• Smart Structures and Systems
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• 제10권4_5호
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• pp.427-442
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• 2012

An effective approach for updating finite element model is presented which can provide reliable estimates for structural updating parameters from identified operational modal data. On the basis of the dynamic perturbation method, an exact relationship between the perturbation of structural parameters such as stiffness change and the modal properties of the tested structure is developed. An iterative solution procedure is then provided to solve for the structural updating parameters that characterise the modifications of structural parameters at element level, giving optimised solutions in the least squares sense without requiring an optimisation method. A regularization algorithm based on the Tikhonov solution incorporating the generalised cross-validation method is employed to reduce the influence of measurement errors in vibration modal data and then to produce stable and reasonable solutions for the structural updating parameters. The Canton Tower benchmark problem established by the Hong Kong Polytechnic University is employed to demonstrate the effectiveness and applicability of the proposed model updating technique. The results from the benchmark problem studies show that the proposed technique can successfully adjust the reduced finite element model of the structure using only limited number of frequencies identified from the recorded ambient vibration measurements.

• 한국농공학회논문집
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• 제61권1호
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• pp.95-105
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• 2019

Evapotranpiration (ET) is one of the important factor in Hydrological cycle and irrigation planning. In this study, temperature-based artificial neural network (ANN) model for daily reference crop ET estimation was developed and compared with reference crop evapotranpiration ($ET_0$) from FAO-56 Penman-Monteith method (FAO-56 PM) and parameter regionalized Hargreaves method. The ANN model was trained and tested for 10 weather stations (5 inland stations and 5 costal stations) and two input climate factors, maximum temperature ($T_{max}$), minimum temperature ($T_{min}$), and extraterrestrial radiation (RA) were used for training and validation of temperature-based ANN model. Monthly reference ET by the ANN model also compared with parameter regionalized Hargreaves method for ANN model applicability evaluation. The ANN model evapotranspiration demonstrated more accordance to FAO-56 PM evapotranspiration than the $ET_0$ from parameter regionalized Hargreaves method(R-Hargreaves). The results of this study proposed that daily reference crop ET estimated by the ANN model could be used in the condition of no sufficient climate data.

• Smart Structures and Systems
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• 제29권5호
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• pp.715-728
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• 2022

Recently, numbers of long span pedestrian suspension bridges have been constructed worldwide. While recent tragedies regarding pedestrian suspension bridges have shown how these bridges can wreak havoc on the society, there are no specific guidelines for construction standards nor safety inspections yet. Therefore, a structural health monitoring system that could help ensure the safety of pedestrian suspension bridges are needed. System identification is one of the popular applications for structural health monitoring method, which estimates the dynamic system. Most of the system identification methods for bridges are currently adapting output-only system identification method, which assumes the dynamic load to be a white noise due to the difficulty of measuring the dynamic load. In the case of pedestrian suspension bridges, the pedestrian load is within specific frequency range, resulting in large errors when using the output-only system identification method. Therefore, this study aims to develop a system identification method for pedestrian suspension bridges considering both input and output of the dynamic system. This study estimates the location and the magnitude of the pedestrian load, as well as the dynamic response of the pedestrian bridges by utilizing artificial intelligence and computer vision techniques. A simulation-based validation test was conducted to verify the performance of the proposed system. The proposed method is expected to improve the accuracy and the efficiency of the current inspection and monitoring systems for pedestrian suspension bridges.

• 분석과학
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• 제24권6호
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• pp.533-543
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• 2011

hERG (human ether-a-go-go related gene) 이온채널은 심장 재분극의 중요 요소이며 이 채널의 저해제는 부정맥과 돌연사를 유발할 수 있다. 따라서, 신약개발과정에서 후보물질이 hERG 이온채널의 잠재적인 저해제일 경우에는 심장독성 부작용을 유발하므로, 이를 최소화하고자 많은 노력이 집중되고 있다. 본 연구는 HEK(인간 배아 신장)세포에서 얻은 202개 유기화합물의 $IC_{50}$ 데이터를 이용하여 2차원 구조-활성의 정량적 관계(2D-QSAR)방법으로 예측하는 모델을 개발하였다. hERG이온채널 저해제의 기계 학습방법으로는 다중선형회귀(Multiple Linear Regression), 서포트 벡터 머신(Support Vector Machine: SVM)방법과 인공신경망(Artificial Neural Network)방법이며, 교차검증을 적용한 모집단 기반 전진선택(forward selection)방법과 결합하여 각 학습모델에 적합한 최적의 표현자들을 결정하였다. 가장 우수한 방법은 14종의 표현자를 사용한 인공신경망방법($R^2_{CV}$=0.617, RMSECV=0.762, MAECV=0.583)이었고, 다중선형회귀방법을 통해서 hERG이온채널 저해물질의 구조적 특징과 수용체와의 상호작용을 설명할 수 있다. QSAR모델의 검증은 교차검증과 Y-scrambling test방법으로 수행하였다.

