Multi-Code CDMA 시스템 성능 향상에 관한 연구

천병걸,홍인기 경희-다반 ASIC 설계교육센터 2003 경희-다반 ASIC센터 논문집 Vol.4 No.-

본 논문은 고속 데이터 전송을 위해 사용되는 Multi-Code CDMA 성능 향상에 관한 연구이다. 기존의 Multi-Code CDMA 시스템은 단일경로에서는 고속전송이 가능하나 다중경로로 신화가 수신될 경우 간섭성분의 영향이 훨씬 커지는 문제점이 있었다. 이를 본 논문에서는 새로운 Code LAS-Code를 사용하여 보았고 전송방식을 MCCS(Multi-Carrier Code Selection) CDMA 방식으로 하여 성능 향상에 관하여 살펴보았으며 마지막으로 LAS-Code를 MCCS에 적용하였을 경우의 성능 향상에 관하여 살펴보았다.

광산폐수의 중금속 제거에 대한 온도의 영향

백병천,김광복 國立 麗水大學校 環境問題硏究所 1999 環境硏究論文集 Vol.2 No.-

SRB(Sulfate Reducing Bacteria) converts into sulfide using an organic carbon source as the electron donor. The sulfide formed precipitates the various matals present in AMD(Acid Mine Drainage). In this study, the effects of temperature on sulfate reduction and heavy metals removal from AMD were investigated in batch and continuous flow reactors operating at the range from 15˚C to 40˚C. Reduced sulfate/removed COD(mg/mg) ratio maximized at temperature of 30˚C in the batch reactor operating at COD(glucose)/sulfate ratio of 0.5 and then removal efficiencies of heavy metals were 97.5% of Cu, 99.99% of Pb, 99.99% of Cr, 49% of Mn, 98% of Zn, 99.99% Cd and 92.4% of Fe. Two anaerobic floating media reactors were continuously operated at hydraulic retention time of 3days, COD/sulfate ratio from 0.3 to 0.8, temperature from 30˚C to 35˚C, and alkalinity of 1000mg/ℓ (as CaCO_(3)). At CCD/sulfate(SO_(4)^(2-)) ratio of 0.5 and temperature of 35˚C, the ratio of reduced sulfate(SO_(4)^(2-))/removed COD(mg/mg) kept about 1 and the reactor achieved 99.99% of Cr, Pb and Fe, 98% of Cd, and 90% of Mn removal efficiencies, respectively. Decreasing temperature to 30˚C increased the ratio of reduced sulfate(SO_(4)^(2-))/removed COD(mg/mg) to 1.31. Amount of sulfate reduction maximized at the temperature of 30˚C and the COD/sulfate ratio of 0.4 in the influent and then removal effciencies of heavy metals were 100% of Fe, 100% of Pb, 99.99% of Cr. 97.3% of Mn, 99.9% of Zn,99.9% of Cd and 99.9% Cu.

UASB 반응조내 생물학적 거동분석을 위한 모델링

백병천,전관수 麗水水産大學校産業技術硏究所 1992 産業基術硏究所 論文集 Vol.1 No.-

Modeling made it possible to predict the behavior of constituents and microorganisms, and microorganisms, and the changes of process variables with respect to the bed height by assuming the sludge bed zone in UASB(upflow anaerobic sludge blanket) reactor to be a series of CFSTRs(continuous flow stirred tank reactors) of which the volume is proportioned to the gas quantity passing the segmented zone. Mathematical simulations were attemped to identify the balance and distribution of the two microbial populations, which were divided into two groups of acidogenic and methanogenic bacteria, as well as the responces of reactor to the operational conditions in terms of the bed height. Considering the constituents as complex substrates composed of hydrolyzed and nonhydrolyzed materials and VFAs(volatile fatty acids), prediction of the concentration of each constituent was allowed. This reserch indicated that the UASB reactor was relatively stable to shock loading and that the lower part placed below the height of 20%-30% of the sludge bed probably served as a shock absorbing zone. About 70% of organic COD was removed in the lower 55% portion of the sludge bed height.

SM45C강의 Tempering 온도 변화에 따른 상온 및 300℃에서의 피로균열전파특성

장천수,김현철,임병수 成均館大學校 科學技術硏究所 1993 論文集 Vol.44 No.2

The effect of micros tructural and tempering temperature change on ΔK_th has been investigated at room temperature and 300℃ For the experiments, using SM4OC steel, specimens of different grain sizes, spacings between ΔK_th particles and tempering temperatures were prepared. Some of the conclusions obtained are as follows ; 1. ΔK_th values were greater at 300℃ when compared with those at room temperature and the crack growth rate decreased as test temperature increased. 2. ΔK_th was observed to increase with tempering temperature. However, ΔK_th value of 450℃ tempered specimen was very low, which is believed to be the result of Tempered Martensite Embrittlement(T.M.E.).

