• Progress in Medical Physics
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• v.20 no.4
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• pp.225-234
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• 2009

Geant4 (GEometry ANd Tracking) provides various packages specialized in modeling electromagnetic interactions. The validation of Geant4 physics models is a significant issue for the applications of Geant4 based simulation in medical physics. The purpose of this study is to evaluate accuracy of Geant4 electromagnetic physics for proton therapy. The validation was performed both the Continuous slowing down approximation (CSDA) range and the stopping power. In each test, the reliability of the electromagnetic models in a selected group of materials was evaluated such as water, bone, adipose tissue and various atomic elements. Results of Geant4 simulation were compared with the National Institute of Standards and Technology (NIST) reference data. As results of comparison about water, bone and adipose tissue, average percent difference of CSDA range were presented 1.0%, 1.4% and 1.4%, respectively. Average percent difference of stopping power were presented 0.7%, 1.0% and 1.3%, respectively. The data were analyzed through the kolmogorov-smirnov Goodness-of-Fit statistical analysis test. All the results from electromagnetic models showed a good agreement with the reference data, where all the corresponding p-values are higher than the confidence level $\alpha=0.05$ set.

• The Journal of Engineering Geology
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• v.23 no.4
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• pp.389-398
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• 2013

Studies of the thermal properties of various rock types obtained from several locations in Korea have revealed significant differences in thermal conductivities in the thermal response test (TRT), which has been applied to the design of a ground-source heat pump system. In the present study, we aimed to compare the thermal conductivities of the samples with those obtained by TRT. The thermal conductivities of soil and rock samples were 1.32W/m-K and 2.88 W/m-K, respectively. In comparison, the measured TRT value for thermal conductivity was 3.13W/m-K, which is 10% higher than that of the rock samples. We consider that this difference may be due to groundwater flow because abundant groundwater is present in the study area and has a hydraulic conductivity of 0.01. It is natural to consider that the object of TRT is to calculate the original thermal conductivity of the ground, following the line source theory. Therefore, we conclude that the TRT applied to a domestic standing column type well is not suitable for a line source theory. To solve these problems, values of thermal conductivity measured directly from samples should be used in the design of ground-source heat pump systems.

• Journal of Science Education
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• v.36 no.2
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• pp.394-407
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• 2012

This study analyzed the result of the National Assessment of Educational Achievement (NAEA) in a Grade 9 Science class. The study first found that the ratio of below basic achievement was 8.1 percent. This means that a large number of middle school students have not reached basic scientific literacy. Second, the ratio of male students in the below basic level was 10.4 percent, which was double the ratio of female students at 5.5 percent. Third, according to the analysis of achievement by gender, female students outperformed male students. In addition, the female students' standard deviation was smaller than that of the male students, and their scaled scores were distributed nearer the average than that of the male students. Furthermore, analysis of achievement by content domains indicated that females outperformed in all content domains including motion and energy, materials, life, and earth sciences. Showing a similar tendency in the behavior domains, females outperformed males in all behavior domains except the understanding domain. Last, for achievement by living area, students living in the middle and small cities showed the highest scaled score, 196.81. Whereas the average scaled score of the students living in the big cities was 196.15; that of the students living in rural areas was 194.86. With respect to the standard deviation, big cities had the largest, 33.73. That of middle and small cities was 33.70, and of rural areas was 32.92. Although students in cities showed higher achievement in science compared to students in rural areas, they had a bigger gap in academic achievement.

• Economic and Environmental Geology
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• v.35 no.6
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• pp.545-552
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• 2002

In order to investigate the influence of nuclear power plant operation on its nearby environment, soil, stream and marine sediment samples were collected in the vicinity of the Youngkwang Nuclear Power Plant in Korea, and analyzed for artificial and natural radionuclide radioactivity. From the analytical result, Cs-137 was detected in most soil samples. but it may have been derived fiom past nuclear weapon tests because Cs-134 having short half-live was not detected. The radioactivities of Cs-137 in the sediment samples were also detected which are within the normal range in the sediments based upon the published literature between 1997 and 1999. For the quality control of radioactivity analysis of environmental samples, sets of marine sediments in the Gamami area were analyzed using two HPGe Gamma-ray Spectroscopes (30% and 45%) according to the geostatistical sampling strategy, and Cs-137 and K-40 results were interpreted by analysis of variance (ANOVA). In the two-way ANOVA, variances derived from the geochemical variation were significant, but errors from sampling and analytical procedures are negligible. In conclusion. all the radioanalytical procedures of this study including sampling are validated to be acceptable.

