• Proceedings of the Korean Society of Precision Engineering Conference
• /
• 2007.06a
• /
• pp.607-608
• /
• 2007

• Proceedings of the Korean Society for Agricultural Machinery Conference
• /
• 1996.06a
• /
• pp.7-11
• /
• 1996

• The Transactions of the Korean Institute of Electrical Engineers P
• /
• v.53 no.4
• /
• pp.201-204
• /
• 2004

In this paper, a direct adaptive tracking controller based Lyapunov method is designed for a wheeled mobile robots. A wheeled mobile robots have three degrees of freedom and two control variables. Therefore, it is difficult to control a mobile robot using the general linear control. We introduce two kinds of Lyapunov function for the design of the controller and verify the controller. A mobile robots using the designed adaptive direct tracking controller is well-behaved and is easily implemented.

• 제어로봇시스템학회:학술대회논문집
• /
• 1996.10b
• /
• pp.453-456
• /
• 1996

In this paper, the direct adaptive control using neural networks is presented for the control of chaotic nonlinear systems. The direct adaptive control method has an advantage that the additional system identification procedure is not necessary. In order to evaluate the performance of our controller design method, two direct adaptive control methods are applied to a Duffing's equation and a Lorenz equation which are continuous-time chaotic systems. Our simulation results show the effectiveness of the controllers.

• Journal of the Computational Structural Engineering Institute of Korea
• /
• v.21 no.1
• /
• pp.21-34
• /
• 2008

An improved optimum design method for reinforced concrete frames using integrated genetic algorithm(GA) with direct search method is presented. First, various sets of initially assumed sections are generated using GA, and then, for each resultant design member force condition optimum solutions are selected by regression analysis and direct search within pre-determined design section database. In advance, global optimum solutions are selected from accumulated results through several generations. Proposed algorithm makes up for the weak point in standard genetic algorithm(GA), that is, low efficiency in convergence causing the deterioration of quality of final solutions and shows fast convergence together with improved results. Moreover, for the purpose of elevating economic efficiency, optimum design based on the nonlinear structural analysis is performed and therefore makes all members resist against given loading condition with the nearest resisting capacity. The investigation for the effectiveness of the introduced design procedure is conducted through correlation study for example structures.

• Journal of the Society of Naval Architects of Korea
• /
• v.43 no.4 s.148
• /
• pp.484-493
• /
• 2006

Recently, direct load analysis using ship motion program is required to confirm structural safety for the Post-Panamax class large container carrier. However, there is no exact comparative study data for structural response between 20 and 30 wave load. So, in this paper, to compare the hull girder stress response between 20 versus 3D wave load calculation method, direct load analysis and global F.E analysis have been performed for three kinds of large container vessels using each 20 and 30 wave load calculation program. The results of 2D wave load RAO(Response Amplitude Operator) of each dominant load parameter(vertical, torsional and horizontal moment) are generally bigger than that of 30 results, especially in vertical wave bending moment. And the results of structural analysis based on the equivalent design wave method shows that there is a big difference in view of stress, but the stress distribution is very similar for each wave load case.

• Nuclear Engineering and Technology
• /
• v.52 no.4
• /
• pp.734-741
• /
• 2020

A new air-cooled waste heat removal system with a direct contact heat exchanger was designed for SMRs requiring 200 MW of waste heat removal. Conventional air-cooled systems use fin structure causing high thermal resistance; therefore, a large cooling tower is required. The new design replaces the fin structure with a vertical string type direct contact heat exchanger which has the most effective performance among tested heat exchangers in a previous study. The design results showed that the new system requires a cooling tower 50% smaller than that of the conventional system. However, droplet formation on a falling film along a string caused by Rayleigh-Plateau instability decreases heat removal performance of the new system. Analysis of Rayleigh-Plateau instability considering drag force on the falling film surface was developed. The analysis results showed that the instability can be prevented by providing thick string. The instability is prevented when the string radius exceeds the capillary length of liquid by a factor of 0.257 under stagnant air and 0.260 under 5 m/s air velocity.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
• /
• 2002.05a
• /
• pp.559-564
• /
• 2002

Cross-talk cancellation, inverse filter design or deconvolution in a generic term, is a vital process for a virtual sound realization in the stereo sound reproduction system. Most, if not all, of the design algorithms available for the inverse filter are based on a linearized model of the real physical plant. The result of such a plant-based design method, which may be referred to here as the indirect method, is biased due to both modelling and inversion errors. This paper presents a novel direct cross-talk cancellation method that may be free from the inversion error. The direct method can directly models the inverse filter by a suitable rearrangement of the input and output ports of the original plant so that no inversion is required here. Advantages are discussed with various experiments in an anechoic chamber using a PC soundcard. Binaural reproduction tests conducted showed that the conventional indirect method yields about 8 % reproduction performance error on both ear positions, whereas the direct method offers about 3 %.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
• /
• 2007.06a
• /
• pp.415-415
• /
• 2007

In this study. it was investigated about optical simulation in direct-type backlight design. Direct-type backlight has been used high-brightness backlight such as LCD television application. The key parameter in designing direct-type backlight was consists of three geometrical dimension such as the distance of two lamps. the gap of lamp and reflection plate and the number of lamps. It has many variation in optical design and it causes the different properties in backlight system. It shows the best values of above parameters; 26mm of the distance of two lamps. 4.5mm of the gap of lamp and reflection plate and 16 lamps. And we produced the specimen as above condition. and acquired good result in backlight such as the value of the brightness is 6436 nit in center of emission area and less than 5% in brightness uniformity. It shows the effective ways of designing backlight system using optical simulation method.

• Journal of the Korea Fashion and Costume Design Association
• /
• v.25 no.4
• /
• pp.1-11
• /
• 2023

The purpose of this study was to characterize the upper body shape of men in their 50s and 60s by analyzing direct measurement data. Sixty one direct measurement items were analyzed. Subjects (n = 752) were classified based on 5 factors into 4 body types. In order to acquire accurate upper body shape information by analyzing body type using the 8th Size Korea direct measurement data, body shapes were classified through factor and cluster analysis. As a result of the comparative analysis of the upper body measurements from the 5th to the 8th Size Korea measurement, it was found that waist circumference item tended to increase significantly from the 5th Size Korea measurements. The upper body type of middle aged males were classified using five factors: the trunk obesity factor, the trunk vertical factor, the width of the back shoulder, the vertical factor behind the back, and the length factor of the upper body. Middle-aged men were classified into four body types through cluster analysis. Type 1 is relatively short with big arms, Type 2 has wide shoulders and thin arms, and in Type 3, the upper body is relatively long. Type 4 is the most obese upper body.