• Journal of the Korean Geophysical Society
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• v.5 no.2
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• pp.153-161
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• 2002

In order t determine blasting sites for the crustal refraction studies in the korean peninsula, seismic refraction profiling was conducted at two sites in the reclaimed land of Seosan. At a quarry for construction material and another site on a rice field 2km east of the quarry, 24 channel refraction profiling of 46m was conducted at a geophone spacing of 2m. Seismic velocity profiles obtained through tomographic invesion reveal that the quarry is regarded as an ideal place for blasting based on the observation that fresh basements with seismic velocities of 3,900 m/s or greater locate approximately 6m deep. On the contrary, under the reclaimed rice field, the basements are weathered more, of slower velocities, and buried deeper than quarry, indicating not an ideal location for detonating seismic explosives of large amounts.

• Economic and Environmental Geology
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• v.54 no.5
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• pp.561-572
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• 2021

Aggregate collection is taking place in many areas in Korea, resulting in large cut slopes or large amounts of cut rocks. If the development site for such aggregate collection is a stratum accompanied by sulfide minerals, Acid Rock Drainage (ARD) may occur, which may cause environmental pollution in the development site and surrounding areas. As a result of the study on forest aggregate samples, most of the samples were classified as acid-forming potential samples, and among them, some samples from Gwangju, Goyang, and Sokcho were classified as potential acid-generating samples. This can be expected to affect the quality of aggregates when a large amount of aggregate is used in the future. Therefore, it is judged that these forest aggregates need to be managed when they are used. By predicting the occurrence of ARD through the acid-generating ability test, it is expected that economic losses that may occur in the future can be reduced, and it is judged that the problem of surrounding environmental pollution can be further alleviated.

• Journal of the Korean association of regional geographers
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• v.10 no.2
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• pp.341-355
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• 2004

This thesis is to analyze characteristic of sustainable development in the Nak-dong River. The results are summarized in the followings. 1) The principles which did not consider the equilibrium between development and environment, ecosystem, security. precautionary measure, equity could devise a plan, changes of economic land area, sand & gravel extractions from the riverbed, the river contamination cleanup, dam build 2) The rules which disregard polluter pay and opening participation in public affairs could input of too much province budget and manpower, project team. The measures to solve these problems could be proposed expansion of environmental infrastructure, sustainable sand & gravel extractions from the riverbed, fortifying the assistance of the residents who live in Dam construction site and the peripheral area of Dam, lower local fund rates in national projects, and the creation of management organization.

• Journal of Korea Water Resources Association
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• v.43 no.10
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• pp.921-932
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• 2010

In this study, the adjustment processes of the disturbed channels by sand or gravel mining were investigated by a two dimensional numerical model in the generalized coordinate system. As a numerical scheme, the CIP (cubic interpolated pseudoparticle method) method was used to calculate the advection term in the flow field and central difference method was used to the diffusion term in it. The pit of the channel was partially filled with sediment at the toe of the pit upstream. As time increased, the headcut erosion upstream in the pit was decreased due to the sediment inflow. The almost inflow sediment upstream was trapped into the pit and the sediment deposit wedge migrated downstream in the pit with the steep submerged angle of repose. The numerical model was reproduced well the evolution processes of the channel. The mining pit migrated with speed as the channel was steep, and the numerical results were in overall agreement with the experimental results.

• Journal of Korea Water Resources Association
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• v.48 no.1
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• pp.1-8
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• 2015

General features of sediment budget for the Nakdong River before the Four Rivers Restoration Project were analyzed using surveying, dredging, and mining data for the past 20 years, as well as sediment data measured from the tributaries, and numerical modeling, etc. As a result of the sediment budget analysis of the Nakdong River before the Four Rivers Restoration Project, sediment inflow supplied from the watershed is $2,100,000m^3/yr$ and sediment outflow including mining and dredging volumes is $10,180,000m^3/yr$. Therefore, the bed change volume estimated by the sediment budget analysis is $-8,080,000m^3/yr$ of the bed erosion volume which is similar to the analysis result ($-8,300,000m^3/yr$) of natural and artificial bed changes using the surveyed data.

