• Journal of the Korean Society of Radiology
• /
• v.11 no.5
• /
• pp.371-377
• /
• 2017

General phantom for practical X-ray photography Practical phantom is an indispensable textbook for radiology, but it is difficult for existing commercially available phantom to be equipped with various kinds of phantom because it is an expensive import. Using 3D printing technology, I would like to make the general phantom for practical X-ray photography less expensive and easier. We would like to use a skeleton model that was produced based on CT image data using a 3D printer of FDM (Fused Deposition Modeling) method as a phantom for general X-ray imaging. 3D slicer 4.7.0 program is used to convert CT DICOM image data into STL file, convert it to G-code conversion process, output it to 3D printer, and create skeleton model. The phantom of the completed phantom was photographed by X - ray and CT, and compared with actual medical images and phantoms on the market, there was a detailed difference between actual medical images and bone density, but it could be utilized as a practical phantom. 3D phonemes that can be used for general X-ray practice can be manufactured at low cost by utilizing 3D printers which are low cost and distributed and free 3D slicer program for research. According to the future diversification and research of 3D printing technology, it will be possible to apply to various fields such as health education and medical service.

• Journal of the Korean Ceramic Society
• /
• v.41 no.12 s.271
• /
• pp.929-932
• /
• 2004

It is known that small amount of MgO in excess is often added to develop pure perovskite single phase of PMN-based composite, however, extra MgO precipitates in grains and inhibits densification of PMN. In this study PMN-PT-BT (PBT) powder was prepared by a conventional mixed oxide method using $(MgCO_3)_4{\cdot}Mg(OH)_2{\cdot}5H_{2}O$ instead of MgO. The precursor was heated at $500^{\circ}C/1h$ and its surface was modified with MgO sol. This effect was investigated in the aspects of sintering and dielectric properties. Small amount of added MgO sol ($0.5{\sim}1.0wt\%$) enhanced sintering substantially below $1000^{\circ}C$. The PBT with $0.5wt\%$ MgO sol sintered at $900^{\circ}C/2h$ had density of $7.62\;g/cm^3$, room temperature dielectric constant of 14800, loss of dielectric constant of $1.1\%$, which were comparable to those of the PBT sintered at $1000^{\circ}C/2h$. It was noticeable that the extra MgO precipitated mostly on triple points and grain boundaries and resulted in inhibition of grain growth.

• Korean Journal of Environmental Biology
• /
• v.29 no.4
• /
• pp.345-352
• /
• 2011

We investigated 12 plots using Herles' diversity of structure feature calculation method, which is based on the Shannon-Weaver-Index for estimation of species diversity. This study sought to facilitate a more systematic understanding of the structure of the forest stands in the Korean fir natural forest in Naeseorak. Although the change in the forest structure is dependent on the change in phase, factors of the natural forest were confirmed by associating individual structure features. As shown in the results of diversity of structure features, the diversity of the structure of the fir tree natural forest in Naeseorak was relatively low. The association between species diversity and overall factors (diversity) related with the change in the structure was found to be weak. The association between the number of trees and the diversity of forest structure stands was moderate, showing that the higher the number of trees, the less diverse the forest structure is. In most of the investigated plots, stem volume and volume of dead tree were associated with the height of natural regeneration, but these were not associated with other factors. Height of natural regeneration was found to be correlated to stand density, crown area and crown class, whereas tree height and BHD did not have any association with other factors. Overall, the results of the investigation are helpful in understanding the change in the structure of Korean fir natural forest. Further investigation with more plots is required.

• Journal of Energy Engineering
• /
• v.21 no.1
• /
• pp.55-67
• /
• 2012

For the development of gas hydrate as new future energy resources, the drilling was carried out at the five locations where have high potential as gas hydrate bearing sediments in Ulleung basin, offshore Korea in 2007. Well log data were obtained from all wells and core data were procured from 3 wells, UBGH1-04, UBGH1-09 and UBGH1-10. In this study, user-friendly software, "KMU GH Logs 2010", is developed and this software is based on the estimation methods developed in previous study for gas hydrate bearing sediments and the properties estimated from UBGH1-04, UBGH1-09 and UBGH1-10. Petrophysical properties in un-cored wells, UBGH1-01 and UBGH1-14, are also estimated by using well log data. Porosity is estimated by density log and gas hydrate saturation is calculated by sonic log and resistivity log. Sedimentary facies are estimated by applying the linear discriminant analysis using both well log and sedimentary facies data from core analysis. It is confirmed that DITM facies and MSS facies appeared signs of gas hydrate disassociation are able to be distinguished by the method.

