• 대한의용생체공학회:학술대회논문집
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• 대한의용생체공학회 1997년도 춘계학술대회
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• pp.88-91
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• 1997

One of the most significant feature of diagnostic ultrasonic instrument is to display information on the soft tissues in the body in real time. In this paper we carried out basic study on the digital moving image processing for tracing the movement of heart valves in echocardiograms. Digital moving image file was made from analog echocardiograms and it was remade as 256 gray-level images on each frame. The ROI(Region of interest) was placed on a heart valve region to process images efficiently. Images were processed by the use of image enhancement filters and morphology filters. The result shows that the processed images were more enhanced than original images. When a moving image is reconstructed by using these enhanced images, we can trace the movement of heart valves more easily. In this study we proposed the availability of the moving image reconstruction using enhancement images.

• 대한기계학회논문집B
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• 제21권9호
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• pp.1139-1148
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• 1997

Compression waves propagating in a high-speed railway tunnel develops large pressure fluctuations on the train body or tunnel structures. The pressure fluctuations would cause an ear discomfort for the passengers and increase the aerodynamic resistance of trains. As a fundamental research to resolve the pressure wave phenomenon in the tunnel, experiments were carried out by using a shock tube with an open end. A blockage to model trains inside the tunnel was installed on the lower wall of shock tube, thus forming a sudden cross-sectional area reduction. The compression waves were obtained by the fast opening gate valve instead of a conventional diaphragm of shock tube and measured by the flush mounted pressure transducers with a high sensitivity. The experimental results were compared with the previous theoretical analyses. The results show that the ratio of the reflected to the incident compression wave at the sudden cross-sectional area reduction increases but the ratio of the passing to the incident compression wave decreases, as the incident compression wave becomes stronger. This experimental results are in good agreements with the previous theoretical ones. The maximum pressure gradient of the compression wave abruptly increases but the width of the wave front does not vary, as it passes over the sudden cross-sectional area reduction.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2002년도 학술대회지
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• pp.705-706
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• 2002

Hemodynamics of the TPLS(Twin Pulse Life Support System) is numerically investigated to delineate the possibility of hemolysis in blood. Computational method employing finite element algorithm is utilized to solve the blood flow of the sac squeezed by moving actuator. We assume that the blood flow interacts with the sac material which is activated by the rigid body motion of the actuator. Valve dynamics at the ends of the sac is simplified as on/off type motion. We compute the transient viscous flow in the two-dimensional geometry of the blood sac. Incompressible laminar flow is simulated on the assumption of Newtonian fluid. Blood velocity has a step gradient near the throat of the sac formed by the moving actuator. According to the decrease of the gap size of blood passage, the magnitude of shear stress in the blood is dramatically increased. Numerical solutions show that the maximum value of shear stress in the blood flow in TPLS is relatively smaller than that of the roller type ECLS.

• 한국자동차공학회논문집
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• 제24권6호
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• pp.702-708
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• 2016

The torque converter is deformed according to the rotating speed and control pressure when engine power is transferred to the transmission. This deformation, which is called ballooning phenomenon, occurs mainly at the outer side by the centrifugal force of the automatic transmission fluid (ATF) and the control pressure from the valve body. Although the torque converter is slightly deformed when rotating, the ballooning phenomenon affects fluid performance, efficiency and durability. Thus, expansion characteristics analysis is important in determining torus size, control pressure and structure. In this paper, an analysis equation and FEM model was developed to investigate the expansion characteristics. Using this model, structural analysis was performed to investigate the relationships between deformation and the torus diameter. The results were confirmed by comparing with the test results.

• 한국자동차공학회논문집
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• 제8권3호
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• pp.181-189
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• 2000

The aerodynamic characteristics of large transport vehicle has become more and more important in recent vehicle design to improve driving performance in high speed cruising and raise the product valve with regard to a comfortable driving condition. Hence, detailed knowledge of the flow field around truck coner vane is essential to improve fuel efficiency and reduce the dirt contamination on vehicle body surface. In this study, three-dimensional flow characteristics around corner vane attached to truck cabin were computed for the steady, incompressible, and high speed viscous flow, adopting the RNG k-$\varepsilon$ turbulence model. In order to investigate the influence of configuration and structure of corner vane, computations were carried out for four cases at a high Reynolds number, Re=4.1$\times$106 (based on the cabin height). The global flow patterns, drag coefficient and the distributions such as velocity magnitude, turbulent kinetic energy around the corner vane, were examined. As a result of this study, we could identify the flow characteristics around corner vane for the variation of corner vane length and width. Also, suggest the improved structure to reduce the dirt contamination in cabin side.

