• Bulletin of the Korean Chemical Society
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• 제33권11호
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• pp.3711-3718
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• 2012

Here, we report a chain-length dependent morphology and pore structure tailing of mesoporous silica templated from organogels, which is formed by primary alkylamine and ethylene glycol at room temperature. As the chain length of alkylamine changes from 12 to 18, the resulted materials exhibit a morphology change from layers to spheres and platelets, respectively. SEM and TEM observation revealed that these shapes appear to be inherited from their parent organogels. Further pore structure characterization by nitrogen sorption analysis demonstrates that all the resulted silicas exhibit typical IV isotherms indicative of uniform mesopores, and their pore sizes are dependent on the chain length of alkylamine used.

• 한국지반공학회:학술대회논문집
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• 한국지반공학회 2008년도 추계 학술발표회
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• pp.1512-1517
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• 2008

Laboratory column tests were conducted in this study using $Cl^-$ tracers on Jumunjin sand to analyze contaminant transport in mixed contaminated soils. Results obtained from clean soils and soils containing residual diesel verified heterogeneous distribution of residual diesel, and clear acceleration of solute movement. In addition, asymmetric breakthrough curves indicated development of immobile region where solute movement becomes stagnant and creates tailing phenomenon.

• 한국토양환경학회지
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• 제4권2호
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• pp.175-183
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• 1999

진곡광산의 광미와 주변 밭과 논의 토양에서의 중금속과 시안의 오염도에 대해 조사하였다. 광미 중의 As, Cd, Cu, Hg, Pb, Zn및 CN￣의 평균농도는 각각 3.94$\times$$10^3$, 14.3, 266, 6,13, 4.07$\times$$10^3$, 2.51$\times$$10^3$, 1.19mg/kg이었고 Kloke가 제안한 허용기준치를 이용한 오염지수는 32~58 이었으며 pH 는 약산성이었다. 토양오염공정시험법에 의한 중금속 농도는 광미와 인접한 일부 토양만을 제외하고는 토양환경보전법의 농경지 우려기준이하였다.

• 한국안전학회지
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• 제22권2호
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• pp.8-14
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• 2007

In this study, tensile and fatigue crack propagation tests machined from actual wheels were performed. FEM analysis also was performed on the crack that was assumed to be 15 mm in depth under the wheel tread surface. The stress intensity factors K I and K II at the crack tip under the stress($P_{max}=911.5MPa$) due to a rolling contact were analyzed for crack growth characteristics. As a result, the perpendicular crack was found to be more dangerous compared to the parallel one. It is found that in the wheel fatigue crack, parallel to the wheel tread surface, the crack with its length 2a = 2.4mm starts to propagate due to the fact that the effective stress intensity factor access to the threshold stress intensity factor($K_{th}=16.04MPa{\sqrt{m}}$) of the wheel.

• 한국토양환경학회지
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• 제4권1호
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• pp.35-47
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• 1999

구봉광산의 광미와 주변 밭과 논의 토양 및 하상퇴적물에서의 중금속과 시안의 분포 및 오염도에 대해 조사하였다. 광미 중의 As, Cd, Cu, Hg, Pb, Zn및 CN￣의 평균농도는 각각 6.93$\times$$10^{3}$, 56.9, 209, 5.03, 3.25$\times$$10^{3}$, 1.89$\times$$10^{3}$, 21mg/kg이었고 Kloke가 제안한 허용기준치를 이용하여 계산한 오염지수는 42~95이었으며 pH는 약알칼리성이었다. 광산과 인접한 밭 토양 중의 중금속과 시안 함량은 논 토양보다 높았다. 하상퇴적물 중의 중금속과 시안 함량은 광미 중의 분석치정도로 많이 검출되었다.

• 한국방사선학회논문지
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• 제8권7호
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• pp.443-447
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• 2014

토양 시료 중에 극미량의 $^{134}Cs$ 방사능 농도는 지각 기원자연방사성 핵종들에 의한 background의 영향 및 피크간의 중첩 및 간섭으로 구분하기가 어렵다. 감마선 분광학에서 참 피크의 식별은 피크의 모양이 대체로 Gaussian임을 고려하여 smoothing에 의해 통계적 요동을 감소시켜 보거나 피크의 폭이나 솟아오름의 정도를 검사하거나, 저에너지 tailing 현상에 대한 함수를 추가하거나 Gaussian 함수자체를 변형시켜 확인 할 수 있었다. 그러므로 스펙트럼 분석에 대한 정보와 지식이 필요할 것으로 사료된다.

• 대한화학회지
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• 제15권2호
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• pp.49-54
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• 1971

It is shown that the impurities of Cu(II), Pb(II), Zn(II) and Ag(I) in Bismuth metal and the components of Pb(II), Zn(II) and Sn(IV) in Bismuth alloy are separated into their components from each other by elutions through $3.14cm^2{\times}10cm$ cation exchange resin, $Dowex\;50w\;{\times}\;8$ (100~200 mesh), column with the mixed solutions of HAc and NaAc as the eluents. The elution curve of Fe(III) has a long tailing and is not separated quantitatively from Bi(III). The eluents used for this separation are as follows; 1M HAc + 0.1M NaAc (pH 3.36) for Fe(III) and Bi (III). 0.3M HAc + 0.3M NaAc (pH 4.70) for Cu(II), Pb(II) and Zn(II). 0.5M HAc + 0.5M NaAc (pH4.70) for Ag(I) and Sn(IV). The analysis of cations eluted are carried out by spectrophotometry and EDTA titrimetry. Their recoveries are more than 99%.

