• Progress in Medical Physics
• /
• v.10 no.1
• /
• pp.55-62
• /
• 1999

In an effort to study the characteristics of x-rays utilized in radiation therapy, we calculated the energy distribution and the mean energy of x-rays generated from a tungsten target bombarded by 6, 10, and 15 MeV electron beams, using a Monte Carlo technique. The average photon energies calculated as a function of the beam radius lied in 1.4 ∼ 1.6, 2.1 ∼ 2.5 and 2.8 ∼ 3.3 MeV ranges for 4, 10, and 15 MV electron beams, respectively, which turned out to have no strong dependence on the radius. Using the energy distributions of 6,10, and 15 MV x-rays obtained for the target distance of 100 cm, percentage depth doses were determined using Monte Carlo calculations. For the case 10 MV, a comparison was made between our calculation and measurement performed by others. The calculated percentage depth dose appeared somewhat smaller than the measured one except in the surface region. We conclude that this is due to the fact that the beam hardening effect resulting from the flattening filter was not properly allowed for in our Monte Carlo calculations.

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
• /
• v.20 no.2
• /
• pp.111-118
• /
• 2002

These days, surveying instruments are developing rapidly and the precision is improving continuously. The building of three dimensional terrains of high precision are possible and the calculation of the areas or the volumes have high precision due to the development of the technique of the spatial information system using computer. But actually, in construction site they calculate two-dimensional area using the traditional method, plate table surveying, planimeter, and then get three-dimensional area through multiplying two-dimensional area by the slope correction factor. In this study, we show the defect and inefficiency of the calculation of area by the traditional methods and survey the area with Electric Distance Measurement and GPS instrument. With this data, we made the three dimensional terrain model and calculated two-dimensional area, three-dimensional area. After that, we compared areas that calculated by algorithm of triangulated irregular network and analysis of grid method with standard area that calculated by the traditional method. Finally, this paper suggested more effective and precious method in calculating three-dimensional area.

• Journal of Ocean Engineering and Technology
• /
• v.20 no.3 s.70
• /
• pp.67-76
• /
• 2006

Three-dimensional information of submarine topography was acquired by assembling DGPS and Echo Sounder, which is mainly used in the marine survey. However, the features of submarine topography, derived according to mechanical data, were confirmed using human eyes. Because the dredging capacity using a submarine surveying data influences harbor public affairs, analysis and the process method of surveying data is a very special element in construction costs. In this study, information on submarine topography is acquired by assembling DGPS and Echo Sounder. Moreover, the dredging capacity in harbor public affairs has been analyzed by the interpolation method: inverse distance to a power, kriging, minimum curvature, nearest neighbor, and radial basis function. Also, utilization of DGPS and Echo Sounder method in calculation of the dredging capacity have been confirmed by comparing and analyzing the dredging capacity and the actual one, as per each interpolation. According to this comparison result, in the case of applying Radial basis function interpolation and Kriging, 3.94 % and 4.61 % of error rates have been shown, respectively. In the case of the study for application of the proper interpolation, as per characteristics of submarine topography, is preceded in calculation of the dredging capacity relevant to harbor public affairs, it is expected that more speedy and correct calculation for the dredging capacity can be made.

• Journal of radiological science and technology
• /
• v.44 no.1
• /
• pp.53-58
• /
• 2021

Kerma Area Product (KAP) is best indicator of radiation monitoring on radiographic examinations. KAP can be measured differently depending on the X-ray irradiation area, air kerma, souce-skin distance, type of equipment, etc. The major factors are exposure area and the air krema. The KAP currently used only considers the exposure area with X-rays and has a problem that KAP is always excessively overestimated from the dose received by an actual subject. Therefore, in this study, in order to measure the accurate KAP, a new area dose calculation that can be calculated by dividing the area where the actual X-ray is irradiated is presented, and the KAP is the real area. We compared and analyzed how much it was overestimated compared to the dose. The Skull AP projection and seven other projection were compared and analyzed, and the KAP was overestimated in each test by 52% to 60%. In this way, the effective KAP (EKAP) calculation developed through this study should be utilized to prevent extra calculation of the existing KAP, and only the accurate patient subject area should be calculated to derive the accurate area dose value. EKAP is helpful for control the patient's exposure dose more finely, and it is useful for the quality control of medical radiation exposure.

• Applied Chemistry for Engineering
• /
• v.32 no.1
• /
• pp.102-109
• /
• 2021

Recently, an interest in risk calculation methods has been increasing in Korea due to the establishment of classification code for explosive hazardous area on gas facility (KGS CODE GC101), which is based on the international standard of classification of areas - explosive gas atmospheres (IEC 60079-10-1). However, experiments to check for leaks of combustible or toxic gases are very difficult. These experiments can lead to fire, explosion, and toxic poisoning. Therefore, even if someone tries to provide a laboratory for this experiment, it is difficult to install a gas leakage equipment. In this study we find out differences among actual experiments, CFD by using FLACS and calculation based on classification code for explosive hazardous area on gas facility (KGS CODE GC101) by comparing to each other. We develpoed KGS HAC (hazardous area classification) program which based on KGS GC101 for convenience and popularization. As a result, actual gas leak, CFD and KGS HAC are showing slightly different results. The results of dispersion of 1.8 to 2.7 m were shown in the actual experiment, and the CFD and KGS HAC showed a linear increase of about 0.4 to 1 m depending on the increase in a flow rate. In the actual experiment, the application of 3/8" tubes and orifice to take into account the momentum drop resulted in an increase in the hazardous distance of about 1.95 m. Comparing three methods was able to identify similarities between real and CFD, and also similarities and limitations of CFD and KGS HAC. We hope these results will provide a good basis for future experiments and risk calculations.

