• Proceedings of the KSME Conference
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• 2001.06c
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• pp.224-228
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• 2001

This paper presents the analyzing method of golf shoes and shows design technique including air-cycled pump in the midsole. The golf shoes are analyzed by using the finite element method for the optimization in design by considering the configuration of midsole and outsole, which compose the golf shoes. Also the optimum size of air-cycled pump in the midsole is examined. Standard human pressure values for boundary conditions are adoped for the finite element analysis. The unknown constants of the strain energy function of Ogden type are observed in accordance with the axial tension test. By using the commercial FEM software for nonlinear analysis, MARC V7.3, the strains and the values of volume change for midsole and outsole are obtained, respectively. As a result, it can be concluded that these values in the midsole and the outsole are different depending on the characteristic of elastomer. More precise investigation about the assembly of two parts, which represent midsole and outsole, is under studying.

• The Magazine of the Society of Air-Conditioning and Refrigerating Engineers of Korea
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• v.17 no.6
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• pp.696-707
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• 1988

This study simulates a typical solar system using the transient simulation program TRNSYS, and calculates the maximum cooling load of the model room of $50m^2$. In this study, energy rate control method is used in calculating a maximum cooling load. On the ground of the maximum cooling load of the model room, the variables that have an effect on the solar collection performance of the solar system are made a selection. Also in this study the trend of the solar collection performance is shown as the variables change. The results show that the variables which have an effect on the collection performance are collector area, collector mass flow rate, collector slope and the volume of storage tank, and the optimal value of Ac/Vt is not constant but varies as the collector area and the collector mass flow rate. Also the results show that for cooling system the optimal value of the collector slope is latitude minus $15^{\circ}$ during the seasonal operations, and twenty percent of the maximum cooling load is saved with the aid of the solar energy.

• International Journal of Fluid Machinery and Systems
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• v.5 no.1
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• pp.38-48
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• 2012

One centrifugal compressor is applied for refrigeration and its working substance is R134a. The operating points obtained by using similar conversion at different rotation speeds are compared with the numerical results. They keep consistent with each other while the rotation speeds are lower, but the error between them will become large with the increasing of the rotation speed. Then the operating points are obtained when the working substance is air by using two similar conversion methods separately. Based on the comparison, it can be obtained that the result of keeping the specific volume ratio of inlet and outlet is more accurate than the result of maintaining Ma number. Then the test result is compared with the similarity result and the numerical result when the working substance is air. It is obtained that the similarity result is more consistent with the test result better than the numerical result and the trend of efficiency and pressure ratio change with the flow rate is consistent with the test result. In the process of similar conversion, the efficiency ${\eta}$ is no useful for similitude design and it has less influence on the conversion result.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2003.05a
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• pp.270-273
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• 2003

The characteristic of constant volume micro combustor was investigated experimentally. The shape of micro combustor was cylindrical and has row aspect ratio or has relatively large diameter compared with chamber height. Diameter and chamber height was varied to investigate the geometric effect of combustor on the flame propagation. Diameter of 15 mm and 7.5 mm was designed while chamber height was designed to be 1mm, 2mm, and 3mm. The effect of initial pressure was also investigated parametrically from 1bar to 3bar. The gas used in this study was stoichiometric mixture of methane and air. The maximum pressure achieved in down scaled combustors was lower than that of conventional combustor because heat loss to wall was dominant as expected. The maximum pressure responded favorably with the change of height of combustor and the initial pressure, the maximum pressure was also increased. The flame propagation was possible when the specific condition was satisfied. Although the quenching distance of stoichiometric mixture of CH4 and Air is 2.5 mm, the flame could propagate even under quenching distance as the initial pressure increased.

• 한국태양에너지학회:학술대회논문집
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• 2012.03a
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• pp.165-170
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• 2012

This study aims to analyze the characteristics of temperature variation of Spandrels. According to the change of SHGC of Window system, air space, insulation performance and absorption factor of inner surface at the Spandrels, It was firstly estimated by using simulation. Secondly, measured to minimize the temperature-rise of inner surface temperature and the intermediate air temperature by using Full-scale Mock-up based on the result of simulation analysis. As a result, it turns out that low SHGC window system such as BIPV system had an advantage of reducing the window surface temperature, and the surface temperature of clear window system was all higher than BIPV system on simulation results. In the experiment results, it had some advantages of increasing the Spandrels volume, decreasing insulation performance and lower absorption factor.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.29 no.1 s.232
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• pp.55-62
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• 2005