• 한국식품영양과학회지
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• 제43권11호
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• pp.1737-1741
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• 2014

개별 인정형 건강기능식품 기능성 원료로 개발한 고흥 유자추출물의 표준화를 위해 지표성분으로 naringin을 설정하였으며, HPLC를 이용하여 지표성분 naringin의 분석법을 확립하고 그에 따른 유효성분 검정을 실시하고자 하였다. 유효성 검정 결과, 본 시험법에서 표준용액의 retention time과 고흥 유자 추출물의 retention time이 일치하는 것을 확인할 수 있었으며 동일한 spectrum을 나타내어 특이성을 확인하였다. 검량선의 상관계수($R^2$)는 0.9986으로 높은 직선성을 보였으며 검출한계는 0.0218 mg/L, 정량한계는 0.0661 mg/L로 설정되었다. Naringin의 회수율은 1 mg/mL에서는 95.75~98.25%, 0.5 mg/mL에서는 97.67~101.01%, 0.1 mg/mL에서는 97.33~104.64%, 0.05 mg/mL에서는 95.53~106.82%의 범위의 회수율을 얻었으며 intra-day에서의 정밀도(RSD)는 1.39~1.95%, inter-day에서는 0.17~1.49%의 정밀도를 나타내어 고흥 유자 추출물의 지표성분 naringin의 분석법은 적합한 시험법임을 확인하였다.

• Journal of Pharmaceutical Investigation
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• 제35권3호
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• pp.137-142
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• 2005

A rapid, selective and sensitive reversed-phase HPLC method for the determination of glipizide in human serum was validated and applied to the pharmacokinetic study of glipizide. Glipizide and internal standard, tolbutamide, were extracted from human serum by liquid-liquid extraction with benzene and analyzed on a Nova Pak $C_{18}\;60{\AA}$ column with the mobile phase of acetonitrile-potassium dihydrogen phosphate (10 mM, pH 3.5) (4:6, v/v). Detection wavelength of 275 nm and flow rate of 0.7 ml/min were fixed for the study. The assay robustness for the changes of mobile phase pH, organic solvent content, and flow rate was confirmed by $3^3$ factorial design using a fixed glipizide concentration (500 ng/ ml) with respect to its peak area and retention time. And also, the ruggedness of this method was investigated at three different laboratories using same quality control (QC) samples. This method showed linear response over the concentration range of 10-1000 ng/ml with correlation coefficient greater than 0.999. The lower limit of quantitation using 0.5 ml of serum was 10.0 ng/ml, which was sensitive enough for pharmacokinetic studies. The overall accuracy of the quality control samples ranged from 82.6 to 105.0% for glipizide with overall precision (% C.V.) being 1.13-13.20%. The percent recovery for human serum was in the range of 85.2 93.5%. Stability studies showed that glipizide was stable during storage, or during the assay procedure in human serum. The peak area and retention time of glipizide were not significantly affected by the changes of mobile phase pH, organic solvent content, and flow rate under the conditions studied. This method showed good ruggedness (within 15% C.V.) and was successfully used for the analysis of glipizide in human serum samples for the pharmacokinetic studies at three different laboratories, demonstrating the suitability of the method.

