• Journal of the Korean Institute of Telematics and Electronics A
• /
• v.29A no.11
• /
• pp.19-24
• /
• 1992

In this paper, a high frequency method is developed which combines the uniform Geometrical Theory of Diffraction(GTD) and the Aperture Integration(AI) to analyze electromagnetic plane wave scattering by a perfectly-conducting, open-ended, semi-infinite parallel plate waveguide with a uniform layer of absorbing material on its inner wall, and with a slanted planar termination inside. In this method, first, the field of an arbitary point inside the paraller plate waveguide is computed by the GTD. Second, the field scattered into exterior region by the waveguide is found using the equivalent current, which can be obtaind from the aperture field of the waveguide and using the AI. Numerical results based on this GTD method are presented and compared with those based on the mode matching method.

• ETRI Journal
• /
• v.30 no.2
• /
• pp.301-307
• /
• 2008

As broadband access is evolving from digital subscriber lines to optical access networks, Ethernet passive optical networks (EPONs) are considered a promising solution for next generation broadband access. The point-to-multipoint topology of EPONs requires a time-division multiple access MAC protocol for upstream transmission. In this paper, we propose a new enhanced dynamic bandwidth allocation algorithm with fairness called EFDBA for multiple services over EPONs. The proposed algorithm is composed of a fairness counter controller and a fairness system buffer in the optical line terminal. The EFDBA algorithm with fairness can provide increased capability and efficient resource allocation in an EPON system. In the proposed EFDBA algorithm, the optical line termination allocates bandwidth to the optical network units in proportion to the fairness weighting counter number associated with their class and queue length. The proposed algorithm provides efficient resource utilization by reducing the unused remaining bandwidth made by idle state optical network units.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
• /
• 2001.07a
• /
• pp.495-498
• /
• 2001

The distribution line through which electricity is supplied from substation to customer generally varies by underground line and overhead line. In contrast that the underground line is shielded, the overhead lines do not have the shield layer. To overcome this weak point of the overhead lines, the aerial bundled cable(ABC) connection systems have been developed. The basic concept of the ABC connection system is the application of the underground cable system containing complete shield layer to the overhead cable system. The ABC system is the innovative technologies which enable the prevention of electric shocks, reduction of the maintenance charge and damage of the cable. This paper give a full detail of vertical connection system applied within a country.

• The Transactions of the Korean Institute of Electrical Engineers A
• /
• v.48 no.10
• /
• pp.1349-1355
• /
• 1999

A power distribution facility map is drawn on cadastral map. Besides, grid lines are added on the map for sectionalization. For automatic recognition of the map, we first extract recognizing regions. In this paper, we propose an extraction method of recognizing regions by partially extending thinned image. The proposed method is consist of three phases, binarization phase, thinning phase and partial extending phase. The first phase generate a binary image using threshold value which is obtained by histogram analysis. The binary image contains many part of recognizing regions, but not all. The second phase generate thinned image which is generated by appling thinning operator to the binary image. And the third phase extends thinned image from terminal point until satisfying termination condition. The proposed method is tested on several power distribution facility maps, and the results are presented.

• Proceedings of the Computational Structural Engineering Institute Conference
• /
• 1997.10a
• /
• pp.155-162
• /
• 1997

Genetic algorithms(GA) are based on the principles of natural genetics and natural selection. The algorithm searches an optimum design point using information based on the fitness function evaluated for the population of many design points. An application of GA on optimal design of a truss structure is studied. The terminology and the operating procedures common in GA are formalized by establishing similarities between GA and genetics from biology. In using GA, (1) coding of the design variables, (2) formulation of the fitness function, (3) setting of the termination condition, and (4) establishment of the probabilities are essential. These four points are discussed in the paper.

• International conference on construction engineering and project management
• /
• 2005.10a
• /
• pp.699-704
• /
• 2005

Normally, monetary penalties for breach of agreement will be stipulated in the contract. The contractor parties, who fail to fulfill the agreement, are required to pay the other parties a certain amount or proportion of money as a fine. However, it is worth our study - whether or not the scope of monetary penalty implementation and bases for determination of a fine will cover the losses of social and administrative costs incurred by the interruption of the contract. This research is about the best timing for government to cancel the freeway repair work contracts. Under the goal of the maximum social welfare, the limitation of government spending for the social and administrative costs invoked by interruption of contracts will have to be considered to attain the best timing of contracts' suspension or deferment. According to the factors of social and administrative costs, the best time point is calculated to reduce the loss of the aforesaid costs, which can also be used as theoretical basis for the future road-widening construction at home.

