• 대한수학회지
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• 제43권4호
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• pp.885-897
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• 2006

A new mathematical model of pumping heart coupled to lumped compartments of blood circulation is presented. This lumped pulsatile cardiovascular model consists of eight compartments of the body that include pumping heart, the systemic circulation, and the pulmonary circulation. The governing equations for the pressure and volume in each vascular compartment are derived from the following equations: Ohm's law, conservation of volume, and the definition of compliances. The pumping heart is modeled by the time-dependent linear curves of compliances in the heart. We show that the numerical results in normal case are in agreement with corresponding data found in the literature. We extend the developed lumped model of circulation in normal case into a specific model for arrhythmia. These models provide valuable tools in examining and understanding cardiovascular diseases.

• Journal of Chest Surgery
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• 제51권5호
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• pp.363-366
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• 2018

One of the complications of permanent pacemaker implantation is unintended phrenic nerve stimulation. A 15-year-old boy with a permanent pacemaker presented with chest discomfort due to synchronous chest wall contraction with pacing beats. Even after reprogramming of the pacemaker, diaphragmatic stimulation persisted. Therefore, we performed thoracoscopic phrenic nerve insulation using a Gore-Tex patch to insulate the phrenic nerve from the wire. A minimally invasive approach using a thoracoscope is a feasible option for retractable phrenic nerve stimulation after pacemaker implantation.

• Journal of Chest Surgery
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• 제50권4호
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• pp.298-299
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• 2017

We report the case of a 17-year-old girl who presented with an indentation in the right ventricle caused by an incomplete pericardium on preoperative 3-dimensional reconstructed computed tomography. She was to undergo surgery for a partial atrioventricular septal defect and secundum atrial septal defect. Preoperative electrocardiography revealed occasional premature ventricular beats. We found the absence of the left side of the pericardium intraoperatively, and this absence caused strangulation of the diaphragmatic surface of the right ventricle. After correcting the lesion, the patient's rhythm disturbances improved.

• 대한의용생체공학회:의공학회지
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• 제26권2호
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• pp.87-93
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• 2005

A new method for real-time estimating left ventricular relaxation time constant (T) from the left ventricular (LV) pressure waveform, based on the isovolumic relaxation model, is proposed. The presented method uses a recursive least squares (RLS) algorithm to accomplish real-time estimation. A new criterion to detect the end-point of the isovolumic relaxation period (IRP) for the estimation of T is also introduced, which is based on the pattern analysis of mean square errors between the original and reconstructed pressure waveforms. We have verified the performance of the new method in over 4,600 beats obtained from 70 patients. The results demonstrate that the proposed method provides more stable and reliable estimation of τ than the conventional 'off-line' methods.

• The Korean Journal of Pain
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• 제26권3호
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• pp.303-306
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• 2013

Postural orthostatic tachycardia syndrome (POTS) refers to the presence of orthostatic intolerance with a heart rate (HR) increment of 30 beats per minute (bpm) or an absolute HR of 120 bpm or more. There are sporadic reports of the autonomic nervous system dysfunction in migraine and fibromyalgia. We report a case of POTS associated with migraine and fibromyalgia. The patient was managed with multidisciplinary therapies involving medication, education, and exercise which resulted in symptomatic improvement. We also review the literature on the association between POTS, migraine, and fibromyalgia.

• Journal of Korean Neurosurgical Society
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• 제42권2호
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• pp.135-140
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• 2007

It is not the best way to treat a hopeless patient with life-sustaining medical devices until the heart beats stop. Advanced medical technology may prolong the life for a significant period without recovery from the disease. However, it would give an unbearable economic burden to the family and the society. In 2006, we decided not to operate 9 patients with traumatic intracranial hematomas. We examined those patients with special references to possible legal and ethical problems. It is reasonable to withhold a treatment after documentation that the family never wants any life sustaining treatment when the treatment does not guarantee the meaningful life.

• 대한음성학회:학술대회논문집
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• 대한음성학회 2007년도 한국음성과학회 공동학술대회 발표논문집
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• pp.213-216
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• 2007

The purpose of this study is to observe how Korean learners with low (KL) and high (KH) English proficiency manifest English rhythm with respect to the relative temporal stability or temporal constraint of syllable. In this study, speech cycling task, repeating a short phrase with the series of beeps of same interval, was used to examine temporal distribution of stressed beats.

• 한국멀티미디어학회논문지
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• 제20권2호
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• pp.234-243
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• 2017

With the development of smartphone technologies enable photoplethysmogram (PPG) acquisition by camera and heart rate (HR) measurement. This papers presents improved algorithm to extract HR from PPG signal recorded by smartphone camera and to develop real-time PPG signal processing Android application. 400 video samples recorded by Samsung smartphone camera are imported as input data for further processing and evaluating algorithm on MATLAB. An optimized algorithm is developed and tested on Android platform with different kind of Samsung smartphones. To assess algorithm's performance, medical device Beurer BC08 is used as reference. According to related works, accuracy parameters includes 90% number of samples that has relative errors less than 5%, Person correlation (r) more than 0.9, and standard estimated error (SEE) less than 5 beats-per-minutes (bpm).

• Journal of Multimedia Information System
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• 제3권2호
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• pp.1-8
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• 2016

In this paper, we propose a method to automatically diagnose various diseases. The input data consists of electrocardiograph (ECG) recordings. We extract R-to-R interval (RRI) signals from ECG recordings, which are preprocessed to remove trends and ectopic beats, and to keep the signal stationary. After that, we perform some prospective analysis to extract time-domain parameters, frequency-domain parameters, and nonlinear parameters of the signal. Those parameters are unique for each disease and can be used as the statistical symptoms for each disease. Then, we perform feature selection to improve the performance of the diagnosis classifier. We utilize the selected features to diagnose various diseases using machine learning. We subsequently measure the performance of the machine learning classifier to make sure that it will not misdiagnose the diseases. The first two steps, which are R-to-R extraction and preprocessing, have been successfully implemented with satisfactory results.

• 한국정보처리학회논문지
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• 제7권5호
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• pp.1341-1350
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• 2000

Much research has been performed to represent music information on computers. However, one problem of the previous approaches is that music information cannot be hared with other music systems since they have used their own representation schemes. In order to resolve this problem, we have developed a new scheme for representing, editing, and playing rhythms among music information based on XML which is a web standard language. We present a RDML (Rhythm Description Markup Language) to exactly describe rhythm information such as beats, musical instruments, and performance information, which is much simpler thant previous representation schemes. Moreover, the RDML representation can be played by converting it into SMIL representation. Because our approach is based on the web standard, the music information can be shared on the web.