• Design & Manufacturing
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• v.16 no.3
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• pp.34-38
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• 2022

Regular expression pattern matching is widely used in applications such as computer virus vaccine, NIDS and DNA sequencing analysis. Hardware-based pattern matching is used when high-performance processing is required due to time constraints. ReCPU, SMPU, and REMP, which are processor-based regular expression matching processors, have been proposed to solve the problem of the hardware-based method that requires resynthesis whenever a pattern is updated. However, these processor-based regular expression matching processors inefficiently handle repetitive operations of regular expressions. In this paper, we propose a new instruction set to improve the inefficient repetitive operations of ReCPU and SMPU. We propose REMPi, a regular expression matching processor that enables efficient iterative operations based on the REMP instruction set. REMPi improves the inefficient method of processing a particularly short sub-pattern as a repeat operation OR, and enables processing with a single instruction. In addition, by using a down counter and a counter stack, nested iterative operations are also efficiently processed. REMPi was described with Verilog and synthesized on Intel Stratix IV FPGA.

• Rapid Communication in Photoscience
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• v.4 no.3
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• pp.63-66
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• 2015

When the molecule in the excited state is subject to prompt predissociation, it is quite nontrivial to obtain vibrational structure of the excited state in general. This applies to the case of photochemistry of dimethylamine (DMA:$(CH_3)_2NH$). When DMA is excited to its first electronically excited state ($S_1$), the N-H bond dissociation occurs promptly. Therefore, $S_1$ vibronic bands are homogeneously broadened to give extremely small ionization cross sections and heavily-congested spectral features, making infeasible any reasonable spectral assignment. Here, we demonstrate that the predissociation rate of the excited state could be significantly reduced by the NH/ND substitution to give the much better-resolved $S_1$ spectral feature, revealing the vibrational structure of the excited state of $DMA-d_1$ ($(CH_3)_2ND$) for the first time.

• Bulletin of the Korean Chemical Society
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• v.30 no.11
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• pp.2661-2664
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• 2009

Photodissociation of nitrous oxide near 203 nm has been studied by a combination of high resolution slice ion imaging technique and (2+1) resonance-enhanced multiphoton ionization (REMPI) spectroscopy of $N_2(X^1{{\Sigma}_g}^+)$ via the (a″$^1{{\Sigma}_g}^+$) state. We have measured the recoil velocity and angular distributions of $N_2$ fragments by ion images of the state-resolved photofragments. The $N_2$ fragments were highly rotationally excited and the NN-O bond dissociation energy was determined to be 3.635 eV. Also, we investigated the photofragment images from the photodissociation of $N_2O$ clusters with various stagnation pressures.

• Bulletin of the Korean Chemical Society
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• v.27 no.9
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• pp.1393-1396
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• 2006

The 1+1 two-photon Resonant Enhanced Multiphoton Ionization (REMPI) spectra of 1,4-dichlorobenzene was obtained from 240 nm through to 250 nm on a laser mass spectrometer. Special care was taken to build up a heatable sample inlet system suitable for detecting a trace semi-volatile organic compound and reducing the memory effort on the inner wall of the inlet system. The detection limits of 1,4-dichlorobenzene in ppbV/V concentration range at certain wavelengths are presented.

• Bulletin of the Korean Chemical Society
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• v.23 no.2
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• pp.189-194
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• 2002

Two-photon resonant third photon ionization of atomic bromine $(4p^5\;^2P_{3/2}\;and\;^2P_{1/2})$ has been studied using a photoelectron imaging spectroscopy in the wavelength region 250 - 278 nm. The technique has yielded simultaneously both relative branching ratios to the three levels of $Br^+(^3P_2,\;^3P_{0.1}\;and^1D_2)$ with $4p^4$ configuration and the angular distributions of outgoing photoelectrons. The product branching ratios reveal a strong propensity to populate particular levels in many cases. Several pathways have been documented for selective formation of $Br^+(^3P_2)$ and $Br^+(^3P_{0.1})$ ions. In general, the final ion level distributions are dominated by the preservation of the ion core configuration of a resonant excited state. Some deviations from this simple picture are discussed in terms of the configuration interaction of resonant states and the autoionization in the continuum. The photoelectron angular distributions are qualitatively similar for all transitions, with a positive $A_2$ anisotropy coefficient of 1.0-2.0 and negligible $A_4$ in most cases, which suggests that the angular distribution is mainly determined by the single-photon ionization process of a resonant excited state induced from the third photon absorption.

• Bulletin of the Korean Chemical Society
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• v.32 no.2
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• pp.659-663
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• 2011

The photodissociation dynamics of bromobenzene near 234 nm has been investigated using a two-dimensional photofragment ion-imaging technique coupled with a state-selective [2+1] resonance-enhanced multiphoton ionization (REMPI) scheme. The nascent Br atoms are produced by the primary C-Br bond dissociation, which leads to the formation of $C_6H_5$ ($\tilde{X}$) and Br($^2P_j$, j = 1/2, 3/2). The observed translational energy distributions have been fitted by a single Boltzmann function and two Gaussian functions. Trimodal translational energy distributions of Br($^2P_j$) have been assigned to the direct/indirect dissociation mechanisms originating from the initially excited $^3({\pi},{\pi}^*)$ state. The assignments have been confirmed by the recoil anisotropy and distribution width corresponding to the individual components.