• Journal of the Korea Academia-Industrial cooperation Society
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• v.21 no.10
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• pp.64-71
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• 2020

This study evaluated the effects of the culture media and light sources on the growth of microalgae Haematococuus pluvialis. Limited ingredient medium, Modified Bold's Basic Medium (MBBM), commercial liquid fertilizer medium Neo, and seven different light sources with different wavelengths were used to incubate H. pluvialis for 39 days, and the growth rates were compared. As a result, the growth of H. pluvialis, a limited ingredient medium, produced the highest cell growth in the fluorescent light source while cell growth was the lowest in the blue+red LED. The growth of H. pluvialis in commercial medium Neo was highest in the fluorescent light source, and cell growth was lowest in the blue LED. In this study, the MBBM culture medium showed better results than the Neo culture medium. Microalgae grown in the fluorescent light source using the MBBM culture medium showed the best cell growth result in this study. The results were optimized for the culture medium, light source, and light quantity in H. pluvialis culture for the production of secondary metabolites and provide basic data for the mass culture of microalgae.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.15 no.4
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• pp.2476-2483
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• 2014

This study aims to review the characteristics of specialized classrooms for governmental secondary schools in the Japanese Colonial Era by analyzing architectural drawings collected by National Archives of Korea. The results of this study are summarized as follows 1) Under the influence of Japanese science promotion of that time, specialized classrooms for science were considered as one of essential facilities. Typically exclusive specialized classrooms were assigned to two major science subjects : physics-chemistry and biology. 2) To science specialized classrooms, ancillary rooms for preparation, experiment equipment and specimen were attached and science lecture room with stepped floor was planned additionally only for the lecture on theories and the demonstration of experiment. 3) Specialized classrooms for science were zoned independently of other facilities because of the special equipments and safety. 4) Art rooms were common to both boys' and girls' schools but concerning music rooms, girls' schools had special concerns, whereas boys' schools did not. 5) Specialized classrooms for homemaking subject of girls' school were as much important as those for science subjects of boys' school. 6) Some early-established Korean boys' schools had handicraft rooms which were the symbol of vocational education-oriented, unequal policy on Koreans. Though not general cases, specialized classrooms for geography-history were planned for Japanese boys' school. Restricted to governmental secondary schools but considering the uncommon state of specialized classrooms of that time, these characteristics show conditions of early time when special classrooms were introduced into Korea.

• Journal of The Korean Association For Science Education
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• v.27 no.7
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• pp.547-558
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• 2007

The purpose of this study is to compare inquiry activities in science textbooks' physics contents for Korean secondary schools with those of Singapore in order to provide a reference for further improvement of inquiry activities in Korean science textbooks. We analyzed inquiry activities using the framework of Millar et al.(1998) and Chinn & Malhotra (2002). The results of this study are as follows: There are differences between Korean and Singaporean inquiry activities in the area of 'learning objectives', 'students' thinking activities' and 'degree of openness'. In the area of 'learning objectives', the Korean textbooks have more activities associated with the learning of science content than those in Singaporean, whereas the Singaporean textbooks have more activities associated with the processes of scientific inquiry than in Korean textbooks. In the area of 'students' thinking activities', the Singaporean textbooks have activities like 'test a prediction', which Korean textbooks lack. The 'degree of openness' is higher in Singaporean textbooks than in Korean textbooks. And some differences in the area of 'authentic scientific inquiry' between Korean and Singaporean textbooks were also found. While the Korean textbooks do not have any activities associated with 'generating research questions', the Singaporean ones feature such activities. In the area of 'designing studies', the Singaporean textbooks have activities corresponding to 'selecting variables' and 'controlling variables', while the Korean ones never have such activities. The results of this study imply that it is necessary to balance inquiry activities in the area of 'learning objectives', 'students' thinking activities' and 'degree of openness', and to present activities close to authentic scientific inquiry in inquiry activities in textbooks.