• Journal of the Korean GEO-environmental Society
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• v.18 no.12
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• pp.5-11
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• 2017

The 19 mm-sized aggregate was produced by melting vinyl waste (waste polyethylene film) generated from vinyl greenhouses in rural areas. It was mixed with As'cone at various weight ratios, and then insulation effect test, tension test after repeated freezing and thawing, ice pull-out strength test and field density test were conducted for the mixtures. These results demonstrated that as the mixing ratio of polyethylene aggregate increased, the insulation effect increased, due to the many pore spaces that existed in the polyethylene aggregate. After repeatedly freezing and thawing As'cone, the tensile strength significantly increased at 2.5% of the polyethylene aggregate content rather than 0% of polyethylene aggregate content but it also slightly decreased at 5% and 10% of polyethylene aggregate content in comparison to 2.5% of its polyethylene aggregate content. As'cone added with polyethylene aggregate by 2.5% resulted in lower ice pull-out strength than that of normal As'cone. As a result of the porosity test for the samples taken at the site, porosity of the As'cone, which added polyethylene aggregate, was smaller than that of the general As'cone.

• Journal of the Korean Recycled Construction Resources Institute
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• v.6 no.1
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• pp.120-127
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• 2011

Recently, there are problems due to the exhaustion of natural aggregate resources, and strict restrictions. In this study, the possibility of using Water Granulated Ferro-Nickel slag as a substitutive material of fine aggregate is determined from the properties of mechanical and durability for the concrete that is made with Water Granulated Ferro-Nickel slag. According to the test results, when the mixing rate of Water Granulated Ferro-Nickel Slag aggregates concrete is adjusted, up to 50% of its aggregates by mixing rate can be mixed with general aggregates. The optimum mix ratio is considered to be 40%. The freezing and thawing resistance of Water Granulated Ferro-Nickel Slag aggregates concrete is identical to that of general aggregates concrete, while the carbonation resistance is found to be same as or lower than that of general aggregates concretes.

• Journal of the Korea Concrete Institute
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• v.28 no.4
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• pp.445-454
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• 2016

With the increase of decrepit facilities, construction waste increased to a certain level and now the increase is more or less stabilized. Yet construction waste still constitutes the largest portion of the overall wastes. Also, it is inevitable to spend a huge amount of the national budget due to the aggravating shortage of aggregate caused by prohibition on collection of natural aggregates as well as due to the damage to the land and environment caused by development of the sources of aggregates. As a countermeasure to the situation, the Ministry of Land, Infrastructure and Transport promulgated the quality standard for recycled aggregate to manage the usage of recycled aggregate according to its quality. But use of recycled aggregate for the purpose of high added value still remains nominal. Therefore, this research aims to study the applicability of recycled aggregate concrete as structural concrete by evaluating the quality improvement effects and the performance of the recycled aggregate concrete including recycled fine aggregate and recycled coarse aggregate that have undergone carbonation for 4 days and 14 days respectively in the condition of 60% RH, 20% $CO_2$ and $20^{\circ}C$ temperature, suggested for carbonation modifying from the advance research. The result shows carbonation modify contributed to quality improvement with 0.91% decrease in absorption rate for recycled fine aggregate and 0.7% decrease in absorption rate for recycled coarse aggregate. The physical properties and durability of the recycled aggregate made of aggregate modified by carbonation showed results similar to general concrete, which confirmed the possibility of applying the recycled aggregate made of recycled aggregate modified by carbonation to structural concrete.

