ICES Database ElectroMagnetic Field Literature Search Engine |
 |
| |
| Home |
| View EMF Studies (Static,ELF) 0-300 Hz |
| View EMF Studies (Intermediate) 300 Hz-300 KHz |
| View EMF Studies (RF/mmW/THz) 300 kHz-300 GHz |
| Advanced Search |
| Citation List (Author Search) |
(Database last updated on Mar 27, 2024)
| ID Number | 2360 | |
| Study Type | Engineering & Physics | |
| Model | SAR values in SAM phantom and other head models of children and adults exposed at mobile phone frequencies including 835 and 1900 MHz and 5G exposure assessment in Republic of Korea. | |
| Details | AUTHORS' ABSTRACT: Lee and Yun 2011 (IEEE # ): The specific absorption rates (SARs) in 7-year-old Korean, and 5- and 9-year-old European child head models were evaluated and compared with those of the specific anthropomorphic mannequin (SAM) phantom for mobile phone exposure at 835 and 1900 MHz. Compression of the pinnae was also considered for the 5- and 7-year-old child models during the evaluation. The cheek and tilt positions occurring when the earpiece of the phone is placed at the ear entrance canal (EEC) were analyzed against the same positions occurring when the earpiece is placed at the ear reference point (ERP). SAR variations were investigated for different skin and fat properties, as well as for different internal fat and muscle morphologies in the tissue area near the phone. A basic phone model with a monopole antenna was used for SAR calculation at each frequency. A phone model with a planar inverted F antenna was also used for verification, since the SAR results in the child models were higher than those in the SAM phantom at 1900 MHz. The spatial peak 10-g SAR values in all tissue including the pinnae and head-only were normalized to a forward power of 1 W at the feedpoint of the phone. Our results can be summarized as follows. First, a compressed pinna did not show significant changes in SAR values at 835 MHz; however, at 1900 MHz, there was an average 25% increase in spatial peak 10-g SARs for pinna-excluded tissue and a 29% increase for pinna-included tissue. Second, a phone earpiece placed at the EEC provided higher SARs in many cases compared to placement at the ERP. Third, the peak 10-g SAR was found to be very sensitive to the fat and muscle structure under the skin when touched by the mobile phone; a muscle-dominant internal head structure led to a higher peak 10-g SAR. Finally, the SAM phantom does not seem to provide a conservative estimation of child head exposure at 1900 MHz; 45% (pinna-excluded: IEEE Std C95.1) and 75% (pinna-included: ICNIRP guidelines) of the 40 total cases we reviewed showed higher SAR results than the SAM phantom. AUTHORS' ABSTRACT: Lee et al. 2005 (IEEE #5463): A specific anthropomorphic mannequin (SAM) model was used to investigate the relation between local specific absorption rate (SAR) and head size. The model was scaled to 80 to 100% sized models at intervals of 5%. We assumed that the shell of the SAM model has the same properties as the head equivalent tissue. Five handsets with a monopole antenna operating at 835 MHz were placed in the approximate cheek position against the scaled SAM models. The handsets had different antenna lengths, antenna positions, body sizes, and external materials. SAR distributions in the scaled SAM models were computed using the finite-difference time-domain method. We found that a larger head causes a distinct increase in the spatial peak 1-voxel SAR, while head size did not significantly change the peak 1-g averaged-SAR and 10-g averaged-SAR values for the same power level delivered to the antenna. AUTHORS' ABSTRACT: Lee et al. 2002 (IEEE #5464): Using scaled models for an anatomical head model and a simple head model, we investigated the effects of head size on specific absorption rate characteristics for two mobile phones operating at 835 MHz and 1765 MHz. Our results showed that a larger head produced a higher localized SAR at 835 MHz. However, at 1765 MHz, the differences among the head models were insignificant since the superficial absorption was dominant over the effects of head shape and size. A larger head produced a lower whole-head averaged SAR at both frequencies. AUTHORS' ABSTRACT: Lee and Choi 2012 (IEEE #5651): Compliance of the ICNIRP reference and IEEE action levels with the basic restrictions on whole-body average (WBA) SAR was investigated based on age, physique, and posture under isolated and grounded conditions. First, Korean male models 1, 3, 5, 7, and 20 years of age with body sizes in the 50th percentile were developed and used as the test subjects: 1y50th, 3y50th,5y50th, 7y50th, and 20y50th. The effects of age-dependent dielectric properties due to the water content of the tissue onWBA SAR were analysed, and showed that the changes in WBA SAR are marginal. At the ages of 1, 5, and 20, thin models 1y10th, 5y10th, and 20y10th with body sizes in the 10th percentile for the horizontal plane were added in order to determine the influence of physical variations of the population. We considered standing postures with arms up and arms down. The WBA SAR for each human model was calculated when exposed to a vertically polarized plane wave in the frequency range of 10 MHz3 GHz using the finite-difference time-domain method. The evaluated WBA SAR-based safety factor of each model is discussed for exposure to the ICNIRP reference and IEEE action levels. Finally, the lowest external electric field strength required to produce the basic restrictions on the WBA SAR, 0.08 W kg1, was obtained. The results showed that the ICNIRP public reference level is not conservative in the frequency range of 20200 MHz for an arms-up posture, in the range of 40200 MHz for an arms-down posture, and above 1 GHz for both postures. The IEEE action level is different from the ICNIRP reference level below 30 MHz, where most cases showed a safety factor of less than 50, which is the minimum value