• Structural Engineering and Mechanics
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• v.84 no.6
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• pp.707-722
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• 2022

In this study, a new refined hyperbolic shear deformation theory (RHSDT) is developed using an equivalent single-layer shell displacement model for the static bending and free vibration response of cross-ply laminated composite spherical shells. It is based on a new kinematic in which the transverse displacement is approximated as a sum of the bending and shear components, leading to a reduction of the number of unknown functions and governing equations. The proposed theory uses the hyperbolic shape function to account for an appropriate distribution of the transverse shear strains through the thickness and satisfies the boundary conditions on the shell surfaces without requiring any shear correction factors. The shell governing equations for this study are derived in terms of displacement from Hamilton's principle and solved via a Navier-type analytical procedure. The validity and high accuracy of the present theory are ascertained by comparing the obtained numerical results of displacements, stresses, and natural frequencies with their counterparts generated by some higher-order shear deformation theories. Further, a parametric study examines in detail the effect of both geometrical parameters (i.e., side-to-thickness ratio and curvature-radius-to-side ratio), on the bending and free vibration response of simply supported laminated spherical shells, which can be very useful for many modern engineering applications and their optimization design.

• Journal of the Korean Society for Precision Engineering
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• v.21 no.8
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• pp.106-111
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• 2004

Micro-stereolithography technology has made it possible to fabricate any form of three-dimensional microstructures. It makes a 3D structure by dividing the shape into many slices of relevant thickness along horizontal surface, hardening each layer of slice with a laser, and stacking them up to a desired shape. Until now, however, the micro-stereolithography device was not designed systematically because the key factors governing the device were not considered. In this paper, we designed micro-stereolithography device using axiomatic approach. This paper contains an overview and an analysis of a new proposed system for development of micro-stereolithegraphy device, and detailed descriptions of the activities in this system. The newly designed system offers reduced machine size by minimizing of optical components and decoupled design matrix.

• Journal of the Korean Society for Precision Engineering
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• v.17 no.3
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• pp.200-207
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• 2000

The analysis of interference and efficiency are important phases in the design of planetary gear train. Because most planetary gear trains contain internal gear called ring gear, interferences between ring gear and planet gear should be analyzed in the step of design and manufacturing. Addendum modification coefficient, pressure angle, speed ratio between ring gear and sun gear are governing factors for interferences. In this paper, the interferences of 2K-H I type planetary gear train based on various planetary gear trains are studied. As that results, the ranges of addendum modification coefficients which would not lead to interferences is analyzed. Based on these ranges, theoretical efficiencies are investigated as 6 configurations of 2K-H I type planetary gear train, which is based on basic efficiency, and optimal addendum modification coefficients which generate the maximum efficiency of planetary gear train are presented. To prove results of theoretical efficiency analysis, experimentations are performed.

• Steel and Composite Structures
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• v.27 no.2
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• pp.135-147
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• 2018

Quasi-static three-point bending tests on sandwich beams with expanded metal sheets as core were conducted. Relationships between the force and displacement at the mid-span of the sandwich beams were obtained from the experiments. Numerical simulations were carried out using ABAQUS/EXPLCIT and the results were thoroughly compared with the experimental results. A parametric analysis was performed using a Box-Behnken design (BBD) for the design of experiments (DOE) techniques and a finite element modeling. Then, the influence of the core layers number, size of the cell and, thickness of the substrates was investigated. The results showed that the increase in the size of the expanded metal cell in a reasonable range was required to improve the performance of the structure under bending collapse. It was found that core layers number and size of the cell was key factors governing the quasi-static response of the sandwich beams with lattice cores.

• Structural Engineering and Mechanics
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• v.29 no.1
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• pp.1-16
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• 2008

Tunnels are generally constructed below the ground water table, which produces a long-term interaction between the tunnel lining and the surrounding geo-materials. Thus, in conjunction with tunnel design, the presence of water may require a number of considerations such as: leakage and water load. It has been reported that deterioration of a drainage system of tunnels is one of the main factors governing the long-term hydraulic and structural lining-ground interaction. Therefore, the design procedure of an underwater tunnel should address any detrimental effects associated with this interaction. In this paper an attempt to identify the coupled structural and hydraulic interaction between the lining and the ground was made using a numerical method. A main concern was given to local hindrance of flow into tunnels. Six cases of local deterioration of a drainage system were considered to investigate the effects of deterioration on tunnels. It is revealed that hindrance of flow increased pore-water pressure on the deteriorated areas, and caused detrimental effects on the lining structures. The analysis results were compared with those from fully permeable and impermeable linings.

