• Earthquakes and Structures
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• 제4권5호
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• pp.557-585
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• 2013

The recent huge earthquake ground motion records in Japan result in the reconsideration of seismic design forces for nuclear power stations from the view point of seismological research. In addition, the seismic design force should be defined also from the view point of structural engineering. In this paper it is shown that one of the occurrence mechanisms of such large acceleration in recent seismic records (recorded in or near massive structures and not free-field ground motions) is due to the interaction between a massive building and its surrounding soil which induces amplification of local mode in the surface soil. Furthermore on-site investigation after earthquakes in the nuclear power stations reveals some damages of soil around the building (cracks, settlement and sand boiling). The influence of plastic behavior of soil is investigated in the context of interaction between the structure and the surrounding soil. Moreover the amplification property of the surface soil is investigated from the seismic records of the Suruga-gulf earthquake in 2009 and the 2011 off the Pacific coast of Tohoku earthquake in 2011. Two methods are introduced for the analysis of the non-stationary process of ground motions. It is shown that the non-stationary Fourier spectra can detect the temporal change of frequency contents of ground motions and the displacement profile integrated from its acceleration profile is useful to evaluate the seismic behavior of the building and the surrounding soil.

• 한국지열·수열에너지학회논문집
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• 제7권2호
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• pp.51-59
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• 2011

Storage and transfer heat in soils are governed by the soil thermal properties and these properties are therefore needed in many engineering applications, including horizontal ground heat exchanger for ground-coupled heat pumps. This paper presents the measured results of the thermal diffusivity of soils(silica, quartzite, limestone, sandstone, and masonry soils) used for the trench backfilling materials of the horizontal ground heat exchanger. To assess this thermal property, we (i) measure the soil thermal conductivities and volumetric heat capacities using dual-probe method and (ii) compare the estimates from the de Vries method of summing the heat capacities of the soil constituents. The results show that the thermal diffusivity tends to increase as dry soil begins to wet, but it approaches a constant value or even decreases as the soil continues to wet. Measurements made by using the dual-probe method agreed well with independent estimates obtained using the single-probe method.

• 한국지구물리탐사학회:학술대회논문집
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• 한국지구물리탐사학회 2007년도 특별 심포지엄 논문집
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• pp.31-42
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• 2007

Dc resistivity monitoring has been increasingly used in order to understand the changes of subsurface conditions in terms of conductivity. The commonly adopted interpretation approach which separately inverts time-lapse data may generate inversion artifacts due to measurement error. Eventually the contaminated error amplifies the artifacts when reconstructing the difference images to quantitatively estimate the change of ground condition. In order to alleviate the problems, we defined the subsurface structure as four dimensional (4-D) space-time model and developed 4-D inversion algorithm which can calculate the reasonable subsurface structure continuously changing in time even when the material properties change during data measurements. In this paper, we discussed two case histories of resistivity monitoring to study the ground condition change when the properties of the subsurface material were artificially altered by injecting conductive materials into the ground: (1) dye tracer experiment to study the applicability of electrical resistivity tomography to monitoring of water movement in soil profile and (2) the evaluation of cement grouting performed to reinforce the ground. Through these two case histories, we demonstrated that the 4-D resistivity imaging technique is very powerful to precisely delineate the change of ground condition. Particularly owing to the 4-D inversion algorithm, we were able to reconstruct the history of the change of subsurface material property.

• 한국건축시공학회:학술대회논문집
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• 한국건축시공학회 2013년도 추계 학술논문 발표대회
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• pp.66-67
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• 2013

Replacing a large amount of ground granulated blast furnace slag is limited because early age strength is low due to latent hydraulic property despite excellence of long-term strength. This study aimed to examine produceableness of high-activated ground granulated blast furnace slag using slag by-product from steel process. As experimental variable, the properties of strength development were analyzed by setting fineness and replacement ratio of slag by-product, curing conditions, and W/B. The results of study showed that high-activated ground granulated blast furnace slag using slag by-product as an activator improve the compressive strength of mortar. It is expected to be used as binder for secondary product of concrete considering curing and mixing conditions because high-activated ground granulated blast furnace slag can be hydrated by itself.

• 한국식품조리과학회지
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• 제32권3호
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• pp.290-298
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• 2016

Purpose: This study aimed to investigate the effect of grape skin on the physicochemical properties and sensory score of ground pork meat. Methods: Four types of ground pork were evaluated: T0 without grape skin, T1 with 0.3% grape skin, T2 with 0.7% grape skin, and T3 with 1.0% grape skin. Results: There was no significant group wise difference in VBN content, L-value, b-value, chemical composition of raw and cooked meat, cooking yield, water holding capacity, moisture retention, fat retention, hardness, springiness, cohesiveness, gumminess, chewiness, taste, texture, juiciness, or palatability. Total polyphenol content was highest in T3, and DPPH radical scavenging activity was highest in T2 and T3 (p<0.001). The pH was highest in T0, and was lowest in T3 (p<0.001). The a-value of T2 and T3 were significantly higher than that of T0 (p<0.05). Flavor was highest in T2 among samples (p<0.01). Conclusion: The study results suggest that grape skin may be a useful ingredient in ground pork meat in terms of antioxidant potential, color and flavor.

