• Earthquakes and Structures
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• v.13 no.2
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• pp.193-200
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• 2017

To overcome the difficulty of performing multi-point response spectrum analysis for engineering structures under spatially varying ground motions (SVGM) using the general finite element code such as ANSYS, an approach has been developed by improving the modelling of the input ground motions in the spectral analysis. Based on the stochastic vibration analyses, the cross-power spectral density (c-PSD) matrix is adopted to model the stationary SVGM. The design response spectra are converted into the corresponding PSD model with appropriate coherency functions and apparent wave velocities. Then elements of c-PSD matrix are summarized in the row and the PSD matrix is transformed into the response spectra for a general spectral analysis. A long-span high-pier bridge under multiple support excitations is analyzed using the proposed approach considering the incoherence, wave-passage and site-response effects. The proposed approach is deemed to be an efficient numerical method that can be used for seismic analysis of large engineering structures under SVGM.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.26 no.2
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• pp.180-183
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• 1990

The variability of ambient noise with time and water depth is measured in the coastal water of Pusan. The Noise Spectrum levels are relatively high, and have standard deviations amounting to 3 to 4 dB with time and 2 to 3 dB with water depth in the B area of high ship activity. On the other hand, in the A area where shipping is sparse the standard deviations are only 1 to 2 dB with time and water depth respectively. These results show that ship traffic is one of the dominent sources at frequencies greater than 500Hz.

• Ocean and Polar Research
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• v.35 no.4
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• pp.281-290
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• 2013

The vertical structure of sediment temperatures in the tidal flats of Geunso Bay and Seonyu Island in western Korea were measured for more than a year and analyzed. Mean temperature decreased with depth in spring and summer. On the contrary, it increased with depth in fall and winter, faithfully reflecting the seasonal variation resulting from the heating and cooling of the surface sediment. The surface sediment temperatures are shown to be strongly dependent on solar radiation, M2, and M4 tidal components. They are also weakly affected by precipitation. Thermal diffusivity of sediment is estimated at each depth and in each of the four seasons by applying the amplitude equation method. In Geunso Bay, the estimated seasonal-mean values decreased with depth, while they showed little change in Seonyu Island. Depth-averaged thermal diffusivity in Geunso Bay ($1.94 {\times}10^{-7}m^2/s$) was smaller than Seonyu Island ($2.20 {\times}10^{-7}m^2/s$). The variability of thermal diffusivity is shown to corelate with sediment composition and sorting from the grain-size analysis of intertidal sediments in Geunso Bay and Seonyu-do.

• Science of Emotion and Sensibility
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• v.2 no.1
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• pp.147-155
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• 1999

온열쾌적감에 영향을 주는 중요한 요인들로는 온도, 습도, 기류 등의 물리적 요인과 성별이나 체질 등 뿐만 아니라 온열환경에서 느끼는 인간의 감성적인 측면도 요인으로 작용한다. 본 연구에서는 여러 가지 온열 환경 중에서 실내의 상하온도차와 기류방식의 제어에 따른 생체반응의 변화, 및 감성의 변화를 관찰하여 온열환경에 따른 인간의 온열쾌적감을 평가하기 위해 생리신호를 측정, 분석하였다. 인간에게 가장 쾌적함을 주는 최적의 실내 상하온도차와 기류제어방식을 구현하기 위한 평가방법으로 MST(mean skin temperature)분석 및 HRV(heart rate variability) 분석과 EEG 주파수 스펙트럼 분석을 시행하였다. 그 결과 실내의 상하온도차는 23$^{\circ}C$의 머리부위 온도에서 발 부위와의 온도차가 -3$^{\circ}C$일 때 가장 쾌적한 조건으로 나타났고, 기류제어방식은 감성기류조건에서 가장 쾌적함을 보였다. 본 연구를 통해 실내의 상하온도차와 기류방식에 대한 온열환경의 쾌적조건을 설정하였고, HRV 분석과 EEG의 주파수 분석이 주판신소설문평가와 유의한 결과를 나타내어 이러한 생리신호의 분석이 인간의 감성적 측면을 고려한 온열쾌적성을 펑가하는데 보다 객관적이고 신뢰성 있는 평가지표로 이용될 수 있음을 제시하였다.

