• Journal of the Korean Chemical Society
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• v.55 no.3
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• pp.385-391
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• 2011

The time-dependent density functional theory (TDDFT) method has been carried out to investigate the excitedstate hydrogen-bonding dynamics of phenol-$(H_2O)_2$ complex. The geometric structures and infrared (IR) spectra in ground state and different electronically excited states ($S_1$ and $T_1$) of the hydrogen-bonded complex have been calculated using the density functional theory (DFT) and TDDFT method. A ring of three hydrogen bonds is formed between phenol and two water molecules. We have demonstrated that the intermolecular hydrogen bond $O_1-H_2{\cdots}O_3-H$ of the three hydrogen bonds is strengthened in $S_1$ and $T_1$ states. In contrast, the hydrogen bond $O_5-H_6{\cdots}O_1-H$ is weakened in $S_1$ and $T_1$ states. These results are obtained by theoretically monitoring the changes of the bond lengths of the hydrogen bonds and hydrogen-bonding groups in different electronic states. The hydrogen bond $O_1-H_2{\cdots}O_3-H$ strengthening in both the $S_1$ and $T_1$ states is confirmed by the calculated stretching vibrational mode of O-H (phenol) being red-shifted upon photoexcitation. The hydrogen bond strengthening and weakening behavior in electronically excited states may exist in other ring structures of phenol-$(H_2O)_n$.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.21 no.11
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• pp.1275-1284
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• 2010

100 MHz bandwidth and 1 Gbit/s data speed are needed in LTE-advanced for the next generation mobile communication system. Therefore, spectrum aggregation method has been studied recently to extend usable frequency bands. Also bandwidth utilization is increased since vacant frequencies are used to communicate. However, transceiver structure requires the digital RF and SDR. Therefore, frequency synthesizer and PA must operate over wide-bandwidth and RF impairments also increases in transceiver. Uplink of LTE advanced uses DFT-S OFDM using plural power amplifier. The effect of ICI increases in frequency domain of receiver due to phase noise and IQ imbalance. In this paper, we analyze influences of ICI in frequency domain of receiver considering phase noise and IQ imbalance in multiband system. Also, we separate phase noise and IQ imbalance effect from channel response in frequency domain of uplink system. And we propose a method to estimate the channel exactly and to compensate IQ imbalance and phase noise. Simulation result shows that the proposed method achieves the 2 dB performance gain of BER=$10^{-4}$.

• Journal of Bio-Environment Control
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• v.32 no.3
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• pp.234-241
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• 2023

This study was conducted to investigate the growth of lettuce (Lactuca sativa L.) and Korean mint (Agastache rugosa Kuntze) with microbubble in a closed-type plant production system (CPPS) with a deep flow technique (DFT). Lettuce and Korean mint were grown in CPPS for 23 days. Microbubble was treated for 5 minutes daily at 9:00, 13:00, and 17:00 for 16 days. The leaf length, leaf width, leaf area, and fresh and dry weights of lettuce and Korean mint were significantly lower in microbubble than in the control. The total root length, root surface area, and the number of root tips of lettuce and Korean mint were significantly lower in the microbubble than in the control. In the case of average root diameter, there was no difference between the treatments of lettuce. However, Korean mint significantly increased in thickness in the microbubble treatment, indicating variations among the different crops. The results of the research indicated that microbubble treatment in the DFT inhibited plant growth by inducing abiotic stress in lettuce and Korean mint.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.68 no.4
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• pp.246-261
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• 2023

We investigated critical temperature for early marginal transplanting (CT-EMT) of the contemporary japonica rice varieties in Korea through the field, pot seedling tray, and the phytotron experiments during 2020 to 2023. The lowest mean temperature for 10 days from transplanting (MT-10DFT) that resulted in earlier heading date was 12.4℃ and the highest MT-10DFT that did not show the earlier heading date was 12.0℃ in the field study when the MT-10DFT varied by changing transplanting date. The lowest MT-10DFT that induced the increased biomass but not the earlier heading date was 11.6℃ and the highest MT-10DFT that showed neither the increased biomass nor the earlier heading date was 11.4℃. Compared to the 10-day later transplanting, the dates of the first root development, initiation of the chlorophyll recovery, and the first tiller development were earlier when the MT-10DFT was 9.1℃ or higher, 10.5℃ or higher, and 11.6℃ or higher, respectively, in the pot seedling tray and field experiments. The earliness of the first tiller development was a practical index for the estimation of CT-EMT during the early growth stage of rice. The response of transplanted rice to temperature treatments with the diurnal change of 10℃ in the phytotron study was similar to that shown in the field study. The data shown for constant temperature without a diurnal change revealed that the extent of positive effects of high temperature at day-time was greater than the extent of negative effects of low temperature at night-time on the early growth of transplanted rice. It was concluded that the critical MT-10DFT for early marginal transplanting of japonica rice in the temperate environments was between 11.4 to 11.6℃ based on the plant growth and between 12.0 to 12.4℃ based on the plant development.

