• Journal of Korea Water Resources Association
• /
• v.53 no.12
• /
• pp.1081-1095
• /
• 2020

This study is to evaluate stream flow and water quality changes of Yeongsan river basin (3,371.4 km2) by inter-basin water transfer (IBWT) from Juam dam of Seomjin river basin using SWAT (Soil and Water Assessment Tool). The SWAT was established using inlet function for IBWT between donor and receiving basins. The SWAT was calibrated and validated with 14 years (2005 ~ 2018) data of 1 stream (MR) and 2 multi-functional weir (SCW, JSW) water level gauging stations, and 3 water quality stations (GJ2, NJ, and HP) including data of IBWT and effluent from wastewater treatment plants of Yeongsan river basin. For streamflow and weir inflows (MR, SCW, and JSW), the coefficient of determination (R2), Nash-Sutcliffe efficiency (NSE), root mean square error (RMSE), and percent bias (PBIAS) were 0.69 ~ 0.81, 0.61 ~ 0.70, 1.34 ~ 2.60 mm/day, and -8.3% ~ +7.6% respectively. In case of water quality, the R2 of SS, T-N, and T-P were 0.69 ~ 0.81, 0.61 ~ 0.70, and 0.54 ~ 0.63 respectively. The Yeongsan river basin average streamflow was 12.0 m3/sec and the average SS, T-N, and T-P were 110.5 mg/L, 4.4 mg/L, 0.18 mg/L respectively. Under the 130% scenario of IBWT amount, the streamflow, SS increased to 12.94 m3/sec (+7.8%), 111.26 mg/L (+0.7%) and the T-N, T-P decreased to 4.17 mg/L (-5.2%), 0.165 mg/L (-8.3%) respectively. Under the 70% scenario of IBWT amount, the streamflow, SS decreased to 11.07 m3/sec (-7.8%), 109.74 mg/L (-0.7%) and the T-N, T-P increased to 4.68 mg/L (+6.4%), 0.199 mg/L (+10.6%) respectively.

• Korean Journal of Remote Sensing
• /
• v.40 no.2
• /
• pp.229-241
• /
• 2024

With the advancement of big data processing technology using cloud platforms, access, processing, and analysis of large-volume data such as satellite imagery have recently been significantly improved. In this study, the Change Detection Method, a relatively simple technique for retrieving soil moisture, was applied to the backscattering coefficient values of pre-processed Sentinel-1 synthetic aperture radar (SAR) satellite imagery product based on Google Earth Engine (GEE), one of those platforms, to estimate the surface soil moisture for six observatories within the Yongdam Dam watershed in South Korea for the period of 2015 to 2023, as well as the watershed average. Subsequently, a correlation analysis was conducted between the estimated values and actual measurements, along with an examination of the applicability of GEE. The results revealed that the surface soil moisture estimated for small areas within the soil moisture observatories of the watershed exhibited low correlations ranging from 0.1 to 0.3 for both VH and VV polarizations, likely due to the inherent measurement accuracy of the SAR satellite imagery and variations in data characteristics. However, the surface soil moisture average, which was derived by extracting the average SAR backscattering coefficient values for the entire watershed area and applying moving averages to mitigate data uncertainties and variability, exhibited significantly improved results at the level of 0.5. The results obtained from estimating soil moisture using GEE demonstrate its utility despite limitations in directly conducting desired analyses due to preprocessed SAR data. However, the efficient processing of extensive satellite imagery data allows for the estimation and evaluation of soil moisture over broad ranges, such as long-term watershed averages. This highlights the effectiveness of GEE in handling vast satellite imagery datasets to assess soil moisture. Based on this, it is anticipated that GEE can be effectively utilized to assess long-term variations of soil moisture average in major dam watersheds, in conjunction with soil moisture observation data from various locations across the country in the future.

• Korean Journal of Soil Science and Fertilizer
• /
• v.29 no.2
• /
• pp.124-129
• /
• 1996

This experiment has been conducted to find out a effective decomposition method of popped rice hulls which are hard to be decomposed in vitro. It was found that the C/N ratio of 35 was better than the C/N ratio of 20 for improving the decomposition ratio of popped rice hulls. The addition of rice bran accelerated the decomposition of popped rice hulls. The real decomposition rate of popped rice hulls for 10 days was merely 8 percent. This poor decomposition ratio seemed to be come from the chemical constituent of rice hull which has 20 percent of silica content. It was considered that the addition of rice bran speeded up only the decomposition of bran itself by increasing the number of microorganisms. It was also observed that color changes developed from the decomposition of rice hulls proved not to be a yardstick for the degree of decomposition.

