• 한국의학물리학회지:의학물리
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• 제23권1호
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• pp.26-32
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• 2012

확대촬영은 일반촬영뿐 아니라 미세골촬영, 유방촬영 및 다른 진단 영역에서 널리 사용되고 있다. 유한한 X선 초점의 크기로 인해 확대촬영은 분해능, 노이즈, 대조도 등 영상 시스템 전체에 영향을 미친다. 본 연구의 목적은 유효검출양자효율(effective detective quantum efficiency, eDQE)을 이용하여 영상시스템에 있어서 확대도와 초점크기의 영향을 알아보고자 함이다. 전체적인 영상 시스템 특성을 반영하는 eDQE는 초점에 의한 흐림 현상, 확대, 산란 그리고 격자 반응 등의 영향을 고려한다. 본 실험에서는 Food and Drug Administration (FDA)에서 고안된 흉부 팬텀을 사용하여 실제 가슴 촬영조건에서 측정된 유효변조전달함수(effective modulation transfer function, eMTF), 유효잡음력스펙트럼(effective noise power spectrum, eNPS), 산란율(scatter fraction, SF) 및 투과율(transmission fraction, TF)을 통해 eDQE 값을 도출하였다. 연구 결과를 통해 살펴보면 소초점을 사용했을 경우, eMTF의 값이 10%일 때의 공간주파수는 확대도가 1.2, 1.4, 1.6, 1.8, 2.0일때 각각 2.76, 2.21, 1.78, 1.49 그리고 1.26 lp/mm이었다. 대초점을 사용했을 경우, MTF의 값이 10%일 때의 공간주파수는 확대도가 1.2, 1.4, 1.6, 1.8, 2.0일 때 각각 2.21, 1.66, 1.25, 0.93 그리고 0.73 lp/mm이었다. 확대도가 증가할수록 eMTF 값이 떨어지고, 소초점을 사용했을 때가 대초점을 사용했을 때보다 eMTF가 전체적으로 높다는 것을 확인할 수 있었다. 초점의 크기에 따른 zero frequency에서의 eDQE 값의 변화는 크게 보이지 않았다. 그러나 대초점을 사용했을 경우, 소초점을 사용했을 때보다 저 주파수에서 고 주파수로 갈수록 eDQE가 급격하게 감소하는 것을 확인할 수 있었다. 일반적으로 확대촬영은 작은 병변을 확대시키고 낮은 유효잡음과 air-gap에 의한 산란선의 감소로 인해 대조도를 증가시킨다. 이로 인해 크기가 작은 병변을 고대조도로 확대시킴으로써 진단율을 높일 수 있다. 그러나 초점 크기로 인한 흐림 현상이 확대도에 따라 공간 분해능에 더 큰 영향을 미친다. 이러한 결과를 바탕으로, 디지털 일반촬영 시스템에서의 확대촬영을 시행하기 위한 적절한 초점크기와 확대도가 확립되어야 한다.

• Journal of Electrical Engineering and Technology
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• 제9권2호
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• pp.569-575
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• 2014

A highly efficient class E power amplifier is demonstrated for application to wireless power transfer system. The amplifier is designed with an L-type matching at the output for harmonic rejection and output matching. The power loss and the effect of each component in the amplifier with the matching circuit are analyzed with the current ratio transmitted to the output load. Inductors with a quality factor of more than 120 are used in a dc feed and the matching circuit to improve transmission efficiency. The single-ended amplifier with 20 V supply voltage shows 7.7 W output power and 90.8% power added efficiency at 6.78 MHz. The wireless power transfer (WPT) system with the amplifier shows 5.4 W transmitted power and 82.3% overall efficiency. The analysis and measurements show that high-Q inductors are required for the amplifier design to realize highly efficient WPT system.

• Journal of Mechanical Science and Technology
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• 제16권4호
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• pp.549-556
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• 2002

An investigation on the fully developed heat transfer and friction factor characteristics has been made in rectangular ducts with one-side roughened by five different shapes. The effects of rib shape geometries as well as Reynolds numbers are examined. The rib height-to-duct hydraulic diameter, pitch-to-height ratio, and aspect ratio of channel width to height are fixed at e/De=0.0476, P/e=8, and W/H=2.33, respectively. To understand the characteristics of heat transfer enhancements, the friction factors are also measured. The data indicates that the triangular type rib has a substantially higher heat transfer performance than any other ones.

