• Proceedings of the KIPE Conference
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• 2008.06a
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• pp.91-93
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• 2008

In this paper, novel phase angle following algorithm for the single phase grid-connected inverter is proposed. Gird-connected inverter needs phase angle detection for synchronization grid voltage with the inverter output. In case of single phase grid-connected inverter, zero crossing detection and virtual 2-phase PLL using digital all pass filter or digital low pass filter are used conventionally. But these methods have a weakness for harmonics, noises and ripples. The proposed method of PLL achieve DFT(Discrete Fourier Transform) using Goertzel algorithm. It can extract fundamental voltage of grid. As a results, it can obtain phase angle using digital all pass filter without effect of harmonics, noises and ripples. Simulation results are presented to demonstrate the effectiveness of the proposed algorithm.

• Bulletin of the Korean Chemical Society
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• v.21 no.3
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• pp.300-304
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• 2000

The B3LYP method based on the density functional theory(DFT) is shown to be much better than the ab initio MP2 method for structural determination of diphosphadithiatetrazocine systems having transannular S--S bonding. The presence of bonding between the two sulfur atoms across the cyclic ring is theoretically confirmed in the case of the neutral diphosphadithiatetrazocine. The S--S dobding disappears in the ionized species. The planarity of the dicationic heterocyclic ring system turns out to be closely associated with the $\pi-electron$ delocalization over the entire ring as well as the N-S-N bonds, which become stiffened upon ionizaiton. In the case of dianionic species, the chair-boat and chair conformers are nearly degenerate and far more stable than the crown conformer.

• International Journal of Computer Science & Network Security
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• v.23 no.1
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• pp.103-111
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• 2023

Implementing conventional DFT solution for arrays of DNN accelerators having large number of processing elements (PEs), without considering architectural characteristics of PEs may incur overwhelming test overheads. Recent DFT based techniques have utilized the homogeneity and dataflow of arrays at PE-level and Core-level for obtaining reduction in; test pattern volume, test time, test power and ATPG runtime. This paper reviews these contemporary test solutions for ASIC based DNN accelerators. Mainly, the proposed test architectures, pattern application method with their objectives are reviewed. It is observed that exploitation of architectural characteristic such as homogeneity and dataflow of PEs/ arrays results in reduced test overheads.

• Journal of the Korean Chemical Society
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• v.68 no.2
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• pp.65-73
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• 2024

The halide-acetylene anions, X^--HCCH (X = F, Cl, and Br) have been studied by using several different ab initio and DFT methods to determine structures, hydrogen-bond energies, vibrational frequencies of the anion complexes. Although the halide-acetylene complexes all have linear equilibrium structures, it is found that the fluoride complex is characterized with distinctively different structure and interactions compared to those of the chloride and bromide complexes. The performance of various density functionals on describing ionic hydrogen-bonded complexes is assessed by examining statistical deviations with respect to high level ab initio CCSD(T) results as reference. The density functionals employed in the present work show considerably varying degrees of performance depending on the properties computed. The performances of each density functional on geometrical parameters related with the hydrogen bond, hydrogen-bond energies, and scaled harmonic frequencies of the anion complexes are examined and discussed based on the statistical deviations.

• Journal of Korean society of Dental Hygiene
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• v.15 no.4
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• pp.705-711
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• 2015

