• Journal of the Korean Society of Radiology
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• v.15 no.7
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• pp.965-973
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• 2021

Since radiation therapy is irradiated with high-energy X-rays in a variety of at least 20 Gy to 80 Gy, a high dose is administered to the local area where the tumor is located, and various side effects of some normal tissues are expected. Currently, in clinical practice, lead, a representative material, is used as an effort to shield normal tissues, but lead is classified as a heavy metal harmful to the human body, and a large amount of skin contact can cause poisoning. Therefore, this study intends to manufacture a measurement sheet that can compensate for the limitations of lead using the materials Tungsten, Brass, and Copper of the 3D printer of the FDM (Fused Deposition Modeling) method and to investigate the penetration performance. Tungsten mixed filament transmission measurement sheet size was 70 × 70 mm and thickness 1, 2, 4 mm using a 3D printer, and a linear accelerator (TrueBeam STx, S/N: 1187) was measured by irradiating 100 MU at SSD 100 cm and 5 cm in water using a water phantom, an ion chamber (FC-65G), and an elcetrometer (PTW UNIDOSE), and the permeability was evaluated. As a result of increasing the measurement sheet of each material by 1 mm, in the case of Tungsten sheet at 3.8 to 3.9 cm in 6 MV, the thickness of the lead shielding body was thinner than 6.5 cm, and in case of Tungsten sheet at 4.5 to 4.6 cm in 15 MV. The sheet was thinner than the existing lead shielding body thickness of 7 cm, and equivalent performance was confirmed. Through this study, the transmittance measurement sheet produced using Tungsten alloy filaments confirmed the possibility of transmission shielding in the high energy region. It has been confirmed that the usability as a substitute is also excellent. It is thought that it can be provided as basic data for the production of shielding agents with 3D printing technology in the future.

• Journal of the Mineralogical Society of Korea
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• v.31 no.4
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• pp.235-248
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• 2018

The present work was performed in order to study the effect of competing cation of $Ca^{2+}$ ion on ion exchange of $Cs^+$ on zeolite Y (Si/Al = 1.56). Three single-crystals of fully dehydrated and partially $Cs^+$-exchanged zeolites Y (Si/Al = 1.56) were prepared by the flow method using mixed ion-exchange solutions. The $CsNO_3:Ca(NO_3)_2$ molar ratios of the ion exchange solution were 1 : 1 (crystal 1), 1 : 100 (crystal 2), and 1 : 250 (crystal 3) with a total concentration of 0.05 M. The single-crystals were then vacuum dehydrated at 723 K and $1{\times}10^{-4}Pa$ for 2 days. The structures of the crystals were determined by single-crystal synchrotron X-ray diffraction technique in the cubic space group $Fd{\bar{3}}m$, at 100(1) K. The unit-cell formulas of crystals 1, 2, and 3 were ${\mid}Cs_{21}Ca_{27}{\mid}[Si_{117}Al_{75}O_{384}]-FAU$, ${\mid}Cs_2Ca_{36.5}{\mid}[Si_{117}Al_{75}O_{384}]-FAU$, and ${\mid}Cs_1Ca_{37}{\mid}[Si_{117}Al_{75}O_{384}]-FAU$, respectively. In all three crystals, the $Ca^{2+}$ ions preferred to occupy site I in the D6Rs, with the remainder occupying sites I', II', and II. On the other hand, the significant differences in the fractional distribution of $Cs^+$ ions are observed depending on the intial $Cs^+$ concentrations in given ion exchange solution. In Crystal 1, $Cs^+$ ion are located at sites II', II, III, and III', and in crystal 2, at sites II, IIIa, and IIIb. In crystal 3, $Cs^+$ ions are only located at sites IIIa and IIIb. The degree of $Cs^+$ ion exchange decreased sharply from 28.0 to 2.7 to 1.3 % as the initial $Ca^{2+}$ concentration increases and the $Cs^+$ content decreases.

