• Journal of Navigation and Port Research
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• v.26 no.1
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• pp.137-145
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• 2002

Water flow simulations for environmental problems often require local detailed analyses for better understanding and accurate prediction of the fate of pollutant in water bodies. This study deals with the development and application of a two-dimensional flow an dispersion model to the coastal water area to find out possible changes due to the wide port development plan. As far as the spatial discretization is concerned, the finite element method is attractive because of its flexibility and ability to naturally treat complex coastal geometries. The model uses finite element theory and the Galerkin weighted-residual approach as its basis. Developed model is applied to the Busan New harbor Construction site. Results from the model were compared with the measured water level and flows in four stations. The flow pattern by the model shows to be similar to the observed data away from the construction site where the flow is not affected. From the simulation results, it is concluded that the model may be useful for numerous other studies for planning and management purposes, especially flow and pollution dispersion in the coastal water bodies where the flow is so complicated.

• KIPS Transactions on Software and Data Engineering
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• v.6 no.11
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• pp.527-536
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• 2017

With the recent development of smart grid industry, the necessity for efficient EMS(Energy Management System) has been increased. In particular, in order to reduce electric load and energy cost, sophisticated electric load forecasting and efficient smart grid operation strategy are required. In this paper, for more accurate electric load forecasting, we extend the data collected at demand time into high time resolution and construct an artificial neural network-based forecasting model appropriate for the high time resolution data. Furthermore, to improve the accuracy of electric load forecasting, time series data of sequence form are transformed into continuous data of two-dimensional space to solve that problem that machine learning methods cannot reflect the periodicity of time series data. In addition, to consider external factors such as temperature and humidity in accordance with the time resolution, we estimate their value at the time resolution using linear interpolation method. Finally, we apply the PCA(Principal Component Analysis) algorithm to the feature vector composed of external factors to remove data which have little correlation with the power data. Finally, we perform the evaluation of our model through 5-fold cross-validation. The results show that forecasting based on higher time resolution improve the accuracy and the best error rate of 3.71% was achieved at the 3-min resolution.

• Journal of Korean Society of Steel Construction
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• v.9 no.4 s.33
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• pp.659-672
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• 1997

Thermal response induced from nonlinear temperature distribution in composite box gilder bridges depends on several variables(environmental conditions, physical and material properties, location and orientation of bridge, and cross-section geometry). In this paper, parametric study are conducted in order to find the effects of variations of seasons, location and orientation of bridge, sectional geometry and some material properties on the axial deformation, curvature and stresses in composite box girder bridge. A two-dimensional transient finite element model to conduct this parametric studies is briefly presented. Firstly, the effects of the parameters on the diurnal variation of curvature are considered, and for the time of maximum curvature, on the distribution of temperature and stresses of composite box girder sectional are considered. Finally, some considerations about the influence of the parameters on the daily maximum values of axial deformation, curvature and stresses are carried out. The influence of thermal effect on structures is important as much as the influence of live or dead load in some cases. In the design of steel composite bridges, the thermal stresses calculated on the supposition that the temperature difference between the concrete slab and steel girder is $10^{\circ}C$ and the temperature distributions are uniform in concrete slab and steel girder can be underestimated.

• Tunnel and Underground Space
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• v.11 no.3
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• pp.257-269
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• 2001

Numerical simulation is performed to understand the structural behavior of an underground radwaste repository, assumed to be located at the depth of 500 m, in a granitic rock mats, in which a fault intersects the roof of the repository cavern. Two dimensional universal distinct element code, UDEC is used in the analysis. The numerical model includes a granitic rock mass, a canister with PWR spent fuels surrounded by the compacted bentonite inside the deposition hole, and the mixed bentonite backfilled in the rest of the space within the repository cavern. The structural behavior of three different cases, each case with a fault of an angle of $33^{\circ},\;45^{\circ},\;and\;58^{\circ}$ passing through the cavern roof-wall intersection, has been compared. And then fro the case with the $45^{\circ}$ fault, the hydro-mechanical, thermo-mechanical, and thermo-hydro-mechanical interaction behavior have been studied. The effect of the time-dependent decaying heat, from the radioactive materials in PWR spent fuels, on the repository and its surroundings has been studied. The groundwater table is assumed to be located 10m below the ground surface, and a steady state flow algorithm is used.

