• Geotechnical Engineering
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• v.11 no.1
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• pp.41-50
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• 1995

In situ clay soils with Ko condition have anisotropic characteristics, varying the response according to the principal stress direction upon loading. But because of their practicality and simplicity, consolidated isotropic undrained compression tests are commonly used in practice to determine the behavior of cohesive soils. In this study to investigate the anisotropic characteristics and the effects of consolidation stress states on the response of normally consolidated clay soils during shearing, triaxial compression and extension tests after consolidating the undisturbed clay soil samples, which are obtained as a block sample to normalized consolidation states under isotropic or Ko state, were carried out. As a result of tests, the anisotropy of the undrained strength was confirmed. Comparing the soil responses between isotropic and Ko consolidation, the undrained strength by isotropic consolidation is overestimated because of its higher mean consolidation pressure. And isotropic consolidation reduces the anisotropy of soil response and influences on the stress-strain behavior and pore pressure response because the animotropic soil structure is partially collapsed during isotropic consolidation process. Also, OCR in overconsolidated soils is decreased by isotropic consolidatiorL Friction angle in eztension is higher than that in compression, but regression analysis shows that friction angle with cohesion in extension is almost the same as that without cohesion in compresslon.

• Journal of the Korean Geotechnical Society
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• v.27 no.7
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• pp.69-79
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• 2011

Laboratory tests are generally used to determine the input parameters for the selected constitutive models controlling various stress and drainage conditions, but have disadvantages in that the tests are performed on the samples obtained from the bore hole which are prone to be disturbed by various factors such as the tube penetrations, sample preparations and storage. To overcome these disadvantages, it is necessary to understand the effect of disturbance on the stiffness of the sample, especially the normally consolidated clays which are generally considered as soft clays. Therefore, in this study triaxial tests are performed on the normally consolidated kaolinite to evaluate the sample disturbance effects on the stiffness and to determine the field representative input parameters. The stress path results show that the shear and coupling modulus degradation patterns with strain are affected seriously by the disturbance. However, the strengths of the normally consolidated kaolinite are little influenced by the disturbance.

• Communications of Mathematical Education
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• v.33 no.3
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• pp.181-205
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• 2019

This study analyzed how university students' motivations for learning mathematics and emotions for learning mathematics occur and how they relate to each other by introducing the factor called needs in the particular context of mathematics learning, mathematics class centered on peer discussions. We conceptualized the key concepts of the study, motivation for learning mathematics and emotion for learning mathematics. Based on them, we drew specific ways to observe motivation and emotion for learning mathematics and conduct the research. As a result, motivations for learning mathematics occurred to satisfy some needs. Also, positive emotions for learning mathematics occurred when some needs were satisfied, whereas negative emotion for learning mathematics occurred when some needs were not satisfied. Furthermore, when the needs leading to motivations for leaning mathematics were satisfied, positive emotions for learning mathematics occurred. The unfulfilled needs leading to negative emotions for learning mathematics make motivations for learning mathematics occur to satisfy those needs.

• Journal of the Korean Geotechnical Society
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• v.22 no.7
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• pp.13-21
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• 2006

When enforced earth is used for the retain wall and four walls, the most important thing would be how to maximize the land utilization. Accordingly, in case of enforced earth, we pile up the minimal height of earth ($20{\sim}50\;cm$) and harden the earth using a static dynamic hardening machine. In this paper, we tried to analyze and compare the stress transformation characteristics of reinforced weathered granite soil with geosynthetics when repetitive load is added to the enforced earth structure and when static load is added. The result is that the cohesion component of the strength increased greatly and the friction component decreased slightly.

• Journal of the Korean Geotechnical Society
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• v.24 no.4
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• pp.57-66
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• 2008

In this study, the blast-induced vibration effects on the structural stability of the adjacent tunnel and the stability were estimated with respect to the allowable peak particle velocity (PPV). The blasting distance from the tunnel satisfying the allowable PPV was estimated based on the analytical solutions, United States Bureau of Mines (USBM) suggestions, and the equations used in the subway in Seoul. The allowable blasting distance was estimated by using finite difference analysis (FDA) and the behavior of the concrete lining and rock bolts was examined and the stability of those was estimated during the blast. Research results show that the blast-induced vibration effects on the structural stability are negligible for the concrete lining but relatively large for the rock bolts.

• Journal of the Korean Geotechnical Society
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• v.26 no.6
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• pp.21-28
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• 2010

Decomposed granite soil is the most common type of soils. The measurement of the stress-strain-strength behavior of anisotropic decomposed granite soils is very important for the deformation and stability analysis of slopes, retaining walls, excavations. A series of unsaturated-drained triaxial compression tests were performed to know unsaturated strength properties. The sample had three different angles of the axial (major principal) direction to the sedimentation plane (compaction plane): 0, 45 and 90 degrees. The compression strain of specimens subjected to an isotropic compression was strongly influenced by the sedimentation angle. In addition, the time dependence was independent of the sedimentation angle in relation to the deformation behavior during the secondary compression process. The effect of the sedimentation angle on the triaxial compression strength and deformation was clearly shown with low confining stress. The effect of the sedimentation angle on the compressive strength and deformation was more evident in saturated specimens. A new method of predicting the shear strength of unsaturated decomposed granite soils, considering compaction angles, was proposed.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.26 no.6C
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• pp.377-384
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• 2006

Theoretical and experimental study of the unconfined penetration (UP) test was conducted to suggest a new test method (referred to as IUP, Improved Unconfined Penetration) for determination of the tensile strength of compacted sand-bentonite mixtures. The tensile strength of compacted mixtures can be calculated from limit analysis based on the theory of perfect plasticity. The measurement errors in new test method were reduced by improving the UP device. Preliminary experiment results indicate that the tensile strength increases with increasing the disk size, loading rate and pH level. In addition, the disk diameter with 25.4 mm and the loading rate with 0.5%/min~1%/min are most suitable condition for the IUP test. The reliability of IPU test was verified by through the fact that good agreement between the IUP and conventional split tensile test results is observed.

