• Convergence Security Journal
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• v.13 no.6
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• pp.3-9
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• 2013

With the rapidly changing information communication environment and development of technologies, the informati on networks are evolved from traditional fixed form to an active variable network that flexible large variety of data can be transferred. To reflect the needs of users, the next generation using DWDM (Dense Wavelength Division M ultiplexing) transmission system and OXC (Optical Cross Connect) form a dynamic network. After that GMPLS (Ge neralized Multi-Protocol Label Switching) can be introduced to dynamically manage and control the Reconfigurable Optical Add-drop Multiplexer (ROADM)/Photonic Cross Connect (PXC) based network. This paper propose a softw are architecture of Path Computation Element (PCE) protocol that has proposed by Internet Engineering Task Force (IETF) to path computation. The functional blocks and Application Programming Interface (API) of the PCE protoco l implementation are also presented.

• Transactions of the Korean Society of Machine Tool Engineers
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• v.14 no.4
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• pp.32-40
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• 2005

The purpose of this study is to investigate variation of spark plug protrusion and PDA valve on the exhaust emission in a gasoline engine. Swirl is one of the important parameters that affects the characteristics of combustion. PDA valve has been developed to satisfy requirements of sufficient swirl generation for improving the combustion and reducing of emission level. Also, especially, the variation of spark plug protrusion have an important effect to the early flame propagative process. This is largely due to the high flame speed by short of flame propagation distance. So, this is forced that injection timing, spark timing and intake air motion govern the stable combustion. As a result, using two combustion chamber, without charge of engine specification and the variable spark plug location and PDA valve could be reduced exhaust gas at a part load engine conditions(1500rpm imep 3.9bar, 2000rpm imep 3.2bar, 2400rpm imep 3.9bar).

• Transactions of the KSME C: Technology and Education
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• v.3 no.1
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• pp.63-69
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• 2015

Among the material handling system, EMS (Electric Monorail System), which is the facility of transferring the material hanging on truss, has the strength point of the maximum utilization of working space and the improvement of working environment including low-level noise generation. This paper will introduce the variable method of EMS rail analysis, which has the main role of supporting the whole material weight and guiding them with high-speed transportation, and, based on the analysis, the direction of optimization of the rail design be described. The rail with light-weight and high-strength contributes the reduction of the load of truss, the cost-down of rail production and the easy-installation on site.

• The Journal of the Korea Contents Association
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• v.18 no.7
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• pp.656-664
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• 2018

The following study was conducted to determine the optimal location in terms of efficiency for solar energy facilities, and to propose a policy implications for the orientation of the installments. 92 cases in Jeollanam-do Province were selected. A regression analysis was performed between the average electricity generation time as the dependent variable, and the facility, weather and site conditions as the independent variables. As a result, 5 variables were deemed significant. Larger site areas, closer proximity to rivers, islands, oceans, etc., least south-oriented, higher average wind speed, and facilities in agricultural land use and natural environment conservation land use had the highest efficiency. This study minimized the possibility of secure databases and errors following facility types, and was limited in the number of sites studied, since this was only conducted in Jeollanam-do Province. Nevertheless, these conclusions still offer important policy implications for determining the most optimal location for solar energy facilities.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.36 no.9
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• pp.1065-1071
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• 2012

Wind energy is becoming one of the most preferable alternatives to conventional sources of electric power that rely on fossil fuels. For stable electric power generation, constant rotating speed control of a wind turbine is performed through pitch control and stall control of the turbine blades. Recently, variable pitch control has been implemented in modern wind turbines to harvest more energy at variable wind speeds that are even lower than the rated one. Although wind turbine pitch controllers are currently optimized using a step response via the Ziegler-Nichols auto-tuning process, this approach does not satisfy the requirements of variable pitch control. In this study, the variable pitch controller was optimized by a genetic algorithm using a neural network model that was constructed by the Latin Hypercube sampling method to improve the Ziegler-Nichols auto-tuning process. The optimized solution shows that the root mean square error, rise time, and settle time are respectively improved by more than 7.64%, 15.8%, and 15.3% compared with the corresponding initial solutions obtained by the Ziegler-Nichols auto-tuning process.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.46 no.11
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• pp.66-76
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• 2009

