• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.27 no.8
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• pp.440-447
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• 2015

In the shipbuilding process, the confined work spaces of the ship are formed continuously; the ventilation method can therefore be limited to dilution ventilation due to the complex structure and limited opening of the confined space. Also, it is difficult to evaluate air-quality using measurement and an adequate ventilation method. CFD simulation methods are typically used in analyzing ventilation efficiency in these cases. In this study, a method is suggested to analyze the air quality of the complex enclosures in shipbuilding using CFD. Especially, among the conventional indices, the ventilation efficiency scales or indices, the supply air contribution (SVE4), and the age of the air (SVE3) (fit for the confined and complex enclosure) were applied.

• Solar Energy
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• v.17 no.3
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• pp.67-73
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• 1997

In order to development of a new wall structure type thermal diode for energy saving, the numerical studies have been performed for natural convection across an rectangular enclosure with the various lengthes of the heat source and sink plate. The governing equations for the two-dimensional, laminar, natural convection process in an enclosure are discretized by the control volume approach which insures the conservative characteristics to be satisfied in the calculation domain, and solved by a elliptic SIMPLE algorithm. The momentum and energy equations are coupled through the buoyancy term.

• Journal of the Korea Institute of Military Science and Technology
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• v.3 no.2
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• pp.204-212
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• 2000

The waste ammunitions have been accumulated in excessive amounts these days. This study focused on the problems related to the method of ammunition disposal which leads the explosion inside the enclosure structure and controls the effects of detonation. This study enables us to design a new type of explosive disposal facilities that would fit to our environments. And this study gives us the prototype design of the explosive disposal structure that are explored in this research and will give us a chance to develop a new type structure that have not been devised by Army, and also will be applicable to construct a civilian explosive disposal structure located in airports, harbors, and public facilities.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.12 no.5
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• pp.837-843
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• 2001

Conventional reverberation chamber has a rectangular structure including mode stirrers or mode-turned stirrers to obtain the field uniformity inside the chamber. This paper explained the way to improve the field uniformity in an asymmetric structure instead of conventional rectangular structure with right-angled planes. Two types of asymmetric structure were considered. One was an asymmetric reverberation chamber using Quadratic Residue Diffuser and the other was an asymmetric chamber with oblique enclosure including fixed Randomly Made Diffusers. The FDTD simulation method was used to analyze the field homogeneous characteristics of these asymmetric reverberation chambers.

• Journal of Forest and Environmental Science
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• v.37 no.4
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• pp.292-303
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• 2021

Studies that relate the structure of tropical regrowth vegetation to soil properties are generally lacking in the literature. This study proposes three indices for assessing the structural regeneration of secondary forests. They are: (1) the tree diameter class, (2) the plant life form and (3) the woody/herbaceous plants ratio indices. They were applied to assess the regeneration status of forest regrowth vegetation (aged 1-10 years), derived savanna regrowth vegetation in south western Nigeria, and to secondary forests in different stages of succession in Columbia and Venezuela, Bolivia, Mexico in South and Central America and semi-arid savanna in Ethiopia and seasonal deciduous forest successional stages in India. In all the cases, the indices increased with increasing age of regrowth vegetation and hence, with increasing structural complexity of regenerating vegetation. The tree diameter class index increased from 32.1% in a 9-year secondary forest to 69.0% in an 80-year-old secondary forest in Columbia and Venezuela and from 0.4% in a 1-year fallow to 20.9% in 10-year regrowth vegetation in southwestern Nigeria. In semi-arid savanna in northern Ethiopia, the woody/herbaceous plants ratio index increased from 18.1% in a 5-year protected grazing enclosure to 75.1% in 15-year protected enclosure, relative to the status of 20-year enclosure. The indices generally had correlations of 0.6-0.90 with species richness and Simpson's/Margalef's species diversity, implying that they are appropriate measures of ecosystem development over time. The proposed indices also had strong and positive correlations with soil organic carbon and nutrients. They are therefore, significant indicators of fertility status.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 1997.04a
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• pp.218-223
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• 1997

The technique used is the active structural acoutrol (ASAC)approach which involves controlling the acoustic response of a panel-cavity covpled system by applying oscillating force inputs in the form of prezoelectric actuators directly to the flexible panel. The linear quadratic Gaussian control scheme is used for attenuating nosie inside the rectangular enclosure causing by flexible wall vibration. Results indicated the application of control inputs to the radiating wall resukted in considerable noise reductions inside the cavity. Auso,the possibility of application to the more complicated fluid-structure coupled system is verified.

• Fire Science and Engineering
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• v.10 no.3
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• pp.41-50
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• 1996

In many of the developed countries, there have been continuous offers to observe and understand the fire phenomenon for the establishment of fire safety and the development of fire protection technology. In the past, full scale fire experiments have been conducted for the development of the construction technology and the design methods in order to secure the safety of the buildings and the people as well. This study aims at the statistics concerning the structural vulnerablity parts based on the full scale fire experiment in one of the apartment buildings that represents the average households in Korea, thereby acquring the experimental technology, and the basic data needed for the prediction of enclosure fire phenomenon which is critical for the establishment of evalution methods through simulation, and has also presents secured problems concerning the balcony structure and the window types that requires imediate improvement.

• Nuclear Engineering and Technology
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• v.21 no.3
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• pp.186-192
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• 1989

As a part of the design of the top end piece(TEP) for the 14$\times$14 reload fuel, various models of top end piece structure were analysed, using the ANSYS code, under fuel assembly shipping and handling load conditions. The 3-dimensional isoparametric elements were used in each model. By rearrangement of slots and holes on the adapter plate, without violating the design requirements, and also by changing the enclosure attachment method used on the adapter plate from pin joints to through-weld, the load carving capacity of the adapter plate was greatly strengthened. These concepts were adopted for the design of the 14$\times$14 reload fuel.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.32 no.1
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• pp.16-24
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• 2022

A computational study of combined thermal and solutal convection (double diffusive convection) in a sealed crystal growth reactor is presented, based on a two-dimensional numerical analysis of the nonlinear and strongly coupled partial differential equations and their associated boundary conditions. The average Nusselt numbers for the source regions are greater than those at the crystal regions for 9.73 × 10³ ≤ Gr_t ≤ 6.22 × 10⁵. The average Nusselt numbers for the source regions varies linearly and increases directly with the thermal Grashof number form 9.73 × 10³ ≤ Gr_t ≤ 6.22 × 10⁵ for aspect ratio, Ar (transport length-to-width) = 1 and 2. Additionally, the average Nusselt numbers for the crystal regions at Ar = 1 are much greater than those at Ar = 2. Also, the occurrence of one unicellular flow structure is caused by both the thermal and solutal convection, which is inherent during the physical vapor transport of Hg₂Br₂. When the aspect ratio of the enclosure increases, the fluid movement is hindered and results in the decrease of thermal buoyancy force.

• Proceedings of the KSME Conference
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• 2002.08a
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• pp.663-666
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• 2002

Hard disk drived (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. The distribution of pressure disturbance on disks has relation to flow structure. To investigate the flow structure, time-resolved hot-wire measurements of the circumferential velocity component were obtained for the flow between the center pair of four disks of common radius $R_2$ coretating at angular velocity ${\Omega}$ in a fixed cylindrical enclosure. Hot-wire supporter acts as an obstruction in this case. The effects of rotating speed and size of hot-wire supporter diameter between disks on the flow driven by disks were investigated. Velocity spectra at the fixed space were measured to obtain the structure of inner and outer region in flow field.