Objectives: The purpose of the study is to evaluate the effect of continuing dental care program by elementary school dental clinic in Gimcheon from 2008 to 2013. Methods: The subjects were experimental group of 152 students from three elementary schools having dental clinics and control group of 136 students from three elementary schools of no dental clinics. The six dentists in Gimcheon community health center carried out the regular dental checkups in the elementary schools and four dental hygienists recorded the dental examination results. After receiving WHO dental survey guideline education, the examiners used dental mirror and dental probe under the natural light. The contents of the survey included dental caries in the deciduous and permanent teeth, malocclusion, remaining ratio of sealant, treatment, and follow up. Results: DFT index by grade showed that 3.71 in experimental group and 4.56 in control group and it was remarkable in the 3rd grade. Thus. DFT index in the experimental group was lower than that of control group (p<0.05). DT index by grade was 0.63 in experimental group and 1.28 in control group marked in the 6th grade. DT index in the control group was higher than that of the experimental group (p<0,001). DFT index and DMFT Index by grade showed no significant difference between the control group and the experimental group. DFT and DMFT Index of the control group in the 3rd and 6th grade were lower score than those of experimental group. DFT and DMFT index in the third and 6th grade showed no significant difference between the control group and the experimental group. The remaining ratio of the sealant was 4.89 experimental group in the 6th grade. The remaining ratio of the sealant in the experimental group was higher than that in the control group. Conclusions: The continuing dental care program in the elementary school is very effective method in the treatment of oral disease in the elementary school children. The oral health care and prevention for the elementary school children should be implemented and carried out continuously.

• Bulletin of the Korean Chemical Society
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• v.29 no.6
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• pp.1141-1148
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• 2008

Geometry optimizations and electronic structure calculations are reported for meso-tetraphenyl porphyrin (TPP) and a series of meso-substituted catecholic porphyrins (KP99150, KP99151, KP99152, KP99153, and KP99090) using density functional theory (DFT). The calculated B3LYP//RHF bond lengths are slightly longer than those of LSDA//RHF. The calculated electronic structures clearly show that TPP and meso-catecholic group contribute to π-electron conjugation along porphyrin ring for HOMO and LUMO, significantly reduced the HOMO-LUMO gap. The wavelength due to B3LYP energy gaps is favored with experimental value in Soret (B), and LSDA energy gaps are favored with experimental value in visible bands (Q). The electronic effect of the catecholic groups is to reduced energies of both the HOMOs and LUMOs. However, the distortion of porphyrin predominantly raises the energies of the HOMOs, so the net result is a large drop in HOMO and smaller drop in LUMO energies upon meso-substituted catecholic group of the porphyrin macrocycle as shown in KP99151 and KP99152 of Figure 5(a). 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).

• Bulletin of the Korean Chemical Society
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• v.30 no.9
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• pp.2077-2082
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• 2009

The conformational and electronic properties of 2-cyano-3-(thiophen-2-yl)acrylic acid (TCA) in analogues used as sensitizers in dye-sensitized solar cells was examined using density functional theory (DFT) and natural bond orbital analysis methods. A relaxed potential energy surface scan was performed on NKX-2677 by rotating the C-C bond between the thiophene and cyanoacrylic acid which yielded activation energy barriers of about 13 kcal/mol for both E and Z configurations. The most stable conformation of all the analogues was E-180 except for NKX-2587 which has an electrostatic repulsion between the oxygen of the coumarin and the nitrogen of the cyanoacrylic acid. The increase in the electron delocalization between the thiophene and cyanoacrylic acid influences the stability for most of the analogues. But for NKX-2600, even though there was a greater deviation from the planarity of TCA, the stability was mainly due to the presence of a weak hydrogen bond between the hydrogen of the methyl group of the amine located in the donor moiety and the nitrogen of the cyanoacrylic acid. The vertical excitation energies of the analogues containing TCA were calculated by time-dependent DFT method. There were slight differences in its vertical excitation energies but the oscillator strengths vary significantly especially in the case of NKX-2600.

