• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2010년도 추계학술대회 논문집
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• pp.981-982
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• 2010

• 한국대기환경학회지
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• 제20권4호
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• pp.503-514
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• 2004

In Seoul metropolitan area, nocturnal variation of surface ozone concentrations observed at 27 monitoring sites from 1998 to 2002 showed that high ozone levels occurred frequently during the spring. Frequency distributions for nighttime ozone indicated that elevated concentrations in spring were influenced by advection of different air mass compared to other seasons. Surface wind analysis during the spring revealed that relatively strong southwesterly winds were associated with nocturnal ozone enhancement, which can be attributed to the regional transport of ozone. In order to identify the origin of nocturnal ozone enhancement in spring, 3-day backward trajectories were calculated by HYSPLIT 4 for the episode days and then classified. The results showed that NW, W, and SW flows, indicating influence of polluted air masses from the China continent, have 51% in a]1 the episode days, which suggest that the nocturnal ozone enhancement can occur under the effect of long-range transport of ozone-laden air mass on a regional scale. Case study of nocturnal ozone maxima associated with long-range transport was discussed in more detail in the light of meteorological conditions. Southwesterly synoptic flow along the outer edge of moving high-pressure system was found to be the important cause of nocturnal ozone maxima in Seoul. This flow could lead to be long-range transport of ozone that had effectively accumulated in the stagnating portion of the system located eastern coast of China. Low atmosphere soundings, backward trajectories, and elevated ozone and CO levels at the back-ground tiles gave evidence for regional effects on nocturnal ozone enhancement In Seoul.

• 환경생물
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• 제30권3호
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• pp.219-230
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• 2012

2010년 진해만의 춘계와 하계를 중심으로 환경요인 변화와 식물플랑크톤의 군집구조의 상관관계에 대한 생태학적 연구를 수행하였다. 식물플랑크톤의 생물량과 환경요인과의 상관관계를 조사하기 위해 수행한 다중상관분석과 CCA (Canonical Correspondance Analysis) 결과, 하계에 우점한 Chaetoceros spp., Skeletonema costatumlike spp., Pseudo-nitzschia delicatissima는 생물량 변화에 영향을 미치는 주요 요인을 선정할 수는 없었다. 반면, 춘계의 Cryptomonas spp.와 Pseudo-nitzschia multistriata 는 질산염과의 양(+)의 상관관계(p<0.05)가 있을 것으로 판단되었다. 하계에 나타난 식물플랑크톤과 환경요인간의 유의한 양 (+) 상관관계가 나타나지 않는 것은 강우에 의해 유입된 탁도 물질등에 의한 저층의 광합성 활성의 저하와 우점종의 구성과 생물량 차이에 의해 나타난 결과로 판단되었다. 또한 환경에 적응한 우점종의 분포특성은 진해만 광역해역을 부분적으로 구분할 수 있는 생물학적 요인으로 판단되었다. 결과적으로 식물플랑크톤과 환경요인과의 상관관계는 주요 우점종의 분포와 관련이 있었고, 특히 성층화된 하계에 우점한 식물플랑크톤 분포는 해역 구분에 중요한 인자로 활용 될 수 있었다.

• Ocean and Polar Research
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• 제30권4호
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• pp.379-399
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• 2008

