• 정보처리학회논문지:컴퓨터 및 통신 시스템
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• 제5권9호
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• pp.275-284
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• 2016

원자력분야에서 사용되는 안전관련 소프트웨어는 계획단계부터 설치단계까지의 전 생명주기 공정을 통해 개발과 확인검증, 안전성 분석, 그리고 품질보증 활동을 수행해 소프트웨어의 안전성을 보장하고 있다. 그러나 이러한 개발과 검증공정을 통한 평가는 시간과 비용을 많이 필요로 한다. 또한, 소프트웨어의 품질을 향상시키기 위해 다양한 활동을 수행했다고 주장하지만, 어느 정도의 품질이 향상되었는지 확인하기에는 한계가 있다. 이러한 한계를 극복하기 위해서 정량적인 평가를 수행할 수 있는 소프트웨어 신뢰도 계산 방법을 제안한다. 특히, 소프트웨어가 사용하는 메모리 공간에 고장을 주입하여 소프트웨어의 고장을 모사하고, 주입된 고장에 가중치를 부여하여 고장 민감도에 차이를 두고, 감지능력을 평가하여 소프트웨어 고장율을 계산한다. 이러한 고장율을 활용하여 소프트웨어 신뢰도 계산을 수행하면 정량적인 평가결과를 획득할 수 있게 된다.

• Smart Structures and Systems
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• 제6권5_6호
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• pp.561-578
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• 2010

This study proposes a multi-level damage localization strategy to achieve an effective damage detection system for civil infrastructure systems based on wireless sensors. The proposed system is designed for use of distributed computation in a wireless sensor network (WSN). Modal identification is achieved using the frequency-domain decomposition (FDD) method and the peak-picking technique. The ASH (angle-between-string-and-horizon) and AS (axial strain) flexibility-based methods are employed for identifying and localizing damage. Fundamentally, the multi-level damage localization strategy does not activate all of the sensor nodes in the network at once. Instead, relatively few sensors are used to perform coarse-grained damage localization; if damage is detected, only those sensors in the potentially damaged regions are incrementally added to the network to perform finer-grained damage localization. In this way, many nodes are able to remain asleep for part or all of the multi-level interrogations, and thus the total energy cost is reduced considerably. In addition, a novel distributed computing strategy is also proposed to reduce the energy consumed in a sensor node, which distributes modal identification and damage detection tasks across a WSN and only allows small amount of useful intermediate results to be transmitted wirelessly. Computations are first performed on each leaf node independently, and the aggregated information is transmitted to one cluster head in each cluster. A second stage of computations are performed on each cluster head, and the identified operational deflection shapes and natural frequencies are transmitted to the base station of the WSN. The damage indicators are extracted at the base station. The proposed strategy yields a WSN-based SHM system which can effectively and automatically identify and localize damage, and is efficient in energy usage. The proposed strategy is validated using two illustrative numerical simulations and experimental validation is performed using a cantilevered beam.

• Biomedical Engineering Letters
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• 제8권4호
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• pp.399-404
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• 2018

The purpose of this study was to evaluate the accuracy of a mobile wireless digital automatic blood pressure monitor for clinical use and mobile health (mHealth). In this study, a manual sphygmomanometer and a digital blood pressure monitor were tested in 100 participants in a repetitive and sequential manner to measure blood pressure. The guidelines for measurement used the Korea Food & Drug Administration protocol, which reflects international standards, such as the American National Standard Institution/Association for the Advancement of Medical Instrumentation SP 10: 1992 and the British Hypertension Society protocol. Measurements were generally consistent across observers according to the measured mean ${\pm}SD$, which ranged in $0.1{\pm}2.6mmHg$ for systolic blood pressure (SBP) and $0.5{\pm}2.2mmHg$ for diastolic blood pressure (DBP). For the device and the observer, the difference in average blood pressure (mean${\pm}$SD) was $2.3{\pm}4.7mmHg$ for SBP and $2.0{\pm}4.2mmHg$ for DBP. The SBP and DBP measured in this study showed accurate measurements that satisfied all criteria, including an average difference that did not exceed 5 mmHg and a standard deviation that did not exceed 8 mmHg. The mobile wireless digital blood pressure monitor has the potential for clinical use and managing one's own health.

