• 한국산학기술학회논문지
• /
• 제10권5호
• /
• pp.917-922
• /
• 2009

본 연구에서는 ISO, MIRA, 그리고 Wong에 의해 제안된 노면 PSD 함수를 기초의 3차원 노면의 생성 방법에 대해 연구하였다. 주어진 노면 거칠기 특성이 PSD 함수를 사용하여 2차원 노면을 생성한 뒤 상관도를 고려하여 횡방향으로 연속적으로 배치함으로써 실제 노면 특성에 유사한 3차원 노면을 생성하였다. 생성된 노면의 상관도를 평가한 결과 실제 노면의 상관도 특성과도 잘 일치함을 확인하였다. 또한, 3차원 노면을 자동으로 생성하기 위하여 반복적으로 횡방향 노면을 생성시켜 주는 프로그램을 개발하였다.

• 한국초등과학교육학회지:초등과학교육
• /
• 제25권2호
• /
• pp.159-166
• /
• 2006

Changes in the brain activities following pre-service elementary teachers' learning hypothesis-generation were investigated using the analysis of EEG relative power and EEG coherence. In this study, the experimental group (n=16) were trained using learning methods for hypothesis-generation and the control group(n=16) were trained using learning methods for hypothesis-reception over the course of 8 weeks. EEG was measured before and following the learning process for both groups. Decreased theta ($4{\sim}7.9Hz$)/alpha 1 ($8{\sim}9.9Hz$) power and increased alpha 2 ($10{\sim}l2.9Hz$)/beta ($13{\sim}29.9Hz$)/gamma ($30{\sim}50Hz$) power were showed in the experimental group. Additionally, many changes in brian activities were observed for theta, beta and gamma coherence in the experimental group. In particular, fronto-parietal coherence increased in the experimental group. These differences in brain activities between the two groups suggest that the learning for subjects' hypothesis generation presumably leads to interesting changes in some types of brain activities in pre-service elementary teachers.

• Journal of the Optical Society of Korea
• /
• 제15권2호
• /
• pp.111-117
• /
• 2011

Full-range spectral domain optical coherence tomography (SD-OCT) with a 1-${\mu}m$ band light source is shown here. The phase of the reference beam is continuously stepped while the probing beam scans the sample laterally (B-scan). The two dimensional spectral interferogram obtained is processed by a Fourier transform method to obtain a complex spectrum leading to a full-range OCT image. A detailed mathematical explanation of the complex conjugate resolving method utilized is provided. The system's measurement speed was 7.96 kHz, the measured axial resolution was $9.6{\mu}m$ in air and the maximum sensitivity 99.4 dB. To demonstrate the effect of mirror image elimination, In vivo human eye pathology was measured.

• 치위생과학회지
• /
• 제16권5호
• /
• pp.323-330
• /
• 2016

본 연구는 치위생(학)과 학생의 통합성, 임상실습스트레스, 학과만족도와의 관계를 파악하는 데 목적이 있다. 임상실습을 1회 이상 경험한 치위생(학)과 학생을 편의 추출하여 설문조사를 실시하였으며, 총 319명의 자료를 최종 분석하여 다음과 같은 결론을 얻었다. 첫째, 일반적 특성에 따른 임상실습스트레스에서는 학제기준에서는 '4년제' 학생이, 학과선택동기에서는 '주변권유로' 치위생(학)과를 선택한 경우가, 임상실습스트레스가 많은 것으로 나타났다. 학과만족도는 학제기준에서는 '3년제'가, 학과성적에서는 '4.0 이상'대의 학생들이 높게 나타났다. 임상실습횟수에서는 '2회 이하'의 실습을 한 학생들이 가장 높은 학과만족도를 나타냈다. 둘째, 통합성은 임상실습스트레스(p<0.01)와 음의 상관관계를, 학과만족도(p<0.01)와는 양의 상관관계를 보이는 것으로 나타났다. 셋째, 경로분석 결과 통합성에 따른 임상실습스트레스, 임상실습스트레스에 따른 학과만족도는 모두 부정적 영향관계를 나타냈으며, 통합성에 따른 학과만족도는 정적 영향관계를 나타냈다. 요인간의 직, 간접효과는 모두 유의한 차이를 보였으나 간접효과는 0.06으로 낮게 나타나 통합성과 학과만족도 사이에서 임상실습스트레스는 부분매개효과를 가지나 매우 크지 않은 것으로 확인되었다. 이상의 결과를 볼 때 통합성, 임상실습스트레스, 학과만족도 간에는 영향관계가 있는 것으로 확인되었으나 간접효과가 낮게 나타난 부분에 대한 충분한 논의를 통하여 확대 후속연구를 제언하며 통합성과 관련한 반복적 연구를 통해 통합성 증진프로그램을 개발하고 학과만족도를 높일 수 있는 방안의 모색이 필요하다.

