• Title/Summary/Keyword: cohesion

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Scale Effects of Initial Model and Material on 3-Dimensional Distinct Element Simulation (3차원 개별요소해석 시의 초기 모델 및 재료 스케일 영향)

  • Jeon, Jesung;Shin, Donghoon;Ha, Iksoo
    • Journal of the Korean GEO-environmental Society
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    • v.12 no.7
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    • pp.57-65
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    • 2011
  • Numerical simulations by three-dimensional Particle Flow Code($PFC^{3D}$, Itasca) considering distinct element method (DEM) were carried out for prediction of triaxial compression test with sand material. The effect of scale conditions for numerical model and distinct material on final prediction results was analyzed by numerical models under various scale conditions, and following observations were made from the numerical experiments. It is very useful to model the initial material condition without any porosity conversion from 2-D to 3-D DEM. Numerical experiments have shown that in all cases considered, 3D distinct element modeling could provide good agreement on stress-strain behavior, volume change and strength properties with laboratory testing results. It was important thing to assess reasonable scale ratio of numerical model and distinct elements for saving calculation time and securing calculation efficiency under condition with accuracy and appropriateness as numerical laboratory. As results of DEM simulations under various scale conditions, most of results show that shear strength properties as cohesion and internal friction angle are similar in condition of $D_{mod}/D_{gmax}$ < 10. It shows that 3-D distinct element method could be used as efficient tool to assess strength properties by numerical laboratory technique.

Suicide among the Elderly in Korea: A Meta-Analysis (노인의 자살생각에 영향을 미치는 요인군에 대한 메타분석)

  • Lee, Jung-eun;Lyu, Jiyoung
    • 한국노년학
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    • v.37 no.3
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    • pp.601-616
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    • 2017
  • Elderly suicide is a major public health issue in South Korea. The aim of this study was to systematically examine the current knowledge about suicidal ideation among Korean older adults with specific focus on risk and preventive factors. In order to achieve this aim, a meta-analysis was conducted using Korean academic peer-reviewed journals published since 2001. A total of 97 articles were selected that met the research criteria (e.g., original study findings and key words of suicidal ideation, suicidal thought, and suicide). Three domains were identified and used for further analysis: individual, family, and society. Results showed that among individual factors, depression and burden or stress increased the risk of suicidal ideation, while better mental health reduced the risk of suicidal ideation. Among family factors, living alone was a risk factor for suicidal ideation, while family cohesion was a preventive factor for suicidal ideation. Among social factors, elderly discrimination, social isolation, and negative relationships were significant risk factors, while social support, social environment, and social activities were significant preventive factors affecting suicidal ideation. The results suggest several practical implications for developing suicide prevention programs and counseling approaches to address suicidal ideation. For example, depression and stress can be reduced by MBSR (Mindfulness-Based Stress Reduction) program where meditation is used as a coping strategy. In addition, counseling programs specifically focused on improving family and social relations should be implemented. Government should continuously support for these programs to prevent suicide among older Koreans.

Evaluation of the Stability of Ipseok-dae Columnar Joints in Mudeungsan National Park Using 3DEC (3DEC을 이용한 무등산국립공원 입석대 주상절리대의 안정성 평가)

  • Noh, Jeongdu;Kang, Seong Sueng
    • The Journal of Engineering Geology
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    • v.32 no.3
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    • pp.351-361
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    • 2022
  • Numerical analysis performed to predict the behavior of Ipseok-dae columnar joints in Mudeungsan National Park to understand their stability and movement. The numerical analysis technique, 3DEC, is based on the discrete element method that can analysis discontinuities. The analysis used data for material properties derived from laboratory tests, which found that average density was 2.68 kN/m3, average normal stiffness was 3.15 GPa/m, average shear stiffness was 1.00 GPa/m, average cohesion was 0.51 MPa, and the average friction angle was 33°. The Ipseok-dae columnar joints were modeled on the basis of the field survey data for 15 joints located between the observation platform and the hiking trail. The numerical analysis assessed the behavior of each columnar joint by interpreting the displacement of the edges of its upper and lower surfaces. The greatest maximum displacement was found in columnar joint No. 6, and the greatest minimum displacement was found in joint No. 11. Analyzing the movements of five discontinuities in joint No. 11 indicated that the maximum displacement occurred at the 2nd level. The other levels were ordered 5th, 4th, 1st, and 3rd in terms of subsequent greatest displacements. Considering the total displacement in the 15 studied joints, the Ipseok-dae columnar joints are judged to be stable. However, considering the cultural and historical value of Mudeungsan National Park, it is regarded that the currents slope stability should be maintained by monitoring the individual rock blocks of the joints.

