• 한국산학기술학회논문지
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• 제20권3호
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• pp.500-506
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• 2019

본 연구에서는 arPLS(asymmetrically reweighted penalized least squares) 방법에서 분광신호의 길이와 차수를 이용한 최적의 평활화 매개변수를 위한 결정함수를 제안한다. 분광신호의 기준선 보정은 분석 시스템의 성능을 좌우하는 매우 중요한 과정으로 많은 경우에 육안 검사로 매개변수를 선택하여 추정한다. 이 과정은 매우 주관적이고 특히 대량의 데이터인 경우 지루한 작업을 동반하므로 좋은 분석 결과를 보장하기 어렵다. 이러한 이유로 기준선 보정에서 최적의 매개변수를 결정하기 위한 객관적인 방법이 필요하다. 제안한 결정함수는 기준선 보정에 사용 가능한 매개변수 범위의 중앙값이 신호의 길이가 길어질수록 증가하고, 신호의 차수가 작아질수록 감소하는 관계를 정리하여 모델링하였다. 모의실험 데이터는 신호의 길이 7가지에 대해 조합한 분석신호 4가지와 선형 기준선과 2차, 3차, 4차 곡선 기준선을 각각 더하여 모두 112개를 생성하였다. 모의실험 데이터와 실제 라만 분광신호를 이용한 실험에서 제안한 결정함수의 평활화 매개변수가 기준선 보정에 효과적으로 적용될 수 있음을 확인하였다.

• 수면정신생리
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• 제4권2호
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• pp.164-171
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• 1997

Introduction : Periodic limb movement disorder (PLMD) is shown to common in patients with OSA and may become evident or worsened when treated with nasal continuous positive airway pressure (CPAP). Whether this is due to im proved sleep continuity. adverse nocturnal body positioning, uncovered by CPAP, or due to the CPAP stimulus is still debat-ed. We hypothesized that the increase in PLM activity following CPAP is associated with more supine-sleeping tendencies when being treated with CPAP. In the present work, we compared differences in the PLMD index (PLMI) and sleeping position of patients with sleep disordered breathing before and after CPAP treatment. Method : We studied 16 patients (mean age 46 yr, 9M, 7F) with OSA (11 patients) or UARS (5 patients) who either had PLMD on initial polysomnogram (baseline PSG) or on nasal CPAP trial (CPAP PSG). All periodic leg movements were scored on anterior tibialis EMG during sleep according to standard criteria (net duration; 0.5-5.0 seconds, intervals; 4-90 seconds. 4 consecutive movements). Paired t-tests compared PLMD index (PLMI), PLMD-related arousal index (PLMD-ArI), respiratory disturbance index (RDI), and supine sleeping position spent with baseline PSG and CPAP PSG. Results : Ten patients (63%) on baseline PSG and fifteen patients (94%) on CPAP PSG had documented PLMD ($PLMI{\ge}5$) respectively with significant increase on CPAP PSG(p<0.05). Ten patients showed the emergence (6/10 patients) or substantial worsening (4/10 patients) of PLMD during CPAP trial. Mean CPAP pressure was $7.6{\pm}1.8\;cmH_2O$. PLMI tended to increase from baseline PSG to CPAP PSG, and significantly increase when excluding 2 outlier (baseline PSG, $19.0{\pm}25.8/hr$ vs CPAP PSG, $29.9{\pm}12.5/hr$, p<0.1). PLMD-ArI showed no significant change, but a significant decrease was detected when excluding 2 outlier (p<0.1). There was no significant sleeping positional difference (supine vs non-supine) on baseline PSG, but significantly more supine position (supine vs non-supine, p<0.05) on CPAP PSG. There was no significant difference in PLMI during supine-sleeping and nonsupine-sleeping position on both of baseline PSG and CPAP PSG. There was also no significant difference in PLMI during supine-sleeping position between baseline PSG and CPAP PSG. With nasal CPAP, there was a highly significant reduction in the RDI (baseline PSG, $14.1{\pm}21.3/hr$ vs CPAP PSG, $2.7{\pm}3.9/hr$, p<0.05). Conclusion : This preliminary data confirms previous findings that CPAP is a very effective treatment for OSA, and that PLMD is developed or worsened with treatment by CPAP. This data also indicates that supine-sleeping position is more common when being treated with CPAP. However, there was no clear evidence that supine position is the causal factor of increased PLMD with CPAP. It is, however, suggested that the relative movement limitation induced by CPAP treatment could be a contributory factor of PLMD.

