• ETRI Journal
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• 제28권4호
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• pp.513-516
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• 2006

Experimental demonstration of bipolar spectral encoding code-division multiple-access with modified pseudorandom noise codes is presented. Bipolar spectral encoding is achieved with an erbium-doped fiber amplifier amplified spontaneous emission source and arrayed waveguide gratings. The bit-error rate performance of 1.25 Gbps signal transmission over 80 km single mode fiber is measured in a multiple-user environment.

• 한국도서관정보학회지
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• 제50권2호
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• pp.237-260
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• 2019

본 연구에서는 이용량이 기하급수적으로 증가하는 A대학 기관리포지터리(IR)의 자료 유형별 이용통계와 이용자가 A-IR에 접근하는 접근경로의 변화 추이를 분석하였다. 특히, 접근경로의 변화 추이에 초점을 맞추어 다양한 노출경로의 확보가 A-IR 이용확산에 기여한다는 것을 검증하였으며, SNS 등 시대적 소통방식이 A-IR의 접근경로로 활용된다는 것도 확인하였다. 이를 통해서 향후 기관리포지터리를 활성화하는 노출경로의 다양화 등 운영방향을 제시하고자 하였다.

• ETRI Journal
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• 제26권1호
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• pp.13-20
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• 2004

We propose a new optical code division multiple access (OCDMA) scheme for reducing multiple access interference (MAI) and enhancing performance for optical subscriber access networks using modified pseudorandom noise (PN)-coded fiber Bragg gratings with bipolar OCDMA decoders. Through the bipolar OCDMA decoder and the modified PN codes, MAI among users is effectively depressed. As the data are encoded either by a unipolar signature sequence of the modified PN code or its complement according to whether the data bit is 1 or 0, the bit error ratio (BER) can be more improved with the same signal to interference plus noise ratio over the conventional on-off shift keying-based OCDMA system. We prove by numerical analysis that the BER of the proposed bipolar OCDMA system is better than the conventional unipolar OCDMA system. We also analyze the spectral power distortion effects of the broadband light source.

• International Journal of Internet, Broadcasting and Communication
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• 제13권4호
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• pp.39-47
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• 2021

Lempel-Ziv coding is one of the most famous source coding schemes. The output of this source coding is usually a non-uniform code, which requires additional source coding, such as arithmetic coding, to reduce a redundancy. However, this additional source code increases complexity and decoding latency. Thus, this paper proposes the optimal maximum a-posteriori (MAP) receiver for non-uniform source non-orthogonal multiple access (NOMA) with symmetric superposition coding (SSC). First, we derive an analytical expression of the bit-error rate (BER) for non-uniform source NOMA with SSC. Then, Monte Carlo simulations demonstrate that the BER of the optimal MAP receiver for the non-uniform source improves slightly, compared to that of the conventional receiver for the uniform source. Moreover, we also show that the BER of an approximate analytical expression is in a good agreement with the BER of Monte Carlo simulation. As a result, the proposed optimal MAP receiver for non-uniform source could be a promising scheme for NOMA with SSC, to reduce complexity and decoding latency due to additional source coding.

• Journal of Communications and Networks
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• 제18권2호
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• pp.261-269
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• 2016

In this paper, the impact of energy constraints on a two-hop network with a source, a relay and a destination under random medium access is studied. A collision channel with erasures is considered, and the source and the relay nodes have energy harvesting capabilities and an unlimited battery to store the harvested energy. Additionally, the source and the relay node have external traffic arrivals and the relay forwards a fraction of the source node's traffic to the destination; the cooperation is performed at the network level. An inner and an outer bound of the stability region for a given transmission probability vector are obtained. Then, the closure of the inner and the outer bound is obtained separately and they turn out to be identical. This work is not only a step in connecting information theory and networking, by studying the maximum stable throughput region metric but also it taps the relatively unexplored and important domain of energy harvesting and assesses the effect of that on this important measure.

• Asian Pacific Journal of Cancer Prevention
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• 제15권15호
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• pp.6171-6176
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• 2014

Background: In order to design effective educational intervention for cancer survivors, it is necessary to identify most-trusted sources for health-related information and the amount of attention paid to each source. Objective: The objective of our study was to explore the sources of health information used by cancer survivors according to their access to the internet and levels of trust in and attention to those information sources. Materials and Methods: We analyzed sources of health information among cancer survivors using selected questions adapted from the 2012 Health Information National Trends Survey (HINTS). Results: Of 357 participants, 239 (67%) had internet access (online survivors) while 118 (33%) did not (offline survivors). Online survivors were younger (p<0.001), more educated (p<0.001), more non-Hispanic whites (p<0.001), had higher income (p<0.001), had more populated households (p<0.001) and better quality of life (p<0.001) compared to offline survivors. Prevalence of some disabilities was higher among offline survivors including serious difficulties with walking or climbing stairs (p<0.001), being blind or having severe visual impairment (p=0.001), problems with making decisions (p<0.001), doing errands alone (p=0.001) and dressing or bathing (p=0.001). After adjusting for socio-demographic status, cancer survivors who were non-Hispanic whites (OR= 3.49, p<0.01), younger (OR=4.10, p<0.01), more educated (OR= 2.29, p=0.02), with greater income (OR=4.43, p<0.01), and with very good to excellent quality of life (OR=2.60, p=0.01) had higher probability of having access to the internet, while those living in Midwest were less likely to have access (OR= 0.177, p<0.01). Doctors (95.5%) were the most and radio (27.8%) was the least trusted health related information source among all cancer survivors. Online survivors trusted internet much more compared to those without access (p<0.001) while offline cancer survivors trusted health-related information from religious groups and radio more than those with internet access (p<0.001 and p=0.008). Cancer survivors paid the most attention to health information on newsletters (63.8%) and internet (60.2%) and the least to radio (19.6%). More online survivors paid attention to internet than those without access (68.5% vs 39.1%, p<0.001) while more offline survivors paid attention to radio compared to those with access (26.8% vs 16.5%, p=0.03). Conclusions: Our findings emphasize the importance of improving the access and empowering the different sources of information. Considering that the internet and web technologies are continuing to develop, more attention should be paid to improve access to the internet, provide guidance and maintain the quality of accredited health information websites. Those without internet access should continue to receive health-related information via their most trusted sources.

