Extended Airtime Fair Scheduling Method for a Zigbee Network

Van-Tu Chau,T.T. Quyen Bui,Anh-Tuan Do,Quang-Vinh Thai 제어로봇시스템학회 2014 제어로봇시스템학회 국제학술대회 논문집 Vol.2014 No.10

In a Zigbee network, when many nodes simultaneously send data packets to a Zigbee coordinator through routes (branches), the Zigbee coordinator cannot deal with all signals. Interference and noises are existed during data transmission. This problem is still one of challenges in the network communication. In this paper, we propose an extended airtime fair algorithm in which throughput of a Zigbee network is maximized and fractions of airtime are taken into account. We adapt a utility function that is proposed by Kelly (1997) in maximizing the network throughput; nevertheless, throughput of each branch is multiplied by a fraction of airtime. Fractions of airtime play a role in creating a balance of throughputs of branches: the throughput and fairness of each branch is guaranteed. Moreover, the usefulness of our proposed algorithm for a Zigbee network is presented; simulation results show that the throughput and fairness are better than those of a case of not using airtime fair.

An Analysis of Port Service Quality and Customer Satisfaction: The Case of Korean Container Ports

여기태,Vinh Van THAI,Sae Yeon Roh 한국해운물류학회 2015 The Asian journal of shipping and Logistics Vol.31 No.4

Ports play a critical role in the economy of many countries and regions. Failure or unreliability of port services can significantly influence port customers—shipping lines and cargo owners—and result in their dissatisfaction. However, what constitutes port service quality (PSQ) and its influence on the satisfaction of port customers has not been well investigated in the literature. Therefore, this study investigates the concept of PSQ and its influence on customer satisfaction in the case of Korean container ports. Following a literature review, a conceptual model of PSQ and its influence on customer satisfaction is proposed. The model was validated through a survey of 313 members of the Korean Port Logistics Association (KPLA). Partial least squares structural equation modeling (PLS-SEM) was conducted to confirm the PSQ dimensions and to examine their relationship with customer satisfaction using SmartPLS 3.2.1 software. PSQ is found to be a five-factor construct, and its management, and image and social responsibility factors have significant positive effects on customer satisfaction. In addition to its academic contribution, this study also contributes to management practices because port managers can use the PSQ scale to measure their customers’ satisfaction and justify investments in the quality management of port services.

Towards Sustainable ASEAN Port Development: Challenges and Opportunities for Vietnamese Ports

Saeyeon ROH,Vinh Van THAI,Yiik Diew WONG 한국해운물류학회 2016 The Asian journal of shipping and Logistics Vol.32 No.2

Sustainability agendas are challenging port authorities around the world to find ways of operating and managing their ports efficiently and effectively in terms of economic, social, as well as environmental development. In this respect, governments in ASEAN countries have been implementing various green activities seeking to reduce the environmental impact of shipping and related activities. In this connection, most studies in the existing literature mainly focus on the environmental aspects of sustainable development and have not clearly explained what sustainable port development exactly entails. Furthermore, most of these studies emphasized on the impact of port development and overlooked what factors influence sustainable port development. To address these gaps, this research aim to explore the main factors shaping sustainable port development. This was conducted through a comprehensive review of related literature as well as confirmatory in-depth interviews with port authorities. As a result, findings from this research would help identify key elements of sustainable port development from port authorities’ perspective. The challenges, opportunities and managerial implications for Vietnamese ports are also discussed accordingly.

Fuzzy MCDM approach for evaluating intangible resources affecting port service quality

Ji Yeong Pak,여기태,Vinh Van THAI 한국해운물류학회 2015 The Asian journal of shipping and Logistics Vol.31 No.4

Intangible resources consist of soft resources such as knowledge, information and capabilities. It is important for ports to enhance intangible as well as tangible resources to obtain sustainable competitive advantage. In this connection, this study aims to identify port intangible resources which may contribute to the delivery of port service quality and to propose a fuzzy TOPSIS approach to solve the port choice problem focusing on intangible resources. Fuzzy TOPSIS is appropriate to assist decision making with ambiguous and uncertain problems such as port choice with respect to intangible resources. In this paper, five port intangible resources were identified and evaluated and five leading container ports in the Asia-Pacific region were assessed in terms of their intangible resources. A survey questionnaire was sent to 21 experts who are working in shipping companies in Korea and involved in the selection of ports. It was found that customer and relational resource contributes most to the delivery of port service quality while Hong Kong appeared to be the port where intangible resources were most highly evaluated. This research helps to enrich the literature on port service quality and port choice evaluation. Its findings can also be used as guidelines for port managers to prioritise resources that may have greater influence on the delivery of port service quality and the subsequent training and education programs.

