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Membrane Characteristics for Removing Particulates in PFC Wastes
Gye-Nam Kim,Sung-Yeol Lee,Hui-Jun Won,Chong-Hun Jung,Won Jin Oh,Jin-Ho Park 한국방사성폐기물학회 2005 방사성폐기물학회지 Vol.3 No.2
원자력연구시설의 핫셀 내 바닥이나 장치표면에 부착된 고방사능분진의 제거를 위해서 PFC제염기술을 적용한다. 고가인 PFC 용액의 재사용을 위해서는 여과장치의 개발이 필요하고 제염종료 후 이차폐기물의 양을 최소화할 필요가 있다. PFC 제염폐액 내 방사성 입자를 제거하기 위해 핫셀 내의 고방사능분진의 오염 특성을 조사했다. 여과 막을 이용한 입자의 제거효율 측면에서 보면 세라믹 , PVDF, PP 막 모두가 95 이상의 높은 여과 성능을 보였다. 기공 크기가 같은 동일 여과 막에서는 입자가 크거나 가하는 압력이 높을수록 좀더 높은 제거효율을 나타내었고, 3psi이하에서는 PVDF의 제거효율이 다른 막에 비해 작게 나타났다. 플럭스 성능은 PVDF 막이 가장 높은 수준을 나타냈고 세라믹과 PP 막에서는 다소 낮은 성능을 보였다. PVDF 막은 낮은 압력과 짧은 여과시간으로 최대(한계)플럭스에 도달함을 확인하였다. 세라믹 막은 모의입자의 제거 효율은 높지만 다소 낮은 Flux 성능을 나타냈다. 또한, 막 자체의 비싼 가격과 쉽게 부서지는 성질의 단점을 지니고 있지만 무기화합물의 재질로 되어있기 때문에 알파방사능 환경에서 H, 가스를 발생하는 고분자 막인 PVDF, PP 막과 비교하여 훨씬 안정적이었다. 그리고 이들 소수성 여과막들의 특성 비교를 바탕으로 세라믹 막을 적용한 PFC 실증 여과장치의 공정도를 살펴보았다. PFC(Perfluorocarbon) decontamination process is one of best methods to remove hot particulate adhered at inside surface of hot cell and surface of equipment in hot cell. It was necessary to develop a particulate filtration equipment to reuse PFC solution used on PFC decontamination due to its high cost and to minimize the volume of second wastewater. Contamination characteristics of hot particulate were investigated and then a filtration process was presented to remove hot particulate in PFC solution generated through PFC decontamination process. The removal efficiency of PVDF(Poly vinylidene fluoride), PP(Polypropylene), Ceramic(AlO filter showed more than 95. The removal efficiency of PVDF filter was a little lower than those of other kiters at same pressure(3psi). A ceramic filter showed a higher removal efficiency with other filters, while a little lower flux rate than other filters. Due to inorganic composition, a ceramic filter was highly stable against radio nuclides in comparison with PVDF and PP membrane, which generate H gas in e-radioactivity atmosphere. Therefore, the adoption of ceramic filter is estimated to be suitable for the real nitration process.
Trajectory Optimization for a Supersonic Air-Breathing Missile System Using Pseudo-Spectral Method
Park, Jung-Woo,Tahk, Min-Jea,Sung, Hong-Gye The Korean Society for Aeronautical and Space Scie 2009 International Journal of Aeronautical and Space Sc Vol.10 No.1
This paper deals with supersonic air-breathing missile system. A supersonic air-breathing missile system has very complicated and incoherent thrust characteristics with respect to outer and inner environment during operation. For this reason, the missile system has many maneuver constraints and is allowed to operate within narrow flight envelope. In this paper, trajectory optimization of the missile is accomplished. The trajectory optimization problem is formulated as a discrete parameter optimization problem. For this formulation, Legendre Pseudo-Spectral method is introduced. This method is based on calculating the state and control variables on Legendre-Gauss-Lobatto (LGL) points. This approach helps to find approximated derivative and integration quantities simply. It is shown that, for this trajectory optimization, trend analysis is performed from thrust characteristics on various conditions so that the trajectory optimization is accomplished with fine initial guess with these results.
