• Korean Journal of Applied Biomechanics
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• v.15 no.1
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• pp.237-257
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• 2005

It was to study as a following-research of "A Case Study on Center of Gravity(COG) Analysis when Performing Uchimata(inner thigh reaping throw) by Posture and Voluntary Resistance Levels(VRL) of Uke in Judo[I]". The purpose of this study was to analyze the COG variables when performing uchimata(inner thigh reaping throw) by two postures and voluntary resistance levels(VRL) of uke(reciver) in Judo. The subjects, who were one male judoka(YH) for 1992 Barcelona Olympic Games Olympian(silver medalist), and one male trainee; Y.I.University representative member (SDK), and were filmed on two S-VHS 16mm video cameras(60fields/sec.) through 3-dimensional motion analysis methods, that postures of uke were shizenhontai (straight natural posture) and jigohontai(straight defensive posture), VRL of uke were 0% and 100%, respectively. The kinematical variable was COG variable, distance of COG, and distance of resultant COG between uke and tori(the thrower), velocity and acceleration of COG. The data of this study collection were digitized by SIMI Motion Program computed the mean values and the standard deviation calculated for each variables. When performing uchinmata according to each posture and VRL of uke and classifying. From the data analysis and discussion, the conclusions were as follows : 1. Displacement of COG Subject YH, COG was the highest in kuzushi(balance -breaking), vertical COG was low when following in tsukuri(positioning; set-up), kake(application; execution), and COG was pattern of same character each postures and resistance, respectively. Subject SDK, COG was low from kumikata(engagement positioning) to kake, and COG was that each postures and resistance were same patterns, respectively. Subject YH, SDK, each individual, postures and resistance, vertical COG was the lowest in kake phase, when performing. 2. Distance of COG between uke and tori The distance of COG between uke and tori when performing, subject YH was $0.64{\sim}0.70cm$ in kumikata, $0.19{\sim}0.28cm$ in kake, and SDK was $0.68{\sim}0.72cm$ in kumikata, $0.30{\sim}0.42\;cm$ in kake. SDK was wider than YH. 3. Distance of resultant COG between uke and tori The distance of resultant COG between uke and tori when performing, subject YH was $0.27{\sim}0.73cm$ from kumikata to kake. and SDK was $0.14{\sim}0.34cm$ in kumikata, $0.28{\sim}0.65cm$ in kake. Jigohontai(YH:$0.43{\sim}0.73cm$,SDK:$0.59{\sim}0.65cm$) was more moved than shizenhontai(YH:$0.27{\sim}0.53cm$, SDK: $0.28{\sim}\;0.34cm$). 4. Velocity of COG The velocity of COG when performing uchimata, subject YH was fast anterior-posterior direction in kuzushi, ant.-post. and vertical direction fast in tsukuri and kake. SDK was lateral, ant.-post. and vertical direction in kuzushi, ant.-post. and vertical direction in tsukuri and ant.-post. direction in take, respectively. 5. Acceleration of COG The acceleration of COG when performing uchimata, The trend of subject YH was showed fast vertical direction in kuzushi and tsukuri, ant.-post. and vertical direction fast in kake. The trends of SDK showed lateral direction in kuzushi, lateral and ant.-post. direction in tsukuri and ant.-post. direction in kake, respectively.

• Structural Engineering and Mechanics
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• v.25 no.1
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• pp.75-89
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• 2007

Post-earthquake reconnaissance and experimental research indicate that squat reinforced concrete (RC) columns in existing buildings or bridge piers are vulnerable to non-ductile shear failure. Recently, several experimental studies were conducted to investigate upgrading the shear resistance capacity of such columns in order to modify their failure mode to ductile one. Among these upgrading methods is the use of fibre-reinforced polymer (FRP) jackets. One of the preferred analytical tools to simulate the response of frame structures to earthquake loading is the lumped plasticity macromodels due to their computational efficiency and reasonable accuracy. In these models, the columns' nonlinear response is lumped at its ends. The most important input data for such type of models is the element's lateral force-displacement backbone curve. The objective of this study is to verify an analytical method to predict the lateral force-displacement ductility relationship of axially and laterally loaded rectangular RC squat columns retrofitted with FRP composites. The predicted relationship showed good accuracy when compared with tests available in the literature.

