• 한국통신학회논문지
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• 제34권3C호
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• pp.251-256
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• 2009

본 논문에서는 음성신호의 정현파 합성방법 중 하나인 선형위상을 사용한 중첩합산방법에 대하여 감쇄(Damping) 하모닉 크기 파라미터를 사용하여 합성음성의 연속성을 개선시킨 새로운 방법을 제안한다. 기존의 중첩합산 정현파 합성방법은 프레임의 중간 지점에 대한 정현파 파라미터를 얻기 위해서 가중치로 사용된 정현파 크기값을 과거 프레임과 현재 프레임의 평균값을 사용하였으나 제안하는 방법은 정현파 크기값을 단순히 과거와 현재 프레임에서 평균값이 아닌 원 신호와 합성신호 사이의 상관성을 이용하여 감쇄(Damping)요소를 정의하고 보다 정확한 정현파 크기의 파라미터 값을 추출한 후 합성한다. 이렇게 제안한 합성 방법의 성능을 관찰하기 위해 합성방법의 연속성 평가를 통해 기존의 방법과 비교 평가한다. 제안한 방법의 평균 MSE값이 N/2 중첩길이에서 0.251dB, N/4 중첩길이에서 0.298dB 낮아짐을 볼 수 있다.

• 전기학회논문지
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• 제62권11호
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• pp.1633-1639
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• 2013

In a section of AC electric railway, a phase between the sections is different although voltage levels supplied from substations are the same. Therefore, section insulators have been installed to electrically divide between the sections. Two differenet types of section insulator, namely an overlap type and insulator type, are used. In Korean high-speed lines, overlap type section insulator has been adopted. And, insulator type is used in conventional line. The overlap type has the advantage of having no speed limit, but has the disadvantage of requiring long section length. However, the insulator type has the advantage of section length, but also has the disadvantage of having speed limit. In Korean conventional line, an insulator type one relies on the import and there is some problem with wear. In this study, we developed the insulator type section insulator which adopts Teflon tube insulation material. The Teflon material has advantage of the excellent electrical characteristics and wear-resistance characteristics for a longer expected life than that made of existing FRP. In order to compare wear characteristics between the materials, wear tests with reciprocal wear tester are performed. And dynamic behavior tests between the insulators and pantograph are also performed for showing its better dynamic characteristics.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제11권11호
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• pp.5574-5591
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• 2017

Inspired by the idea of Artificial Immune System, many researches of wireless sensor network (WSN) intrusion detection is based on the artificial intelligent system (AIS). However, a large number of generated detectors, black hole, overlap problem of NSA have impeded further used in WSN. In order to improve the anomaly detection performance for WSN, detector generation mechanism need to be improved. Therefore, in this paper, a Differential Evolution Constraint Multi-objective Optimization Problem based Negative Selection Algorithm (DE-CMOP based NSA) is proposed to optimize the distribution and effectiveness of the detector. By combining the constraint handling and multi-objective optimization technique, the algorithm is able to generate the detector set with maximized coverage of non-self space and minimized overlap among detectors. By employing differential evolution, the algorithm can reduce the black hole effectively. The experiment results show that our proposed scheme provides improved NSA algorithm in-terms, the detectors generated by the DE-CMOP based NSA more uniform with less overlap and minimum black hole, thus effectively improves the intrusion detection performance. At the same time, the new algorithm reduces the number of detectors which reduces the complexity of detection phase. Thus, this makes it suitable for intrusion detection in WSN.

• 한국의학물리학회지:의학물리
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• 제27권4호
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• pp.203-212
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• 2016

Dose differences between three-dimensional (3D) and four-dimensional (4D) doses could be varied according to the geometrical relationship between a planning target volume (PTV) and an organ at risk (OAR). The purpose of this study is to evaluate the correlation between the overlap volume histogram (OVH), which quantitatively shows the geometrical relationship between the PTV and OAR, and the dose differences. 4D computed tomography (4DCT) images were acquired for 10 liver cancer patients. Internal target volume-based treatment planning was performed. A 3D dose was calculated on a reference phase (end-exhalation). A 4D dose was accumulated using deformation vector fields between the reference and other phase images of 4DCT from deformable image registration, and dose differences between the 3D and 4D doses were calculated. An OVH between the PTV and selected OAR (duodenum) was calculated and quantified on the basis of specific overlap volumes that corresponded to 10%, 20%, 30%, 40%, and 50% of the OAR volume overlapped with the expanded PTV. Statistical analysis was performed to verify the correlation with the OVH and dose difference for the OAR. The minimum mean dose difference was 0.50 Gy from case 3, and the maximum mean dose difference was 4.96 Gy from case 2. The calculated range of the correlation coefficients between the OVH and dose difference was from -0.720 to -0.712, and the R-square range for regression analysis was from 0.506 to 0.518 (p-value <0.05). However, when the 10% overlap volume was applied in the six cases that had OVH value ${\leq}2$, the average percent mean dose differences were $34.80{\pm}12.42%$. Cases with quantified OVH values of 2 or more had mean dose differences of $29.16{\pm}11.36%$. In conclusion, no significant statistical correlation was found between the OVH and dose differences. However, it was confirmed that a higher difference between the 3D and 4D doses could occur in cases that have smaller OVH value.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1998년도 하계학술대회 논문집 A
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• pp.131-133
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• 1998

