• The Korean Journal of Nuclear Medicine
• /
• 제38권5호
• /
• pp.338-343
• /
• 2004

Purpose: The purpose of this study was to develop a small animal PET using dual layer phoswich detector to minimize parallax error that degrades spatial resolution at the outer part of field-of-view (FOV). Materials and Methods: A simulation tool GATE (Geant4 Application for Tomographic Emission) was used to derive optimal parameters of small PET, and PET was developed employing the parameters. Lutetium Oxyorthosilicate (LSO) and Lutetium-Yttrium Aluminate-Perovskite(LuYAP) was used to construct dual layer phoswitch crystal. $8{\times}8$ arrays of LSO and LuYAP pixels, $2mm{\times}2mm{\times}8mm$ in size, were coupled to a 64-channel position sensitive photomultiplier tube. The system consisted of 16 detector modules arranged to one ring configuration (ring inner diameter 10 cm, FOV of 8 cm). The data from phoswich detector modules were fed into an ADC board in the data acquisition and preprocessing PC via sockets, decoder block, FPGA board, and bus board. These were linked to the master PC that stored the events data on hard disk. Results: In a preliminary test of the system, reconstructed images were obtained by using a pair of detectors and sensitivity and spatial resolution were measured. Spatial resolution was 2.3 mm FWHM and sensitivity was 10.9 $cps/{\mu}Ci$ at the center of FOV. Conclusion: The radioactivity distribution patterns were accurately represented in sinograms and images obtained by PET with a pair of detectors. These preliminary results indicate that it is promising to develop a high performance small animal PET.

• Korean Journal of Poultry Science
• /
• 제17권1호
• /
• pp.53-58
• /
• 1990

Tests to evaluate the efficacy of disinfectant "Lysococ" against the oocfsts of Eimeria tenella were tested. In the sporulation test the sporulation of unsporulated oocysts of E. tenella was nearly suppressed by contact with "Lysococ" in 4% concentration after 30 minutes. In the suspension test with sporulated oocysts, "Lysococ" 4% disinfected sporulated oocysts of 5. tenella completely after a contact tune on 10 minutes. When using the oocyst-carrier test, the 4% solution was able to disinfect sporulated oocysts after a 90 minutes contact time.ter a 90 minutes contact time.

• Tuberculosis and Respiratory Diseases
• /
• 제50권4호
• /
• pp.426-436
• /
• 2001

Background : Chronic obstructive pulmonary disease(COPD) is one of the major contributors to morbidity and mortality among the adult population. Cigarette smoking(CS) is undoubtedly the single most important factor in the pathogenesis of COPD. However, its mechanism is unclear. The current hypothesis regarding the pathogenesis of COPD postulates that an imbalance between proteases and antiproteases leads to the destructive changes in the lung parenchyma. This study had two aims. First, to evaluate the effect of CS exposure on histologic changes of the lung parenchyme, and second, to evaluate the effect of CS exposure on the expression of the gelatinolytic enzymes in BAL fluid cells in guinea pigs. Methods : Two groups of five guinea pigs were exposed to the whole smoke of 20 commercial cigarettes per day, 5 hours/day, 5 days/week, for 6weeks, and 12 weeks, respectively, using a smoking apparatus. Five age-matched guinea pigs exposed to room air were used as controls. Five or more sections were microscopically extamined(${\times}400$) and the number of cellular infiltration of the alveolar wall was measured in order to evaluate the effect of CS exposure on the histologic changes of lung parenchyme. The statistical significance was analyzed by a linear regression method. To evaluate the expression of the gelatinolytic enzymes in intraalveolar cells, BAL fluid was obtained and the intraalveolar cells were separated by centrifugation (500 g for 10 min at $4^{\circ}C$). Two sets of culture plates were loaded with $1{\times}10^6$ intraalveolar cells. One plate, contained O.1mM EDTA, a inhibitor of matrix metalloproteases(MMPs), and the other plate had no EDTA. Both plates were incubated for 48 hours at $37^{\circ}C$. After incubation, gelatinolytic protease expression in the supernatants was analyzed by gelatin zymography. Results : At the end of CS exposure, the level of blood carboxy Hb had increased significantly(4.1g/dl in control group, 24g/dl immediately after CS exposure, 18g/dl 30 min after CS exposure, 15g/dl 1 hour after CS exposure). Alveolar inflammatory cells were identified in the CS exposed guinea pigs. The number of alveolar cellular cells observed in a microscopic field ($400{\times}$) was $121.4{\pm}7.2$, $158.0{\pm}20.2$, $196.8{\pm}32.8$, in the control, the 6 weeks, and the 12 weeks group, respectively. The increased extent of inflammatory cellular infiltration of the lung parenchema showed a statistically significant linear relationship with the duration of CS exposure(p=0.001, $r^2=0.675$). Several types of gelatinolytic enzymes in the intraalveolar cells of CS exposed guinea pigs were expressed, of which some were inhibited by EDT A. However, the gelatinolytic enzymes were not expressed in the control groups. Conclusion : CS exposure increases inflammatory cellular infiltration of the alveolar wall and the expression of gelatinolytic proteases in guinea pigs. EDTA inhibits some of the gelatinolytic proteases. These findings suggest a possibility that CS exposure may increase MMP expression in the lungs of guinea pigs.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
• /
• 한국전기전자재료학회 2010년도 하계학술대회 논문집
• /
• pp.300-300
• /
• 2010