• Proceedings of the Korean Vacuum Society Conference
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• 2015.08a
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• pp.119-119
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• 2015

Ion beam sputtering has been widely used in Secondary Ion Mass Spectrometry (SIMS), X-ray Photoelectron Spectroscopy (XPS), and Auger Electron Spectroscopy (AES) for depth profile or surface cleaning. However, mainly due to severe matrix effects such as surface composition change from its original composition and damage of the surface generated by ion beam bombardment, conventional sputtering skills using mono-atomic primary ions with energy ranging from a few hundred to a thousand volts are not sufficient for the practical surface analysis of next-generation organic/inorganic device materials characterization. Therefore, minimization of the surface matrix effects caused by the ion beam sputtering is one of the key factors in surface analysis. In this work, the electronic structure of a $Ta_2O_5$ thin film on $SiO_2/Si$ (100) after Ar Gas Cluster Ion Beam (GCIB) sputtering was investigated using X-ray photoemission spectroscopy and compared with those obtained via mono-atomic Ar ion beam sputtering. The Ar ion sputtering had a great deal of influence on the electronic structure of the oxide thin film. Ar GCIB sputtering without sample rotation also affected the electronic structure of the oxide thin film. However, Ar GCIB sputtering during sample rotation did not exhibit any significant transition of the electronic structure of the $Ta_2O_5$ thin films. Our results showed that Ar GCIB can be useful for potential applications of oxide materials with sample rotation.

• Journal of the Korean Chemical Society
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• v.46 no.1
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• pp.46-51
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• 2002

The recognition and cleavage of 5S rRNA from P. alcaligenes by metallopeptides to the form $Ni(II){\cdot}Gly$-Gly-His(Arg)COOH and $Cu(II){\cdot}Gly$-Gly-His(Arg)COOH were investigated. The results of RNA cleavage analyses suggest that metallopeptides selectively target the unpaired or unstably paired bases of stem-loop structure of 5S rRNA. The selectivity of metallopeptides was little affected by the species of metal ion, Ni(II) or Cu(II). When the result of cleavage by metallopeptides was compared with that of by metal complexes M(II)CR, the recognition by metallopeptides was more selective and structure specific. The cleavage data by metallopeptides and other metal complexes were used to probe the secondary structure of 5S rRNA from P. alcaligenes.

• Proceedings of the Korean Society of Medical Physics Conference
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• 2002.09a
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• pp.241-243
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• 2002

New types of protocols have been recently in development, all based on an absorbed dose-to-water with the aim of improving the accuracy of measurements of absorbed dose to water. IAEA TRS-277, the air-kerma standard-based present protocol, and IAEA TRS-398 and AAPM TG-51, the absorbed dose-to-water standard-based new one, were studied and compared theoretically and experimentally for photon beams of 6, 10, and 15 MV. NE 2571 and 3 Farmer types of ionization chambers in widely commercial use were used to determine an absorbed dose to water at the reference depth in water. Two different kinds of calibration factors were given respectively for every chamber calibrated in $\^$60/CO gamma ray beams from a Korean Secondary Standard Dosimetry Laboratory (KFDA). This work shows that there is around 1 % of difference of absorbed doses measured between two different types of calibration systems owing to different physical parameters and reference conditions used. We hope this work to help form the basis on development of new type of protocol in Korea.

• Progress in Medical Physics
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• v.16 no.2
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• pp.97-103
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• 2005

The energy spectra and dose calculations were performed for secondary neutrons from a 24 MV LINAC using MCNPX code (V2, 4, 0). The energy spectra for neutrons and photons emitted from the LINAC head, and absorbed dose to water were calculated in water phantom. The absorbed doses calculated with Monte Carlo were $0.66\~0.35$ mGy/photon Gy at the surface to d=5 cm, and calculated with interaction data was 0.52 mGy/photon Gy at the depth of electron equilibrium in water. We have shown that this work can be applied to dose estimation of neutrons from high energy LINAC through the comparison of our results with other results.

