• Journal of the Korean Society of Manufacturing Technology Engineers
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• v.9 no.5
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• pp.157-164
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• 2000

A machine tool generally has some serious stability problems in the form of tool chatter during the cutting process. Chatter vibration deteriorates the surface finish, reduce tool and machine life, accelerates machine tool system component wear, and may lead to an unacceptable noise sound in the working environment. In this study, the behavior of spectral density of AE signal and principal cutting force signal in order to monitor the chatter vibration in the cutting process has been investigated. From the results, the reliability of proposed monitoring method has been confirmed.

• Journal of Korea Society of Digital Industry and Information Management
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• v.5 no.1
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• pp.127-139
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• 2009

Recently a rapid development of Information Technology including Internet have brought new way of education such as Distance education, Cyber University, Home Schooling and so on. This change of education have also brought about the change of a tool and medium for education. It is a using multimedia contents in education. Using the multimedia learning contents on line education is considered as one of new way of education and expected to bring learner's better performance. Therefore, it's necessary to research online education contents and its design. In this paper, we discussed how the multimedia contents should be designed to help to reinforce what the learner have learned and researched a critical factor of online contents to effect on learner's better performance.

• Journal of the Korean Society of Industry Convergence
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• v.9 no.4
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• pp.247-253
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• 2006

Power consumption for double-stage paddle impeller in spherical and cylindrical agitated vessel was measured over a wide range of Reynolds number from laminar to turbulent flow regions. The power correlation was obtained which was applied to both spherical and cylindrical vessel, when the apparent diameter of the spherical vessel was equal to the diameter of the cylindrical vessel which had a height equal to its diameter and had the same volume as the spherical vessel. The power consumption for the double-stage impeller was dependent upon the distance of among the impeller in the agitated vessels, as follows: $$f/2={\frac{C_L}{Re_G}}+{\frac{Ct}{2}}({\frac{C_tr}{Re_g}}+Re_g)^{-m}$$

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.13 no.5
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• pp.407-415
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• 2002

In this paper, mutual coupling effect between antennas mounted on UAV(Unmanned Air Vehicle), operating In different frequency bands, is calculated for supposing efficient arrangement. For the calculation, FDTD method is used, simulation parameters are confined to distance between antennas, height of antennas, types of ground, etc. The simulation data are compared with those of other numerical method to confirm accuracy of the results. It is appeared that the critical factor of mutual coupling is height of an antenna relative to that of the other antenna.

• International Journal of Quality Innovation
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• v.10 no.2
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• pp.57-76
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• 2009

Although many adherents openly praise the importance of quality management practices (QMP) in organisations, others have identified significant costs and implementation obstacles. Some recent studies showed that QMP have failed due to the ignorance of quality cultures. How to improve the success rate of QMP in organisations has become a critical issue both in the academy and in practice. This paper discusses the common enablers of and cultural impacts on QMP. It explores the dimensions of national versus organisational culture, and identifies the main features of four quality culture models as advocated in the literature in relation to facilitating QMP in organisations. It was found that flat structures, decentralised functions, empowerment, flexibility, innovation, limited rules and regulations and teamwork favor the QMP implementation. For facilitating culture changes for QMP, values associated with low power distance, low uncertainty avoidance and collectivism would have to be nurtured. Further research is needed to incorporate the findings and develop a practical quality culture approach for real applications in industry.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 1995.10a
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• pp.290-294
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• 1995

In master-slave teleoperation system, time delay may be a critical problem because a task is performed over a distance. Even if the system is stable without time delay, time delay can make the system unstable. In this paper a new control scheme applicable to the system with time delay would be proposed,which is based on the conventional position-position feedback type controller. The stability of this control system is proved using scattering theory, and is compared with the conventional ones. By performing the simulation of a one-d.o.f master-slave system, the validity of the proposed algorithm is verified.

• Journal of Astronomy and Space Sciences
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• v.32 no.2
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• pp.137-140
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• 2015

The results of the study of ionospheric variations in the summer months of 1998-2002 at an ionospheric station of vertical sounding "Petropavlovsk-Kamchatsky" are presented. Anomalous variations of virtual sporadic-E height (h'Es), Es blanketing frequency (fbEs), and the critical frequency of the ionospheric F2 layer (foF2) (which can be attributed to the possible earthquake precursors) are selected. The high efficiency of the selection of ionospheric earthquake precursors based on the several parameters of Es and F2 layers is shown. The empirical dependence, which reflects the connection between the lead-time of the earthquake moment, the distance to the epicenter from the observation point, and the magnitude of the earthquake are obtained. This empirical dependence is consistent with the results of the detection of earthquake precursors by measuring the physical parameters of the Earth's crust in the same region.

• Structural Engineering and Mechanics
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• v.21 no.1
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• pp.53-66
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• 2005

When a large number of identical cylinders are placed in an array with equal separation distance, near-resonant phenomena may occur between cylinders at critical frequencies, and cause large wave forces on each element of the array. In this paper, 64 truncated circular cylinders arranged in 4 rows and 16 columns are considered to check occurrence of near-resonant phenomena and performance of theoretical predictions based on the potential flow. Experiments are conducted in head waves to measure the wave elevation along the longitudinal centerline of the model, and measured results are compared with numerical ones. Attention is focused on the spatial variation of the wave amplitude around the first near-trapped-mode frequency.

• Proceedings of the Korea Information Processing Society Conference
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• 2007.05a
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• pp.1283-1285
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• 2007

A wireless sensor network is the combination of a large number of deployed sensors over an area. Communication between the sensors is the most important factor for a successful sensor network. It is mandatory that long distance and multi-hop communication will occur between sensors. Generally sensors relay the sensed data of a particular territory to the command center via a base station. For the non uniformed deployment of sensors many sensors may deploy in hostile areas surrounded by full of obstacles or in other condition it may be out of the direct communication range of the base station. It seems a critical problem for routing data to and from those sensors to the base station. This paper proposes a route management scheme using a dynamic load balancing approach based on residual energy of each agent sensors.

• Proceedings of the Polymer Society of Korea Conference
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• 2006.10a
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• pp.116-117
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• 2006

Increasing the solvent molecular size leads to shrinkage of the polymer chains and increase of the critical overlap concentrations. In addition, the dependency of $R_{g}$ on polymer concentration under normal solvent conditions and solvent molecular size is in good agreement with scaling laws. When the solvent molecular size approaches the ideal end-to-end distance of the polymer chain, an extra aggregation of polymer chains occurs, and the solvent becomes the so-called medium-sized solvent. When the size of solvent molecules is smaller than the medium size, the polymer chains are swollen or partially swollen. However, when the size of solvent molecules is larger than the medium size, the polymer coils shrink and segregate, enwrapped by the large solvent molecules.