Ceramic capacitor의 에너지내량을 향상시켜 제품의 신뢰성을 높이고자 RF Sputtering을 이용하여 외부전극을 형성하였다. 본 연구에서는 Target의 종류, 증착 시간 및 열처리 유/무에 따른 Ceramic capacitor의 전기적 특성 및 미세구조를 분석하여 최적조건을 확립하였으며, 최적 증착 조건으로 제작한 Ceramic capacitor의 에너지내량을 측정하였다. Target은 Ni target과 Cu target을 사용하였으며, Sputtering 시간은 10, 30, 60분으로 하였다. Sputtering 시간에 따른 Ceramic capacitor의 용량 특성과 손실은 큰 차이가 없었지만, Wire 연결시 Sputtering 시간에 따라 납땜성의 차이가 나타났으며, 증착 시간과 열처리 유/무에 따른 에너지내량의 변화를 확인하였다.

• Food Science and Preservation
• /
• 제13권2호
• /
• pp.119-124
• /
• 2006

This study was conducted to optimize roasting process of Job's tears for utilization as food Optimal condition for masting was investigated with changes in temperature and time by response surface methodology. The qualities of water extract such as browning degree, polyphenol and DPPH radical scavenging ability were affected more by roasting temperature than time. The values increased with temperature and time proportionally. The response variables were more significant with temperature than time and the established polynomial model was suitable (P>0.05) model by Lack-of-Fit analysis. Optimal roasting conditions with the limit of $0.2{\sim}0.3$ browning degree, $2.0{\sim}2.5{\mu}g/mL$ polyphenol, $30{\sim}40%$ scavenging ability and $0{\sim}100$ hue angle were $215^{\circ}C$ and 32 min.

• KSBB Journal
• /
• 제22권6호
• /
• pp.438-442
• /
• 2007

A biosensor using electrochemically-active bacteria (EAB) enriched in three-electrode electrochemical cell, was developed for the determination of biochemical oxygen demand (BOD) in wastewater. In the electrochemical cell, the positively poised working electrode with applying a potential of 0.7 V was used as an electron acceptor for the EAB. The experimental results using artificial and raw wastewater showed that the current pattern generated by the biosensor and its Coulombic yield were proportional to the concentration of organic matter in wastewater. The correlation coefficients of BOD vs Coulombic yield and $BOD_5$ vs Coulombic yield were 0.99 and 0.98, respectively. These results indicate that the biosensor enriched with the EAB capable of transferring electrons directly toward the electrode can be utilized as a water-quality monitoring system due to a quick and accurate response.

• Science of Emotion and Sensibility
• /
• 제12권2호
• /
• pp.169-180
• /
• 2009

The present study have investigated the effect of the characteristics of stereoscopic images and viewing environment on visual fatigue. We manipulated the speed of stereo images with motion-in-depth and viewing distance, which were used as representative variables of the characteristics of stereo image and viewing environment, respectively. Visual fatigue was evaluated with use of a subjective questionnaire which is consisting of 5 different and independent factors: "Eye pain", "Visual stress," "Nauseousness", "Body stiffness", and "Blurriness". In general, when viewing time increased from 10 minutes to 20 and 40 minutes, observers felt severe visual fatigue. Among other factors, only the factor score of "Nauseousness" was significantly increased as the speed of object moving in depth became faster. When viewing distance was increased, the score of "Blurriness" was decreased. These results suggest that different kind of the visual fatigue might be induced depending on characteristics of the stereo images and viewing environment.

