• Tuberculosis and Respiratory Diseases
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• 제47권3호
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• pp.374-382
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• 1999

연구배경: 자연기흉은 임상에서 흔히 접하는데도 불구하고 기흉의 위험인자, 재발율, 임상양상, 치료에 대한 반응과 예후와의 관계를 조사한 연구는 드물다. 방법: 경북대학교병원에서 1996년 1월부터 1997년 12월까지 자연기흉으로 진단받은 225예를 대상으로 기흉의 크기, 폐허탈의 분포, 흉관삽관술 시행빈도 등을 $17{\pm}7.8$개월 추적기간 동안 재발율과 재발의 위험인자를 조사하였다. 결과: 원발성과 자연기흉은 저체중인 환자가 많았으며, 홉연력은 속발성 자연기흉에서 유의하게 많았다(p<0.05). 속발성 자연기흉의 기저질환은 비활동성 폐결핵이 68%로 가장 많았고, 활동성 폐결핵 12.4%, 만성폐쇄성폐질환 11.3% 순이었다. 기흉의 기왕력은 원발성 자연기흉의 경우 28.9%에서, 그리고 속발성 자연기흉의 경우는 25.8%에서 있었다. 폐허탈의 분포는 속발성에서 원발성 자연기흉에 비해 국소형이 유의하게 많았다(p<0.05). 흉관삽관을 시행한 경우는 원발성과 속발성 자연기흉에서 각각 96.8%와 97.9%였으며, 추가적인 흉관 삽관이 필요했던 경우는 원발성 6.4%와 속발성 18.0%로 속발성 자연기흉에서 유의하게 많았다 (p<0.05); 흉관 유치기간은 원발성의 경우 $7.5{\pm}6.57$일인데 비해 속발성은 $18.2{\pm}19.59$일로 속발성 자연기흉에서 유의하게 길었다(p<0.05). 수술적 치료는 원발성 자연기흉의 22.7%, 그리고 속발성 자연기흉의 10.3%에서 시행하였으며, 수술 원발성의 경우 기흉이 기왕력이 있는 경우가 가장 많은 반면 속발성의 경우는 치료실패가 가장 많았다. 보존적인 치료를 방은 경우 재발율은 원발성의 경우 16.5%, 11.8%였으며, 원발성 자연기흉의 재발율은 남자, 흡연자, 저체중에서 높았다. 결론 : 자연기흉의 재발율을 감소시키기 위해서는 수술적 치료 등의 보다 적극적인 치료가 필요할 것으로 생각된다.

• 환경영향평가
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• 제19권3호
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• pp.323-333
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• 2010

$PM_{10}$ mass were measured in Gwaebeopdong (inland) and Dongsamdong (seashore) of Busan in summer and fall, 2007 and the 24-hour averaged samples were analyzed to investigate temporal and spatial variability of metallic elements and water-soluble ions in $PM_{10}$. Overall average concentrations of $PM_{10}$ mass during the study period were 72.7 ${\mu}g/M^3$ and 64.3 ${\mu}g/M^3$ in Gwaebeopdong and Dongsamdong, respectively. As for metal elements, averaged concentrations of crustal components, Ca, Fe, K, Mn, and Ti, in Gwaebeopdong exhibited enhancement relative to Dongsamdong. Non-crustal elements, Pb and Cu, displayed elevated levels in Gwaebeopdong while Ni and Zn were observed to be high in Dongsamdong. Averaged nitrate concentration in Gwaebeopdong (6.36 ${\mu}g/M^3$) was greater than in Dongsamdong(5.68 ${\mu}g/M^3$) and both areas had higher level of nitrate in summer than in fall. Averaged sulfate concentrations in Dongsamdong (25.4%) exhibited elevated level relative to Gwaebeopdong (19.4%). Overall average contribution of water-soluble ions to $PM_{10}$ in Dongsamdong (47.5%) was higher than in Gwaebeopdong (37.8%). The average mass fractions of secondary ions in $PM_{10}$ were elevated in Dongsamdong (37.1%) as compared to Gwaebeopdong (31.4%). Equivalent ratio of [${SO_4}^{2-}/NO_3{^-}$] was seen to be lower in Gwaebeopdong (1.39) than that in Dongsamdong (1.79) and consistently higher in summer than in fall for both areas.

