• 대한수학회보
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• 제56권4호
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• pp.1027-1039
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• 2019

The concept of jump concerns the distribution of $Tur{\acute{a}}n$ densities. A number ${\alpha}\;{\in}\;[0,1)$ is a jump for r if there exists a constant c > 0 such that if the $Tur{\acute{a}}n$ density of a family $\mathfrak{F}$ of r-uniform graphs is greater than ${\alpha}$, then the $Tur{\acute{a}}n$ density of $\mathfrak{F}$ is at least ${\alpha}+c$. To determine whether a number is a jump or non-jump has been a challenging problem in extremal hypergraph theory. In this paper, we give a way to generate non-jumps for hypergraphs. We show that if ${\alpha}$, ${\beta}$ are non-jumps for $r_1$, $r_2{\geq}2$ respectively, then $\frac{{\alpha}{\beta}(r_1+r_2)!r_1^{r_1}r_2^{r_2}}{r_1!r_2!(r_1+R_2)^{r_1+r_2}}$ is a non-jump for $r_1+r_2$. We also apply the Lagrangian method to determine the $Tur{\acute{a}}n$ density of the extension of the (r - 3)-fold enlargement of a 3-uniform matching.

• 비교문화연구
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• 제28권
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• pp.37-53
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• 2012

This paper examines 'an active nihilism' in Suk-je Sung's novels in detail. The focus of this study is formed from the critical mind in a critical perspective that in Korean novels before and after 2000s, characters who embody 'problematic individuals' of $Luk{\acute{a}}cs$ have disappeared and those close to 'active nihilists' has become the mainstream. The most representative example of this phenomenon is Suk-je Sung's novels. 'Active nihilists' in his novels are described as 'ascetics' who mastered various spheres such as 'billiard', 'baduk gambling', 'alcohol', 'dance', and 'book collecting', and so on. In the sense that they reject the transcendental conditions of the modern world and live in the space and time of play in which they can display their passion and potentiality to the maximum, they beings jumping over the 'reality principle'. Also, what they want to repeat is not the endless exchange of labor and capital according to the capitalist system of exchange but rather the repeated existence of their power and passion. This 'anthropology of power and passion' is 'active nihilism' which could be expressed as the 'subject of creating new value' and 'Dionysian affirmation' by Nietzsche. Suk-je Sung's novels sharply prove the stylistic essence of 'a novel' which has to create its own form every time, constantly renewing the narrative style of the past ideal model. In this respect, they are very problematic and his innovation of a form draws the attention. Further, this will certainly be the important object of research in the diachronic dimension of contemporary Korean novel.

• 대한물리의학회지
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• 제16권3호
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• pp.123-130
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• 2021

PURPOSE: Robotic gait training is being used increasingly to improve the gross motor performance and gait speed. The present study examined the effectiveness of a novel end-effector type of robotic gait training (RGT) system on standing, walking, running, and jumping functions, as well as the gait speed in children with spastic cerebral palsy. METHODS: Eleven children with spastic cerebral palsy Gross Motor Function Classification System (GMFCS) levels I-III (6 males; age range, 15.09 ± 1.44 years) were examined. They underwent 24 sessions (30 minutes/sessions, one time/day, three days/week for eight consecutive weeks) of RGT. The Gross Motor Function Measure-88 D domain (GMFM D), and GMFM E were assessed with a pretest and posttest of RGT. The setting was a one-group pretest-posttest design. RESULTS: A comparison of the pre-test and post-test show that the outcomes in post-test of GMFM D (p < .01), GMFM E (p < .05), and 10MWT were improved significantly after RGT intervention. CONCLUSION: The present study provided the first evidence on the effects of an eight-weeks RGT intervention in participants with spastic CP. The outcomes of this clinical study showed that standing performance, locomotion function, and gait speed increased in after 24 sessions of the end-effector RGT system in children with spastic cerebral palsy.