• Proceeding of EDISON Challenge
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• 2015.03a
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• pp.320-323
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• 2015

본 연구에서는 18 atoms unit cell graphene film을 기반으로 한 graphene/h-BN heterostructure의 bandgap 변화에 대해 EDISON LCAODFTLab simulator의 DFT기반 전자구조계산을 통해 알아보았다. Graphene 상에 BN-doping 형태로 주어진 여러 heterostructure의 전자구조계산을 통해 태양전지의 이론적 최적효율을 나타내는 1.2eV 정도의 값을 갖는 구조를 찾을 수 있었다.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.25 no.4
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• pp.467-475
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• 2014

In this paper, we introduce a sparse recovery algorithm applied to a radar signal model, based on the compressive sensing(CS), for the formulation of the radar signatures, such as high-resolution range profile(HRRP) and ISAR(Inverse Synthetic Aperture Radar) image. When there exits missing data in observed RCS data samples, we cannot obtain correct high-resolution radar signatures with the traditional IDFT(Inverse Discrete Fourier Transform) method. However, high-resolution radar signatures using the sparse recovery algorithm can be successfully recovered in the presence of data missing and qualities of the recovered radar signatures are nearly comparable to those of radar signatures using a complete RCS data without missing data. Therefore, the results show that the sparse recovery algorithm rather than the DFT method can be suitably applied for the reconstruction of high-resolution radar signatures, although we collect incomplete RCS data due to unwanted interferences or jamming signals.

• Journal of the Korean Chemical Society
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• v.59 no.1
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• pp.9-17
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• 2015

The density functional theory (DFT) calculations on $(H_2O)_n@C_{60}$, (n=1-10) complexes have been performed to elucidate hydrogen interaction between fullerene and water clusters. The optimized geometries, harmonic vibrational frequencies, and binding energies are predicted at various levels of theory. The harmonic vibrational frequencies for the molecules considered in this study show all real numbers implying true minima. We also compare the H-bond interaction between $(H_2O)_n$ and $(H_2O)_n@C_{60}$, (n=1-10) clusters.

• Journal of the Korean Chemical Society
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• v.54 no.6
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• pp.671-679
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• 2010

The geometrical parameters and binding energies of the benzene ion-water complex [$C_6H_6^+-(H_2O)_n$(n=1-5)] have been investigated using ab initio (MP2) and density functional theory (DFT) with large basis sets. 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 have been considered to predict the binding energies. The predicted binding energy of 8.6 kcal/mol for $C_6H_6^+-(H_2O)$ at the MP2/aug-cc-pVTZ level of theory is in excellent agreement with recent experimental result of $8.5{\pm}1$ kcal/mol.

• Journal of Veterinary Clinics
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• v.33 no.1
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• pp.1-5
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• 2016

Septic tenosynovitis of the digital flexor tendon sheath (DFTS) is a potentially career-ending and life-threatening problem in horses. This study aimed to describe the outcomes of tenoscopy for the treatment of acute septic digital flexor tenosynovitis in horses. Tenoscopy was performed on 13 Thoroughbred horses with acute septic tenosynovitis of the DFTS. Surgical time was 56-148 min (mean 85.6 min, median 84.0 min). In the synovial fluid analysis, mean white blood cell count, mean neutrophil proportion, and mean total protein were $42.9{\times}10^3cells/{\mu}l$ (range, $7.2-109.5cells/{\mu}l$), 89.5% (range, 68-97%), and 4.0 g/dl (range, 2.5-5.2 g/dl), respectively. Microbial growth in the synovial fluid culture was detected in 2 of 11 horses. All horses survived and returned to their intended use without complications. The present study demonstrated that the tenoscopy is useful for treating acute septic tenosynovitis of the DFTS in horses.

• Journal of the korean academy of Pediatric Dentistry
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• v.25 no.3
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• pp.576-582
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• 1998

The purpose of the study was to determine the ability of the caries activity test, 'Cariostat' to identify preschool children with dental caries. The subjects of this study were 76 children of 3 to 5 years of age. Oral examination was carried out to assess the caries experience using a mirror and explorer. In all subjects buccal plaque samples were obtained, incubated, and scored as the manufacturer's instructions for the Cariostat test. Statistical analyses were used with the Crosstabulation. The test group exhibited mean dft index 5.21, while 27.63% of subjects were caries free and had no restorations. The sensitivity of the Cariostat test was found to be 98.8% while the specificity was found to be 19.05% The results showed that caries activity measured by visual reading was highly significant to the Cariostat score and dft index(P<0.001). The Cariostat method has indicated the future possible occurrence of caries. The use of this method is meant to require in the caries prevention program.