• 한국신재생에너지학회:학술대회논문집
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• 2011.05a
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• pp.76.1-76.1
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• 2011

With the growing penetration of distributed generation including from renewable sources, smart grid power system is needed to address the reliability problem. One important feature of smart grid is demand response. In order to design a demand response program, it is indispensable to understand how consumer reacts upon the change of electricity price. In this paper, we construct an econometrics model to estimate the hourly price elasticity of demand. This panel model utilizes the hourly load data obtained from KEPCO for the period from year 2005 to 2009. The hourly price elasticity of demand is found to be statistically significant for all the sample under investigation. The samples used for this analysis is from the past historical data under the price structure of three different time zones for each season. The result of the analysis of this time of use pricing structure would allow the policy maker design an appropriate incentive program. This study is important in the sense that it provides a basic research information for designing future demand response programs.

• Journal of Computing Science and Engineering
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• v.3 no.1
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• pp.27-58
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• 2009

Aggregation join queries are an important class of queries over data streams. These queries involve both join and aggregation operations, with window-based joins followed by an aggregation on the join output. All existing research address join query optimization and aggregation query optimization as separate problems. We observe that, by putting them within the same scope of query optimization, more efficient query execution plans are possible through more versatile query transformations. The enabling idea is to perform aggregation before join so that the join execution time may be reduced. There has been some research done on such query transformations in relational databases, but none has been done in data streams. Doing it in data streams brings new challenges due to the incremental and continuous arrival of tuples. These challenges are addressed in this paper. Specifically, we first present a query processing model geared to facilitate query transformations and propose a query transformation rule specialized to work with streams. The rule is simple and yet covers all possible cases of transformation. Then we present a generic query processing algorithm that works with all alternative query execution plans possible with the transformation, and develop the cost formulas of the query execution plans. Based on the processing algorithm, we validate the rule theoretically by proving the equivalence of query execution plans. Finally, through extensive experiments, we validate the cost formulas and study the performances of alternative query execution plans.

• Proceedings of the Korea Air Pollution Research Association Conference
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• 2003.11a
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• pp.195-195
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• 2003

Combustion generated fine particles, defined as those with aerodynamic diameters less than 2.5 m, have come under increased regulatory scrutiny because of suspected links to adverse human health effects. Transition metals are of particular interest due to the results of a number of studies that have shown cardiopulmonary damage associated with exposure to these elements and their presence in coal, residual fuel oils, sewage sludge, and other combusted fuels and wastes. This lecture will review results from multi-di sciplinary studies being conducted at EPA and elsewhere examining the physical, chemical, and toxicological characteristics of combustion generated particles. The research describes how collaborative work between combustion engineers and health scientists can provide insight on how combustion processes affect particle properties and subsequent health effects as measured by a combination of in-vitro and in-vivo studies using a variety of animal models. The focus of this lecture is on the interdisciplinary approach required to address the problem. Difficulties are discussed. Engineering aspects involved in this approach are described in detail. Physical and chemical characterizations are performed using a variety of analytical approaches including new techniques of x-ray absorption fine structure (XAFS) spectroscopy and x-ray absorption near-edge structure (XANES) deconvolution of these spectra to gather metal speciation information.

• Journal of Computing Science and Engineering
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• v.10 no.2
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• pp.39-50
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• 2016

In this paper, we present a comparative study of spatial domain features for writer identification and verification with different ink width conditions. The existing methods give high error rates, when comparing two handwritten images with different pen types. To the best of our knowledge, we are the first to design the feature with different ink width conditions. To address this problem, contour based features were extracted using a chain code method. To improve accuracy at higher levels, we considered histograms of chain code and variance in bins of histogram of chain code as features to discriminate handwriting samples. The system was trained and tested for 1,000 writers with two samples using different writing instruments. The feature performance is tested on our newly created dataset of 4,000 samples. The experimental results show that the histogram of chain code feature is good compared to other methods with false acceptance rate of 11.67%, false rejection rate of 36.70%, average error rates of 24.18%, and average verification accuracy of 75.89% on our new dataset. We also studied the effect of amount of text and dataset size on verification accuracy.

