• 한국광학회지
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• 제11권6호
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• pp.452-456
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• 2000

동맥혈의 맥동성분에 의한 파장별 광흡수도를 측정하여 비침습적으로 산소포화도 값을 알수 있는 펄스옥시미터 장치와 신호처리방법을 개발하고 예측 알고리즘을 적용하였다. 본 장치는 광원 및 검출기로 구성된 프로브와 광신호 처리부, LED 구동회로 PC 인터페이스부로 구성되었고 데이터의 수집을 위한 구동소프트웨어 및 데이터 처리 소프트웨어를 개발하였다. 개발된 산소포화도 측정장치의 성능을 평가하는데에는 Bio-Tek 사의 펄스 옥시미터 시뮬레이터를 사용하여 다양한 알고리즘 및 데이터처리 방법들을 비교분석한 결과 맥동파형의 $In(I_p/I_v) 값을 I_{avr}$값으로 보정하는 계산 알고리즘의 방법과 진폭비보다 면적비를 이용한 계산방법이 산소포화도와의 상관관계가 우수한 것으로 나타났다. 정확한 신호 획득을 위해 개발된 맥동의 기저선 보상처리 프로그램을 inv-vivo 테스트의 데이터 처리방법에 적용하여 결과가 향상되는 것을 확인하였고 광원으로 660nm(Red)와 805nm(IR)파장을 이용한 경우보다 660nm(Red)와 940nm(IR) 파장을 이용했을 때 산소포화도와의 상관관계 및 정밀도에서 더 우수한 결과를 얻을 수 있었다.

• International Journal of Ocean System Engineering
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• 제1권2호
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• pp.60-67
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• 2011

This paper presents an in-situ correction method to compensate for the position error of an autonomous underwater vehicle (AUV) near the sea floor. AUVs generally have an inertial navigation system assisted with auxiliary navigational sensors. Since the inertial navigation system shows drift in position without the bottom reflection of a Doppler velocity log, external acoustic positioning systems, such as an ultra short baseline (USBL), are needed to set the position without surfacing the AUV. The main concept of the correction method is as follows: when the AUV arrives near the sea floor, the vehicle moves around horizontally in a circular mode, while the USBL transceiver installed on a surface vessel measures the AUV's position. After acquiring one data set, a least-square curve fitting method is adopted to find the center of the AUV's circular motion, which is transferred to the AUV via an acoustic telemetry modem (ATM). The proposed method is robust for the outlier of USBL, and it is independent of the time delay for the data transfer of the USBL position with the ATM. The proposed method also reduces the intrinsic position error of the USBL, and is applicable to the in-situ calibration as well as the initialization of the AUVs' position. Monte Carlo simulation was conducted to verify the effectiveness of the method.

• 분석과학
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• 제7권4호
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• pp.427-434
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• 1994

GFAAS(graphite furnace atomic absorption spectrophotometer)를 이용하여 혈액 중 납을 분석할 때, 납은 비교적 휘발성 원소인 관계로 바탕선이 높아지므로 희화 온도를 일정 온도 이상으로 높일 수 없었다. 그래서 종래에는 매트릭스 변형제를 사용하여 희화 온도를 $700^{\circ}C$까지 올려서 희화시켜야 바탕선이 안정되었다. 본 연구에서는 광온도 및 전류 제어 장치가 부착된 기기(Shimadzu, AA-6501S)를 사용하여 온도조절을 단시간에 정확히 함으로써 매트릭스 변형제를 사용하지 않고 Triton X-100으로만 희석하여 분석해도 희화 온도 $550^{\circ}C$ 부근에서 바탕선이 안정됨을 알았다. 또한 자동 바탕 보정 장치인 $D_2$ arc형과 SR(self reversal)법을 비교해 본 결과, 같은 농도에서의 흡광도는 $D_2$ arc형이 높았으나 BGC(background correction)값은 SR법이 높음을 알았다.

