• Title/Summary/Keyword: Coherent systems

Search Result 232, Processing Time 0.021 seconds

A Study on Adaptive Linear MMSE Detector for DS-CDMA Reverse Link in Rayleigh Fading Environment (레일리 페이딩 환경하에서 DS-CDMA 역방향 링크에 적용 가능한 적응 선형 MMSE 수신기의 연구)

  • 안태기;이병섭;김성락;이정구
    • The Journal of Korean Institute of Electromagnetic Engineering and Science
    • /
    • v.9 no.2
    • /
    • pp.131-140
    • /
    • 1998
  • MAI(Multi-Access Interference) and fast channel variation due to the fading environment are the major problems in the mobile CDMA communication systems. Recently, interest has been increasing in applying the Adaptive Linear MMSE Detector to MAI cancellation in the CDMA reverse link. In this paper, we propose a modified Adaptive Linear MMSE Detector structure which can be used in Long-duration code CDMA system in the presence of independent Rayleigh fading. We use independent multiple tap-weight vector structure to cope with the variation of spreading sequence pattern between neighbor symbols because of the Long-duration code. In this case, more exact channel parameter estimation is required. To solve this problem, we use coherent CDMA structure which can track the channel parameters like amplitude and phase by employing the low power pilot channel in the CDMA reverse link.

  • PDF

Multimodal Nonlinear Optical Microscopy for Simultaneous 3-D Label-Free and Immunofluorescence Imaging of Biological Samples

  • Park, Joo Hyun;Lee, Eun-Soo;Lee, Jae Yong;Lee, Eun Seong;Lee, Tae Geol;Kim, Se-Hwa;Lee, Sang-Won
    • Journal of the Optical Society of Korea
    • /
    • v.18 no.5
    • /
    • pp.551-557
    • /
    • 2014
  • In this study, we demonstrated multimodal nonlinear optical (NLO) microscopy integrated simultaneously with two-photon excitation fluorescence (TPEF), second-harmonic generation (SHG), and coherent anti-Stokes Raman scattering (CARS) in order to obtain targeted cellular and label-free images in an immunofluorescence assay of the atherosclerotic aorta from apolipoprotein E-deficient mice. The multimodal NLO microscope used two laser systems: picosecond (ps) and femtosecond (fs) pulsed lasers. A pair of ps-pulsed lights served for CARS (817 nm and 1064 nm) and SHG (817 nm) images; light from the fs-pulsed laser with the center wavelength of 720 nm was incident into the sample to obtain autofluorescence and targeted molecular TPEF images for high efficiency of fluorescence intensity without cross-talk. For multicolor-targeted TPEF imaging, we stained smooth-muscle cells and macrophages with fluorescent dyes (Alexa Fluor 350 and Alexa Fluor 594) for an immunofluorescence assay. Each depth-sectioned image consisted of $512{\times}512$ pixels with a field of view of $250{\times}250{\mu}m^2$, a lateral resolution of $0.4{\mu}m$, and an axial resolution of $1.3{\mu}m$. We obtained composite multicolor images with conventional label-free NLO images and targeted TPEF images in atherosclerotic-plaque samples. Multicolor 3-D imaging of atherosclerotic-plaque structural and functional composition will be helpful for understanding the pathogenesis of cardiovascular disease.

The Research on Coherence of Legal System for Systematic Development of Spatial Information (공간정보의 체계적 발전을 위한 법제도적 정합성에 관한 연구)

  • Kim, Hyun-Hee;Lim, Hyung-Taek
    • Journal of Cadastre & Land InformatiX
    • /
    • v.45 no.1
    • /
    • pp.1-15
    • /
    • 2015
  • Korea's Spatial Information Policy has been institutionalized based by "National Spatial Data Infrastructure Act", "Act on Land Survey, Waterway Survey and Cadastral Records", "Spatial Data Industry Promotion Act". In year 2015, These acts were modified with new names and contents. It is critical that the definition of spatial information ought to be generalized. In addition, it is of paramount importance to review factors those contribute to the systematic development on coherent relation between Spatial Information Act and other acts. Examples of improvement area may include: Categorization of Spatial Information Concept, Systematization of Spatial Data Related Legislation, and Enhancement of Organization Specializing in Spatial Information. Furthermore, Legislation & Policy case of Germany, France and the United States were used as a basis for improvement.