• Korean Journal of Acupuncture
• /
• v.21 no.4
• /
• pp.69-82
• /
• 2004

Objectives : In the present study, the effect of electroacupuncture (EA) applied to hand yang meridian on the ankle sprain model was examined. Methods & Results : A common source of persistent pain in humans is the lateral ankle sprain. To model this condition, the rat's right ankle was bent repeatedly, overextending lateral ligaments, for 4 min under halothane anesthesia. The rat subsequently showed swelling of the ankle and a reduced stepping force of the affected limb for the next several days. The reduced stepping force of the limb was presumably due to a painful ankle. EA was applied to the several acupuncture point on the contralateral forelimb for 30 min under gaseous anesthesia. After the termination of EA, behavioral tests measuring stepping force were periodically conducted during the next 4 h. EA applied to SI-6 point produced a significant improvement of stepping force of the sprained foot lasting for at least 2 h. However, neigher LI-4 point nor TE-3 point produced any significant increase of weight bearing force. The improvement of stepping pressure was interpreted as an analgesic effect. The analgesic effect was specific to the acupuncture point since the analgesic effect on the ankle sprain pain model could not be mimicked by EA applied to a nearby point, LI-4 or TE-3. The analgesic effect of EA applied to SI-6 was more powerful when EA was applied by low-frequency and high-intensity stimulation. In addition, this effect need to be stimulated more than 15 min. Conclusions : These data suggest that EA produces a potent analgesic effect on the ankle sprain pain model in the rat. This analgesic effect is produced by applying EA to a Tae-Yang meridian at opposite side from the painful area in a stimulus point-specific way.

• Transactions of Materials Processing
• /
• v.27 no.2
• /
• pp.115-122
• /
• 2018

Most domestic and international standards on the forming limit diagram (FLD) including ISO 12004-2, use a 'position-dependent method,' which determines the forming limit from a strain distribution measured on the specimen after necking or fracture. However, the position-dependent method has inherent problems such as the incidence of asymmetry of a strain distribution, the estimation of missing data near fracture, the termination time of test, and the deformation due to the new stress equilibrium after a fracture, which is blamed for causing sometimes a significant lab-to-lab variation. The 'time-dependent method,' which is anticipated to be a new international standard for evaluating the forming limit, is expected to greatly improve these intrinsic disadvantages of the position-dependent method. It is because the time-dependent method makes it possible to identify and accurately determine the forming limit, just before the necking point from the strain data as continuously measured in a short time interval. In this study, we propose a new time-dependent method based on a Gaussian fitting of strain acceleration with the introduction of 'normalized correlation coefficient.' It has been shown in this study that this method can determine the forming limit very stably and gives a higher value, which is in comparison with the results of the previously studied position-dependent and time-dependent methods.

• Proceedings of the Korean Society for Technology of Plasticity Conference
• /
• 2000.10a
• /
• pp.136-140
• /
• 2000

It is desirable to predict springback quantitatively and accurately for the tool and process design in sheet stamping operations, however, it is blown very difficult. The result of springback analysis by the finite element method is sensitively influenced by numerical factors such as blank element size, number of integration point, punch velocity, contact algorithm etc. In the present work, a parametric study by Taguchi method is performed in order to evaluate the influence of numerical factors on springback Quantitatively and to obtain the combination of numerical factors which yields the best approximation to experimental data. Since springback is determined by the residual stress after forming process, it is important to evaluate stress distribution accurately. The oscillation in the time history curve of stress obtained by explicit FEM says that the stress solution at termination time is in very unstable state. Therefore, a variability study is also carried out in this study in order to assess the stability of implicit springback analysis starting from the stress solution by explicit forming simulation. The 2D draw bending process, one of the NUMISHEET '93 benchmark problems, is adopted as an application model.

• Computational Structural Engineering
• /
• v.10 no.3
• /
• pp.185-193
• /
• 1997

The order of the stress singularity that occurs at the termination of an interface between materials exhibiting bilinear stress-strain response under plane strain conditions has been calculated, The governing equation of elasticity together with traction-free boundary condition and interface continuity condition defines a two-point boundary value problem. The stress components near the free edge are assumed to be proportional to r/sup s-1/, with solutions existing only for certain values of s. Finding these values entails the solution of an eigenvalue problem. Because it has been impossible to integrate the differential equations analytically, the integration has been performed numerically with a shooting method coupled with a Newton improvement scheme.