• Proceedings of the KIEE Conference
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• 2011.07a
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• pp.143-144
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• 2011

Due to enhanced demands on quality, security and reliability of the electric power energy system, a microgrid has become a subject of special interest. In this paper, output characteristics of energy storage system (ESS) with an electric double layer capacitor (EDLC) and battery energy storage system (BESS) of a renewable energy based microgrid were analyzed under grid-connected and islanded operation modes. The microgrid which consists of photovoltaic and wind power turbine generators, diesel generator, ESS with an EDLC, BESS and loads was modeled using real time digital simulator. The results present the effective control patterns of the microgrid system.

• Proceedings of the KIEE Conference
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• 1998.07f
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• pp.2051-2053
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• 1998

In spite of nonlinear or step-changing load and line disturbances, the inverter for the UPS must provide the pure sinusoidal output voltage with low THD(Total Harmonics Distortion). This paper proposes an inverter controller for the UPS which has a good dynamic response characteristic and robustness for applying industrial world directly. The inverter output voltage is controlled instantaneously with a double regulation loop by a TMS320C31 Digital Signal Processor so that it has very good dynamic response for nonlinear or step-changing load and line disturbances. To improve the voltage utilization and response characteristics, the Space Vector Modulation(SVM) technique is adapted for the switching method of this system. The characteristics of the proposed control system were verified by simulations and experiments.

• Proceedings of the KIEE Conference
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• 2006.07a
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• pp.68-69
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• 2006

A new type of simulation training system for power system operation is presented in this paper It is based on transmission mimic board, double screen PC, mimic control panel, and real-time digital simulator, KEPS. The operating simulation includes the simulations of the control panel interface and the simulator. The mimic board displays transmission network summary information using a software view of the hardware based mimic board. The symbols, numbers and colors layout exactly match those of the KEPS draft case to provide operators a familiar and effective starting point. This paper describes the development of an innovative training system, utilizing the benefits of 3 dimension visualization s/w and communication-control s/w to create the appropriate operational environment and allow simulation of various power system operations without the restrictions of other training methods. Experiences gained in developing concepts and meeting considerable s/w challenges are outlined, and the potential of the simulator for future operations training discussed.

• JSTS:Journal of Semiconductor Technology and Science
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• v.17 no.1
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• pp.110-119
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• 2017

This paper describes a CMOS image sensor (CIS) with dual correlated double sampling (CDS) and column-parallel analog-to-digital converter (ADC) and its measurement method using a field-programmable gate array (FPGA) integrated module. The CIS is composed of a $320{\times}240$ pixel array with $3.2{\mu}m{\times}3.2{\mu}m$ pixels and column-parallel 10-bit single-slope ADCs. It is fabricated in a $0.11-{\mu}m$ CIS process, and consumes 49.2 mW from 1.5 V and 3.3 V power supplies while operating at 6.25 MHz. The measured dynamic range is 53.72 dB, and the total and column fixed pattern noise in a dark condition are 0.10% and 0.029%. The maximum integral nonlinearity and the differential nonlinearity of the ADC are +1.15 / -1.74 LSB and +0.63 / -0.56 LSB, respectively.

• Proceedings of the KSRS Conference
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• 2008.10a
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• pp.324-327
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• 2008

Microwave remote sensing has great potential, especially in monsoon Asia, since optical observations are often hampered by cloudy conditions. The radar backscattering characteristics of rice crop were investigated with a ground-based automatic scatterometer system. The system was installed inside a shelter in an experimental paddy field at the National Institute of Agricultural Science and Technology (NIAST) before transplanting. The rice cultivar was a kind of Japonica type, called Chuchung. The scatterometer system consists of X-band antennas, HP8720D vector network analyzer, RF cables, and a personal computer that controls frequency, polarization and data storage. This system automatically measures fully-polarimatric backscattering coefficients of rice crop every 10 minutes, accompanied by a digital camera that takes pictures in a fixed position with the same interval. The backscattering coefficients were calculated by applying a radar equation. Plant variables, such as leaf area index (LAI), biomass, plant height and weather conditions were measured periodically throughout the rice growth season. We have performed polarimetric decomposition of paddy data such as single, double and volume scattering to extract the scattering information effectively. We investigated the relationships between backscattering coefficients and the plant variables.

