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The detector performance and presence of Te secondary-phase defects distribution were investigated in CdMnTe (CMT) crystals prepared with different cooling rates. Detectors fabricated from fast-cooled CMT crystals exhibit a relatively poor detector performance, although IR transmission microscopy measurements show that the Te secondary-phase defects have a lower concentration and smaller size compared to slow-cooled crystals. Current deep-level transient spectroscopy (I-DLTS) measurements for both CMT detectors reveal the same trap levels, but there is a clear difference in the densities for the 0.26- and 0.42-eV traps for the two different cooling schemes. These two traps are probably attributed to Cd vacancies and Te anti-site defects, respectively. In addition, there is some likelihood that the traps are anti-correlated with respect to each other. [ABSTRACT FROM AUTHOR]

The relationship between slider and lubricant becomes increasingly important as the mechanical spacing between slider and disk is reduced to satisfy the demand for higher areal density. At a reduced flying height, the slider easily contacts the lubricant, which can cause slider instability. This study analyzed slider dynamics to improve the head-disk reliability in the unsteady proximity condition, considering bias voltages between the slider, disk, and lubricant. Force-distance curves were measured using atomic force microscopy to investigate changes in lubricant performance induced by an applied voltage. Additionally, the touch-down power and take-off power were measured under various applied voltage conditions. Experiments were carried out to estimate slider instability as a function of charged disk and slider conditions, to improve the slider dynamics in the unsteady proximity condition. The effect of the bias voltage induced by a voltage applied to the lubricant was carefully examined to accurately understand slider dynamics. The relationship between the lubricant behavior and the applied voltage was investigated; the voltage applied to the disk was more influential in improving slider dynamics. Consequently, the effects of bias voltage and lubricant, as induced by a charged disk, should be considered when analyzing slider dynamics to improve head-disk interface reliability in an unsteady proximity condition. [ABSTRACT FROM AUTHOR]

This paper analyzed the effect of lubricant contact on slider dynamics under the unsteady proximity condition, which is related to the intermolecular forces between the slider and disk. To investigate the slider dynamics, an experiment was conducted with a commercial drive, and the slider dynamics were analyzed during touch-down and takeoff (TO) considering the approach and withdrawal speeds of the slider. The instability of the slider dynamics increased under the rapid withdrawal condition during TO. [ABSTRACT FROM AUTHOR]

With an increased mobility, hard disk drives (HDDs) now use ramp load/unload technology, and multiple disks are used to increase the data capacity. This can result in contact between the ramp and the disks, which negatively affects the slider dynamics under operational shock conditions. There are several types of ramp–disk contact, such as simultaneous, successive, and single contact, and these depend on the distance between the ramp and each disk in a multi-disk HDD. This paper examines the effect of ramp–disk contact on the slider dynamics using a transient shock analysis. The ramp–disk contact affects the head stack assembly bending mode and slider dynamics. The effect of irregular gaps between the disks and adjacent ramp on the slider dynamics is analyzed with the ramp–disk contact force. The simulation shows that the gap irregularity between the ramp and each disk should be as small as possible to improve the stability of the slider dynamics. [ABSTRACT FROM AUTHOR]

The objective of this study was to evaluate the patient effective dose and scattered dose from recently developed dental mobile equipment in Korea. The MCNPX 2.6 (Los Alamos National Laboratory, USA) was used in a Monte Carlo simulation to calculate both the effective and scattered doses. The MCNPX code was constructed identically as in the general use of equipment and the effective dose and scattered dose were calculated using the KTMAN-2 digital phantom. The effective dose was calculated as 906 μSv. The equivalent doses per organ were calculated via the MCNPX code, and were 32 174 and 19 μSv in the salivary gland and oesophagus, respectively. The scattered dose of 22.5–32.6 μSv of the tube side at 25 cm from the centre in anterior and posterior planes was measured as 1.4–3 times higher than the detector side of 10.5–16.0 μSv. [ABSTRACT FROM AUTHOR]

In this study, diagnostic reference levels (DRLs) were suggested and patient doses were analysed through the dose–area product value in dental radiography. In intraoral radiography, at three sites, i.e. molar, premolar and incisor on the maxilla and acquired third quartile values: 55.5, 46 and 36.5 mGy cm2, respectively, were measured. In panoramic, cephalometric and cone beam computed tomography, the values were 120.3, 146 and 3203 mGy cm2 (16 × 18 cm), respectively. It has been shown that, in intraoral radiography, the patient dose changes proportionally to the value of mA s, but the change in extraoral radiography in response to mA s could not be confirmed. The authors could confirm, however, the difference in dose according to the manufacturer in all dental radiography examinations, except for panoramic radiography. Depending on the size of hospital, there were some differences in patient dose in intraoral radiography, but no difference in patient dose in extraoral radiography. [ABSTRACT FROM AUTHOR]

Recently, simulations based on the Monte Carlo code have been increasingly applied for physics phenomena, patient dose and quality assurance of radiation systems. The objective of this study was to use Monte Carlo simulation and measurement to verify dose and dose reduction in cephalography. The collimator was constructed with 3-mm thick lead plate, and attached to the tube head to remove regions of disinterest in the radiation field. A digital phantom patient was constructed to evaluate patient dose. In addition, detectors of pixel size 1×1 cm2 and 0.1×0.1 cm2 were constructed to check collimator location. The effective dose according to International Commission on Radiological Protection 103 was calculated with and without collimation. The effective doses for simulation with and without collimation were 5.09 and 11.32 µSv, respectively. The results of the calculated effective dose show 61.7 % reduction of field area and 55 % of effective dose. The Monte Carlo simulation is a good evaluation tool for patient dose. [ABSTRACT FROM PUBLISHER]

The primary goal of this study was to analyse the state of patient doses in the field of computed tomography (CT) examinations in the Republic of Korea. All survey data including the CT applications and patient dose details were obtained from general hospitals registered in the Korean Hospital Association. The systematic analysis of the patient dose survey gives target values of the weighted computed tomography dose index (CTDI(w)) and the dose-length product (DLP). The targeted CTDI(w) values were 69, 69, 31, 19, 44, 25, 24, 20, 2, 19 and 19 mGy for the brain non-contrast enhancement (BNCE), brain contrast enhancement (BCE), neck, chest, spine, liver, pancreas, stomach, kidneys, abdomen routine and abdomen trauma protocols, respectively. The targeted DLP values were 1056, 2112, 762, 1234, 1338, 2794, 2742, 2378, 2836, 1844 and 1939 mGy cm for the BNCE, BCE, neck, chest, spine, liver, pancreas, stomach, kidneys, abdomen routine and abdomen trauma protocols, respectively. Comparing with the EUR recommendation, especially in the DLP, the adjustment of the total scan phase frequency and the shortening of the scan phase in each scan phase are needed to reduce the patients radiation exposure to international standards.

The purpose of this research is to develop a diagnostic reference level for computed tomography (CT) suitable for Korean medical purposes. The direction of CT application and details on patient dose were investigated by survey, and the dose measurement is targeted in general hospitals registered with the Korean Hospital Association. The dose measurement was done with head and body phantom, and an accurate dosimeter was utilised in medical institutions that participated in the survey. The survey and dose measurements on the patient dose showed that the 75th percentiles in the distribution of weighted CT dose index (CTDIw) were 50.5 and 45.4 mGy for the head and 14.4 and 25.30 mGy for the body portions, respectively. Based on these research data, the target patient doses that are believed to be achievable for CT examination in Korean circumstances are about 48 +/- 4 mGy in the head and 20 +/- 8 mGy in the body.