• The KIPS Transactions:PartC
• /
• v.14C no.4
• /
• pp.365-370
• /
• 2007

Connected Dominating Set(CDS) has been used as a virtual backbone in wireless ad hoc networks by numerous routing and broadcast protocols. Although computing minimum CDS is known to be NP-hard, many protocols have been proposed to construct a sub-optimal CDS. However, these protocols are either too complicated, needing non- local information, not adaptive to topology changes, or fail to consider the difference of energy consumption for nodes in and outside of the CDS. In this paper, we present two Timer-based Energy-aware Connected Dominating Set Protocols(TECDS). The energy level at each node is taken into consideration when constructing the CDS. Our protocols are able to maintain and adjust the CDS when network topology is changed. The simulation results have shown that our protocols effectively construct energy-aware CDS with very competitive size and prolong the network operation under different level of nodal mobility.

• The KIPS Transactions:PartD
• /
• v.15D no.3
• /
• pp.313-320
• /
• 2008

A typical software development life cycle consists of a series of phases, each of which has some ability to insert and detect defects. To achieve desired quality, we should progress the defect removal with the all phases of the software development. The well-known model of phase-based defect profile is Gaffney model. This model assumes that the defect removal profile follows Rayleigh curve and uses the parameters as the phase index number. However, these is a problem that the location parameter cannot present the peak point of removed defects when you apply Gaffney model to the actual situation. Therefore, Gaffney model failed to represent the actual defect profile. This paper suggests two different models: One is modified Gaffney model that introduce the parameter of Putnam's SLIM model to replace of the location parameter, the other is the growth function model because the cumulative defect profile shows S-shaped. Suggested model is analyzed and verified by the defect profile sets that are obtained from 5 different software projects. We could see from the experiment, the suggested model performed better result than Gaffney model.

• Journal of KIISE:Software and Applications
• /
• v.31 no.11
• /
• pp.1455-1473
• /
• 2004

This paper suggests a technique, TELOR(Technique of Object Extraction Based on Legacy System Interface for Improvement of Object Reusability) for reuse and reengineering by analyzing the Legacy System interface to distill the meaningful information from them and disassemble them into object units which are to be integrated into the next generation systems. The TELOR method consists of a 4 steps procedure: 1) the interface use case analysis step, 2) the interface object dividing step, 3) the object structure modeling step, and 4) the object model integration step. In step 1, the interface structure and information about the interaction between the user and the Legacy System are obtained. In step 2, the interface information is divided into semantic fields. In step 3, studies and models the structural and collaborative relationship among interface objects. Finally, in step 4, object model integration step, integrates the models and improves the integrated model at a higher level. The objects integration model created through TELOR provides a more efficient understanding of the Legacy System and how to apply it to next generation systems.

• Journal of KIISE
• /
• v.42 no.3
• /
• pp.399-407
• /
• 2015

Wireless sensor networks are used for data collection and processing from the surrounding environment for various applications. Since wireless sensor nodes operate on low computing power, restrictive battery capacity, and low network bandwidth, their architecture model has greatly affected the performance of applications. If applications have high computation complexity or require the real-time processing, the centralized architecture in wireless sensor networks have a delay in data processing. Otherwise, if applications only performed simple data collection for long period, the distributed architecture wasted battery energy in wireless sensors. In this paper, the energy consumption and processing delay were analyzed in centralized and distributed sensor networks. In addition, we proposed a new hybrid architecture for wireless sensor networks. According to the characteristic of applications, the proposed method had the optimal number of wireless sensors in wireless sensor networks.

• Journal of KIISE:Information Networking
• /
• v.34 no.1
• /
• pp.48-61
• /
• 2007

WiBro (Wireless Broadband) service, developed in Korea, can provide the host mobility while its users hang around within the subnet. Next-generation Internet protocols, IPv6 and Mobile IPv6 (MIPv6), provide a plenty of addresses to the nodes and enable the handover between different subnets. However, MIPv6 is not enough to support a real time service such as VoIP (Voice over IP) due to the long latency, and it is necessary to develop an enhanced handover mechanism which is optimized to the WiBro networks. In this paper, we suggest an improved fast handover mechanism while the mobile node moves around WiBro networks. The proposal is based on Fast Mobile IPv6 (FMIPv6) which is the representative protocol for fast handover, and reduces the handover latency by the close interaction between the link layer (WiBro MAC) and IP layer (FMIPv6). Finally, we analyze the performance of proposed mechanism through the mathematical analysis.

