• Proceedings of the KIEE Conference
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• 2006.10d
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• pp.129-131
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• 2006

This paper presents a new ZVS-PWM high frequency inverter. The ZVS operation is achieved in the whole load range by using a simple auxiliary reverse blocking switch in parallel with series resonant capacitor. The operating principle and the operating characteristics of the new high frequency circuit treated here are illustrated and evaluated on the basis of simulation results. It was examined that the complete soft switching operation can be achieved even for low power setting ranges by introducing the high frequency dual duty cycle control scheme. In the proposed high frequency inverter treated here, the dual mode pulse modulation control strategy of the asymmetrical PWM in the higher power setting ranges and the lower power setting ones, the output power of this high frequency inverter could introduce in order to extend soft switching operation ranges. Dual duty cycle is used to provide a wide range of output power regulation that is important in many high frequency inverter applications. It is more suitable for induction heating applications the operation and control principle of the proposed high frequency inverter are described and verified through simulated results.

• Journal of Biosystems Engineering
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• v.19 no.4
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• pp.291-300
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• 1994

It is desired to operate tractor engines at or near maximum torque much of the time in field operation to increase fuel efficiency. To do this it is necessary to reduce engine speed and to shift gears to higher ratios as frequently as possible. Because of load variations in most drawbar work and inconvenience in gear shift, however, gear-type transmission are usually set in one ratio at unnecessarily high engine speeds, and engine-torque variations are used to compensate for changes in drawbar load. As a result, the most of time the tractor is not operated efficiently in terms of fuel consumption and work output. The objective of this study was to develop an automatic control system which is able to operate a tractor equipped with gear transmission under the optimal condition in terms of fuel efficiency with automatic governor setting and gear shift. An indoor experimental test set which can be used to simulate tractor operation, control engine speed and transmission ratio was developed in the previous paper. In this paper, the performance of the optimal operation system is reported. Through a series of tests, it was found that the automatic control system for optimal operation of tractors with gear transmission had a satisfactory performance.

• Journal of Chest Surgery
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• v.14 no.3
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• pp.195-201
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• 1981

The results of reconstruction of the lower esophagus with jejunum in a total of 24 cases of primary carcinoma of the lower third esophagus and gastroesophageal carcinoma were presented, and clinical values of substitution for the esophagus with jejunum were also discussed. They were operated in the department of thoracic and cardiovascular surgery, Hanyang University Hospital during the period of 9 years from 1972 to 1981. Surgical managements to lower esophageal reconstruction with jejunum were carded out with not the same procedure in all cases studied, but with three different procedure mentioned below/ In 13 cases of lower third esophagectomy with or without partial `8astrectomy of a total of 24 cases, interposition of jejunum between the esophagus and the stomach were performed after the fashion to esophagojejunostomy with mobilized jejunal loops and 8astro-JeJunostomy with side to side anastomosis. In 7 cases of lower third esophagectomy and total gastrectomy, the continuity of the esophagus were performed the fashion to esophagojejunostomy with mobilized jejunum. In 4 cases of unresectable gastro-esophageal carcinoma, bypass operation of the lower esophagus and the stomach were performed after the fashion to esophagojejunostomy with side to and anastomosis. After the bypass operation, it was observed that oral feeding to the patients was excellent. Following these consecutive series of 20 cases of radical operation for lower esophageal carcinomas and 4 cases of bypass operation for unresectable gastroesophageal carcinomas, no complication such as postoperative leakage and stenosis from anastomotic site or Infection In operating area and operative death were observed.

• Journal of Chest Surgery
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• v.14 no.3
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• pp.202-209
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• 1981

The results of reconstruction of the lower esophagus with jejunum in a total of 24 cases of primary carcinoma of the lower third esophagus and gastroesophageal carcinoma were presented, and clinical values of substitution for the esophagus with jejunum were also discussed. They were operated in the department of thoracic and cardiovascular surgery, Hanyang University Hospital during the period of 9 years from 1972 to 1981. Surgical managements to lower esophageal reconstruction with jejunum were carded out with not the same procedure in all cases studied, but with three different procedure mentioned below/ In 13 cases of lower third esophagectomy with or without partial `8astrectomy of a total of 24 cases, interposition of jejunum between the esophagus and the stomach were performed after the fashion to esophagojejunostomy with mobilized jejunal loops and 8astro-JeJunostomy with side to side anastomosis. In 7 cases of lower third esophagectomy and total gastrectomy, the continuity of the esophagus were performed the fashion to esophagojejunostomy with mobilized jejunum. In 4 cases of unresectable gastro-esophageal carcinoma, bypass operation of the lower esophagus and the stomach were performed after the fashion to esophagojejunostomy with side to and anastomosis. After the bypass operation, it was observed that oral feeding to the patients was excellent. Following these consecutive series of 20 cases of radical operation for lower esophageal carcinomas and 4 cases of bypass operation for unresectable gastroesophageal carcinomas, no complication such as postoperative leakage and stenosis from anastomotic site or Infection In operating area and operative death were observed.

