• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.12 no.7
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• pp.520-526
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• 2002

Identification of noose sources, their locations and strengths, has been taken great attention. The methods that can identify noise sources normally assume that noise sources are located in a free field. However, the sound in a reverberant field consists of that coming directly from the source plus sound reflected or scattered by the walls or objects in the field. In contrast to the exterior sound field. reflections are added to sound field. Therefore, we haute to consider the reverberation effect on the source identification method. The main objective of this paper is to identify noise source in the reverberant field. At fist, we try to identify noise sources in a rigid wall emc;psire using the beamforming method. In many cases of practical interest, the wall has admittance so that random reflections occur in an enclosure. In this paper, we assumed the complex reverberant field in the enclosure to be the sum of plane caves with random Incidence and magnitude. Then we try to explain effects of reverberant field at interior source identification.

• Ocean and Polar Research
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• v.30 no.4
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• pp.475-484
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• 2008

The word 'Saemangeum' indicates an estuarine tidal flat in the southwestern part of the Korean peninsula. The Saemangeum Reclamation Project was launched as a national project in 1991 to reclaim a large coastal area of $401\;km^2$ by constructing a 33-km long dyke. The final dyke enclosure in April 2006 has transformed the tidal flat into lake and land. An integrated oceanographic study has been conducted since 2002 as a part of the Government Action Plan to monitor and assess changes in the marine environment. Prior to the dyke enclosure, the coastal environment in the Saemangeum was a complex system governed by tidal motion, estuarine processes, and coastal circulation of the Yellow Sea. The dyke construction has radically changed not only the estuarine tidal system inside the dyke, but also the coastal marine environment outside the dyke. Post to the dyke enclosure, subsequent changes such as red tide, hypoxia, and coastal erosion/deposition occur successively. Red tides appear almost the year round in the inner area. Even under the condition that the sluice gates are fully open, the water quality does not improve as much as the developers would expect, mainly due to the critical reduction of the hydrodynamic stirring power. We will introduce details of our monitoring program and significant changes in the Saemangeum marine environment, based on observations and model results.

• Transactions of the Korean Society of Mechanical Engineers
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• v.17 no.5
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• pp.1054-1065
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• 1993

A computer simulation is performed on the effectiveness of the active minimization of harmonically excited enclosed sound fields for producing global reduction in the amplitude of the pressure fluctuations. In this study for the appreciable reductions in total time averaged acoustic potential energy, $E_{pp}$, the transducer location strategies for three dimensional active noise control is presented based on a state space modal which approximates the closed acoustic field.In this study, the above theoretical basis is used to investigate the application of active control to sound fields of low modal density. By the used of room-like 3-dimensional rectangular enclosure it is demonstrated that the reductions in $E_{pp}$ can be achieved by using a single secondary source, provided that the source is placed within the half a wavelength from the primary source and placed away from nodal line of the sound field. Concerning the reductions in $E_{pp}$ by minimzing the pressure in sound fields by the use of 3-dimensional rectangular enclosure, the effects of the number of sensors and the locations of these sensors are investigated. When a few modes dominate the response it is found that if only a limited number of sensors are located away from nodal line and located at the pressure maxima of the sound field such as at each corner of a rectangular enclosure.

• Architectural research
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• v.15 no.1
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• pp.9-15
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• 2013

Effects of physical attributes of workstation enclosures on the performance of office workers with different difficult levels of office tasks and moods are presented. Performance scores in complex tasks were expected to increase with greater workstation enclosures while those in simple tasks would be the same. Mood ratings were expected to be higher in lower workstation enclosures. Performance of 102 college students on ambient office sounds (45 dBA) with office tasks were measured for 100 minutes under three different workplace enclosures: (1) four foot partitions on two sides; (2) six foot partitions on three sides; and (3) a fully enclosed workstation with eight foot partitions. The tasks were to memorize a paragraph with 130 words (complex task) and to search phone numbers (simple task). The complex task performance in the fully enclosed workstation was increased compared to that in the workstation with four foot partitions (p < 0.001) and to that in the workstation with six foot partitions (p < 0.05). However, occupants in the fully enclosed workstation with office sounds without speech generally gave higher mood ratings. It indicates that closed individual offices may offer important contributions to collaborative work as well as individual productivity. These findings would help design community revise open plan design to increase collaboration among office workers.