• The Journal of Advanced Prosthodontics
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• v.12 no.5
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• pp.283-290
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• 2020

PURPOSE. The present study aimed to evaluate the clinical applicability of monolithic zirconia (MZ) crowns of different thickness via determination of fracture resistance and marginal fit. MATERIALS AND METHODS. MZ crowns with 0.5, 0.8, 1.0, and 1.5 mm thickness and porcelain fused to metal (PFM) crowns were prepared, ten crowns in each group. Marginal gaps of the crowns were measured. All crowns were aged with thermal cycling (5 - 55℃/10000 cycle) and chewing simulator (50 N/1 Hz/lateral movement: 2 mm, mouth opening: 2 mm/240000 cycles). After aging, fracture resistance of crowns was determined. Statistical analysis was performed with one-way ANOVA and Tukey's HDS post hoc test. RESULTS. Fracture loads were higher in the PFM and 1 mm MZ crowns compared to 0.5 mm and 0.8 mm crowns. 1.5 mm MZ crowns were not broken even with the highest force applied (10 kN). All marginal gap values were below 86 ㎛ even in the PFM crowns, and PFM crowns had a higher marginal gap than the MZ crowns. CONCLUSION. The monolithic zirconia exhibited high fracture resistance and good marginal fit even with the 0.5 mm thickness, which might be used with reduced occlusal thickness and be beneficial in challengingly narrow interocclusal space.

• Steel and Composite Structures
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• v.32 no.2
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• pp.265-279
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• 2019

The self-centering capacity and energy dissipation performance have been recognized critically for increasing the seismic performance of structures. This paper presents an innovative steel moment frame with self-centering steel reinforced concrete (SRC) wall panel incorporating replaceable energy dissipation devices (SF-SCWD). The self-centering mechanism and energy dissipation mechanism of the structure were validated by cyclic tests. The earthquake resilience of wall panel has the ability to limit structural damage and residual drift, while the energy dissipation devices located at wall toes are used to dissipate energy and reduce the seismic response. The oriented post-tensioned strands provide additional overturning force resistance and help to reduce residual drift. The main parameters were studied by numerical analysis to understand the complex structural behavior of this new system, such as initial stress of post-tensioning strands, yield strength of damper plates and height-width ratio of the wall panel. The static push-over analysis was conducted to investigate the failure process of the SF-SCWD. Moreover, nonlinear time history analysis of the 6-story frame was carried out, which confirmed the availability of the proposed structures in permanent drift mitigation.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.20 no.3
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• pp.252-262
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• 2019

Following the earthquake in Gyeongju (2016) and Pohang (2017), South Korea is no longer a safe place for earthquakes. Accordingly, the need for shelters suitable for disaster environments is increasing. In this study, a lightweight composite panel was used to produce post-disaster housing for refugees to compensate for the disadvantages of existing evacuation facilities. For this purpose, an evaluation of structural performance and thermal environment for post-disaster housing for refugees composed of lightweight composite panels was performed. To assess the structural performance, a lateral loading test was conducted on a system made of lightweight composite panels. The specimens consisted of two types, which differed according to the bonding method, as a variable. In addition, the seismic and wind loads were calculated in accordance with KBC 2016 and compared with the experimental results. Regarding the energy performance, optimization of south-facing window planning and window-wall ratio and solar heat gain coefficient were analyzed to minimize heating, cooling, and lighting energy. As a result, the specimens composed of lightweight composite panels will perform sufficiently safely for lateral loads and the optimized window planning will lead to a low-energy operation.

• Earthquakes and Structures
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• v.21 no.5
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• pp.445-460
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• 2021

This study experimentally explored the behaviour of 12 concrete filled steel tube (CFST) and steel tube columns subjected to lateral cyclic loading. The L/D ratio was 12.3 while D/t ratios were 45.4, 37.8 and 32.4, classifying these 12 specimens into 3 groups. Each group included 3 CFST and 1 steel tube columns and were tested to failure. The experimental results indicated that CFST specimens reached the state of 'collapse prevention' (drift 4%) prior to the occurrence of local buckling. Strength degradation of CFST specimens did not occur up to the failure by buckling. This showed the favourable characteristic of CFST columns in preventing collapse of structures subjected to earthquakes. The high energy absorption capability in the post collapse limit state was appropriate for dissipating energy in structures. Compared to steel tube columns, CFST columns delayed local buckling and prevented inward buckling. Consequently, CFST columns exhibited their outstanding seismic performance in terms of the increased ultimate resistance, capacity to sustain 2-3 additional load cycles and significantly higher drift. A simple and reasonably accurate model was proposed to predict the ultimate strength of CFST columns under lateral cyclic loading.

• Geomechanics and Engineering
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• v.15 no.5
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• pp.1101-1111
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• 2018

This study aims to present accurate soil modeling and validation of a single roadside guardrail post as well as a single concrete pile installed near cut slopes or compacted sloping embankment. The conventional Winkler's elastic spring model and p-y curve approach for horizontal ground cannot directly be applied to sloping ground where ultimate soil resistance is significantly dependent on ground inclination. In this study, both grid-based 3-D FE model and particle-based SPH (smoothed particle hydrodynamics) model available in LS-DYNA have been adopted to predict the static behavior of a laterally loaded guardrail post. The SPH model has potential to eliminate any artificial soil stiffness due to the deterioration of the node-connected Lagrangian soil mesh. For this purpose, this study comprises two parts. Firstly, only 3-D FE modeling has been tested to show the numerical validity for a single concrete pile in sloping ground using Mohr-Coulomb material. However, this material option cannot be implemented for SPH elements. Nevertheless, Mohr-Coulomb model has been used since this material model requires six input soil data that can be obtained from the comparative papers in literatures. Secondly, this work is extended to compute the lateral resistance of a guardrail post located near the slope using the hybrid approach that combines Lagrange FE elements and SPH elements by the suitable node-merging option provided by LS-DYNA. For this analysis, the FHWA soil material developed for application to road-base soils has been used and also allows the application of SPH element.

