• Structural Engineering and Mechanics
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• 제77권2호
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• pp.179-196
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• 2021

Experimental investigations on the seismic behaviors of the PVC-FRP Confined Reinforced Concrete (PFCRC) columns under low cyclic loading are carried out and two variable parameters including CFRP strips spacing and axial compression ratio are considered. The PFCRC column finally fails by bending and is characterized by the crushing of concrete and yielding of the longitudinal reinforcement, and the column with a high axial compression ratio is also accompanied by the cracking of the PVC tube and the fracture of CFRP strips. The hysteretic curves and skeleton curves of the columns are obtained from the experimental data. With the increase of axial compression ratio, the stiffness degradation rate accelerates and the ductility decreases. With the decrease of CFRP strips spacing, the unloading sections of the skeleton curves become steep and the ductility reduces significantly. On the basis of fiber model method, a numerical analysis approach for predicting the skeleton curves of the PFCRC columns is developed. Additionally, a simplified skeleton curve including the elastic stage, strengthening stage and unloading stage is suggested depending on the geometric drawing method. Moreover, the loading and unloading rules of the PFCRC columns are revealed by analyzing the features of the skeleton curves. The quantitative expressions that are used to predict the unloading stiffness of the specimens in each stage are proposed. Eventually, an analytical model for the PFCRC columns under low cyclic loading is established and it agrees well with test data.

• Physical Therapy Rehabilitation Science
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• 제10권1호
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• pp.22-31
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• 2021

Objective: This review aims to analyze the effects of electromechanically assisted walking in patients with cerebral palsy(CP). Design: A systematic review and meta-analysis. Methods: We reviewed systematically using the PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) checklist guidelines. The inclusion criteria for this study were all CP patients. The intervention was electromechanically assisted walking. The outcome measures included gait parameters, function, spasticity. Studies excluded from this review were excluded from the review if they were non-English languages and if the study was not published as a full report, and if they were not randomized controlled trials (RCTs) designs. The RevMan 5.4 program was used to evaluate and explain the results. The risk of bias was evaluated independently by two reviewers. The quantitative meta-analysis, including mean differences (MD) and associated standard deviations (SD) from baseline and follow-up assessments, were recorded. Results: A total of 634 articles were searched. Two hundred eighty-nine duplicate articles were excluded, and 345 of 634 originals were left for selection. Of these 74 papers, 44 were out of topic, and 19 reported no mean or standard deviation values. And one was a non-experimental study. Finally, ten studies were included. All 10 RCTs of electromechanically assisted walking were analyzed. The meta-analysis showed a significant improvement in gait cycle (95% CI (confidence intervals), 0.09 to 0.19, I2=0%), Gross Motor Function Measure (GMFM) D (95% CI, 3.27 to 13.17, I2=0%) and GMFM E (95% CI, 0.22 to 6.41, I2=0%). Conclusions: Electromechanically assisted training helps in walking in patients with CP.

• Journal of Astronomy and Space Sciences
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• 제38권4호
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• pp.237-250
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• 2021

A rover is a planetary surface exploration device designed to move across the ground on a planet or a planetary-like body. Exploration rovers are increasingly becoming a vital part of the search for scientific evidence and discoveries on a planetary satellite of the Sun, such as the Moon or Mars. Reliable behavior and predictable locomotion of a rover is important. Understanding soil behavior and its interaction with rover wheels-the terramechanics-is of great importance in rover exploration performance. Up to now, many researchers have adopted Bekker's semiempirical model to predict rover wheelsoil interaction, which is based on the assumption that soil is deformable when a pressure is applied to it. Despite this basic assumption of the model, the pressure-sinkage relation is not fully understood, and it continues to present challenges for rover designers. This article presents a new pressure-sinkage model based on dimensional analysis (DA) and results of bevameter tests. DA was applied to the test results in order to propose a new pressure-sinkage model by reducing physical quantitative parameters. As part of the work, a new bevameter was designed and built so that it could be successfully used to obtain a proper pressure-sinkage relation of Korean Lunar Soil Simulant (KLS-1). The new pressure-sinkage model was constructed by using three different sizes of flat plate diameters of the bevameter. The newly proposed model was compared successfully with other models for validation purposes.