• Journal of the Korean Geophysical Society
• /
• v.5 no.4
• /
• pp.293-303
• /
• 2002

Applying elastic plate model, we estimated elastic thickness and rigidity of the lithosphere in southern part of the Korean Peninsula($332km{\times}332km$ area of which center is $36.5^{\circ}N$ in latitude and $127.5^{\circ}E$ in longitude) by analysing terrain data and gravity data measured up to 2002. We tried to exclude the East Sea in choosing the study area because it has different tectonic environment. The mean Moho depth was estimated to be 30 km by power spectrum analysis of gravity data in the study area, Assuming one layer crust and applying elastic plate model, the loads with wavelengths of greater than 300 km are locally compensated, loads with wavelengths in the range 80-300km are partially supported by the strength of the lithosphere, and loads with wavelengths of less than 80km are almost completely supported by lithospheric strength. Assuming crustal model and rigidity, we calculated predicted coherence and compared it with observed coherence. As a result, we wert able to estimate the effective elastic thickness to be of 15 km(corresponding flexural rigidity is $3.0{\times}10^{22}Nm$). This indicates that the crust of the study area is relatively weaker than other old and stable continental regions but is similar to continental margins or oceanic area. The low rigidity could be explained by many tectonic and thermal activities such as orogenic activities, magmatic intrusions, volcanic activities, foldings, faultings, etc.

• Korean Journal of Fisheries and Aquatic Sciences
• /
• v.33 no.1
• /
• pp.25-31
• /
• 2000

In order to investigate the composition, seasonal and regional variation of extractive nitrogenous components in the raw anchovy (Engraulis japonica) harvested from June 1991 to June 1992 at Nam-hae and Ki-jang in the southern coast of Korea, the contents of extractive nitrogen (EN), free amino acids (FAA), oligopeptides (OP), ATP and its related compounds (ARC), quaternary ammonium bases, and guanidino compounds were measured. The EN contents of raw anchovy were $444{\~}773\;mg/100\;g$. Thirty-four kinds of FAA were found and their total amount were $1,049{\~}2,079\;mg/100\;g$. Histidine, taurine, alanine, leucine and glutamic acid were the major free amino acids in the anchovy extracts. The amount of ARC was average $5.02\;{\mu}mol/g$, and IMP was the major compound among them, who and creatine contents in the extracts or raw anchovy were average 164 and 229 mg/100 g, respectively. The contents of glycinebetaine,${\brta}-alaninebetaine,\;{\gamma}-burobetaine$, homarine, TMA, and creatinine were extremely small. As for the regional and seasonal disparities, the Nam-hae samples contained more EN, FAA, OP, betaines and creatine than the Ki-jang samples. On the other hand the Ki-jang samples contained more ARC and TMAO. The spring samples contained more EN, FAA, OP, ARC and betaines than the autumn samples. On the other side the autumn samples contained more TAMO and creatine.

• Journal of Korean Society of Coastal and Ocean Engineers
• /
• v.17 no.3
• /
• pp.149-157
• /
• 2005

Typical water quality (WQ) parameters defined in the governing equation of the WQ model are the pollutant loads from atmosphere and watersheds, pollutant release rates from sediment, diffusion coefficient and reaction coefficient etc. The direct measurement of these parameters is very difficult as well as requires high cost. In this study, the pollutant budget equation including these parameters was used to construct the linear simultaneous equations. Based on these equations, the inverse problems were constructed and WQ parameter estimation method minimizing the sum of squared errors between the computed and observed amounts of the mass changes was suggested. WQ parameters, i.e., the atmospheric pollutant loads, sediment release rates, diffusion coefficients and reaction coefficient, were estimated using .this method by utilizing the vertical concentration profile data which has been observed in Cheonsu Bay and Ulsan Port. Values of the estimated parameters show a large temporal variation. However, this technique is persuasive in that the RHS (root mean square) error was less than $5.0\%$ of the observed value ranges and the agreement index was greater than 0.95.

• Journal of Korean Society of Environmental Engineers
• /
• v.22 no.2
• /
• pp.341-353
• /
• 2000

The purpose of this study is to investigate the characteristics of pollutants overflow on storm events and the first flush analysis in industrial complex. Eight sub-basins in the Chongju industrial complex were selected for sampling and study with different characteristics during the period from June 1997 to August 1998. Water quality parameters of stormwater runoff such as $BOD_5$, COD, SS, TKN, $NO_3-N$, $PO_4-P$, TP, n-Hexane extracts, Cr, Cu, Pb and Fe were analyzed. During the storm events, measured concentration ranges of $BOD_5$, COD, SS, $NO_3-N$, TKN, $PO_4-P$, TP, r-Hexane extracts, Cr, Cu, Pb and Fe were 2~324 mg/L, 5~810 mg/L, 1~1,110 mg/L, 0.01~10.89 mg/L, 0.1~59.8 mg/L, 0.08~7.02 mg/L, 0.1~7.8 mg/L, 0.1~1,723.6 mg/L, 0.001~0.363 mg/L, 0.001~0.488 mg/L, 0.001~1.28 mg/L, and 0.26~18.91 mg/L, respectively in the industrial complex watersheds. And a quantitative of first flush has been presented. First flush occurs more frequently as the ratio of impervious area increases.

