• Journal of Radiation Protection and Research
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• 제34권3호
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• pp.102-106
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• 2009

We exposed ICR mice to low-dose (0.2 Gy) and low-dose-rate (0.7 mGy/h) $\gamma$-radiation ($^{137}Cs$) in the Low-dose-rate Irradiation Facility at the Radiation Health Research Institute to evaluate systemic effects of low-dose radiation. We compared the body and organ weights, number of blood cells (white and red blood cells and platelets), levels of biochemical markers in serum, and frequency of micronuclei in polychromatic erythrocytes between low-dose irradiated and non-irradiated control mice. The ICR mice irradiated with total doses of 0.2 and 2 Gy showed no changes in body and organ weights, number of blood cells (white and red blood cells), or frequency of micronuclei in the polychromatic erythrocytes of peripheral blood. However, the number of platelets (P = 0.002) and the liver weight (P < 0.01) were significantly increased in mice exposed to 0.2 and 2 Gy, respectively. These results suggest that a low-dose-rate of 0.7 mGy/h does not induce systemic damage. This dose promotes hematopoiesis in the bone marrow microenvironment and the proliferation of liver cells. In the future, the molecular biological effects of lower doses and dose rates need to be evaluated.

• 천문학회지
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• 제33권1호
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• pp.37-45
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• 2000

We have investigated the properties of the high-latitude cloud MBM 7 using the 3 mm transitions of CO, CS, HCN, $HCO^+,\;C_3H_2,\;N_2H^+$, and SiO. The molecular component of MBM 7 shows a very clumpy structure with a size of $\le$0.5 pc, elongated along the northwest-southeast direction, perpendicularly to an extended HI component, which could be resulted from shock formation. We have derived physical properties for two molecular cores in the central region. Their sizes are 0.1-0.3 pc and masses 1-2 M$\bigodot$ having an average volume density $\~2{\times}10^3 cm^{-3}$ at the peak of molecular emission. We have tested the stability of the cores using the full version of the virial theorem and found that the cores are stabilized with ambient medium, and they are expected not to be dissipated easily without external perturbations. Therefore MBM 7 does not seem to be a site for new star formation. The molecular abundances in the densest core appear to be much less (by about one order of magnitude) than the 'general' dark cloud values. If the depletions of heavy elements are not significant in the HLCs compared with those in typical dark clouds, our results may suggest different chemical evolutionary stages or different chemical environments of the HLCs compared with dense dark clouds in the Galactic plane.

• The Plant Pathology Journal
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• 제18권5호
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• pp.266-270
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• 2002

Inbred lines of Chinese cabbage KU-101 (resistant line against Plasmodiophora brassicae race race 6) and CS-113 (susceptible line) were crossed and their progeny lines F$_1$, BC$_1$F$_1$, F$_2$, and F$_3$ were produced for the construction of the genetic linkage map of R brassicae race 6-resistant Brassica campestris ssp. pekinensis genome. Restriction fragment length polymorphism (RFLP) was applied to compare between parents and their f$_2$ progenies with a total of 192 probes and 5 restriction enzymes. The constructed RFLP map covered 1,104 cM with a mean distance between genetic marker of 8.0 cM, and produced 10 linkage groups having 121 genetic loci. The loci of P. brassicae race 6 (CR6)-resistant Brassica genome were determined by interval mapping of quan-titative trait loci (QTL), which resulted from bioassay using the same race of the fungi in P3 population. Resistant loci were estimated in numbers 1 (Gl) and 3 (G3) linkage groups. In the regression test, Gl had a value of4.8 logarithm of odd (LOD) score, while C3 had values of 4.2-7.2. Given these results, the location of the CR6-resistant loci within the Brassica genome map can now be addressed.

