• The Journal of the Korean dental association
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• v.16 no.10 s.113
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• pp.791-794
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• 1978

The authors selected socio-geographically different sample areas. The dental caries on the deciduous teeth was observed and evaluated in each sample area. And then, dft rate, dft index, dt rate and ft rate were calculated and compared. The obtained results were as follows; 1. The dft rate of the deciduous teeth was 33.28% in the metropolitan area, 19.78% in city area, 18.21% in town area, 13.48% in field area, 15.26% in coastal area, 22.11% in mountain area, and 20.37% in hot spring area. 2. The dft index of the deciduous teeth was 4.51 in metropolitan area, 2.78 in city area, 2.59 in town area, 1.95 in field area, 2.30 in coastal area, 3.03 in mountain area, and 2.85 in hot spring area. 3. The dt rate of the deciduous teeth was 66.51% in metropolitan area, 95.38% in field area, 98.94% in hot spring area, and 100% in the other areas. 4. The ft rate of the deciduous teeth was 33.48% in metropolitan area, 4.61% in field area, 10.50% in hot spring area, and 0.00% in the other areas. 6. We could not find that the some dental cares for the dental caries on the deciduous teeth of Korean children were supplied in metropolitan area, and the track of dental cares was appreciated in the field area, but no trace was indentified in the coastal, mountain, city, and town areas.

• Proceeding of EDISON Challenge
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• 2015.03a
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• pp.117-123
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• 2015

본 연구에서는 DFT를 이용하여 Nucleophilicity와 Basicity의 연관성에 대한 계산화학적 분석을 수행하였다. Basicity는 선정된 모델 분자의 protonation 반응에서 생성물과 반응물의 enthalpy 변화량인 양성자 친화도(Proton affinity, PA) 값을 구하여 분석하였다. 계산한 결과는 실험을 통해 얻은 PA 결과와 경향성이 거의 일치함을 확인하였다. Nucleophilicity는 모델 분자들과 $CH_3Br$ (electrophile)의 $SN_2$반응에서 gibbs free energy of activation(${\Delta}G^{\ddag}$) 값으로 그 경향성을 분석하였다. 또한 용매의 종류를 다르게 하여 용매에 따른 ${\Delta}G^{\ddag}$ 값의 경향성도 확인하였다. 각 용매에 따라 구한 ${\Delta}G^{\ddag}$와 PA의 상관관계를 비교하였으나, 큰 연관성은 보이지 않았다. 이에 ${\Delta}G^{\ddag}$와 PA의 상관관계를 보여줄 수 있는 parameter를 찾기 위하여 각 모델 분자의 Electronegativity와 Polarizability를 계산하여 연관성을 비교해보았다. Polarizability를 적용했을 때 Nucleophilicity와 Basicity사이의 연관성을 나타낼 수 없었던 반면, Electronegativity를 적용하여 Basicity와 Nucleophilicity의 연관성 보일 수 있음을 이론적으로 규명하였다.

• The Transactions of the Korean Institute of Power Electronics
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• v.15 no.4
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• pp.266-273
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• 2010

The main function of the power conditioning system (PCS) is grid-connection with renewable system. The level of total harmonic distortion(THD) caused by the PCS should be maintained less than 5% according to the IEEE-1547 regulation. The THD is measured by the dedicated instrument, not by the PCS in the domestic products. There should be the necessity for harmonic measurement by the PCS in order to cope with degradation or fault condition. In this paper, the real-time harmonic measurement technique using highperformance DSP controller is presented. The proto-system is manufactured using 32-bit floating DSP processor and tested with 256-point DFT(Discrete Fourier Transform) algorithm. The test result shows that the harmonic calculation time is less than 1 [ms]. It can be used as a auxiliary method for predicting the fault in the PCS system.

• Journal of the Korean Chemical Society
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• v.55 no.3
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• pp.392-399
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• 2011

Two conformations of benzoic acid derivatives ($NH_2$, OH, H, F, Cl, CN, NO, $NO_2$) have been investigated at MP2, DFT and HF level using the 6-311++G(d,p) basis set. It was found that the cis isomers are more stable. Hydrogen bonding formation of benzoic acids has been estimated from stabilization energies. The calculated hydrogen-bonding energies of dimers showed a cooperative interaction in the cyclic ones. It was found that an electron-releasing group (ERG) into the phenyl rings resulted in the formation of more stable hydrogen bonding. Red shift of O-H bond was found from -565.3 to -589.3 for dimers. The natural bond orbital (NBO) analysis was applied to characterize nature of the interaction.

• Korean Chemical Engineering Research
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• v.55 no.2
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• pp.270-274
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• 2017

Formic acid has been known as one of key sources of hydrogen. Among various monometallic catalysts, hydrogen can be efficiently produced on Pd catalyst. However, the catalytic activity of Pd is gradually reduced by the blocking of active sites by CO, which is formed from the unwanted indirect oxidation of formic acid. One of promising solutions to overcome such issue is the design of alloy catalyst by adding other metal into Pd since alloying effect (such as ligand and strain effect) can increase the chance to mitigate CO poisoning issue. In this study, we have investigated formic acid deposition on the bimetallic $Pd/Pd_3Fe$ core-shell nanocatalyst using DFT (density functional theory) calculation. In comparison to Pd catalyst, the activation energy of formic acid dehydrogenation is greatly reduced on $Pd/Pd_3Fe$ catalyst. In order to understand the importance of alloying effects in catalysis, we decoupled the strain effect from ligand effect. We found that both strain effect and ligand effect reduced the binding energy of HCOO by 0.03 eV and 0.29 eV, respectively, compared to the pure Pd case. Our DFT analysis of electronic structure suggested that such decrease of HCOO binding energy is related to the dramatic reduction of density of state near the fermi level.

