• Title/Summary/Keyword: 한국 지형학회

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The Geomorphology and the Sediment Characteristics of Sagye Coastal Dune, Jeju Island, Korea (제주도 사계 해안사구의 지형과 퇴적물 특성)

  • Seo, Jong-Cheol;Sohn, Myung-Won
    • Journal of the Korean association of regional geographers
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    • v.12 no.6
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    • pp.631-644
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    • 2006
  • The study area is a pocket beach which consisted of sandy beach, dune, agricultural land and residential area etc. The coastal dune area is classified to foredune, dune plain, secondary (or back) dune. The foredune area is covered by herbaceous dune plants(ex. Carex kobomugi, Wedelia prostrata, etc.), whereas the dune plain area is covered by herbs and shrubs(Vitex rotundifolia). The most inner area, secondary dune, is planted by pine forest(Pinus thunbergii). The mean size of the beach and dune sediments ranges from 1.1 to $1.8{\Phi}$, which mean these values are higher than normal sediments. Sorting and Skewness is $0.6{\sim}-1.2{\Phi}$ and $-2.7{\sim}1.6{\Phi}$ respectively. We found that the soil formation process in the secondary dune area has been progressed rapidly from the analysis of fine grain content, organic matter content, and CEC.

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A Study on the Distribution and Change of Montane Meadows in the East Face of Mt. Baekdu (백두산 동사면 산지초지 분포와 변화에 관한 연구)

  • Kim, Nam-Sin
    • Journal of the Korean association of regional geographers
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    • v.18 no.4
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    • pp.364-373
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    • 2012
  • This study is to analyze distribution and change of montane meadows on the lava plateau in the east face of Mt. Baekdu. Process for aims carried out field survey, and analyzed landsat images of 1993, 1999, 2004, and year 2010. After research findings, the area of forests has increased by 33% from $636km^2$ to $848km^2$, montane meadow has decreased by 58% from $303km^2$ to $127km^2$ during 18 years. Montane meadows could be classified as 2 categories of wet meadow and dry meadow by the geomorphic environments and vegetation types. Wet meadow has decreased by 30%, dry meadow has decreased by 70% in the same period. Decreasing areas are replacing meadows with forests in invasion by trees and shrubs. According to the analysis with weather data for 16 years from 1993 to 2008, temperature has increased by $1.6^{\circ}C$, on the other hand, precipitation has decreased by 5.3mm. These kinds of climate change trends continue in the future, it could be change montane meadows into tree types.

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Evaluation of Regression Models in LOADEST to Estimate Suspended Solid Load in Hangang Waterbody (한강수계에서의 부유사 예측을 위한 LOADEST 모형의 회귀식의 평가)

  • Park, Youn Shik;Lee, Ji Min;Jung, Younghun;Shin, Min Hwan;Park, Ji Hyung;Hwang, Hasun;Ryu, Jichul;Park, Jangho;Kim, Ki-Sung
    • Journal of The Korean Society of Agricultural Engineers
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    • v.57 no.2
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    • pp.37-45
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    • 2015
  • Typically, water quality sampling takes place intermittently since sample collection and following analysis requires substantial cost and efforts. Therefore regression models (or rating curves) are often used to interpolate water quality data. LOADEST has nine regression models to estimate water quality data, and one regression model needs to be selected automatically or manually. The nine regression models in LOADEST and auto-selection by LOADEST were evaluated in the study. Suspended solids data were collected from forty-nine stations from the Water Information System of the Ministry of Environment. Suspended solid data from each station was divided into two groups for calibration and validation. Nash-Stucliffe efficiency (NSE) and coefficient of determination ($R_2$) were used to evaluate estimated suspended solid loads. The regression models numbered 1 and 3 in LOADEST provided higher NSE and $R_2$, compared to the other regression models. The regression modes numbered 2, 5, 6, 8, and 9 in LOADEST provided low NSE. In addition, the regression model selected by LOADEST did not necessarily provide better suspended solid estimations than the other regression models did.

