• KSII Transactions on Internet and Information Systems (TIIS)
• /
• v.6 no.6
• /
• pp.1586-1605
• /
• 2012

With the prevalence of multimedia applications and the potential commercial usage of Mobile Ad hoc Networks (MANETs) in group communications, Quality of Service (QoS) support became a key requirement. Recently, some researchers studied QoS multicast issues in MANETs. Most of the existing QoS multicast routing protocols are designed with flat topology and small networks in mind. In this paper, we investigate the scalability problem of these routing protocols. In particular, a Position-Based QoS Multicast Routing Protocol (PBQMRP) has been developed. PBQMRP builds a source multicast tree guided by the geographic information of the mobile nodes, which helps in achieving more efficient multicast delivery. This protocol depends on the location information of the multicast members which is obtained using a location service algorithm. A virtual backbone structure has been proposed to perform this location service with minimum overhead and this structure is utilized to provide efficient packet transmissions in a dynamic mobile Ad hoc network environment. The performance of PBQMRP is evaluated by performing both quantitative analysis and extensive simulations. The results show that the used virtual clustering is very useful in improving scalability and outperforms other clustering schemes. Compared to On-Demand Multicast Routing Protocol (ODMRP), PBQMRP achieves competing packet delivery ratio and significantly lower control overhead.

• Journal of the Korea Institute of Information Security & Cryptology
• /
• v.24 no.4
• /
• pp.617-624
• /
• 2014

Smart phone usage has increased exponentially and open source based Android OS occupy significant market share. However, various malicious applications that use the characteristic of Android threaten users. In this paper, we construct an efficient malicious application detector by using the principle component analysis and the incremental k nearest neighbor algorithm, which consider an required permission, of Android applications. The cross validation is exploited in order to find a critical parameter of the algorithm. For the performance evaluation of our approach, we simulate a real data set of Contagio Mobile.

• Journal of the Korean Home Economics Association
• /
• v.46 no.10
• /
• pp.133-146
• /
• 2008

This study investgates the factors influencing the levels of consumer satisfaction and life satisfaction of resident foreigners in Korea. The data were collected through a structured self-administered survey and 545 foreigners who lived in Korea for more than 3 months, with age over 20 participated as respondents. A research framework was formulated based on the resource constraint hypothesis and the study investigated the impact of information resource(human, media and internet information source) and consumer resource(monthly income, language ability and consumer proficiency) on the levels of consumer satisfaction and life satisfaction. The results from data analysis can be summarized as follows; First, analysis of consumer problems of resident foreigners in Korea indicated that resident foreigners recognize a burden for residence cost, food expense and education fee. Most of resident foreigners in Korea are found to use small local shops most often indicating they may experience adverse market environment due to resource constraint such as language or psychological barrier, and most of the respondents answered that the most often used payment method was cash. Furthermore, resident foreigners in Korea responded that lack of language service, lack of information provision, inability to use certain goods and services are the common cause of consumer dissatisfaction, as well as price and quality problems. Second, the level of consumer satisfaction (2.96 in 4.0) is higher than the level of life satisfaction (2.63 in 4.0). Third, the level of life satisfaction is significantly influenced by Korean language ability and the level of consumer satisfaction. The level of consumer satisfaction is by the media information source usage and consumer claim experience. Fourth, the level of consumer satisfaction is found to be the variable with the strongest causal relationship with the level of life satisfaction.

• Journal of the Korean Society of Costume
• /
• v.50 no.8
• /
• pp.99-111
• /
• 2000

The purposes of this study were to segment the elderly women's apparel market according to their benefits sought and to develop the profiles of each segment. Questionnaire survey was done to 500 elderly women aged over 55 in Chonbuk province from Mar. 1. to Mar. 15, 2000, and 360 questionnaires were used. Frequencies, percentages, means, factor analysis, cluster analysis, $\chi$$^2$-test, and ANOVA were done with SPSS Win+. Duncan's Multiple Range test was followed. The factors of clothing benefits ere consisted of fashion, brand loyalty, economy, practicality, activity, and utility. The elderly women segmented into 4 groups of the reasonability pursuit, th economy & practicality, the benefit unconscious, and the fashion & brand pursuit. The fashion information sources were divided into mass communication-dominated source and point-of-purchase & consumer-dominated source. The factors of store patronage criteria were divided into product assortment, convenience, and additive service. The economy and practicality pursuit selected their clothing with the help of others, used any kind of information sources less, considered convience of the store more, shopped at traditional market, group size was the biggest, was the oldest, and educated less. The reasonability pursuit selected their clothing by themselves, used all kind of information sources, considered many facets of stores, shopped at department store, was younger, healthier, educated more, and lived with husband more. The benefit unconscious spent less money to their clothing, lower usage of information sources, selected their clothing with the help of others, considered all facets of stores less, shopped at moderate or volume zone apparel market or traditional market, was older, healthy, and involved the widowed more. The fashion and brand pursuit spent more money to clothing, considered the product assortment or additive service of store more, shopped at department store, and selected their clothing by themselves, group size was the smallest, was younger educated more, healthy, and showed a tendency of living with husband.