• Journal of Applied Biological Chemistry
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• 제65권4호
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• pp.343-348
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• 2022

백지는 산형과(Umbelliferae)에 속하는 구릿대(Angelica dahurica)의 뿌리를 건조한 것으로, 다양한 약리작용을 하는 것으로 알려져 예로부터 한약재로 사용되어 왔다. 백지의 대표적인 활성 성분인 coumarin을 포함하여 다양한 성분이 알려져 있으며, 최근 백지의 다양한 생리활성이 보고되고 있다. 본 연구는 백지를 건강기능식품의 기능성 원료로 활용하고자, 백지의 지표성분 설정 및 이에 대한 UPLC 분석법을 확립하여 분석법 유효성 검증을 실시하였다. 백지의 지표성분으로는 oxypeucedanin hydrate, byakangelicol, oxypeucedanin, imperatoin, phellopterin, isoimperatorin의6종을 설정하였다. 분석법 유효성 검증은 특이성, 직선성, 검출한계, 정량한계, 정확성, 정밀성 등의 항목을 이용하여 확인하였다. 본 시험법에서 지표성분 6종은 서로 간섭없이 분리되어 특이성을 확인하였고, 결정계수의 값도 0.999 이상으로 나타나 높은 직선성을 나타내었다. 분석법 유효성 검증 결과, 지표 성분 6종의 RSD는 5% 이하로 나타났으며 90-110%의 범위의 회수율을 나타내 높은 정확성과 정밀성이 있는 것을 확인할 수있었다. 이러한 결과는 UPLC를 이용한 백지의 지표성분 분석법이, 새롭게 제시한 6종에 대해 적합한 동시분석 분석법임을 나타낸다. 따라서, 본 연구를 통하여 확립된 백지의 지표성분 분석법이 향후 백지(구릿대)의 건강기능식품 기능성 원료 개발을 위한 기초자료로 활용될 것으로 기대된다.

• 한국축산식품학회지
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• 제39권1호
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• pp.93-101
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• 2019

Nucleotides play important roles in numerous intracellular biochemical processes and are used in infant formulas and other dairy products. However, domestic analytical methods for assessing nucleotide content in products have not yet been established, and therefore, methods for determining nucleotide content are urgently required. A rapid and simple analytical method for determining the content of five types of nucleotides in dairy products was improved using solid phase extraction clean-up and high-performance liquid chromatography with diode array detector. The extraction solvent used in the AOAC method was not well dissolved and was changed to hydrophilic EDTA-Na. In addition, the results obtained using the isocratic elution method and a single wavelength were similar to those obtained using the AOAC method, and the time taken for analysis was shortened from 40 min to 25 min. The process of method validation revealed the following parameters: accuracy (84.69%-102.72%), precision (1.51%-6.82%), linearity (0.999), and limit of detection (cytidine 5'-monophosphate, 0.09 mg/L; uridine 5'-monophosphate, 0.11 mg/L; adenosine 5'-monophosphate, 0.12 mg/L; guanosine 5'-monophosphate, 0.11 mg/L; and inosine 5'-monophosphate, 0.14 mg/L). The method was also used to determine the nucleotide concentration in 25 samples (infant formulas, 1.99-29.39 mg/100 g; and cow milk, 0.28-0.83 mg/100 g). The newly improved method was appropriate for analyzing nucleotides in infant formulas and other dairy products faster when compared to conventional methods.

• 한국공간정보시스템학회:학술대회논문집
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• 한국공간정보시스템학회 2004년도 춘계 학술발표회 논문집 제1권1호(통권1호)
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• pp.89-95
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• 2004

The measured damping ratio was analysed to obtain amplitude dependence. Wind-induced vibration of 20 story steel-framed building was measured to investigate amplitude dependence by RD method. Micro-tremo vibrations of 20 RC bearing wall typed buildings were performed to analysis the amplitude dependence by formula proposed by Tamua and ESDU. Amplitude dependent damping in 17 story steel-framed building was showed clearly in the increasing rate of 9%. But Amplitude dependent damping of 17 RC bearing wall typed buildings was very low in the increasing rate of 2.5%. The tendency of dynamic properties of building obtained here are useful for the validation of dynamic properties of buildings in the evaluation of serviceability.

• 한국자동차공학회논문집
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• 제19권5호
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• pp.1-6
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• 2011

This paper proposes a new design method for electric scooter which can maximize the power efficiency at the given driving condition. The proposed method is designed with the electric and mechanical parameters and driving dynamics. These values are extracted from the dynamic and mathematical equations of the scooter. For validation, numerical simulation results are presented in this paper. As a result, the scooter achieved over 80% efficiency at 360 rpm at 1.42kw load. It is clear that the proposed method was verified through a 1.42kw numerical model.