• Journal of the Korean Institute of Telematics and Electronics T
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• v.36T no.2
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• pp.32-41
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• 1999

The design method that the structure of double actuators of read-only or read-writable DVD optical pick-up of high density can be compact into the structure of one actuator, is proposed. The designed actuator has the structure of the shaft sliding type in which the moving part can be rotated about the shaft accord to a used optical disc and an objective lens can be switched, and is suspended with magnetic spring. In this actuator, Coulomb's friction is used as damping force and the moving part is designed by finite element method so that the second natural vibration mode can not occur within the servo band. The mock-up of the actuator designed in this paper is made, and its dynamic characteristics is measured and estimated.

• Archives of Plastic Surgery
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• v.33 no.1
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• pp.67-74
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• 2006

Palatoplasty using Furlow's double-opposing Z-plasty has been performed from June, 1995 to September, 1999 at Seoul National University Children's Hospital. The goal of this study is to determine the optimal timing of repair and cleft severity affecting velopharyngeal function. This is the retrospective study of patients operated by the second author. The mean age of patients was 10.53 months. The patients could be divided into three groups-isolated cleft palate(n=70), unilateral cleft lip and palate(n=88), and bilateral cleft lip and palate(n=42). To evaluate the velopharyngeal function, we used two parameters, speech evaluation and cineofluorography using DSR(digital subtraction radiography). Also, to determine the relevance between cleft severity and speech development, we measured the distance between maxillary tuberosities and cleft margins. Among 200 patients, about 96% had no or minimal hypernasality and 87% had no or mild nasal emission. The cleft width and length of soft palate seemed not to be related with the speech development. Palatoplasty at the age under 12 months resulted in less 'nasal emission' and better 'articulation' of the parameters that were assessed at the age of 7 years. It can be concluded Furlow palatoplasty shows satisfactory results and also it seems that it is better to perform the operation before the age of 12 months.

• Korean Journal of Remote Sensing
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• v.34 no.1
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• pp.17-24
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• 2018

Grounding line of a glacier or ice shelf where ice bottom meets the ocean is sensitive to changes in the polar environment. Recent rapid changes of grounding lines have been observed especially in southwestern Antarctica due to global warming. In this study, ERS-1/2 and Sentinel-1A Synthetic Aperture Radar (SAR) image were interferometrically acquired in 1996 and 2015, respectively, to monitor the movement of the grounding line in the western part of Ronne Ice Shelf near the Antarctic peninsula. Double-Differential Interferometric SAR (DDInSAR) technique was applied to remove gravitational flow signal to detect grounding line from the interferometric phase due to the vertical displacement of the tide. The result showed that ERS-1/2 grounding lines are almost consistent with those from Rignot et al. (2011) which used the similar dataset, confirming the credibility of the data processing. The comparison of ERS-1/2 and Sentinle-1A DDInSAR images showed a grounding line retreat of $1.0{\pm}0.1km$ from 1996 to 2015. It is also proved that the grounding lines based on the 2004 MODIS Mosaic of Antarctica (MOA) images and digital elevation model searching for ice plain near coastal area (Scambos et al., 2017), is not accurate enough especially where there is a ice plain with no tidal motion.

• Journal of the Institute of Electronics Engineers of Korea SP
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• v.44 no.5
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• pp.11-19
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• 2007

This paper presents an objective video quality evaluation method for digital mobile video. The proposed method is to objectify subjective quality by extracting edge region feature metric and blockiness effect. To evaluate performance of proposed algorithm, we carried out subjective video qualify test with the DSCQS method and obtained mean opinion score(MOS) values for CIF/QCIF 140 video clips. We compared error of proposed method with that of existing. The experiment results show that the proposed method has 25% higher performance.

• Transactions of the Society of Information Storage Systems
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• v.10 no.2
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• pp.50-54
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• 2014

Object image using DRPE(Double Random Phase Encryption) in 4f system is encrypted by space-division method using amplitude mask. However, this method has the weakness for the case of having partial data of amplitude mask which can access the original image. To improve the security, we propose the method using the 2-dimension logistic chaos function which shuffles the encrypted data. It is shown in simulation results that the proposed method is highly sensitive to chaos function parameters. To properly decrypt from shuffled encryption data, below 1e-5 % errors of each parameter should be required. Thus compared with conventional method the proposed shows the higher security level.