• 한국컴퓨터정보학회논문지
• /
• 제19권5호
• /
• pp.99-107
• /
• 2014

최근관광에도 여러 가지변화가 일어나고 있는데, 그 중 하나가 자연 그대로의 상태를 보고, 즐기는 도보관광이다. 본 연구는 이러한 도보관광지 체험과 도보관광객 만족도, 재방문 의도 간의 구조적 관계를 분석하여, 차후 지자체의 도보관광지 활성화를 위한 방안을 제시하는데 목적이 있다. 먼저 실증분석을 위해 북한산 둘레길을 방문하는 도보관광객들을 대상으로 서베이를 실시하였고, 수집된 자료 250부에 대해 SPSS 18 통계패키지를 이용하여 빈도분석, 요인분석, 신뢰도분석, 상관관계분석을 실시하였으며, 또한 AMOS 7.0을 활용하여 공분산구조분석(Covariance Structure Analysis)의 확인적 요인분석과 모형검증(Model Test)을 실시하였다. 그 결과 Pine과 Gilmore(1998)의 개념적 연구의 4가지(오락, 교육, 심미, 일탈) 요소 중 심미적 체험요소와 일탈적 체험요소가 도보관광객의 만족에 유의한 영향을 미쳤다. 또한 재방문 의사에 대한 만족도의 영향은 기존 연구에서 밝혀진 바와 같이 매우 강한 인과관계를 보여주었다. 연구결과는 도보관광객들의 만족도를 높여 재방문을 유도하기 위해서는 심미적 체험과 일탈적 체험의 질을 강화해야 한다는 시사점을 제공하였다.

• 한국산학기술학회논문지
• /
• 제16권11호
• /
• pp.7690-7697
• /
• 2015

본 연구는 사업시행의 핵심요인이라 할 수 있는 경제적 측면에서 조합원의 실질적인 입주부담금에 영향을 미치는 개별요인들의 구조적 인과구조를 밝히고, 모의실험과 실증분석을 통해 그 영향력을 파악하고자 하였다. 분석결과 첫째, 조합원의 실질적인 입주부담금은 조합원에게 적용되는 특별분양가와 일반분양가와의 차익 및 관리처분계획 인가 시점과 입주 시점의 시차에 의해 발생하는 시세차익을 반영하여 결정되는 것으로 나타났다. 둘째, 조합원의 실질적 입주부담금에 영향을 미치는 개별요인들의 민감도를 분석한 결과, 사업구역에 적용되는 계획용적률이 가장 큰 영향을 미치는 것으로 나타났다. 또한 사업구역 내 기반시설 설치 시 비용분담 주체에 따라서도 조합원의 입주부담금은 크게 영향을 받는 것으로 분석되었다. 셋째, 조합원 입주부담금 결정요인들 간의 인과관계를 기초로 구조모형을 설정하고, 이를 구조방정식모형(SEM)을 이용하여 개별요인들이 미치는 영향경로와 영향력을 실증적으로 살펴보았는데 규제요소 및 지역특성요소가 계획요소를 매개로 하여 입주부담금에 영향을 미치는 구조를 나타내었다.

• 대한의용생체공학회:의공학회지
• /
• 제27권5호
• /
• pp.224-228
• /
• 2006

The object of this study is to investigate the potential of dual-electrospun polymer based structure for vascular tissue engineering, especially for the medium or small sue blood vessels. Polyurethane(PU), which is known to be biocompatible in this area, was electrospun with poly(ethylene oxide) (PEO). Concentration of PU was fixed at 20wt%, while that of PEO was set from 15 to 35wt%. Morphological features were observed by SEM image and measurement of porosity and cellular responses were tested before and after extracting PEO from the hybrid scaffolds by immersing the scaffolds into distilled water. The diameter of PEO fibers were ranged from 200nm to 500nm. The lower concentration of PEO tended to show beads. The porosity of the scaffolds after extracting PEO was highly increased with higher concentration of PEO as expected. Also, higher proliferation rate of smooth muscle cells was observed at higher concentration of PEO than at the lower concentration and without PEO. As conclusions, this dual electrospinning technique combined with PU and PEO is expected to overcome the current barrier of cell penetration by providing more space for cells to proliferation.

