• 한국음향학회지
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• 제7권4호
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• pp.98-109
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• 1988

본 연구는 이차 볼테라 필터 계수를 연속적으로 변화시키기 위하여 sequential regression (SER) 방법을 이용한 적응 비선형 디지탈 필터링 알고리즘에 대하여 서술하였다. 일반적으로 SER 방법은 Wiener 필터 이론을 볼테라필터에 직접 적용시킬때 생기는 큰 행렬을 역변환시키기 위하여 사용되었다. 그러나, 본 연구에서는 입력신호가 가우시안일 경우, 최소 자승해를 구하기 위하여 SER 방법을 이용하였다. 이 알고리즘에서, 역변환시킬 행렬의 크기는 일반적 접근 방법보다 작게 되기때문에, 일반적 비선형 시스템 인식 기술보다 본 연구에서 제시한 방법의 계산량이 적다. 본 연구에서 제안한 알고리즘의 성능을 검토하기 위하여 시뮬레이션 결과를 구했다.

• Smart Structures and Systems
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• 제31권2호
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• pp.101-111
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• 2023

Structural health monitoring (SHM) covers a range of damage detection strategies for buildings. In real-time, SHM provides a basis for rapid decision making to optimise the speed and economic efficiency of post-event response. Previous work introduced an SHM method based on identifying structural nonlinear hysteretic parameters and their evolution from structural force-deformation hysteresis loops in real-time. This research extends and generalises this method to investigate the impact of a wide range of flag-shaped or pinching shape nonlinear hysteretic response and its impact on the SHM accuracy. A particular focus is plastic stiffness (K_p), where accurate identification of this parameter enables accurate identification of net and total plastic deformation and plastic energy dissipated, all of which are directly related to damage and infrequently assessed in SHM. A sensitivity study using a realistic seismic case study with known ground truth values investigates the impact of hysteresis loop shape, as well as added noise, on SHM accuracy using a suite of 20 ground motions from the PEER database. Monte Carlo analysis over 22,000 simulations with different hysteresis loops and added noise resulted in absolute percentage identification error (median, (IQR)) in K_p of 1.88% (0.79, 4.94)%. Errors were larger where five events (Earthquakes #1, 6, 9, 14) have very large errors over 100% for resulted K_p as an almost entirely linear response yielded only negligible plastic response, increasing identification error. The sensitivity analysis shows accuracy is reduces to within 3% when plastic drift is induced. This method shows clear potential to provide accurate, real-time metrics of non-linear stiffness and deformation to assist rapid damage assessment and decision making, utilising algorithms significantly simpler than previous non-linear structural model-based parameter identification SHM methods.

• 한국임상약학회지
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• 제6권2호
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• pp.1-6
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• 1996

Carcadian rhythm dependence of vancomycin pharmacokinetics was evaluated in 5 normal volunteers receiving a single intravenous 1.0 g dose of vancomycin at 8 o'clock in the morning and another occasion at 8 o'clock in the evening in a crossover manner. The serum data were subjected to simultaneous computer nonlinear least squares regression analysis using a two-compartment pbarmacokinetic model. The mean half-life of vancomycin was $4.78\pm0.81$ hr in the morning and $4.25\pm0.51$ hr in the evening. The mean total body clearance of vancomycin was $1.29\pm0.58$ hr in the morning and $5.58\pm0.48$ hr in the evening. No circadian rhythm was found to be apparent in normal volunteers. The mean in intrasubject difference in the half-life between 8 A.M. and 8 P.M. was $15.4\%$ with fluctuations ranging from $10.4\sim33.8\%$, It is reasonable to consider individual circadian rhythm for effective dosage regimen of vancomycin in clinical chronotherapeutics.

• 한국대기환경학회지
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• 제26권5호
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• pp.533-542
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• 2010

