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Parallel Processing Method for Generating Elemental Images from Hexagonal Lens Array (육각형 렌즈 어레이로부터 요소영상을 생성하기 위한 병렬 처리 기법)

  • Kim, Do-Hyeong;Park, Chan;Jung, Ji-Sung;Kwon, Ki-Chul;Kim, Nam;Yoo, Kwan-Hee
    • The Journal of the Korea Contents Association
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    • v.12 no.6
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    • pp.1-8
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    • 2012
  • According that most integral imaging techniques have used rectangular lens array, this integrated distribution of light is recorded in the form of a rectangular grid. However, hexagonal lens array gives a more accurate approximation of ideal circular lens and provides higher pickup/display density than rectangular lens array[4]. Using the parallel processing technique in order to generate the elemental imaging for hexagonal lens array, each pixel that compose the elemental imaging should be determined to belong to the hexagonal lens. This process is output to the screen for every pixel in progress, and many computations are required. In this paper, we have proposed parallel processing method using an OpenCL to generate the elemental imaging for hexagonal lens array in 3D volume date. In the experimental result of proposed method show speed of 20~60 fps for hexagonal lens array of $20{\times}20$ sizes and input data of Male[$128{\times}256{\times}256$] volume data.

A 4-Channel Multi-Rate VCSEL Driver with Automatic Power, Magnitude Calibration using High-Speed Time-Interleaved Flash-SAR ADC in 0.13 ㎛ CMOS

  • Cho, Sunghun;Lee, DongSoo;Lee, Juri;Park, Hyung-Gu;Pu, YoungGun;Yoo, Sang-Sun;Hwang, Keum Cheol;Yang, Youngoo;Park, Cheon-Seok;Lee, Kang-Yoon
    • JSTS:Journal of Semiconductor Technology and Science
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    • v.16 no.3
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    • pp.274-286
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    • 2016
  • This paper presents a 4-channel multi-rate vertical-cavity surface-emitting laser (VCSEL) driver. In order to keep the output power constant with respect to the process, voltage, temperature (PVT) variations, this research proposes automatic power and magnitude. For the fast settling time, the high-speed 10-bit time-interleaved Flash-successive approximation analog to digital converter (Flash-SAR ADC) is proposed and shared for automatic power and magnitude calibration to reduce the die area and power consumption. This chip is fabricated using $0.13-{\mu}m$ CMOS technology and the die area is $4.2mm^2$. The power consumption is 117.84 mW per channel from a 3.3 V supply voltage at 10 Gbps. The measured resolution of bias /modulation current for APC/AMC is 0.015 mA.

A low complexity ZF Equalization for OFDM Systems over Time-varying Channels (OFDM 시스템을 위한 복잡도가 감소된 ZF 등화기법)

  • Park, Ji-Hyun;Hwang, Seung-Hoon;Whang, Keum-Chan
    • Journal of the Institute of Electronics Engineers of Korea TC
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    • v.45 no.4
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    • pp.1-8
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    • 2008
  • In orthogonal frequency division multiplexing (OFDM) system the time selectivity of wireless channel introduces intercarrier interference (ICI), which degrades system performance in proportion to Doppler frequency. To mitigate the ICI effect, we can generally employ a classical zero-forcing (ZF) equalizer. However, the ZF scheme requires an inverse of a large matrix, which results in prohibitively high computational complexity. In this paper, we propose a low complexity ZF equalization scheme for suppressing the ICI caused by highly time-varying channels in OFDM systems. From the fact that the ICI on a subcarrier is mainly caused by several neighboring subcarriers, the proposed scheme exploits a numerical approximation for matrix inversion based on Neumann's Series (truncated second order). To further improve performance, the partial ICI cancellation technique is also used with reduced complexity. Complexity analysis and simulation results show that the proposed scheme provides the advantage of reducing computational complexity significantly, while achieving almost the same performance as that of the classical ZF a roach.

Ab Initio Studies on Hydrogen-Bonded Trimers Formed between Hydrogen Cyanide and Hydrogen Fluorides (시안화수소와 플루오르화수소와의 수소결합 삼합체들에 관한 Ab Initio 연구)

  • Rhee, Soon Ki;Lee, Hyun Jin
    • Journal of the Korean Chemical Society
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    • v.40 no.3
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    • pp.187-195
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    • 1996
  • Ab initio SCF calculations have been carried out for the five conceivable trimers formed between one hydrogen cyanide and two hydrogen fluorides using a basis set of TZ+P quality. Several ground state properties of these trimeric complexes have been evaluated, and compared with those of isolated monomers and appropriate dimers. Computed equilibrium geometries, stabilization energies, and dipole moments are given in order to suppliment the available experimental data. At this level of approximation, intramolecular bond distances are consistently shorter than experimental ones. However, intermolecular distances upon complex formation, and dipole moments are overestimated compared with experimental ones. HCN$(HF)_2$ trimer appears to be the most favourable among the five kinds of trimer complex, and also more stable than $(HCN)_2HF$. The typical features of the non-additivity of intermolecular interaction are relatively strong in the HCN$(HF)_2$ trimer.

