• Journal of the Korean Society of Manufacturing Process Engineers
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• v.11 no.1
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• pp.56-61
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• 2012

The dynamic instability and natural frequency of axially moving beam with an attached mass are investigated. Thus, the effects of an attached mass on the stability of the moving beam are studied. The governing equation of motion of the moving beam with an attached mass is derived from the extended Hamilton's principle. The natural frequencies are investigated for the moving beams via the Galerkin method under the simple support boundary. Numerical examples show the effects of the attached mass and moving speed on the stability of moving beam. Moreover, the lowest critical moving speeds for the simple supported conditions have been presented. The results can be used in the analysis of axially moving beams with an attached mass for checking the stability.

• Nuclear Engineering and Technology
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• v.44 no.1
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• pp.71-78
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• 2012

In many semi-empirical analyses of flow boiling heat transfer, an annular flow is often assumed as a model flow and the local liquid film thickness is a key parameter in the analysis. This work considers a simple electrical conductance technique to estimate the local liquid film thickness in two-phase annular flows. In this approach, many electrodes are mounted flush with the inner wall of the pipe. Voltage differences between two neighboring electrodes for concentric annular flows with various liquid film thicknesses are obtained before the main experiments and logged in a look-up table. For an actual application in the annual flow, voltage differences of neighboring electrodes are measured and then corresponding local film thicknesses are determined by the interpolation of the look-up table. Even though the proposed technique is quite simple and straightforward, the numerical and static phantom experiments support its usefulness.

• Proceedings of the KSME Conference
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• 2000.11a
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• pp.381-386
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• 2000

Simple spring-damper-mass models have been widely used to understand whole-body vertical biodynamic response characteristics of the seated vehicle driver. However, most previous models have not considered about the non-rigid masses(wobbling masses). A simple mechanical model of seated human body developed in this study included the torso represented by a rigid and a wobbling mass. Within the 0.5-20Hz frequency range and for excitation amplitudes maintained below $5ms^{-2}$, this 4-degree-of-freedom driver model is proposed to satisfy the measured vertical vibration response characteristics defined from a synthesis of published data for subjects seated erect without backrest support. The parameters are identified by using the combinatorial optimization technique, simulated annealing method. The model response was found to be provided a closer agreement with the response characteristics than previously published models.

• Journal of the Korean Statistical Society
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• v.28 no.1
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• pp.73-92
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• 1999

In Bayesian model selection or testing problems, one cannot utilize standard or default noninformative priors, since these priors are typically improper and are defined only up to arbitrary constants. The resulting Bayes factors are not well defined. A recently proposed model selection criterion, the intrinsic Bayes factor overcomes such problems by using a part of the sample as a training sample to get a proper posterior and then use the posterior as the prior for the remaining observations to compute the Bayes factor. Surprisingly, such Bayes factor can also be computed directly from the full sample by some proper priors, namely intrinsic priors. The present paper explains how to derive intrinsic priors for simple tree ordered exponential means. Some numerical results are also provided to support theoretical results and compare with classical methods.

• Journal of KSNVE
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• v.10 no.6
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• pp.998-1008
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• 2000

The continuous circular cylindrical shells are widely used for the high performance structures of aircraft, spacecraft, missile, nuclear fuel rod shell etc.. In this paper, a method for the free vibration analysis of the continuous circular cylindrical shells with the multiple simple supports is developed by using the receptance method. With this method, the vibrational characteristics of the continuous system is analyzed by considering as a combined structure. The system receptance is also derided by the application of the equilibrium of forces and the continuity of displacements at the support points. The natural frequencies and mode shapes are calculated numerically and they are compared with the FEM results to improve the reliability of analytical solution. Numerical results on the 4-equal-span continuous circular cylindrical shell are presented in this paper.

• Journal of Chest Surgery
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• v.24 no.4
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• pp.390-396
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• 1991

From July 1984 to September 1990, 316 patients of congenital heart diseases were operated and 15 patients died. Hospital mortality was 4.75%. Five patients of 73 PDA had residual shunt after operation: 4 were ligated under support of Dacron patch, 1 was closed through the pulmonary arteriotomy under CPB. 3 patients were reoperated. No patient had residual shunt or reopening among the patients of simple ligation or division and suture. During the ligation of PDA, Dacron patch for protection from tearing may disturb the complete interruption of shunt. If the tissue around the ductus arteriosus looks weak or fragile, division and suture may be more reliable other than ligation with supporting patch. If the septal leaflet of tricuspid valve is adherent around the VSD, remained opening of VSD may be closed with simple suture directly. In these cases, the incidence of postoperative residual shunt is as high as the incidence of more large VSD closed with patch [10.9%: 9.6%]. During the direct closure of remained opening of VSD, another leaking route should be looked for carefully beneath the septal leaflet of tricuspid valve.

• Proceedings of the Korean Geotechical Society Conference
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• 2009.09a
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• pp.863-874
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• 2009

The engineering characteristics and the reinforcement effect of the elephant foot method were discussed with parametric study. The elephant foot method is adopted to support the loads transferred from tunnel crown and improve bearing capacity of elephant foot in poor ground condition. The evaluation of reinforcement effect, which has the mechanical relationship between ground condition, footing size and reinforcement system, was carried out through the previous research and numerical analysis. In addition, the simple design chart was proposed to estimate the applicability of the elephant foot reinforcement method. It will be practical for the engineer to determine the optimum reinforcement method for safe tunnelling in soft ground condition.

• ETRI Journal
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• v.26 no.1
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• pp.27-37
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• 2004

The architecture in a differentiated services (DiffServ) network is based on a simple model that applies a per-class service in the core node of the network. However, because the network behavior is simple, the network structure and provisioning is complicated. If a service provider wants dynamic provisioning or a better bandwidth guarantee, the differentiated services network must use a signaling protocol with QoS parameters or an admission control method. Unfortunately, these methods increase the complexity. To overcome the problems with complexity, we investigated scalable dynamic provisioning for admission control in DiffServ networks. We propose a new scalable $qDPM^2$ mechanism based on a centralized bandwidth broker and distributed measurement-based admission control and movable boundary bandwidth management to support heterogeneous QoS requirements in DiffServ networks.

• Journal of Electrical Engineering and Technology
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• v.12 no.3
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• pp.1257-1261
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• 2017

This paper focuses on understanding the interrupting capability of an arc contact system in a molded case circuit breaker (hereafter MCCB). We selected four types of MCCBs and analyzed the magnetic flux density distributions in the contact systems caused by the fault currents. We ascertained that the magnetic flux density profile varies according to the shape of the contact system and was asymmetric at both the ends of an arc, perpendicular to the arc column because of the magnetic grid installed in the contact system. The asymmetric difference creates a magnetic force that pushes the arc current outwards and provides an interrupting capability. We have introduced a simple analysis method for determining the interrupting capability of the contact system for an MCCB by the arc-driving magnetic flux density.

• Journal of Multimedia Information System
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• v.5 no.2
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• pp.83-86
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• 2018

Owing to high speed internet technologies, video conferencing systems are exploited in our home as well as work places using a laptop or a webcam. Although eye contact in the video conferencing system is significant, most systems do not support good eye contact due to improper locations of cameras. Several ideas have been proposed to solve the eye contact problem; however, some of them require complicated hardware configurations and expensive customized hardwares. In this paper, we propose a simple eye gaze correction method using the three-dimensional (3D) affine transformation. We also apply an image in-painting method to fill empty holes that are caused by round-off errors from the coordinate transformation. From experiments, we obtained visually improved results.