• Transactions of the Korean Society of Mechanical Engineers B
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• v.24 no.11
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• pp.1457-1463
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• 2000

Experimental studies on determination of the supply leading time of propellants to combustion chamber have been made to stably and efficiently guarantee the ignitions process with liquid rocket engine. The propellant used is a Kerosene as fuel and a liquid oxygen as oxidizer. FOOF type of three injectors are set with an angle of 135。 and the combustion chamber pressure is 200psi. The present experiment program also includes the stability on the quadlet type of ignitor using the triehylaluminum (TEAL) as an ignition source. Experimental results clarifies that the propellant supply through LOx leading to combustion chamber is proper for stable ignition and combustion processes based on the fuel and oxidizer manifold pressures, combustion chamber pressure, and the variation of flame length from the nozzle exit with lapse time, and shows that the leading supply time pf propellants effects the engine performance little.

• The Journal of the Korea Contents Association
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• v.17 no.3
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• pp.589-595
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• 2017

We present an estimation model for optimal channel capacity required to data traffic transmission. The optimal channel capacity should be calculated in order to satisfy the permitted transmission delay of each wireless data services. Considering the discrete-time operation of digital communication systems and batch arrival of packet-switched traffic for various wireless services, $Geo^x$/G/1 non-preemptive priority queueing model is analyzed. Based on the heuristic interpretation of the mean waiting time, the mean waiting times of various data packets which have the service priority. Using the mean waiting times of service classes, we propose the procedure of determining the optimal channel capacity to satisfy the quality of service requirement of the mean delay of wireless services. We look forward to applying our results to improvement in wireless data services and economic operation of the network facilities.

• Journal of Energy Engineering
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• v.20 no.2
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• pp.123-142
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• 2011

Coal Gasification Technology is one of the best alternatives among clean fossil fuel utilization. Major technology holding companies are devoting their efforts to develop more advanced technology to dominate the market in advance because of its importance on the applications such as IGCC, CTL, coal to SNG, various chemicals and so on. Japan and China, as well as America and European countries, have developed couple of thousands ton/day-class coal gasification technology. However, our gasification technology remains in the development stage with couple of ton/day-class pilot plant. So, we should be interested in developing this technology considering that we are heavily dependent of coal energy. In this paper, we summarized the trend and status of coal gasification technology development and commercial deployment of major technology holding companies mainly from the presentation materials of 'Gasification Technology Conference 2010', which is the biggest place of information exchange for recent coal gasification technology.

• The Journal of the Korea Contents Association
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• v.10 no.10
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• pp.140-151
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• 2010

In the era of the rapid change of broadcasting industry, Korean terrestrial TV, dominant player, face also to severe competition with the new media platforms. To survive in the traditional market and to be winner in the new market, they tend to diverse their activities. Particularly, they expand the activities to the content business. Therefore, this study focus on the diversification of 3 major free TV, KBS, MBC, SBS. As a result, Korean terrestrial TV still dominate content industry with their enormous library and their distribution networks : they conflict with the independent companies and do the contents business exclusively. There are no rooms for the independent distributor. Among 3 players, the strategies of SBS have been oriented to the business and in the field of MPP(Multiple program Provider), the performance of MBC has been remarkable.

• Journal of Korean Society for Geospatial Information Science
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• v.16 no.4
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• pp.25-31
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• 2008

As we choose ground control points for aerial triangulation, we have a lot of problems in a mountain, a costal area, a desert, the foreshore etc because they don't have clear topography for control points and it spends a lot of cost and occurs problems of accuracy. In this study, we compare and analyze between ground control points from LiDAR intensity, digital map with ground control points from the field survey as doing AT each. As the result, the average error was ${\pm}1.02m$ from using LiDAR intensity, ${\pm}1.13m$ from using digital map. this result can present the control points from LiDAR intensity is 0.11m better than from digital map.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2013.05a
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• pp.482-485
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• 2013

With the advent of smart age, the concern on smart work has gradually increased in solving our social problems including low birth, aging, low productivity and green growth with low carbon as well as encouraging the balance between work and life. In addition, the competitiveness among companies and countries to preoccupy the advanced smart work technologies which lead the economic growth in the future have increased more than ever before. So have global standard competitiveness done under the situation of using international standardization as practical strategy for dominating market. It is essential to make standardization strategy and do systematic implementation for core technology which leads global market in order to fit such an environment and introduce smart work as soon as possible. Therefore, this paper suggests standardization items which lead global standard and implementation direction on standardization through analysing the current situation introducing smart work and technology/standardization trend.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2001.10a
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• pp.450-453
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• 2001

It is requested interoperability and inter-connection among technologies due to inertia and network externalities in the telecommunications industry. for that reason, firms in the telecommunications industry compete intensively against preempting their markets. Consumers' utilties can be increased, but searching or transaction cost of consumers may be decreased by standardization which is the core issue in the telecommunications. Also, standardization may prevent firms in that industry from overplus investment. However standardization may decrease the diversity of goods and technologies, so it can be the constraint factor in the consumption. In this paper, we'll examin the economic effects of standardization in the telecommunication industry and the effects to the industrial structure of standardization. After that, we'll suggest national policies in relation to standardization.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• v.9 no.1
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• pp.965-968
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• 2005

According to the rapid development of IT technologies, between different technologies and weakness of entry barriers, standardization for interoperability and intercompatibility is being recognized as a core strategy for preoccupation of global IT market and strengthening of national competitive power. Recently IPR(Intellectual property Rights) including patents is considered indispensably in international standardization. Also advanced countries strengthen their positions through preemption of global IT market by linking their IPR with international standardization. Therefore relationship between IPR and standardization is being changed to mutually complementary from mutually exclusive. In this paper, we will examine ITU-T's IPR policy and related discussion trends in ITU-T and try to find national policy for IPR related issues.

• The Transactions of the Korea Information Processing Society
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• v.6 no.12
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• pp.3652-3661
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• 1999

To support multimedia applications such as a multimedia communication systems and multimedia broadcasting, an operating system need to predict their timing-constraints. So, In this real-time systems, we must solve the priority inversion problem that may make the behavior of unpredictable systems and need a real-time server model that provides a better preemptability and minimizes a system overhead. In current real-time systems, the single thread server model, the worker model and the dynamic server model are being used for synchronization but they cannot propose an effective structure for managing shared resources. In this paper, the priority inheritance protocol is used to solve the priority inversion problem and the hybrid prioritized worker model is proposed, which can provide a more effective structure and a faster response time minimizing a system overhead. The hybrid prioritized worker model is to combine the static and the dynamic prioritized worker model, and have a better performance than other models in response time which is an important factor in a real-time system.

• Journal for History of Mathematics
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• v.18 no.4
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• pp.49-66
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• 2005

Finite element Methods(FEM) have been the primary computational methodologies in science and engineering computations for more than half centuries. One of the main limitations of the finite element approximations is that they need mesh which is an artificial constraint, and they need remeshing to solve in some special problems. The advantages in meshfree Methods is to develop meshfree interpolant schemes that only depends on particles, so they relieve the burden of remeshing and successive mesh generation. In this paper we describe the development of meshfree particle Methods and introduce the numerical schemes for Smoothed Particle hydrodynamics, meshfree Galerkin Methods and meshfree point collocation mehtods. We discusse the advantages and the shortcomings of these Methods, also we verify the applicability and efficiency of Meshfree Particle Methods.