• The Academic Congress of Korean Shoulder and Elbow Society
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• 2007.03a
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• pp.27-27
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• 2007

• Journal of radiological science and technology
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• v.29 no.2
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• pp.57-62
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• 2006

Purpose : This study was to understand about the measurement of shoulder motion fraction and motion ratio. We proposed the radiological criterior of glenohumeral and scapulothoracic movement ratio. Materials and Methods : We measured the motion fraction of the glenohumeral and scapulothoracic movement using CR(computed radiological system) of arm elevation at neutral, 90 degree, full elevation. Central ray was $15^{\circ},\;19^{\circ},\;22^{\circ}$ to the cephald for the parallel scapular spine, and the tilting of torso was external oblique $40^{\circ},\;36^{\circ},\;22^{\circ}$ for perpendicular to glenohumeral surface. Healthful donor of 100 was divided 5 groups by age(20, 30, 40, 50, 60). The angle of glenohumeral motion and scapulothoracic motion could be taken from gross arm angle and radiological arm angle. We acquired 3 images at neutral, $90^{\circ}$ and full elevation position and measured radiographic angle of glenoheumeral, scapulothoracic movement respectively. Results : While the arm elevation was $90^{\circ}$, the shoulder motion fraction was 1.22(M), 1.70(W) in right arm and 1.31, 1.54 in left. In full elevation, Right arm fraction was 1.63, 1.84, and left was 1.57, 1.32. In right dominant arm(78%), $90^{\circ} and Full motion fraction was 1.58, 1.43, in left(22%) 1.82, 1.94. In generation 20, $90^{\circ} and Full motion fraction was 1.56, 1.52, 30' was 1.82, 1.43, 40' was 1.23, 1.16, 50' was 1.80, 1.28, 60' was 1.24, 1.75. There was not significantly by gender, dominant arm and age. Conclusion : The criterior of motion fraction was useful reference for clinical dignosis the shoulder instability.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.20 no.2
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• pp.157-167
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• 2008

The aeration of an overtopping wave on a vertical structure generated by a plunging wave was investigated through laboratory measurements of void fraction. The overtopping wave occurring after wave breaking becomes multi-phased and turbulent with significant aeration, so that the void fraction of the flow is of importance. In this study, fiber optic reflectometer and bubble image velocimetry were employed to measure the void fraction, velocity, and layer thickness of the overtopping flow. Mean properties were obtained by ensembleand time-averaging the repeated instantaneous void fractions and velocities. The mean void fractions show that the overtopping wave is very high-aerated near the overtopping wave front and relatively low-aerated near the deck surface and rear free surface of the wave. The flow rate and momentum of the overtopping flow estimated using the measured data show that the void ratio is an important parameter to consider in the multiphase flow. From the similarity profiles of the depth-averaged void fraction, velocity, and layer thickness, one-dimensional empirical equations were obtained and used to estimate the flow rate and momentum of the overtopping flow.

• Clinics in Shoulder and Elbow
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• v.1 no.2
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• pp.221-229
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• 1998

We measured, with manual goniometer, the active and passive arc of motion of the shoulder in 31 healthy male subjects who were right-hand dominant and who ranged in age from twenty to thirty-one years. Among ten directions through the four motion plane, the range of motion on the dominant side were significantly smaller than those on the non-dominant side in the motion of six directions. We also measured the motion fraction of the glenohumeral and scapulothoracic movement using fluoroscope in 30-degree intervals of arm elevation in the scapular plane. The ratio of glenohumeral to scapulothoracic movement(θGH/θST) was 1.6 for the full range of motion in scapular plane. At the lower angles of abduction, scapulothoracic movement was slight compared with glenohumeral movement. The motion fraction of scapulothoracic joint was increased from 60-degree to 150 degree of arm angle especially between 120 to 150 degree. During arm elevation, scapula was also extended from 42 degrees to 20 degrees tilting as well as internal rotation. The measuring technique of glenohumeral to scapulothoracic movement(θGH/θST) with fluoroscopy could be applied to the simple radiographic measurement at the out-patient clinic in order to identify the pathology and recovery of shoulder motion after treatment.

