• Proceedings of the SAREK Conference
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• 2008.06a
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• pp.255-262
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• 2008

The simulation of refrigeration cycle is important since the experimental approach is too costly and time-consuming. The present simulation focuses on the effect of capillary tube-suction line heat exchangers (CT-SLHX), which are widely used in small vapor compression refrigeration systems. The simulation of steady states is based on fundamental conservation equations of mass and energy. These equations are solved simultaneously through iterative process. The non-adiabatic capillary tube model is based on homogeneous two-phase model. This model is used to understand the refrigerant flow behavior inside the non-adiabatic capillary tubes. The simulation results show that both of the location and length of heat exchange section influence the coefficient of performance (COP). These results can be used in either design calculation of capillary tube length for refrigeration cycle or effect of suction line heat exchanging on refrigeration cycle.

• IEIE Transactions on Smart Processing and Computing
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• v.2 no.4
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• pp.248-254
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• 2013

The size and power consumption of digital circuits including the dimming circuit part will increase for high-performance solid state lighting (SSL) systems in the future. This study examined the low-power consumption of adiabatic dynamic CMOS logic (ADCL) due to the principles of adiabatic charging. Furthermore, the designed low-power ADCL digital pulse width modulation (PWM) was optimized for SSL dimming systems. For this purpose, an ADCL digital 3-bit PWM was optimized in two steps. In the first step, the architecture of the ADCL digital 3-bit PWM was miniaturized. In the second step, the clock cut-off circuit was designed and added to the ADCL PWM. As a result, compared to the original configuration, 60 transistors and 15 capacitors of ADCL digital 3-bit PWM were reduced for miniaturization. Moreover, the clock cut-off circuit, which controls wake-up and sleep mode of ADCL D-FFs, was designed. The power consumption of an optimized ADCL digital PWM for all bit patterns decreased by 54 %.

• Progress in Superconductivity and Cryogenics
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• v.6 no.1
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• pp.53-58
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• 2004

A Miniature inertance pulse tube refrigerator was designed and tested with a 10 W compressor. Erperiments were carried out for different pulse tube length and inertance tube length. An adiabatic model which considered the pressure drop in the regenerator was used to analyze the performance of the pulse tube refrigerator. Among various design parameters which should be optimized, the pulse tube length and the inertance tube length were optimized. PdV work and several different loss mechanism were included in the analysis to simulate more accurately the physical phenomena in the pulse tube refrigerator. Nevertheless, the simulation program could not completely predict the porformance of the refrigerator. The possible reason for the difference of the optimal point between the simulation and the experiment was explained.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.15 no.9
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• pp.744-750
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• 2003

The performance of adiabatic capillary tubes are measured to provide the database for a generalized correlation. Test conditions and capillary tube geometries are selected to cover a wide range typically observed in air-conditioning and heat pump applications. Based on extensive experimental data for R22, R290, and R407C measured in this study, a generalized correlation for refrigerant flow rate in adiabatic capillary tubes is developed by implementing dimensionless parameters for tube inlet conditions, capillary tube geometry, and refrigerant properties. The correlation yields good agreement with the present data for R22, R290, and R407C with average and standard deviations of 0.9% and 5.0%, respectively. In addition, approximately 97% of the data for Rl2, R134a, R152a, R410A, and R600a obtained in the open literature are correlated within a relative deviation of $\pm$ 15%.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2013.11a
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• pp.56-57
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• 2013

In this study, in regard to concrete considering variety of admixture content rate, we evaluated property of adiabatic temperature rise. By setting up high temperature history, we evaluated effect to compression strength property of high strength concrete by early high temperature history. As a result, early high temperature history accelerated Hydration reaction of cement and contribute early strength development but it didn't accomplish performance objective in long-term aged.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2021.05a
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• pp.114-115
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• 2021

The research team conducted a series of studies to use CGS as fine aggregate for concrete. In this paper, through the adiabatic temperature rising test, CGS' hydration heating performance and its usability as a mass concrete hydration heating agent were reviewed. According to the analysis, the maximum temperature of the mix of OPC 100 was 53.7℃, and the temperature of CGS 50% was 45.2℃, which was 8.5℃ lower than the OPC 100.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.25 no.8
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• pp.1122-1130
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• 2001

Film cooling performance from two rows of holes with opposite orientation angles is evaluated in terms of heat flux ratio. The film cooling hole has a fixed inclination angle of 35°and orientation angle of 45°for the downstream row and -45°for the upstream row. Four film cooling hole arrangements including inline and staggered configurations are investigated. The blowing ratio studied was 1.0. Boundary layer temperature distributions are measured to investigate injectant behaviors and mixing characteristics. Detailed distributions of the adiabatic film cooling effectiveness and the heat transfer coefficient are measured using TLC(Thermochromic Liquid Crystal). For the inline configuration, there forms a downwash flow at the downstream hole exit to make the injectant well attach to the wall, which gives high adiabatic film cooling effectiveness and heat transfer coefficient. The evaluation of heat flux ratio shows that the inline configuration gives better film cooling performance with the help of the downwash flow at the downstream hole exits.

• Journal of the Korea Institute of Military Science and Technology
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• v.7 no.4 s.19
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• pp.100-106
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• 2004

The effects of adiabatic flame temperature and mass flux on deuterium fluoride(DF) chemical laser performance were investigated. The power flux and specific power, which are important parameters containing the information of scaling effects of laser device magnitude, and chemical efficiency were selected as a judging parameter of DF laser performance. For the specific power, it was decreased by the increase of power flux of DF laser. Higher the adiabatic flame temperature of atomic fluorine generator, higher the chemical efficiency of DF laser was changed. It seems that the mass flux effect on the chemical efficiency is not remarkable.

• The KSFM Journal of Fluid Machinery
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• v.13 no.2
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• pp.24-29
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• 2010

This paper presents a study on the performance of NASA Rotor 37 with the casing grooves based on three-dimensional numerical analysis. Reynolds-averaged Navier-Stokes equations are solved on a hexahedral grid with the shear stress transport model as a turbulence closure model. The governing equations are discretized by a finite volume method. The validation of the numerical results is performed through experimental data for the total pressure ratio and the adiabatic efficiency. The investigation for an axial compressor with a smooth casing and the casing grooves is carried out to compare the performance parameters, for example, surge margin and efficiency, etc. The surge margin is improved in the case of the casing grooves while remarkable improvement of the efficiency is not produced. The result shows that the casing groove is beneficial to expand the operating range of NASA Rotor 37.

• Journal of Korean Tunnelling and Underground Space Association
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• v.11 no.1
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• pp.37-45
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• 2009

In this study, experiments of development and application of 50 MPa high-performance concrete are performed for large dimensional tunnel linings. In order to produce 50MPa high-performance concrete, eight optimal mixtures replacing with fly ash and ground granulated blast furnace slag up to 50 percent of type I Portland cement were selected then tests for mechanical properties and simple adiabatic temperature rise tests were carried out. And in order to assess the quantitative characteristics of heat of hydrations of developed mixtures, three mixtures that the type I Portland cement (OPC) and each one mixture of binary and ternary mixtures (BS30, F15S35) were reselected, then the adiabatic temperature rise tests and mock-up tests were performed. Consequently, the comparisons between the results of mock-up tests and finite element analysis can be enhanced the reliability of analyzing routines of thermal behaviours of the developed high-performance concrete.