• ETRI Journal
• /
• v.28 no.5
• /
• pp.593-606
• /
• 2006

Thanks to the great possibilities of providing different types of telecommunication traffic to a large geographical area, satellite networks are expected to be an essential component of the next-generation internet. As a result, issues concerning the designing and testing of efficient connection-admission-control (CAC) strategies in order to increase the quality of service (QoS) for multimedia traffic sources, are attractive and at the cutting edge of research. This paper investigates the potential strengths of a generic digital-video-broadcasting return-channel-via-satellite (DVB-RCS) system architecture, proposing a new CAC algorithm with the aim of efficiently managing real-time multimedia video sources, both with constant and high variable data rate transmission; moreover, the proposed admission strategy is compared with a well-known iterative CAC mainly designed for the managing of real-time bursty traffic sources in order to demonstrate that the new algorithm is also well suited for those traffic sources. Performance analysis shows that, both algorithms guarantee the agreed QoS to real-time bursty connections that are more sensitive to delay jitter; however, our proposed algorithm can also manage interactive real-time multimedia traffic sources in high load and mixed traffic conditions.

• Proceedings of the Korean Institute of Building Construction Conference
• /
• 2009.11a
• /
• pp.15-18
• /
• 2009

Due to its high dependency of manpower, construction work has several difficulties in terms of quality control, imbalance of supply and demand of qualified manpower, safety management for them and improvement of production. Such problems related to the management can be at some degree solved by introducing an automation facility. Since the unique environment of a construction site in the past was not structured, it is very hard to introduce a facility to automate construction work from operation of the equipment to assignment of where to work. This is a preliminary research for automation of construction work. In this study, the trend of development of a cutting-edge technology, RTLS, was researched and analyzed in order to review the possibility of utilizing RTLS in construction work and present a control mechanism for construction equipment. Although the presented mechanism is at the concept stage, which still has lots of restrictions to be solved, the application of the RTLS will be very much feasible. That is, if linkage of the study between the RTLS and the automation of construction is built, it will be expected to contribute to many fields such as cost reduction through efficient and systemic management, the reduction of construction period and precise construction as well as raising the level of the automation of domestic construction work.

• Korean Journal of Agricultural Science
• /
• v.44 no.3
• /
• pp.318-324
• /
• 2017

With the development of next-generation sequencing (NGS), a cutting-edge technology, genotype-by-sequencing (GBS) became available at a low cost per sample. GBS makes it possible to customize the process of library preparation to obtain high-quality single nucleotide polymorphisms (SNPs) in the most efficient way. However, a GBS library is hard to construct due to fine-tuning of concentration of each reagent and set-up. The major reason for this is the presence of undigested genomic DNA (gDNA) owing to the efficiency of different restriction enzymes for different species with unknown reasons. Therefore, this proof-concept study is to demonstrate the unpredictable patterns of enzyme digestion from various plants in order to make the reader aware of the caution needed when choosing restriction enzymes for their GBS library preparations. Indeed, no pattern was found for the digestibility of gDNA samples and restriction enzymes in the current study. We suggest that more data should be accumulated on this matter to help researchers who want to apply GBS technologies in a variety of genetic approaches.

• Maxillofacial Plastic and Reconstructive Surgery
• /
• v.40
• /
• pp.2.1-2.7
• /
• 2018

With the development of computer-aided design/computer-aided manufacturing (CAD/CAM) technology, it has been possible to reconstruct the cranio-maxillofacial defect with more accurate preoperative planning, precise patient-specific implants (PSIs), and shorter operation times. The manufacturing processes include subtractive manufacturing and additive manufacturing and should be selected in consideration of the material type, available technology, post-processing, accuracy, lead time, properties, and surface quality. Materials such as titanium, polyethylene, polyetheretherketone (PEEK), hydroxyapatite (HA), poly-DL-lactic acid (PDLLA), polylactide-co-glycolide acid (PLGA), and calcium phosphate are used. Design methods for the reconstruction of cranio-maxillofacial defects include the use of a pre-operative model printed with pre-operative data, printing a cutting guide or template after virtual surgery, a model after virtual surgery printed with reconstructed data using a mirror image, and manufacturing PSIs by directly obtaining PSI data after reconstruction using a mirror image. By selecting the appropriate design method, manufacturing process, and implant material according to the case, it is possible to obtain a more accurate surgical procedure, reduced operation time, the prevention of various complications that can occur using the traditional method, and predictive results compared to the traditional method.

• Journal of Korean Society of Industrial and Systems Engineering
• /
• v.31 no.4
• /
• pp.100-105
• /
• 2008

Cost reduction, time to market, and quality improvement of software product are critical issues to the software companies which try to survive in recent competitive market environments. Software Product Line Engineering (SPLE) is one of the approaches to address these issues. The goal of software product line is to maximize the software reuse and achieve the best productivity with the minimum cost. In software product line, software components are classified into the common and variable modules for composition work. In this paper, we proposed a dynamic composition process based on aspect-oriented programming methodology in which software requirements are classified into the core-concerns and cross-cutting concerns, and then assembled into the final software product. It enables developers to concentrate on the core logics of given problem, not the side-issues of software product such as transactions and logging. We also proposed useful composition patterns based on aspect oriented programming paradigm. Finally, we implemented a prototype of the proposed process using Java and Aspect to show the proposed approach's feasibility. The scenario of the prototype is based on the embedded analysis software of telecommunication devices.

