• The Transactions of the Korean Institute of Power Electronics
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• v.27 no.1
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• pp.63-73
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• 2022

The differential power processor (DPP) system is used to prevent a decrease in the total power generation due to the partial shading of photovoltaic modules. Compared with traditional series strings and full power processing (FPP) converter solutions, the DPP converter system shows advantages in terms of modularization process, volume, and transformation losses. However, the system has a limitation in that the power generation process of differential power processors produces lower power under certain irradiation conditions. This paper proposes a structure and operating algorithm for differential power processing modules that can use a single power converter for multiple strings. The operational algorithm for the differential power regulators allows the maximum power generation to be maintained in comparison with conventional series-connected and differential power processing methods even under various partial shading conditions. The operation algorithm of the proposed DPP is verified by Matlab/Simulink simulations.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.59 no.8
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• pp.1489-1496
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• 2010

A feed forward differential architecture of analog PRML decoder is investigated to implement on analog parallel processing circuits. The conventional PRML decoder performs the trellis processing with the implementation of single stage in digital and its repeated use. The analog parallel processing-based PRML comes from the idea that the decoding of PRML is done mainly with the information of the first several number of stages. Shortening the trellis processing stages but implementing it with analog parallel circuits, several benefits including higher speed, no memory requirement and no A/D converter requirement are obtained. Most of the conventional analog parallel processing-based PRML decoders are differential architecture with the feedback of the previous decoded data. The architecture used in this paper is without feedback, where error metric accumulation is allowed to start from all the states of the decoding stage, which enables to be decoded without feedback. The circuit of the proposed architecture is simpler than that of the conventional analog parallel processing structure with the similar decoding performance. Characteristics of the feed forward differential architecture are investigated through various simulation studies.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.39 no.5
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• pp.74-86
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• 2002

This paper proposes a VLSI architecture for high-speed data processing of the differential phase detectors with the decision feedback. To improve the BER performance of the conventional differential phase detection, DF-DPD, DPD-RGPR and DFDPD-SA have been proposed. These detection methods have the architecture feedbacking the detected phase to reduce the noise of the previous symbol as phase reference. However, the feedback of the detected phase results in lower data processing speed than that of the conventional differential phase detection. In this paper, the VLSI architecture was proposed for high-speed data processing of the differential phase detectors with decision feedback. The Proposed architecture has the pre-calculation method to previously calculate the results on 'N'th step at 'M-1'th step and the pre-decision feedback method to previously feedback the predicted phases at 'M-1'th step. The architecture proposed in this paper was implemented to RTL using VHDL. The simulation results show that the Proposed architecture obtains the high-speed data processing.

• Korean Journal of Computational Design and Engineering
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• v.20 no.1
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• pp.44-54
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• 2015

Solving partial differential equations (PDEs) on a manifold setting is frequently faced problem in CAD, CAM and CAE. However, unlikely to a regular grid, solutions for those problems on a triangular mesh are not available in general, as there are no well-established intrinsic differential operators. Considering that a triangular mesh is a powerful tool for representing a highly-complicated geometry, this problem must be tackled for improving the capabilities of many geometry processing algorithms. In this paper, we introduce mathematically well-defined differential operators on a triangular mesh setup, and show some examples of their applications. Through this, it is expected that many CAD/CAM/CAE application will be benefited, as it provides a mathematically rigorous solution for a PDE problem which was not available before.

• Textile Coloration and Finishing
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• v.16 no.2
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• pp.47-51
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• 2004

A differential refractive index detector was used for monitoring glucose contents in textile processing solutions. The sensitivity of the device was high enough to measure 0.05％ aqueous glucose solution that could not be measured by normal refractive index measurement. The device was set to monitor glucose concentration continuously in real time by measuring differential refractive index and calibrated by standard glucose solutions in a range of 0.1 to 1.0%. The possibility of industrial application of the device was demonstrated by real-time monitoring of glucose concentration in textile processing solutions such as desizing bath and cellulase treatment bath. Both of solutions contained glucose as a major degraded product. The device would be able to control the weight loss of cellulosic fiber during cellulase treatment since the amount of degraded products in a processing bath is proportional to its weight loss.