• Journal of Korean society of Dental Hygiene
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• v.16 no.6
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• pp.849-861
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• 2016

Objectives: The purpose of the study was to investigate the relationships among snack habits, oral health practice, and oral health status in preschool children. Methods: The subjects were 209 preschool children and their mothers in Jeonbuk from March 24 to May 30, 2014. The study instruments comprised snack habits, oral health practice, and oral health status. Data were analyzed for independent t-test, one way ANOVA and hierarchical multiple regression using SPSS Win 21.0 version. Results: Higher dft index was shown in the older age (p=0.033), lower mother's education (p<0.001), lower mother's daily toothbrushing (p<0.001), check-up after tooth-brushing (p<0.001), tooth-brushing practice before sleeping (p<0.001), tooth-brushing practice after snack (p<0.001), regular dental check-up (p<0.001), fluoride and sealant for prevention caries (p<0.001), limitation of sugar snack intake (p<0.007), periodic replacement toothbrush (p=0.022). The cause of higher dft index included soda (p<0.001), yogurt (p<0.001), snack (p=0.002), bread and cake (p=0.002) and caramel and candy (p<0.001). Fruit (p<0.001), vegetable (p<0.001) and milk (p=0.004) decreased dft index. Factors affecting oral health status were tooth-brushing practice before sleeping, tooth-brushing practice after snack, regular dental check-up, fluoride and sealant for prevention caries, and intake of soda, yogurt, caramel, candy, and fruit. The explanation power of the final model was 67.6%. Conclusions: It is necessary to develop the oral health education program for the preschool children and mothers to enhance the best oral health condition.

• Applied Science and Convergence Technology
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• v.25 no.1
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• pp.19-24
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• 2016

In this study, we evaluated the change of electronic structure during redox process in cerium-doped $ZrO_2$ grown by sol gel method. By sol-gel method, we could obtain cerium-doped $ZrO_2$ in high oxygen partial pressure and low temperature. After post annealing process in nitrogen ambient, the film is deoxidized. We used spectroscopic and theoretical methods to analysis change of electronic structure. X-ray absorption spectroscopy (XAS) for O K1-edge and Density Functional Theory (DFT) calculation using VASP code were performed to verify the electronic structure of the film. Also, high resolution x-ray photoelectron spectroscopy (HRXPS) for Ce 3d was carried out to confirm chemical bond of cerium doped $ZrO_2$. Through the investigation of the electronic structure, we verified as followings. (1) During reduction process, binding energy of oxygen is increase. Simultaneously, oxidation state of cerium was change to 4+ to 3+. (2) Cerium 4+ and cerium 3+ states were generated at different energy level. (3) Absorption states in O K edge were mainly originated by Ce 4+ $f_0$ and Ce 3+, while occupied states in valance band were mainly originated from Ce 4+ $f_2$.

• Journal of Korean Neurosurgical Society
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• v.30 no.2
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• pp.186-193
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• 2001

Objectives : Trigeminal neuralgia and hemifacial spasm are caused by vascular compression of the REZ(root entry or exit zone) of the 5th and the 7th cranial nerve. Preoperative detection of neurovascular compression is essential for accurate diagnosis, appropriate treatment, and the good operative results. Three dimensional Fourier Transformation-Constructive Interference in Steady State(3DFT-CISS) images are known to give good contrast between CSF, nerve, and vessels. We applied a 3DFT-CISS imaging technique for the preoperative evaluation of patients with these diseases and estimated the diagnostic accuracy and usefulness of this study. Methods : A series of 71 patients with trigeminal neuralgia and hemifacial spasm were treated by microvascular decompression. Among them 34 patients with trigeminal neuralgia and 24 patients with hemifacial spasm had preoperative CISS images. We compared the radiologic finding with the operative finding, and analysed the diagnostic usefulness of 3DFT-CISS imaging. Results : The sensitivity of CISS images of detecting the neurovascular compression was 90.3% in trigeminal neuralgia and 100% in hemifacial spasm. There were one false-positive and three false-negative cases in trigeminal neuralgia, and one false-positive case in hemifacial spasm. The accuracy in diagnosing the causative vessel was 73.5% in trigeminal neuralgia and 83.3% in hemifacial spasm. Conclusion : CISS image is very useful diagnostic tool for preoperative evaluation of neurovascular compression in patients with trigeminal neuralgia and hemifacial spasm. No additional neuroradiologic examination other than CISS image and MRA is needed for preoperative evaluation of patients with trigeminal neuralgia and hemifacial spasm.