• Asian Journal of Atmospheric Environment
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• 제8권3호
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• pp.126-139
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• 2014

In order to estimate the influence of sources on $PM_{2.5}$ in the industrial area of Japan, we carried out a source analysis using chemical component data of $PM_{2.5}$. $PM_{2.5}$ samples were collected intermittently at an industrial area in Japan from July 2010 to November 2012. Water soluble ions ($Cl^-$, $NO_3{^-}$, $SO{_4}^{2-}$, $Na^+$,$NH_4{^+}$, $K^+$, $Mg^{2+}$, $Ca^{2+}$), elements (Al, K, Ca, Ti, V, Cr, Mn, Fe, Ni, Cu, Zn, As, Cd, Sb, Pb), and carbonaceous species (OC, EC) of the $PM_{2.5}$ (a total of 198 samples) were analyzed. Positive Matrix Factorization (PMF) model was applied to the data of those chemical components to identify the source of $PM_{2.5}$. At this observation site, nine factors were extracted. The major contributors of $PM_{2.5}$ were secondary sulfate 1, in which loading factors of $SO{_4}^{2-}$ and $NH_4{^+}$ were large (percentage source contribution: 20.9%), traffic, in which loading factors of OC (organic carbon) and EC (elemental carbon) were large (20.8%), secondary sulfate 2, in which loading factors of K and $SO{_4}^{2-}$ were large (8.0%), steel mills (7.8%), secondary chloride and nitrate (7.0%), soil (5.0%), heavy oil combustion (3.8%), sea salt (3.8%), and coal combustion (2.3%). The conditional probability function (CPF) and the potential source contribution function (PSCF) were carried out to examine the influence of a regional source and a broad-based source, respectively. CPF results supported local source influences such as steel mills, sea salt, traffic, coal combustion, and heavy oil combustion. PSCF results suggested that ships in the East China Sea, an industrial area of the east coastal region of China, and an active volcano in the Kyushu region of Japan were potential regional sources of secondary sulfate 1. Secondary sulfate 2 was affected by the burning of biomass fields and by coal combustion in Chinese urban areas such as Beijing, Hebei, and western Inner Mongolia. Source characterization using continuous data from one site showed a potential source representing fossil fuel combustion is affected both by regional and broad-based sources.

• 한국입자에어로졸학회지
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• 제15권3호
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• pp.91-104
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• 2019

In this study, hourly measurements of $PM_{2.5}$ and its major chemical constituents such as organic and elemental carbon (OC and EC), and ionic species were made between January 15 and February 10, 2018 at the air pollution intensive monitering station in Gwangju. In addition, 24-hr integrated $PM_{2.5}$ samples were collected at the same site and analyzed for OC, EC, water-soluble OC (WSOC), humic-like substance (HULIS), and ionic species. Over the whole study period, the organic aerosols (=$1.6{\times}OC$) and $NO_3{^-}$ concentrations contributed 26.6% and 21.0% to $PM_{2.5}$, respectively. OC and EC concentrations were mainly attributed to traffic emissions with some contribution from biomass burning emissions. Moreover, strong correlations of OC with WSOC, HULIS, and $NO_3{^-}$ suggest that some of the organic aerosols were likely formed through atmospheric oxidation processes of hydrocarbon compounds from traffic emissions. For the period between January 18 and 22 when $PM_{2.5}$ pollution episode occurred, concentrations of three secondary ionic species ($=SO{_4}^{2-}+NO_3{^-}+NH_4{^+}$) and organic matter contributed on average 50.8 and 20.1% of $PM_{2.5}$, respectively, with the highest contribution from $NO_3{^-}$. Synoptic charts, air mass backward trajectories, and local meteorological conditions supported that high $PM_{2.5}$ pollution was resulted from long-range transport of haze particles lingering over northeastern China, accumulation of local emissions, and local production of secondary aerosols. During the $PM_{2.5}$ pollution episode, enhanced $SO{_4}^{2-}$ was more due to the long-range transport of aerosol particles from China rather than local secondary production from $SO_2$. Increasing rate in $NO_3{^-}$ was substantially greater than $NO_2$ and $SO{_4}^{2-}$ increasing rates, suggesting that the increased concentration of $NO_3{^-}$ during the pollution episode was attributed to enhanced formation of local $NO_3{^-}$ through heterogenous reactions of $NO_2$, rather than impact by long-range transportation from China.