The $PM_{10}$ concentrations in the underground should be monitored for the health of commuters on the underground subway system. Seoul Metro and Seoul Metropolitan Rapid Transit Corporation are measuring several air pollutants regularly. As for the measurement of $PM_{10}$ concentrations, instruments based on $\beta$-ray absorption method and gravimetric methods are being used. But the instruments using gravimetric method give us 20-hour-average data and the $\beta$-ray instruments can measure the $PM_{10}$ concentration every one hour. In order to keep the $PM_{10}$ concentrations under a healthy condition, the air quality of the underground platform and tunnels should be monitored and controlled continuously. The $PM_{10}$ instruments using light scattering method can measure the $PM_{10}$ concentrations every less than one minute. However, the reliability of the instruments using light scattering method is still not proved. The purpose of this work is to study the reliability of the instruments using light scattering method to measure the $PM_{10}$ concentrations continuously in the underground platforms. One instrument using $\beta$-ray absorption method and two different instruments using light scattering method (LSM1, LSM2) were placed at the platform of the Jegi station of Seoul metro line Number 1 for 10 days. The correlation between the $\beta$-ray instrument and the LSM2 ($r^2$=0.732) was higher than that between the $\beta$-ray instrument and the LSM1 ($r^2$=0.393). Thus the LSM2 was chosen for further analysis. Three different regression analysis methods were tested: Linear regression analysis, Nonlinear regression analysis and Orthogonal regression analysis. When the instruments using light scattering method were used, the data measured these instruments have to be converted to actual $PM_{10}$ concentrations using some factors. With these analyses, the factors could be calculated successfully as linear and nonlinear forms with respect to the data. And the orthogonal regression analysis was performed better than the ordinary least squares method by 28.45% reduction of RMSE. These findings propose that the instruments using light scattering method light scattering method can be used to measure and control the $PM_{10}$ concentrations of the underground subway stations.

• 분석과학
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• 제11권1호
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• pp.47-53
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• 1998

본 연구는 당뇨병 진단방법의 개선을 위하여 채혈을 직접적으로 하지 않고 혈당을 측정할 수 있도록 하기 위하여 근적외선 분광법을 적용하였다. 본 연구를 위하여 근적외선 분광법을 이용하여 1 mg/dL에서 200 mg/dL 사이의 표준 시료 80개 글루코오스 흡수 스팩트럼을 측정하고 이를 정량하여 표준 농도와의 상관관계를 비교하였을 때 1.8 mg/dL 오차범위에서 매우 우수하였다. 그리고 실제 혈액중에 존재할 수 있는 전해질 및 피부에 의한 산란의 영향을 연구하였을 때 모두 2.8 mg/dL 및 3.8 mg/dL의 표준오차를 나타내었다. 특히 실제 피부에 적용하기 위하여 검량곡선에 비직선성을 유발하는 빛의 산란 현상에 관한 모델링을 통하여 정확도를 향상시키는 통계적인 방법을 제시하였다.

• Journal of Radiation Protection and Research
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• 제45권4호
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• pp.171-177
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• 2020

Background: This study aims to determine the effective atomic number (Zeff) from dual-energy image sets obtained using a conventional computed tomography (CT) simulator. The estimated Zeff can be used for deriving the stopping power and material decomposition of CT images, thereby improving dose calculations in radiation therapy. Materials and Methods: An electron-density phantom was scanned using Philips Brilliance CT Big Bore at 80 and 140 kVp. The estimated Zeff values were compared with those obtained using the calibration phantom by applying the Rutherford, Schneider, and Joshi methods. The fitting parameters were optimized using the nonlinear least squares regression algorithm. The fitting curve and mass attenuation data were obtained from the National Institute of Standards and Technology. The fitting parameters obtained from stopping power and material decomposition of CT images, were validated by estimating the residual errors between the reference and calculated Zeff values. Next, the calculation accuracy of Zeff was evaluated by comparing the calculated values with the reference Zeff values of insert plugs. The exposure levels of patients under additional CT scanning at 80, 120, and 140 kVp were evaluated by measuring the weighted CT dose index (CTDIw). Results and Discussion: The residual errors of the fitting parameters were lower than 2%. The best and worst Zeff values were obtained using the Schneider and Joshi methods, respectively. The maximum differences between the reference and calculated values were 11.3% (for lung during inhalation), 4.7% (for adipose tissue), and 9.8% (for lung during inhalation) when applying the Rutherford, Schneider, and Joshi methods, respectively. Under dual-energy scanning (80 and 140 kVp), the patient exposure level was approximately twice that in general single-energy scanning (120 kVp). Conclusion: Zeff was calculated from two image sets scanned by conventional single-energy CT simulator. The results obtained using three different methods were compared. The Zeff calculation based on single-energy exhibited appropriate feasibility.