• 한국재료학회지
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• 제16권11호
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• pp.698-704
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• 2006

In this study, the effect of chill layers occurred in shot sleeve on the molten metal filling was analyzed through computer simulation. The behavior of chill layers with temperature variation of shot sleeve set from 200 to $280^{\circ}C$ was also investigated. The simulation results showed the chill layers set in the in-gates during the injection process change the main filling direction and cause turbulent flow pattern, resulting in porosities inside the castings. The amount of chill layers with the increasing temperature of shot sleeve was considerably reduced. Particularly, at the setting temperature of $280^{\circ}C$ by heat control unit, the biggest reduction in chill layers, excellent trimmed surface and the highest density were achieved, suggesting that as the optimal sleeve condition in aluminum high pressure diecasting, especially for highly complex parts like valve body.

• 대한안전경영과학회지
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• 제18권4호
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• pp.99-105
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• 2016

This study was conducted to develop a dummy in an environment similar to the human body, to prepare a standard for evaluation and to present the process of the production in order to evaluate the performance of the robot that can detect the persons needing rescue in a confined space, who are difficult for fire-fighting officials to rescue in case of fire and disaster. As a result, a standard for evaluation was developed and standardized into four parts 'Normal,' 'Risk Stage 1,' 'Risk Stage 2' and 'Risk Stage 3'based on the number of breath cycles, carbon dioxide concentration, core temperature and criteria for hearing to recognize the voice. In addition, in order to produce a dummy, fever, breathing capacity and voice output function were compared and analyzed. This study has significance that it built up basic data of the method of producing the actual dummy, by presenting characteristics and controlling methods using the waterproof insulation heating coil for the function, solenoid valve for the consecutive output of breathing capacity and USB program sound board for voice output.

• 한국정보통신학회:학술대회논문집
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• 한국정보통신학회 2014년도 춘계학술대회
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• pp.402-403
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• 2014

미소자기감지 시스템은 자기신호를 전기신호로 변환하여 신호처리부로 송신하는 과정에서 AC성 노이즈가 유입되고, 필터링 과정에서 과도한 신호의 시간 및 위상 지연 현상이 발생한다. 본 논문에서는 상기의 문제점을 해결하기 위하여 무선통신 기술을 적용한 미소자기 감지 시스템을 설계하고 구현하였다. 미소자기시스템은 자기 센서 검출부, 신호처리부, 무선센서네트워크부, 시스템 제어부 및 모니터링부로 구성하였으며, 무선센서네트워크 기반의 센서의 무선화 적용을 통해 신호 노이즈 및 신호 지연을 최소화 하는 결과를 얻을 수 있었다.

• 한국임상수의학회지
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• 제36권3호
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• pp.155-158
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• 2019

Morphologic changes or functional impairments of the papillary muscle (PM) can influence mitral valve competence. The purpose of this study was to investigate PM size and contractile function using two-dimensional and color tissue Doppler echocardiography in normal dogs. 35 unsedated Beagle dogs without cardiovascular disease were examined. The vertical (VD) and horizontal diameter (HD) of the posterior and anterior PM was measured at end-diastole, and compared with the thickness of the left ventricular posterior wall (LVPWd). Longitudinal systolic movement of the PM was quantified as myocardial velocity and strain using tissue Doppler. The VD, HD, and ratios (VD/LVPWd, HD/LVPWd, VD/HD) were significantly greater in the posterior than anterior PM (P < 0.001). The VD and HD of posterior PM and the HD of anterior PM were significantly correlated with LVPWd (r = 0.47, 0.44, and 0.42, respectively). Body weight was significantly correlated with VD of posterior PM (r = 0.37). The peak systolic tissue velocity of the PM was $4.93{\pm}1.25cm/sec$ and peak strain was $-30.83{\pm}11.92%$. PM size and systolic function can be quantitatively assessed using two-dimensional and tissue Doppler. The establishment of these objective PM measurements may be useful to evaluate morphological and functional abnormalities of the canine PM.

• The Korean Journal of Legal Medicine
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• 제42권4호
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• pp.153-158
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• 2018

Staphylococcus aureus is an important cause of human infections, and it is also a commensal that colonizes the nose, axillae, vagina, throat, or skin surfaces. S. aureus has increasingly been recognized as a cause of severe invasive illness, and individuals colonized with this pathogen are subsequently at increased risk of its infections. S. aureus infection is a major cause of skin, soft tissue, respiratory, bone, joint, and endovascular disorders, and staphylococcal bacteremia may cause abscess, endocarditis, pneumonia, metastatic infection, foreign body infection, or sepsis. The authors describe a case of a fisherman who died of sepsis on a fishing boat during sailing out for fish. The autopsy shows paravertebral abscess, pus in the pericardial sac, infective endocarditis with vegetation on the aortic valve cusp, myocarditis, pneumonia and nephritis with bacterial colonization, and also liver cirrhosis and multiple gastric ulcerations.