• Resources Recycling
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• v.29 no.2
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• pp.18-27
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• 2020

Chemical experiment KS F 2545 and Physical experiment ASTM C 1260 has been accomplished to estimate the potential of alkali aggregate. Used for testing aggregate samples are forest aggregate and recycled aggregate which collected in Gangwon province Samcheok and Pyeongchang, Jeollabuk province Gimje and Kochang, and Gyeongsangnam province Goryeong. As the results of chemical experiment confirmed that if silicate rock and carbonate rock are mixed, reduction in alkalinity is increase. So it has been identified that case makes a disturb at the result of alkali aggregate reaction. In 9 out of the 62 aggregate samples check dissolved silica exceeding 100 mmol/ℓ. and mortar bar length increase rate confirmed that 5 of 9 chemical method aggregates were 0.1~0.2% and 2 aggregates were 0.2%. As a result of the alkaline aggregate reaction test using the chemical method and the mortar bar method, the aggregates showing alkali aggregate reaction are sandstone and tuff aggregates. Therefore, Alkali aggregate reaction tests are required to use clastic sedimentary rocks and volcanic pyroclastic rocks aggregates.

• Proceedings of the Korea Water Resources Association Conference
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• 2021.06a
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• pp.454-454
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• 2021

하천 환경에 대한 최근의 사회적 관심은 하천횡단구조물에 대한 평가를 기존의 이□치수적 관점에서 환경□생태학적 관점으로 변화시키고 있다. 이는 자연하천(특히 충적하천)이 수공구조물에 가로막히면 일반적으로 유사, 식생 등의 하천 제반 환경에 부정적인 영향을 준다는 전제에서 댐에 대한 평가가 시작되는 것으로, 국내에서는 이러한 인식의 변화가 2010년대 이후 널리 퍼지면서 현재는 더 이상 신규 댐을 건설할 수 없게 되었다. 댐에 의한 수리 특성과 기후 변화 등으로 댐 하류하천의 유사, 식생, 생태변화는 최근 급격하게 진행되었지만, 정량적인 변화량 및 지표 도출에 대한 연구는 대부분 최근의 data를 반영하지 못하고 있어 관련 원인과 대책 제시에 다소 한계가 있다고 생각된다. 이에 본 연구에서는 낙동강 주요 지류 중 하나이며, 충적하천인 황강을 대상으로 가용한 data를 활용하여, 합천댐 건설 전□후의 유사, 식생변화로 대표되는 하천 환경변화를 정량적으로 분석하고, 변화 원인을 파악하고자 하였다. 유사환경의 변화 분석은 댐 건설 전부터 최근까지의 문헌들에서 조사□제시된 data를 이용하였다. 연도별 최심 및 평균하상고는 댐 건설 전과 비교해 1.0 m가량 감소하였는데, 댐에 의한 세류사 공급차단보다는 골재 채취 및 하도 정비 등이 지배적인 원인인 것으로 파악되었다. 유사 입경의 변화는 댐 건설 전 대비 조립화가 진행되어 모래비율이 감소하고 유사 입경(댐 직하류 약 2배)이 증가하였다. 이는 골재 채취 및 댐에 의한 세류사 차단에 기인한 것으로, 준설된 지역의 하상이 모래 대신 자갈로 대체되고 있기 때문인 것으로 판단된다. 유사량의 경우 몇 번의 조사 과정이 있었으나, 기준이 명확하지 않아 정량적인 변화는 파악하기 어려웠다. 제외지의 식생 분포는 본 연구에서 개발한 이미지 처리 기법을 동원하여 분석하였으며, 대상은 합천댐 하류 중 모래 사주의 비율이 큰 곳을 선택(3지점)하였다. 분석 결과 2008~2011년 이전까지 큰 폭으로 사주가 식생 서식처로 변화(약 20%)되었으며, 이후 큰 변화 없이 안정화 된 경향을 보였다. 이는 2009~2011년 동안 식생이 활착되는 봄~초여름의 강우량 감소, 댐의 홍수조절 및 하상 조립화로 인한 다년생 식생의 활착되고 성장할 시간이 확보되면서 홍수 등 외부 변화에 대한 식생의 대응 능력이 증가했기 때문인 것으로 생각된다. 합천댐이 황강 환경변화에 주는 영향은 분명하지만, 현재 상황은 기후 변화와 인위적인 골재채취도 주요 원인으로 판단되는 바, 향후 하천 환경 개선 계획 수립 시 이러한 변화 원인이 고려된 대책이 수립되어야 할 것이다.