• The Transactions of The Korean Institute of Electrical Engineers
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• v.58 no.7
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• pp.1263-1269
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• 2009

Stable and sustainable power supply means maintaining a certain level of power quality and service while securing energy resource and resolving environmental issues. Distributed generation (DG) has become an essential and indispensable element from environmental and energy security perspectives. It is known that voltage violation is the most important constraint for load variation and the maximum allowable DG. In distribution system, sending voltage from distribution substation is regulated by ULTC (Under Load Tap Changer) designed to maintain a predetermined voltage level. ULTC is controlled by LDC (Line Drop Compensation) method compensating line voltage drop for a varying load, and the sending voltage of ULTC calls for LDC parameters. The consequence is that the feasible LDC parameters considering variation of load and DG output are necessary. In this paper, we design each LDC parameters determining the sending voltage that can satisfy voltage level, decrease ULTC tap movement numbers, or increase DG introduction. Moreover, the maximum installable DG capacity based on each LDC parameters is estimated.

• Journal of the Korean Ceramic Society
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• v.52 no.6
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• pp.403-409
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• 2015

Porous alumina ceramics are involved in many industrial applications due to the exceptional properties of these products. This study addresses the preparation of porous alumina ceramics using hollow microspheres as a pore-forming agent and slip casting as a green-body-forming technique. A uniform distribution of pores is a basic requirement of a porous material. This study investigates three different slurry systems, i.e., as-prepared alumina slurry, alumina slurry electrostatically dispersed by hydrochloric acid (HCl), and slurry dispersed by the commercial dispersant 'Darvan C-N'. At a low viscosity, the hollow microspheres in the slurry tend to float, which causes a non-uniform pore distribution. To avoid this phenomenon, the viscosity of the slurry was increased to the extent that the movement of hollow microspheres ceased in the slurry. As a result, a uniform pore distribution was achieved.

• Journal of the Korean Wood Science and Technology
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• v.33 no.5 s.133
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• pp.50-56
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• 2005

The effect of wood material type on biocide retention and distribution during supercritical fluid impregnation was assessed using three different wood types including solid wood, plywood and oriented strand board (OSB). The result revealed that biocide treatability differed with structural composition and permeability of the various materials. Low treatability of plywood might be attributed to interferences of glue line limiting fluid movement. OSB samples showed higher biocide retentions, resulting from the presence of interconnecting gaps permitting more open flow.

• Transactions of the Korean Society of Mechanical Engineers
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• v.17 no.10
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• pp.2418-2425
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• 1993

A two-dimensional transient heat transfer model for reactive gas assisted laser cutting process with a moving Gaussian heat source is developed using a numerical finite difference technique. The kerf width, melting front shape and temperature distribution were calculated by using the boundary-fitted coordinate system to handle the ejection of workpiece material and heat input from reaction and evaporation. An analytical solution for cutting front movement was adopted and numerical simulation was performed to calculate the temperature distribution and melting front thickness. To calculate the moving velocity of cutting front, the normal distribution of the cutting gas velocity was used. The kerf width was revealed to be dependent on the cutting velocity, laser power and cutting gas velocity.

• Proceedings of the Korean Geotechical Society Conference
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• 2002.10a
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• pp.374-381
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• 2002

Several sensor systems are used to estimate the reinforceing effect of pile in hihg cut slopes, and to find a failure zone in slopes effectively. Inclinometer, extensometer and V/W sensor have shown a great potentiality to serve real time health monitoring of the slope structures. They were embedded or attached to the structures, we conducted field tests and test results have shown great solutions for sensor systems of Civil Engineering Smart Structures. This research is to seek for the relationships among the slope movement and the reinforceing effect of pile, and the strain distribution in a active zone by analyzing the data from the in-situ measurement so that the possible failure zone should be well defined based on the relationships. Also, the relationships between temperature and reinforceing effect of pile, and the strain distribution are estimated in this paper.

• Journal of the Korean Institute of Telematics and Electronics S
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• v.35S no.5
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• pp.94-102
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• 1998

In this paper, we proposed a dynamic selection scheme of advnaced prediction mode(DAPM), which reduces computational cost and improves coding efficiency. We can select the mode between default prediction mode (DPM) and advanced prediction mode (APM) according to motion componenets in a frame dynamically. For this purpose, we defined error distribution of motion estimation (EDME) as sum of absolute difference(SAD) for each searching points. This distribution region is divided to four subregions. We calculate minimum values in each subregions and then, we determine whether block motion estimation is performed or not depending on the results. As a result, we reduced computational complexity to 30% without degradation of image quality compared to fixed APM(FAPM) by selecting DPM for linear movement.

