Visual cryptography, first introduced by Naor and Shamir, allows a secret (black and white) image to be encoded and distributed to a set of participants such that certain predefined sets of participants may reconstruct the image without any computation. In 2000, Blundo, De Santis, and Naor introduced a model for grey-level visual cryptography which is a generalization of visual cryptography for general access structures. Grey-level visual cryptography extends this model to include grey-scale images. Decoding is done by the human visual system. In this thesis we survey known results of grey-level visual cryptography and visual cryptography for general access structures. We extend several visual cryptography constructions to grey-level visual cryptography, and derive new results on the minimum possible pixel expansion for all possible access structures on at most four participants.

Since the business environment of today is characterized to be dynamic and service-driven, corporations are looking for solutions how to cut costs and still keep their competitive advantage in the market, and also how to decrease lead-time and flexibility. In this environment are 3PL-providers operating with an incentive to always please the customer. This study will investigate a 3PL-provider´s information sharing with its customer and how value can be extracted from this type of sharing. The purpose of this thesis is to understand and investigate the value of information sharing between the 3PL-provider and its customer. Two research questions have been dictated; R1: How do the respondents at the 3PL-provider perceive the relationship with their customer? R2: How are information requirements met? For the frame of reference have theories in the area of third-party logistics, information, relation, and value been studied. The carrying out of the study has been performed with a bounded ethnography approach since this study has essences from both the scientific and ethnographic approaches. The research reasoning is mainly inductive but with deductive elements. The research strategy is of qualitative character, where the data collection has been carried out through interviews/discussions within multiple case studies. There were several interviews launched within the target 3PL-relationships. The analysis of the empirical findings has been done through the existing theories in the frame of reference. The investigation showed that improvements of the information requirements and utilization of the communication methods improves the quality of the information sharing, and the conclusion drawn is that the information requirements and communication methods are big contributors for the information sharing as a whole. Since the information sharing is considered a big contributor to the customer value one can use the customer value as reference for how to value the information sharing. A main conclusion is therefore that the value of information sharing is dependent on its contribution for the customer value.

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Recently there has been an increasing demand for efficient mechanisms of carrying out computations that exhibit coarse grained parallelism. Examples of this class of problems include simulations involving Monte Carlo methods, computations where numerous, similar but independent, tasks are performed to solve a large problem or any solution which relies on ensemble averages where a simulation is run under a variety of initial conditions which are then combined to form the result. With the ever increasing complexity of such applications, large amounts of computational power are required over a long period of time. Economic constraints entail deploying specialized hardware to satisfy this ever increasing computing power. We address this issue in Dispatch, a peer-to-peer framework for sharing computational power. In contrast to grid computing and other institution-based CPU sharing systems, Dispatch targets an open environment, one that is accessible to all the users and does not require any sort of membership or accounts, i.e. any machine connected to the Internet can be the part of framework. Dispatch allows dynamic and decentralized organization of these computational resources. It empowers users to utilize heterogeneous computational resources spread across geographic and administrative boundaries to run their tasks in parallel. As a first step, we address a number of challenging issues involved in designing such distributed systems. Some of these issues are forming a decentralized and scalable network of computational resources, finding sufficient number of idle CPUs in the network for participants, allocating simulation tasks in an optimal manner so as to reduce the computation time, allowing new participants to join the system and run their task irrespective of their geographical location and facilitating users to interact with their tasks (pausing, resuming, stopping) in real time and implementing security features for preventing malicious users from compromising the network and remote machines. As a second step, we evaluate the performance of Dispatch on a large-scale network consisting of 10−130 machines. For one particular simulation, we were able to achieve up to 1500 million iterations per second as compared to 10 million iterations per second on one machine. We also test Dispatch over a wide-area network where it is deployed on machines that are geographically apart and belong to different domains.

Abstract People are racing with time in the era of knowledge economics. Those who are faster will be the winners. Those who are with original ideas will catch more chances to meet the customer¡¦s needs. Business speed and originality pop out of the performance of R&D. The performance of R&D depends on its member¡¦s personal knowledge and the knowledge prevailing in the origination. The pile of knowledge quantity and speed bases on how fast knowledge is shared. The factors of knowledge sharing situation are related to the characters of the organization and the sharing culture of its departments. This study will discuss the factors of the knowledge sharing situation. Furthermore, what are the performances of R&D? And what is the relationship between the character of the organization and knowledge sharing situation? And will the character of the organization and the R&D¡¦s knowledge sharing affect the performance of R&D? The conclusions of this study are proposed as followings: 1. Factors of the relationship between the character of the organization and knowledge sharing situation: 2. Factors of the relationship between knowledge sharing situation and the performance of the R&D: 3. The impact of the interaction with the organization character and the knowledge sharing situation on the performance of the R&D. Keywords: knowledge sharing R&D performance

The IT community has increasingly come to view storage as a resource that should be shared among computer systems and managed independently of the computer systems that it serves. And, the explosive growth of the Web contents has led to increasing attention on two major challenges: scalability and high availability of network file system. Therefore, the ways to improve the reliability and availability of system, to achieve the expected reduction in operational expenses and to reduce the operations of system management of system have become essential issues. A basic technique for improving reliability of a file system is to mask the effects of failures through replication. Consistency control protocols are implemented to ensure the consistency among these replicas. In this dissertation, we leveraged the concept of intermediate file handle to cover the heterogeneity of file system. But, the monolithic server system suffered from the poor system utilization due to the lack of dependence checking between writes and management of out-of-ordered requests. Hence, in this dissertation, we followed the concept of intermediate file handle and proposed an efficient data consistency control scheme, which attempts to eliminate unnecessary waits for independent NFS writes to improve the efficiency of file server group. In addition, we also proposed a simple load-sharing mechanism for NFS client to improve system throughput and the utilization of duplicates. Finally, the results of experiments proved the efficiency of the proposed consistency control mechanism and load-sharing policy. Above all, easy to implement is our main design consideration.

