• Journal of Environmental Science International
• /
• v.9 no.5
• /
• pp.375-384
• /
• 2000

It is very important to interprete and simulate the variation of phytoplankton maximum region for the prediction and control of red tide. This study was composed of two parts first the hydrodynamic simulation such as residual current and salinity diffusion and second the ecological simulation such as phytoplankton distribution according to freshwater discharge and pollutant loads. Without the Nakdong river discharge residual current was stagnated in inner side of this estuary and surface distribution of salinity was over 25psu. On the contrary with summer mean discharge freshwater stretched very far outward and some waters flowed into Chinhae Bay through the Kadok channel and low salinity extended over coastal sea and salinity front occurred. From the result of contributed physical process to phytioplankton biomass the accumulation was occurred at the west part of this estuary and the Kadok channel with the Nakdong river discharge. When more increased input discharge the accumulation band was transported to outer side of this estuary. The frequently outbreak of red tide in this area is caused by accumulation of physical processes. The phytoplankton maximum region located inner side of this estuary without the Nakdong river discharge and with mean discharge of winter but it was moved to outer side when mean discharge of the Nakdong river was increased. The variation of input concentration from the land loads was not largely influenced on phytoplankton biomass and location of maximum region. When discharge was increased phytoplankton maximum region was transferred to inner side of the Kadok channel. ON the other hand when discharge was decreased phytoplankton maximum region was transferred to inner side of this estuary and chlorophyll a contents increased to over 20$\mu\textrm{g}$/L Therefore if any other conditions are favorable for growth of phytoplankton. decreas of discharge causes to increase of possibility of red tide outbreak.

• Atmosphere
• /
• v.26 no.4
• /
• pp.577-598
• /
• 2016

Observational and numerical studies have been carried out to understand the cause and development processes of the heavy rainfall over the middle Korean Peninsula during 0300 LST-1500 LST 29 June 2011 (LST = UTC + 0900). The heavy rainfall event occurred as the synoptic-scale ridge extended from Western Pacific Subtropical High (WPSH) was maintained over East Asia. Observational analysis indicates that the heavy rainfall is mainly due to scattered convective systems, formed over the Yellow Sea, traveling northeastward across the middle peninsula without further organization into larger systems during 0300 LST-0800 LST, and mesoscale convective systems (MCSs) over the Yellow Sea, transformed into a squall line, traveling eastward during 0800 LST-1500 LST. Organization of convective systems into MCSs can be found over the area of mesoscale trough and convergence zone in the northern end of the low-level jet (LLJ) after 0600 LST. Both observational and numerical investigations indicate that a strong LLJ extended from the East China Sea to the Yellow Sea plays an essential role for the occurrence of heavy rainfall. The strong LLJ develops in between the WPSH and a pressure trough over eastern China. Numerical experiments indicate that the land-sea contrast of solar heating of surface and latent heating due to convective developments are the major factors for the development of the pressure trough in eastern China. Numerical study has also revealed that the mountainous terrain including the mountain complex in the northern Korean Peninsula contributes to the increase of rainfall amount in the middle part of the peninsula.

• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
• /
• v.7 no.3
• /
• pp.148-156
• /
• 2002

The coastline of Hampyung Bay, southwestern coast of Korea, was examined and measured in the field for the understanding of geomorphic changes and sea-cliff erosion processes. The Hampyung-Bay coastline is characterized by steep-face slope and soft soil and/or intensively weathered rock composition. Saw teeth-shaped coastline, and relict weathered basement-rock and "Island Stack" exposed on the beach surface are peculiar geomorphic features indicating active sea-cliff erosion. The coastline in the study area is continuously retreating with the following cyclic process: erosion of cliff base, gravitational landslide or mass wasting, formation of talus, and then erosion and removal of talus. In this study, sea-level rise during summer in the west coast of Korea is suggested as one of the key factors fur the removal of soil taluses and, thereby, accelerating sea-cliff erosion.f erosion.

• Proceedings of the Korean Vacuum Society Conference
• /
• 2012.02a
• /
• pp.436-437
• /
• 2012

