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        검색결과 80

        61.
        2020.04 KCI 등재 서비스 종료(열람 제한)
        Mankind has been using ships for more than 5,000 years and has developed a range of related technologies. However, despite such a long history, compared to aircraft with a history of approximately one century, the pace of progress has been markedly slow. Even though technological progress of ships or the installation of various navigation equipment have been achieved, seaborne collisions have occurred quite frequently. This study analyzed the TCAS( Traffic Collision Avoidance System) that has contributed to the prevention of collisions with other transport methods including aircraft to suggest a collision avoidance system that can be deployed for ships. To apply the technologies applied to aircraft that move in 3D to ships that move in 2D, the difference in the operational environment between the two modes was analyzed to identify elements that need to be applied to ships. The suggested display of data on the collision prevention system is one that manipulates the augmented reality display device used in automobiles that over the past few years has undergone rapid development. Based on the presentation of technological elements that need to be considered when adopting the SCAS or the Seaborne Collision Avoidance System as suggested in this study, the authors hope to contribute to the prevention of collisions.
        62.
        2019.04 서비스 종료(열람 제한)
        In this research, airborne chlorides of sea bridges in terms of height were measured every month in the West and South coast for 1 year. The results showed that the decreasing tendency of airborne chlorides to height strongly depends on the maximum amount of airborne chlorides of the target area.
        63.
        2019.03 KCI 등재 서비스 종료(열람 제한)
        직경 10 μm 미만의 대기 미립자 물질(particulate matter, PM10)은 다양한 신체기관에서 산화 스트레 스와 염증반응을 유발한다. 본 연구의 목적은 인간 표피 각질형성세포(HEK)에서 PM10에 의해 유도되는 반응 성 산소종(ROS) 생성의 메커니즘을 알아보는 것이다. 배양된 HEK를 PM10에 노출시켰을 때 ROS가 증가하였으며, 이는 항산화제 apocynin에 의해 저해되었다. PM10에 의해 유도되는 ROS 생성에서 NADPH oxidase (NOX) family의 역할을 규명하기 위하여 이들의 mRNA 발현을 분석하였다. PM10은 NOX1, NOX2, dual oxidase (DUOX)1 및 DUOX2의 mRNA 발현을 증가시켰다. 다른 NOX들에 비교하여 DUOX1 및 DUOX2의 발현 수준이 높았으며, 이들 효소의 maturation factors, 즉 DUOXA1와 DUOXA2의 mRNA 발현도 PM10에 의하여 증가하였다. 칼슘 의존성 효소인 DUOX1과 DUOX2가 PM10에 의해 유도되는 ROS의 생성을 매개하는 지 조사하였다. 선택적인 세포내 칼슘 킬레이터인 BAPTA-AM은 PM10 및 칼슘 ionophore A23187에 유도된 ROS 생성을 감소시켰다. 작은 간섭 RNA (siRNA)에 의한 DUOX2의 하향 조절은 PM10에 의해 유도된 ROS의 생성을 감소시켰고 DUOX1 siRNA는 영향이 없었다. PM10은 interleukin (IL)-1β, IL-6, IL-8 및 interferon (IFN)-γ 등 사이토카인의 발현을 증가시켰다. siRNA에 의한 DUOX2의 하향 조절은 IFN-γ의 발현을 저해하였지만 다른 사이토카인의 발현은 저해하지 않았다. 본 연구는 PM10에 노출된 HEK의 ROS 생성 및 염증 반응에서 DUOX2가 중요한 역할을 함을 시사한다.
        64.
        2018.09 KCI 등재 서비스 종료(열람 제한)
        대기 오염은 피부의 산화적 손상, 염증 및 노화를 일으킬 수 있다. 레스베라트롤은 폴리페놀 화합물의 일종으로 항산화, 항염증, 멜라닌 생성 억제 작용 등 다양한 생물학적 활성이 있는 한편 열과 빛에 약한 단점이 있다. 레스베라트릴 트라이아세테이트(RTA)는 레스베라트롤에 비해 안정하고, 피부 안전성과 미백 효능이 보고된 화장품 신소재이다. 본 연구의 목적은 직경 10 μ m 미만 대기 미립자 물질(PM10)에 노출된 인간 표피 각질형성세포(HEK)의 염증 반응에 대한 레스베라트롤과 RTA의 영향을 조사하기 위한 것이다. 배양된 HEK세 포를 레스베라트롤과 RTA의 유무 조건에서 PM10에 노출시키고, 세포 생존율, 반응성 산소종(ROS)의 생성 및 염증성 사이토카인의 발현을 분석하였다. PM10을 처리하였을 때 세포 생존율이 감소하였고 종양괴사인자- α(TNF-α), 인터루킨-1β(IL-1β), 인터루킨-6(IL-6) 및 인터루킨-8(IL-8)의 발현이 증가하였다. 레 스베라트롤과 RTA는 PM10으로 유도된 세포의 사멸과 ROS 생성을 경감시켰다. PM10에 의해 증가되는 여러 염증성 사이토카인의 발현은 레스베라트롤과 RTA에 의해 경감되거나(IL-6), 증진되거나(IL-1β), 변화하지 않았다(TNF-α 및 IL-8). PM10에 의해 유도된 IL-6단백질의 발현이 레스베라트롤과 RTA에 의해 감소되 었다. 본 연구의 결과는 레스베라트롤과 RTA가 대기 미립자 물질에 노출된 피부의 세포 손상과 염증 반응을 조절하는 작용이 있음을 시사한다.
