• Bulletin of the Korean Chemical Society
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• 제27권9호
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• pp.1315-1322
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• 2006

The following study describes the gas chromatography-mass spectrometry (GC-MS) based screening and confirmation analysis of urinary androgenic steroids. Four commercially available solid-phase extraction (SPE) cartridges, Serdolit PAD-1, Sep-pak $C_{18}$, amino-propyl, and Oasis HLB, and three different extractive organic solvents, diethyl ether, methyl tert-butyl ether (MTBE), and n-pentane, were tested for sample preparation. Overall, Oasis HLB combined with MTBE extraction provided the highest recoveries in 39 of 46 total androgenic steroids examined and it showed a good extraction yield (>82.1%) for polar steroids, such as metabolites of fluoxymesterone, oxandrolone, and stanozolol, which gave a poor recovery in both n-pentane (9.2-64.3%) and diethyl ether (22.2-73.6%) extractions. All SPE sorbents tested showed potential, because they were efficient in extraction for most or selective steroids. When applied to positive urine samples based on the results obtained, the present method allowed selective and sensitive analysis for detection of urinary androgenic steroids. The experiments showed that the high-resolution MS method is clearly more efficient than the low-resolution MS technique for the detection of many urinary steroids. However, comprehensive sample clean-up procedures also might be needed especially in confirmation analysis to increase detectability.

• 한국대기환경학회지
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• 제20권1호
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• pp.17-31
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• 2004

The subway play an important part in serious traffic problems. However, because subway system is a closed environment, many serious air pollution problems occurred in subway stations and injured passenger's health. Therefor, it is a necessary to identify sources and to estimate pollutant sources in order to protect passenger's health and to keep clean subway environment. The purpose of this study was to analyze a air quality in the subway stations and to apply a new receptor methodology for quantitatively estimate of PM10 sources. In this study, the size distributions of particulate matters has been measured by using Aerosizer LD (U.S.A., API, Inc.). It's real time measurement capability of time-of-flight technique offers a significant advantage of user convenience and air pollution management. Also, the mass concentrations of PM 10 has been measured by using mini-vol portable sampler (U.S.A., Airmetrics Co.). The sampling performed in Seoul subway stations during the period of February 2000 and April 2000. The number distribution data used in this study consisted of 26 raw data sets in the Jongno-sam-ga station. Correlation Analysis can be used in subway stations for source separation and identification. Then, number contribution from each source is determined by the particle number balance (PNB). The mass concentration data used in this study consisted of 31 raw data in the 8 different stations. The mass contributions of PM10 sources in the concourse by using PMF/CMB model.

• 한국해양공학회지
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• 제25권2호
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• pp.1-6
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• 2011

Vibration-based Structural Health Monitoring (SHM) systems use field measurements of operational signals, which are distorted by noise from many sources. Reducing this noise allows a more accurate assessment of the original "clean" signal and improves analysis results. The implementation of a noise reduction methodology for the Modal Distribution Method (MDM) is reported here. The spectral subtraction method is a popular broadband noise reduction technique used in speech signal processing. Its basic principle is to subtract the magnitude of the noise from the total noisy signal in the frequency domain. The underlying assumption of the method is that noise is additive and uncorrelated with the signal. In speech signal processing, noise can be measured when there is no signal. In the MDM, however, the magnitude of the noise profile can be estimated only from the magnitude of the Power Spectral Density (PSD) at higher frequencies than the frequency range of the true signal associated with structural vibrations under the additional assumption of white noise. The implementation of the spectral subtraction method to MDM may decrease the energy of the individual mode. In this work, a modification of the spectral subtraction method is introduced that enables the conservation of the energies of individual modes. The main difference is that any (negative) bars with a height below zero after subtraction are set to the absolute value of their height. Both noise reduction methods are implemented in the MDM, and an application example is presented that demonstrates its effectiveness when used with a signal corrupted by noise.

• 천문학회보
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• 제38권2호
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• pp.58.2-58.2
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• 2013

Both peculiar velocities and errors in the assumed redshift-distance relation ("Alcock-Paczynski effect") generate correlations between clustering amplitude and orientation with respect to the line-of-sight. In this talk we propose a novel technique to extract the Alcock-Paczynski, geometric, distortion information from the anisotropic clustering of galaxies in 3-dimensional redshift space while minimizing non-linear clustering and peculiar velocity effects. We capitalize on the recent, large dataset from the Sloan Digital Sky Survey III (SDSS-III), which provides a large comoving sample of the universe out to high redshift. We focus our analysis on the Baryon Oscillation Spectroscopic Survey (BOSS) constant mass (CMASS) sample of 549,005 bright galaxies in the redshift range 0.43

• Journal of Advanced Marine Engineering and Technology
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• 제21권5호
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• pp.564-570
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• 1997

The most important factor for the desalination system is the fresh water production cost dependent upon the possible energy source which should be obtained easily and with low price. Recently in Korea the demand of LNG, as a cheap and clean energy which does not cause an environmental problem, has sharply been increased. In general, LNG is storaged in a tank as a liquid state below -162 'C. When it is serviced, however, the LNG absorbs energy from a heating source and transforms to the gaseous state with high pressure. During this process a huge amount of cold energy accumulated in LNG is wasted. This waste cold energy can be utilized for producing fresh water from sea water using a sea water freezing desalination system. In order to develop a sea water freezing desalination system and to establish its design technique, a qualitative and quantitative data regarding the freezing behavior of sea water is needed in advance. The goal of this study, therefore, are to reveal the freezing mechanism of sea water, to measure the freezing rate, and to investigate the freezing heat-transfer characteristics. The experimental results help to provide a general understanding of the sea water freezing behavior in a Rectangular vessel cooled from below.

