• Progress in Medical Physics
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• v.17 no.4
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• pp.192-200
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• 2006

We evaluated the positional accuracy of the delivered beams to the target in a phantom by simulating the whole process of the radiation treatments Including CT scanning, planning and beam exposures with MLCs. For this purpose, a phantom was made to calibrate the alignment between the CT and the attached laser system. A new, convenient method was also devised to align the setup lasers in the treatment room. Film was used for the Identification of the delivered beam and analyzed with a homemade computer program. The positional differences between the target and the beam centers varied with the couch rotations. The accelerator we used showed a maximum discrepancy of 2.0 mm at the table angle of $295^{\circ}$. The same measurements based on the new isocenter from the Winston-Lutz test resulted in the maximum of 1.35 mm for all rotation angles. The evaluation of the differences between the target and the beam centers is useful for the treatment planning.

• Korean Journal of Agricultural and Forest Meteorology
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• v.20 no.2
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• pp.228-232
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• 2018

Process-based crop models have been used to assess the impact of climate change on crop production. These models are implemented in procedural or object oriented computer programming languages including FORTRAN, C++, Delphi, Java, which have a stiff learning curve. The requirement for a high level of computer programming is one of barriers for efforts to develop and improve crop models based on biophysical process. In this study, we attempted to develop a Chinese cabbage model using Microsoft Excel with Visual Basic for Application (VBA), which would be easy enough for most agricultural scientists to develop a simple model for crop growth simulation. Results from Soil-Plant-Atmosphere-Research (SPAR) experiments under six temperature conditions were used to determine parameters of the Chinese cabbage model. During a plant growing season in SPAR chambers, numbers of leaves, leaf areas, growth rate of plants were measured six times. Leaf photosynthesis was also measured using LI-6400 Potable Photosynthesis System. Farquhar, von Caemmerer, and Berry (FvCB) model was used to simulate a leaf-level photosynthesis process. A sun/shade model was used to scale up to canopy-level photosynthesis. An Excel add-in, which is a small VBA program to assist crop modeling, was used to implement a Chinese cabbage model under the environment of Excel organizing all of equations into a single set of crop model. The model was able to simulate hourly changes in photosynthesis, growth rate, and other physiological variables using meteorological input data. Estimates and measurements of dry weight obtained from six SPAR chambers were linearly related ($R^2=0.985$). This result indicated that the Excel/VBA can be widely used for many crop scientists to develop crop models.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.28 no.6
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• pp.332-349
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• 2016

OLAFOAM is the powerful CFD code and is an expanded version of $OpenFOAM^{(R)}$, for wave mechanics simulation. The $OpenFOAM^{(R)}$ does provide many solvers to correspond to each object of the numerical calculation in a variety of fields. OLAFOAM's governing equation bases on VARANS (Volume-Averaged Reynolds-Averaged Navier-Stokes) equation, and the finite volume method is applied to numerical techniques. The program is coded in C++ and run on the Linux operating system. First of all, in this study, OLAFOAM was validated for 1) wave transformation inside porous structure under bore and regular wave conditions, 2) wave transformation by submerged breakwater under regular wave condition, and 3) regular wave transformation and resultant vertical velocity distribution under current by comparison with existing laboratory measurements. Hereafter, this study, which is almost no examination carried out until now, analyzed closely variation characteristics of water surface level, wave height, frequency spectrum, breaking waves, averaged velocity and turbulent kinetic energy around porous submerged breakwater in the wave and current coexisting field for the case of permeable or impermeable rear beach. It was revealed that the wave height fluctuation according to current direction(following or opposing) was closely related to the turbulent kinetic energy, and others.

