• International Journal of Oral Biology
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• 제43권2호
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• pp.101-111
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• 2018

Understanding the classification of malocclusion is a crucial issue in Orthodontics. It can also help us to diagnose, treat, and understand malocclusion to establish a standard for definite class of patients. Principal component analysis (PCA) and k-means algorithms have been emerging as data analytic methods for cephalometric measurements, due to their intuitive concepts and application potentials. This study analyzed the macro- and meso-scale classification structure and feature basis vectors of 1020 (415 male, 605 female; mean age, 25 years) orthodontic patients using statistical preprocessing, PCA, random matrix theory (RMT) and k-means algorithms. RMT results show that 7 principal components (PCs) are significant standard in the extraction of features. Using k-means algorithms, 3 and 6 clusters were identified and the axes of PC1~3 were determined to be significant for patient classification. Macro-scale classification denotes skeletal Class I, II, III and PC1 means anteroposterior discrepancy of the maxilla and mandible and mandibular position. PC2 and PC3 means vertical pattern and maxillary position respectively; they played significant roles in the meso-scale classification. In conclusion, the typical patient profile (TPP) of each class showed that the data-based classification corresponds with the clinical classification of orthodontic patients. This data-based study can provide insight into the development of new diagnostic classifications.

• 한국콘텐츠학회논문지
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• 제21권9호
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• pp.762-770
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• 2021

본 연구에서는 고등학생의 스트레스와 행복감 간의 관계를 확인하고, 그 관계를 주관적 웰빙과 감사성향이 이중으로 매개하는지를 검증하고자 하였다. 연구 참여자는 남녀 고등학생 245명이었다. 이 연구를 위해서 지각된 스트레스 척도, 삶의 만족 검사, 정서빈도검사, 감사성향 척도 및 주관적 행복 척도를 사용하였다. 직렬적 이중 매개효과는 PROCESS Macro 3.5 모형 6으로 검증하였다. 연구 결과, 고등학생의 스트레스는 주관적 웰빙, 감사성향 및 행복감과 유의한 부적 상관이 있었다. 고등학생의 주관적 웰빙은 감사성향이나 행복감과 정적 상관이 있었으며, 감사성향도 행복감과 정적 상관이 있었다. 본 연구에서는 고등학생의 스트레스와 행복감 간의 관계를 주관적 웰빙과 감사성향이 직렬로 이중매개 하는 것으로 나타났다. 결론적으로 청소년들의 행복에 주관적 웰빙과 감사성향이 중요한 역할을 한다는 것이 발견되었기 때문에, 그들의 주관적 웰빙 수준과 감사성향을 증진시킬 필요가 있다.

• 한국콘텐츠학회논문지
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• 제22권3호
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• pp.189-196
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• 2022

본 연구는 성인의 거부민감성과 SNS 중독경향성의 관계를 온라인 사회적 지지가 조절하는지 검증하고자 한다. 이를 위해 전국 성인 486명을 대상으로 SNS 중독경향성 척도, 거부민감성 척도, 온라인 사회적 지지척도를 사용하여 설문조사를 실시하였다. 수집된 자료는 SPSS 27, PROCESS Macro 3.5를 활용하여 분석하였다. 본 연구결과 첫째, SNS 중독경향성, 거부민감성, 온라인 사회적 지지는 모두 정적상관이 있었다. 둘째, 거부민감성과 SNS 중독경향성의 관계에서 온라인 사회적 지지는 남자집단에서 조절효과가 나타났다. 이는 온라인 사회적 지지 수준에 따라 거부민감성으로 인한 SNS 중독경향성이 남자집단에서 다르게 나타남을 의미한 다. 본 연구의 결과는 남녀 집단에서 SNS 중독경향성을 확인하는데 거부민감성과 온라인 사회적 지지의 중요성을 확인하였다는데 의의가 있다. 이러한 결과를 바탕으로 본 연구의 한계점 및 후속연구를 위한 제언을 제시하였다.

• Structural Engineering and Mechanics
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• 제30권1호
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• pp.99-117
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• 2008

This paper presents a comprehensive approach to the evaluation of macroscopic material parameters for natural stone and quarry masonry. To that end, a reliable non-linear material model on a meso-scale is developed to cover the random arrangement of stone blocks and quasi-brittle behaviour of both basic components, as well as the impaired cohesion and tensile strength on the interface between the blocks and mortar joints. The paper thus interrelates the following three problems: (i) definition of a suitable periodic unit cell (PUC) representing a particular masonry structure; (ii) derivation of material parameters of individual constituents either experimentally or running a mixed numerical-experimental problem; (iii) assessment of the macroscopic material parameters including the tensile and compressive strengths and fracture energy.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2003년도 춘계학술대회 논문집
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• pp.215-218
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• 2003

Nano-scale experiments for adhesion force and friction force were performed with AFM/FFM. In macro-scale, the friction coefficient is constant without relating to the change of contact area. However, many papers have indicated that in nano-scale, the friction coefficient is related to the contact area. Contact area would increase with the normal force. Therefore, in this study, we analyzed the trend of the friction coefficient of Si(100) and Mica according to the normal force and then. the contact area was calculated by JKR-theory. Results showed the friction coefficient was constant under 180 nm$^2$ contact area and over 180 nm$^2$ contact area, it was degraded. Moreover. the friction coefficient was constant according to the adhesion force.