• 한국결정성장학회지
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• 제22권1호
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• pp.11-14
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• 2012

AlGaN는 3.4~6.2 eV까지 넓은 밴드갭을 가지는 직접천이형 반도체이다. 최근에 자외영역의 광소자가 다양하게 응용되면서 자외선 발광이 가능한 AlGaN 역시 주목받고 있다. 이를 위해서는 고품질의 AlGaN 층이 필요하지만 GaN 층위에 AlGaN 층을 성장하는 것은 이들의 격자상수와 열팽창계수 차이로 인해 어렵다. 본 논문에서, multi-sliding boat법이 적용된 혼합소스 HVPE법을 이용하여 GaN template 위에 LED 구조를 성장하였다. 활성층의 Al 조성을 조절함으로써 AlGaN의 격자상수 변화와 광학적 변화를 관찰하고자 하였다. 에피 성장을 위해 HCl과 $NH_3$ 가스를 혼합소스 표면으로 흘려주었고, 수송가스로는 $N_2$를 사용하였다. 소스영역과 성장영역의 온도는 각각 900과 $1090^{\circ}C$로 안정화하였다. 성장 후 샘플은 x-ray diffraction(XRD)과 electro luminescence(EL) 측정을 하였다.

• 한국산학기술학회:학술대회논문집
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• 한국산학기술학회 2010년도 춘계학술발표논문집 2부
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• pp.1233-1236
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• 2010

본 연구에서는 메탄을 물질로 산화실험을 수행하였다. 메탄의 발화온도가 탄화수소 중에 가장 높으며, 대부분의 전이금속촉매 활성온도가 가장 높게 나타나는 물질이므로 메탄의 연소가 일어날 경우 대부분의 탄화수소류는 연소가 일어날 수 있으므로 메탄의 산화반응을 연구하였다. 메탄의 산화를 위한 전이금속 촉매중 망간을 산화물형태로 $Al_2O_3$, $TiO_2$에 담지하여 메탄에 대한 활성능을 측정하였으며, 조촉매로 금속산화물을 이용하여 활성능의 변화를 연구하였다. 또한 자연에 존재하는 천연망간광석과 금속산화물을 담지하여 최적의 메탄에 대한 활성능을 지닌 촉매를 선별하였다. 조촉매로는 Ce, Sn, Ni, Co, Mo 등을 이용하였다. 또한 본 연구에서는 촉매 제조는 과잉용액함침법을 사용하여 담지체에 촉매물질을 분산하였으며, 온도와 유량에 대한 각 조성 촉매의 활성능을 측정하여 활성화에너지 및 $T_{50}$, $T_{90}$을 도출하였다.

• The Korean Journal of Physiology
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• 제19권2호
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• pp.113-125
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• 1985

Electrophysiological difference of the central and peripheral area of the sinoatrial node in the rabbit was studied by glass microelectrode technique. Effects of $K^+,\;Na^+,\;Cs^+,$ adrenaline and ouabain on the action potential of the two areas were investigated, and transient hyperpolarization ($K^+-induced$ hyperpolarization) which developed following readmission of potassium after having pre-treated with $K^+-free$ Tyrode solution for 10 minutes was analyzed. The results obtained were as follows ; 1) The frequency of the spontaneous action potential recorded in the periphery of the SA node was faster than the central area. Reduction by $Cs^+$ and increase by O mM $K^+$, $10^{-6}M$ adrenaline and $10^{-6}M$ ouabain in the frequency of action potential were noticed more prominently in the peripheral than the central area. On the contrary, the frequency in the central area was more decreased than the Peripheral area by 13 mH $K^+$ and 1 mM $Co^{2+}$. 2) The amplitude of the K+_induced hyperpolarization was very small in the central area but large in the peripheral area. Transient hyperpolarization was abolished by ouabain and low sodium, and decreased by cooling the tissue $(17^{\circ}C)$. 3) By changing the concentration of $Ca^{2+}$ in the perfusate, the amplitude and the rate of transient hyperpolarization were increased in the high $Ca^{2+}$ concentration. It could be concluded that the central area of the SA node is less susceptible to the inhibition of Na-Pump and more susceptible to Ca-blocker and high concentration of $K^+$. The Na-Pump activity of the central area measured by means of transient hyperpolarization is found to be much less active than that of the peripheral area.