• Korean Journal of Food Science and Technology
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• v.24 no.3
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• pp.256-260
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• 1992

This study was conducted to calculate and predict the shelf-life of meat sausage through physicochemical and biological analysis. Judging from physico-chemical components, it can be found out the most effective indicator in meat sausage. And also, the materials used for packaging is cellulose #23 in inner-packaging and CN/HDPE laminating film in outer-packaging. The changes of the most effective indicator were discussed through the method of kinetic analysis. Judging from physico-chemical components, VBN was the most available component in quality judgement of meat sausage and their upper limiting contents were 20 mg%. It is possible to calculate and predict the shelf-life of meat sausage through the regression equation and $Q_{10}$ value. As a result, the shelf-life prediction was $58{\sim}63$ days at $10^{\circ}C$, $47{\sim}51$ days at $20^{\circ}C$ and 26 days at $40^{\circ}C$, respectively, but the difference between two methods showed about $4{\sim}5$ days. $Q_{10}$ value on the changes contents was 1.35 at acceralated temperature $40^{\circ}C$. The reaction rate of VBN contents could be interpreted as a first order reaction that divided into 2 periods with different reaction rate constants. The corresponding Arrhenius activation energies were 2.959 Kcal/mole and 3.632 Kcal/mole, respectively.

• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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• v.4 no.4
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• pp.312-322
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• 1999

We have studied both submarine morphology and sediment characteristics of waste disposal sites in the southwestern Ulleung Basin, East Sea, as part of a marine environmental preservation program. The Jung waste disposal site in the outer shelf is characterized by the thick accumulation of coarse-grained palimpsest sediments and fine-grained sediments from various sources. The Byung waste disposal site in the continental slope is generally characterized by hemipelagic muds with intermittent sandy sediments originated from the outer shelf and upper slope. The hemipelagic sediments, draping the seafloor, consist of fluidized muds. The core sediments show numerous bioturbation structures which cause vertical mixing of sediments. The surface sediments can be divided into four sand types (S-1, S-2, S-3, and S-4) and two mud types (M-1 and M-2) based on relative contents of reworked coarse-grained palimpsest sediments and fine-grained sediments. sorting and heavy mineral contents. The sands are probably relict sediments reworked during high-energy conditions such as typoon or storm. On the other hand, the muds were originated from various sources such as recent input from the Nakdong River, reworked fine-grained sediment from the shelf or suspended particulate matter from the East Sea Warm Current.

• Korean Journal of Applied Biomechanics
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• v.12 no.2
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• pp.295-306
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• 2002

The purpose of this study was analysis inter relative the ball velocity and isotonic torque of shoulder joint. The subject were twelve overthrow pitcher of professional baseball player. The measurement was used Cybex 6000. The results of this study were as follows : 1. As the siting position of maximal adduction torque of dominant, A group was higher than B group. As the non-dominant, B group was higher than A group for improved angular velocity. There is no significance difference between group. 2. As the siting position of maximal abduction torque of dominant and non-dominant, B group was higher than A group for all measurement. There is no significance difference between group. 3. As the layed position of maximal internal torque of dominant, A group was higher than B group. As the non-dominant was just higher at $180_{\circ}$/sec than B group, B group was higher at $60_{\circ}$/sec and $300_{\circ}$/sec than A group. There is no significance difference between group. 4. As the layed position of maximal external torque of dominant and non-dominant, A group was more higher than B group for all measurement. There is no significance difference between group. 5. As the standing position of maximal internal torque of dominant, A group was just higher at $60_{\circ}$/sec than B group, B group was higher at $180_{\circ}$/sec and $300_{\circ}$/sec than A group. As the non-dominant, B group was higher than A group. There is no significance difference between group. 6. As the standing position of maximal external torque of dominant, A group was higher $60_{\circ}$/sec and $180_{\circ}$/sec than B group. But B group was higher $300_{\circ}$/sec than A group. As the non-dominant, B group was higher than A group. There is no significance difference between group.