• 한국농공학회논문집
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• 제64권3호
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• pp.75-83
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• 2022

Recent settlements and sinkhole openings in urban areas have caused social problems such as damage to roads and structures, fear of the public, and loss of property. Several studies have demonstrated that surface subsidence and sinkhole opening are greatly affected by rainfall and rainfall intensity in urban areas. In this paper, we analyzed the relationship with the characteristics of recorded rainfall data using the ground subsidence database reported in major cities. The correlations were found using sedimentation and precipitation data from 2010 to 2014. The duration and intensity of a given precipitation have evolved to obtain an effect on ground sedimentation rate (SR). The results show that the relationship between SR and precipitation is asymptotic and can be modeled by a hyperbolic equation. Through this study, it is possible to predict the occurrence of ground subsidence due to precipitation in advance.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2001년도 봄 학술발표회 논문집
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• pp.929-934
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• 2001

This study aimed to examine the cause of latent hydraulic property manifestation of ground granulated blast-furnace slag(GGBFS) using different alkali activators in pH, type and quantity. According to the experimental result, the higher pH value accelerated lastly latent hydraulic property and the early stage strength of GCBFS was ranked as activators with the higher pH, in an order of NaOH, $Ca(OH)_{2}$ and $Na_{2}$$Co_{3}$. Also, NaOH had accelerated latent hydraulic property of GGBFS, which had 40~50% of the 3 and 7 days compressive strength of base mortar in case of using 10% of powder-weight. In the case of 30% of GGBFS substitution with annexing 2.5% $Ca(OH)_{2}$, the compressive strength on the 3 and 7 days of the early-age, was increased to 5~10% than that of the same admixture with no activator. With annexing 5.0% $Ca(OH)_{2}$, the strength was increased to 10~20%. Although activator NaOH was effective on the manifestation of latent hydraulic property, it caused cement mortar compressive strength decrease by enlarging pore diameter.

• 한국터널지하공간학회 논문집
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• 제22권1호
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• pp.1-21
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• 2020

국내 폐광산은 다양한 형태의 침하를 발생시키고 있으며 이러한 침하의 예측 및 위험도의 평가는 대단히 어려운 실정이다. 기존 수치해석을 활용한 침하 예측 및 위험도 평가 연구에서는 지질구조와 지반조건에 대해 통합 물성을 적용하고 채굴적 주변 소성영역을 해석하는데 그치고 있다. 또한 입력정보를 확보하는데 있어 제한된 자료밖에 파악할 수 없는 현실적인 한계점이 존재하며 이는 곧 수치해석 결과의 신뢰성 저하로 연결된다. 본 연구에서는 실제 침하가 발생한 폐광산을 대상으로 현장 지질구조 및 지반정보를 적용하여 2차원 모델링을 수행하였다. 또한 지반물성을 수정하여 해석결과와 실제 침하지 정보(규모, 위치)의 차이가 최소가 되도록 수치해석을 반복하여 해석모델을 보정하였다. 이러한 보정에 있어 최적화 기법을 적용하여 자동화하였으며 다수의 지반물성을 나누어 고려하는 단계적 최적설계 기법을 개발하였다.

• 한국지반공학회논문집
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• 제34권12호
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• pp.19-27
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• 2018

테르쟈기는 트랩도어 처짐에 기반한 상부지반의 수직활동면을 가정한 2차원 아칭식을 제안하였다. 이후 관련 식은 3차원 터널굴착조건과 경사활동면을 고려할 수 있도록 확장되었다. 본 연구에서는 3차원 터널굴착조건에서 비등방지반조건을 반영하여 터널 횡방향 및 종방향에서의 지반물성치 및 활동면의 경사각을 달리하여 고려할 수 있도록 더욱 확장된 아칭식을 유도하고 제시하였다. 제시된 식을 이용하여 다양한 조건(지반물성치, 경사활동면, 굴착조건, 상재하중, 토압계수)에서 발생되는 수직응력에 대해 조사하였고 테르쟈기의 2차원 아칭식과도 비교하였다. 조사결과, 발생 수직응력은 굴착폭 및 굴착길이, 경사각, 상재하중이 증가할수록 증가했고 점착력과 마찰각, 토압계수가 감소할수록 증가하였으며, 굴착길이가 작을 때와 횡방향 지반물성치에 의해서 더 큰 영향을 받는 것으로 나타났다. 또한 테르쟈기 2차원 아칭식과 비교하여 발생 수직응력은 더 작은 것으로 나타났고 그 차이정도는 지반물성치, 경사활동면, 3차원 터널굴착 조건에 따라 매우 큰 영향을 받는 것으로 나타났다. 제시된 3차원 아칭식은 터널굴착으로 인한 복잡한 아칭현상을 보다 잘 이해하는데 도움을 줄 수 있을 것으로 판단된다.

• 대한설비공학회:학술대회논문집
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• 대한설비공학회 2007년도 동계학술발표대회 논문집
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• pp.429-433
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• 2007

Cement mortar and concrete can be used as grouts but problems regarding shrinkage and the discord of coefficients of thermal expansion between grouts and HDPE pipes has to be solved. Thermal conductivities of wet condition two times larger than those of dry condition, except for pure cement mortar. The addition of sand into the cement grouts greatly increases the thermal conductivity. The addition of bentonite into the cement grouts reduces thermal conductivity thus reducing the density. Bentonite grouting must be used only below the groundwater table since bentonite grouts possesses high shrinkage property in dry condition. The addition of sand prevents the shrinkage of bentonite grouts. Bentonite manufactured in Korea can be used since they possess similar thermal conductivities with imported products. The addition of sand into the bentonite grouts greatly increases the thermal conductivity.