• 대한방사선기술학회지:방사선기술과학
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• 제38권4호
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• pp.443-449
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• 2015

초음파 프로브는 초음파 진단기에서 성능 결함이 발생할 빈도가 매우 높으면서 도플러 영상에 미치는 영향이 크다. 본 연구는 초음파 프로브의 소자 결함이 파워 및 칼러 도플러 영상에 미치는 영향을 실험적으로 살펴 본 것이다. 실험 결과 초음파 프로브 소자 결함은 그 크기가 클수록 도플러 활동 소자군 중심부에 위치할수록 도플러 영상의 밝기 및 도플러 속도를 크게 감소시키는 것으로 나타났다. 컬러 및 파워 도플러 영상에서 소자 결함이 증가할수록 혈관의 주변 부위에서부터 혈관 플라그로 오인할 수 있는 허상이 생기고 있음을 보여 주었다. 따라서 소자결함이 의심될 때는 B-모드에서 확인과정이 필요하다. 이를 볼 때 초음파 검사에 있어서는 우선적으로 프로브에 관심을 가지고 지속적인 초음파프로브 QA가 중요하다.

• 전기학회논문지
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• 제62권6호
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• pp.833-839
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• 2013

Cardiopulmonary resuscitation (CPR) is performed by thoracic compression and artificial ventilation for the patient under emergent situation to maintain at least the minimum level of respiration and blood circulation for life survival. Good quality CPR requires monitoring respiration, however, traditional respiratory air flow transducers cannot be used because the transducer elements are facing the whole area perpendicular to the flow axis. The present study developed a new air flow transducer conveniently applicable to CPR. Specially designed "sensing rod" samples the air velocity at 3 different locations of the flow cross-section, then transforms into average dynamic pressure by the Bernoulli's law. The symmetric structure of the sensing holes of the sensing rod enables bi-directional measurement simply by taking the difference in pressure by a commercial differential pressure transducer. Both inspiratory and expiratory flows were obtained with symmetric measurement characteristics. Quadratic curve fitting provided excellent calibration formula with a correlation coefficient>0.999 (P<0.0001) and the mean relative error<1%. The present results can be usefully applied to accurately monitor the air flow rate during CPR.

• 대한의용생체공학회:의공학회지
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• 제19권4호
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• pp.369-377
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• 1998

본 논문에서는 레이저 다이오드의 자기혼합 효과를 이용한 레이저 도플러 혈류계를 위한 신호처리 알고리즘들에 대한 in vitro적인 실험결과를 비교하였다. 단순하고 유연성있는 레이저 도플러 시스템을 구성함으로써 디지털 신호해석 방법에 의하여 여러 가지 신호처리 알고리즘들을 비교할 수 있도록 하였다. 이 시스템은 다양한 알고리즘을 퍼스널 컴퓨터를 사용하여 소프트웨어로 제어하므로써 다양한 알고리즘을 선택하여 비교 연구할 수 있도록 하였다. 또한, 유체 흐름의 재현성과 조직의 혈류 흐름을 모의하기 위하여 두 개의 실험적인 혈류모델을 제작하여 적용하였다. 광원은 파장 780nm의 레이저 다이오드를 사용하였으며, 3 종류의 입자 농도와 속도를 갖는 액체를 두 개의 실험모델에 흘리면서 측정된 결과들을 비교하였다. 그 결과 주파수로 가중되지 않은 알고리즘(0차 모멘트)이 속도와 농도변화를 잘 나타내는 반면에 주파수로 가중된 알고리즘들(1차와 2차 모멘트, 0차 모멘트와의 비)은 농도보다는 속도 변화를 잘 나타내었다.

• Journal of Preventive Medicine and Public Health
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• 제44권6호
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• pp.260-266
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• 2011

Objectives: We evaluated the association between common carotid artery intima-media thickness (CCA-IMT), brachialankle pulse wave velocity (baPWV), carotid plaque, and peripheral arterial disease (PAD) as indicators of macroangiopathy and diabetic retinopathy as an indicator of microangiopathy in type 2 diabetic patients. Methods: We analyzed 605 type 2 diabetic patients registered at a public health center in Korea. Following overnight fasting, venous blood and urine samples were collected and analyzed. The CCA-IMT, levels of carotid plaque, baPWV, and ankle-brachial index (ABI) of the subjects were assessed. We used non-mydriatic fundus photography to diagnose diabetic retinopathy. Multiple logistic regression analyses were used to evaluate the association between macroangiopathy and diabetic retinopathy. CCA-IMT and baPWV were divided into tertiles: CCA-IMT, 0.39 to 0.65 mm, 0.66 to 0.78 mm, and 0.79 to 1.30 mm; baPWV, 9.9 to 15.8 m/s, 15.9 to 18.9 m/s, and 19.0 to 38.0 m/s. Results: The association between baPWV and diabetic retinopathy remained significant after adjustment, with an increasing odds ratio (OR) in the second tertile (OR, 2.41; 95% confidence interval [CI], 1.27 to 4.55) and the third tertile (OR, 4.63; 95% CI, 2.33 to 9.21). No significant differences were observed in carotid plaque, PAD, and each tertile of CCA-IMT. Conclusions: BaPWV was associated with diabetic retinopathy, while CCA-IMT, carotid plaque, and PAD were not. This study suggests that the association between macroangiopathy and microangiopathy may be attributable to functional processes rather than structural processes within the vascular system.

