• Proceedings of the KIEE Conference
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• 2009.04b
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• pp.21-22
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• 2009

본 논문에서는 Phase Set Shift (PSS)를 이용한 영구자석형 선형 전동기에서의 코깅력의 저감에 대해 기술한다. Phase Set Shift는 코깅력의 주기성을 이용하여 코깅력을 저감하는 방법으로 각 phase set이 갖는 코깅력을 위상차이를 주어 서로의 코깅력을 상쇄하여 총 코깅력을 저감하는 방법이다. 선형 전동기의 코깅력의 해석을 위해서 유한요소법을 이용하였으며 코깅력의 주기성에 대한 연구를 위해 푸리에 급수를 이용하였다.

• Proceedings of the KIPE Conference
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• 2016.11a
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• pp.109-110
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• 2016

영구자석 동기 전동기(PMSM)의 결선방법에 따라 전동기의 전압과 전류는 그 크기와 위상에 차이가 발생한다. 따라서, 결선을 고려한 영구자석 동기 전동기의 제어가 필요하다. 본 논문에서는 와이 결선과 델타 결선된 전동기의 등가회로를 모델링하고, 델타 결선된 영구자석 동기 전동기의 구동 시스템에서 직류단 션트저항을 이용한 3상 전류 추정 알고리즘을 제안하였다. 컴퓨터 시뮬레이션을 통해 제안한 알고리즘의 타당성을 검증하였다.

• The Bulletin of The Korean Astronomical Society
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• v.44 no.1
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• pp.45.4-45.4
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• 2019

각국의 인구와 국민총생산 등에 대한 천문학 및 천체물리학 관련 박사 연구자수의 상관관계를 구하였다. 그 결과, 국가별 상황에 따라 몇 개의 그룹으로 나뉨을 발견하였고, 신흥 선진국과 전통적 선진국 사이의 상관관계가 차이가 있음을 발견하였다. 이를 바탕으로 각국의 과학이나 경제 정책 등과의 관련성을 논의할 것이며, 특히 한국 천문학의 현주소에 대해 정량적으로 논의하고자 한다. 이를 통해 한국은 후발국과 선진국 사이의 중간자적인 입장임을 밝혔고, 한국 천문학을 선진국 수준으로 발전시키기 위한 투자 규모를 정량적 수치로 제공한다.

• The Journal of Korean Society for Radiation Therapy
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• v.30 no.1_2
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• pp.83-95
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• 2018

Purpose : After planning the Respiratory Gated Radiotherapy for Lung cancer, the movement and volume change of sparing normal structures nearby target are not often considered during dose evaluation. This study carried out 4-D dose evaluation which reflects the movement of normal structures at certain phase of Respiratory Gated Radiotherapy, by using Deformable Image Registration that is well used for Adaptive Radiotherapy. Moreover, the study discussed the need of analysis and established some recommendations, regarding the normal structures's movement and volume change due to Patient's breathing pattern during evaluation of treatment plans. Materials and methods : The subjects were taken from 10 lung cancer patients who received Respiratory Gated Radiotherapy. Using Eclipse(Ver 13.6 Varian, USA), the structures seen in the top phase of CT image was equally set via Propagation or Segmentation Wizard menu, and the structure's movement and volume were analyzed by Center-to Center method. Also, image from each phase and the dose distribution were deformed into top phase CT image, for 4-dimensional dose evaluation, via VELOCITY Program. Also, Using $QUASAR^{TM}$ Phantom(Modus Medical Devices) and $GAFCHROMIC^{TM}$ EBT3 Film(Ashland, USA), verification carried out 4-D dose distribution for 4-D gamma pass rate. Result : The movement of the Inspiration and expiration phase was the most significant in axial direction of right lung, as $0.989{\pm}0.34cm$, and was the least significant in lateral direction of spinal cord, as -0.001 cm. The volume of right lung showed the greatest rate of change as 33.5 %. The maximal and minimal difference in PTV Conformity Index and Homogeneity Index between 3-dimensional dose evaluation and 4-dimensional dose evaluation, was 0.076, 0.021 and 0.011, 0.0 respectfully. The difference of 0.0045~2.76 % was determined in normal structures, using 4-D dose evaluation. 4-D gamma pass rate of every patients passed reference of 95 % gamma pass rate. Conclusion : PTV Conformity Index was more significant in all patients using 4-D dose evaluation, but no significant difference was observed between two dose evaluations for Homogeneity Index. 4-D dose distribution was shown more homogeneous dose compared to 3D dose distribution, by considering the movement from breathing which helps to fill out the PTV margin area. There was difference of 0.004~2.76 % in 4D evaluation of normal structure, and there was significant difference between two evaluation methods in all normal structures, except spinal cord. This study shows that normal structures could be underestimated by 3-D dose evaluation. Therefore, 4-D dose evaluation with Deformable Image Registration will be considered when the dose change is expected in normal structures due to patient's breathing pattern. 4-D dose evaluation with Deformable Image Registration is considered to be a more realistic dose evaluation method by reflecting the movement of normal structures from patient's breathing pattern.

