• Journal of Korea Society of Industrial Information Systems
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• v.18 no.5
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• pp.73-80
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• 2013

Recently, Li-ion battery is regarded as a potential energy storage device in the lime light and it can supply power to the satellite very effectively during eclipse. Because it has better features as high voltage range, large capacity and small volume than any other battery. Generally, multi cells are connected in series to use Li-ion batteries in satellite application. Since the internal resistance of cells is different each other, voltage in some cells can be overcharged or undercharged, so capacity of the cell is reduced and the life of whole battery pack is decreased. Therefore, a voltage balancing circuit with Fly-back converter is proposed and the voltage equalization of each cell is verified the prototype in this paper.

• Journal of Digital Convergence
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• v.18 no.5
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• pp.485-495
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• 2020

The purpose of this study was to examine the role of self-esteem (SE) and cooperation (CO) in the effect of parental attitudes (PA) as perceived by children on the quality of peer relationships (PR). To this end, the data of 1299 boys and 1278 girls in 4th grade were analyzed using the Korean Children and Youth Panel Survey data. The correlation analysis, confirmatory factor analysis, structural equation modeling using phantom variables and bootstrapping were performed by using SPSS and AMOS programs. The results of this study are as follows. First, perceived PA had a significant effect on SE, CO, and PR, SE had a significant effect on CO and PR, and CO had a significant effect on PR. Second, the serial multi-mediating model that assumed that SE and CO mediate the relationship between PA and PR was found to be appropriate. These results suggest that it is important to consider the child's self-esteem and cooperation with parenting attitudes to improve the child's peer relationship. Future research and clinical implications were discussed.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.39 no.6
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• pp.51-58
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• 2002

In this paper, a 155/311 Mb/s MUX/DEMUX chip using ECL macrocell away has been developed with a single device. This device for a 2.5 Gb/s SDH based transmission system is to interleave the parallel data of 51 Mb/s into 155 Mb/s(or 311 Mb/s) serial data output, and is to interleave a serial input bit stream of 155 Mb/s(or 311 Mb/s) into the parallel output of 51 Mb/s. The input and output of the device ate TTL compatible at the low-speed end, but 100k ECL compatible at the high-speed end. The device has been fabricated with Motorola ETL3200 macrocell away The fabricated chip shows the typical phase margin of 180 degrees and output data skew less than 220ps at the high-speed end.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.30 no.6C
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• pp.560-569
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• 2005

This paper proposes an algorithm for transmit antenna selection in a multi-input multi-output(MIMO) spatial multiplexing system with per antenna rate control(PARC) and an ordered successive interference cancellation (OSIC) receiver. The active antenna subset is determined at the receiver and conveyed to the transmitter using feedback information on transmission rate per antenna. We propose a serial decision procedure consisting of a successive process that tests whether antenna selection gain exists when the antenna with the lowest pre-processing signal to interference and noise ratio(SINR) is discarded at each stage. Furthermore, we show that 'reverse detection ordering', whereby the signal with the lowest SINR is decoded at each stage of successive decoding, widens the disparities among fractions of the whole capacity allocated to each individual antenna and thus maximizes a gain of antenna selection. Numerical results show that the proposed reverse detection ordering based serial antenna selection approaches the closed-loop MIMO capacity and that it induces a negligible capacity loss compared with the heuristic selection strategy even with considerably reduced complexity.

• The Transactions of the Korean Institute of Power Electronics
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• v.14 no.5
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• pp.343-354
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• 2009

In this paper, a magnetic-less dc-dc switching converter realizing an integrable power conversion system is described. Instead of magnetic devices, the inductive impedance range of piezoelectric transducers is utilized to store and resonate the energy for soft-switching. Piezoelectric devices have no windings and deliver the power by the electrodes, which lead to mass product through semiconductor-manufacturing process. This paper presents a resonant-type step-up dc-dc power converter employing a disk-type piezoelectric transducer, analyzing the operation principles and the frequency control characteristics. Also, a topology extension of the single stage converter into cascaded multi-stage is presented and analyzed with the operation principles and control characteristics. For verification of the analysis, a 10W output dc-dc power converter hardware was implemented. The hardware experiments shows a good frequency control and power efficiency greater than 96% in the single stage. A hardware prototype of the extended multi-stage one was also realized and tested. The results shows that the converter has the same frequency control performance and high efficiency such as 93%.

• Journal of IKEEE
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• v.23 no.1
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• pp.1-8
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• 2019

In this paper, the electrical characteristics with various C-rates are tested with a high power series battery pack comprised of 18650 cylindrical nickel cobalt aluminum(NCA) lithium-ion battery. The electrical characteristics of discharge capacity test with 14S1P battery pack and electric vehicle (EV) cycle test with 4S1P battery pack are compared and analyzed by the various of C-rates. Multiple linear regression is used to estimate voltage imbalance of 14S1P and 4S1P battery packs with various C-rates based on experimental data. The estimation accuracy is evaluated by root mean square error(RMSE) to validate multiple linear regression. The result of this paper is contributed that to use for estimating the voltage imbalance of discharge capacity test with 14S1P battery pack using multiple linear regression better than to use the voltage imbalance of EV cycle with 4S1P battery pack.

