• The Journal of Korean Academy of Orthopedic Manual Physical Therapy
• /
• v.29 no.1
• /
• pp.1-9
• /
• 2023

BACKGROUND: The purpose of this study was to find out which exercise is more effective for the activation of the trunk, when the suspension plank and modified bridge exercise are performed. Weakening of the trunk muscles can lead to secondary injuries such as back injuries. In order to prevent injury, trunk muscles must be strengthened, and representative trunk strengthening exercises include planks and bridges. Each has been developed with a modified method, but since there is no paper comparing which exercise is more effective for trunk muscle strength, it was written to compare the two exercises. METHODS: The subjects were a random sample of 30 healthy men who agreed to participate in the study. The subjects were divided into two groups of 15 people each, and the suspension plank and the modified bridge exercise were performed for six weeks. The thickness of the transverse abdominis (TrA), internal abdominal oblique (IO), external abdominal oblique (EO), rectus abdominis (RA), multifidus (MF) was measured before and after the exercise. The two groups were analyzed using an independent t-test and paired t-test to compare the muscle thickness and the difference before and after exercise. RESULTS: The trunk muscle thickness was increased in both groups with suspension plank and modified bridge exercise, and there was a statistically significant difference. When comparing the two groups, the suspension plank group also showed a significant difference in RA (p<.05). CONCLUSION: As a result of this study, suspension plank exercise can have a positive effect on activating the trunk muscles and strengthening the strength of RA. Therefore, it is considered that suspension plank exercise is a more effective intervention to strengthen trunk muscle than modified bridge exercise.

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.19 no.9
• /
• pp.84-90
• /
• 2018

In constructing the multi-body dynamics model to analyze the behavior of the railway vehicle, it is very important to understand the properties of the suspension elements that constitute the suspension system. Among them, coil springs, which are mainly used in primary and secondary suspension systems, clearly show the axial stiffness in the drawings, but the lateral properties of the coil springs are not specified clearly, making it difficult to construct a dynamic analysis model. Therefore, in this paper, the model for analyzing the lateral stiffness of the coil spring is examined. A finite element method was applied to analyze the lateral stiffness of the coil spring and numerical analysis was performed by applying the coil spring lateral stiffness analysis model proposed by Krettek and Sobczak. And the test to analyze the lateral stiffness of coil spring was conducted. As a result of comparing with the test results, it was found that the results obtained by applying the lateral stiffness analysis model of Krettek and Sobczak and correcting the correction coefficient are similar to those of the test results.

• KSBB Journal
• /
• v.20 no.1 s.90
• /
• pp.34-39
• /
• 2005

In order to product the furofuranoid lignans, (+)-eudesmin which is one of the secondary products from Magnolia sieboldii. through cell suspension cultures; various culture media, initial sucrose concentration, elicitations, shaking speeds, and inoculum sizes. Among the culture media tested, MS medium had a pronounced effect on suspension cell growth and (+)-eudesmin contents. The maximum dry cell weight (DCW) of 3.71 g per flask was obtained at inoculum size of 0.5 g and in MS medium supplemented with $3\%$ sucrose plus 0.5 mg/L 2,4-D after 8 weeks. (+)-Eudesmin biosynthesis was stimulated with high initial sucrose concentration ,and the maximum (+)-eudesmin production of $3.2{\mu}g/g$ DCW was achieved at 200mg/L chitosan and $5\%$ initial medium sucrose. The optimal shaking speeds for dry biomass accumulation and (+)-eudesmin contents was 130 rpm. This work is considered to be helpful for large-scale bioprocessing of Magnolia sieboldii suspension cell cultures in bioreactor.

• Korean journal of dermatology
• /
• v.56 no.9
• /
• pp.552-555
• /
• 2018

Vitiligo is a commonly acquired cutaneous depigmentation disorder that affects 0.5~1% of the population worldwide. While phototherapy is the primary treatment for vitiligo, surgical methods can be used for treating patients who are refractory to conventional treatments. Herein, we present the case of a 14-year-old Korean girl who developed vitiligo after hematopoietic stem cell transplantation for the treatment of acute lymphoblastic leukemia. She had multiple depigmented patches on her lower legs that did not respond to narrow-band ultraviolet B phototherapy for 7 months. The depigmented patches were successfully treated by transplantation of non-cultured epidermal cell suspension from the epidermal roof of the suction blister in the right inner thigh. No adverse event, such as secondary infection or scarring in both the donor and recipient sites, was noted. We recommended that non-cultured epidermal cell suspension transplantation using the suction blister method would be a safe and effective option for the treatment of refractory vitiligo.

