• Proceedings of the Korean Society of Precision Engineering Conference
• /
• 2004.10a
• /
• pp.985-988
• /
• 2004

This paper proposes a new training system for equilibrium sense and postural control using unstable platform and force plate. This system consists of unstable platform, force plate, computer interface, software and the computer. Using this system and training programs, we perform the experiment to train the equilibrium sense and postural control of subject. To evaluate the effects of balance training, we measured some parameters such as the maintaining time in the target, the moving time to the target and the mean absolute deviation of the trace before and after training. The result shows that this system can improve the equilibrium sense and balance ability of subject. This study shows that proposed system had an effect on improving equilibrium sense and postural control and might be applied to clinical rehabilitation training as a new effective balance training system.

• Journal of the Korean Society of Visualization
• /
• v.3 no.2
• /
• pp.45-50
• /
• 2005

Electro-osmotic flow (EOF) instability in a microchannel has been experimentally investigated using a micro-PIV system. The micro-PIV system consisting of a two-head Nd:Yag laser and cooled CCD camera was used to measure instantaneous velocity fields and vorticity contours of the EOF instability in a T-shape glass microchannel. The electrokinetic flow instability occurs in the presence of electric conductivity gradients. Charge accumulation at the interface of conductivity gradients leads to electric body forces, driving the coupled flow and electric field into an unstable dynamics. The threshold electric field above which the flow becomes unstable and rapid mixing occurs is about 1000V/cm. As the electric field increases, the flow pattern becomes unstable and vortical motion is enhanced. This kind of instability is a key factor limiting the robust performance of complex electrokinetic bio-analytical devices, but can also be used for rapid mixing and effective flow control fer micro-scale bio-chips.

• Journal of Chest Surgery
• /
• v.26 no.5
• /
• pp.349-354
• /
• 1993

From July 1992 through January 1993, 11 patients with unstable angina received aorto-coronary bypass surgery at Dong-A University Hospital. There were 5 males and 6 females whose age ranged from 36 to 76 years old. Of the 11 patients, 3 were Functional class IL 5 were Functional class 111.3 were Functional class IV. Preoperative coronary angiography showed a significant stenosis of the left anterior descending artery in 9 cases, of its diagonal branch in I case, of the circumfiex artery in 3 cases, and of its obtuse marginal branch in 2 cases, of the right coronary artery in 4 cases, and of left main coronary artery in 3 cases. There were 4 cases of single vessel disease, 1 double vessel disease, 3 triple vessel disease and 3 left main disease. A single graft was placed in 1 patient, a double graft in 5, a triple graft in 2, and a quadriple graft in 3 patients. Left internal mammary artery plus saphenous vein graft were used in 4 patients. Postoperative complications were mediastinitis in 1, sternal instability in 2, pneumonia in 1, arrythmia in I case.

• Journal of Chest Surgery
• /
• v.13 no.2
• /
• pp.118-124
• /
• 1980

A double aorto-coronary bypass procedure performed in 2 cases, one with a Prinzmetal`s variant angina and the other with an unstable angina, is presented. The patient with a Prinzmetal`s angina who had a high-grade obstruction of the left anterior descending and the right coronary system showed a marked postoperative improvement with complete disappearance of anginal pain. The other patient with unstable angina had obstruction of the left anterior descending as well as a marginal branch of the left circumflex artery. Following bypass of these vessels, the patient did well during the immediate postoperative period. However, he developed hypotension in the recovery room and died 6 hours postoperatively, in spite of an intensive effort at resuscitation. The most likely cause of death in this patient is a myocardial infarction.

• The Transactions of The Korean Institute of Electrical Engineers
• /
• v.60 no.5
• /
• pp.993-998
• /
• 2011

In this paper we suggest new criteria for the classification of the electrode gap between common and scan electrodes. The electrode gap is categorized as a short, middle, and long gap according to the criteria. Among these structures, we focus on the erase waveform of a mid-gap structure. we report an unstable discharge arising from the erase ramp period in a mid-gap structure. Based on the Vt close curve, we analyze the unstable discharge at various conditions. Our analysis reveals that the unstable discharge is ignited between surface electrodes and caused by un-erased wall charges accumulated on the outer edges of electrodes. By reducing the voltage level of the last sustain pulse, the problem is solved.

