• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2015.10a
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• pp.68-70
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• 2015

The four-port coupler circuit consists of input port, isolation port and two output ports. When it inserts a signal at the input port and the isolation port, the magnitude and phase of the output signal at two output ports are decided by the magnitude and phase of the input signal. This paper analyzes the output signal characteristic of two output ports due to the input signal magnitude and phase of two input ports using the typical 4-port coupler circuit, Branchline hybrid coupler and Ring-hybrid coupler. And, it studies about new way to use branchline hybrid coupler and ring-hybrid coupler on the basis of the this information.

• Journal of the Ergonomics Society of Korea
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• v.27 no.4
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• pp.73-83
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• 2008

With a rapid extension of functions in mobile phones, text input method has become very important for mobile phone users. Previous studies for text input methods were focused on Fitts' law, emphasizing expert's behaviors with one-handed text input method. However, it was observed that 97% of Korean mobile phone users input texts with two-hands. Therefore, this study was designed to develop a prediction model of two-handed Hangul text entry method including novice users as well as experts for mobile phone. For this study, Fitts' law was hypothesized to predict experts' movement time(MT) whereas Hick-Hyman law for visual search time was hypothesized to be added to MT for novices. The results showed that the prediction model was well fitted with the empirical data for both experts and novices with less than 3% error rates. In conclusion, this prediction model of two-handed Hangul text entry including novice users was proven to be a very effective model for modeling two-handed Hangul text input behavior for both experts.

• Korean Journal of Agricultural Science
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• v.23 no.2
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• pp.285-300
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• 1996

This study is aimed to provide data of low-input rice cultivation for agricultural policy, to reveal the problems of low-input cultivation through comparing the economic result of low-input cultivation with the common one, to search for solution or mitigation of the problems of low-input cultivation, and to forecast the future prospect of low-input rice cultivation. The following were the results obtained from the survey and analysis. The working hours per 10a inputted 45.4 hours which is 32% more than 34.5 hours of common cultivation. Yield per 10a was 355kg which was 101kg less than 456kg of common cultivation. But the farm received price per kg was 1,984.9 won which was 547.9 won more than 1,436.5 won of common cultivation. Gross receipts per 10a was 704,438 won which was higher than 655,044 won of common cultivation, and management cost was 230,820 won which slightly higher than 188,157 won of common cultivation. Consequently, the income of low-input rice cultivation was 473,617 won which somewhat exceed to 466,887 won of common cultivation.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.19 no.9
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• pp.654-661
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• 2007

This study has been conducted to investigate the pumping characteristics of diffuser-nozzle based thermopneumatic micropumps with different input voltages and frequencies. In this study, the displacements of the membrane have been obtained changing the input voltage and frequency in load-free state because it is very difficult to measure the displacement of the membrane in an actual load state. It has been found that the amplitude of the membrane displacement increases as the input voltage increases. The pressure head of the thermopneumatic micropump increases almost linearly over some range of the input voltage and decreases almost linearly as the frequency increases. Also, the results show that the thermopneumatic micropump can pump the fluid over a certain input voltage. This study can be utilized as basic data for design and evaluation of thermopneumatic micropumps.

• Journal of Power Electronics
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• v.17 no.3
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• pp.632-640
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• 2017

Input series output independent (ISOI) dc-dc converter systems are suitable for high voltage input and multiple output applications with low voltage rating switches. This paper proposes a novel control strategy consisting of one output voltage regulating (OVR) control loop and n-1 (n is the number of modules in the ISOI system) input voltage sharing (IVS) control loops. An ISOI system with the proposed control strategy can be applied to applications where the output loads of each module are the same. Under these conditions, IVS can be achieved and output voltages copying can be realized in an ISOI system. In this control strategy there is only one controller for each module and the design process of the control loops is simple. Since no central controller is needed in the system, modularity of the system is improved. The operation principle of the new control strategy is introduced and the control effect is simulated. Then the output power and voltage characteristics of an ISOI system under this new control strategy are analyzed. The stability of the proposed control strategy is explored base on a Hurwitz criterion, and the design guide line of the control strategy is given. A two module ISOI system prototype is fabricated and tested in the laboratory. Experimental results verify the effectiveness of the proposed control strategy.