The effects of stress perception due to COVID-19 and category coherence on category-based inductive generalization (코로나-19로 인한 스트레스 지각과 범주 응집성이 범주기반 귀납적 일반화에 미치는 효과)

  • Lee, Guk-Hee;Doh, Eun Yeong
    • Korean Journal of Cognitive Science
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    • v.33 no.3
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    • pp.135-154
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    • 2022
  • The purpose of this study was to confirm that the property generalization to social categories with low coherence is stronger when stress due to COVID-19 is perceived as high, compared to when stress is perceived as low. To this end, this study selected categories with high coherence(nun, soldier, flight attendant) and categories with low coherence(wedding planner, interpreter, florist), and recruited 336 participants to perform a category-based inductive generalization task(inferring how many properties repeatedly observed by some category members would appear across all category members), and measured their perceived COVID-19 stress. As a result, this study showed that when the cohesion of social categories is high, the effect of property generalization is stronger than when it is low, and the effect of property generalization is stronger in those who perceive stress due to Corona 19 higher than those who perceive it as low. In addition, this study confirmed that people who perceive COVID-19 stress strongly tend to generalize strongly to properties that are repeatedly observed in the low coherence category. This study is important in that it shows that there is a cognitive mechanism that is at the root of the phenomenon that stereotypes and prejudices deepen and discriminatory behaviors increase after the outbreak of COVID-19, such as COVID-19 stress and the resulting increase in attribute generalization tendency.

Navigating Identity: A Qualitative Content Analysis of Related Field Professionals' Views on Arts Education for North Korean Refugee Youth (탈북 청소년 대상 문화예술교육에 대한 질적 내용 분석 연구 - 정체성 형성 과정을 중심으로 -)

  • Shin, Hyesun;Youn, Hyunkyoung
    • Korean Association of Arts Management
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    • no.55
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    • pp.75-113
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    • 2020
  • This research aims to identify current issues of arts education programs which have designed for North Korean Refugee Youth in South Korea and then navigates further steps to better serve the group. The purpose of study also pertains to the '2010 Seoul Agenda: Goals for the Development of Arts Education' announced at the Second World Conference on Arts Education, particularly, to the third Goal indicating how arts education practices can contribute to resolving social and cultural issues and promoting social cohesion and intercultural dialogues (UNESCO, 2010). This research engages with critical theory approach and adopts qualitative content analysis for collected documents and interview data. Based on the findings of this research, interview participants found its need of current arts education program for North Korean refugee youth become more value-driven and participant-centered. Currently, those programs available seem to incline to helping their adjustment to the South Korean society through arts-related activities, such as enhancing Korean language skills and learning Korean culture. Rather, it has been addressed that providing emotional and psychological supports and opportunities to search their own 'voice(s)' should be core objectives of the arts education programs. Moreover, when it is offered, arts educators and administrators need to make sure that participants can feel safe and secure as being present at the space for programs in order to express and encounter their true inner voice(s).

Outdoor Healing Places Perception Analysis Using Named Entity Recognition of Social Media Big Data (소셜미디어 빅데이터의 개체명 인식을 활용한 옥외 힐링 장소 인식 분석)

  • Sung, Junghan;Lee, Kyungjin
    • Journal of the Korean Institute of Landscape Architecture
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    • v.50 no.5
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    • pp.90-102
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    • 2022
  • In recent years, as interest in healing increases, outdoor spaces with the concept of healing have been created. For more professional and in-depth planning and design, the perception and characteristics of outdoor healing places through social media posts were analyzed using NER. Text mining was conducted using 88,155 blog posts, and frequency analysis and clique cohesion analysis were conducted. Six elements were derived through a literature review, and two elements were added to analyze the perception and the characteristics of healing places. As a result, visitors considered place elements, date and time, social elements, and activity elements more important than personnel, psychological elements, plants and color, and form and shape when visiting healing places. The analysis allowed the derivation of perceptions and characteristics of healing places through keywords. From the results of the Clique, keywords, such as places, date and time, and relationship, were clustered, so it was possible to know where, when, what time, and with whom people were visiting places for healing. Through the study, the perception and characteristics of healing places were derived by analyzing large-scale data written by visitors. It was confirmed that specific elements could be used in planning and marketing.

Types and Characteristics of Landslides in Danyang Geopark (단양 지질공원 내의 산사태 유형과 특징)

  • Seong-Woo Moon;Ho-Geun Kim;Yong-Seok Seo
    • The Journal of Engineering Geology
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    • v.33 no.3
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    • pp.427-438
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    • 2023
  • We carried out a geological survey to classify the types of mass movement in Danyang Geopark (where various rock types are distributed) and analyzed the mechanical and hydraulic characteristics of landslide materials using a series of laboratory tests. Debris flows occurred in areas of limestone/marble, shale, and porphyroblastic gneiss, and limestone/marble landslides were distinguished from the others through the presence of karren topography. Soil tests showed that soil derived from weathered gneiss, which has a higher proportion of coarse grains, has a higher friction angle, lower cohesion, and larger hydraulic conductivity than soils from areas of limestone/marble, and shale. Rock failure mass movements occurred in areas of phyllite, sandstone, and conglomerate and were subdivided into plane failure, block-fall, and boulder-fall types in areas of phyllite, sandstone, and conglomerate, respectively. The shear strength of phyllite is much lower than that of the other types of rock, which have similar rock quality. The slake durability index of the conglomerate is similar to that of the other rock types, which have similar degrees of weathering, but differential weathering of the matrix and clasts was clearly observed when comparing the samples before and after the test. This study can help establish appropriate reinforcement and disaster prevention measures, which depend on the type of mass movement expected given the geological characteristics of an area.

