• Journal of The Korean Society of Integrative Medicine
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• v.5 no.3
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• pp.57-61
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• 2017

Purpose : The purpose of study was to find out the environmental risk factor that can be easily occurred imbalance muscle activities according to direction for using the ramp during one legged standing. Method : The subjects were 20 normal adults with a mean age of $23.15{\pm}2.14years$ and a Body Mmass Index (BMI) of $22.74{\pm}1.07$. Participants were measured muscle activities on vastus medialis, vastus lateralis, tibialis anterior, peroneus longus during one legged stance at four conditions ramp (down ramp, up ramp, medial ramp, lateral ramp). The statistical analyses were performed using IBM SPSS(Ver. 23) and p-value less than .05 were considered statistically significant for all cases. Result : In this study, the activity of the lower extremity muscle and the ratio of the vastus medial and lateral muscles according to the direction of use of the ramp were investigated. The changes in the muscle activity of the lower limbs along the direction of the ramp were significantly different between the vastus medial muscle and the peroneus longus muscle. Conclusion : For a short time on a ramp or a pedestrian crossing, a clerk in a ramp can move or stand by placing the lower limbs in various directions, but if performed in consideration of the individual's disease characteristics or unstable foot position, It is thought that there will be an effect to prevent on the ankle and knee unstability.

• The KSFM Journal of Fluid Machinery
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• v.18 no.5
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• pp.49-53
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• 2015

Thrust vector control is the method which generates the side force and roll moment by controlling exhausted gas directly in a rocket nozzle. TVC is classified by mechanical and fluid dynamic methods. Mechanical methods can change the flow direction by several objects installed in a rocket nozzle exhaust such as tapered ramp tabs and jet vane. Fluid dynamic methods control the flight direction with the injection of secondary gaseous flows into the rocket nozzle. The tapered ramp tabs of mechanical methods are used in this paper. They installed at the rear in the rocket nozzle could be freely moved along axial and radial direction on the mounting ring to provide the mass flow rate which is injected from the rocket nozzle. TVC of the tapered ramp tabs has the potential to produce both large axial thrust and high lateral force. We have conducted the experimental research and flow analysis of ramp tabs to show the performance and the structural integrity of the TVC. The experiments are carried out with the supersonic cold flow system and the schlieren graph. This paper provides to analyze the location of normal shock wave and distribution of surface pressure on the region enclosed by the tapered ramp tabs.

• Journal of the Architectural Institute of Korea Planning & Design
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• v.35 no.3
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• pp.59-66
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• 2019

In recent years, urban regeneration is focused on smart and pedestrian oriented development utilizing various mobility technology. The characteristics of walkways needs to reflect such development orientations. This research is the first step to find an adequate slope for ramp replacing stairs and shared by pedestrians, personal mobilities and powered wheelchairs. It aims to check if ramps on a recommended degree of angle by general guidelines are more preferred than stairs and find out what make difference of such preferences. Two surveys were conducted at $9^{\circ}$ and $9.6^{\circ}$ ramps coexisted with stairs at sequential and parallel location. The study on the survey result found that the general evaluation of $9^{\circ}$ ramp was better than $9.6^{\circ}$ ramp but $9^{\circ}$ ramp was not preferred than stairs while $9.6^{\circ}$ ramps was preferred. The difference of preferences was related to characteristics of stairs. The stair with shorter tread and riser next to $9^{\circ}$ ramp was evaluated much better than stairs next to $9.6^{\circ}$ ramp. Therefore the research concludes that $10.0^{\circ}$ which many guidelines recommend for the maximum slop of a ramp was not adequate for a ramp to replace stairs as a preferred means of vertical circulation. In addition the research found that the preference was sensitive to moving direction and gender especially in regards to comfort of stairs and safety of ramp. Most pedestrians chose a means of vertical circulation based on its comfort but pedestrian's evaluation of safety was most different based on moving direction.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2005.05a
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• pp.329-332
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• 2005

