• Korean Journal of Agricultural and Forest Meteorology
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• v.21 no.1
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• pp.1-28
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• 2019

This study analyzed the density and mortality rate of Korean fir at 9 sites where individuals of Korean firs were marked into the live and dead trees with coordinates on orthorectified aerial images by digital photogrammetric system. As a result of the analysis, Korean fir in each site showed considerable heterogeneity in density and mortality rate depending on the location within site. This make it possible to assume that death of Korean fir can occur by specific factors that vary depending on the location. Based on the analyzed densities and mortality rates of Korea fir, we investigated the correlation between topographic factors such as altitude, terrain slope, drainage network, solar radiation, aspect and the death of Korean fir. The density of Korean fir increases with altitude, and the mortality rate also increases. A negative correlation is found between the terrain slope and the mortality rate, and the mortality rate is higher in the gentle slope where the drainage network is less developed. In addition, it is recognized that depending on the aspect, the mortality rate varies greatly, and the mean solar radiation is higher in live Korean fir-dominant area than in dead Korean fir-dominant area. Overall, the mortality rate of Korean fir in Mt. Halla area is relatively higher in areas with relatively low terrain slope and low solar radiation. Considering the results of previous studies that the terrain slope has a strong negative correlation with soil moisture and the relationship between solar radiation and evaporation, these results lead us to infer that excess soil moisture is the cause of Korean fir mortality. These inferences are supported by a series of climate change phenomena such as precipitation increase, evaporation decrease, and reduced sunshine duration in the Korean peninsula including Jeju Island, increase in mortality rate along with increased precipitation according to the elevation of Mt. Halla and the vegetation change in the mountain. It is expected that the spatial patterns in the density and mortality rate of Korean fir, which are controlled by topography such as altitude, slope, aspect, solar radiation, drainage network, can be used as spatial variables in future numerical modeling studies on the death or decline of Korean fir. In addition, the method of forest distribution survey using the orthorectified aerial images can be widely used as a numerical monitoring technique in long - term vegetation change research.

• Proceedings of the Korea Water Resources Association Conference
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• 1988.07a
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• pp.85-92
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• 1988

A model for the transient one-dimensional moisture movement in the saturated-unsaturated zone using a finite difference method is developed. Hysteresis in the soil water retention is incorporated. The model considers layered geologic formations. Monte Carlo simulation, together with the nearest neighbor model is used. Outputs of the model include pressure head, water content, and the water table elevation. Two Monte Carlo simulations of 100 realizations each are made for a 12-day simulation period with different input values. The simulation results show that the S.D. of the outputs increases with an increase in the input, the S.D. of the log K$$. The model is applied to predict a long term water table fluctuation, and the predicted water table agress well with the observed one.

• Korean Journal of Agricultural and Forest Meteorology
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• v.18 no.1
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• pp.30-41
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• 2016

The temporal variation of soil water storage is important in hydrological modeling. In order to evaluate an antecedent wetness state, the antecedent precipitation index (API) has been used. The aim of this article is to compare observed soil water storage with APIs calculated by widely used four equations, to configure the relationship between soil water storage and API by a regression model for one-year(2009), and to predict the soil water storage for the next two years(2010~2011). The soil water storage was evaluated from the observed soil moisture dataset in soil depths of 10, 30, 60cm at 21 locations by TDR measurement system for 3 years. As a result, API with the exponential function among the four equations can describe the variation of the observed soil water storage. Monthly optimized parameters of the API's equations seemed to be roughly related with the (potential) evapotranspiration (PET). Using revised monthly optimized parameters of APIs considering the seasonal pattern of PET, we characterize the relationship between API and the observed soil water storage for one year, which looks better than those of other researches.

• Journal of Korean Society of Forest Science
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• v.85 no.2
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• pp.210-224
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• 1996

The SLODSVAT consists of interrelated submodels that simulate : the transfer of radiation, water vapour, sensible heat, carbon dioxide and momentum in two canopy layers determined by environmental conditions and ecophysiological properties of the vegetation ; uptake and storage of water in the "root-stem-leaf" system of plants ; interception of rainfall by the canopy layers and infiltration and storage of rain water in the four soil layers. A comparison of the results of modeling experiments and field micro-climatic observations in a spruce forest(Picea abies [L].Karst) in the Soiling hills(Germany) shows, that the SLODSVAT can describe and simulate the short-term(diurnal) as well as the long-term(seasonal) variability of water vapour and sensible heat fluxes adequately to natural processes under different environmental conditions. It proves that it is possible to estimate and predict the transpiration and evapotranspiration rates for spruce forest ecosystems on the patch and landscape scales for one vegetation period, if certain meteorological, botanical and hydrological information for the structure of the atmospheric boundary layer, the canopy and the soil are available.

