• Proceedings of the KSME Conference
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• 2003.11a
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• pp.798-803
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• 2003

The objective of the present study is to investigate the changes in the acoustic source characteristics and far-field noise propagation in an incompressible round jet at Re=10000 for single-frequency excitations using large eddy simulation and Lighthill acoustic analogy. We apply excitations at a frequency corresponding to the jet-column mode ($St_{D}=0.85$) or maximum growth rate in the shear layer ( $St_{\theta}=0.017$ ). The acoustic source derived from the Lighthill acoustic analogy is the second spatial derivative of the Reynolds stresses. In the case of $St_{D}=0.85$, vortex ring and large scale structures are dominant sources, whereas in the case of $St_{\theta}=0.017$, the main sources are located at an upstream position along the shear layer than in the uncontrolled case. Also, the far-field noise propagates along the axial direction due to excitation.

• Proceedings of the Korea Information Processing Society Conference
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• 2016.10a
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• pp.119-122
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• 2016

대표적인 네트워크 기반의 이동성 기법인 PMIPv6(Proxy Mobility IPv6)은 이동 단말에 대한 끊김 없는 서비스 지원이 가능하다. 하지만 PMIPv6 기법은 단말과 홈 에이전트 간 IP Tunnel을 생성해야 하며, 그에 따른 시그널링 비용이 발생하게 된다. 또한, 단말 이동에 따른 연속적인 서비스 지원만 고려할 뿐 이동 중 발생하는 패킷 손실은 고려하지 않는 문제점이 있다. 본 논문은 이러한 문제점을 해결하기 위해 SDN(Software Defined Networks)을 적용하였다. 데이터 플레인에서 Anchor 스위치를 선정하여 이동 전 위치의 단말로 전송되던 패킷을 이동한 위치의 단말로 Re-direction 함으로써 패킷 손실을 줄이기 위한 기법을 제안한다.

• 제어로봇시스템학회:학술대회논문집
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• 2000.10a
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• pp.16-16
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• 2000

This paper describes a new structure re create a pseudo Gaussian function network (PGFN). The activation function of hidden layer does not necessarily have to be symmetric with respect to center. To give the flexibility of the network, the deviation of pseudo Gaussian function is changed according to a direction of given input. This property helps that given function can be described effectively with a minimum number of center by PGFN, The distribution of deviation is represented by level set method and also the loaming of deviation is adjusted based on it. To demonstrate the performance of the proposed network, general problem of function estimation is treated here. The representation problem of continuous functions defined over two-dimensional input space is solved.

• Journal of Chest Surgery
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• v.12 no.3
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• pp.197-206
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• 1979

The most common abnormal relationship between the great arteries and ventricle is transposition of great arteries, among which complete D-transposition is a common and lethal malformation. Without appropriate treatment, the infant born with transposition of the great arteries rarely survives the first year of life. In contrast to the grim hopelessness of only a few years ago, modern aggressive palliative and corrective surgical interventions can provide such infants with considerable hope for adolescent and adult life. Up until this time, intraatrial baffle technique for re-direction of venous return, which was proposed by Mustard originally, has been successfully applied to infants and children in many foreign clinics with decreasing trend of the operative risk. In this report, we present one case of a 4 year-old girl having complete D-transposition of the great arteries with atrial septal defect, and reviewed the relevant literatures.

• International Journal of Aeronautical and Space Sciences
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• v.2 no.2
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• pp.28-38
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• 2001

A numerical method for the assessment and correction of tunnel wall interference effects on forced-oscillation testing is presented. The method is based on the wall pressure signature method using computed wall pressure distributions. The wall pressure field is computed using unsteady three-dimensional full Navier-Stokes solver for a 70-degree pitching delta wing in a wind tunnel. Approximately-factorized alternate direction implicit (AF-ADI) scheme is advanced in time by solving block tri-diagonal matrices. The algebraic Baldwin-Lomax turbulence, model is included to simulate the turbulent flow effect. Also, dual time sub-iteration with, local, time stepping is implemented to improve the convergence. The computed wall pressure field is then imposed as boundary conditions for Euler re-simulation to obtain the interference flow field. The static computation shows good agreement with experiments. The dynamic computation demonstrates reasonable physical phenomena with a good convergence history. The effects of the tunnel wall in upwash and blockage are analyzed using the computed interference flow field for several reduced frequencies and amplitudes. The corrected results by pressure signature method agree well with the results of free air conditions.

