• Journal of Korean Society of Environmental Engineers
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• v.22 no.6
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• pp.1113-1126
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• 2000

Humic substances present in landfill leachates were extracted and their characteristics were analyzed with respect to landfilling age as a basic study to evaluate the effect of humic substances on the transport and transformation of other pollutants in pollution plume contaminated by landfill leachate. Element analysis of the extracted humic substances were performed. The information on the functional groups of the humic substances molecules were obtained from the spectroscopic analysis using UV-visible, FT/IR, and fluorescence spectroscopy. The structural characteristics of the humic substances were also analyzed by $^1H$ and $^{13}C$ NMR spectroscopy. From the results of the analyses it was found that the structure of the humic substances present in landfill leachates was more aliphatic than aromatic relative to other common humic substances extracted from natural soils and water. The results indicate that the degree of humification of the humic substances were relatively low. The degree of humification, however, was increased as the landfilling age was increased.

• Proceedings of the Korean Institute of Surface Engineering Conference
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• 2013.05a
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• pp.184-184
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• 2013

본 연구에서는 금 합금 도금층의 접촉저항에 미치는 첨가 합금원소의 영향을 조사하였다. 또한 표면실장을 위한 솔더링 공정에서 도금층에 가해지는 열이력이 접촉저항 값에 미치는 영향을 조사하기 위해서, $260^{\circ}C$에서 thermal aging을 실시한 후, 접촉저항을 측정하였다. 합금원소의 종류에 따라서 thermal aging후의 접촉저항 값이 변하는 요인을 조사하기 위해서 XPS를 이용하여 표면분석을 실시하였다.

• Proceedings of the KSEEG Conference
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• 2003.04a
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• pp.245-248
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• 2003

현재까지 폐석 및 광미의 환경적 영향에 대한 많은 연구들은 중금속원소 등의 총 농도 분석 및 화학용매를 이용한 부분추출을 통해 중금속의 존재형태를 규명하는데 중점을 두었다. 하지만 대부분 지표환경에 제한되어 중금속 원소들의 오염원으로서의 잠재성, 즉 심도별 중감속원소 함유 광물의 pH 및 산화ㆍ환원 조건변화에 따른 용해도 특성과 이동성 등에 대한 정보를 제공하기에는 미흡하다. (중략)

• Analytical Science and Technology
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• v.7 no.3
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• pp.293-299
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• 1994

Fifty ancient Korean coins originated in Choson period have been determined for 11 elements such as Sn, Fe, As, Au, Co, Sb, Ir, Os, Ru and Ni by destructive and non-destructive neutron activation analysis as well as for 3 elements such as Cu, Pb and Zn by atomic absorption spectroscopy. The multivariate data have been analyzed by principal component mapping method. The spread of sample points in the eigenvector polt has been attributed to common origins of some elements.

• Korean Journal of Soil Science and Fertilizer
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• v.42 no.5
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• pp.399-407
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• 2009

Laser induced breakdown spectroscopy(LIBS) is an simple analysis method for directly quantifying many kinds of soil micro-elements on site using a small size of laser without pre-treatment at any property of materials(solid, liquid and gas). The purpose of this study were to find an optimum condition of the LIBS measurement including wavelengths for quantifying soil elements, to relate spectral properties to the concentration of soil elements using LIBS as a simultaneous un-breakdown quantitative analysis technology, which can be applied for the safety assessment of agricultural products and precision agriculture, and to compare the results with a standardized chemical analysis method. Soil samples classified as fine-silty, mixed, thermic Typic Hapludalf(Memphis series) from grassland and uplands in Tennessee, USA were collected, crushed, and prepared for further analysis or LIBS measurement. The samples were measured using LIBS ranged from 200 to 600 nm(0.03 nm interval) with a Nd:YAG laser at 532 nm, with a beam energy of 25 mJ per pulse, a pulse width of 5 ns, and a repetition rate of 10 Hz. The optimum wavelength(${\lambda}nm$) of LIBS for estimating soil and plant elements were 308.2 nm for Al, 428.3 nm for Ca, 247.8 nm for T-C, 438.3 nm for Fe, 766.5 nm for K, 85.2 nm for Mg, 330.2 nm for Na, 213.6 nm for P, 180.7 nm for S, 288.2 nm for Si, and 351.9 nm for Ti, respectively. Coefficients of determination($r^2$) of calibration curve using standard reference soil samples for each element from LIBS measurement were ranged from 0.863 to 0.977. In comparison with ICP-AES(Inductively coupled plasma atomic emission spectroscopy) measurement, measurement error in terms of relative standard error were calculated. Silicon dioxide(SiO2) concentration estimated from two methods showed good agreement with -3.5% of relative standard error. The relative standard errors for the other elements were high. It implies that the prediction accuracy is low which might be caused by matrix effect such as particle size and constituent of soils. It is necessary to enhance the measurement and prediction accuracy of LIBS by improving pretreatment process, standard reference soil samples, and measurement method for a reliable quantification method.

