• Economic and Environmental Geology
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• v.43 no.4
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• pp.371-379
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• 2010

Fresh water injection test in a fractured bedrock aquifer was applied as an efficient approach to lower saline concentrations in the saltwater-freshwater transition zone formed by seawater intrusion in a coastal area. The methodology and effectiveness of fresh water injection for hydraulically controlling seawater intrusion is overwhelmingly site dependent, and there is an urgent need to characterize the permeable fractures or unconsolidated porous formations which can allow for seawater flow and transport. Considering aquifer characteristics, injection and monitoring boreholes were optimally designed and completed to inject fresh water through sand layer and fractured bedrock, respectively. We devised and used the injection system using double packer for easy field operation and maintenance. Overall fracture distribution was systematically identified from borehole image logs, and the section of fresh water injection was decided from injection test and monitoring. With fresh water injection, the fluid electrical conductivity of the monitoring well started to be lowered by the inflow of fresh water at the specific depth. And this inflow leaded to the replacement of the fluid in the upper parts of the borehole with fresh water. Furthermore, the injection effect lasted more than several months, which means that fresh water injection may contribute to the mitigation of seawater intrusion in a coastal area.

• Economic and Environmental Geology
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• v.49 no.6
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• pp.445-458
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• 2016

Most of water curtain cultivation (WCC) area in Korea has been inveterately suffering from the gradual draw-down of groundwater level and related shortage of water resources at the late stage of WCC peak time. To solve this problem, artificial recharge techniques has been recently applied to some WCC area. This study introduces infiltration gallery, which is one of the artificial recharge methods, and tentatively examined the effectiveness of three galleries installed at Sangdae-ri WCC area of Cheongju City. Seven galleries are set up at each empty space between eight vinyl houses in this area and its dimension is designed as 50 cm in each width and height and 300 cm in each length. Installation process was including bed excavation, backfill with gravels and silica sands, and completion of gallery by equipment of piezometer and covering with non-woven cloth. For each B, C, D gallery, 3 types of test including preliminary, four step and one long-term injection were performed. The first preliminary test showed the rough relations between injection rates and water level rise as follows; 20 cm and 30 cm level rise for $33.29{\sim}33.84m^3/d$ and $45.60{\sim}46.99m^3/d$ in B gallery; 0 cm, 16 cm and 33 cm level rise for $21.1m^3/d$, $33.98m^3/d$ and $41.69m^3/d$ in C gallery; 29 cm and 42 cm level rise for $48.10m^3/d$ and $52.23m^3/d$ in D gallery. Afterwards, more quantitative results estimating effectiveness of artificial recharge were reasoned out through stepped and long-term injection tests, which is expected to be employed for estimating water quantity re-injected into the aquifer through these galleries by natural injection over the period of WCC peak time.

• Economic and Environmental Geology
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• v.43 no.2
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• pp.177-184
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• 2010

When cement grout is used for waterproofing of grounds, important roles are played by fluidity, particle size and bleeding. The most important element which determines their characteristics is the water/cement ratio of grout. Moreover in order to improve the efficiency of soil permeation, micro cement with a smaller average diameter is used in addition to ordinary portland cement. Besides the mixing ratio and cement diameter, the condition of ground is also of fundamental importance in the efficiency of permeation. In order to evaluate grout in terms of permeation ability into ground, we need a field test of grounting, which is cost and time consuming. In this paper we present a laboratory test method in which the suitability and efficiency of grouts are simply and more practically tested. In Korea neither a test standard nor devices are available to simulate grouting in a laboratory. We devised a grout injection equipment in which grouting was reproduced in the same condition with different materials, and suggested a standard for the production of specimens. Our tests revealed that the efficiency of injection increases with the water/cement ratio. We also found that more efficiently injected is the grout with the order of decreasing size; MS8000, micro cement, and ultra fine cements, and colloidal super cement.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.11 no.4
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• pp.189-200
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• 1991