• Earthquakes and Structures
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• 제20권4호
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• pp.365-375
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• 2021

Rammed earth (RE) buildings have existed all over the world for thousands of years, and have gained increasing attention because of its sustainable advantages, however, the shrinkage cracks reduce its bearing capacity and seriously affect its durability and applicability. In this study, the shrinkage cracks test was carried out to investigate the effects of initial water content, proportion of sand and gravel, compaction degree, thickness and the additives (polypropylene fiber, cement and sodium silicate) of shrinkage cracks in RE buildings, ten groups of RE samples were prepared and dried outdoors to crack. Four quantitative parameters of geometrical structure of crack patterns were used to evaluate the development of cracks. The results show that the specimens cracking behavior and the geometrical structure of crack patterns are significantly influenced by these considered factors. The formation of crack can be accelerated with the increase of initial water content and thickness of specimen, while restricted with the increase of the compaction degree and the proportion of sand and gravel. Moreover, the addition of 1% polypropylene fiber, 10% cement and 0.5 volume ratio sodium silicate can significantly restrain the form and development of cracks. In RE construction, these factors should be considered comprehensively to prevent the harm caused by shrinkage cracks. Further works should be carried out to obtain the optimum dosage of the additives, which can benefit the construction of RE buildings in future.

• Journal of Applied Biological Chemistry
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• 제65권3호
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• pp.195-202
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• 2022

콩잎의 기능성식품소재연구가 활발히 진행되고 있지만 기능성 식품소재로서 콩잎을 관리할 수 있는 밸리데이션 방법은 제시되지 않고있다. 본 연구에서는 콩잎에서 7개의 kaempferol 유도체를 UHPLC-ESI-Q-TOF-MS로 동정하고 이들 중 camelliaside A를 지표물질로 선정하였다. 콩잎열수추출물에서 camelliaside A를 정량할 수 있는 HPLC-UVD 밸리데이션 방법을 식품의약품안전처의 건강기능성식품에 대한 가이드라인에 따라 구축하였다. 개발된 HPLC-UVD 밸리데이션 방법은 특이성, 정확도, 일내정밀도, 일간정밀도, 검출한계, 정량한계 및 직선성에서 가이드라인을 만족하는 결과값으로 검증되었다. 또한 camelliaside A 분석법을 콩잎열수추출물에 적용하여 적합한 수준의 평가값을 얻었다.

• 대한의용생체공학회:의공학회지
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• 제42권6호
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• pp.251-258
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• 2021

Hyaluronic acid (HA) microspheres (MSs) crosslinked with polyethylene glycol diglycidyl ether (PEGDE) are prepared using a simple fluidic device (SFD) to investigate the optimized parameters. A solution mixture of PEGDE in 2-methyl-1-propanol was prepared as a continuous phase in SFD. HA solutions of 1 wt% concentration were introduced into SFD as a discontinuous phase. The HA solution prepared by stirring for more than 48 h exhibited spherical MSs at the needle tip inside the ring cap. As the flow rate of the continuous phase increased from 0.7 to 1.9 mL/min, the diameter of the MS decreased from 173±36 ㎛ to 129±13 ㎛. Although the PEGDE concentration in the range of 0.2 to 1.8 vol% did not affect the diameter of the MS, the microstructure of MS, consisting of inner hollow void and wall, was changed. The inner void and wall size decreased and increased from 79.5 ㎛ to 57.2 ㎛ and from 10.3 ㎛ to 21.4 ㎛, respectively, with increasing PEGDE concentration from 0.2 vol% to 1.8 vol%. FT-IR peaks located around 2867 cm^-1 and 1088 cm^-1 indicated that the HA MS prepared at different PEGDE concentrations were chemically crosslinked. The HA MSs containing different PEGDE concentrations exhibited quantitative cell viability of more than 98%. L-929 cells adhered well to the HA MSs and proliferated continuously with increasing culture time to 48 h regardless of PEGDE concentration, implying that the HA MSs are clinically safe and effective.

• 한국구조물진단유지관리공학회 논문집
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• 제27권1호
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• pp.86-94
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• 2023

본 연구에서는 강재 슬릿댐퍼를 대상으로 하여 면외 변형을 구속할 수 있는 보완상세를 제시하고, 제안상세 적용 유무와 댐퍼의 형상비를 변수로 하여 일정진폭 가력실험을 수행하였다. 실험결과에 따라 제안상세가 적용된 슬릿댐퍼의 반복이력은 설정된 변수 범위에서 모두 안정적인 방추형의 이력거동을 나타내었으며 종국거동까지 댐퍼의 면외변형은 관찰되지 않았다. 누적변형각 분석을 통해 제안상세가 적용된 댐퍼 시스템은 대조군에 비해 월등히 큰 소성변형능력을 확보할 수 있음을 확인하였다. 이러한 구조적 효과(구속패널효과)는 슬릿댐퍼의 형상비가 작을수록 크게 나타났다. 관련 국외기준을 참고하여 제안상세 적용유무에 따른 슬릿댐퍼의 피로곡선을 작성하고 예측곡선 제시를 위한 매개변수를 도출하였다. 본 연구의 결과를 토대로 향 후 다양한 종류의 제진장치의 구조성능에 대한 정량적인 비교가 가능할 것으로 판단된다.