• 정보관리학회지
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• 제33권3호
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• pp.31-61
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• 2016

본 연구의 목적은 공개 소프트웨어를 활용하여 지역 축제기록을 보존 활용할 수 있는 전자기록관리시스템을 구축하고, 사용한 공개 소프트웨어를 비교하여 축제 기록에 적합한 공개 소프트웨어를 평가하는 것이다. 본 연구의 적용 대상 축제로 춘향제를 선정하였으며, 현재 춘향제 기록관리의 문제점을 제기하여 그 중 축제기록을 보존할 시스템이 없다는 점을 제시하였다. 이후, 기록관리용 공개 소프트웨어인 AtoM(Access to Memory)와 OMEKA를 활용하여 축제기록관리시스템을 구현하였다. 구축된 각각의 시스템을 지역 축제기록의 특성에 따라 비교한 결과, AtoM 기반 축제기록관리시스템이 지역 축제기록의 보존 활용에 더욱 적합한 것으로 나타났다.

• International Journal of Internet, Broadcasting and Communication
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• 제13권4호
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• pp.48-54
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• 2021

In most existing researches on non-orthogonal multiple access (NOMA) with symmetric superposition coding (SSC), uniform sources have been usually considered. For the first part in this two-part paper, for the strongest channel gain user, we showed that the bit-error rate (BER) for the optimal maximum a-posteriori (MAP) receiver for the non-uniform source improves slightly, compared to that of the conventional receiver for the uniform sources. We demonstrate that in communication scenarios of the non-uniform source NOMA schemes, for the weakest channel gain user, the BER performance of the optimal MAP receiver for a non-uniform source improves greatly, compared to that of the conventional receiver for uniform sources. We first derive an analytical expression of the BER for non-uniform source NOMA with SSC. Then, simulations demonstrate that the BER of the optimal MAP receiver for the non-uniform source improves, compared with that of the conventional maximum likelihood (ML) receiver for the uniform sources. In result, the proposed optimal MAP receiver for the non-uniform source could be a promising scheme for SSC NOMA, with improved BER performances.

• 정보처리학회논문지D
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• 제18D권1호
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• pp.35-44
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• 2011

메모리 사용에 관련한 오류는 해당 프로그램뿐 아니라 시스템의 오작동을 유발할 수 있다. 특히 발생 빈도가 매우 낮은 일부 메모리 오류의 경우 제대로 된 동작 테스트를 할 수 없어, 오류에 대한 파악 및 수정이 힘들다. 이에 본 논문에서는 실행 프로그램을 역어셈블(Dis-Assemble)하여 만들어진 어셈블리어 코드를 구문 분석하여 명령어 전이도를 도출하고 이에 기반을 두어 메모리 사용 오류 가능성을 검출하는 방법을 제안하였다. 몇 가지 프로그램을 검사대상으로 선정하여 Local Memory Return Error, Null Pointer Access Error, Uninitialized Pointer Access Error를 검출하였으며 그 중 오픈 소스 프로젝트(Open Source Project)인 아파치 웹 서버와 PHP 스크립트 해석기에서도 메모리 사용 오류의 가능성이 있는 코드가 검출되었다.

• International Journal of Advanced Culture Technology
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• 제9권3호
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• pp.321-326
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• 2021

In a multi-cloud environment, it is necessary to minimize physical movement for efficient interoperability of distributed source data without building a data warehouse or data lake. And there is a need for a data platform that can easily access data anywhere in a multi-cloud environment. In this paper, we propose a new platform based on data fabric centered on a distributed platform suitable for cloud environments that overcomes the limitations of legacy systems. This platform applies the knowledge graph database technique to the physical linkage of source data for interoperability of distributed data. And by integrating all data into one scalable platform in a multi-cloud environment, it uses the holochain technique so that companies can easily access and move data with security and authority guaranteed regardless of where the data is stored. The knowledge graph database mitigates the problem of heterogeneous conflicts of data interoperability in a decentralized environment, and Holochain accelerates the memory and security processing process on traditional blockchains. In this way, data access and sharing of more distributed data interoperability becomes flexible, and metadata matching flexibility is effectively handled.