Spatial-temporal variations in physiochemical water qualities (temperature, salinity, DO, SPM, POC and nutrients) of surface and bottom waters were investigated along the mid-western coastal area (Taean Peninsula to Gomso Bay) of Korea. Spatial distribution patterns of temperature and salinity were mostly controlled by the physical mixing process of freshwater from Geum River and/or Gyunggi Bay with nearby coastal water. A strong tidal front is formed off Taean Peninsula during spring and summer. Seasonal variations in nutrient concentrations, lower in spring and summer and higher in fall and winter, are primarily regulated by magnitude of phytoplankton occurrence rather than freshwater loadings into the bay. Based on seasonal and spatial variability of physicochemical parameters, water quality of the study area can be divided into four water masses; Gyunggi Bay-influenced Water Mass (GBWM), Geum River-influenced Water Mass (GRWM), Yellow Sea Bottom Cold Water Mass (YSBCWM) and Cheonsu Bay Water Mass (CBWM). Water quality of the GBWM (Taean Peninsula coastal area), which has relatively low salinity and high concentrations of nutrients, is strongly controlled by the Gyunggi Bay coastal water, which is under influence of the Han River freshwater. In this water mass, the mixed layer is always developed by strong tidal mixing. As a result, a tidal front is formed along the offshore boundary of the mixed layer. Such tidal fronts probably play an important role in the distribution of phytoplankton communities, SPM and nutrients. The GRWM, with low salinity and high nutrients, especially during the flood summer season, is closely related to physiochemical properties of the Geum River. During the flood season, nutrient-enriched Geum River water mass extends up to 60 km away from the river mouth, potentially causing serious environmental problems such as eutrophication and unusual and/or noxious algal blooms. Offshore (<$30{\sim}40m$ in water depth) of the study area, YSBCWM coupled with a strong thermocline can be identified in spring-summer periods, exhibiting abundant nutrients in association with low temperature and limited biological activity. During spring and summer, a tidal front is formed in a transition zone between the coastal water mass and bottom cold water mass in the Yellow Sea, resulting in intensified upwelling and thereby supplying abundant nutrients to the GBWM and GRWM. Such cold bottom water mass and tidal front formation seems to play an important role in controlling water quality and further regulating physical ecosystem processes along mid-western Korean coastal area.

• 한국약용작물학회지
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• 제14권6호
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• pp.322-328
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• 2006

Green tea is of particular source as it has been found to have strong antioxidant activities. The extracts of green tea during the commercial harvest seasons from April, 2003 to August, 2003 were compared. The purpose of this study was to determine the correlation between the polyphenol content of green teas and its antioxidant activities. The con-tent of total polyphenols was analyzed and several antioxidant testings were performed. The levels of total polyphenols were higher in the green teas (e.g. Woojeon, Sejak) harvested during very early spring and lower in the green teas harvested late(eg. Ipha, Yepcha). In particular, the free radical scavenging, the inhibition of LDL oxidation, the cytoprotective effect and the inhibition of DNA damage were correlated with the total polyphenol contents of green tea extracts harvested early spring such as Woojeon, Sejak and Jungjak. The results obtained here show that all extracts of green teas including purified green tea catechin, GTC, have strong antioxidant activities on oxidative stress in vifrθ. The variation in polyphenol content and antioxidant activities among various types of green tea by the harvesting time may provide critical information for investigators and consumers using tea in purposes of nutrition and chemoprevention.

• 대한원격탐사학회:학술대회논문집
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• 대한원격탐사학회 2006년도 Proceedings of ISRS 2006 PORSEC Volume I
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• pp.118-121
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• 2006

Variations in the extent and dispersal of river plume are important in the study of coastal environment. The objectives of this study are to examine relationship between satellite detected plume area and river discharge and to clarify the temporal and spatial dynamic of plume from Tokachi River, Hokaido, Japan. We used 1.1 km spatial resolution of SeaWiFS normalized water-leaving radiance (nLw) images from 1998 to 2002. Supervised maximum likelihood classification was implemented to define classes of surface water optical properties. Satellite observed plume area was correlated to the amount of river discharge from April to October. First mode (44% of variance) of EOF analysis shows the turbid plume distribution resulting from re-suspension by strong wind mixing along the coast during winter. This mode also shows plume distribution along-shelf direction in spring and late summer. Second mode (17% of variance) shows spring pattern across-shelf direction due to strong discharge of snow melting water.