실폐광폐수의 중금속 제거를 위한 AFMR 공정 운전 연구

백병천,김광복 國立 麗水大學校 環境問題硏究所 2000 環境硏究論文集 Vol.3 No.-

This research is to establish operation technology of AFMR(Anaerobic Floating Media Reactor) Process for heavy metals removal from raw acid mine drainage. Two AFMR were operated at hydraulic retention time(HRT) of 3days, COD/sulfate ratio of 0.5, temperature of 30℃, and alkalinity from 600㎎/ℓ to 1,000㎎/ℓ (as CaCO_(3)). AT COD/sulfate(SO_(4)^(2-)) ratio of 0.5 and temperature of 30℃, the maximum ratio of reduced sulfate(SO_(4)^(2-))/removed COD(㎎/㎎) kept about 1.34 and the reactor achieved 99.9% of Cr, Cu and Fe, 99.4% of Pb, 99% of Zn, 98% of Cd, and 92.5% of Mn removal efficiencies, respectively. Increment of alkalinity in influent can lead to reduce level of heavy metals in effluent . In order to achieve the efficient removal of heavy metal from raw acid mine drainage, alkalinity of range from 800㎎/ℓ to 1,000㎎/ℓ (as CaCO_(3)) has to be supplied to the influent feed, Sulfate reducing bacteria(SRB) of rods and bacillus types were also observed on surface floating media used in this study.

영상정보저장 및 검색시스템

金炳天,金奉權 안성산업대학교 1991 論文集 Vol.23 No.-

오늘날 컴퓨터의 주된 사용은 많은 양의 데이터를 적절히 분류하여 저장하고 이들로부터 정보를 얻어내는 데 있다. 특히, 기호자료(symbolic data) 뿐만 아니라 영상자료(Image data)에 대한 처리가 필수적으로 요구되고 있는 시점에서 영상정보 저장 및 검색 시스템에 대한 중요성은 고조되고 있다. 그러므로 영상정보를 다루기 위한 시스템은 매우 중요한 것으로 인식된다. 본 논문에서는 영상정보의 저장 및 검색 기법에 대해 논하며, 영상정보 저장 및 검색 시스템을 설계하고 구현한 결과와 특징을 소개한다. Nowadays the main usage of a computer is to store and retrieve a large set of data. Especially there increases a need for a computer to handle image data as well as symbolic data. Thus, the role of image information system becomes very important. This paper dicusses key issues that one should consider when designing image information system. And then this paper describes main properties of our Image Information Store and Retrieval system.

생물여과반응기에서 폐가스의 VOC 제거에 대한 전자수용체의 영향

백병천,Xueqing Zhu 國立 麗水大學校 環境問題硏究所 1998 環境硏究論文集 Vol.1 No.-

Biofiltration is fast becoming the technology of choice for the control of the volatile organic compounds (VOCs) present in air streams due to its cost-effectiveness. This study was carried out to investigate the effect of electron acceptors on the performance of biofiltration process treating diethyl ether as a VOC substrate in waste gases. Two trickle bed biofilters with pelletized synthetic media were operated co-currently at a empty bed hydraulic retention time of 25 seconds, inlet gas flow rate of 8.64㎥/day, Nutrient liquid flowrate of 1L/day, and COD loading rate from 1.8 to 7.1㎏ COD/㎥.day. Nitrate and oxygen were used as the electron acceptor for the VOC (ether) biodegradation. By increasing the concentration of oxygen in the feed to this biofilter from 21% (ambient air) to 50% and 100% while maintaining an influent VOC (ether) concentration of 133 ppm_(v) and a feed nitrate concentration of 67㎎/ℓ, the performance of the biofilter was not significantly affected. However, the VOC (ether) removal efficiencies improved with increasing influent nitrate concentration. which suggest that nitrate is a good electron acceptor more than oxygen. It was also found that nitrate was rate limiting as a growth nutrient rather than as an electron acceptor, and that resistance to the transport of nitrate into the biofilm led to nutrient limitations in the deeper layers of the biofilm.

