• Ocean and Polar Research
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• 제31권2호
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• pp.177-187
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• 2009

This study examined the multi-scale variabilities of sea surface temperature (SST) and salinity in the Japan/East Sea (JES) based on statistical analyses of observational data, with a focus on the northwestern part of the sea. The regionality of JES SST variability was estimated for different frequency ranges on semimonthly (11-17 days), monthly to seasonal (30-90 days), quasi-semiannual (157-220 days), and quasi-biennial (1.5-3 years) time scales using cluster analyses of daily gridded SST data for 1996 to 2007 from the Japan Meteorological Agency (JMA). Several significant peaks and regional cores were found in each frequency range of the SST anomaly (SSTA) oscillations. Quasi-semiannual SSTA oscillations with high amplitude were found in the south-southwestern part of the Japan Basin ($41-43^{\circ}N$) and were amplified in the area adjacent to Peter the Great Bay. Oscillations with periods of 79 and 55 days also prevailed over the southwest Japan Basin between the Yamato Rise and the continental slope. A similar method was applied to classify SST and the annual cycle of surface salinity using Generalized Digital Environmental Model (GDEM) gridded data. The Tatarskii Strait and adjacent area showed the most specific annual cycles and variability in salinity on interannual to interdecadal time scales. The most significant inverse relationship between surface salinity in the Tatarskii Strait and southern JES areas was found on the interdecadal time scale. Linkages of sea water salinity in the Tatarskii Strait with Amur River discharge and wind velocity over Amurskii Liman were also revealed.

• 천문학회보
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• 제38권1호
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• pp.43.1-43.1
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• 2013

We present here the preliminary results of the fast variability of AGN radio light curves. The shortest time scale of minute in AGN light curves is needed to probe the AGN activity for a few reasons; First, to check if there is any kind of shortest time scale activity. Secondly, to find out what high frequency end of AGN spectra look like. For the last, to see the time delay at several wavelength bands and the change of the spectral index with time. The observation was conducted with three KVN(Korea VLBI Network) antennas with single dish cross scan mode. In order not to lose the target at any given time, whenever one station needs to observe the calibrator, the other station is on the target. Though the detailed data reduction is still going on, there might exist varying feature in the radio light curve. The more fine calibration will be done in near future and another good data set is ready for the reduction.

• 정신신체의학
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• 제21권1호
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• pp.55-61
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• 2013

연구목적 알츠하이머병(Alzheimer's disease, 이하 AD)과 경도 인지 장애(Mild cognitive impairment, 이하 MCI)는 자율신경계를 포함한 여러 신경 기능에 영향을 미친다. 신경정신과적 장애와 심박 변이도(Heart rate variability, 이하 HRV)간의 연관성은 많이 연구되어 왔지만, AD에서 심혈관계 자율신경 기능에 관한 연구는 시행된 바가 적고, 연구 결과도 일관되지 않는다. 이에 본 연구는 HRV의 분석을 통하여 AD, MCI 그리고 정상 대조군에서 자율 신경계의 활성도 차이를 평가하고자 하였다. 방 법 5분 동안 RR 간격의 시간, 주파수 영역 변이도가 26명의 정상 대조군, 22명의 MCI군, 34명의 AD군에서 각각 평가되었다. 그룹 간 차이를 평가하기 위해 일원배치 분산분석(Analysis of variance, ANOVA)이 사용되었으며, MMSE-KC와 HRV 요소 간의 상관관계는 피어슨 상관계수(Pearson's correlation coefficient)로 평가되었다. 결 과 HRV의 시간, 주파수 영역 분석에서 그룹간의 의미 있는 차이는 관찰되지 않았다. 인지 기능 장애 정도와 HRV 간의 상관 관계도 유의하지 않은 것으로 나타났다. 결 론 정상 대조군과 비교하였을 때 MCI, AD군의 HRV 요소는 통계적으로 유의한 차이가 없는 것으로 나타났다. MCI와 AD의 비침습적인 검사 도구로써 HRV가 사용되기 위해서는 후속적인 연구가 필요할 것으로 생각된다.

• Ocean and Polar Research
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• 제40권1호
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• pp.1-13
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• 2018

Previous studies have indicated a great regional difference in Sea Level Rise (SLR) in the Pacific and it has been suggested that this is linked to climate variability over the past two decades. In this study, we seek to identify the possible linkage between regional sea level and Pacific climate variability from altimetry-based sea level data (1993-2012) and further investigate how the Pacific sea level has changed spatially and temporally over the past 60 years from long-term sea level reconstruction data (1953-2008). Based on the same method as Zhang and Church (2012), the Inter-annual Climate Index (ICI) associated with the El $Ni{\tilde{n}}o-Southern$ Oscillation (ENSO) and the Decadal Climate Index (DCI) associated with Pacific Decadal Oscillation (PDO) are defined and then the multiple variable linear regression is used to analyze quantitatively the impact of inter-annual and decadal climate variability on the regional sea levels in the Pacific. During the altimeter period, the ICI that represents ENSO influence on inter-annual time scales strongly impacts in a striking east-west "see-saw mode" on sea levels across the tropical Pacific. On the other hand, the decadal sea level pattern that is linked to the DCI has a broad meridional structure that is roughly symmetric in the equator with its North Pacific expression being similar to the PDO, which largely contributes to a positive SLR trend in the western Pacific and a negative trend in the eastern Pacific over the two most recent decades. Using long-term sea level reconstruction data, we found that the Pacific sea levels have fluctuated in the past over inter-annual and decadal time scales and that strong regional differences are presented. Of particular interest is that the SLR reveals a decadal shift and presents an opposite trend before and after the mid-1980s; i.e., a declining (rising) trend in the western (eastern) Pacific before the mid-1980s, followed by a rising (declining) trend from the mid-1980s onward in the western (eastern) Pacific. This result indicates that the recent SLR patterns revealed from the altimeters have been persistent at least since the mid-1980s.

