• ETRI Journal
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• 제20권1호
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• pp.16-27
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• 1998

In this paper, we consider the acquisition performance of an IS-95 reverse link access channel slot as a function of system design parameters such as postdetection integration length and the number of access channel message block repetitons. The uncertainty region of the reverse link spreading codes compared to that of forward link is very small, since the uncertainty region of the reverse link is determined by a cell radius. Thus, the parallel acquisiton technique in the reverse link is more efficient than a serial acquisition technique in terms of implementation and of acquisition time. The parallel acquisition is achieved by a bank of N parallel I/Q noncoherent correlator are analyzed for band-limited noise and the Rayleigh fast fading channel. The detection probability is derived for multiple correct code-phase offsets and multipath fading. The probability of no message error is derived when rake combining, access channel message block combining, and Viterbi decoding are applied. Numerical results provide the acquisition performance for system design parameters such as postdetection integration length and number of access channel message block repetitions in case of a random access on a mobile station.

• Journal of Communications and Networks
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• 제18권3호
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• pp.439-445
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• 2016

In this paper, we consider subcarrier-index modulation (SIM) for precoded orthogonal frequency division multiplexing (OFDM) with a few activated subcarriers per user and its generalization to multi-carrier multiple access systems. The resulting multiple access is called sparse index multiple access (SIMA). SIMA can be considered as a combination of multi-carrier code division multiple access (MC-CDMA) and SIM. Thus, SIMA is able to exploit a path diversity gain by (random) spreading over multiple carriers as MC-CDMA. To detect multiple users' signals, a low-complexity detection method is proposed by exploiting the notion of compressive sensing (CS). The derived low-complexity detection method is based on the orthogonal matching pursuit (OMP) algorithm, which is one of greedy algorithms used to estimate sparse signals in CS. From simulation results, we can observe that SIMA can perform better than MC-CDMA when the ratio of the number of users to the number of multi-carrier is low.

• Journal of Magnetics
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• 제7권3호
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• pp.101-105
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• 2002

MRAM (Magnetoresistive Random Access Memory) is a promising candidate for a universal memory that meets all application needs with non-volatile, fast operational speed, and low power consumption. The simplest architecture of MRAM cell is a series of MTJ (Magnetic Tunnel Junction) as a data storage part and MOS transistor as a data selection part. This paper is for testing the actual electrical parameters to adopt MRAM technology in the semiconductor based memory device. The discussed topics are an actual integration of MRAM core cell and its properties such as electrical tuning of MOS/MTJ for data sensing and control of magnetic switching for data writing. It will be also tested that limits of the MRAM technology for a high density memory.

• 한국인터넷방송통신학회논문지
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• 제8권3호
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• pp.57-70
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• 2008

This paper introduces a new paradigm of physical layer security through channel coding for wireless networks. The well known spread spectrum based physical layer security in wireless network is applicable when code division multiple access (CDMA) is used as wireless air link interface. In our proposal, we incorporate the proposed security protocol within channel coding as channel coding is an essential part of all kind of wireless communications. Channel coding has a built-in security in the sense of encoding and decoding algorithm. Decoding of a particular codeword is possible only when the encoding procedure is exactly known. This point is the key of our proposed security protocol. The common parameter that required for both encoder and decoder is generally a generator matrix. We proposed a random selection of generators according to a security key to ensure the secrecy of the networks against unauthorized access. Therefore, the conventional channel coding technique is used as a security controller of the network along with its error correcting purpose.

• JSTS:Journal of Semiconductor Technology and Science
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• 제16권2호
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• pp.147-152
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• 2016

In this study, we fabricated Ag-based electrochemical metallization memory devices which is also called conductive-bridge random-access memory (CBRAM) in order to investigate the resistive switching behavior depending on the bottom electrode (BE). RRAM cells of two different layer configurations having $Ag/Si_3N_4/TiN$ and $Ag/Si_3N_4/p^+$ Si are studied for metal-insulator-metal (MIM) and metal-insulator-silicon (MIS) structures, respectively. Switching voltages including forming/set/reset are lower for MIM than for MIS structure. It is found that the workfunction different affects the performances.

