• Smart Structures and Systems
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• v.1 no.1
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• pp.29-46
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• 2005

In this study, a wavelet packet based method is proposed for identifying damage occurrence and damage location for beam-like structures. This method assumes that the displacement or the acceleration response time histories at various locations along a beam-like structure both before and after damage are available for damage assessment. These responses are processed through a proper level of wavelet packet decomposition. The wavelet packet signature (WPS) that consists of wavelet packet component signal energies is calculated. The change of the WPS curvature between the baseline state and the current state is then used to identify the locations of possible damage in the structure. Two numerical studies, one on a 15-storey shear-beam building frame and another on a simply-supported steel beam, and an experimental study on a simply-supported reinforced concrete beam are performed to validate the proposed method. Results show the WPS curvature change can be used to locate both single and sparsely-distributed multiple damages that exist in the structure. Also the accuracy of assessment does not seem to be affected by the presence of 20-15dB measurement noise. One advantage of the proposed method is that it does not require any mathematical model for the structure being monitored and hence can potentially be used for practical application.

• Structural Engineering and Mechanics
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• v.61 no.6
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• pp.701-709
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• 2017

Seismic dissipation devices can play a crucial role in mitigating earthquake damages, loss of life and post-event repair and downtime costs. This research investigates the use of ring springs with high-force-to-volume (HF2V) dissipaters to create damage-free, recentring connections and structures. HF2V devices are passive rate-dependent extrusion-based devices with high energy absorption characteristics. Ring springs are passive energy dissipation devices with high self-centring capability to reduce the residual displacements. Dynamic behaviour of a system with nonlinear structural stiffness and supplemental hybrid damping via HF2V devices and ring spring dampers is used to investigate the design space and potential. HF2V devices are modelled with design forces equal to 5% and 10% of seismic weight and ring springs are modelled with loading stiffness values of 20% and 40% of initial structural stiffness and respective unloading stiffness of 7% and 14% of structural stiffness (equivalent to 35% of their loading stiffness). Using a suite of 20 design level earthquake ground motions, nonlinear response spectra for 8 different configurations are generated. Results show up to 50% reduction in peak displacements and greater than 80% reduction in residual displacements of augmented structure compared to the baseline structure. These gains come at a cost of a significant rise in the base shear values up to 200% mainly as a result of the force contributed by the supplemental devices.

• Journal of Multimedia Information System
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• v.4 no.4
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• pp.179-188
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• 2017

The Internet Video Coding (IVC) standard is due to be published by Moving Picture Experts Group (MPEG) for various Internet applications such as internet broadcast streaming. IVC aims at three things fundamentally: 1) forming IVC patents under a free of charge license, 2) reaching comparable compression performance to AVC/H.264 constrained Baseline Profile (cBP), and 3) maintaining computational complexity for feasible implementation of real-time encoding and decoding. MPEG experts have worked diligently on the intellectual property rights issues for IVC, and they reported that IVC already achieved the second goal (compression performance) and even showed comparable performance to even AVC/H.264 High Profile (HP). For the complexity issue, however, there has not been thorough analysis on IVC decoder. In this paper, we analyze the IVC decoder in view of the time complexity by evaluating running time. Through the experimental results, IVC is 3.6 times and 3.1 times more complex than AVC/H.264 cBP under constrained set (CS) 1 and CS2, respectively. Compared to AVC/H.264 HP, IVC is 2.8 times and 2.9 times slower in decoding time under CS1 and CS2, respectively. The most critical tool to be improved for lightweight IVC decoder is motion compensation process containing a resolution-adaptive interpolation filtering process.

