• Title/Summary/Keyword: UsN

Search Result 761, Processing Time 0.033 seconds

A novel IGBT with improved electrical characteristics (향상된 전기적 특성을 갖는 IGBT에 관한 연구)

  • Koo, Yong-so
    • The Journal of Korea Institute of Information, Electronics, and Communication Technology
    • /
    • v.6 no.3
    • /
    • pp.168-173
    • /
    • 2013
  • In this paper, we tried different two approach to improve the performance of the IGBT. The first approach is that adding N+ region beside P-base in the conventional IGBT. It can make the conventional IGBT to get faster turn-off time and lower conduction loss. The second approach is that adding P+ region on right side under gate to improve latching current of conventional IGBT. The device simulation results show improved on-state, latch-up and switching characteristics in each structure. The first one was presented lower voltage drop(3.08V) and faster turn-off time(3.4us) than that of conventional one(3.66V/3.65us). Also, second structure has higher latching current(369A/?? ) that of conventional structure. Finally, we present a novel IGBT combined the first approach with second one for improved trade-off characteristic between conduction and turn-off losses. The proposed device has better performance than conventional IGBT.

Comparison of Combined Therapy Using Conventional Chemoembolization and Radiofrequency Ablation Versus Conventional Chemoembolization for Ultrasound-Invisible Early-Stage Hepatocellular Carcinoma (Barcelona Clinic Liver Cancer Stage 0 or A)

  • Lee, Hyukjoon;Yoon, Chang Jin;Seong, Nak Jong;Jeong, Sook-Hyang;Kim, Jin-Wook
    • Korean Journal of Radiology
    • /
    • v.19 no.6
    • /
    • pp.1130-1139
    • /
    • 2018
  • Objective: To compare the therapeutic efficacy between conventional transarterial chemoembolization (cTACE) and combined therapy using cTACE and radiofrequency ablation (RFA) in ultrasound (US)-invisible early stage hepatocellular carcinoma (HCC). Materials and Methods: From January 2008 to June 2016, 167 patients with US-invisible early stage HCCs were treated with cTACE alone (cTACE group; n = 85) or cTACE followed by immediate fluoroscopy-guided RFA targeting intratumoral iodized oil retention (combined group; n = 82). Procedure-related complications, local tumor progression (LTP), time to progression (TTP), and overall survival (OS) were compared between the two groups. Multivariate analyses were performed to identify prognostic factors. Results: There was no major complication in either group. The cTACE group showed higher 1-, 3-, and 5-year LTP rates than the combined group; i.e., 12.5%, 31.7%, and 37.0%, respectively, in the cTACE group; compared to 7.3%, 16.5%, and 16.5%, respectively, in the combined group; p = 0.013. The median TTP was 18 months in the cTACE group and 24 months in the combined group (p = 0.037). Cumulative 1-, 3-, and 5-year OS rates were 100%, 93.2%, and 87.7%, respectively, in the cTACE group and 100%, 96.6%, and 87.4%, respectively, in the combined group (p = 0.686). Tumor diameter > 20 mm and cTACE monotherapy were independent risk factors for LTP and TTP. Conclusion: Combined therapy using cTACE followed by fluoroscopy-guided RFA is a safe and effective treatment in US-invisible early stage HCCs. It provides less LTP and longer TTP than cTACE alone.

Neutron activation analysis: Modelling studies to improve the neutron flux of Americium-Beryllium source

  • Didi, Abdessamad;Dadouch, Ahmed;Jai, Otman;Tajmouati, Jaouad;Bekkouri, Hassane El
    • Nuclear Engineering and Technology
    • /
    • v.49 no.4
    • /
    • pp.787-791
    • /
    • 2017
  • Americium-beryllium (Am-Be; n, ${\gamma}$) is a neutron emitting source used in various research fields such as chemistry, physics, geology, archaeology, medicine, and environmental monitoring, as well as in the forensic sciences. It is a mobile source of neutron activity (20 Ci), yielding a small thermal neutron flux that is water moderated. The aim of this study is to develop a model to increase the neutron thermal flux of a source such as Am-Be. This study achieved multiple advantageous results: primarily, it will help us perform neutron activation analysis. Next, it will give us the opportunity to produce radio-elements with short half-lives. Am-Be single and multisource (5 sources) experiments were performed within an irradiation facility with a paraffin moderator. The resulting models mainly increase the thermal neutron flux compared to the traditional method with water moderator.

