• Journal of Chest Surgery
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• v.37 no.12
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• pp.1019-1021
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• 2004

Neurogenic tumors are common in posterior mediastinal tumors. In most cases, tumors were accidentally showed on simple chest X-ray. In some cases, they were presented by symptoms which were induced by nerve compression or airway compression. But as in our case, neurogenic tumor with spontaneous hemothorax is very rare. A 45-year-old man admitted to emergency room of other hospital because of acute right chest pain and dyspnea. A chest X-ray showed a right pleural effusion. Hemothorax was diagnosed after closed thoracostomy. Following chest CT showed posterior mediastinal mass. The patient was transferred to our hospital. T spine MRI showed dumbbell shaped mass. Diagostic impression was neurogenic tumor. The pathologic result was neurilemmoma after surgical resection.

• Proceedings of the KSR Conference
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• 2011.10a
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• pp.1707-1714
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• 2011

Since 2010 December, the Gyeongchun line can provide better service than the other modes in respect of cost & time efficiency by operating electric double track from Sangbong station to Chuncheon station. However customers living in the Northern part of capital area, which there are stations of line No.1, have inconvenience to transfering twice to access Gyeongchun line. To minimize inconvenience, this study has analyzed the demand variation of Geongchun line upon changing the terminal of some trains on Gyeongchun line which reduces the number of transfer. In this study, the demand variation has been estimated by the direct demand model considering only saving time between O/D. So some additional modifications are required, because the effect of fare and accession convenience has not been considered.

• The Korean Journal of Emergency Medical Services
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• v.17 no.1
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• pp.9-19
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• 2013

Purpose : The purpose of this study was to investigate the variation of elapsed time in the cardiopulmonary resuscitation (CPR) quality and the fatigue in continuous CPR by single rescuer. This study will provide basic data about the time for the alternation of the CPR providers. Methods : The volunteer students having healthcare provider certification were recruited from the department of emergency medical service. The students performed 30:2 CPR for 20 minutes, and the data were recorded and analyzed. Metrics were based on the 2010 American Heart Association (AHA) Guidelines, and the CPR continued without any feedback. Results : Among the indicators of CPR, the accuracy and the depth of chest compressions decreased after about 5.3 minutes, and the rate increased approximately after 6.8 minutes. Changes in clinical indicators appeared, and fatigue increased after about 3 minutes. According to the increase in fatigue level, the changes in the CPR indicators and clinical indicators showed up, and these results proved to be statistically significant. However, there were no associations among the time, fatigue, and gender. Conclusion : Even though the times of changes in the indicators appeared differently, the times of changes in fatigue and CPR quality were able to be confirmed.

• Journal of Fisheries and Marine Sciences Education
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• v.7 no.1
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• pp.111-126
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• 1995

In general, the electromagnetic transient phenomenon always exists in induction motor(IM) with the torque change. The control performance of IM is very worse than that of D.C motor owing to this transient phenomenon. So many studies about the elimination methods of the transient phenomenon have been making progress. Interesting methods of them are the Field acceleration method(FAM) and the method of impulse addition on the input voltage at the time point of torque change. In this paper, first, the circuit equation of IM is derived from the phase segregation method. The torque equation consisted of the stator and rotor currents is derived from the solving of the circuit equation. As we well known, the transient terms exist in this the torque equation. The method of impulse addition on the input voltage at the instance of torque change is confirmed theoretically for the elimination of the transient phenomenon. With the base on it, the author proposed a real time algorithm to eliminate the transient terms. The control system is consisted of the PI controller with the feedforward of torque change. The author could confirm that the quick stepwise responses of torque and speed can be obtained from response simulations.

• Journal of Agricultural Extension & Community Development
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• v.10 no.1
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• pp.31-42
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• 2003

The purposes of this study were (1) to identify the present situation and pending problems of agricultural education in Agricultural Technology & Extension Center (ATEC), (2) to analyze the satisfaction degree and educational needs of agricultural extension education program, and (3) to draw some implications in the direction of the development direction of agricultural extension, based on the analysis aforementioned. Data were collected through questionnaires from 230 farmers. Based on the results of study, the recommendations were as follows. 1. Increase of income could not guarantee the improvement of QOL. So, ATEC should make some efforts to plan and administer diversified agricultural extension and education programs. 2. Agricultural practice was the most effective educational methods. Especially, for return-migrants and young farmers, applicable educational program should be planned and offered. 3. Education program on agricultural information, especially on the internet use, would be the most attractive program of agricultural extension education in the future.

