• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2011.04a
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• pp.127-129
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• 2011

In the building, controlling temperature is main concern for maintaining fresh environment. To control temperature, phase change material(PCM) can be used as a medium that keeps temperature in certain level. PCM has its own phase change temperature. PCM melts/solidifies while absorbing/releasing the heat. Because of the advantage, PCM can be applied to a air-PCM heat exchanger. In this study, the air-PCM heat exchanger was designed based on the system requirements and experimental analysis was conducted to study on the performance of the heat exchanger.

• Journal of Advanced Engineering and Technology
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• v.10 no.3
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• pp.285-290
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• 2017

Molding of body with ribs is the most difficult during flow molding process. The rib area is easy to be deformed at the rear side due to wall thickness variation. In this study, relationships between molding condition and deflection of rib-shaped part is investigated during the compression molding of fiber reinforced plastic composites, and the following results are derived. Polypropylene(PP), Polystyrene(PS), and stampable sheet(SS 40wt%) show the increment of deflection along with releasing temperature. For the correlation between incremental holding pressure load and deflection, stampable sheet exhibits lower deflection along with higher holding pressure, while PS shows significant increase of deflection with higher holding pressure, PP shows completely different characteristic, significant reduction of deflection along with higher holding pressure. Regarding to mold temperature and deflection, deflection amount of SS is the biggest, and PS shows the smallest. In addition, all three kinds shows the highest amount of deflection at 173C. Deflection is reduced when mold closing speed is increased. Amount of deflection in SS is larger and is not highly dependent on molding conditions like holding pressure and cooling parameters, compared with single component material like PP. This can be elucidated by anisotropic and inhomogeneous characteristics of glass fiber during filling process of stampable sheet composite.

• KIEAE Journal
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• v.12 no.4
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• pp.97-104
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• 2012

A phase-change material is a substance with a high heat of fusion which, melting and freezing at a certain temperature, is capable of storing and releasing large amounts of energy. Heat is absorbed or released when the material changes from solid to liquid. Therefore, PCMs are classified as latent heat storage (LHS) units. The purpose of this study is to analyze PCM wallboard design parameters using dynamic energy simulation. Among the factors of PCM, melting temperature, latent heat, phase change range, thermal conductivity are very important element to maximize thermal energy storage. In order to analyze these factors, EnergyPlus which is building energy simulation provided by department of energy from the U.S is used. heat balance algorithm of energy simulation is conduction finite difference and enthalpy-temperature function is used for analyzing latent heat of PCM. The results show that in the case of melting temperature, the thermal energy storage could be improved when the melting temperature is equal to indoor surface temperature. It seems that when the phase change range is wide, PCM can store heat at a wide temperature, but the performance of heat storage is languished.

• International Journal of Naval Architecture and Ocean Engineering
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• v.10 no.6
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• pp.670-682
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• 2018

This paper presents the experimental and numerical investigation results of the response of low-temperature steel (LT-FH32 grade steel) beams under repeated impacts at room temperature and a single impact at a sub-zero temperature. After conducting tensile tests at room and sub-zero, repeated impact tests were conducted on two clamped single-beam models at room temperature, and single-impact tests of two other clamped single-beam models were conducted at $-50^{\circ}C$. The single and repeated impact tests were conducted by releasing a knife-edge striker using a drop testing machine. The permanent deflection of the model measured after each impact gradually increased with increasing number of impacts. Under the reduced temperature, the permanent deflection of the models slightly decreased. The numerical analyses were also performed to predict the damage response of the tested single-beam models. A comparison of the numerical prediction with those of experiments showed quite reasonable agreement.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 1997.04a
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• pp.337-341
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• 1997

The purpare of this research is to develope a FEM program for analyzing solidification processes of axisymmetic casting, considering phase changes and the contact between the metal and mold. Temperture recovery method is employed for considering the phase changes releasing the latent heat. A gap element is employed for modeling the interface between the model and metal in finding deformed shapes. In order to verify the developed program, an axisymmetric aluminum casting processes is simulated. Temperature distribution, phase front position, and shrinkaga and porosity creation are compared with measurement, FIDAP results, and ANSYS results, and good agreements are examined.

• Journal of the Korean Society of Manufacturing Technology Engineers
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• v.21 no.2
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• pp.259-266
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• 2012

In this study, the temperature distributions are analyzed on the air flow according to the position of fan inside computer main frame by CFD simulation. In case that ventilation hole is existed at the side of computer frame, the air with lower temperature can be circulated near CPU radiant thermal panel. In case of installation with fan at the side panel, the temperature of air flow becomes lowest. The efficiency of thermal emission at personal computer and its durability can be improved by releasing a lot of heat at air flow effectively inside computer frame according to this simulation result.

• Carbon letters
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• v.13 no.3
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• pp.173-177
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• 2012

A drug delivery system (DDS) was prepared with a temperature and pH-responsive hydrogel. Poly(vinyl alcohol) (PVA)/poly(acrylic acid) (PAAc)/poly(N-isopropylacrylamide) (PNIPAAm)/multi-walled carbon nanotube (MWCNT) nanocomposites were prepared by radical polymerization for the temperature and pH-responsive hydrogels. MWCNTs were employed to improve both the thermal conductivity and mechanical properties of the PVA/PAAc/PNIPAAm/MWCNT nanocomposite hydrogels. Various amounts of MWCNTs (0, 0.5, 1 and 3 wt%) were added to the nanocomposite hydrogels. PVA/PAAc/PNIPAAm/MWCNT nanocomposite hydrogels were characterized with a scanning electron microscope. The mechanical properties were measured with a universal testing machine. Swelling and releasing properties of nanocomposite hydrogels were investigated at various temperatures and pHs. Temperature and pH-responsive release behavior was found to be dependent on the content of MWCNTs in nanocomposite hydrogels.

• Proceedings of the Korean Fiber Society Conference
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• 2003.04a
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• pp.287-288
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• 2003

Polyurethane(PU) materials have been generally used in the automobile, paint, furniture, adhesive, and textile industries. The use of Waterborne PU was motivated form the environmental point of view, i.e. reduction of solvent emissions into the atmosphere(volatile organic compounds, VOC)[1]. Generally speaking, phase change materials (PCM) have the capability of absorbing or releasing thermal energy to reduce or eliminate heat transfer at the temperature range of the particular temperature stabilizing material[2]. (omitted)

• 한국전산유체공학회:학술대회논문집
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• 2001.05a
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• pp.170-175
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• 2001

Fire inside light railway transit(LRT) was simulated for various fire scenarios using CFD analysis in order to assess the safety of passengers. Considered in the present paper are the effects of locations of fire, a fire size, an operation of ventilation system and an opening time of door on evolution of temperature and smoke concentration inside the LRT. For fire simulation, fire cells releasing heat and smoke corresponding to fire size were positioned at the location of fire. From the results, it is seen that the ventilation system and the opening time of door were the most important factors on temperature and smoke concentration inside the LRT

• 한국지구물리탐사학회:학술대회논문집
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• 2003.11a
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• pp.642-647
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• 2003

Palladium is widely used for several applications and recovery of palladium from secondary sources becomes increasingly important since palladium is one of maldistributed platinum group metals. Electrochemical recovery of dense palladium metal sheet from Pd leaching solution is a simple and easily controlled method. The surface morphology of the recovered Pd metal was significantly affected by current density and temperature. Dense deposit morphology was in higher stress state regardless of preparation condition under $55^{\circ}C$. Rising temperature up to $70^{\circ}C$ had a stress releasing effect besides densification of Pd deposit.