• Journal of the Korea Institute of Information and Communication Engineering
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• v.20 no.10
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• pp.1881-1886
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• 2016

In this paper, by using D2D communications that perform direct communications among devices within small transmission range of each device without base station, we assume that a device generates and transmits data packets to other proximate devices and the devices which receive the data packets relay those to other adjacent devices. To maximize the total number of devices which successfully receive data packets, Epidemic routing protocol is considered in this paper. In Epidemic routing protocol, all devices which received data packets try to relay the packets to other adjacent devices. We assume various network environment where devices are densely distributed in specific area(crowded area). In this environment, D2D SD can be a source node and D2D devices can be relay nodes. By setting transmission range of D2D SD and D2D devices as parameters, we analyze performance results of coverage probability of Epidemic routing protocol through intensive simulations.

• Membrane Journal
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• v.10 no.3
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• pp.139-147
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• 2000

Non-Fickian (or anomalous) diffusion was observed in transient sorption of aromatic solvents(such as benzene, toluene, and chlorobenzene) in fluoropolymers (such as ETFE, ECTFE and PVDF). In this study, five other transient sorption models (Crank, Long ＆ Richman, Berens ＆ Hopfenberg, Neogi, Li) based on Fick's law were employed to fit the anomalous sorption data for aromatic solvents. The adjustable parameters were determined by least square analysis of the measured and predicted fractional uptake. For ETFE sorption data slightly deviating from Fickian behavior, all the models exhibited satisfactory results in fitting the anomalous sorption data. In particular, Neogj model predicted intrinsic diffusivity (0.4～0.8$\times$10$^{-5}$ $\textrm{cm}^2$/day) and equilibrium diffusivity (0.13～0.31$\times$10$^{-4}$ $\textrm{cm}^2$/day) as well as relaxation kinetics related to non-Fickain diffusion. For a typical sigmoidal sorption behavior in PVDF, only Crank's model could give the reasonable evaluation on transport properties. The ratio of intial diffusivity (D$_{i}$) to final equilibrium diffusivity (D$_{\infty}$) was ranged from 80 to 200. For the final stage of uptake In ECTFE with drastic acceleration, all the models exhibited significant deviations from the sorption data. New diffusion models based on thermodynamics and continuum mechanics should be employed to get valuable information on transport properties as well as relaxation kinetics coupled with non-Fickian diffusion.

• Journal of the Korean Institute of Telematics and Electronics D
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• v.35D no.6
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• pp.37-45
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• 1998

In this paper, we report the first three-dimensional simulation result of the transient enhanced diffusion(TED) of dopants in the ion-implanted silicon by employing our 3D semiconductor process simulator, INPROS system. In order to simulate three-dimensional TED redistribution of dopants in silicon, the dopant distributions after the ion implantation was calculated by Monte Carlo(MC) method, followed by finite element(FE) numerical solver for thermal annealing. Excellent agreement between the simulated 3D profile and the SIMS data has been obtained for ion-implanted arsenic and phosphorus after annealing the boron marker layer at 75$0^{\circ}C$ for 2 hours. Our three-dimensional TED simulation could successfully explain the reverse short channel effect(RSCE) by taking the 3D point defect distribution into account. A coupled TED simulation and device simulation allows reverse short channel effect on threshold to be accurately predicted.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.46 no.8
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• pp.1-9
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• 2009

In this paper, we describe DSSS transceiver development robust to jamming signals as an investigation of ECCM transceiver for UAV uplink. The jamming margin is 15dB or greater with the development target of transceiver because the jamming margin is more important than the transmission rate of data and the spreading code can be changeable. The rake receiver is applied to combine multipath components and turbo code which the coding gain is 7.2dB as a FEC. In this paper, the whole structure, design method and functional test result about the designed modem are described and a conclusion is made.

• Proceedings of the Acoustical Society of Korea Conference
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• autumn
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• pp.487-490
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• 2004

OFDM(Orthogonal Frequency Division Multiplexing) 방식의 수중음향 데이터 통신시스템에서 도플러 편이(Doppler Shift)와 도플러 확산(Doppler Spread)의 영향을 완화하여 주파수 효율을 향상시킬 수 있는 수신신호처리 방안을 설계하고 해상에서 송수신 된 시험 데이터의 BER 로써 성능을 평가한다. 도플러 편이를 OFDM 심볼에 부가된 Cyclic Prefix 와 상관계수법을 통해 추정하였으며 도플러 확산에 의해 시간에 따라 변화하는 채널을 Time-Frequency 축상에서 $2\times1D$ MMSE 방식으로 추정한다. 해상실험 결과, $8kHz\~11kHz$ 의 전송대역을 사용 할 때 복호 전 전송률 3098bps, 송수신 소자간 거리 7km, SNR 15dB에서 약 $1\~3\%$의 BER이 추정된다.