• 대한지리학회지
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• 제13권
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• pp.13-19
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• 1976

본 고에서는 기후학연구의 동향을 대략 살펴보고자 한다. 우리나라 기후학연구의 시작은 해방과 한국동란의 긴 격동기를 거쳐 1960년대에 들어와서라고 할 수 있고, 본격적인 연구는 1970년대에 들어서면서라고 볼 수 있다. 연구분야에 있어서는 기후분류를 주로했던 초기단계에서 기후요소나 변동을 다루게 되었고 최근에는 기후지형, 수분수지, 기단기후, 체감기후등의 방향으로 관심이 높아졌다. 그러나 meso scale이나 micro scale의 연구가 개척되지 않고 macro scale의 기후연구에 머물러 있는 감이 있다. 60년대 후반에서 70년대 초반에 걸친 우리나라의 산업근대화나 인구의 증가, 급속한 도시화에 따라 중기후나 소기후 연구의 필요성이 높아졌고 특히 일약팽창하는 도시에 있어서의 기후환경의 연구는 현대생활에 불가피의 과제이다. 이 방면에 약간의 연구가 시작되기는 하였지만 아직도 많은 연구문제가 방치되어있다. 중.소기후의 연구에는 현재보다 훨씬 많은 관측망의 설치가 선행되어야 할 것이며 도시기후의 관측에는 관측계기나 관측에 따르는 재정적인 문제가 달려있다. 이와같은 분야의 연구는 연구 team의 문제도 있어 개인연구로서는 도저히 감당하기 어려운 분야이다. 따라서 연구기관이나 국가의 지원하에 도시기후의 공동연구가 추진되어야 할 것이다.

• Geomechanics and Engineering
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• 제21권3호
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• pp.259-268
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• 2020

The synthetic rock mass (SRM) were used to investigate the influence of specimen size on the mechanical properties of jointed rock mass. The SRM were established based on parallel bond model (PBM) and smooth joint model (SJM) and the scaled rock specimens were sampled in two SRMs considering three sampling locations. The research results show that the smaller the initial fracture density is, the greater the uniaxial compressive strength (UCS), elastic modulus (E) is when compared with the same sampling location. The mechanical properties of rock specimens obtained by different sampling methods in different SRMs have different scale effects. The strength of rock specimens with more new cracks is not necessarily less than that of rock specimens with fewer new cracks and the failure of rock is caused by the formation of macro-fracture surface.

• International Journal of Advanced Culture Technology
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• 제11권3호
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• pp.247-252
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• 2023

The purpose of the study was to examine the mediating effect of kindergarten teachers' psychological burnout in the relationship between grit and teacher-child interactions. We conducted a cross-sectional study with 191 kindergarten teachers in South Korean. To measure the major variables, Grit scale [1], teacher-child interaction scale [2], and psychological burnout scale [3] were used. Hayes' PROCESS macro was used to test mediation effects of psychological burnout in the relationship between grit and teacher-child interactions. Indirect effects were tested using bootstrapped confidence intervals. As the results, kindergarten teachers' teacher-child interactions were found to have a significantly positive correlation with their grit but a significantly negative correlation with their psychological burnout. In addition, the relationship between grit and teacher-child interactions was mediated by psychological burnout.

• International Journal of Advanced Culture Technology
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• 제11권4호
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• pp.163-168
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• 2023

The purpose of the study was to examine the mediating effect of early childhood teachers' professional development in the relationship between intrapersonal intelligence and teacher-child interactions. We conducted a cross-sectional study with 324 early childhood teachers working at kindergartens and child-care centers in South Korea. The empirical data using survey questionnaires were collected by administering the Adult Introspective Intelligence Scale, the Professional Development Scale for Early Childhood Teachers, and the Teacher-child Interactions Scale. SPSS and Hayes' PROCESS macro weres utilized. The results showed the statistically positive correlations between the major variable and the mediating effect of early childhood teachers' professional development in the relationship between intrapersonal intelligence and teacher-child interactions.

• Structural Engineering and Mechanics
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• 제33권4호
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• pp.429-446
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• 2009

Three-scale homogenization procedure is proposed in this paper to provide estimates of the effective thermal conductivities of porous carbon-carbon textile composites. On each scale - the level of fiber tow (micro-scale), the level of yarns (meso-scale) and the level of laminate (macro-scale) - a two step homogenization procedure based on the Mori-Tanaka averaging scheme is adopted. This involves evaluation of the effective properties first in the absence of pores. In the next step, an ellipsoidal pore is introduced into a new, generally orthotropic, matrix to make provision for the presence of crimp voids and transverse and delamination cracks resulting from the thermal transformation of a polymeric precursor into the carbon matrix. Other sources of imperfections also attributed to the manufacturing processes, including non-uniform texture of the reinforcements, are taken into consideration through the histograms of inclination angles measured along the fiber tow path together with a particular shape of the equivalent ellipsoidal inclusion proposed already in Sko ek (1998). The analysis shows that a reasonable agreement of the numerical predictions with experimental measurements can be achieved.