• International Journal of Aeronautical and Space Sciences
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• v.18 no.2
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• pp.175-185
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• 2017

This paper presents new differential methods for computing the combined and single dynamic stability derivatives of flight vehicle. Based on rigid dynamic mesh technique, the combined dynamic stability derivative can be achieved by imposing the aircraft pitching to the same angle of attack with two different pitching angular velocities and also translating it to the same additional angle of attack with two different rates of angle of attack. As a result, the acceleration derivative is identified. Moreover, the rotating reference frame is adopted to calculate the rotary derivatives when simulating the steady pull-up with different pitching angular velocities. Two configurations, the Hyper Ballistic Shape (HBS) and Finner missile model, are considered as evaluations and results of all the cases agree well with reference or experiment data. Compared to traditional ones, the new differential methods are of high efficiency and accuracy, and potential to be extended to the simulation of combined and single stability derivatives of directional and lateral.

• Journal of the Korea Computer Industry Society
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• v.4 no.12
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• pp.1043-1052
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• 2003

In this paper, we present a fast motion estimation algorithm to reduce the computations of block matching algorithm for motion estimation in video coding. The proposed algorithm is based on Multi-level Successive Elimination Algorithm and Efficient Multi-level Successive Elimination Algorithms. The best estimate of the motion vectors can be obtained by hierarchical search point sampling and thus the proposed algorithm can decrease the number of matching evaluations that require very intensive computations. The efficiency of the proposed algorithm was verified by experimental results.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.33 no.9B
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• pp.786-794
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• 2008

IETF's NETCONF WG has taken efforts in standardizing configuration management protocol, which allows high interoperability of configuration management. In addition to interoperability, high performance is also required in configuration management, but many researches have often discarded the performance aspect of it. In order to fill that void, this paper proposes methods to improve performance with layers of NETCONF. It demonstrates and compares the performance evaluations to verify the efficiency of the proposed methods.

• Proceedings of the KIEE Conference
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• 2006.07d
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• pp.2013-2014
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• 2006

For large capacity optical CDMA networks, we propose a shared-type encoder/decoder based on an tunable wavelength conveter (TWC) and an arrayed waveguide grating (AWG) router. Feasibility of the structure of the proposed encoder/decoder for dynamic code allocation is tested through simulations using three types of wavelength/time 2-D codes, which are the generalized multi-wavelength prime code(GMWPC), the generalized multi-wavelength Reed-Solomon code(GMWRSC) and the matrix code. Test results show that the proposed encoder/decoder can increase the channel efficiency not only by increasing the number of simultaneous users without any multiple-access interference but by using a relatively short length CDMA codes.

• KIEAE Journal
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• v.12 no.2
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• pp.33-38
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• 2012

This study aims to evaluate the structural safety of the balcony photovoltaic systems easily installed or moved on the buildings. Also, the systems are controlled by solar altitudes focused on its mobility rather than high efficiency generation performance thereof. The results of the study are as follows. Two types of typical photovoltaic systems which can be mounted on the balcony are proposed, and, the sizes of the systems are designed to be adjusted within certain ranges of the frames in order to attach the various rail sizes. To evaluate the structural safety of the proposed systems, several simulation evaluations are performed on the safety evaluation standards by the Ministry of Construction-Transportation and KCI 2007. The results are that the proposed plans are reasonable in terms of stress and deflection in the structural aspects at the wind pressures of $1,907(N/m^2)$ of external wall surface under the condition of wind velocity higher than 25(m/s).

• 한국정보디스플레이학회:학술대회논문집
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• 2006.08a
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• pp.1202-1205
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• 2006

Dynamic Driving Carbon Nanotube Backlight Units (CNT-BLUs) can well utilize the persistence of their phosphor. This paper studies several dynamic driving schemes for the CNT-BLU developed by DTC/ITRI. Their illuminating efficiencies are experimentally evaluated. From these evaluations, this paper develops a new driving approach and even better efficiencies are obtained.

• The Transactions of the Korean Institute of Electrical Engineers A
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• v.53 no.2
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• pp.121-128
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• 2004

This paper presents a new approach for determining an accurate incentive levels of Direct Load Control (DLC) program using sequential Monte Carlo Simulation (MCS) techniques. The economic analysis of DLC resources needs to identify the hourly-by-hourly expected energy-not-served resulting from the random outage characteristics of generators as well as to reflect the availability and duration of DLC resources, which results the computational explosion. Therefore, the conventional methods are based on the scenario approaches to reduce the computation time as well as to avoid the complexity of economic studies. In this paper, we have developed a new technique based on the sequential MCS to evaluate the required expected load control amount in each hour and to decide the incentive level satisfying the economic constraints. In addition, the mathematical formulation for DLC programs' economic evaluations are developed. To show the efficiency and effectiveness of the suggested method, the numerical studies have been performed for the modified IEEE reliability test system.

• Journal of Ocean Engineering and Technology
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• v.16 no.6
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• pp.76-81
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• 2002

The purpose of this study is to set up the optimum economical formation of the purse seiner fishing system. For this task, the characteristics of existing purse-seiner fishing system were reviewed, and the possible formations of the fleet in tile purse-seiner fishing system were examined through the reallocation of function for each individual vessel. In addition, economic evaluations of the possible formations of the fleet are carried out. Consequently, it was found that 2-vessel formations have the most economic efficiency. Then, a conceptual system design for the main vessel in the 2-vessel formations was performed. As a result, this paper can be used as a helpful guideline to develop the most profitable and economical fishing system in the fleet type fishery.

• 유체기계공업학회:학술대회논문집
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• 2001.11a
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• pp.135-142
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• 2001

Design optimization of a transonic compressor rotor (NASA rotor 37) using response surface method and three-dimensional Navier-Stokes analysis has been carried out in this work. Baldwin-Lomax turbulence model was used in the flow analysis. Three design variables were selected to optimize the stacking line of the blade. Data points for response evaluations were selected by D-optimal design, and linear programming method was used for the optimization on the response surface. As a main result of the optimization, adiabatic efficiency was successfully improved. Ana, it is found that the design process provides reliable design of a turbomachinery blade with reasonable computing time.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.11 no.5
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• pp.76-81
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• 2012

The continuing demand for increasingly slimmer and brighter liquid crystal display(LCD) panels has led to an increased focus on the role of the light guide panels(LGPs) or optical films that are used to obtain diffuse, uniform light from the backlight unit(BLU). And the most basic process in the production of such BLU components is the micromachining. LCD BLUs comprise various optical elements such as a LGP, diffuser sheet, prism sheet, and protector sheet with micro patterns. High aspect ratio patterns are required to reduce the number of sheets and enhance light efficiency, but there is a limit to the aspect ratio achievable for a given material and cutting tool. Therefore, this study comprised a series of experimental evaluations conducted to determine the machining feasibility in microcutting various aspect ratio patterns on electroless nickel plated die materials when using single-crystal diamond tools. Cutting performance was evaluated at various cutting speeds and depths of cut using different machining methods and machine tools.