• Proceedings of the Korean Society for Emotion and Sensibility Conference
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• 1998.11a
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• pp.94-98
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• 1998

최근 온열 환경에서 인간의 쾌적감에 대한 관심이 커지고 있다. 온열쾌적감에 영향을 주는 요인들로는 온도, 습도, 기류 둥의 물리적 요인과 성별이나 체질 둥의 개인적인 요인들 뿐만 아니라 온열환경에서 느끼는 인간의 감성적인 측면도 요인으로 작용하게 된다. 본 연구에서는 여러가지 온열 환경 중에서 기류환경에 따른 인간의 온열 쾌적감을 평가하기 위해 생체반응의 변화 및 감성의 변화에 따른 생리신호를 분석을 통해 살펴보았다. 기류환경은 기존에 사용되고 있는 풍향변화기류 및 풍량변화기류와 새롭게 개발되어진 감성기류의 3가지 기류 조건을 제시하였고, 이에 따른 인체의 자율신경계의 반응과 감성 상태를 관찰하기 위해 심전도(ECG)와 뇌파(EEC)를 측정하여 HRV(Heart Rate Variability) 분석과 EEG 주파수 스펙트럼 분석을 시행하였다. 생리신호 분석결과 심전도의 HRV 분석에서는 감성기류가 풍향변화 기류와 풍속변화기류에 비해 HF/LF 비가 높게 나타났고, 뇌파의 주파수 스펙트럼 분석에서도 $\beta$파에 대한 뇌파의 상대 전력비가 감성기류에서 높게 나타나 감성기류가 제시된 다른 기류인 풍향변화기류나 풍속변화기류에 비해 쾌적한 온열환경 제시를 위한 기류조건이라고 평가되었다. 결론적으로 심전도의 HRV분석과 뇌파의 주파수 분석이 .제시된 기류환경의 온열쾌적감 평가에서 서로 유의한 결과를 나타냄으로써, 이들 생리신호의 분석이 온열환경에 따른 인간의 감성 변화를 객관적으로 나타내고 온열 쾌적감을 평가하는데 있어 유용한 정보가 될 수 있음을 제시하였다.

• Journal of Biomedical Engineering Research
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• v.22 no.5
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• pp.439-448
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• 2001

This paper considers the acoustical characteristics of the closing click sounds of the mechanical valves employed in an implantable biventricular assist device (BYAD) and their re1evance to the Physical states of the valved. Bj rk Shiley Convexo Concave tilting disk valve was chosen for the study and acoustic measurement was made for the BYAD operated in a mock circulatory system as well as implanted in an animal (sheep). In the BYAD operated in the mock circulatory system. three different states of the valve were examined, ie. normal. mechanically damaged. pseudo-thrombus attached. Microphone measurement for the BVAD implanted in the animal was carried out for five days at a regular time interval from one day after implantation. Characteristic spectrum of the sound from the valve was estimated using Multiple Signal Classification (MUSIC) in which the optimal order was determined according to Bayesian Information Criterion (BIC) . It was observed that the mechanical damage of the valve resulted in changes of the structure of the acoustic spectrum. In contrast. the thrombus formed on the valve did not change much the basic structure of the spectrum but brought about altering the spectral Peak frequencies and energies. Maximum spectral Peak (MSP) with the greatest energy was seen at 2 kHz for the normal valve and it was shifted to 3 kHz for the calve attaching the Pseudo-thrombus. Unlike the normal valve, strong spectral Peak appeared around 7 kHz in the sound from the valve mechanically damaged. In the case of the BYAD implanted in the animal. as the thrombus grew, acoustic energy was reduced relatively more in the low frequency components (〈 2 kHz) and the frequencies of the 1st, 2nd and 3rd MSP were increased little. The thrombus formation would result in reduction in both the variability of the 1st, 2nd and 3rd MSP and the value of the BIC optimal order.

• Journal of Music and Human Behavior
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• v.13 no.1
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• pp.61-87
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• 2016

With broad individual variability in social communication skills of children with autism spectrum disorders and increasing focus on interventions targeting social communication of this population, there is a need for systematic analysis of how social communication outcomes are measured. This study aimed to systematically analyze the measurement tools used in the music therapy interventions for improving social communication of children with ASD. Electronic databases and music therapy journals were searched for controlled studies published between 1980 and 2015. A total of 21 studies were included for the analysis. The results demonstrated that direct observation of behaviors was the most frequently used and the combination of targeted social communication areas and specific measurements used for a specific skill varied among the studies. In addition, 90.4% of studies reported interrater reliability. These results indicate that there has been a diversity in approaches to measure social communication skills despite increasing attempts for systematic measurements. In consideration of the nature of social communication development in children with ASD, multifaceted strategy to understand and assess the target skills in terms of specific behavior acquisition, social functioning in general, and social cognition was recommended.

