• 제어로봇시스템학회논문지
• /
• 제8권9호
• /
• pp.764-775
• /
• 2002

A kinematic and dynamic optimal design of a new parallel-type rolling mill based upon Stewart platform manipulator is investigated. To provide sufficient degrees-of-freedom in the rolling process and the structural stability of each stand, a parallel manipulator with six legs is considered. The objective of this new parallel-type rolling mill is to permit an integrated control of the strip thickness, strip shape, pair crossing angle, uniform wear of the rolls, and tension of the strip. By splitting the weighted Jacobian matrices Into two parts, the linear velocity, angular velocity, force, and moment transmissivities are analyzed. A manipulability measure, the ratio of the manipulability ellipsoid volume and the condition number of a split Jacobian matrix, is defined. Two kinematic parameters, the radius of the base and the angle between two neighboring Joints, are optimally designed by maximizing the global manipulability measure in the entire workspace. The maximum force needed in the hydraulic actuator is also calculated using the structure determined through the kinematic analysis and the Plucker coordinates. Simulation results are provided.

• 한국자동차공학회논문집
• /
• 제11권3호
• /
• pp.145-154
• /
• 2003

Occupant simulation models have been used to study trends or specific design changes in several typical crash situations. The ATB, Articulated Total Body, was developed and used to predict gross human body responses to vehicle crashes and pilot ejections. Since the ATB source code is open to public, the user can add their own defined modules and functions. The introduction of seat belts into cars significantly decreased the injury risk of passengers in frontal impacts. In this paper, a new seat belt model was developed and implemented into the ATB. For this purpose, a subroutine of the new seat belt was constructed. A force-deflection function was added to replace an existing function to consider energy absorption. The function includes hysteresis effects of the experiment data of the loading and unloading parts of the seat belt load-extension curve. Moreover, this belt model considers a slip between ellipsoid and belt segments. This paper attempted to validate the ATB program which includes the subroutine of new belt models comparing with the real car frontal crash experiments and MADYMO frontal models. The analysis focusses on the human movement and body accelerations.

• Mycobiology
• /
• 제47권4호
• /
• pp.401-407
• /
• 2019

Two new species of the lichen genus Placolecis are discovered in China, namely P. kunmingensis An. C. Yin & Li S. Wang and P. sublaevis An. C. Yin & Li S. Wang. The new combination P. loekoesiana (S.Y. Kondr., Farkas, J.J. Woo & Hur) An. C. Yin is proposed. Placolecis kunmingensis is characterized by having simple, spherical or ellipsoid, hyaline spores, and pear-shaped pycnidia; while P. sublaevis can be distinguished by its thallus forming larger aggregations with slightly flattened lobes at the thallus margin, and urn-shaped pycnidia. Descriptions, a phylogenetic tree and a key are provided for all the known Placolecis species in China.

• 제어로봇시스템학회:학술대회논문집
• /
• 제어로봇시스템학회 2003년도 ICCAS
• /
• pp.2713-2718
• /
• 2003

Some of manufacturing tasks such as sawing task often requires continuous impulsive motion. In case of sawing task, such impulsive motions can be observed between the teeth of the saw and the object. The amount of the external impulse exerted on the object has been treated as an important control parameter. The purpose of this work is to introduce a new concept of an effective mass in sawing task and to suggest an external impulse model in sawing task. A normalized impulse ellipsoid reflecting the velocity direction is employed to visualize the impact geometry. Experiments are performed for soft and hard workpieces to justify the external impulse model in the sawing task. It is demonstrated through simulation and experiment that the proposed external impulse model is effective to characterize the impact property.

• 한국정밀공학회지
• /
• 제18권6호
• /
• pp.109-114
• /
• 2001

Forming pressure of the rupture disc has been analyzed theoretically and verified by experiments. Final shape of the rupture disc after forming process is assumed to be hemi-ellipsoid for small height of the rupture disc. The predicted forming pressures are in good agreement with those by experiment. A new simple model has been proposed to predict the burst pressure of the rupture disc. Experimental results show that the proposed model of burst pressure describes the bursting characteristics of the rupture disc very well.

• Journal of the Optical Society of Korea
• /
• 제20권2호
• /
• pp.234-238
• /
• 2016

A new method to design a low distortion, even relative illumination, optical see-through head-mounted display (HMD) with a freeform reflective mirror (FFRM) based on the two similar ellipsoids structure is proposed. The HMD we have realized has a simple structure which consists of two similar ellipsoid surfaces, an FFRM, a 7-piece co-axis relay lens, and an OLED. This structure can be applied to offset distortion, reach even relative illumination, and correct the off-axis aberrations. The HMD we finally have realized has a near 3% low distortion, a higher than 80% relative illumination, and a 40°×30° field of view (FOV).

• International Journal of Control, Automation, and Systems
• /
• 제5권2호
• /
• pp.218-222
• /
• 2007

This paper presents a new Perfect Tracking Control (PTC) scheme for linear systems with state constraint. The proposed controller increases the number of the steps on-line for perfect tracking to satisfy the given ellipsoid-type state constraint. The unavoidable step delay that we impose is minimized by solving LMI feasibility problems and the possible feedback information loss is avoided. The proposed schemes are easy to develop, theoretically simple and clear, and include the conventional PTC as its special case.

• 한국식물병리학회지
• /
• 제11권1호
• /
• pp.98-99
• /
• 1995

A disease causing fruit rot and leaf and vine blight on watermelon was found in Euseong in July, 1991 and in Bonghwa, Kyungpook province in August, 1993. Abundant zoosporangia characteristics of Phytophthora capsici were formed on the surface of the infected fruits. The zoosporangia were ovoid to ellipsoid, tapering to the base and with conspicuous papilla. The fungus isolated from the infected fruits was pathogenic on seedlings of watermelon, pumpkin, and pepper. The morphological characteristics and host range agreed with those of P. capsici. The watermelon disease caused by P. capsici was reported long time ago in Japan and America but rot yet in Korea. Thus, the disease on watermelon caused by P. capsici is reported as a new record in Korea.

• International Journal of Fuzzy Logic and Intelligent Systems
• /
• 제3권1호
• /
• pp.100-104
• /
• 2003

The SVDD(support vector data description) is one of the most well-known one-class support vector learning methods, in which one tries the strategy of utilizing balls defined on the kernel feature space in order to distinguish a set of normal data from all other possible abnormal objects. The major concern of this paper is to consider the problem of modifying the SVDD into the direction of utilizing ellipsoids instead of balls in order to enable better classification performance. After a brief review about the original SVDD method, this paper establishes a new method utilizing ellipsoids in feature space, and presents a solution in the form of SDP(semi-definite programming) which is an optimization problem based on linear matrix inequalities.

• 제어로봇시스템학회논문지
• /
• 제6권1호
• /
• pp.112-119
• /
• 2000

A die-casting junction method is usually used to manufacture the tub of an IH(induction heating) jar. If there is a very small air bubble in the junction area, the thermal conductivity is deteriorated and local overheat occurs. Such problem brings serious inferiority of the IH jar. In this paper, we propose a new method to detect such defect with simply measured thermal data. Thermal distribution of preheated tubs is obtained by scanning with infrared thermal sensors and analyzed with the statistic pattern recognition method. By defining the characteristic feature as the temperature difference between sensors and using ellipsoid function as decision boundary, a supervised learning method of genetic algorithm is proposed to obtain the required parpameters. After applying the proposed method to experiment, we have proved that the rate of recognition is high even for a small number of data set.