An Uncertainty Analysis of Topographical Factors in Paddy Field Classification Using a Time-series MODIS (시계열 MODIS 영상을 이용한 논 분류와 지형학적 인자에 따른 불확실성 분석)

  • Yoon, Sung-Han;Choi, Jin-Yong;Yoo, Seung-Hwan;Jang, Min-Won
    • Journal of The Korean Society of Agricultural Engineers
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    • v.49 no.5
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    • pp.67-77
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    • 2007
  • The images of MODerate resolution Imaging Spectroradiometer (MODIS) that provide wider swath and shorter revisit frequency than Land Satellite (Landsat) and Satellite Pour I' Observation de la Terre (SPOT) has been used fer land cover classification with better spatial resolution than National Oceanic and Atmosphere Administration/Advanced Very High Resolution Radiometer (NOAA/AVHRR)'s images. Due to the advantages of MODIS, several researches have conducted, however the results for the land cover classification using MODIS images have less accuracy of classification in small areas because of low spatial resolution. In this study, uncertainty of paddy fields classification using MODIS images was conducted in the region of Gyeonggi-do and the relation between this uncertainty of estimating paddy fields and topographical factors was also explained. The accuracy of classified paddy fields was compared with the land cover map of Environmental Geographic Information System (EGIS) in 2001 classified using Landsat images. Uncertainty of paddy fields classification was analyzed about the elevation and slope from the 30m resolution Digital Elevation Model (DEM) provided in EGIS. As a result of paddy classification, user's accuracy was about 41.5% and producer's accuracy was 57.6%. About 59% extracted paddy fields represented over 50 uncertainty in one hundred scale and about 18% extracted paddy fields showed 100 uncertainty. It is considered that several land covers mixed in a MODIS pixel influenced on extracted results and most classified paddy fields were distributed through elevation I, II and slope A region.

Analysis of the Difference of Flow Duration Curve according to the Cumulative Variation of the Daily Average Flow in Unit Watershed for TPLCs (총량관리 단위유역 일평균유량의 시계열 누적 변화에 따른 유량지속곡선 차이 분석)

  • Hwang, Ha-sun;Rhee, Han-pil;Seo, Ji-yeon;Choi, Yu-jin;Park, Ji- hyung;Shin, Dong-seok;Lee, Sung-jun
    • Journal of The Korean Society of Agricultural Engineers
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    • v.60 no.6
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    • pp.97-109
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    • 2018
  • The LDC (Load Duration Curve) method can analyze river water quality changes according to flow rate and seasonal conditions. It is also possible to visually recognize whether the target water quality is exceeded or the size of the reduction load. For this reason, it is used for the optimal reduction of TPLCs and analysis of the cause of water pollution. At this time, the flow duration curve should be representative of the water body hydrologic curve, but if not, the uncertainty of the interpretation becomes big because the damaged flow condition is changed. The purpose of this study is to estimate the daily mean flow of the unit watershed using the HSPF model and to analyze the difference of the flow duration curves according to the cumulative daily mean flow rate using the NSE technique. The results show that it is desirable to construct the flow duration curve by using the daily average flow rate of at least 5 years although there is a difference by unit watershed. However, this is the result of the water bodies at the end of Han River basin watershed, so further study on various water bodies will be necessary in the future.

Effect of Artificial Structures on the Long-Term Topographic Changes at Daehang-ri Intertidal Flat, the West Coast of Korea (인공구조물에 의한 대항리 갯벌의 장기 지형변화)

  • Choi, Tae-Jin;Jeong, Eui-Young;Yang, Young Jin;Choi, Jin-Yong
    • Journal of The Korean Society of Agricultural Engineers
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    • v.62 no.2
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    • pp.75-82
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    • 2020
  • The Daehang-ri intertidal flat located the just outside of the Saemangeum dike has been reported to show new-developing flats. Based on the topographic surveys of 21 times from 2000 to 2016 by a leveling method every year, this site clearly shows variation of deposition/erosion in time and space. Deposition has consistently occurred at the rate of +3.75 cm per year at the area along the dike (Zone 1), and this tidal flat is expanding and prograding seaward. In the area of far from the dike (Zone 2), on the other hand, erosion prevails at the rate of -2.38 cm per year, and this zone tends to retreat landward. However, the erosional trend of Zone 2 has slightly slowed down since 2014. As a whole from 2000 to 2016, net deposition is recorded over 3.0 m at the upper beach and the area adjacent to the dike (Zone 1), while erosion up to 1.0 m in Zone 2. In conclusion, the results at the Daehang-ri intertidal flat clearly revealed that its topographic changes were induced by the artificial structures and water masses through its sluice gate. Counter-clockwise gyre newly created after the sea dikes construction probably results in relocating of sediment outside the dike 1 by transportation of materials eroded from the south to the north along the coast.