• Korean Journal of Heritage: History & Science
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• v.42 no.2
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• pp.86-109
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• 2009

Mireuksa Temple was founded during the reign of King Mu of Baekje(AD 600-641). The circumstance of the construction of this temple is documented in "Memorabilia of the Three Kingdoms (Samgukyusa)". The pagoda named stone pagoda at Mireuksaji temple stands outside the main sanctuary of the western area. The south and west sides of the stone pagoda have completely collapsed, leaving only the eastern facade of six of its levels intact. Through the recent discovery of sarira reliquary we can see that the erection of this pagoda was in 639. So owing to accumulation of excavation results about Baekje temple site and vigorous academic exchange, it is possible that architecture of western pagoda at Mireuksaji temple can be understood in connection with the architectural development of wooden pagoda from 6th to early 7th century in East Asia. So this study is on the consideration of building of this pagoda putting first structure of upper part and cross-shaped space in 1st floor. It was considered that the material characteristics as stone could be applied to the temple pagoda architecture of large scale. The results are as follows. First, it had been built in recognition that the outer and inner part of pagoda should be separated. As it is the expression of structural system in temple pagoda architecture of large scale at that time. In pagoda there was a self-erected structure and the members of outer part of it were constructed additionally. Second, in Mireuksaji stone pagoda there is central column with stones. With inner part of pagoda it can be regarded as mixed structural system that constitutes central contral column and inner structural part. And it could be a kind of middle step to more developed structure of whole as wooden pagodas in Japan. Third, as the sarira reliquary was in central column on the first floor, the cross-shaped space could be made. The formation of this space was so on the natural meaning of sarira that the concept as memorial service of graves could be apllied to the pagoda. The style of tomb in Baekje was expressed to the space of 1st floor in pagoda where Sarira had been mstalled. That was not only effective presentation of symbolic space but also easier method in the use of same material.

• Korean Journal of Heritage: History & Science
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• v.46 no.4
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• pp.108-125
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• 2013

This study examined the actual reconstruction drawing, composite mineral, particle size and property test, fine organic matters, color differences and main ingredients of the earthen mold excavated in Dongcheon-dong, Gyungju. The cross-section of the inner mold and outer mold divides into inside (1st layer) and outside (2nd layer), with organic matters mixed outside. The cross-section has been altered due to heat and form removal agent. X-ray analysis revealed that the layer was made of minerals with high transmissivity and only quartz particles were observed through a polarizing microscope. The inside of cross-section in SEM observation identified enlarged air gap, with crack developed in the center, but no changes observed on the outside. The particle size of the composites is almost the same for the inner mold and outer mold and is silt clay loam. The ratio between silt clay and silt clay loam was about 2.7:1 and 2.9:1 respectively. In the property test, the density and absorption rate of inner mold and outer mold were similar, but porosity was different, with inner mold of 27.36% and outer mold of 31.09%. The color difference of cross-section seems to have been caused by the spread of soot on the 1st layer surface for removal of form or by the covering of ink to protect the 1st layer. Composite mineral analysis revealed the same composition for the inner mold and outer mold, except for the magnetite that was detected in the inner mold alone. As for the main ingredient analysis, the average content of $SiO_2$ was 71.64% and that of $Al_2O_3$ was 14.59%. As for the sub-ingredients, $Fe_2O_3$ was 4.51%, $K_2O$ 3.06%, $Na_2O$, MgO, CaO, $TiO_2$, $P_2O_5$ and MnO was less than 2%.

• Korean Journal of Heritage: History & Science
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• v.39
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• pp.243-280
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• 2006

At the Bujang-ri Site, Seosan, South Chungcheong Province, around 220 archaeological features, including semi-subterranean houses and pits of Bronze Age and semi-subterranean houses, pits, and burials of Baekje period had been identified and investigated. In Particular, mound burials No. 5 of 13 of Baekje mound burials yielding a gilt-bronze cap along with other valuable artifacts drew international scholarly attention. The gilt-bronze cap from the mound burial No. 5 is a significant archaeological data not only in the study of Baekje archaeology but also in the study of international affairs and exchange at that time. At the time of exposure, the gilt-bronze cap was already broken into a number of pieces and seriously damaged by corrosion, and hardening and urethane foam were necessary in the process of collecting its pieces. Ahead of main conservational treatments on cap, X-ray photograph and CT(computerizes tomography) were taken in order to examine interior structure of the cap and to decide appropriate treatments. In the five layers identified in the profile of cap, a textile layer was set between a metal and a layerof bark of paper birch for avoiding direct contact of the metal and the bark of paper birch. Analyses were executed for examining textile layer and a layer of fibroid material. According to microscopic analysis, while the textile layer consisted of the simplest plain fabric with one fold among three kinds of textile structures, the layer of fibroid material was mixed with two or three kinds of fibers. A comparative analysis with standard sample using FT-IR (Fourier Transform Infrared Spectroscopy) announced that both textiles and fabrics were hemp. Analysis of kind of the paper birch resulted in barks of paper birch with 15 fold. A metallographic microscope, SEM, and WDS were used for the analysis of microscopic structures of plated metal pieces. While amalgam plating was treated as a plating method, the thickness of the plated layer, a barometer of plating technique, was ranged from $1.72{\mu}m$ to $8.67{\mu}m$. The degree of purity of gold (Au) used in plating was 98% in average, and less than 1% of silver (Ag) was included.