• 자원환경지질
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• 제39권3호
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• pp.329-342
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• 2006

이 연구에서는 곤양지역 하상퇴적물에 대한 지구화학적 특성을 규명하고 환경오염과 지질재해에 대해서 이해하고자 한다. 이를 위해 물이 흐르고 있는 1차 수계를 대상으로 하상퇴적물시료 178개를 채취하였고, 실험실에서 자연건조 시켰다. 시료는 알루미나 몰타르를 이용하여 200메쉬 이하로 분쇄하였고, XRD, XRF, ICP-AES, NAA분석을 실시하였다. 연구지역 하상퇴적물 지질집단별 지구화학적 특성 비교를 위해, 석영반암 지역, 퇴적암류 지역, 아노르도사이트 지역과 편마암류 지역으로 분류하였다. 곤양지역 하상퇴적물의 주성분원소 함량은 $SiO_2\;41.86{\sim}76.74\;wt.%,\;Al_{2}O_{3}\;9.92{\sim}30.00\;wt.%,\;Fe_{2}O_{3}\;2.74{\sim}12.68\;wt.%,\;CaO\;0.22{\sim}3.31\;wt.%\;,MgO\;0.34{\sim}3.97\;wt.%,\;K_{2}O\;0.75{\sim}0.93\;wt.%,\;Na_{2}O\;0.25{\sim}1.92\;wt.%,\;TiO_{2}\;0.40{\sim}3.00\;wt.%,\;MnO\;0.03{\sim}0.21\;wt.%,\;P_{2}O_{5}\;0.05{\sim}0.38\;wt.%$이다. 하상퇴적물의 미량성분원소 및 희토류원소 함량은 $Cu\;7{\sim}102\;ppm,\;Pb\;15{\sim}47\;ppm,\;Sr\;48{\sim}513\;ppm,\;V\;29{\sim}129\;ppm,\;Zr\;31{\sim}217\;ppm,\;Li\;14{\sim}94\;ppm,\;Co\;5.6{\sim}32.1\;ppm,\;Cr\;23{\sim}259\;ppm,\;Cs\;1.7{\sim}8.7\;ppm,\;Hf\;2.1{\sim}109.0\;ppm,\;Rb\;34{\sim}247\;ppm,\;Sc\;4.5{\sim}21.9\;ppm,\;Zn\;24{\sim}609\;ppm,\;Sb;0.8{\sim}2.6\;ppm,\;Th\;3{\sim}213\;ppm,\;Ce\;22{\sim}1000\;ppm,\;Eu;0.7{\sim}5.3\;ppm,\;Yb\;0.6{\sim}6.4\;ppm$의 범위를 보인다.

• 융합정보논문지
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• 제11권3호
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• pp.7-13
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• 2021

본 연구는 딥러닝(Deep Learning) 알고리즘 GAN 모델을 기반으로 초미세먼지(PM2.5) 인공지능 예측시스템을 개발한다. 실험 데이터는 시계열 축으로 생성된 온도, 습도, 풍속, 기압의 기상변화와 SO2, CO, O3, NO2, PM10와 같은 대기오염물질 농도와 밀접한 관련이 있다. 데이터 특성상, 현재시간 농도가 이전시간 농도에 영향을 받기 때문에 반복지도학습(Recursive Supervised Learning) 예측 모델을 적용하였다. 기존 모델인 CNN, LSTM의 정확도(Accuracy)를 비교분석을 위해 관측값(Observation Value)과 예측값(Prediction Value)간의 차이를 분석하고 시각화했다. 성능분석 결과 제안하는 GAN이 LSTM 대비 평가항목 RMSE, MAPE, IOA에서 각각 15.8%, 10.9%, 5.5%로 향상된 것을 확인하였다.