• Journal of Periodontal and Implant Science
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• v.46 no.2
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• pp.96-106
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• 2016

Purpose: Stress distribution and mandible distortion during lateral movements are known to be closely linked to bruxism, dental implant placement, and temporomandibular joint disorder. The present study was performed to determine stress distribution and distortion patterns of the mandible during lateral movements in Class I, II, and III relationships. Methods: Five Korean volunteers (one normal, two Class II, and two Class III occlusion cases) were selected. Finite element (FE) modeling was performed using information from cone-beam computed tomographic (CBCT) scans of the subjects' skulls, scanned images of dental casts, and incisor movement captured by an optical motion-capture system. Results: In the Class I and II cases, maximum stress load occurred at the condyle of the balancing side, but, in the Class III cases, the maximum stress was loaded on the condyle of the working side. Maximum distortion was observed on the menton at the midline in every case, regardless of loading force. The distortion was greatest in Class III cases and smallest in Class II cases. Conclusions: The stress distribution along and accompanying distortion of a mandible seems to be affected by the anteroposterior position of the mandible. Additionally, 3-D modeling of the craniofacial skeleton using CBCT and an optical laser scanner and reproduction of mandibular movement by way of the optical motion-capture technique used in this study are reliable techniques for investigating the masticatory system.

• Journal of Communications and Networks
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• v.15 no.5
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• pp.504-513
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• 2013

Communication in delay tolerant networks (DTNs) relies on message transport by mobile nodes, and a correct understanding of the node mobility characteristics is therefore crucial to the design of an efficient DTN routing protocol. However, previous work has mainly focused on uncovering all behaviors of node movement, which is not conducive to accurately detecting the specific movement characteristics of a different node. In this paper, we seek to address this problem based on a consideration of social relationships. We first consider social ties from both static and dynamic perspectives. For a static perspective, in addition to certain accidental events, social relations are considered for a long time granularity and tend to be stable over time. For a dynamic perspective, social relations are analyzed in a relatively short time granularity and are likely to change over time. Based on these perspectives, we adopted different efficient approaches to dividing node pairs into two classes, i.e., familiar and unfamiliar pairs. A threshold approach is used for static social ties whereas a density-based aggregation method is used for dynamic social relationships. Extensive experimental results show that both familiar and unfamiliar node pairs have the same inter-contact time distribution, which closely follows a power-law decay up to a certain point, beyond which it begins to exponentially decay. The results also demonstrate that the inter-contact time distribution of familiar pairs decays faster than that of unfamiliar pairs, whether from a static or dynamic perspective. In addition, we also analyze the reason for the difference between the inter-contact time distributions of both unfamiliar and familiar pairs.

• Journal of the Korean Geotechnical Society
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• v.20 no.8
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• pp.193-203
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• 2004

Arching effects in backfill materials generate a nonlinear active earth pressure distribution on a rigid retaining wall with rough face, and arching effects on the shape of the nonlinear earth pressure distribution depends on the mode of wall movement. Therefore, the practical shape of failure surface and arching effect in the backfill changed with the mode of wall movement must be considered to calculate accurate magnitude and distribution of active earth pressure on the rigid wall. In this study, a new formulation for calculating the active earth pressure on a rough rigid retaining wall rotating about the base is proposed by considering the shape of nonlinear failure surface and arching effects in the backfill. In order to avoid mathematical complexities in the calculation of active earth pressure, the imaginary failure surface composed of four linear surfaces is used instead of the nonlinear failure surface as failure surface of backfills. The comparisons between predictions from the proposed equations and existing model test results show that the proposed equations produce satisfactory predictions.

• Journal of the Korean Society of Radiology
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• v.13 no.4
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• pp.637-643
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• 2019

To verify internal movements of the body, a DICOM file obtained from CT and a Geant4 code were used to simulate lung cancer patients. In addition, the method is applied to measure the movement of tumor when the movement of t he tumor is located inhale and exhale by creating a virtual tumor in the self-produced moving phantom, and to check the distribution of dose in the treatment plan and the accuracy of tumor in PTV for respiratory and lung cancer patients. It was confirmed that 97% or more respiratory control radiation therapy was effective even if the moving area was more than 3cm, in the 40% to 70% range. Dose distribution with respiratory radiation therapy applied to moving targets, measured by film in the actuation phantom, was shown to be within a 3mm margin of error for dose distribution containing 90%. It was confirmed that for actual patient breathing curves, the treatment time may be shorter than that due to the longer expiratory time.