• Annals of Clinical Neurophysiology
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• 제14권1호
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• pp.20-24
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• 2012

Background: Migraine patients can be sensitive to external or internal stimuli, such as light, noise, or hormonal changes. Using transcranial Doppler ultrasonography (TCD) with breath-holding method, we evaluated the changes of cerebrovascular reactivity (CVR) to hypercapnia in women with migraine without aura between fasting and postprandial period. Methods: Twelve women with migraine without aura and the same number of age and sex-matched healthy controls with no significant history of headache participated in this study. Using TCD examinations, we studied mean flow velocity in middle cerebral artery with better temporal window. Each subject was examined consecutively before and after a standard meal, together with serum glucose level and blood pressure. CVR was evaluated with breath-holding index (BHI). Results: Postprandial-BHI (mean+SD) was significantly higher than fasting-BHI (mean+SD) in patients group but not in controls (in patient group; postprandial-BHI=1.38, fasting-BHI=1.08, in control group; postprandial-BHI=1.25, fasting-BHI=1.18, P=0.021 and 0.239, respectively). After meal, serum glucose level was significantly enhanced but blood pressure was not in both groups. Serum glucose level of patients showed a tendency of mild positive correlation with BHIs (${\gamma}$=0.448, P=0.032). Conclusions: Although exact mechanisms are unclear, cerebrovascular reactivity of some women with migraine without aura may be influenced by prandial state.

• Transactions on Electrical and Electronic Materials
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• 제17권6호
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• pp.375-379
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• 2016

Increasing fat tissue of obese people, increases the rate of cardiovascular disease, diabetes, metabolic syndromes and dyslipidemia. An increase in the focal tissue of pancreas is a known risk factor of these diseases. Although there exists sufficient research on the diagnosis and treatment of pancreatic cancer, studies have been done on fatty pancreas. In this study, based on ultrasound imaging and using a texture characteristic of GLCM, fatty pancreas was divided into three categories: mild, moderate and severe. We compared and analyzed the three groups was by Pancreatic ultrasonography and body characteristics, serological tests, pressure and the degree of arteriosclerosis, against normal control group. The following parameters of control and test groups were measured: WC (waist circumference),BMI (body mass index), TC (total cholesterol), TG (triglyceride), HDL-C (High-density lipoprotein cholesterol) and LDL-C (Low-density lipoprotein cholesterol), SBP (systolic blood pressure), BST (Blood Sugar Test) and aortic PWV (pulse wave velocity). We observed the values correspondingly increasing fat deposition. However, ABI (Ankle Brachial pressure index) stenosis and HDL-C levels decreased with increasing fat deposit (p <0.05); a drop in these parameters are known to be harmful to the human body. The difference in texture characteristics between normal control group and pancreatic fatty group (mild, moderate, and severe) was statistically confirmed. Ultrasound imaging of pancreatic steatosis categorized the disease as mild, moderate and severe based on the characteristic texture. In conclusion, we observed on increase in metabolic syndrome, dyslipidemia, and arteriosclerosis, proportional to the degree of pancreatic fat deposition. The escalation of these diseases was confirmed and was directly related with predictors of cardiovascular diseases.

