• Proceedings of the Korea Concrete Institute Conference
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• 2008.11a
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• pp.417-420
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• 2008

The requirement for durability of concrete is increasing recently as a large-scale concrete structure is built. For this reason, the concern about high-durable concrete is being high. Recently, metakaoline to be profitable in economical aspect as well as to have strength and durability of level similar to silica fume is evaluated highly as new admixture. In this study, the scaling, the drying shrinkage, the chloride resistance and the air-void structure are compared for both metakaolin and silica fume concrete. According to the results, the replacement of metakaoline improved the resistance of chloride penetration, freezing and thawing in concrete. On the other hand, as metakaolin was replaced to 10%, it was similar level with OPC in the property of scaling. It was showed that replacement of only metakaoline was similar with OPC in the drying shrinkage. However, MS5 reduced the drying shrinkage about 10%. In conclusion, replacement of the metakaoline 10% is the most excellent performance in terms of durability of concrete.

• Proceedings of the Korean Geotechical Society Conference
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• 2006.03a
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• pp.414-423
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• 2006

Many construction projects adopt grouting technology to prevent the leakage of groundwater or to improve the shear strength of the ground. Recognition as a feasible field procedure dates back to 1925, Since then, developments and field use have increased rapidly. According to improvement of grout materials, theoretical study on grout penetration characteristics is demanded. Fluid of grout always tends to flow from higher hydraulic potential to lower and the motion of grout is also a function of formation permeability. Viscosity of grout is changed by chemical action while grout moves through pores. Due to the increment of viscosity, permeability is decreased. Permeability is also reduced by grout particle deposits to the soil aggregates. In this thesis, characteristics of new cement grout material that is developed recently is studied: injectable volume of new grout material is tested in two different sizes of sands, and the method to calculate injectable volume of grout is suggested with consideration of change in viscosity and clogging phenomena. The calculated values are compared with injection test results. Viscosity of new grout material is found to be an exponential function of time. And lumped parameter $\theta$ of new grout material to be used for assessing deposition characteristics is estimated by comparing deposit theory with injection test results considering different soil types and different injection pressure.

• Proceedings of the KSR Conference
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• 2007.11a
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• pp.1267-1272
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• 2007

In the case of the railway bridge, there are following the progress of works after the drainage method of a bridge surface - vibration proof rubber establishment, track gravel construction and rail construction etc. But these works are not enforced consecutively by the execution and economical reason. This is the reason of the long period of exposure after drainage execution. In many case, from the deterioration phenomenon by long term exposure of surface, there are a lot of occasions that do not keep primitive penetration depth waterproof primitive time. It is the most important that select the drainage method that have durability - it is not fallen in long-term exposure of surface. The major objective of this study is to deduce objective analysis result through examination about the Deterioration Restraining Agent method and to master KNOW-HOW of DRA drainage method. Through the study, minimize economical damage by frequent repair and reinforcement and present the reasonable standard of judgement fot drainage method of construction.

• Applied Chemistry for Engineering
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• v.31 no.4
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• pp.347-351
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• 2020

A material changes its physical and chemical properties through the interaction with radiation and also the neutrons, which is electronically neutral so that the penetration depth is relatively deeper than that of other radioactive way including alpha or beta ray. Therefore, the radiation damage by neutron irradiation has been intensively investigated for a long time with respect to the safety of nuclear power plants. The damage induced by neutron irradiation begins with the creation of point defects in atomic scale in the unit of picoseconds, and their progress pattern can be characterized by microstructural defects, such as dislocation loops and voids. Their morphological characteristics affect the properties of neutron-irradiated materials, therefore, it is very important to predict the microstructure at a given neutron irradiation condition. This paper briefly reviews the evolution of radiation damage induced by neutron irradiation and introduces a phase-field model that can be widely used in predicting the microstructure evolution of irradiated materials.

• Journal of the Korean Geographical Society
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• v.49 no.4
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• pp.546-562
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• 2014

This research attempts to investigate the geographical approaches on healing, which have been neglected in geography relatively, comprehensively and to examine the meaning of healing in daily life from the viewpoint of the managers of psychological counselling caf$\acute{e}$s. According to the results of this research, exposed healing spaces such as mental clinics or counselling centers are regarded as cultural stigmatic spaces; besides, psychological counselling caf$\acute{e}$s decrease psychological distance or resistance and people calling for healing can access these healing spaces easily. Second, healing spaces from a perspective of modern people mean geographical boundaries as refuges for a brief time; accordingly, the users' activities in psychological counselling caf$\acute{e}$s as instant or unexpected healing spaces in daily life are interpreted as special experiences without any emotional burdens. And these psychological counselling caf$\acute{e}$s are regarded as the spaces where can experience healing repeatedly and continuously. Third, psychological counselling caf$\acute{e}$s were changed into general caf$\acute{e}$s as open spaces; therefore, they can penetrate deeper into daily life rather than others.

