• Journal of Navigation and Port Research
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• v.37 no.6
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• pp.575-580
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• 2013

The IMU(Inertial Measurement Unit) which is the expensive equipment has been used as a special limited area, usually in measurement of posture of applying to the areas of ship, submarine, aircraft and military equipment application. However, in the current situation, MEMS AHRS technology can replace the high-priced IMU in MEMS AHRS selected application field. In this paper, wireless hull motion measurement system was suggested for measuring key elements of ship's movement such as rolling, pitching and yawing using gyro, acceleration and magnetic sensors of AHRS. In order to reduce the error such as instantaneous acceleration, effects and vibration of geomagnetic, we have adopted the sensors equipped with Kalman filtering. The Wireless hull motion measurement system using AHRS sensors was tested in actual ship and it could easily be applied in limited installation circumstances of the ship. In the future, this system can be useful in the navigation safety and marine accident analysis by using with ship equipment such as INS or VDR in the maritime.

• Horticultural Science & Technology
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• v.30 no.4
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• pp.449-462
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• 2012

The objectives of this study were to measure the range of motion for joints and muscle activation of upper limb for flower arrangement tasks for physical rehabilitation and to test horticultural therapy programs using flower arrangement tasks for improving upper limb function of the patients with stroke. Major flower arrangement tasks were classified with eight tasks (cutting 1, thick stem; cutting 2, thin stem; fixing 1, long stem; fixing 2, short stem; rolling a leaf; bending 1, thick stem; bending 2, thin stem; and winding, using a wire) based on the occupational analysis. When eight male university students (mean age $24.1{\pm}2.5$ years) conducted the eight flower arrangement tasks, range of motion for joints and muscle activation of upper limb were measured by a 3D motion analyzer and electromyography, respectively. Based on the results of the range of motion and muscle activation of upper limb, horticultural therapy programs using flower arrangement tasks (total 33 sessions) for improving upper limb function of the patients with stroke was conducted at a rehabilitation hospital, Seoul, South Korea and then the range of motion, grip strength, and upper limb function of the patients were tested. Among the eight flower arrangement tasks, cutting 1, winding, and bending 1 induced the highest value for the range of motion in joints of shoulder, elbow, and wrist, respectively (P < 0.001). In terms of muscle activation, eight flower arrangement tasks performed in this study showed various patterns of muscle activation and several muscles were simultaneously used for each task (P < 0.001). In addition, thickness and length of the materials used in a task had a prominent effect on the range of motion for joints and muscle activation of upper limb (P < 0.001). The stroke patients had positive effects for their range of motion of upper limb (shoulder, forearm, and elbow), grip strength, and overall upper limb function through the horticultural therapy program. Thus, this study suggested that flower arrangement tasks would be a potential horticultural activity for physical rehabilitation program. It would be interesting to apply a customized horticultural therapy program using flower arrangement tasks according to the symptoms of patient for physical rehabilitation.

• Proceedings of the KSME Conference
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• 2007.05a
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• pp.590-595
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• 2007

It is important to predict the collision behavior of a train consist to improve its crashworthiness. To analyze crash behavior of train, four kinds of methods are mainly used so far. The first is method using multibody dynamics to predict the gross motion of the train set. The second uses 3D FE model to apply the section analysis method in order. The third is used to deduce design specification and evaluate the crashworhiness of a train by using 1D model. The last is to constitute 2D model to check overriding and coupling devices. The train evaluation procedures are so complex that it is difficult to understand or deal with. In this study, VTM for railway train was introduced to simplify the procedures. VTM involves 3D models, 1D models and dynamic components such as suspension and coupling. The method using hybrid concept model makes it possible to do all the things that are mentioned above. To analyze crash behavior tendency of VTM, the model was simulated and the simulation results were discussed.

• Wind and Structures
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• v.18 no.5
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• pp.511-528
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• 2014

The characteristics of wake galloping phenomenon for two parallel/unparallel circular cylinders were investigated via wind tunnel tests. The two cylinders were initially deployed in parallel and wake galloping phenomena were observed by varying the center-to-center distance. The effect of an unparallel arrangement of two cylinders was next investigated by fixing the spacing ratio of one side of the cylinders at 5.0D and the other side at 3.0D, in which D represents the diameter of the cylinder. For the unparallel disposition, the 5.0D side showed a small, limited vibration while the 3.0D side produced much larger amplitude of vibration, resulting in a rolling motion. However, the overall amplitude appeared to decrease in unparallel disposition when compared with the amplitude of the 3.0D - 3.0D parallel case. This represents the mitigation effect of wake galloping due to the unparallel disposition between two cylinders. Flow visualization tests with particle image velocimetry were conducted to identify flow fields between two cylinders. The test results demonstrate the existence of a complex interaction of the downstream cylinder with the shear layer generated by the upstream cylinder. When the spacing ratio was large enough, the shear layer was not observed and the downstream cylinder showed only limited random vibration.