The motion estimation in video encoding system occupies the biggest part. So, we require the motion estimator with efficient structure for real-time operation. And for motion estimator's implementation, it is desired to design hardware module of an exclusive use that perform the encoding process at high speed. This paper proposes motion estimation detection block(MED), 41 SADs(Sum of Absolute Difference) calculation block, minimum SAD calculation and motion vector generation block based on parallel processing. The parallel processing can reduce effectively the amount of the operation. The minimum SAD calculation and MED block uses the pre-computation technique for reducing switching activity of the input signal. It results in high-speed operation. The MED and 41 SADs calculation blocks are composed of adder tree which causes the problem of critical path. So, the structure of adder tree has changed the most commonly used ripple carry adder(RCA) with carry skip adder(CSA). It enables adder tree to operate at high speed. In addition, as we enabled to easily control key variables such as control signal of search range from the outside, the efficiency of hardware structure increased. Simulation and FPGA verification results show that the delay of MED block generating the critical path at the motion estimator is reduced about 19.89% than the conventional strukcture.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.25 no.4B
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• pp.661-674
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• 2000

The main memory DBMS(MMDBMS) efficiently supports various database applications that require high performance since it employs main memory rather than disk as a primary storage. In this paper, we discuss theexperiences obtained in developing the index manager of the Tachyon, a next-generation MMDBMS. The indexmanager is an essential sub-component of the DBMS used to speed up the retrieval of objects from a largevolume of a database in response to a certain search condition. Previous research efforts on indexing proposed various index structures. However, they hardly dealt with the practical issues occured in implementating an index manager on a target DBMS. In this paper, we touch these issues and present our experiences in developing the index manager on the Tachyon as solutions. The main issues touched are (1) compact representation of an indexentry, (2) support of variable-length keys, (3) support of multiple-attribute keys, (4) support of duplicated keys,(5) definition of external APls, (6) concurrency control, and (7) backup and recovery. We believe that ourcontribution would help MMDBMS developers highly reduce their trial-and-errors.

• Journal of Advanced Navigation Technology
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• v.6 no.1
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• pp.69-76
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• 2002

With the growth of data communication service by mobile devices, WAP is proposed to efficiently access the Internet contents by user request through wireless condition that has a high error rate and mobility. But, because a transmission speed of WAP is limited, it takes many times to transmit and to receive the data. This paper has studied the WAP packet transmission time using WTP-SAR algorithm. As a method that is to improve transfer capability of WAP, using SAR function in WTP, total message down from upper layer has been fragmented and packet is transmitted through RLP frame time slot. Then, we have analyzed the transmission time of WAP packet with variable RLP layer size on the wireless CDMA network for next generation systems. From the results, we could obtain the WAP packet transmission time and optimal WTP packet size.

• New & Renewable Energy
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• v.8 no.2
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• pp.14-23
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• 2012

The TMY (Typical Meteorological Year) for the solar energy study is generated using observation data with 22 solar sites from KMA (Korea Meteorological Administration) during 11 years (2000-2010). The meteorological data for calculation the TMY are used solar radiation, temperature, dew point temperature, wind speed and humidity data. And the TMY is calculated to apply the FS (Finkelstein and Schafer) statistics and RMSE (Root Mean Squared Error) methods. FS statistics performed with each point and each variable and then selected top five candidate TMM months with statistical analysis and normalization. Finally TMY is generated to select the highest TMM score with evaluation the average errors for the 22 whole points. The TMY data is represented average state and long time variations with 22 sites and meteorological data. When TMY validated with the 11-year daily solar radiation data, the correlation coefficient was about 0.40 and the highest value is 0.57 in April and the lowest value is 0.23 in May. Mean monthly solar radiation of TMY is 411.72 MJ which is 4 MJ higher than original data. Average correlation coefficient is 0.71, the lowest correlation is 0.43 in May and the highest correlation is 0.90 in January. Accumulated annual solar radiation by TMY have higher value in south coast and southwestern region and have relatively low in middle regions. And also, differences between TMY and 11-year mean of is distributed lower 100 MJ in Kyeongbuk, higher 200 MJ in Jeju and higher 125 MJ in Jeonbuk and Jeonnam, respectively.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.12 no.4_1
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• pp.137-150
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• 1992

A complete solution, exact to second-order, for wave motion forced by a hinged-wavemaker of variable-draft is presented. A solution for a piston type wavemaker is also obtained as a special case of a hinged-wavemaker. The laboratory waves generated by a plane wave board are shown to be composed of two components; viz., a Stokes second-order wave and a second-harnomic free wave which travels at a different speed. The amplitude of the second-harmonic free wave is relatively large in shallow water and decreases to less than 10% of the amplitude of the primary wave in deep water. Wavemakers with relatively deeper draft (i.e., hinged near the bottom) generate the free waves of smaller amplitude in shallow and intermediate water depths than the wavemakers with shallow draft. However, the opposite is predicted by theory in deep water.