Stability of New Carbapenem DA-1131 to Renal Dipeptidase : DehydropeptidaseⅠ
Park, Sung Wook,We, Jeoung Soon,Kim, Gye Won,Choi, Seong Hak,Park, Haeng Soon 전남대학교 약품개발연구소 2002 약품개발연구지 Vol.11 No.-
The stability of DA-1131 to renal dipeptidase (RDPase) (EC 3.4.13.19) was compared with that of imipenem and meropenem by V_max/ K_m ratios as an index of the enzyme's preference for substrates. Our results showed a decreasing order of imipenem (6.24), meropenem (2.41), and DA-1131 (1.39). The biochemical evaluation of DA-1131 as the least preferred substrate of RDPase suggest its potential use as a novel β-lactam antibiotic which may be usable without coadministration of RDPase inhibitors once its clinical suitability is proven.
Gye-Jeong Oh,Kwi-Dug Yun,Kwang-Min Lee,Hyun-Pil Lim,Sang-Won Park 대한치과보철학회 2010 The Journal of Advanced Prosthodontics Vol.2 No.3
PURPOSE. The purpose of this study was to compare the linear sintering behavior of presintered zirconia blocks of various densities. The mechanical properties of the resulting sintered zirconia blocks were then analyzed. MATERIALS AND METHODS. Three experimental groups of dental zirconia blocks, with a different presintering density each, were designed in the present study. Kavo Everest(R). ZS blanks (Kavo, Biberach, Germany) were used as a control group. The experimental group blocks were fabricated from commercial yttria-stabilized tetragonal zirconia powder (KZ-3YF (SD) Type A, KCM. Corporation, Nagoya, Japan). The biaxial flexural strengths, microhardnesses, and microstructures of the sintered blocks were then investigated. The linear sintering shrinkages of blocks were calculated and compared. RESULTS. Despite their different presintered densities, the sintered blocks of the control and experimental groups showed similar mechanical properties. However, the sintered block had different linear sintering shrinkage rate depending on the density of the presintered block. As the density of the presintered block increased, the linear sintering shrinkage decreased. In the experimental blocks, the three sectioned pieces of each block showed the different linear shrinkage depending on the area. The tops of the experimental blocks showed the lowest linear sintering shrinkage, whereas the bottoms of the experimental blocks showed the highest linear sintering shrinkage. CONCLUSION. Within the limitations of this study, the density difference of the presintered zirconia block did not affect the mechanical properties of the sintered zirconia block, but affected the linear sintering shrinkage of the zirconia block.
Sung, Hea Jung,Cho, Yu Kyung,Moon, Sung Jin,Kim, Jin Su,Lim, Chul Hyun,Park, Jae Myung,Lee, In Seok,Kim, Sang Woo,Choi, Myung-Gye Korean Society of Neurogastroenterology and Motili 2012 Journal of Neurogastroenterology and Motility (JNM Vol.18 No.3
<P><B>Background/Aims</B></P><P>Available data about reflux patterns and symptom determinants in the gastroesophageal reflux disease (GERD) subtypes off proton pump inhibitor (PPI) therapy are lacking. We aimed to evaluate reflux patterns and determinants of symptom perception in patients with GERD off PPI therapy by impedance-pH monitoring.</P><P><B>Methods</B></P><P>We retrospectively reviewed the impedance-pH data in patients diagnosed as GERD based on results of impedance-pH monitoring, endoscopy and/or typical symptoms. The characteristics of acid and weakly acidic reflux were evaluated. Symptomatic and asymptomatic reflux were compared according to GERD subtypes and individual symptoms.</P><P><B>Results</B></P><P>Forty-two patients (22 males, mean age 46 years) were diagnosed as GERD (17 erosive reflux disease, 9 pH(+) non-erosive reflux disease [NERD], 9 hypersensitive esophagus and 7 symptomatic NERD). A total of 1,725 reflux episodes were detected (855 acid [50%], 857 weakly acidic [50%] and 13 weakly alkaline reflux [< 1%]). Acid reflux was more frequently symptomatic and bolus clearance was longer compared with weakly acidic reflux. In terms of globus, weakly acidic reflux was more symptomatic. Symptomatic reflux was more frequently acid and mixed reflux; these associations were more pronounced in erosive reflux disease and symptomatic NERD. The perception of regurgitation was related to acid reflux, while that of globus was more related to weakly acidic reflux.</P><P><B>Conclusions</B></P><P>In patients not taking PPI, acid reflux was more frequently symptomatic and had longer bolus clearance. Symptomatic reflux was more frequently acid and mixed type; however, weakly acidic reflux was associated more with globus. These data suggest a role for impedance-pH data in the evaluation of globus.</P>