• Korean Journal of Remote Sensing
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• v.35 no.3
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• pp.347-358
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• 2019

Lambertian cloud model (Lambertian Cloud Model) is the simplified cloud model which is used to effectively retrieve the vertical ozone distribution of the atmosphere where the clouds exist. By using the Lambertian cloud model, the optical characteristics of clouds required for radiative transfer simulation are parametrized by Optical Centroid Cloud Pressure (OCCP) and Effective Cloud Fraction (ECF), and the accuracy of each parameter greatly affects the radiation simulation accuracy. However, it is very difficult to generalize the vertical ozone error due to the OCCP error because it varies depending on the radiation environment and algorithm setting. In addition, it is also difficult to analyze the effect of OCCP error because it is mixed with other errors that occur in the vertical ozone calculation process. This study analyzed the ozone retrieval error due to OCCP error using two methods. First, we simulated the impact of OCCP error on ozone retrieval based on Optimal Estimation. Using LIDORT radiation model, the radiation error due to the OCCP error is calculated. In order to convert the radiation error to the ozone calculation error, the radiation error is assigned to the conversion equation of the optimal estimation method. The results show that when the OCCP error occurs by 100 hPa, the total ozone is overestimated by 2.7%. Second, a case analysis is carried out to find the ozone retrieval error due to OCCP error. For the case analysis, the ozone retrieval error is simulated assuming OCCP error and compared with the ozone error in the case of PROFOZ 2005-2006, an OMI ozone profile product. In order to define the ozone error in the case, we assumed an ideal assumption. Considering albedo, and the horizontal change of ozone for satisfying the assumption, the 49 cases are selected. As a result, 27 out of 49 cases(about 55%)showed a correlation of 0.5 or more. This result show that the error of OCCP has a significant influence on the accuracy of ozone profile calculation.

• Journal of The Korean Association For Science Education
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• v.39 no.2
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• pp.187-195
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• 2019

The purpose of this study is to diagnose the operation status of high school integrated science newly introduced in the 2015 revised national curriculum and first applied in 2018, to examine teachers' perception on the new educational policy, and then based on this, extract implications for settling down the policy. A survey was administered to science teachers who participated in the in-service teacher training on integrated science, and the responses of 384 high school science teachers were analyzed. According to the results of the survey, integrated science was allotted six units to each school, and two or more teachers divided achievement standards and were responsible for them in many cases. Science teachers pointed to the increase of student-oriented activities as the biggest change due to the application of integrated science and also showed a positive attitude towards increasing the proportion of performance-based assessment, diversifying evaluation methods, increasing teacher consultations, and enhancing the holistic understanding of natural phenomenon, etc. In particular, teachers with 15 years or more of teaching experience were significantly positive about the increase of student-oriented activities, diverse assessment methods, and opportunities of teacher consultations. For teachers with a sub-major in science, teaching about non-majored contents was the most difficult and it was also difficult to determine the appropriate level of contents to teach. Teachers who majored common science, however, rarely complained about teaching non-majored content. In the case of two teachers in charge of integrated science, there was a statistically significant demand for subject matter knowledge as training content, and for mixed education incorporating theory and practice and customized training as a training method. In the case of one teacher responsible for the subject, there was a relatively lower demand. From these results, some implications for the successful implementation of integrated science were discussed.