• Structural Engineering and Mechanics
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• 제82권3호
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• pp.283-294
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• 2022

An inerter is a passive mechanical element whose inertance can be thousands of times its own physical mass. This paper discusses the application of an inerter-based passive control system, termed rotational inertial double-tuned mass damper (RIDTMD), to mitigate human-induced floor vibrations. First, the acceleration frequency response function of the floor with an RIDTMD is first derived. It is then employed to determine the optimal design parameters of the RIDTMD using the extended fixed-points technique. Based on a theoretical analysis, design-oriented empirical functions are proposed for the RIDTMD optimal parameters, whose performance for floor vibration control is evaluated by numerical examples, in which three typical human-induced load types are considered: walking, jumping, and bouncing. The results indicate that the applicability and effectiveness of the RIDTMD for human-induced floor vibration control are robust for various load types, load frequencies, and floor natural frequencies. For the same mass ratio, the RIDTMD is better than the TMD in reducing the floor vibration amplitude and improving the effective frequency suppression bandwidth, and for the same vibration suppression effect, the mass of the RIDTMD is much lighter than that of the TMD.

• Steel and Composite Structures
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• 제46권4호
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• pp.577-589
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• 2023

In this study, on-site testing was carried out to investigate the vibration performance of a cold-formed thin-walled steel floor system. Ambient vibration, walking excitation (single and double persons), and impulsive excitation (heel-drop and jumping) were considered to capture the primary vibration parameters (natural frequencies, damping ratios, and mode shapes) and vertical acceleration response. Meanwhile, to discuss the influence of cement fiberboard on structural vibration, the primary vibration parameters were compared between the systems with and without the installation of cement fiberboard. Based on the experimental analysis, the cold-formed thin-walled steel floor possesses high frequency (> 10 Hz) and damping (> 2%); the installed cement fiberboard mainly increases the mass of floor system without effectively increasing the floor stiffness and may reduce the effects of primary vibration parameters on acceleration response; and the human-structure interaction should be considered when analyzing the vibration serviceability. The comparison of the experimental results with those in the AISC Design Guide indicates that the cold-formed thin-walled steel floor exhibits acceptable vibration serviceability. A crest factor 𝛽_rp (ratio of peak to root-mean-square accelerations) is proposed to determine the root-mean-square acceleration for convenience.

• 한국전문물리치료학회지
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• 제30권4호
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• pp.275-280
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• 2023

Background: Although warm-ups before exercise are widely accepted, research on sex differences in improving hamstring flexibility is limited. Differences in the physical and physiological characteristics between males and females may result in different responses to warm-ups. Objects: This study aimed to examine sex differences in the effects of specific warm-up on hamstring flexibility. Methods: This study included 24 young adults with hamstring tightness. The participants performed five maximal knee extensions and flexions at 90° flexion of the hip, and the maximal knee extension angle was measured in real-time using a smartphone clinometer application. Results: The groups did not significantly affect the maximal knee extension angle but showed a significant effect for repetition (p = 0.002) and group-repetition interaction (p = 0.002). Males had no significant change in hamstring flexibility; however, females showed a significant increase in flexibility in the 5^th trial compared with the 1^st trial (p = 0.041). These results demonstrated sex-specific differences in flexibility improvement over time. Conclusion: The findings of this study suggest that specific warm-up can successfully improve hamstring flexibility in females. This may be due to various factors, such as muscle stiffness of the lower extremity, estrogen levels, and temperature sensitivity. In clinical settings, specific warm-up might be helpful for females who participate in sports or activities, such as running or jumping, which require a full range of motion in the hip and knee joints.