Cross rolling process is one of incremental forming processes to form an axi-symmetric shaped metal component. It can be classified into two types according to the shape of dies, which are a drum type (roll type) and a plate type (straight type). It can also be classified into a wedge type and a ramp type processes according to deformation characteristics of a material. The ramp type die is applied to plate type cross rolling process in cold forming process for forming of teeth of gear or bolt, while the wedge type die is generally utilized to drum type and plate type cross rolling processes in hot forming process. A shape of the ramp type die is usually same as final shape of a product at every section of a progressing direction, while the shape of the wedge type die has different shapes in a progressing direction. In this paper, a rolling of neck part in a ball stud component has been carried out using the plate type cross rolling process with a ramp shaped die. Forming characteristics have been performed using finite element analysis in order to obtain a proper preform for the ramp type plate cross rolling process.

• Proceedings of the KSME Conference
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• 2007.05b
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• pp.3068-3073
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• 2007

Aerodynamic forces and moments have been used to control rocket propelled vehicles. If control is required at very low speed, Those systems only provide a limited capability because aerodynamic control force is proportional to the air density and low dynamic pressure. But thrust vector control(TVC) can overcome the disadvantages. TVC is the method which generates the side force and roll moment by controlling exhausted gas directly in a rocket nozzle. TVC is classified by mechanical and fluid dynamic methods. Mechanical methods can change the flow direction by several objects installed in a rocket nozzle exhaust such as tapered ramp tabs and jet vane. Fluid dynamic methods control the flight direction with the injection of secondary gaseous flows into the rocket nozzle. The tapered ramp tabs of mechanical methods are used in this paper. They installed at the rear in the rocket nozzle could be freely moved along axial and radial direction on the mounting ring to provide the mass flow rate which is injected from the rocket nozzle. In this paper, the conceptual design and the performance study on the tapered ramp tabs of the thurst vector control has been carried out using the supersonic cold flow system and shadow graph. Numerical simulation was also performed to study flow characteristics and interactions between ramp tabs. This paper provides to analyze the location of normal shock wave and distribution of surface pressure on the region enclosed by the tapered ramp tabs.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2004.03a
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• pp.117-124
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• 2004

The mixing enhancement is one of the most important problems for the development of scramjet engines. The influence of the streamwise vortices produced by a ramp in a unheated supersonic flow on the mixing of twin jets injected from its base was experimentally investigated. Nominal Mach number of the main airstream and of the twin jets at the nozzle exits were 2.35 and 2.0, respectively. Three dimensional velocity distributions near the ramp with and without injection were measured by Particle Image Velocimetry (PIV). A pair of counter rotating streamwise vortices could be seen behind the injector without injection. On the other hand, two pairs of streamwise vortices could be seen with injection. The outer one had the same direction as the vortex pair produced by the ramp, but they were stronger than those produced by the ramp. The inner ones had the opposite directions to the outer ones. It is considered that these vortices enhance the mixing near the injector.

• The KSFM Journal of Fluid Machinery
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• v.10 no.6
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• pp.32-37
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• 2007

Aerodynamic forces and moments have been used to control rocket propelled vehicles. If control is required at very low speed, Those systems only provide a limited capability because aerodynamic control force is proportional to the air density and low dynamic pressure. But thrust vector control(TVC) can overcome the disadvantages. TVC is the method which generates the side force and roll moment by controlling exhausted gas directly in a rocket nozzle. TVC is classified by mechanical and fluid dynamic methods. Mechanical methods can change the flow direction by several objects installed in a rocket nozzle exhaust such as tapered ramp tabs and jet vane. Fluid dynamic methods control the flight direction with the injection of secondary gaseous flows into the rocket nozzle. The tapered ramp tabs of mechanical methods are used in this paper. They installed at the rear in the rocket nozzle could be freely moved along axial and radial direction on the mounting ring to provide the mass flow rate which is injected from the rocket nozzle. In this paper, the conceptual design and the study on the tapered ramp tabs of the thurst vector control has been carried out using the supersonic cold flow system and schlieren system. This paper provides the thrust spoilage, three directional forces and moments and distribution of surface pressure on the region enclosed by the tapered ramp tabs.

