• Journal of the Korean Wood Science and Technology
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• v.50 no.2
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• pp.93-103
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• 2022

Currently, biofibers are used as a reinforcement in polymer composites for structural elements and construction materials instead of the synthetic fibers which cause environmental problems and are expensive. One of the chemicals with a pH close to neutral that can be potentially used as a modified fiber material is sodium chloride (NaCl). Therefore, this study aims to investigate the characteristics of a composite board made from NaCl-treated kenaf fiber. A completely randomized design method was used with consideration of two factors: the content of NaCl in the treatment solution (1 wt%, 3 wt%, and 5 wt%) and the duration of immersion of fibers in the solution (1 h, 2 h, and 3 h). The NaCl treatment was conducted by soaking the fibers in the solution for different durations. The fibers were then rinsed with water until the pH of the water reached 7 and subsequently dried inside an oven at 80℃ for 6 h. Kenaf fiber and epoxy were mixed manually with the total loading of 20 wt% based on the dry weight of the fiber. Physical and mechanical properties of the fibers were then evaluated based on JIS A 5908 particleboard standards. The results showed that increasing NaCl content in the fiber treatment solution can increase the physical and mechanical properties of the composite board. The properties of fibers treated with 5 wt% NaCl for 3 h were superior with a modulus of elasticity of 2.085 GPa, modulus of rupture of 19.77 MPa, internal bonding of 1.8 MPa, thickness swelling of 3%, and water absorption of 10.9%. The contact angle of untreated kenaf fibers was 104°, which increased to 80° and 73° on treatment with 1 wt% and 5 wt% NaCl for 3 h, respectively.

• Computers and Concrete
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• v.14 no.2
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• pp.145-161
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• 2014

The article presents the statistical method of grouping the results of the compressive strength of concrete in continuous production. It describes the method of dividing the series of compressive strength results into batches of statistically stable strength parameters at specific time intervals, based on the standardized concept of "concrete family". The article presents the examples of calculations made for two series of concrete strength results, from which sets of decreased strength parameters were separated. When assessing the quality of concrete elements and concrete road surfaces, the principal issue is the control of the compressive strength parameters of concrete. Large quantities of concrete mix manufactured in a continuous way should be subject to continuous control. Standardized approach to assessing the concrete strength proves to be insufficient because it does not allow for the detection of subsets of the decreased strength results, which in turn makes it impossible to make adjustments to the concrete manufacturing process and to identify particular product or area on site with decreased concrete strength. In this article two independent methods of grouping the test results of concrete with statistically stable strength parameters were proposed, involving verification of statistical hypothesis based on statistical tests: Student's t-test and Mann - Whitney - U test.

• Structural Engineering and Mechanics
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• v.18 no.5
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• pp.591-607
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• 2004

The substance of the use of the derived non-linear creep constitutive equations under variable stress levels (see first part of the paper, Kmet 2004) is explained and the strategy of their application is outlined using the results of one-step creep tests of the steel spiral strand rope as an example. In order to investigate the creep strain increments of cables an experimental set-up was originally designed and a series of tests were carried out. Attention is turned to the individual main steps in the production and application procedure, i.e., to the one-step creep tests, definition of loading history, determination of the kernel functions, selection and definition of constitutive equation and to the comparison of the resulting values considering the product and the additive forms of the approximation of the kernel functions. To this purpose, the parametrical study is performed and the results are presented. The constitutive equations of non-linear creep of cable under variable stress history offer a strong tool for the real simulation of stochastic variable load history and prediction of realistic time-dependent response (current deflection and stress configuration) of structures with cable elements. By means of suitable stress combination and its gradual repeating various loads and times effects can be modelled.

• Journal of the Korea Safety Management & Science
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• v.14 no.2
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• pp.49-54
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• 2012

As all kind of industry has developed, metal structure and machine instrument use bolt, pin, rivet and welding for assembly and combination. For pin and hinge, dimension accuracy is crucial to keep the operation and safety of the structure and machine instrument. In case of complex machine, the hinge for cover open-loop system is one of the significant design elements. Most of the hinges are being imported and assembled sine they give high technology development cost for its unit cost position. The reason is that the localization of hinge is inadequate. As the demand increase and the necessity of localization grow, it is now more important than ever to develop low cost structure. By the low cost structure, a new technology could be obtained for electronic product and structural hinge since it would enable for complex machine hinge to be guaranteed, technologically. Open-loop hinge is the link type and designed for the structure to keep constant open-loop. And, the hinge is examined in design stability by finite element analysis method. In this paper, the operation result is presented when the hinge for complex machine open-loop is designed for link type structure.

• Proceedings of the Earthquake Engineering Society of Korea Conference
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• 2005.03a
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• pp.308-315
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• 2005

The capacity protection is normally related with slenderness effect of the columns, force transfer in connections between columns and adjacent elements, and shear design of columns. It is intends to prevent brittle failure of the structural components of bridges, so that the whole bridge system may show ductile behavior and failure during earthquake events. For bridge systems, this means it is necessary to assess the overstrength capacity of columns prior to proceeding with the design of foundation and superstructure. The objective of this paper is to develop a capacity design approach that applies an overstrength factor for determination of possible maximum shear force in the plastic hinge zone of reinforced concrete bridge columns. In order to estimate and determine overstrength factor, material strength was developed to investigate for actual material strength total 3,407 steel and 5,405 concrete by domestic product. Based on actual material strength, this paper was conducted on moment overstrength factors using moment-curvature analysis program. And also design recommendations for capacity design are presented to revise the annual report, KEERC 2002.

