• The Journal of Korean Association of Computer Education
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• v.6 no.1
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• pp.29-39
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• 2003

In this paper we proposed dynamic adaptive model based on discrete probabilistic distribution functions and user's profile for web media systems(web based hypermedia systems). The model represented that the application domain is modelled using a weighted direct graph and the user's behaviour is modelled using a probabilistic approach that dynamically constructs a discrete probability distribution functions. The proposed probabilistic interpretation of the web media structure is used to characterize latent properties of the user's behaviour, which can be captured by tracking user's browsing activity. Using that distribution the system attempts to assign the user to the best profile that fits user's expectations.

• 유체기계공업학회:학술대회논문집
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• 2004.12a
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• pp.572-577
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• 2004

This paper presents numerical study on the performance improvement of the sirocco fan in a range hood. The performance of sirocco fan means a higher flowrate, a higher static pressure and a lower required motor power in a fixed geometry constraint. Various impeller geometric parameters, such as blade profile, blade diameter, blade thickness profile and blade exit angle, were investigated by numerically and the results were compared with each other to know the effects on the performance. In this approach, the volute geometry were fixed with the original shape. The numerical results show that the blade profile with airfoil shape and small exit blade thickness increases the performance. The blade exit angle shows optimum angle within a varied range. The efficiency of the optimized exit angle was about $10\%$ higher than the base blade exit angle and the static pressure was about $28\%$ higher at the flow coefficient 0.22.

• The Journal of Korean Society for Radiation Therapy
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• v.7 no.1
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• pp.15-31
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• 1995

The radiosurgery treatment is one time, non surgical approach to the treatment of patients with intracranial disorders whose conditions would be difficult or dangerous to treat with conventional sugical procedures. The LINAC based radiosurgery is based on the combination of multiple isocentric arc irradiation with small fields centered in the stereotactic target. The absorption of the beam in a tissue equivalent medium, such as water, as well as the uniformity, or profile, of the beam must be precisely documented. The beam characteristics and dosimetric measurememts of the 6MV X-ray beam from a ML-6M linear accelerator are examined. The percent depth dose (PDD) and beam profile (including flatness, symmetry and penumbra) is calibrated with the radiosurgery cone in water phantom. The cone is made of lead which size is from $10{\times}10mm{\phi}$ to $30{\times}30mm{\phi}$ All of these dosimetric measurements sufficiently characterized the beam to permit safe clinical use.

• ETRI Journal
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• v.31 no.6
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• pp.784-794
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• 2009

We present a full HD (1080p) H.264/AVC High Profile hardware encoder based on fast motion estimation (ME). Most processing cycles are occupied with ME and use external memory access to fetch samples, which degrades the performance of the encoder. A novel approach to fast ME which uses shared multibank memory can solve these problems. The proposed pixel subsampling ME algorithm is suitable for fast motion vector searches for high-quality resolution images. The proposed algorithm achieves an 87.5% reduction of computational complexity compared with the full search algorithm in the JM reference software, while sustaining the video quality without any conspicuous PSNR loss. The usage amount of shared multibank memory between the coarse ME and fine ME blocks is 93.6%, which saves external memory access cycles and speeds up ME. It is feasible to perform the algorithm at a 270 MHz clock speed for 30 frame/s real-time full HD encoding. Its total gate count is 872k, and internal SRAM size is 41.8 kB.

• Steel and Composite Structures
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• v.45 no.5
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• pp.653-663
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• 2022

This study reports the results of a series of tests of pultruded glass fiber reinforced polymer (P-GFRP) box section composite profile columns, geometrically similar with/without concrete core, containing 0-1-2-3% steel fiber, with different lengths. The recycled steel wires were obtained from waste tyres. The effects of steel fiber ratio on the collapse and size effect of concrete filled P-GFRP columns under axial pressure were investigated experimentally and analytically. A total of 36 columns were tested under compression. The presence of pultruded profile and steel wire ratio were selected as the primary variable. The capacity of pultruded profiles with infilled concrete are averagely 9.3 times higher than the capacity of concrete without pultruded profile. The capacity of pultruded profiles with infilled concrete are averagely 34% higher than that of the pultruded profiles without infilled concrete. The effects of steel wire ratio are more pronounced in slender columns which exhibit buckling behavior. Moreover, the proposed analytical approach to calculate the capacity of P-GFRP columns successfully predicted the experimental findings in terms of both pure axial and buckling capacity.

• Journal of the Korean Society for Precision Engineering
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• v.13 no.5
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• pp.95-103
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• 1996

This paper describes a computer aided design system for spur and helical gears. To establish the appropriate program, an integrate approach based on a rule-base system was adopted. This system is implemented on the personal computer and its environment is a commercial CAD package called AutoCAD. This system includes a main program and five sub-modules such as data input module, tooth profile drawing module, strength calculation module, and drawing edit module. In the main program, all the sub-modules are loaded and the type of gear and tooth profile are selected. In the data input module, the variables which are necessary to the design of gear are selected from the database. In the drawing module, from the calculated results, the required gear tooth is produced on the screen. The developed system that aids gear designer provides powerful capabilities for gear design.