• Advances in concrete construction
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• 제10권6호
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• pp.479-488
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• 2020

The experimental and numerical works were carried out on high performance fiber reinforced concrete (HPFRC) with w/cm ratios ranging from 0.25 to 0.40, fiber volume fraction (Vf)=0-1.5% and 10% silica fume replacement. Improvements in compressive and flexural strengths obtained for HPFRC are moderate and significant, respectively, Empirical equations developed for the compressive strength and flexural strength of HPFRC as a function of fiber volume fraction. A relation between flexural strength and compressive strength of HPFRC with R=0.78 was developed. Due to the complex mix proportions and non-linear relationship between the mix proportions and properties, models with reliable predictive capabilities are not developed and also research on HPFRC was empirical. In this paper due to the inadequacy of present method, a back propagation-neural network (BP-NN) was employed to estimate the 28-day compressive strength of HPFRC mixes. BP-NN model was built to implement the highly non-linear relationship between the mix proportions and their properties. This paper describes the data sets collected, training of ANNs and comparison of the experimental results obtained for various mixtures. On statistical analyses of collected data, a multiple linear regression (MLR) model with R2=0.78 was developed for the prediction of compressive strength of HPFRC mixes, and average absolute error (AAE) obtained is 6.5%. On validation of the data sets by NNs, the error range was within 2% of the actual values. ANN model has given the significant degree of accuracy and reliability compared to the MLR model. ANN approach can be effectively used to estimate the 28-day compressive strength of fibrous concrete mixes and is practical.

• Journal of Cardiovascular Imaging
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• 제31권3호
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• pp.135-141
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• 2023

BACKGROUND: Global longitudinal strain (GLS) is an accurate and reproducible parameter of left ventricular (LV) systolic function which has shown meaningful prognostic value. Fast, user-friendly, and accurate tools are required for its widespread implementation. We aim to compare a novel web-based tool with two established algorithms for strain analysis and test its reproducibility. METHODS: Thirty echocardiographic datasets with focused LV acquisitions were analyzed using three different semi-automated endocardial GLS algorithms by two readers. Analyses were repeated by one reader for the purpose of intra-observer variability. CAAS Qardia (Pie Medical Imaging) was compared with 2DCPA and AutoLV (TomTec). RESULTS: Mean GLS values were -15.0 ± 3.5% from Qardia, -15.3 ± 4.0% from 2DCPA, and -15.2 ± 3.8% from AutoLV. Mean GLS between Qardia and 2DCPA were not statistically different (p = 0.359), with a bias of -0.3%, limits of agreement (LOA) of 3.7%, and an intraclass correlation coefficient (ICC) of 0.88. Mean GLS between Qardia and AutoLV were not statistically different (p = 0.637), with a bias of -0.2%, LOA of 3.4%, and an ICC of 0.89. The coefficient of variation (CV) for intra-observer variability was 4.4% for Qardia, 8.4% 2DCPA, and 7.7% AutoLV. The CV for inter-observer variability was 4.5%, 8.1%, and 8.0%, respectively. CONCLUSIONS: In echocardiographic datasets of good image quality analyzed at an independent core laboratory using a standardized annotation method, a novel web-based tool for GLS analysis showed consistent results when compared with two algorithms of an established platform. Moreover, inter- and intra-observer reproducibility results were excellent.

• 한국식품영양과학회지
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• 제45권11호
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• pp.1610-1616
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• 2016