Framing advocacy event: Comparing news coverage and Facebook comments of the Belt and Road Forum in Pakistan and the USA

  • Xu, Yi
    • Journal of Contemporary Eastern Asia
    • /
    • v.20 no.1
    • /
    • pp.1-23
    • /
    • 2021
  • With regard to the recent developments in public diplomacy, the increasing fusion of strategic communication appears necessary. China engages in public diplomacy with a strategic purpose to shape its national image abroad. Hosting diplomatic advocacy event is regarded as an instrument with expectations to present reliable and responsible image and promote international collaborations. The present research focuses on the Belt and Road Forum (BRF) in May 2017 with the objective to analyze its outcomes and influence on the international news agenda, news frames, and foreign citizens' comments online. The quantitative content analyses are used to compare the media reports (N=364) and Facebook users' comments on the selected news (N=957) between the US and Pakistan. Results reveal that Pakistani media provided more diverse frames and attributed more positive evaluations to the BRF than the US media. However, Facebook comments expressed more unfavorable opinions toward the BRF and China's image with rare differences between two countries. In conclusion, the BRF has served as an eye-catching advocacy of Chinese foreign policy, as it influenced the news agenda in two selected countries. However, news frames vary due to the differences in media system and the involvement in the BRF. China's public diplomacy practices follow a traditional top-down communication which needs meticulous subdivision of target stakeholders, delicate messaging strategies, and integrated tactics.

Sensing Nitrate and Potassium Ions in Soil Extracts Using Ion-Selective Electrodes (이온선택성 전극을 이용한 토양추출물의 질산 및 칼륨이온 측정)

  • Kim, H.J.;Sudduth Kenneth A.;Hummel John W.
    • Journal of Biosystems Engineering
    • /
    • v.31 no.6 s.119
    • /
    • pp.463-473
    • /
    • 2006
  • Automated sensing of soil macronutrients would allow more efficient mapping of soil nutrient spatial variability for variable-rate nutrient management. The capabilities of ion-selective electrodes for sensing macronutrients in soil extracts can be affected by the presence of other ions in the soil itself as well as by high concentrations of ions in soil extractants. Adoption of automated, on-the-go sensing of soil nutrients would be enhanced if a single extracting solution could be used for the concurrent extraction of multiple soil macronutrients. This paper reports on the ability of the Kelowna extractant to extract macronutrients (N, P, and K) from US Corn Belt soils and whether previously developed PVC-based nitrate and potassium ion-selective electrodes could determine the nitrate and potassium concentrations in soil extracts obtained using the Kelowna extractant. The extraction efficiencies of nitrate-N and phosphorus obtained with the Kelowna solution for seven US Corn Belt soils were comparable to those obtained with IM KCI and Mehlich III solutions when measured with automated ion and ICP analyzers, respectively. However, the potassium levels extracted with the Kelowna extractant were, on average, 42% less than those obtained with the Mehlich III solution. Nevertheless, it was expected that Kelowna could extract proportional amounts of potassium ion due to a strong linear relationship ($r^2$ = 0.96). Use of the PVC-based nitrate and potassium ion-selective electrodes proved to be feasible in measuring nitrate-N and potassium ions in Kelowna - soil extracts with almost 1 : 1 relationships and high coefficients of determination ($r^2$ > 0.9) between the levels of nitrate-N and potassium obtained with the ion-selective electrodes and standard analytical instruments.