• 한국소음진동공학회:학술대회논문집
• /
• 한국소음진동공학회 2008년도 추계학술대회논문집
• /
• pp.650-651
• /
• 2008

In this thesis, source identification tool for NI-PXI equipment is developed with LabVEIW. For the purpose of examining propriety of developed tool, simulation is performed with several signals that have different frequency range. After checking the coherence functions for concerned frequency domain, an experiment is conducted on an evaporator that cause the principal noise of a refrigerator.

• Journal of Advanced Marine Engineering and Technology
• /
• 제22권1호
• /
• pp.77-84
• /
• 1998

Based on experimental analysis, the characteristics of pulsating pressure wave propagation is clarified by testing of 4-stroke gasoline engine. The pulsating pressure wave in exhaust system is generated by pulsating gas flow due to working of exhaust valve. The pulsating pressure wave is closely concerned to the loss of engine power according to back pressure and exhaust noise. It is difficult to exactly calculate pulsating pressure wave propagation in exhaust system because of nonlinear effect. Therefore, in the first step for solving these problems, this paper contains experimental model and analysis method which are applied two-port network analysis. Also, it shows coherence function, frequency response function, back pressure, and gradient of temperature in exhaust system.

• 한국소음진동공학회:학술대회논문집
• /
• 한국소음진동공학회 2004년도 추계학술대회논문집
• /
• pp.999-1004
• /
• 2004

In this study, we identify contribution of structure-borne-noise of vehicle HVAC system using Multi-Dimensional spectral analysis (MDSA) method. Firstly, to identify the applicability of MDSA method, the case of HVAC system was modeled with four input / single output system. The four inputs which is given vibration data is composed of blower, evaporator, heater and duct. The single output is noise data from driver's seat. When the blower motor is operating, we analyze the contributions of four input / single output. As a result of experiment, we identify efficiency of systems modeled with four input / single output through ordinary coherence function (OCF) and multiple coherence function (MCF).

• 생물정신의학
• /
• 제18권1호
• /
• pp.25-35
• /
• 2011

Objectives : Cerebral laterality is thought to be an important marker for neurodevelopment. Prenatal testosterone could influence both cerebral laterality and 2nd to 4th finger length ratio(2D : 4D). EEG coherence and 2D : 4D were examined to investigate the relationship between prenatal testosterone level and cerebral laterality. Methods : EEG was recorded in 24 healthy subjects in the eyes closed resting state. Differences in 2D : 4D finger ratio were used to discriminate "masculine finger type" and "feminine finger type" groups. The 2D : 4D ratio was lower and greater than one for the "masculine finger type" group and "feminine finger type" group, respectively. We used coherence analysis to estimate the cortical functional connectivity. Results : There were statistically meaningful relationships among cerebral functional connectivity, sex and finger ratio. Man and masculine finger type group showed higher intra-hemispheric coherence than those of woman and feminine finger type group. Woman and feminine finger type group showed higher inter-hemispheric coherence than those of man and masculine finger type group. Conclusions : These results imply that prenatal testosterone might act as important determinants of cerebral laterality. Further examination of the relationship between 2D : 4D and EEG coherence in schizophrenia could give some clues for the neurodevelopmental hypothesis of schizophrenia genesis.

• 한국자동차공학회논문집
• /
• 제4권4호
• /
• pp.18-26
• /
• 1996

Based on experimental analysis, the characteristics of pulsating pressure wave propagation is clarified by testing of 4-stroke gasoline engine. The pulsating pressure wave in exhaust system is generated by pulsating gas flow due to working of exhaust valve. The pulsating pressure wave is closely concerned to the loss of engine power according to back pressure and exhaust noise. It is difficult to exactly calculate pulsating pressure wave propagation in exhaust system because of nonlinear effect. Therefore, in the first step for solving these problems, this paper contains experimental model and analysis method which are applied two-port network analysis. Also, it shows coherence function, frequency response function, back pressure, and gradient of temperature in exhaust system.

• East Asian Economic Review
• /
• 제19권2호
• /
• pp.189-220
• /
• 2015

Multi-scale representations are effective in characterising the time-frequency characteristics of financial return series. They have the capability to reveal the properties not evident with typical time domain analysis. Given the aforesaid, this study derives crucial insights from multi scale analysis to investigate the co-movements between Indian and emerging Asian equity markets using wavelet correlation and wavelet coherence measures. It is reported that the Indian equity market is strongly integrated with Asian equity markets at lower frequency scales and relatively less blended at higher frequencies. On the other hand the results from cross correlations suggest that the lead-lag relationship becomes substantial as we turn to lower frequency scales and finally, wavelet coherence demonstrates that this correlation eventually grows strong in the interim of the crises period at lower frequency scales. Overall the findings are relevant and have strong policy and practical implications.