• Journal of information and communication convergence engineering
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• 제12권4호
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• pp.215-220
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• 2014

We consider quantization optimized for distributed estimation, where a set of sensors at different sites collect measurements on the parameter of interest, quantize them, and transmit the quantized data to a fusion node, which then estimates the parameter. Here, we propose an iterative quantizer design algorithm with a weighted distance rule that allows us to reduce a system-wide metric such as the estimation error by constructing quantization partitions with their optimal weights. We show that the search for the weights, the most expensive computational step in the algorithm, can be conducted in a sequential manner without deviating from convergence, leading to a significant reduction in design complexity. Our experments demonstrate that the proposed algorithm achieves improved performance over traditional quantizer designs. The benefit of the proposed technique is further illustrated by the experiments providing similar estimation performance with much lower complexity as compared to the recently published novel algorithms.

• Journal of information and communication convergence engineering
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• 제16권3호
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• pp.142-147
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• 2018

We present a practical design algorithm for quantizers at nodes in distributed systems in which each local measurement is quantized without communication between nodes and transmitted to a fusion node that conducts estimation of the parameter of interest. The benefits of vector quantization (VQ) motivate us to incorporate the VQ strategy into our design and we propose a low-complexity design technique that seeks to assign vector codewords into sets such that each codeword in the sets should be closest to its associated local codeword. In doing so, we introduce new distance metrics to measure the distance between vector codewords and local ones and construct the sets of vector codewords at each node to minimize the average distance, resulting in an efficient and independent encoding of the vector codewords. Through extensive experiments, we show that the proposed algorithm can maintain comparable performance with a substantially reduced design complexity.

• 디지털산업정보학회논문지
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• 제7권3호
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• pp.75-83
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• 2011

Cognitive radio (CR) technology is to maximize the spectrum utilization by allocating the unused spectrums to the unlicensed users. This technology enables the sharing of channels among secondary (unlicensed) and primary (licensed) users on a non-interference basis after sensing the vacant channel and as a result, it is possible to harness wireless frequency more efficiently. To enhance the accuracy of sensing, RDSS was suggested. It is a fusion mechanism based on the reputation of sensing nodes and WSPRT (weighted sequential probability ratio test). However, in RDSS, the execution number of WSPRT could increase according to the order of inputted sensing values, and the fast defense against the forged values is difficult. In this paper, we propose a transaction signing-based authentication scheme for secure distributed spectrum sensing to response the forged values. The validity of proposed scheme is provided by BAN logic.

• 전기전자학회논문지
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• 제23권2호
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• pp.710-715
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• 2019

We consider parameter estimation in distributed systems in which measurements at local nodes are quantized in a non-regular manner, where multiple codewords are mapped into a single local measurement. For the system with non-regular quantization, to ensure a perfect independent encoding at local nodes, a local measurement can be encoded into a set of a great number of codewords which are transmitted to a fusion node where estimation is conducted with enormous computational cost due to the large cardinality of the sets. In this paper, we propose an efficient estimation technique that can handle the non-regular quantized data by efficiently finding the feasible combination of codewords without searching all of the possible combinations. We conduct experiments to show that the proposed estimation performs well with respect to previous novel techniques with a reasonable complexity.

• ETRI Journal
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• 제46권3호
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• pp.421-431
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• 2024

In this study, a direct position tracking method for non-circular (NC) signals using distributed passive arrays is proposed. First, we calculate the initial positions of sources using a direct position determination (DPD) approach; next, we transform the tracking into a compensation problem. The offsets of the adjacent time positions are calculated using a first-order Taylor expansion. The fusion calculation of the noise subspace is performed according to the NC characteristics. Because the proposed method uses the signal information from the previous iteration, it can realize automatic data associations. Compared with traditional DPD and two-step localization methods, our novel process has lower computational complexity and provides higher accuracy. Moreover, its performance is better than that of the traditional tracking methods. Numerous simulation results support the superiority of our proposed method.

• Bulletin of the Korean Chemical Society
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• 제32권2호
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• pp.510-514
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• 2011

Photodissociation dynamics of allyl alcohol ($H_2C$=CH-$CH_2OH$) has been investigated at 205 - 213 nm along the UV absorption band by measuring rotationally-resolved laser-induced fluorescence spectra of OH radicals. Observed energy partitioning of the available energy among products at all photon energies investigated was similar and the barrier energy for OH production is about 574.7 kJ/mol from the OH yield measurements. The potential energy surfaces for the $S_0$, $T_1$, and $S_1$ excited states along the dissociation coordinate were obtained by ab initio quantum chemical calculations. The observed energy partitioning was successfully modeled by the "barrier-impulsive model" with the reverse barrier and the geometry obtained by the calculated potential energy surfaces. The dissociation takes place on the $T_1$ excited state potential energy surface with an energy barrier in the exit channel and a large portion of the photon energy is distributed in the internal degrees of freedom of the polyatomic products.

