• Structural Engineering and Mechanics
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• 제73권6호
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• pp.651-666
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• 2020

In this study, the spatial variation mechanisms of large far-field earthquakes at engineering scales are first investigated with data from the 2008 Ms 8.0 Wenchuan earthquake. And a novel 'coherency cut-off frequency' is proposed to distinguish the spatial variations in ground motions in the low-frequency and high-frequency ranges. Then, a practical piecewise coherency model is developed to estimate and characterize the spatial variation in earthquake ground motions, including the effects of source-to-site distances, site conditions and neighboring topography on these variations. Four particular earthquake records from dense seismograph arrays are used to investigate values of the coherency cut-off frequency for different source-to-site distances. On the basis of this analysis, the model is established to simulate the spatial variations, whose parameters are suitable for both near- and far-field earthquake conditions. Simulations are conducted to validate the proposed model and method. The results show that compared to the existing models, the proposed model provides an effective method for simulating the spatial correlations of ground motions at local sites with known source-to-site distances.

• 응용통계연구
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• 제28권2호
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• pp.325-334
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• 2015

한국의 고령화는 매우 빠른 속도로 진행되고 있고, 노인자살은 노인의 주요 사망원인이며 노인은 다른 연력층보다 자살의 고위험군으로 알려져있다. 고령화 시대에서 노인의 자살은 사회적인 문제로 대두되고 있으며 이를 예방하기 위해 노인자살에 대한 위험요인을 파악하고, 지역적 차이를 확인하는 것이 중요하다. 특히 노인의 자살문제에서는 지역사회와의 통합결여 등이 큰 원인으로 고려되기 때문이다. 따라서, 본 논문에서는 공간적 상관관계를 고려하여 추정된 표준화사망률을 이용하여 질병지도를 작성하고자 하였다. 공간적 상관관계를 고려하기 위해서 simultaneous CAR model을 사용하였다. 2006년부터 2010년까지 통계청 사망자료를 이용하여 국내 시군구별 노인자살자수에 대해 두 모형을 적합시켜본 결과, 공간적 상관관계를 고려하지 않은 모형보다 공간적 상관관계를 고려한 모형이 더 좋은 모형임을 보였다. 또한 효율적인 베이지안 추론을 위해 격자망 방법 등을 고려하였다.

• 한국수학교육학회지시리즈C:초등수학교육
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• 제16권3호
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• pp.303-313
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• 2013

공간능력은 수학의 직관적 관점과 수학적 이해 및 수학적 성취도와도 밀접한 관련이 있다는 점에서 매우 중요한 능력으로 평가될 수 있다. 본 연구에서는 초등학교 4, 5, 6학년 학생 1228명을 대상으로 공간시각화능력을 조사하였다. 이를 통하여 다음과 같은 연구결과를 얻을 수 있었다. 첫째, 공간시각화 능력과 수학성취도, 공간시각화 능력과 공간시각화 검사시간 사이에 상관관계가 있다. 둘째, 공간능력은 남녀 사이에 차이가 있었으며, 남학생이 여학생보다 더 높게 나타났다. 셋째, 공간능력은 학년수준에서 4학년보다는 5학년이 높았으며, 5학년보다는 6학년이 더 높게 나타났다.

• 대한원격탐사학회지
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• 제30권3호
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• pp.375-381
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• 2014

Soil moisture is an essential satellite-driven variable for understanding hydrologic, pedologic and geomorphic processes. The European Space Agency (ESA) has endorsed soil moisture as one of Climate Change Initiates (CCI) and had merged multi-satellites over 30 years. The $0.25^{\circ}$ coarse resolution soil moisture satellite data showed correlations with variables of a water stress index, Temperature-Vegetation Dryness Index (TVDI), from a stepwise regression analysis. The ancillary data from TVDI, Land Surface Temperature (LST) and Normalized Difference Vegetation Index (NDVI) from MODIS were inputted to a multi-regression analysis for estimating the surface soil moisture. The estimated soil moisture was validated with in-situ soil moisture data from April, 2012 to March, 2013 at Andong observation sites in South Korea. The soil moisture estimated using satellite-based LST and NDVI showed a good agreement with the observed ground data that this approach is plausible to define spatial distribution of surface soil moisture.