• Proceedings of the Korean Society for Emotion and Sensibility Conference
• /
• 한국감성과학회 2001년도 춘계학술대회 논문집
• /
• pp.313-319
• /
• 2001

본 연구는 시뮬레이터 실험에서 필수적으로 발생하는 Simulator Sickness(SS)를 평가하기 위하여 동적 시뮬레이터에서 일정한 속도(60km/h)로 1시간 주행했을 때 Simulator Sickness Questionnaire(SSQ)를 이용하여 주관적 Sickness를 평가하고 생리적 반응으로 심박 변동량(HRV)과 피부온도 및 피부저항을 측정하여 성별, Simulator 수준에 따라 비교 분석하였다. 분석 결과 동적 시뮬레이터에서 주행시 주관적인 Simulator Sickness는 안정에 비해 시간이 지남에 따라 45분까지 선형적으로 증가하여UT고, 여자와 sick군이 남자와 nonsick군에 비해 더 높았으며 sickness 수준간에서는 유의성이 나타났지만 남녀간의 유의한 차이는 없었다. 생리적 반응은 시간에 따른 변화는 없었으나 안정에 비해 R-R 간격의 감소, (LF+MF)/total 및 (LF+MF)/HF의 증가로부터 교감 신경이 활성화되었으며 피부온도의 감소와 피부저항의 증가로부터 긴장도가 커짐을 알 수 있었다. 주행 50분 이후는 HF/total가 감소하여 부교감 신경의 작용이 저하되는 것으로 나타났다.. 성별, sickness수준에 따라서는 남녀간에는 부분적으로 유의한 차이가 있었고 평균 R-R 간격에서만 sick군이 nonsick군보다 유의하게 낮았다.

• Proceedings of the Korea Information Processing Society Conference
• /
• 한국정보처리학회 2001년도 추계학술발표논문집 (하)
• /
• pp.1383-1386
• /
• 2001

Internet 이용자의 급격한 증가와 광대역 통신망(B-ISDN) 구축의 확산에 따라 ATM(Asynchronous Transfer Mode)망 접속장치의 큰 수요가 기대되며, 또한 ATM망 접속장치의 성능 향상도 요구되고 있다. 기존의 연구들은 컴퓨터 프로그램의 메모리에 대한 참조가 지역적이라는 특성을 이용한 가상 메모리의 효율적인 페이지 교체 알고리즘 및 캐쉬 처리 방안들이 진행되어 왔다. 본 논문은 ATM 프로토콜 프로세서를 설계하는데 있어 네트워크 트래픽의 지역성(Locality of Reference)을 고려한 캐쉬 메모리 구조를 적용하여 보다 향상된 ATM 셀 수신이 가능하도록 한다. ATM 셀의 가상 패스 식별자/가상 채널 식별자(VPI/VCI)를 캐쉬 처리함으로써, 패킷을 분해, 재조립(Segmentation and Reassembly)할 때 관련 테이블의 검색 시간을 줄일 수 있다. 캐쉬 메모리 적용으로 인한 성능 향상을 평가하기 위해 ATM NIC 프로세서와 내부 캐시 메모리 그리고, 외부 SRAM 사이에 셀 수신 정보의 Read 와 Write에 드는 시간 비용(System Clock Cycle)을 캐시의 Hit 또는 Miss 등에 따라 구분하고, 이를 기반으로 한 시뮬레이터에 3 종류의 ATM 셀 스트림을 가하여 각각에 대해 평균 셀 처리시간, 데이터 버스의 트래픽 비율 그리고, 히트율의 3가지 평가요소를 측정하고, 비교하였다.

• Analytical Science and Technology
• /
• 제18권4호
• /
• pp.292-297
• /
• 2005

The effect of neutron irradiation on the chemical properties was measured in boric acid solution. The pH of the solution decreased in proportion to the irradiation time and the concentration of boric acid. The concentration of hydrogen peroxide, which is one of the radiolysis products of water, is in proportion to the concentration of boric acid, while in inverse proportion to the irradiation time. The oxygen and hydrogen gases had same chemically equivalent ratio in water radiolysis. The lithiun, which comes from $^{10}B(n,{\alpha})^7Li$, had poor relationship with neutron irradiation time at low concentration, $233{\sim}699{\mu}g/mL$, of boric acid, but the relationship was improved at higher concentration.