        65.
        2017.09 서비스 종료(열람 제한)
        In this study, airborne chlorides by height of sea-crossing bridges in West and South seashore were discussed. As the results during spring and summer, the higher altitude, the less airborne chlorides was detected. However, the closer height to the traffic road, the more abundant airborne chlorides were showed.
        66.
        2017.04 서비스 종료(열람 제한)
        The airborne chlorides environment by de-icing salts of the Suam road tunnel in motorway were examined. It was found that higher airborne chlorides were detected inside road tunnel than outside. Therefore, there is a need to appreciate that RC structures inside tunnel might be exposed to salt attack environment.
        67.
        2017.04 서비스 종료(열람 제한)
        The depth of a surface-breaking crack in a concrete slab is characterized by using airborne surface wave transmission measurements. Two air-coupled sensors are used to measure surface waves across surface-breaking cracks with varying depths from 0 mm to 100 mm in a concrete slab (1500 X 1500 X 180 mm3). Resulting transmission coefficient and crack depth relation from a series of experimental studies shows a good agreement with theoretical results previously obtained by the author.
        68.
        2017.01 KCI 등재 서비스 종료(열람 제한)
        The airborne chlorides environment by de-icing salts of the Suam road tunnel in motorway were examined. It was found that higher airborne chlorides were detected inside road tunnel than outside. Therefore, there is a need to appreciate that RC structures inside tunnel might be exposed to salt attack environment
        69.
        2016.04 서비스 종료(열람 제한)
        The airborne chlorides environment by de-icing salts of retaioning wall in motorway were examined. It was found that in the retaining wall, height of 14m, the airborne chlorides tend to be decreased by height ranged between 81.0-73.8%.
        70.
        2015.05 KCI 등재 서비스 종료(열람 제한)
        East Asia is characterized by anthropogenic emissions resulting from the large population and fast economic growth of this region. Since the prevailing wind is westerly and northwesterly, emissions from Ul-jin can be expected to contribute to acidic deposition increase in downwind direction. Aerosols collected at the near coast site, Uljin geun, gyungbook and were analyzed for NH4 +, Mg2+, Na+, Ca2+, Cl-, SO4 2-, and NO3 - from Aug. 2012 to Feb. 2013. The seasonal averaged aerosol concentration showed the highest potassium and calcium ion in winter and the highest ammonium ion due to a meadow and high solar intensity in summer. Sodium and chloride ion showed the same ratio all seasons and sulfate and nitrate species showed the maximum value in winter Chemical components of aerosols collected at the near coast site, Uljin geun, gyungbook were lower by 16 to 73% than those collected at other similar environment site such as kanghwa, yangyang. Comparing air quality data at the near coast site, Uljin geun, gyungbook, There was found that Uljin coast site is less influenced by the sea salts(potassium, magnesium, calcium) and nss-SO4 2- percentage is 3~13% higher than similar condition site.
        71.
        2015.05 KCI 등재 서비스 종료(열람 제한)
        This study was performed to identify the state of the exposure and characteristics of pollutants by each process at 4 casting sites located in Gyeongsang-do from April to November 2013. The concentrations of methanol, crystallized silica glass, formaldehyde and phenol were analyzed by different process - casting process, molding process, core process, and shakeout & finishing process. The highest concentration of methanol was found in casting and molding process, whereas the highest concentration of crystalline quartz(Silica) was observed in core process. The most oxidized steel dusts and the highest concentration of fume were found in shakeout & finishing process. As a result of this study, those labors working at the casting site were found to be constantly exposed to various forms of hazardous chemicals; therefore, it is considered that this is the time to manage and plan how to reduce them. In addition, it is required to thoroughly manage the local exhauster, and improve the process and working environment to reduce various forms of hazardous chemicals.
        72.