• Physical Therapy Korea
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• v.25 no.4
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• pp.46-52
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• 2018

Background: The hamstring muscles in the lower extremity are highly important for knee joint stability and can be classified into medial and lateral hamstrings according to the anatomical position, which have some different functions. To measure the strength of the individual hamstring muscles, manual muscle testing is clinically performed by dividing rotation postures into internal and external postures. However, this has no sufficient scientific background. Objects: This study aimed to test the difference that the tibial rotation would cause in the muscle activity of the medial and lateral hamstrings. Methods: The muscle activities of the biceps femoris, semitendinosus, and semimembranosus were measured in a total of three different postures (neutral position and internal and external rotations) with 3 replications. During the maximal isometric contraction, resistance was constantly provided by the string attached to the strap, not by manual resistance of the examiner. Before and after electromyography measurements, the participants underwent hamstring flexibility measurement using the active knee extension test in the supine position on the treatment table. Results: The semitendinosus had a 12.56% reduction in muscle activity in external rotation as compared with that in neutral position. The biceps femoris and semimembranosus showed reduced muscle activities in both external and internal rotations as compared with those in neutral position. Only the women showed significant decreases in the comparison between pre and post-active knee extension. Conclusion: Only the semitendinosus muscle was consistent with the anatomical speculation. However, the reduction in the muscle activity of the semitendinosus as compared with that in neutral position was only 12.56%, the clinical value of which may be difficult to justify.

• Horticultural Science & Technology
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• v.32 no.2
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• pp.235-240
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• 2014

Cucumber mosaic virus (CMV) is one of the most important viral diseases in pepper (Capsicum annuum L.), and several genes for resistance were reported in Capsicum spp. In Korea, a single dominant gene that is resistant to $CMV_{Fny}$ and $CMV_{P0}$ has been used for breeding. Recently, a new strain ($CMV_{P1}$) was reported that could infect cultivars resistant to both $CMV_{Fny}$ and $CMV_{P0}$. Therefore, breeding of more robust CMV-resistant cultivars is required. In this study, we surveyed the inheritance of $CMV_{P1}$ resistance and analyzed the location of the resistance loci. After $CMV_{P1}$ inoculation of various germplasms and breeding lines, one accession (ICPN18-8) showed no visual symptoms at 15 dpi (days post inoculation) but was susceptible after 45 dpi, and one resistant line (I7339) showed resistance until at 45 dpi. The latter line was used for tests of resistance inheritance. A total of 189 $F_2$ plants were examined, with 42 individuals showing resistance at 15 dpi and a phenotype segregation ratio close to 1:3 (resistant:susceptible plants). In a lateral ELISA test at 45 dpi, 11 plants showed resistance, and the segregation ratio was changed to 1:15. These results indicate that resistance in C. annuum 'I7339' is controlled by two different recessive genes; we named these resistance genes 'cmr3E' and 'cmr3L,' respectively. To locate these two resistant loci in the pepper linkage map, various RAPD, SSR, and STS markers were screened; only nine markers were grouped into one linkage group (LG). Only one RAPD primer (OPAT16) was distantly linked with cmr3E (22.3 cM) and cmr3L (20.7 cM). To develop more accurate markers for marker-assisted breeding, enriching for molecular markers spanning two loci will be required.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2009.11a
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• pp.31-34
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• 2009

Large outrigger elements tie the concrete core to perimeter columns, significantly increasing the building's lateral stiffness as well as its resistance to overturning due to wind. The outriggers are deep elements, and large tie forces are resisted by top and bottom heavy longitudinal reinforcing and vertical ties. To reduce construction costs, all primary reinforcing bars in outrigger levels are SD500. Further, concrete strengths of 80MPa have been specified for outrigger elements. However, the reductions in the amount of concrete and reinforcement steel are more increased in tall building. With these backgrounds, 80MPa high strength concrete outrigger system using post tension method is developed. Significant economic savings can be made by reducing the element sizes and material content. The developed outrigger system is designed using strut-and-tie models. In addition, four 1/4-scale test specimens were selected from the same prototype structure. The results from the tests are confirmed that the structural behaviors of the developed outrigger member have better capacities than those of a conventional method.