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        검색결과 12

        1.
        2023.05 구독 인증기관·개인회원 무료
        During the decommissioning of a nuclear power plant, the structures must be dismantled to a disposal size. Thermal cutting methods are used to reduce metal structures to a disposal size. When metal is cut using thermal cutting methods, aerosols of 1 μm or less are generated. To protect workers from aerosols in the work environment during cutting, it is necessary to understand the characteristics of the aerosols generated during the cutting process. In this study, changes in aerosol characteristics in the working environment were observed during metal thermal cutting. The cutting was done using the plasma arc cutting method. To simulate the aerosols generated during metal cutting in the decommissioning of a nuclear power plant, a non-radioactive stainless steel plate with a thickness of 20 mm was cut. The cutting condition was set to plasma current: 80 A cutting speed: 100 mm/min. The aerosols generated during cutting were measured using a highresolution aerosol measurement device called HR-ELPI+ (Dekati®). The HR-ELPI+ is an instrument that can measure the range of aerodynamic diameter from 0.006 μm to 10 μm divided into 500 channels. Using the HR-ELPI+, the number concentration of aerosols generated during the cutting process was measured in real-time. We measured the aerosols generated during cutting at regular intervals from the beginning of cutting. The analyzed aerosol concentration increased almost 10 times, from 5.22×106 [1/cm3] at the start of cutting to 6.03×107 [1/cm3] at the end. To investigate the characteristics of the distribution, we calculated the Count Median Aerodynamic Diameter (CMAD), which showed that the overall diameter of the aerosol increased from 0.0848 μm at the start of cutting to 0.1247 μm at the end of the cutting. The calculation results were compared with the concentration by diameter over time. During the cutting process, particles with a diameter of 0.06 μm or smaller were continuously measured. In comparison, particles with a diameter of 0.2 μm or larger were found to increase in concentration after a certain time following the start of cutting. In addition, when the aerosol was measured after the cutting process had ended, particles with a diameter of 0.06 μm or less, which were measured during cutting, were hardly detected. These results show that the nucleation-sized aerosols are generated during the cutting process, which can explain the measurement of small particles at the beginning of cutting. In addition, it can be speculated that the generated aerosols undergo a process of growth by contact with the atmosphere. This study presents the results of real-time aerosol analysis during the plasma arc cutting of stainless steel. This study shows the generation of nucleation-sized particles at the beginning of the cutting process and the subsequent increase in the aerosol particle size over time at the worksite. The analysis results can characterize the size of aerosol particles that workers may inhale during the dismantling of nuclear power plants.
        8.
        2020.04 KCI 등재 구독 인증기관 무료, 개인회원 유료
        본 연구는 불법적으로 수산물에 사용될 수 있는 염료 18종에 대한 안전관리 강화를 위해 정량 및 정성 분석이 가능한 LC-MS/MS를 적용하여 검증하기 위해 수행되었다 . 확립된 시험법은 CODEX CAC/GL-71 가이드라인에 따라 직선성, 정밀성 , 정량한계 및 회수율 등을 통해 유효성을 확인하였다 . 대상시료에 1% 아세트산을 함유한 아세토니트릴로 추출 후 C18 과 PSA로 정제하였다 . 본 실험에서 정량한계는 0.002 mg/kg 수준으로 정량한계를 포함한 농도에 따라 검량선을 작성하였고 모두 0.98 이상의 직선성을 확인하였다 . 또한 정확성은 63%-112% 이고, 정밀도는 15% 이하로 재현성이 우수하였다 . 국내 유통 중인 수산물 124 건을 수거하여 개발된 분석법의 적용성 검증과 안전성을 확인하고자 잔류실태조사를 실시 하였고 그 결과 7건이 미량으로 검출 되었고 부적합은 없었다 . 확립된 시험법은 수산물 안전관리에 활용할 수 있을 것으로 사료되는 바이다 .
        4,000원
        9.