• The Journal of Industrial Distribution & Business
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• v.4 no.2
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• pp.41-49
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• 2013

Purpose - Currently, the distribution environment has been changing rapidly because of the advent of super-supermarkets (SSM),which adopt the "price break" and "lowest price" strategies. Specifically, a diversification of the distribution environment allowed customers to reasonably decide where to shop. With a broadened range of criteria governing the choice of a store, determining changes in the distribution environment should be based on customer satisfaction surrounding the service levels of SSMs. This study examines the effects of service quality and product quality of SSMs on customer satisfaction levels, and analyzes whether these factors affect customers' revisit intention directly. Research design and methodology - A survey method was used and 127 SSM customers responded to the questionnaires that were developed to measure service quality, product quality, customer satisfaction, and store revisit intention. A multi-regression analysis was used to test the hypotheses. Results - Except hypothesis 2, the other seven hypotheses were supported. Hypothesis 2 suggested a positive relationship between product factors and customer satisfaction. Conclusions - This study found a systematic effect of service factors and product factors on customer satisfaction and word-of-mouth, and consequently on store revisit intention.

• Structural Engineering and Mechanics
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• v.66 no.6
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• pp.729-736
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• 2018

This paper studies thermal buckling and post-buckling behaviors of functionally graded materials (FGM) tubes subjected to a uniform temperature rise and resting on elastic foundations via a refined beam model. Compared to the Timoshenko beam theory, the number of unknowns of this model are the same and no correction factors are required. The material properties of the FGM tube vary continuously in the radial direction according to a power function. Two ends of the tube are assumed to be simply supported and in-plane boundary conditions are immovable. Energy variation principle is employed to establish the governing equations. A two-step perturbation method is adopted to determine the critical thermal buckling loads and post-buckling paths of the tubes with arbitrary radial non-homogeneity. Through detailed parametric studies, it can be found that the tube has much higher buckling temperature and post-buckling strength when it is supported by an elastic foundation.

• Korean Institute of Interior Design Journal
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• v.20 no.4
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• pp.11-20
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• 2011

Jeju Special Self-Governing Province are trying every effort to be presented as an International Free City with unique combination of history, culture and landscape, This research focuses on the analysis of characteristics we can find in buildings in Jeju province. The main purpose is to provide basic and informative materials for the landscape formation of Jeju by investigating current status of buildings in Jeju province. This research divides Jeju province into 34 areas and categorizes buildings by use. 2,973 cases in total are collected and analyzed their architectural features. A basic analysis of the collected data is conducted in the first and the second stages. And In the third stage, 505 cases whose addresses can be identified are selected for the in-depth analysis of the registered building data on architecture year, building area, and total area. These data are analyzed by the categories of region, year, and size for the study of general characteristics of buildings in Jeju. The results show that territoriality is weak because of the simplicity of building layout on the streets. Exterior form of buildings, streetscape image, and overall city image are tedious and boring because of the lack of the variety of facade and exterior finishing materials.

• Journal of Navigation and Port Research
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• v.34 no.2
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• pp.145-152
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• 2010

The management of safety at sea is based on a set of internationally accepted regulations and codes, governing or guiding the design and operation of ships. The regulations most directly concerned with human safety and protection of the environment are, in general, agreed internationally through the International Maritime Organization(IMO). IMO has continuously dealt with safety problems and, recognized that the human element is a key factor in both safety and pollution prevention issues(IMO, 2010). This paper proposes a human error analysis methodology which is based on the human error taxonomy and theories (SHELL model, GEMS model and etc.) that were discussed in the IMO guidelines for the investigation of human factors in marine casualties and incidents. In this paper, a cognitive process model, a human error analysis technique and a marine accident causal chains focused on human factors are discussed, and towing vessel collision accidents are analyzed as a case study in order to examine the applicability of the human error analysis technique to marine accidents. Also human errors related to those towing vessel collision accidents and their underlying factors are discussed in detail.

• Korean Institute of Interior Design Journal
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• v.22 no.6
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• pp.190-198
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• 2013

With globalization and the execution of a self-governing system, the government-oriented system has been transformed into a city-oriented system. The importance of the competitive power of a city is thus increasing. Because of this each region is trying to develop its own differentiated image and to create branding using unique historical and cultural resources and, as one of the strategies for this, public spaces have been developed. For a public space to be used as a means to promote the attractiveness of a city, creates a local image and works as a medium to help a community of people realize a pleasant life. Therefore, in this study, I am clarified theoretically the meaning of placeness and form factors. and study realization methods in the space around the public space case. The results of the study are as following. In the modern space, Place is to be understood as a recognition and experience. Therefore rather than spatial structure physical fixed, recognition through the human experience is an important feature of the place-making, it is necessary to access in spatial planning based on this point of view. The factors of the placeness formation are physical environment factors, activity elements of the human, the meaning factors. and these elements form the placeness through via interaction. Therefore, even space implementation of the place, it is necessary to grasp the elements of each, as well as the physical aspects in particular, planning programmatic and various functions must be parallel strategically. There is a need to implement a space device that can be carried out in space activities.