• Journal of the Korean Geotechnical Society
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• v.25 no.10
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• pp.87-97
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• 2009

The seismic site coefficients are often used with the seismic hazard maps to develop the design response spectrum at the surface. The site coefficients are most commonly developed deterministically, while the seismic hazarde maps are derived probabilistically. There is, hence, an inherent incompatibility between the two approaches. However, they are used together in the seismic design codes without a clear rational basis. To resolve the fundamental imcompatibility between the site coefficients and hazard maps, this study uses a novel probabilistic seismic hazard analysis (PSHA) technique that simulates the results of a standard PSHA at a rock outcrop, but integrates the site response analysis function to capture the site amplification effects within the PSHA platform. Another important advantage of the method is its ability to model the uncertainty, variability, and randomness of the soil properties. The new PSHA was used to develop fully probabilistic site coefficients for site classes of the seismic design code and another sets of site classes proposed in Korea. Comparisons highlight the pronounced discrepancy between the site coefficients of the seismic design code and the proposed coefficients, while another set of site coefficients show differences only at selected site classes.

• Journal of Acupuncture Research
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• v.22 no.3
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• pp.105-112
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• 2005

Obiective : The purpose of this study was to assess the effect of acupuncture treatment for chronic headache patients using power spectrum analysis of the heart rate variability(HRV). Methods : 15 clinical experiment participants were gathered and through a questionnaire patients who experienced headache for more than 4 hours a day and more than IS days per month were qualified as Chronic Headache patients. Treatment was afplied 2 times a weeks for 8 weeks. The acupoints, GV2O, HN23, ST8, HN46, TEl7, GB2O, LI2O, LI11, LI14, ST36, and LR3 were stimulated for 20 minutes. The effects of acupuncture treatment were analyzed using power spectrum analysis of the HRV. HRV was recorded before and after acupuncture treatment. Results : HRV before and after treatment was compared after 8 weeks of acupuncture treatment. Increase in mean values of SDNN and RMSSD were observed but the increases were not statistically significant. Increase in mean values of TP, LF and HF were observed but, the increase was significant(p<0.05) only in TP. Conclusions : The results suggest that acupuncture treatment on chronic headache patients can increase the activity of autonomic nervous system. Further use of HRV for quantitative analysis of acupuncture treatment on autonomic nervous system related symptoms is suggested.

• Science of Emotion and Sensibility
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• v.6 no.4
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• pp.9-14
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• 2003

Sleep stages have been useful indicator to check a person's comfortableness in a sleep, But the traditional method of scoring sleep stages with polysomnography based on the integrated analysis of the electroencephalogram(EEG), electrooculogram(EOG), electrocardiogram(ECG), and electromyogram(EMG) is too restrictive to take a comfortable sleep for the participants, While the sympathetic nervous system is predominant during a wakefulness, the parasympathetic nervous system is more active during a sleep, Cardiovascular function is controlled by this autonomic nervous system, So, we have interpreted the heart rate variability(HRV) among sleep stages to find a simple method of classifying sleep stages, Six healthy male college students participated, and 12 night sleeps were recorded in this research, Sleep stages based on the "Standard scoring system for sleep stage" were automatically classified with polysomnograph by measuring EEG, EOG, ECG, and EMG(chin and leg) for the six participants during sleeping, To extract only the ECG signals from the polysomnograph and to interpret the HRV, a Sleep Data Acquisition/Analysis System was devised in this research, The power spectrum of HRV was divided into three ranges; low frequency(LF), medium frequency(MF), and high frequency(HF), It showed that, the LF/HF ratio of the Stage W(Wakefulness) was 325% higher than that of the Stage 2(p＜.05), 628% higher than that of the Stage 3(p＜.001), and 800% higher than that of the Stage 4(p＜.001), Moreover, this ratio of the Stage 4 was 427% lower than that of the Stage REM (rapid eye movement) (p＜.05) and 418% lower than that of the Stage l(p＜.05), respectively, It was observed that the LF/HF ratio decreased monotonously as the sleep stage changes from the Stage W, Stage REM, Stage 1, Stage 2, Stage 3, to Stage 4, While the difference of the MF/(LF+HF) ratio among sleep Stages was not significant, it was higher in the Stage REM and Stage 3 than that of in the other sleep stages in view of descriptive statistic analysis for the sample group.