• Journal of the Korean Solar Energy Society
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• v.27 no.4
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• pp.11-17
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• 2007

The purpose of this study is to check whether the plate temperature could be lower than the surrounding air by using the radiant cooling during the day time in summer at Seoul. Without an insolation shield as this experiment was performed, a few cases were found. The temperatures of the black painted plate are lower than those of the aluminium film coated plate if the following condition exist; no or small insolation over the plate, the wind velocity less than around 2 m/s, and clear sky However if there are insolation over the plate, the temperatures of the aluminium coated plate are lower than the black painted plate. Also, as the wind velocity increases, the plate temperature decreases faster. The temperature response of the small system is much faster than the large system.

• Journal of Surface Science and Engineering
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• v.48 no.6
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• pp.297-302
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• 2015

Nanocrystalline diamond(NCD) coated aluminium plates were prepared and applied as heat sinks for LED modules. NCD films were deposited on 1 mm thick Al plates for times of 2 - 10 h in a microwave plasma chemical vapor deposition reactor. Deposition parameters were the microwave power of 1.2 kW, the working pressure of 90 Torr, the $CH_4/Ar$ gas ratio of 2/200 sccm. In order to enhance diamond nucleation, DC bias voltage of -90 V was applied to the substrate during deposition without external heating. NCD film was identified by X-ray diffraction and Raman spectroscopy. The Al plates with about 300 nm thick NCD film were attached to LED modules and thermal analysis was carried out using Thermal Transient Tester (T3ster) in a still air box. Thermal resistance of the module with NCD/Al plate was 3.88 K/W while that with Al plate was 5.55 K/W. The smaller the thermal resistance, the better the heat emission. From structure function analysis, the differences between junction and ambient temperatures were $12.1^{\circ}C$ for NCD/Al plate and $15.5^{\circ}C$ for Al plate. The hot spot size of infrared images was larger on NCD/Al than Al plate for a given period of LED operation. In conclusion, NCD coated Al plate exhibited better thermal spreading performance than conventional Al heat sink.

• Journal of the Korean Society for Geothermal and Hydrothermal Energy
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• v.14 no.1
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• pp.22-29
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• 2018

The purpose of this study is to investigate the preliminary thermal performance of a plastic coated aluminum material(PCAM) plate heat exchanger. Plastic coating which has high corrosion resistivity and thermal conductivity can overcome corrosive weakness of aluminum material. The heat exchangers are modeled for STS316, Titanium and PCAM materials, and analyzed numerically using HTRI and ANSYS Fluent CFD softwares. The results show that PCAM heat exchanger is superior in heat transfer performance compared to existing materials. For chevron angle of $60^{\circ}$, thermal performances of Titanium and PCAM are higher by 12.2% and 48.9% when compared to STS316, respectively.

• Journal of Surface Science and Engineering
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• v.50 no.3
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• pp.198-205
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• 2017

Thermal dissipation was investigated for poly methyl methacrylate (PMMA) composite films containing graphite and multi wall carbon nanotube(CNT) powders as filler materials. After mixing PMMA with fillers, solvent, and dispersant, the pastes were prepared by passing through a three roll mill for three times. The prepared pastes were coated $15{\sim}40{\mu}m$ thick on a side of 0.4 mm thick aluminium alloy plate and dried for 30 min at $150^{\circ}C$ in an oven. The content of fillers in dried films was varied as 1, 2, and 5 weight % maintaining the ratio of graphite and CNT as 1:1. Raman spectra from three different samples exhibited D, G and 2D peaks, as commonly observed in graphite and multi wall CNT. Among those peaks, D peak was prominent, which manifested the presence of defects in carbon materials. Thermal emissivity values of three samples were measured as 0.916, 0.934, and 0.930 with increasing filler content, which were the highest ever reported for the similar composite films. The thermal conductivities of three films were measured as 0.461, 0.523, and $0.852W/m{\cdot}K$, respectively. After placing bare Al plate and film coated samples over an opening of a polystyrene box maintained for 1 h at $92^{\circ}C$, the temperatures inside and outside of the box were measured. Outside temperatures were lower by $5.4^{\circ}C$ in the case of film coated plates than the bare one, and inside temperatures of the former were lower by $3.6^{\circ}C$ than the latter. It can be interpreted that the PMMA composite film coated Al plates dissipate heat quicker than the bare Al plate.

