• 지질공학
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• 제19권3호
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• pp.365-371
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• 2009

본 연구에서는 비점오염원의 효율적인 관리방안을 확립하기 위하여 단위재배지로부터의 오염물질 배출특성을 조사하였다. 무강우일수가 상대적으로 길었던 약 20%의 강우사상을 제외한 나머지 강우사상에 대해서는 강우량과 강우에 의한 유출수량의 상관성은 상관계수 0.92로 매우 높았으며, 유출수량이 유출계수에 미치는 영향인자로는 유출직전의 강우강도가 주요인자임을 알 수 있었다. 한편, 유출수로부터 발생하는 오염물질의 EMCs(유량가중평균농도)가 높은 강우사상의 결과로 무강우일수가 길었던 강우사상에서 무강우에 의해 건조된 토양의 영향에 기인한 것임을 알 수 있다. 유출수로부터 발생되는 TSS, BOD, COD, TN 및 TP 등의 부하량은 동일한 강우사상에서 유사한 경향을 나타내므로 부유물질을 제어함으로써 다른 오염물질의 제거도 가능할 것으로 추정된다. 따라서 강우량계급별 유출계수 만을 이용한 오염물질부하량은 많은 오차를 나타낼 것이며, 오염부하 예측시스템을 개발할 때에는 강우량, 무강우일수, 선행강우량 등을 인자로 고려한 재배지토양조건을 충분히 고려하여야 할 것이다.

• 생태와환경
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• 제51권1호
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• pp.135-147
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• 2018

In order to investigate the runoff characteristics of nonpoint source pollutants in the Lake Doam watershed, water quality and flow rate were monitored for 38-rainfall events from 2009 to 2016. The EMC values of SS, COD, TN and TP were in the range of 33~2,169, 3.5~56.9, 0.09~7.65 and $0.06{\sim}2.21mg\;L^{-1}$, respectively. As a result of analyzing the effect of rainfall factor on the nonpoint source pollutant load, EMCs of SS, COD and TP showed a statistically significant correlation with rainfall (RA) (p<0.01) and SS showed highly significant correlation with maximum rainfall intensity (MRI, R=0.48). The load ranges of SS, COD, TN and TP were 10.4~11,984.6, 1.1~724.4, 0.6~51.6 and $0.03{\sim}22.85ton\;event^{-1}$, respectively, showing large variation depending on the characteristics of rainfall events. The effect of rainfall on the load was analyzed. SS, COD and TP showed a positive correlation, but TN did not show any significant correlation. The annual load of SS was the highest with $88,645tons\;year^{-1}$ in 2011 when rainfall was the highest with 1,669 mm. The result of impact analysis of nonpoint source pollution reduction project and land-use change on runoff load showed that pollutant load significantly reduced from 2009 to 2014 but SS and TP loads were increased from 2014 to 2016 due to increase in construction area. Therefore, we suggested that nonpoint source pollution abatement plan should be continued to reduce the soil loss and pollutants during rainfall, and countermeasures to reduce nonpoint source pollution due to construction need to be established.

• 항공우주시스템공학회지
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• 제18권3호
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• pp.17-26
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• 2024

항공기 엔진은 비행 중 고온, 고압과 터빈 축의 회전으로 인한 응력이 발생한다. 이러한 하중으로 인해 구조 내/외부에 미세한 균열이 발생할 수 있다. 이는 구조적 결함으로 이어져 부품의 수명에 악영향을 줄 수 있다. 이러한 현상을 사전에 방지하고자 균열에 대한 유한요소해석이 진행된다. 하지만 이 과정은 반복적인 균열 모델링이 이루어져 많은 시간과 노력을 수반한다. 그러므로 본 논문에서는 유한요소모델 기반의 균열 모델링 기법을 개발하였다. 균열 모델링에는 점 간의 연결에 제한을 가지고 공간을 삼각 분할하는 Constrained Delaunay Triangulation(CDT)을 사용하였다. 반타원 균열을 가지는 평판과 원통형 용기에 대한 응력확대계수 비교를 통해 기법을 검증하였으며, 균열 해석에 유용함을 보였다.

