• Journal of Advanced Navigation Technology
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• v.15 no.3
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• pp.441-448
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• 2011

It is very important that establishing the valve train equations and representing the behavior of the valve train parts. To maintain the specific efficiency of running engine, the cam profile of valve train has more specific influence on the adequate behavior of the valve train than a valve clearance, heat-resistance and durability of parts. The polynomial cam, the multipol cam and polydyne cam profie are widely used to represent cam behaviour. In this study, using polydyne cam design profile equations which is more adequate for representing high speed engine, the geometrical modeling and mathmatical variable analysis are established to analysis the valve behaviour.

• Journal of Biomedical Engineering Research
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• v.10 no.3
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• pp.269-278
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• 1989

The initial impact at foot strike is produced by a slider type mechanical model, which can be measured using a force platform to evaluate various shoes. The lower extremity and foot motion was filmed by a 16mm high speed movie camera and several points on the rear half of the shoe and those near the trochanter and the lateral epicondyle were digitized to provide the linear and angular positions and velocities during impact. With these observed kinematics, a slider type foot strike simulator composed of guide rail and sliding dummy is designed. The simulator system makes the artificial foot of the dummy with running shoe on it to follow the foot strike motion. The dummy has the relevant mass-spring-damper system modeled after McMahon's. The motion of the model is drived by the gravity force and the generated motion alone with the ground reaction forces are monitored by the same procedures afore mentioned producing the initial foot strike impact similar to the onto observed in human gait.

• Journal of the Korean Society for Railway
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• v.12 no.6
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• pp.852-858
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• 2009

This paper is a study on the reliability management of onboard signaling equipment for the Koran Tilting Train (TTX) to run the existing railway to express railway. For safe running of tilting train which operates at Automatic Train Protection (ATP) and Automatic Train Stop (ATS), a reliability management plan for TTX onboard is proposed for preventing train safety from driver oversight and malfunction by establishing braking curves based on movement authority and speed limit, according to preceding train location and rail conditions. Also, reliability of TTX onboard equipment on the basis of proposed plan was estimated, and actual case studies based on the international requirements IEC 62278 (EN 50126) were provided to verify its reliability.

• Journal of the Semiconductor & Display Technology
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• v.4 no.1 s.10
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• pp.61-64
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• 2005

This study presents a new algorithm to detect the facial feature in a color image entered from the mobile device with complex backgrounds and undefined distance between camera's location and the face. Since skin color model with Hough transformation spent approximately 90$\%$ of running time to extract the fitting ellipse for detection of the facial feature, we have changed the approach to the simple geometric vector operation, called a TS(Triangle-Square) transformation. As the experimental results, this gives benefit of reduced run time. We have similar ratio of face detection to other methods with fast speed enough to be used on real-time identification system in mobile environments.

• Proceedings of the IEEK Conference
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• 2009.05a
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• pp.372-374
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• 2009

In this research, an obstacle avoidance method is proposed. The common usage of a robot is indoor and the obstacles to the indoor robot is studied. The accurate detection of direction after overcoming the obstacles is necessary for performance of autonomous navigation and mission project. The sensors such as Laser, Ultrasound, PSD can be used to measure the obstacles. In this research, a PSD sensor is used to detect obstacles. It detects the height and width of obstacles located on the floor. Before measuring the obstacles, a calibration of the sensor was done and it produced a better accuracy. We have plotted an error graph using data obtained from the repeated experiments. The graph is fitted to a polynomial curve. The polynomial equation is used for the robot navigation. And in this research, a model of the error of the direction of the robot after overcoming obstacles was obtained also. The prototype of the obstacle and the error of the direction after overcoming the obstacles are modelled using a neural networks. The input of the neural network composed with the height of the obstacles, the speed of robot, the direction of wheels and the error of the direction. To implement the suggested algorithm, we set up a robot which is operated by a notebook computer. Experiment showed the suggested algorithm performed well.