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Robust Recurrent Wavelet Interval Type-2 Fuzzy-Neural-Network Control for DSP-Based PMSM Servo Drive Systems

  • El-Sousy, Fayez F.M.
    • Journal of Power Electronics
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    • v.13 no.1
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    • pp.139-160
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    • 2013
  • In this paper, an intelligent robust control system (IRCS) for precision tracking control of permanent-magnet synchronous motor (PMSM) servo drives is proposed. The IRCS comprises a recurrent wavelet-based interval type-2 fuzzy-neural-network controller (RWIT2FNNC), an RWIT2FNN estimator (RWIT2FNNE) and a compensated controller. The RWIT2FNNC combines the merits of a self-constructing interval type-2 fuzzy logic system, a recurrent neural network and a wavelet neural network. Moreover, it performs the structure and parameter-learning concurrently. The RWIT2FNNC is used as the main tracking controller to mimic the ideal control law (ICL) while the RWIT2FNNE is developed to approximate an unknown dynamic function including the lumped parameter uncertainty. Furthermore, the compensated controller is designed to achieve $L_2$ tracking performance with a desired attenuation level and to deal with uncertainties including approximation errors, optimal parameter vectors and higher order terms in the Taylor series. Moreover, the adaptive learning algorithms for the compensated controller and the RWIT2FNNE are derived by using the Lyapunov stability theorem to train the parameters of the RWIT2FNNE online. A computer simulation and an experimental system are developed to validate the effectiveness of the proposed IRCS. All of the control algorithms are implemented on a TMS320C31 DSP-based control computer. The simulation and experimental results confirm that the IRCS grants robust performance and precise response regardless of load disturbances and PMSM parameters uncertainties.

Stiffness-based Optimal Design of Shear Wall-Frame Structure System using Sensitivity Analysis (민감도 해석을 이용한 전단벽-골조 구조시스템의 강성최적설계)

  • Lee Han-Joo;Kim Ho-Soo
    • Journal of the Computational Structural Engineering Institute of Korea
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    • v.19 no.1 s.71
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    • pp.63-71
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    • 2006
  • This study presents the effective stiffness-based optimal technique to control Quantitatively lateral drift for shear wall-frame structure system using sensitivity analysis. To this end, the element stiffness matrices are constituted to solve the compatibility problem of displacement degree of freedom between the frame and shear wall. Also, lateral drift constraint to introduce the approximation concept that can preserve the generality of the mathematical programming and can effectively solve the large scaled problems is established. And, the section property relationships for shear wall and frame members are considered in order to reduce the number of design variables and differentiate easily the stiffness matrices. Specifically, constant-shape assumption which is uniformly varying in size during optimal process is applied in frame structure. The thickness or length of shear wall can be changed depending on user's intent. Two types of 20 story shear wall-frame structure system are presented to illustrate the features of the stiffness-based optimal design technique.

Capacity Spectrum Analysis using Equivalent SDOF Method and Equivalent Damping Method for RC Wall Structure (철근콘크리트 벽체구조물에 대한 등가단자유도 방법 및 등가 감쇠비 산정방법에 따른 역량스펙트럼해석)

  • Song, Jong-Keol;Jang, Dong-Hui;Kim, Hark-Soo;Chung, Yeong-Hwa
    • Journal of the Computational Structural Engineering Institute of Korea
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    • v.21 no.2
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    • pp.169-187
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    • 2008
  • Performance-based approaches as an alternative method of the existing force-based approach have gradually become recognized tools for the seismic design and evaluation. The maximum inelastic displacement response using capacity spectrum method (CSM) with elastic response spectrum is estimated from seismic response of equivalent linear system converted from nonlinear system. The purpose of this paper is to evaluate accuracy of capacity spectrum method using the equivalent SDOF methods of 4 types and the equivalent damping methods of 5 types for RC wall structure. In order to evaluate accuracy of capacity spectrum analysis, the shaking table test results for RC wall structures are compared with those by the capacity spectrum analysis. Also, the effect of bilinear capacity curves by two bilinear approximation methods for capacity spectrum analysis is compared.