• 스마트미디어저널
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• 제12권7호
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• pp.18-26
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• 2023

본 연구에서는 YOLOX와 OC-SORT를 기반으로 한 소 행동 인식시스템을 제시하였다. YOLOX는 실시간으로 목표를 감지하고 소의 위치와 행동 정보를 제공한다. OC-SORT 모듈은 비디오에서 소를 추적하고 고유 ID를 할당하는 역할을 한다. 양적 분석 모듈은 소의 행동과 위치 정보를 분석한다. 실험 결과, 우리의 시스템은 목표 감지와 추적에서 높은 정확도와 정밀도를 보여주었다. YOLOX의 평균 정확도(AP)는 82.2%, 평균 재현율(AR)는 85.5%, 매개변수 양은 54.15M, 계산량은 194.16GFLOP이었다. OC-SORT는 복잡한 환경과 가림막 상황에서도 높은 정밀도의 실시간 목표 추적을 유지할 수 있었다. 소의 운동 변화와 승가행동의 빈도를 분석함으로써, 제안 시스템은 소의 발정 행동을 더 정확하게 판별하는데 도움을 줄 수 있다.

• 한국수자원학회:학술대회논문집
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• 한국수자원학회 2023년도 학술발표회
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• pp.374-374
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• 2023

Groundwater is the main source of water on which relies many countries in case of emergency, this is the case of Japan in 2011 after the great Sendai Earthquake. This important resource is found to be heavily influenced by human induced factors such as wetland area reduction. For groundwater sustainable management in perfect cohesion with wetland it is important to understand the relationship between both resources. Wetlands have a strong interaction with both groundwater and surface water, influencing catchment hydrology and water quality. Quantifying groundwater-wetland interactions can help better identify locations for wetlands restoration and/or protection. This study uses observation data from piezometers and wetland to study the qualitative and quantitative aspects of the correlation. Groundwater level, wetland area, chemical, organic and inorganic contaminants are the important parameters used. the results proved that few contaminants in the wetland are found in groundwater and in general the wetland quality does not affect that much groundwater quality. The strong linear relationship found between wetland water level and nearest groundwater level proved that, in term of quantity, groundwater and wetland are strongly correlated. While wetland becoming dry, groundwater level has dropped in the region about 0.52m. The area of wetland was found to be lightly correlated with groundwater level, proving that wetlands dry has contributed to groundwater level declining. This study has showed that whilst rainfall variability contributed to the decline and loss of wetlands, the impacts from landuse changes and groundwater extraction were likely to be significant contributors to the observed losses.

• Clinics in Shoulder and Elbow
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• 제26권1호
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• pp.10-19
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• 2023

Background: Tendon degeneration contributes to rotator cuff tears; however, its role in postoperative structural integrity is poorly understood. The purpose of this study was to investigate the factors associated with postoperative structural integrity after rotator cuff repair, particularly focusing on the histology of tendons harvested intraoperatively. Methods: A total of 56 patients who underwent primary arthroscopic rotator cuff repair between 2009 and 2011 were analyzed. A 3-mm-diameter sample of supraspinatus tendons was harvested en bloc from each patient after minimal debridement of the torn ends. Tendon degeneration was assessed using seven histological parameters on a semi-quantitative grading scale, and the total degeneration score was calculated. One-year postoperative magnetic resonance imaging was used to classify the patients based on retear. Results: The total degeneration scores in the healed and retear groups were 13.93±2.03 and 14.08±2.23 (P=0.960), respectively. Arthroscopically measured anteroposterior (AP) tear sizes in the healed and retear groups were 24.30±12.35 mm and 36.42±25.23 mm (P=0.026), respectively. Preoperative visual analog scale pain scores at rest in the healed and retear groups were 3.54±2.37 and 5.16±2.16 (P=0.046), respectively. Retraction sizes in the healed and retear groups were 16.02±7.587 mm and 22.33±13.364 mm (P=0.037), respectively. The odds of retear rose by 4.2% for every 1-mm increase in AP tear size (P=0.032). Conclusions: The postoperative structural integrity of the rotator cuff tendon was not affected by tendon degeneration, whereas the arthroscopically measured AP tear size of the rotator cuff tendon was an independent predictor of retear. Level of evidence: III.