• 대한원격탐사학회:학술대회논문집
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• 대한원격탐사학회 1999년도 Proceedings of International Symposium on Remote Sensing
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• pp.474-478
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• 1999

SAR interferometry (InSAR) using the space-borne Synthetic Aperture Radar (SAR) have recently become one of the most effective tools monitoring surface changes caused by landslides, earthquakes, subsidences or volcanic eruption. This study focuses on examining the feasibility of InSAR using the RADARSAT data. Although the RABARSAT SAR with its high resolution and variable incidence angle has several advantages for repeat-pass InSAR, it has two key limitations: first, the orbit is not precisely known; and second, RADARSAT's 24-day repeat pass interval is not very favourable for retaining useful coherence. In this study, two pairs of RADARSAT data in the Nahanni area, NWT, Canada have been tested. We will discuss about the special consideration required on the interferometric processing steps specifically for RADARSAT data including image co-registration, spectral filtering in both azimuth and range, estimation of the interferometric baseline, and correction of the interferogram with respect to the "flat earth" phase contribution. Preliminary results can be summarized as: i) the properly designed azimuth filter based upon the antenna characteristic improves coherence considerably if difference in Doppler centroid of the two images is relatively large; ii) the co-registration process combined by fringe spectrum and amplitude cross-correlation techniques results in optimal matching; iii) the baseline is not always possible to be estimated from the definitive orbit information.

• 한국측량학회지
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• 제22권2호
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• pp.137-143
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• 2004

EDM 기계는 1950년대 최초로 소개된 이후 전자 및 광학기술의 발전에 힘입어 소형화, 고정밀화 됨으로써 현재에는 측량뿐만 아니라 정밀 과학 계측 분야에서까지 널리 활용되고 있다. EDM 기계에 대한 원리의 이해 및 표준화된 관측 방법에 대한 이해와 더불어 정밀도에 대한 이해는 측정 결과의 신뢰성 향상 및 산업측량, 시공측량 등의 활용 분야에 있어서 2차적인 생산물의 품질 향상을 위해서 매우 중요하다 할 수 있다. 이러한 EDM 기계의 정밀도 유지를 위해서 규칙적이고 주기적인 점검이 이루어져야 하며, 단순하면서도 정밀한 점검 방법이 요구된다. 본 논문에서는 기선거리 관측 데이터로부터 최소자승법을 이용하여 간단하게 EDM 기계의 보정계수인 영점오차와 축척오차를 동시에 결정하는 방법을 제시하였고 산정된 보정계수를 이용하여 EDM 기계의 정밀도에 따른 검교정을 위한 검정 방법을 제시하였다.

• Clinical and Experimental Pediatrics
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• 제65권5호
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• pp.254-261
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• 2022

Background: The use of systemic steroids for 6+ weeks in children is associated with decreased bone mineral content (BMC) and density (BMD). However, the effects of a shorter duration of use on BMD are unknown. Purpose: To determine the effect of the use of systemic steroids for 2-6 weeks on BMD and BMC in pediatric patients. Methods: Twenty-five pediatric patients (21 with tuberculosis, 2 with systemic juvenile idiopathic arthritis, 1 with inflammatory bowel disease, 1 with autoimmune hemolytic anemia) who received systemic steroids for 2-6 weeks and 25 age- and sex-matched controls were enrolled. BMC, BMD, and z scores of the whole body (WB), lumbar spine (LS), nondominant distal radius (DR), and total body less the head (TBLH) were determined by dual-energy x-ray absorptiometry at baseline, the end of steroid therapy or 6 weeks (whichever was earlier; first follow-up), and at the end of 3 months from baseline (second follow-up) in patients and at baseline in controls. The values were adjusted for confounding variables. Continuous and categorical variables were compared using Student t test and the chi-square test or Fisher exact test, respectively. Pairwise comparisons employed Bonferroni correction. Results: Statistically significant decreases in BMC, BMD, and all z scores were observed. BMC declined by 5.37%, 2.08%, 1.82%, and 2.27%, and 11.42%, 3.75%, 3.34%, and 4.17% for WB, LS, DR, and TBLH, respectively, at the first and second follow-ups, respectively. Similarly, BMD declined by 2.01%, 2.31%, 2.18%, and 1.70% and 4.59%, 3.76%, 3.14%, and 3.50% for the WB, LS, DR, and TBLH, respectively, at the first and second follow-ups, respectively. A significant negative correlation was found among bone densitometric parameters, duration, and cumulative dose. Conclusion: The use of systemic steroids for 2-6 weeks in pediatric patients decreased the BMD and BMC of trabecular and cortical bones, an effect that persisted after discontinuation.

