• Journal of the Korean Chemical Society
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• v.61 no.6
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• pp.328-338
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• 2017

The density functional theory(DFT) and ab initio calculations have been applied to investigate hydrogen interaction of $H_2O_3(H_2O)_n$ clusters(n=1-5). The structures, IR spectra, and H-bonding energies are calculated at various levels of theory. The $trans-H_2O_3$ monomer is predicted to be thermodynamically more stable than cis form at the CCSD(T)/cc-pVTZ level of theory. For clusters, the geometries are optimized at the MP2/cc-pVTZ level of theory. The binding energy of $H_2O_3-H_2O$ cluster is predicted to be -6.39 kcal/mol at the CCSD(T)//MP2/cc-pVTZ level of theory after zero-point vibrational energy (ZPVE) and basis set superposition error (BSSE) correction. This result implies that $H_2O_3$ is a stronger proton donor(acid) than either $H_2O$ or $H_2O_2$. The average binding energies per $H_2O$ are predicted to be 8.25 kcal/mol for n=2, 7.22 kcal/mol for n=3, 8.50 kcal/mol for n=4, and 8.16 kcal/mol for n=5.

• Proceeding of EDISON Challenge
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• 2013.04a
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• pp.203-204
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• 2013

Phenylalanine Ammonia Lyase (PAL)는 phenylalanine의 산성도가 더 큰 ammonium hydrogen 과는 반응하지 않고 그것의 nonacidic ${\beta}$ proton을 제거하는 역할을 한다. Phenylalanine은 electrophilic 그룹을 갖고 있으며 지난 30 여년 동안 phenylalanine의 electrophilic 그룹이 PAL의 반응 기작에 중요한 역할을 한다고 믿어왔다. 그러나 최근 X-ray와 UV spectroscopy를 통하여 상당히 electrophilic 한 5-methylene-3,5-dihydroimidazol-4-one (MIO) 그룹이 발견되었다. 이전의 연구들은 실험을 통하여 MIO와 관련된 electrophile에 의한 Friedel-Crafts Attack 메커니즘과 electrophile에 대한 nucleophilic addition 메커니즘을 제시하였으며, 본 연구진은 양자계산을 통하여 두 가지 메커니즘의 에너지 차이를 살펴봄으로써 더욱 합리적인 메커니즘을 제시, 규명하고자 한다. 본 연구에서는 특히 electrophile에 대한 nucleophilic addition 메커니즘에 대하여 양자계산을 이용하여 반응물, 생성물, 전이상태의 분자 구조를 제시하고 반응이 일어나는데 필요한 에너지를 계산하고자 한다.

• Korean Journal of Materials Research
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• v.18 no.12
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• pp.673-677
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• 2008

Calcia (CaO) stabilized cubic-$HfO_2$ is studied by density functional theory (DFT) with generalized gradient approximation (GGA). When a Ca atom is substituted for a Hf atom, an oxygen vacancy is produced to satisfy the charge neutrality. The lattice parameter of a $2{\times}2{\times}2$ cubic $HfO_2$ supercell then increases by $0.02\;{\AA}$. The oxygen atoms closest to the oxygen vacancy are attracted to the vacancy as the vacancy is positive compared to the oxygen ion. When the oxygen vacancy is located at the site closest to the Ca atom, the total energy of $HfO_2$ reaches its minimum. The energy barriers for the migration of the oxygen vacancy were calculated. The energy barriers between the first and the second nearest sites, the second and the third nearest sites, and the third and fourth nearest sites are 0.2, 0.5, and 0.24 eV, respectively. The oxygen vacancies at the third and fourth nearest sites relative to the Ca atom represent the oxygen vacancies in undoped $HfO_2$. Therefore, the energy barrier for oxygen migration in the $HfO_2$ gate dielectric is 0.24 eV, which can explain the origin of gate dielectric leakage.

• Journal of the Institute of Electronics Engineers of Korea SC
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• v.44 no.6
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• pp.29-34
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• 2007

It is important to analyse the frequency spectrum for the measurement of modulated signal, distortion, and noise. The frequency spectrum analysis is performed by the execution of Radix-2 DIT DFT i.e. FFT algorithm. The discrete input signal converted by A/D converter from the input signal in time domain is mathematically transformed to the frequency spectrum by FFT algorithm. In this study, we design the digital spectrum analyser by the hardware based on the TMS320F2812 DSP and AD9244 converter, and by the software based on the C28x S/W modules. We can timely analyse the frequency spectrum in mobile communication system by the digital frequency analyser based on the high performance DSP and S/W modules. This real-time analysing capability is the important performance in the internet-based mobile communication server system.