• Asian Pacific Journal of Cancer Prevention
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• 제16권7호
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• pp.2889-2894
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• 2015

Background: To investigate the impact of the breast size, shape, maximum heart depth (MDH), and chest wall hypotenuse (the distance connecting middle point of the sternum and the length of lung draw on the selected transverse CT slice) on the volumetric dose to heart with whole breast irradiation (WBI) of left-sided breast cancer patients. Materials and Methods: Fifty-three patients with left-sided breast cancer undergoing adjuvant intensity-modulated radiotherapy (IMRT) were enrolled in the study. The primary breast size and shape, MHD and DCWH (chest wall hypotenuse) were contoured on radiotherapy (RT) planning CT slices. The dose data of hearts were obtained from the dose-volume histograms (DVHs). Data were analyzed by one-way analysis of variance (ANOVA), Student's t-test and linear regression analysis. Results: Breast size was independent of heart dose, whereas breast shape, MHD and DCWH were correlated with heart dose. The shapes of breasts were divided into four types, as the flap type, hemisphere type, cone type and pendulous type with heart mean dose being $491.8{\pm}234.6cGy$, $752.7{\pm}219.0cGy$, $620.2{\pm}275.7cGy$, and $666.1{\pm}238.0cGy$, respectively. The flap type of breasts shows a strong statistically reduction in heart dose, compared to others (p=0.008 for V30 of heart). DCWH and MHD were found to be the most important parameters correlating with heart dose in WBI. Conclusions: More attention should be paid to the heart dose of non-flap type patients. The MHD was found to be the most important parameter to correlate with heart dose in tangential WBI, closely followed by the DCWH, which could help radiation oncologists and physicsts evaluate heart dose and design RT plan in advance.

• 한국방재안전학회논문집
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• 제16권4호
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• pp.19-31
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• 2023

미래 기후 시나리오에 따르면 우리나라 자연재해의 주요 요인인 태풍의 강도는 강해질 것으로 전망된다. 태풍 강도 증가는 내습 파고 상승으로 이어져 주거, 산업, 관광 등의 용도로 인구 및 건물 밀집도가 높은 연안 지역의 대규모 피해발생 가능성이 높은 상황이다. 따라서 본 연구에서는 동해 해양기상부이 관측자료를 분석하여 최대 유의파고가 나타난 태풍 마이삭(202009) 내습 기간에 대해 파랑추산 수치모형실험을 수행하였다. 파랑추산실험 경계조건은 JMA-MSM의 바람장과 SSP5-8.5 미래 기후 시나리오의 태풍 중심기압 감소율을 적용한 바람장을 사용하였다. 파랑추산실험 결과 SSP5-8.5 시나리오에서 속초항 방파제 전면에서의 파고는 4.06 m에서 4.68 m로 15.27% 증가하였다. 또한, 심해설계파 147-2 격자점 위치에서의 재현빈도는 최소 2배 이상 증가하는 것으로 산출되어, 현재 해안구조물 설계 시 관행적으로 적용하는 50년 재현빈도 심해설계파에 대한 제고가 필요하다.

• 한국환경생태학회지
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• 제33권5호
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• pp.605-619
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• 2019

