• Nuclear Engineering and Technology
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• 제48권2호
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• pp.293-298
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• 2016

Thirty-eight spherules from the Antarctic ice sheet were analyzed using neutron activation analysis under two different conditions to investigate their origin. In almost all of these spherules, the contents of iron, cobalt, and manganese were determined to be 31% to 88%, 17 mg/kg to 810 mg/kg, and 0.017% to 7%, respectively. A detectable iridium content of 0.84 mg/kg was found in only one spherule, which was judged to be extraterrestrial in origin. A comparison of elemental compositions of the Antarctic spherules analyzed in this study with those of deep-sea sediment spherules and those of terrestrial materials revealed that most of the Antarctic spherules except for the sample in which iridium was detected could not be identified as extraterrestrial in origin.

• 약학회지
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• 제29권2호
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• pp.96-102
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• 1985

Innovated utilization of Korean kaolins as pharmaceuticals is attempted, for which relevant properties including adsorptive behaviours are observed in connection with their mineralogical structures. In practice, physico-chemical properties are assessed by means of IR, XRD and thermal analysis including DTA, TG and DSC. Elemental analysis of the ore specimens under investigation is carried out in conventional manners. It is found that the chemical compositions are varied significantly with sampling sites and primary classifications. The clay ores thus analyzed are mainly composed of halloysite species. Proper benefication of the raw clays is necessary so that authentic requirements for medicinal use may be satisfied. White-colored premium grade halloysite could be utilized as therapeutics with relative ease after purification. Evidence indicates that gibbsite-like impurities are intercalated between the 1 : 1 layered moieties. Thermal behaviours may be characterized in such a fashion that loss of free water occurs near 100.deg. C and further heatings result in liberation of bound water near 500.deg. C, with subsequent transformation into amorphous metastable entities. Through thermal activation, enhanced pharmaceutical effects could be envisaged.

• Journal of Forest and Environmental Science
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• 제9권1호
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• pp.67-80
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• 1993

무공해 대체 펄프화법 개발의 일환으로 비교척 최근에 많은 연구가 이루어지고 있는 아세트산-물 용매 증해법을 이용하여 현사시나무와 소나무률 펄프화 하였다. 펄프 특성의 변화에서 현사시나무는 거의 모든 아세트산 충해초건에서 우수한 펄프화 경향을 보였지만 소나무는 저온에서 충해가 거의 일어나지 않았다. 현사시나무의 최적 중해조건은 중해농도 95%, 중해온도 $185^{\circ}C$, 증해시간 0.5hr이었다. 구성당 성분의 거동은 현사시나무와 소나무에서 glucose만이 소량 감소하는 반면 그외의 당성분들은 다량 용출되었다. 폐액중의 용출 아세트산 리그닌에 대한 기초척인 성질을 살펴본 결과 현사시나무의 아세트산 리그닌의 원소조성은 C가 63.88%, H가 5.45%, O가 30.67%이며 $C_9$의 formular는 $C_9H_{9.15}O_{3.24}$였고 소나무의 아세트산 리그닌의 조성온 C가 61.85%, H가 6.14%, O가 32.01% 이며 $C_9$의 formular는 $C_9H_{9.15}O_{3.50}$이었으며 두 수종의 아세트산 리그닌 중합 명균분자량은 현사시나무가 731이며 소나무는 725였다.

• 분석과학
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• 제26권4호
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• pp.245-255
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• 2013

교통사고로 인해 피해자 의류 또는 사고관련 차량에 부착된 페인트는 법과학적으로 중요한 증거물이다. 의류에 부착된 페인트는 용의차량을 추적하고 교통사고의 피해자임을 입증할 수 있는 단서가 되며, 피해차량과 용의차량에 상호 전이되어 부착된 페인트는 페인트의 동일성 비교로써 사고의 진실을 밝히고 사고 상황을 재구성하는데 중요한 역할을 한다. 부착된 페인트는 보통 미량의 시료이고 특히 단색인 흰색, 노란색, 적색, 청색, 검정색인 경우 페인트 동일성 비교는 입체현미경으로 색상과 안료에 함유된 알루미늄, 펄, 마이카 등의 입자 형상에 대한 상호 비교가 곤란하므로 이에 대한 분석법이 요구되었다. 따라서 본 연구의 목적은 단색의 차량 페인트에서 색상을 구현하는 basecoat 층에 대해 micro-FT-IR과 micro-XRF를 이용하여 안료의 바인더 수지와 무기안료의 구성원소를 확인하여 법과학적 측면에서 페인트 동일성 비교를 하고자 하였다. FT-IR 분석은 시료를 전처리 없이 Reflectance와 ATR 2가지 방법을 병용했으며 Reflectance 스펙트럼은 $4000{\sim}2000cm^{-1}$ 영역에서 aromatics과 aliphatic, acrylonitrile 등의 피크 정보를 얻었고 ATR 스펙트럼은 $2000{\sim}650cm^{-1}$ 영역에서 carbonyl, isocyanate, carbamate 등의 피크 및 피크의 패턴 비교로 안료의 바인더 수지를 비교하는데 이용하였다. 또한 XRF 분광법은 미량 페인트의 무기안료에 함유된 구성원소를 확인하여 적외선 흡수스펙트럼으로 동일성 비교가 곤란한 시료에 대해 판별 가능하게 하였다.