• Journal of the Korea institute for structural maintenance and inspection
• /
• v.9 no.4
• /
• pp.119-126
• /
• 2005

The objective of this paper is to evaluate the flexural tensile strength of unreinforced concrete masonry wall to ensure the structural safety in out-of-plane behaviors under the wind or earthquake loads. Flexural tensile strength of unreinforced concrete masonry wall has been obtained from the full scale tests of total 327 specimens and the statistical analysis are performed for each of the cases. The flexural tensile strength derived from experiments is classified as 13 groups according to masorny units, mortar ingredients, and the direction of tensile stresses and the mean tensile strength and the variable coefficient are obtained for each case. The uniform and concentrated transverse loads have been applied over the face of the wall specimens. The ultimate mean flexural tensile strengths are distributed from 1,564 kPa to 363 kPa according to masonry units, mortar ingredients, and other factors. The allowable flexural tension stress criteria will be established based on the mean flexural tensile strengths in the future.

• 한국신재생에너지학회:학술대회논문집
• /
• 2010.11a
• /
• pp.120-120
• /
• 2010

에너지 절약적 차원에서 한 대의 실외기에 다수의 실내기가 접속되는 개별공조형 멀티 열펌프에 관한 연구 및 개발과 보급이 증대되고 있다. 본 연구에서는 복수의 실내기를 갖고 가변속 압축기를 채용한 지열원 물대공기 멀티열펌프시스템을 학교 현장에 설치하여 제조사의 운전 제어 알고리즘에 따라 일일 냉난방 실증 성능 특성을 분석하였다. 2008년 9월 30일의 냉방부하가 낮은 일자에 대하여 시간에 따른 부하 변동에 따라 압축기의 용량가변으로 실내기 냉방용량은 정격용량 대비 17.1%에서 111.3%의 범위에서 변이되었으나, 열펌프 유닛의 일일 최대 COP는 6.2를 나타냈으며, 일일 평균 열펌프 유닛 COP는 4.5로 열펌프 유닛 인증 기준 이상의 성능을 나타냈다. 2008년 11월 10일 대비 2008년 12월 15일에는 시스템 가동 중의 평균 외기온도가 $9.6^{\circ}C$ 감소하였으나, 각 재실공간의 용도별 부분 부하특성으로 11월 10일 보다 난방 부하량이 작게 나타났다. 하지만, 12월 15일에는 부하량이 매우 작아서 11월 10일보다 잦은 압축기 가변에 따른 손실로 일일 평균 COP가 낮게 나타났다. 2009년 1월 12일에는 정격 용량대비 94%의 부하율로 11월 10일과 12월 15일 대비 4배 이상의 부하량으로 압축기 용량 가변율이 작아서 난방용량과 COP 변화율이 작게 나타났다. 2009년 1월 12일에는 지중순환수의 실외열교환기 유입온도가 2008년 12월 15일보다 감소하고, 시스템의 난방용량 증가로 상대적으로 응축기와 증발기 크기가 감소한 효과로 히트펌프 유닛 COP가 감소하였으나, 본 지열원 열펌프 제조사에서 생산하고 있는 본 지열원 시스템과 동일한 압축기 등을 채용한 동일 용량의 공기열원 열펌프의 1월 12일 외기온도 $-10^{\circ}C$에서의 열펌프 유닛 COP 대비 70% 우수한 성능을 나타냈다. 본 지열원 히트펌프의 2008년 11월 10일의 일일 평균 히트펌프 유닛 COP는 외기온도가 낮고 일일 부하량이 크게 나타난 1월 12일의 일일 평균 히트펌프 유닛 COP 대비 37% 높게 나타났으나, 지중순환펌프의 정속운전으로 시스템 요구 지중순환수 유량 증가에 따른 성능 향상보다 소비전력 증가 영향이 커서 1월 12일의 시스템 COP 보다 33.3% 작은 값을 나타냈다. 본 연구의 용량 가변형 압축기를 채용한 지열원 멀티 히트펌프 유닛을 지열원 냉난방 시스템의 히트펌프 유닛으로 사용할 경우 시스템 최적화를 통한 시스템 COP 향상과 연간에너지 절감을 이루기 위해서는 히트펌프의 용량 변화 시에 지중순환펌프의 순환 유량 최적화를 위한 효율적 운전 제어 알고리즘 개발이 요구된다.

• Journal of the Korea Institute of Building Construction
• /
• v.9 no.5
• /
• pp.127-133
• /
• 2009

It is important to increase the strength of binders in order to enhance the strength of concrete. However, when the mineral admixture used for high strength concrete is incorporated individually, its dispersibility decreases due to the phenomenon of compaction, which reduces its fluidity and results in insufficient strength being created. To solve this problem, we can pre-mix each binder in advance to disperse a mineral admixture among binders, which will strengthen the fluidity and strength of concrete. Therefore, this study analyzed the properties of high strength concrete depending on the mix method used, to determine the effect of pre-mix cements ranging from W/B 15 to 35%. It was found that the fluidity of pre-mix increased to a level higher than that of individual mix due to its dispersion and ball bearing effect. The air content was slightly decreased from the result of individual mix due to the micro filler effect, which causes fine particles of silica-fume to fill the voids among cement particles, while the setting time of pre-mix was shorter than that of individual mix, because enhanced dispersion of pre-mix affects hydration heat time. The compressive strength of pre-mix increased due to the phenomenon of compaction of gap structure, and the variation of coefficient decreased by 1.69% on average in strength variation.