• Journal of the korean academy of Pediatric Dentistry
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• v.47 no.1
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• pp.78-86
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• 2020

This study aimed to evaluate the relationship between parenting styles and childhood dental caries using a sample of 3 to 6 years old children in Korea. The subjects were 158 children aged 3 to 6 years old and their parents in Korea. The parenting styles were divided into three groups (authoritative, authoritarian, and permissive) using a translated version of the Parenting Styles and Dimensions Questionnaire (PSDQ). Among the 353 parents/child dyads, 158 questionnaires were returned. Authoritative parenting style was the majority (95.6%), followed by authoritarian (3.8%), and permissive (0.6%). There were no statistically significant differences between dental caries and parenting styles. The mean of dft index in authoritative group was lower than others. In the authoritative domain, the higher the authoritative tendency, the lower the dft index. Overall, authoritative parenting styles resulted in low rates of dental caries for the children. The stronger the authoritative tendency of the parents, the lower the experience of dental caries in the children. Therefore, parenting styles were likely to affect the oral health of a child, but it seemed necessary to supplement the evaluation tool to evaluate the parenting styles.

• Journal of the Institute of Electronics and Information Engineers
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• v.52 no.12
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• pp.22-31
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• 2015

Recently, 3rd Generation Partnership Project (3GPP) has developed device-to-device (D2D) communication to cope with the explosively increasing mobile data traffic. The D2D communication uses sidelink based on single carrier-frequency division multiple access (SC-FMDA) due to its low peak-to-average power ratio (PAPR). In addition, demodulation reference signal (DMRS) is designed to support multiple input multiple output (MIMO). In this paper, we propose the DFT-based channel estimation scheme for sidelink in D2D communication. The proposed scheme uses the 2-Dimensional Minimum Mean Square Error (2-D MMSE) interpolation scheme for the user moving at a high speed. We perform the system level simulation based on 20MHz bandwidth of 3GPP LTE-Advanced system. Simulation results show that the proposed channel estimation scheme can improve signal-to-interference-plus-noise ratio (SINR), throughput and spectral efficiency of conventional scheme.

• Journal of the korean academy of Pediatric Dentistry
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• v.29 no.3
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• pp.318-327
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• 2002

The purpose of this study was to make a comprehensive study and to provide information about the dental caries and plaque index of cerebral person, and to aid improvement of their oral health. The author examined intraorally 1180 deciduous teeth, 5626 permanent teeth of 264 (male:153 female:111) cerebral palsy person and 1526 deciduous teeth, 4140 permanent teeth of 220 (male:125 female:95) non cerebral palsy person as the control group. The results were as follows : 1. Cerebral palsy persons Had higher dft rate than non-cerebral palsy persons. 2. Dental caries incidence between males and females in cerebral palsy persons showed no difference, and dental caries incidence of types in cerebral palsy person showed no difference, either. 3. Mental, motor, speech handicap degrees were negatively related to DMFT rate and DMFT index, and institutionalized cerebral palsy persons and cerebral palsy persons of which parent's occupation is private business were found low DMFT rate and DMFT index. 4. Cerebral palsy persons were found to have higher plaque index than non-cerebral palsy persons, and non institutionalized cerebral palsy persons and self-supported cerebral palsy persons were found high plaque index. 5. Plaque index of male and female in cerebral palsy person showed no difference, and Plaque index of types in cerebral palsy person showed no difference, either Plaque index of handicap degrees(mental, motor, speech) showed no difference.

• Journal of the korean academy of Pediatric Dentistry
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• v.26 no.1
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• pp.162-171
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• 1999

The purpose of this study was to make a comprehensive study and to provide information about the dental caries of autistic persons, and to aid improvement of their oral health. The authors examined intraorally 114(male; 87, female; 27) autistic persons and 119(male; 68, female; 51) normal persons as control group. The obtained results were as follows: 1. Autistic persons were found to have lower dft rate than normal persons. 2. There was no significant difference in dental caries incidence between male and female autistic persons. 3. Institutionalized autistic persons were found to have lower dental caries incidence of deciduous teeth than non-institutionalized autistic persons. 4. Autistic persons whose parent's occupation is laborer were found to have higer dft index than those whose parent's occupation is private business or employee.

• The Transactions of the Korean Institute of Electrical Engineers P
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• v.64 no.4
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• pp.291-296
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• 2015

Transmission line is exposed to a large area, and then faults are likely to occur than the other component of power system. When a fault occurs on a transmission line, fault locator helps fast recovery of power supply on power system. This paper deals with the design of a digital fault locator for improvement accuracy of the fault distance estimation and a fault occurrence position for transmission line. The algorithm of a fault locator uses a DC offset removal filter and DFT filter. The algorithm utilizes a fault data of GPS time synchronized. The computed fault information is transmitted to the other side substation through communication. The digital fault locator includes MPU module, ADPU module, SIU module, and a power module. The MMI firmware and software of the fault locator was implemented.