• Journal of Korean Society for Geospatial Information Science
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• v.16 no.1
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• pp.23-32
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• 2008

According to recent frequent local flash flood due to climate change, the very short-term rainfall forecast using remotely sensed rainfall like radar is necessary to establish. This research is to evaluate the feasibility of GIS-based distributed model coupled with radar rainfall, which can express temporal and spatial distribution, for multipurpose dam operation during flood season. $Vflo^{TM}$ model was used as physically based distributed hydrologic model. The study area was Yongdam dam basin ($930\;km^2$) and the 3 storm events of local convective rainfall in August 2005, and the typhoon.Ewiniar.and.Bilis.collected from Jindo radar was adopted for runoff simulation. Distributed rainfall consistent with hydrologic model grid resolution was generated by using K-RainVieux, pre-processor program for radar rainfall. The local bias correction for original radar rainfall shows reasonable results of which the percent error from the gauge observation is less than 2% and the bias value is $0.886{\sim}0.908$. The parameters for the $Vflo^{TM}$ were estimated from basic GIS data such as DEM, land cover and soil map. As a result of the 3 events of multiple peak hydrographs, the bias of total accumulated runoff and peak flow is less than 20%, which can provide a reasonable base for building operational real-time short-term rainfall-runoff forecast system.

• Maxillofacial Plastic and Reconstructive Surgery
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• v.27 no.6
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• pp.552-558
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• 2005

Orthognathic surgery changes patient's mandibular position and environment of related anatomic structures. Many clinicians were interested in these changes and studied about this problem. However, most of them were based on two dimensional cephalogram. According to the development of image and computer system, it would be possible that the airway change is analyzed with three dimensional CT. So we tried to measure the volumetric change of airway and analyzed the relationship between the airway structure and volumetric change. Nineteen patients who experienced orthognathic surgery due to mandibular prognathism were analyzed with 3D CT data (preoperative and postoperative 6 months) and 2D lateral cephalometry. Volumetric change was measured and 3 dimensional change of related structure was assessed with simulation program ($V-works^{(R)}$, 4.0 Cybermed, Korea). Ten patients showed the decrease of airway volume change and nine showed the increase of airway volume change. Volumetric change was determined by dimensional change of mandible and hyoid bone. The dimensional positions of mandible and hyoid bone were the key factor for determining the airway change after surgery. Airway change is also predictable with the dimensional change of mandible and hyoid bone.

• The Journal of the Convergence on Culture Technology
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• v.6 no.4
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• pp.139-147
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• 2020

The number of deaths from child traffic accidents in Korea is currently higher than the average figure of OECD members, and attention needs to be paid to reduce the school zone accident rate. According to the TAAS statistics of the Traffic Accident Analysis System, the number of deaths from traffic accidents in children (under 12 years of age) in Korea has been steadily decreasing recently, but the number of accidents and injuries has been continuously increasing and decreasing. With the number of accidents and injuries of children in Korea continuing to increase and decrease, the number of traffic accidents, deaths, and injuries of children in the school zone (under 12 years of age) has also been on the rise since 2019. Therefore, we were different from the preceding study (Study on Improvement through School Zone Accident Risk Survey, Study on Improvement of Children's Traffic Safety Facilities through Simulation Program). In order to prevent traffic accidents among school zones, which have the highest accident rate among children, a survey was conducted on traffic safety facilities and safety awareness of drivers. After that, we will analyze the problems and present measures for improving traffic safety in the school zone and improving drivers' safety awareness.

• Journal of the Korean Geotechnical Society
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• v.28 no.12
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• pp.5-15
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• 2012

In this study, a series of CFD (Computational Fluid Dynamics) numerical analyses were performed in order to evaluate the thermal performance of six full-scale closed-loop vertical ground heat exchangers constructed in a test bed located in Wonju. The circulation HDPE pipe, borehole and surrounding ground formation were modeled using FLUENT, a finite-volume method (FVM) program, for analyzing the heat transfer process of the system. Two user-defined functions (UDFs) accounting for the difference in the temperatures of the circulating inflow and outflow fluid and the variation of the surrounding ground temperature with depth were adopted in the FLUENT model. The relevant thermal properties of materials measured in laboratory were used in the numerical analyses to compare the thermal efficiency of various types of the heat exchangers installed in the test bed. The simulation results provide a verification for the in-situ thermal response test (TRT) data. The CFD numerical back-analysis with the ground thermal conductivity of 4 W/mK yielded better agreement with the in-situ thermal response tests than with the ground thermal conductivity of 3 W/mK.

