• Geomechanics and Engineering
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• v.17 no.1
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• pp.19-30
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• 2019

Recent research on the behavior of silty sand tends to advocate the use of equivalent skeleton void ratio to characterize the density state of this type of soil. This paper presents an investigation to explore the physical meaning of the equivalent skeleton void ratio by means of DEM simulations for assemblies of coarse and fine particles under biaxial shear. The simulations reveal that the distribution pattern of fine particles in the soil skeleton plays a crucial role in the overall macroscopic response: The contractive response observed at the macro scale is mainly caused by the movement of fine particles out of the force chains whereas the dilative response is mainly associated with the migration of fine particles into the force chains. In an assembly of coarse and fine particles, neither all of the fine particles nor all of the coarse ones participate in the force chains to carry the external loads, and therefore a more reasonable definition for equivalent skeleton void ratio is put forward in which a new parameter d is introduced to take into account the fraction of coarse particles absent from the force chains.

• Journal of the Korean Society for Geothermal and Hydrothermal Energy
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• v.17 no.2
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• pp.1-10
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• 2021

Lithium-ion batteries with high energy density, long cycle life and other advantages, have been widely used to energy storage systems(ESS). But as ESS fires frequently occur, the safety concern has become the main obstacle that hinders the large-scale applications of lithium-ion batteries. Especially, thermal runaway is the key scientific problem in battery safety research. Therefore, in this study, we performed a numerical analysis on the thermal runaway phenomenon of NCM111, NCM523 and NCM622 batteries using a two-dimensional analysis model. The results show that the two-dimensional simulation results are generally matched with three-dimensional simulation. Also, In the case of NCM111 with a low Ni content in the temperature range used in this study, thermal runaway phenomenon does occurred very slowly, but as the Ni content is increased, the thermal runaway phenomenon occurs rapidly and the thermal stability tends to be decreased. And, in NCM523 and NCM622 batteries, chain reactions occur almost simultaneously, but in the case of NCM111 battery, it is found that after the SEI(Solid Electrolyte Interface) layer decomposition reaction, the cathode-electrolyte reaction is appeared sequentially. After that, the anodic decomposition reaction is increased and leads to the thermal runaway reaction.

• Korea Trade Review
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• v.44 no.3
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• pp.253-269
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• 2019

This study examines the utilization effect of FTA on the sales and profit of the secondary auto-part suppliers in two aspects: 1) firm-level survey on the utilization of FTA and 2) statistical inference on the FTA effects on their sales and profit. We use the GLS statistical technique, panel and survey data of 130 secondary auto-part suppliers in the Daegu and Kyungpook area in 2007-2016. The evidence shows that the secondary auto-part suppliers struggle to prepare documents for the FTA certificates of origin due to their small firm size, although they utilize the FTA at the relatively high rate of 92 percent. Statistical evidence shows that an increase in the export of the first vender significantly affects the sale of the secondary auto-part vendors, but not their profit. The low profit and high managing cost of utilizing the FTA deteriorate the utilization effect of the FTA of the secondary auto-part vendors, which is a key factor in a global supply chain and for the competitiveness of the automobile industry. Government policies are required for the secondary auto-part suppliers to utilize the FTA more effectively and share the benefits of tariff reduction with first auto-part vendors under FTA transaction.

• Journal of Distribution Science
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• v.20 no.8
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• pp.9-20
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• 2022

Purpose: Distribution competence plays a key role in supply chain management. A successful distribution system will bring high values and profit for company. Omni-channel is a modern type of distribution which is used by many companies to access customers more effectively. This research is about the influence of distribution competence on customer value creation, competitive advantage and business performance of retailers in omni-channel. Research design, data and methodology: Questionnaires were issued to 200 managers who have experiences in using an Omni-channel to provide consumer goods. PLS-SEM is used to check the relationship among these above factors in omni-channel in Vietnam context. Results: Distribution competence has positive direct effect on business performance. At the same time, it has positive indirect effect on business performance through the mediating role of customer value creation and competitive advantage. Moreover, the role of mediating variables make contribution to strengthen the relationship of distribution competence and business performance in omni-channel. Conclusions: Through distribution competence, retailers can get competitive advantage, create more values for customers and increase business performance in omni channel in Vietnam.

• Steel and Composite Structures
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• v.42 no.2
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• pp.161-172
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• 2022

In this paper, four specimens of CFST column joints with endplates and long bolts are tested in the scenario of progressive collapse. Flush endplate and extended endplate are both adopted in this study. The experimental results show that increasing the thickness of the endplate could improve the behavior of the joint, but delay the mobilization of catenary action. The thickness of the endplate should not be relatively thick in comparison to the diameter of the bolts, otherwise catenary action would not be mobilized or work effectively. Effective bending deformation of the endplate could help the formation and development of catenary action in the joints. The performance of flexural action in the joint would affect the formation of catenary action in the joint. Extra middle-row bolts set at the endplates and structural components set below the bottom beam flange should be used to enhance the robustness of joints. A special weld access hole between beam and endplate should be adopted to mitigate the chain damage potential of welds. It is suggested that the structural components of joints should be independent of each other to enhance the robustness of joints. Based on the component method, a formula calculating the stiffness coefficient of preloaded long bolts was proposed whose results matched well with the experimental results.

