• 감성과학
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• 제25권2호
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• pp.3-10
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• 2022

기억용이성은 자극이 얼마나 잘 기억될 수 있는가를 나타내는 척도로 자극의 지각적, 의미적 특성으로는 설명되지 않는 자극 고유의 특성이다. 기존의 기억용이성 연구는 주로 단독으로 제시된 자극을 얼마나 잘 기억할 수 있는가를 측정했다. 그러나 단일 자극만 제시하는 연구로는 다수의 자극이 동시에 나타나는 현실 세계의 시각 정보 처리 과정을 설명하는 데 한계가 있다. 이에 본 연구에서는 다수의 자극이 동시에 제시되었을 때 자극의 기억용이성 수준에 따라 기억 과제 수행이 어떻게 달라지는가를 알아봤다. 참가자들은 기억용이성이 높거나 낮은 방해자극과 동시에 제시된 목표자극을 기억하는 과제를 수행했다. 실험 결과, 목표자극의 기억용이성이 높았을 때 기억 수행이 향상되었으나, 목표자극의 기억용이성 효과는 동시에 제시된 방해자극의 기억용이성 수준의 영향을 받지 않았다. 이러한 결과는 높은 기억용이성을 가진 자극이 자동적으로 상향적 주의를 유도하지 않는다는 선행 연구 결과를 지지한다.

• Geomechanics and Engineering
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• 제33권1호
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• pp.1-9
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• 2023

The unconfined compression strength (UCS) of soils is commonly used either before or during the construction of geo-structures. In the pre-design stage, UCS as a mechanical property is obtained through a laboratory test that requires cumbersome procedures and high costs from in-situ sampling and sample preparation. As an alternative way, the empirical model established from limited testing cases is used to economically estimate the UCS. However, many parameters affecting the 1D soil compression response hinder employing the traditional statistical analysis. In this study, gene expression programming (GEP) is adopted to develop a prediction model of UCS with common affecting soil properties. A total of 79 undisturbed soil samples are collected, of which 54 samples are utilized for the generation of a predictive model and 25 samples are used to validate the proposed model. Experimental studies are conducted to measure the unconfined compression strength and basic soil index properties. A performance assessment of the prediction model is carried out using statistical checks including the correlation coefficient (R), the root mean square error (RMSE), the mean absolute error (MAE), the relatively squared error (RSE), and external criteria checks. The prediction model has achieved excellent accuracy with values of R, RMSE, MAE, and RSE of 0.98, 10.01, 7.94, and 0.03, respectively for the training data and 0.92, 19.82, 14.56, and 0.15, respectively for the testing data. From the sensitivity analysis and parametric study, the liquid limit and fine content are found to be the most sensitive parameters whereas the sand content is the least critical parameter.

• 한국재난정보학회 논문집
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• 제19권3호
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• pp.689-697
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• 2023

연구목적: 본 연구는 미니트렌칭 공법 적용 과정에서 범용 스마트폰을 이용하여 지중매설물의 정보를 자동 추출하는데 목적이 있다. 연구방법:이미지 학습을 위한 데이터 셋은 주야간, 높이, 각도 등의 다양한 조건에서 수집하였으며, 객체 검지알고리즘은 R-CNN 알고리즘을 이용하였다. 연구결과: 성능평가지표는 정확한 예측과 재현율의 평균을 동시에 고려할 수 있는 F1-Score를 적용하였으며, 학습결과 F1-Score는 0.76으로 나타났다. 결론: 본 연구의 결과는 스마트폰 기반의 지중매설물 정보 추출이 가능한 것으로 나타났으나, 학습데이터의 추가적인 확보와 현장 실증 등을 통해 알고리즘의 정밀성 및 정확성을 향상시킬 필요가 있을 것으로 판단된다.

