• 한국음향학회:학술대회논문집
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• 한국음향학회 1984년도 추계학술발표회 논문집
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• pp.86-90
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• 1984

In this paper, a method measuring the reverberation time simultaneously on all of the audio frequency range was studied. The system developed in this study is composed of a pink noise generator, filter bank, and microcomputer with graphic display. In the experiment, reverbration time data measured by existing analog method and by the system were compared, and were almost same through the audio frequency. Based on the conclusion, the subject method has more convenience and accuracy with algorithm program development without existing problems and it was found out that this kind of method is widely available for many branches of room accoustics and architectual acoustics.

• 한국음향학회지
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• 제9권6호
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• pp.29-37
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• 1990

건축물이 갖게 될 음향학적 특성을 미리 예측함으로써 그 건축물의 음향학적 특성을 미리 예측 함으로써 그 건축물의 음향학적 요구에 맞는 설계를 수행할 수 있도록 하기 위해 computer simulation 방법을 개발하였다. 본 연구에서 사용된 simulation 방법은 영상음원법을 기초로 하였으며, simulation 에 의한 임펄스 응답이 유한한 시간 내로 제한되어 발생되어 오차를 줄이기 위한 방법이 제시되었다. 개발된 simulatio 방법으로 실내에서의 임펄스 응답, 잔향 곡선, early/rate energy ratio 등을 예측하고 실험 결과와 비교 하였으며, 실용적인 응용 가능성도 검토하였다.

• 한국소음진동공학회논문집
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• 제24권8호
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• pp.600-605
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• 2014

Two mufflers for a large-size sedan are suggested aiming (1) sporty-sound and (2) quiet-sound as well as both satisfying low back-pressure and low manufacturing cost. Transmission loss prediction considering heat and flow may increase the accuracy and reduce the development cost in muffler design; thus, GT-power prediction considering heat, flow, and acoustics is utilized. By understanding the fundamentals of flow-acoustic theory in small orifice(hole), an effective muffler design concept is proposed. Vehicle tests show the consistence with predictions for sound; also a back-pressure test bench confirms the advantage in pressure drop for both suggested mufflers. Those suggested mufflers also have advantages in manufacturing cost due to simplicity of the design.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2007년도 춘계학술대회논문집
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• pp.618-622
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• 2007

Recently, in accordance with elevation of the consciousness level of citizens, the desire for cultural life is on increasing, and according to this trend, it is the real fact that the demand of the Grand Performance Hall where various cultural events can be performed, is also on increasing. However, since the Grand Performance Hall in view of its distinctiveness, is required of the repletion or abundance of sound, it could be said that the sufficient examination and planning about this are indispensable from the designing stage. On this viewpoint, this Study has intended to design the performance hall that maintains the optimized acoustic capacity through an acoustic simulation for the object of the grand performance hall on the step of construction. After completion of the construction for Grand Performance Hall hereafter, if compare the data analyzed in such way with the actually measured acoustic performance, it is considered that the more optimized architectural acoustic design could be achieved.

• 대한기계학회논문집B
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• 제40권9호
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• pp.613-620
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• 2016

유체의 전도율(conductivity)이 전자기유량계의 특성에 미치는 영향을 평가하기 위해 소형 전자기 유량계를 설계 제작하였다. 유량계의 측정관(measuring tube)은 $4mm{\times}3mm$의 직사각형 단면을 가지며 길이는 9 mm이다. 전극은 직경이 1.5 mm인 점전극과 단면이 $2mm{\times}3mm$인 면전극으로 설계하였다. 코일의 열 발생에 영향을 미치는 자화주파수, 회전수 및 굵기를 변화시키면서 최적값을 찾았다. 최적화된 측정관은 자속밀도(magnetic flux density) 0.04 T (400 gauss)를 발생시키며 안정되고, 선형적인 유량신호를 얻을 수 있었다. 유량계를 특성을 평가하기 위해 중량식 유량계 교정 장치를 제작하였다. 유동율 범위는 최대 $1.17{\times}10^{-5}m^3/s$(700 cc/min)이며 ISO규격에 따라 유동량 결정의 불확도를 평가하였으며 크기는 0.06 % 이내이었다. 유체의 전도율은 $3-11{\mu}S/cm$ 사이에서 조절하였다.

