• Biotechnology and Bioprocess Engineering:BBE
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• 제9권6호
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• pp.495-499
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• 2004

The analyses of peak shapes in chromatography are useful in operating chroma­tographic system. The asymmetry and sharpness of a chromatographic peak are estimated by the reversed-phase adsorption of two standard peptides (angiotensin II bradykinin) on $C_{18}$ In this work, the average particle diameters of $C_{18}$ were 5 and 15 $\mu$m, while the pore sizes were 100 and 300 A. The composition of the mobile phase was $50/50\;vol.\;{\%}$ of a binary mixture of acetonitrile and water with $0.1\%$ TFA, and the particles were packed in a stainless column ($4.6{\times}150$ mm). The third and the fourth central movement were calculated from the chromatographic elution curves by moment analysis. The peak asymmetry was determined by two theoretical calculations: the asymmetry factor by elution peak analysis and skewness with moment analysis. The sharpness was estimated by the fourth central moment. In this work, the most acceptable skewness was calculated when the pore size was 300 A. The large excess was observed on small pore size.

• 한국운동역학회지
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• 제18권2호
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• pp.75-83
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• 2008

본 연구의 목적은 보행 속도의 차이에 따른 최대 관절 모멘트와 최대 모멘트 발생 시점의 관절 각도 상관관계를 규명하는데 있다. 8명의 $20{\sim}30$대 남성을 대상으로 보행 속도의 3가지 단계(1.5m/s, 1.8m/s, 2.1m/s)를 나누어 속도에 따른 보행을 실시하여 얻어진 결론은 다음과 같다. 1. 보행 속도가 증가함에 따라 무릎 최대 신전 모멘트는 증가하였고, 굴곡, 외전 모멘트는 큰 영향을 받지 않았다. 2. 최대 신전 모멘트가 발생하는 시점의 무릎 관절 각도는 굴곡의 움직임이 커졌으나, 다른 무릎 관절 각도에는 변화가 없었다. 3. 힙 최대 신전, 굴곡, 외전 모멘트는 증가하였다. 4. 최대 굴곡과 신전 모멘트가 발생하는 시점의 힙 관절 각도의 신전과 굴곡의 증가 현상을 보였으나, 최대 외전 모멘트가 발생하는 시점의 무릎 관절 각도에는 변화가 없었다. 5. 무릎 최대 신전, 굴곡, 외전 모멘트와 무릎 관절 각도를 least square method를 이용하여 적합도 검사를 실시한 결과 R2값이 높게 나타나 상관관계의 설명력이 높았다. 이렇게 근사된 곡선의 근사식은 보행 속도에 따른 무릎 관절의 평가 자료로 이용될 것으로 기대된다.

• Steel and Composite Structures
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• 제44권1호
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• pp.49-63
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• 2022

This study aims to develop ensemble machine learning (ML) models for estimating the peak floor acceleration and maximum top drift of steel moment frames. For this purpose, random forest, adaptive boosting, gradient boosting regression tree (GBRT), and extreme gradient boosting (XGBoost) models were considered. A total of 621 steel moment frames were analyzed under 240 ground motions using OpenSees software to generate the dataset for ML models. From the results, the GBRT and XGBoost models exhibited the highest performance for predicting peak floor acceleration and maximum top drift, respectively. The significance of each input variable on the prediction was examined using the best-performing models and Shapley additive explanations approach (SHAP). It turned out that the peak ground acceleration had the most significant impact on the peak floor acceleration prediction. Meanwhile, the spectral accelerations at 1 and 2 s had the most considerable influence on the maximum top drift prediction. Finally, a graphical user interface module was created that places a pioneering step for the application of ML to estimate the seismic demands of building structures in practical design.