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
• /
• v.32 no.5
• /
• pp.469-479
• /
• 2014

N-RTK(Network based RTK) methods are able to improve the accuracy of GNSS positioning results through modelling of the distance-dependent error sources(i.e. primarily the ionospheric and tropospheric delays and orbit errors). In this study, the comparison of the TTFF(Time-To-Fix-First ambiguity), accuracy and discrepancies in horizontal/vertical components of N-RTK methods(VRS and FKP) with the static GNSS at 20 Unified Control Stations covering Incheon metropolitan city area during solar storms(Solar cycle 24 period) were performed. The results showed that the best method, compared with the statics GNSS survey, is the VRS, followed by the FKP, but vertical components of both VRS and FKP were approximately two times bigger than horizontal components. The reason for this is considered as the ionospheric scintillation because of irregularities in electron density, and the tropospheric scintillation because of fluctuations on the refractive index take the place. When the TTFF at each station for each technique used, VRS gave shorter initialization time than FKP. The possible reasons for this result might be the inherent differences in principles, errors in characteristics of different correction networks, interpolating errors of FKP parameters according to the non-linear variation of the dispersive and non-dispersive errors at rover when considering both domestic mobile communication infra and the standardized high-compact data format for N-RTK. Also, those test results revealed degradation of positing accuracy, long initialization time, and sudden re-initialization, but more failures to resolve ambiguity during space weather events caused by Sunspot activity and solar flares.

• Journal of Nutrition and Health
• /
• v.34 no.1
• /
• pp.30-38
• /
• 2001

This research was conduced to 1) examine the influence of milk group intake on the dietary, considering dietary diversity and nutrient adequacy, 2) identify which foods truly contribute to the intake of specific nutrients 3) point out the dietary problems of this age group. The subjects were 664(male 357, female 307) healthy toddlers of the ages of 12-36 months, who had neither been taking any medicine-type supplements nor had any diseases that affect the dietary intakes, chosen among the outpatients of university and private hospitals in Seoul and Kyonggi province during Mach-August, 1999. The 24 hour recall method and CAN Pro(food analysis program) were used to analyze the amount of nutrient intake. The grouping of the subjects for the analysis by monthly age was based on the 98 Korean Child growth standard. The results that the milk group intake showed significant negative correlations with the grain group(r=-0.194, p<0.01), the vegetable group(r=-0.115, p<0.01) and the fruit group(r=-0.125, p<0.01). It also showed that the more the milk group intake, the lower the Dietary Diversity Score(r=-0.131, p<0.01), and the more the intake of raw milk, the more dificient the intake of iron(r=-0.211, p<0.01), vitamin A(r=-0.169,p<0.01), vitamin B$_1$(r=-0.078, p<0.05) and vitamin C(r=-0.187, p<0.01). Foods contributory to nutrient intake for of 12-14 months of were mostly infant formula, and the contribution ratio was high. In the age of 15-17 months, the subjects obtained most of the nutrients from raw milk., liquid-type yoghurt, soybean milk, cooked rice, etc. As for iron intake, the age of 21-23 month obtained the most from ionic drinks, and 24-29 months from raw milk, chocolate cakes, ionic drinks, etc. Though the NAR(Nutrient Adequacy Ratio) and MAR(Mean Adequacy Ratio) generally tended to increase accordingly with the DDs, as for nutrients Ca, vitamin A, vitamin B$_1$, and vitamin C the NAR marked the highest when the DDS marked the lowest(due to infant formula). And for iron, even when the DDS was 5 the NAR value was low. Im conclusion, the more the milk group intake, the lower was the dietary diversity. High dependency on infant formula and others from milk group over the age of 12 months proved to result in a decrease of nutritious solid food intake, iron deficiency and a low dietary diversity score, which can lead to an unbalanced diet. Therefore, nutrition education towards mothers/caretakers of toddler is of urgent need, in order to reduce the fluid milk group intake of low nutritional density and to provide various solid foods the children. (Korean J Nutrition 34(1):30-38, 2001)

• Korean Journal of Remote Sensing
• /
• v.36 no.2_1
• /
• pp.103-119
• /
• 2020

Recently, the rapid redeposition and erosion of rivers artificially created by climate change and the Four Rivers Restoration Project is questionable. According to the revised law in Korea, the river management agency will periodically carry out bed changes surveys. However, there are technical limitations in contrast to the trend of increasing spatial coverage, density and narrowing of intervals. National organizations are interest in developing innovative bed changessurvey techniquesfor efficiency. Core of bathymetry survey is to measure the depth of rivers under a variety of river conditions, but that is relatively more risky, time-consuming and expensive compared to conventional ground surveys. To overcome the limitations of traditional technology, echo sounder, which has been mainly used for ocean depth surveying, has been applied to rivers. However, due to various technical limitations, it is still difficult to periodically investigate a wide range of areas. Therefore, technique using the remote sensing has been spotlighted as an alternative, especially showing the possibility of depth measurement using spectral characteristics. In this study, we develop and examine a technique that can measure depth of water using reflectance from spectral characteristics. As a result of applying the technique proposed in thisstudy, it was confirmed that the measured depth and the correlation and error corresponding to 0.986 and 0.053 m were measured in the depth range within 0.95 m. In the future, this study could be applied to the measurement of spatial depth if it is applied to the hyperspectral sensor mounted on the drone.