• 한국주거학회논문집
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• 제19권4호
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• pp.49-57
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• 2008

The case study for this research is a middle school music room located in Iksan City, Korea. Although the room is used for teaching music, indiscreet sound-absorbing materials were applied within the space. Accordingly, a number of difficulties have been experienced when using the room. During a music lesson, the sound-volume is inadequate for music appreciation, while the music performance has an arid sound due to an insufficient echo. In order to control the obstructive factors resulting from a short Reverberation Time, the acoustic factor is optimized in this study by using an Acoustic Simulation, following an arrangement of Acoustic Design. A Psycho-acoustics Experiment was conducted using the Auralizational Technique, whereby the Virtual Acoustic Field can be experienced at the design stage.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2002년도 춘계학술대회논문집
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• pp.796-801
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• 2002

The goal of this research is the shape design of the valve using a computer simulation. For an analysis a basic mathematical model describing compression cycle is considered as consisting of five sets of coupled equations. These are the volume equation (kinematics), valve dynamic equation (dynamics), ideal gas equation (thermodynamics), Bernoulli equation (fluid dynamics), and dynamic equation of fluid particle based on Helmholtz equation (acoustics). Valve motion is made by the superposition of free vibration modes obtained by the finite element method. That is, the eigenvalues and eigenvectors are the sufficient modeling factors fur the valve in the simulation program. Thus, to design a shape of the valve, shape design sensitivity through chain-ruled derivatives is considered from two sensitivity coefficients, one is the design sensitivity of the capability of compressor with respect to the eigenvalues of the valve, and the other is the design sensitivity of the eigenvalue with respect to the shape change of the valve. In this research, the continuum design sensitivity analysis concepts are used for the latter.

• KIEAE Journal
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• 제10권6호
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• pp.105-114
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• 2010

As children are known to touch and chew everything, green cleaning procedures are an important step in preventing children from ingesting harmful toxins. The objectives of this study are to develop a new, self-evaluation checklist and to suggest design recommendations which comply with easy, adaptable, economical ways to improve the eco-friendly indoor environment of Korean childcare facilities. The information compiled during this study was collected through literature review and internet surveys1) from July, 2009 to February, 2010. The results of this study show that the current Korean childcare accreditation system and practices emphasize clean building interiors, policies for sanitation and cleanliness, and control of humidity and lighting. On the other hand, the information provided by green-building rating systems from GBCC, LEED, and GBTool offers additional and comparative details regarding indoor environment quality and standards regarding the IAQ performance and management plan, ventilation and thermal comfort systems, views from windows, acoustics, and lighting. In conclusion, this document provides an appropriate and easy-to-follow, self-evaluation checklist composed of eight criteria and 51 practical items. This study also provides the design recommendations composed of 27 practical ideas focusing on interior elements. Both the checklist and design recommendations I have suggested can be a post-occupancy tool for evaluating eco-healthy facility standards as well as tips for continuing to maintain eco-healthy childcare facilities.

• 한국실내디자인학회논문집
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• 제13권3호
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• pp.112-119
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• 2004

The purpose of this study is to grasp musical expression in the Monastery of La Tourette, an architectural work produced by an architect, Le Corbusier and a musician, Iannis Xenakis based on a musical piece, Metastasis. The results of the study on musical expression in the Monastery of La Tourette, which was done through analysis of correlation in expression between architecture and music, and spatial characteristics of this monastery, are as follows: First, in modern architecture and music, the expression of the space-time continuum concept is emphasized. Second, the architectural characteristics in this monastery that constitute musical expression are the Modular, confliction and fluidity in composition, plastic (acoustic) shape and symbolic shape. Third, these architectural characteristics are found to be expressed as counterpoint, alteration, temporality, acoustics and canon of music.

• Journal of Mechanical Science and Technology
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• 제18권2호
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• pp.272-285
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• 2004

The losses at off-design points from a compressor cascade occur due to the deviation from a design incidence angle at the inlet of the cascade. The self-noise from the blade cascade at off-design points comes from a separated boundary layer and vortex sheddings. If the incidence angle to the cascade increases, stalling in blades may occur and the noise level increases significantly. This study applied Large-Eddy Simulations (LES) using deductive and deductive dynamic SGS models to low Mach-number, turbulent flow with each incidence angle to the cascade ranging from -40$^{\circ}$ to +20$^{\circ}$ and compared numerical predictions with measured data. It was observed that the oscillating separation bubbles attached to the suction surface do not modify wake flows dynamically for cases of negative incidence angles. However, an incidence angle greater than 8$^{\circ}$ caused a separated vortex near the leading edge to be shed downstream and created stalling. The computed performance parameters such as drag coefficient and total pressure loss coefficient showed good agreement with experimental results. Noise from the cascade of the compressor is summarized as sound generated by a structure interacting with unsteady, turbulent flows. The hybrid method using acoustic analogy was observed to closely predict the measured overall sound powers and directivity patterns at design and off-design points of blade cascade.