decreased. The glass transition temperatures (Tg) of PUT were shifted to a lower temperature as IPDI conent increased. When [NCO]/[OH] mole ratio was 1.2, the adhesion force of PUD shown the best result at [TDI]/[IPDI] mole ratio of 50/50. And, at [NCO]/[OH] mole ratio of 1.2, the adhesion force of PUD was the best when [TDIl/[IPDI] mole ratio was 75/25.

Pd 촉매 하에서 알릴 디올의 아릴화 연구 : 방향족 히드록시 케톤 및 페닐 치환된 알릴디올의 합성 Highly Selective Synthesis of Phenyl-Substituted Allylic Diols

강석구,정경윤,박찬희,남궁은영,김태현 성균관대학교 기초과학연구소 1995 論文集 Vol.46 No.2

The coupling reaction of iodobenzene with allylic diols in the presence of Pd(OAc)_2 and nBu_3P as catalysts using K_2CO_3 as base afforded the phenyl-substituted allylic diols. However, under the same reaction conditions with Et3N as base, phenyl-substituted α-hydroxy ketone was obtained.