• The Journal of the Korean dental association
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• v.22 no.11 s.186
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• pp.979-989
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• 1984

The purpose of this study was to obtain the basic data for oral health program planning of the totally blind persons. The author had surveyed oral health status and dental needs of 268 totally blind persons aged from 7 years old to 29 in Seoul, Korea, Thereafter, the toothbrushing frequency, df rate, dft index, DMF rate, DMFT index, restorative treatment requirement, bridge status, periodontal status, and periodontal requirement were calculated and discussed. The obtained results were as follows: 1. The average toothbrushing frequency was 2.53 times a day, and the average toothbrushing frquency after eating was 2.12 times a day. 2. DMF rate was 53.73%, and DMFT index was 2.12. 3. the average number of teeth required restorative treatment due to dental caries was 1.95. 4. Oral hygiene instruction was required in 15.30%, oral porphylaxis and oral hygiene instruction in 58.58%, periodontal therapy in 10.14%. %. Incremental dental care system was recommended to improve dental health status of the totally blind persons.

• Journal of Institute of Control, Robotics and Systems
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• v.18 no.1
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• pp.62-68
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• 2012

In this paper, a detection method of a pedestrian safety road marking was proposed. The proposed algorithm uses laser range and reflectivity of a range finder (LRF). For a detection of crosswalk marking and stop line, the DFT (Discrete Fourier Transform) of reflectivity and cross-correlation method between the reference replica and the measured reflectivity are used. A speed bump is detected through measuring an altitude difference of two LRFs which have the different tilted angle. Furthermore, we proposed a velocity constrained a detection method of a speed bump. Finally, the proposed methods are tested in on-line, on the pavement of a road. The considered road markings are wholly detected. The localization errors of both road markings are smaller than 0.4 meter.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2012.10a
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• pp.37-38
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• 2012

In this research, the application of PUF modeling which is configured to be doped oxide material on Si substrate and this oxide material is to prevent corrosion of the security chip device. It is to design device replication technology through applying the electromagnetic formulation and its analysis of a device and find ways to PUF design.

• Proceeding of EDISON Challenge
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• 2017.03a
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• pp.172-174
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• 2017

메탄올 용매 내에서 1,2-dichloroethane ($C_2H_4Cl_2$)의 photo-induced halogen elimination 과정을 계산화학적 방법으로 분석하였다. 특히 실험적 방법으로 분석이 까다로운 중간체 및 반응 메커니즘 분석에 집중하였다. DFT(${\omega}B97XD$ / aug-cc-pVTZ) 계산을 기반으로 진행하였으며, 추가적인 분석을 위해 중간체 샘플링 프로그램이 사용되었다. 그 결과 $C_2H_4Cl_2$ 반응계와 유사하게 bridged 형태의 중간체가 생성되는 것을 확인하였다. 또한 반응물, 생성물, 중간체 2개 및 transition states 2개로 구성된 반응 메커니즘을 밝혀내었다.

• Proceeding of EDISON Challenge
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• 2014.03a
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• pp.385-397
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• 2014

신약을 개발하거나 단백질 구조를 예측하는데 Molecular Mechanics (MM)의 방법을 사용한다. 하지만, MM 만으로는 자연현상에서 일어나는 결과를 정확하게 기술하기 어렵다. 본 연구는 기존의 MM 방법으로는 정확히 예측이 불가능한 비 공유결합 중 하나인 ${\pi}-{\pi}$ interaction을 양자역학 계산을 통해 정확한 예측이 가능한지 보았다. ${\pi}-{\pi}$ interaction 이란 생체 내, 의약 화합물에서 발견되는 결합이기 때문에, 단백질과 결합하는 구조의 예측이 중요하다고 할 수 있다. 본 실험은 ${\pi}-{\pi}$ interaction을 갖는 Sandwich, T shape, 그리고 Parallel displaced 세 가지 모형을 가지고 양자역학 계산을 수행하였다. 양자역학 계산은 DFT의 세가지 함수 M06_2X, M05_2X, B3LYP를 이용하였다. 실험결과에서 세 가지 함수가 각기 다른 결과를 보였는데, M06_2X의 결과에서 ${\pi}-{\pi}$ interaction을 더 정확하게 계산하였다. 이러한 결과를 바탕으로, 양자역학의 방법을 통해 MM에서는 예측이 불가능한 ${\pi}-{\pi}$ interaction을 계산 할 수 있고 이 부분을 고려하여 화합물 간의 결합구조를 예측을 향상시킬 수 있다.

