• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.26 no.7
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• pp.343-350
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• 2014

Regardless of the building design scenarios, evaluation of high-rise buildings required to have smoke-proof enclosures that are provided with a smoke management system. The goal of the smoke management system design is to make sure the pressure differentials at every story within the building fall within the allowable pressure range. If the minimum design pressure is not met, smoke may enter the stair. If the provided pressure is too great, it becomes difficult for occupants to open the doors, while attempting to egress. Ensuring that the pressure differential between the vestibule and the floor is within the prescribed range becomes challenging, due to natural effects on the building, such as the stack effect. In this research, smokeproof enclosure design scenarios were evaluated; and as a result, separation levels for compartmentation were deduced, in the balancing of pressurized-vestibule smoke control systems.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.25 no.9
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• pp.1272-1280
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• 2001

An experimental study has been conducted to elucidate the resonance of natural convection in a side-heated square enclosure having a mechanically oscillating bottom wall. Under consideration is the impact of the imposed oscillating frequency, amplitude and the system Rayleigh number on the fluctuation of air temperatures. The experimental results show that the magnitude of the fluctuation of air temperature is substantially augmented at a specific forcing frequency of the oscillating bottom wall. The resonant frequency is increased with the increase of the Rayleigh number and it is little affected by the amplitude of the oscillating wall. It is also found that the resonant frequency is relevant to the Brunt- V$\"{a}$iS$\"{a}$l$\"{a}$ frequency which represents the stratification degree of the system.

• 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.

• Journal of The Korean Society For Urban Railway
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• v.6 no.4
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• pp.427-436
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• 2018

HADAX is a serial communication converter of train control computer. It is connected with various signal equipments such as wayside signal equipments, station signal equipments, train control computers, and transmits control information and signal condition information for train control. And transmits information to several electronic interlocking devices through a splitter interface. Since HADAX interfaces with many signaling devices through serial communication, frequent communication connection faults necessitate improvement of performance such as dual system configuration, integration of external splitter, and multi-channelization of communication card. The improved HADAX device should have compatibility with the dimensions of existing enclosure and enclosure, and verify the performance of dual system and splitter integration. Therefore, we verified the performance of HADAX through the route control test, dual system test, and multi-channel communication test with splitter integrated connection by connecting with the existing signal equipment.

• Nuclear Engineering and Technology
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• v.44 no.3
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• pp.283-296
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• 2012

The natural convection in a horizontal enclosure heated from the bottom wall, cooled at the top wall, and having a square adiabatic body in the center is studied. Three different Prandtl numbers (0.01, 0.7 and 7) are considered for the investigation of the effect of the Prandtl number on natural convection. Adiabatic boundary conditions are employed for the side walls. A two-dimensional solution for unsteady natural convection is obtained, using an accurate and efficient Chebyshev spectral methodology for different Rayleigh numbers varying over the range of $10_3$ to $10_6$. It had been experimentally reported that the heat transfer mode becomes oscillatory when Pr is out of a specific Pr band beyond the critical Ra. In this study, we reproduced this phenomenon numerically. It was found that when Ra=$10_6$, only the case for intermediate Pr (=0.7) reached a non-changing steady state and the low and high Pr number cases (Pr=0.01 and 7) showed a periodically oscillatory fashion hydrodynamically and thermally. The variation of time- and surface-averaged Nusselt numbers on the hot and cold walls for different Rayleigh numbers and Prandtl numbers are presented to show the overall heat transfer characteristics in the system. Further, the isotherms and streamline distributions are presented in detail to compare the physics related to their thermal behavior.

• Journal of Korean Society of Occupational and Environmental Hygiene
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• v.7 no.2
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• pp.171-180
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• 1997

The objectives of this study were both 10 discuss the sampling method for airborne metalworking fluids(MWF)' mist and 10 suggest measures to minimize worker's exposure to carcinogen contained in metalworking fluids. In order to measure airborne MWF mist, it seems to be appropriate to use NIOSH Method #0500(filler weight) rather than NIOSH Method # 5026(analysis by FTIR). Because MWF mist on PVC filter evaporated and migrated during sampling, worker's exposure to MWF could be underestimated. So, when evaluating worker's exposure to MWF mist, other environmental conditions also must be considered. Enclosure and local exhaust ventilation system seems to he the most effective measure and must be constructed with process facility. In order to control worker exposure to carcinogens contained in MWF, distillation type and condition for crude oil, PAH concentration in MWF, and viscosity index of MWF must legally be described.

