• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2009.11a
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• pp.573-577
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• 2009

Dynamic behavior simulation of supersonic engine was performed and PI control algorithm was studied for the buzz control in the inlet and the thrust control. Firstly, required thrust was tracked according to the fuel flow control and then inlet pressure was regulated through the nozzle throat area control so that the buzz margin has the positive all the time. The control was performed according to the change of flight Mach number, altitude and angle of attack. The proportional gain and the integral gain for regulating the buzz margin was induced and simulated. In the results, it was confirmed and satisfied that control target in the operating area was changed the angle of attack from $0^{\circ}$ to $10^{\circ}$ at the flight Mach number of 2.1~3.0.

• The Journal of the Acoustical Society of Korea
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• v.37 no.5
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• pp.309-316
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• 2018

Various studies have been conducted to improve the BSR (Buzz, Squeak, Rattle) noise generated irregularly while the vehicle is running. In vehicle, When an external force such as vibration or force flows into the contact surface, BSR noise is generated at the contact surfaces of nearby components. In this paper, BSR conceptually explain the kind of noise generation mechanisms and the basic principles of generation, which have been proven by observing and improving noise phenomena in automobiles over the last 10 years. Through this, it is expected that researchers who want to study BSR related improvement research not only in automobiles but also in other industries, It will be able to understand the BSR phenomenon and provide a framework for thinking out improvement ideas and to carry out further research.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2007.11a
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• pp.617-621
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• 2007

Recent advances in automotive noise control engineering have reduced major sound sources in the vehicle, customers perceive Buzz, Squeak and Rattle (BSR) as one of important indicators of vehicle quality and durability. As the long-term goal, we expect to establish the integrated design cycle for the reduction of BSR noise in the early stage of development, which consist of design, prediction, and evaluation procedures. This is possible only with great bulk of experimental data for BSR noise. In this paper, BSR noise is experimentally identified for vehicle doors, which have been traditionally considered as one of main sources of BSR noise. Based on this result, we proposed method for the prevention of BSR noise in the vehicle doors.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.17 no.12
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• pp.1217-1222
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• 2007

With recent advance in automotive noise control engineering reducing major sound sources in the vehicle, customers perceive Buzz, Squeak and Rattle (BSR) as one of important indicators of vehicle quality and durability. As the long-term goal, we expect to establish the integrated design cycle for the reduction of the BSR noise in the early stage of vehicle development. which consist of design, prediction and evaluation procedures. This is possible only with great bulk of experimental data for BSR noise. In this paper, BSR noise is experimentally identified for vehicle doors, which have been traditionally considered as one of main sources of BSR noise. Based on this result, we proposed systematic method for the prevention of BSR noise in the vehicle doors.

• Proceedings of the Korean Society of Computer Information Conference
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• 2012.07a
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• pp.457-458
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• 2012

본 논문에서는 실시간 원격 수업(Real-Time Distance Education) 환경 하에서 학생들의 수업 집중 및 효율적인 교수를 위한 버즈학습(Buzz Learning)의 필요성을 제안한다. 이 학습법은 실시간 원격 수업에서 일어날 수 있는 집중력 저하 및 수업참가율 저조를 최소화하고, 학습자 간의 협동 및 상호작용을 향상시킨다. 또한 버즈법에 의한 그룹 편성 및 학습형태는 각 그룹에서 토의한 결과를 다시 전체가 모여 토의함으로써 소집단의 토의결과를 종합 정리하고 결론을 도출해 내는 집단 토의 형태를 띤다. 토의학습은 흔히 몇몇 학생의 경우 토의에 참가하지 않거나 또는 한 명이 독무대화하는 경향이 있는데 여기서는 그룹 전원이 토론에 적극 참여할 수 있게 한다. 본 논문에서는 실시간 원격 수업을 통하여 이뤄지는 실제 강의에 적용된 버즈 학습이 학생들의 수업참여도 및 학습 향상 면에서 우수함을 보여준다.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2011.04a
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• pp.132-135
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• 2011

A technology for buzz margin determination is suggested to obtain stable shock structure and high compression efficiency of supersonic intake. By using the shock equilibrium equation of supersonic intake, sensitivity equation of terminal shock position for free stream and back pressure is induced and disturbances are quantified through statistical approach. Numerical results show that the sensitivity of shock position for disturbances is proportional to Mach number and the back pressure is dominant for variance of terminal shock position.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• v.y2005m4
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• pp.334-342
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• 2005

A numerical analysis is performed using two dimensional axisymmetric RANS (Reynolds Averaged Navier-Stokes) equations system on the transition sequence of the Integrated Rocket Ramjet and the unsteady reacting flow-field in a ramjet combustor during unstable combustion. The mode transition of an axisymmetric ramjet is numerically simulated starting from the initial condition of the boost end phase of the entire ramjet. The unsteady reacting flow-field within combustor is computed for varying injection area. In calculation results of the transition, the terminal normal shock is occurred at the downstream of diffuser throat section and no notable combustor pressure oscillation is observed after certain time of the inlet port cover open. For the case of a small injection area at the same equivalence ratio, periodic pressure oscillation in the combustor leads to the terminal shock expulsion from the inlet and hence the buzz instability occurred.

• Proceedings of the KSME Conference
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• 2004.11a
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• pp.1494-1498
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• 2004

Transition sequence of rocket to ramjet was simulated numerically for a two-dimensional axisymmetric can-type ramjet engine. Multi-species preconditioned Navier-Stokes equations with $k-{\varepsilon}$ turbulence model and finite-rate chemistry model was employed. To calculate transition sequence, initial flow-field conditions for inlet diffuser with closed port-cover was computed first, and then that result was applied as initial conditions after port-cover opened. Terminal shock was developed as a result of increased pressure in a combustor due to combustion and ramjet operated at supercritical condition. For a smaller nozzle throat area, buzz instability was occurred. Strong pressure oscillations were observed as a result of forward and backward movement of terminal shock and those oscillations were not damped out.

• Journal of Information Technology Services
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• v.15 no.1
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• pp.97-111
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• 2016

In the creative economy paradigm, motivation of the opportunity based startup is a continuous concern to policy-makers. Recently, bigdata anlalytics challenge traditional methods by providing efficient ways to identify social trend and hidden issues in the public sector. In this study the authors introduce a case study using social bigdata analytics for conducting policy analysis. A semantic network analysis was employed using textual data from social media including online news, blog, and private bulletin board which create buzz on the startup business. Results indicates that each media has been forming different discourses regarding government's policy on the startup business. Furthermore, semantic network structures from private bulletin board reveal unexpected social burden that hiders opening a startup, which has not been found in the traditional survey nor experts interview. Based on these results, the authors found the feasibility of using social bigdata analysis for policy-making. Methodological and practical implications are discussed.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2014.10a
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• pp.796-799
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• 2014

It is treated more seriously than ever as the customer requirements are becoming a high-quality and diversification. Among the various elements to affect customer's evaluation of automobile quality, BSR(buzz, squeak, rattle noise) are considered to be a mostly contributing factor. Rattle Noises in cockpit modules are one of the major concerns mentioned above. Recently, measurements of the BSR noise between the parts that make up the products from the perspective that the structural causes. For structures that make up material has not been any consideration of the BSR noise characteristics. The aim of this study is to clarify the characteristics of noise occurrence in vehicle cockpit module that consist of plastic material after measuring noise by rattle special testing instrument.