• Journal of Bio-Environment Control
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• v.16 no.3
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• pp.222-227
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• 2007

In this study, nutrient solution for Liliaceae (Chinese chive) leafy vegetable was developed. The various strength (1/2, 1 and 3/2) of nutrient solution recommended by National Horticultural Research Institute (NSH) was applied to the crops in deep flow technique (DFT) system for 42 days. The growth of Chinese chive were highest in the treatment of 1/2 strength. The proper constitution of nutrient solution developed for liliaceae crops (NSL) was N 12, P 2.5, K 7, Ca 4 and Mg 2 met. The crops were grown two times in March and September to examine the appropriateness of the NSC. As a result, the relative growth rate and the amount of chlorophyll (SPAD value)of Chinese chive treated with NSL were increased 1.11 times. The most important nutrient factor of ascorbic acid were also increased 1.16 times.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.19 no.6
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• pp.79-85
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• 2019

Recently, small radar require the development of small millimeter wave radar with high distance resolution to disable the target's system with a single strike. Small millimeter wave radar with high distance resolution need to process large amounts of data in real time to acquire and track target. In this paper, we summarized the real-time data preprocessing method to process the large amount of data required for small millimeter wave radar. In addition, the digital IF(Intermediate Frequency) receiver, Window processing, and, DFT(Discrete Fourier Transform) functions presented by real-time data preprocessing are implemented using FPGA(Field Programmable Gate Array). Finally the implemented real-time data preprocessing module was applied to the signal processor for small millimeter wave radar and verified by performance test related to the real-time preprocessing function.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.24 no.10A
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• pp.1546-1554
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• 1999

In this paper, Dynamic Fault Tree algorithm(DFT algorithm) is presented. This algorithm provides a concise representation of dynamic fault tolerance system including fault recovery techniques with fault detection, mask and switching function. And this algorithm define FDEP, CSP, SEQ, PAG gate which captures the dynamic characteristics of system. It show that this algorithm solved the constraints to satisfy the dynamic characteristics of system which there are in Markov and also this is able to satisfy the dynamic characteristics of system which there are in Markov and also this is able to covered the disadvantage of Fault tree methods. To show the key advantage of this algorithm, a traditional method, that is, Markov and Fault Tree, applies to TMR and Dual-Duplex systems with the dynamic characteristic and a presented method applies to those. He results proved that the DFT algorithm for solving the problems of the system is more effective than the Markov and Fault tree analysis model..

• Journal of the Korean Chemical Society
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• v.62 no.5
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• pp.344-351
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• 2018

The IR spectra of gaseous phenanthrene, phenathrenols, phenanthrenyl radicals, and hydroxylphenanthrene radicals have been obtained using the BLYP/6-311++G(d,p) method. A comparison of these spectra shows that the measurements of IR spectra can be valuable to identify the reaction pathway(s) of the phenanthrene decomposition reaction by ${\cdot}OH$. We have found that the H atom abstraction reaction process can be easily identifiable from the $650-850cm^{-1}$ (CH out-of-plane bending) region and the ${\cdot}OH$ addition reaction process from the CH stretching and bending modes region of IR spectra. In addition, the calculated IR spectra of all five phenanthren-n-ols (n = 1, 2, 3, 4, 9) have also given in this work.

• Journal of the Korean Chemical Society
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• v.55 no.6
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• pp.905-911
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• 2011

The possible minimum structures of $C_{60}(CH_2)_nOH$ (n=0~2) and $C_{60}(OH)_2$have been optimized using density functional theory (DFT) with the 6-311G (d,f) basis set. The harmonic vibrational frequencies and IR intensities are also determined to confirm that all the optimized geometries are true minima. Also zero-point vibrational energies (ZPVE) have been considered to predict the binding energies. The predicted binding energy of $C_{60}CH_2OH$ is about 10 kcal/mol more stable than the binding energy of $C_{60}OH$.

• Journal of the Korean Chemical Society
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• v.53 no.3
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• pp.244-256
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• 2009

The psoralen-pyrimidine base complexes resulting from interstrand cross-linking through $C_4$-cycloaddition is studied by ab initio and DFT methods. The results indicate that in the case of the molecular complex formation between psoralens and pyrimidine base, the most probable photocycloadditions are 8-MOP< >Thy, Ps< >Cyt and Ps< >Thy. The geometries of photoadducts were optimized at the HF levels and ${\Delta}{G^{\circ}}$ were calculated. The photocycloadduct was inferred to be a C4-cycloaddition product with the stereochemistry of trans-syn 8-MOP< >Thy, trans-anti Ps(3, 4)< >Cyt, trans-anti Ps(12, 13)< >Cyt, trans-syn Ps(3, 4)< >Thy, trans-syn Ps(12, 13)< >Thy, trans-anti Ps(12, 13)< >Ps(12, 13), cis syn, cis anti Thy< >(3, 4)Ps(12, 13)< >Thy.