• Proceedings of the Korea Water Resources Association Conference
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• 2009.05a
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• pp.630-634
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• 2009

최근 산림지 및 조림지역에의 축산 분뇨 액비 처리가 자연순환농업의 일환으로써 하나의 대안으로 대두되고 있는데 액비처리에 의한 환경영향, 특히 수분 및 영양성분 수지의 불균형을 초래하여 수질 오염 및 토양에 과잉 영양분을 축적할 우려가 있어 이에 수질에 미치는 영향에 대한 모니터링과 분석 시행함으로써 적용의 문제점 및 대책 방안 도출이 필요할 것으로 판단된다. 따라서 본 연구에서는 산림 유역에서 SCB액비 처리에 따른 지하수에 미치는 영향을 살펴보기 위하여 지하수의 수질 모니터링을 실시하였다. 질산태 질소 중심으로 SCB액비 처리에 의한 지하수의 수질 영향을 분석하고, 질소 동위원소비를 이용하여 지하수의 질산태 질소 오염원을 판별하였다. 그 결과 바이오순환림이 액비처리에 의해 지하수 하류부에서 질산태 질소가 증가하는 경향을 나타내었는데, 이는 질소 동위원소비 분석 결과, 액비로부터 침출된 것으로 분석되었다. 반면에 유휴지의 경우, 액비 시용으로 인한 지하수 수질 영향은 거의 없는 것으로 나타났다. 추후 SCB액비 시용에 따른 산림유역에 대해서 지속적인 모니터링과 샘플링을 실시하여 다양한 항목에 대한 조사 및 분석을 이루어진다면 조림지와 같은 산림지역에서의 SCB액비 시용에 따른 수질 영향 모델링 및 모형 구축의 기초 자료로 사용할 수 있을 것으로 판단된다.

• Proceedings of the Korea Water Resources Association Conference
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• 2011.05a
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• pp.471-471
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• 2011

2012년 가축분뇨 해양투기가 전면 금지됨에 따라 가축분뇨의 자원화의 필요성이 대두되고 있다. 하지만 현재 가축분뇨 발생량의 일부는 퇴비화로 농경지로 환원되고 있으며, 지역에 따라 일부 지역에서는 농경지면적 대비 가축분뇨 필요량을 초과하는 것으로 나타나, 산림지 및 조림지역으로의 가축분뇨 환원이 새로운 대안중 하나로 대두되고 있다. 특히, SCB (Slurry Composting and Biofiltration) 액비는 성분이 비교적 균질하고 저농도이며 냄새가 없어 산림유역에 시비가 가능할 것으로 판단된다. 하지만, 액비 시비량에 따라 수분 및 영양성분 수지 불균형 등을 초래하여 토양에 축적될 우려가 있고, 지하수로 침출될 가능성이 있어 이에 대한 모니터링이 필요할 것으로 판단된다. 따라서 본 연구에서는 산림유역 중 백합나무 조림지인 바이오순환림과 포플러 조림지인 유휴지에 SCB액비를 시용하였을 때 지하수에 미치는 영향을 살펴보기 위하여 매주 지하수 수질 모니터링을 실시하였다. 특히, 청색증 등을 유발시켜 지하수 오염의 지표인 질산성질소를 중심으로 지하수 수질 분석을 하였으며 질산성질소의 오염원을 판단하기 위하여 질소 동위원소비를 분석하였다. 시험림의 물리적 특성이 다른 두 산림유역에서의 SCB액비 시용에 따른 지하수 모니터링 결과는 향후 지속적인 모니터링이 이루어진다면 산림지에서 SCB액비 시용에 따른 수질영향 평가 및 모델링 기초 자료로 활용될 수 있을 것으로 판단된다.

• Proceedings of the Korea Water Resources Association Conference
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• 2016.05a
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• pp.320-320
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• 2016

본 연구에서는 자연환경, 수생태환경과 관련된 모니터링자료 및 수문/수질 SWAT(Soil and Water Assessment Tool) 모델링 자료를 이용하여 유역건전성을 평가하기 위한 지수를 개발하고, 한강유역($34,148km^2$)을 대상으로 표준유역단위 유역건전성 평가를 수행하였다. 본 연구에서는 미국 EPA(Environmental Protection Agency)의 유역건전성 분석 사례를 개선하여 우리나라에 유역 특성에 맞는 통합 유역건전성 평가지수를 개발하였다. 본 연구에서 분석하고자 하는 유역건전성은 유역이 본래 가지고 있는 자연적인 건전성을 평가하고자 하는 것으로, 평가를 위한 지표로 자연토지피복, 하천환경, 수문, 수질, 서식지, 수생태 관련 요소를 각각 선정하였다. 자연토지피복 및 하천, 서식지 유역건전성 평가를 위해서 DEM, 토지이용도, 하천도, 저수지, 습지자료를 이용하였고, 수생태 유역건전성 평가를 위해서는 6년간(2008년~2013년) 모니터링 된 TDI, BMI, FAI 자료로 이용하였다. 수문/수질 유역건전성 평가를 위해서는 SWAT 모형의 장기모의 결과를 활용하였으며, 30년간(1985년-2014년) 모의된 강수량, 총유출, 지표유출, 침투, 토양수분, 중간유출, 침루, 지하수 충진, 기저유출, Sediment, T-N, T-P 결과를 이용하였다. 각 평가지표로부터 표준유역별 sub-index를 도출하였으며, 6가지 sub-index를 이용하여 통합 유역건전성 지수를 산정하였다. 산정된 지수는 0부터 1까지의 값으로 나타나며, 1에 가까울수록 유역건전성이 좋은 유역을 의미한다. 연구결과 한강유역의 통합 유역건전성은 상류에서 하류로 갈수록 건전성이 안 좋아지는 것으로 분석되었으며, 특정 표준유역에 대하여 자연환경, 수문, 수질, 수생태환경 각각의 유역건전성을 평가할 수 있었다.