• 대한치과재료학회지
• /
• 제44권1호
• /
• pp.69-77
• /
• 2017

The aim of this study was to investigate the effects of chitosan powder addition on the strengthening of conventional glass ionomer cement. Two types of chitosan powders with different molecular weight were mixed with conventional glass ionomer cement (GIC): low-molecular weight chitosan (CL; 50~190 kDa), high-molecular weight chitosan (CH; 310~375 kDa). The chitosan powders (CL and CH) were separately added into the GIC liquid (0.25-0.5 wt%) under magnetic stirring, or mixed with the GIC powder by ball-milling for 24 h using zirconia balls. The mixing ratio of prepared cement was 2:1 for powder to liquid. Net setting time of cements was measured by ISO 9917-1. The specimens for the compressive strength (CS; $4{\times}6mm$), diametral tensile strength (DTS; $6{\times}4mm$), three-point flexure (FS; $2{\times}2{\times}25mm$) with flexure modulus (FM) were obtained from cements at 1, 7, and 14 days after storing in distilled water at $(37{\pm}1)^{\circ}C$. All mechanical strength tests were conducted with a cross-head speed of 1 mm/min. Data were statistically analyzed by one-way ANOVA and Tukey HSD post-hoc test. The mechanical properties of conventional glass ionomer cement was significantly enhanced by addition of 0.5 wt% CL to cement liquid (CS, DTS), or by addition of 10 wt% CH (FS) to cement powder. The CL particles incorporated into the set cement were firmly bonded to the GIC matrix (SEM). Within the limitation of this study, the results indicated that chitosan powders can be successfully added to enhance the mechanical properties of conventional GIC.

• Structural Engineering and Mechanics
• /
• 제60권6호
• /
• pp.1063-1077
• /
• 2016

Components manufactured from composite materials are frequently subjected to superimposed mechanical and thermal loadings during their operating service. Both types of loadings may cause fracture and failure of composite structures. When composite cross-ply laminates of type [$0_m/90_n]_s$ are subjected to uni-axial tensile loading, different types of damage are set-up and developed such as matrix cracking: transverse and longitudinal cracks, delamination between disoriented layers and broken fibers. The development of these modes of damage can be detrimental for the stiffness of the laminates. From the experimental point of view, transverse cracking is known as the first mode of damage. In this regard, the objective of the present paper is to investigate the effect of transverse cracking in cross-ply laminate under thermo-mechanical degradation. A Finite Element (FE) simulation of damage evolution in composite crossply laminates of type [$0_m/90_n]_s$ subjected to uni-axial tensile loading is carried out. The effect of transverse cracking on the cross-ply laminate strength under thermo-mechanical degradation is investigated numerically. The results obtained by prediction of the numerical model developed in this investigation demonstrate the influence of the transverse cracking on the bearing capacity and resistance to damage as well as its effects on the variation of the mechanical properties such as Young's modulus, Poisson's ratio and coefficient of thermal expansion. The results obtained are in good agreement with those predicted by the Shear-lag analytical model as well as with the obtained experimental results available in the literature.

• Journal of Korea Trade
• /
• 제23권8호
• /
• pp.45-72
• /
• 2019

Purpose - This study examines the mediating effect of switching costs (economic risk costs and setup costs) on the relationships of country image with product attitude and product attachment. Switching-cost effects for the Korean Wave, which are insufficiently addressed in the literature, were investigated using the country image of Korea as a proxy for the Korean Wave. Moreover, this study examined the economic effects of the Korean Wave and the negative effect of the Terminal High Altitude Area Defense (THAAD) deployment on these economic effects. Design/methodology - A total of 302 Chinese consumers were surveyed using a questionnaire. Because this was an exploratory study and was not based on a classical model, the PLS-SEM method was employed to test the stability of the model and its hypotheses. Findings - Switching costs had mediating effects on the relationships of country image with product attitude and product attachment. The switching-cost effects for the Korean Wave were verified. However, neither the economic image nor cultural image of Korea had significant effects on the economic risk costs. Moreover, the economic image of Korea had no significant effect on the set-up costs. Originality/value - This study broadened the understanding of the relationships among country image, switching costs, product attitude, and product attachment and advanced the knowledge of relevant theories. The results contribute theoretically to the literature on switching-cost effects for the Korean Wave. The results confirmed the negative effect of THAAD deployment on the economic effects of the Korean Wave. In the rapidly developing international environment, these research results could serve as theoretical reference guidelines for suppliers when developing marketing strategies.

• Structural Engineering and Mechanics
• /
• 제68권5호
• /
• pp.575-589
• /
• 2018

It is well known that the incidence angle of seismic excitation has an influence on the structural response of buildings, and this effect can be more significant in the case of near-fault signals. However, current seismic codes do not include detailed requirements regarding the direction of application of the seismic action and they have only recently introduced specific provisions about near-fault earthquakes. Thus, engineers have the task of evaluating all the relevant directions or the most critical conditions case by case, in order to avoid underestimating structural demand. To facilitate the identification of the most critical incidence angle, this paper presents a procedure which makes use of a two-degree of freedom model for representing a building. The proposed procedure makes it possible to avoid the extensive computational effort of multiple dynamic analyses with varying angles of incidence of ground motion excitation, which is required if a spatial multi-degree of freedom model is used for representing a building. The procedure is validated through the analysis of two case studies consisting of an eight- and a six-storey reinforced concrete frame building, selected as representative of existing structures located in Italy. A set of 124 near-fault ground motion records oriented along 8 incidence angles, varying from 0 to 180 degrees, with increments of 22.5 degrees, is used to excite the structures. Comparisons between the results obtained with detailed models of the two structures and the proposed procedure are used to show the accuracy of the latter in the prediction of the most critical angle of seismic incidence.