• Journal of Radiation Protection and Research
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• 제48권3호
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• pp.153-161
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• 2023

Background: Fukushima Medical University (FMU) is located 57 km northwest of the Fukushima Daiichi Nuclear Power Plant. Our laboratory has been conducting environmental radiation measurements continuously before and after the nuclear accident. We aimed to report the observed behavior of radiation originating from the released radioactive materials due to the accident, predict future trends, and disseminate the results to the local residents. Materials and Methods: Measurements of the counting rate by a diameter of 76 mm and a length of 76 mm thallium-doped sodium iodide (NaI[Tl]) scintillation detector (S-1211-T; Teledyne Brown Engineering Environmental Services) in the central part of the laboratory, and the dose rate outward at the window by NaI(Tl) scintillation detector and digital processor (EMF211; EMF Japan Co. Ltd.) were conducted. Results and Discussion: Measurements by Teledyne S-1211-T showed that in the early stages, radiation from radioactive isotopes with short half-lives was dominant, while radiation from radioactive isotopes with longer half-lives became dominant as the measurement period became longer. Through nonlinear least squares regression, both short and long half-lives were successfully determined. It was also possible to predict how the radiation dose would decrease. The environmental radiation trends around FMU were measured by the EMF211. Both measurements were affected by rainfall and snow accumulation. Decontamination work on the FMU campus impacted measurements by the EMF211 especially. Conclusion: The results of two types of measurements, one at the center and the other at the window side of the laboratory, were presented. By applying a simplified model, radiation from radioactive isotopes with short and long half-lives was identified. Based on these results, future trends were predicted, and the information was used for public communication with the local residents.

• Journal of Animal Science and Technology
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• 제45권6호
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• pp.885-890
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• 2003

본 연구는 재래돼지와 랜드레이스 품종을 기초축으로 조성한 F2 집단의 일령별 체중 자료를 이용하여 비선형 회귀에 의해 추정한 개체별 성장곡선 모수 및 성장 특성치에 대한 LEPR 관련 초위성체 표지인자의 다형성에 따른 효과를 추정함으로써 Leptine 수준에 따른 성장 형질의 특성을 규명하고자 실시하였다. 조사된 F2 집단에 대해 개체별 성숙체중(A)과 성숙률(k)의 평균은 각각 179.69${\pm}$4.40kg 및 0.3103${\pm}$0.0043으로 추정되었으며, 성장 특성에 대한 성의 효과는 통계적 유의성이 없었으며 (p〉.05), 성숙체중(A) 및 최대 증체 속도($\partial$W$_{t1}$/$\partial$t)는 분만 그룹에 따른 유의적인 차이를 보였다(p〈.05). 조사된 모든 성장특성에 대해 LEPR 표지인자의 다형성 효과는 유의적으로 나타났으며(p〈.05), AA 유전자형을 가지는 개체는 만숙성이며, 반면 유전자형이 DD인 경우, 조사된 유전자형들 가운데 초기 성장이 빠른 조숙성의 성장 특성으로 가지지만, 성장률의 증가추세가 일찍 감소하며, 성숙체중의 최대치는 낮을 것을 추정되었다. 따라서 조사된 LEPR 관련 표지인자 유전자형의 다형성에 따른 성장 특성의 해석 및 예측이 가능하며, 그 범위는 생애 전반에 걸쳐 적용해야 할 것으로 사료된다.

• 한국응용곤충학회지
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• 제35권2호
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• pp.119-125
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• 1996

가루깍지벌레 월동안 부화시기 예찰모형을 수립하기 위하여 월동알에 대한 온도발육 실험이 수행된다. 5개온도(10, 15, 20, 25, 27$^{\circ}C$)와 채집시기별로 월동알 부화기간을조사하여 비교분석하였다. Wagner 등 (1984a)의 비선형발육모형이 온도별 평균발육률에 대하여 적용되었으며 ($R^2$=0.9729). 발육영점온도는 15~$25^{\circ}C$ 영역에서 얻은 직선회귀식에 의하여 $11.9^{\circ}C$로 추정되었으며, 발육완료를 위해서는 154.14일도가 필요하였다. 적산온도 모형과 발육률전산(Wagner 등 1985) 모형이 부화시기 예측에 이용된다. 적산온도 모형은 평균온도에서 발육영점온도 이상의 온도를 적산하는 방법(Mean-minus-base 추정법), Sine wave 추정법(Allen 1976), 그리고 Rectangle 추정법(Arnold 1960)을 잉요하여 계산하였다. 50% 부화예측일을 실측일과 비교한 결과 적산온도를 이용하는 경우 Mean-minus-base 추정법은 18~28일, Sine wave 추정법은 11~14일, 그리고 Rectangle 추정법은 3~5일의 편차를 보였고, 발육률 적산모형은 2~3일의 편차가 있었다.