• Proceedings of the Korean Society of Veterinary Clinics Conference
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• 2009.10a
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• pp.240-240
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• 2009

• Journal of the Korea Academia-Industrial cooperation Society
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• v.11 no.11
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• pp.4411-4417
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• 2010

This study was retrospectively to compare the exposure dose and the imaging quality in coronary CT angiography by using the 64 channel multidetector computed tomography and the 128 channel DSCT. Effective dose was calculated dose length product (DLP) by multiplied the convention factor of chest (0.017). Imaging quality was assessed by radiologists using the 5-point Likert scale. The DLP was ranged from 851 to $1277mGy{\cdot}cm$ (mean: 17.23 mSv) in the 64 channel MDCT and from 82 to $110mGy{\cdot}cm$ (mean: 1.58 mSv) in the of 128 channel DSCT, respectively. The score of imaging quality was respectively $3.31{\pm}0.62$ in 64 channel MDCT and $4.05{\pm}0.46$ in the 128 channel DSCT. The exposure dose of 128 channel DSCT has decreased 1ess 1/10. The score of imaging quality was significant difference between two modalities and the frequency (>4 good) in the 128 channel DSCT is about three times than that of the 64 channel MDCT. Therefore, the 128 channel DSCT in coronary CT angiography is clinically more effective modality for both investigators and patients.

• Proceedings of the Korea Society for Simulation Conference
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• 2001.05a
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• pp.133-133
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• 2001

무선 근거리 지역망(Wireless LAN;WLAN) 환경에서 다중 채널을 이용하여 실시간 서비스를 제공하기 위한 매체 접근제어 계층에서의 채널의 사용 구간 할당 방법을 제안하고, 컴퓨터 모의 실험을 통하여 제한된 방식의 실시간 서비스 지원 성능과 채널의 사용 효율을 분석한다. 제안한 채널 사용 구간 할당 방안은 개선된 매체 접근 제어 프로토콜 RICH-DP (Receiver-Initiated Channel-Hopping with Dual Polling)를 바탕으로 한다. 무선 환경에서 RTS-CTS를 사용하는 프로토콜은 SRMA, MACA, MACAW, IEEE 802.11, FAMA 등이 있다. 최근에 단일 채널을 환경에서 RICH(Receiver Initiated Channel-Mopping) 프로토콜이 제안되었다. RICH는 충돌 회피를 위해서 경쟁 구간에서 충돌 감지(carrier sensing)을 사용한다. RICH는 제한된 어플케이션에 국한되는 단절이 있다. 반면에 RICH-DP는 다중 채널 환경에서 충돌 감지와 특별한 코드(spreading code) 할당 없이 일반화된 충돌 회피를 제공한다. 실시간 서비스를 이용하자 차는 단말들로 하여금 RICH-DP를 사용하여 서비스를 제공할 때, 대역폭에 대한 정보를 AP(Access Point)로 전송토록 함으로써 비경쟁 구간에서 뿐 아니라, 경쟁구간에서도 높은 채널 효율이 얻어질 수 있도록 하고 있다. 제한된 방안의 성능 평가를 위한 모의 실험은 OPNET를 이용하여 실시간 서비스 데이터를 7개의 상태 천이를 갖는 VBR 소스로 모델링하고 비동기 트래픽들은 Poisson 소스로 모델링하여 실시간 서비스 단발들의 이용 대역폭과 채널 처리율과 시스템 지연시간을 성능 평가 인자로 하여 수행하였다. 논문에서 제한된 방법을 적용한 개선된 RICH-DP을 모의 실험을 통하여 분석한 결과 기존의 제한된 RICH-DP는 실시간 서비스에 대한 처리율이 낮아지며 서비스 시간이 보장되지 못했다. 따라서 실시간 서비스에 대한 새로운 제안된 기법을 제안하고 성능 평가한 결과 기존의 RICH-DP보다 성능이 향상됨을 확인 할 수 있었다.

• Nuclear Medicine and Molecular Imaging
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• v.42 no.1
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• pp.77-78
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• 2008

A 71-year-old woman was assigned to our department for Tc-99m myocardial perfusion SPECT(MPS) and coronary CT angiography. She admitted for substernal pain, via the ER, 2 days ago. The heart was scanned after intravenous injection of 925 MBq of $^{99m}Tc$-sestamibi adenosine-induced stress SPECT using dual head gamma camera (Hawkeye, GE healthcare. USA). The MPS shows decreased tracer uptake in the apical & mid area of anterior & lateral wall and mid & basal inferior wall. Coronary CT angiograph was obtained using Discovery VCT (GE healthcare). 3D angiography portrayed significant stenosis of ramus intermedius(RI) and posterolateral branch of right coronary artery(PLB) with fibrocalcified plaque. Two images were fused using Cardiac IQ fusion softwear package (Advantage workstation 4.4, GE healthcare) The fusion images explain the perfusion defect of anterior, lateral and inferior wall is due to stenosis of the RI and PLB. And 3 days later, coronary angiography was done and revealed the marked stenosis of RI and PLB. Then balloon angioplasty and stent was instituted in RI. Cardiac SPECT/CT fusion imaging provides additional information about hemodynamic relevance and facilitates lesion interpretation by allowing exact allocation of perfusion defects to its subtending coronary artery.

• The Korean Journal of Physiology and Pharmacology
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• v.24 no.6
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• pp.555-561
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• 2020

TWIK-related two-pore domain K⁺ channel-2 (TREK-2) has voltage-independent activity and shows additional activation by acidic intracellular pH (pH_i) via neutralizing the E³³² in the cytoplasmic C terminal (Ct). We reported opposite regulations of TREK-2 by phosphatidylinositol 4,5-bisphosphate (PIP₂) via the alkaline K³³⁰ and triple Arg residues (R^355-357); inhibition and activation, respectively. The G³³⁴ between them appeared critical because its mutation (G³³⁴A) endowed hTREK-2 with tonic activity, similar to the mutation of the inhibitory K³³⁰ (K³³⁰A). To further elucidate the role of putative bent conformation at G³³⁴, we compared the dual mutation forms, K³³⁰A/G³³⁴A and G³³⁴A/R^355-7A, showing higher and lower basal activity, respectively. The results suggested that the tonic activity of G³³⁴A owes to a dominant influence from R^355-7. Since there are additional triple Arg residues (R^377-9) distal to R^355-7, we also examined the triple mutant (G³³⁴A/R^355-7A/R^377-9A) that showed tonic inhibition same with G³³⁴A/R^355-7A. Despite the state of tonic inhibition, the activation by acidic pH_i was preserved in both G³³⁴A/R^355-7A and G³³⁴A/R^355-7A/R^377-9A, similar to the R^355-7A. Also, the inhibitory effect of ATP could be commonly demonstrated under the activation by acidic pH_i in R^355-7A, G³³⁴A/R^355-7A, and G³³⁴A/R^355-7A/R^377-9A. These results suggest that the putative bent conformation at G³³⁴ is important to set the tug-of-war between K³³⁰ and R^355-7 in the PIP₂-dependent regulation of TREK-2.