• Proceedings of the KSMRM Conference
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• 2002.11a
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• pp.47-49
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• 2002

At present, the trend of magnetic field strength in MRI system is dramatically changing. In early 70, the only low field (<0.5T) was developed. It was technically difficult to develop the high field system. At that time, people believed that the fine MR imaging could not be obtained in the high field MR system due to the magnetic susceptibility effect. However, 1.5T system was evolved at the end of 80, and used for clinical usage. Thus, it was proved that the signal to noise ratio (SNR) could be greatly contribute to enhance the image quality. And, the results of functional MRI and MR spectroscopy could be improved in the higher field MR system. So, 8T system was eventually developed in Ohio State University Hospital at the end of 90. Therefore, there is no doubt that the system with the ultra high magnetic field strength will be developed near future in 21 century.

• Journal of the Korea Computer Industry Society
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• v.4 no.4
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• pp.433-442
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• 2003

The performance of communication systems should be tested against a set of requirements. To this end, noise generation systems are used to generate noise signals with specified characteristics. In recent study, noise generation system using DCT outperforms the conventional noise generation system when a noise model requires complicated PSD(Power Spectral Density) specifications. In this paper low area/power structures of non-DCT block in DCT-based noise generation system are proposed. Simulation results show that the low area structure results in area reduction by 61-64% and the low power structure achieves power reduction by 88-89% except DCT blocks.

• Smart Media Journal
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• v.8 no.4
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• pp.64-71
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• 2019

The performance of an OMR (Optical Music Recognition) system is usually determined by the characterizing features of the input music score images. Low resolution is one of the main factors leading to degraded image quality. In this paper, we handle the low-resolution problem using the super-resolution technique. We propose the use of a deep neural network with instance normalization to improve the quality of music score images. We apply instance normalization which has proven to be beneficial in single image enhancement. It works better than batch normalization, which shows the effectiveness of shifting the mean and variance of deep features at the instance level. The proposed method provides an end-to-end mapping technique between the high and low-resolution images respectively. New images are then created, in which the resolution is four times higher than the resolution of the original images. Our model has been evaluated with the dataset "DeepScores" and shows that it outperforms other existing methods.

• Journal of Astronomy and Space Sciences
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• v.27 no.3
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• pp.253-262
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• 2010

The electrical power system (EPS) of Korean satellites in low-earth-orbit is designed to achieve energy balance based on a one-orbit mission scenario. This means that the battery has to be fully charged at the end of a one-orbit mission. To provide the maximum solar array (SA) power generation, the peak power tracking (PPT) method has been developed for a spacecraft power system. The PPT is operated by a software algorithm, which tracks the peak power of the SA and ensures the battery is fully charged in one orbit. The EPS should be designed to avoid the stress of electronics in order to handle the main bus power from the SA power. This paper summarizes the results of energy balance to achieve optimal power sizing and the actual trend analysis of EPS performance in orbit. It describes the results of required power for the satellite operation in the worst power conditions at the end-of-life, the methods and input data used in the energy balance, and the case study of energy balance analyses for the normal operation in orbit. Both 10:35 AM and 10:50 AM crossing times are considered, so the power performance in each case is analyzed with the satellite roll maneuver according to the payload operation concept. In addition, the data transmission to the Korea Ground Station during eclipse is investigated at the local-time-ascending-node of 11:00 AM to assess the greatest battery depth-of-discharge in normal operation.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.10 no.10
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• pp.1804-1809
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• 2006

The aim of this Paper is to describe the implementation of a low-power digital front-End Design (FED) that will act as the core of a stand-alone Power dissipation methodology. The design of digital integrated circuits is a large and diverse area, and we have chosen to focus on low power FED. Designs are made from synthesized logic, and we need to consider the low power digital FED including input clock, buffer, latches, voltage regulator, and capacitance-to-voltage counter which have been integrated onto hish bandwidth communication chips and system. These single- chip micro instruments, implemented in a 0.12um CMOS technology operate with a single 0.9V supply voltage, and can be used to monitor dynamic and static power dissipation, Vesture, acceleration junction temperature (Tj), etc.