• Proceedings of the Korean Vacuum Society Conference
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• 2010.08a
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• pp.133-133
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• 2010

중성입자빔 입사장치(neutral beam injection, NBI)의 중성빔 에너지 효율은 이온원의 수소 이온밀도 분율이 결정한다. 이온원에서 만들어진 $H^+$, $H_2^+$ 그리고 ${H_3}^+$는 중성화 과정(neutralization) 중 해리(dissociation) 때문에 각각 입사 에너지의 1, 1/2 그리고 1/3을 가진 중성입자가 된다. 중성빔 에너지 효율 제고하기 위해서는 이온원의 전체 이온 중 단원자 수소 이온 밀도 증가가 필요하다. 유도결합형 수소 플라즈마 이온원에서 RF 안테나 주파수에 따른 플라즈마 밀도와 단원자 수소 이온 밀도 비율 변화를 관찰하였다. RF 플라즈마에서 가스 압력이 결정하는 전자의 운동량 전달 충돌 주파수 대비 높은 RF 안테나 주파수(13.56 MHz)와 낮은 RF 안테나 주파수(수백 kHz)의 전력을 인가하였으며, Langmuir 탐침, 안테나 V-I 측정기 그리고 QMS(quadrupole mass spectrometer)을 이용하여 플라즈마 특성을 진단하였다. 플라즈마 밀도와 수소 이온 밀도 분율은 플라즈마 가열 메커니즘과 수소 플라즈마 내 반응 메커니즘에 의해 결정된다. 플라즈마 가열 메커니즘에 따른 실험 결과에 대한 RF 안테나 주파수 효과는 플라즈마 트랜스포머 회로 모델을 통해 해석하였으며, 수소 플라즈마 내 반응은 0-D 정상 상태의 입자 및 전력 평형 방정식 결과로 해석하였다.

• Proceedings of the Korean Nuclear Society Conference
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• 1995.05a
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• pp.531-537
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• 1995

본 논문에서는 증기폭발의 전파과정을 해석하기 위한 수학적 모델을 제시하였다. 이 모델은 용융물, 용융파편, 그리고 냉각재 기상과 액상 둥 4상 유체의 2차원적인 천이거동을 지배방정식 및 관련상관식의 수치적 해를 구함으로써 증기폭발의 전파속도 및 폭발압력 등을 예측할 수 있다. 모델에 사용된 주요 상관식은 용융물 분쇄, 냉각재 상변화, 에너지 교환, 그리고 운동량 교환함으로 구성되어 있다. 냉각재의 상태를 결정하는데 있어서 냉각재의 기상과 액상 사이의 열역학적인 비평형을 허용할 수 있도록 냉각재의 상태방정식을 구성하였다. 주석/물의 증기폭발에 대한 예제계산을 수행한 결과 폭발의 전파속도 및 압력 등에 있어서 합당한 것으로 밝혀졌다. 또한 중요한 초기변수(중기 분율, 용융물 분율) 및 관련상관식에 대한 민감도 분석을 수행함으로써 모델개선을 위한 중요인자를 제시하였다.

• Journal of the Korean Society of Propulsion Engineers
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• v.11 no.2
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• pp.37-46
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• 2007

In this study, combustion fields of the end-burning hybrid combustor with tangential oxidizer injectors are examined. Momentum ratio of oxidizer is used as a main parameter to analyse the combustion efficiency with temperature, pressure, swirl velocity and mixture fraction field. It was found that as momentum ratio decreases the overall combustion efficiency is enhanced with the pressure field being insensitive to momentum ratio keeping quasi-uniform distribution. Irrespective to the momentum ratio, annular hot region commonly occurred in the upper combustion chamber where this phenomenon was left for a future improvement to be followed.