• 한국식생활문화학회지
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• 제27권6호
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• pp.636-645
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• 2012

The purpose of this study is to investigate factors influencing dietary satisfaction, and their perceived importance and performance, in North Korean refugees according to age. Questionnaires were completed by 220 North Korean refugees and data was analyzed with SPSS software. From our study we determined that fresh food, clean dishes, and proper vegetable oil are of high importance but considered poorly performed. 'Taste' and 'comfort' were factors with low importance but considered well-performed. The IPA technique proved that 8 items including Q4, Q5, Q6, Q7, Q8, Q9, Q11, Q13 were in 'Doing great, keep it up' and no items that got high importance and low performance were in 'Focus here'. North Korean refugees like Korean food more than Chinese, Japanese, and Western food. They specifically want to learn how to cook Korean casseroles, soups, and side dishes(e.g. Myeolchibokkum, Kongjorim). The North Korean refugees who resided in South Korea under a year have difficulties in understanding menus and Western table manners.

• 한국해양환경ㆍ에너지학회지
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• 제5권2호
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• pp.28-34
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• 2002

본 연구는 수거된 해양폐기물을 원료로 이용하여 폐기물연료(RDF : Refuse Derived Fuel)를 제조하는 공정 개발을 목적으로 하고 있으며, 산업용 연료로서의 활용 가능성을 확인하기 제조된 RDF의 물성분석을 분석하였다. 해양폐기물은 로우프에서의 납제거와 파쇄 그리고 해저 슬러지의 세척과 같은 전처리, 그리고 가연성분의 입자화 공정을 통하여 해양폐기물이 에너지로 변환하는 것이 가능하게 되었다. 이와 같은 해양폐기물 자원화 공정은 수거 폐기물의 환경적 처리는 물론 대체에너지 확보의 측면에서 매우 유익한 것으로 사료된다.

• 농촌계획
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• 제23권2호
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• pp.29-42
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• 2017

Sustainable development is no longer an option, but a requirement. Under this awareness, UN adopted 17 goals for a new sustainable development agenda on September 2015, named 'Sustainable Development Goals(SDGs)'. The Korean Society of Rural Planning(KSRP) is established on July 1994 for the sustainable development of rural areas. On the purpose to quantitatively analyze the research trend of KSRP's publications with the viewpoint of SDGs, the qualitative documents of 17 SDGs and 771 publications were mathematically transformed into vectors and the similarity was numerically measured with the 'Vector Space Model(VSM)'. The results show that 'Sustainable cities and communities(SDG 11)', 'Zero hunger(SDG 2)', 'Life on land(SDG 15)' and 'Responsible consumption and production(SDG 12)' have strong relationships with KSRP, while those of 'Affordable and clean energy(SDG 7)', 'Peace, justice and strong institution(SDG 16)' and 'Gender equality(SDG 5)' are weak. It is also found that the relationships of KSRP publications with 'energy' and 'climate change' issues(SDG 7, 13) were greatly increased during the period of 1995-2016, in spite of their weak relationships.

• 한국신뢰성학회지:신뢰성응용연구
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• 제5권2호
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• pp.241-259
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• 2005

The environmental problem is a main subject of the 21C and an environment destruction phenomenon by various kinds of environmental materials is reaching serious level. Nations to be classified as the environmental developed country, are born again environmental rich country. And they earn a large income by trade Every kind environmental resource in an international commercial transaction. Especially, the study that a reliability assessment method to prevent to reliability problem to be happened when the solder lead(lead-free solder), non-cd component, non-bromide component(without the polybrominated biphenyls(PBB) and polybrominated diphenyl ethers(PBDE))and hexavalent chromium(Cr VI) clearance component and mercury-free applied to electronic equipment is progressed. As the result of the study for applying of a reliability assessment technique of lead-free solder that recognized the most of urgent problem at the company, combination accelerated life test could taken by adding and appling the part of a humidity acceleration part to Eyring Model which is proposed by R.E.Thomas. The reliability assessment methods study of PWB clean environmental materials is expected to respond to a reliability elevation and environmental material regulation policy spreading all over the world by beginning form Europe.

• 한국연초학회지
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• 제36권1호
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• pp.26-33
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• 2014

Simultaneous determination of crop protection agents(CPAs) in food are done with multi-residue methods, which are composed of sample clean-up, concentration, chromatographic separation and detection. Stir Bar Sorptive Extraction(SBSE) technique is used for sample preparation of various analytes in several fields. The aim of this study was to develop a sensitive and fast method based on SBSE followed by thermal desorption - gas chromatography - mass spectrometry(TD - GC/MS) to determine CPAs in tobacco sample. For the analysis of tobacco sample prior to the SBSE method, solvent extraction or ultrasound-assisted solvent extraction was performed. methanol was used as the extraction solvent. The extract was then diluted with water. Finally, the sample was subjected to SBSE. A method for fast screening of crop protection agents in tobacco using SBSE-TD - GC/MS has been developed. About 17 CPAs including organochlorine, organophosphorous and others were identified and quantified. This method showed good linearity and high sensitivity for most of the target CPAs. The method was applied to the determination of CPAs at ng/mL levels in tobacco sample. This method is simple, rapid and may be applied in detection of other components.