• Journal of the Institute of Electronics and Information Engineers
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• v.52 no.6
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• pp.10-14
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• 2015

In holographic data storage systems, data is recorded and read by page on a volume of storage medium, and it can increase transmission rate and storage capacity because of two-dimensional page-oriented data processing by charge-coupled devices. However, HDS suffers two-dimensional intersymbol interference unlike conventional data storages. In this paper, we propose a preprocessing method of decreasing ISI before read data in HDS pass to detector. This method has some advantage when we collaborate with the preprocessing for reducing misalignment error and modulation code.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2009.05a
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• pp.887-890
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• 2009

To transmit information over a channel in the presence of noise, there needs some technique to code the information. One of the coding techniques used for error detection and correction close to the Shannon limit is Low Density Parity Code. LDPC and decoding characteristic features by sum-product algorithm are matched for the performance to Turbo Code, RA(Repeat Accumulate) code, in case of very long code length of LDPC surpass their performance. This paper explains LDPC coding scheme of image data and decoding scheme, implements LDPC decoder in FPGA.

• Proceedings of the Korea Water Resources Association Conference
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• 2019.05a
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• pp.104-104
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• 2019

기후 관측자료의 경우 관측, 가공, 전송 중에 오류가 발생할 수 있으며, 특히 글로벌 기후자료는 다양한 조건을 가지고 있는 자료를 수집하였기 때문에 일반적으로 해당 국가 관측자료보다 품질이 낮다. 본 연구에서는 글로벌 기후 관측자료의 품질을 개선할 수 있는 품질관리 기법을 개발하고 국내 지역에 적용해보고자 한다. 연구대상지역으로 국내 대표도시 7 곳을 선정하였으며, 글로벌 기후자료는 NCDC (National Climatic Data Center)의 일 단위 GSOD (Global Surface Summary of the Day) 자료를 수집하였다. 품질관리는 강수와 기온에 대해서 실시하였으며 과정은 크게 이상치 검사, 이상치 및 결측치 보정, 연, 월 단위 기후 자료 산정으로 구분된다. 이상치 검사는 중복성 검사, 내적일치성 검사, 기후범위 검사, 공간동질성 검사를 기반으로 구성되어 있다. 이상치 및 결측치 보정은 인접 관측소의 자료를 보간하여 수행하였으며, 보간기법은 4 방향 역거리 가중법을 활용하였다. 연, 월 단위 자료 산정은 자료의 결측률을 고려하여 일 단위 자료를 연, 월 단위 자료로 변환하는 과정이다. 이상치 검사 결과 대부분의 이상치는 기후범위와 공간동질성 검사에서 발견되는 것으로 나타났으며, 중복성 및 내적일치성 검사는 이상치 검출 효과가 적은 것으로 나타났다. 결측치 및 이상치 보간 결과 추정된 자료와 관측값 간의 상관관계가 있는 것으로 나타나 활용성이 있었다. 본 연구는 글로벌 자료의 품질관리 기법을 제시하였다는 점에서 활용성이 있으며, 향후 품질관리 기법의 검증에 관한 연구를 수행할 필요가 있다.

• The Transactions of the Korea Information Processing Society
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• v.1 no.2
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• pp.263-271
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• 1994

Automation of production in modern manufacturing is based on the integration of the various stage of production process by means of processing system. Information processing and network interface are of fundamental importance in programmable device in industrial automation, as they essential in order to active integration in production lines. In this paper, TBC(token bus controller) in the Mini-MAP board performs the function of the MAC sublayer, The LLC sublayer is implemented according to the specification of Class 3 that includes Type 1 and 3. And the MMS services are designed within the scope of implementation MAP 3.0 All the softwares are implemented under the real time executive for real time application of the Mini-MAP and they are loaded into PROMs at the network board. We tested the LLC functions to make use of a protocol analyzer for the token bus protocol. Also the MMS conformance test was carried out by exchanging primitives between a model system(including NIU) and a MMS product that had already passed the conformance the conformance test based on measurement method of network analysis.

• The Journal of the Acoustical Society of Korea
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• v.32 no.1
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• pp.22-31
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• 2013

In this paper, we propose a method that estimates the channel response from underwater communication signals with MMSE (Minimun Mean Squared Error) and detects dominant components automatically based on power of response components using CFAR (Constant False Alarm Rate). Statistical characteristics are analyzed with variation of magnitude and phase and time coherence via experimental data obtained by drifting transmitter and receiver. We show that bit error rate has small difference, 1.2 times, compared with the case using every channel information estimated within data period when estimation and equalization is performed with extracted characteristic obtained by the proposed method.

• 전자공학회논문지 IE
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• v.43 no.4
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• pp.115-121
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• 2006

In this paper, we proposed about data error check and correction on channel transmission in the communication system. LDPC codes are used for minimizing channel errors by modeling AWGN Channel as a VDSL system. Because LDPC Codes use low density parity bit, mathematical complexity is low and relating processing time becomes shorten. Also the performance of LDPC code is better than that of turbo code in long code word on iterative decoding algorithm. This algorithm is better than conventional algorithms to correct errors, the proposed algorithm assigns weights for errors concerning parity bits. The proposed weighted Bit-flipping algorithm is better than the conventional Bit-flipping algorithm and we are recognized improve gain rate of 1 dB.

• Journal of the Institute of Electronics and Information Engineers
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• v.54 no.3
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• pp.3-9
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• 2017

Recently, in 3rd Generation Partnership Project(3GPP), there is a study of the Long Term Evolution(LTE) based vehicle communication which has been actively conducted to provide a transport efficiency, telematics and infortainment. Because the vehicle communication is closely related to the safety, it requires a reliable communication. Because vehicle speed is very fast, unlike the movement of the user, radio channel is rapidly changed and generate a number of problems such as transmission quality degradation. Therefore, we have to continuously updates the channel estimates. There are five types of conventional channel estimation scheme. Least Square(LS) is obtained by pilot symbol which is known to transmitter and receiver. Decision Directed Channel Estimation(DDCE) scheme uses the data signal for channel estimation. Constructed Data Pilot(CDP) scheme uses the correlation characteristic between adjacent two data symbols. Spectral Temporal Averaging(STA) scheme uses the frequency-time domain average of the channel. Smoothing scheme reduces the peak error value of data decision. In this paper, we propose the novel channel estimation scheme in LTE based Vehicle-to-Vehicle(V2V) environment. In our Hybrid Reliable Channel Estimation(HRCE) scheme, DDCE and Smoothing schemes are combined and finally the Linear Minimum Mean Square Error(LMMSE) scheme is applied to minimize the channel estimation error. Therefore it is possible to detect the reliable data. In simulation results, overall performance can be improved in terms of Normalized Mean Square Error(NMSE) and Bit Error Rate(BER).