The purpose of this study is to examine the cut-off effect in aquifer by chemical grouting. Moreover, injection tests using specially prepared injection equipment of 1.5 shot system which hydrauric condition can be controlled are attempted to investigate the cut-off effect by confirming the gelling condition of samples according to the variation of flow velosity. And the permeability is measured according to changing of time by falling head test in order to consider the durability of grouts. Therefore to increase the cut-off effect in groundwater flow, shortening the gel-time according to the increasement of flow velocity, increasing the concentration and quantity of grouts(grouting ratio) according to the increasement of that, and as another direct method, contracting the distance between grouting holes or enlarging the grouting line should be done. These coefficients should be designed by data based on injection test in laboratory and field.

• Review of KIISC
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• v.24 no.2
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• pp.50-55
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• 2014

자동차 전장제품 활용의 급속한 증가에 대응하기 위하여 자동차 분야에서는 ISO 26262 안전설계절차를 도입하여 차량용 임베디드 시스템의 안전성을 확보하려고 노력하고 있다. ISO 26262는 자동차에서 발생 가능한 비정상상태(abnormal state)를 식별하고 그의 영향을 분석하며 전체 시스템의 안전을 검증하는 것을 목표로 하고 있다. 다양한 종류의 부품이 연동되는 복잡한 시스템의 안전 검증은 결함수목법과 고장모드영향분석법을 활용하는 위험분석법이 보편적으로 사용된다. 결함주입시험은 이러한 위험분석의 기반도구로서 안전성을 향상시키기 위하여 사용된 고장감내 기능의 동작여부 및 그에 따른 시스템의 안전성을 검증하는 목적으로 사용된다. 본 논문에서는 차량용 고신뢰성 임베디드 시스템에서 사용되는 고장감내 메카니즘들의 기능과 안전을 검증하는 방법과 사례를 소개한다. 최근의 복잡한 차량용 임베디드 시스템의 개발은 상위수준의 모델을 개발하여 지정된 위험 및 고장을 초래하는 결함을 시스템에 주입하고 그의 결과를 분석하여 안전을 검증하는 것이 일반적인 방법이다. 개발 목표 차량의 임베디드 시스템 모델을 개발하고, 식별된 결함의 결함모델을 준비한 뒤, 시스템 모델 기반 결함주입 도구를 이용하여 결함주입을 수행하는 시험방법과 그 결과에 대하여 논의한다. 하드웨어는 SystemC 하드웨어 설계언어를 이용하여 개발하고, 소프트웨어를 컴파일하여 실행화일을 확보하여 시험대상인 결함모델을 개발하고 이를 대상으로 결함주입시험에 대해 설명한다.

• The Journal of Engineering Geology
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• v.25 no.2
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• pp.215-225
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• 2015

We performed injection tests in a deep-seated confined aquifer to assess the potential of artificial recharge as a means of preventing saltwater contamination, thereby securing groundwater resources for the Nakdong Delta area of Busan City, Korea. The study area comprises a confined aquifer, in which a 10-21-m-thick clay layer overlies 31.5-36.5 m of sand and a 2.8-11-m-thick layer of gravel. EC logging of five monitoring wells yielded a value of 7-44 mS/cm, with the transition between saline and fresh water occurring at a depth of 15-38 m. Above 5 m depth, water temperature is 10-15.5℃, whereas between 5 and 50 m depth the temperature is 15.5-17℃. Approximately 950 m³ of fresh water was injected into the OW-5 injection well at a rate of 370 m³/day for 62 hours, after which the fresh water zone was detected by a CTD Diver installed at a depth of 40 m. The persistence of the fresh water zone was determined via EC and temperature logging at 24 hours after injection, and again 21 days after injection. We observed a second fresh water zone in the OW-2 well, where the first injection test was performed more than 20 days before the second injection test. The contact between fresh and saline water in the injection well is represented by a sharp boundary rather than a transitional boundary. We conclude that the injected fresh water occupied a specific space and served to maintain the original water quality throughout the observation period. Moreover, we suggest that artificial recharge via long-term injection could help secure a new alternative water resource in this saline coastal aquifer.

