• Geomechanics and Engineering
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• v.5 no.6
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• pp.499-517
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• 2013

In order to investigate shear behavior of granular materials due to excavation and associated unloading actions, load-controlled plane strain compression tests under decreasing confining pressure were performed under drained conditions and the results were compared with the conventional plane strain compression tests. Four types of granular material consisting of two quartz sands and two glass beads were used to investigate particle shape effects. It is clarified that macro stress-strain behavior is more easily influenced by stress level and stress path in sands than in glass beads. Development of localized deformation was analyzed using photogrammetry method. It was found that shear bands are generated before peak strength and shear band patterns vary during the whole shearing process. Under the same test condition, shear band thickness in the two sands was smaller than that in one type of glass beads even if the materials have almost the same mean particle size. Shear band thickness also decreased with increase of confining pressure regardless of particle shape or size. Local maximum shear strain inside shear band grew approximately linearly with global axial strain from onset of shear band to the end of softening. The growth rate is found related to shear band thickness. The wider shear band, the relatively lower the growth rate. Finally, observed shear band inclination angles were compared with classical Coulomb and Roscoe solutions and different results were found for sands and glass beads.

• Phonetics and Speech Sciences
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• v.7 no.3
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• pp.183-191
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• 2015

This study evaluated the effect of the therapeutic methods between vocal function exercise(VFE), which has been used for the patients with presbyphonia in the precedent studies and laryngeal calibration technique($SKLCT^{(R)}$), which is designed by the author. We identified 58 patients who was been diagnosed as presbylaryngis by laryngoscopic examinations. 21 patients were underwent voice therapy using $SKLCT^{(R)}$, 20 patients were taken VFE, and the control group of 17 patients were not taken any voice therapy. All subjects received the therapy, ranging from seven to nine sessions, and were evaluated the voice change on pretherapy and posttherapy. The grade of hoarseness, roughness, and breathiness voice were reduced on perceptual judgments after $SKLCT^{(R)}$, but only grade of hoarseness was reduced after the VFE. Jitter, Shimmer, NHR were reduced and MPT were increased after the $SKLCT^{(R)}$(p<.05), while Jitter and SFF were reduced after the VFE. Frequency and intensity range were increased significantly on the posttest performance after taking voice therapy by the $SKLCT^{(R)}$, on the other hand only intensity range was increased after VFE. Especially, we can find the significant change that glottic gap and supraglottic compressions was reduced in most of patients after the $SKLCT^{(R)}$, but there's no changes in the group of VFE and control group. In the study, we can suggest that the $SKLCT^{(R)}$ may be useful in improving the voice qualities and laryngeal function of presbyphonia.

• The Korean Journal of Emergency Medical Services
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• v.22 no.3
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• pp.67-76
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• 2018

Purpose: The purpose of this study was to evaluate the quality of chest compressions and ventilation when using an mechanical device(LUCAS) and 2-men manual cardiopulmonary resuscitation(CPR) performed on a minikin, as well as to propose a more effective CPR method during transit. Methods: Data were collected by LUCAS and manual virtual reality based ambulance simulation. Analysis was performed using SPSS software 12.0. The average and standard deviation of chest compression depth and ventilation were analyzed using descriptive statistics and t-test. Results: In the virtual reality based LUCAS and manual CPR results, LUCAS showed better chest compression and lower incomplete chest release than manual CPR. During CPR with a chest compression-ventilation ratio of 30:2 in virtual reality ventilation with bag-valve mask was able to deliver an adequate volume of breathing. Conclusion: It is suggested that rescuers on ambulance may consider using LUCAS as an alternative to high-quality chest compression during transit.

• Structural Engineering and Mechanics
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• v.70 no.5
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• pp.525-534
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• 2019

An analytical research on buckling of simply supported thin plate with variable thickness under bi-axial compression is presented in this paper. Combining the perturbation technique, Fourier series expansion and Galerkin methods, the linear governing differential equation of the plate with arbitrary thickness variation under bi-axial compression is solved and the analytical expression of the critical buckling load is obtained. Based on that, numerical analysis is carried out for the plates with different thickness variation forms and aspect ratios under different bi-axial compressions. Four different thickness variation forms including linear, parabolic, stepped and trigonometric have been considered in this paper. The calculated critical buckling loads and buckling modes are presented and compared with the published results in the tables and figures. It shows that the analytical expressions derived by the theoretical method in this paper can be effectively used for buckling analysis of simply supported thin plates with arbitrary thickness variation, especially for the stepped thickness that used in engineering widely.

• Steel and Composite Structures
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• v.31 no.2
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• pp.187-199
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• 2019

This paper presents the semi-analytical development of the dynamic instability behavior and the dynamic response of functionally graded (FG) cylindrical shallow shell panel subjected to different type of periodic axial compression. First, in prebuckling analysis, the stresses distribution within the panels are determined for respective loading type and these stresses are used to study the dynamic instability behavior and the dynamic response. The prebuckling stresses within the shell panel are the same as applied in-plane edge loading for the case of uniform and linearly varying loadings. However, this is not true for the case of parabolic loadings. The parabolic edge loading produces all the stresses (${\sigma}_{xx}$, ${\sigma}_{yy}$ and ${\tau}_{xy}$) within the FG cylindrical panel. These stresses are evaluated by minimizing the membrane energy via Ritz method. Using these stresses the partial differential equations of FG cylindrical panel are formulated by applying Hamilton's principal assuming higher order shear deformation theory (HSDT) and von-$K{\acute{a}}rm{\acute{a}}n$ non-linearity. The non-linear governing partial differential equations are converted into a set of Mathieu-Hill equations via Galerkin's method. Bolotin method is adopted to trace the boundaries of instability regions. The linear and non-linear dynamic responses in stable and unstable region are plotted to know the characteristics of instability regions of FG cylindrical panel. Moreover, the non-linear frequency-amplitude responses are obtained using Incremental Harmonic Balance (IHB) method.