The Effect of Continuous Ultrasound Therapy and Pulsed Ultrasound Therapy on Adjuvant Induced Rheumatoid Arthritis in Rat (지속적인 초음파치료와 맥동 초음파치료가 Adjuvant로 유도된 흰쥐의 관절염에 미치는 효과)

  • Lee, Byeung-Ok;Min, Kyung-Ok;Hong, Wan-Seng;Lee, Kyung-Moo;Hwang, Seock-Yeon
    • Journal of Korean Physical Therapy Science
    • /
    • v.9 no.4
    • /
    • pp.7-14
    • /
    • 2002
  • The drug therapy for rheumatoid arthritis must be maintained constantly or for the whole life but is apt to induce the adverse effects in gastrointestinal or renal system. Therefor, newer methods are paid attention to reduce adverse effects. The thirty-two rat female separated into seven groups depending on the therapy or Freund's adjuvant applied: Normal group(n=8) not received anything, Positive control group(n=8) only received adjuvant, USC group(n=8) received continuous US, USP group(n=8) received pulsed US. The physical and radiological findings by thermal and non-thermal effects of ultrasound were evaluated in groups with continuous mode at 1 MHz, $0.5\;W/cm^2$ for 6 minutes and with pulsed mode (duty cycle 1:9) at 1 MHz, $0.5\;W/cm^2$ for 6 minutes. The result summarized followings. 1. Swelling of forepaw and hindpaw was significantly reduced in USP. 2. Arthritis indices in USP group were significantly reduced than those in PCG. 3. In naked eye and radiologic findings, swelling was significantly prevented in USP group but not in PCG. The change of swelling, arthritis index, gross feature in naked eye, radiologic finding were significantly improved in all groups except for USC group, taking care for using its continuous mode.

  • PDF

sanN Encoding a Dehydrogenase is Essential for Nikkomycin Biosynthesis in Streptomyces ansochromogenes

  • Ling, Hong-Bo;Wang, Guo-Jun;Li, Jin-E;Tan, Hua-Rong
    • Journal of Microbiology and Biotechnology
    • /
    • v.18 no.3
    • /
    • pp.397-403
    • /
    • 2008
  • Nikkomycins are a group of peptidyl nucleoside antibiotics with potent fungicidal, insecticidal, and acaricidal activities. sanN was cloned from the partial genomic library of Streptomyces ansochromogenes 7100. Gene disruption and complementation analysis demonstrated that sanN is essential for nikkomycin biosynthesis in S. ansochromogenes. Primer extension assay indicated that sanN is transcribed from two promoters (sanN-P1 and sanN-P2), and sanN-P2 plays a more important role in nikkomycin biosynthesis. Purified recombinant SanN acts as a dehydrogenase to convert benzoate-CoA to benzaldehyde in a random-order mechanism in vitro, with respective $K_{cat}/K_m$$ values of $3.8mM^{-1}s^{-1}\;and\;12.0mM^{-1}s^{-1}$ toward benzoate-CoA and NADH, suggesting that SanN catalyzes the formation of picolinaldehyde during biosynthesis of nikkomycin X and Z components in the wild-type stain. These data would facilitate us to understand the biosynthetic pathway of nikkomycins and to consider the combinatorial synthesis of novel antibiotic derivatives.

Magnetic Field Structure and Formation Scenario of the N159/N160 Star-Forming Complex in the Large Magellanic Cloud

  • Kim, Jaeyeong;Jeong, Woong-Seob;Pyo, Jeonghyun;Pak, Soojong;Park, Won-Kee;Kwon, Jungmi;Tamura, Motohide
    • The Bulletin of The Korean Astronomical Society
    • /
    • v.42 no.1
    • /
    • pp.38.3-39
    • /
    • 2017
  • The N159 and N160 ionized regions in the Large Magellanic Cloud are an important extragalactic star-forming complex. The physical environments and the star formation stages are different in N159 and N160. We performed near-infrared polarimetry to those star forming regions with IRSF/SIRPOL 1.4-m telescope. Near-infrared polarization enabled us to trace the detailed structure of magnetic fields in star-forming regions. Through the polarimetric data of J, H, and Ks bands, we examined the magnetic field structures in the N159/N160 complex. In this presentation, we show complex distribution of the magnetic fields associated with dust and gas structures. We verify the local magnetic fields in each star-forming region, which appear to be related with local environments, such as interior and boundary of shell structure, star-forming HII regions, and boundaries between HII regions and dense dark clouds. We discuss the formation scenario of the N159/N160 complex suggested from the magnetic field structure.