본 연구에서는 대표적인 몇가지 경우의 전류크기와 회전자 위치각에 따른 토오크값을 직접 측정하고, 이들 값으로부터 연속적인 토오크 값을 얻은 후, 이를 이용하여 각 상간 토오크의 중첩을 고려한 평활한 토오크를 발생할 수 있는 전류의 형상을 도출하였다. 이러한 순시적인 전류의 크기를 제어기 위한 순시접압은 PWM으로 제어하였다.

• Bulletin of the Korean Chemical Society
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• 제34권2호
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• pp.609-614
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• 2013

Extended H$\ddot{u}$ckel tight-binding band structure calculations are used to address the chemical bonding and elastic properties of $Zr_2AC$ (A=Al, Si, P, and S). Elastic properties are interpreted by analyzing the density of states and the crystal orbital overlap population for the respective phases. Our results show that the bulk modulus of these ternary compounds is determined by the strength of Zr-A bonds.

• Bulletin of the Korean Chemical Society
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• 제8권1호
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• pp.10-15
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• 1987

The results of an ab initio (6-31G) molecular orbital calculation of the dipole moment derivatives and gas phase IR intensities of difluoromethane are reported. The results are compared with corresponding values obtained from a CNDO calculation. The directions of the dipole derivatives calculated by the two methods agree very well, whereas the intensities differ significantly. The results are also analyzed for the charge-charge flux-overlap electronic contributions to the dipole derivatives.

• Bulletin of the Korean Chemical Society
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• 제8권3호
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• pp.174-179
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• 1987

The results of an ab initio (6-31G) molecular orbital calculations of the dipole moment derivatives and gas phase IR intensities in $CH_3F$ and $CF_4$ are reported. The results are compared with corresponding values obtained from a CNDO calculation. We have also analyzed the theoretical polar tensors into the charge, charge flux, and overlap contributions. The effective term charges of hydrogen atom appeared to be transferable among the fluoromethane molecules.

• 한국정보전자통신기술학회논문지
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• 제16권2호
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• pp.69-76
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• 2023

MDCT/IMDCT 과정을 사용하는 고품질 오디오/음성 코덱은 이전 프레임 과의 중첩-합(Overlap-add) 과정을 통해 현재 프레임을 완벽 복원 가능하다. 중첩-합 과정에서 프레임 길이 만큼의 알고리즘 지연이 발생하게 된다. 본 논문에서는 알고리즘 지연을 줄이기 위해 MDCT/IMDCT에 가변적인 위상변이를 사용하여 알고리즘 지연을 줄인 MDCT/IMDCT 과정을 제안한다. 가변 지연 MDCT/IMDCT알고리즘을 ITU-T 표준 코덱 G.729.1 코덱에 적용하여 저지연 오디오/음성 코덱을 제안하였다. MDCT/IMDCT 과정에서의 알고리즘 지연은 기존 20 ms에서 1.25ms 까지 감소시킬 수 있다. 저지연 MDCT/IMDCT를 적용한 오디오/음성 코덱의 복호화된 출력신호는 객관적 음질 시험 방법인 PESQ 시험을 통해 성능 평가하였다. 전송 지연이 감소 됨에도 불구하고 기존 방법과 음질 차이가 없음을 확인할 수 있었다.

• 한국철도학회논문집
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• 제18권1호
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• pp.25-32
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• 2015

일반도로와 노면전차가 교차하는 신호교차로에서 준비되어야 하는 교통신호제어 운영조건을 검토하고 이를 토대로 노면전차 교통신호와 일반차량 교통신호의 효율적 통합 운영을 지원하기 위해 현재의 교통신호제어기가 추가 확보하여야 하는 기능적 및 기술적 요구사항을 진단한다. 본 연구의 검토 내용은 도로 현장에서 발생 가능한 일반차량과 노면전차의 다양한 교차상황, 노면전차 전용신호등의 등기단자 최소 구성, 교통신호현시 순서 운영상황 조합 및 이를 기반으로 한 현시표출방안을 포함한다. 분석결과 우회전 중첩현시 표출을 위한 중첩현시 등기장치 및 노면전차와 일반차량 복합 현시운영을 위한 사중고리현시표출체계 기능을 포함하는 교통신호제어기 도입이 필요함을 제안한다.