• 천문학회지
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• 제24권2호
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• pp.217-271
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• 1991

We have observed dense core around young stellar objects, DR21, S140, Orion-KL, and L1551 using four millimeter-wave transitions of $HC_3N\;J$=4-3, J=5-4, J=10-9, and J=12-11. The spatial distribution of $HC_3N$ emission closely resembles the morphology of the previous CS observations that trace high density gas. These observations reveal the existence of $HC_3N$ dense cores around central IR source, elliptical in shape and almost perpendicular to the CO bipolar outflow axis. Small differences can be explained by that $HC_3N$ molecular line is more optically thin and is seen to be more detailed structure in the neighborhood of central IR sources. In S140 and Orion-KL, massive(${\sim}10\;M_{\odot}$), slowly rotating dense cores lie near at the central IR sources of bipolar outflows. The velocity channel maps of DR21 show that the bipolar outflow gas may have a correlation with the dense core of DR21. We analyzed intensities of the four lines to derive physical conditions in dense core from two methods, LTE and LVG. The column density of $HC_3N$, $N(HC_3N)$, between LTE and LVG calculations agree well with each other. The abundances of $HC_3N$ in each observing source have been estimated using the average values of $n(H_2)$ and $N(HC_3N)$ and assuming the size of dense core. The fractional $HC_3N$ abundances in massive dense cores of DR21, S140, and Orion-KL have a range of $(2-7){\times}10^{-10}$, while that of low mass dense core, L1551, has one order of magnitude greater value of $2{\times}10^{-9}$. This should be considered good agreement with the result by Morris et al.(1976). It may be considered that dense cores of DR21, S140, and Orion-KL may have almost same stage of chemical evolution, and their abundances have a small values relative to that of L1551. The column density $N(HC_3N)$ decreases with increasing distance from the densest part of the cloud, the central infrared source, and have the relation of $N(HC_3N){\varpropto}R^{\alpha}$, where a has a range of 0.65 to 0.89. The values of $n(H_2)$ are not varied with increasing distance from the dense core, and have almost same values. Therefore, it is considered that the dense cores in these regions probably consist of dense clumps in diffuse molecular gas medium, and $n(H_2)$ of each clump is ${\sim}10^5\;cm^{-3}$. Levels in the $T_{ex}$ increases with $n(H_2)$. It is considered that the $HC_3N$ dense cores are not completely thermalized. We examine the relationships between the luminosity of central infrared sources versus mass of the dense cores, and the luminosity of central infrared sources versus molecular hydrogen column density. Luminosities of the central IR sources show good correlation with mass and hydrogen column density of the dense core. Same has been found from CS observations. However, mass and size derived from $HC_3N$ observations are one order of magnitude smaller than those from CS. It can be interpreted that we see more central part of the cloud cores in $NC_3N$ lines than CS lines.

• Journal of the Korean Wood Science and Technology
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• 제49권6호
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• pp.658-666
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• 2021

A novel flame retardant and antibacterial composite membrane coating for wood surfaces was prepared by adding POSS-based phosphorous nitrogen flame retardant (later referred to as NH₂-POSS) and silver nanoparticles (Ag NPs) to chitosan (CS). The effects of NH₂-POSS content (mass fractions of CS 0%, 0.5%, 1%, 3%, 5%, and 7%) on the structure and properties of the composite membrane coating on wood were investigated. The composite film was prepared by the method of blending and ducting. Contact angle, tensile property and antibacterial effects of the composite film were measured, and infrared spectroscopy was used. The results show that the addition of NH₂-POSS can not only improve the toughness of the membrane, but also the flame retardancy of the membrane, which improves the application of the membrane in wood products. However, with the addition of NH₂-POSS, the transparency of the composite membrane was weakened. The inhibitory effect of the composite membrane on the growth of Escherichia coli was enhanced with the increase in Ag NPs. This research provides a foundation for the application of functional wood.