• Journal of Chest Surgery
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• v.19 no.3
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• pp.374-380
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• 1986

From June 1983 to September 1984, the pleural biopsies with Cope needle were performed at department of thoracic and cardiovascular surgery, Pusan Paik Hospital, Inje college, on 78 patients for exudative pleural effusion caused by various conditions. These results were analyzed clinically and summarized as follows: 2. The accuracy of pleural biopsy was 69.2% [54 of 78 patients]. The accuracy represented by ratio for the number of biopsy was 63.5% [54 of 85 biopsies]. 3. Among 61 patients of tuberculosis or malignancy, 37 [60.7%] were confirmed by pleural biopsy. 4. Tuberculosis was diagnosed in 48 patients, in 26[54.2%] out of these by pleural biopsy alone, in 3[6.2%] by pleural biopsy and isolation of AFB, in 2[4.2%] by pleural biopsy and operation, in 4[8.3%] by isolation of AFB, in 2[4.2%] by operation, and in 11[22.9%] clinically. 5. Among 13 patients of malignancy, 4[30.8%] were diagnosed by cytology alone, 4[30.8%] by pleural biopsy and cytology alone, 4[30.8%] by pleural biopsy and cytology, 1[7.7%] by pleural biopsy alone, 1[7.7%] by pleural biopsy and operation, and remained 3 by operation, lymph node biopsy, or bronchoscopy respectively. 6. False positive of clinical diagnosis was 12.5% for tuberculosis and 28.6% for malignancy. In pathological diagnosis there was no false positive. So specificity of pleural biopsy was very high. But false negative of pleural biopsy was 29.2% for tuberculosis and 46.2% for malignancy. 7. 4 cases[5.1%] of minimal pneumothorax were in the early series.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.62 no.2
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• pp.149-154
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• 2013

Short term load forecasting for electric power demand is essential for stable power system operation and efficient power market operation. High accuracy of the short term load forecasting can keep the power system more stable and save the power market operation cost. We propose an optimal coefficient selection method for exponential smoothing model in short term load forecasting on weekdays. In order to find the optimal coefficient of exponential smoothing model, load forecasting errors are minimized for actual electric load demand data of last three years. The proposed method are verified by case studies for last three years from 2009 to 2011. The results of case studies show that the average percentage errors of the proposed load forecasting method are improved comparing with errors of the previous methods.

• The Journal of Information Technology
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• v.8 no.3
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• pp.1-10
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• 2005

Cosine and Sine function is widely used for the arithmetic, translation, object drawing, Simulation and etc. of Computer Graphics in Natural Science and Engineering. In general, Cordic Algorithm is effective method since it has relatively small size and simple architecture on trigonometric function generation. However profitably it has those merits, the problem of operation speed is occurred. In graphic display system, the operation result of object drawing is quantized and has the condition that is satisfied with rms error less than 1. So in this paper, the proposed generator is composed of partition operation at each ${\pi}/4$ and basic Cosine, Sine function generator in the range of $0{\sim}{\pi}/4$ using the lower order of Tayler's series in an acceptable error range, that enlarge the range of $0{\sim}2{\pi}$ according to a definition of the trigonometric function for the purpose of having a high speed Cosine, Sine function generation. And, division operator using code partition for divisor three is proposed, the proposed function generator has high speed operation, but it has the problems in the other application parts with accurate results, is need to increase the speed of the multiplication.

• Nuclear Engineering and Technology
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• v.54 no.2
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• pp.644-652
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• 2022

During the pyroprocessing operation, various signals can be collected by process monitoring (PM). These signals are utilized to diagnose process states. In this study, feasibility of using PM for nuclear safeguards of electrorefining operation was examined based on the use of machine learning for detecting off-normal operations. The off-normal operation, in this study, is defined as co-deposition of key elements through reduction on cathode. The monitored process signal selected for PM was cathode potential. The necessary data were produced through electrodeposition experiments in a laboratory molten salt system. Model-based cathodic surface area data were also generated and used to support model development. Computer models for classification were developed using a series of recurrent neural network architectures. The concept of transfer learning was also employed by combining pre-training and fine-tuning to minimize data requirement for training. The resulting models were found to classify the normal and the off-normal operation states with a 95% accuracy. With the availability of more process data, the approach is expected to have higher reliability.

• Geomechanics and Engineering
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• v.34 no.3
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• pp.303-316
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• 2023

With the development and utilization of urban underground space, the artificial ground freezing technology has been widely used in the construction of underground engineering in soft soil areas. The mechanical properties of soft clay changed greatly after freezing and thawing, which affected the seismic performance of underground structures. In this paper, a series of triaxial tests were carried out to study the dynamic response of the freezing-thawing clay under the seismic load considering different dynamic stress amplitudes and different confining pressures. The reduction factor of dynamic shear stress was determined to correct the amplitude of the seismic load. The deformation development mode, the stress-strain relationship and the energy dissipation behavior of the soft clay under the seismic load were analyzed. An empirical model for predicting accumulative plastic strain was proposed and validated considering the loading times, the confining pressures and the dynamic stress amplitudes. The relevant research results can provide a theoretical reference to the seismic design of underground structures in soft clay areas.

• Journal of Advanced Marine Engineering and Technology
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• v.34 no.2
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• pp.332-338
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• 2010

Annually, electrical fires caused by arcing phenomena in power system rapidly increase as the use of more electric appliances, but there is no established method for the prevention of the accidents. With this background, this paper dealt with the experimental results on a series arc detection technique and a device for air conditioners. Series arcing phenomena that is generated in incomplete connection of air conditioners was simulated, and the frequency spectrum was analyzed. The Fast Fourier Transform (FFT) of the arc pulse showed that the dominant frequency components exist in ranges of 190 kHz~250 kHz and 900 kHz~1.6 MHz. An arc detection circuit with low cut off frequency of 170 kHz to attenuate 60 Hz by 170 dB and a signal discriminator were designed. Also, an algorithm which separate series arc signal from unwanted noises produced by switching operation, inverter, and surge was proposed. Application experiment was carried out on several types of air-conditioners by using the arc generator specified in UL1699, and the results showed the over 99 % accuracy.