• Journal of KIISE:Software and Applications
• /
• v.30 no.3_4
• /
• pp.326-338
• /
• 2003

The objective of a neural network design and model selection is to construct an optimal network with a good generalization performance. However, training data include noises, and the number of training data is not sufficient, which results in the difference between the true probability distribution and the empirical one. The difference makes the teaming parameters to over-fit only to training data and to deviate from the true distribution of data, which is called the overfitting phenomenon. The overfilled neural network shows good approximations for the training data, but gives bad predictions to untrained new data. As the complexity of the neural network increases, this overfitting phenomenon also becomes more severe. In this paper, by taking statistical viewpoint, we proposed an integrative process for neural network design and model selection method in order to improve generalization performance. At first, by using the natural gradient learning with adaptive regularization, we try to obtain optimal parameters that are not overfilled to training data with fast convergence. By adopting the natural pruning to the obtained optimal parameters, we generate several candidates of network model with different sizes. Finally, we select an optimal model among candidate models based on the Bayesian Information Criteria. Through the computer simulation on benchmark problems, we confirm the generalization and structure optimization performance of the proposed integrative process of teaming and model selection.

• Journal of the Microelectronics and Packaging Society
• /
• v.20 no.2
• /
• pp.39-46
• /
• 2013

In this paper, organic solar cells(OSCs) based on bulk-heterojunction structures were fabricated by spin coating method using polymer P3HT and fullerene PCBM as a photoactive layer. The fabricated OSCs had a simple glass/ITO/PEDOT:PSS/P3HT:PCBM/Al structures. The photoactive layer of mixed P3HT:PCBM was formed with 1:1 weight ratio. The hole transport layer(HTL) was used conducting polymer PEDOT:PSS concentration with gold nanoparticles. The annealing temperature and concentration of nanoparticles in HTL were verified to improve the OSC characterization. The percentage of gold nanoparticles in HTL were 0.5 wt% and 1.0 wt%, and the surface morphology, electrical properties and absorption intensities were investigated. The devices were 0.5 wt%, and the highest 3.1% of the powder conversion efficiency(PCE), 10.2 $mA/cm^2$ of the maximum short circuit current density($J_{SC}$), 0.535V of the open circuit voltage($V_{OC}$) and 55.8% of the fill factor(F.F) could be obtained when the nanoparticle concertration was 0.5 wt%. The annealing temperature of HTL was $110^{\circ}C$, $130^{\circ}C$, $150^{\circ}C$ in vacuum oven and measured the absorption intensities, surface morphology, crystallinity and electrical properties were investigated. The best property was obtained in HTL annealed at $130^{\circ}C$ for gold nanoparticles of 0.5 wt%, showing that $J_{SC}$, $V_{OC}$, F.F and PCE were about 12.0 $mA/cm^2$, 0.525V, 64.2% and 4.0%, respectively.

• International Journal of Highway Engineering
• /
• v.7 no.4 s.26
• /
• pp.21-30
• /
• 2005

Traffic volume data have been used for the plan, the design, and the operation of highway. Since 1955, traffic survey has been nation- widely carried out at national highway and the regular survey in national highway has been conducted at the intersections of highways. However, it is critical issue to select the priority of the regular survey because it is almost impossible to conduct regular survey at all intersections of national highways. In this study, MCDM(Multiple Criteria Decision Making) using AHP(Analytic Hierarchy Process) was applied to decide the priority of the regular survey. The following standard variables for determining the priority was selected the highway plan variables[AADT, VKT, Peak Hourly Volume, Location of highway from Urban], the highway design variables[Volume(pcu), Directional Traffic Volume, Heavy Vehicle Rate], and the highway operation variables[Speed, Density, V/C]. The standard variables were quantified and normalized. Using the Eigen vector method, the weighted values of each hierarchy based on the pair-wise comparison values from the questionnaire survey were calculated. The selection of the priority of regular survey was dependent on the size of the product of the weighted values for each hierarchy and the normalized values for the standard variables. Finally, the priority of regular survey of the intersections of national highways was determined according to the order in the size of the product of two values.