• Journal of Adhesion and Interface
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• v.19 no.3
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• pp.106-112
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• 2018

Recently, the hyperthermia treatment of malignant tissues has gained great attention as a biocompatible and benign method that facilitates successful cancer therapy compared to radiation and chemotherapy. In this study, superparamagnetic ($Fe_3O_4$) iron oxide nanoparticles (IONP) coated with biocompatible polymer (IONP@P(MPC/FOM)) for the purpose of hyperthermia treatment were prepared and related characterization were performed. IONPs with having 15 nm diameter were first prepared by coprecipitation and followed by surface modification with 4-cyanopentanoic acid dithiobenzoate (CTP) for reversible addition-fragmentation chain transfer (RAFT) copolymerization by using 2-methacryloyloxyethyl phosphorylcholine (MPC) and fluorescein O-methacrylate (FOM) to form corona layer of P(MPC/FOM) on the surface of the IONP. Transmission electron microscopy (TEM) and dynamic light scattering (DLS) confirmed the morphology and hydrodynamic size of the IONP@P(MPC/FOM) and thermogravimetric analysis (TGA) confirmed the formation of P(MPC/FOM) corona layer, respectively. Exposing IONP dispersion to alternating magnetic field suggests that the IONP@P(MPC/FOM) aqueous dispersion with 0.2 wt.% can be used for hyperthermia treatment.

• Journal of Astronomy and Space Sciences
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• v.19 no.4
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• pp.305-318
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• 2002

We have constructed two flight models of airglow photometer system (AGP) to be onboard Korea Sounding Rocket-III (KSR-III) for detection of MUV dayglow above the Korean peninsular. The AGP system is designed to detect dayglow emissions of OI 2972${\AA}$, $N_2$ VK(0,6) 2780${\AA}$, $N_2$ 2PG 3150${\AA}$ and background 3070${\AA}$ toward the horizon at altitudes between 100 km and 300 km. The AGP system consists of a photometer body, a baffle an electronic control unit and a battery unit. The MUV dayglow emissions enter through a narrow band interference filter and focusing lens of the photometer, which contains an ultraviolet sensitive photomultiplier tube. The photometer is equipped with an in-flight calibration light source on a circular plane that will rotate at the rocket's apogee. A bane tube is installed at the entry of the photometer in order to block strong scattering lights from the lower atmosphere. We have carried out laboratory measurements of sensitivity and in-flight calibration light source for the AGP flight models. Although absolute sensitivities of the AGP flight models could not be determined in the country, relative sensitivities among channels are well measured so that observation data during rocket flight in the future can be analyzed with confidence.

• Proceedings of the Korean Vacuum Society Conference
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• 2013.08a
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• pp.172-172
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• 2013