How has Brexit changed the UK: Deepening of Social Division and Increase of Rancour (브렉시트(Brexit)가 바꾼 영국: 사회적 분열의 심화와 증오의 확산)

  • Sungwook Yoon
    • Analyses & Alternatives
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    • v.7 no.2
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    • pp.79-110
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    • 2023
  • The purpose of this research is to explore the relation between Brexit and division in various areas within the British society. This research can lead to understanding how division of the British society and the decision of Brexit was mutually influenced. The UK's withdrawal from the EU has been explained mainly through the relations between the EU and the UK; therefore, issues of immigration, EU regulation, and the UK's EU rebate are considered as major reasons. In addition, 'British identity' or 'British exceptionalism' existing in the British society and politics for a long time has been regarded as a reason for Brexit. Although it is generally accepted that Brexit results in the division in the British society, the reasons mentioned above have limitation to explain the result of referendum and the division of the British society in the post-Brexit era. In this sense, this research explores the division in various areas - generation, social grade including income and education level, value and region, etc. - revealed in the British society is not the result of Brexit; rather, this research argues division deeply rooted in the British society before referendum is the root cause of Brexit. The division in various areas immanent in the British society for a long time is complicatedly intertwined, and the decision on Brexit by referendum has led to solidifying the division of the British society. Having considered this division in the British society has been expanded to rancour, it is necessary for the UK to establish appropriate policies for national cohesion.

Development of Stability Evaluation Algorithm for C.I.P. Retaining Walls During Excavation (가시설 벽체(C.I.P.)의 굴착중 안정성 평가 알고리즘 개발)

  • Lee, Dong-Gun;Yu, Jeong-Yeon;Choi, Ji-Yeol;Song, Ki-Il
    • Journal of the Korean Geotechnical Society
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    • v.39 no.9
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    • pp.13-24
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    • 2023
  • To investigate the stability of temporary retaining walls during excavation, it is essential to develop reverse analysis technologies capable of precisely evaluating the properties of the ground and a learning model that can assess stability by analyzing real-time data. In this study, we targeted excavation sites where the C.I.P method was applied. We developed a Deep Neural Network (DNN) model capable of evaluating the stability of the retaining wall, and estimated the physical properties of the ground being excavated using a Differential Evolution Algorithm. We performed reverse analysis on a model composed of a two-layer ground for the applicability analysis of the Differential Evolution Algorithm. The results from this analysis allowed us to predict the properties of the ground, such as the elastic modulus, cohesion, and internal friction angle, with an accuracy of 97%. We analyzed 30,000 cases to construct the training data for the DNN model. We proposed stability evaluation grades for each assessment factor, including anchor axial force, uneven subsidence, wall displacement, and structural stability of the wall, and trained the data based on these factors. The application analysis of the trained DNN model showed that the model could predict the stability of the retaining wall with an average accuracy of over 94%, considering factors such as the axial force of the anchor, uneven subsidence, displacement of the wall, and structural stability of the wall.

A Dilemma of Kyrgyzstan Goes Through the Process of Nation-Building: National Security Problems and Independent National Defense Capability (국가건설과정에서 키르기스스탄의 국가안보와 자주국방의 딜레마)

  • Kim, Seun Rae
    • Journal of International Area Studies (JIAS)
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    • v.14 no.4
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    • pp.27-52
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    • 2011
  • The regions of Central Asia have each acquired an elevated strategic importance in the new security paradigm of post-September 1lth. Comprised of five states, Kazakhstan, Kyrgyzstan, Tajikistan, Turkmenistan and Uzbekistan, Central Asia's newly enhanced strategic importance stems from several other factors, ranging from trans-national threats posed by Islamic extremism, drug production and trafficking, to the geopolitical threats inherent in the region's location as a crossroads between Russia, Southwest Asia and China. Although the U.S. military presence in the region began before September 11th, the region became an important platform for the projection of U.S. military power against the Taliban in neighboring Afghanistan. The analysis goes on to warn that 'with US troops already in place to varying extents in Central Asian states, it becomes particularly important to understand the faultlines, geography, and other challenges this part of the world presents'. The Kyrgyz military remains an embryonic force with a weak chain of command, the ground force built to Cold War standards, and an almost total lack of air capabilities. Training, discipline and desertion - at over 10 per cent, the highest among the Central Asian republics - continue to present major problems for the creation of combat-effective armed forces. Kyrgyzstan has a declared policy of national defence and independence without the use of non-conventional weapons. Kyrgyzstan participates in the regional security structures, such as the Collective Security Treaty Organisation (CSTO) and the Shanghai Co-operation Organisation (SCO) but, in security matters at least, it is dependent upon Russian support. The armed forces are poorly trained and ill-equipped to fulfil an effective counter-insurgency or counter-terrorist role. The task of rebuilding is much bigger, and so are the stakes - the integrity and sovereignty of the Kyrgyz state. Only democratization, the fight against corruption, reforms in the military and educational sectors and strategic initiatives promoting internal economic integration and national cohesion hold the key to Kyrgyzstan's lasting future