• 대기
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• 제31권4호
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• pp.405-420
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• 2021

Forest fire happens every year at Yeongdong, Gangwon-do, due to the strong local wind during the spring time and it causes a huge damage. This wind is named "Yangganjipung" or "Yanggangjipung" that blows along Yeongdong. However, the occurrence conditions of the wind have been still unclear. To identify the occurrence mechanism of local strong wind through three-dimensional observation data, Gangwon Regional Meteorological Administration performed Joint Gangwon-Yeongdong 3D Observation Project in 2020. The special observation was carried out for 6 times from March to April. The observation data was analyzed by focusing on the structure of synoptic pressure distribution and inversion layer. The result showed that the strength of wind is different depending on the latitude of low pressure, intensity of inversion layer, and changes on height in the south-high and north-low pressure distribution. As the interval of the upper and lower parts of the inversion layer was narrow, the strength of the wind became stronger, which is one of the observational characteristics of the springtime wind pattern at Yeongdong, Gangwon-do. In future, the clear mechanism of the local wind in the Yeongdong during the spring time is expected to be verified based on the accumulative observation data and close analysis.

• 해양환경안전학회지
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• 제25권3호
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• pp.278-286
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• 2019

The Port of Pyeong Taek is located on the west coast, meaning that the difference between the rise and fall of tide is great (flood tide 1.8 to 2.9 knots, ebb tide 1.6 to 2.9 knots). Due to mainly N~NW'ly strong winds & high waves during winter, navigating as well as loading & discharging vessels must focus on cargo handling. The strong tidal and wind forces in the Port of Pyeong Taek can push an LNG carrier away from its berth, which will end up causing forced disconnection between the vessel's cargo line and shore-side loading arm. The primary consequence of this disconnection will be LNG leakage, which will lead to tremendous physical damage to the hull and shore-side equipment. In this study, the 125K LNG Moss Type ship docked at No. 1 Pier of the Pyeong Taek is observed, and the tension of the mooring line during cargo handling is calculated using a combination of wind and waves to determine effective mooring line and mooring line priority management. As a result if the wind direction is $90^{\circ}$ to the left and right of the bow, it was found that line monitoring should be performed bearing special attention to the Fore Spring Line, Fore Breast Line, and Aft Spring Line.

• 한국해양학회지
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• 제29권2호
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• pp.83-94
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• 1994

현장 관측, 수리실험 및 수치실험에 의해 진해만 조류 및 조속간차류의 2차원적 변동특성을 연구하였다. 수리 및 수치실험 결과는 현장 관측결과와 비교적 잘 일치하 였다. 가덕수로, 견내량수로 및 진해만의 중앙수로에서 대조기 최강유속은 약 90∼110 cm/s 이고, 소조기 최강유속은 약 30∼40 cm/s 로써 강하게 나타났으며, 조속간 차류 도로 여러개의 와류를 형성하면서 강하게 일어났다. 진해만의 서부해역과 북부해역에 서 대조기 외강유속은 약 30 cm/s 이하, 소조기 최강유속은 약 10 cm/s 이하로써 약하 며, 조속장로 비교적 약하게 일어났다. 가조로 북부해역에서는 북향하는 조속장로 가 조로 이남해역에서는 시계방향으로 회전하는 와류가 발생하였다. 만내에서 표층흐름 은 바람 하천유출수에 의해 강하게 지배되고, 대조류보다 소조기의 흐름이 바람 과 유출수의 영향을 더 많이 받는다.

• 한국구조물진단유지관리공학회 논문집
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• 제12권4호
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• pp.71-78
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• 2008

철도교량의 경우, 열차하중에 의한 영향으로 교량 단부에서 상향력이 발생하였으며, 이 상향력은 체결장치에 압축력과 인장력을 유발시켰다. 현재까지 이에 대한 안전성을 검토하기 위해 체결장치를 1방향의 스프링 요소로 모사하여 구조해석을 수행해 왔다. 이러한 경우에 스프링 요소의 강성은 압축력을 재하한 실험적 연구에 의하여 산정되었다. 따라서, 상향력은 체결장치에 압축력뿐만 아니라 인장력도 유발시키기 때문에 합리적이고 정확한 구조해석을 수행하기 위해서는 인장력을 재하한 실험적 연구로부터 산정된 병진방향 강성 그리고 회전방향 강성을 함께 고려해야 한다. 본 연구에서는 6가지 실험체에 대하여 탄성과 비탄성 실험을 수행하여 레일 연직방향 병진강성과 레일 강축에 대한 회전강성을 검토하였고, 체결장치의 구조적인 거동을 분석하였다.