• Physical Therapy Korea
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• v.30 no.2
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• pp.128-135
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• 2023

Background: Despite the fact that aquatic exercise is one of the most popular alternative treatment methods for children with cerebral palsy (CP), there are few research regarding its effectiveness. Objects: The purpose of this study was to examine the effects of aquatic exercise on upper extremity function and postural control during reaching in children with CP. Methods: Ten participants (eight males and two females; 4-10 years; Gross Motor Function Classification System levels II-IV) with spastic diplegia were recruited to this study. The aquatic exercise program consisted of four modified movements that were selected from the Halliwick 10-point program to enhance upper extremity and trunk movements. The participants attended treatment two times a week for 6 weeks, averaging 35 minutes each session. The Box and Block Test (BBT), transferring pennies in the Bruininks-Oseretsky Test (BOT), and pediatric reaching test (PRT) scores were used as clinical measures. Three-dimensional motion analysis system was used to collect and analyze kinematic data. Differences in BBT and BOT values among pre-treatment, post-treatment, and retention (after 3 weeks) were analyzed using a Friedman test. In addition, the PRT scores and variables (movement time, hand velocity, straightness ratio, and number of movement units) from the three-dimensional motion analysis were tested using a Wilcoxon signed-rank test. The significance level was established at p < 0.05. When the results appeared to be statistically significant, a post-hoc test for multiple comparisons was performed with the Wilcoxon signed-rank test. Results: All clinical measures, which included BBT, transferring pennies of BOT, and PRT, were significantly increased between pre-intervention and post-intervention scores and between pre-intervention and retention scores after treatment (p = 0.001). Three-dimensional motion analysis mostly were significantly improved after treatment (p = 0.001). Conclusion: Aquatic exercise may help to improve body function, activity, and participation in children with varying types of physical disabilities.

• Journal of Naturopathy
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• v.7 no.1
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• pp.1-9
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• 2018

The purpose of this study is to statistically investigate the changes in mean differences of the vascular age types and index, heart beating, vessel elasticity, diastolic reserves contents measured by the fingertip plethysmogram before and after the subjects (49 people) visit the Gotjawal forest for two hours. While there is no significant change in the mean differences of vascular age types and index, heart beating, diastolic reserves contents in the control group before and after the visit, the differences in the test groups gets higher than the control group and shows a significant difference. Moreover, the variance analyses of the mean values of the contents shows a significant change after the visit. There is no significant change in the values of vessel elasticity changes between the groups after the visit, but the change of values is significant in the within group, and it is not significant between group by variance analysis. The differences of the heart beating was insignificant in the within group, but significant between group after the visit. In conclusion this study proves the effects of forest bathing, because the HRV index significantly improved after the bathing. Therefore the b-c-d-e/a ratio may be useful for evaluation of HRV.

• Clean Technology
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• v.29 no.4
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• pp.327-332
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• 2023

This study investigated synthesis gas production via steam reforming of biogas. Ni-Al₂O₃ and Ni-CeO₂ catalysts were synthesized using the co-precipitation method, with controlled precipitation agent injection rates. Catalytic performances were tested at various temperatures, with a gas composition ratio of CH₄:CO₂:H₂O = 1:0.67:3 and a gas hourly space velocity (GHSV) of 647,000 mL h^-1 gcat^-1. The rate of precipitation agent injection influenced the characteristics of the catalysts depending on the type of support used. As the temperature increased, both the CO₂ reforming of methane and the reverse water gas shift reactions occurred. The Ni-Al₂O₃ catalyst, synthesized with a single injection of the precipitation agent, exhibited the best catalytic activity under conditions with sufficient steam supply among the prepared catalysts, due to its high Ni dispersion.

• Clean Technology
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• v.29 no.4
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• pp.313-320
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• 2023

In order to increase the usability of H₂-SCR, the NOx removal characteristics with catalyst powder of PtNi/CeO₂-W-TiO₂ using Ce as a co-catalyst was synthesized and coated on a porous metal structure (PMS) were evaluated. Catalyst powder of PtNi/CeO₂-W-TiO₂(PtNi nanoparticles onto W-TiO₂, with the incorporation of ceria (CeO₂) as a co-catalysts) was synthesized and coated onto a porous metal structure (PMS) to produce a Selective Catalytic Reduction (SCR) catalyst. H₂-SCR with CeO₂ as a co-catalyst exhibited higher NOx removal efficiency compared to H₂-SCR without CeO₂. Particularly, at a 10wt% CeO₂ loading ratio, the NOx removal efficiency was highest at 90℃. As the amount of catalyst coating on PMS increased, the NOx removal efficiency was improved below 90℃, but it was decreased above 120℃. When the space velocity was changed from 4,000 h^-1 to 20,000 h^-1, the NOx removal efficiency improved at temperatures above 120℃. It was expected that the use of the catalyst could be reduced by applying the PMS with excellent specific surface area as a support.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.43 no.6
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• pp.735-747
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• 2023