• Proceedings of the KIEE Conference
• /
• 2006.07b
• /
• pp.733-734
• /
• 2006

In this parer, characteristics of the flexible rail in levitation control system are analysed. The magnetic levitation system is an electromagnet type and is full-scaled vehicles. The system consists of electromagnet, chopper, flexible rail, secondary suspension system and levitation controller. The mathematical modelling for the whole system is carried out. Especially, the flexible rail is modelled using second-order mass-spring-damper system. Using the derived model, the dynamic characteristics for the system are presented with different vehicle speed.

• Proceedings of the KSR Conference
• /
• 2007.05a
• /
• pp.1631-1638
• /
• 2007

In this paper, a modeling for the dynamic behavior of a train vehicle is suggested for the prediction of the braking characteristics. In the dynamic modeling, effects of the primary and secondary suspension elements are considered and interactions between two vehicles are also estimated. This study can offer some fundamental results for a further research to enhance the braking performance using active braking control.

• Proceedings of the KIEE Conference
• /
• 1998.07a
• /
• pp.49-51
• /
• 1998

The 4-pole LHSM was composed of the figure-of-eight shaped 3-phase armature windings. DC field windings, and the segmented secondary with the transverse bar track. These parameters were computed from the analytical expressions and examined from FEM analysis.

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.21 no.11
• /
• pp.617-623
• /
• 2020

Urban railroad vehicles carry many passengers and are the core of an urban railroad transportation system. Therefore, the dynamic performance of the vehicle must be ensured. Dynamic behaviors such as the vibration and ride comfort of railway vehicles are affected by the structure of the suspension system. We analyzed the dynamic behavior of a railway vehicle according to the suspension system of an urban railway vehicle, which is mainly operated in Korea. For two types of vehicles with different suspension structures, the vibration of the vehicles on railway tracks was measured, and dynamic behavior characteristics such as vibration, ride, and vibration reduction rate were analyzed. The result of the test shows that the vibration performance of the body is superior to that of B-bogie in the lateral direction and that of A-bogie in the vertical direction. Overall, the ride quality of the A-bogie car is superior to that of B-bogie. When analyzing the vibration attenuation rate of primary suspension system, the vibration attenuation performance of B-bogie with coil spring was superior to that of A-bogie with a conical rubber spring. The secondary suspension system has better vibration attenuation performance for A-bogie with air springs compared to coil springs.

• Proceedings of the KSR Conference
• /
• 2005.05a
• /
• pp.350-355
• /
• 2005

The running stability and safety of a railway vehicle depends on the design characteristics and the contact condition between wheel and rail. In this paper, numerical simulations using ANSYS and ADAMS were done on the basis of the experimental observations. The results show that 0.6 Hz of the tail car motion is due to the natural mode of car combination of the KTX. The effects of the conicity of wheel and the lateral stiffness of the secondary suspension on the running stability were analyzed numerically using ADAMS/RAIL. The results also show 0.6 Hz as like the experimental observations. And the adoption of the wheel of GV40(${\lambda}=0.025$) brought the sway motion at the tail cars, but XP55(${\lambda}=0.055$) did not when the secondary lateral stiffness of the KTX was greater than 0.3 MN/m.

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.18 no.10
• /
• pp.81-87
• /
• 2017

This paper describes the dynamic behavior and enhancement of Korean high-speed trains. The tail vibration reduction method of the yaw damper installation method change, which was derived from previous research, was applied to the running test of high-speed train. In addition, the vibration reduction method for the entire vehicle was derived by a numerical method and its effect was confirmed by a running test. The improved design was applied to the double-deck high-speed train coaches and the commissioning proceeded without problems in dynamic behavior. Sensitivity analysis of the suspension parameters affecting the critical speed of Korean next-generation high-speed trains was performed and four design variables that greatly affected the critical speed were derived. These were in the order of the primary elastic joint x-directional stiffness, the secondary yaw damper series stiffness, the secondary lateral damper damping coefficient, and the carbody damper damping coefficient. By optimizing the design variables, the suspension parameter that improves the critical speed by 23.3% can be used in the commercial designs of Korean next-generation high-speed trains.