• Journal of the Korean Society for Precision Engineering
• /
• v.23 no.6 s.183
• /
• pp.143-150
• /
• 2006

Recently, in proportion to increased demand on environmentally-friendly heat source, efficient management of district heating(DH) system becomes one of important issue. The objectives of this paper are to systematize data processing of transition temperature, investigate the effect of temperature variations on thermal fatigue and find out a way to improve design fractures of Korean DH pipes. For this purpose, reliable fatigue lift evaluation procedures are examined and applied to quantify thermal fatigue lives. Also, as a prototypal optimization analysis results, mean value of original cross sectional area of selected pipes was reduced 18.6% sustaining their sufficient margins against fatigue failure. So, it is anticipated that the output of this research can be used as useful information of optimal design and operation in the future.

• Journal of the Institute of Electronics Engineers of Korea SP
• /
• v.41 no.1
• /
• pp.57-68
• /
• 2004

Although variable-length codes (VLCs) increase coding efficiency using the statistical characteristics of the source data, they have catastrophic effects from bit errors in noisy transmission environments. In order to overcome this problem with VLCs, reversible variable-length codes (RVLCS) have recently been proposed owing to their data recovering capability. RVLCS can be divided into two categories: symmetrical and asymmetrical RVLCs. Although the symmetrical RVLC has generally more overheads than the asymmetrical RVLC, it has some advantages of simpler design and more efficient memory usage. However, existing symmetrical RVLCs still have high complexity in their code design and some room for improvement in coding efficiency. In this paper, we propose a new algorithm for constructing a symmetrical RVLC from the optimal Huffman code table. The proposed algorithm has a simpler design process and also demonstrates improved performance in terms of the average codeword length relative to the existing symmetrical RVLC algorithms.

• Journal of the Korea Institute of Information and Communication Engineering
• /
• v.20 no.7
• /
• pp.1290-1295
• /
• 2016

Recently, as mobile internet usage has been increasing rapidly, malware attacks through user's web browsers has been spreading in a way of social engineering or drive-by downloading. Existing defense mechanism against drive-by download attack mainly focused on final download sites and distribution paths. However, detection and prevention of injection sites to inject malicious code into the comprised websites have not been fully investigated. In this paper, for the purpose of improving defense mechanisms against these malware downloads attacks, we focus on detecting the injection site which is the key source of malware downloads spreading. As a result, in addition to the current URL blacklist techniques, we proposed the enhanced method which adds features of detecting the injection site to prevent the malware spreading. We empirically show that the proposed method can effectively minimize malware infections by blocking the source of the infection spreading, compared to other approaches of the URL blacklisting that directly uses the drive-by browser exploits.

• The Transactions of the Korea Information Processing Society
• /
• v.4 no.3
• /
• pp.731-746
• /
• 1997

The usage of object models for the development of software has been frowung due to the prevalence of the ob-ject oriented paradigm.The object moedels produced as results of requirments analysis and design activities are vety veneficial to the implementation phase.It is even possible for source code to be genrated automatically if object models are concrete enough.Therefore system analyzers and desingners should make an dffort to refine theabstrace ogject model defined at.an early stage in order to achieve a more conrete object model.In general,re-fining an abstrace object model into a concrete model depends too much on the desigver's infromal experience.In this paper,we persent the refinement techniques required for concreting an abstract object model bassed on OMT(Object Modeling Technique)'s notation,We will discuss the definition of the abstraction level of an object model and the transformational rules of refinement.These transformational rules are currently applied to the design of a software tool,named Process Modeler,which is a major component of the software development process modeling system for ICS(Information Communication Service). Finally we can achieve a concrete object model which can easily be translated into C++ source code.

• Journal of Ocean Engineering and Technology
• /
• v.17 no.1
• /
• pp.61-66
• /
• 2003

A nautical chart is an essential material not only for the safety of navigation at sea, but also for the research and understanding of the ocean. Paper nautical harts have been used for navigational purposes for several hundreds years, but it was show that paper nautical charts have certain limitations, because the speed of ships has increased dramatically, and Global Positioning Systems (GPS) are now available at sea. Thus, the development of digital charts has been conducted by a number of countries. As a result, the International Hydrographic Organization (IHO) has developed a standard format, Special Publication No. 57 (S-57), as a guideline for the production of electronic navigational charts (ENC). Even though ENCs are a state-of-the-art navigational tool because they are produced on the basis of Geographical Information System (GIS) technology, they can be utilized for various purposes. in this paper, the usage of paper nautical charts, ENCs, and digital charts is reviewed. Also, the various application system that make use of electronic navigational harts and digital charts, as a basic geographical source of information, will be examined on the basis of GIS.

• Journal of Electrical Engineering and Technology
• /
• v.5 no.2
• /
• pp.307-318
• /
• 2010

In this work, an accurate analysis of low frequency current ripple in residential fuel cell power generation systems is performed based on the proposed residential load model and its unique operation algorithm. Rather than using a constant dc voltage source, a proton exchange membrane fuel cell (PEMFC) model is implemented in this research so that a system-level analysis considering the fuel cell stack, power conditioning system (PCS), and the actual load is possible. Using the attained results, a comparative study regarding the discrepancies of low frequency current ripple between a simple resistor load and a realistic residential load is performed. The data indicate that the low frequency current ripple of the proposed residential load model is increased by more than a factor of two when compared to the low frequency current ripple of a simple resistor load under identical conditions. Theoretical analysis, simulation data, and experimental results are provided, along with a model of the load usage pattern of low frequency current ripples.