• 물과 미래
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• 제29권3호
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• pp.187-195
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• 1996

남한강 상류 평창강 유역을 대상으로 기상레이더 자료와 지상강우량 자료를 이용한 시우량 곡면 예측 방법을 연구하였다. 레이더 자료의 이용시에 필요한 비정상 에코와 지형에코의 제거, 강우에 의한 감쇄 효과의 보정 방법, 레이더 반사도 Z와 강우강도 R의 관계, 등을 검토분석하였다. 보정된 레이더 반사도 자료를 레이더 우량곡면으로 변환하고, 그 결과와 지상강우량 자료를 이용하여 시우량곡면을 합성하였다. 시우량곡면 예측을 위하여 상호상관 계수법을 이용한 강우장의 이동성과 유역 평균 레이더 강우강도의 시변성을 고려하였다. 이 예측방법을 합성된 시우량곡면 자료에 적용하여 3시간까지의 시우량곡면을 예측하고, 예측된 결과를 지상우량 및 합성우량 곡면과 비교하였다. 본 연구의 단시간 강우예측 방법은 보다 많은 자료를 이용한 검증과 강우장의 물리적 특성 및 지형을 고려한 방법으로의 보완이 필요한 것으로 사료되었다.

• 한국지형학회지
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• 제24권3호
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• pp.83-103
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• 2017

Sand deposit with shell units is exposed in Hasa-ri, Yeonggwang-gun, Jeonnam province. We investigated the characteristics of sand sediment topography in the Yeonggwang coastal area to collect evidence of the paleo-environmental change. We performed analysis on particle characteristics, chemical composition, and the age of deposition of sediments. The deposit comprise moderately well sorted medium and fine sand ($1.00{\sim}2.19{\varphi}$). Various sedimentary structures can be observed. Geochemical characteristics change by depth and the degree of variation with depth is small. The results obtained from OSL dating show that sand layers below shell units are deposited 0.32-0.43 ka. As the elevation of the shell unit far mean high water levels or highest high water level, the extensive shell layers could only have been deposited during storm surge conditions. Aeolian processes are discounted due to the size of clasts and the location at which they occur. Results of age dating of the surrounding deposits indicate shell deposits formed after around 300 years age. There is a distinct difference between sedimentary layers including dark brown-black layer. The sedimentary characters such as particle size and geochemistry show difference with depth. It is presumed that depositional environmental in Hasa-ri has changed several times before. This study is expected to contribute to finding an evidence about occurrence of storm surges.

• 농촌계획
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• 제24권4호
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• pp.99-119
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• 2018

Unit load factor, which is used for the quantification of non-point pollution in watersheds, has the limitation that it does not reflect spatial characteristics of soil, topography and temporal change due to the interannual or seasonal variability of precipitation. Therefore, we developed the method to estimate a watershed-scale non-point pollutant load using seasonal forecast data that forecast changes of precipitation up to 6 months from present time for watershed-scale water quality management. To establish a preemptive countermeasure against non-point pollution sources, it is possible to consider the unstructured management plan which is possible over several months timescale. Notably, it is possible to apply various management methods such as control of sowing and irrigation timing, control of irrigation through water management, and control of fertilizer through fertilization management. In this study, APEX-Paddy model, which can consider the farming method in field scale, was applied to evaluate the applicability of seasonal forecast data. It was confirmed that the rainfall amount during the growing season is an essential factor in the non-point pollution pollutant load. The APEX-Paddy model for quantifying non-point pollution according to various farming methods in paddy fields simulated similarly the annual variation tendency of TN and TP pollutant loads in rice paddies but showed a tendency to underestimate load quantitatively.

• 한국수자원학회:학술대회논문집
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• 한국수자원학회 2015년도 학술발표회
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• pp.53-53
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• 2015