• Journal of Positioning, Navigation, and Timing
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• v.5 no.1
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• pp.11-20
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• 2016

In this paper, a system that can collect GPS L1 C/A, GLONASS G1, and BDS B1I signals with single front-end receiver was implemented using a universal software radio peripheral (USRP) and its performance was verified. To acquire the global navigation satellite system signals, hardware was configured using USRP, antenna, external low-noise amplifier, and external oscillator. In addition, a value of optimum local oscillator frequency was selected to sample signals from three systems with L1-band with a low sampling rate as much as possible. The comparison result of C/N0 between the signal collection system using the proposed method and commercial receiver using double front-end showed that the proposed system had 0.7 ~ 0.8dB higher than that of commercial receiver for GPS L1 C/A signals and 1 ~ 2 dB lower than that of commercial receiver for GLONASS G1 and BDS B1I. Through the above results, it was verified that signals collected using the three systems with a single USRP had no significant error with that of commercial receiver. In the future, it is expected that the proposed system will be combined with software-defined radio (SDR) and advanced to a receiver that has a re-configuration channel.

• ETRI Journal
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• v.42 no.6
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• pp.943-950
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• 2020

We propose 8.2-GHz band radar RFICs for an 8 × 8 phased-array frequency-modulated continuous-wave receiver developed using 65-nm CMOS technology. This receiver panel is constructed using a multichip solution comprising fabricated 2 × 2 low-noise amplifier phase-shifter (LNA-PS) chips and a 4ch RX front-end chip. The LNA-PS chip has a novel phase-shifter circuit for low-voltage operation, novel active single-to-differential/differential-to-single circuits, and a current-mode combiner to utilize a small area. The LNA-PS chip shows a power gain range of 5 dB to 20 dB per channel with gain control and a single-channel NF of 6.4 dB at maximum gain. The measured result of the chip shows 6-bit phase states with a 0.35° RMS phase error. The input P1 dB of the chip is approximately -27.5 dBm at high gain and is enough to cover the highest input power from the TX-to-RX leakage in the radar system. The gain range of the 4ch RX front-end chip is 9 dB to 30 dB per channel. The LNA-PS chip consumes 82 mA, and the 4ch RX front-end chip consumes 97 mA from a 1.2 V supply voltage. The chip sizes of the 2 × 2 LNA-PS and the 4ch RX front end are 2.39 mm × 1.3 mm and 2.42 mm × 1.62 mm, respectively.

• Journal of Industrial Technology
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• v.21 no.B
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• pp.117-123
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• 2001

In a modern control field, a control engineer who has theoretical backgrounds with some practical knowledge is demanded. That is to say, an engineer who can understand and operate the various parts such as modeling, simulation, system analysis, signal processing, statistics, and hardware is required. In order to prove the theoretical backgrounds and operate various hardwares, a lot of experimental devices for students are designed in universities. Since the conventional experimental devices are manufactured abroad and the prices of the devices are too high, it is difficult to have. If a low cost experimental device can be developed, it will be very useful for a control engineering education. In Ibis paper, an experimental rig which has two control inputs and three sensor outputs to control the end point of a flexible beam is designed and manufactured. This rig can be used for a control field education.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 1997.04a
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• pp.817-821
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• 1997

Ever since the nonlinearity of machine tool dynamics was established, researchers attempted to make use of this fact to devise better monitoring, diagnostics and system, which were hitherto based on linear models. Theory of chaos, which explains many nonlinear phenomena comes handy for furthering the analysis using nonlinear model. In this study, measuring system will be constructed using multi-sensor (Tool Dynamometer, Acoustic Emission) in end millingprocess. Then, it will be verified that cutting force is low-dimensional deterministic chaos calculating Lyapunov exponents, Fractal dimension, Embedding dimension. Aen it will be investigated that the relations between characteristic parameter caculated form sensor signal and tool wear.

• Journal of Energy Engineering
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• v.21 no.3
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• pp.221-227
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• 2012

The CANDU 9 shield cooling system was designed and layout with the objective of promoting natural circulation on loss of forced flow. In the present study, the shield cooling natural circulation was analyzed using verified the thermal-hydraulic code when the coolant pump or the heat exchanger was lost. This study showed that thermosyphoning cooled the end shields and prevented the end shields and the reserve water tank from boiling for at least 8 hours on loss of the shield cooling pumps but the heat exchangers still operational. With the loss of both pumps and heat exchangers, the end shields remain subcooled for up to 4 hours. To enhance thermosyphoning, the bypass connection to the line from the reserve water tank should be relocated to a point as low as possible.