• Proceedings of the Korean Society of Organic Agriculture Conference
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• 2009.12a
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• pp.299-299
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• 2009

유기농업에서 유기자원을 이용하여 적정량의 양분을 공급하기 위해서는 먼저 유기자원의 무기화특성을 고려하여야 한다. 토성, 기온, 재배형태 등 다양한 요인을 고려하면서 무기화모델을 이용하여 유기농업에서 많이 사용되고 있는 유기질비료와 작물잔사 등을 대상으로 잠재 무기화가능 질소량(PMN, Potentially mineralizabe nitrogen)을 추정하였다. 실험은 실내에서 항온 배양하여 유기자원별 질소 무기화 양상을 분석함으로서 대상 유기자원의 PMN 및 무기화 속도를 도출하였다. 실험재료는 팜박, 피마자박, 팽화왕겨, 토마토, 수박, 감자, 마늘 등 7종을 대상으로 $20^{\circ}C,\;25^{\circ}C,\;30^{\circ}C$ 조건에서 하였으며, 최대수분보유량의 60% 수준으로 하여 사양토 및 식양토 조건에서 실험하였다. 유기자원은 토양 100g에 질소 30kg/10a 해당량을 시용하여 112일까지 항온하였다. 토성별 무기화량은 식양토 보다 사양토에서 다소 높은 경향을 보였다. 또한 항온온도가 높을수록 무기화량이 증가하였다. 유기자원별로는 피마자박에서 높았고, 팽화왕겨는 낮은 경향이었다. 유기자원이 처리된 것에서 토양 자체의 무기화량을 뺀 순무기화량은 피마자박, 토마토잔사, 감자잔사가 항온초기부터 무기화가 진행되었으며, 수박잔사, 마늘잔사는 항온 초기에 음의 값을 가지는 유기화 과정을 거친 후 항온 60일에서 80일 사이에서 무기화가 진행되었고 팽화왕겨의 경우 항온 11일까지 유기화가 계속되었다. PMN 및 무기화속도를 추정하기 위하여 반응속도식을 이용하였으며, 모델의 적합도를 높이기 위하여 이중지수모형을 이용하여 매개변수를 결정하고 무기화경향을 예측한 결과 PMN은 피마자박>마늘잔사=팜박>수박잔사=토마토잔사>감자잔사의 순이었다. 또한 유기자원의 무기화량과 C/N율과는 부의 상관관계($r^2$=0.8653)를 나타내었다. 요소의 PMN(135.6mg/kg)에 대한 유기자원별 PMN의 상대적 비율은 피마자박이 100%, 팜박과 마늘잔사가 81%, 토마토, 수박 및 감자잔사가 28~65% 수준이었다.

• Economic and Environmental Geology
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• v.53 no.3
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• pp.245-258
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• 2020

In this study, a data-driven response surface method using the results acquired from the numerical simulation is developed to evaluate the potential storage capacity of groundwater due to the construction of a groundwater dam. The hydraulic conductivities of alluvium and basement rock, depth and slope of the channel are considered as the natural conditions of the location for groundwater dam construction. In particular, the probability models of the hydraulic conductivities and the various types of geometry of the channel are considered to ensure the reliability of the numerical simulation and the generality of the developed estimation model. As the results of multiple simulations, it can be seen that the hydraulic conductivity of basement rock and the depth of the channel greatly influence to the groundwater storage capacity. In contrast, the slope of the channel along the groundwater flow direction shows a relatively lower impact on the storage capacity. Based on the considered natural conditions and the corresponding numerical simulation results, the storage capacity estimation model is developed applying an artificial neural network as the nonlinear regression model for training. The developed estimation model shows a high correlation coefficient (>0.9) between the simulated and the estimated storage amount. This result indicates the superiority of the developed model in evaluating the storage capacity of the potential location for groundwater dam construction without the numerical simulation. Therefore, a more objective and efficient comparison for the storage capacity between the different potential locations can be possibly made based on the developed estimation model. In line with this, the proposed method can be an effective tool to assess the optimal location of groundwater dam construction across Korea.

• Tunnel and Underground Space
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• v.31 no.4
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• pp.243-269
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• 2021

Since the early 2010s, the social importance of research and practical projects targeting deep geological disposal of high-level nuclear waste, underground CO₂ storage and characterization of deep subsurface by borehole investigation has been increasing. In this regard, there is also a significant increase in the need for in situ test technology to obtain quantitative and reliable information on the hydraulic characteristics of deep rock mass. Through years of research and development, we have independently set up Deep borehole Hydraulic Test System (DHTS) based on the key apparatuses designed and made with our own technology. Using this system, high precision constant pressure injection tests were successfully completed at the two 1 km boreholes located in Mesozoic granite and sedimentary rock regions, Gyeongju. During the field tests, it was possible to measure very low flow rate below 0.01 l/min with micro flow rate injection/control module. In this paper, the major characteristics of DHTS are introduced and also some results obtained from the high precision field tests under the deep and low permeable rock mass environment are briefly discussed.