• Journal of Information Processing Systems
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• v.14 no.5
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• pp.1068-1074
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• 2018

In this paper, we consider the delay partial differential equation of three dimensions with constant coefficients. We established the alternating direction difference scheme by the standard finite difference method, gave the order of convergence of the format and the expression of the difference scheme truncation errors.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.20 no.4
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• pp.109-115
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• 2010

Differential Power Analysis (DPA) is well known as one of efficient physical side-channel attack methods using leakage power consumption traces. However, since the power traces usually include the components irrelevant to the encryption, the efficiency of the DPA attack may be degraded. To enhance the performance of DPA, we introduce a pre-processing technique which extracts the encryption-related parts from the measured power consumption signals. Experimental results show that the DPA attack with the use of the proposed pre-processing method detects correct cipher keys with much smaller number of signals compared to that of the conventional DPA attack.

• Proceedings of the KIPE Conference
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• 2016.07a
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• pp.175-176
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• 2016

기존의 태양광 시스템은 대체로 고정된 형태로 사용되었지만 태양광 시스템의 응용분야가 확장됨에 따라 전기자동차, 웨어러블 기기 등의 이동식 태양광 시스템 또한 많이 개발되고 있다. 이동식 태양광 시스템의 경우 불균일한 태양빛에 많이 노출되며, 이러한 불균일한 태양빛은 극심한 시스템 효율 저하를 야기한다. 본 연구에서는 이러한 시스템 효율 저하 문제를 해결하기 위해 differential power processing (DPP) 컨버터를 병렬로 적용한 photovoltaic (PV) 충전 가방을 제시하였다. DPP 컨버터는 PV 충전 가방이 불균일한 태양빛에 노출되어도, 각각의 태양전지가 고유의 최대 전력점에서 작동하도록 제어하는 역할을 한다. PV 충전 가방은 4개의 태양전지로 구성되어 있으며 충분한 태양빛 아래, 5 W의 출력전력을 가질 수 있다. PV 충전 가방은 하나의 front-end 컨버터와 4개의 DPP 컨버로 구성되었으며, P-SIM 시뮬레이션과 실험을 통해 front-end 컨버터와 DPP 컨버터의 정상 작동을 입증하였다. 또한 동일한 태양빛에 노출된 경우, 기존의 연결 방법 중 하나인 병렬 배열은 1.49 W의 출력 전력을 가진 반면, DPP 시스템은 4.35 W의 출력 전력을 가져 약 3배 높은 출력 전력을 확인하였다.

• Proceedings of the KIPE Conference
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• 2017.07a
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• pp.48-49
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• 2017

태양광 발전 시스템 구현에 있어 가장 큰 문제점 중 하나는 불균일한 태양빛 조건에서의 전체 시스템 발전량 감소이다. 이를 해결하기 위해 module-integrated converter (MIC), dc optimizer, differential power processing (DPP) 등 다양한 컨버터가 연구되고 있다. 그 중에서도 DPP 컨버터는 낮은 전력변환 손실로 높은 시스템 효율을 얻을 수 있어 최근 많은 주목을 받고 있다. 보통 그리드 연결형 태양광발전 시스템에 적용되는 직렬 DPP의 경우, 이미 많은 연구가 진행되고 있지만, 병렬 DPP의 경우 아직 많은 연구가 필요한 상황이다. 본 논문에서는 front-end 컨버터의 존재 유무에 따른 두 가지 병렬 DPP 컨버터 배열을 비교 분석 하였다. Front-end 컨버터가 적용된 병렬 DPP 컨버터 배열의 경우, dc 전압과 태양전지의 전압 차이를 최소화해 전력 변환 손실을 감소시킬 수 있지만, front-end 컨버터에서 추가적인 전력 변환 손실이 발생한다. Front-end 컨버터가 없는 경우, dc 전압과 태양전지의 전압차이가 커 DPP 컨버터에서 발생하는 전력 변환 손실이 커진다. 따라서 주어진 조건 아래 효율적인 병렬 DPP 컨버터 디자인을 위한 가이드라인을 본 논문에서 제시하고자 한다.

• Journal of the Institute of Convergence Signal Processing
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• v.5 no.3
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• pp.223-229
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• 2004

Recently, OFDM and STC techniques have been considered to be candidate to support multimedia services in the next generation mobile radio communications and have been developed the many communications systems in order to achieve the high data rates. In this paper, we propose the Trellis-Coded Differential Space Time Modulation-OFDM system with multiple symbol detection. The Trellis-code performs the set partition with unitary group codes. The Viterbi decoder containing new branch metrics is introduced in order to improve the bit error rate (BER) in the differential detection of the unitary differential space time modulation. Also, we describe the Viterbi algorithm in order to use this branch metrics. Our study shows that such a Viterbl decoder improves BER performance without sacrificing bandwidth and power efficiency.