        2015.02 서비스 종료(열람 제한)
        기후변화로 인해 최근 홍수의 발생 빈도, 돌발홍수 및 국지성 홍수가 증가하고 있을 뿐 아니라 규모도 커지고 있어, 홍수 예측을 위한 컴퓨터 수치모형의 신속성과 정확성에 대한 요구가 점점 증대되고 있다. 본 연구에서는 홍수 예측 수치모형의 정확성 검증을 위한 한 방안으로 위성영상자료의 활용에 관해 보여준다. 적용한 홍수 예측 수치모형은 2차원 유한체적 홍수범람 모형으로 혼합격자(삼각형과 사각형)의 사용이 가능하여, 복잡한 지형의 홍수 모델링에도 쉽게 적용이 가능하다. 연구유역은 2000년 11월에 계절 평균 강수량을 초과하는 이상강우로 인한 제방 월류로 홍수가 10일 이상 동안 발생한 영국의 Severn강 유역이다. 이 유역 홍수 모델링을 위한 지형자료의 구축을 위해 3m 해상도의 LiDAR (Light Detection And Ranging)를 이용하였으며, 실측홍수량(위)을 상/하류단 경계조건으로 적용하였다. 그리고 홍수 발생기간 동안 촬영된 4개(11월 8일, 14일, 15일 그리고 17일)의 ASAR (Airborne Synthetic Aperture Radar) 영상자료를 홍수범람모형의 검증에 활용하여, 홍수 최대 범람 범위뿐만 아니라 홍수가 증가하는 시기와 하류단 배수로 인해 홍수가 감소하는 시기를 모두 포함하는 홍수범람범위에 대하 2차원 홍수범람모형의 검증을 수행하였다.
        73.
        2013.12 KCI 등재 서비스 종료(열람 제한)
        The objective of this study was to evaluate associations between airborne manganese and blood manganese in a general population of South Korean adults. The concentrations of airborne manganese in total suspended particulate (TSP) were calculated from data obtained from ambient air-monitoring stations (AAMSs) located in South Korea. Blood manganese data obtained Korean National Health and Nutrition Examination Survey (KNHANES) using a rolling sampling design involving a complex, stratified, multistage, probability cluster survey of a representative sample of the non-institutionalized civilian population of South Korea. Airborne manganese geometric means was 46.10 ng/㎥, blood manganese geometric means were 1.19 ㎍/㎗ for male and 1.40 ㎍/㎗ for female. In multiple linear regression analysis of log transformed blood manganeseas a continuous variable on airborne manganese, after adjusting for covariates including gender, age, job, smoking and drinking status, education level, BMI (body mass index). Airborne manganese was positively associated with blood manganese with statistical significance. The present study confirms that airborne manganese is a possible contributor to the increase of blood manganese in the adult general population.
        74.
        2013.10 KCI 등재 서비스 종료(열람 제한)
        Graphene oxide (GO)-titania composites have emerged as an attractive heterogeneous photocatalyst that can enhance the photocatalytic activity of TiO2 nanoparticles owing to their potential interaction of electronic and adsorption natures. Accordingly, TiO2-GO mixtures were synthesized in this study using a simple chemical mixing process, and their heterogeneous photocatalytic activities were investigated to determine the degradation of airborne organic pollutants (benzene, ethyl benzene, and o-xylene (BEX)) under different operational conditions. The Fourier transform infrared spectroscopy results demonstrated the presence of GO for the TiO2-GO composites. The average efficiencies of the TiO2-GO mixtures for the decomposition of each component of BEX determined during the 3-h photocatalytic processes were 26%, 92%, and 96%, respectively, whereas the average efficiencies of the unmodified TiO2 powder were 3%, 8%, and 10%, respectively. Furthermore, the degradation efficiency of the unmodified TiO2 powder for all target compounds decreased during the 3-h photocatalytic processes, suggesting a potential deactivation even during such a short time period. Two operational conditions (air flow entering into the air-cleaning devices and the indoor pollution levels) were found to be important factors for the photocatalytic decomposition of BEX molecules. Taken together, these results show that a TiO2-GO mixture can be applied effectively for the purification of airborne organic pollutants when the operating conditions are optimized.
        76.
        2011.05 KCI 등재 서비스 종료(열람 제한)
        This paper describes efficient flight control algorithms for building a reconfigurable ad-hoc wireless sensor networks between nodes on the ground and airborne nodes mounted on autonomous vehicles to increase the operational range of an aerial robot or the communication connectivity. Two autonomous flight control algorithms based on adaptive gradient climbing approach are developed to steer the aerial vehicles to reach optimal locations for the maximum communication throughputs in the airborne sensor networks. The first autonomous vehicle control algorithm is presented for seeking the source of a scalar signal by directly using the extremum-seeking based forward surge control approach with no position information of the aerial vehicle. The second flight control algorithm is developed with the angular rate command by integrating an adaptive gradient climbing technique which uses an on-line gradient estimator to identify the derivative of a performance cost function. They incorporate the network performance into the feedback path to mitigate interference and noise. A communication propagation model is used to predict the link quality of the communication connectivity between distributed nodes. Simulation study is conducted to evaluate the effectiveness of the proposed reconfigurable airborne wireless networking control algorithms.