• 문화기술의 융합
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• 제1권2호
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• pp.65-69
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• 2015

인체 골격의 열에 대한 영향의 연구는 주로 뼈와 치아에 한정되어져 왔는데, 인체의 다른 조직에 비해 고온에서 저항성이 크고 장시간의 열의 노출에도 인지할 수 있는 형태로 남아있기 때문이다. 고온에 따른 치아의 조직변화에 대해서는 많은 연구가 있어왔지만, 뼈에 관한 연구는 미진하며, 한국에서는 이에 대한 연구가 전무하다. 본 연구에서는 주사전자현미경과 에너지분산분광분석기로 한국인 남녀의 화장 후 분골을 분석하였으며, 그 결과 남녀 모두 두 종류의 결정(구형, 6각형 프리즘형태)이 관찰되었으며, 남자보다 여자의 분골 결정이 작고 더 둥글었다. 칼슘과 산소의 양이 분골 무기질의 대부분을 차지하였는데, 이는 고온에서 형성되는 CaO(칼슘옥사이드)에 의한 것으로 확인할 수 있었다.

• 한국지하수토양환경학회지:지하수토양환경
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• 제20권7호
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• pp.70-79
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• 2015

A sample of soil humic acid (HA) was divided by ultrafiltration (UF) into five fractions of different molecular size (UF₁: > 300, UF₂: 100~300, UF₃: 30~100, UF₄: 10~30, UF₅: 1~10 kilodaltons). Apparent average molecular weight (M_w) of the HA fractions were measured using high performance size exclusion chromatography (HPSEC), and the chemical and structural properties of the five HA fractions were characterized by elemental compositions (H/C, O/C and w ((2O + 3NH)/ C)) and ultraviolet-visible absorption ratios (SUVA, A_4/6). The organic carbon normalized-sorption coefficients (Koc) for the binding of phenanthrene to the HA fractions were determined by fluorescence quenching and relationship between the sorption coefficients and structural characteristics of the HA fractions were investigated. The elemental analysis and UV-vis spectral data indicated that the HA fractions with higher molecular weights have grater aliphatic character and lower contents of oxygen, while the HA fractions with lower molecular size have greater aromatic character and molecular polarity that correspond to greater SUVA and internal oxidation values (w). The log Koc values (L/kg C) were gradual increased from 4.45 for UF₅ to 4.87 for UF1. The correlation study between the structural descriptors of the HA fractions and log Koc values of phenanthrene show that the magnitude of Koc values positively correlated with $M_w$ and H/C, while negatively correlated with the independent descriptors of the O/C, w, SUVA and A_4/6.

• Asian Journal of Atmospheric Environment
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• 제11권2호
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• pp.79-95
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• 2017

A number of field studies have provided evidence that biomass burning is one of the major global sources of atmospheric particles. In this study, we have collected $PM_{2.5}$ emitted from biomass burning combusted at open burning and laboratory chamber situations. The open burning experiment was conducted with the cooperation of 9 farmers in Chiba Prefecture, Japan, while the chamber experiment was designed to evaluate the characteristics of chemical components among 14 different plant species. The analyzed categories were $PM_{2.5}$ mass concentration, organic carbon (OC), elemental carbon (EC), ionic components ($Na^+$, ${NH_4}^+$, $Ca^{2+}$, $Mg^{2+}$, $K^+$, $Cl^-$, ${NO_3}^-$ and ${SO_4}^{2-}$), water-soluble organic carbon (WSOC), water-insoluble inorganic carbon (WIOC), char-EC and soot-EC. OC was the dominant chemical component, accounting for the major fraction of primary $PM_{2.5}$ derived from biomass burning, followed by EC. Ionic components contributed a small portion of $PM_{2.5}$, as well as that of $K^+$. In some cases, $K^+$ is used as biomass burning tracer; however, the observations obtained in this study suggest that $K^+$ may not always be suitable as a tracer for biomass burning emissions. Also, the results of all the samples tested indicate relatively low values of char-EC compared to soot-EC. From our results, careful consideration should be given to the usage of $K^+$ and char-EC as indicators of biomass burning. The calculated ratios of WSOC/OC and WIOC/OC were 55.7% and 44.3% on average for all samples, which showed no large difference between them. The organic materials to OC ratio, which is often used for chemical mass closure model, was roughly estimated by two independent methods, resulting in a factor of 1.7 for biomass burning emissions.