• Journal of Surface Science and Engineering
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• v.49 no.2
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• pp.218-224
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• 2016

Thermal radiation pastes were prepared by dispersing carbon materials as fillers with a content of 1 weight percent in an acrylic resin. The kind of fillers was as follows; $25{\mu}m$ graphite, $45{\mu}m$ graphite, $15{\mu}m$ carbon nanotube(CNT), a 1:1 mixture of $25{\mu}m$ graphite and $15{\mu}m$ CNT, and a 1:1 mixture of $45{\mu}m$ graphite and $15{\mu}m$ CNT. Thermal emissivity was measured as 0.890 for the samples with graphite only, 0.893 for that with CNT only, and 0.892 for those containing both. After coating prepared pastes on a side of 0.4 mm thick aluminium plate and placing the plate over an opening of a box maintained at $92^{\circ}C$ with the coated side out, the temperatures on the uncoated side of the plates were measured. The samples containing graphite and CNT showed the lowest temperatures. The paste with mixed fillers was coated on the back side of the PCB of an LED module and thermal analysis was carried out using Thermal Transient Tester (T3ster) in a still air box. The thermal resistance of the module with coated PCB was measured as 14.34 K/W whereas that with uncoated PCB was 15.02 K/W. The structure function analysis of T3ster data revealed that the difference between junction and ambient temperatures was $13.8^{\circ}C$ for the coated case and $18.0^{\circ}C$ for the uncoated. From the infrared images of heated LED modules, the hottest-spot temperature of the module with coated PCB was lower than that of the uncoated one for a given period of LED operation.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.6 no.5
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• pp.418-422
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• 2005

The degradation of IPA according to coating conditions was examined by $TiO_{2}$/p-25-coated aluminium metal plate. Inorganic(KR-400), inorganic$\cdot$ organic hybrid(TMOS) and organic(A-9540) resins were used as binder $TiO_{2}$ coated surface of aluminum metal plate was clear with all binders, and the adhesion of binders was good except inorganic binder. The activity for IPA degradation appeared to range in order A-9540>TMOS>KR-400. The optimum activity was obtained when the ratio of TMOS and P-25 was 1.6:10, and when the ratio of A-9540 and P-25 was 1.0:6.0, respectly.

• Anatomy and Cell Biology
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• v.55 no.1
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• pp.92-99
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• 2022

The liver is the largest gland of the gastrointestinal tract having both exocrine and endocrine functions. Developmentally it arises as a ventral outgrowth from the gut endoderm during 3rd week of intrauterine life. The foetal liver is very important because of its synthetic and hemopoietic potential. The present work aimed to see the detailed histogenesis and development of the foetal liver by cytological, immunohistochemical and ultrastructural study. The liver tissue of nine aborted foetuses of various gestational age were studied. For cytology: special stains like Masson trichrome, periodic acid Schiff and reticulin were used, immunohistochemical staining was performed with triple antibodies (c-myc, Ki-67 and Ber-H2), and for ultrastructure: aluminium mounted specimens were coated with gold and argon gas and observed under scanning electron microscopy (EM). Cytology and immunohistochemistry showed the development of duct patterns and hemopoietic patterns in all stages of fetogenesis. The ductal plate was marked by the layer of dark brown staining cells at the edge of two portal tracts. The haemopoietic cells with sinusoids and aggregation of hepatocytes were observed in the early weeks of gestation. EM showed tree-like branching of a portal canal depicting hepatic segmentation of foetal liver. The organizational changes in lobular pattern, duct pattern, and microstructure of liver during fetogenesis are very crucial to achieve the adult morphology in feature. Histogenesis of the foetal liver follows a multistep process depending upon the gestational age, any deviation from normalcy may lead to structural and functional abnormality later in life.