• 한국실내디자인학회논문집
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• 제18권3호
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• pp.47-56
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• 2009

This research aims to analyze the characteristics of the architectural space of Rem Koolhaas based on the spatial discourse of Gilles Deleuze, a philosopher of post-structuralism which comprehends pluralism accepting even contingency and uncertainty beyond deterministic attitudes of structuralism that has led the western discourses since the 19th century. First of all, this research will reflect on Deleuze's spatial concept through literatures and extract the characteristics related to architectural spaces. Then, on the basis of these characteristics, it will analyze the characteristics which were applied to the interior space of the recent architectural works of Rem Koolhaas to find out how Deleuze's spatial dicourse was embodied. Among Deleuze's speculations, the characteristics which falls under the spatial discourse were classified into three categories; degree between the striated space and the smooth one, the space of events and singularity, and the space of the multiple sense. These analysis words are used to look into the correlations among the specific practicing methods embodied in the architecture of Kookhaas. In conclusion, in the architectural space of Rem Koolhaas, it was found that the characteristics of Gilles Deleuze's spatial discourse of post-structuralism were embodied by the methods such as (1) Space of continuous transition, (2) Space of the $multiplicit{\acute{e}}$ accepting contingent events, (3) Space of the multiple sense, and (4) Space of movement.

• 영재교육연구
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• 제22권2호
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• pp.371-386
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• 2012

본 연구는 공간능력이 영재학생들을 판별하는데 중요한 요소로 작용한다는 전제하에 한국의 중학교 영재학생들과 일반학생의 공간능력을 비교하는 것을 주 목적으로 하고 있다. 이를 위하여 한국의 중학생들에게 '퍼듀 공간 시각화 검사: 회전의 시각화(Revised PSVT:R)'를 실시하였다. Revised PSVT:R의 타당도 검증을 위하여 확인적 요인분석을 실시하였으며, 이를 바탕으로 영재 학생들과 일반 학생들의 공간 능력 차이를 비교하였다. 연구 결과, 영재학생들은 일반학생들보다 공간능력에 있어서 훨씬 우수하였다. 공간 능력에 대한 검사 결과를 확장하여 공간능력과 수학, 과학, 언어 분야와의 관계를 살펴보았다. 공간능력은 수학, 과학, 언어분야와 상관관계가 높은 것으로 나타났다. 이상의 연구 결과를 종합하여 볼 때, 공간능력이 우수한 학생과 영재교육에 참여하고 있는 영재학생은 같은 특성이 있는 것으로 판단된다. 따라서 공간능력은 영재학생을 판별하는 중요한 검사도구로 포함되어야 할 것이다.

• 한국전산유체공학회:학술대회논문집
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• 한국전산유체공학회 2008년도 춘계학술대회논문집
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• pp.189-192
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• 2008

Turbulent coherent structure near rod-roughened wall are investigated by analyzing the database of direct numerical simulation of turbulent boundary layer. The roughness sublayer id defined as two-point correlations are not independent of streamwise locations around roughness. The roughness sublayer based on the two-point spatial correlation is different from that given by one-point statistics. Quadrant analysis and probability-weighted Reynolds shear stress indicate that turbulent structures are not affected by surface roughness above the roughness sublayer defined by the spatial correlations. The conditionally-averaged flow fields associated with Reynolds shear stress producing Q2/Q4 events show that though turbulent vortices are affected in the roughness sublayer, these are very similar at different streamwise locations above the roughness sublayer. The Reynolds stress producing turbulent vortices in the log layer have almost the same geometrical shape as those in the smooth wall-bounded turbulent flows. This suggests that the mechanism by which the Reynolds stress is produced in the log layer has not been significantly affected by the present surface roughness.