• Journal of the Korea Institute of Building Construction
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• v.20 no.6
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• pp.489-495
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• 2020

Whereas the control of the hydration heat in mass concrete has been important as the concrete structures enlarge, many conventional strategies show some limitations in their effectiveness and practicality. Therefore, In this study, as a solution of controling the heat of hydration of mass concrete, a method to reduce the heat of hydration by controlling the hardening of cement was examined. The reduction of the hydration heat by the developed Phosphate Inorganic Salt was basically verified in the insulated boxes filled with binder paste or concrete mixture. That is, the effects of the Phosphate Inorganic Salt on the hydration heat, flow or slump, and compressive strength were analyzed in binary and ternary blended cement which is generally used for low heat. As a result, the internal maximum temperature rise induced by the hydration heat was decreased by 9.5~10.6% and 10.1~11.7% for binder paste and concrete mixed with the Phosphate Inorganic Salt, respectively. Besides, the delay of the time corresponding to the peak temperature was apparently observed, which is beneficial to the emission of the internal hydration heat in real structures. The Phosphate Inorganic Salt that was developed and verified by a series of the aforementioned experiments showed better performance than the existing ones in terms of the control of the hydration heat and other performance. It can be used for the purpose of hydration heat of mass concrete in the future.

• Journal of the Korean GEO-environmental Society
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• v.22 no.6
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• pp.17-26
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• 2021

Ground investigation and result analysis generally used to examine all sorts of structures' subsidence or stability can be classified into sandy soil and cohesive soil, and analysis on the liquid limit of soil is utilized to evaluate the physical properties of ground and types or technical behavior of soil. The most widely used method to analyze liquid limit is Casagrande with which liquid limit can be calculated relatively easily; however, it is fairly difficult to apply it to soil equipped with intermediate properties. Therefore, concerning the properties of soil having the intermediate properties of sedimentary ground, this researcher mixed the clay from Yangsan, Gwangyang, and Busan with sandy soil to make intermediate soil and then carried out the test of consistency limit and also evaluated applicability by using the suggested formula of consistency revision. The sample of intermediate soil was the mixture of clay and sandy soil, and to produce intermediate soil, the content (F_c) of fine soil was applied as 50%, 75%, or 100%. Regarding the physical properties of intermediate soil, to maintain the properties of clay in the natural state, bentonite was added at a fixed rate for controlling the properties of clay, and then, consistency was analyzed. By adopting the formula of consistency revision suggested in advanced research, this author analyzed consistency based on the experiment and consistency based on the suggested formula of revision. Also, about intermediate soil collected at the site, consistency based on the experiment and consistency based on the suggested formula of revision were analyzed comparatively, and about intermediate soil collected, this researcher analyzed particle size and calculated the content (F_c) of fine soil to analyze intermediate soil in diverse conditions. Moreover, about intermediate soil collected at the site, the suggested formula of consistency revision was applied to calculate the compression index, and the compression index based on the experiment and the compression index based on the suggested formula were analyzed comparatively to evaluate the applicability of the suggested formula.

• Journal of The Korean Society of Grassland and Forage Science
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• v.40 no.4
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• pp.203-208
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• 2020

This experiment was conducted to investigate the effects of feeding TMR(Total Mixed Ration) with Sasa quelpaertensis Nakai of Jeju cross-bred horses on the body weight and blood composition. Fourteen herds of Jeju cross-bred horses older than 36 months were selected as experimental animals. The experiment was conducted by dividing the herds into seven herds for feeding TMR with 20% Sasa quelpaertensis Nakai(treatment) and another seven herds for feeding TMR without Sasa quelpaertensis Nakai(control) and water were fed ad libitum. In the 12th week, the MPV(mean platelet volume) was statistically significantly higher with Sasa TMR than with control (p<0.05). However, both MPV levels are within a normal range and there were no health problems. With regard to the levels of cholesterol, there was a statistically significant difference between the 33.8±5.9 mg/㎗ with individual management and 25.4±8.2 mg/㎗ with control group (p<0.05). But It are also within a normal range and there were no health problems. In conclusion, feeding TMR with 20% Sasa quelpaertensis Nakai of Jeju cross-bred horses could be utilized as a feeding method for horse.