• Structural Engineering and Mechanics
• /
• 제77권1호
• /
• pp.47-56
• /
• 2021

This paper deals with damage detection using a Gapped Smoothing Method (GSM) combined with deep learning. Convolutional Neural Network (CNN) is a model of deep learning. CNN has an input layer, an output layer, and a number of hidden layers that consist of convolutional layers. The input layer is a tensor with shape (number of images) × (image width) × (image height) × (image depth). An activation function is applied each time to this tensor passing through a hidden layer and the last layer is the fully connected layer. After the fully connected layer, the output layer, which is the final layer, is predicted by CNN. In this paper, a complete machine learning system is introduced. The training data was taken from a Finite Element (FE) model. The input images are the contour plots of curvature gapped smooth damage index. A free-free beam is used as a case study. In the first step, the FE model of the beam was used to generate data. The collected data were then divided into two parts, i.e. 70% for training and 30% for validation. In the second step, the proposed CNN was trained using training data and then validated using available data. Furthermore, a vibration experiment on steel damaged beam in free-free support condition was carried out in the laboratory to test the method. A total number of 15 accelerometers were set up to measure the mode shapes and calculate the curvature gapped smooth of the damaged beam. Two scenarios were introduced with different severities of the damage. The results showed that the trained CNN was successful in detecting the location as well as the severity of the damage in the experimental damaged beam.

• Structural Engineering and Mechanics
• /
• 제77권1호
• /
• pp.115-135
• /
• 2021

This paper focuses on examining the effects of span arrangements on displacement responses of plan-symmetric RC frame buildings designed using the direct displacement-based design (DDBD) method by employing non-linear analyses and the skew seismic attack. In order to show the desired performance of DDBD design approach, the force-based design approach is also used to examine the seismic performance of the selected structures. To realize this objective, 8-story buildings with different plans are selected. In addition, the dynamic behavior of the structures is evaluated by selecting 3, 7, and 12-story buildings. In order to perform non-linear analyses, OpenSees software is used for modeling buildings. Results of an experimental model are used to validate the analytical model implemented in OpenSees. The results of non-linear static and non-linear dynamic analyses indicate that changing span arrangements does not affect estimating the responses of structures designed using the DDBD approach, and the results are more or less the same. Next, in order to apply the earthquake in non-principle directions, DDBD structures, designed for one-way performance, are designed again for two-way performance. Time history analyses are performed under a set of artificial acceleration pairs, applied to structures at different angles. It is found that the mean maximum responses of earthquakes at all angles have very good agreement with the design-acceptable limits, while the response of buildings along the height direction has a relatively acceptable and uniform distribution. Meanwhile, changes in the span arrangements did not have a significant effect on displacement responses.

• Structural Engineering and Mechanics
• /
• 제77권3호
• /
• pp.343-354
• /
• 2021

The frequencies formulas of the bridge are of great importance in the design process since these formulas provide insight dynamic characteristics of the structure, which guides the designers to parametric analyses and the layout of the bridge in conceptual or preliminary design. Continuous rigid frame bridge is popular in the mountainous area. Mostly, this type of bridge was simplified either as a girder or cantilever when calculating the frequency, however, studies showed that the different configuration of the bridge made the problem more complex, and there is no unified fundamental calculation pattern for this kind of bridge. In this study, an empirical frequency equation is proposed as a function of pier's height, stiffness of pier and the weight of the structure. A unified fundamental frequency formula is presented based on the energy principle, then the typical continuous rigid frame bridge is investigated by finite element method (FEM) to study the dynamic characteristics of the structure, and then several key parameters are investigated on the effect of structural frequency. These parameters include the number, position and stiffness of the tie beam. Nonlinear regression analyses are conducted with a comprehensive statistical study from plenty of engineering structures. Finally, the proposed frequency equation is validated by field test results. The results show that the fundamental frequency of the continuous rigid frame bridge increases more than 15% when the tie beams are set, and it increases with the stiffness ratio of tie beam to pier. The results also show that the presented unified fundamental frequency has an error of 4.6% compared with the measured results. The investigation can predicate the approximate longitudinal fundamental frequency of continuous ridged frame bridge, which can provide reference for the seismic response and dynamic impact factor design of the pier.