• The Korean Journal of Emergency Medical Services
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• v.25 no.3
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• pp.179-188
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• 2021

Purpose: This study aimed to identify effective cardiopulmonary resuscitation methods by comparing the fatigue of rescuers according to various positions in cardiopulmonary resuscitation situations conducted on beds in hospitals. Methods: An experimental study of students in the department of emergency medical service in H University, G Metropolitan City was conducted in four positions for applying chest pressure on mannequins on beds. Results: As a result of measuring the muscle fatigue of four muscle attachments according to the four positions conducted on the bed, the average was 3.4%, the P was significant at 0.001, and the fatigue difference was confirmed to occur depending on the attachment. An analysis of pressure depth by pose revealed that P1, P2, P3, and P4 have a depth of 58.3, 55.1, 56.4, and 56.3 mm, respectively, with P4 having the deepest depth. Conclusion: Among the various postures of the rescuer during cardiopulmonary resuscitation performed on the bed in the hospital, P1 is thought to be the most tiring, although its associated CPR quality is good.

• The Korean Journal of Emergency Medical Services
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• v.26 no.1
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• pp.139-150
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• 2022

Purpose: This protocol aims to improve the simplicity of the existing two-person cardiopulmonary resuscitation (CPR) by focusing on chest compressions and artificial respiration, and classifying the roles within the scope that can be observed. Methods: In this study, the protocol was developed by forming an expert group consisting of a professor from the emergency and rescue department, a professor from the nursing department, and a first aid officer from the fire department. In addition, if the number of panels is 15 and the derived content validity ratio (CVR) value exceeds 0.49, a reference point that satisfies content validity at 95% reliability is presented. Results: All 11 performance items exceeded the CVR value of 0.49 to meet the reference point, and the CVR range of this protocol is 0.625 to 1.000. Conclusion: In order to improve the quality of three-person CPR, verification of simulation models and continuous protocol revision should be conducted by individuals specializing in various fields.

• Journal of the Korean Society of Radiology
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• v.6 no.3
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• pp.217-226
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• 2012

This study examines image quality of medical image after compression using JPEG2000 for AAPM CT Performance Phantom in PACS. The compressed images of 15:1 showed change of 1.93% and 0.81% in the CT number of water and the slice thickness, respectively, compared to the original images. The variation of the uniformity did not give a correlation for each measured area. In noise measurements at compressions of 10:1 and 15:1, changes of 1.47% to 10.99% were observed, respectively. The noise showed incremation tendency as increasing over the compression ratio 15:1, and the noise of 81.68% was measured at a compression of 40:1. CT number, uniformity, slice thickness, spatial resolution and contrast resolution for the compressed images were slightly changed by increasing the compression ratio. However, the noise was seriously changed relatively at the compressed images. Thus the noise was a important factor to determine the compression ration. A compression ratio of 10:1 for the AAPM CT Performance Phantom image was appropriate and could be applied to diagnostic images.

• Journal of Korean Academy of Fundamentals of Nursing
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• v.18 no.2
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• pp.201-209
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• 2011

Purpose: The purpose of this study was to evaluate the learning experience, knowledge, and performance of cardiopulmonary resuscitation (CPR) in newly graduated nurses, and to identify differences related to learning experience. Methods: The participants were 114 new nurses in the hospital. They were asked to complete a questionnaire, which included CPR learning experience. They were evaluated by a written test and a skill test using a manikin and check list. Results: All participants attended CPR lectures and underwent practice while in university. Only 12.28% of participants were taught by a certified Basic Life Support (BLS) instructor. The mean scores of the written and skill tests were $79.82{\pm}12.69$ and $64.41{\pm}11.71$, respectively. The nurses lacked CPR knowledge related to checking breathing, the frequency of 30 chest compressions, compression rate, and automated external defibrillator use. They also lacked skill in performing CPR related to checking breathing and pulse and giving 2 breaths. CPR performance differed according to learning time (p=.047) and BLS educator (p=.029). Conclusion: The findings of this study reveal that CPR performance by newly graduated nurses is poor and suggest that CPR education by trained instructors, practice-based education, and reeducation programs must be provided to newly graduated nurses in the hospital.

• Journal of Biomedical Engineering Research
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• v.37 no.5
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• pp.153-160
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• 2016

This study proposes an algorithm for removal of CPR artifact in order that automated external defibrillator (AED) can effectively diagnose ECG rhythm during cardiopulmonary resuscitation (CPR). Current AED required to interrupt chest compression for reliable rhythm analysis to avoid the effect of artifacts produced by CPR. However even temporarily interruption of chest compression during CPR adversely affects the probability of restoration of spontaneous circulation (ROSC) and survival after the delivery of the shock. Therefore, we proposed a method for removal of CPR artifacts using least mean square (LMS) filter. The removal of the CPR artifacts would enable compressions to continue during AED rhythm analysis, thereby increasing the likelihood of resuscitation success. It was tested on 31 segments of shockable and 300 segments of non-shockable ECG signals recorded from three pigs during CPR. In the result, sensitivity (Se) and specificity (Sp) analysis on the test segments showed values of Se = 3.2%, Sp = 66.0% and Se = 96.8%, Sp = 98.7% in the case of unfiltered and filtered signals during CPR. In conclusion, it was shown that the proposed method can be a useful tool to exactly diagnose the ECG rhythm during the CPR.