• Journal of the Korean Society for Aeronautical & Space Sciences
• /
• v.50 no.3
• /
• pp.157-164
• /
• 2022

In this paper, we describe how to implement the mountainous terrain, radar, and air defense network for UAV path planning in a 3-D environment, and perform path planning and re-planning using the PRM algorithm, a sampling-based path planning algorithm. In the case of the original PRM algorithm, the calculation to check whether there is an obstacle between the nodes is performed 1:1 between nodes and is performed continuously, so the amount of calculation is greatly affected by the number of nodes or the linked distance between nodes. To improve this part, the proposed LineGridMask method simplifies the method of checking whether obstacles exist, and reduces the calculation time of the path planning through parallelization. Finally, comparing performance with existing PRM algorithms confirmed that computational time was reduced by up to 88% in path planning and up to 94% in re-planning.

• Nuclear Engineering and Technology
• /
• v.56 no.1
• /
• pp.78-91
• /
• 2024

Double steel plate concrete composite shear wall (SCSW) has been widely utilized in nuclear power plants and high-rise structures, and its shear connectors have a substantial impact on the seismic performance of SCSW. Therefore, in this study, the mechanical properties of SCSW with angle stiffening ribs as shear connections were parametrically examined for the reactor containment structure of nuclear power plants. The axial compression ratio of the SCSW, the spacing of the angle stiffening rib arrangement and the thickness of the angle stiffening rib steel plate were selected as the study parameters. Four finite element models were constructed by using the finite element program named ABAQUS to verify the experimental results of our team, and 13 finite element models were established to investigate the selected three parameters. Thus, the shear capacity, deformation capacity, ductility and energy dissipation capacity of SCSW were determined. The research results show that: compared with studs, using stiffened ribs as shear connectors can significantly enhance the mechanical properties of SCSW; When the axial compression ratio is 0.3-0.4, the seismic performance of SCSW can be maximized; with the lowering of stiffener gap, the shear bearing capacity is greatly enhanced, and when the gap is lowered to a specific distance, the shear bearing capacity has no major affect; in addition, increasing the thickness of stiffeners can significantly increase the shear capacity, ductility and energy dissipation capacity of SCSW. With the rise in the thickness of angle stiffening ribs, the improvement rate of each mechanical property index slows down. Finally, the shear bearing capacity calculation formula of SCSW with angle stiffening ribs as shear connectors is derived. The average error between the theoretical calculation formula and the finite element calculation results is 8% demonstrating that the theoretical formula is reliable. This study can provide reference for the design of SCSW.

• KSCE Journal of Civil and Environmental Engineering Research
• /
• v.30 no.4D
• /
• pp.369-376
• /
• 2010

At present, many problems in traffic operation and safety occurs since there is no clear design criteria on designating the not-permitted entrance/exit section at curb areas within complex areas. Even, there is no specific and detailed researches on the not-permitted entrance/exit section by now. This research calculated the proper length of the entrance/exit section at curb areas by dividing the access not-permitted section into the two sections. First, the calculation of the entrance section was done by considering the location of crosswalks, stop line clearance, the queue length of vehicles approaching to second lanes, and marginal distance for safety have been considered. Second, the calculation of the exit section was done by comparing and analyzing the distance between cars of the entrance section according to the investigation point and the distance considering the location of crosswalks, the behavior of exit vehicles and the length of vehicles. In conclusion, by presenting the proper length in consideration of the traffic operation and safety on the access not-permitted section within complex areas, it can be used as a traffic safety improvement alternative and will be contributed in establishing and operating the proper installation criteria for the access not-permitted section within complex areas.

• Fire Science and Engineering
• /
• v.15 no.4
• /
• pp.1-9
• /
• 2001

The purpose of this study is to set up disaster prevention plan and risk assessment system considering combustion velocity at traditional housing zone. The combustion velocity analysis could contribute to build in disaster prevention technique through the potential risk analysis of the area, such analysis also able to set up comprehensive disaster prevention management system. Following results have achieved through the combustion velocity calculation. \circled1 The combustion velocity was calculated in order of the below winds, the above winds and the side winds. \circled2 It must be careful to set up disaster prevention plan in case of the below winds. \circled3 The combustion velocity was calculated at the density Bone where neighboring Distance and Length was small. \circled4 It proved that factors of each parameter not mostly effect to analyse the combustion velocity in limit of the 30 minutes after ignition. \circled5 At the density zone where Distance and Length is small the duration of transfer to neighboring house takes up to 4 minutes, it is required to set up of emergency response plan to minimize the fire dispersion.

• Journal of Biomedical Engineering Research
• /
• v.26 no.5
• /
• pp.295-300
• /
• 2005

We introduce an x-ray micro tomography system capable of high resolution imaging of a local region inside a small animal. By combining two kinds of projection data, one from a full field-of-view (FOV) scan of the whole body and the other from a limited FOV scan of the region of interest, we have obtained zoomed-in images of the region of interest without any contrast a nomalies. We have integrated a micro tomography system using a micro-focus x-ray source, a $1248\times1248$ flat-panel x-ray detector, and a precision scan mechanism. Using the cross-sectional images taken with the zoom-in micro tomography system, we measured trabecular thicknesses of femur bones in postmortem rats. To compensate the limited spatial resolution in the zoom-in micro tomography images, we used the fuzzy distance transform for the calculation of the trabecular thickness. To validate the trabecular thickness measurement with the zoom-in micro tomography images, we compared the measurement results with the ones obtained from the conventional micro tomography images of the extracted bone samples.