• Clinics in Shoulder and Elbow
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• v.17 no.1
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• pp.25-30
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• 2014

Background: Normal elbow joint kinematics has been widely studied in cadaver, whilst in vivo study, especially of the forearm, is rare. Our study analyses, in vivo, the kinematics of normal forearm and of malunited forearm using a three-dimensional computerized simulation system. Methods: We examined 8 patients with malunited Monteggia fracture and 4 controls with normal elbow joint. The ulna and radius were reconstructed from CT data placing the forearm in three different positions; full pronation, neutral, and full supination using computer bone models. We analyzed the axis of rotation 3-dimentionally based on the axes during forearm rotation from full pronation to full supination. Results: Axis of rotation of normal forearm was pitch line, with a mean range of 2 mm, from full pronation to full supination, connecting the radial head center proximally and ulnar fovea distally. In normal forearm, the mean range was 1.32 mm at the proximal radioulnar joint and 1.51 mm at the distal radioulnar joint. However in Monteggia fracture patients, this range changed to 7.65 mm at proximal and 4.99 mm at distal radoulnar joint. Conclusions: During forearm rotation, the axis of rotation was constant in normal elbow joint but unstable in malunited Monteggia fracture patients as seen with radial head instability. Therefore, consideration should be given not only to correcting deformity but also to restoring AOR by 3D kinematics analysis before surgical treatment of such fractures.

• Journal of Radiation Protection and Research
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• v.30 no.2
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• pp.69-75
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• 2005

Gas avalanche microdetectors, such as micro-strip gas chamber (MSGC), micro-gap chamber (MGC), micro-dot chamber (MDOT), etc., are operated under high voltage to induce large electron avalanche signal around micro-size anodes. Therefore, the anodes are highly exposed to electrical damage, for example, sparking because of the interaction between high electric field strength and charge multiplication around the anodes. Gas electron multiplier (GEM) is a charge preamplifying device in which charge multiplication can be confined, so that it makes that the charge multiplication region can be separate from the readout micro-anodes in 9as avalanche microdetectors possible. Primary electron collection efficiency is an important measure for the GEM performance. We have defined that the primary electron collection efficiency is the fractional number of electron trajectories reaching to the collection plane from the drift plane through the GEM holes. The electron trajectories were estimated based on 3-dimensional (3D) finite element method (FEM). In this paper, we present the primary electron collection efficiency with respect to various GEM operation parameters. This simulation work will be very useful for the better design of the GEM.

• Journal of The Korean Association For Science Education
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• v.35 no.5
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• pp.877-884
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• 2015

Technology is an important means to enhance students' understanding about scientific concepts. In particular, newly introduced 3D printing technology has great potential to help students learn scientific concepts better. 3D printing is a process for a creating physical object with a three dimensional model. In this study, we explored two types of learners' (students vs. adults) motivation and satisfaction with 3D printing technology. With regard to motivation, student learners showed higher task value, self-efficacy for learning, and satisfaction than adult learners. The result implied that 3D printing technology is more effective to student learners than adult learners. In addition, for adult learner group, negative relationship between technology and satisfaction was found. Therefore, support for reducing the technology anxiety for adult learners is necessary. Further discussions are provided for the research and application of 3D printing technology in science classroom.

• Journal of Dental Rehabilitation and Applied Science
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• v.25 no.2
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• pp.171-181
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• 2009

The objective of this study was to analyse stress distribution of maxillary complex by use of face mask. The construction of the three-dimensional FEM model was based on the computed tomography(CT) scans of 13.5 years-old male subject. The CT image were digitized and converted to the finite element model by using the mimics program, with PATRAN. An anteriorly directed force of 500g was applied at the first premolar 45 degrees downwards to the FH plane and at the first molar 20 degrees downwards to the FH plane. When 45 degrees force was applied at maxillary first premolar, there were observed expansion at molar part and constriction at premolar part. The largest displacement was 0.00011mm in the x-axis. In the y-axis, anterior displacement observed generally 0.00030mm at maximum. In the z-axis, maxillary complex was displaced 0.00036 mm forward and downward. When 20 degrees force was applied at maxilla first molar, there were observed expansion at lateral nasal wall and constriction at molar part. The largest displacement was 0.001mm in the X-axis. In the Y-axis, anterior displacement observed generally 0.004mm at maximum. In the Z-axis, ANS was displaced upward and pterygoid complex was displaced downward. The largest displacement was 0.002mm.