Performance Comparison of Five SARS-CoV-2 Antibody Assays for Seroprevalence Studies
Park Younhee,Hong Ki Ho,Lee Su-Kyung,Hyun Jungwon,Oh Eun-Jee,Lee Jaehyeon,이혁민,Song Sang Hoon,Kee Seung-Jung,Kwon Gye Cheol,Kim Su Hwan,Do Hyeon-Nam,Kim Ah-Ra,Lee June-Woo,Kim Sung Soon,Kim Hyun Soo 대한진단검사의학회 2022 Annals of Laboratory Medicine Vol.42 No.1
Background: Seroprevalence studies of coronavirus disease 2019 (COVID-19) cases, including asymptomatic and past infections, are important to estimate the scale of the disease outbreak and to establish quarantine measures. We evaluated the clinical performance of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) antibody assays available in Korea for use in seroprevalence studies. Methods: The sensitivity, specificity, cross-reactivity, and interference of five SARS-CoV-2 antibody assays were evaluated using the following: 398 serum samples from confirmed COVID-19 patients, 510 negative control samples from before 2018 (pre-pandemic), 163 serum samples from patients with SARS, Middle East respiratory syndrome (MERS), and other viral infections, and five samples for the interference study. Results: The sensitivities of the five assays ranged from 92.2% to 98%, and their specificities, including cross-reactivity and interference, ranged from 97.5% to 100%. The agreement rates were excellent (kappa >0.9). Adjustment of the cutoff values could be considered through ROC curve analysis. The positive predictive values of the individual assays varied from 3.5% to 100% at a 0.1% prevalence but were as high as ≥95% when two assays were combined. Conclusions: The prevalence of COVID-19 in Korea is considered to be exceptionally low at present; thus, we recommend using a combination of two or more SARS-CoV-2 antibody assays rather than a single assay. These results could help select SARS-CoV-2 antibody assays for COVID-19 seroprevalence studies in Korea.
Sex Ratio and Sex Reversal in Two-year-old Class of Oyster, Crassostrea gigas (Bivalvia: Ostreidae)
Park Jung Jun,Kim Hyejin,Kang Seung Wan,An Cheul Min,Lee Sung-Ho,Gye Myung Chan,Lee Jung Sick 한국발생생물학회 2012 발생과 생식 Vol.16 No.4
The sex ratio (F:M) in the same population of oyster, Crassostrea gigas at the commencement of the study (2007) was 1:1.0, but changed to 1:2.8 by the end of the study (2008). The sex reversal rate in two-year-old oysters was 40.2%. Specifically, female to male sex reversal rate was 66.1%, which is higher than the male to female sex reversal rate of 21.1%. The sex reversal pattern of C. gigas appears to go from male female male, and as such is determined to be rhythmical hermaphroditism.
A Study on the Behavior of Ultrasonic Guided Wave Mode in a Pipe Using a Comb Transducer
Park, Ik Keun,Kim, Yong Kwon,Cho, Youn Ho,Song, Won Joon,Ahn, Yeon Shik,Cho, Yong Sang,Jung, Gye Jo Trans Tech Publications, Ltd. 2005 Key Engineering Materials Vol.297 No.-
<P>A preliminary study of the behavior of ultrasonic guided wave mode in a pipe using a comb transducer for maintenance inspection of power plant facilities has been verified experimentally. Guided wave mode identification is carried out in a pipe using time-frequency analysis methods such as wavelet transform (WT) and short time Fourier transform (STFT), compared with theoretically calculated group velocity dispersion curves for longitudinal and flexural mode. The results are in good agreement with analytical predictions and show the effectiveness of using the time-frequency analysis method to identify the individual guided wave modes. And, It was found out that longitudinal mode (0, 1) is affected by mode conversion less than the other modes. Therefore, L (0, 1) is selected as a optimal mode for evaluating location of the surface defect in a pipe.</P>