compliant with the basic restrictions for exposure to the general public. AUTHORS' ABSTRACT: Lee et al. 2017 (IEEE #6724): Mobile phones differ in terms of their operating frequency, outer shape, and form and location of the antennae, all of which affect the spatial distributions of their electromagnetic field and the level of electromagnetic absorption in the human head or brain. For this paper, the specific absorption rate (SAR) was calculated for four anatomical head models at different ages using 11 numerical phone models of different shapes and antenna configurations. The 11 models represent phone types accounting for around 86% of the approximately 1400 commercial phone models released into the Korean market since 2002. Seven of the phone models selected have an internal dual-band antenna, and the remaining four possess an external antenna. Each model was intended to generate an average absorption level equivalent to that of the same type of commercial phone model operating at the maximum available output power. The 1 g peak spatial SAR and ipsilateral and contralateral brain-averaged SARs were reported for all 11 phone models. The effects of the phone type, phone position, operating frequency, and age of head models on the brain SAR were comprehensively determined. AUTHORS' ABSTRACT: Lee et al. 2016 (IEEE #6727): This paper describes an implementation method and the results of numerical mobile phone models representing real phone models that have been released on the Korean market since 2002. The aim is to estimate the electromagnetic absorption in the human brain for casecontrol studies to investigate health risks related to mobile phone use. Specific absorption rate (SAR) compliance test reports about commercial phone models were collected and classified in terms of elements such as the external body shape, the antenna, and the frequency band. The design criteria of a numerical phone model representing each type of phone group are as follows. The outer dimensions of the phone body are equal to the average dimensions of all commercial models with the same shape. The distance and direction of the maximum SAR from the earpiece and the area above 3 dB of the maximum SAR are fitted to achieve the average obtained by measuring the SAR distributions of the corresponding commercial models in a flat phantom. Spatial peak 1-g SAR values in the cheek and tilt positions against the specific anthropomorphic mannequin phantom agree with average data on all of the same type of commercial models. Second criterion was applied to only a few types of models because not many commercial models were available. The results show that, with the exception of one model, the implemented numerical phone models meet criteria within 30%. AUTHORS' ABSTRACT: Han et al. 2018 (IEEE #6979): Increased use of mobile phones raises concerns about the health risks of electromagnetic radiation. Phantom heads are routinely used for radiofrequency dosimetry simulations, and the purpose of this study was to construct averaged phantom heads for children and young adults. Using magnetic resonance images (MRI), sectioned cadaver images, and a hybrid approach, we initially built template phantoms representing 6-, 9-, 12-, 15-year-old children and young adults. Our subsequent approach revised the template phantoms using 29 averaged items that were identified by averaging the MRI data from 500 children and young adults. In females, the brain size and cranium thickness peaked in the early teens and then decreased. This is contrary to what was observed in males, where brain size and cranium thicknesses either plateaued or grew continuously. The overall shape of brains was spherical in children and became ellipsoidal by adulthood. In this study, we devised a method to build averaged phantom heads by constructing surface and voxel models. The surface model could be used for phantom manipulation, whereas the voxel model could be used for compliance test of specific absorption rate (SAR) for users of mobile phones or other electronic devices. AUTHORS' ABSTRACT: Lee, Park et al. 2019 (IEEE #7173): This paper aims to implement average head models of Korean males and investigate age-related differences in the brain for exposure from radiation from mobile phones. Four male head models composed of a total of 69 structures were developed through a statistical investigation of the anatomical morphology for the age groups of 6, 9, 15 and 2024 years in age, which are named KR-6, KR-9, KR-15, and KR-22 herein. Three numerical bar phone models with a dual-band built-in antenna were applied to calculate the specific absorption rate (SAR) in the brain; the body lengths of models M avg and M long have the mean value and upper 5th percentile value of commercial bar phone models, respectively, with an antenna at the bottom, whereas M rev has an antenna on top of the phone body, which is the same as in M avg but rotated 180°. The cheek and tilt positions were employed for SAR simulations. As a result, a higher peak spatial-average SAR (psSAR) was observed in the brain for the child groups of KR-6 and KR-9 than for the adult groups of KR-15 and KR-22. In most configurations, the position-averaged psSAR10 g in the child brain was 62% (M long, 835 MHz), 61% (M avg, 835 MHz), 102% (M long, 1850 MHz), 108% (M avg, 1850 MHz), and 125% (M rev, 1850 MHz) higher than in the adult brain. The higher frequency of 1850 MHz showed a wider difference in the brain psSAR between the child and adult groups owing to the shorter penetration depth. When a long phone with an antenna at the bottom operates at a higher frequency, it significantly reduces the brain exposure. |
|
| Findings | Effects (replication needed) | |
| Status | Completed With Publication | |
| Principal Investigator | Electronics and Telecom Res Institute, Korea | |
| Funding Agency | KCC | |
| Country | KOREA, REPUBLIC OF | |
| References |
|
|
| Comments |