• Proceeding of EDISON Challenge
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• 2015.03a
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• pp.467-475
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• 2015

In this paper, the FREECAD 0.14 was used for modeling conventional Selfie-stick and the newly proposed Selfie-stick design. The purpose of this paper is to demonstrate the utility of FREECAD 0.14, which is open-source and still in development for further use. After modeling the conventional Selfie-stick, CatiyaV5 was used to assemble FREECAD 0.14 drawn elements. Main advance in newly designed Selfie-stick is the portability. To improve portability of the Selfie-stick, folding mechanism was adopted from folding LED stands. Several mechanisms were adopted to improve user convenience as well. Ansys 14.0 was used for structural analyses of conventional Selfie-stick model and the newly designed model as well. Several simplifications for the models were needed to process the analyses. When analyzing the newly designed model various materials were used one by one to find compatible composition. Using Aluminum alloys for the stick and the hand grip was found to be compatible. FREECAD was useful for suggestion of the newly designed model but not so much useful to design an actual product. Various efforts would make FREECAD the best choice for industrial use for free as it is named.

• CDE review
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• v.21 no.2
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• pp.61-64
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• 2015

In this paper, the FREECAD 0.14 was used for modeling conventional Selfie-stick and the newly proposed Selfie-stick design. The purpose of this paper is to demonstrate the utility of FREECAD 0.14, which is open-source and still in development for further use. After modeling the conventional Selfie-stick, CatiyaV5 was used to assemble FREECAD 0.14 drawn elements. Main issue in newly designed Selfie-stick is the portability. To improve portability of the Selfie-stick, folding mechanism was adopted from folding LED stands. Several mechanisms were adopted to improve user convenience as well. Ansys 14.0 was used for structural analyses of conventional Selfie-stick model and the newly designed model as well. Several simplifications for the models were needed to process the analyses. When analyzing the newly designed model various materials were used one by one to find compatible composition. Using Magnesium Alloy for the stick and the hand grip was found to be compatible. FREECAD was useful for suggestion of the newly designed model but not so much useful to design an actual product. Various efforts would make FreeCAD the best choice for industrial use for free as it is named.

• Journal of the Institute of Electronics Engineers of Korea SC
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• v.41 no.6
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• pp.27-35
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• 2004

Finite or Galois fields have been used in numerous applications such as error correcting codes, digital signal processing and cryptography. These applications often require exponetiation on GF(2$^{m}$ ) which is a very computationally intensive operation. Most of the existing methods implemented the exponetiation by iterative methods using repeated multiplications, which leads to much computational load, or needed much hardware cost because of their structural complexity in implementing. In this paper, we present an effective VLSI architecture for exponentiation on GF(2$^{m}$ ). This circuit computes the exponentiation by multiplying product terms, each of which corresponds to an exponent bit. Until now use of this type algorithm has been confined to a primitive element but we generalize it to any elements in GF(2$^{m}$ ).

• Journal of Distribution Science
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• v.19 no.5
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• pp.23-34
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• 2021

Purpose: This study identifies the critical elements of relationship management required to be studied in distribution sciences to create a relational bond of watch manufacturers with their retailers in India. The offline watch retail market is undergoing a rapid transformation due to technology intervention in the product portfolio and the advent of online retailing. The study identifies the interrelationships amongst the constructs of interdependence, trust, affective commitment, and information exchange to form long-lasting relational bonds in the watch industry. Research design, data and methodology: We used a path analysis to investigate the relationship between interdependence, trust, affective commitment, and information exchange. Data has been collected from 143 watch retailers using judgmental sampling method. Results: The data analysis suggested the establishment of measurement and structural model. The absolute and relative goodness of fit models in the causal analysis are 0.628 and 0.959 suggesting a sufficient fit index. Based on the analysis of direct and indirect effects, the results indicate that trust fully mediates the effect of interdependence and information exchange of retailers with the manufacturer. Conclusions: Trust plays an important role in driving commitment and information exchange between watch manufacturers and retailers. Interdependence in the manufacturer-channel relationships would lead to affective commitment only when trust exists in the relationship. [AMAWATE, Vibhas.] in Web of Science and Scopus).

• The Journal of Economics, Marketing and Management
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• v.11 no.1
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• pp.1-12
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• 2023

Purpose: This study identified the effects of the three types of consumer interactions on the utilitarian and hedonic values experienced by community members, their degree of participation, and brand loyalty. In addition, the mediating effect of virtual interactivity between the interactions that occur within the online brand community and the value experienced by community members was also identified. Research design, data and methodology: An online survey was distributed, and the data gathered was analyzed using structural equations modeling. Results: Test results showed that product-information interaction has a positive effect on utilitarian value and interpersonal interaction has a positive effect on hedonic value. Human-computer interaction was found to have a negative effect on hedonic value and no significant effect on utilitarian value. Furthermore, it was revealed that among the three types of interactions, virtual interactivity had a mediating effect only in the relationship between human-computer interaction and hedonic value. Moreover, utilitarian values experienced by community members affected their level of participation which ultimately enhances brand loyalty. Hedonic value did not affect their level of participation within the online brand community. Conclusions: When marketers establish online brand community strategies, they must place elements that can directly help the use of brands and products.