최근에 디스프로슘 이온이 도핑된 형광체의 백색 발광 현상 때문에 백색 발광 소재의 제조에 관한 연구가 상당한 관심을 끌고 있다. 본 연구에서는 $Eu^{3+}$와 $Dy^{3+}$ 이온의 몰 비를 변화시키면서 $BaNb_2O_6:RE^{3+}$ (RE=Eu, Dy) 형광체 분말을 합성한 결과를 보고한다. 특히 활성제 이온인 $Eu^{3+}$와 $Dy^{3+}$ 이온의 몰 비에 따른 $BaNb_2O_6$ 형광체 분말의 결정 구조, 입자의 모양과 크기, 흡광과 발광 스펙트럼의 변화를 관측하였고, 최적의 합성 조건을 제시하고자 한다. 파장 393 nm로 여기 시킨 $Dy^{3+}$ 이온의 몰 비에 따른 $BaNb_2O_6$ 형광체 분말의 발광 스펙트럼은 580 nm에 주 피크를 갖는 황색 스펙트럼이 관측되었다. 이 발광 신호는 $^4F_{9/2}-^6H_{13/2}$ 전이 신호이다. $Dy^{3+}$ 이온의 몰 비가 0 mol인 경우에는 발광 신호가 검출되지 않았다. $Dy^{3+}$ 이온의 몰 비가 0.10 mol일 때 발광 피크의 세기는 최대이었으며, $Dy^{3+}$ 이온의 몰 비가 더욱 증가함에 따라 발광 스펙트럼의 세기는 계속 증가하지 않고 갑자기 감소하기 시작하였다. 이것은 $Dy^{3+}$ 이온의 몰 비가 임계값을 초과하여 더욱 증가하면 모체 격자들 사이에 치환 고용되어 있는 $Dy^{3+}$ 이온들 사이의 거리가 더욱 가까워져서 $Dy^{3+}$ 이온들이 서로 용이하게 결합함으로써 내부 산란에 의하여 발광의 세기가 감소함을 의미한다. 흡광 스펙트럼의 경우에, $Dy^{3+}$ 이온의 몰 비가 0.01 mol일때 형광체 분말은 두 종류의 흡광 스펙트럼을 나타내었다. 첫째는 $Dy^{3+}$ 양이온과 $O^{2-}$ 음이온들 사이에 발생한 전하 전달 밴드에 의해 발생하는 310 nm를 정점으로 하여 280~340 nm 영역에 걸쳐서 광범위하게 분포하는 흡광 신호가 관측되었으며, 둘째는 $Dy^{3+}$ 이온의 $4f^9$ 전자 배열 내에서 발생하는 4f-4f 전이 신호로서, 이것은 350~500 nm 영역에 걸쳐서 비교적 밴드폭이 좁은 다수의 흡광 신호가 나타났다. 본 실험에서는 다섯 개의 피크를 갖는 흡광 신호가 검출되었는데, 이중에서 제일 강한 주 피크인 393 nm의 흡수 파장은 모체 격자 내에 있는 $Dy^{3+}$ 이온의 바닥 상태인 $^6H_{15/2}$ 준위에서 여기 상태인 $^4F_{7/2}$ 인 에너지 준위로 전이하면서 발생한 신호이며, 이에 비하여 상대적으로 흡광 세기가 약한 370, 432, 458, 370 nm의 흡수 파장이 관측되었다.

• Journal of the Mineralogical Society of Korea
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• v.20 no.4
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• pp.339-349
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• 2007

For various types of the Pungchon limestone, diverse mineral characters of the limestone including their size and morphology are investigated by using of ELS and SEM to examine the possibility of application as fillers to paper industry. Also, the measurement of zeta potential and the evaluation of coagulation properties in calcite suspension was made for fine powders of the limestone to examine the applicability and efficiency in wet-papermaking process. Fine powder of the Pungchon lime-stone, largely controlled by original mineral characters of ore in mineralogical aspects, exhibits some-what different trend in particle morphology according to ore types, and thereby, the size distribution, zeta potential and coagulation properties also become different. The examined whiteness, brightness, opacity and sheet strength in hand sheet also show remarkable differences according to ore types. These are seemed to be basically due to the results of combined effects of whiteness, site distribution, refractive index, and morphology of the limestone powder on the properties of hand sheet. Considering the investigated results, all types of the Pungchon limestone appear to be sufficiently applicable to paper industry. Especially, the mega-crystalline calcite type is evaluated to be overall suitable for the purpose of paper industry due to the higher values in whiteness and brightness. In addition the fine powder of micro-crystalline calcite type is assessed particularly to have a good quality in sheet strength by virtue of irregular particle shape.

• Korean Journal of Remote Sensing
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• v.37 no.2
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• pp.233-243
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• 2021

Photovoltaic panels are hazardous electronic waste that has heavy metal as one of the hazardous components. Each year, hazardous electronic waste is increasing worldwide and every heavy rainfall exposes the photovoltaic panel to become the source of heavy metal soil contamination. the development needs a monitoring technology for this hazardous exposure. this research use relationships between SAR temporal baseline and coherence of Sentinel-1 satellite to detected photovoltaic panel. Also, the photovoltaic plant detection tested using the difference between that photovoltaic panel and the other difference surface of coherence. The author tested the photovoltaic panel and its environment to calculate differences in coherence relationships. As a result of the experiment, the coherence of the photovoltaic panel, which is assumed to be a permanent scatterer, shows a bias that is biased toward a median value of 0.53 with a distribution of 0.50 to 0.65. Therefore, further research is needed to improve errors that may occur during processing. Additionally, the author found that the change detection using a temporal baseline is possible as the rate of reduction of coherence of photovoltaic panels differs from those of artificial objects such as buildings. This result could be an efficient way to continuously monitor regardless of weather conditions, which was a limitation of the existing optical satellite image-based photovoltaic panel detection research and to understand the spatial distribution in situations such as photovoltaic panel loss.