Natural Frequency of 2-Dimensional Heaving Circular Cylinder: Time-Domain Analysis (상하동요하는 2차원 원주의 고유진동수: 시간 영역 해석)

  • Kim, Ki-Bum;Lee, Seung-Joon
    • Journal of the Society of Naval Architects of Korea
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    • v.50 no.4
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    • pp.224-231
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    • 2013
  • The concept of the natural frequency is useful for understanding the characters of oscillating systems. However, when a circular cylinder floating horizontally on the water surface is heaving, due to the hydrodynamic forces, the system is not governed by the equation like that of the harmonic one. In this paper, in order to shed some lights on the more correct use of the concept of the natural frequency, a problem of the heaving circular cylinder is analyzed in the time domain. The equation of motion, an integro-differential equation, was derived following the fashion of Cummins (1962), and its coefficients including the retardation function were obtained using the numerical solution of Lee (2012). The equation was solved numerically, and the experiment was also carried out in the CNU flume. Using our numerical and experimental results, the natural frequency was defined as its average value given by the motion data excluding those of the initial stage. Our results were then compared with those of the existing investigations such as Maskell and Ursell (1970), Ito (1977) and Yeung (1982) as well as the newly obtained results of Lee (2012). Comparison showed that the natural frequency obtained here agrees well with that of Lee (2012), which was found through the frequency domain analysis. It was also shown that the approximation of heaving motion by a damped harmonic oscillation, which was regarded as suitable by most previous investigators, is not physically suitable for the reason that can be clearly shown through comparing the shape of MCFRs(Modulus of Complex Frequency Response). Furthermore, we found that although the previous approximations yield the damping ratio significantly different from our result the magnitude of natural frequency is not much different from our result.

Performance analysis of maximum likelihood detection for the spatial multiplexing system with multiple antennas (다중 안테나를 갖는 공간 다중화 시스템을 위한 maximum likelihood 검출기의 성능 분석)

  • Shin Myeongcheol;Song Young Seog;Kwon Dong-Seung;Seo Jeongtae;Lee Chungyong
    • Journal of the Institute of Electronics Engineers of Korea TC
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    • v.42 no.12
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    • pp.103-110
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    • 2005
  • The performance of maximum likelihood(ML) detection for the given channel is analyzed in spatially multiplexed MIMO system. In order to obtain the vector symbol error rate, we define error vectors which represent the geometrical relation between lattice points. The properties of error vectors are analyzed to show that all lattice points in infinite lattice almost surely have four nearest neighbors after random channel transformation. Using this information and minimum distance obtained by the modified sphere decoding algorithm, we formulate the analytical performance of vector symbol error over the given channel. To verify the result, we simulate ML performance over various random channel which are classified into three categories: unitary channel, dense channel, and sparse channel. From the simulation results, it is verified that the derived analytical result gives a good approximation about the performance of ML detector over the all random MIMO channels.

Molecular Geometries and Electronic Structures of Methyl Pyropheophorbide-a and (Cationic) Tropolonyl Methyl Pyropheophorbides: DFT Calculation

  • Kim, Na-Ri;Kim, Su-Jin;Kim, Jin-Dong;Huh, Do-Sung;Shim, Young-Key;Choe, Sang-Joon
    • Bulletin of the Korean Chemical Society
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    • v.30 no.1
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    • pp.205-213
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    • 2009
  • This study reports on the geometry optimizations and electronic structure calculations for methyl pyropheophorbide (MPPa), tropolonyl methyl pyropheophorbides (TMPPa, ITMPPa), and cationic tropolonyl methyl pyropheophorbides ($TMPPa^+{{\cdot}BF_4}^-,\;ITMPPa^+{{\cdot}BF_4}^-,\;TMPPa^+,\;and\;ITMPPa^+$) using Local Spin Density Approximation (LSDA/ 6-31G*) and the Restricted Hatree-Fock (RHF/6-31G*) level theory. From the calculated results, we found that substituted cationic tropolonyl groups have larger structural effects than those of substituted neutral tropolonyl groups. The order of structural change effects is $ITMPPa^+ > ITMPPa^+{{\cdot}BF_4}^-$ > ITMPPa, as a result of the isopropyl group. Because it is an electron-releasing group, the substituted isopropyl group electronic effect on a 3-position tropolone increases the Highest Occupied Molecular Orbital and Lowest Unoccupied Molecular Orbital (HOMO-LUMO) energy gap. It was constituted that the larger the cationic characters of these photosensitizers, the smaller the HOMOLUMO band gaps are. The orbital energies of the cationic systems and the ions are stronger than those of a neutral system because of a strong electrostatic interaction. However, this stabilization of orbital energies are counteracted by the distortion of chlorin macrocycle, which results in a large destabilization of chlorin-based compound HOMOs and smaller destabilization of LUMOs as shown in TMPPa (ITMPPa), $TMPPa^+{{\cdot}BF_4}^- (ITMPPa^+{{\cdot}BF_4}^-),\;and\;TMPPa^+\;(ITMPPa^+)$ of Figure 6 and Table 6-7. These results are in reasonable agreement with normal-coordinate structural decomposition (NSD) results. The HOMO-LUMO gap is an important factor to consider in the development of photodynamic therapy (PDT).