• Journal of Astronomy and Space Sciences
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• v.26 no.1
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• pp.59-74
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• 2009

Relative navigation system is presented using GPS measurements from a single-channel global positioning system (GPS) simulator. The objective of this study is to provide the real-time inter-satellite relative positions as well as absolute positions for two formation flying satellites in low earth orbit. To improve the navigation performance, the absolute states are estimated using ion-free GRAPHIC (group and phase ionospheric correction) pseudo-ranges and the relative states are determined using double differential carrier-phase data and singled-differential C/A code data based on the extended Kalman filter and the unscented Kalman filter. Furthermore, pseudo-relative dynamic model and modified relative measurement model are developed. This modified EKF method prevents non-linearity of the measurement model from degrading precision by applying linearization about absolute navigation solutions not about the priori estimates. The LAMBDA method also has been used to improve the relative navigation performance by fixing ambiguities to integers for precise relative navigation. The software-based simulation has been performed and the steady state accuracies of 1 m and 6 mm ($1{\sigma}$ of 3-dimensional difference errors) are achieved for the absolute and relative navigation using EKF for a short baseline leader/follower formation. In addition, the navigation performances are compared for the EKF and the UKF for 10 hours simulation, and relative position errors are mm-level for the two filters showing the similar trends.

• Journal of Sensor Science and Technology
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• v.22 no.5
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• pp.338-345
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• 2013

Premature ventricular contractions are the most common of all arrhythmias and may cause more serious situation like ventricular fibrillation and ventricular tachycardia in some patients. Therefore, the detection of this arrhythmia becomes crucial in the early diagnosis and the prevention of possible life threatening cardiac diseases. Most methods for detecting arrhythmia require pp interval, or the diversity of P wave morphology, but they are difficult to detect the p wave signal because of various noise types. Thus, it is necessary to use noise-free R wave. So, the new approach for the detection of PVC is presented based on the rhythm analysis and the beat matching in this paper. For this purpose, we removed baseline wandering of low frequency band and made summed signals that are composed of two high frequency bands including the frequency component of QRS complex using the wavelet filter. And then we designed R wave detection algorithm using the adaptive threshold and window through RR interval. Also, we developed algorithm to classify PVC using RR interval. The performance of R wave and PVC detection is evaluated by using MIT-BIH arrhythmia database. The achieved scores indicate average detection rate of 99.76%, sensitivity of 99.30% and specificity of 98.66%; accuracy respectively for R wave and PVC detection.

• Journal of The Korea Institute of Healthcare Architecture
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• v.25 no.1
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• pp.51-60
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• 2019

Purpose: This study aims to analyze design guidelines for hospice facilities in the US, UK, and Canada focused on design considerations and space requirements, and utilizes them as baseline data for establishing standards for Korean hospice facilities. Methods: Comparative review was carried out to investigate hospice care models, design consideration, and room sizes and requirements for design guideline of hospice facilities in United States, UK and Canada identified on electronic database and review articles, and to examine major characteristics and tendencies of hospice facilities. Results: The hospice care models characteristics in design guidelines is generally largely divided into hospital-based hospice facility, Nursing home-based hospice facility, and daycare hospice. The design considerations in hospice facilities focused on medical efficiency, flexibility, barrier-free environment, person-centered care, and stability. There is also a need for single resident room, rooms for the patient's family, and isolation room for infection control. Implications: it is recommended to establish standards for the installation and operation of required and recommended rooms and considerations when establishing the standards of hospice facilities in Korea. This Study is limited to a simple comparative analysis of the framework of guideline.

• Structural Monitoring and Maintenance
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• v.9 no.3
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• pp.237-258
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• 2022

This paper studies detecting and locating loose bolts using nonlinear guided waves. The 3D Finite Element (FE) simulation is used for the prediction of guided waves' interactions with loose bolted joints. The numerical results are verified by experimentally obtained data. The study considers bolted joints consisting of two bolts. It is shown that the guided waves' interaction with surfaces of a loose bolted joint generates Contact Acoustic Nonlinearity (CAN). The study uses CAN for detecting and locating loose bolts. The processed experimentally obtained data show that the CAN is able to successfully detect and locate loose bolted joints. A 3D FE simulation scheme is developed and validated by experimentally obtained data. It is shown that FE can predict the propagation of guided waves in loose bolts and is also able to detect and locate them. Several numerical case studies with various bolt sizes are created and studied using the validated 3D FE simulation approach. It is shown that the FE simulation modeling approach and the signal processing scheme used in the current study are able to detect and locate the loose bolts in imperfect bolted joints. The outcomes of this research can provide better insights into understanding the interaction of guided waves with loose bolts. The results can also enhance the maintenance and repair of imperfect joints using the nonlinear guided waves technique.