• 한국조리학회지
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• 제21권2호
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• pp.1-10
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• 2015

본 연구에서는 조미김 식품제조 가공 업소에서 제조한 조미김을 대상으로 주요 원료 및 제조공정별 생물학적 위해요소분석을 실시하여 생물학적 중요관리점(CCP)을 파악하고, 이를 관리하고 모니터링하기 위한 한계기준을 설정하여 HACCP Plan을 제시하고자 한다. 본 연구 결과, 일반세균수는 2차 가열공정 이전에서는 $10^3{\sim}10^4CFU/g$의 높은 수준으로 검출되었으나, 2차 가열 이후에서는 $1.0{\times}10CFU/g$ 미만으로 검출되었다. 조미김의 제조공정별 병원성미생물 분석결과, 모든 제조공정에서 검출되지 않았다. 이와 같은 결과로 조미김의 제조 유통시 CCP는 2차 가열 과정으로 결정되었다. 가열온도를 $170{\pm}5^{\circ}C$, $200{\pm}0.5^{\circ}C$, $230{\pm}5^{\circ}C$로 하고, 각각의 온도에서 가열시간을 $3.0{\pm}5$초, $4.0{\pm}0.5$초, $5.5{\pm}0.5$초로 실시하면서 일반세균과 병원성미생물을 시험한 결과, 2차 가열 전 병원성 미생물은 음성이었다. 일반세균은 $230{\pm}5^{\circ}C$일 때 현저히 감소되었고, 특히 가열시간을 $5.5{\pm}0.5$일 때 $1.0{\times}10CFU/g$ 이하로 나타났다. 미생물학적 위해요소를 HACCP 시스템에 적용하여 생산한 조미김의 경우 상품가치와 품질, 안전성을 확보하기에 가장 적절한 가열온도와 가열시간은 $230{\pm}5^{\circ}C$, 가열시간은 $5.5{\pm}0.5$초로 한계기준을 설정하였다. 본 연구를 통하여 제조공정별 위해요소분석을 활용하여 조미김의 중요관리점 및 한계기준을 설정하였고, 이를 통하여 HACCP 계획을 수립하고, 사후관리 등에 활용할 수 있다.

• 한국대기환경학회지
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• 제17권2호
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• pp.133-145
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• 2001

The receptor modeling is one of the statistical methods to achieve reasonable air pollution strategies. The pur-pose of this study was to survey the concentration variability oi inorganic elements and ionic species in the PM-10 particles, to qualitatively characterize emission sources by an advanced algorithm called positive matrix factoriza-tion(PMF) as a receptor model that can strictly provide results in every loading matrix. A total of 254 samples was collected by a PM-10 high volume air sampler from Mar. 1997 to Feb. 1998 in Kyung Hee University at Suwon Campus. Fourteen chemical species(Zn, Cu, Fe, Pb, Al, Mn, $Na^{+}$, NH$_4$+, $K^{+}$, $Mg^{2+}$, $Ca^{2+}$, $SO_4^{2-}$, $NO_{3}^{-}$, and $Cl^{-}$) were determined by AAS and IC methods. The study results showed that the average monthly concentration of PM-10 particles were 86.3$\mu\textrm{g}$/$\textrm{m}^3$ in March (maximum) and 28.5$\mu\textrm{g}$/$\textrm{m}^3$ in August(minimum), respectively. The concentrations of Na+, NH$_4$+, $K^{+}$ and $Cl^{-}$ in winter, $Mg^{2+}$, $Ca^{2+}$ and $NO_{3}^{-}$, in spring, and $SO_4^{2-}$ in summer showed the largest peak concentration for the respective season. Through and app-lication of a PMF program of Pm-10 concentration data of Suwon, 9 sources were qualitatively identified , such as incineration source, oil burning source, soil related source, open burning source automobile source, coal burning sources, secondary sulfate related source, and secondary nitrate related source.

