Jae-moon Jo

Performance evaluation of MIMO-OFDM systems in correlated fading channels

In this paper, we provide the simulation results for the bit error rate (BER) performance of multi-input multi-output (MIMO) systems supporting a 96 Mbps data-rate, based on an IEEE 802.11a OFDM PHY layer under various channel models. A spatial multiplexing system combined with space-time trellis coding (SM-STTC) undergoes the most significant performance degradation in correlated channel environments compared to that in an uncorrelated channel. A spatial multiplexing system combined with space-time block coding (SM-STBC) and a hybrid SM-STBC system produce similar results in correlated fading channels. The V-BLAST system achieves comparable performance to other systems under correlated channels when receive diversity is exploited.

3D perception enhancement using depth map based color processing

The color, contrast and detail of an object in focus are increased, whereas those of a background are decreased based on the depth map for simulating atmospheric perspective and proximity luminance.

Active contour configuration model in estimating the posterior ablative margin on image fusion of real-time ultrasound and 3D ultrasound or magnetic resonance images for radiofrequency ablation: an experimental study

Purpose The purpose of this study was to evaluate the accuracy of an active contour model for estimating the posterior ablative margin in images obtained by the fusion of real-time ultrasonography (US) and 3-dimensional (3D) US or magnetic resonance (MR) images of an experimental tumor model for radiofrequency ablation. Methods Chickpeas (n=12) and bovine rump meat (n=12) were used as an experimental tumor model. Grayscale 3D US and T1-weighted MR images were pre-acquired for use as reference datasets. US and MR/3D US fusion was performed for one group (n=4), and US and 3D US fusion only (n=8) was performed for the other group. Half of the models in each group were completely ablated, while the other half were incompletely ablated. Hyperechoic ablation areas were extracted using an active contour model from real-time US images, and the posterior margin of the ablation zone was estimated from the anterior margin. After the experiments, the ablated pieces of bovine rump meat were cut along the electrode path and the cut planes were photographed. The US images with the estimated posterior margin were compared with the photographs and post-ablation MR images. The extracted contours of the ablation zones from 12 US fusion videos and post-ablation MR images were also matched. Results In the four models fused under real-time US with MR/3D US, compression from the transducer and the insertion of an electrode resulted in misregistration between the real-time US and MR images, making the estimation of the ablation zones less accurate than was achieved through fusion between real-time US and 3D US. Eight of the 12 post-ablation 3D US images were graded as good when compared with the sectioned specimens, and 10 of the 12 were graded as good in a comparison with nicotinamide adenine dinucleotide staining and histopathologic results. Conclusion Estimating the posterior ablative margin using an active contour model is a feasible way of predicting the ablation area, and US/3D US fusion was more accurate than US/MR fusion.

From WLR to product reliability and qualifications in the 3D transistor era

Reliability mechanisms associated with HK+MG transistors including latest FinFETs on 14nm technology node will be discussed along with circuit and product implications on reliabilty stresses and qualifications. Reliability efforts made at the transistor module level to circuit, IP blocks, and finally to a product level reliability will be discussed and limiting mechanisms and examples will be highlighted. As part of the product qual strategy, high-speed HTOL and Set level tests were leveraged to signficantly lower product dpms and seamless introduction of high volume manufacturing.

Quantitative analysis of age-dependent backscatter factor (BSF) in x-ray examinations with a Monte Carlo method using XCAT phantoms

The international organizations, including IAEA, have established a diagnostic reference levels (DRLs) for diagnostic xray examinations in order to control doses. The DRLs are mostly expressed as an entrance surface dose (ESD) to quantify dose on the patients. However, there are significant uncertainties associated with the measurements of ESD, and most of them are results from back scatter factor (BSF). The accurate BSF could be determined only by Monte Carlo simulations. In addition, as the human body is much more complicate compared with a commonly used ANSI phantom, for realistic simulation the computational anthropomorphic extended cardiac-torso (XCAT) phantom has to be used in order to obtain accurate BSF. However, to our knowledge, a few BSF values have previously been reported in the literature in x-ray examinations considering patients’ age with XCAT phantom with Monte Carlo methods. The aim of this study was to quantitatively analyze the BSFs using XCAT phantom with Monte Carlo simulation in various x-ray examinations considering the patient’s age. For chest examinations, the BSFs were 1.21, 1.29, and 1.35 for one-year old, seven-year old, and adult patient’s protocol, respectively. For adult patient, the BSFs were 1.35, 1.26, and 1.10 for chest, abdomen, and extremity examinations, respectively. In addition, the ESDs in chest examinations were 36.30 μGy, 52.69 μGy, and 111.80 μGy for one-, seven-year old, and adult patient’s protocol, respectively. These results demonstrated that accurate BSF should be chosen considering the diagnostic examination in order to estimate the ESD properly.

Theoretical characterization of performance effectiveness of photon-counting technique for digital radiography applications

Photon-counting (PC) technique has been paid attention to digital radiography applications due to its potential in lowdose operation and multi-energy imaging capability. In this study, we theoretically investigate the performance gain in digital radiography when the PC detectors are used instead of the conventional energy-integrating (EI) detectors. We use the Monte Carlo technique for estimating energy-absorption distributions in detector materials such as CdTe for the PC detector and CsI for the EI detector. To estimate the signal and noise transfers through the two different detectoroperation schemes, we use the cascaded linear-systems approach. In the Monte Carlo simulations, the square and rectangle focal spots are considered to mimic the advanced carbon nanotube (CNT) and conventional filament cathodes, respectively. From the simulation results, the modulation-transfer functions of the PC detector are more sensitive to asymmetric focal spot geometry than those of the EI detector. On the other hand, the PC detector shows better image signal-to-noise ratio than the EI detector; hence better dose efficiency with the PC detector. The dose efficiency of the PC detector in comparison with the EI detector is however marginal for the filament x-ray beam whereas the dose efficiency is not negligible for the CNT x-ray beam. The theoretical upper limits of the imaging performance of the advanced digital radiography technology are reported in this study.

An 18ms-latency wireless high quality codec SoC for full HD streaming

An SoC integrating both an IEEE 802.11n Wireless LAN (WLAN) and a high quality codec is implemented using 90nm CMOS technology for wireless connectivity between full HD video-supporting devices. The WLAN operates with up to 270-Mbps data rates using 2×3 MIMO technologies and the codec supports up to 1080P 60Hz resolution with 30-bit RGB color format. The system achieves total 18ms latency, which enables this SoC to be used in gaming consoles and PCs as well as full-HD digital TVs with 1.5W power consumption.