• Journal of the Korean Wood Science and Technology
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• v.49 no.3
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• pp.254-266
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• 2021

Using forest resources involves solving complex and diverse tasks. At the same time, one of the key goals in the field is improving the quality of forest infrastructure. This direction requires adequate mathematical and economic justification. Moreover, creating an effective infrastructure will not only increase the accessibility and usage volumes of wood and other forest resources, but also contribute to the development of continuous and sustainable forest management. The existing practice of making decisions in terms of the organizational and technological aspects of logging, based on the personal experiences of managers or leading specialists in enterprises, hinders the achievement of constant optimal efficiency. The paper presents results that are a continuation of the research cycle of the authors' team in the fields of optimization and algorithmization of various logging processes. The focus of the study lies in the processing and movement of wood resources, the most valuable products of the investigated groups of enterprises. To this end, the paper presents a developed algorithm for determining an effective technological chain of transportation in logging operations, and for improving loading and unloading processing operations under dynamic natural and production conditions. This algorithm serves as the methodological basis for designing logging infrastructure in a dynamically changing environment.

• Journal of Distribution Science
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• v.21 no.2
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• pp.35-43
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• 2023

Purpose: As Thailand seeks to become a regional startup hub, Thai startups have been acquiring growth and scalability in the last ten years. Hence, this paper examines influential factors in Thailand's growth of logistics tech startups. The conceptual framework incorporates sensing user needs, sensing technological options, conceptualizing, scaling, and stretching, co-producing, and orchestrating, business strategy, strategic flexibility, and startup growth. Research design, data, and methodology: The quantitative method was applied to distribute the questionnaire to 500 managers and above in logistics tech startups in Thailand. The sampling techniques involve judgmental, convenience, and snowball samplings. Before the data collection, The Item Objective Congruence (IOC) Index and pilot test (n=45) were employed for content validity and reliability. The data were mainly analyzed by Confirmatory Factor Analysis (CFA) and Structural Equation Model (SEM). Results: The findings revealed that sensing technological options, scaling, and stretching, co-producing, and orchestrating, and business strategy significantly influence the growth of startups in Thailand. Nevertheless, sensing user needs, conceptualizing, and strategic flexibility have no significant relationship with startup growth. Conclusions: For Thailand to accelerate its digital economy driven by tech startups, firms must emphasize influential factors to accelerate growth by providing the right tech solutions for people's lives.

• Asian Journal of Innovation and Policy
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• v.12 no.1
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• pp.75-100
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• 2023

Over the past few decades, globalization has been shifting economic power upward to transnational actors on the one hand, and downward to subnational or regional spaces on the other. This phenomenon has resulted in the centrality of territorially delimited subnational regions acting as critical loci of economic governance within a complex and globally distributed value chain of trade and service flows. Within this broader context of industrial restructuring are economic regions that span national borders in their collective assets. The paper focuses on investigating the economic competitiveness and productivity of cross-border (or binational) economic regions. Using the conceptual framework of economic clusters, an econometric model that measures proxies of geographic proximity of firms in the life sciences cluster, and a new binational economic model, the paper examines the key characteristics, potentials and constraints of economic competitiveness and productivity in a cross-border region comprising counties in Western New York and regional municipalities in Southern Ontario. The findings demonstrate the direct and indirect benefits of closer cross-border economic cooperation. The paper then concludes with some policy observations about leveraging cross-border economic clusters for strategic industrial cooperation.

• Proceedings of the Korea Information Processing Society Conference
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• 2010.04a
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• pp.649-652
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• 2010

무선 센서 네트워크에서 클러스터링 기법은 데이터 병합을 통해 통신 대역폭 사용을 용이하게 하며, 센서 노드들간의 송수신 전력 소비를 줄일 수 있고, 노드 증가에 따른 네트워크 확장성이 용이하므로 현재 많은 연구가 되고 있다. 클러스터링 기법은 클러스터 헤더를 선출하는 것으로부터 시작된다. 기존의 클러스터 헤더 선출 기법들은 에너지 잔여량, 센서 노드의 위치, 센서 노드들의 평균 에너지 등을 클러스터 헤더 선출값으로 하여 클러스터 헤더를 선정한다. 그러나 이 기법들은 악의 적인 노드가 다른 노드의 클러스터 헤더 선출값을 변경하고, 자신의 클러스터 헤더 선출값을 증가시켜 클러스터 헤더가 될 수 있는 보안 취약점을 가지고 있다. 이와 같은 보안 취약점을 개선하기 위해 클러스터 헤더 선출값에 대한 무결성과 클러스터 헤더 선출값을 전송하는 노드의 인증이 필요하다. 본 논문에서는 one-way key chain 기법을 사용하는 안전한 클러스터 헤더 선출 기법을 제안하고, 제안한 기법에 대한 안전성을 분석한다.

• International Journal of Computer Science & Network Security
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• v.23 no.8
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• pp.137-145
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• 2023

E-Commerce is a buzzword well known for electronic commerce activities including but not limited to the online shopping, digital payment transactions, and B2B online trading. In today's digital age, e-commerce has been playing a very important and vital role in areas such as retail shopping, sales automation, supply chain management, marketing and advertisement, and payment services. With a huge amount of data been collected from various e-commerce services available, there are multiple opportunities to use that data to analyze graphs and trends. Strategize profitable activities, and forecast future trade. This paper explains a contemporary approach for collecting key data metrics and implementing cost-effective automation that will support in improving conversion rates and sales performance of the e-commerce websites resulting in increased profitability.