• Proceeding of EDISON Challenge
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• 2015.03a
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• pp.412-414
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• 2015

유기 반도체의 전하 이동 특성은 그 구조적 특성에 매우 민감하다. 따라서 재료의 특성을 정확히 예측하기 위해서는 정확하게 구조를 모델링할 필요가 있다. 본 연구에서는 OLED에 널리 쓰이는 ${\alpha}$-NPD의 구조를 분자동역학을 통해 예측하기 위하여 OPLS-AA force field를 기반으로 하여 dihedral coefficient를 최적화하였다. DFT 계산을 기준으로 이를 근사하는 dihedral coefficient를 계산하였으며 ${\alpha}$-NPD의 중앙에 위치한 biphenyl dihedral의 경우, $K_2=2.74kcal/mol$, $K_4=-0.12kcal/mol$을 얻었다. 또한 이를 이용하여 melt-quench 방법을 통해 ${\alpha}$-NPD의 비정질 구조를 모델링하였다. 계산으로 얻어진 밀도는 $1.11g/cm^3$이며 실험값은 $1.12g/cm^3$이다.

• Proceedings of the Korean Fiber Society Conference
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• 2003.10b
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• pp.177-178
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• 2003

Many researchers have made efforts to control the stereoregularity in radical polymerization of vinyl monomers because the physical and chemical properties of the polymer are significantly affected by the stereostructure.[1]-[4] In general, monomer design, reaction conditions(e.g. solvent, temperature, and monomer concentration), and additives can alter the stereochemistry of the radical polymerization of acrylic monomer. (omitted)

• Proceedings of the IEEK Conference
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• 2006.06a
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• pp.367-368
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• 2006

This paper presents an analytic derivation of phase measurement error. The analysis derives the measurement error caused by the finite-bit quantization of both input signals and twiddle factors used in the recursive implementation of the phasor measurement algorithm. The derivation is based on the statistical exploration of the error dynamic equations. The effect of frequency deviation and the number of DFT points are also included in the study. The analysis results are verified with the data obtained from the computer simulation by widely varying the values of error causing factors.

• The Transactions of the Korean Institute of Electrical Engineers
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• v.43 no.4
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• pp.553-563
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• 1994

This paper presents a filtering method using neural networks to extract fundamental frequency components of the transient wave signals in power systems. Based on the ability of multilayer feedforward neural networks to approximate any continuous function, a neural networks mapping filter is proposed for the protective distance relaying systems to extract the effective components efficiently. A characteristic feature of this mapping filter is composed of the multilayer perceptron neural networks which are trained by using random signals and those are mapped to the DFT filtering computational structure by GDR(Generalized Delta Rule). The advantage of this approach is demonstrated by the random waves and the fault transient wave signals of EMTP(electromagnetic transients program) in power systems fault conditions. The proposed method is compared with the conventional method and the simulation results show the efficiency of the neural networks.

• Proceedings of the KIEE Conference
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• 2003.07a
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• pp.335-337
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• 2003

The protection against transient instability and consequent out-of-step condition is a major concern for the utility. The unstable system may cause serious damage to system elements such as generators and transmission lines. Therefore, out-of-step detection is essential to operate a system safely. This paper presents the Out-of-Step detection algorithm using voltage frequency variation. The digital filters based on Discrete Fourier Transforms (DFT) to calculate the frequency of a sinusoid voltage are used, and the generator angle is estimated using the variation of the calculated voltage frequency. The proposed out-of-step algorithm is based on the assessment of a transient stability using equal area criterion. The proposed out-of-step algorithm is verified and tested by using EMTP MODELS.