• Journal of the Korean Society of Marine Environment & Safety
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• v.24 no.5
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• pp.611-618
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• 2018

In this study, numerical analysis of solid-liquid two-phase flow was conducted as a preliminary step to analyze the flow characteristics of drilling fluid using the commercial CFD code, ANSYS CFX 14.5. The homogeneous model and separated flow model were used to simulate solid-liquid two-phase flow phenomena. In the separated flow model, Gidaspow's drag force model was applied with the kinetic theory model was applied for solid particles. The validity of the numerical model used in this study was verified based on the published experimental results. Numerical analysis was carried out for volume fractions of 0.1 to 0.5 and velocities of 1 to 5 m/s in a horizontal tube with a diameter of 54.9 mm and a length of 3 m. The Pressure drop and volume fraction distribution of solid particles were confirmed. The pressure drop was predicted using the homogeneous model and separated flow model within the MAE of 17.04 % and 8.98 %, respectively. A high volume fraction was observed in the lower part of the tube, and the volume fraction decreased toward the upper part. As velocity increased, variations in volume fraction distribution at varying heights were decreased, and the numerical results predicted these flow characteristics well.

• Clean Technology
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• v.27 no.1
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• pp.93-103
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• 2021

As the seriousness and necessity of responding to climate change and reducing carbon emissions increases, countries around the world are continuing their efforts to reduce greenhouse gases. Among various efforts, research on CCUS, capturing and utilizing carbon dioxide generated when using carbon-based fuels, is actively being conducted. Studies on pressurized oxy-fuel combustion (POFC) that can be used with CCUS are also being conducted by many researchers. The purpose of this study is to analyze basic information related to the flame structure and pollutant emissions of pressurized oxy-fuel combustion. For this, a counter-flow diffusion flame model was used to analyze the combustion characteristics according to pressure and oxygen concentration. As the pressure increased, the flame temperature increased and the flame thickness decreased due to a reaction rate improvement caused by the activation of the chemical reaction. As oxygen concentration increased, both the flame temperature and the flame thickness increased due to an improvement to the reaction rate and diffusion because of a change in oxidizer momentum. Analyzing the related heat release reaction by dividing it into three sections as the oxygen concentration increased showed that the chemical reaction from the oxidizer side was subdivided into two regions according to the mixture fraction. In addition, the emission index of NO classified according to the NO formation mechanism was analyzed. The formation trend of NO according to each analysis condition was presented.

• Sleep Medicine and Psychophysiology
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• v.24 no.1
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• pp.24-31
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• 2017

Objectives: Periodic limb movement disorder (PLMD) has been debated with regard to its clinical significance and diagnostic criteria. The current diagnostic criterion for PLMD in adults has been changed from periodic limb movement index (PLMI) > 5/hour to PLMI > 15/hour by the International Classification of Sleep Disorders (ICSD). In this study, we aimed to investigate the changes in polysomnographic sleep variables according to PLMI and to determine the relevance of the diagnostic criterion for PLMD. Methods: Out of 4195 subjects who underwent standard polysomnography, we selected 666 subjects (370 males and 296 females, aged $47.1{\pm}14.8$) who were older than 17 years and were not diagnosed with primary insomnia, sleep apnea, narcolepsy, or REM sleep behavior disorder. Subjects were divided into three groups according to PLMI severity: group 1 ($PLMI{\leq}5$), group 2 (5 < $PLMI{\leq}15$), and group 3 (PLMI > 15). Demographic and polysomnographic sleep variables and Epworth sleepiness scale (ESS) were compared among the three groups. Results: There were significant differences among the three groups in age and gender. Sleep efficiency (SE) and stage 3 sleep percentage in group 1 were significantly higher than those in groups 2 and 3. The wake after sleep onset (WASO) score in group 1 was significantly lower than those in groups 2 and 3. However, there were no significant differences in SE, stage 3 sleep percentage, or WASO between groups 2 and 3. Sleep latency (SL) in group 1 was significantly lower than that in group 3, but there was no difference in SL between group 2 and group 3. ESS score in group 1 was significantly higher than that in group 3, but there was no difference between group 2 and group 3. Partial correlation analysis adjusted by age showed that PLMI was significantly related to SE and WASO. Conclusion: This study suggests that PLMI influences polysomnographic sleep variables. In addition, we found the individuals who did not have PLMD but had PLMI > 5 were not different in polysomnographic sleep variables from the individuals who had PLMD according to the current criterion. These results raise questions about the relevance of the current diagnostic criterion of PLMD.