• Nuclear Engineering and Technology
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• v.48 no.5
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• pp.1273-1279
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• 2016

Production of iodine-131 by neutron activation of tellurium in tellurium dioxide ($TeO_2$) material requires a target that meets the safety requirements. In a radiopharmaceutical production unit, a new lid for a can was designed, which permits tight sealing of the target by using tungsten inert gaswelding. The leakage rate of all prepared targets was assessed using a helium mass spectrometer. The accepted leakage rate is ${\leq}10^{-4}mbr.L/s$, according to the approved safety report related to iodine-131 production in the TRIGA Mark II research reactor (TRIGA: Training, Research, Isotopes, General Atomics). To confirm the resistance of the new design to the irradiation conditions in the TRIGA Mark II research reactor's central thimble, a study of heat effect on the sealed targets for 7 hours in an oven was conducted and the leakage rates were evaluated. The results show that the tightness of the targets is ensured up to $600^{\circ}C$ with the appearance of deformations on lids beyond $450^{\circ}C$. The study of heat transfer through the target was conducted by adopting a one-dimensional approximation, under consideration of the three transfer modes-convection, conduction, and radiation. The quantities of heat generated by gamma and neutron heating were calculated by a validated computational model for the neutronic simulation of the TRIGA Mark II research reactor using the Monte Carlo N-Particle transport code. Using the heat transfer equations according to the three modes of heat transfer, the thermal study of I-131 production by irradiation of the target in the central thimble showed that the temperatures of materials do not exceed the corresponding melting points. To validate this new design, several targets have been irradiated in the central thimble according to a preplanned irradiation program, going from4 hours of irradiation at a power level of 0.5MWup to 35 hours (7 h/d for 5 days a week) at 1.5MW. The results showthat the irradiated targets are tight because no iodine-131 was released in the atmosphere of the reactor building and in the reactor cooling water of the primary circuit.

• Korean Journal of Applied Biomechanics
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• v.16 no.1
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• pp.55-63
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• 2006

The purpose of this study is to prove the kinematical characteristics of Deff motion, the high bar performance, in terms of flying phases so that we can provide basic sources for improving gymnastic performance. To do this, we selected and analyzed the performance of two athletes who did Deff motion in the high bar competition of male artistic gymnastic in the 22nd Universiade 2003 Daegu. We drew the conclusions from the kinematical factors that were came out through analyzing three-dimensional cinematography of the athletes' movements, by using a high speed video camera. To make a successful performance, a performer releases the bar at a height of a high bar vertically and at a height of 82cm horizontally, and the flying performance should be made without moving forward, as maintaining the proper balance, in order to rise over 118cm high during the flying phase. When the performer is releasing the bar, an increase of the vertical speed in the center of the body and extension of a knee joint and a hip joint contribute to increasing a flying height. And when the moving body is twisted, leaning to left side is caused by the winding movement of a knee joint, which causes an unstable bar grasp. To grasp the bar stably, just before releasing the performer should gain propulsive force from twisting rotation through increasing the speed of shoulder rotation. And before the peak point, the performer should make sure of a body rotation distance over $164^{\circ}$ so that he or she can do an aerial rotary performance smoothly. When grasping the high bar, the center of the body should be above the bar and the angle of shoulder rotation should be maintained close to $540^{\circ}$ simultaneously. he high point performance(S1) has more speed on an ascending phase and less speed on a descending phase than the low point performance (S2). At the peak point, both the rotation angle of the body and that of the shoulder in high point performance are big as well. In conclusion, it is shown that a performer can make a jump toward the high bar easily with the body straight because the performer can hold the upper part of the body erect early in a descending phase.