• Ocean and Polar Research
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• 제27권3호
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• pp.335-339
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• 2005

The underwater positioning system is important in interpreting data that are acquired from towing vehicles such as the deep-sea camera (DSC) system. Currently, several acoustic positioning systems such as long baseline (LBL), short baseline (SBL), and ultra short baseline (USBL), are used for underwater positioning. The accurate position of DSC, however, could not be determined in a R/V Onnuri unequipped with any of these underwater positioning systems. As an alternative, the DSC position was estimated based on the topography of towing track and cable length in the cruises before 1999. The great uncertainties, however, were found in the areas of flat bottom topography. In the 2003 and 2004 cruises these uncertainties were reduced by calculating the position of DSC with the cable length and seafloor depth below the vessel. The Japanese cruises for Mn-nodule used a similar estimation method for the DSC positioning system with a CTD sensor. Although the latter can provide better information for the position of DSC, the USBL underwater positioning system is strongly recommended for establishing better positioning of DSC and other towing devices.

• 한국측량학회:학술대회논문집
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• 한국측량학회 2003년도 추계학술발표회 논문집
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• pp.81-86
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• 2003

As the utility value of GPS in surveying field is on the increase after the conversion into the world geodetic system, it is attracting the interest of many people involved in the application of GPS. In this study an algorithm was established settling ambiguity through LAMBDA techniques and the baseline processing program was developed for L1/L2 carrier phase using visual c++ 6.0, which is an object-oriented language. And the developed program proved that it maintained a difference of less than 3mm over the short baseline of 1.5m or shorter when compared with other commercialized programs.

• 대한의용생체공학회:학술대회논문집
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• 대한의용생체공학회 1995년도 추계학술대회
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• pp.101-104
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• 1995

In this paper, we designed a cascade adaptive filter for elimination of the baseline drift and the distortion of the filtered signal. The cascade adaptive filter(CAF) consists of two filters. The first adaptive filter which has the cutoff frequency of 0.3Hz eliminate the noisy signal. The second adaptive filter remove the remnant baseline drift which is not eliminated by the first adaptive filter. Comparing the performance of the CAF with standard filter, recursive notch filter(RNF) and a adaptive impulse correlated filter(AICF), the CAF showed a higher performance in removal of the baseline drift than standard filler, and RNF. Also, considering the distortion of filtered signal, CAF is better than AICF and is comparable to the standard filter.

• 전자공학회논문지B
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• 제33B권7호
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• pp.99-106
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• 1996

Estimation and removal procedures for baseline drift have been developed using linear, cubic spline, and bilineared transformed high pass filter. Linear and cubic spline interpolation with the PQ and TP segmens, which are considered to be isoelectric, as fiducial points ahve been estimated respectively. For a quantitative validation of the estimation procedure, 4 ECGs with arfificial baseline drift were constructed and analyzed by mean square error calculations and amplitude histograms. Also real ECGs were analyzed in a test set of the CSE data set 3 and set 4. Baseline drift detecton rule were designed and new method for the decision of fiducial point were constructed to avoid distorting as the case of premature ventricular or atrial contraction. From these comparison, proposed cubic spline method with PQ and TP segment (CS_PQ & TP) emerged as the most efficient method.

• 풍력에너지저널
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• 제3권2호
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• pp.34-41
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• 2012

The paper is focusing on investigating the control characteristics of the baseline controller of 5 MW wind turbine provided by NREL(National Renewable Energy Laboratory). The baseline controller consist of two control logics, a maximum power tracking control below the rated wind speed and a constant power control above the rated wind speed. In the low wind speed, the mean generator power for changing the turbulent intensity and the optimal constant is studied through numerical simulations using FAST program. On the other hand, the constant power control logic and the constant control logic are compared in the high wind speed. It is confirmed that optimal constant is closely related to the turbulent intensity in low wind speed region and the constant torque control has better performance than the constant power control with respect to mechanical load in high wind speed region.