• Journal of Korea Society of Digital Industry and Information Management
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• v.5 no.4
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• pp.199-211
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• 2009

The purpose of this study is to elicit influential factors on accepting IPTV services and define the casual relationship between the factors, and "user satisfaction", "re-use intention", "stranger recommendation intention", in an attempt to provide useful guidelines to IPTV carriers, contents providers and equipment makers for their forming IPTV service models and marketing strategies. For this end, the theoretical background of this study has been brought from relevant literature, and theoretical study models have been established by logical reasoning of the interrelation among diverse components. Then, the established models have been analyzed by using statistical packages "SPSS(12.0), LISREL(8.72)". Finally theoretical and practical significance and future study direction have been suggested. To make sure of effective validity of IPTV service adoption models above, empirical studies should be made continuously. And then vertical and horizontal studies at a specific point would show ever-changing causal relationship, helping to promote financial outcome of relevant companies and organizations.

• Bulletin of the Korean Space Science Society
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• 2009.10a
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• pp.44.1-44.1
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• 2009

Identification of wave characteristics during current disruption events in the near-Earth geomagnetic tail region (~ 10 RE) is important to understand the substorm onset mechanism. In this paper, linear stability analysis in the ion-cyclotron grequency range, considering temperature anisotropy and cross-field flow is presented. It is found that the ion-cyclotron drift waves propagating in a quasi-perpendicular direction with respect to the ambient magnetic field are characterized by low frequencies ($\omega$ < $0.5{\Omega}ci$), while quasi-parallel waves have frequencies close to the ion-cyclotron frequency ($\omega{\sim}{\Omega}ci$). This finding is consistent with the observation by THEMIS spacecraft of a current disruption event in which a similar high- and low-frequency band structure is also present [A. T. Y. Lui, et al., J. Geophys. Res. 113, A00C06 (2008)]. It is also found that the quasi-perpendicular mode is excited by the ion cross-field flow.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.7 no.1
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• pp.81-88
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• 1995

Fully developed turbulent flow through three concentric annuli with both the rough inner and outer walls was experimentally investigated for a Reynolds number range Re=15,000-85,000. Measurements were made of the pressure drop, the positions of zero shear stress and maximum velocity, and the velocity distributions in annuli of radius ratios, ${\alpha}=0.26$, 0.4 and 0.56, respectively. The experimental results showed that the positions of zero shear streess and maximum velocity were only weakly dependent on the Reynolds number. It was also found that the position of zero shear stress was not coincident with that of maximum velocity. Furthmore, the former was influenced more sensitively than the latter on the square-ribbed roughness along the axial direction.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.25 no.12
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• pp.654-659
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• 2013

This paper presents a numerical optimization of louvered fins to enhance the JF factor in terms of the design parameters, including the fin pitch, the number of louvers, the louver angle, the fin thickness, and the re-direction louver length. We carried out a parametric study to select the three most important parameters affecting the JF factor, which were the fin pitch, number of louvers, and the louver angle. We optimally designed the louvered fin by using 3rd-order full factorial design, the kriging method, and a micro genetic algorithm. Consequently, the JF factor of the optimum model increased by 16% compared to that of the base model. Moreover, the optimum model reduced the pressure drop by 17% with a comparable heat transfer rate.

• Korean Journal of Computational Design and Engineering
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• v.3 no.1
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• pp.22-30
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• 1998

The deflection yoke (DY) controls the direction of the electron beam that falls on the screen of the television monitor. Its quality depends on the shape and density of coils wound around the DY coil separator. Winding frames are used to make these coils, and therefore, their shapes are essential in making quality coils. A reverse engineering(RE) is applied to create the 3D model of the winding frame. It considerably shortens the design verification time and shows the level of accuracy that is feasible in the production mode. The paper explains each step of the reverse engineering process in detail.