• 한국심리학회지:법
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• 제11권2호
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• pp.155-171
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• 2020

본 연구는 거짓말 탐지 시 정서적 각성 및 인지적 부하가 동공 크기 변화에 미치는 영향을 확인했다. 총 60명 모집 후, 참가자가 자발적으로 집단을 선택했다. 유죄 집단(n = 30)은 모의 범죄(현금 훔치기)를 수행하고, 무죄 집단(n = 30)은 연구 조교 사무실에서 임무(메시지 보내기)를 수행했다. 그 후, 거짓말 탐지 면담 질문 중에 웨어러블 아이트래커를 사용하여 동공 크기를 측정했다. 면담 질문은 인지적 부하 질문 3개, 정서적 각성 질문 3개, 중립 질문 3개로 구성되었다. 실험 결과, 집단이나 시간의 주효과는 유의미하게 나타나지 않았으나, 집단과 시간의 상호작용은 유의미하게 나타났다. 즉, 동공 크기에 기반한 거짓말 탐지 시 인지적 부하 질문에 응답 할 때 유죄 집단이 무죄 집단 보다 동공 크기가 더 크게 증가했다. 이는 동공 크기를 기반한 거짓말 탐지 시 인지 부하를 유도하는 것이 정서적 각성을 유발하는 것보다 효과적임을 시사한다.

• Structural Engineering and Mechanics
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• 제86권4호
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• pp.443-459
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• 2023

This study investigates the theoretical thermal buckling analyses of thick porous rectangular functionally graded (FG) plates with different geometrical boundary conditions resting on a Winkler-Pasternak elastic foundation using a new higher-order shear deformation theory (HSDT). This new theory has only four unknowns and involves indeterminate integral variables in which no shear correction factor is required. The variation of material properties across the plate's thickness is considered continuous and varied following a simple power law as a function of volume fractions of the constituents. The effect of porosity with two different types of distribution is also included. The current formulation considers the Von Karman nonlinearity, and the stability equations are developed using the virtual works principle. The thermal gradients are involved and assumed to change across the FG plate's thickness according to nonlinear, linear, and uniform distributions. The accuracy of the newly proposed theory has been validated by comparing the present results with the results obtained from the previously published theories. The effects of porosity, boundary conditions, foundation parameters, power index, plate aspect ratio, and side-to-thickness ratio on the critical buckling temperature are studied and discussed in detail.

• 미래기술융합논문지
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• 제2권2호
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• pp.31-38
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• 2023

본 연구는 서 있는 자세에서 측정된 정적균형과 근육두께(배근육, 넙다리네갈래근)의 상관관계를 확인하였다. 29명의 건강한 성인 29명이 본 연구에 참여하였으며, 근육두께와 정적균형을 측정하였다. 넙다리곧은근의 근육 두께는 정적균형체중분포지수와 유의한 상관관계를 나타냈다. 그러나 다른 근육과의 유의한 관계는 발견되지 않았다. 본 연구는 건강한 20대 남성만을 대상으로 하였으며, 그 결과를 다른 연령대에 일반화할 수 없었다. 본 연구의 한계점으로는 근력과 시각이 측정되지 않아 연구의 정확성을 표현하고 결과를 일반화하기에는 무리가 있어 보인다. 향후 연구에서는 대단위의 피험자 수를 대상으로 근력을 추가적으로 측정하여 연구를 진행할 필요가 있다.

• Structural Engineering and Mechanics
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• 제85권4호
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• pp.531-543
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• 2023

The existing concrete bridges are time-varying working systems, where the maintenance strategy should be planned according to the time-varying performance of the bridge. This work proposes a time-dependent residual capacity assessment procedure, which considers the non-stationary bridge load effects under growing traffic and non-stationary structural deterioration owing to material degradations. Lifetime bridge load effects under traffic growth are predicated by the non-stationary peaks-over-threshold (POT) method using time-dependent generalized Pareto distribution (GPD) models. The non-stationary structural resistance owing to material degradation is modeled by incorporating the Gamma deterioration process and field inspection data. A three-span continuous box-girder bridge is illustrated as an example to demonstrate the application of the proposed procedure, and the time-varying reliability indexes of the bridge girder are calculated. The accuracy of the proposed non-stationary POT method is verified through numerical examples, where the shape parameter of the time-varying GPD model is constant but the threshold and scale parameters are polynomial functions increasing with time. The case study illustrates that the residual flexural capacities show a degradation trend from a slow decrease to an accelerated decrease under traffic growth and material degradation. The reliability index for the mid-span cross-section reduces from 4.91 to 4.55 after being in service for 100 years, and the value is from 4.96 to 4.75 for the mid-support cross-section. The studied bridge shows no safety risk under traffic growth and structural deterioration owing to its high design safety reserve. However, applying the proposed numerical approach to analyze the degradation of residual bearing capacity for bridge structures with low safety reserves is of great significance for management and maintenance.