섬쑥부쟁이로부터 고요산혈증 개선에 도움을 주는 기능성 식품 개발을 위하여 최적의 에탄올 추출물 탐색과 high performance liquid chromatography-ultraviolet(HPLC-UV) 분석방법에 의한 validation을 실시하였다. 지표성분으로 3,5-dicaffeoylquinic acid(3,5-DCQA)를 선정하여 표준화를 실시하였으며 검출법 확립을 위한 3,5-DCQA 정량분석은 Luna RP-18 칼럼($4.6{\times}250mm$, $5{\mu}m$)을 이용하여 1% 초산용액과 메탄올을 전개용매로 사용하였다. 용출은 1.0 mL/min의 유속으로 기울기 용출(gradient elution) 방법을 이용하였으며, 320 nm 파장에서 검출한 피크 면적을 이용하여 검량곡선을 작성하여 분석하였다. 본 연구에서 확립한 분석법으로 특이성, 직선성, 정밀성, 정확성, 회수율을 검색하였다. 3,5-DCQA의 검량선으로부터 상관계수($R^2$) 0.9999의 우수한 직선성과 intra-day와 inter-day 분석에서 90% 이상의 회수율과 5% 미만의 RSD를 나타내 정밀성과 정확성을 입증하였다. 검출한계는 $2.68{\mu}g/mL$였고 정량한계는 $8.11{\mu}g/mL$로 나타났다. 섬쑥부쟁이 에탄올 추출물(AGE)은 70과 $80^{\circ}C$에서 30, 50, 70, 80% 에탄올로 3, 4, 5, 6시간 동안 각각 추출하였으며, 지표물질의 검량곡선을 활용하여 각각의 AGE로부터 3,5-DCQA의 함량을 분석하였다. 본 시험법으로 분석한 3,5-DCQA의 함량은 $70^{\circ}C$에서 추출한 70% AGE가 $52.59{\pm}3.45mg/Aster$ glehni 100g의 함량을 나타내 가장 우수하게 나타났다. 그러나 섬쑥부쟁이 추출물에 함유된 5-caffeoylquinic acid(5-CQA)의 함량 비교분석은 에탄올 함량이나 추출 시간에 따른 함량 변화가 미미하게 나타났다. 또한, 다양한 AGE에 대하여 XOD 저해 효능을 검색하였을 때, 3,5-DCQA의 함량이 가장 높은 $70^{\circ}C$에서 추출한 70% AGE에서 우수한 효능을 나타내 기능성 원료 표준화를 위한 적합한 분석법임이 검증되었다. 따라서 본 연구를 통하여 확립된 3,5-DCQA의 분석법은 섬쑥부쟁이 에탄올 추출물로부터 개별인정형 건강기능식품 기능성 원료 개발을 위한 유용한 자료로 활용될 것으로 생각한다.

• Korean Journal of Radiology
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• 제24권5호
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• pp.395-405
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• 2023

Objective: This study aimed to develop and validate models using radiomics features on a native T1 map from cardiac magnetic resonance (CMR) to predict left ventricular reverse remodeling (LVRR) in patients with nonischemic dilated cardiomyopathy (NIDCM). Materials and Methods: Data from 274 patients with NIDCM who underwent CMR imaging with T1 mapping at Severance Hospital between April 2012 and December 2018 were retrospectively reviewed. Radiomic features were extracted from the native T1 maps. LVRR was determined using echocardiography performed ≥ 180 days after the CMR. The radiomics score was generated using the least absolute shrinkage and selection operator logistic regression models. Clinical, clinical + late gadolinium enhancement (LGE), clinical + radiomics, and clinical + LGE + radiomics models were built using a logistic regression method to predict LVRR. For internal validation of the result, bootstrap validation with 1000 resampling iterations was performed, and the optimism-corrected area under the receiver operating characteristic curve (AUC) with 95% confidence interval (CI) was computed. Model performance was compared using AUC with the DeLong test and bootstrap. Results: Among 274 patients, 123 (44.9%) were classified as LVRR-positive and 151 (55.1%) as LVRR-negative. The optimism-corrected AUC of the radiomics model in internal validation with bootstrapping was 0.753 (95% CI, 0.698-0.813). The clinical + radiomics model revealed a higher optimism-corrected AUC than that of the clinical + LGE model (0.794 vs. 0.716; difference, 0.078 [99% CI, 0.003-0.151]). The clinical + LGE + radiomics model significantly improved the prediction of LVRR compared with the clinical + LGE model (optimism-corrected AUC of 0.811 vs. 0.716; difference, 0.095 [99% CI, 0.022-0.139]). Conclusion: The radiomic characteristics extracted from a non-enhanced T1 map may improve the prediction of LVRR and offer added value over traditional LGE in patients with NIDCM. Additional external validation research is required.