• Journal of Sensor Science and Technology
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• v.6 no.5
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• pp.346-355
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• 1997

In this paper, the analyses of the stress disturibution and frequency characteristics of silicon microstructures for an accelerometer were performed using the general purpose finite element simulation program, ANSYS. From the analyses, we determined the parameter values of a new 6-beam piezoresistive accelerometer applicable to the accelerometer's specification in airbag system of automobile. Then, the mass paddle radius, beam length, beam width, and beam thickness of the designed accelerometer were$500{\mu}m$, $350{\mu}m$, $100{\mu}m$, and $5{\mu}m$, respectively and two different seismic masses with 0.4 mg and 0.8 mg were defined on the same sensor structure. The designed 6- beam accelerometers were fabricated on the selectively diffused (111)-oriented $n/n^{+}/n$ silicon substrates and the characteristics of the fabricated accelerometers were investigated. Then, we used a micromachining technique using porous silicon etching method for the formation of the micromechanical structure of the accelerometer.

• The Journal of Korea Institute of Information, Electronics, and Communication Technology
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• v.13 no.1
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• pp.48-57
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• 2020

MCU used in applications such as wireless chargers and USB type-C require MTP memory with a small cell size and a small additional process mask. Conventional double poly EEPROM cells are small in size, but additional processing masks of about 3 to 5 sheets are required, and FN tunneling type single poly EEPROM cells have a large cell size. In this paper, a 110nm MTP cell using a vertical PIP capacitor is proposed. The erase operation of the proposed MTP cell uses FN tunneling between FG and EG, and the program operation uses CHEI injection method, which reduces the MTP cell size to 1.09㎛2 by sharing the PW of the MTP cell array. Meanwhile, MTP memory IP required for applications such as USB type-C needs to operate over a wide voltage range of 2.5V to 5.5V. However, the pumping current of the VPP charge pump is the lowest when the VCC voltage is the minimum 2.5V, while the ripple voltage is large when the VCC voltage is 5.5V. Therefore, in this paper, the VPP ripple voltage is reduced to within 0.19V through SPICE simulation because the pumping current is suppressed to 474.6㎂ even when VCC is increased by controlling the number of charge pumps turned on by using the VCC detector circuit.

• Journal of Korea Water Resources Association
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• v.54 no.7
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• pp.495-507
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• 2021

With the recent industrial development, accidental pollution in riverine environments has frequently occurred. It is thus necessary to simulate pollutant transport and dispersion using water quality models for predicting pollutant residence times. In this study, we conducted a field experiment in a meandering reach of the Sum River, South Korea, to validate the field applicability and prediction accuracy of RAMS+ (River Analysis and Modeling System+), which is a two-dimensional (2D) stream flow/water quality analysis program. As a result of the simulation, the flow analysis model HDM-2Di and the water quality analysis model CTM-2D-TX accurately simulated the 2D flow characteristics, and transport and mixing behaviors of the pollutant tracer, respectively. In particular, CTM-2D-TX adequately reproduced the elongation of the pollutant cloud, caused by the storage effect associated with local low-velocity zones. Furthermore, the transport model effectively simulated the secondary flow-driven lateral mixing at the meander bend via 2D dispersion coefficients. We calculated the residence time for the critical concentration, and it was elucidated that the calculated residence times are spatially heterogeneous, even in the channel-width direction. The findings of this study suggest that the 2D water quality model could be the accidental pollution analysis tool more efficient and accurate than one-dimensional models, which cannot produce the 2D information such as the 2D residence time distribution.