• 한국운동역학회지
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• 제22권3호
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• pp.325-332
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• 2012

This study aimed to analyze the effects of external load between male and female on angular velocity, moment, and absorbed energy of the lower-extremity joints during drop landing. The study subjects were 9 male($mass=70.82{\pm}4.64kg$, $height=1.71{\pm}0.04m$, $age=24.5{\pm}1.84years$), 9 female($mass=50.14{\pm}4.09kg$, $height=1.61{\pm}0.03m$, $age=23.6{\pm}2.62years$), without any serious musculoskeletal, coordination, balance, or joint/ligament problems for 1 year before the study. The angular velocity, flexion/extension and abduction/adduction moments, and absorbed energy of the lower-extremity joints were compared between the men and women during drop landing under 4 different conditions of external load(0%, 8%, 16%, and 24%) by using two-way repeated ANOVA(p < .05). The women landed with a greater peak angular velocity of the ankle joint, greater peak inversion moment, and lower peak hip-extension moment than the men did, under all 4 conditions. Additionally, the landing characteristics of the women were distinct from those of the men; the women showed a greater peak knee-adduction moment and greater absorbed energy of the knee joint. These differences indicate that anterior cruciate ligament(ACL) strain was greater in the women than in the men and therefore, women may be at a higher potential risk for noncontact injuries of the ACL with an increase in external load.

• Nuclear Engineering and Technology
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• 제29권4호
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• pp.310-319
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• 1997

A finite element analysis of a trunnion pipe anchor is presented. The structure is analyzed for the case of internal pressure and moment loadings. The stress results are categorized into the average (membrane) stress, the linearly varying (bending) stress and the peak stress through the thickness. The resulting stresses are interpreted per Section III of the ASME Boiler and Pressure Vessel Code from which the Primary(B$_1$), Secondary(C$_1$) and Peak(K$_1$) stress indices for pressure, the Primary (B$_2$), Secondary(C$_2$) and Peak(K$_2$) stress indices for moment are developed. Based on the comparison between stress value by stress indices derived in this paper and stress value represented by the ASME Code Case N-391-1, the empirical equations for stress indices are effectively used in the piping stress analysis. Therefore, the use of empirical equations can simplify the procedure of evaluating the local stress in the piping design stage.

• 한국운동역학회지
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• 제17권3호
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• pp.181-188
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• 2007

The purpose of this study was to investigate the biomechanical effects of wearing different type of insole shoes on gait characteristics in patients with knee osteoarthritis. Seven patients with knee osteoarthritis (Grade 3 & 4 by Kellgren & Lawrence) were participated in the study. They wore two different type of shoes (with Gel-type Insole: GIS, with Normal insole: NIS) during gait. Three dimensional cinematography and Ground Reaction Force(GRF) data were used to get the maximal value of horizontal distance between the center of pressure in GRF and knee joint center, GRF in mediolateral direction, peak value of GRF in frontal plane, vertical compressive force and adduction moment in knee joint. The results were as follows: The maximal value of horizontal distance between the center of pressure in GRF and knee joint center was smaller in GIS than NIS. The peak value of GRF in mediolateral direction was found in 30% of gait cycle, five subjects wearing GIS showed lower value of peak GRF in mediolateral direction than wearing NIS. The peak value of GRF in frontal plane and vertical compressive force in knee joint did not show any difference between GIS and NIS. The adduction moment in GIS decreased in the late stance of gait and the mean value of the adduction moment in GIS smaller than that in NIS. GIS may help to move quickly knee joint center to the center of pressure in GRF, therefore it may prevent increasing the adduction moment in knee joint.

• Steel and Composite Structures
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• 제15권6호
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• pp.645-658
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• 2013

The objective of the study is to predict the moment anchorage capacity of the concrete filled steel box (CFSB) as footing by using the 3D finite element program CAMUI developed by authors' laboratory. The steel box is filled with concrete and concrete filled steel tube (CFT) column is inserted in the box. Numerical simulation of the experimental specimens was carried out after introducing the new constitutive model for post peak behavior of concrete in compression under confinement. The experimental program was conducted to verify the reliability of the simulation results by the FE program. The simulated peak loads agree reasonably with the experimental ones and was controlled by concrete crushing near the column. After confirming the reliability of the FEM simulation, effects of different parameters on the moment anchorage capacity of concrete filled steel box footing were clarified by conducting numerically parametric study.