Basin-scale motions in a stratified lake rely on interactions of spatially and temporally varying wind force, bathymetry, density variation, and earth's rotation. These motions provide a major driving force for vertical and horizontal mixing of inorganic and organic materials, dissolved oxygen, storm water and floating debris in stratified lakes. In Lake Tahoe, located between California and Nevada, USA, basin-scale circulations are obviously important because they are directly associated with the fate of the suspended particulate materials that degrade the clarity of the lake. A three-dimensional hydrodynamic model, ELCOM, was applied to Lake Tahoe to investigate the underlying mechanisms that determine the characteristics of basin-scale circulations. Numerical experiments were designed to examine the relative effects of various mechanisms responsible for the horizontal circulations for two different seasons, summer and winter. The unique double gyre, a cyclonic northern gyre and an anti-cyclonic southern gyre, occurred during the winter cooling season when wind stress curl, stratification, and Coriolis effect were all incorporated. The horizontal structure of the upwelling and downwelling formed due to basin-scale internal waves found to be closely related to the rotating direction of each gyre. In the summer, the spatially varying wind field and the Coriolis effect caused a dominant anti-cyclonic gyre to develop in the center of the lake. In the winter, a significant wind event excited internal waves, and a persistent (2 week long) cyclonic gyre formed near the upwelling zone. Mechanism of the persistent cyclonic gyre is explained as a geostrophic circulation ensued by balancing of the baroclinc pressure gradient (or baroclinic instability) and Coriolis effect. Topographic effect, examined by simulating a flat bathymetry with constant depth of 300m, was found to be significant during the winter cooling season but not as significant as the wind curl and baroclinic effects.

• 한국전기전자재료학회논문지
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• 제34권5호
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• pp.314-320
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• 2021

Controlling ambient humid condition through high performance humidity sensors has become important for various fields, including industrial process, food storage, and the preservation of historic remains. Although aerosol deposited humidity sensors using ceramic BaTiO₃ (BT) material have been widely studied because of their longtime stability, there remain critical disadvantages, such as low sensitivity, low linearity, and slow response/recovery time in case of the sensors fabricated at room temperature. To achieve superior humidity sensing properties even at room temperature condition, BT-Cu composite films utilizing aerosol deposition (AD) process have been proposed based on the percolation theory. The BT-Cu composite films showed gradually improved sensing properties until the Cu concentration reached 15 wt% in the composite film. However, the excessive Cu (above 30 wt%) containing BT-Cu composite films showed a rapid decrease of the sensing properties. The results of observed surface morphology of the AD fabricated composite films, to figure out the metal filler effect, showed correlation between surface topography as well as size and the amount of open pores according to the metal filler content. Overall, it is very important not only dielectric constant of the humidity sensing films but also microstructures, because they affect either the variation range of capacitance by ambient humidity or adsorption/desorption of ambient humidity onto/from the humidity sensing films.

• 인간식물환경학회지
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• 제24권5호
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• pp.469-483
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• 2021

Background and objective: If the Nelumbo nucifera spreads in a wetland at a high density, it can have considerable positive and negative ecological effects on habitats. For this reason, it is necessary to precisely investigate the impacts of its rapid proliferation. This study was conducted to propose the distribution and management of N. nucifera, which can cause the degradation of wildlife habitats due to the rapid spread of internal and external environmental factors that may affect the Junam wetland ecosystem. Methods: For the investigation and analysis of physical and ecological characteristics, factors of the abiotic environment such as general weather conditions, topography and water depth structure, and soil and water quality analysis, and bioenvironment characteristics such as changes in the N. nucifera community distribution were evaluated. To assess whether the differences in the soil depth and physicochemical characteristics between the N. nucifera community and the aquatic plant community are statistically significant, a One-way ANOVA was executed. Results: N. nucifera was presumably introduced in approximately 2007 and observed at a prevalence of only 0.8% in 2009, but had expanded to 11.1% in 2014. After that, the area was increased to 19.3% in 2015 and 40.0% in 2017, about twice that of the previous survey year. The rapid diffusion of an N. nucifera colony can have adverse effects on wildlife habitats and biodiversity at Junam Wetland. To solve these problems, four management methods can be proposed; water level management, mowing management, installation of posts and removal of lotus roots. Control of the N. nucifera community using these methods was judged to be suitable for cutting and water level management when considering expansion rate, water level variation, and wildlife habitat impacts. Conclusion: As the biotic and abiotic environmental factors are different for each wetland, it is necessary to determine the timing and method of management through a detailed investigation.