• 한국정보과학회:학술대회논문집
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• 한국정보과학회 2007년도 한국컴퓨터종합학술대회논문집 Vol.34 No.1 (B)
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• pp.437-440
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• 2007

최근 환경 문제를 해결하기 위하여 환경 문제의 많은 컴퓨터 기술들이 응용되고 있다. 환경 정보는 환경오염원 및 주위에 미치는 영향과 오염된 농도에 대한 정보를 연구 및 분석 할 수 있는 분야이다. 최근 환경에 관련 연구가 일부에서 수행되고 있으나 이를 IT기술과 접목하여 다양한 정보를 효율적으로 저장 및 검색 할 수 있는 시스템은 부족한 실정이다. 또한 현재 환경오염의 측정방법으로는 수작업으로 이루어지는 경우가 많아서 공간적 및 물리적 제약이 있는 따르는 실정이다. 환경오염에 관한 정보를 센서를 사용하여 사용자에게 실시간으로 효과적으로 저장 관리하여 관련된 연구자들 간에 서로가 필요한 정보를 쉽게 공유할 수 있도록 본 논문에서는 Ubiquitous Sensor Network(USN), Java Message Service(JMS) 및 Webservice를 이용한 환경 모니터링 서비스를 제안 한다. 본 논문에서 제안한 시스템은 환경정보와 사용자간에 유연성, 확장성 및 실시간을 보장해 주는 시스템을 구현한다.

• 한국미생물·생명공학회지
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• 제13권4호
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• pp.383-389
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• 1985

전분을 발효할 수 있는 새로울 효모균수의 개발을 목적으로 PEG를 fusogen으로 사용하여 이속 효모간 원형질체 융합을 시도하였다. 원형질체 융합에 사용한 친균주의 genetic marker로는 상보적 영양요구성을 이용하였고 각각의 영양요구성이 상호보완되어 최소배지상에 자라는 colony를 융합체로하였다. S. cerevisiae와 C. tropicalis의 이속간 원형질체의 융합빈도는 $10^{-4}$에서 $10^{-6}$ 정도였으며, 원형질체 융합에 있어서 PEG 4,000. 30%가 가장 좋은 효과를 나타내었다. 최적 pH는 8.0이었으며, PEG의 처리효과는 온도가 상승함에 따라 증가하여 35$^{\circ}C$에서 최적을 나타내었고 또한 Ca이온의 첨가에 의해서도 증가하였는데 Ca 이온의 촉진효과는 1mM과 100mM 농도 사이에서 최고를 나타내었다.

• 한국표면공학회지
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• 제54권2호
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• pp.77-83
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• 2021

In this study, we investigated various coating methods of graphene oxide on the surface of a petri dish made of polystyrene and analyzed the physical and chemical properties of the coated surface. For coating, spinning, spraying and pressing methods were attempted. The coated surface was characterized by SEM, Raman Spectroscopy, AFM, FT-IR, UV-Vis Spectroscopy and Contact Angle measurement. By spin coating and spray coating, well distributed graphene oxide in the form of multiple islands on the plastic surface with an average size of 5 to 20㎛ are observed by SEM, and high binding energy between graphene oxide and plastic surface is measured by AFM. In case of hand press coating, graphene oxide of 10㎛ or more was observed, and low surface energy was measured. By FT-IR and Raman Spectroscopy analysis, surface coating of graphene oxide was confirmed.

• 제어로봇시스템학회논문지
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• 제16권9호
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• pp.898-904
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• 2010

Unmanned autonomous forklifts have a great potential to enhance the productivity of material handling in various applications because these forklifts can pick up and deliver loads without an operator and any fixed guide. There are, however, many technical difficulties in developing such forklifts including localization, map building, sensor fusion, control and so on. Implementation, which is often neglected, is one of practical issues in developing such an autonomous device. This is because the system requires numerous sensors, actuators, and controllers that need to be connected with each other, and the number of connections grows very rapidly as the number of devices grows. Another requirement on the integration is that the system should allow changes in the system design so that modification and addition of system components can be accommodated without too much effort. This paper presents a network-based distributed approach where system components are connected to a shared CAN network, and control functions are divided into small tasks that are distributed over a number of microcontrollers with a limited computing capacity. This approach is successfully applied to develop an unmanned forklift.