Time filter

Source Type

Ban Rangsit, Thailand

Wessapan T.,Eastern Asia University | Srisawatdhisukul S.,Rangsit University | Rattanadecho P.,Rangsit University
International Journal of Heat and Mass Transfer | Year: 2012

This study presents a numerical analysis of specific absorption rate (SAR) and temperature distributions in the realistic human head model exposed to mobile phone radiation at 900 MHz and 1800 MHz. In the realistic human head model, the effects of operating frequency and gap distance between the mobile phone and the human head on distributions of specific absorption rate and temperature profile within the human head are systematically investigated. This study focuses attention on each tissue in the human head in order to investigate the effects of mobile phone radiation on the human head. The SAR and the temperature distribution in various tissues in human head during exposed to mobile phone radiation, obtained by numerical solution of electromagnetic wave propagation and unsteady bioheat transfer equations, are presented. For both frequencies, the highest SAR values are obtained in the region of the skin near the antenna. It is found that the highest SAR values are 0.823 W/kg and 1.187 W/kg for the frequencies of 900 MHz and 1800 MHz, respectively. The SAR values obtained from this study are well below ICNIRP limit for all cases. In addition, it is found that the temperature distributions are not directly proportional to the local SAR values. Moreover, the experimental validation has been carried out by using the infrared camera in order to complement the simulation results. © 2011 Elsevier Ltd. All rights reserved.

Wessapan T.,Eastern Asia University | Rattanadecho P.,Rangsit University
International Journal of Heat and Mass Transfer | Year: 2016

Electromagnetic fields (EMF) have been a vital part of our daily life over the past decade. Therefore, people are continuously exposed to electromagnetic (EM) sources in their vicinity generated by electronic devices such as those emitted by Wi-Fi, mobile phones, portable wireless router and other wireless services. This study aims to investigate the SAR, fluid flow and heat transfer in biological tissue due to EM near-field exposure. In a tissue model, the effects of distance to an EMF source and tissue permeability on natural convection in the biological tissue are systematically investigated. The specific absorption rate (SAR), fluid flow and the temperature distributions in the tissue during exposure to EM fields are obtained by numerical simulation of EM wave propagation and heat transfer equations. The EM wave propagation is expressed mathematically by Maxwell's equations. The heat transfer model used in this study is developed based on bioheat model and porous media model. By using the porous media model, the distribution patterns of temperature are quite different from the bioheat model by the strong blood dissipation effect of the porous media model. The exposure distance significantly influences the SAR, velocity field and temperature distribution. Moreover, the tissue permeability also affects the temperature distribution patterns within the tissue. The obtained results may be of assistance in determining exposure limits for the power output of the wireless transmitter, and its distance from the human body. The results can also be used as a guideline to clinical practitioners in EM relates the interaction of the radiated waves with the human body. © 2016 Elsevier Ltd. All rights reserved.

Klongpityapong P.,Eastern Asia University | Supabphol R.,Srinakharinwirot University | Supabphol A.,Srinakharinwirot University
Asian Pacific Journal of Cancer Prevention | Year: 2013

Background: To assess the antioxidant effects of gamma-oryzanol on human prostate cancer cells. Materials and Methods: Cytotoxic activity of gamma-oryzanol on human DU145 and PC3 prostate cancer cells was determined by proliferation assay using 3-(4, 5-dimethylthiazol, 2-yl)-2, 5-diphenyl tetrazolium bromide (MTT) reagent. mRNA levels of genes involved in the intracellular antioxidant system, superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GPX) and glutathione reductase (GSR) were determined by reverse transcription-polymerase chain reaction (RT-PCR). Cancer cell lysates were used to measure lipid peroxidation using thiobarbituric acid reactive substance (TBARS). Glutathione contents of the cell lysates were estimated by the reaction between sulfhydryl group of 5, 5'-dithio (bis) nitrobenzoic acid (DTNB) to produce a yellow-color of 5-thio-2-nitrobenzoic acid using colorimetric assay. Catalase activity was also analysed by examining peroxidative function. Protein concentration was estimated by Bradford's assay. Results: All concentrations of gamma-oryzanol, 0.1-2.0mg/ml, significantly inhibited cell growth in a dose- and time-dependent fashion in both prostate cancer cell lines, DU145 and PC3. Gene expression of catalase in DU145 and PC3 exposed to gamma-orizanol at 0.5mg/ml for 14 days was down regulated, while mRNA of GPX was also down regulated in PC3. The MDA and glutathione levels including catalase activity in the cell lysates of DU145 and PC3 treated with gamma-oryzanol 0.1 and 0.5mg/ml were generally decreased. Conclusions: This study highlighted effects of gamma-oryzanol via the down-regulation of antioxidant genes, catalase and GPX, not cytotoxic roles. This might be interesting for adjuvant chemotherapy to make prostate cancer cells more sensitive to free radicals. It might be useful for the reduction of cytotoxic agents and cancer chemoprevention.

Uyaisom C.,Eastern Asia University
Advanced Science Letters | Year: 2014

Personal computer or PC is widely used in business, industry, education, and entertainment. Today, a PC can be either a desktop PC or an all-in-one PC. All-in-one PCs are newer models that are increasingly more popular because they are small, and so need less space, are easy to move, and consume less electrical energy, up to 77.36%. However, an All-in-one PC may cause a serious problem of power quality, such as harmonics noise and low power factor, to control systems. Particularly, it can affect other electronic devices connected to the same main and cause electronic malfunction or even permanently damage these devices. © 2014 American Scientific Publishers All rights reserved.

Kerdlap P.,Eastern Asia University
Applied Mechanics and Materials | Year: 2014

This paper presents the effect of power supply of LED lamp for external lighting are compares with electrical performance, electrical energy saving, illuminance, and the effect of harmonics noise from each power supplies on external lighting with LED. By designing and construct a linear power supply by the full wave rectifier circuit by bridge diode type and switching power supply by buck converter. The result that, the full wave rectifier circuit by bridge diode type was consumed higher power less than buck converter but lower effect of harmonics noise. In additional, as a result will be important data to the education develops and the next research. © (2014) Trans Tech Publications, Switzerland.

Discover hidden collaborations