The coordination of all supply chain members has become a crucial issue in ensuring the success of supply chain management. The streamline of the inter-organizational coordination such as material flow/distribution, information flow/exchange, and product planning/development are required to facilitate the efficient operation of supply chain. To further sustain the competitive edge (e.g.,time-to-market) of a supply chain, the coordination mechanism has become an emerging research issue in current supply chain management. This study looks into a cause model of the information sharing of supply chain members.The impact of trust and commitment on information sharing mechanism is then examined. The data from 122 senior managers participating in Supply Chain Management activeities were collected and empirically tested. The results show that the trust is significantly impact on the quality of information sharing in e-business supply chain. The member¡¦s long-term commitment also affects the dedicated partner-based process of supply chain management. Moreover, the dedicated partner-based processes will effectively reduce the supply chain uncertainty and high quality information improves significantly the operation efficiency between supply chain enterprises.

This study developed a conceptual model for exploring the correlation between relational dimension of social capital and relation models in hope to reveal to what extent each elements in relational dimension of social capital influences the combination of relation models of knowledge sharing. Further we investigated the impact of each relation model on the effectiveness of knowledge sharing and attempt to present an efficient mechanism based on the combination of the four relation models. We adopted the survey method and focus on the members in IS project team to collect research data. Canonical correlation analysis was employed to examine the correlation between the two constructs, the relational dimension of social capital and the relation models of knowledge sharing, and two significant canonical functions with powerful explanation were derived. The first canonical function with major explanatory power showed that all the elements in the relational dimension of social capital are highly related with the models, CS, EM and MP, in the construct of relation models. The second canonical function, in which obligation is highly related with MP and AR, was derived with inferior explanatory power to the first one. Stepwise regression analysis was conducted to investigate the relationship between each relation model and the effectiveness of knowledge sharing. CS, among the four relation models, was found to have the highest positive significance with the effectiveness, followed by EM and MP sequentially, while AR was found no significant relation with the effectiveness of knowledge in our observations. With the results of this study, we hope to present an efficient mechanism for practitioners to promote knowledge management by enhancing corresponding social capital in relational dimension and offer comprehensive perspectives for researchers to achieve a better insight of the dynamics of knowledge sharing.

Knowledge has been considered as the important resource to the competitive advantage of an organization. Knowledge sharing is critical because intellectual assets, unlike physical assets, increase in value with use. Knowledge and intellect grow exponentially when shared. However, Professionals¡¦ reluctance to exchange knowledge inhibits sharing. Knowledge always could not be allocated well. Therefore, this paper is based on an empirical investigation of knowledge-sharing from information system (IS) professionals. Through a social perspective, it explores the important affecting factors on Knowledge-sharing behavior. The main contribution of this study is to adopt a well-established social theory, i.e., Social Exchange Theory (Blau, 1964¡FThibaut &Kelley, 1959¡FHomans, 1958) to construct a knowledge-sharing research model, which provides some practical and academic suggestions for the future.

Original equipment manufacture(OEM) is typically the role played by the high-tech or traditional industries in Taiwan, and is marked by highly efficient vertical supply chains where division of manufacturing function is done very well. Supply chain management could help companies to integrate their business process and information systems. Moreover, what kind of strategies needed to be adopted, and what kind of information needed to be exchanged transaction. The research issues regarding supply chain strategy and information sharing become apparently important. In the study, supply chain type and supply chain uncertainty are the two major constructs that guide our research. Convergent assembly supply network is type of supply chain selected for case study, and the automotive industry is the actual case for research. The research results indicated that information sharing is most intensive between suppliers and manufacturers. The lack of coordination between production and sale in manufacturer was resulted from supply chain uncertainty which can be addresses by the aspects of procurement, manufacturing, and demand respectively. The current supply chain strategy of manufacturer has push more inventory to its suppliers. This is due to the made-to-stock(MTS) method applied by the manufacturer. In addition, continuous flow process has occupied part of the manufacturing process for automobile production, and high uncertainty resulted from this stage often led to problems for delivery of product parts in the subsequent stages. Furthermore, demand uncertainty and mass customization requirement from the manufacturer have push suppliers to get timely sale information in order to have quick response to orders. Based on the case findings, this research suggested propositions regarding supply chain strategies and information sharing for the convergent assembly supply network. Because of relatively high procurement and demand uncertainty, the MTS production strategy should be switched to assembly-to-order(ATO). In addition, it is necessary for the manufacturer to establish stable relationship with suppliers, and incorporate them into product development process. This will help the manufacturer to achieve ATO and shorten product development time due to the notion of design for assembly and concurrent engineering. For information sharing in supply chains, the focus is upon shop floor information transparency between suppliers and the manufacturer, exchange of sale information between suppliers and distributors, and exchange of information regarding quality, management capability, product development between suppliers and the manufacturer.