• Journal of Electrical Engineering and Technology
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• v.5 no.4
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• pp.631-636
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• 2010

Gas-insulated transmission lines (GITL) are valued as technological solutions in hydro-power stations due to their enormous power handling capabilities. The performance of GITL is a function of the size of metallic particles inside the gas-insulated chamber. Electrostatic field (E-field) enhancement is a common phenomenon in gas-insulated lines due to these metallic particles. In this study, the E-field enhancement factor is calculated by considering metallic particles at various locations in the gas-insulated line/bus section, such as high-tension (HT) conductor, high-voltage shields, support insulator, and inner surface of grounded enclosure. For this purpose, a two-dimensional model based on finite element (FE) method is developed. The length of the metallic particle is in the range of 1 to 10 mm while the diameter is between 1 to 3 mm. E-field enhancement is also computed for various particle configurations of the gas-insulated system, with focus on dielectric coating made of epoxy on HT conductor and inner surface of grounded enclosure.

• Journal of computational fluids engineering
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• v.16 no.3
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• pp.29-36
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• 2011

The natural convection in a horizontal enclosure heated from the bottom wall, cooled at the top wall, and having a square adiabatic body at its centered area was studied. Three different Prandtl numbers (0.01, 0.7 and 7) were considered for an effect of the Prandtl number on natural convection. A two-dimensional solution for unsteady natural convection was obtained, using Chebyshev spectral methodology for different Rayleigh numbers varying over the range of $10^4$ to $10^6$. It had been experimentally and numerically reported [1,2] that the heat transfer mode becomes oscillatory when Pr is out of a specific Pr band beyond the critical Ra. In this study, we reproduced this phenomenon numerically. The variation of time- and surface-averaged Nusselt numbers on the hot and cold walls for different Rayleigh numbers and Prandtl numbers was presented to show the overall heat transfer characteristics in the system. And also, the isotherms and streamline distributions were presented in detail to compare the physics related to their thermal behavior.

• Proceedings of the KSR Conference
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• 2005.11a
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• pp.964-968
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• 2005

The standardization of information communication is doing a Internal each other connection and each other characteristic stability operation security in objective. From the low-speed network of the subway operation beginning currently it changes with the superhigh speed digital information transmission communication service environment which is a quality service, the hazard which plans the quality improvement of the efficient communication service use which hits to here and passenger service the standardization of the technical standard which stands and the improvement which hits to an engineering standard and facility must come to accomplish. The facility which existing is been old or the enclosure communication equipments which are insufficient. it improves, establishment itexpands efficiently, like this facilities it is stabilized and it is economic and rationally use maintenance it manages with the plan for the inside and outside of the country information communication relation technical standard and engineering standard service feature improvement and future expandability and economical efficiency, the possibility of having a pliability in order to be, rational technical standard and standard it takes a triangular position, efficient characteristic security of information communication service there is a place objective which promises the rational development of course city railroad communication system with character. Function improvement of enclosure communication base equipment, against an improvement and standardization plan it described trom the prosecution which it sees.

• The Magazine of the Society of Air-Conditioning and Refrigerating Engineers of Korea
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• v.12 no.4
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• pp.264-274
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• 1983

Two-dimensional jet flows into a couple of confined rectangular enclosures such as an Ondol flue channel and their flow distributions were analyzed by numerical graphics : rectangular space in one enclosure is vacated and the other has 8 rectangular small posts. Both enclosures have a protruded inlet nozzle and on outlet on its center line. Steady state incompressible laminar viscous flow was assumed. The primitive forms of Navier-Stokes equations and continuity equation in a cartesian coordinate system were solved numerically by the Marker and Cell method for Reynolds numbers of 5, 10, 20, 30 and 40. From the numerical graphics it was found that the flow regions in both enclosures were devided into tow parts ; one part was the jet flow localized in a narrow center region of the enclosure and the other part was the very slow recirculating flow occupying the rest of the flow region in the enclosures. However there were a little differences in the shapes of jet flow in both enclosures for Reynolds numbers of 5 and 10 and also in the shapes of recirculating flows in both enclosures for all Reynolds number. Also it was found that waving flow appeared right before the outlet at Reynolds number of 20 and more.