• Economic and Environmental Geology
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• v.56 no.4
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• pp.435-445
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• 2023

A delta is a depositional landform that is formed when sediment transported by a river is deposited in a relatively low-energy environment, such as a lake, sea, or a main channel. Among these, a delta formed at the confluence of rivers has a great importance in river management and research because it has a significant impact on the hydraulic and sedimentological characteristics of the river. Recently, the equilibrium state of the confluence area has been disrupted by large-scale dredging and construction of levees in the Nakdong River. However, due to the natural recovery of the river, the confluence area is returning to its pre-dredging natural state through ongoing sedimentation. The time-series data show that the confluence delta has been steadily growing since the dredging, but once it reaches a certain size, it repeats growth and retreat, and the overall size does not change significantly. In this study, we developed a model to explain the sedimentation-erosion processes in the confluence area based on the assumption that the confluence delta reaches a dynamic equilibrium. The model is based on two fundamental principles: sedimentation due to supply from the tributary and erosion due to the main channel. The erosion coefficient that represents the Nakdong River confluence areas, was obtained using data from the tributaries of the Nakdong River. Sensitivity analyses were conducted using the developed model to understand how the confluence delta responds to changes in the sediment and water discharges of the tributary and the main channel, respectively. We then used annual average discharge of the Nakdong River's tributaries to predict the dynamic equilibrium positions of the confluence deltas. Finally, we conducted a simulation experiment on the development of the Gamcheon-Nakdong River delta using recorded daily discharge. The results showed that even though it is a simple model, it accurately predicted the dynamic equilibrium positions of the confluence deltas in the Nakdong River, including the areas where the delta had not formed, and those where the delta had already formed and predicted the trend of the response of the Gamcheon-Nakdong River delta. However, the actual retreat in the Gamcheon-Nakdong River delta was not captured fully due to errors and limitations in the simplification process. The insights through this study provide basic information on the sediment supply of the Nakdong River through the confluence areas, which can be implemented as a basic model for river maintenance and management.

• 한국신재생에너지학회:학술대회논문집
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• 2010.06a
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• pp.193.1-193.1
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• 2010

Small hydropower resources for five major river systems have been studied. The model, which can predict flow duration characteristic of stream, was developed to analyze the variation of inflow caused from rainfall condition. And another model to predict hydrologic performance for small hydropower(SHP) plants is established. Monthly inflow data measured at Andong dam were analyzed. The predicted results from the developed models in this study showed that the data were in good agreement with measured results of long term inflow at Andong dam. It was found that the models developed in this study can be used to predict the available potential and technical potential of SHP sites effectively. Based on the models developed in this study, the hydrologic performance for small hydropower sites located in river systems have been analyzed. The results show that the hydrologic performance characteristics of SHP sites have some difference between the river systems. Especially, the specific design flowrate and specific output of SHP sites located on North Han river and Nakdong river systems have large difference compared with other river systems.

• Resources Recycling
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• v.16 no.1 s.75
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• pp.68-72
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• 2007

The influences of reduction time, potential difference and ionic concentration flow rate have been investigated on the electrolytic recovery of silver from artificial photographic wastewater in continuous flow reactor system. As the initial concentration of silver ion and applied potential were increased, the amount of silver recovered was observed to be raised. Also, the electrolytically recovered material from artificial wastewater was proved to be pure silver based on the qualitative analyses by EPMA and XRD.

• Proceedings of the KIEE Conference
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• 2011.07a
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• pp.2112-2113
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• 2011

우리나라는 연평균 강수량이 1,245mm로써, 비교적 강수량이 풍부하고 전국토의 2/3가 산지로 구성되어 있어 지형적 및 수문학적으로 수력자원 부존량이 많은 편이다. 하지만 수력자원 활용을 통한 발전소 건설은 매우 미미한데 이는 수력발전소 개발지점이 제약되어 있고 개발지점의 가동율 또한 매우 낮아 경제성 확보가 어렵기 때문이다. 수력발전은 전력수요 급증 시 부하 평준화 효과와 석유 수입대체 및 환경 친화적인 에너지원이라는 장점이 있다. 따라서 국산화된 수차발전시스템의 사용으로 초기투자비를 낮추고 하천형 수력발전소 건설을 통하여 가동율을 높인다면 우리나라의 수력발전사업은 크게 활성화 될 것이다. 본 논문에서는 하천형 수력발전소 시공사례를 통하여 주요 시공사례를 소개하고, 하천공사의 특징으로 인하여 설계 및 시공 시 반영해야 할 사항에 대해 몇 가지 소개하였다. 표준화를 통하여 건설비용을 절감, 발전 단가의 기준가격 현실화를 통한 재정적인 지원 및 법규 정비를 통한 제도적인 도움 이 세가지를 해결한다면 경쟁력 있는 소수력발전소 건설이 가능 할 것이다.

