• Journal of the Korean Society of Visualization
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• v.17 no.2
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• pp.39-47
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• 2019

Impingement cooling utilizing synthetic jets is emerging as a popular cooling technique because of its high local cooling efficiency. The interaction between the vortex structure of the synthetic jet and the surface is crucial in understanding the mechanism of this technique. In this study, the impinging vortex structure and its advection are investigated by experiments with jet-to-surface spacing $2{\leq}H/D{\leq}7$, and synthetic jet Reynolds number $5120{\leq}Re{\leq}9050$. Using phase-locked particle image velocimetry, ensemble averaged (phase averaged) flow fields are obtained, and vortex identification and quantification techniques are applied. The shape, trajectory, and intensity change of the vortex are assessed. A sharp decline in the vortex intensity and the occurrence of a counter-rotating vortex at the impingement point are observed.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2010.10a
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• pp.431-432
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• 2010

• Proceedings of the KSME Conference
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• 2008.11b
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• pp.2137-2143
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• 2008

This paper investigates the plate loop heat pipe system with an evaporator mounted with fin-wick structure to dissipate effectively the heat generated by the electronic components. The heat transfer formulation is modeled and predicted through thermal resistance analysis of the fin-wick structure in the evaporator. The experimental approach measures the thermal resistances and the operating characteristics. These results gathered in this investigation have been used to the objective of the information to improve the LHP system design so as to apply as the future cooling devices of the electronic components.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.19 no.4
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• pp.328-332
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• 2007

A superconducting magnetic energy storage (SMES) system has shorter response time and longer life time, and is more economical, and environment-friendly than other uninterruptible power supply (UPS). A conduction cooling system is well answer for the high temperature superconductor (HTS) SMES system. Because the conduction cooling system is simple, light and small structure. The purpose of this paper is to design and verify the effective conduction cooling system for the HTS SMES system. The analysis of heat loads in cryostat is performed. Thermal shield heat loads, temperatures of HTS coil surface and conduction Cu plate are estimated and measured.

• Proceedings of the Korea Concrete Institute Conference
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• 1999.04a
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• pp.299-304
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• 1999

Cracking of concrete is one of the main issues of structural design next to ensuring the load-bearing capacity. Thermal cracking is a recurring concern in the production of concrete structures in particular when large, massive structures are considered. Thremal stresses arise from the differential temperature distribution either within s sturcture or between newly cast sectons and adjoining older parts. There are many different methods of reducing thermal stresses. A method often used for reducing temperature within a structure, is to cool the inner core with embedded cooling pipes. In this study, finite element method is employed for thermal analysis of concrete structures. To calculate water temperature variation in pipe, the conservation of thermal energy in internal flow was adopted. The cooling effect of pipe cooling is studied with several factors like convective coefficient, water temperature, concrete heat characteristics

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.9 no.3
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• pp.364-375
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• 1997

The fundamental theory and technical approach to aid design and development of an automotive air-conditioning system are presented. The evaluation methods for transient cooling load transferred to a passenger compartment and simulation of automotive air-conditioning components are outlined. The structure of the computer program, the experiemntal correlations, and the simulation results are also included. The total cooling load of the white-colored car is reduced upto 5% for that of the black-colored car when the car is running. Using the infrared reflectance glass, we can also obtain 5% reduction of the total cooling load for the common glass.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2003.11a
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• pp.132-137
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• 2003

For the evaluation of acoustic noise of a DLP projector, vibration and sound characteristics of a DLP projector were studied. The acoustic noise of DLP projector could be classified into three categories, that is, the direct noise from a body of rotation, the air-bone noise generated from turbulence or vortex occurred during cooling process and the structural born noise produced by vibrating elements. Cooling fans and color filter wheel which rotates at 9000 rpm are main causes of acoustic noise induced in DLP projector. Since the structure of an optical module in a DLP projector can be excited by the excessive vibration of a color filter wheel, the structural design for anti-vibration should be considered. To make a reduction of overall acoustic noise, the anti-vibration design and the enclosing structure have been studied and applied to a color filter wheel.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.14 no.9 s.90
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• pp.861-867
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• 2004

For the evaluation of acoustic noise of a DLP projector, vibration and sound characteristics of a DLP projector were studied. The acoustic noise of DLP projector could be classified into three categories, that is, the direct noise from a body of rotation, the air-bone noise generated from turbulence or vortex occurred during cooling process and the structural born noise produced by vibrating elements. Cooling fans and color filter wheel which rotates at 9000 rpm are main causes of acoustic noise induced in DLP projector. Since the structure of an optical module in a DLP projector can be excited by the excessive vibration of a color filter wheel, the structural design for anti-vibration should be considered. To make a reduction of overall acoustic noise, the anti-vibration design and the enclosing structure have been studied and applied to a color filter wheel.

• Journal of the Microelectronics and Packaging Society
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• v.23 no.2
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• pp.73-78
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• 2016

An increase in the transistor density of integrated circuit devices leads to a very high increase in heat dissipation density, which causes a long-term reliability and various thermal problems in microelectronics. In this study, liquid cooling method was investigated using straight microchannels with various metal bumps. Microchannels were fabricated on Si wafer using deep reactive ion etching (DRIE), and Ag, Cu, or Cr/Au/Cu metal bumps were placed on Si wafer by a screen printing method. The surface temperature of liquid cooling structures with various metal bumps was measured by infrared (IR) microscopy. For liquid cooling with Cr/Au/Cu bumps, the surface temperature difference before and after liquid cooling was $45.2^{\circ}C$ and the power density drop was $2.8W/cm^2$ at $200^{\circ}C$ heating temperature.

• Journal of the Architectural Institute of Korea Structure & Construction
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• v.36 no.2
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• pp.175-180
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• 2020

The purpose of this study was to clarify precautions during the design and operation phases for energy reduction in a public office building. To check the operation status of the building, we measured the indoor temperature and humidity in the office space of the building installed central heating and cooling systems. And we analyzed these data and annual BEMS data. As a result, we found six problems related to decreasing system efficiency. Based on these, we presented the information to improve the efficiency of the system from the design and operation phase. Also, we present the need for a system to support the decision-making of operational managers in real-time for the energy efficiency of the building.