• Korean Journal of Mineralogy and Petrology
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• v.35 no.3
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• pp.259-271
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• 2022

Lattice preferred orientation (LPO), which shows a specific lattice-orientation of minerals, is affected by the deformation conditions of minerals. Because of this reason, LPO is very useful to study the deformation conditions of the minerals and the rocks. In this study, we collected amphibole-rich rocks from the Geumgye Mountain, Chugye-ri, Yugu-eup, Chungcheongnamdo, located in the southwestern part of the Gyeonggi Massif, and analyzed the LPO of amphibole and plagioclase using electron backscattered diffraction. Two types of LPOs of amphibole, type I and type IV, were observed in Yugu amphibole-rich rocks. Our data suggest that the amphibole-rich rocks in Yugu were deformed by rigid body rotation regardless of the LPOs and grain size of amphibole, and the LPOs are considered to have been affected by the degree of deformation (i.e. strain). In the low strained amphibole-rich rock, a strong type I LPO and a large grain size of amphibole were observed. On the other hand, in the highly strained amphibole-rich rocks, a weak type IV LPO and a small grain size of amphibole were observed. The various degree of deformation observed in the Yugu amphibole-rich rocks were also observed in the adjacent peridotites, indicating that the rocks in Yugu experienced various levels of deformation.

• Journal of Korean Society of Forest Science
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• v.48 no.1
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• pp.29-39
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• 1980

This study was initiated to find out the possible insect vector and other means of transmission of jujube witches'-broom disease. 1. Eight species of leafhoppers were found to feed on both healthy and diseased jujube trees. Among these, rhombic marked leafhoppers (Hishimonus sellatus Uhler) were most abundant throughout the growing season of jujube trees in all localities surveyed. H. sellatus was far more abundant on diseased trees than healthy ones. 2. Jujube witches'-broom mycoplasma(JWM) was transmitted to jujube seedlings by Hishimonus sellatus. Jujube seedlings inoculated with H. sellatus which had been fed for 14-21 days on diseased jujube plants, developed smaller, chlorotic leaves 40-60 days after inoculation. Electron microscopy of midveins and petioles of the infected jujube seedlings revealed the presence of numerous mycoplasmalike organisms in phloem tissues. 3. Jujube witches'-broom mycoplasma was also transmitted to Vinca rosea plants by H. sellatus. Infected Vinca rosea plants developed vein clearing and marginal chlorosis of upper leaves 25-38 days after inoculation and followed by stunting and ultimate wilting and death of plant. Electron microscopy of petioles and midveins of infected Vinca rosea plant revealed the presence of numerous mycoplasmalike organisms in phloem tissues. 4. H. sellatus survived more than 30 days on jujube, Vinca rosea, carrot, celery, eggplant, hop, Calystegia japonica, Humulus japonicus, Astragalus sinicus, white clover, red clover, and radino clover. Many second generation nymphs of H. sellatus were also abserved on these plants but clovers. 5. Jujube seeds collected from witches'-broom diseased jujube trees yielded healthy seedlings.

• Journal of the Korea Concrete Institute
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• v.19 no.1
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• pp.121-130
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• 2007

To investigate the enhancement in strength and deformation capacities of concrete confined by FRP composites, tests under axial loads were carried out on three groups of thirty six short columns in circular section with diverse GFRP confining reinforcement. The major test variables considered include fiber content or orientation, wrap or tube type by varying the end loading condition, and continuous or discontinuous confinement depending on the presence of vortical spices between its two halves. The circumferential FRP strains at failure for different types of confinements were also investigated with emphasis. Various analytical models capable of predicting the ultimate strength and strain of the confined concrete were examined by comparing to observed results. Tests results showed that FRP wraps or tubes provide the substantial increase in strength and deformation, while partial wraps comprising the vertical discontinuities fail in an explosive manner with less increase in strength, particularly in deformation. A bilinear stress-strain response was observed throughout all tests with some variations of strain hardening. The failure hoop strains measured on the FRP surface were less than those obtained from the tensile coupons in all tests with a high degree of variation. In overall, existing predictive equations overestimated ultimate strengths and strains observed in present tests, with a much larger scatter related to the latter. For more accuracy, two simple design- oriented equations correlated with present tests are proposed. The strength equation was derived using the Mohr-Coulomb failure criterion, whereas the strain equation was based on entirely fitting of test data including the unconfined concrete strength as one of governing factors.