본 연구는 합천호에서 2002~2017년까지 16년간의 장기간 동안 수질변수를 이용하여 부영양화 특성, 경험적 모델분석 및 몬순강도에 따른 수질변이 특성을 분석하였다. 장기간의 연별 수질 분석에서 합천호는 중영양~부영양 상태로 분석되었고, 계절별 수질분석에서 부영양화 현상은 하절기 이후 심화되는 것으로 나타났다. 장기간의 수질변이 특성은 유역의 점오염원 및 비점 오염원이 크게 변하지 않는 상황 하에서 매년 강우 사상 (집중 강우 vs. 약한 강우) 및 계절적인 강우강도에 의해 조절되는 것으로 분석되었다. 총인(TP), 총질소(TN), 생물학적 산소요구량(BOD) 및 이온 농도변화는 건기해(Dry year)와 홍수해 (Wet year)의 비교분석에서 뚜렷한 차이를 보여 영양염류, 유기물 농도 및 이온농도 변동에 가장 중요한 역할을 하는 것으로 분석되었다. 특히, 수질 변수 중 매년 영양염 지표(TP, TN), 유기물 지표(BOD, COD), 총 부유물질 농도 및 1차생산력의 지표 (Chl-a)는 강수량과 정 상관관계를 보였다. 녹조의 지표인 Chl-a 농도는 총인, 총질소, 및 BOD와 높은 상관관계를 보여, 타 호수처럼 영양염의 과도한 증가시기에 Chl-a농도가 낮아지는 특성과는 차이를 보였다. Log-전환된 총질소, 총인 및 Chl-a에 대한 경험적 모델(Empirical model) 분석에 따르면, Chl-a 농도는 인(phosphorus) 농도에 의해 1차적으로 조절되며, 질소(N)농도는 유의한 영향을 주지 않는 것으로 나타났다. 이는 $Log_{10}TN$, $Log_{10}TP$, $Log_{10}CHL$의 상류, 중류, 하류구간에 대한 공간적 회귀분석에서 총인과 Chl-a는 p <0.005의 유의적인 상관관계를 나타내었으나 총질소와 Chl-a는 p > 0.005의 결과를 보여, 녹조번성에 대해 인(P)이 핵심역할을 하는 것으로 분석 되었다. 또한, 총질소와 총인 모두 Chl-a와 댐에 가까운 하류구간(Lacustrine zone)에 비해 상류구간(Riverine zone)에서 더 유의적인 결과를 보여, 상류역에서 무기성 부유물의 농도의 영향에 의한 광제한 효과(Light limitation)가 거의 나타나지 않는 것으로 분석되었다.

• 생태와환경
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• 제55권4호
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• pp.320-329
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• 2022

Urban areas in watersheds increase the impervious surface, and agricultural areas deteriorate the water quality of rivers due to the use of fertilizers. As such, anthropogenic land use affects the type, intensity and quantity of land use and is closely related to the amount of substances and nutrients discharged to nearby streams. Riparian vegetation reduce the concentration of pollutants entering the watershed and mitigate the negative impacts of land use on rivers. This study analyzes the data through correlation analysis and regression analysis through point data measured twice a year in spring and autumn in 21 selected damaged tributary rivers within the Han River area, and then uses a structural equation model to determine the area land use. In the negative impact on water quality, the mitigation effect of riparian vegetation was estimated. As a result of the correlation analysis, the correlation between the agricultural area and water quality was stronger than that of the urban area, and the area ratio of riparian vegetation showed a negative correlation with water quality. As a result of the regression analysis, it was found that agricultural areas had a negative effect on water quality in all models, but the results were not statistically significant in the case of urban areas. As a result of the model estimated through the structural equation, BOD, COD, TN, and TP showed a mitigation effect due to the accumulation effect of river water quality through riparian vegetation in agricultural areas, but the effect of riparian vegetation through riparian vegetation was found in urban areas. There was no These results were interpreted as having a fairly low distribution rate in urban areas, and in the case of the study area, there was no impact due to riparian forests due to the form of scattered and distributed settlements rather than high-density urbanized areas. The results of this study were judged to be unreasonable to generalize by analyzing the rivers where most of the agricultural areas are distributed, and a follow-up to establish a structural equation model by expanding the watershed variables in urban areas and encompassing the variables of various factors affecting water quality research is required.

• 한국농공학회지
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• 제22권4호
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• pp.108-114
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• 1980