• 한국운동역학회지
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• 제26권4호
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• pp.433-441
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• 2016

Objective: The purpose of this study was to understand the injury mechanism and to provide quantitative data to use in prevention or posture correction training by conducting kinematic and kinetic analyses of risk factors of lower extremity joint injury depending on the change of direction at different angles after a landing motion. Method: This study included 11 men in their twenties (age: $24.6{\pm}1.7years$, height: $176.6{\pm}4.4cm$, weight: $71.3{\pm}8.0kg$) who were right-leg dominant. By using seven infrared cameras (Oqus 300, Qualisys, Sweden), one force platform (AMTI, USA), and an accelerometer (Noraxon, USA), single-leg drop landing was performed at a height of 30 cm. The joint range of motion (ROM) of the lower extremity, peak joint moment, peak joint power, peak vertical ground reaction force (GRF), and peak vertical acceleration were measured. For statistical analysis, one-way repeated-measures analysis of variance was conducted at a significance level of ${\alpha}$ <.05. Results: Ankle and knee joint ROM in the sagittal plane significantly differed, respectively (F = 3.145, p = .024; F = 14.183, p = .000), depending on the change of direction. However, no significant differences were observed in the ROM of ankle and knee joint in the transverse plane. Significant differences in peak joint moment were also observed but no statistically significant differences were found in negative joint power between the conditions. Peak vertical GRF was high in landing (LAD) and after landing, left $45^{\circ}$ cutting (LLC), with a significant difference (F = 9.363, p = .000). The peak vertical acceleration was relatively high in LAD and LLC compared with other conditions, but the difference was not significant. Conclusion: We conclude that moving in the left direction may expose athletes to greater injury risk in terms of joint kinetics than moving in the right direction. However, further investigation of joint injury mechanisms in sports would be required to confirm these findings.

• 한국수자원학회논문집
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• 제36권2호
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• pp.183-193
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• 2003

강우의 지속시간을 처리하는 방법에 따라 AMC조건과 강우의 시간분포인(1차, 2차, 3차, 4차 모멘트)가 유출에 미치는 연관성을 연구하였다. 연구결과 강우를 10분위로 고려하는 경우, CN은 AMCIII조건에서 1차 및 2차 모멘트와 상관성을 보였으나 그 외의 조건에서는 상관성이 없었다. 또한 첨두유출비(QP/Q)는 AMC I조건에서 3차 및 4차 모멘트와 상관성을 보였으며, AMCIII조건에서는 1차 및 2차 모멘트와 상관성을 보였다. 강우의 전체 지속시간을 고려하는 경우, CN은 AMC I조건에서 모든 시간분포인자와 상관성을 보였으나 AMCIII조건에서는 1차 및 2차 시간분포인자와 상관성을 보였다. 그리고 첨두유출비(QP/Q)는 AMC I조건에서 3차 및 4차 시간분포인자와 상관성을 보였으나 그 외의 조건에서는 거의 상관성을 보이지 않았다. 따라서 보다 정확한 CN 산정을 위해 강우의 시간분포와 제시된 시간분포인자를 고려할 것을 제안하였다.

• 대한통합의학회지
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• 제5권4호
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• pp.41-48
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• 2017

Purpose : The purpose of this study was to verify the relationships among the knee adduction moment, hip rotation range, strength of hip rotators, and Foot Posture Index of healthy young adults. Method : Thirty-two healthy adults(24 male, 8 females) participated in this study. Subjects performed 5 walking trials to evaluate the knee adduction moments using a three-dimensional motion analysis system. Hip rotation ranges and hip rotator strengths were measured using a standard goniometer and a handheld dynamometer, respectively. The mean of three trials of clinical tests was used for data analysis. Results : The first peak knee adduction moment was significantly correlated with the hip rotation ranges and hip rotator strengths (P<.05). The second peak knee adduction moment was showed significant correlations with hip external rotation and rotation ratio. There were no correlations between Foot Posture Index and all knee adduction moments (P>.05). Conclusion : This study suggests that imbalances of the range of motion and strength of the internal and external rotation of the hip joint can affect knee adduction moments. The impact may exacerbate musculoskeletal disorders such as osteoarthritis of the knee. Therefore, further studies should be conducted to evaluate the effects of clinical interventions to correct these imbalances on the reduction of the knee adduction moments in patients with knee osteoarthritis.