Receiver Design for OFDM based Wireless LAN and Its Performance Evaluation in Mobile Environment (이동 환경에서 OFDM 기반 무선랜의 수신을 위한 수신기 설계 및 성능 평가)

  • Seo, Kang-Woon;Yoon, Seok-Hyun;Kim, Baek-Hyun;Kim, Yong-Kyu
    • Journal of the Institute of Electronics Engineers of Korea TC
    • /
    • v.48 no.11
    • /
    • pp.1-8
    • /
    • 2011
  • In this paper, we study receiver design issue to apply the OFDM based WLAN specification, such as 802.11p, to the communications in high speed mobile environment, e.g., for the ICT based railroad control on a train having its speed up to 300 km/hr. To successfully apply the existing WLAN specifications without modifying its transmission format, the performance at the receiver will solely depends on the channel estimation performance if we ignore the affect of frequency offset With a speed of multiple hundred km/hr, the channel estimation using only the preamble will not provide enough precision since the channel changes so fast. Therefore, in this paper, taking the high mobility into account, we focus on the design of decision directed channel estimation and equalization techniques and perform simulations to evaluate and compare their performances and to finally confirm the applicability of the existing WLAN specification to the systems with very high mobility.

The Concept and Analysis of Redundant Information in Space Perception - Focused on the Works of NOX - (공간지각에 있어 잉여정보의 의미와 분석 - NOX의 공간을 중심으로-)

  • Kim, Joo-Mi
    • Korean Institute of Interior Design Journal
    • /
    • v.15 no.6 s.59
    • /
    • pp.77-88
    • /
    • 2006
  • According to critics and architects, non-linear structure is not only an organic form of space, but also a form of space detached from modem style. Accordingly, non-linear structure can be accepted as an alternative to what has remained unsolved by deconstructionist. However, they are criticized for not clarifying the interdependent relationship between non-linearity of space and cognitive structure of human being. They ended up remaining the hypothesis just an intuitive and abstract one. This research began on the basis that their hypothesis is hard to be objectified, and it needs further inquiry. The purpose of this thesis is to explore how the redundant factors constitute non-linear structures of digital media centered space design. Geometric compositions of space structure were analyzed to define what types of redundant factors are contrived in the process of visual information. This study about the visual form, researching the Information Theory, and then offer a quantitative analysis that makes those more objective. Space structure and geometric composition were analyzed to define what types of redundancy are contrived in the process of visual information. In particular, I put higher theoretical emphasis on what characteristics are ensued in the process of structuring spaces than any other subjects. Followings are the conclusion of analysis. First, as a result of examining, we can assume that NOX' space structure is not a chaotic form, but has an operating the form of its own. Second, in case of curvilinear, the structure was found redundancy on mid deviation ratio and discontinuous circular fabric. Although most of their structures appeared complex with a higher coherent constant, they were found to be stable factors because of the low deviation ratio between systems. The amount of surplus information was stable structure as well.

A Study on the Industrial Applications of Quantum Information Processing and Communication (퀀텀정보통신기술의 산업적 응용가능성에 관한 연구)

  • Kwon, Moon-Ju;Kim, Richard C.S.;Park, Seong-Taek;Kim, Tae Ung
    • Journal of Digital Convergence
    • /
    • v.11 no.7
    • /
    • pp.173-184
    • /
    • 2013
  • Quantum Information Processing and Communication, based on the physical laws of Quantum mechanics, exploits fundamentally new modes of computation and communication and holds the promise of immense computing power beyond the capabilities of any classical computer. In Quantum Information Processing, replacing bits with qubits, one makes two-state quantum systems that do not possess in general the definite values of 0 or 1 of classical bits, but rather are in a so-called. "coherent superposition", of the two. Full exploitation of this additional freedom implies that new processing devices need to be designed and implemented, and that a large scale quantum computer can in principle be built. New discoveries will enable a range of exciting new possibilities including: greatly improved sensors with potential impact for mineral exploration and improved medical imaging and a revolutionary new computational paradigm that will likely lead to the creation of computing devices capable of efficiently solving problems that cannot be solved on a classical computer. In short, Quantum computing is an economy game changer, with a potential of disrupting entire industries and creating new ones.