영상 데이타 베이스 시스템 설계 및 구현

金炳天,金三根 안성산업대학교 1991 論文集 Vol.23 No.-

This paper presents how to design the integrated image database system for image and relational database since past years. The image database management system that maintains both image and signal data is stored in logical image, which consists of the set of image objects, and relational table. Since database and image processing techniques have been recently developed, and memory and device technology have been considerably advanced, there are fast increasing the requirement that integrates both image and database. This paper, therefore, proposes the image database management system that introduces query for user friendliness. The purpose of this paper is to is to focus on concernment for image database.

탄화수소를 환원제로 하는 배연 탈질공정에서 금속이온교환된 ZSM-5 촉매들의 촉매활성 비교연구

김재천,한상현,신병선,정석진 경희대학교 산학협력기술연구원 1998 산학협력기술연구논문집 Vol.4 No.-

In this study, in order to make up its drawbacks in the Cu-ZSM-5 catalytic system, some of transition metals or alkaline earth metals were cocation-exchanged in Cu-ZSM-5. Among various cocation-ion-exchanged XSM-5 catalysts, Mg/Cu-ZSM-5 was found to be the most active and durable in NOx reduction even with high oxygen content as well as in the presence of water vapor. The role of Mg in ZSM-5 is supposed to prevent the dealumination of aluminium ions the in supercage even at harsh hydro-thermal conditions, and also it seems to stabilize the Cu ions in the structure. In order to prepare commercially available catalysts, Mg/Cu-ZSM-5 catalysts were wash-coated on the surface of honeycomb type monolith, and tested in terms of catalytic activities. As a results, it was found that the catalyst prepared by the wash-coating showed satisfactorily high NOx conversion for the practical in the SCR process.

어린이의 식이습관과 치아우식발생과의 상관관계에 관한 연구

김재곤,전철완,이두철,백병주 대한소아치과학회 2001 大韓小兒齒科學會誌 Vol.28 No.2

본 연구는 치아우식 발생과 식이습관과의 상관관계를 알아보기 위하여 전주시내 소재 유치원에 다니는 남아 143명과 여아 124명을 대상으로 유치의 우식경험지수를 조사하고, 어머니로부터 설문조사를 통하여 어머니의 직업유무, 수유경험 및 어린이의 식품기호도 등을 조사한 후 이상의 자료를 분석하였으며, 본 연구에서 나타난 결과들을 중심으로 다음과 같은 결론을 얻었다. 전체 어린이의 유치 우식경험지수는 2.92±1.05이였으며 여아(3.40±1.46)가 남아(2.51±0.97) 보다 다소 높은 우식경험지수를 나타냈으나, 남녀간의 유의한 차이는 나타나지 않았으며(P>0.05), 연령에 따른 유치의 우식경험지수를 비교한 결과, 나이가 증가할수록 높아지는 양상을 보였으며, 3세와 4세에 비해 5세와 6세에서 각각 높은 우식경험지수를 나타냈다(P<0.05). 각 식품군에 대한 기호도에서 남아는 과실류를, 여아는 해조류를 가장 좋아하였으며, 해조류를 제외한 다른 식품군에서 남녀별 유의한 차이를 나타내지 않았으며(P>0.07), 조사 식품군에 대한 어린이의 기호도와 관련한 유치 우식경험지수를 비교한 결과. 당류(r=0.3854, P<005), 유류(r=0.4328, P<0.05), 음료(r=0.2586, P<0.05)에서는 유의성이 인정되었으나, 다른 식품군에서는 유의한 상관성이 인정되지 않았다(P>0.05). The aim of the present study was to analyze relationship between dietary habits and dental caries experience inpreschool children. All 143 boys and 124 girls living in a chonju city were investigated dmf index by dentists through oral examination and dietary habit by children's mothers through questionaires such as infant diets and food preferences. The statistical analysis were performed to evaluate whether variations in dietary habits are related to dental caries experience. The obtained results were as follows; 1. The average dmf index scores of all children were examined 2.92±1.05. The girls had higher than the boys, but no significant differences between the genders were seen the을 index(P>0.05). 2. The higher were their age of children, the higher dmf index was investigated. The dmf index of 5 and 6-yr old childrens was higher than that in 3 and 4-yr old children(P<0.05). 3. No sigificant difference was found between the present of mother's occupation (P>0.05) and type of infant dietary habits(P>0.05). 4. The fruits and sea weeds were showed high degree of preference and fats and vegetables were showed low degree generally. Among 13 food groups, there was no significant difference between boys and girls except for sea weeds(P>0.05). 5. Among 13 food groups, the을 index was positively associated with sugars(r=0.3854, P<0.05), dairy products(r=0.4328, P<0.05) and soft drinks(r=0.2586, P<0.05), and negatively associated with other food groups.