        77.
        2011.04 KCI 등재 서비스 종료(열람 제한)
        Unlike many laboratory-scale studies on absorption of organic compounds (VOCs), limited pilot-scale studies have been reported. Accordingly, the present study was carried out to examine operation parameters for the effective control of a hydrophilic VOC (methyl ethyl ketone, MEK) by applying a circular pilot-scale packed-absorption system (inside diameter 37 cm × height 167 cm). The absorption efficiencies of MEK were investigated for three major operation parameters: input concentration, water flow rate, and ratio of gas flow-rate to washing water amount (water-to-gas ratio). The experimental set-up comprised of the flow control system, generation system, recirculation system, packed-absorption system, and outlet system. For three MEK input concentrations (300, 350, and 750 ppm), absorption efficiencies approached near 95% and then, decreased gradually as the operation time increased, thereby suggesting a non-steady state condition. Under these conditions, higher absorption efficiencies were shown for lower input concentration conditions, which were consistent with those of laboratory-scale studies. However, a steady state condition occurred for two input concentration conditions (100 and 200 ppm), and the difference in absorption efficiencies between these two conditions were insignificant. As supported by an established gas-liquid absorption theory, a higher water flow rate exhibited a greater absorption efficiency. Moreover, as same with the laboratory-scale studies, the absorption efficiencies increased as water-to-gas ratios increased. Meanwhile, regardless of water flow rates or water-to-gas ratios, as the operation time of the absorption became longer, the pH of water increased, but the elevation extent was not substantial (maximum pH difference, 1.1).
        78.
        2010.04 KCI 등재 서비스 종료(열람 제한)
        his study was investigated the characteristics of indoor air concentration of fiber particles in 30 public facilities and 245 schools by PCM (phase contrast microscopy). Also SEM/EDX (scanning electron microscope / energy dispersive using X-ray analysis) was used to obtain physicochemical information of asbestos fiber and to classify asbestos and non-asbestos of fiber particles. The airborne concentrations of fiber particles were 0.0009±0.0009 counts/mL in public facilities and 0.0012±0.0006 counts/mL in schools by PCM. All the samples were satisfied with the IAQ (indoor air quality) level of 0.01counts/mL. In classification of 4 type shapes, over 80% of the fiber particles were identified as single fiber type. And this study analysed airborne fiber particles in 4 sites for identifying asbestos of by SEM/EDX. The asbestos fibers in most samples could not be found.
        79.
        2006.06 KCI 등재 서비스 종료(열람 제한)
        Airborne particles collected from a heavily industrialized site were analyzed by chemical speciation of seven trace metals: Pb, Cd, Cr, Cu, Ni, Zn, and As. The average concentrations were as follows: Zn, 502.0 ± 230.7; Pb, 176.5 ± 310.9; Cu, 111.9 ± 82.7; As, 38.0 ± 31.0; Cr, 21.5 ± 24.4; Cd, 20.8 ± 17.4; and Ni, 11.4 ± 8.4 ng/m3. The median enrichment factor (EF) values of Cd (7,280), As (1,030), Cu (215), Zn (214), and Pb (143), with respect to iron, were much larger than 100. We observed that Cd was found in the soluble and exchangeable form (56.9%), and that Pb and Cr were found in carbonates, oxides and the reducible form (69.8% and 61.1%, respectively). These two forms, which are the most easily absorbed into human body tissue, predominated in most of the trace metals investigated in this study.
        80.
        2004.03 KCI 등재 서비스 종료(열람 제한)
        This study was conducted to evaluate the characterization of airborne bioaerosol in public facilities in Seoul. A total of 17 public facilities were investigated from December, 2002 to February, 2003. As results of the survey, the mean concentrations of bacteria and fungi in indoor air of public facilities were 378.08±296.33CFU/m3 by RCS and 106.38±171.63CFU/m3 and 347.46±335.32CFU/m3 and 95.23±62.61CFU/m3, by Six-stage cascade air sampler respectively. The mean concentrations of bacteria in indoor air (by ventilation method) were 517.14±343.93CFU/m3 of natural ventilation and 215,83±100.71CFU/m3 of mechanical ventilation. The mean concentrations of fungi in indoor air (by ventilation method) were 83.14±79.16CFU/m3 of natural ventilation and 133.50±248.07 CFU/m3 of mechanical ventilation. The mean concentrations of bacteria in indoor air were 449.44CFU/m3 for the ground and 217.50±103.68CFU/m3 for the underground. The mean concentrations of fungi in indoor air were 63.89±77.66CFU/m3 for the ground and 202.00±290.08CFU/m3 for the underground.
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