• 분석과학
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• 제22권4호
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• pp.326-335
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• 2009

계란 중에 잔류하는 6 종의 글루코코티코이드 약물을 극미량으로 분석하는 방법이 개발되었다. 동시분석을 위한 시료 추출방법과 정제방법을 확립하였으며 액체 크로마토그래프와 질량분석기의 최적화 조건을 확립하였으며, 글루코코티코이드를 분석하기 위해서는 5 g의 계란에 초산 완충용액을 사용하여 시료의 pH를 5.2로 조절한 후 효소 가수분해를 위해 Helilx pomatia를 사용하였다. 혼합물을 원심분리하여 20 mL n-헥산으로 두 번 추출하였다. 다시 HLB 카트리지에서 메탄올에 의한 추출이 이루어진 후 연속해서 실리카 카트리지에서 메탄올/에틸아세테이트를 사용하여 정제하였다. 분석물질은 역상 HPLC/ESI-MS/MS로 분석하였으며 ESI는 음이온 모드를 사용하였다. 검정곡선의 상관계수는 0.99 이상을 나타내었고 검출한계는 $0.09-0.17{\mu}g/kg$ 이었으며 회수율은 55.7-69.8%이었다. 바탕 계란 중에서 실험된 유효성 검증방법에 근거하여 확립된 분석법은 계란 중 글루코코티코이드를 수 ${\mu}g/kg$ 농도까지 검출하는데 사용될 수 있을 것이다.

• 청정기술
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• 제2권2호
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• pp.100-125
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• 1996

After recycle of spent materials has been optimised, there remains a proportion of waste which must be dealt with in the most environmentally friendly manner available. For materials such as municipal waste, clinical waste, toxic waste and special wastes such as tyres, incineration is often the most appropriate technology. The study of incineration must take a process system approach covering the following aspects: ${\bullet}$ Collection and blending of waste, ${\bullet}$ The two stage combustion process, ${\bullet}$ Quenching, scrubbing and polishing of the flue gases, ${\bullet}$ Dispersion of the flue gases and disposal of any solid or liquid effluent. The design of furnaces for the burning of a bed of material is being hampered by lack of an accurate mathematical model of the process and some semi-empirical correlations have to be used at present. The prediction of the incinerator gas phase flow is in a more advanced stage of development using computational fluid dynamics (CFD) analysis, although further validation data is still required. Unfortunately, it is not possible to scale down many aspects of waste incineration and tests on full scale incinerators are essencial. Thanks to a close relationship between SUWIC and Sheffield Heat&Power Ltd., an extended research programme has been carried out ar the Bernard Road Incinerator plant in Sheffield. This plant consists of two Municipal(35 MW) and two Clinical (5MW) Waste Incinerators which provide district heating for a large part of city. The heat is distributed as hot water to commercial, domestic ( >5000 dwelling) and industrial buildings through 30km of 14" pipes plus a smaller pipe distribution system. To improve the economics, a 6 MW generator is now being added to the system.

• Toxicological Research
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• 제31권3호
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• pp.265-271
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• 2015

This study was carried out to investigate contents of 8 polycyclic aromatic hydrocarbons (PAHs) from frequently consumed seafood and dairy products and to evaluate their chemical analysis methods. Samples were collected from markets of 9 cities in Korea chosen as the population reference and evaluated. The methodology involved saponification, extraction with n-hexane, clean-up on Sep-Pak silica cartridges and gas chromatograph-mass spectrometry analysis. Validation proceeded on 2 matrices. Recoveries for 8 PAHs ranged from 86.87 to 103.57%. The limit of detection (LOD) 8 PAHs was $0.04{\sim}0.20{\mu}g/kg$, and limit of quantification (LOQ) of 8 PAHs was $0.12{\sim}0.60{\mu}g/kg$. The mean concentration of benzo[a]pyrene (BaP) was $0.34{\mu}g/kg$ from seafood and $0.34{\mu}g/kg$ from dairy products. The total PAHs concentration was $1.06{\mu}g/kg$ in seafood and $1.52{\mu}g/kg$ in dairy products.

• 대한간호학회지
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• 제33권1호
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• pp.9-16
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• 2003

Purpose : The objective of this study was the development and validation of a scale to measure the self-care of patients with chronic obstructive pulmonary disease(COPD) in Korea. Method: Self-care scale was developed based on the self-care activities patients had to carry out in order to manage their COPD. The original scale contained 34 items rated along a five-point Likert scale and was reviewed by 18 professional nurses and 10 Korean patients with COPD for content validity. Subsequently, patients with COPD were asked to complete this 23-item scale and further tests were done with the 125 useable responses. Result: Factor analysis identified eight factors-'maintaining a clean air way', 'taking medication', 'support from family', 'preventing infection', 'managing symptoms', 'breathing exercising', and 'taking in nutrition'. The internal consistency of the total scale was Cronbach's α=0.7226. These eight factors explained 60.8% of total variance. There was correlation among Korean Self-Care Scale score, administration level, and knowledge level but there was no correlation to patients' satisfaction with medical services. Conclusion: The 23 item questionnaire positively identified 8 areas defined important for COPD patients. Further studies are required to see how these can be integrated into patient education.