Cost Consequences of a Port-Related Supply Chain Disruption

Hui Shan LOH,Vinh Van THAI 한국해운물류학회 2015 The Asian journal of shipping and Logistics Vol.31 No.3

Port functionality is a significant and important aspect of cargo transportation. Previous studies have identified a list of port-related supply chain disruption threats and developed a management model that seeks to address these threats. This paper adds value to these related studies by comparing four consequences of an example of these threats: (1) avoidance of disruption, (2) mitigation of disruption, (3) deviation of transportation plan and (4) delays and deviation of transportation plan. The impact of these consequences is simulated in a case study using data from a chemical manufacturer based in Singapore. This paper quantitatively measures the impact of a port-related threat on supply chains and thus highlights the importance of port-related supply chain disruption management.

Are Customers Willing to Pay for Corporate Social Responsibility? A Study of Individual-Specific Mediators

( Kum Fai Yuen ),( Van Vinh Thai ) 한국품질경영학회 2015 한국품질경영학회 학술대회 Vol.2015 No.2

Purpose - This study identifies, specifies, and examines the variables that mediate the link between firms □ involvement in corporate social responsibility (CSR) and customers □ willingness to pay premium prices for CSR (WTP for CSR). Methodology - Theoretical and alternative models were first proposed from reviewing the literature. Subsequently, a survey was administered to 212 users of shipping logistics services in Singapore. Based on the obtained data, the proposed models were analysed and compared using structural equation modelling. Findings - The link between CSR and WTP for CSR was found to be indirect and mediated by personal factors including customer satisfaction, CSR belief, and customer loyalty. It was also found that practising CSR in conjunction with service quality result in greater customer satisfaction, which subsequently elicits positive behavioural intentions and responses. Implications - In general, CSR can be employed as a strategy to satisfy customers□ psychosocial needs. However, customer satisfaction is a necessary but insufficient condition for customers to be willing to pay for CSR. Instead, CSR beliefs and customer loyalty, which are to a small extent influenced by customer satisfaction, are the true determinants of WTP for CSR. Originality -This is one of the few papers that focus on examining the mediating processes between CSR and WTP for CSR. A robust method using model comparison was adopted to rigorously test the hypotheses of this study.

Managing Port-Related Supply Chain Disruptions: A Conceptual Paper

Hui Shan LOH,Vinh Van THAI 한국해운물류학회 2014 The Asian journal of shipping and Logistics Vol.30 No.1

The increased importance of ports makes them a vulnerable node as a port-related disruption can generate domino effect on a network of supply chains. The vulnerability of ports thus needs to be addressed to ensure the functionality of ports and enhance supply chain resilience. This paper synthesizes the current literature into a management model that seeks to target operational deficiencies at ports. The management model is operationalized in three tiers, from the top management level to the front-line employees, with characteristics from risk management, business continuity management and quality management theories. The proposed model serves as a universal guide in assisting port management in managing port-related disruptions and seeks to reduce the occurrences of port-related supply chain disruption threats.

A Benchmarking of Operational Efficiency in Asia Pacific International Cargo Airports

정태원,안우철,Su-min JEON,Vinh Van THAI 한국해운물류학회 2015 The Asian journal of shipping and Logistics Vol.31 No.1

This paper compares operational efficiency of major cargo airports in the Asia Pacific region. The multi-dimensional scaling cluster analysis by R-square method was used as the benchmarking tool to provide airport management with a means to examine various aspects of their operational efficiency against those of other airports. Ten operational efficiency factors for the clustering and efficiency estimation of airports in the Asia Pacific region were used in a regression model to overcome the complexity of multi-dimensional scaling approach. The resulting classification is used to identify the efficiency benchmarks of leading air cargo airports which have implications for Incheon airport in Korea.

Impacts of Global Manufacturing Trends on Port Development: The Case of Hong Kong

Abraham ZHANG,Hui Shan LOH,Vinh Van THAI 한국해운물류학회 2015 The Asian journal of shipping and Logistics Vol.31 No.1

Global manufacturing trends may have profound implications for regional port development. This paper studies Hong Kong port (HKP), which has been one of the world’s busiest container ports since the 1990s. In recent years, global manufacturers have started to move away from its primary cargo base, the Chinese Pearl River Delta. This study investigates impacts of the emerging global manufacturing trends on HKP development. It is found that relocation of manufacturing to Western Guangdong benefits HKP, while other relocation destinations make HKP less attractive or even irrelevant. Based on the findings, government policies are discussed that may be formulated to support the growth of the port and wider port-related economy.