• Journal of Medicine and Life Science
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• v.19 no.1
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• pp.14-19
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• 2022

We investigated the safety and efficacy of pemetrexed monotherapy in patients with lung adenocarcinoma and various renal conditions, including chronic kidney disease. We also analyzed whether baseline renal function affected progression-free survival (PFS). We retrospectively analyzed 71 patients who received maintenance-and second-line pemetrexed monotherapy. Patients were divided into two groups according to estimated glomerular filtration rate (eGFR): fair eGFR (>60 mL/min/1.73 m²) and lower eGFR (59 mL/min/1.73 m² or less). The safety and efficacy were evaluated for each group. Median ages were 73.2 years in the lower eGFR group (n=28) and 64.5 years in the fair eGFR group (n=43). Patients with a lower eGFR achieved a median PFS of 4.7 months, while the median PFS for patients with a fair eGFR was 2.7 months. The difference between the two groups was not statistically significant (P=0.075). Both groups showed treatment-related low-grade hematological and non-hematological adverse events. Pemetrexed monotherapy is safe and effective in patients with lung adenocarcinoma with a lower eGFR.

• Structural Engineering and Mechanics
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• v.88 no.1
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• pp.83-94
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• 2023

An accurate and highly efficient inverse element labelled iPCB is developed based on the inverse finite element method (iFEM) for real-time shape estimation of plane-curved structures (such as arch bridges) utilizing onboard strain data. This inverse problem, named shape sensing, is vital for the design of smart structures and structural health monitoring (SHM) procedures. The iPCB formulation is defined based on a least-squares variational principle that employs curved Timoshenko beam theory as its baseline. The accurate strain-displacement relationship considering tension-bending coupling is used to establish theoretical and measured section strains. The displacement fields of the isoparametric element iPCB are interpolated utilizing nonuniform rational B-spline (NURBS) basis functions, enabling exact geometric modelling even with a very coarse mesh density. The present formulation is completely free from membrane and shear locking. Numerical validation examples for different curved structures subjected to different loading conditions have been performed and have demonstrated the excellent prediction capability of iPCBs. The present formulation has also been shown to be practical and robust since relatively accurate predictions can be obtained even omitting the shear deformation contributions and considering polluted strain measures. The current element offers a promising tool for real-time shape estimation of plane-curved structures.

• Journal of Preventive Medicine and Public Health
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• v.33 no.2
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• pp.199-207
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• 2000

Objectives : This study was peformed to identify the risk factors related to the development of hypertension in a rural area. Method : Total of 3,573 subjects in Chung-Song County were interviewed and examined in 1996. The study cohort comprised 2,580 hypertension-free subjects aged above 20. One-year follow up was completed for 1,781 subjects(69.0%) in 1997. General characteristics(age, gender, education level, economic status, marital status), the family history of hypertension, diet, alcohol, smoking, coffee, stress, past history of oral contraceptive and menopausal status in female, height, weight, waist and hip circumference, baseline blood pressure, and serum total cholesterol were considered as risk factors. Results : Multivariate analysis using logistic regression model indicated that age(RH=1.50, 95% CI; 1.15-1.96), the family history of hypertension(RR=2.11, 95% CI; 1.04-4.26), waist-hip ratio(WHR) (RR=2.09, 95%, CI; 1.15-3.79), and baseline systolic blood pressure(130-139/<120mmHg)(RR=3.34, 95% CI; 1.47-7.60) were significant risk factors associated with the development of hypertension above the borderline level in male. In female, age(RR=1.06, 95% CI; 1.03-1.09), change in menopausal status$(no{\rightarrow}yes/no{\rightarrow}no)$ (RR=3.32, 95% CI; 1.01-10.87), baseline systolic blood pressure(120-129/<120mmHg: RR=2.00, 95% CI; 1.02-3.90)(130-139/<120mmHg: RR=2.64, 95% CI; 1.34-5.20) and baseline diastolic blood pressure(85-89/<80mmHg)(RR=4.09, 95% CI; 1.86-8.96) were identified as risk factors. Conclusions : Age and high normal blood pressure were significant risk factors for the development of hypertension above the borderline level. In addition, the family history of hypertension and WHR in men, and the change of menopausal status in women might be significant risk factors in Korea.