In recent times, the sharp increase in extreme flood damages due to climate change has posed a challenge to effectively address flood-related issues solely relying on conventional flood management infrastructure. In response to this problem, this study aims to consider the effectiveness of nature-based flood management approaches, specifically levee retreat and relocation. To achieve this, we utilized a 1D numerical model, HEC-RAS, to analyze the flood reduction effects concerning floodwater levels, flow velocities, and time-dependent responses to a 100-year frequency flood event. The analysis results revealed that the effect of creating a flood buffer zone of the nature-based solution extends from upstream to downstream, reducing flood water levels by up to 30 cm. The selection of the flow roughness coefficient in consideration of the nature-based flood buffer space creation characteristics should be based on precise criteria and scientific evidence because it is sensitive to the flood control effect analysis results. Notably, floodwater levels increased in some expanded floodplain sections, and the reduction in flow velocities varied depending on the ratio of the expanded cross-sectional area. In conclusion, levee retreat and floodplain expansion are viable nature-based alternatives for effective flood management. However, a comprehensive design approach is essential considering flood control effects, flow velocity reduction, and the timing of peak water levels. This study offers insights into addressing the challenges of climate-induced extreme flooding and advancing flood management strategies.

• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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• v.13 no.4
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• pp.320-324
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• 2008

In order to identify the change of tidal characteristics on average in the Asan Bay due to the construction of the Hwaong (Namyang Bay) tidal barrier (HTB), the tide data at Pyongtack (PT) and Anheung (AH) for the periods from 1993 to 2006 were analyzed using the harmonic analysis method, and major and shallow water tidal constituents were compared. The semidiurnal tidal amplitudes at PT increased while those at AH decreased after the tidal barrier construction. In particular, the amplitudes at PT increased abruptly during the period of $2002{\sim}2003$ when HTB was completed. On the other hand, the amplitudes of the diurnal tides at PT and AH showed minimal change. This suggests that the tidal characteristics change in the Asan Bay may be related to the construction of HTB. The cause of this change is different from either blocking the tidal wave propagation by the Keum River tidal barrier or removing 'choking effect' by the Yeongsan River tidal barrier. The $M_4/M_2$ ratio increased and their phase difference decreased after the completion of HTB. Accordingly, these changes may result in increase of tidal range, decrease of the flood duration and increase of the flood current velocity, inducing more sediments into the Asan Bay.

• Korean Journal of Radiology
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• v.24 no.7
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• pp.647-659
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• 2023

Objective: The study was conducted to investigate the effect of correct occlusion of the left atrial appendage (LAA) on intracardiac blood flow and thrombus formation in patients with atrial fibrillation (AF) using four-dimensional (4D) flow magnetic resonance imaging (MRI) and three-dimensional (3D)-printed phantoms. Materials and Methods: Three life-sized 3D-printed left atrium (LA) phantoms, including a pre-occlusion (i.e., before the occlusion procedure) model and correctly and incorrectly occluded post-procedural models, were constructed based on cardiac computed tomography images from an 86-year-old male with long-standing persistent AF. A custom-made closed-loop flow circuit was set up, and pulsatile simulated pulmonary venous flow was delivered by a pump. 4D flow MRI was performed using a 3T scanner, and the images were analyzed using MATLAB-based software (R2020b; Mathworks). Flow metrics associated with blood stasis and thrombogenicity, such as the volume of stasis defined by the velocity threshold ($\left|\vec{V}\right|$ < 3 cm/s), surface-and-time-averaged wall shear stress (WSS), and endothelial cell activation potential (ECAP), were analyzed and compared among the three LA phantom models. Results: Different spatial distributions, orientations, and magnitudes of LA flow were directly visualized within the three LA phantoms using 4D flow MRI. The time-averaged volume and its ratio to the corresponding entire volume of LA flow stasis were consistently reduced in the correctly occluded model (70.82 mL and 39.0%, respectively), followed by the incorrectly occluded (73.17 mL and 39.0%, respectively) and pre-occlusion (79.11 mL and 39.7%, respectively) models. The surfaceand-time-averaged WSS and ECAP were also lowest in the correctly occluded model (0.048 Pa and 4.004 Pa^-1, respectively), followed by the incorrectly occluded (0.059 Pa and 4.792 Pa^-1, respectively) and pre-occlusion (0.072 Pa and 5.861 Pa^-1, respectively) models. Conclusion: These findings suggest that a correctly occluded LAA leads to the greatest reduction in LA flow stasis and thrombogenicity, presenting a tentative procedural goal to maximize clinical benefits in patients with AF.