Unified DC Offset Cancellation and I/Q Regeneration with Carrier Phase Recovery in Five-Port Junction based Direct Receivers (Five-port 접합을 이용한 RF 수신기를 위한 동시 DC 오프셋 제거와 I/Q 신호 재생 알고리즘)

  • Park, Hyung-Chul;Lim, Hyung-Sun;Yu, Jong-Won
    • Journal of the Institute of Electronics Engineers of Korea TC
    • /
    • v.44 no.6 s.360
    • /
    • pp.64-70
    • /
    • 2007
  • This paper presents a novel unified DC offset cancellation and I/Q regeneration for five-port junction based direct receivers. It utilizes the symmetry characteristics of the single-frequency continuous-wave (CW) signal, making it possible that the proposed method can be used regardless of carrier phase offset. The proposed method eliminates the additional DC offset cancellation and reduces the I/Q regeneration parameter estimation time. Since the proposed method employs a single-frequency CW signal independent of the modulation scheme, five-port junction based direct receivers can be used for the demodulation of orthogonal frequency-division multiplexing and continuous phase modulation as well as phase shift-keying.

Performance Evaluation for Fast Closed-Loop Power Control of cdma2000 Forward Link in frequency-Selective Rayleigh Fading Channel (주파수 선택적 Rayleigh 페이딩 채널에서 cdma2000 순방향링크의 고속 폐루프 전력제어에 대한 성능 평가)

  • 강법주;남윤석
    • The Journal of Korean Institute of Communications and Information Sciences
    • /
    • v.26 no.11B
    • /
    • pp.1522-1533
    • /
    • 2001
  • In this paper, we handle the estimation method of the received $E_{b}l1_{o}$ for forward closed-loop power control in cdma2000 systems. The estimation of MS-received $E_{b}l1_{o}$ utilizes the symbols related to the forward power control subchannel transmission. The estimation of the received bit energy and noise variance is analyzed for the frequency-selective Rayleigh fading channel. In order to improve SIR (signal-to-interference), the estimation of the received bit energy is made by the coherent combining of the rake-fingers and received I/Q symbols. And, in this paper, we evaluate the performance of forward closed-loop power control according to the mobile speed and the power adjustment step size in terms of the bit error rate (BER) and power control error. Simulation results present the optimal power adjustment step sizes according to the mobile speeds.

  • PDF

Web Service based Recommendation System using Inference Engine (추론엔진을 활용한 웹서비스 기반 추천 시스템)

  • Kim SungTae;Park SooMin;Yang JungJin
    • Journal of Intelligence and Information Systems
    • /
    • v.10 no.3
    • /
    • pp.59-72
    • /
    • 2004
  • The range of Internet usage is drastically broadened and diversed from information retrieval and collection to many different functions. Contrasting to the increase of Internet use, the efficiency of finding necessary information is decreased. Therefore, the need of information system which provides customized information is emerged. Our research proposes Web Service based recommendation system which employes inference engine to find and recommend the most appropriate products for users. Web applications in present provide useful information for users while they still carry the problem of overcoming different platforms and distributed computing environment. The need of standardized and systematic approach is necessary for easier communication and coherent system development through heterogeneous environments. Web Service is programming language independent and improves interoperability by describing, deploying, and executing modularized applications through network. The paper focuses on developing Web Service based recommendation system which will provide benchmarks of Web Service realization. It is done by integrating inference engine where the dynamics of information and user preferences are taken into account.

  • PDF

Institutional Quality, Regulatory Environment and Microeconomic Performance: Evidence from Transition and Non-transition Developing Countries

  • Ochieng, Haggai Kennedy;Park, Bokyeong
    • East Asian Economic Review
    • /
    • v.25 no.3
    • /
    • pp.273-309
    • /
    • 2021
  • The development of regulatory systems varies between transition and non-transition economies. This suggests that they provide different incentives for entrepreneurial development and could have varied effects on the economy because they have different methods to deal with market failure. However, limited empirical evidence exists to prove the assumption of dichotomy. Using comprehensive data for institutional quality, labor market and financial market development, this research sought to analyze their effect on employment growth at micro level. The results show that the quality of institutions in transition economies are poorer relative to those in non-transition economies, but their financial and labor markets are more developed than the latter. Further analysis for the transition sample shows that the three variables are individually positively related with employment growth. For the non-transition sample, institutional quality and labor market flexibility bear a positive and significant effect on employment. Financial market development enters the model with a negative coefficient when regressed alone, but a joint test of significance finds that all the variables have a positive effect on employment growth. This result could imply that there is interdependence between institutional quality, labor flexibility and financial market development in firm-employment-growth relationship, or complementarity between regulations and the quality of institutions. Alternatively, this finding suggests that a stringently regulated credit market in non-transition economies have a selection effect-allocating credit only to entrepreneurs who already demonstrate strong growth potential. In sum, despite differences in the evolution of regulatory environment between the two samples, both of them complement employment growth at firm level. The overall implication of these findings is that less rigid regulations and coherent policies that are enforced with impartiality provide incentives for firms to expand.