• Journal of Microbiology and Biotechnology
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• 제30권7호
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• pp.974-981
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• 2020

Sequence type 410 (ST410) of Escherichia coli is an extraintestinal pathogen associated with multi drug resistance. In this study, we aimed to investigate the horizontal propagation pathway of a high-risk clone of E. coli ST410 that produces Klebsiella pneumoniae carbapenemase (KPC). blaKPC-encoding E. coli and K. pneumoniae isolates were evaluated, and complete sequencing and comparative analysis of blaKPC-encoding plasmids from E. coli and K. pneumoniae, antimicrobial susceptibility tests, polymerase chain reaction, multilocus sequence typing, and conjugal transfer of plasmids were performed. Whole-genome sequencing was performed for plasmids mediating KPC-2 production in E. coli and K. pneumoniae clinical isolates. Strains E. coli CPEc171209 and K. pneumoniae CPKp171210 were identified as ST410 and ST307, respectively. CPEc171209 harbored five plasmids belonging to serotype O8:H21, which is in the antimicrobial-resistant clade C4/H24. The CPKp171210 isolate harbored three plasmids. Both strains harbored various additional antimicrobial resistance genes. The IncX3 plasmid pECBHS_9_5 harbored blaKPC-2 within a truncated Tn4401a transposon, which also contains blaSHV-182 with duplicated conjugative elements. This plasmid displayed 100% identity with the IncX3 plasmid pKPBHS_10_3 from the K. pneumoniae CPKp171210 ST307 strain. The genes responsible for the conjugal transfer of the IncX3 plasmid included tra/trb clusters and pil genes coding the type IV pilus. ST410 can be transmitted between patients, posing an elevated risk in clinical settings. The emergence of a KPC-producing E. coli strain (ST410) is concerning because the blaKPC-2-bearing plasmids may carry treatment resistance across species barriers. Transgenic translocation occurs among carbapenem-resistant bacteria, which may spread rapidly via horizontal migration.

• 한국수정란이식학회지
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• 제31권1호
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• pp.13-17
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• 2016

The purpose of this study was to examine the effects of taurine and vitamin E on sperm characteristics damaged by bromopropane (BP) in pig. We evaluated toxicity of BP on viability, membrane integrity and mitochondrial activity of spermatozoa. 1-BP (0, 2.5, 5.0, 10, and $50{\mu}M$), 2-BP (0, 2.5, 5.0, 10, and $50{\mu}M$), taurine (0, 5.0, 10, and $25{\mu}M$) and vitamin E (0, 50, 100, and $200{\mu}M$) were treated in fresh boar semen for 6 h. 10 and $50{\mu}M$ of 1-BP and 2-BP inhibited sperm viability, membrane integrity and mitochondrial activity in fresh boar semen (P<0.05). $25{\mu}M$ of taurine increased sperm viability and membrane integrity (P<0.05), $100{\mu}M$ of vitamin E enhanced viability and mitochondrial activity of sperm (P<0.05). Finally, $10{\mu}M$ of 1-BP and 2-BP was co-treated with taurine ($25{\mu}M$) and vitamin E ($100{\mu}M$) in the fresh boar semen. The co-treated samples did affected viability, membrane integrity and mitochondrial activity of sperm. In conclusion, taurine and vitamin E can improve and maintain sperm quality in fresh boar semen.

• 한국대기환경학회지
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• 제15권4호
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• pp.475-483
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• 1999

A lab-scale test was carried out to study the reduction of electrical energy consumption in the pulsed corona discharge process for nitrogen oxides removal. The experiment was mainly focused on 1) the activation of pollution removal reactions by chemical additives and 2) the optimization of electrical circuit for the efficient energy transfer from the power supply to the corona reactor. Hydrocarbon chemical additives used in the experiment are thought to be responsible for the enhancement of the NO conversion through the chain reactions of free radicals such as, R, RCO, and RO. Electrical energy consumption per converted NO molecule has a minimum value of 17 eV when pentanol is injected. When ethylene and propylene are injected, 30 eV and 22 eV of electrical energy consumption is required for the conversion of NO molecule respectively. The ratio of the pulse forming capacitance$(C_e)$ to the reactor capacitance$(C_R)$ plays an important role in the energy transfer efficiency to the reactor. Maximum energy transfer efficiency of approximately 72% could be obtained by using the pulse forming capacitance which is 3.4 times larger than the reactor capacitance, and also the maximum NO conversion efficiency was observed with the same condition.