• 현장농수산연구지
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• 제25권4호
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• pp.103-110
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• 2024

This study was conducted to provide basic data to prepare a plan for establishing a horse riding competition system to expand the base of the horse industry. As a result of analyzing the factors and needs that affect participation in horse riding competitions among athletes participating in horse riding competitions, the following conclusions were obtained. First, for participants in equestrian competitions, competitions and games will be held in which even athletes with lower skills can participate, and measures will be taken to ensure that obstacle jumping and dressage can develop equally. Second, there is a need for a venue in the metropolitan area where national-scale equestrian competitions can be held. Third, the point system must be introduced to manage the history of participants in horseback riding competitions as well as to encourage continuous participation in competitions. In future research, it is necessary to seek the development of horse riding competitions by examining the size of the prize money, the continuation of competition participation, and the transformation into professional athletes in horse riding competitions.

• 로봇학회논문지
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• 제19권1호
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• pp.53-57
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• 2024

A hopping robot can move through a confined environment while overcoming obstacles. To create a small hopping robot, it must be able to generate a large amount of energy and release it at the same time. However, due to the small size of the robot, there is a limit to the size of the actuator that can be used, so it is mainly used to collect energy in an elastic element and release it at once. In this paper, we propose a small hopping robot with a simplified design by removing ancillary parts and enabling continuous hopping using only a small actuator based on a direct-drive method. In addition, repeated actuation over the rated voltage can cause thermal breakdown of the actuator. To check the safety of the actuator at high voltage, we perform modeling to predict the temperature of the actuator and verify the accuracy of the modeling through experiments.

• 한국생활과학회지
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• 제21권3호
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• pp.567-576
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• 2012

The purpose of this study was to analyze and determine the relationship between physiological responses including blood flow rate and garment pressure, and the feeling of restrictive tightness associated with the wearing skinny pants as a popular clothing style. Evaluation was based on material type, posture and activity type, and body part location. Five female college students took part in this research. Five kinds of experimental clothes with waist measurements of 66cm were chosen. An analysis of the selected skinny pants demonstrated the degree of the whole looseness was higher in this order: clothing type A>B>D>C, and E with E being knitted cloth. Garment pressure was the highest in the front knee portions and was lowest in the outside thigh region. Garment pressure was highest in this sequence : clothing type C>=D>A>=B>E. In terms of posture and activity types, garment pressure was the highest when research participants were crouching, and was the lowest when standing. The blood flow rate was highest in this order: clothing type E>D>B>A>C. Type C skinny pants impeded blood flow and demonstrated the tightest and most restrictive relationship. Blood flow rate varied depending on the type of movement and was highest in this order: getting up, rowing, kicking, jumping and O-shaped leg posture. The results of subjective pressure evaluation demonstrated that pressure was highest in this order: E>=C>B>A>D. These results suggests the need to improve on the patterns and the material design in the area of the front knees. The degree of the looseness when wearing skinny pants did not always correspond to garment pressure or subjective sensation.

• 한국전문물리치료학회지
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• 제8권1호
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• pp.20-34
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• 2001

This paper presents the relevance between GMFM and the spatiotemporal parameters of gait in children with cerebral palsy. Twenty-one children ($73.11{\pm}30.06$ months) with cerebral palsy participated in this study. GMFM was performed and spatiotemporal parameters of gait were measured by foot print gait analysis. A correlation analysis was used to investigate the correlation between GMFM scores and spatiotemporal parameters of gait. A linear regression analysis was employed to find how much each gait spatiotemporal parameters could be predicted from GMFM scores. The total GMFM scores was significantly correlated with walking speed, cadence, and stride length. Dimensions D (standing) and E (walking, running, and jumping) were more significantly correlated with gait spatiotemporal parameters than dimensions A (lying and rolling), B (sitting), and C (crawling and kneeling). The GMFM scores were useful for predicting spatiotemporal parameters. However, it is difficult to predict the status of gait development using GMFM scores because GMFM scores and gait spatiotemporal parameters are only measured as quantities not qualities. In the field, it is easily found that many children with cerebral palsy are unable to walk in any way. Consequently, gait analysis cannot be performed in many cases. Therefore, it is more reasonable to investigate the influence of GMFM on spatiotemporal parameters, rather than vice versa.