• Journal of the Korean Society of Physical Medicine
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• v.12 no.2
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• pp.53-57
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• 2017

PURPOSE: The purpose of study was to clear up the environmental risk factor that can be easily occurred unstability of hip during gait and one leg standing at various ramp angle. METHODS: Twenties healthy males of 69 subjects is participated in this study. Participants was measured activation on gluteus medius muscle during both conditions (walk across the ramp and one leg stand in the transverse direction) of seven different angle. The measured data were analyzed using one-way ANOVA to investigate the effect of muscle activation on the each condition. The statistical analyses were performed using SPSS ver. 18.0 and p-value less than .05 were considered significant for all cases. A post-hoc test was performed by Bonferoni method. RESULTS: The study showed that more muscle activities on gluteus medius is increased by increasing the ramp angle. Post-hoc analysis demonstrated that the peak and mean of muscle activity increased significantly with a ramp angle of $15^{\circ}$ and $25^{\circ}$ during gait and one-leg stand. CONCLUSION: According to the study results, impaired balance can be easily occurred when cross walk and one-leg stand on a ramp from higher than $15^{\circ}$, and highest risk was angle of $25^{\circ}$ or more. As a people with gluteus medius muscle weakness walks a ramp, the ramp angle has a cross relationship with the impaired balance. If people with gluteus medius weakness walk on the more than $10^{\circ}$ of ramp angle, they will need a lot of attention for prevent impaired balance.

• Journal of the Korea Society of Computer and Information
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• v.17 no.1
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• pp.211-218
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• 2012

Fossil fuel is used all over the world and it produces greenhouse gases due to fossil fuel use. Therefore, it cause global warming and is serious environmental pollution. In order to decrease the environmental pollution, we should use renewable energy which is clean energy. Among several renewable energy, wind energy is the most promising one. Wind power generation is does not produce environmental pollution and could not be exhausted. However, due to wind power generation has irregular power output, it is important to predict generated electrical energy accurately for smoothing wind energy supply. There, we consider use ramp characteristic to forecast accurate wind power output. The ramp increase and decrease rapidly wind power generation during in a short time. Therefore, it can cause problem of unbalanced power supply and demand and get damaged wind turbine. In this paper, we make prediction models using power ramp rate as well as wind speed and wind direction to increase prediction accuracy. Prediction model construction algorithm used multilayer neural network. We built four prediction models with PRR, wind speed, and wind direction and then evaluated performance of prediction models. The predicted values, which is prediction model with all of attribute, is nearly to the observed values. Therefore, if we use PRR attribute, we can increase prediction accuracy of wind power generation.

• PNF and Movement
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• v.16 no.3
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• pp.415-424
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• 2018

Purpose: This study aimed to determine the effects of various wheelchair handling directions on the upper limb muscle activities of wheelchair attendants while climbing a ramp. Methods: For the study participants, healthy males over 20 years of age were chosen, and the order of the direction of wheelchair handle grip was determined using a randomized method. The handling directions for pushing the wheelchair up a ramp included a general grip with ulnar deviation, a medial grip with wrist pronation, and a neutral grip with a neutral wrist. The muscle activities in the participants' upper limbs were measured using surface electromyography. For statistical data processing, SPSS 18.0 was used to perform repeated measures ANOVA in order to compare the muscle activity among the intervention groups. A contrast test was also conducted among the participants. The significance level (${\alpha}$) was set to 0.05. Results: There was a significant difference between groups using a general grip and a medial grip in the biceps brachii, triceps brachii, and flexor carpi radialis muscles (p<0.05). There was also a significant difference between using a general grip and a neutral grip in the biceps brachii and flexor carpi radialis muscles (p<0.05), and there was a significant difference between using a medial grip and a neutral grip in the biceps brachii and extensor carpi radialis brevis muscles (p<0.05). Conclusion: In this study, the wheelchair assistants' wrist muscle activity was the lowest with a neutral grip while ascending a ramp. Accordingly, this study proposes that wheelchair assistants push wheelchairs up ramps with a neutral grip.