• 한국지능시스템학회논문지
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• 제22권1호
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• pp.81-86
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• 2012

본 논문에서는 전형적인 Linear Discriminant Analysis을 확장시켜 전체 입력공간을 다수의 지역공간으로 분할하고 분할된 공간에 Local Linear Discriminant Analysis 기반으로 하여 패턴 분류 규칙을 설계하는 새로운 방법을 제안한다. 전체 입력공간을 여러 개의 지역공간으로 분할하기 위한 방법으로 unsupervised clustering의 대표적인 방법인 k-Means 클러스터링 기법과 최적화 알고리즘인 차분 진화 연산 알고리즘을 사용한다. 제안된 알고리즘의 성능 평가를 위해 기존의 패턴 분류기와 비교 결과를 제시한다.

• 정보보호학회논문지
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• 제10권4호
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• pp.107-112
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• 2000

본 논문에서는 DES(Data Encryption Standard)를 변형하여 설계된 HEA(Hangul Encryption Algorithm)을 차분분석 관점에서의 안전성에 대하여 고찰하고자 한다. HEA는 한글 64음절(1,024 비트) 입 ·출력이 되도록 설계된 56비트 키를 사 용하고 DES와 동일한 8개의 S-box를 적용한 16라운드 Fiestel 구조의 블록 암호알고리즘이다. 본 논문에서는 기존의 DES에 적용한 차분분석 기법이 동일하게 HEA에도 적용됨을 보이고 10라운드로 축소된 HEA 경우 선택평문공격(chosen plaintext attack)이 가능하며 일정한 확률에 의해 분석됨을 증명하였다.

• 전자공학회논문지A
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• 제31A권7호
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• pp.29-35
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• 1994

The performance of continuous phase modulation signals is well known for the coherent demodulation. But the carrier recovery circuits of the coherent receiver have long acquisition time and the receiver experiences high error floors for fading channels. In this paper, we propose the differential demodulation of 2-h continuous phase modulation signals. The sets of modulation indices of 2-h phase codes adequate to the differential demodulation for differentially encoded input are obtained and the average bit error probability in Additive White Gaussian Noise environments is derived and analyzed.

• 한국통신학회논문지
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• 제32권2A호
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• pp.195-202
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• 2007

A differential space-frequency block code - orthogonal frequency division multiplexing (SFBC-OFDM) scheme as a multiple-input multiple-output (MIMO) transmission technique for next-generation digital multimedia broadcasting (DMB) is proposed in this paper. A linear decoding method for differential SFBC, which performs comparably to the ML decoding method, is derived for the cases of two or four transmit antennas. A simple table lookup method is proposed to improve the efficiency of the encoding/decoding process of DSFBC for the case of non-constant modulus constellations. A DMB MIMO channel model, developed by extending the 3GPP MIMO model to fit DMB environments, is used to compare BER performances of differential space block code schemes for various channel environments. Simulation results show that the differential SFBC-16QAM scheme using either four transmit antennas with one receive antenna or two transmit antennas with two receive antennas achieves a performance gain of 12dB than that of the conventional DQPSK scheme, even with a data rate twice faster.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 2001년도 ICCAS
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• pp.88.4-88
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• 2001

In this paper, we propose a solver for differential equations, using a multi-layer neural network. The multi-layer neural network is a transformer function originally where the function is differential and the explicit representation has been developed. The learning determines the response of neural networks; however, the response is not equal to the output values. The differential relations are also the response. The differential conditions can be also set as teaching data; therefore, there is a possibility to reach a new solver for the differential equations. Since it is unknown how to define the input data for the neural network solver during long terms, we could not derive the expressions. Recently, the analogue type neural network is known and it transforms any vector to another The "any" must be...

• 스마트미디어저널
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• 제4권2호
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• pp.55-61
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• 2015

A bandwidth-enhanced ultra-wide band (UWB) CMOS balun-LNA is implemented as a part of a software defined radio (SDR) receiver which supports multi-band and multi-standard. The proposed balun-LNA is composed of a single-to-differential converter, a differential-to-single voltage summer with inductive shunt peaking, a negative feedback network, and a differential output buffer with composite common-drain (CD) and common-source (CS) amplifiers. By feeding the single-ended output of the voltage summer to the input of the LNA through a feedback network, a wideband balun-LNA exploiting negative feedback is implemented. By adopting a source follower-based inductive shunt peaking, the proposed balun-LNA achieves a wider gain bandwidth. Two LNA design examples are presented to demonstrate the usefulness of the proposed approach. The LNA I adopts the CS amplifier with a common gate common source (CGCS) balun load as the S-to-D converter for high gain and low noise figure (NF) and the LNA II uses the differential amplifier with the ac-grounded second input terminal as the S-to-D converter for high second-order input-referred intercept point (IIP2). The 3 dB gain bandwidth of the proposed balun-LNA (LNA I) is above 5 GHz and the NF is below 4 dB from 100 MHz to 5 GHz. An average power gain of 18 dB and an IIP3 of -8 ~ -2 dBm are obtained. In simulation, IIP2 of the LNA II is at least 5 dB higher than that of the LNA I with same power consumption.