• 한국항공우주학회지
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• 제39권2호
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• pp.153-161
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• 2011

한국항공우주연구원에서는 GBAS 기준국의 무결성 감시 알고리즘 개발을 위한 데이터 제공 및 시험을 위하여 무결성 감시 테스트베드를 구축하였다. 개발된 알고리즘의 정확한 구현 및 시험을 위해서는 기반이 되는 시설 및 소프트웨어의 기본 기능이 국제 표준에 부합하게 구현되어 있어야 하므로, 본 논문에서는 현재 구축된 테스트베드의 GBAS 기준국으로서의 기본 기능에 대한 검증시험을 수행한다. 이를 위해 국제적으로 신뢰받고 있는 프로그램인 PEGASUS와의 비교를 통하여 GBAS 보정 정보의 타당성을 확인하였으며, 이를 적용한 사용자 측면에서의 거리 영역 및 위치 영역에서의 데이터 분석을 통하여 시스템의 무결성 및 가용성 성능을 확인하였다.

• 대한임베디드공학회논문지
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• 제18권2호
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• pp.41-50
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• 2023

Gait analysis is an important tool in the clinical management of cerebral palsy, allowing for the assessment of condition severity, identification of potential gait abnormalities, planning and evaluation of interventions, and providing a baseline for future comparisons. However, traditional methods of gait analysis are costly and time-consuming, leading to a need for a more convenient and continuous method. This paper proposes a method for analyzing the posture of cerebral palsy patients using only smartphone videos and deep learning models, including a ResNet-based image tilt correction, AlphaPose for human pose estimation, and SmoothNet for temporal smoothing. The indicators employed in medical practice, such as the imbalance angles of shoulder and pelvis and the joint angles of spine-thighs, knees and ankles, were precisely examined. The proposed system surpassed pose estimation alone, reducing the mean absolute error for imbalance angles in frontal videos from 4.196° to 2.971° and for joint angles in sagittal videos from 5.889° to 5.442°.

• Nuclear Engineering and Technology
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• 제55권12호
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• pp.4350-4356
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• 2023

Radiation detection systems working at high count rates suffer from the overlapping of their output electric pulses, known as pulse pile-up phenomenon, resulting in spectrum distortion and degradation of the energy resolution. Pulse tail extrapolation is a pile-up correction method which tries to restore the shifted baseline of a piled-up pulse by extrapolating the overlapped part of its preceding pulse. This needs a mathematical model which is almost always nonlinear, fitted usually by a nonlinear least squares (NLS) technique. NLS is an iterative, potentially time-consuming method. The main idea of the present study is to replace the NLS technique by an integration-based non-iterative method (NIM) for pulse tail extrapolation by an exponential model. The idea of linear extrapolation, as another non-iterative method, is also investigated. Analysis of experimental data of a NaI(Tl) radiation detector shows that the proposed non-iterative method is able to provide a corrected spectrum quite similar with the NLS method, with a dramatically reduced computation time and complexity of the algorithm. The linear extrapolation approach suffers from a poor energy resolution and throughput rate in comparison with NIM and NLS techniques, but provides the shortest computation time.

• 대기
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• 제31권5호
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• pp.593-606
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• 2021

The Korea Meteorological Administration/National Institute of Meteorological Sciences (KMA/NIMS) has monitored atmospheric CO₂ at Anmyeondo (AMY) World Meteorological Organization (WMO) Global Atmosphere Watch Programme (GAW) regional station since 1999, and expanded its observations at Jeju Gosan Suwolbong station (JGS) in the South and at Ulleungdo-Dokdo stations in the East (ULD and DOK) since 2012. Due to a recent WMO CO₂ scale update and a new filter (NIMS) to select baseline levels at each station, the 22 years of CO₂ data are recalculated. After correction for the new CO₂ scale, we confirmed that those corrected records are reasonable within the compatibility goal (±0.1 ppm of CO₂) between KMA/NIMS and National Oceanic and Atmosphereic Administration (NOAA) flask-air measurements with the new scale. With the new NIMS filter, CO₂ baseline levels are now more representative of the large-scale background compared to previous values, which contained large CO₂ enhancements. Atmospheric CO₂ observed in South Korea is 4 to 8 ppm greater than the global average while the amplitude of seasonal variation is similar (10~13 ppm) to the amplitude averaged over a comparable latitude zone (30°N-60°N). Variations in CO₂ growth rate are also similar, increasing and decreasing similar to global values, as it reflects the net balance between terrestrial respiration and photosynthesis. In 2020, atmospheric CO₂ continued increasing despite the COVID-19 pandemic. Even though fossil emission was reduced (around -7% globally), we still emitted large amounts of anthropogenic CO₂. Overall, since CO₂ has large natural variations and its source was derived from not only fossil fuel but also biomass burning, the small fossil emission reduction could not affect the atmospheric level directly.