• 한국태양에너지학회:학술대회논문집
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• 2011.04a
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• pp.235-240
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• 2011

Small hydropower resources for five major river systems have been studied. The model, which can predict flow duration characteristic of stream, was developed to analyze the variation of inflow caused from rainfall condition. And another model to predict hydrologic performance for small hydropower(SHP) plants is established. Monthly inflow data measured at Andong dam were analyzed. The predicted results from the developed models in this study showed that the data were in good agreement with measured results of long term inflow at Andong darn. It was found that the models developed in this study can be used to predict the available potential and technical potential of SHP sites effectively. Based on the models developed in this study, the hydrologic performance for small hydropower sites located in river systems have been analyzed. The results show that the hydrologic performance characteristics of SHP sites have some difference between the river systems. Especially, the specific design flowrate and specific output of SHP sites located on North Han river and Nakdong river systems have large difference compared with other river systems.

• Resources Recycling
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• v.1 no.1
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• pp.51-57
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• 1992

The hydrochloric acid leaching has been studied as a fundamental experiment on the recovery of arsenic from arsenic-bearing copper slime in copper electrorefining. The slime is mainly composed of $\beta-Cu_3As$ Which is intermetallic compound of CU and As. And the minor components are $CU_2O$ and CusAs in the slime. The optimum conditions of leaching of the slime were found to be as follows : 6N hydrochloric acid, particle size passed through 140 mesh, leaching for 150 min at $60^{\circ}C$, ratio of HCI/slime of 3 to 1 ; where 98 percent of arsenic were leached out of the As-bearing slime.

• 한국방재학회:학술대회논문집
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• 2011.02a
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• pp.47-47
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• 2011

에너지자원이 부족하여 에너지 해외의존도가 약 80% 이상인 우리나라의 특성상 에너지 해외의존도를 경감시키고 에너지부족 상황을 안정시키기 위하여 국내의 부존에너지를 최대한 활용하는 것이 필요하다. 또한 지구온난화에 대처하는 범세계적인 규제에 대비하기 위하여, 청정에너지를 적극 개발하여 에너지자립도를 향상시켜야 한다. 신재생에너지 중 하나인 소수력은 친환경적인 청정에너지 중 하나로 다른 대체 에너지원에 비해 높은 에너지 밀도를 가지고 있어 개발 가치가 큰 부존자원으로 평가되고 있다. 그리고 소수력은 여러측면의 사회적 환경적 이점으로 최근에는 선진국에서도 매우 큰 관심을 끌고 있으며, 에너지 자원이 빈약하여 대부분 석유수입에 의존하는 우리나라는 지역에너지로 소수력을 적극 개발하여야 한다. 소수력 부존량이 풍부한 우리나라는 1982년에 소수력 개발 활성화 방안이 공표되면서부터 정부주도 하에 소수력 발전소 건설에 관한 연구를 적극적으로 지원하게 되었다. 대수력과 비교하여 소수력의 장점으로는 비교적 짧은 계획 및 시공기간, 낮은 투자비용, 개인이나 기업을 통한 투자참여, 주위 인력이나 자재를 이용한 쉬운 설치, 적은 환경적인 피해 등이 있다. 이와 같이 청정에너지 중 하나인 소수력의 개발과 활용을 위하여 IT 기술을 접목한 다양한 응용시스템 구축이 진행되고 있다. 특히, 한국에너지기술연구원에서는 신재생에너지 개발 및 보급 확대를 목표로 2006년에 신재생에너지 자원지도시스템을 구축하였으며, 이를 웹상에서 제공하고 있다. 소수력 발전시설의 적극적인 활용을 위해서는 초기설계시 장기유출 특성분석을 통해 해당유역의 수자원을 최대로 활용하고, 지형적인 요소를 이용하여 전기의 생산이 최대가 되도록 하는 최적설계가 이루어 져야 한다. 따라서 본 연구에서는 소수력 발전시설의 최적설계를 위해 한강수계 258개 표준유역 중 섬강합류점에 대하여 자원지도를 활용하여 연평균유량을 추정한 후 소수력 자원량을 산정하였고, 그 결과로 시설용량과 연간전기생산량은 각각 1,633kW, 6,224MWh로 산정되었다. 또한 유출량의 미계측 유역에서의 소수력 발전성능을 예측하기 위한 방법으로 Weibull 분포의 특성화 방법을 선택하여 그 적용성을 검토하였다. 섬강합류점 표준유역 내에 위치하고 있는 목계관측소, 앙성관측소에서의 10개년(1999~2008) 강우자료를 바탕으로 유황곡선을 작성하여 상관관계분석을 실시한 결과 목계관측소에서 0.994701, 앙성관측소에서 0.992616으로 관측치와 계산값이 상당히 유사한 것으로 나타났다.