• Proceedings of the Korean Society of Soil and Groundwater Environment Conference
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• 2004.04a
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• pp.495-498
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• 2004

대전시 유성구 한국원자력연구소 부근 지역의 심부 단열대 확인을 위해 BHTV 검층, 일정구간별 정압 주입시험을 실시하였다. BHTV 조사 결과 A Zone(100m～120m)과 B Zone(250m～280m)이 연결되었다고 판단되며, 일정구간별 정압주입시험을 통해 B Zone(250m～280m)과 C Zone(400～420m)의 연결성을 추측할 수 있었다. 또한, 시추공의 심도별 지하수위 자료를 통해 지하 250m 부근에서 그 상부와 하부의 지하수 시스템이 연속되지 않은 독립된 시스템을 갖는다고 추측된다. 이러한 결론은 MP system이 설치된 시추공의 구간별 압력변화 결과에 의해서도 확인된다.

• Proceedings of the Korean Society for Agricultural Machinery Conference
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• 2002.02a
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• pp.139-144
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• 2002

본 연구에서 열발생탱크, 모타, 로타와 스탯, 순환펌프, 열교환기로 구성된 풍력-열변환시스템을 제작하여 열교환에 미치는 몇 가지 요인에 대하여 시험하였다. 주요결과는 다음과 같다. 가. 풍력열교환시스템은 발열부, 구동부, 열교환부로 구성하였다. 나. 열교환성능시험에서 열교환에 미치는 요인은 유체주입량 3수준, 점성유체의 종류 2수준, 로타의 졸류 3수준, 로타와 스텟의 간격 3수준으로 정하여 열교환시험을 하였다. 다. SAS GLM procedure를 사용하여 열교환량에 대한 각 처리의 효과에 대해 조사해본바 유체주입량이 열 교환량에 가장 큰 영향을 미친다는 것을 발견했다. 라. 최고열교환량은 처리조건 R3 로타, 유체주입량 110 L, 로타와 스텟의 간격 17mm, A 오일에서 발생했으며 7,800 kcal/h 가 되었다. 마. 열 변환효율을 극대화하려면 열발생탱크의 직경보다는 높이를 크게 하고 유체를 최대 높이까지 주입하는 것이 바람직하리라 사료된다.

• Proceedings of the Korean Institute of Surface Engineering Conference
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• 2012.05a
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• pp.252-253
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• 2012

음극전기분해법을 이용하여 고강도 DP강과 TRIP강에 수소를 강제 주입시켜, 시험편 내 수소량을 정량적으로 분석하였고, 표면하 미소경도분포 측정과 소형펀치시험 및 파단면 관찰을 통하여 수소주입량에 따른 고강도 박강판재의 수소침투 및 수소취화거동을 평가하고자 하였다. DP강은 강도가 클수록 높은 수소량으로 조사되었고, TRIP강은 DP강에 비해 주입된 수소량이 적은 것으로 조사되었다. 또한 미소경도분포 및 소형펀치시험에서도 DP강은 TRIP강에 비해 수소취성에 민감성이 높은 것으로 평가되었다.

• Journal of the Korean Institute of Gas
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• v.18 no.1
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• pp.61-67
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• 2014

Small punch(SP) tests were performed on high strength Dual Phase(DP) steels in order to evaluate the behavior of hydrogen embrittlement. For this purpose, three different kinds of DP steel specimens were charged with hydrogen by electochemical hydrogen charging experiment. After charging with hydrogen, the amount of charged hydrogen was measured. The measurement results showed that amounts of charged hydrogen were largely dependent on the martensite volume fraction of DP steel. The hydrogen charging time of 25 hrs with current densities of 150 and $200mA/cm^2$ was investigated as saturation condition with hydrogen. The analysis results on the SP energy and height of SP bulbs after SP tests showed that those were decreased as the amount of charged hydrogen increased. Fractographs of SP bulbs were observed a brittle fracture mixed with quasi-cleavage fractures, layered structures and clear facets.