• Journal of the Korean Society for Aeronautical & Space Sciences
• /
• v.38 no.3
• /
• pp.274-279
• /
• 2010

The present work is to analyze the longitudinal static stability and the drop trajectory of fighter aircraft's external fuel tank, of which horizontal fin is modified as the 20% scale down size compared with the original one. The analytical results to the pitching stability of external fuel tank using a thin airfoil's aerodynamic force data show the corresponding tendency to results of wind tunnel experiment. Results of trajectory simulation by the 6 degree of freedom equations of motion, comparing with drop trajectories of wind tunnel experiment, are shown that aircraft's attitude affects strongly on horizontal movement but not on the vertical movement. Those results give the reliability to aircraft safety when the external fuel tank with the 20% reduced horizontal fins is released from aircraft based on the flight manual.

• The Journal of the Acoustical Society of Korea
• /
• v.21 no.3
• /
• pp.245-255
• /
• 2002

This thesis deals a method to deliver more realistic sound by cancelling the cross-talk which is inherent to the 5.1 channel speaker system. The acoustical model for cross-talk cancellation is the free field model. This model minimizes distortion of sound. I used the bark scale sound quality compensation which based on psycho-acoustic. For the surround channels, band-limited sound quality compensation is performed in the frequency domain. I also performed the sound quality assessment test on the traditional 2 channel stereo and 5.1 channel system. This test is performed in the test chamber which satisfies the ITU-R specifications. I uses the IACC (Inter-Aural Cross-Correlation) to determine the preferences of the amateur and the golden ear experts to asses the trans-aural filter. According to the result from the proposed method, I got more the 38 dB separation rates with the Dolby standard speaker array. The results on the diffusion by the subjective test with the experts shows 0.4 point increased then before.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
• /
• v.19 no.9
• /
• pp.978-984
• /
• 2008

In this paper, we propose a RFID metal tag antenna with a minimum by size of a metal surface to attach. This proposed tag antenna is a patch antenna which is able to stick on metal surface and designed for very slim structure ($119{\times}30{\times}1.6$ mm) antenna that is matched to a chip impedance. This has a loop coupling feeding and consists of a inner radiator and a outer radiator. The outer radiator activates the current to concentrate on the inner radiator regardless of metal size to attach. Also the tag antenna is designed by CST microwave tool and the performance is measured in the anechoic chamber. The optimum antenna has 3.77 % of the matching bandwidth($S_{11}<-10$ dB). The readable range of the tag antenna is about 2.9 m on metal(max. size $700{\times}700$ mm) and 5.5 m in free space according to the measurement results.

• International Commerce and Information Review
• /
• v.19 no.2
• /
• pp.25-44
• /
• 2017

Though electronic commerce has grown rapidly in international trade, there is no basic consensus for its concept and rule applied. So WTO has done practice of not imposing customs duties on digital contents and been researching overall on electronic commerce through Work Program while many countries of the world attempt to obtain their interests by stipulating chapter of electronic commerce in their FTAs. This paper has compared and analysed chapter of electronic commerce in all the FTAs which Korea has signed and enforced. Korea's FTA stipulates commonly no customs duties, the other chapter's priority when chapter of electronic commerce conflicts the other chapter, electronic authentication, protection of personal information and consumer protection. But it has weak consistency and framework as it has different provisions for the objects of electronic commerce respectively, reserves classification & applied rule for electronic commerce, stipulates differently on non discrimination treatment and so on. Korea should participate in the research of international organization including WTO and cope actively and elastically by analysing the provisions of electronic commerce of the other countries' FTA such as USA, EU, CHINA and so on.

• Korean Journal of Childcare and Education
• /
• v.5 no.2
• /
• pp.91-112
• /
• 2009

The purpose of this study was to analysis children's engagement behavior and teachers' linguistic behavior by type of group activity in kindergarten. The subjects were 45 children and 2 teachers of 5 years' class in 2 kindergarten. The data were collected by 16 times observation in general classrooms for 4 weeks to explore the children's engagement behavior and teachers' linguistic behavior. The results of this study are as follows: Firstly, the large group and structural activity from initiated teacher's plan. Secondly, children's watching and listening behavior was most frequently shown in academic large group activity. And children's active engagement behavior was most frequently shown in free play of peer group. Finally teachers explained and directed frequently in academic large group activity. And teacher praise and permission was frequently shown in free play of small group teacher-child interaction. Consequently, it is important to recognize the relationships between the activity type and children's engagement behavior in organized daily program for early child education.

