• Journal of the Korea Safety Management & Science
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• v.17 no.3
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• pp.363-370
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• 2015

In this paper, the control technique of the stepping motor using back electromotive force(B-EMF) without encoder is investigated. The stepping motor generally uses the rotary encoder to detect the rotor position. Since this method increases the cost and the motor configuration size, the new closed-loop control method applied for the B-EMF was implemented by using current detect circuit, AD-converter, and micro controller unit(MCU). The control loop of stepping motor became very simplified. The current change of stepping motor measured by the amplifier was measured and analyzed, when the missing step is occurred. Based on the data from current feedback, position errors were compensated and confirmed by using AD-converter.

• The Journal of Korean Association of Computer Education
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• v.7 no.6
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• pp.141-150
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• 2004

The method of reusing the environmental data which is previously modelled in modeling and simulation is very important. So, we need an environmental data representation and interchange mechanism which satisfies the requirements of sharing. The SEDRIS STF(SEDRIS Transmittal Format) provides environmental data users and producers with a clearly defined interchange specification. In this paper, We design and implement an automatic converter which converts commercial data(Maya) format to standard interchange format and vice verse without losing semantic of information content using SEDRIS standard interchange format.

• ETRI Journal
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• v.41 no.6
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• pp.760-770
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• 2019

Based on the growing demand for neural network technologies, various neural network inference engines are being developed. However, each inference engine has its own neural network storage format. There is a growing demand for standardization to solve this problem. This study presents interworking techniques for ensuring the compatibility of neural networks and data among the various deep learning frameworks. The proposed technique standardizes the graphic expression grammar and learning data storage format using the Neural Network Exchange Format (NNEF) of Khronos. The proposed converter includes a lexical, syntax, and parser. This NNEF parser converts neural network information into a parsing tree and quantizes data. To validate the proposed system, we verified that MNIST is immediately executed by importing AlexNet's neural network and learned data. Therefore, this study contributes an efficient design technique for a converter that can execute a neural network and learned data in various frameworks regardless of the storage format of each framework.

• Journal of Korean Society of Water and Wastewater
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• v.29 no.5
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• pp.565-573
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• 2015

The influencing factors to remove phosphate were evaluated by converter slag (CS). Experiments were performed by batch tests using different CS sizes and column test. Solutions were prepared at the different pH and concentrations. The maximum removal efficiency was obtained over 98% with the finest particle size, $CS_a$ within 2 hours in batch tests. The removal efficiency was increased in the order of decreasing size with same amount of CS for any pH of solutions. The adsorption data were well fitted to Freundlich isotherm. From the column experiment, the specific factors were revealed that the breakthrough removal capacity (BRC) $x_b/m_{cs}$, was decreased by increasing the influent concentration. The breakthrough time, tb was lasted shorter as increasing the influent concentration. The pH drop simultaneously led to lower BRC drop during the experimental hours. The relation between the breakthrough time and the BRC to influent concentration was shown in the logarithmic decrease. Results suggested that the large surface area of CS possessed a great potential for adsorptive phosphate removal. Consequently particle size and initial concentration played the major influencing factors in phosphate removal by converter slag.

• Journal of Power Electronics
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• v.17 no.3
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• pp.601-609
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• 2017

Gallium nitride (GaN) power switching devices are promising candidates for high switching frequency and high efficiency power conversion due to their fast switching, low on-state resistance, and high-temperature operation capability. In order to facilitate the use of these new devices better, it is required to investigate the device characteristics and performance in detail preferably by comparing with various conventional silicon (Si) devices. This paper presents a comprehensive study of GaN high electron mobility transistor (HEMT) based non-isolated point-of-load (POL) synchronous buck converter operating at 2.7 MHz with a high step-down ratio (24 V to 3.3 V). The characteristics and performance of GaN HEMT and three different Si devices are analytically investigated and the optimal operating point for GaN HEMT is discussed. Zero-voltage switching (ZVS) is implemented to minimize switching loss in high switching frequency operation. The prototype circuit and experimental data support the validity of analytical and simulation results.

• Journal of the Korea Institute of Military Science and Technology
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• v.14 no.5
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• pp.818-824
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• 2011

In this paper, we proposed a phase noise model of a frequency synthesizer for a radar system. Especially, it was proposed a phase noise model in a DAS(Direct Analog Synthesizer) and a frequency up converter system using Leeson's model. The proposed phase noise model was derived from the measurement data of model 1 and evaluated by adapting to model 2 and model 3 frequency synthesizers. The prediction phase noise by modeling was totally matched to the measured data and the effective analysis of the phase noise was done in a frequency synthesizer and a frequency converter of radar system.

• Journal of Biomedical Engineering Research
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• v.7 no.2
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• pp.133-138
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• 1986

Abstract In a conventional digital sector scan system in the ultrasound medical imaging, the sampling space is in the polar coordinates while the display space is in the cartesian coordinates, which necessitates a coordinate transformation process resultion process resulting the overall system very complex and bulky. In this paper we propose a new architecture of the Digital-Scan-Converter (DSC) for the ultrasound sector scan system in which sampling space is the same as the display space, so the data are displayed as they are acquired without any interpola- tion process required. To implement the above real time DSC. two frequency synthesizes with very high switching time and a low-pass filter are required. The former determines the precise location of the data points and the latter fills the gap betw- een pixels in the horizontal direction.

• Proceedings of the KIEE Conference
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• 1987.07b
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• pp.1583-1586
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• 1987

In the study for effective speech control we designed a personal computer system with A/D converter in which the speech signal is transformed by digital data displayed graphically on the moniter and with a D/A converter in which the digital data is transformed into speech signal which people can hear. We analyzed the character of the speech signal produced by the system. We designed the adaptive noise cancel algorithm so that noise and Interference are cancelled whenever the speech signal is recognized by the computer system. This is a basic system for artificial Intelligence.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 1995.11a
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• pp.298-301
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• 1995

In this study, the properties of Thermally Stimulated Current is measured automatic Data Acquisition System with a A/D Converter set. The A/D Converter set is configured with DIO 8255(Intel), AMD 9513 Timer/Counter and some Programed Controllers. Especially, the numerical method of asymtotic estimation to separate single relaxation curve and physical factors related to charged particles were obtained rapidely and completely. As a result, the data obtained by automatic Acquisition System need to be corrected to average value and the whole control and inspectation system is needed.

• Proceedings of the KIEE Conference
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• 2006.04a
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• pp.213-215
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• 2006

A static frequency converter(SFC) in a pumped storage power plant is important equipment for converting electric motor kinetic energy into electric Bower. A SFC monitoring system consists of high voltage thyristor firing equipment, fault detection module, data gathering module, real time data processing equipment and man machine Interface system. This paper describes SFC system overview, developed SFC monitoring system configuration including system characteristics. and successful application result to San-Cheong pumped storage power plant.