• Proceedings of the IEEK Conference
• /
• 2003.07a
• /
• pp.446-449
• /
• 2003

In recent years, the research of an efficient transmission method is going to meet a demand for high speed and large capacity radio communication. These systems make use of ultra-short duration pulses which yield UWB(Ultra Wide Band) signals characterized by low power spectral densities. The wavelet synthesis wave is able to set up the scale freely. So it is possible to use as the transmission wave of UWB by compressing time. In this paper, we present a general analytical expression for the average BER(Bit Error Rate) performance of UWB data transmission using wavelet system as a function of the cross-correlation between the users' signatures in an additive white Gaussian noise(AWGN) channel.

• Proceedings of the KSME Conference
• /
• 2008.11a
• /
• pp.1752-1757
• /
• 2008

Simple and highly efficient droplet merging method is proposed, which enables two nanoliter or picoliter droplets to merge regularly in a straight microchannel. We observe that two droplets of the same size but of different viscosities are merged by velocity difference induced as they are transported with the carrier fluid. To make viscosity difference, the mass ratio of water and glycerol is varied. Two droplets of the same size or of different sizes are generated alternatingly in the cross channel by controlling flowrates. This droplet merging method can be used to mix or encapsulate one target sample with another material, so that it can be applied to cell lysis, particle synthesis, drug discovery, hydrogel-bead production, and so on.

• The Journal of the Acoustical Society of Korea
• /
• v.28 no.1E
• /
• pp.29-34
• /
• 2009

MPEG4 High Efficiency Advanced Audio Coding (HE-AAC) and MPEG Surround are one of the most efficient combinations for low bit rate multi-channel audio coding. Based on the fact that these two codecs have identical quadrature mirror filter (QMF) analysis and synthesis structures, we propose a dual-domain connection scheme for the codecs. Specifically two time-domain connection methods are analyzed and compared to the QMF subband-domain connection method. Experimental results show that both the time-domain connection methods cause no subjective sound quality degradation compared to the QMF subband-domain connection method, which verifies that one can select either of them depending on application scenarios.

• JSTS:Journal of Semiconductor Technology and Science
• /
• v.16 no.3
• /
• pp.261-273
• /
• 2016

Reconfigurable finite impulse response (FIR) filters whose filter coefficients and filter order change dynamically during run-time play an important role in the software defined radio (SDR) systems, multi-channel filters, and digital up/down converters. However, there are not many reports on such reconfigurable designs which can support dynamic variation of filter order and filter coefficients. The purpose of this paper is to provide an architectural solution for the FIR filters to support run-time variation of the filter order and filter coefficients. First, two straightforward designs, namely, (i) single-MAC based design and (ii) full-parallel design are presented. For large variation of the filter order, two designs based on (iii) folded structure and (iv) fast FIR algorithm are presented. Finally, we propose (v) high throughput design which provides significant advantage in terms of hardware and/or time complexities over the other designs. We compare complexities of all the five structures, and provide the synthesis results for verification.

• Proceedings of the IEEK Conference
• /
• 2003.11c
• /
• pp.68-71
• /
• 2003

An output multiplexer of manifold type is widely employed in a recent satellite transponder due to its small size and mass. For correct operation, channel fillers in manifold multiplexer must be singly terminated. In this paper, a simple synthesis method fur a single terminated filter is described. From the given method, a 4-pole singly terminated elliptic function filter for Ka band satellite transponder is designed. The filter is shown to be suitable for satellite application and its measured results agrees well with computed ones.

• Journal of the Korea Institute of Military Science and Technology
• /
• v.6 no.3
• /
• pp.36-43
• /
• 2003

Multi-target away signal simulator which can simulate the radiated noises of maneuvering targets in a specified ocean range is an essential equipment for the validation of developed towed array sonar system. This simulator should provide realistic multi-channel signals those are required for beamforming on the signal processing unit of towed away system. This paper describes the overall system configuration and signal synthesis techniques for the target radiated noise. And this paper considers why the time delays between target and individual sensors are caused and how to compensate these time delays to individual sensors output. This multi-purpose target simulator could be used for the training of TASS operators.