• The KIPS Transactions:PartD
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• v.10D no.2
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• pp.309-316
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• 2003

In this paper, we propose a new watermarking method based on spread spectrum and a semi-fingerprinting system architecture that can be built using our robust watermarking method. Especially, we describe a method that extends the application area of watermarking technology to more practical application domains by applying the watermarking technology that has been focused mainly on copyright protection to fingerprinting area. Our proposed watermarking scheme uses the method that inserts more data by using random number shifting method. We improved the reliability of acquired data with 20-bits CRC code and 60-bits inserted information. In addition, we designed the system architecture based on the recommendation of cIDf (content ID forum) in order to apply the system on the semi-fingerprinting area.

• The KIPS Transactions:PartD
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• v.15D no.2
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• pp.163-170
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• 2008

Due to the proliferation of the Internet and intranet, a new application domain called stream data processing has emerged. Stream data is real-timely and continuously generated. In this paper, we focus on the processing of stream data whose characteristics vary unpredictably by over time. Particularly, we suggest a method which generates an efficient operator execution order called WT-Heuristics. WT-Heuristics efficiently determines the operator execution order since it considers only two adjacent operators in the operator execution order. Also, our method changes the execution order with respect to the change of data characteristics with minimum overheads.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.26 no.10B
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• pp.1428-1435
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• 2001

본 논문에서는 이미지 데이터의 저작권 보호를 위해 영상변형, JPEG 손실 압축 및 임펄스 잡음에 효과적인 새로운 DM/SS (Direct Matrix/Spread Spectrum) 이미지 워터마킹 기법을 제안한다. 제안하는 기법은 워터마크 영상을 저작권자의 개인 ID (IDentification)로 확산시킨 다음, 원 영상에 삽입하고 역확산시켜 복원하는 방법이다. 원터마크 영상은 2진 영상을 사용하고, 워터마크 시스템에서 요구되는 비가시성과 외부 공격에 대한 워터마크의 강인성을 확인하기 위하여 PSNR (Peak Signal to Noise Ratio)과 워터마크 영상의 복원율 (reconstructive rate)을 구한다. 실험 결과, 워터마크가 삽입된 영상의 PSNR은 93.75 dB로 화질저하가 거의 없었고, 확산 이득으로 인하여 32$\times$32 워터마크 영상이 삽입된 영상에서 우수한 워터마크 영상의 복원율을 얻는다는 것을 보인다. 영상변형 및 JPEG 손실 압축 하에서도 우수한 워터마크 복원 결과를 보였고, 임펄스 잡음이 첨가된 영상의 PSNR이 5.54 dB인 경우에도 효과적으로 워터마크 영상을 복원할 수 있다는 것을 알 수 있었다.

• Journal of Satellite, Information and Communications
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• v.8 no.4
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• pp.75-80
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• 2013

In this paper, the Ka-band maritime satellite communication systems for mobile terminals are proposed. The design includes the link budget analysis, determination of modulation and coding schemes and the overall structure of a transmitter. To avoid the harmful effects on the existing DVB-S2 services, the proposed maritime satellite system using the same spectrum with DVB-S2 at the same time employs the very wideband spreading transmission. Additionally, omni-directional low-gain antennas should be equipped in a mobile terminal to reduce the system cost. These two considerations limit the maximum transmission rate of the proposed system. Due to the limitations, the proposed system includes 36 dB or 39 dB spreading gain depending on the modulation scheme and a link-adaptive repetition method depending on the level of rain attenuation. To support short packets with minimal performance loss, the turbo code used in 3GPP instead of LDPC(low density parity check code) is adopted. By combining them, the overall structure of low-rate maritime satellite communication system is designed.

• Proceedings of the Korea Information Processing Society Conference
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• 2021.11a
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• pp.499-502
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• 2021

정부는 '한국판 뉴딜 1.0'(2020.7)과 '한국판 뉴딜 2.0'(2021.7)을 발표하여 국가의 새로운 미래를 설계하고자 디지털뉴딜, 그린 뉴딜, 휴먼 뉴딜, 지역균형 뉴딜 분야에 집중 지원 중이다. 이 중 디지털 뉴딜은 사회, 경제 전반에 걸친 디지털화의 확산 및 디지털 신사업 육성이 목표이다. 본 논문에서는 디지털 뉴딜과 관련해 인공지능(AI)과 이동통신(5G) 분야에 대해 국가R&D 지원 현황 등을 분석하였다. 분석 데이터는 2015년부터 2020년까지 NTIS에서 서비스하는 총 61,356건 과제와 총 198,355건 성과정보를 키워드 추출을 통하여 수집하였다. 데이터 분석 결과 각 분야의 과제와 연구비, 논문 성과는 지속적으로 증가하고 있으나, 특허 성과는 최근 소폭 감소하는 것을 알 수 있었다. 정부가 추진하는 한국판 뉴딜 정책의 혁신성장 성과분야에 대해 이용자가 바로 파악할 수 있도록 다양한 분석을 통하여 향후 NTIS에서 서비스할 계획이다.