• Wind and Structures
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• 제29권6호
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• pp.471-488
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• 2019

Wind pressure is a critical argument for the wind-resistant design of structures. The attempt, however, to explore the wind pressure field on buildings still encounters challenges though a large body of researches utilizing wind tunnel tests and wind field simulations were carried out, due to the difficulty in logical treatments on the scale effect and the modeling error. The full-scale measurement has not yet received sufficient attention. By performing a field measurement, the present paper systematically addresses wind pressures on the rectangular attic of a double-tower building. The spatial and temporal correlations among wind speed and wind pressures at measured points are discussed. In order to better understand the wind pressure distribution on the attic facades and its relationship against the approaching flow, a full-scale CFD simulation on the similar rectangular attic is conducted as well. Comparative studies between wind pressure coefficients and those provided in wind-load codes are carried out. It is revealed that in the case of wind attack angle being zero, the wind pressure coefficient of the cross-wind facades exposes remarkable variations along both horizontal and vertical directions; while the wind pressure coefficient of the windward facade remains stable along horizontal direction but exposes remarkable variations along vertical direction. The pattern of wind pressure coefficients, however, is not properly described in the existing wind-load codes.

• 대한기계학회논문집B
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• 제32권6호
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• pp.463-470
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• 2008

Turbulent coherent structures near rod-roughened wall are investigated by analyzing the database of direct numerical simulation of turbulent boundary layer. The surface roughness rods with the height $k/{\delta}=0.05$ are arranged periodically in $Re_{\delta}=9000$. The roughness sublayer is defined as two-point correlations are not independent of streamwise locations around roughness. The roughness sublayer based on the two-point spatial correlation is different from that given by one-point statistics. Quadrant analysis and probability-weighted Reynolds shear stress indicate that turbulent structures are not affected by surface roughness above the roughness sublayer defined by the spatial correlations. The conditionally-averaged flow fields associated with Reynolds shear stress producing Q2/Q4 events show that though turbulent vortices are affected in the roughness sublayer, these are very similar at different streamwise locations above the roughness sublayer. The Reynolds stress producing turbulent vortices in the log layer ($y/{\delta}=0.15$)have almost the same geometrical shape as those in the smooth wall-bounded turbulent flows. This suggests that the mechanism by which the Reynolds stress is produced in the log layer has not been significantly affected by the present surface roughness.

• 교육시설 논문지
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• 제18권5호
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• pp.61-71
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• 2011

The purpose of this paper is to analyze university students' types of spatial consumptive decision behavior in order to provide a guideline on development of creative squares on campus. In particular, it is investigated how student's general characteristics, such as gender, age and major, awareness of creative squares, and preferred spatial types have influence on types of spatial decision consumptive behavior. In addition, correlations among the factors and types are analyzed. As a specific method for gathering information, a questionnaire composed of 46 questions was drawn up to conduct a survey of 206 students of S University in Seoul. The collected data from the survey were analyzed using SPSS windows v17.0. Based on a few previous works, the spatial consumptive decision behavior is classified into four types with Crombach ${\alpha}=0.794$ : 'Exploration' type, 'Experience' type, 'Showing-off type, and 'Trend-Following' type. The main results of this paper can be summarized as follows. First, all factors that affect spatial consumptive decision behavior are more or less correlated with one another. Second, awareness of creative square is significantly different according to the age and major of students. Third, in general, the 'Exploration' type embraces the largest number of students, followed by 'Experience' type, 'Showing-off type, and 'Trend-Following' type. Fourth, the portion of students belonging to each type is a little different according to the major of students. Finally, each type of spatial consumptive decision behavior is highly correlated with the gender and preferred spatial types of students. It was also found that all types of students prefer three to five specific spatial types. Accordingly, the identified spatial types can be exploited in developing a creative square in campus. The results of this paper are expected to expedite follow-up research on creative squares on campus under various conditions.