Combustion Characteristics and quenching criteria of micro combustor in various condition was exploited experimentally. Two different gases were used, and various geometric matrixes were considered to figure out quenching characteristic of micro combustor. The micro combustor studied in this study was constant volume, and has cylindrical shape. Geometric parameter of combustor was defined to be combustor height and diameter. The effect of height was exploited parametrically as 1 mm, 2mm and 3mm and the effect of diameter was parameterized to be 7.5mm and 15mm. Three different combustibles. (1) Stoichiometric mixture of methane and are, (2) Stoichiometric mixture of hydrogen and air and (3) Mixture of hydrogen and air with fuel stoichiometry of two were used. Pressure transition during combustion process was recovered. The ratio of maximum pressure to initial pressure responded favorably with the change of height of combustor and the initial pressure, the maximum pressure was also increased. The flame propagation was observed only when a specific condition was satisfied. From the experiment the condition that guarantees stable propagation of flame was tabulated. The tabulated results includes criteria of quenching according to combustor height, combustor diameter, species of fuel and initial pressure.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.7 no.4
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• pp.577-588
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• 1995

A numerical study is made on the melting process of an unconstrained ice inside an isothermal ice-ball capsule. The unmelted ice core is continuously ascending on account of buoyancy forces. Such a buoyancy-assisted melting is commonly characterized by the existence of a thin liquid film above the ice core. The present study is motivated to present a full-equation-based analysis of the influences of the initial subcooling and the natural convection on the fluid flow associated with the buoyancy-assisted melting. In the light of the solution strategy, the present study is substantially distinguished from the existing works in that the complete set of governing equations in both the melted and unmelted regions are resolved in one domain. Numerical results are obtained by varying the wall temperature and initial temperature. The present results reported the transition of the flow pattern in a spherical capsule, as the wall temperature was increased over the density inversion point. In addition, time wise variation of the shapes for the liquid film and the lower ice surface, the time rate of change in the melt volume fraction and the melting distance at symmetric line is analyzed and is presented.

• Journal of the Korean Geotechnical Society
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• v.19 no.4
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• pp.15-21
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• 2003

A series of triaxial compression tests were performed on samples of compacted granite soil in a modified triaxial cell that allowed separate control of pore air pressure ($U_a$) and pore water pressure ($U_w$) in order to examine the characteristics of pore pressure, volume change and stress-strain behavior during undrained loading conditions. Triaxial samples of unsaturated and saturated compacted granite soil, 50mm in diameter and 100mm in height, were prepared by compaction in a mould. These samples were tested at 3 different suction values (0.5, 1.0, 2.0 kgf/cm$^2$) for unsaturated compacted granite soil and at 3 different confining stresses (1.0, 2.0, 4.0 kgf/cm$^2$). Results showed that only effective cohesion increased with little variation of friction angle, according to matric suction.

• International Journal of Concrete Structures and Materials
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• v.3 no.1
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• pp.15-23
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• 2009

Over about 30% of problems in construction is related to water-leaking, and the loss from this problem can incur as much as three times the cost of initial construction. Thus, water vapor pressure is known to be the primary cause of defective waterproofing. Accordingly, the theories on the relationship between water pressure and temperature as well as damp-proofing volume of concrete and the change in vapor pressure volume were reviewed and analyzed in this study by making test samples after spraying a dampness remover and applying waterproofing materials to the prepared test specimens. The result of measuring water vapor pressure with the surface temperature of the waterproofing (fluid-applied membrane) layer at the experimental temperature setting of about $10^{\circ}C$, which is the annual average temperature of Seoul, indicated that (1) the temperature of the fluid-applied membrane elevated to about $40^{\circ}C$, and the water vapor pressure generated from the fluid-applied membrane was about 0.03 N/mm 2 when the surface temperature of the waterproofing layer was raised to about $80^{\circ}C$. (2) when the temperature of the fluid-applied membrane of the waterproofing layer was raised from $30^{\circ}C$ to $35^{\circ}C$, water vapor pressure of about 0.01 N/mm 2 was generated, and (3) when a thermal source was applied to the fluid-applied membrane (waterproofing) layer, the temperature increased from $35^{\circ}C$ to $40^{\circ}C$, and approximately $0.005\;N/mm^2$ of water vapor pressure was generated.

• Journal of Biomedical Engineering Research
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• v.24 no.1
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• pp.9-13
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• 2003

An assist device was developed to identify the epidural space by continously monitoring the air-filled catheter pressure. The pressure signal appropriately amplified and filtered enabled to alarm the needle introduction into the epidural space by thresholding detection. Ten LEDs provided a visual change of catheter pressure before alarming for user convenience. Clinical trials were performed in 30 patients with 83% success rate at the first trial. When failed, the second trial was enough for successful anesthesia. The air volume introduced during each anesthesia was less than 1ml, causing side effects. Air filling of the catheter could also minimize infection possibility. Therefore, the present device guarantees safe anesthesia with user convenience.