• Journal of Radiation Protection and Research
• /
• v.48 no.3
• /
• pp.153-161
• /
• 2023

Background: Fukushima Medical University (FMU) is located 57 km northwest of the Fukushima Daiichi Nuclear Power Plant. Our laboratory has been conducting environmental radiation measurements continuously before and after the nuclear accident. We aimed to report the observed behavior of radiation originating from the released radioactive materials due to the accident, predict future trends, and disseminate the results to the local residents. Materials and Methods: Measurements of the counting rate by a diameter of 76 mm and a length of 76 mm thallium-doped sodium iodide (NaI[Tl]) scintillation detector (S-1211-T; Teledyne Brown Engineering Environmental Services) in the central part of the laboratory, and the dose rate outward at the window by NaI(Tl) scintillation detector and digital processor (EMF211; EMF Japan Co. Ltd.) were conducted. Results and Discussion: Measurements by Teledyne S-1211-T showed that in the early stages, radiation from radioactive isotopes with short half-lives was dominant, while radiation from radioactive isotopes with longer half-lives became dominant as the measurement period became longer. Through nonlinear least squares regression, both short and long half-lives were successfully determined. It was also possible to predict how the radiation dose would decrease. The environmental radiation trends around FMU were measured by the EMF211. Both measurements were affected by rainfall and snow accumulation. Decontamination work on the FMU campus impacted measurements by the EMF211 especially. Conclusion: The results of two types of measurements, one at the center and the other at the window side of the laboratory, were presented. By applying a simplified model, radiation from radioactive isotopes with short and long half-lives was identified. Based on these results, future trends were predicted, and the information was used for public communication with the local residents.

• International Journal of Naval Architecture and Ocean Engineering
• /
• v.6 no.4
• /
• pp.788-799
• /
• 2014

This study conducted four field measurements of local ice pressure during the icebreaking voyage of the icebreaking research vessel "ARAON" in the Chukchi and Beaufort seas from July to August of 2010. For measurements, 14 strain gauges, including 8 strain gauge rosettes, were set on the bow of the port side. Influence coefficients were determined using a finite element model of the instrumented area and they were used to convert the measured strains on the hull structure to local ice pressures. The converted maximum pressure was calculated as 2.12 MPa on an area of $0.28m^2$. Pressure-area curves were developed from the surveyed pressure data and the results were compared with previously measured data. The study results are expected to provide an understanding of local ice pressures and thus be useful in the structural design of ice class ships.

• Journal of Technologic Dentistry
• /
• v.27 no.1
• /
• pp.27-39
• /
• 2005

This study is to show the qualitative analytic methods of facial asymmetry with three-dimensional morphometry and find out asymmetry change resulted from enlarging three local regions. Steel balls (1.2mm in diameter) were attached in twenty seven landmarks of a symmetrical artificial human skull. This artificial human skull was used as experimental materials. Twelve different asymmetrical artificial human skulls were formed by gradually enlarging the mandibular body length, gonial angle, and ramus height of the left hemiface. From the three-dimensional morphometry of each skull type, nine local area measurements and three total sum area measurements(representing the mandibular area, maxillary area, and lower facial area) were acquired and made into the surface area asymmetry degree. Menton deviation itself was used as the surface area asymmetry degree while right-left percentages were used in the other measurements. These surface area asymmetry degrees were compared with each other to find out asymmetry change according to the degree of actual facial asymmetry. Through the statistical analysis, following results were obtained. The results were as follows: 1. Left maxillary area of artificial human skull was 7.13$\pm$0.26% larger while mandibular area was 4.14$\pm$0.12% smaller than each those of right hemiface. After all, left lower facial area was 1.44$\pm$0.07% larger than those of right hemiface.(n=7). 2. Among the reduce rates of surface area asymmetry degree resulted from enlarging three local regions, ramus height was similar to mandibular body length while it was bigger than those of gonial angle. 3. Among the increase rates of menton deviation resulted from enlarging the local regions, ramus height was the biggest, mandibular body length was the second and gonial angle was the smallest. These results suggest that three-dimensional morphometry can be used to qualitatively analyse facial asymmetry and the asymmetry degree is more influenced by enlarging the ramus height, mandibular body length than those of gonial angle.

• 한국연소학회:학술대회논문집
• /
• 2004.11a
• /
• pp.91-96
• /
• 2004

Simultaneous CH and OH planar laser induced fluorescence(PLIF) and stereoscopic particle image velocimetry (PIV) measurements have been developed to investigate the local flame structure of turbulent premixed flames. The developed simultaneous two radical concentrations and three component velocity measurements on a two-dimensional plane was applied for relatively high Reynolds number turbulent premixed flames in a swirl stabilized combustor. All measurements were conducted for methane-air premixed flames in the corrugated flamelets regime. Strong three-dimensional fluctuation implies that misunderstanding of the flame/turbulent interactions would be caused by the analysis of two-component velocity distribution in a cross section. Furthermore, comparisons of CH-OH PLIF and three-component velocity field show that the burned gases not always have high-speed velocity in relatively high Reynolds number turbulent premixed flame. The Reynolds number dependence of the flame front was clearly captured by the simultaneous CH-OH PLIF and stereoscopic PIV measurements.