• 한국전자통신학회논문지
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• 제15권1호
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• pp.191-198
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• 2020

본 연구는 ECG 신호를 이용하여 AR/VR 장치 사용 중에 발생할 수 있는 스트레스와 심장 상태에 따른 위험 예측을 위한 실시간 분석 시스템을 개발하였다. 제안 방법에는 ECG 신호의 R-R 간격을 이용한 HRV, BPM 측정법과 선행연구를 이용하여, 2차원 공간의 대치방법을 통해 실시간 진단방법을 제안하였다. 5분단 위로 ECG 데이터를 분석하고 자율신경계 진단 결과로 도출했다.

• Journal of Radiation Protection and Research
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• 제38권4호
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• pp.185-188
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• 2013

Heating method using electric heater was used to reduce water content in fingernail clippings. Authors found that low water content is helpful to measure EPR signal of fingernail sample with enhanced variability. Generally, natural dehydration happens in normal room condition at least one month and needs much time for using in experiment. So, artificial heating method is applied in this study for time savings. Fingernail samples were tested to find effect of water content to the EPR signal on microwave power levels for dosimetry. Low water content in fingernail reduced variability of EPR signal and makes it possible to measure accurate EPR signal. It also made it possible to measure constant movement of EPR signals on several microwave power levels. Although this method was difficult to apply directly in fingernail/EPR dosimetry, we, authors, believe that this heating method would be useful to differentiate MIS2 and RIS which are generally located at the same g-factor and almost impossible to be identified with each other.

• 천문학회보
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• 제41권1호
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• pp.71.1-71.1
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• 2016

Photometric reverberation mapping is an effective alternative to time consuming spectroscopy. It usually employs narrow bands to track the luminosity variations of broad emission lines, such as Balmer lines, and broadbands for the continuum variability. Here, we investigate the feasibility of substituting these for medium bands, with 50nm widths, that are currently being used on the SED Camera for QUasars in EArly uNiverse (SQUEAN) installed on the 2.1m Otto Struve Telescope at McDonald Observatory. Three targets with recent variability and/or short expected time lags were selected, and observed for 15 minutes each in the medium band containing $H{\alpha}$, and the two adjacent bands for continuum subtraction afterwards. Analysis shows that for one of the objects, SDSS J0350+0037, the pure $H{\alpha}$ emission line flux has a S/N ~ 12, so that variabilities up to ~ 8% are detectable. Thus, future observations using these medium bands on SQUEAN seem to be practical.

• 천문학회보
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• 제37권2호
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• pp.126.1-126.1
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• 2012

The middle-latitude ionization trough, the plasma density depletion in the subauroral region, has been extensively studied since its discovery in the 1960s. Our knowledge of the variability of the trough is mostly based on the observations in the northern hemisphere. Recently, the COSMIC observations enabled the investigation of the trough in both hemispheres at all local time. However, the investigation was limited to the period of the low solar activity. In this study, we investigate the variability of the trough location and morphology with local time, solar cycle, magnetic activity, and interplanetary magnetic field. For this purpose, we analyze the DMSP F15 data acquired during 2000-2010.

• Journal of Information Technology Applications and Management
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• 제25권2호
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• pp.73-90
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• 2018

Despite of increasing studies for product recommendation, the recommendation of product repurchase timing has not yet been studied actively. This study aims to propose deep neural network models usingsimple purchase history data to predict the repurchase timing of each customer and compare performances of the models from the perspective of prediction quality, including expected ROI of promotion, variability of precision and recall, and diversity of target selection for promotion. As an experiment result, a recurrent neural network (RNN) model showed higher promotion ROI and the smaller variability compared to MLP and other models. The proposed model can be used to develop a CRM system that can offer SMS or app-based promotionsto the customer at the right time. This model can also be used to increase sales for product repurchase businesses by balancing the level of ordersas well as inducing repurchases by customers.

• Journal of Acupuncture Research
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• 제23권3호
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• pp.155-163
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• 2006

Objectives : This study was designed to evaluated the effect of electro acupuncture on Heart Rate Variability of Patients with functional voiding disease. Methods: Subjects were voluntarily recruited by newspapers and internet. Electro acupuncture was performed three times a week for 3 weeks. Acupuncture point for EA group was B32, Electrical stimulation frequency was 2Hz, duration 20min, and intensity was up to pain threshold according to patients. The patients' Heart Rate Variability was measured before, after 3 weeks of treatment for 5 minutes. Results : In time domain analysis, There were significant increase of SDNN and RMSSD(p<0.05) after 3 weeks treatment. In frequency domain analysis, There were significant increase of LF and LF /HF ratio(p<0.05) after 3 weeks treatment. There were no significant changes in other components of heart rate variability. Conclusion : This study suggests that electroacupuncture treatments can be applicable to improve autonomic nervous system in patients with functional voiding disease.