• 대한의생명과학회지
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• 제14권4호
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• pp.219-223
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• 2008

The present study was designed to clarify whether scuba diving at 5 meters of seawater influences cerebral hemodynamics, hematological and biochemical variables. Twenty healthy young men well trained scuba diving participated in this study. The blood flow velocity in the right and left middle cerebral arteries (L-MCAV and R-MCAV), blood pressure (BP), heart rate (HR), CBC and differential count, prothrombin time (PT), activated partial thromboplastin time (aPTT), biochemical variables, D-dimer and interleukin-8 (IL-8) levels were determined before, immediately after scuba diving for 30 min, and after 30 min of rest (Pre-scuba, Scuba and R-30m, respectively). L-MCAV and R-MCAV tended to increase, but the only significant increase was in L-MCAV in Scuba. SBP and HR significantly declined in R-30m compared with those of Pre-scuba and the Scuba. IL-8 levels were elevated in Scuba and R-30m compared with that of Pre-scuba. In Scuba and R-30m, hematological variables except PT and biochemical parameters excluding glucose and lactic acid did not significantly changed in comparison with those of Pre-scuba. PT level at Scuba and glucose level at R-30m significantly declined in Scuba, while lactate level at R-30m increased compared with each in Pre-scuba. However, PT level at Scuba was within a normal range. These results suggest that scuba diving at 5 m of seawater for 30 min has no adverse effects, is safe and useful for improving health. However, further study must be performed to clarify the mechanism of elevated IL-8 level following scuba diving.

• 한국임상수의학회지
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• 제31권2호
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• pp.112-116
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• 2014

2개월령 수컷 핏불테리어종 개 (체중 1.01 kg)가 심한 복부 팽만, 운동 불내성, 성장 지연, 노란 비루와 식욕부진을 주증으로 진료 의뢰 되었다. 영상 진단상에 비정상적인 막으로 분할된 확대된 우심방, 심한 수축기 폐동맥 제트 혈류 (최고혈류 5.66 m/s) 그리고 심방 중격에서의 우좌 단락혈류가 관찰되었다. 임상증상 및 진단학적 결과에 기초하여, 본 증례는 심한 폐동맥 협착과 우좌 단락의 난원공 개존증이 합병된 우측 삼중심방증으로 진단 되었다. 비안정적인 환자의 상태 때문에 수술적 혹은 중재적 치료는 시도되지 않았다. 그 개는 수혈, 산소공급 그리고 심장 관련 약물적 치료(예, 실데나필, 스피로노락톤, 에날라프릴)로 회복되었다.

• 대한기계학회논문집B
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• 제25권1호
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• pp.18-28
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• 2001

The present study investigates flow dynamics between two dimensional compliant plates under sinusoidal flow conditions in order to understand influence of wall motion, impedance phase angle (time delay between pressure and flow waveforms), and non-Newtonian fluid on wall shear stress using computational fluid dynamics. The results showed that wall motion induced additional terms in the streamwise velocity profile and the pressure gradient. These additional terms due to wall motion reduced the amplitude of wall shear stress and also changed the mean wall shear stress. The trend of the changes was very different depending on the impedance phase angle. As the impedance phase angle was changed to more negative values, the mean wall shear stress decreased while the amplitude of wall shear stress increased. As the phase angle was reduced from 0°to -90°under $\pm$4% wall motion, the mean wall shear stress decreased by 12% and the amplitude of wall shear stress increased by 9%. Therefore, for hypertensive patients who have large negative phase angles, the ratio of amplitude and mean of the wall shear stress is raised resulting in a more vulnerable state to atherosclerosis according to the low and oscillatory shear stress theory. We also found that non-Newtonian characteristics of the blood protect atherosclerosis by decreasing the oscillatory shear index.

• 한국정밀공학회지
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• 제24권10호
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• pp.123-130
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• 2007

Hypoplastic left heart syndrome is currently the most lethal cardiac malformation of the newborn infant. Survival following a Norwood operation depends on the balance between systemic and pulmonary blood flow, which is highly dependent on the fluid dynamics through the interposition shunt between the two circulations. The purpose of this study is an optimization of the systemic-to-pulmonary artery shunt. In this study, We used computational fluid dynamic(CFD) models to determine the velocity profile in a systemic-to-pulmonary artery shunt and suggested a simplified method of calculating the blood flow in the shunt based on Ultrasound systems. We analyzed the flow characteristic variations and oscillatory shear index(OSI) due to the anastomosis angle and shunt diameter changing. Four different CFD models were constructed with the shunt sizes ranging from 3 to 3.5mm. The angle between the brachiocephalic trunk(BCT) and the shunt were $30^{\circ}$ and $45^{\circ}$, respectively. When the diameter is 3.0 mm, the oscillatory shear index decreased by 1.2% at $30^{\circ}$ as opposed to at $45^{\circ}$. When the diameter is 3.5 mm, it increased by 18% more at $30^{\circ}$ as opposed to at $45^{\circ}$. When the joint angle is $30^{\circ}$ and the diameter is 3.0 mm, the oscillatory shear index decreased by 4.1% in comparison with the 3.5 mm diameter. When the angle is $45^{\circ}$ and the diameter is 3.0 mm, the index increased by 14.6% in comparison with the 3.5 mm diameter.