• Journal of Information Processing Systems
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• 제15권3호
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• pp.694-706
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• 2019

In this study, we applied the long short-term memory (LSTM) model to classify the cryptocurrency price time series. We collected historic cryptocurrency price time series data and preprocessed them in order to make them clean for use as train and target data. After such preprocessing, the price time series data were systematically encoded into the three-dimensional price tensor representing the past price changes of cryptocurrencies. We also presented our LSTM model structure as well as how to use such price tensor as input data of the LSTM model. In particular, a grid search-based k-fold cross-validation technique was applied to find the most suitable LSTM model parameters. Lastly, through the comparison of the f1-score values, our study showed that the LSTM model outperforms the gradient boosting model, a general machine learning model known to have relatively good prediction performance, for the time series classification of the cryptocurrency price trend. With the LSTM model, we got a performance improvement of about 7% compared to using the GB model.

• 대한화장품학회지
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• 제38권1호
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• pp.33-41
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• 2012

네일락카와 헤어스프레이 같은 화장품에 존재하는 미량의 프탈레이트를 정량분석하기 위하여, 가스크로마토그래피와 질량분석기를 사용한 효과적이면서 환경친화적인 분석방법을 개발하였다. 이들 화장품들은 다량의 유기용매를 함유되어 프탈레이트를 분석하기 위하여 널리 사용되는 시료의 클린업 방법이 적합하지 않았다. 더군다나 미량의 프탈레이트 분석시에는 실험과정 중에서의 오염으로 인해 실제보다 높은 분석값을 산출하게 되는 경우가 매우 많다. 이에 정확한 함량분석 및 이차오염을 방지하기 위해 유기용매를 사용하여 시료를 직접 희석하는 시료 전처리를 적용하였다. 이 분석방법은 높은 정확성, 분석감도, 그리고 시료전처리를 간략히 할 수 있는 이점을 가진다. 화장품에서의 검출되는 빈도가 높고, 사람과 동물에 영향을 미치는 환경호르몬으로 보고되는 dibutyl phthalate (DBP)와 di (2-ethylhexyl) phthalate (DEHP) 두 종의 프탈레이트를 분석대상으로 선정하였다. 정량시 그 정확도 향상을 위해서 내부표준물질로 두 물질의 중수소치환체인 DBP-$d_4$,와 DEHP-$d_4$를 사용하였다. 시험법의 유효화를 시행한 결과 본 시험법이 ppm 농도의 프탈레이트 정량분석에 적합함을 확인하였으며, 네일락카와 헤어스프레이 제품에 약 $25{\mu}g/g$의 농도로 표준물질을 첨가하여 분석한 회수율은 95 - 106.1 % 범위였고, % 상대표준편차 값은 3.9 % 이하였다.

• 청정기술
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• 제26권1호
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• pp.55-64
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• 2020

재생에너지 3020 이행계획에 따라 재생에너지 발전 비중 증가에 대비해 잉여전력 저장 및 전력 공급 안정화 기술 필요성이 대두되고 있다. 이를 위해 수요 공급의 불균형으로 활용할 수 없는 전력을 수소 또는 메탄으로 전환하여 저장하는 Power-to-Gas 기술 개발이 활발히 진행되고 있다. 본 연구에서는 국내 실정을 반영한 Power-to-Gas 경제성분석을 수행하였다. 균등화 수소원가를 산정하기 위하여 Total revenue requirement 방법론을 활용하여 경제성 분석 방법론을 재정립하고, 국제에너지기구의 경제성 분석 결과를 통해 검증하였다. 연구결과 국내 기준 100 MW급 Power-to-Gas 시스템 균등화 수소원가는 kg당 8,344원으로 나타났다. 전기 비용, 수전해 장비 비용, 작동 연한에 따른 민감도 분석이 수행되었고, 재생에너지 이용 수소 생산비용과 천연가스 개질 수소 생산비용을 비교하여 경제성을 확보할 수 있는 조건을 제시하였다.