• Journal of Forest and Environmental Science
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• 제39권3호
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• pp.180-194
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• 2023

This study characterize, classify and evaluates the function of topography on spatial variability of some selected soil properties to assist in designing land management that support uniform agricultural production. The study site, an agricultural land, was part of the derived savanna zone in southwest Nigeria. Four soil profile pits each were established along two delineated toposequence and described following the FAO/UNESCO guidelines. Samples were collected from the identified genetic horizons. Properties of four soil series developed on different positions of the two delineated Toposequence viz upper, middle, lower slopes and valley bottom positions respectively were studied. The soil samples were analysed for selected physical and chemical properties and data generated were subjected to descriptive and inferential statistics. The results showed that soil colour, depth and texture varied in response to changes in slope position and drainage condition. The sand content ranged from 61 to 90% while the bulk density ranged between 1.06 g cm^-3 to 1.68 g cm^-3. The soils were neutral to very strongly acid with low total exchangeable bases. Available phosphorus value were low while the extractable micronutrient concentration varied from low to medium. Soils of Asejire and Iwo series mapped in the study area were classified as Typic isohyperthermic paleustult, Apomu series as Plinthic isohyperthermic paleustult and Jago series as Aquic psamment (USDA Soil Taxonomy). These soils were correlated as Lixisol, Plinthic Lixisol and Fluvisol (World Reference Based), respectively. Major agronomic constraints of the soils associations mapped in the study area were nutrient availability, nutrient retention, slope, drainage, texture, high bulk density and shallow depth. The study concluded that the soils were not homogenous, shows moderate spatial variation across the slope, had varying potentials for sustainable agricultural practices, and thus, the agronomic constraints should be carefully addressed and managed for precision agriculture.

• 한국농림기상학회지
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• 제11권1호
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• pp.13-18
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• 2009

기상대에서 측정한 '일적산수평면일사량'을 토대로 임의 경사면 상의 '일적산경사면일사량'을 비교적 정확하고 간편하게 알아낼 수 있는 지형보정계수를 고안하였다. 주어진 시간대의 수평면 청천일사량에 대한 경사면 청천일사량의 비율을 '매시일사보정계수'라 정의하고, 청천일사량을 기준으로 수평면의 시간대별 상대 일사강도와 수평면에 대한 경사면의 일사수광비율의 곱으로 표현하였다. 매시일사보정계수를 하루 단위로 적산한 것이 해당 날짜의 지형보정계수이다. 제주도 내 기생화산 '높은오름'의 등고도면 8 방위에서 사면일사수광량을 1년간 관측하는 한편, 이들 지점의 일사량을 지형보정계수에 의해 추정하여 서로 비교하였다. 지형보정계수에 의한 일사추정값의 편차평방근오차는 연평균 $1.61MJ\;m^{-2}$ 이었으나, 4월부터 10월 사이 영농기간에는 절반 이하로 줄어들었다. 경사향에 무관하게 10월에 가장 오차가 작은 반면, 11월에는 경사향에 따른 오차의 변동폭이 가장 컸다. RMSE 값의 연중변동폭은 남향과 북향사면에서 가장 컸고, 남서-남동-북서사면 순으로 줄어들었다. 어떤 경사면이든 365일 동안의 지형보정계수를 한번만 계산해 두면 인근 기상대에서 관측한 임의 날짜의 전천일사량에 이 계수를 적용함으로써 그 날의 적산일사량을 실용적인 오차범위 내에서 추정할 수 있어 복잡지형의 일사수광량 분포를 용이하게 파악할 수 있다.

• 한국수산과학회지
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• 제28권5호
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• pp.677-697
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• 1995