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
• /
• v.40 no.4
• /
• pp.325-332
• /
• 2022

Determination of VLBI IVP (Very Long Baseline Interferometry Invariant Point) position with high accuracy is required to compute local tie vectors between the space geodetic techniques. In general, reflective targets are attached on VLBI antenna and slant distances, horizontal and vertical angles are measured from the pillars. Then, adjustment computation is performed by using the mathematical model which connects measurements and unknown parameters. This indicates that the accuracy of the estimated solutions is affected by the accuracy of the measurements. One of issues in local tie surveying, however, is that the reflective targets are not in favorable condition, that is, the reflective sheet target cannot be perfectly aligned to the instrument perpendicularly. Deviation from the line of sight of an instrument may cause different type of measurement errors. This inherent limitation may lead to incorrect stochastic modeling for the measurements in adjustment computation procedures. In this study, error characteristics by measurement types and pillars are analyzed, respectively. The analysis on the studentized residuals is performed after adjustment computation. The normality of the residuals is tested and then equal variance test between the measurement types are performed. The results show that there are differences in variance according to the measurement types. Differences in variance between distances and angle measurements are observed when F-test is performed for the measurements from each pillar. Therefore, more detailed stochastic modeling is required for optimal solutions, especially in local tie survey.

• Transactions of the Korean Society of Mechanical Engineers B
• /
• v.33 no.5
• /
• pp.365-372
• /
• 2009

The influence of combustor pressure on the local reaction characteristics of $CH_4$/air flames was investigated by measurements of local chemiluminescence intensity. Induced flow flames are often applied to the industrial boiler systems and incinerator in order to improve heat transfer and prevent exhaust gas leakage. In order to investigate combustion characteristics in the induced flow pattern, the combustor pressure index($P^*$) was controlled in the range of $0.7{\sim}1.3$ for each equivalence ratio in the present combustion system, where $P^*$ is defined as the ratio of absolute pressure to atmospheric one. Relationship between local reaction intensity and pressure index have been investigated by simultaneous $CH^*$, $C^*_2$ and $OH^*$ intensity measurements. It could be observed that flame length became longer with decreasing $P^*$ from $CH^*$ chemiluminescence intensity of axial direction. The mean value of $C^*_2$ and $CH^*$ chemiluminescence intensities, which indicates reaction intensity in the $CH_4$/air flames, decreased with decreasing pressure index for ${\Phi}{\leq}1$, but increased with decreasing pressure index for ${\Phi}$>1. $C^*_2/CH^*$ intensity ratio, which can be a good marker to demonstrate local equivalence ratio, was almost same for ${\Phi}{\leq}1$ regardless of pressure index change, while they showed high level for lower pressure index for ${\Phi}$>1 conditions.

• Journal of the Korean Society for Precision Engineering
• /
• v.22 no.6 s.171
• /
• pp.213-221
• /
• 2005

An insole type local shear force measurement system was developed and local shear stresses in the foot were measured during level walking. The shear force transducer based on the magneto-resistive principle, was a rigid 3-layer circular disc. Sensor calibrations with a specially designed calibration device showed that it provided relatively linear sensor outputs. Shear transducers were mounted on the locations of four metatarsal heads and heel in the insole. Sensor outputs were amplified, decorded in the bluetooth transmission part and then transferred to PC. In order to evaluate the developed system, both shear and plantar pressure measurements, synchronized with the three-dimensional motion analysis system, were performed on twelve young healthy male subjects, walking at their comfortable speeds. The maximum peak pressure during gait was 5.00kPa/B.W at the heel. The time when large local shear stresses were acted correlated well with the time of fast COP movements. The anteroposterior shear was dominant near the COP trajectory, but the mediolateral shear was noted away from the COP trajectory. The vector sum of shear stresses revealed a strong correlation with COP movement velocity. The present study will be helpful to select the material and to design of foot orthoses and orthopedic shoes for diabetic neuropathy or Hansen disease.

• Earthquakes and Structures
• /
• v.15 no.5
• /
• pp.463-471
• /
• 2018

The virtual forces of the original local flexibility method are restricted to inducing stress on the local parts of a structure. To circumvent this restriction, we developed a pseudo local flexibility (PLFM) method that can successfully detect damage to hyperstatic beam structures using fewer modes. For this study, we further developed the PLFM so that it could detect damage in plate structures. We also devised the theoretical background for the PLFM with non-local virtual forces for plate structures, and both the lateral and rotary degree of freedom (DOF) measurements were considered separately. This study investigates the effects of the number of modes, the actual location that sustained damage, multiple damage locations, and noise in modal parameters for the damage detection results obtained from damaged numerical plates. The results revealed that the PLFM can be used for damage detection, localization, and quantification for plate structures, regardless of the use of the lateral DOF and/or rotary DOF.

• Journal of Electrical Engineering and Technology
• /
• v.3 no.4
• /
• pp.451-459
• /
• 2008

Accurate load modeling is essential for power system static and dynamic analysis. By the nature of the problem of parameter estimation for power system load modeling using actual measurements, multiple local optimal solutions may exist and local methods can be trapped in a local optimal solution giving possibly poor performance. In this paper, Trust-Tech, a novel methodology for global optimization, is applied to tackle the multiple local optimal solutions issue in measurement-based power system load modeling. Multiple sets of parameter values of a composite load model are obtained using Trust-Tech in a deterministic manner. Numerical studies indicate that Trust-Tech along with conventional local methods can be successfully applied to power system load model parameter estimation in measurement-based approaches.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
• /
• v.12 no.10
• /
• pp.886-893
• /
• 2000

A good understanding of the heat transfer distribution is very important to suppress the deformation of steel products. In this study, the local heat transfer coefficients are experimentally investigated to understand the heat transfer distribution of thick steel plates with even flat spray nozzle. The steel slabs are cooled down from the initial temperature of about $1000^{\circ}C$ , and the local heat transfer coefficients and surface temperatures are calculated from the measured temperature-time history. The results show that the local heat transfer coefficients of spray cooling are dominated by the local droplet flow rate, and in proportion to becoming more distant from the center of heat transfer surface, the local heat transfer coefficients decrease with the decrease of the local droplet flow rate.