• Publications of The Korean Astronomical Society
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• v.30 no.2
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• pp.397-399
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• 2015

Recently, cosmic voids have been recognized as a powerful cosmological probe. A number of studies have focused on the effects of the gravitational lensing by voids on the temperature (and in some cases polarization) anisotropy of the Cosmic Microwave Background (CMB) background at relatively large to medium scales, l ~ 1000. Many of these studies attempt to explain the unusually large cold spot in CMB temperature maps and dynamical evidence of dark energy via detections of late-time integrated Sachs Wolfe (ISW) effect. Here, the effects of lensing by voids on the CMB temperature anisotropy at small scales, up to l = 3000, will be investigated. This work is carried out in the light of the benefits of adding large catalogues of cosmic voids, to be identified by future large galaxy surveys such as EUCLID and LSST, to the analysis of CMB data such as those from Planck mission. Our numerical simulation utilizes two methods, namely, the small-de ectionangle approximation and full ray-tracing analysis. Using the fitted void density profiles and radius (RV ) distribution available in the literature from N-body simulations, we simulated the secondary temperature anisotropy (lensing) of CMB photons induced by voids along a line of sight from redshift 0 to 2. Each line of sight contains approximately 1000 voids of effective radius $RV_{,eff}=35h^{-1}Mpc$ with randomly distributed radial and projected positions. Both methods are used to generate temperature maps. The two methods will be compared for their accuracy and effciency in the implementation of theoretical modeling.

• Nuclear Engineering and Technology
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• v.53 no.9
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• pp.3018-3025
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• 2021

The authors developed a volumetric dosimetry detector system using in-house 3D-printable plastic scintillator resins. Three tumor model scintillators (TMSs) were developed using magnetic resonance images of a tumor. The detector system consisted of a TMS, an optical fiber, a photomultiplier tube, and an electrometer. The background signal, including the Cherenkov lights generated in the optical fiber, was subtracted from the output signal. The system showed 2.1% instability when the TMS was reassembled. The system efficiencies in collecting lights for a given absorbed energy were determined by calibration at a secondary standard dosimetry laboratory (k_SSDL) or by calibration using Monte Carlo simulations (k_sim). The TMSs were irradiated in a Gamma Knife® Icon^TM (Elekta AB, Stockholm, Sweden) following a treatment plan. The energies absorbed to the TMSs were measured and compared with a calculated value. While the measured energy determined with k_SSDL was (5.84 ± 3.56) % lower than the calculated value, the energy with k_sim was (2.00 ± 0.76) % higher. Although the TMS detector system worked reasonably well in measuring the absorbed energy to a tumor, further improvements in the calibration procedure and system stability are needed for the system to be accepted as a quality assurance tool.

• Progress in Medical Physics
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• v.33 no.4
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• pp.114-120
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• 2022

Purpose: Particle beam therapy is advantageous over photon therapy. However, adequately delivering therapeutic doses to tumors near critical organs is difficult. Nanoparticle-aided radiation therapy can be used to alleviate this problem, wherein nanoparticles can passively accumulate at higher concentrations in the tumor tissue compared to the surrounding normal tissue. In this study, we investigate the dose enhancement effect due to gold nanoparticle (GNP) when Carbon-12, He-4, and proton beams are irradiated on GNP. Methods: First, monoenergetic Carbon-12 and He-4 ion beams of energy of 283.33 MeV/u and 150 MeV/u, respectively, and a proton beam of energy of 150 MeV were irradiated on a water phantom of dimensions 30 cm×30 cm×30 cm. Subsequently, the secondary-particle information generated near the Bragg peak was recorded in a phase-space (phsp) file. Second, the obtained phsp file was scaled down to a nanometer scale to irradiate GNP of diameter 50 nm located at the center of a 4 ㎛×4 ㎛×4 ㎛ water phantom. The dose enhancement ratio (DER) was calculated in intervals of 1 nm from the GNP surface. Results: The DER of GNP computed at 1 nm from the GNP surface was 4.70, 4.86, and 4.89 for Carbon-12, He-4, and proton beams, respectively; the DER decreased rapidly with increasing distance from the GNP surface. Conclusions: The results indicated that GNP can be used as radiosensitizers in particle beam therapy. Furthermore, the dose enhancement effect of the GNP absorbed by tumor cells can aid in delivering higher therapeutic doses.