• Progress in Medical Physics
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• v.26 no.4
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• pp.208-214
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• 2015

The aim of this study is to investigate the effect of low magnetic field on dose distribution in the partial-breast irradiation (PBI). Eleven patients with an invasive early-stage breast carcinoma were treated prospectively with PBI using 38.5 Gy delivered in 10 fractions using the $ViewRay^{(R)}$ system. For each of the treatment plans, dose distribution was calculated with magnetic field and without magnetic field, and the difference between dose and volume for each organ were evaluated. For planning target volume (PTV), the analysis included the point minimum ($D_{min}$), maximum, mean dose ($D_{mean}$) and volume receiving at least 90% ($V_{90%}$), 95% ($V_{95%}$) and 107% ($V_{107%}$) of the prescribed dose, respectively. For organs at risk (OARs), the ipsilateral lung was analyzed with $D_{mean}$ and the volume receiving 20 Gy ($V_{20\;Gy}$), and the contralateral lung was analyzed with only $D_{mean}$. The heart was analyzed with $D_{mean}$, $D_{max}$, and $V_{20\;Gy}$, and both inner and outer shells were analyzed with the point $D_{min}$, $D_{max}$ and $D_{mean}$, respectively. For PTV, the effect of low magnetic field on dose distribution showed a difference of up to 2% for volume change and 4 Gy for dose. In OARs analysis, the significant effect of the magnetic field was not observed. Despite small deviation values, the average difference of mean dose values showed significant difference (p<0.001), but there was no difference of point minimum dose values in both sehll structures. The largest deviation for the average difference of $D_{max}$ in the outer shell structure was $5.0{\pm}10.5Gy$ (p=0.148). The effect of low magnetic field of 0.35 T on dose deposition by a Co-60 beam was not significantly observed within the body for PBI IMRT plans. The dose deposition was only appreciable outside the body, where a dose build-up due to contaminated electrons generated in the treatment head and scattered electrons formed near the body surface.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.39 no.4
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• pp.41-54
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• 2002

In this study, we have analyzed the effects of the membrane layer and the bragg reflector layers on the resonance characteristics through comparing the characteristics of the membrane type FBAR (Film Bulk Acoustic Wave Resonator) and the one type bragg reflector layers with those of the ideal FBAR with top and bottom electrode contacting air by using equivalent circuit technique. It is assumed that ZnO is used for piezoelectric film, $SiO_2$ are used for membrane layer and low acoustic impedance layer, W are used for the high acoustic reflector layer and Al is used for the electrode. Each layer is considered to have a acoustic propagation loss. ABCD parameters are picked out and input impedance is calculated by converting 1-port equivalent circuit to simplified equivalent circuit that ABCD parameters are picked out possible. From the variation of resonance frequency due to the change of thickness of electrode layers, reflector layers and membrane layer it is confirmed that membrane layer and the reflector layer just under the electrode have the greatest effect on the variation of resonance frequency. From the variation of resonance properties, K and electrical Q with the number of layers, K is not much affected by the number of layers but electrical Q increases with the number of layers when the number of layers is less than seven. The electrical Q is saturated when the number of layers is large than six. The electrical Q is dependent of mechanical Q of reflector layers and membrane layer. Both ladder filter and SCF (Stacked Crystal Filters) show higher insertion loss and out-of-band rejection with the increase of the number of resonators. The insertion loss decreases with the increase of the number of reflector layers but the bandwidth is not much affected by the number of reflector layers. Ladder Filter and SCF with membrane layer show the spurious response due to spurious resonance properties. Ladder filter shows better skirt-selectivity characteristics in bandwidth but SCF shows better characteristics in insertion loss.