• Journal of the Korean Society of Groundwater Environment
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• v.6 no.4
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• pp.188-193
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• 1999

Transport of pollutants in aquifer largely depends on groundwater flow which is governed by aquifer hydraulic parameters. Determination of these parameters and associated groundwater modeling become essential for adequate remediation of contaminate groundwater. The objective of this paper is to analyze groundwater flow and determine the optimum hydraulic parameters by performing groundwater modeling based on sensitivity analysis for unconfined sandy gavel aquifer constructed in a laboratory scale under various boundary condition. Results revealed that the simulated drawdown was lower than the observed drawdown irrespective of boundary conditions. and specific yield (S$_{y}$) had less effect on the grondwater flow than permeability (K) in the aquifer. Water balance analysis showed that the measured drawdown in neighboring observation wells during pumping was higher than either simulated or recovered water table. The indicated that a difference might exist in the water tables between aquifer and wells. The difference was investigated by time domain reflectometry (TDR) measurements on water contents in the region of water table and capillary fringe, and explained by a delayed response of water table during gravitational drainage as the water table was lowered as a result of pumping.g.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.24 no.6
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• pp.644-653
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• 2013

In this paper, a formulation for obliquely incident electromagnetic wave has been presented for an analysis of highpower electromagnetic pulse penetration into multilayered dispersive media. Based on generalized models of measured dielectric constants and propagation channels reflecting the Earth's general features, the propagation phenomenon of the obliquely incident early-time(E1) high altitude electromagnetic pulse(HEMP) is analyzed. In addition, the polarization and critical angle are also considered. It is found that the total reflection occurs at an incident angle of about 38 degrees at the soil-rock interface, and that the parallel-polarized E1 HEMP penetrates better than the perpendicular-polarized one. The peak level of the penetrating electric field is found to be 5.6 kV/m at normal incidence, regardless of the type of polarization, and E1 HEMP is greatly reduced near the critical angle. Moreover, the penetrating E1 HEMP is analyzed as a variation of moisture content and depth of materials, resulting E1 HEMP could be useful in determining the levels of shielding required for buried facilities.

• Korean Journal of Agricultural and Forest Meteorology
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• v.18 no.4
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• pp.307-319
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• 2016

A Land-Atmosphere Modeling Package (LAMP) for supporting agricultural and forest management was developed at the National Center for AgroMeteorology (NCAM). The package is comprised of two components; one is the Weather Research and Forecasting modeling system (WRF) coupled with Noah-Multiparameterization options (Noah-MP) Land Surface Model (LSM) and the other is an offline one-dimensional LSM. The objective of this paper is to briefly describe the two components of the NCAM-LAMP and to evaluate their initial performance. The coupled WRF/Noah-MP system is configured with a parent domain over East Asia and three nested domains with a finest horizontal grid size of 810 m. The innermost domain covers two Gwangneung deciduous and coniferous KoFlux sites (GDK and GCK). The model is integrated for about 8 days with the initial and boundary conditions taken from the National Centers for Environmental Prediction (NCEP) Final Analysis (FNL) data. The verification variables are 2-m air temperature, 10-m wind, 2-m humidity, and surface precipitation for the WRF/Noah-MP coupled system. Skill scores are calculated for each domain and two dynamic vegetation options using the difference between the observed data from the Korea Meteorological Administration (KMA) and the simulated data from the WRF/Noah-MP coupled system. The accuracy of precipitation simulation is examined using a contingency table that is made up of the Probability of Detection (POD) and the Equitable Threat Score (ETS). The standalone LSM simulation is conducted for one year with the original settings and is compared with the KoFlux site observation for net radiation, sensible heat flux, latent heat flux, and soil moisture variables. According to results, the innermost domain (810 m resolution) among all domains showed the minimum root mean square error for 2-m air temperature, 10-m wind, and 2-m humidity. Turning on the dynamic vegetation had a tendency of reducing 10-m wind simulation errors in all domains. The first nested domain (7,290 m resolution) showed the highest precipitation score, but showed little advantage compared with using the dynamic vegetation. On the other hand, the offline one-dimensional Noah-MP LSM simulation captured the site observed pattern and magnitude of radiative fluxes and soil moisture, and it left room for further improvement through supplementing the model input of leaf area index and finding a proper combination of model physics.