• Proceedings of the Korean Society for Emotion and Sensibility Conference
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• 2003.05a
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• pp.115-119
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• 2003

본 연구는 인간에 있어서 가장 간단한 의사라고 여겨지는 긍정과 부정 응답에 대해 나타나는 뇌파의 변화를 잘 반영하는 특징을 찾아내고자 하기 위한 것이다. 고차 통계적 방법(high order statical analysis)인 바이스펙트럼(bispectrum)은 뇌파의 다른 부위와 다른 주파수 사이의 비선형위상커플링(non-linear phase coupling)을 잘 반영하므로, 이를 이용하여 긍정이나 부정을 선택할 때 나타나는 뇌파를 분석하였다. 분석결과, 반응 전 1.25초∼0.5초 에 유의미한 차이를 보였다. 긍정과 부정 응답에 대한 뇌파의 주파수와 부위를 찾아 신경회로망의 입력으로 사용하여 긍정과 부정 응답에 대해 분별하였다. 2번의 뇌파실험에서 각각 실험 데이터에 대해서는 긍/부정 차이가 존재하지만 공통적인 특징이 나타나지는 않았다.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.14 no.9
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• pp.919-923
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• 2003

In this paper, a double-sided planar balun using Microstrip-to-CPW coupled structure is fabricated and measured. The measured amplitude and phase imbalance are, respectively, less than 0.2 dB and 2.1$^{\circ}$ in a wide frequency range from 2.44 GHz to 4.33 GHz. It is expected that the proposed balun can improved the performance of balanced mixer, amplifier and feeding network of antennas. Also, it can be used in many microwave multilayer structures due to its structural characteristics.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.25 no.12B
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• pp.1979-1987
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• 2000

다중 경로 감쇄 채널 환경에서 순방향 DS-CDMA 송수신기의 성능은 사용자에 할당된 확산 수열의 특성에 따라 영향을 받는다. DS-CDMA의 수신기 비트 오류 확률 (BER) 성능은 수신단에서의 신호 대 간섭전력비 (SIR)의 함수로서, 사용자 확산 수열로 왈시 부호와 같은 직교 수열을 사용한 직교 확산 방식과 임의의 랜덤 수열로 사용한 랜덤 확산 방식에서의 수신 신호 간섭 전력은 상이한 특성을 가진다. 이 논문에서는 채널 부호를 사용하지 않은 경우와 길쌈 부호를 사용한 경우에 대해 두 시스템에서의 수신 심벌 SIR을 유도한 뒤 몬테 카를로 분석을 통해 이론적인 BER 성능을 구하고, 전산 모의 실험을 통해 이러한 분석의 타당성을 확인한다. 위상 지연이 동일한 다른 사용자 신호들로 인한 간섭 전력의 상승으로 인해 랜덤 확산 방식은 직교 확산 방식에 비해 성능이 크게 떨어진다. 경로수가 증가함에 따라 이러한 성능 차이는 감소하나 경로수가 많은 경우에도 2배 이상의 사용자 용량 차이가 발생한다.

• Composites Research
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• v.25 no.6
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• pp.236-240
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• 2012

The purpose of this study was to investigate the feasibility on the detection of dental composite delamination using a lock-in thermography method. Amplitude and phase images of detected thermal signals were analyzed according to the lock-in frequencies. At a lock-in frequency of 0.05 Hz, the ligament thickness of 0.5 mm in the specimen exhibited the highest amplitude contrast between defective area and sound area. For ligament thicknesses of 1 mm and 1.5 mm, delamination detection was possible at 0.025 Hz and 0.01 Hz through the amplitude differences. At lock-in frequencies of 0.006 Hz and 0.01 Hz, ligament thickness 0.5 mm exhibited the highest phase contrast. For ligament thicknesses of 1 mm and 1.5 mm, the phase contrast exhibited possible detection of delamination at 0.006-0.1 Hz.

• Journal of the Institute of Electronics Engineers of Korea SC
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• v.38 no.4
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• pp.45-53
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• 2001

We have proposed a new driving method of AC PDP for both high resolution over HDTV and high luminance. The new driving method can reduce data and scan pulse width to 0.85${\mu}s$ by utilizing both rising and falling edges of sustain pulse and can provide high resolution AC PDP with high luminance by increasing the number of addressing discharge using sustain pulses with phase shifts. As a result, the proposed driving scheme makes it possible to drive 2080 horizontal resolution panel with high luminance. The experimental results using 4-inch color AC PDP with $30{\times}58$ pixels indicate that the luminance can achieved up to 850 $cd/m^2$ without image noise when we employ the four phase shifted sustain pulses with the amplitude of 140V and the frequency of 125KHz.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.18 no.4
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• pp.374-380
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• 1985

The annual variations of sea surface temperature (SST), air temperature (AT), and sea-air temperature separation (SST-AT) in the East Sea (Japan Sea) are studied by harmonic analysis of the monthly data in 2 by 2 degree rectangles. In the Tsushima Current region of the Japan Sea, the annual means of SST and AT are high due to warm water advection by the current, and the annual amplitudes of SST and AT are small because the annual variations of heat advection the the current and of the incoming solar radiation are almost out of phase each other. In summer the SST and the AT in the Japan Sea are almost the same, but in winter the SST is $6{\sim}10^{\circ}C$ higher than the AT. The physical processes responsible for the observed SST-AT in the Japan Sea and their consequences in the sea-air thermal interactions are discussed in this paper.