• Journal of Intelligence and Information Systems
• /
• v.11 no.3
• /
• pp.45-55
• /
• 2005

In this paper, we propose a method to a synchronization of chaotic UAVs(Unmanned Aerial Vehicle) that have unstable limit cycles in a chaos trajectory surface. We assume all obstacles in the chaos trajectory surface have a Van der Pol equation with an unstable limit cycle. The proposed methods are assumed that if one of two chaotic UAVs receives the synchronization command, the other UAV also follows the same trajectory during the chaotic UAVs search on the arbitrary surface.

• The Korean Journal of Pain
• /
• v.11 no.1
• /
• pp.146-149
• /
• 1998

Herpes zoster is a viral disease characterized by skin rash and persistent pain. Early treatment with epidural analgesia provides very effective pain relief and reduces the incidence of postherpetic neuralgia. However, epidural analgesia in elderly, deliberated or hypovolemic patients may complicate circulatory depression such as hypotension and bradycardia. Even if temporary, a major decrease in blood pressure may decrease coronary blood flow of patients with arteriosclerosis and ischemic accident may occur. We experienced a case of unstable angina pectoris after lumbar epidural blockade in a herpes zoster patient with chronic stable angina pectoris.

• 한국연소학회:학술대회논문집
• /
• 2001.11a
• /
• pp.125-135
• /
• 2001

Aiming at a direct, also more realistic, prediction of unstable waves evolving in the combustion chamber, present paper introduces a new analytical method. Instability equations are freshly formulated, and solve the time-integrated ODEs for amplification factors to find the transients of pressure and velocity fluctuations. Present numerical approach requires no separate treatments for nonlinearities. Preliminary numerical experiments for unstable waves in quasi-one-dimensional rocket combustor, show validity and applicability of present model, and promise for its practical use. Study for the complex models for physics, especially velocity- and pressure-coupled responses, and inclusion of multi dimensionality remains as future tasks.

• International Journal of Railway
• /
• v.9 no.2
• /
• pp.46-49
• /
• 2016

In this study a new detection technique based on WAK is introduced that can be used for identifying unstable concrete sleeper installed in ballast by triggering activated wave on the sleeper surface. If a gap exists immediately below the concrete sleeper, static stiffness can be lower than stable case's stiffness. The concrete sleeper is assumed as a single degree of freedom system (SDOF). The static stiffness K can be obtained by iteratively calculated mass (m), stiffness (k) and damping coefficient (c) of SDOF system. Those coefficients are used to specify the ballast condition such as a gap between the sleeper and ballast. Typical test results using a small sleeper model test are summarized and explained for proof of effectiveness of the WAK test for checking unstable condition of the sleeper.

• Journal of Chest Surgery
• /
• v.20 no.2
• /
• pp.393-398
• /
• 1987

Unstable angina pectoris is often premonitory to an acute myocardial infarction. Surgical revascularization in this syndrome is of great potential benefit and relatively low mortality. A patient with unstable angina pectoris is reported. A 65-year-old man complained of dyspnea and pain in the left anterior chest. The pain was brought on by mild exercise, occurred at rest and sleeping time. The pain worsened over a month period and more aggravated in intensity and duration. Physical examination showed no abnormalities except hypertension and laboratory data were within normal limits. His anginal pain was not relived by nitroglycerin ingestion. Preoperative coronary angiograms revealed significant obstruction [>90%] of left anterior descending coronary artery. Aorto-left anterior descending coronary bypass with autogenous saphenous vein used as conduit was performed. The postoperative course was uneventful and he was discharged on 16th postoperative day in a healthy condition.