• Proceedings of the Korean Society of Computer Information Conference
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• 2012.07a
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• pp.47-50
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• 2012

본 연구에서는 수용가에서 에너지 절감과 최대수요전력 제어를 위하여 마이크로프로세서를 이용한 고효율 자동 전압 조정기의 제어 방법에 대하여 제안한다. 제안한 고효율 자동 전압 조정기는 트로이달 코아에 1개의 직렬 권선과 분리된 4개의 분로 권선으로 구성되어 있는 단권 변압기를 사용한다. 변압기의 전압 조정은 직렬 권선과 분로 권선의 연결 방법에 따라 감압/승압이 가능하다. 스위치는 릴레이와 트라이악을 병행하여 사용한다. 스위치의 조작 시 발생하는 권선의 여자돌입전류를 제어하기 위하여 트라이악을 이용 연결 상태를 변경하고 연결 상태 유지 시에는 릴레이를 이용함으로써 스위치 소비 전력을 최소화 한다. 제어신호는 여자 돌입 전류를 줄이기 위하여 전압 파형에 동기화 하여 제어되며 이를 위하여 소프트웨어 PLL을 사용한다. 소프트웨어 PLL은 전압 파형의 zero-cross, 전압 최고점 등의 시간을 생성한다. 권선 스위치의 제어, 소프트웨어 PLL등 자동 전압 조정기의 제어는 마이크로프로세서에 의해서 이루어진다.

• Proceedings of the Korea Information Processing Society Conference
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• 2010.04a
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• pp.782-785
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• 2010

본 논문은 연속된 음성 신호를 전송로 상에 전송하기 위해 음성 신호를 G.711 표준 권고인 PCM으로 다중화한 후 고정 타임슬롯을 배정하여 전송하는 시스템에서 PCM 화된 디지털 음성 데이터를 실시간으로 암호화하여 전송하는 스트림 암호화 기법에 관한 것이다. 실시간으로 처리되는 음성 데이터의 암호화 시에는 하드웨어 방식이 적합한 데, 본 논문에서는 고정 타임슬롯을 배정받는 음성 데이터의 실시간 암호화 기법에 관한 것이다. 일반적으로 아날로그 음성 신호 코딩 시에 국내에서는 북미 방식인 ${\mu}-law$ 코딩 기법을 적용하는 데 이는 표본화한 음성 데이터를 양자화전에 압축하고 복호화 후 신장하는 비선형 양자화 기법을 적용하는 것으로 표본화된 값을 8 비트의 PCM 데이터로 변화하여 E1(2.048Mbps) 급 속도로 전송한다. 본 논문에서는 PCM 전송로 상에 전송되기 전의 직렬 입력 데이터를 암호화 장치를 거쳐 해당 타임슬롯에 해당하는 8 비트의 데이터를 실시간으로 암호화하여 전송로 상으로 전송하고 역으로 수신 단에서는 PCM 전송로를 거친 직렬 입력 데이터를 암호화된 타임슬롯을 판별하여 해당 타임슬롯의 데이터를 복호화하여 원래 데이터를 복원한다. 본 논문에서는 고정 타임슬롯을 배정받은 PCM 데이터를 암호화하여 전송한 후 수신 단에서 복호화 과정을 거친 후 타임슬롯 단위로 데이터 암호화/복호화가 가능함을 보여준다.

• Journal of the Korean Association of Geographic Information Studies
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• v.4 no.4
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• pp.1-7
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• 2001

Remotely sensed data is the most fundamental data in acquiring the GIS informations, and may be analyzed to extract useful thematic information. Multi-spectral classification is one of the most often used methods of information extraction. The actual multi-spectral classification may be performed using either supervised or unsupervised approaches. This paper analyze the effect of assigning clever initial values to image classes on the performance of parallelepiped classification algorithm, which is one of the supervised classification algorithms. First, we investigate the effect on serial computing model, then expand it on MIMD(Multiple Instruction Multiple Data) parallel computing model. On serial computing model, the performance of the parallel pipe algorithm improved 2.4 times at most and, on MIMD parallel computing model the performance improved about 2.5 times as clever initial values are assigned to image class. Through computer simulation we find that initial values of image class greatly affect the performance of parallelepiped classification algorithms, and it can be improved greatly when classes on both serial computing model and MIMD parallel computation model.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.9 no.1
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• pp.15-28
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• 1999

In Multilevel Secure Database Management System(MLS/DBMS), we assume that system has a security clearance level for each user and a classification level for each data item in system and the objective of these systems is to protect secure information from unauthorized user. Many algorithms which have been researched have focus on removing covert channel by modifying conventional lock-based algorithm or timestamp-based algorithm. but there is high-level starvation problem that high level transaction is aborted by low level transaction repeatedly. In order to solve this problem, we propose an algorithm to reduce high-level starvation using dynamic adjustment of serialization order, which is basically using orange lock. Because our algorithm is based on a single version unlike conventional secure algorithms which are performed on multiversion, it can get high degree of concurrency control. we also show that it guarantees the serializability of concurrent execution, and satisfies secure properties of MLS/DBMS.