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        검색결과 29

        22.
        2008.06 KCI 등재후보 구독 인증기관 무료, 개인회원 유료
        In this study, the performance of fast gas chromatography system was evaluated using VOC standards prepared in both liquid and gaseous phase. When the liquid‐phase VOC standards were analyzed by both direct injection and HS‐SPME method, all the chromatographic separation was completed within 4 minutes. The calibration experiments were conducted further using gaseous standard of BTX. The calibration results derived by direct injection method generally showed good linearities, regardless of phases, while it was not the case for HS‐SPME method. In case of liquid‐phase standard, MDL values for direct injection and HSSPME method were calculated in the range of 0.07~0.19 to 0.63~3.76 ng, respectively. In contrast, MDL values for gaseous standard were 0.27~0.45 and 1.94~6.90, respectively. The reproducibility of our method, when expressed in terms RSE, showed above 5 %. When the sensitivity of different techniques is compared, the calibration slope values of BTX decreased on the order: direct injection of liquid‐phase standard > HSSPME method of liquid‐phase standard > direct injection of gaseous standard > HS‐SPME method of gaseous standard. Although fast GC is very efficient to reduce the total running time significantly, extended studies are desirable to improve its reproducibility.
        5,100원
        25.
        2022.12 KCI 등재 서비스 종료(열람 제한)
        지질과학 분야에서 암석의 생성 시기, 지각과 맨틀 진화연구의 기초자료로 활용되는 Sr 동위원소비는 열이온화 질량분석기(thermal ionization mass spectrometry, TIMS) 혹은 다검출기 유도결합 플라즈마 질량분 석기(multi-collector plasma ionization mass spectrometry, MC-ICP-MS)와 같은 질량분석기를 이용하여 측정할 수 있다. 이 기술보고에서는, Sr 동위원소비 측정시, 원소의 불완전한 화학적 분리가 Sr 동위원소비의 참값 (true value)에 어떤 영향을 미치는지를 비교하였다. 실험에는 상업용 레진, NBS987(NIST SRM987) Sr 동위 원소 표준물질 그리고 일본지질조사소의 암석표준시료 JG1a, JB3, JA1를 이용하였다. 비교실험 결과, NBS987 Sr 동위원소 표준시료, 일본지질조사소의 암석표준시료 JG1a, JB3, JA1 모두 불완전한 분리에 의해 Rb이 남 아있는 경우 87Sr/86Sr의 측정값이 변하는 것이 명확하게 관찰된다. 이는 질량분석기 특히 MC-ICP-MS로 동위 원소비를 측정하고자 하는 경우, 동종동위원소의 간섭에 대한 보정에도 불구하고 측정값은 참값에서 벗어나 므로 완전한 분리가 중요한 인자임을 지시해준다. 그러므로 MC-ICP-MS를 이용한 Sr 동위원소비 측정결과를 보고할 때는, 동종동위원소에 의한 영향을 판단할 수 있도록 Sr의 동위원소 전체의 측정강도와 더불어 85Rb의 측정강도도 함께 보고돼야 할 것이다.
        26.
        2015.03 KCI 등재 서비스 종료(열람 제한)
        In order to measure the Radionuclides and Concentration, the directly grinded land samples (river soil, pine leaves and mugwort) among the environment samples around the nuclear power plant were filled in a 450 mL Marinelli beaker and weighed to obtain the dry mass ratio of the samples. Then the background and land samples were measured for 80,000 sec. The analysis of the collected land samples showed that most of them contained less radiation nuclide than the detection minimum limit in the ‘Ministry of Education, Science and Technology Public Notice No. 2010-32.’In others, the natural radionuclides 40K were detected. Of the products of nuclear reaction discharged by a nuclear reaction, 134Cs and 137Cs are more easily detected, and their discharge sources can be traced using the relative ratio. Although the radioactive concentration in the vicinity of Kori Nuclear Power Plant, which is more than 1,100km away from Fukushima, the Japanese nuclear accident site, continuous monitoring is needed as the radionuclides can still be accumulated in the soil or animals and plants.
        27.
        2014.12 KCI 등재 서비스 종료(열람 제한)
        In a mercury leaching test for waste using the Korean Standard Method (ES 06404.1), the pre-treatment process of an eluate is very complicated with a high possibility of contamination and low mercury recovery rate. It is also difficult to analyze multiple samples in a short time and the process generates experimental wastes. Accordingly, a direct mercury analyzer (DMA) applying thermal decomposition gold-amalgamation analysis has been recently used. The method shows a relatively high recovery rate for solid samples without complicated pre-treatment and it can be applied to both liquid and solid samples as the EPA method 7473 does. In order to use the auto-sampler in DMA for analyzing many elution samples from waste, this study checked recovery rates depending on acid solutions and additives during continuous analysis. The result showed a significant drop in recovery and precision except for an L-cysteine added sample. Considering commonly used acid-treatment of wastes, three types of acid solutions (nitrate, hydrochloric acid and sulfate) were chosen for analysis, and precision and accuracy were relatively high in nitric acid solution. It has been determined that accuracy and precision improved when 0.01% L-cysteine was added as an additive and this reduced the impact of continuous measurement. Therefore, during analysis of liquid samples or eluted samples using DMA continuously, introducing suitable additives is necessary depending on pre-treatment method in order to improve accuracy and precision in the analysis of mercury.
        28.
        2014.01 KCI 등재 서비스 종료(열람 제한)
        Quality of GHG emission from solid waste disposal depends on level of activity data. Activity data of solid wastedisposal is mass of waste disposal and waste composition. Waste composition is one of the main factors influencingemissions from solid waste disposal. According to GHG target management in Korea, uncertainty of activity datadetermined by level of tier. We suggest minimum sample number for analysis of waste composition. In result, we suggestto revise the guideline for GHG target management that minimum sample number for analysis of waste compositionmust be over 73 times during 3 years for total uncertainty of waste composition must be less than or equal to 7.5%(Tier 1 level).
        29.
        2013.06 KCI 등재후보 서비스 종료(열람 제한)
        한국어 높임 표현은 외국인학생들이 습득하기 매우 어려워 하는 표현 중 하나이다. 잘못 사용할 경우 한국인 청자에게 무례함 내지는 불쾌감을 불러일으킬 수 있다는 점에서 볼 때 정확한 교육이 필요하며 한국어 교육에서 꼭 다루어야 할 중요한 주제이다. 본고에서는 먼저 한국어 교육에서 높임 표현에 대한 앞선 연구들을 살펴본 후 화용론에서의 이론적 배경과 높임 표현 분류를 살펴보고 이를 바탕으로 본 연구의 기틀을 마련하고자 한다. 실제 교실에서 한국어 수업을 전사한 내용을 토대로 한국어 교사와 학습자들의 높임 표현 사용 양상을 살펴보고자 한다. 그리고 교실에서 교사가 높임 표현을 발화할 때의 정확성과 그 사용 빈도가 학습자들에게 어떤 영향이 미치는지도 밝히고자 한다. 본 연구 마지막 부분에서 예상과 반대로 나타나는 분석 결과의 원인도 밝혔다. 그리고 본 연구의 한계점도 제시하였다.
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