• Nutrition Research and Practice
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• 제5권3호
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• pp.246-252
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• 2011

Bioelectrical impedance analysis (BIA) models must be validated against a reference method in a representative population sample before they can be accepted as accurate and applicable. The purpose of this study was to compare the eight-electrode BIA method with DEXA as a reference method in the assessment of body composition in Korean adults and to investigate the predictive accuracy and applicability of the eight-electrode BIA model. A total of 174 apparently healthy adults participated. The study was designed as a cross-sectional study. FM, %fat, and FFM were estimated by an eight-electrode BIA model and were measured by DEXA. Correlations between BIA_%fat and DEXA_%fat were 0.956 for men and 0.960 for women with a total error of 2.1%fat in men and 2.3%fat in women. The mean difference between BIA_%fat and DEXA_%fat was small but significant (P < 0.05), which resulted in an overestimation of $1.2{\pm}2.2$%fat (95% CI: -3.2-6.2%fat) in men and an underestimation of $-2.0{\pm}2.4$%fat (95% CI: -2.3-7.1%fat) in women. In the Bland-Altman analysis, the %fat of 86.3% of men was accurately estimated and the %fat of 66.0% of women was accurately estimated to within 3.5%fat. The BIA had good agreement for prediction of %fat in Korean adults. However, the eight-electrode BIA had small, but systemic, errors of %fat in the predictive accuracy for individual estimation. The total errors led to an overestimation of %fat in lean men and an underestimation of %fat in obese women.

• 정보관리학회지
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• 제40권1호
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• pp.1-21
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• 2023

본 연구는 텍스트 분류를 위한 효율적인 자질선정 방법으로 자질 순위화 기법의 성능을 구체적으로 검토하였다. 지금까지 자질 순위화 기법은 주로 문헌빈도에 기초한 경우가 대부분이며, 상대적으로 용어빈도를 사용한 경우는 많지 않았다. 따라서 텍스트 분류를 위한 자질선정 방법으로 용어빈도와 문헌빈도를 개별적으로 적용한 단일 순위화 기법들의 성능을 살펴본 다음, 양자를 함께 사용하는 조합 순위화 기법의 성능을 검토하였다. 구체적으로 두 개의 실험 문헌집단(Reuters-21578, 20NG)과 5개 분류기(SVM, NB, ROC, TRA, RNN)를 사용하는 환경에서 분류 실험을 진행하였고, 결과의 신뢰성 확보를 위해 5-fold cross validation과 t-test를 적용하였다. 결과적으로, 단일 순위화 기법으로는 문헌빈도 기반의 단일 순위화 기법(chi)이 전반적으로 좋은 성능을 보였다. 또한, 최고 성능의 단일 순위화 기법과 조합 순위화 기법 간에는 유의한 성능 차이가 없는 것으로 나타났다. 따라서 충분한 학습문헌을 확보할 수 있는 환경에서는 텍스트 분류의 자질선정 방법으로 문헌빈도 기반의 단일 순위화 기법(chi)을 사용하는 것이 보다 효율적이라 할 수 있다.

• 약학회지
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• 제49권3호
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• pp.225-229
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• 2005

A rapid, sensitive and selective tandem mass spectrometric method (LC-MS/MS) for the quantitation of nicorandil in human plasma was developed. A bioavailability study of Sigmat tablet (5 mg nicorandil, Choongwae Co.) was per-formed using the validated LC-MS/MS method. The dose of 5 fig of nicorandil (1 tablet) was orally administered to 9 healthy Korean subjects. After administration, blood was taken at 0.25, 0.5, 1, 2, 3, 4, 5, 6, 9, 12, and 24 hour. The validation data were as follows; the standard curve was linear ($r^2$=0.999) over the concentration range of $0.5\~200.0 ng/ml$. The coefficient of variation for intra- and inter-day assay were $3.55\~7.44$, and $2.17\~9.102\%$, respectively. The lower limit of quantification for nicorandil was 0.5 ng/ml. The pharmacokinetic parameters obtained were as follows; $AUC_t$ was 145.9$\pm$83.0 ng-hr/ml, Cmax was 83.8$\pm$32.2 ng/ml, $C_{max}$ was 0.42$\pm$0.13 hr, $K_e$ was 0.56$\pm$0.23 l/hr, and $t_{l/2}$ was 1.42$\pm$0.52 hr. Based on the validated analytical method and pharmacokinetic parameters, a standard guideline of the bioavailability test of nicorandil dos-age forms was prepared successfully and could be used for the bioequivalence test of nicorandil preparation.