• Nuclear Engineering and Technology
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• 제50권6호
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• pp.957-962
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• 2018

The gamma radiation shielding capability (GRSC) of two clay-materials (Ball clay and Kaolin)of Southwestern Nigeria ($7.49^{\circ}N$, $4.55^{\circ}E$) have been investigated by determine theoretically and experimentally the mass attenuation coefficient, ${\mu}/{\rho}(cm^2g^{-1})$ of the clay materials at photon energies of 609.31, 1120.29, 1173.20, 1238.11, 1332.50 and 1764.49 keV emitted from $^{214}Bi$ ore and $^{60}Co$ point source. The mass attenuation coefficients were theoretically evaluated using the elemental compositions of the clay-materials obtained by Particle-Induced X-ray Emission (PIXE) elemental analysis technique as input data for WinXCom software. While gamma ray transmission experiment using Hyper Pure Germanium (HPGe) spectrometer detector to experimentally determine the mass attenuation coefficients, ${\mu}/{\rho}(cm^2g^{-1})$ of the samples. The experimental results are in good agreement with the theoretical calculations of WinXCom software. Linear attenuation coefficient (${\mu}$), half value layer (HVL) and mean free path (MFP) were also evaluated using the obtained ${\mu}/{\rho}$ values for the investigated samples. The GRSC of the selected clay-materials have been compared with other studied shielding materials. The cognizance of various factors such as availability, thermo-chemical stability and water retaining ability by the clay-samples can be analyzed for efficacy of the material for their GRSC.

• 한국분말재료학회지
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• 제26권5호
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• pp.375-382
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• 2019

Homogeneous multicomponent indium gallium zinc oxide (IGZO) ceramics for transparent electrode targets are prepared from the oxides and nitrates as the source materials, and their properties are characterized. The selected compositions were $In_2O_3:Ga_2O_3:ZnO$ = 1:1:2, 1:1:6, and 1:1:12 in mole ratio based on oxide. As revealed by X-ray diffraction analysis, calcination of the selected oxide or nitrides at $1200^{\circ}C$ results in the formation of $InGaZnO_4$, $InGaZn_3O_6$, and $InGaZn_5O_8$ phases. The 1:1:2, 1:1:6, and 1:1:12 oxide samples pressed in the form of discs exhibit relative densities of 96.9, 93.2, and 84.1%, respectively, after sintering at $1450^{\circ}C$ for 12 h. The $InGaZn_3O_6$ ceramics prepared from the oxide or nitrate batches comprise large grains and exhibit homogeneous elemental distribution. Under optimized conditions, IGZO multicomponent ceramics with controlled phases, high densities, and homogeneous microstructures (grain and elemental distribution) are obtained.

• 환경분석과 독성보건
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• 제21권4호
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• pp.229-236
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• 2018

In this study, inter-laboratory comparison was done using elemental analyzer-isotope ratio mass spectrometers (EA-IRMSs) to determine carbon and nitrogen contents as well as stable carbon and nitrogen isotopic compositions (${\delta}^{13}C$ and ${\delta}^{15}N$) of five environmental samples containing lake and marine sediments, higher plant leaves, and fish muscle, and one organic analytical standard (Protein (Casein) Standard OAS). Five national laboratories participated in this comparison study, and each laboratory analyzed all five samples and the analytical standard. Results showed that variations in total organic carbon (TOC) and total nitrogen (TN) contents as well as ${\delta}^{13}C_{TOC}$ and ${\delta}^{15}N_{TN}$ values among the laboratories were large compared to the analytical uncertainties. The results highlighted the inhomogeneity of the test samples and thus, the need to select suitable standard reference materials for future inter-laboratory studies. Further inter-laboratory comparison exercises could promote good measurement practices in the acquisition of stable carbon and nitrogen isotopic composition data.