• Wind and Structures
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• v.5 no.2_3_4
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• pp.177-192
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• 2002

Computation solutions for the flow around a cube, which were generated as part of the Computational Wind Engineering 2000 Conference Competition, are compared with full-scale measurements. The three solutions shown all use the RANS approach to predict mean flow fields. The major differences appear to be related to the use of the standard $k-{\varepsilon}$, the MMK $k-{\varepsilon}$ and the RNG $k-{\varepsilon}$ turbulence models. The inlet conditions chosen by the three modellers illustrate one of the dilemmas faced in computational wind engineering. While all modeller matched the inlet velocity profile to the full-scale profile, only one of the modellers chose to match the full-scale turbulence data. This approach led to a boundary layer that was not in equilibrium. The approach taken by the other modeller was to specify lower inlet turbulent kinetic energy level, which are more consistent with the turbulence models chosen and lead to a homogeneous boundary layer. For the $0^{\circ}$ case, wind normal to one face of the cube, it is shown that the RNG solution is closest to the full-scale data. This result appears to be associated with the RNG solution showing the correct flow separation and reattachment on the roof. The other solutions show either excessive separation (MMK) or no separation at all (K-E). For the $45^{\circ}$ case the three solutions are fairly similar. None of them correctly predicting the high suctions along the windward edges of the roof. In general the velocity components are more accurately predicted than the pressures. However in all cases the turbulence levels are poorly matched, with all of the solutions failing to match the high turbulence levels measured around the edges of separated flows. Although all of the computational solutions have deficiencies, the variability of results is shown to be similar to that which has been obtained with a similar comparative wind tunnel study. This suggests that the computational solutions are only slightly less reliable than the wind tunnel.

• Geomechanics and Engineering
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• v.31 no.5
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• pp.439-452
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• 2022

A forecast of slope behavior during catastrophic events, such as earthquakes is crucial to recognize the risk of slope failure. This paper endeavors to eliminate the significant supposition of predefined slip surfaces in the slope stability analysis, which questions the relevance of simple conventional methods under seismic conditions. To overcome such limitations, a methodology dependent on the slip line hypothesis, which permits an automatic generation of slip surfaces, is embraced to trace the extreme slope face under static and seismic conditions. The effect of earthquakes is considered using the pseudo-static approach. The current outcomes developed from a parametric study endorse a non-linear slope surface as the extreme profile, which is in accordance with the geomorphological aspect of slopes. The proposed methodology is compared with the finite element limit analysis to ensure credibility. Through the design charts obtained from the current investigation, the stability of slopes can be assessed under seismic conditions. It can be observed that the extreme slope profile demands a flat configuration to endure the condition of the limiting equilibrium at a higher level of seismicity. However, a concurrent enhancement in the shear strength of the slope medium suppresses this tendency by offering greater resistance to the seismic inertial forces induced in the medium. Unlike the traditional linear slopes, the extreme slope profiles mostly exhibit a steeper layout over a significant part of the slope height, thus ensuring a more optimized solution to the slope stability problem. Further, the susceptibility of the Longnan slope failure in the Huining-Wudu seismic belt is predicted using the current plasticity approach, which is found to be in close agreement with a case study reported in the literature. Finally, the concept of equivalent single or multi-tiered planar slopes is explored through an example problem, which exhibits the appropriateness of the proposed non-linear slope geometry under actual field conditions.

• 제어로봇시스템학회:학술대회논문집
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• 2004.08a
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• pp.1012-1016
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• 2004

In this paper, we propose a simple but optimized NC code generating technique for disk cams by means of tool path error control in a five-axis CNC machining center. Using the geometric theorem of the triangle made between manufacturing points and error checkpoint, the tool path error has been studied for disk cams profile generation and an improvement in the profile has been obtained. Then, based on the present manufacturing approach a computer program is developed on $C^{++}$ language to perform and to verify the shape design, the manufacturing simulation, and the optimized generation of the NC code.

• Journal of Electrical Engineering and Technology
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• v.11 no.6
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• pp.1582-1589
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• 2016

In this paper the integration of Distributed Generation (DG) in radial distribution system is investigated by computing the optimal site and size of DG to be placed. An analytical expression based on equivalent current injection has been derived by utilizing topological structure of radial distribution system to find optimal size of DG to minimize losses. In the presented formulation, the optimal DG placement is obtained without repeatedly computing the load flow. The proposed formulation can be used to find the optimal size of all types of DGs namely Type-I, Type-II, Type-III and Type-IV DGs. The investigations are carried out on IEEE 33-bus and 69-bus radial distribution systems. The optimal DG placement results into reduction in active and reactive power losses and improvement in voltage profile of the buses.