• Proceedings of the Acoustical Society of Korea Conference
• /
• autumn
• /
• pp.337-340
• /
• 2000

입체음향 생성을 위한 기존의 방법은 크게 바이노럴 녹음기법과 머리전달함수(HRTF)를 이용한 바이노럴 합성 기법으로 나눌 수 있다. 기존 2채널 더미헤드를 이용한 바이노럴 녹음기법과 바이노럴 합성기법은 표준 더미헤드를 사용함으로써 청취자 머리와의 오차로 정면 음상 정위의 어려움, "Front-back confusion", 이동 음 음상 정위 어려움 등의 문제로 실제 녹음 현장에서는 거의 사용되지 않고 있다. 본 논문에서 제안한 3채널 더미헤드 기법은 이러한 문제점을 극복할 수 있고, 특히, HRTF 합성 시 기존의 HRTF의 문제점을 극복할 수 있는 새로운 HRTF를 구축할 수 있다. 따라서 바이노럴 합성 기법이 필요한 오락, 시뮬레이터, 음장 가청화 기술(Auralization) 프로그램 등 다양한 분야에서의 적용이 가능하다.

• Proceedings of the KIEE Conference
• /
• 1999.07g
• /
• pp.3199-3201
• /
• 1999

Convolutional coding with Viterbi decoding is known as a powerful method for forward error correction among many kinds of channel coding methods. This paper presents a soft decision Viterbi decoder which has systolic array trace-back architecture[1]. Soft decision is known as more effective method than hard decision and most of digital communication systems use soft decision. The advantage of using a systolic array decoder is that the trace-back operation can be accomplished continuously in an array of registers in a pipe-line fashion, instead of waiting for the entire trace-back procedure to be completed at each iteration. Therefore it may be suitable for faster communication system. We described operations of each module of the decoder and showed results of the logic synthesis and functional simulation.

• Applied Chemistry for Engineering
• /
• v.30 no.2
• /
• pp.133-140
• /
• 2019

Two-dimensional (2D) ultrathin molybdenum dichalcogenides $MoS_2$ has gained a great deal of attention in energy conversion and storage applications because of its unique morphology and property. The 2D $MoS_2$ nanosheets provide a high specific surface area, 2D charge channel, sub-nanometer thickness, and high conductivity, which lead to high electrochemical performances for energy storage devices. In this paper, an overview of properties and synthetic methods of $MoS_2$ nanosheets for applications of supercapacitors and rechargeable batteries is introduced. Different phases triangle prismatic 2H and metallic octahedral 1T structured $MoS_2$ were characterized using various analytical techniques. Preparation methods were focused on top-down and bottom-up approaches, including mechanical exfoliation, chemical intercalation and exfoliation, liquid phase exfoliation by the direct sonication, electrochemical intercalation exfoliation, microwave-assisted exfoliation, mechanical ball-milling, and hydrothermal synthesis. In addition, recent applications of supercapacitors and rechargeable batteries using $MoS_2$ electrode materials are discussed.

• Proceedings of the PSK Conference
• /
• 2002.10a
• /
• pp.355.1-355.1
• /
• 2002

Recently. we have reported that several lipoxygenases products directly activate the capsaicin-activated channel as intracellular messengers in neuron. In particular, 12-(S)-hydroperoxyeicosatetraenoic acid turned out to be the most potent endogenous VR activator. This finding prompted us to search for a novel non-vaniloid VR agonists and antagonists. We have designed and synthesized a series of non-vanilloid VR binding ligands based on the structural simllarity between 12-HPETE and capsaicin, the natural VR agonist. Our recent studies on the development of selective vanilloid receptor agonists and antagonists will be presented.