• Korean Circulation Journal
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• v.53 no.11
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• pp.744-755
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• 2023

Background and Objectives: Aortic valve replacement (AVR) is considered a class I indication for symptomatic severe aortic stenosis (AS). However, there is little evidence regarding the potential benefits of early AVR in symptomatic patients diagnosed with normal-flow, low-gradient (NFLG) severe AS. Methods: Two-hundred eighty-one patients diagnosed with symptomatic NFLG severe AS (stroke volume index ≥35 mL/m², mean transaortic pressure gradient <40 mmHg, peak transaortic velocity <4 m/s, and aortic valve area <1.0 cm²) between January 2010 and December 2020 were included in this retrospective study. After performing 1:1 propensity score matching, 121 patients aged 75.1±9.8 years (including 63 women) who underwent early AVR within 3 months after index echocardiography, were compared with 121 patients who received conservative care. The primary outcome was a composite of all-cause death and heart failure (HF) hospitalization. Results: During a median follow-up of 21.9 months, 48 primary outcomes (18 in the early AVR group and 30 in the conservative care group) occurred. The early AVR group demonstrated a significantly lower incidence of primary outcomes (hazard ratio [HR], 0.52; 95% confidence interval [CI], 0.29-0.93; p=0.028); specifically, there was no significant difference in all-cause death (HR, 0.51; 95% CI, 0.23-1.16; p=0.110), although the early AVR group showed a significantly lower incidence of hospitalization for HF (HR, 0.43; 95% CI, 0.19-0.95, p=0.037). Subgroup analyses supported the main findings. Conclusions: An early AVR strategy may be beneficial in reducing the risk of a composite outcome of death or hospitalization for HF in symptomatic patients with NFLG severe AS. Future randomized studies are required to validate and confirm our findings.

• Journal of the Korea institute for structural maintenance and inspection
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• v.13 no.2 s.54
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• pp.172-180
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• 2009

Normally in order to build a semi-active control system equipped with MR damper, the dynamic modeling of the damper is required to numerically predict its dynamic damping force and also its behavioral characteristics. For the dynamic modeling of the MR damper, this paper attempts to predict and evaluate its dynamic behavior by applying specifically both a power model and a Bingham model. Dynamic loading tests were performed on the squeeze type of damper specially designed for this research, and force-displacement hysteresis loops confirmed the effectiveness of the damper as a semi-active control device. In the meantime, in order to evaluate the effectiveness of each model applied, the model parameter for each model was identified. On the basis of the parameter, we derived the error ratio of the force-velocity relationship curve and the dynamic damping force, which was contrasted and compared with the experimental results of the squeeze type of damper. Finally, the squeeze type of MR damper developed in this research was proved to be valid as a semi-active control device, and also the evaluation of the two dynamic models showed they were working fine so that they were likely to be easily utilized to numerically predict the dynamic characteristics of any dampers with MR fluid as well as the squeeze type of MR damper.

• Clean Technology
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• v.25 no.4
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• pp.316-323
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• 2019

In order to enhance combustion efficiency and reduce atmosphere pollutants, it is essential to measure carbon monoxide (CO) concentration precisely in combustion exhaust. CO is the important gas species regarding pollutant emission and incomplete combustion because it can trade off with NOx and increase rapidly when incomplete combustion occurs. In the case of a steel annealing system, CO is generated intentionally to maintain the deoxidation atmosphere. However, it is difficult to measure the CO concentration in a combustion environment in real-time, because of unsteady combustion reactions and harsh environment. Tunable Diode Laser Absorption Spectroscopy (TDLAS), which is an optical measurement method, is highly attractive for measuring the concentration of certain gas species, temperature, velocity, and pressure in a combustion environment. TDLAS has several advantages such as sensitive, non-invasive, and fast response, and in-situ measurement capability. In this study, a combustion system is designed to control the equivalence ratio. Also, the combustion exhaust gases are produced in a Liquefied Petroleum Gas (LPG)/air flame. Measurement of CO concentration according to the change of equivalence ratio is confirmed through TDLAS method and compared with the simulation based on Voigt function. In order to measure the CO concentration without interference from other combustion products, a near-infrared laser at 4300.6 cm^-1 was selected.