• Journal of the Korean Vacuum Society
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• v.18 no.3
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• pp.213-220
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• 2009

The optimal condition of low temperature deposition of transparent conductive Al-doped zinc oxide (AZO) films is studied by RF magnetron sputtering method. To achieve enhanced-electrical property and good crystallites quality, we tried to deposit on glass using a two-step growth process. This process was to deposit AZO buffer layer with optimal growth condition on glass in-situ state. The AZO film grown at rf 120 W on buffer layer prepared at RF $50{\sim}60\;W$ shows the electrical resistivity $3.9{\times}10^{-4}{\Omega}cm$, Carrier concentration $1.22{\times}10^{21}/cm^3$, and mobility $9.9\;cm^2/Vs$ in these results, The crystallinity of AZO film on buffer layer was similar to that of AZO film on glass with no buffer later but the electrical properties of the AZO film were 30% improved than that of the AZO film with no buffer layer. Therefore, the cause of enhanced electrical properties was explained to be dependent on degree of crystallization and on buffer layer's compressive stress by variation of $Ar^+$ ion impinging energy.

• Polymer(Korea)
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• v.29 no.2
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• pp.177-182
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• 2005

Montmorillonite (MMT) modified with siloxane diamine was reacted with a reactant obtained from 4,4'-diphenyl methane diisocyanate (MDI) and polyester type polyol, $Nippollan4010(\bar{M}_n2000)$. Finally, polyurethane (PU)/MMT composites were prepared by using 1,4-butane diol as a chain extender in $25\;wt\%$ solution of N,N-dimethyl acetamide (DMAc). It was expected that these nanocomposites had superior exfoliation property to that of MMT dispersed polyurethanes produced by simple mixing due to insertion of siloxane main chain to the silicate interlayer of MMT. Extent of reaction and formation of final products were analysed by using FT-IR spectroscopy. Dispersion into the PU and intercalation of MMT were identified by applying X-ray diffraction (XRD) and transmission electron microscopy (TEM). Tensile data were acquired by universal test machine (UTM). Thermal stability and variation of surface energy were characterized by thermal gravimetric analysis (TGA) method and measurement of contact angle on the synthesized composites, respectively. As the results the organo-MMT modified with siloxane diamine in the PU composites has an intercalated structure relatively well-expanded rather than a completely exfoliated structure. The tensile strengths and the moduli for the PU/organo-MMT composites were drastically enhanced in comparison to those of $PU/Na^+-MMT$ composites.

• Journal of Bio-Environment Control
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• v.11 no.3
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• pp.101-107
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• 2002

This study was carried out to improve the performance of heat recovery device attached to exhaust gas flue connected to combustion chamber of greenhouse heating system. Three different units were prepared far the comparison of heat recovery performance; A-type is exactly the same with the typical one fabricated for previous study of analyzing heat recovery performance in greenhouse heating system, other two types (B-type and C-type) modified from the control unit are different in the aspects of airflow direction (U-turn airflow) and pipe arrangement. The results are summarized as follows ; 1. In the case of Type-A, when considering the initial cost and current electricity fee required for system operation, it was expected that one or two years at most would be enough to return the whole cost invested. 2. Type-B and Type-C, basically different with Type-A in the aspect of airflow pattern, are not sensitive to the change of blower capacity with higher than 25m$^3$.min$^{-1}$ . Therefore, heat recovery performance was not improved so significantly with the increment of blower capacity. This was assumed to be that air flow resistance in high air capacity reduced the heat exchange rate as well. Never the less, compared with control unit, resultant heat recovery rate of Type-B and Type-C was improved by about 5％ and 13％, respectively 3. Desirable blower capacity of these heat recovery units experimented were expected to be about 25m$^3$.min$^{-1}$ , and at the proper blower capacity, U-turn airflow units showed better heat recovery performance than control unit. But, without regard to the type of heat recovery unit, it was recommended that comprehensive consideration of system's physical factors such as pipe arrangement density, unit pipe length and pipe thickness, etc., was required for the optimization of heat recovery system in the aspects of not only energy conservation but economic system design.