• 전자공학회논문지SC
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• 제38권4호
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• pp.20-30
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• 2001

트랜스리니어 셀을 이용한 새로운 200 MHz CMOS 트랜스컨덕터를 제안하였다. 제안한 트랜스컨덕터는 트랜스리니어 셀에 기초를 둔 전압 폴로워 및 전류 폴로워와 하나의 저항기로 구성된다. 트랜스컨덕터의 폭 넓은 응용을 위해, 단일-입력 단일-출력, 단일-입력 차동-출력, 그리고 완전-차동 트랜스컨덕터를 각각 체계적으로 설계하였다. 컴퓨터 시뮬레이션의 결과, 완전-차동 트랜스컨덕터는 ${\pm}3$ V의 공급 전압에서 ${\pm}2.7$ V의 입력 선형 범위, 200 MHz의 3-dB 주파수, 그리고 41 $ppm/^{\circ}C$ 이하의 온도 계수를· 가진다는 것을 확인하였다. 완선-차동 트랜스컨덕터의 응용성을 확인하기 위해, 인덕턴스 시뮬레이션 방식에 기초한 3차 사다리형 일립틱 저역-통과 여파기를 설계하였다. 설계된 저역-통과 여파기는 22 MHz의 리플 대역폭파 0.36 dB의 통과 대역 리플, 그리고 26 MHz의 차단 주파수를 가진다.

• Journal of Power Electronics
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• 제17권4호
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• pp.1037-1047
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• 2017

The Differential Power Processing (DPP) converter is a promising multi-module photovoltaic inverter architecture recently proposed for photovoltaic systems. In this paper, a DPP converter architecture, in which each PV-panel has its own DPP converter in shunt, performs distributed maximum power point tracking (DMPPT) control. It maintains a high energy conversion efficiency, even under partial shading conditions. The system architecture only deals with the power differences among the PV panels, which reduces the power capacity of the converters. Therefore, the DPP systems can easily overcome the conventional disadvantages of PCS such as centralized, string, and module integrated converter (MIC) topologies. Among the various types of the DPP systems, the feed-forward method has been selected for both its voltage balancing and power transfer to a modified H-bridge inverter that needs charge balancing of the input capacitors. The modified H-bridge multi-level inverter had some advantages such as a low part count and cost competitiveness when compared to conventional multi-level inverters. Therefore, it is frequently used in photovoltaic (PV) power conditioning system (PCS). However, its simplified switching network draws input current asymmetrically. Therefore, input capacitors in series suffer from a problem due to a charge imbalance. This paper validates the operating principle and feasibility of the proposed topology through the simulation and experimental results. They show that the input-capacitor voltages maintain the voltage balance with the PV MPPT control operating with a 140-W hardware prototype.

• 전기학회논문지
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• 제60권1호
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• pp.8-13
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• 2011

A percentage current differential relay is widely used for transformer protection. Because many percentage current differential relays recently use modified methods instead of conventional methods for deciding the operating characteristics of the large current region, in this paper, the operating region of a percentage current differential relay is analyzed in input-output current domain instead of operating-restraint current domain. An effective method to set the operating region when a CT is saturated is proposed with a series of investigations comparing a conventional method with the proposed modified method. The performance of the proposed method is evaluated for internal and external faults of a power transformer having the voltage rating of 345/154kV. EMTP-RV is used for the relaying data collection.

• ETRI Journal
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• 제29권1호
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• pp.45-49
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• 2007

The poly-Si thin film transistor (TFT) shows large variations in its characteristics due to the grain boundary of poly-crystalline silicon. This results in unacceptably large input offset of low-voltage differential signaling (LVDS) receivers. To cancel the large input offset of poly-Si TFT LVDS receivers, a full-digital offset compensation scheme has been developed and verified to be able to keep the input offset under 15 mV which is sufficiently small for LVDS signal receiving.