• 대한방사선기술학회지:방사선기술과학
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• 제45권5호
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• pp.397-405
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• 2022

Computed radiography (CR) systems, which convert an analog signal recorded on a cassette into a digital image, combine the characteristics of analog and digital imaging systems. Compared to digital radiography (DR) systems, CR systems have presented difficulties in evaluating system performance because of their lower detective quantum efficiency, their lower signal-to-noise ratio (SNR), and lower modulation transfer function (MTF). During the step of energy-storing and reading out, a baseline offset occurs in the edge area and makes low-frequency overestimation. The low-frequency offset component in the line spread function (LSF) critically affects the MTF and other image-analysis or qualification processes. In this study, we developed the method of baseline correction using mathematical morphology to determine the LSF and MTF of CR systems accurately. We presented a baseline correction that used a morphological filter to effectively remove the low-frequency offset from the LSF. We also tried an MTF evaluation of the CR system to demonstrate the effectiveness of the baseline correction. The MTF with a 3-pixel structuring element (SE) fluctuated since it overestimated the low-frequency component. This overestimation led the algorithm to over-compensate in the low-frequency region so that high-frequency components appeared relatively strong. The MTFs with between 11- and 15-pixel SEs showed little variation. Compared to spatial or frequency filtering that eliminated baseline effects in the edge spread function, our algorithm performed better at precisely locating the edge position and the averaged LSF was narrower.

• 대한방사선치료학회지
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• 제24권1호
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• pp.15-21
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• 2012

목 적: 본원에서 시행하고 있는 영상유도 방사선치료(Image Guided Radiation Therapy, IGRT)는 On-Board Imager system(OBI)을 이용하여 실시하고 있다. 본 논문에서는 Cone-Beam CT에서 물질 및 호흡의 변화가 영상에 미치는 영향을 분석하고 평가하고자 한다. 대상 및 방법: 호흡의 모양을 임의로 조정할 수 있는 구동 팬텀(Motion Phantom)을 이용하여 기준 호흡에 따른 주기, 진폭, 기저호흡(Baseline)을 변화시키면서 폐 등가 물질 내의 지름 3 cm인 구 형태의 아크릴(Acryl)과 임상에 이용되고 있는 표지자(Fiducial Marker) 두 물질에 대하여 Cone-Beam CT를 총 3회 획득하고, 분석하였다. 결 과: 첫 번째 물질의 종류에 따라 구동 팬텀의 동일한 움직임을 원형 아크릴(Arcyl)일 때 100%, 표지자일 때 120% 나타내었다. 두 번째 기준 호흡 변화에 따라 기준 호흡의 영상크기를 1로 상쇄(Offset)하면 원형 아크릴(Arcyl)의 경우 기저호흡(Baseline)을 1.8 mm 이동 시켰을 때 1.13, 3.3 mm 이동 시켰을 때 1.27, 주기가 1초일 때 1.01, 2.5초일 때 1.045, 진폭이 기준의 0.7배일 때 0.86, 1.7배일 때 1.43의 변화를 보였고, 표지자의 경우 Baseline 1.8 mm shift일 때 1.18, 3.3 mm shift일 때 1.34, 주기가 1초일 때 1.0, 2.5초일 때 1.0, 진폭이 기준의 0.7배일 때 0.99, 1.7배일 때 1.66의 변화를 보였다. 결 론: Cone-Beam CT는 물질에 따라 그 움직임을 나타내는 것에 Fiducial marker의 경우 영상 크기에 20%의 영향이 있었다. 호흡의 변화에 따른 영향은 아크릴(Arcyl)의 경우 최소 13% 최대 43%, Fiducial marker의 경우 최소 18% 최대 66%의 변화를 보였다. 이런 영상의 차이는 큰 불확실성 요인이므로 Cone-Beam CT 획득 전에 환자의 호흡을 안정화해야 한다. 또한 영상획득 중간에도 지속적인 환자의 호흡 관찰을 하여 환자의 큰 호흡변화를 관찰하였다면 영상유도 후에 반드시 투시를 이용하여 치료부위를 확인할 필요가 있으며 재 Cone-Beam CT 획득을 통하여 보다 정확한 영상유도를 하는 것이 바람직하다고 사료된다.

• 대한의용생체공학회:의공학회지
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• 제16권4호
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• pp.517-524
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• 1995

This paper is a study on the design of the cascade adaptive filter (CAF) for baseline wandering elimination in order to enhance the performance of the detection of ST segments in ECG. The CAF using Least Mean Square (LMS) algorithm consists of two filters. The primary adaptive filter which has the cutoff frequency of 0.3Hz eliminates the baseline wandering in raw ECG The secondary adaptive filter removes the remnant baseline wandering which is not eliminated by the primary adaptive filter. The performance of the CAF was compared with the standard filter, the recursive filter, and the adaptive impulse correlated filter (AICF). As a result, the CAF showed a lower signal distortion than the standard filter and the AICF. Also, the CAF showed a better perf'ormance in noise elimination than the standard filter and the recursive filter. In conclusion, considering the characteristics of the noise elimination and the signal distortion, the CAF shows a better performance in the removal of the baseline wandering than the other three Otters and suggests the high performance in the detection of ST segment.