• Journal of the Korea Convergence Society
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• v.8 no.1
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• pp.173-179
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• 2017

The purpose of this study is to theoretically explore the pedagogical meaning of Flipped Learning (FL) through the lens of Bakhtinnian Dialogism. Flipped learning has emerged based on technological development, which enables educators to reorganize educational space and time. In the new converged time and space, teachers changed the activities in and out of classes, flipped lectures with students' activity, and redefined the role of teachers and students. These dialogical characteristics of FL results in several educational consequences: first, underscoring educational dialogue, second, extending the participation in the dialogical chain, third, deconstructing the existing authority of knowledge, and escalating the self-directedness of learners.

• 한국연소학회:학술대회논문집
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• 2014.11a
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• pp.59-62
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• 2014

Predicting coal combustion by computational fluid dynamics (CFD) requires a combination of complicated flow and reaction models for turbulence, radiation, particle flows, heterogeneous combustion, and gaseous reactions. There are various levels of models available for each of the phenomena, but the use of advanced models are significantly restricted in a large-scale boiler due to the computational costs and the balance of accuracy between adopted models. In this study, the influence of coal devolatilization model and turbulent mixing rate was assessed in CFD for a commercial boiler at 500 MWe capacity. For coal devolatilization, two models were compared: i) a simple model assuming single volatile compound based on proximate analysis and ii) advanced model of FLASHCHAIN with multiple volatile species. It was found out that the influence of the model was observed near the flames but the overall gas temperature and heat transfer rate to the boiler were very similar. The devolatilization rate was found not significant since the difference in near-flame temperature became noticeable when it was multiplied by 10 or 0.1. In contrast, the influence of turbulent mixing rate (constant A in the Magnussen model) was found very large. Considering the heat transfer rate and flame temperature, a value of 1.0 was recommended for the rate constant.

• Journal of Advanced Marine Engineering and Technology
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• v.34 no.1
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• pp.92-101
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• 2010

Recently, the magnetic bearings which have many advantages such as no noise, less mechanical friction are widely applied to the suspension of rotors on the rotary machineries. However, the magnetic bearing system is inherently unstable, nonlinear and MIMO(multi-input-multi-output) system as well. In this paper, we design a state feedback controller using linear matrix inequality(LMI) to the multi-objective synthesis, for the magnetic bearing system with integral type servo system. The design objectives include $H_{\infty}$ performance, asymptotic disturbance rejection, and time-domain constraints on the closed-loop pole location. The results of computer simulation show the validity of the designed controller.

• Proceedings of the KIEE Conference
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• 1996.07a
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• pp.267-269
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• 1996

Servo systems became indispensable to applications such as industrial robots and numerically controlled machinery. Especially, induction motor drives are widely used as ac-servo system owing to the fact that it is maintenance-free. At the present time, Quick torque control methods such as vector control have been employed that enables an induction motor to attain as quick torque response as a dc motor. However, these methods can not be realized without knowing several motor parameters accurately, because the methods need them to calculate flux or voltage command. Most of all, secondary resistance has to be identified accurately, because it's value varies greatly for operation of induction motors. In this paper, a new identification method of secondary resistance based on quick torque control system of induction motors is proposed. The proposed method is derived theoretically from motor circuit equation and can be realized very simply by detecting primary current and voltage command of the motor. Through the numerical simulation considered using PWM inverter, the validity of the proposed method was successfully confirmed.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.19 no.6
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• pp.657-662
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• 2008

Inter-radar interferences may cause the critical impact to the radar detection performance because radar operates with high power and wideband. In this paper, the international criteria for radar interference protection is reviewed based on the ITU-R recommendation, and the radar interference analysis model is presented by taking into account the radar operating environments such as ground, airborne and spaceborne radars. Finally, the simulation results are presented with the interference Impact analysis in various radar environments.