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Coacervation-상분리법으로 만든 Ethyl Cellulose 마이크로캅셀의 Glibenclamide 방출특성 및 수용성 첨가제의 영향
김병조,장정수,이문주,김상헌,최영욱 중앙대학교 약학연구소 1996 약학 논총 Vol.10 No.-
Glibenclamide (GBC) is a well-known antidiabetic agent, which stimulates the secretion of endogenous insulin by pancreatic βcells. However, administration of GBC at a high dose can occasionally induced the fatal hypoglycemia, especially in the patients with impaired liver function. Therefore, in order to develop an oral sustained-release preparation which reduces the side effect, microcapsulation of GBC has been carried out in this experiment. Microcapsules of GBC were prepared by coacervation-phase separation method with ethylcellulose as a wall-forming material in cyclohexane, using polyisobutylene as a coacervation-inducing agent. Different amounts of hydrophilic additives. L-arginine(ARG) and polyethylene glycol 4000 (PEG), were added to the microcapsule wall, in order to alter the porosity of the wall and hence to enhance the release of the core material. The microcapsules prepared were examined for physical properties by scanning electron microscopy (SEM) and particle size analysis. The release of the poorly water-soluble GBC was found to be very slow from the microcapsules and strongly dependent on the core to wall ratio of the microcapsules, but it was accelerated considerably with increasing amount of PEG or ARG. In general, on the basis of dissolution kinetics, GBC releases from microcapsules were followed apparent first-order kinetics, while the dissolution data of GBC powder conformed to Hixon-Crowell's cube root law. Therefore, in conclusion, it might be possible to design the sustained-release formulation by the combination of both GBC powder and microcapsules of different core wall ratio with or without hydrophilic additives.
Effective detective quantum efficiency of two detectors in a prototype digital breast tomosynthesis
Choi, Seungyeon,Choi, Sunghoon,Lee, Donghoon,Kim, Ye-seul,Choi, Young-Wook,Kim, Hee-Joung Elsevier 2019 Optik Vol.178 No.-
<P><B>Abstract</B></P> <P>Digital breast tomosynthesis (DBT) system is a novel imaging modality that strongly depends on the detector performance. The effective detective quantum efficiency (eDQE) is a newly accepted system of performance analysis metric that solves the disadvantages of conventional DQE evaluations, which do not consider clinical operating conditions. To evaluate the eDQE, we used the direct-conversion based Anrad detector and the indirect-conversion based Dexela detector. Our aim is to study the performance of such detectors when they are mounted on a prototype DBT system. The prototype DBT system consists of a CsI(Tl) scintillator/CMOS-based flat panel digital detector and an a-Se based direct conversion detector developed by the Korea Electrotechnology Research Institute (KERI). The performance of the two detectors was compared on the basis of scatter fraction, transmission factor, effective modulation transfer function (eMTF), and effective normalized noise power spectrum (eNNPS). As a result, the Dexela detector is characterized by a decreasing eNNPS trend as the spatial frequency increases, whereas the Anrad eNNPS looks almost independent of the spatial frequency. The eMTF was found to be higher in the Anrad detector compared to that in the Dexela one for all frequencies. The eDQE values at 1 cycle/mm (low frequency) were 0.11 and 0.17 for the Anrad and Dexela detectors, respectively, and the values of the spatial frequency <SUB> f e D Q E ( 0.1 ) </SUB> , corresponding to eDQE = 0.1, were 1.25 and 2.81 cycles/mm for the Anrad and Dexela detectors, respectively. The Dexela detector also presented a higher contrast-to-noise ratios (CNRs) for all different sizes of μCa groups, thus demonstrating overall better eDQE results in imaging performance compared to the Anrad detector.</P>
Joung-Wook Moon,Kwang-Chun Choi,Woo-Young Choi IEEE 2014 IEEE TRANSACTIONS ON CIRCUITS AND SYSTEMS PART 2 E Vol.61 No.5
<P>A 0.4-V phase-locked loop (PLL) that has much improved power efficiency is realized in standard 65-nm CMOS. The PLL employs a novel ultralow-voltage charge pump that compensates current mismatch with an active loop filter and produces significantly reduced reference spurs. Its voltage-controlled oscillator (VCO) is designed with the body-bias technique and includes an automatic frequency calibration circuit that provides low VCO gain and wide tuning range. The PLL output frequency can be tuned from 90 to 350 MHz. At 350-MHz output, the PLL consumes 109 μW, which corresponds to the power efficiency of 0.31 mW/GHz.</P>
Seungyeon Choi,Dong Hoon Lee,Hee-Joung Kim,Young-Wook Choi,Sunghoon Choi 한국물리학회 2020 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.76 No.4
Task-based assessment of image quality using a theoretical observer model has recently gained attention in medical imaging fields. Observer models whose performance can suitably match that of a human observer under various imaging conditions have been considered a key concept for virtual clinical studies. This work focused on experimental study in which a prototype digital breast tomosynthesis (DBT) system, developed by the Korea Electrotechnology Research Institute, was used to compare the task-based Fourier metrics of a detectability index with the performance of human observers. Different angular ranges of ±7°, ±10.5°, ±14°, ±17.5°, ±21°, and ±24.5° were used to detect four different sizes of spheroidal masses with the same 15-projection samplings. A total of 16 human observers participated in the study. Human observer performance was measured using four-alternative forced choice (4AFC) tests for different detection tasks, including detecting spheroidal masses. To determine the task-based detectability index (d´), the non-prewhitening matched filter observer was calculated by analyzing the task function, local spatial resolution, and local noise of spheroidal masses. The percentage of signals correctly detected (Pc) with the 4AFC tests was then compared with the detectability index for tasks presented in 2D slices (d´^2slice). The average Pc for 16 human observers was 0.87 (range = 0.56--1). Results showed that Pc decreased as the angular range increased from ±7° to ±24.5° with different mass sizes. Our result also showed that the performance of the task-based theoretical model observer could reasonably estimate d´ for all inserted lesions of different sizes and acquired under different conditions, while presenting a trend similar to those of the human observers. Consequently, our study is expected to contribute to quantitative imaging performance analysis under various DBT imaging acquisition parameters.