• Nuclear Engineering and Technology
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• 제52권6호
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• pp.1120-1130
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• 2020

The CREOLE experiment performed In the EOLE critical facility located In the Nuclear Center of CADARACHE - CEA have allowed us to get interesting and complete experimental information on the temperature effects in the light water reactor lattices. To analyze these experiments with accuracy an elaborate calculation scheme using the Monte Carlo method implemented in the MCNP6.1 code and the ENDF/B-VII.1 cross section library has been developed. We have used the ENDF/B-VII.1 data provided with the MCNP6.1.1 version in ACE format and the Makxsf utility to handle the data in the specific temperatures not available in the MCNP6.1.1 original library. The main purpose of this analysis is the qualification of the ENDF/B-VII.1 nuclear data for the prediction of the Reactivity Temperature Coefficient while ensuring the ability of the MCNP6.1 system to model such a complex experiment as CREOLE. We have analyzed the case of UO₂ lattice with 1166 ppm of boron in ordinary water moderator in specified temperatures. A detailed comparison of the calculated effective multiplication factors with the reference ones [1] in room temperature presented in this work shows a good agreement demonstrating the validation of our 3D calculation model. The discrepancies between calculations and the differential measurements of the Reactivity Temperature Coefficient for the analyzed configuration are relatively small: the maximum discrepancy doesn't exceed 1,1 pcm/℃. In addition to the analysis of direct differential measurements of the reactivity temperature coefficient performed in the poisoned UO₂ lattice configuration, we have also analyzed integral measurements in UO₂ clean lattice configuration using equivalency of the integral temperature reactivity worth with the driver core fuel reactivity worth and soluble boron reactivity worth. In this case both of the ENDF/B-VII.1 and JENDL.4 libraries were used in our analysis and the obtained results are very similar.

• 분석과학
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• 제28권5호
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• pp.309-316
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• 2015

본 연구에서는 ICP-MS의 혈장 중 극미량의 납 분석법을 검증하기 위하여 Class 1,000 이내의 환경조건을 확보한 후 특이성, 일내 및 일간 정확도, 정밀도, 검정곡선 등을 확인하였다. 청정실의 부유 분진량을 측정한 결과, 0.3 µm 크기는 0.3~62개, 0.5 µm 크기는 0.0~28.3 개로 총 부유분진량이 최대 90.3개로 요구 환경에 부합하였다. 우태아 혈청 공시료로 조제한 시료의 MDL (Method detection limit)은 1.77 ng/L이고, LOQ (Limit of quantification)값은 5.55 ng/L 이었다. 검정곡선은 y=1.09×10⁻³ x+4.88×10⁻²이었고, 상관계수 r=0.9999이었다. 분석법 확립을 위한 특이성, 일내 및 일간 정확성, 정밀성, 그리고 검정곡선을 확인한 결과 50 ng/L 이상에서 분석법 확인 기준에 적합하였다. 이를 토대로 분석한 일반인의 혈장 중 납 농도 평균은 55.4 ng/L 이었으며, 현직 근로자는 440 ng/L 이었고, 퇴직 근로자는 132 ng/L 이었다.

• 한국대기환경학회지
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• 제34권3호
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• pp.493-507
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• 2018

Due to high spatio-temporal variability of amount and optical/microphysical properties of atmospheric aerosols, satellite-based observations have been demanded for spatiotemporal monitoring the major aerosols. Observations of the heavy aerosol episodes and determination on the dominant aerosol types from a geostationary satellite can provide a chance to prepare in advance for harmful aerosol episodes as it can repeatedly monitor the temporal evolution. A new geostationary observation sensor, namely the Advanced Himawari Imager (AHI), onboard the Himawari-8 platform, has been observing high spatial and temporal images at sixteen wavelengths from 2016. Using observed spectral visible reflectance and infrared brightness temperature (BT), the algorithm to find major aerosol type such as volcanic ash (VA), desert dust (DD), polluted aerosol (PA), and clean aerosol (CA), was developed. RGB color composite image shows dusty, hazy, and cloudy area then it can be applied for comparing aerosol detection product (ADP). The CALIPSO level 2 vertical feature mask (VFM) data and MODIS level 2 aerosol product are used to be compared with the Himawari-8/AHI ADP. The VFM products can deliver nearly coincident dataset, but not many match-ups can be returned due to presence of clouds and very narrow swath. From the case study, the percent correct (PC) values acquired from this comparisons are 0.76 for DD, 0.99 for PA, 0.87 for CA, respectively. The MODIS L2 Aerosol products can deliver nearly coincident dataset with many collocated locations over ocean and land. Increased accuracy values were acquired in Asian region as POD=0.96 over land and 0.69 over ocean, which were comparable to full disc region as POD=0.93 over land and 0.48 over ocean. The Himawari-8/AHI ADP algorithm is going to be improved continuously as well as the validation efforts will be processed by comparing the larger number of collocation data with another satellite or ground based observation data.