• The Journal of the Acoustical Society of Korea
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• v.14 no.2
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• pp.80-91
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• 1995

A theoretical models has been prepared which describes the noise generated by tire/road interaction for the tire structure-borne sound analysis. The model begin with a set of thin shell equations describing the motion of the belt of a radial ply tire, as drived by Bohm('mechanisms of the belted tire', Igeniur-Archiv, XXXV, 1966). Structural quantities required for these equations are derived from material properties of the tire. The rolling shape of a tire is computed from the steady-state limit of these equations. Vibrational response of the tire is treated by the full dependent shell equations. The force input at the tire/road interface is calculated on the basis of tread geometry and distribution of contact patch pressure. Radiation of noise is calculated by a simpson integral. Using the programs, the effect on noise of various tire design variations is computed and discussed. Trends which lead to quiet tire design are identified.

• 연구논문집
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• s.27
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• pp.57-73
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• 1997

The bogie between the track and the railway vehicle body, is one of the most important component in railroad vehicle. Its effects on the safety of both passengers and vehicle itself, and on the overall performance of the vehicle such as riding quality, noise and vibration are critical. The bogie is mainly consisted of the bogie frame, suspensions, wheels and axles, braking system, and transmission system. The complex shapes of the bogie frame and the complicate loading condition (both static and dynamic) induced in real operation make it difficult to design the bogie frame fulfilling all the requirements. The complicated loads applied to the bogie frame are i) static load due to the weight of the vehicle and passengers, ii) quasi-static load due to the rolling in curves iii) dynamic load due to the relative motion between the track, bogie, and vehicle body. In designing the real bogie frame, fatigue analysis based on the above complicated loading conditions is a must. In this study, stress analysis of the bogie frame has been performed for the various loading conditions according to the UIC Code 6 15-4. Magnitudes of the stress amplitude and mean stress were estimated based on the stress analysis results to simulate the operating loads encountered in service. Fatigue strength of the bogie frame was evaluated by using the constant life diagram of the material. 3-D surface modelling, finite element meshing, and finite element analysis were performed by Pro-Engineer, MSC/PATRAN, and MSC/NASTRAN, respectively.

• Journal of the Korean Society for Precision Engineering
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• v.24 no.2 s.191
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• pp.95-102
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• 2007

A feeding system is a key component in manufacturing packing boxes such as printing, slotting and gluing. The role of the feeding system is to feed corrugate cardboards which is usually tick and large. So, a special method is necessary to feed corrugate cardboards. This paper suggests a concept and an automatic feeding machine to feed corrugated cardboards using TRIZ, the theory of inventive problem solving. The automatic feeding machine consists of units to regulate the machine according to length and width of corrugated cardboards, a feeding part with a plurality of small rollers, and a sucking part which intensify frictional force between rollers and the lowest feeding cardboard. In particular, the feeding part is composed of an up-and-down motion plate with holes to suck the lowest corrugated cardboard as well as small rolling rollers after stopping in a moment. Thus this machine does not sensitive to size of corrugated cardboards and also can keep feeding accuracy during feeding fast.

• Proceedings of the SAREK Conference
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• 2009.06a
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• pp.904-909
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• 2009

In this paper, a rolling piston rotary compressor having a combined vane and roller unit has been introduced. In a conventional rotary compressor, sliding motion takes place between the vane nose and roller. By combining the vane and the roller in one unit, gas leakage through a clearance between the vane nose and the roller can be eliminated, and the frictional loss between them can also be reduced to almost nought. Compressor model with the combined vane and roller has been fabricated and tested in a compressor calorimeter and computer simulation program has been developed to confirm merits of the new mechanism. In a test, cooling capacity has been found to be increased by 1.4%, and the compressor input decreased by 0.3%, resulting in 1.7% increased in EER. Simulation program confirmed the calorimeter test results and the merits of the new model as mentioned above.

• Journal of the Korean Society for Precision Engineering
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• v.30 no.12
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• pp.1327-1333
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• 2013

Air bearings are widely used in precision stages because of low friction and high motion accuracy, however, they suffer from low stiffness in comparison with rolling bearings or hydrostatic bearings. So, several preloading methods using weight, magnet and vacuum force, and opposing pads have been used to increase the stiffness of the air bearings. In this paper, pressure distributions of the vacuum preloaded porous air bearings are calculated using the proposed method. And then, the load capacity and stiffness are analyzed. For the vacuum preloaded air bearings, the stiffness is increased owing to reduced bearing clearance by vacuum force. The simulation results indicate that variation of vacuum pressure with clearance in the vacuum pocket gives rise to low stiffness, so the vacuum pocket should be designed for pressure to be constantly maintained regardless of the bearing clearance by means of large effective pumping speed.

• Proceedings of the KSME Conference
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• 2003.11a
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• pp.1051-1055
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• 2003

Aluminum carbody for rolling stocks is light and perfectly recycled, but includes severe defects which are very dangerous to fatigue strength. Structural integrity assessment for the carbody by static load test has been performed up to date. In this study, to evaluate fatigue strength of the aluminum carbody of urban transit unit. a testing method to simulate dynamic loading condition was proposed and the fatigue strength of the carbody was evaluated. The dynamic load test results showed that the alternating stress ranges were different from the estimated ranges based on the static test results. Excessive stress ranges at the center are thought to come from the flexible motion of the carbody. published fatigue test data for aluminum components, but variation of alternating acceleration along the length due to flexibility of carbody yielded unexpected results. Because fatigue strength based on the static test results may be overestimated at the center, modification of testing method is necessary.