• 한국IT서비스학회지
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• 제10권2호
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• pp.259-269
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• 2011

The B$\'{e}$k$\'{e}$sy audiometer is used to determine not only hearing threshold but also assumption of recruit phenomenon and cause of disease. However, current B$\'{e}$k$\'{e}$sy audiometer takes an operational model, so called face-to-face model, in which model one audiometrist can assess only one subject at a time. As a result, the face-to-face model leads to high audiometrist's labor cost and long waiting time when there exist many subjects. To improve such weakness, this paper extends PC based B$\'{e}$k$\'{e}$sy audiometer to support client/server model in which model one audiometrist enables to concurrently access several subjects. As providing capabilities such as real-time transfer of assessment result, video monitoring of subject and video chat, the same effect as face-to-face model but overcomes weakness of face-to-face model.

• 동력기계공학회지
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• 제18권2호
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• pp.12-18
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• 2014

The local heat transfer of developed turbulent flows in the stationary ribbed rectangular convergent channels has been investigated experimentally. The rectangular convergent channels with one ribbed surface only have the inclination of $0.72^{\circ}$ and $1.43^{\circ}$ at which the ribbed wall is manufactured with a fixed rib height (e) of 10 mm and the ratio of rib spacing (p) to height (e) =10. The measurement was conducted within the range of Reynolds numbers from 15,000 to 89,000. The local heat transfer characteristics of the rectangular convergent channels are quite different from those of the ribbed square straight channel.

• Design & Manufacturing
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• 제2권3호
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• pp.51-57
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• 2008

It is important factor to design the strip layout drawing according to product properties in press die design. Press dies are important processes in production such as a car component, house electronics, computer parts etc. In this paper, the strip layout of parts was designed for transfer dies. Results of this study can be modify the punch, trim position and notching shapes of strip layout. Utilization ratio was 70.3% by conducting piercing and notching for scrap design and materials were arranged with wide width of blank layout.

• 한국어병학회지
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• 제32권2호
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• pp.97-104
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• 2019

본 연구에서는 2017년 4월부터 12월 사이에 여수수산시장에서 구입한 수산물로부터 분리된 Vibrio parahaemolyticus와 Morganella morganii의 내성특성을 알아보고 장내세균인 Escherichia coli와 어류 병원균인 Edwardsiella tarda와의 내성전이 가능성을 알아보았다. Broth mating 법으로 실시한 conjugation에서 형성된 transconjugants를 분리하기 위하여 ampicillin(AMP) 50 ㎍/ml와 streptomycin (SM) 150 ㎍/ml 또는 oxytetracycline(OT) 30 ㎍/ml이 첨가된 TSA배지를 사용하였다. AMP, amoxicillin (AML), colistin(CT)에 낮은 감수성을 보였던 V. parahaemolyticus와 달리 M. morganii는 AMP, AML, CT, erythromycin, OT, tetracyclin등에 감수성이 낮았다. V. parahaemolyticus와 M. morganii를 E. coli와 conjugation을 실시한 결과 transconjugants인 E. coli는 분리되지 않은 반면 SM내성을 획득한 V. parahaemolyticus와 M. morganii가 분리되었다. 한편 V. parahaemolyticus와 E. tarda의 broth mating에서는 AMP와 AML 내성을 획득한 E. tarda transconjugant가 분리되었다. 그러나 V. parahaemolyticus의 β-lactamase 유전자인 VPA 0477의 전이는 확인되지 않았으며, E. tarda의 내성이 전달된 V. parahaemolyticus나 M. morganii는 검출되지 않았다. 이와 같은 결과는 생물 위해성 세균들 간의 내성전이가 양방향성이며 매우 다양한 패턴으로 진행되고 있음을 시사한다.