Air Temperature Variation Affected by Site Elevation in Hilly Orchards (구릉지 과원의 고도에 따른 기온변이)

  • 정유란;서희철;윤진일
    • Korean Journal of Agricultural and Forest Meteorology
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    • v.5 no.1
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    • pp.43-47
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    • 2003
  • Air temperature was continuously measured in hilly pear orchards at 4 sites with elevations of 10, 49, 104 and 253 m above sea level. The mean air temperature, averaged over the 10-month period from August 2001 to June 2002, decreased as the site elevation increased by 0.2$^{\circ}C$ per 100 m. This weak lapse condition was amplified during daytime by sun-slope geometry. But on most days an inversion condition began by sunset and persisted until the next sunrise. During the observation period, daily minimum temperature at the valley bottom was lower than that of the hilltop on 67% of the days, and the average temperature difference was 1.4$^{\circ}C$. Inversion of daily minimum temperature under clear sky conditions was stronger in spring and autumn than in winter with a maximum of 6$^{\circ}C$. Lapse condition was predominant in daily minimum temperature on rainy days, and the lapse rate was strongest in winter.

Modeling of Water Circulation and Suspended Sediment Transport in Lake Daecheong (대청호내 흐름 및 유입 부유사 확산 모델링)

  • Jung Tae Sung;Hwang Jung Hwa
    • Journal of the Korean Society for Marine Environment & Energy
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    • v.6 no.4
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    • pp.67-82
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    • 2003
  • A 2-dimensional hydrodynamic model has been applied to understand water circulation pattern in Lake Deacheong. The simulation results have been used in sediment transport modeling. A sediment transport model using a particle tracking method has been developed to simulate sediment transport in the ocean, river and reservoir. The model was applied to estimate transport track of particulate pollutants in the lake. The hydrodynamic model was verified for water level variations and showed good agreements. Through the results we found out that water velocity is less than 5 cnysec for mean yearly flow and more than 120 cnysec at some points for the simulated flood flow. The incoming sediment particles in flood season reached into the Daecheong Dam. But the incoming sediment particles in the mean flow were settled down at riverbed and didn't move into the dam. These results can be used in setting up water quality management plan in the lake.

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Growth Characteristic of Warm-season Turfgrass in Saemangeum Reclaimed Land (새만금간척지에서 난지형 잔디의 생육 특성)

  • Bae, Eun-Ji;Han, Jeong-Ji;Lee, Kwang-Soo;Park, Yong-Bae;Choi, Su-Min
    • Journal of the Korean Society of Environmental Restoration Technology
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    • v.19 no.1
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    • pp.13-23
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    • 2016
  • This study was conducted to investigate the growth characteristics of warm-season turfgrasses and to find out suitable turfgrass species on Saemangeum reclaimed land. Twenty native zoysiagrass(Zoysia sinica, Z. matrella, Z. japonica, Medium-leaf type zoysiagrass(hybrid zoysiagrass)) and bermudagrass(Cynodon dactylon) collected from Korea were used in this study. Total stolon length and the number of stolon per square meter, relative growth rate of shoot and stolon, and coverage rate were analyzed for 2 year. C. dactylon showed not only the most growth response with high relative growth rate of shoot and stolon, which were 19.9% and 66.3%, but also resulted in higher level of turf visual quality compared to others. Whereas Z. japonica showed the least growth response with low relative growth rate of shoot and stolon, which were 2.4% and 0.7%. Although all warm-season turfgrasses took root and grew up well, there were different growth rates between the interspecies. Z. sinica 'Z2034', Z. matrella 'Z4091', Z. japonica 'Z1064', Medium-leaf type zoysiagrass 'ZN6019' and C. dactylon 'BN7014' were the greatest growth rate of shoot and stolon. These results will be useful for selecting salt tolerant breeding lines and also used to develop a turfgrass cultivar with strong salinity tolerance through continuous monitoring.

Simulation Study on Liquid Air Energy Storage (LAES) System using Dual Refrigeration Cycles and Thermal Oil Circulation (냉매사이클과 열매체유 순환을 활용한 액화공기에너지저장 시스템 공정모사 연구)

  • Jang, Soonnam;Park, Jongpo
    • Journal of the Korean Institute of Gas
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    • v.22 no.4
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    • pp.63-73
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    • 2018
  • Innovative technical process for Energy Storage System (ESS), Liquid Air Energy Storage system (LAES) is mature technologies based on the gas liquefaction process. In spite of many advantages such as high energy density, no geographical constraints, low investment costs and long useful life, the system has not yet widely commercialized due to low round trip efficiency. To improve RTE and acquire high yield of liquid air, various configurations of LAES process have been considered. In this research, dual refrigerants cycle (R-600a and methanol) for air liquefaction and thermal oil circulation for power generation via liquid air gasification have been applied to improve cycle performance significantly using Aspen HYSYS simulator.