• Journal of the Korean Institute of Rural Architecture
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• v.12 no.3
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• pp.11-18
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• 2010

This study tries to view the social and public roles of roads in urban structure in a renewed way, focusing on NakAn-Eupsung, which was a spontaneous settlement, not a designed city, of the many traditional villages. The most valuable meaning the alleys of traditional villages give us is the community of cooperation. Thus, this study tries to examine the features of the community in three major ways happening on the alleys of NakAn-Eupsung in three major ways. First, the features according to regional community; second, the features by social community; third, the features according to public community. Through this, we can understand the features of alleys within the building structure of traditional villages, and also we can have a chance to grasp the image of 'togetherness-of-the-public', long lost on contemporary alleys. In order to realize the ideal of sustainable residence, the techniques of housing complex project are continually being developed, and recently it is not hard to come across the flow of planning techniques taking especially community into consideration. At this point of time, it seems that various kinds of communities being made up on roads of traditional villages can present new directions and models to contemporary housing complex formation.

• Composites Research
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• v.19 no.3
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• pp.1-6
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• 2006

As the structures of the high performance electronic equipments and devices recently become more complex, the electromagnetic interference (EMI) and compatibility (EMC) have been very essential for commercial and military purposes. Thus, sensitive electrical devices and densely packed systems need to be protected from electromagnetic wave. In this research, glass fabric/epoxy composites containing conductive multi-walled carbon nanotube (MWNT) and carbon fiber/epoxy composites as electrical shielding materials were fabricated and electrical properties of the composites were measured. The concerning frequency band is from 300 MHz to 1 GHz. The performances of composite shielding enclosures were predicted using electromagnetic wave 3-D simulation tool, CST Microwave Studio. The shielding enclosure made of carbon fiber/epoxy composites were fabricated and the shielding effectiveness (SE) was measured in the anechoic chamber.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.22 no.3
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• pp.360-372
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• 1998

This study deals with the interaction between buoyancy-induced convection and externally imposed excitation in the form of harmonic rocking and the effect of the interaction upon heat transfer in low-Pr liquids. A wide array of system responses are discussed using the spectral collocation numerical technique. The superposition of buoyancy and Coriolis forces leads to complex fluid flow and heat transfer. The transition to chaotic convection is accelerated, and heat transfer rates are reduced as the enclosure is excited at the fundamental frequency of oscillation associated with the pure buoyancy-driven case. Average heat transfer rates are correlated for Pr=0.02 and 0.03. The heat transfer is affected more in the Pr=0.03 liquid than the case of Pr=0.02.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2003.05a
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• pp.1152-1156
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• 2003

Hard disk drives (HDD) in computer are used extensively as data storage capacity. The trend in the computer industry to produce smaller disk drives rotating at higher speeds requires an improved understanding of fluid motion in the space between disks. PIV measurement was used fer the unsteady flow between the center pair of four disks of four times larger than common radius of HDD disk at several rpm in a fixed cylindrical enclosure. The boundary between inner region and outer region is detected using PIV measurement and the number of dominant vortices s determined clearly. Tip vortices generated by an obstruction with actual-like configuration can be found at inner region. Oscillating flow from the obstruction appears at outer region with complex flow pattern.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2000.11a
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• pp.403-408
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• 2000

An acoustic field in a 3 dimensional enclosure is caused from interference between sound sources and the complex reflections from wall. Therefore, changing an acoustic property of wall such as admittance means generating another acoustic field. The purpose of this paper is utilizing the characteristic to make a quiet zone. First, this paper shows that the control material is essentially on the same road as active noise control(ANC). That is, we can consider the control material as the control source of ANC. However we cannot control the reflection strength of it. Second, through a numerical simulation, this paper shows that the position of the control material is an important variable of the control.

• Korean Institute of Interior Design Journal
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• v.17 no.1
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• pp.60-68
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• 2008

The aim of this study is to elucidate the meaning of "less is more" by examining the design process of the Farnsworth House and its spatial composition. In order to find out what constitutes "less" and "more", Mies' sketches and drawings were reviewed, and the vision of the architect and the owner, and the responses from the critics were studied. As a matter of fact, these seemingly contradictory concepts the "less" and the "more" are relative terms that complement each other. The concept of "less" describes an enclosure of space, fixed, inflexible and invariable space that leaves no room for change. On the other hand, the term "more" represents an openness of space, free, flexible, and variable space. Mies tried to minimize "less" element when designing the interior of the Farnsworth House, and he did so by eliminating columns and walls. On the contrary, by using only fixed core, he created a "more" space, where the effects of flexible and open qualities are maximized. However, duality and contradiction rising from glass external wall and portico in the Farnsworth House raise a critical issue in this "less is more" discourse. The role of these parts of the house is rather contradictory, and the glass wall and the portico hold both "less" and "more" elements. Unlike its relatively simple composition of space, the Farnsworth House encompasses many complex and contradictory ideas that leave room for wide scope of exploration and various interpretations.