• Proceedings of the Korean Radioactive Waste Society Conference
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• 2009.06a
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• pp.296-296
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• 2009

산화물 사용후핵연료를 대상으로 하는 파이로 공정은 고온 용융염 매질에서 산화물을 금속으로 전환시키는 전해환원 공정으로부터 시작된다. 이후, 전해정련 공정이 도입되어 전해환원 공정에서 금속으로 환원된 생성물을 처리하게 된다. 전기화학적 공정인 이 두 공정에는 전류전달 매질인 전해질로 용융염이 사용된다. 그러나 전해환원 공정은 LiCl 염을 기반으로 하는 반면 전해정련은 LiCl-KCl 공융염 조건에서 운전하여 두 공정의 연계성 향상 및 공정 안정성 확보를 위해서는 전해환원 공정에서 생성되는 금속전환체에 존재하는 잔류염을 제거하는 공정의 도입이 두 공정사이에 고려되고 있다. 전해환원 공정에서 산화물이 금속으로 환원되는 동안 고체입자의 외형이 유지되며 따라서 제거된 산소에 의해 금속전환체에는 공극이 발생하게 된다. 또한, 전해환원에 도입되는 산화물의 물리적 형태가 분말 또는 펠렛 등 다양한 형태로 도입 가능하여 단위 입자들 사이에 많은 공극이 발생하게 된다. 이렇게 기존재하거나 또는 공정 운전에 의해 새롭게 생성된 공극에는 전해환원 매질인 LiCl 염이 침투하여 금속전환체는 염에 의해 젖게 되며 공정 종료시 고화되어 금속전환체에 포함된다. LiCl을 제거하기 위해서는 가열에 의한 증류가 연구되고 있다. 그러나 LiCl의 낮은 증기압에 의해 비교적 낮은 온도에서 증발시키기 위해서는 감압조건이 필수적으로 고려되어야 한다. 한국원자력연구원에서는 다공성 모의 금속전환체를 사용하여 LiCl에 의한 Wetting 후 적절한 증발 조건 결정을 목적으로 온도 및 압력 조건 설정을 위한 기초실험에 결과를 수행하였다. 본 연구의 기초 실험 결과 $700^{\circ}C$온도 조건과 감압조건이 잔류염 제거를 위한 공정조건임을 밝혔다. 또한 모의 금속전환체를 담고 있는 미세 다공성 Basket은 고온조건에서 공극의 변형에 의해 증발에 대한 저항으로 작용하여 증발 효율을 저하시키는 것으로 나타났다. 따라서 잔류염 제거를 위해서는 전해환원 Basket이 비교적 큰 공극을 지녀야 할 것으로 판단된다.

• Economic and Environmental Geology
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• v.35 no.5
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• pp.421-428
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• 2002

Lab-scale experiments were conducted to evaluate the effect of surface tension reduction on the extension of the influence zone and the VOC removal efficiency of ground water sparging. A glass column packed with coarse sand was used for VOC removal test at two different surface tensions. A glass column without porous media was also used fer control purpose prior to sand-packed column test. A quasi-two-dimensional glass box model, packed with a sand, was used fer sparging zone tests at different water surface tensions. Surface tension of the aquoues solution used in this study was controlled using sodium dodecyl sulfate (SDS). For the glass, sand column experiments, total amount of air filled in the media increased as surface tension decreased. Toluene (used as VOC in this study) removal rate increased slightly with decreased surface tension f3r both free water column and sand-packed column. Air sparging zone extended up to 500% as the surface tension decreased. Combining the results from two different experiments, VOC removal efficiency is expected to increase significantly with surface tension reduction.

• The Journal of Engineering Geology
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• v.15 no.1
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• pp.77-86
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• 2005

CFRD(Concrete Faced Rockfill Dam) is in widespread use because this type of dam has superior characteristics in structural, material aspects comparing with earth cored rockfill dam. On this paper, up-to-date re-searches and techniques are summed up to be available for future needs in design and construction of CFRD. For example, such items as embankment using weak rock, experience of sand-gravel fill CFRD, connecting slab applied between plinth and face slab, raising experience of old dm, inverse filtration problem, environmental friendly zone, thickness and reinforcing of face slab, alluvial foundation treatment, and curb element method, are summarized for understanding of related engineers.

• Journal of Biomedical Engineering Research
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• v.23 no.4
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• pp.323-327
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• 2002

Chronic diabetic patients need to sample capillary blood for monitoring and controlling the blood sugar level. Frequent sampling requires to minimize pain during skin puncture. The present study developed mechanisms to minimize pain with effective sampling procedure. which consisted of tapered spring, guiding tunnel, and 30G needle Penetration depth was limited to within 2mm for pain reduction as well as for safety. Simple no-reuse mechanism also prevented the cross-patient and secondary infection possibility. Clinical experiments demonstrated the best convenience and safety with minimal pain in the diabetes, normal, and nursing students groups. Sing1e blood sampling was enough for successful blood sugar test by portable analyzer. The present sing1e use auto-lancet should be of great convenience in frequent capillary blood sampling for the diabetes.

• Proceedings of the Korean Geotechical Society Conference
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• 2009.03a
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• pp.154-163
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• 2009

The groutability depends on the properties of the grout, its injection processes, and on the mechanical properties of the soil formation. During the process of pouring cement-based grouting into a porous medium, a variation with time occurs in the viscosity of grout suspension. In addition the particle filtration phenomenon will limit the expansion of the grouted zone because cement particles are progressively stagnant within the soil matrix. In this paper, a closed-form solution was derived by implementing the mass balance equations and the generalized phenomenological filtration law, which can be used to evaluate the deposition of cement-based grout in the soil matrix. The closed-form solution relevant to a particular spherical flow was modified by a step-wise numerical calculation, considering the variable viscosity caused by a chemical reaction, and the decrease in porosity resulting from grout particle deposition in the soil pores. A series of pilot-scale chamber injection tests was performed to verify that the developed step-wise numerical calculation is able to evaluate the injectable volume of grout and the deposition of grout particles. The results of the chamber injection tests concurred well with that of the step-wise numerical calculation. Based on the filtration phenomenon, a new groutability criterion of cement-based grout in a porous medium was proposed, which might facilitate a new insight in the design of the grouting process.