• Proceedings of the Korean Institute of Interior Design Conference
• /
• 2008.05a
• /
• pp.128-133
• /
• 2008

As societal development improves the quality of life and changes the structure of society, the needs of the residents have been varied. As a result, the spaces in Korean houses have also been varied. This phenomenon can be found in both external and internal spaces; a transitional space, which connects the outside space and the inside space, is formed as transition occurs at each phase of movement. As the importance of external and internal spaces is emphasized, and as internal spaces are extended to the exterior, various forms of transitional space are needed. In this study, the boundary types of internal/external spaces are analyzed through transitional spaces that are formed in relation with internal and external spaces. Based on the analysis, transitional spaces in modem Korean houses are classified into the addition type, the cutting type, and the connection type. The results of the study show that transitional spaces in detached houses tend to be placed closely to rooms and a public space, and in terms of material use, the externalization of internal spaces is occurring.

• Magazine of the Korean Society of Agricultural Engineers
• /
• v.27 no.2
• /
• pp.47-56
• /
• 1985

Wasting fiberous residues from the cutting processes of steel materials at an iron-Works were mixed with concrete. The strength and toughness of steel fiber concrete with different steel contents were tested in a laboratory. The test results showed that the steel fiber residues can be used for the reinforcement of concrete. The potential applications of such product include floor constructions for facilities like dairy barns, grain storages, and machinery shops. The test results are as follows. 1. The compressive strengths of steel fiber concrete with one percent steel content by volume were 20 percent greater than that of plain concrete. The treatments also increased the concrete toughness by 96 percent. 2. When applied to tensile forces, the steel fiber concrete showed the increased strengths by 20 percent, and the toughness by 48 percent. 3. The steel content levels greater than or equal to 1.5 percent by volume resulted in the decreases of the compressive and tensile strengths of steel fiber concrete by 10 percent as compared to plain concrete. The concrete toughness increased with the steel contents. 4. The reinforcement effects of steel fiber depend on the quality of fiber material being used. Good steel fiber for concrete reinforcement appears to be uniform in shape and component, fine and long, and round-shaped.

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.15 no.2
• /
• pp.603-608
• /
• 2014

In many manufacturing such as the components of airplane and automobile, aluminum alloys(Al2024) which remarkable in low specific gravity and high strength have been utilized effectively. Face milling machining technology for surface roughness quality of workpiece has been applied in these fields. A face milling machining with chamfered throw away type insert tip can produce a perfect flat surface only in theory. But It is impossible because of many unwanted factors, namely, cutting temperature, plastic deformation, dynamic effect, etc. In this paper, experimental investigations are performed to improve surface roughness after high speed machining of Al2024 using qualified face milling cutter body for high speed machining.

• Journal of Power System Engineering
• /
• v.15 no.5
• /
• pp.22-29
• /
• 2011

In this study, the damage mechanism of large scale steam turbine due to water induction was analyzed and recovery characteristics were reviewed. A turbine consists of the rotating rotor and the stationary casing, and the clearance between them is very small for the efficiency enhancement. If water induction, while relatively cold steam or water is introduced into turbine, occurs, the considerable humping is caused at the casing near the initial water induction point and that induces the rubbing between rotor and casing. Finally, it leads to the catastrophic failure. Bowed rotor has the different characteristics in the recovery depending on damage degree. The elastic deformation due to light rubbing is recovered by turning the rotor with 3 rpm under normal operation condition, but most plastic deformation due to rubbing deforms the local microstructure and that results in permanent deformation which could not be recovered under normal operation condition. Bowed rotor has diverse characteristics depending on the recovery method, and the method is empirical and needs the cutting edge technology. Careful recovery treatment of the rotor will eliminate the risks and secure the high quality rotor similar to new rotor. If any critical error is made during the recovery, the rotor would not be recovered permanently and it should be scrapped.

• Journal of the Korean Society for Precision Engineering
• /
• v.22 no.6 s.171
• /
• pp.222-231
• /
• 2005

Recently, life cycle and lead-time of products have been shortened with the demand of customers. Therefore, it is important to reduce time and cost at the stage of manufacturing trial molds. In order to realize a three-dimensional shape on CAD, the machining process has been widely used because it offers practical advantages such as precision and versatility. However, the traditional machining process needs a large amount of time in cutting a product and the remained material causes trouble such as inconvenience for clarity. In this work, a new rapid manufacturing process using the hot tool, Rapid Heat Ablation process, has been developed to overcome such limitations. While the hot tool moves the predetermined path, the heat of the tool decomposes the remained material. The radius of heat affect ed zone related to process parameters was investigated through experiments to improve the quality of ablated parts. In order to examine the applicability of the proposed process, three-dimensional shapes such as hemisphere and standard test part, wereablatedutilizingtheapparatus.