• The Transactions of the Korean Institute of Electrical Engineers
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• v.36 no.4
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• pp.259-266
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• 1987

In order to drive motor control system precisely, the motor is to be controlled by mmfs and current with sinusoidal waveforms. In this paper the Delta Modulation (DM) Technique is used for generating PWM pulse with sinusoidal waveform. However the motor currents yet contain odd harmonics due to leakage inductances, speed and exitation. To reduce harmonics, the parameter adaptive control method is introduced. That is, Req.C parameter of Delta Modulator is controlled adaptively by parameter adaptor. The adaptive signal is achieved by the difference between motor current and reference waveform, and this signal is converted to the voltage commend signal by adaptive mechanism. The test reslts show that this system is operated smoothly over a wide range of motor speed and motor current is controlled to be sinusoidal waveform adaptively.

• The Transactions of the Korean Institute of Electrical Engineers B
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• v.50 no.5
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• pp.214-220
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• 2001

This paper presents the design schemes for the improvement of force characteristics in a controlled permanent magnet liner synchronous motor (Controlled-PM LSM). The dependence of motor performance on the various design schemes, such as the slot shapes, the magnetization patterns of permanent magnet and the skewing, has been investigated in detail by using finite element method (FEM). The analysis results are verified by the experiment that is performed by a testing machine. From this study, it is known that the skewing of the magnet is the most efficient method in the aspects of detent force reduction and higher force density.

• Proceedings of the KSME Conference
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• 2008.11b
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• pp.2708-2712
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• 2008

The objective of this work is to study various vortical structures from controlled circular jet such as trifurcating and blooming jets. The numerical simulations of flow from a circular jet are carried out at $Re_D=4300$ based on the jet-exit velocity and jet diameter using large eddy simulation with the dynamic Smagorinsky model in a cylindrical coordinate system. The excitation for the controlled jet is achieved by combining axial and helical excitations. The axial velocity controlled by blowing and suction at the jet exit has several peaks in their cycle with respect to ratio of axial to helical excitations. This active control changes the spreading angle and vortical structures in the downstream region.

• Proceedings of the KSR Conference
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• 2000.05a
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• pp.261-268
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• 2000

The purpose of interlocking system was to prevent the route for a train being set up and its protecting signal cleared if there was already another, conflicting route set up and the protecting signal for that route cleared. Recently, the computer based control systems instead of conventional relays circuitry are widely used to industrial systems, therefore, interlocking system are rapidly changing from relay interlocking system to computer controlled interlocking system that control requirements of interlocking at junctions using electronic circuits. However, the reliability of interlocking logic for those systems are harder to demonstrate than in traditional relays circuitry because the faults or errors can not be analyzed and predicted to those systems, In this paper, by examine checking technique of computer controlled interlocking system, we will to acquire interlocking inspection algorithm and method for computer controlled interlocking system

• Journal of the Korea Society of Computer and Information
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• v.28 no.5
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• pp.171-177
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• 2023

This study aims to provide useful information for prevention of doping by investigating and verifying relationships among demographic factors such as athletic career and experience of anti-doping education, controlled motivation, attitude toward anti-doping, perceived behavioral control factors and doping intentions to verify factors affecting doping intentions of domestic elite athletes based on the advance studies that have been carried out various theoretical approaches so far. Method: This study analyzed using SPSS 27.0 program. First, this study confirmed a multicollinearity problem by conducting Pearson's correlation analysis to examine correlation between variables. And this study conducted stepwise multiple linear regression to confirm how the variables affect doping intentions. Result: Study results show that all factors such as athletic career, experience of anti-doping education, controlled motivation, attitude toward anti-doping and perceived behavioral control have a significant impact on doping intentions, and this study verified significant impact by putting variables in order of each influence. As a result of verification, this study confirmed that controlled motivation has the greatest influence, and perceived behavioral control toward doping, experience of anti-doping education, attitude toward and athletic career came next in order.

• Journal of Korean Elementary Science Education
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• v.17 no.2
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• pp.113-121
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• 1998

This study was performed to examine the effects of daily commodities on student's scientific knowledges, inquiring abilities and attitude toward science in elementary school science classes. Daily commodities were collected and sorted properly so as to be readily utilized as experimental instruments in science classes. 164 students of elementary school 5th grade in Taejon City were selected for the study and they were evenly divided into two different groups, one for experiment and the other for comparation respectively. In every science classes throughout the school semester, the experimental group was supplied with daily commodities in addition to conventional instruments while the controlled group for comparation was supplied only with conventional instruments. Student's responses to the questionnaire were treated by statistical analysis and for that purpose the computer programme of SPSS WIN(6.0) was employed. The results of the study are as follows; 1. There is no expressive disparity appeared in the increments of scientific knowledge between experimental and controlled (comparing) groups. 2. The disparity of increments in inquiring ability between experimental and controlled groups is fairly expressive (P<0.05). The experimental group with daily commodities in science classes attained 5% more in increment of inquiring ability than the controlled group. 3. The disparity of the changes in student's attitudes toward science between two groups is remarkable (P<0.001). Student's attitude toward science was much more improved in experimental group than controlled group. The difference in improvement rate between two groups is 8%. The facts mentioned above make it evident that in elementary school science course daily commodities are very effective to enhance student's positiveness as far as both inquiring ability and attitude toward science are concerned. In this respect, a lot of efforts are expected to be made in searching and supplying further the proper daily commodities for elementary science courses. In addition, it is also called for that the examples of replacing conventional instruments with daily commodities will be introduced in future editions of elementary school science book and its guide book if possible.

