• Journal of the Korea Concrete Institute
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• v.20 no.3
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• pp.283-290
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• 2008

The repair technique using surface impregnation of reactive compound is so effective for deteriorated concrete structures that many researches are recently focused on these works. Particularly, inorganic impregnant is regarded as ecofriendly material because there is no air-pollution during manufacturing process as well as field coating works. Furthermore, The delamination between old concrete and impregnated surface does not occur, resulting from different material characteristics. In order to evaluate the durability performance of surface-impregnated concrete, durability evaluation through the long-term exposure tests is significant, however, experiments are usually limited to the temporary and qualitative laboratorial scope. In this study, durability characteristics for inorganic and organic/inorganic impregnated concrete specimens are evaluated through longterm chloride exposure test. The specimens with 21MPa and 34MPa strength have been prepared and exposed to chloride attack in the atmospheric, tidal, and submerged conditions. Evaluation for compressive strength, chloride penetration, and electrical potential (half cell potential) for steel corrosion are performed for the specimens exposed for 2 years. From the results, no distinct strength gaining is observed but the resistance to chloride penetration and steel corrosion is evaluated to be improved through surface impregnation. The more improved resistance to chloride attack is measured in the inorganic impregnated concrete and the results from atmospheric condition show more improved resistance to chloride attack than those from submerged and tidal condition.

• Journal of the Korean Society of Hazard Mitigation
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• v.8 no.6
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• pp.47-52
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• 2008

Deicer has been generally used for prevention of a road freezing in winter, and the usage amount is increasing every year. However, deicer may induce the decrease of bond strength, surface scaling, and environmental pollution. In this study, the field test was performed to investigate the deterioration of concrete road structures used for 17 years. And, the corrosion resistance characteristics were compared for the existing deicer and eco-friendly deicer. According to the field test results, the penetration depth of limit chloride amount was about 40mm, and the average concentration of chloride was $3.45kg/m^3$ at the surface of structures. On the contrary, the carbonation depth was slight. The penetration depth of eco-friendly deicer was less than the existing deicer, and the corrosion resistance of eco-friendly deicer was higher.

• Journal of Korean Tunnelling and Underground Space Association
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• v.19 no.2
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• pp.109-120
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• 2017

Groundwater seepage into a tunnel is one of the main causes triggering tunnel collapse and the consequent ground subsidence. Thus, it is important to estimate adequately the groundwater inflow rate and porewater pressure change during tunneling with time elapse. In current practice, Goodman's analytical solution (or image tunnel method) assuming homogeneous ground condition around a tunnel is commonly used for estimating groundwater inflow rate. However, the generally-used analytical solution for estimating groundwater inflow rate does not consider groundwater level drawdown and permeability change with depth, and the inflow rate can be overestimated in design phase. In this study, parametric study was performed in order to investigate the effect of groundwater level drawdown and permeability reduction with depth, and transient flow analysis was carried out for studying the inflow rate change as well as groundwater level and porewater pressure change around a tunnel with time elapse.

• Journal of the Korea Concrete Institute
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• v.17 no.5 s.89
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• pp.703-708
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• 2005

The effects of polymer-cement ratio and antifoamer content on the setting time and durability of high-fluidity polymer-modified mortars using redispersible polymer powder are examined. As the result, the setting time of the polymer-modified mortars using redispersible polymer powder tends to be delayed with increasing polymer-cement ratio, regardless of the antifoamer content. The water absorption, chloride ion penetration depth and carbonation depth of the high-fluidity polymer-modified mortars using redispersible polymer powder decrease with increasing polymer-cement ratio and antifoamer content. The resistance of freezing and thawing and chemicals improvement is attributed to the improved bond between cement hydrates and aggregates because of the incorporation of redispersible polymer powder

• Journal of the Korea institute for structural maintenance and inspection
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• v.19 no.1
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• pp.35-44
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• 2015

Two main parameters were examined such as CSA content and polymer-binder ratio to find effects on the strength, water absorption, chloride ion penetration depth, carbonation depth, length change and chemical resistance of polymer-modified mortar with CSA and EVA polymer powder (EVAPP). As results, compressive, flexural, tensile, adhesive strengths, and length change of the polymer-modified mortar with CSA and EVAPP increases with increasing CSA content and polymer-binder ratio, although the water absorption, chloride ion penetration depth, and carbonation depth decrease with increasing polymer-binder ratio and CSA content, and also the chemical resistance decreases. Such strength and durability development is attributed to the high tensile strength of EVA polymer and the improved bond between cement hydrates and aggregates because of the addition of EVAPP and CSA.

• Journal of the Korean Recycled Construction Resources Institute
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• v.6 no.4
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• pp.324-330
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• 2018

In accordance with the amendment of the Industrial Safety and Health Act of 2007, Korea completely prohibited the import, distribution and manufacture of asbestos like Europe and Japan. Accordingly, the current problem of asbestos is the safe maintenance and disposal of asbestos construction material, the disposal of asbestos, and the final disposal of asbestos building materials. In the past, Korea used 100,000 tons of asbestos every year, and the building materials using it exceeded 1 million tons per year. These asbestos building materials continued to be used until 2006, and the Ministry predicted that these materials would continue to be maintained until 2044. When the permeable hardening agent is applied to the asbestos building material installed in the pre-pretreatment step for the harmless treatment of the asbestos waste and the dismantling is carried out, the scattering of the asbestos is suppressed in the disassembling step, detoxification treatment conditions can be improved. Therefore, permeable hardeners should be stably penetrated into asbestos building materials. In this study, it is suggested that pre - pretreatment methods for the harmlessization of waste asbestos building materials with medium density level can be presented. In order to efficiently perform pre - treatment for chemical harmlessness in the future, the mixing ratio of permeable hardener and middle water Optimization is the most important factor.