Double patterning technology (DPT) has been suggested as a promising candidates of the next generation lithography technology in FLASH and DRAM manufacturing in sub-40nm technology node. DPT enables to overcome the physical limitation of optical lithography, and it is expected to be continued as long as e-beam lithography takes place in manufacturing. Several different processes for DPT are currently available in practice, and they are litho-litho-etch (LLE), litho-etch-litho-etch (LELE), litho-freeze-litho-etch (LFLE), and self-aligned double patterning (SADP) [1]. The self-aligned approach is regarded as more suitable for mass production, but it requires precise control of sidewall space etch profile for the exact definition of hard mask layer. In this paper, we propose etch end point detection (EPD) in spacer etching to precisely control sidewall profile in SADP. Conventional etch EPD notify the end point after or on-set of a layer being etched is removed, but the EPD in spacer etch should land-off exactly after surface removal while the spacer is still remained. Precise control of real-time in-situ EPD may help to control the size of spacer to realize desired pattern geometry. To demonstrate the capability of spacer-etch EPD, we fabricated metal line structure on silicon dioxide layer and spacer deposition layer with silicon nitride. While blanket etch of the spacer layer takes place in inductively coupled plasma-reactive ion etching (ICP-RIE), in-situ monitoring of plasma chemistry is performed using optical emission spectroscopy (OES), and the acquired data is stored in a local computer. Through offline analysis of the acquired OES data with respect to etch gas and by-product chemistry, a representative EPD time traces signal is derived. We found that the SE-EPD is useful for precise control of spacer etching in DPT, and we are continuously developing real-time SE-EPD methodology employing cumulative sum (CUSUM) control chart [2].

• Journal of the Korean earth science society
• /
• v.21 no.4
• /
• pp.488-501
• /
• 2000

'The Voyage of the Beagle' , one of the best record of scientific travels ever made, written by Charles Darwin (1809-82), the greatest naturalist ever born, is reviewed in the viewpoint of the Earth Sciences. Various observations and interpretations on the Earth Sciences are told in the Voyage. First of all, Darwin understood the geological time much more longer than accepted then as well as the geological phenomena and processes such as orogeny, uplifting, subsidence, erosion, and deposition. And he also provided a perfect interpretation on the formation of coral reefs and a good theory on the evolution of organisms. Reasonable paleoenvironmental reconstructions and interpretations based on the fossils were given in the Voyage. His observations on meteorological phenomena were from the dust composed of organisms collected on the 'Beagle' in the Atlantic Ocean, to the movement of air and extreme clear dry condition experienced on the crest of the Andes, and etc. He made several observations on the general oceanography such as the discoloration of the sea, the lights on the sea surface, conchoidal provinces noted on the Galapagos Archipelago, the trees and plants found in the remotely separated islands, and etc. However relatively scarce observation was carried out on astronomy probably due to his relatively much land travelling. Most of his interpretations and suggestions are accepted in this time.

• Spatial Information Research
• /
• v.3 no.1
• /
• pp.1-18
• /
• 1995

Despite the widespread use of GIS over the past ten years, it has been limited application for regional modeling of pollutant loadings such as sediment, nitrogen, and phosphorus(non-point source pollution), The goals of this study were to: select important processes and parameters of watersheds that contribute to non-point source pollution degradation, develop a ranking model to use the environmental geologic data and verify the model by comparing results with existing water quality data(Chung-ju Lake) for specific watersheds, The GIS database consisted of topography, geology, soils, precipitation, rainfall erosivity, land use, and watershed boundaries. The index(NPSP) for assessing non-point source pollution was comprised in the following three seperate components: soil loss index(SLI) assesses the potential soil erosion and sedim-ent delivery from field to stream; run-off potential ratio(R.P.R) predicts the potential production of surface runoff; chloropgyll-a index ranks the potential manure(animal or human) production within a watershed. The GIS model was a valuable tool to assess the impact of environmental pollation in watersheds.

• Journal of Wetlands Research
• /
• v.11 no.1
• /
• pp.105-113
• /
• 2009

Heat energy exchange is very important processes in the coastal wetland ecosystems. We observed and analyzed the net radiation flux, the sensible heat flux, the latent heat flux and the soil heat flux, which are balanced in the heat energy balance, over a reclaimed land covered with reeds at Goheung, Jeonllanamdo where is horizontally plane. The atmospheric turbulence had been measured in order to estimate the heat transfer during 5 intensive observation periods (IOPs). It was considered that the soil consists of water, fine particles, and vegetation canopy that changes color and density according to the season. We examined the characteristics of the heat flux and the vegetation effect on the air temperature control. It was noted that the heat was transported mainly by latent heat flux in the summer season and the vegetation canopy decreased the daily temperature range due to the heat storage. The air temperature was lower at the IOPs site than near urban area. This showed that the coastal wetland covered with the vegetation control the thermal environment.

• Proceedings of the Korea Water Resources Association Conference
• /
• 2015.05a
• /
• pp.467-467
• /
• 2015

