An integrated concurrency control in object-oriented database systems.

First, the dissertation discusses three important issues of concurrency control in OODBs. These include conflict among methods, class hierarchy locking, and nested method invocations. The previous works for each issue are presented, and their advantages and disadvantages are also discussed. Then, an integrated concurrency control which addresses all three issues is proposed. For conflict among methods, a finer locking granularity, such as an attribute and an individual class object, is adopted for instance access and class definition access so that higher concurrency is achieved. Especially, for instance access, higher concurrency is obtained using run-time information. Also, locks are required for instance method invocations instead of atomic operation invocations so that locking overhead is reduced. For class hierarchy locking, locking overheads are reduced using special classes which are based on access frequency information on classes. Finally, for nested method invocations, semantic information is used in order to provide higher concurrency among methods. Also, parent/children parallelism is adopted for better performance.Finally, a performance study is conducted by means of simulation using the 007 benchmark. The simulation results show that, in terms of transaction response time and lock waiting time, the proposed scheme performs the best, Malta the second best, and Orion the worst.Object-oriented databases (OODBs) have been adopted for non-standard applications requiring advanced modeling power, in order to handle complex data and relationships among such data. One of the important characteristics in database system is manipulation of shared data. That is, database systems, including OODBs, allow shared data to be accessed by multiple users at the same time. Concurrency control is a mechanism used to coordinate access to the multi-user databases so that the consistency of the database is maintained. In order to provide good performance, it is very important that concurrency control schemes incur low overhead and increase concurrency among users. This dissertation presents a concurrency control scheme in OODBs that meets those requirements.Secondly, an analytical model is constructed to measure the performance of concurrency control in an OODB system. Using this model, the proposed technique is then compared with the two existing techniques, Orion and Malta. The analytical results show that the proposed scheme gives the best transaction response time, Malta the second best, and Orion the worst

A Study on Cause Analysis of Digital Divide among Older People in Korea

Most people in modern society enjoy various benefits due to the development of information and communication technology and smart technology in modern society. However, due to the digital divide, there is a social class that cannot enjoy abundant benefits. The representative class is the class of older people. In the latest four-year national report on the status of the digital divide, the class with largest digital divide among various information disadvantaged groups, such as the disabled, the low-income class, farmers and fishermen, and older people, is the class of older people. In this study, the causes of the digital divide among older people in Korea are analyzed from various perspectives. To this end, various statistical analyses have been conducted based on national statistical survey works over the past four years. The digital informatization level, which is an index used to measure the digital divide, can be classified into three main components: information access, information capability, and information utilization. Among the three components, the information capability is found to be the lowest. Information capability can also be divided into three components for PCs and mobile devices: installation, use, and management. Among them, management capability was found to be the lowest. Based on this analysis, various plans to reduce the digital divide among older people were proposed

A Study on Characteristics Analysis and Countermeasures of Digital Sex Crimes in Korea

In the modern knowledge–information age, various information and communication technologies provide us with many benefits and at the same time, bring various side effects such as cybercrime. The number of cybercrimes is increasing gradually, and in particular, the number of digital sex crimes has been increasing recently. In addition, digital sex crimes are becoming increasingly violent, so national measures are needed. In this study, statistical data at the national level were used to investigate the overall characteristics of digital sex crimes in Korea. First, statistical analysis shows that the victims are mainly women in their teens and 20s. Typical types of digital sex crimes are distribution of illegal contents and illegal filming, the perpetrators are mainly unknown, and digital sex crimes were less often recognized by others and more often by the victims themselves. Based on these results, countermeasures against various digital sex crimes are suggested

A Study on the Current Status and Improvement of the Digital Divide among Older People in Korea

In today’s knowledge- and information-based society, information literacy and information utilization skills are indicators of one’s competitiveness, and play a very important role in various fields (e.g., in one’s career, hobbies, as well as in daily life). In particular, information literacy and information utilization skills in older people are becoming essential for them to lead affluent lives. Moreover, information and communication technology is essential form of technology that can allow the elderly to ask for help in cases of emergency, as well as in daily life. Meanwhile, according to a recent Korean national statistical index, the digital divide among older people is more serious than that of the general public. The purpose of this paper is to statistically show that the digital divide among older people is more serious than other information-weak groups, as well as the general public. In addition, the purpose of this study is to identify the priorities that affect the digital divide among the three elements of the digital divide (digital access, digital capacity, and digital utilization) for older people. Based on that, we propose a variety of ways to solve the digital divide for older people. This study is expected to be widely used in future research and policies as a basis for solving the digital divide among older people

Semantic-Based Concurrency Control in Object-Oriented Databases

In this paper, we present a concurrency control scheme to increase concurrency among methods in Object-Oriented Databases. We are concerned with all types of access to an object: instance access and class definition access. For instance access, our work has the following characteristics. First, construction of commutativity relation among methods can be automated. Second, it provides more concurrency than read and write access modes on methods. Third, deadlocks due to lock escalation can be reduced. Finally, concurrency is increased further with the use of runtime information. For class definition access, we allow class definition access methods to run concurrently by taking fine granularity. We also allow more parallelism between class definition access methods and instance access methods. 1