• Journal of the Korean Geosynthetics Society
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• v.7 no.4
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• pp.9-18
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• 2008

Shallow slope failures in residual soil during periods of prolonged infiltration are common in Korea. This study examines an infinite slope analysis to estimate the influence of infiltration on surficial stability of slopes by the limit equilibrium method. Approximate method which is based on the Green-Ampt model have been considered to evaluate the likelihood of shallow slope failure which is induced by a particular rainfall event that accounts for the rainfall intensity and duration for various return periods. Pradel & Raad method which is devised to predict the depth of wetting front to decomposed granite soil slopes having measured soil-water characteristic curves. To compare the results with those obtained from the Pradel & Raad method, a series of numerical analysis using SEEP/W were carried out. It was found that the stability analysis of unsaturated soils calculated by using the soil-water characteristic curve of decomposed granite soils was found to be a proper analysis for shallow slope failures due to rainfall.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.12 no.1
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• pp.31-35
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• 2002

Abstract Spinel powder having a particle size of 0.9$\mu$m was calcined for 30 min at $1300^{\circ}C$, followed by ball milling for 4h, to obtain the spinel particle size of 3.29$\mu$m. The die-pressed spinel was presintered at $1100^{\circ}C$ for 2h and then lanthanum aluminosilicate glass was infiltrated at $1080^{\circ}C$ for 0~2 h to investigate the penetration kinetics in glass-spinel composite. The infiltration distance is parabolic in time due to capillarity. The strength and the fracture toughness of glassspinel composites were 317 MPa and 3.56 MPa $m^{1/2}$ respectively and dual microstructure of column (needle) and polygonal shapes as a result of recrystallization was observed due to the high calcination temperature.

• The Journal of Engineering Geology
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• v.25 no.1
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• pp.57-66
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• 2015

A numerical analysis was performed of the seepage from and stability of a mine waste-dump slope in Imgi, Busan, considering rainfall intensity. The 40-45° slope angle of the waste dump is relatively steep, and the depth of the waste dump down to bedrock is 7-8 m. The groundwater level was 6.6 m below the surface. Various laboratory tests on samples obtained from the waste dump were performed to determine the input data for seepage and stability analyses of the waste-dump slope during rainfall. The results of seepage analysis for various rainfall intensities using the SEEP/W program show that the wetting front moved down with increasing rainfall duration. When the rainfall intensity was > 50 mm/ hour and the duration was > 24 hours, the waste dump became fully saturated because the wetting front reached the groundwater level. The results of slope stability analysis coupled with seepage analysis using the SLOPE/W program show that the safety factor of the slope decreased as the wetting front moved down due to rainfall infiltration. After continuous rainfall for 5-6 hours, the safety factor of the slope suddenly decreased but then recovered and converged. The sudden decrease was induced by an increase in pore-water pressure and a decrease in matric suction down to a certain depth as the wetting front approached the potential sliding surface.

• Journal of the Korean Wood Science and Technology
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• v.19 no.3
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• pp.7-18
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• 1991

목재(木材)의 액체침투성(液體浸透性)을 연구(硏究)하기 위하여 국내(國內)에 있는 침엽수재(針葉樹材)와 활엽수재(闊葉樹材)의 주요수종(主要樹種)을 대상으로 축방향(軸方向), 방사방향(放射方向), 접선방향(接線方向)의 침투(浸透)를 각각 조사(調査)하였다. 또한 방사(放射) 및 접선방향(接線方向)의 주요(主要) 침투경로(浸透經路)를 광학현미경(光學顯微鏡)으로 관찰(觀察)하였다. 실험결과(實驗結果)는 다음과 같다. 1. 종침투(縱浸透)는 침(針) 활엽수재(闊葉樹材)모두 1% $NH_4OH$ 처리(處理)시 침투성(浸透性)이 가장 컸으며 수종(樹種)에 따른 침투성(浸透性)의 차이(差異)는 침엽수재(針葉樹材)인 잣나무가 활엽수재(闊葉樹材)인 물푸레나무와 현사시나무 보다는 더 컸으며 관엽수재내(關葉樹材內)에서는 물푸레나무가 현사시나무보다 침투성(浸透性)이 더 큰 것으로 나타났다. 2. 횡침투(橫浸透)는 침엽수재(針葉樹材)에 있어서 침투면별(浸透面別) 침투량(浸透量)은 접선단면(接線斷面)이 방사단면(放射斷面)보다 훨씬 컸으며, 활엽수재(闊葉樹材)의 경우는 환공재(環孔材)에서는 접선단면(接線斷面)이 방사단면(放射斷面)보다 침투량(浸透量)이 컸으나, 산공재(散孔材)에서는 수종간(樹種間)의 변이(變異)가 컸다. 활엽수재(闊葉樹材)의 환공재(環孔材) 모두 방사조직(放射組織)이 횡침투(橫浸透)에 미치는 영향(影響)은 침엽수재(針葉樹材)만큼 크지 않았다. 침투(浸透)깊이도 침엽수재(針葉樹材)가 활엽수재(闊葉樹材)보다 컸으며, 활엽수재(闊葉樹材)는 수종간(樹種間)의 차이(差異)가 심했다. 3. 침투경로(浸透經路)를 보면 침엽수재(針葉樹材)는 방사유세포(放射柔細胞), 만재부(晩材部)의 소가도관(小假導管)이 주도적(主導的)인 역할을 하였으며, 활엽수재(闊葉葉材)도 역시 방사조직(放射組織)을 통해서 침투(浸透)가 이루어지지만 수종간(樹種間)에 방사조직(放射組織)의 침투양식(浸透樣式)과 침투속도(浸透速度)가 달랐다.