Sustainable water resource management requires the assessment of hydrological variability in response to climate fluctuations and anthropogenic activities. Determining quantitative estimates of water balance and total basin discharge are of utmost importance to understand the variations within a basin. Hard-to-reach areas with few infrastructures, coupled with lengthy administrative procedures makes in-situ data collection and water management processes very difficult and unreliable. In this study, the hydrological behavior of Lake Chad whose extent, extreme climatic and environmental conditions make it difficult to collect field observations was examined. During a 10 year period [January 2003 to December 2013], dataset from space-borne and global hydrological models observations were analyzed. Terrestial water storage (TWS) data retrieved from Gravity Recovery and Climate Experiment (GRACE), lake level variations from Satellite altimetry, water fluxes and soil moisture from Global Land Data Assimilation System (GLDAS) were used for this study. Furthermore, we combined altimetry lake volume with TWS over the lake drainage basin to estimate groundwater and soil moisture variations. This will be validated with groundwater estimates from WaterGAP Global Hydrology Model (WGHM) outputs. TWS showed similar variation patterns Lake water level as expected. The TWS in the basin area is governed by the lake's surface water. As expected, rainfall from GLDAS precedes GRACE TWS with a phase lag of about 1 month. Estimates of groundwater and soil moisture content volume changes derived by combining altimetric Lake Volume with TWS over the drainage basin are ongoing. Results obtained shall be compared with WaterGap Hydrology Model (WGHM) groundwater estimate outputs.

• Proceedings of the Korea Water Resources Association Conference
• /
• 2017.05a
• /
• pp.471-471
• /
• 2017

최근 기상 이변으로 인해 홍수, 가뭄 등과 같은 수재해가 빈번히 발생되고 있다. 이에 수재해예방 등의 안전 기술과 관련된 관심이 증가되고 있다. 수재해 예방을 위해서는 먼저 홍수, 가뭄 등과 같은 수재해 감시가 필요하며, 이를 위해 위성, 레이더 등으로 관측된 자료를 활용한 수문인자 정보는 매우 중요하다. 미국 NASA의 LIS(Land Information System)는 위성 및 지상관측 자료를 활용하여 홍수, 가뭄, 기상, 산사태, 농업 등의 정보를 생산할 수 있는 프레임워크이다. LIS는 크게 지표면 모델 및 자료동화를 위한 변수들의 전처리 과정(LDT), 지표면 모델을 활용한 분석 및 자료동화 과정(LDAS) 및 분석된 자료의 검보정(LVT) 과정으로 구성되어 있다. LIS에서 산출 가능한 인자는 Energy Balance, Water Balance, Surface/Subsurface State, Evaporation, Hydrologic, Cold Season Processes, Compared Data, Carbon 등 9개로 분류되며 약 78개의 인자를 산출한다. 홍수, 가뭄 등과 같은 수재해 감시를 위한 수문인자는 강수량, 증발산량, 토양수분, 지표면 온도 등을 비롯한 여러 가지 인자들이 필요하다. LIS는 주로 미국, 캐나다 등 평활한 지역에 활용되어 공간해상도는 약 10km(0.1deg) 이하로 자료를 산출한다. 산악 지형이 대부분인 한국 지형에 적용하기에는 자료의 정확성이 낮아 10km 이상의 공간해상도 자료가 필요하며, 한국형 수재해정보 플랫폼에서 홍수, 가뭄 등의 기초자료로 사용하기 위한 수문인자의 선정이 필요하다. 이에 본 연구에서 NASA LIS를 통해 산출 가능한 인자를 정리하고 한국형 수재해 정보플랫폼에 활용 가능한 수문인자의 항목을 조사하였다. 홍수, 가뭄 등 수재해 분석에 필요한 기초자료는 강우량, 유출량, 잠재적 증발산량, 식생의 증산량, 토양수분, 표면온도, 알베도 등의 수문인자이며, NASA LIS에서 이와 같은 수문인자 산출이 가능하다. NASA와 국제공동 연구중인 한국형 물순환분석 프레임워크(K-LIS(안)) 개발을 통해 한국 지형에 적합한 홍수 및 가뭄 등의 수재해 감시 평가 예측이 가능할 것이며, K-LIS에서 산출되는 고해상도의 수문인자들을 수재해 정보 웹 포털의 정보 제공 서비스를 통하여 손쉽게 접근 가능할 것으로 사료된다.

• Journal of The Geomorphological Association of Korea
• /
• v.23 no.1
• /
• pp.117-128
• /
• 2016

High resolution aerial photographs and digital elevation models for Bangpo beach using UAV were generated in this study to analyze the thematic and geometric characteristics of coastal features. Based on 728 aerial images acquired on September 10, 2016 by the UAV, a image mosaic at 2.2 cm spatial resolution and a digital elevation model at 4.4 cm spatial resolution were developed. This study found out that Bangpo beach consisted of intertidal zone and supratidal zone. The intertidal zone can be subdivided into lower part and upper part with distinctive geomorphological characteristics. While the lower part included sand bars and ripple marks along the coastline, the cusps and sand dunes were the major coastal features of the upper part. Part of the intertidal zone was occupied by shore platform with average slope of 0.9 degree containing various sizes of gravels. The supratidal zone slanted toward ocean with berms on the surface with an interval of 15 m. These coastal features indicated the flow intensity towards to the land and tidal effect. It validated that the UAV application in coastal research was very effective analyzing to examine coastal processes.