• Journal of the Korean Society of Propulsion Engineers
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• v.13 no.3
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• pp.41-49
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• 2009

The present paper describes a mathematical modeling and simulation of the separation of a solid rocket booster from an air breathing engine vehicle. The vehicle and booster are considered as a multi-connected body and the booster is assumed to move only along the axial direction of the vehicle. The dynamic motion of the vehicle and the booster were modeled by using Kane's method. The aerodynamic forces on the whole system along various positions of booster were calculated by using DATCOM software and the internal pressure force acting on the effective surface during separation was simply calculated with gas dynamics and Taylor MacColl equation. Numerical simulation was done by using Mathworks-Matlab. From the result, the variation of Mach number and angle of attack are not large during the separation, so the variation of pitch angle and the characteristics of inlet flow for varying the Mach number and angle of attack during the separation test can be identified as neglectable values.

• Journal of the Korean Society of Industry Convergence
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• v.23 no.3
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• pp.433-444
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• 2020

This study proposes a method to improve the sleep stage and efficiency estimation of sleep apnea patients using a UWB (Ultra-Wideband) radar. Motion and respiration extracted from the radar signal were used. Respiratory signal disturbances by motion artifacts and irregular respiration patterns of sleep apnea patients are compensated for in the preprocessing stage. Preprocessing calculates the standard deviation of the respiration signal for a shift window of 15 seconds to estimate thresholds for compensation and applies it to the breathing signal. The method for estimating the sleep stage is based on the difference in amplitude of two kinds of smoothed respirations signals. In smoothing, the window size is set to 10 seconds and 34 seconds, respectively. The estimated feature was processed by the k-nearest neighbor classifier and the feature filtering model to discriminate between the sleep periods of the rapid eye movement (REM) and non-rapid eye movement (NREM). The feature filtering model reflects the characteristics of the REM sleep that occur continuously and the characteristics that mainly occur in the latter part of this stage. The sleep efficiency is estimated by using the sleep onset time and motion events. Sleep onset time uses estimated features from the gradient changes of the breathing signal. A motion event was applied based on the estimated energy change in the UWB signal. Sleep efficiency and sleep stage accuracy were assessed with polysomnography. The average sleep efficiency and sleep stage accuracy were estimated respectively to be about 96.3% and 88.8% in 18 sleep apnea subjects.

• Investigative Magnetic Resonance Imaging
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• v.23 no.1
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• pp.38-45
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• 2019

Purpose: To demonstrate the high-resolution numerical simulation of the respiration-induced dynamic $B_0$ shift in the head using generalized susceptibility voxel convolution (gSVC). Materials and Methods: Previous dynamic $B_0$ simulation research has been limited to low-resolution numerical models due to the large computational demands of conventional Fourier-based $B_0$ calculation methods. Here, we show that a recently-proposed gSVC method can simulate dynamic $B_0$ maps from a realistic breathing human body model with high spatiotemporal resolution in a time-efficient manner. For a human body model, we used the Extended Cardiac And Torso (XCAT) phantom originally developed for computed tomography. The spatial resolution (voxel size) was kept isotropic and varied from 1 to 10 mm. We calculated $B_0$ maps in the brain of the model at 10 equally spaced points in a respiration cycle and analyzed the spatial gradients of each of them. The results were compared with experimental measurements in the literature. Results: The simulation predicted a maximum temporal variation of the $B_0$ shift in the brain of about 7 Hz at 7T. The magnitudes of the respiration-induced $B_0$ gradient in the x (right/left), y (anterior/posterior), and z (head/feet) directions determined by volumetric linear fitting, were < 0.01 Hz/cm, 0.18 Hz/cm, and 0.26 Hz/cm, respectively. These compared favorably with previous reports. We found that simulation voxel sizes greater than 5 mm can produce unreliable results. Conclusion: We have presented an efficient simulation framework for respiration-induced $B_0$ variation in the head. The method can be used to predict $B_0$ shifts with high spatiotemporal resolution under different breathing conditions and aid in the design of dynamic $B_0$ compensation strategies.

• Journal of the Korea Society of Computer and Information
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• v.27 no.11
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• pp.191-198
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• 2022

The most basic thing to measure the condition of a companion animal is to check the breathing and pulse. There are several methods to measure the breathing and pulse of a companion animal, and the PPG method is generally used to measure the oxygen saturation (SpO₂) in a companion animal. However, since the input PPG signal is inputted with various information as well as oxygen saturation, it is necessary to separate and extract oxygen saturation information from the PPG signal in order to measure the oxygen saturation. Therefore, in this paper, a wearable measuring device for companion animals that can be measured by applying the PPG method was designed and implemented, and an algorithm for separating oxygen saturation information from the PPG signal input through the wearable measuring device was proposed.