• Analytical Science and Technology
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• v.26 no.6
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• pp.387-394
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• 2013

We aim to unveil dietary history recorded in Neolithic human bone from Janghang site at Gadeok Island, Busan. Excavation of Janghang site at Gadeok Island from 2010 to 2011 is an outstanding discovery in Korean Neolithic archaeology. A large number of human bones (48 individuals) were found at Janghang site, which is the largest-scale Neolithic cemetery in Korea. We extracted human bone collagen from 10 individuals and stable carbon and nitrogen isotope analysis were carried out using carbon and nitrogen analyzer connected to a continuous-flow isotope-ratio-monitoring mass-spectrometer. Although bone histological analysis shows poor preservation state, stable isotope results correspond well with bone collagen quality indicator, which implies that bone collagen reflects lifetime signature. Stable carbon and nitrogen isotope result indicates highly marinebased diet(${\delta}^{13}$C=$-14.5{\pm}1.3$‰, ${\delta}^{15}$N=$-17.4{\pm}1.7$‰, n=10), however the possible input of terrestrial animal and wild plant cannot be excluded. Our isotopic findings provide an invaluable information on Neolithic subsistence economy in this coastal area. In addition, Janghang site shows specific features in burial methods and burial goods. Two different burial methods of arranging bodies are found with extended burial type and particularly high ratio of flexed burial type. There are also burial goods such as pottery. However, there are no significant isotopic differences according to burial methods and burial goods. Although this is a preliminary study on this site, our research will provide important clues in understanding isotopic dietary history of Korean Neolithic people.

• Analytical Science and Technology
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• v.14 no.2
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• pp.103-108
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• 2001

Rare earth elements(REE) were separated by solvent extraction with tri-n-butyl phosphate(TBP) and $NaNO_3$, followed by back extraction with water. The method was applied to the determination of REE to circumvent the spectral interferences of ICP-AES analysis. The effects of the $NaNO_3$ concentration and the addition of hydrophobic solvents on the extraction efficiencies were investigated. Increases of the $NaNO_3$ concentration enhanced the extraction efficiencies of REE, and more than 95% recoveries were obtained at 5M of $NaNO_3$ concentration. On the other hand, addition of hydrophobic solvents lowered the extraction efficiencies. The method was applied to determine the REE in the monazite sample. But the precisions of the analytical results were more than 20%.

• Korean Journal of Mineralogy and Petrology
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• v.36 no.4
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• pp.355-363
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• 2023

In this study, we explore the nature of clumped isotopes of H₂O molecule using quantum chemical calculations. Particularly, we estimated the relative clumping strength between diverse isotopologues, consisting of oxygen (¹⁶O, ¹⁷O, and ¹⁸O) and hydrogen (hydrogen, deuterium, and tritium) isotopes and quantify the effect of temperature on the extent of isotope clumping. The optimized equilibrium bond lengths and the bond angles of the molecules are 0.9631-0.9633 Å and 104.59-104.62°, respectively, and show a negligible variation among the isotopologues. The calculated frequencies of the modes of H₂O molecules decrease as isotope mass number increases, and show a more prominent change with varying hydrogen isotopes over those with oxygen isotopes. The equilibrium constants of isotope substitution reactions involving these isotopologues reveal a greater effect of hydrogen mass number than oxygen mass number. The calculated equilibrium constants of clumping reaction for four heavy isotopologues showed a strong correlation; particularly, the relative clumping strength of three isotopologues was 1.86 times (HT¹⁸O), 1.16 times (HT¹⁷O), and 0.703 times (HD¹⁷O) relative to HD¹⁸O, respectively. The relative clumping strength decreases with increasing temperature, and therefore, has potential for a novel paleo-temperature proxy. The current calculation results highlight the first theoretical study to establish the nature of clumped isotope fractions in H₂O including ¹⁷O and tritium. The current results help to account for diverse geochemical processes in earth's surface environments. Future efforts include the calculations of isotope fractionations among various phases of H₂O isotopologues with a full consideration of the effect of anharmonicity in molecular vibration.

• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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• v.6 no.1
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• pp.27-34
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• 2001

To investigate the processes governing the distribution of elements in the tidal flat, thirty-eight sediment samples collected from the Saemangeum tidal flat of the Korean west coast were analyzed for their contents of major (Al, Fe, Mg, Ca, Na, K, Ti) and trace (P, Mn, Ba, Sr, V, Cr, Co, Cu, Ni, Zn, Pb) elements. Most elements showed generally lower contents compared to data published for other tidal flats of Korea, and the effect of anthropogenic input could not be recognized in the sediments. The relative abundance and distribution of most of the elements varied significantly with the grain size of sediments. High contents of Al, Fe, Mg, Ti, P, Mn, V, Co, Cr, Cu, Ni and Zn were found in the finer sediments in the upper tidal flat of the study area, suggesting that tidal sedimentation processes play an important role in controlling the distribution of these elements. However, sediment grain size does not impose any significant effect on the abundance and distribution of Ca, Na, K, Ba, Sr and Pb. It appears that the clastic mineralogy in the coarse-grained fractions is the dominant factor determining the distribution of these elements in the study area.

• Journal of Radiation Protection and Research
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• v.40 no.2
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• pp.101-109
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• 2015

Alpha spectrometry is typically used for the assessment of uranium particle concentrations and its accuracy can be directly related to the accuracy in which the radiochemical pre-treatment is conducted. Ashing and alkali fusion methods are typically used but the ashing method requires longer analysis time and the alkali fusion method is extremely costly. Therefore, a new pre-treatment method using ultrasonic cleaning was developed and its experimental result was compared against the two conventional methods in terms of pre-treatment time, convenience, cost, and recovery rate of a target material. The results that were obtained by the conventional methods(ashing and alkali fusion) and the new method were compared. Consequently, even though the shorter pre-treatment time was required, the new technique showed almost same recovery rate comparing with two conventional methods. The new method was also featured by its relatively lower cost and a simpler process than two conventional methods.