An 8-Gb/s Inductorless Adaptive Passive Equalizer in 0.18- ㎛ CMOS Technology
Joung-Wook Moon,Woo-Young Choi 대한전자공학회 2012 Journal of semiconductor technology and science Vol.12 No.4
This paper presents an inductorless 8-Gb/s adaptive passive equalizer with low-power consumption and small chip area. The equalizer has a tunable RC filter which provides high-frequency gain boosting and a limiting amplifier that restores the signal level from the filter output. It also includes a feedback loop which automatically adjusts the filter gain for the optimal frequency response. The equalizer fabricated in 0.18-㎛ CMOS technology can successfully equalize 8-Gb/s data transmitted through up to 50-㎝ FR4 PCB channels. It consumes 6.75 ㎽ from 1.8-V supply voltage and occupies 0.021 ㎟ of chip area.
Analysis of Uterine Bacteria to Increase Reproductive Efficiency in Hanwoo(Korean Native Cattle)
Joung-Jun Park,Han-Jun Yoo,Young-Jae Cho,Hye-Won Choi,Pil-Sang Yoon,Seon-Goo Lee,Bae-Dong Jung,Tae-Wook Hahn 韓國受精卵移植學會 2013 한국동물생명공학회지 Vol.28 No.1
The objective of this study was to evaluate several types of uterine bacteria in Hanwoo. uterine bacteria from randomly selected 5 uterus was collected by flushing methods into a sterilized 1.5 ml centrifuge tube and was inoculated onto MacConkey agar and blood agar, respectively. After being incubated for 5% CO2, aerobic or anaerobic condition at 37℃ during 48h, bacterial colonies were selected and re-inoculated onto blood agar plates. Re-cultured colonies were identified by Gram staining and finally identified using Vitek system. The identified bacteria were Staphylococcus lentus, Staphylococcus sciuri, Staphylococcus vitulinus, Staphylococcus warneri of Gram (+) and Rhizobium radiobacter, Sphingomonas paucimobilis of Gram () bacteria. Although, pathogenicity of identified bacteria was unclear, the bacteria can have an effect on the uterine microenvironment. Therefore, repetitive research will be required to determine the effects of bacteria in cattle exposed to a various environment.
Gestational weight gain is an important risk factor for excessive fetal growth
( Joung Min Lee ),( Min Jung Kim ),( Moon Young Kim ),( Jung Yeol Han ),( Hyun Kyeong Ahn ),( June Seek Choi ),( Jin Hoon Chung ),( Si Won Lee ),( You Jung Han ),( Dong Wook Kwak ),( Hyun Mee Ryu ),( 대한산부인과학회 2014 Obstetrics & Gynecology Science Vol.57 No.6
ObjectiveTo estimate the odds ratio of prepregnant body mass index (BMI), gestational weight gain (GWG), and gestational diabetes mellitus (GDM) for excessive fetal growth, which we define as large for gestational age (LGA). MethodsWe included 16,297 women who delivered a live-born singleton baby at term. We fit logistic regressions to estimate the odds ratios of variables, including maternal age, parity, prepregnant BMI ≥23, GWG ≥15 kg, and GDM, for LGA. We classified GWG into four categories (<10, 10-14.9, 15-19.9, and ≥20 kg) and BMI into four categories (underweight, normal, overweight, and obese). After adjusting for age and parity, we analyzed the odds ratios of prepregnant BMI according to GWG between non-GDM and GDM women for LGA. ResultsThe odds ratios of GWG ≥15 kg and prepregnancy BMI ≥23 for LGA were 2.40 (95% confidence interval [CI], 2.16-2.67) and 2.24 (95% CI, 1.99-2.51), respectively. The odd ratio of GDM was 1.37 (95% CI, 1.09-1.71). The risk of GDM women with normal/-overweight BMI and GWG <15 kg for LGA was not significantly greater than those of the reference group. The odd ratios of GDM women with overweight/obese BMI and GWG 15 to 19.9 kg were 3.95 (95% CI, 1.26-12.38) and 9.70 (95% CI, 3.79-24.87), respectively. ConclusionGWG ≥15 kg might be a more important risk factor for LGA than either prepregnancy BMI ≥23 or GDM. Risk for LGA was highest in obese GDM women with GWG ≥15 kg.
Byung Wook Jo,Ye Jee Shim,Jin Hyeok Choi,Jun Sik Kim,Hee Joung Lee,Heung Sik Kim 대한소아내분비학회 2015 Annals of Pediatirc Endocrinology & Metabolism Vol.20 No.2
Vitamin D deficient rickets is generally known to occur in breast fed infants. And excessive phosphate ingestion is a main cause of late onset hypocalcemia in formula fed infants. Here we introduce 45-day-old formula fed hypocalcemic twins with recurrent seizure attacks. They were diagnosed as having both of vitamin D deficient rickets and hyperphosphatemia. Radiologic findings indicated mild rickets and the twins were treated with calcium and alfacalcidol. After 3–5 months of oral supplementation, medication was discontinued in both twins. They showed normal growth and calcium, phosphorus, and vitamin D levels during the 6-month follow-up period. Twins can be at risk for hypocalcemia because of their high risk of vitamin D deficiency, low birth weight, and premature birth. Therefore twin pregnant women need ingestion of sufficient vitamin D and calcium.