• 한국방송∙미디어공학회:학술대회논문집
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• 한국방송∙미디어공학회 2016년도 하계학술대회
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• pp.264-266
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• 2016

During the $2^{nd}$ JVET (Joint Group on Future Video Coding Technology Exploration) meeting, up to 22 coding tools focusing on Future Video Coding (FVC) were proposed. Despite that the application of proposed coding tools has a considerable performance enhancement, however, the encoding time of Joint Exploration Model (JEM) software is over 20 times for All Intra coding mode, 6 times for Random Access coding mode, of HEVC reference model (HM), and decoding time is 1.6 times for All Intra coding mode, 7.9 times for Random Access coding mode, of HM. This paper focuses on analyzing the complexity of the JEM software compared with HM.

• 한국재료학회:학술대회논문집
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• 한국재료학회 2003년도 추계학술발표강연 및 논문개요집
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• pp.180-180
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• 2003

FRAM (Ferroelectric Random Access Memory)은 DRAM(Dynamic Random Access Memory)in 커패시터 재료을 상유전체 물질에서 강유전체 물질로 대체하여 전원 공급이 차단되어도 정보를 기억할 수 있고, 데이터의 고속처리가 가능하고 저소비전력과 집적화가 뛰어난 차세대 메모리 소자이다. 본 연구에서는 n-Well/P-Si(100) 기판위에 $Y_2$O$_3$ 박막을 중간층 (buffer layer)으로 사용하여 (Bi,La) Ti$_3$O$_{12}$ (BLT) 강유전체 박막을 졸-겔 방법으로 형성하여 MFM(I)S(Metal Ferroelectric Metal (Insulation) Silicon) 구조의 커패시터 및 전계효과형 트랜지스터(Field Effect Transistor) 소자를 제작하였다. 제작된 소자에 대해 형상학적, 전기적 특성을 조사, 분석하였다.

• 한국항해항만학회:학술대회논문집
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• 한국항해항만학회 2007년도 추계학술대회 및 제23회 정기총회
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• pp.226-227
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• 2007

항만 물동량의 증가로 자동화 항만 시스템에 대한 연구가 활발히 진행되고 있다. 본 연구는 선형 모터 기반 이송 장비인 LMTT 시스템의 자동화 운용에 있어 충돌 및 교착상태를 방지하기 위해 Random Access Sequence Dynamic Programming(RAS DP)를 이용한 최적 경로 탐색 알고리즘을 제안한다. 제안하는 알고리즘은 실시간으로 각 shuttle car의 최적 경로를 탐색한다.

• 방송공학회논문지
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• 제23권5호
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• pp.718-721
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• 2018

최근 차세대 국제 비디오 압축 표준 제정에 딥러닝을 이용하여 비디오 부호화 효율을 향상시키기 위한 다양한 시도가 이루어지고 있다. 본 논문에서는 참조프레임 리스트에 포함된 복원 프레임을 이용하여 현재 프레임의 가상 참조프레임을 딥러닝으로 생성하여 화면 간 예측 부호화에 이용하는 알고리즘을 제안한다. 실험에 따르면 제안 알고리즘은 HEVC 참조 소프트웨어 대비 Random Access 실험 환경에서 평균 1.9%의 BD-rate 감소 효율을 제공한다.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2002년도 ITC-CSCC -2
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• pp.1350-1353
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• 2002

A new form of spread spectrum technique called the ultra wideband impulse radio (UWB-IR) system has drawn much attention for future high speed wireless communication services. In this paper, a new type of time hopping sequences constructed from multiple distinct m-sequences of the same order, is proposed for multiple access in the UWB-IR systems. Simulation results reveal that the proposed time hopping sequences achieve comparable or even better bit error rate performance than the ideal random sequences, and can be effectively applied in various multiple access situations.