• Natural Product Sciences
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• 제27권4호
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• pp.264-273
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• 2021

Simultaneous quantification of multiple marker compounds in herbal medicine by high performance liquid chromatography (HPLC) analysis is still a challenge due to the complexity in various parameters to be considered and co-existing multi-components. As a case study, a reliable HPLC method for simultaneous quantification of paeoniflorin from Paeoniae Radix and decursin from Angelicae Gigantis Radix in various commercial herbal medicine was developed based on analytical quality by design (AQbD) strategy. As a first step, risk assessment was performed to select the critical method parameters (CMPs) which were decided as organic mobile phase ratio and column oven temperature. In order to evaluate the effect of the CMPs on critical method attributes (CMAs) of peak resolution and tailing, central composite design (CCD) was employed. The final chromatographic conditions were optimized as follows: column- C₁₈, 4.6 × 250 mm, 5 ㎛ particle size; mobile phase- A: acetonitrile, B: 0.1% acetic acid water; detection wavelength- 235 nm for paeoniflorin, 325 nm for decursin; column oven temperature- 25℃; flow rate- 1.0 mL/min; gradient mobile phase system as Time (min) : % A, 0:14, 25:14, 30:50, 60:50, 61:100, 65:100, 66:14, 75:14. The method was successfully validated according to the International Conference on Harmonization (ICH) guidelines and piloted for ten commercial herbal medicines.

• Bulletin of the Korean Chemical Society
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• 제34권6호
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• pp.1745-1750
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• 2013

A novel green aqueous mobile phase modified with room temperature ionic liquids (RTILs) was employed in the absence of volatile organic solvents or ion-pairing reagents to analyze thiamine, a very polar compound, by reverse phase high performance liquid chromatography (RP-HPLC). Due to its strongly hydrophilic nature, thiamine was eluted near the column dead time ($t_0$) using a mobile phase without adding RTILs or ion-pairing reagents, even if a 100% aqueous mobile phase, which has weak elution power under reverse phase conditions, was used. Thus, 1-ethyl-3-methyl-imidazolium hexafluorophosphate ([EMIM][$PF_6$]), which has the strongest chaotropic effect, was selected as a mobile phase additive to improve retention and avoid baseline disturbances at $t_0$. Various mobile phase parameters such as cation moiety, chaotropic anion moiety, pH and concentration of RTILs were optimized to determine thiamine at the proper retention time. Method validation was performed to assess linearity, intra- and inter-day accuracy and precision, recovery and repeatability; all results were found to be satisfactory. The developed method was also compared to the current official United States Pharmacopoeia (USP) and Korean Pharmacopoeia (KP) methods using an organic mobile phase containing an ionpairing reagent by means of evaluating various chromatographic parameters such as the capacity factor, theoretical plate number, peak asymmetry and tailing factor. The results indicated that the proposed method exhibited better efficiency of thiamine analysis than the official methods, and it was successfully applied to quantify thiamine in pharmaceutical preparations.

• 한국지구과학회지
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• 제37권4호
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• pp.211-217
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• 2016

낙동강에는 휴 폐광산의 관리 소홀로 인하여 광미, 광산폐기물, 침출수 등이 산재되어 있으며 여름철 집중 호우기 동안 이 같은 오염물들이 수계에 유입될 수 있다. 경상북도 봉화군 석포면에서 시작해 안동시 안동호 상류에 이르기까지 낙동강에 영향을 미칠 수 있는 광산은 총 105개로 금속광산 60개, 비금속 광산 45개에 달한다. 이를 확인하기 위해서 1년 동안 건기와 우기에 퇴적물, 배출수, 하천수를 채취하였다. 광산의 활동으로 낙동강 주변에 전반적으로 심각한 수준의 중금속 오염을 보이는 퇴적층이 산재해 있음을 확인했다(101개의 시료채취 지점 중 중금속농도를 바탕으로 한 오염지수 10 이상 지점 68개). 하천수 분석 결과에서는 승부, 삼보, 옥방, 장군 광산 등의 지류 시료에서 비소와 카드뮴 농도가 우기 때 증가하는 양상을 보였으며 광산의 배출수와 광미 퇴적층으로 인한 오염이 우려된다. 그러나 광미 퇴적층과 하천수의 화학조성만으로는 오염의 근원이 되는 광산의 유입정도를 분리해 내기 어렵고 이러한 문제는 광해 방지를 어렵게 한다. 광산 활동으로 인한 오염을 효과적으로 방지하기 위해서는 각 오염근원으로부터의 유입비를 분리해 낼 수 있어야 하는데, 그 방법으로써 안정동위원소를 사용하고 이를 통한 오염원 추적 분석 기술 개발에 대한 연구가 필요하다.