• Journal of the Korea Society of Computer and Information
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• v.28 no.12
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• pp.175-182
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• 2023

In this paper, we propose a study compared and analyzed the CPR results and muscle fatigue of the three groups. There is a group that counts loudly when compressing the mannequin's chest (Group A), a group that breathes autonomously without counting (Group B), and a group that breathes abdominally without counting (Group C). Twelve people were assigned to each group, and after performing chest compressions for 5 minutes, the results of CPR were analyzed using a program connected to the mannequin, and the muscle fatigue of the performers was analyzed using wireless electromyography. The most efficient method was found to be group B. If we only look at the speed and depth of compression within the normal range, Group C would be more efficient, but Group B showed significantly lower muscle fatigue, and Group A did not reach the normal range in depth of chest compression and muscle fatigue was the highest. Group B was also found to be the most accurate in hand positioning accuracy, and was also found to be the most efficient in maintaining concentration on chest compressions.

• Journal of Korean Physical Therapy Science
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• v.7 no.2
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• pp.439-457
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• 2000

The causes, risk factors and sequelae of mastectomy were studied, and the physical therapy approaches on post-mastectomy was discussed in this study. It was found that the patients taken mastectomy have experienced pins and needles in muscle, weakening of muscle, pains, deterioration of motion in joint region and activities of daily living, psychiatric sequelae, and etc even after the conservertive therapies like the chemical therapy, radiotherapy, immunotherapy, and hormone therapy. However, few study on the physical therapy approaches for patients with breast cancer has been carried in Korea at present. The followings were proposed as the physical therapy approaches. 1. Shoulder joint motion approach to relax the limit of range of motion 2. Control of breathing exercise for dealing with removal of the pectorailis muscle 3. Method to reduce the edema of arms for tackling the cut of lymph node 4. Method to reduce pains, pins and needles 5. Support home exercise program after discharging from hospital, sexual life and pregnancy, and activities of daily living training method.

• Journal of Korea Multimedia Society
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• v.20 no.9
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• pp.1491-1501
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• 2017

In this paper, we propose a method to measure respiration rate by dividing the respiration related region in depth image using level set method. In the conventional method, the respiration related region was separated using the pre-defined region designated by the user. We separate the respiration related region using level set method combining shape prior knowledge. Median filter and clipping are performed as a preprocessing method for noise reduction in the depth image. As a feasibility test, respiration activity was recorded using depth camera in various environments with arm movements or body movements during breathing. Respiration activity was also measured simultaneously using a chest belt to verify the accuracy of calculated respiration rate. Experimental results show that our proposed method shows good performance for respiration rate estimation in various situation compared with the conventional method.

• Journal of Korean Physical Therapy Science
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• v.6 no.4
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• pp.241-249
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• 1999

One of the major purpose of rehabilitation program is for the individual to achieve independence. That means independence from family members, independence from friends, and independence from rehabilitation team. An independent attitude is essential for autonomous functioning. Unless a disabled person is motivated to function independently, he will never do so. 3) Hydrotherapy, HALLIWICK method was applied to SCI patient. Especially, metacentric effect, density, buoyancy and breathing control are very very important theory.

• Proceedings of the KSME Conference
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• 2002.08a
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• pp.253-254
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• 2002

The determination of thrust is very important in hypersonic air-breathing propulsion design and evaluation. Because of the short flow-residence time in the combustor, the evaluation of engine performance is strongly influenced upon the engine thrust. Conventional methods to determine the thrust is using thrust stand or force measurement system. However, these methods cannot be applied to the case where thrust stands are impractical, such as free jet testing of engines, and model combustor. With this reason, the thrust determination method from measured pilot pressure is considered and evaluated.

• Journal of ILASS-Korea
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• v.25 no.2
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• pp.74-80
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• 2020

The jet in crossflow is a spray method used in the various air-breathing engine. In order to understand the spray characteristics in various environments, many prior studies have been conducted. However, there is a lack of understanding of the low-temperature liquid spray characteristics below 273 K. With this in mind, we tried to enhance the knowledge of the low-temperature liquid spray characteristics by identifying the penetration height of low-temperature ethanol. The experiment was conducted under phase pressure, and 273 K of air and 293, 263, and 233 K of ethanol was used. Shadowgraphy was employed to measure the liquid penetration, and Otsu's method was used to analyze the penetration height. The heights tend to decrease as the temperature of the liquid jet decreases. A correlation for the penetration height in the experimental conditions was derived and presented.