우리나라, 일본, 러시아 해역에서 관측된 조위관측 자료에서 얻은 해수면의 장주기변화를 기상과의 관계로 분석해 본 결과, 기상의 효과는 해역에 따라 다르지만 전반적으로 해수면변화의 절반 정도를 설명해주는 것으로 나타났다 해수운동에 의하여 발생하는 해수면변화는 대마해류역에서 가장 크며 대마해류의 영향을 적게 받는 곳일수록 작아져 해수면변화가 대마해류와 관계 있음을 보여준다. 순압해수면 변화가 허용된 수치모델을 사용하여 해수면변화가 해수순환에 미치는 영향을 알아보았다. 그 결과 기본적인 해류형태는 Pang et al. (1993)에 의해 수행된 GCM (Semtner)모델의 결과와 같이 대만 주변 해역에서 지균형조정을 거친 후 등수심선을 따라 대한해협으로 흐르지만, 순압해수면 변화의 허용에 의해 일부 해수가 황해의 중앙을 따라 황해로 유입된 후 서해안을 따라 남하하여 유출되는 황해의 기본순환형태가 나타났다. 이와 함께 쿠로시오해류에 변화를 가할 때 순압해수면 변화에 의해 대륙붕에 장주기파동이 뚜렷해지며 이 파동으로 황해의 기본순환형태가 교란되어 해수가 서해안을 따라 북상하는 순환형태도 나타났다. 황해순환은 겨울철에는 기본순환형태가 북서 계절풍에 의해 강화되고 여름철에는 파동에 의해 교란된 순환구조에 남동계절풍이 합세하는 것으로 보인다. 장주기파동에 의해 나타나는 다른 특징은 대마해류 기원해역의 변화 가능성이다. 지금까지 대마해류의 기원해역은 크게 큐슈섬 남서해역과 대만 주변해역으로 대립되어 왔다. 그러나 이 연구결과는 이들은 서로 위배되는 것이라기 보다는 대마해류 기원의 중요한 두 해역이며 장주기파동에 의해 한쪽이 강화되어 나타나는 것을 보인다. 쿠로시오해류의 변화에 의해 대만 주변해역에 가해진 파동은 강제파로 대한해협으로 전파되며 대한해협에 이르러 일본연안의 파동은 동해로 계속 전파되는 반면, 우리나라 연안의 파동은 해저지형에 의해 반사하게 된다. 반사된 파동은 자유파로 동중국해 대륙붕을 따라 남서방향으로 진행하며 북동방향으로 진행하는 강제파와 더불어 동중국해의 해수면변화를 결정하게 된다.

• IUGG한국위원회:학술대회논문집
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• IUGG한국위원회 2003년도 정기총회 및 학술발표회
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• pp.20-20
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• 2003

In the summers of 1997 and 1998 and in February of 2000 we made 570 measurements of the ambient geomagnetic field 120 cm above the pavement surface of State Route 130, south of Pahoa, the island of Hawaii using a three-component fluxgate magnetometer. We measured at every 15.2 m (50 feet) interval covering a distance of 6, 310 m (20, 704 ft) where both historic and pre-historic highly magnetic basalt flows underlie. We also collected 197 core samples from eight road cuts, 489 specimens of which were subject to AF demagnetizations at 5 - 10 mT level up to a maximum field of 60 mT. We observed significant inclination anomalies ranging from a minimum of $31^{\circ}$ to a maximum $40^{\circ}$ where a uniform inclination value of $36.7^{\circ}$ (International Geomagnetic Reference Field, IGRF) was expected. Since the mean of the observed inclinations is approximately $35^{\circ}$ we assume that the study area is slightly affected by the magnetic terrain effect to a systematically shallower inclinations for being located in the regionally sloping surface of the southern side of the island (Baag, et al., 1995). We observed inclination anomalies showing wider (spacial) wavelength (160 - 600 m) and higher amplitudes in the historic lava flows area than in the northern pre-historic flows. Our observations imply that preexisting inclination anomalies such as those that we observed would have been interpreted as paleosecular variation (PSV). These inclination anomalies can best be attributed to concealed underground highly magnetic dikes, channel type lava flows, on-and-off hydrothermal activities through fissure-like openings, etc. Both the within- and between-site dispersions of natural remanent magnetization (NRM) are largest (up to ${\pm}7^{\circ}$) above the flows of 1955, while the area of pre-historic flows in the northern part of the study area exhibit the smallest dispersion. Nevertheless, mean inclinations of each historic flow of 1955 and 1790 are almost identical to that of the corresponding present field, whereas mean of NRM (after AF demagnetization) inclinations for each of the four pre-historic lava flow units is twelve to thirteen degrees lower than the present field inclination. We observed three cases of very large inclination variations from within a single flow, the best fitting curves of which are linear, second and third order polynomials each from within a single flow, whereas no present field variations are observed. This phenomena can be attributed to the notion that local magnetic anomalies on the surface of an active volcano are not permanent, but are transient. Therefore we believe that local magnetic anomalies of an active volcano may be constantly modified due to on going subsurface injections and circulations of hot material and also due to wide spacial and temporal distribution of highly magnetic basaltic flows that will constantly modify the topography which will in turn modify the local ambient geomagnetic field (Baag, et al., 1995). Our observations bring into question the general reliability of PSV data inferred from volcanic rocks, because on-going various geologic and geophysical activities associated with active volcano would continuously deflect and modify the ambient geomagnetic field.