• Proceedings of the KIEE Conference
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• 2001.10a
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• pp.180-182
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• 2001

Input Current Correction of Single-Phase Buck Rectifier is studied in the paper. To sinusoidal waveform the input current with a near-unity power factor over a wide variety of operating conditions, the output capacitor is operated with voltage reversibility for the supply by arranging the auxiliary diode and power switching device. Then the output voltage is superposed on the input voltage during on time duration of power switching devices in order to minimize the input current distortion caused by the small input voltage when changing the polarity. The tested setup, using two insulated-gate bipolar transistors(IGBT) and a microcomputer, is implemented and IGBT are switched with 20[kHz], which is out of the audible band. Moreover, a rigorous state-space analysis is introduced to predict the operation of the rectifier. The simulated results confirm that the input current can be sinusoidal waveform with a near-unity power factor and a satisfactory output voltage regulation can be achieved.

• Journal of Welding and Joining
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• v.7 no.3
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• pp.44-54
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• 1989

This study was undertaken to evaluate the allowable welding heat input range for high strength steels manufactured by various processes and to compare the weldability of TMCP steel for high heat input welding with that of conventional Ti-added normalized steel. The allowable welding heat input ranges for conventional 50kg/$mm^2$ steel to guarantee D or E grade of ship structural steel were below 150 and 80kJ/cm respectively. Such a limit in welding heat input was closely related with the formation of undesirable microstructures, such as grain boundary ferrite and ferrite side plate in the coarse grain HAZ. In case of 60 and 80kg/$mm^2$ quenched and tempered steels, for securing toughness in weldments over toughness requirements for base metal, each welding heat input had to be restricted below 60 and 40kJ/cm, that was mainly due to coarsened polygonal ferrite in weld metal and lower temperature transformation products in coarse grain HAZ. The TMCP steel could be appropriate as a grade E ship hull steel up to 200kJ/cm, but the Ti-added normalized steel could be applied only below 130kJ/cm under the same rule. This difference was partly owing to whether uniform and fine intragranular ferrite microstructure was well developed in HAZ or not.

• Journal of Power Electronics
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• v.19 no.6
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• pp.1380-1392
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• 2019

Input filters are very important to matrix converters (MCs). They are used to improve grid side current waveform quality and to reduce the input voltage distortion supplied to the grid side. Due to the effects of the input filter and the output power, the grid side power factor (PF) is not at unity when the input power factor angle is zero. In this paper, the displacement angle between the grid side phase current and the phase voltage affected by the input filter parameters and output power is analyzed. Based on this, a new grid side PF unity compensation method implemented in the indirect space vector pulse width modulation (ISVPWM) method is presented, which has a larger compensation angle than the traditional compensation method, showing a higher grid side PF at unity in a wide output power range. Simulation and experimental results verify that the analysis of the displacement angle between the grid side phase current and the phase voltage affected by the input filter and output power is right and that the proposed compensation method has a better grid side PF at unity.

• Journal of the HCI Society of Korea
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• v.12 no.4
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• pp.37-44
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• 2017

Eye-typing is one kind of human-computer interactive input system which is implemented by location data of gaze. It is widely used as an input system for paralytics because it does not require physical motions other than the eye movement. However, eye-typing interface based on Korean character has not been suggested yet. Thus, this research aims to implement the eye-typing interface optimized for Korean. To begin with, design objectives were established based on the features of eye-typing: significant noise and Midas touch problem. Multilevel input system was introduced to deal with noise, and an area free from input button was applied to solve Midas touch problem. Then, two types of eye-typing interfaces were suggested on phonological consideration of Korean where each syllable is generated from combination of several phonemes. Named as consonant-vowel integrated interface and separated interface, the two interfaces are designed to input Korean in phases through grouped phonemes. Finally, evaluation procedures composed of comparative experiments against the conventional Double-Korean keyboard interface, and analysis on flow of gaze were conducted. As a result, newly designed interfaces showed potential to be applied as practical tools for eye-typing.

• Proceedings of the KIPE Conference
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• 2000.07a
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• pp.237-240
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• 2000

A new control method using average comparison strategy have been proposed in this paper. This control method realizes sinusoidal input and output current. unity input displacement factor regardless of load power factor. Moreover compensation of the asymmetrical and harmonic containing input voltage is sautomatically realized and calculation time of control function is reduced.