        2019.12 KCI 등재 SCOPUS 구독 인증기관 무료, 개인회원 유료
        We present the results of near-infrared imaging observations of the galaxy overdensity around the z = 1.44 radio-loud active galactic nucleus (AGN) 6CE1100+3505, which was carried out with the purpose of sampling the redshifted Hα emission from the actively star-forming galaxies that could constitute the overdensity. The existence of the structure around this AGN was spectroscopically confirmed by previous grism observations which are however limited to the central region. Using the CH4Off narrow/medium-band and H broad band filters in the Wide Infrared Camera (WIRCam) on the Canada-France-Hawaii Telescope (CFHT), we constructed a sample of objects that show a flux excess in the CH4Off band due to line emission. The emission line flux is ∼ 4.9 × 10−16 erg s−1 cm−2 , corresponding to a star formation rate (SFR) of ∼ 50 M⊙ yr−1 for galaxies at redshifts z ∼ 1.4. None of the galaxies with medium-band flux excess is located within 1 Mpc from the central AGN, and there is no evidence that the selected galaxies are associated with the proposed cluster. Along with the star formation quenching near the center that was found from the previous grism observations, the lack of extreme starbursts in the structure suggests that at z ∼ 1.4, overdense regions are no longer favorable locations for vigorous star formation.
        4,000원
        11.
        2018.07 구독 인증기관·개인회원 무료
        Functional magnetic resonance imaging (fMRI) is one of the best available devices that can record the activities of living human brain non-invasively. Its precision and high spatial resolution is matched by none other methodology. The entry barrier to fMRI research is exceptionally high. fMRI has widely been used in medical and scientific research, but its application to marketing research has been limited because of two important reasons. First, the cost problem. The MR scanning devices often cost multi-million dollars and using fMRI for marketing research can be costly. Second, analyzing data from fMRI study is another formidable task. fMRI measures the brain’s hemodynamic activities using voxel as a measuring unit; Voxels are often a cubic with 2 to 3 millimeters on one side. Since a typical adult brain represents over one million voxels in one scan volume, and each scan generally has 2 to 3 seconds of interval time, one experimental block of 40 seconds, for example, will create over 40 million data points. Compared to a typical marketing research data which in general have two dimensions (2d) of rows and columns, fMRI data is inherently 4d with added dimensions of voxel and time. Furthermore, the fMRI signal is sensitive to various sources of noises. In this talk, we offer support for marketing researchers who want to explore fMRI method for their research in the future. First, we discuss issues related to experimental design for fMRI experiments. We explain preprocessing steps that are recommended for fMRI data and show how to apply statistical methods to make inferences that can increase internal validity. Then, we will explicate how to apply big data analytics to fMRI data during this talk to find deep insights into customer’s brains. A real neuromarketing fMRI data will be used to break down the steps for fMRI research and data analytics. Finally, we will open a discussion to discover future research opportunities for marketing research using fMRI. The purpose of this talk is to lower the entry barrier of fMRI method in neuromarketing research so that more people in the marketing field can benefit from the most advanced scientific achievement of our time and discover deepest insights into our customers.
        12.
        2016.10 KCI 등재 구독 인증기관 무료, 개인회원 유료
        It has been reported that the increased uric acid level is associated with metabolic syndrome risk factors in both male and female. However, there has not been enough studies to investigate gender differences of this association in Korea. To evaluate relation between serum uric acids and metabolic syndrome markers, anthropometric and biochemical analyses data was obtained from National Health Examination 2005 and 5,523 (M=3,097; F=2,426) data was analyzed. Results by quartile of serum uric acid levels in females showed that increased serum uric acid level was associated with elevated levels of total-. LDL-cholesterol, and triglycerides, whereas association between serum uric acid and total cholesterol levels was not observed in male subjects. In both female and male, higher quartile of serum uric acid level were linked with lower levels of HDL-cholesterol. In regression analysis, association of serum uric acid levels with fasting glucose levels was significant in female subjects only. In conclusion, higher serum uric acid levels were associated with metabolic syndrome indices, however gender differences were existed for total cholesterol.
        4,000원