• The Journal of the Korea Contents Association
• /
• v.10 no.7
• /
• pp.244-252
• /
• 2010

The purpose of this study was to provide the fundamental data for further developments of the school dental clinic program through evaluating oral health knowledge, status and attitude of school dental program subjected on teachers who had experienced the program. The subjects were total 186 teachers from 8 elementary school in Ulsan metropolitan city area that had been operating school dental clinic program from 1999 to 2005. For the teachers by school and period of operation, the level of knowledge and behavior of oral health were no difference, however the recognition and behavior level in shorter operation group were higher, the level of recommend other school was higher than previous research. The efforts for further development school dental clinic program associated with advanced countries should be emphasized including the higher interests, more active participation and strengthened education. The systematic supports would be also important.

• The Journal of the Korea Contents Association
• /
• v.10 no.9
• /
• pp.348-362
• /
• 2010

In the Knowledge-based economy, it is inevitable for companies to implement knowledge management(KM in short) to improve management performance. In order to better understand the KM, it is necessary to examine the relationship between success factors of KM and KM performance in agribusiness sector. This study empirically analyzes the impact of success factors of Knowledge Management on companies' management performance in agribusiness cluster. From the survey data of 43 companies located in Sunchang fermented soybean products Industrial cluster, the study finds that four factors- learning culture, network, knowledge sharing and knowledge creating- influence management performance in a positive way. It also examines whether Industrial cluster strategy functions as a moderator between KM success factors and companies' performance. Furthermore, this study concludes that Sunchang fermented soybean Industrial cluster has not reached to the final stage of KM and suggests elements for further improvements.

• The Journal of the Korea Contents Association
• /
• v.14 no.1
• /
• pp.305-317
• /
• 2014

The purpose of this study is to examine sociological characteristics, internet and smartphone use characteristics of adults with Internet Addiction, so that the results will be used for the identification of the adult internet addicts, the planning and performing of prevention, counseling of adult internet addicts. This study is explorative study in order to find a sociological profile of adults with internet addiction. Using the data of survey on internet addiction 4787 adults in the age of 20~39 who used internet at least one time within a week were analysed. The results of this study showed that there were significant differences in sociological characteristics like in gender, age, education, occupation as well as in internet use characteristics like spending hours on internet use, the first year of internet use etc. Thirdly, the addict group reported that internet use hour increased due to smartphone usage, and that they overused SNS. Finally, implications and suggestions for further studies are discussed.

• International Journal of Highway Engineering
• /
• v.12 no.1
• /
• pp.55-59
• /
• 2010

High VOC(Vehicle Operating Cost) is the main reason for the rehabilitation of paved road and VOC is composed of fuel consumption, lubricant oil consumption, parts consumption, etc. Fuel consumption is one of the largest components of VOC and the roughness of road represents the deterioration level of the road. For these reasons, the fuel consumption is measured for different IRI(International Roughness Index) in this study. The fuel consumption was measured by processing the voltage signal of fuel injector of vehicle and the speed was measured with GPS. The change rate of fuel consumption for different IRI can be calculated with the results of this test. It's concluded that fuel consumption(L/100km) of medium and large passenger car increases 7 times fast of the increase of IRI(m/km) around 3.5m/km in the speed range of 40 ~ 100km/h, and fuel consumption is the best at 60km/h.

• Journal of the Korean Society for Aeronautical & Space Sciences
• /
• v.46 no.7
• /
• pp.527-534
• /
• 2018

The endurance of the multi-copter is one of the important variables that determine the mission performance. Therefore, accurate endurance should be defined as essential for performing effective missions. In this paper, we present the results of the study on the flight performance of the aircraft, especially the hovering of the drone(multi-copter). Unlike conventional aircraft, which consider aerodynamic performance by the fuselage, the multi-copter is mostly determined by the propulsion system. Therefore, the research method classifies the various parts constituting the drone system into functions, analyzes the performance of the unit parts and obtains the experimental data by sorting out the specifications and functions at the component level and mathematical formulation, The results of this study are as follows. In addition, the 5kg class quad copter was used to predict and verify the voltage change with endurance through analysis of in situ flight. By predicting endurance under various conditions, it can help design/build the right Multi-copter for mission.