• Economic and Environmental Geology
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• v.51 no.2
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• pp.203-211
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• 2018

Issues with past practice in seismic hazard analysis of nuclear power plant sites in Korea are addressed. Brief review on both deterministic and probabilistic methods in seismic hazard analysis is given, and most of the continuing discussion is focussed on the probabilistic seismic hazard analysis. Causes of uncertainty are traced on the basis of the cases that the assessment methodology was applied to the nuclear power plant sites. Considerations on the assessment include the role of experts, a representative seismic catalog, seismic source zonation, earthquake ground-motion relationship, and evaluation process. Factors increasing uncertainty in each item are analyzed and some feasible solutions are discussed.

• Journal of the Korean Society of Hazard Mitigation
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• v.10 no.1
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• pp.43-48
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• 2010

Proctor test A or D method of compaction is the most common laboratory test for investigation of subgrade soil characteristics, however, compression type using roller is used in the field. The differences between laboratory and field compaction have considerable error as application to subgrade soil properties of laboratory test. The investigation of compacted soil is carried into effect to solve the problem. The gyratory compactor which is made to reproduce the field density of asphalt mixture, coming from traffic loads, has an advance to compact it similar to arrangement of field aggregate particles. This gyratory compactor has several problems of investigation of compacted soil, because it has designed to make initial asphalt specimens. The main objectives of this research are grasping problems when compacted soil test using the gyratory compactor and showing solutions. It has made a comparative study of difference of the percentage of water content and weight, which are before and after compaction, about the pressure of compaction, frequency of compaction and speed of compaction. And it also has investigated finding maximum percentage of water content which not occur change of percentage of water content after compaction and searching how has an effect on drawing compaction curve.

• Journal of Korean Academy of Nursing
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• v.8 no.1
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• pp.43-84
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• 1978

미국에 이민 온 한 한국가정을(정씨 가족) 대상으로 세 번의 면담 (interview) 및 art session을 통해서 이 핵가족 및 확대가족을 다음과 같은 방법으로 분석하여 가족의 유형(family Pattern)과 관계된 이론적 모델(Theocratical model)을 理이해하고 변화되고 있는 Health Program에 있어 간호원이 "변화인자(change agent)"로써의 역활을 재발견하고자한다. 이러한 방법은 가족 및 간호과학에 새로운 접근법이며 간호의 영역이 얼마만큼 확대될 수 있는가를 나타내고 있다. (1) Toman의 Family Cnstellation 이론과 일치되는 점 및 일치되지 않는 점 (2) 한국인 핵가족에서 관찰된 비언어적 의사소통(non-verbal communication)및 이것과 Scheflen의 이론과의 관계 (3) family Theory Bowen의 "differentiation of self"와 "family projection Process"이론에 의한 분석 (4) 핵가족에서 관찰된 상호작용 유형(interactional pattern)을 분석 (5) Art Session을 통해서 관찰된 사항 및 Critique 결과적으로 이 핵가족은 사회적 가치관이 변화된데서 오는 갈등에 직면하고 있다. 우리 나라의 확대가족에서 강조된 경치관은 가족을 하나의 전체로써 보는 "우리 (we-ness)"였는데 이것은 일상사용하고 있는 언어에도 영향을 미치고 있는 것을 볼 수 있어 즉, "내 동생 (my sister)"이라고 하는 대신 "우리 동생 (our sister)"이라고 하는데 여기에서 언어가 뜻하는 의미와는 거리가 먼 것을 알 수 있다. 정씨 부부는 미국적 정치관을 인식해서 그들의 상호작용 유형을 긍정적이고 개방적인 토의방법으로(positive open-discuses) 접근해야 한다. 이 핵가족의 부부는 둘 다 유교사상이 강조된 가정에서 자라나, 이 부부가 결혼한지 오 년이나 되었으나 언어적 의사소통이 (verbal communication)굉장히 제한된 것을 쓸 수 있다. 인간의 경험들은 인간이 접하고 있는 사회와의 상호작용에 의해서 결정된다. 사회가 배화함에 따라서 가족도 변화할 것이다. "변화는 언제나 사회에서 부터 가족으로 온다. 이 변화는 절대 작은 단위에서 큰 단위로 오는 것이 아니다.…그러나 가족구조는(family structure) 환경이 변화함에 따라서 적응해야 한다."라고 Minuchin이 지적한 것 같이 정씨 부부가 직면하고 있는 여러 가지 갈등은 이 핵가족이 그들의 가치관 및 상호 작용유형을 변형(repattering) 시키므로써, 복잡하고 다양한 미국사회에서 성장할 수 있는 좋은 기회를 만들어 주고 있다. 세 번의 면담시간은 각 30분이었으나 Volume 생략한 것을 부기하여 둔다.