• The Bulletin of The Korean Astronomical Society
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• v.42 no.2
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• pp.62.2-62.2
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• 2017

We have made an investigation on the radial and azimuthal wave modes of full halo coronal mass ejections (HCMEs). For this, we consider 24 HCMEs which are simultaneously observed by SOHO and STEREO A & B from August 2010 to August 2012 when they were roughly in quadrature. Using the SOHO/LASCO C3 and STEREO COR2 A & B running difference images, we estimate the instantaneous apparent speeds of the HCMEs at 24 different position angles. Major results from this study are as follows. First, there are quasi-periodic variations of the instantaneous radial velocity with the periods ranging from 24 to 48 mins. Second, the amplitudes of instant speed variations are about a third of the projected speeds. Third, the amplitudes are found to have a weak anti-correlation with period. Our preliminary identification from SOHO observations shows that there are several distinct radial and azimuthal wave modes: m=0 (radial) for five events, m=1 for eleven events, m=2 for three events, and unclear for the other events. In addition, we are making a statistical investigation on the oscillation of 733 CMEs to understand their physical origins.

• Journal of Advanced Marine Engineering and Technology
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• v.28 no.3
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• pp.482-492
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• 2004

Recently. the market trend for marine diesel engine has involved the lower running speeds. larger stroke/bore ratio and higher combustion pressure. Consequently, because of the flexible engine shafting system due to the larger mass. inertia and the more elasticity, the complicated coupled torsional-axial vibrations have occurred in the operating speed range. Also, the vibrations act as an excitation on the hull-structural vibration. To predict the vibration behavior with more accuracy and reliability. many studies have proposed the several kinds of method to calculate the stiffness matrix of crankshaft. However, most of these methods have a weak point to spend much time on three dimensional modeling and meshing work for crankshaft. Therefore. in this work. the stiffness matrix for the crankthrow is calculated using the energy method (Influence Coefficient Method, ICM) with the each mass having 6 degree of freedom. Its effectiveness is verified through the comparison with the stiffness matrix obtained by using the finite element method (FEM) and measured results for actual ships propulsion system.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.23 no.7 s.166
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• pp.1155-1163
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• 1999

This study deals with the vibration ride quality for passenger car when running on straight highway at the speed of 70km/h. Ten accelerations were measured at four positions, three axes each at the feet, hip, and head, and one axis at the back. Five seats that have different static sponge stiffness were used, and two subjects were participated. These accelerations were analyzed to produce the ride values such as component ride value and overall ride value. It was hard to see the difference of ride value by the change of sponge stiffness. However we could rank the ride quality by the total vibration exposed to passengers. From the transfer function between the hip and the foot, the fundamental mode was observed to be around 5.8Hz. Also the transfer function between the head and hip was studied. The optimal damping ratio of the seat was calculated according to the seat natural frequency with human weighting filter which makes the optimal damping ratio different from that without weighting filter.

• Proceedings of the Korean Society of Marine Engineers Conference
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• 2006.06a
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• pp.273-274
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• 2006

The sea is origin of all lift, and 90% of the all living organisms are in the sea. The biosynthesis is very different. Many organisms are kept on a lower or developed to another evolutionary level than on shore. Our society is increasing demand and need for marine food and this food has to product at onshore or offshore fish farming sites. Ocean fish farms have a special operation properties such as a good quality water, net cage, sheltered locations and feeding system. The farming site is controlled and monitored for fish welfare as ammonia($NH_3$), temperature, the speed of a running fluid. Specially, the fish farm is seriously influenced by ammonia. In this paper, $NH_3$ monitoring system for ocean fish farm is researched for the suitable fish farming sites, and test equipment is designed for achieving practical data. The equipment wit monitoring algorithm is expected to the useful system for ocean fish farm.

• Journal of the Korean Society of Manufacturing Technology Engineers
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• v.24 no.5
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• pp.576-582
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• 2015

Generally, the fuel economy of hybrid electric vehicle (HEV) is effected by the size of each component. In this study the fuel economy for HEV of our own making is evaluated using backward simulator, where dynamic programming is applied. In a competition, the vehicle is running through the road course that includes many speed bumps and steep grade. Therefore, the new driving cycle including road grade is developed for the simulation. The backward simulator is also developed through modeling each component. A performance map of engine and motor for component sizing is made from the existing engine map and motor map adapted to the HEV of our own making. For optimal component sizing, the feasible region is defined by restricting the power range of power sources. Optimal component size for best fuel economy is obtained within the feasible region through the backward simulation.