A deterministic conceptual erosion model which simulates detachment, entrainment, transport and deposition of eroded soil particles by rainfall impact and flowing water is presented. Both upland and channel phases of sediment yield are incorporated into the erosion model. The algorithms for the soil erosion and sedimentation processes including land and crop management effects are taken from the literature and then solved using a digital computer. The erosion model is used in conjunction with the modified Kentucky Watershed Model which simulates the hydrologic characteristics from watershed data. The two models are linked together by using the appropriate computer code. Calibrations for both the watershed and erosion model parameters are made by comparing the simulated results with actual field measurements in the Four Mile Creek watershed near Traer, Iowa using 1976 and 1977 water year data. Two water years, 1970 and 1978 are used as test years for model verification. There is good agreement between the mean daily simulated and recorded streamflow and between the simulated and recorded suspended sediment load except few partial differences. The following conclusions were drawn from the results after testing the watershed and erosion model. 1. The watershed and erosion model is a deterministic lumped parameter model, and is capable of simulating the daily mean streamflow and suspended sediment load within a 20 percent error, when the correct watershed and erosion parameters are supplied. 2. It is found that soil erosion is sensitive to errors in simulation of occurrence and intensity of precipitation and of overland flow. Therefore, representative precipitation data and a watershed model which provides an accurate simulation of soil moisture and resulting overland flow are essential for the accurate simulation of soil erosion and subsequent sediment transport prediction. 3. Erroneous prediction of snowmelt in terms of time and magnitute in conjunction with The frozen ground could be the reason for the poor simulation of streamflow as well as sediment yield in the snowmelt period. More elaborate and accurate snowmelt submodels will greatly improve accuracy. 4. Poor simulation results can be attributed to deficiencies in erosion model and to errors in the observed data such as the recorded daily streamflow and the sediment concentration. 5. Crop management and tillage operations are two major factors that have a great effect on soil erosion simulation. The erosion model attempts to evaluate the impact of crop management and tillage effects on sediment production. These effects on sediment yield appear to be somewhat equivalent to the effect of overland flow. 6. Application and testing of the watershed and erosion model on watersheds in a variety of regions with different soils and meteorological characteristics may be recommended to verify its general applicability and to detact the deficiencies of the model. Futhermore, by further modification and expansion with additional data, the watershed and erosion model developed through this study can be used as a planning tool for watershed management and for solving agricultural non-point pollution problems.

• 한국태양에너지학회 논문집
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• 제31권3호
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• pp.8-16
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• 2011

The objective of this study is to analyze the characteristic of thermal environment in the summer season by conducting the field observation of temperature, relative humidity, and globe temperature in some parts of the city. Observation point was divided to a densely populated area, a residential area, a green area, a waterfront green area and a suburban district by the distribution ratio of green area. In this study, the correlation between maximum temperature and globe temperature, study on index for intensity of the tropical night and the temperature distribution characteristic of measurement points by the distribution ratio of green area were analyzed. The results of this study are as follows. (1) The difference between temperature and globe temperature by the distribution ratio of green area is confirmed. The difference of nighttime is more clearly that of daytime. (2) The average temperature and globe temperature of the densely populated area($29.2^{\circ}C$, $33.7^{\circ}C$) are higher than that of the waterfront green area($27.9^{\circ}C$, $32.0^{\circ}C$) by $1.3^{\circ}C$ and $1.7^{\circ}C$, respectively. (3) The number of tropical nights has different days of tropical nights by the distribution ratio of green area of 17days for the Daegu weather station, 14days for adensely populated area, 14days for a residential area, 6days for a green area, 2days for a waterfront green area, and 2days for a suburban district. (4) The results of the slope of trend line for the effects of the temperature on globe temperature change and the intercept for the size of the impact of radiant energy gained around by the analysis of the correlation between the maximum temperature and globe temperature can be utilized objective evaluation index of the each point's artificial effects.

• 지질공학
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• 제20권4호
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• pp.401-407
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• 2010

농업지역에서 발생한 오염부하량을 결정하기 위해 여러 토지이용형태 중에서 벚나무 재배지(단위 비점오염원)에서 발생하는 오염부하 특성을 조사하였다. 유출시 발생된 강우사상에서는 강우량과 유출수량의 상관계수가 0.5로 낮게 나타나 투수성을 예측할 수 없는 수준이었다. 강우량 20mm 미만인 경우에도 강우강도가 8.8 mm/hr 수준으로 높은 경우에는 유출이 발생하였으나 강우량이 47.4 mm로 많은 경우라 할지라도 긴 무강우일수와 약한 강우강도를 보인 경우에는 유출이 발생하지 않았다. 강우사상시 발생된 유출량과 SS, BOD, COD, TN 및 TP 오염부하량과의 상관계수는 SS에서 최저값 0.71을 보인 것 이외에는 모두 r ${\geq}$ 0.92로 매우 유의한 값을 나타냈다. 한편 SS와 다른 오염물질간의 오염부하상관성도 모두 r ${\geq}$ 0.73의로 유의한 값을 나타내었으므로 SS관리를 통해 유기물질과 영양염에 대한 제어도 가능함을 알 수 있다. 최고 TN농도는 시비활동에 의해 직접적 영향을 받은 Event의 유출수에서 발생하였다. 따라서 농경지에서 발생하는 유출수의 오염수준을 평가할 때에는 시비여부를 반드시 고려해야 할 것이다.