• Journal of the Korean Institute of Intelligent Systems
• /
• v.16 no.4
• /
• pp.443-448
• /
• 2006

In this paper, a novel method is proposed for generating the low-power and stable walking trajectory of biped robots, and then a biped robot with 25 DOFs(degrees of freedom) is designed and implemented for the realization of the low-power walking trajectory generated by the proposed method. In our method, first a stable VPCG(vertically projected center of gravity) trajectory is generated, and then the trajectories of ankle and pelvis of a biped robot are planned to follow the preplanned stable VPCG trajectory, which produces a waking pattern without bending its knees and enables a biped robot to walk with less power consumption. On the other hand, a biped robot implemented in this paper has the mechanical structure of foot that enables a biped robot to support on the ground well, and the mechanical structure of pelvis that enables a biped robot to move flexibly. From results of the walking experiment and power consumption measurement, it was confirmed that the proposed method can generate the more stable and flexible trajectory with less power consumption compared with the existing methods which do not use the ankle of a biped robot.

• The Journal of the Korea institute of electronic communication sciences
• /
• v.6 no.1
• /
• pp.68-76
• /
• 2011

Today the new social and cultural area is generated by development of digital media and internet. Especially UCC is the new cultural area of this time, UCC is applicated and delivered the individual image and contents by digital equipment. This research tried to study the communication esthetics with the relation of a user. And it study about the function of the media communication, the cultural possibility, the value by art of UCC. From now I have not to see the UCC media technology the level of technical limit and we see it variously the level of cultural and artistic. I study the meaning of them and try the analysis. And I will study about the communication between the individual and the community. And I will study also the short aspect and the synthesize aspect of digital network, and how possible the realization of free culture. And I will analyse the meaning and system of UCC contents that product and copy today and then I will suggest that contribute the UCC culture development.

• KSCE Journal of Civil and Environmental Engineering Research
• /
• v.13 no.2
• /
• pp.61-71
• /
• 1993

The stress waves generated by the mechanical energies by impact or the chemical energies by the explosions are transmitted through medium. The wave propagation process through medium is a very complicated procedure due to the reflections and refractions of the waves at the free surfaces and interfaces. In this study the pressure independent Von-Mises model is employed for the wave propagation analysis in the layered systems. Governing equations of this study are conservation equations of momentum and mass in Lagrangian coordinate system which is fixed to the material. Due to the shock-front which violates the continuity assumptions inherent in the differential equations numerical artificial viscosity is used to spread the shock front over several computational zones. These equations are solved by Finite Difference Method with discretized time and space coordinates. The associate normality flow rule as a plastic theory is implemented to find the plastic strains.

• KSCE Journal of Civil and Environmental Engineering Research
• /
• v.14 no.5
• /
• pp.1033-1042
• /
• 1994

Dynamic behavior of flexible rectangular liquid containers is analyzed by a two-dimensional coupled boundary element-finite element method. The irrotational motion of inviscid and incompressible ideal fluid is modeled by boundary elements and the motion of structure by finite elements. A singularity free integral formulation is employed for the implementation of boundary element method. Coupling is performed by using compatibility and equilibrium conditions along the interface between the fluid and structure. The fluid-structure interaction effects are reflected into the coupled equation of motion as added fluid mass matrix and sloshing stiffness matrix. By solving the eigen-problem for the coupled equation of motion, natural frequencies and mode shapes of coupled system are obtained. The free surface sloshing motion and hydrodynamic pressure developed in a flexible rectangular container due to horizontal and vertical ground motions are computed in time domain.

• Transactions of the Korean Society of Mechanical Engineers A
• /
• v.34 no.6
• /
• pp.667-673
• /
• 2010

This paper proposes a control method based on a pseudo-impedance model to control the motion of biped robots walking on an uneven surface. The pseudo-impedance model simulates the action of the ankle of a foot landing on the ground when a human walks. When the foot is in contact with the ground, the human ankle goes through two different phases. In the first phase, the human exerts little or no effort and applies no torque on the ankle so that the orientation of the foot is effortlessly and passively adjusted with respect to the ground. In the second phase of landing, the ankle generates a significant amount of torque in order to rotate and move the main part of the human body forward and to support the weight of the human; this phase is called the weight acceptance phase. Computer simulations of a 12-DOF biped robot with a 6-DOF environment model were performed to determine the effectiveness of the proposed pseudo-impedance control. The simulation results show that stable locomotion can be achieved on an irregular surface by using the proposed model.