• 한국대기환경학회지
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• 제31권5호
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• pp.437-448
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• 2015

The purpose of this study is to present the source contribution of the fine particles ($PM_{2.5}$) in Chungju area using the CMB (chemical mass balance) method throughout the four seasons in Korea. The Chungju's annual average level of $PM_{2.5}$ was $48.2{\mu}g/m^3$, which exceeded two times higher than standard air quality. Among these particles, the soluble ionic compounds represent 54.2% of fine particle mass. Additionally, the OC concentration in Chungju stayed similar to other domestic cities, while the EC concentration decreased significantly compared to other domestic/international cities. The concentration of sulfur represented the highest composition (8%) among the fine particle compounds. According to the CMB results, the general trend of the $PM_{2.5}$ mass contributors was the following: secondary aerosols (50.5%: ammonium sulfate 26.5% and ammonium nitrate 24.0%) > gasoline vehicle (18.3%) > biomass burning (11.0%) > industrial boiler (6.0%) > diesel vehicles (4.4%). The contribution of the secondary aerosols was the main cause than others. This impact is assumed to be emitted from air pollutants of urban cities or neighbor countries such as China.

• Applied Microscopy
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• 제2권1호
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• pp.1-6
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• 1972

The Optimum Conditions of Preparing barium Ferrite from $BaCO_3$ and $Fe_2O_3$ are Sought for with electron microscope. At first to find the optimum sintering temperature, the mixture in 1 : 3 mole ratio. Sintered primarily at $700^{\circ}C$ for an hour, is Sintered secondary at $960^{\circ}C{\pm}10,\;1040^{\circ}C{\pm}10,\;1120^{\circ}C{\pm}10,\;1200^{\circ}C{\pm}10,\;1250^{\circ}C{\pm}10,\;1330^{\circ}C{\pm}10$, respectively for an hour. at the optimum temperature,abtained in this way. Sintering time is varied from 10 minutes to 120 minutes with 10 minutes intervals. Through the experiment, It is found that the optimum temperature of $1200{\sim}1250^{\circ}C$ and optimum time of half-one hour.

• 한국환경과학회지
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• 제16권10호
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• pp.1157-1167
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• 2007

In an effort to interpret the characteristics of fine particle concentrations in Busan, time variations of hourly monitored concentrations $PM_{10}$ (Particulate Matter with aerodynamic Diameter ${\le}10\;{\mu}m$) in Busan are analyzed for the period from 2000 to 2005. The characteristics of aerosol second generation formation process is also interpreted qualitatively, by using the statistical analysis of the meteorological variables including temperature, wind speed, and relative humidity. The result shows some significant annual, seasonal, weekly and diurnal variations of $PM_{10}$ concentrations. In particular, seasonal(i.e., spring) variations are governed by frequency of yellow sand events even for the non-yellow sand cases where yellow-sand days are eliminated in our analysis. However, in seasonal variation, summer season predominate lower $PM_{10}$ concentrations due to the frequent precipitation, and weekly and diurnal variations are both found to be reflecting the emission rate from traffic amount. Correlation coefficients between $PM_{10}$ concentration and meterological variables for non-yellow sand days show overall negative correlation with visibility, wind speed, cloud amounts, and relative humidity. However for non-precipitation days, during non-yellow sand period positive correlation are found clearly with relative humidity, suggesting the importance of secondary aerosol formation in Busan that can be achieved by both homogeneous aerosol formation and heterogeneous transformations resulting from hygroscopic aerosol characteristics.

• Journal of Electrical Engineering and Technology
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• 제8권6호
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• pp.1571-1578
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• 2013

With the emergence of high-integration array and large area panel process, the need to minimize the generation of particles in the field of semiconductor, LCD and OLED has grown. As an alternative to the conventional roller system, a contactless magnetic conveyor has been proposed to reduce the generation of particles. An EM-PM hybrid which is one of magnetic levitation types is already proposed for the conveyor system. One of problems pointed out with this approach is the vibration caused by the dynamic interaction between conveyor and rail. To reduce the vibration, the introduction of a secondary suspension system which aims to decouple the levitation electromagnet from the main body is proposed. The objective of this study is to develop a dynamic model for the magnetically levitated conveyor, and to investigate the effect of the introduced suspension system. An integrated model of levitation system and rail based on 3D multibody dynamic model is proposed. With the proposed model, the dynamic characteristics of maglev conveyor system are analyzed, and the effect of the secondary suspension and the stiffness and damping are investigated.