• Journal of KIISE:Software and Applications
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• v.34 no.5
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• pp.487-501
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• 2007

To achieve high resource utilization for multi-issue DSPs, production compiler commonly includes variants of iterative modulo scheduling algorithm. However, excessive cyclic data dependences, which exist in communication and media processing loops, unduly restrict modulo scheduling freedom. As a result, replicated functional units in multi-issue DSPs are often under-utilized. To address this resource under-utilization problem, our paper describes a novel compiler preprocessing strategy for effective modulo scheduling. The preprocessing strategy proposed capitalizes on two new transformations, which are referred to as cloning and dismantling. Our preprocessing strategy has been validated by an implementation for StarCore SC140 DSP compiler.

• Journal of Korean Society on Water Environment
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• v.22 no.2
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• pp.193-202
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• 2006

About 99% of microorganisms in the environment are unculturable. However, advances in molecular biology techniques allow for the analysis of living microorganisms in the environment without any cultivation. With the advent of new technologies and the optimization of previous methods, various approaches to studying the analysis of living microorganisms in the environment are expanding the field of microbiology and molecular biology. In particular, real-time PCR provides methods for detecting and quantifying microorganisms in the environment. Through the use of the methods, researchers can study the influence of environmental factors such as nutrients, oxygen status, pH, pollutants, agro-chemicals, moisture and temperature on the performances of environmental processes and some of the mechanisms involved in the responses of cells to their environment. This review will also address information gaps in the analysis of the microorganisms using real-time PCR in the environmental process and possible future research to develop an understanding of microbial activities in the environment.

• Journal of Internet Computing and Services
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• v.19 no.2
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• pp.33-41
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• 2018

In recent years, technology is rapidly changing to support new service consumption and distribution models in multimedia service systems and hybrid delivery of media services is a key factor for enabling next generation multimedia services. This phenomenon can lead to rapidly increasing network traffic and ultimately has a direct and aggravating effect on the user's quality of service (QOS). To address the issue, we propose a novel system architecture to provide smart hybrid media services efficiently. The architecture is designed to apply the software-defined networking (SDN) method, detect changes in traffic, and combine the data, including user data, service features, and computation node status, to provide a service schedule that is suitable for the current state. To this end, the proposed architecture is based on 2-level scheduling, where Level-1 scheduling is responsible for the best network path and a computation node for processing the user request, whereas Level-2 scheduling deals with individual service requests that arrived at the computation node. This paper describes the overall concept of the architecture, as well as the functions of each component. In addition, this paper describes potential scenarios that demonstrate how this architecture could provide services more efficiently than current media-service architectures.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.10 no.3
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• pp.69-74
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• 2010

Due to a development of information and communications technology, now we can watch TV show whenever and wherever we want through DMB service. And this is different from existing TV service which we can just enjoy at certain place. Now, I will look into IPTV technology which is basis of Mobile IPTV service. And then, I will introduce Mobile IPTV service which combines the virtues of 'Mobility' of DMB technology and 'two-way communication' of IPTV technology and lets us enjoy two-way TV service at anytime and anywhere. And also I will check the problems of IPTV, on-going trend of Mobile IPTV(in service), and the perspective of Mobile IPTV. Finally, we suggest new fast duplicate address detection scheme in Mobile IPTV to support seamless IPTV packet transmission.

• The KIPS Transactions:PartC
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• v.8C no.6
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• pp.693-702
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• 2001

One of the major characteristics of C language is that it allows us to use pointer type variables to access any area of virtual address space. So, we can read/write/execute from/to virtual memory area not controlled delicately by operating system. We can access such memory area by using format string and it can be a vulnerability of C language from the point of secure programming. In this paper, we analyze in detail the process of security attack based on format string and then exploit a new virus style attack which is stepwise and durable with some actual scenarios to warn the severity of it, and grope for some preliminary responding actions.

• Journal of Convergence for Information Technology
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• v.9 no.9
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• pp.52-57
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• 2019

DNS stands for 'Domain Name System' and uses IP addresses to identify devices connected to the network on the network. IP is a protocol that registers and manages aliases such as IPs because it is difficult for general users to remember. In recent years, the abuse of such DNS is increasing abroad, and behind the scenes, called 'DNS pionage,' are developing and evolving new rules and malware. DNSpionage attack is abusing DNS system such as Increasing hacking success rate, leading to fake sites, changing or forged data. As a result it is increasing the damage cases. As the global DNS system is expanding to the extent that it is out of control. Therefore, in this research, the countermeasures of DNSpionage attack is proposed to contribute to build a secure and efficient DNS system.