• Transactions of the Korean Society of Automotive Engineers
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• v.10 no.3
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• pp.192-200
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• 2002

Semi-active suspension systems are greatly expected to be in the mainstream of future controlled suspensions for passenger cars. In this study, a continuous variable damper for a passenger car suspension is developed, which is controlled actively and exhibits high performance with light weight, low cost, and low energy consumption. To get fast response of the damper, reverse damping mechanism is adapted, and to get small pressure change rate after blow-off, a pilot controlled proportional valve is designed and analyzed. The reverse continuous variable damper is designed as a HS-SH damper that offers good body control with reduced transferred input force from tire, compared with any other type of suspension system. The damper structure is designed, so that rebound and compression damping force can be tuned independently, of which variable valve is placed externally. The rate of pressure change with respect to the flow rate after blow-off becomes smooth when the fixed orifice size increases, which means that the blow-off slope is controllable using the fixed orifice size. The damping force variance is wide and continuous, and is controlled by the spool opening, of which scheme is usually adapted in proportional valves. The reverse continuous variable damper developed in this study is expected to be utilized in the semi-active suspension systems in passenger cars after its performance and simplicity of the design is confirmed through real car test.

• Korean Journal of Materials Research
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• v.9 no.7
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• pp.740-747
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• 1999

Grain refinement is the only strengthening mechanism that improves both strength and toughness. Controlled rolling and accelerated cooling techniques have been known to be effective method to improve the mechanical properties by controlling the recrystallization and/or grain coarsening during processing. Repeat phase transformation $(\gamma/\alpha)$ by repeat heat treating is another way of grain refinement. In this study, a combined effect of controlled rolling and repeat heat treating was investigated. To study the effects of Mo addition and process parameters, Mo alloyed low carbon steels were prepared and thermomechanical controlled processes were simulated in the Gleeble system. The Mo addition resulted in an increasement of the grain coarsening temperature and suppress austenite recrystallization. The optimum condition for the refinement of austenite was obtained when the controlled rolling was performed twice with the same heat treatment condition, and reduction ratio of second pass was higher than that of first pass.

• Journal of the Korean Society of Laryngology, Phoniatrics and Logopedics
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• v.22 no.2
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• pp.133-136
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• 2011

Background and Objectives : Previous jet ventilation is not becoming more common because of high price, making loud noise, and causing a movement of the vocal cords due to the jet stream. So we designed a new type of manually controlled jet ventilation using previous laryngoscope and introduced it's clinical application. Materials and Method : A prospective study involved 20 patients all having undergone surgical intervention under new type of manually controlled jet ventilation from June 2009 to January 2011. The prospective study was to assess the vital sign and operative and postoperative complications. Results : The Manually Controlled Jet Ventilation were performed in 20 patients. 50% of the patients have Post-located laryngeal lesion, 20% with tracheal stenosis, 20% with glottic cancer biopsy and laser cordectomy, 10% with postglottic stenosis. Conclusion : Manually Controlled Jet Ventilation (Manujet) can be used for airway surgery.

• Journal of The Korean Society of Agricultural Engineers
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• v.57 no.5
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• pp.29-35
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• 2015

The optimal greenhouse scales for controlled tomato should be studied because the increase of oil price and labor costs following the shortage of workforce makes greenhouse cultivation hard to gain profits. The purpose of this study is to estimate optimal production scales by greenhouse types for controlled tomato. The translog cost function is estimated based on the production cost survey data. The results can be summarized as follows: First, the average production cost of controlled tomato per kg decreases as the production scale increases. Second, according to the tomatoes farm of standard farming income data of RDA, the minimum production scale is 23 ton. Third, the estimated output of single-span greenhouse considering production scale with minimum average cost is 345 ton and production cost per kg is 1,476 won. The corresponding figures of multi-span greenhouse are 415 ton and 936 won, respectively. The study results can be used as basic materials for efficient decision making of tomato farmhouses and novice farmers. Also, the study shows that multi-span greenhouse should be encouraged to be built, since it requires lower marginal cost than single greenhouse. The results of this paper will help increase the income of farmhouses and cut expenses for the coming years.