• Journal of the Korean Society for Precision Engineering
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• v.20 no.3
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• pp.210-220
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• 2003

This work presents a method of point to surface assignment fur 3D metrology of solder pastes on PCB. A bounding box enclosing the solder paste tightly on all sides is introduced to avoid incorrect assignment. The shape of bounding box fur solder paste brick is variable according to geometry of measured points. The surface geometry of bounding box is obtained by using five peaks selected in the histogram of normalized gradient vectors. By using the bounding box enclosing the solder pastes, the task of point-to-surface assignment has been successfully conducted, then geometrical features are obtained through the task of surface fitting.

• Journal of the Korean Society for Precision Engineering
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• v.20 no.3
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• pp.82-88
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• 2003

The nondestructive internal quality evaluation of agricultural products has been strongly required from the needs for individual inspection. Recently, the ultrasonic wave has been considered as a solution fur this problem, and an ultrasonic system was constructed for the ultrasonic NDE of fruits and vegetables in our previous work. In this paper, the practical applicability of our ultrasonic system is tested fur the inspection of internal defects (central cavity) in Atlantic potato. Sound speed and RMS of transmitted ultrasonic wave signal were measured and classification algorithm using 2 dimensional stochastic analysis. was presented. Experimental results showed greater value of sound speed and RMS (root mean square) of transmitted signal in normal samples than in abnormal samples with cavity. Also a stochastic method to distinguish normal and abnormal showed fault detection rate less than 5%.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2005.10a
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• pp.94-99
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• 2005

Though the technology on the ultra-precise machining has been developed intensively, the high speed and high precision for large machining range is still very hard to achieve. The linear motor system fur the universal machining center is proper fur high speed and high precision, but it has drawback of sensitivity to disturbance. In this research, two degrees of freedom controller based on the zero phase error tracking controller (ZPETC) and disturbance observer are proposed to improve the tracking performance and dynamic stiffness of linear motor system. The proposed controller is verified in simulations and experiments on a nano-positioner system, and the experimental result shows that the tracking performance improved. In addition, the PID optimization method is proposed for the commercialized controller such as the PMAC based system. The tracking as well as impedance is included in the cost function of optimization.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2005.10a
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• pp.938-941
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• 2005

Recently We make a study of the process expert system model in 2005 process expert system concepts is applied to the digital meister expert system development. Well-designed expert systems imitate the reasoning processes experts use to solve specific problem. Specially, expert systems are used to the engineer in manufacturing industry fur the process control, production management and system management. In this paper, we propose the digital moister expert system fur product design process in manufacturing industry and we present introduction and contents of design process expert system methodology and software far the air purifier design system.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2005.10a
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• pp.366-369
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• 2005

Electrochemical discharge machining (ECDM) has been found to be potential fur the micro-machining of non-conductive materials such as ceramics or glass. However this machining process has its own inherent problem that the reproducibility is too low to get the available geometric accuracy fur micromachining applications. One main challenge in reaching this goal is the control of the hydrogen built around the tool-electrode in which happen the discharges. This paper proposes the methods to improve the geometric accuracy using powder-mixed ECDM process. The experimental results show the effects of powder producing improved geometric accuracy by averaging and decreasing the concentration of spark energy.

• Korean Journal of Organic Agriculture
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• v.15 no.3
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• pp.277-290
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• 2007

This study has been analyzed an execution example of the life cycle assessment on the packaged bean-curd of P company, the first case of the regular life cycle assessment on the processed foods in Korea and considered on the significance and directions of the life cycle assessment on the foods. It is possible to divide the potential environmental impact through the life cycle of the bean-curd into six categories and analyze the environmental impact on the production, use and disposal phases of the product. The values of each environmental impact have been quantified from the strength of the potential impact fur the corresponding category of impact. In the future, it is expected that the result of the lift cycle assessment will be increasingly used fur many areas such as Climate Change Convention and ISO22000, etc. and it is required to promote a project to make database through the assessment on the individual corps or types of businesses for it from now on.

• Coupled systems mechanics
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• v.3 no.1
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• pp.73-88
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• 2014

The paper deals with a model founded on the physical processes in concrete subject to high temperatures. The model is developed in the framework of continuum damage mechanics and the theory of porous media and is demonstrated on selected structures. The model comprises balance equations for heat transfer, mass transfer of water and vapour, for linear momentum and for reaction. The balance equations are completed by constitutive equations considering the special behaviour of concrete at high temperatures. Furthermore, the limitation and decline of admissible stresses is achieved by using a composed, temperature depending crack surface with a formulation for the damage evolution. Finally, the complete coupled model is applied to several structures and to different concrete in order to determine their influence on the high-temperature-behaviour.

• Proceedings of the KSR Conference
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• 1998.11a
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• pp.545-552
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• 1998

A study on collision analysis of TGV-K using a 2-dimensional model is described to evaluate its crashworthiness. Two-dimensional analysis gives good information on overriding behaviour and impact forces applied to interconnecting devices such as side buffers, ball & socket joints, hooks, pins, and fingers. Since the headstock of TGV-K is not designed in a crashworthy point of view, its conceptual design fur KHST(Korean High Speed Train), under development, is suggested to improve crashworthiness. The suggested design, which adopts an energy absorber and a crashworthy headstock, is compared with the conventional headstock on dynamic behaviour to the vertical direction under the accident scenario of SNCF (collision at 110km/h against a movable rigid mass of 15 ton). It is concluded that the design modification make little difference in vertical motion. To evaluate validation of the 2-dimensional model, the results fur longitudinal motion is compared with those of 1-dimemsional one. It is found that the two results are in good agreements.

• Proceedings of the Korea Association of Crystal Growth Conference
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• 1999.06a
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• pp.51-67
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• 1999

The growth of crystals with high melting points tfus$\geq$1$600^{\circ}C$ faces the researcher with experimental problems, as the choice of materials that withstand such high t is rather limited. Many metallic construction materials are in this high t range already molten or exhibit at least a drastically reduced mechanical strength. The very few materials with tfus》1$600^{\circ}C$ as e.g. W, Mo, and partially even Ir are more or less sensitive against oxygen upon heating. Whenever possible, high t crystal growth is performed under inert atmosphere (noble gases). Unfortunately, any oxides are not thermodynamically stable under such conditions, as reduction takes place within such atmosphere. A thoroughly search for suitable growth conditions has to be performed, that are on the one side "oxidative enough" to keep the oxides stable and on the other side "reductive enough" to avoid destruction of constructive parts of the crystal growth assembly. The relevant parameters are t and the oxygen partial pressure pO2. The paper discusses quantitatively relevant properties of interesting oxides and construction materials and ways to forecast their behavior under growth conditions.r growth conditions.

• Nuclear Engineering and Technology
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• v.56 no.3
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• pp.824-831
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• 2024

In order to investigate the occurring processes during long-term dry storage of spent fuel assemblies, a joined project called SPIZWURZ, between the Karlsruhe Institute of Technology and the Gesellschaft für Anlagen-und Reaktorsicherheit (GRS), was started. Aim of the SPIZWURZ project is the determination and quantification of the influence of texture and elastic strain on diffusion and solubility of hydrogen in three different zirconium alloys used in western Europe during a long-term cooling transient (1 K/d) starting at 400 ℃. The strain in the cladding of an irradiated spent fuel rod shall be measured. Models predicting the formation of radial oriented hydrides will be validated, improved, and implemented in the GRS fuel rod performance code TESPA-ROD. This paper describes the SPIZWURZ project and already obtained first results.