  • PDF

Suprapubic Bladder Aspiration Assisted by Ultrasound (초음파 보조하에 시행한 치골상부 방광천자의 유용성)

  • Lee Jung Won;Park Soeun;Cho Su Jin;Yoo Eun Sun;Kim Hae Soon;Lee Seoung Joo
    • Childhood Kidney Diseases
    • /
    • v.6 no.1
    • /
    • pp.68-74
    • /
    • 2002
  • Purpose: Suprapubic bladder aspiration(SBA) of urine is the most reliable method to obtain urine avoiding contamination in non-toilet trained infants. Ultrasonography is a useful tool for guiding the anatomic location as well as for direct visualization during procedure. We evaluated the success rate and complication of ultrasound(US) assisted SBA Methods. Sixty infants who visited Ewha Womans University Mokdong Hospital, with suspected urinary tract infection were randomly divided into the US assisted (n=32) and blind SBA(control, n=28) group. In US assisted SBA group, the anteroposterior(AP), transverse, and sagittal diameters and the volume of the bladder were measured. In the blind SBA group, urine was blindly aspirated when the urinary bladder was palpated at the suprapubic area. The rate of successful urine aspiration, the number of attempts until successful aspiration, aspirated urine volume were compared between the two groups. Results: The success rate was $100\%$(32/32) in the US assisted group, which was significantly higher than $85.7\%$(24/28) of the control group (P<0.05). The aspirated urine volume in the US assisted group was $7.4{\pm}3.7\;mL$, which was significantly higher than $4.5{\pm}3.4\;mL$ of the control group (P<0.05), The diameters and volume of bladder in successful aspiration were $2.1{\pm}0.7\;cm$ in AP diameter, $3.1{\pm}0.6\;cm$ in transverse diameter, $4.2{\pm}1.0\;cm$ in sagittal diameter and $15.2{\pm}10.4\;mL$ in volume, which were significantly higher than those ($1.7{\pm}0.3\;cm,\;1.7{\pm}0.3\;cm,\;1.8{\pm}0.7\;cm,\;2.4{\pm]0.6\;cm,\;3.9{\pm}2.5$) of the control group (P<0.05) The correlations between the AP(r=0.78), transverse (r=0.72), sagittal(r=0.91) diameter and bladder volume were significant (P<0.05). SBA was $100\%$ successful in the AP diameter >3 cm, transverse diameter >4 cm, depth >4 cm and bladder volume >5 mL. Conclusion: US assistance can significantly improve the success rate of SBA in infant with suspected urinary tract infection. (J Korean Soc Pediatr Nephrol 2002 ; 6 : 68-74)

  • PDF

Some Dependence Structures of Multivariate Processes

  • Jong Il Baek
    • Communications for Statistical Applications and Methods
    • /
    • v.2 no.1
    • /
    • pp.201-208
    • /
    • 1995
  • In the last years there has been growing interest in concepts of positive dependence for families of random variables such that concepts are considerable us in deriving inequalities in probability and statistics. Lehman introdued various concepts of positive dependence for bivariate random variables. A much stronger notions of positive dependence were later considered by Esary, Proschan, and Walkup. Ahmed et al and Ebrahimi and Ghosh also obtained multivariate versions of various bivariate positive dependence as descrived by Lehman. See also Block al. Glaz and Johnson an Barlow and Proschan and the references there. Multivariate processes arise when instead of observing a single process we observe several processes, say $X_19t), \cdots, X_n(t)$ simultaneously. For example, in an engineering context we may want to study the simultaneous variation of current and voltage, or temperature, pressure and volume over time. In economics we may be interested in studying inflation rates and money supply, unemployment and interest rates. We could of course, study each quantity on its own and treat each as a separate univariate process. Although this would give us some information about each quantity it could never give information about the interrelationship between various quantities. This leads us to introduce some concepts of positive and for multivariate stochastic processes. The concepts of positive dependence have subsequently been extended to stochastic processes in different directions by many authors.

  • PDF