• Steel and Composite Structures
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• 제46권6호
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• pp.839-856
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• 2023

This work presents a simple four-unknown refined integral plate theory for mechanical and thermal buckling behaviors of functionally graded (FG) plates resting on Visco-Pasternak foundations. The proposed refined high order shear deformation theory has a new displacement field which includes indeterminate integral variables and contains only four unknowns in which any shear correction factor not used, with even less than the conventional theory of first shear strain (FSDT). Governing equations are deduced from the principle of minimum total potential energy and a Navier type analytical solution is adopted for simply supported FG plates. The Visco-Pasternak foundations is considered by adding the impact of damping to the usual foundation model which characterized by the linear Winkler's modulus and Pasternak's foundation modulus. The accuracy of the present model is demonstrated by comparing the computed results with those available in the literature. Some numerical results are presented to show the impact of material index, elastic foundation type, and damping coefficient of the foundation, on the mechanical and thermal buckling behaviors of FG plates.

• Steel and Composite Structures
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• 제45권2호
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• pp.205-218
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• 2022

Proper calculation of splitting tensile strength (STS) of concrete has been a crucial task, due to the wide use of concrete in the construction sector. Following many recent studies that have proposed various predictive models for this aim, this study suggests and tests the functionality of three hybrid models in predicting the STS from the characteristics of the mixture components including cement compressive strength, cement tensile strength, curing age, the maximum size of the crushed stone, stone powder content, sand fine modulus, water to binder ratio, and the ratio of sand. A multi-layer perceptron (MLP) neural network incorporates invasive weed optimization (IWO), cuttlefish optimization algorithm (CFOA), and electrostatic discharge algorithm (ESDA) which are among the newest optimization techniques. A dataset from the earlier literature is used for exploring and extrapolating the STS behavior. The results acquired from several accuracy criteria demonstrated a nice learning capability for all three hybrid models viz. IWO-MLP, CFOA-MLP, and ESDA-MLP. Also in the prediction phase, the prediction products were in a promising agreement (above 88%) with experimental results. However, a comparative look revealed the ESDA-MLP as the most accurate predictor. Considering mean absolute percentage error (MAPE) index, the error of ESDA-MLP was 9.05%, while the corresponding value for IWO-MLP and CFOA-MLP was 9.17 and 13.97%, respectively. Since the combination of MLP and ESDA can be an effective tool for optimizing the concrete mixture toward a desirable STS, the last part of this study is dedicated to extracting a predictive formula from this model.

• Advances in concrete construction
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• 제14권3호
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• pp.153-167
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• 2022

The interaction between blast load and structures, as well as the interaction among structural members may well affect the structural response and damages. Therefore, it is necessary to analyse more realistic reinforced concrete structures in order to gain an extensive knowledge on the possible structural response under blast load effect. Among all the civilian structures, columns are considered to be the most vulnerable to terrorist threat and hence detailed investigation in the dynamic response of these structures is essential. Therefore, current research examines the effect of blast loads on the reinforced concrete columns via development of Pressure- Impulse (P-I) diagrams. In the finite element analysis, the level of damage on each of the aforementioned RC column will be assessed and the response of the RC columns when subjected to explosive loads will also be identified. Numerical models carried out using LS-DYNA were compared with experimental results. It was shown that the model yields a reliable prediction of damage on all RC columns. Validation study is conducted based on the experimental test to investigate the accuracy of finite element models to represent the behaviour of the models. The blast load application in the current research is determined based on the Lagrangian approach. To develop the designated P-I curves, damage assessment criteria are used based on the residual capacity of column. Intensive investigations are implemented to assess the effect of column dimension, concrete and steel properties and reinforcement ratio on the P-I diagram of RC columns. The produced P-I models can be applied by designers to predict the damage of new columns and to assess existing columns subjected to different blast load conditions.