Suwon Lee

Substrate dependence on the optical properties of Al2O3 films grown by atomic layer deposition

The atomic layer deposition technique has been applied to the growth of Al2O3 thin films on the substrates of Si(100), 100-nm-thick SiO2 covered Si(100) [SiO2/Si(100)], and 90-nm-thick TiN covered SiO2/Si(100). The growth rate of Al2O3 films was 0.19 nm/cycle and identical for all substrates employed under the surface controlled process. However, the optical properties of Al2O3 films were significantly affected by different substrates. The average interband-oscillator energy and refractive index parameter were determined to be 3.330 eV and 2.992×10−14 eV m2 for Al2O3 film grown on Si(100), while those for the film grown on SiO2/Si(100) were 4.492 eV and 2.074×10−14 eV m2, respectively.

1060nm vertical-external-cavity surface-emitting lasers with an optical-to-optical efficiency of 44% at room temperature

We report a high power fundamental transverse mode operation of an optically pumped 1060nm vertical-external-cavity surface-emitting laser. A diamond heat spreader was capillary bonded to the semiconductor surface. A 10W continuous wave operation with optical-to-optical conversion efficiency of 44% was achieved at room temperature. The thermal rollover was not found up to a heat sink temperature of 60°C. High efficiency and good thermal stability were mainly due to the optimization of epitaxial quality and the high conductivity of the diamond heat spreader. We have found that the increase of the round trip loss caused by the heat spreader was about 1%.

49.1: New Concept for Improvement of White Color Balance in Hologram Back-light Units

We have improved a white color balance using multi-grating period structure in the holographic backlight units that can be applicable to mobile LCD panel where several LEDs are placed at edge of guide plate as light sources. New H-LGP is based on the characteristics of grating and its diffraction angle can be determined by specific grating period. With this idea, hologram backlight unit can realize not only lower weight and less power consumption but also higher light utilization by eliminating couple of prismatic sheets which have been widely used in conventional unit inevitably.

Holographic backlight unit for mobile LCD devices

— The commercial backlight unit for a portable liquid-crystal display (LCD) device typically consists of several light-emitting diodes (LEDs) as the light source, a couple of prismatic sheets and diffusers, and a guide plate for backlight optics. A simplified backlight unit for portable LCDs, merely consisting of a hologram-imprinted light-guide plate (H-LGP) and one diffuser, is proposed in this paper. By employing H-LGP, it is expected that several optical films essential to the conventional backlight unit can be eliminated. This paper aims to improve the optical efficiency of LGPs by deriving the design parameters of the H-LGP and performing the related computations. The angular luminance distribution of the emanating light from H-LGP has been measured and compared with the results obtained by simulation. A proper collimation is necessary in order to increase the luminance. The backlight developed through this work has high optical performance combined with low cost.

Channel error and handoff compensation scheme for fair queueing algorithms in wireless networks

In order to extend fair queueing algorithms to wireless networks, we propose a channel error and handoff compensation scheme based on a compensation session with a priority swapping mechanism. The proposed compensation scheme provides a short-term fairness guarantee for an error-free session, long-term fairness guarantee for an erroneous session, fast handoff and traffic-specific control.

Mobile data service QoE analytics and optimization

Quality of Experience (QoE) has emerged as the key performance metric to evaluate end-user service quality perception. We propose a system for video and web QoE assessment in LTE networks that we call QoE Analytics system. We build the proposed system and run it on a LTE network and successfully estimates QoE metrics per UE in real-time by inspecting user plane data on S1 interface without any QoE report from UEs. QoE metrics measured by QoE Analytics are verified to be in close match to actual UE observations such as initial playout delay, rebuffering percentage and rebuffering duration for video applications and download time for web traffic. Optimization of eNB scheduler performance based on this real-time QoE Analytics feedback is demonstrated by video QoE-aware scheduler and a significant improvement in QoE metrics is observed in congested situation.

Multimedia Mobility Service Solution

In this paper we provide the description of a new mobility service for an IP Multimedia Subsystem (IMS) platform. It optimizes the operation of multimedia services in a wireless heterogeneous environment containing multiple access networks with different cost per bandwidth ratio. It extends the SIP Presence Service with mobility related information, i.e. Media Independent Handover (MIH). The terminals are able to exchange specific handover knowledge with the remote service provisioning infrastructure and to receive commands adapted to the profile of all the parties involved in multimedia sessions, transparent to the actual multimedia service. The system was designed to enable the adaptation of multimedia sessions to the profile of the users and to the momentary network conditions on an end-to-end basis.

1053 TREATMENT WITH CLEVUDINE FOR 24 WEEKS RESULTS IN SUSTAINED ANTIVIRAL RESPONSE ASSOCIATED WITH CONTINUED HBsAg DECREASE 24 WEEKS POST-TREATMENT IN HBeAg-POSITIVE PATIENTS

viral replication, with mean maximum reductions in HCVRNA ranging from −0.97 to −2.13 (log10 IU/mL). In this study, the safety and efficacy of FBV in combination with pegylated interferon alfa-2a (pegIFN) and ribavirin (RBV) was evaluated. Methods: Eligible patients (treatment naive, HCV genotype 1) were randomized 1:1:1:1 to receive FBV (200, 300 or 500mg BID) or placebo in combination with pegIFN (180 ug/wk) and RBV (1000/1200mg/day) for 4 weeks. Patients are continuing on open label pegIFN/RBV for an additional 44 weeks. Results from the Week 4 analysis are described here. HCVRNA was measured using the Roche COBAS Taqman (LLD= 25 IU/mL). Results: A total of 35 patients were enrolled and 34 completed Week 4. The majority were Caucasian (69%), genotype 1a (80%) and male (51%). The most frequently reported AEs were headache, fatigue, insomnia and nausea. There were no trends towards increased frequency or severity of AEs with increasing dose of FBV. The incidence and severity of laboratory test abnormalities was similar across treatment groups. There was one treatment-related SAE (elevated creatinine) in the FBV 300mg group, which resolved following IV hydration. No other renal AEs were reported. The mean reduction (log10 IU/mL) in HCVRNA at Day 4 for placebo (n = 8), 200 (n = 10), 300 (n = 9) and 500 (n = 8) mg BID was −0.58, −2.29, −2.72 and −2.83, respectively, and −2.10, −4.46, −4.67 and −3.62 at Day 28. The percent of patients achieving RVR (undetectable HCVRNA by Week 4) for placebo, 200, 300 and 500mg BID was 0%, 60%, 75% and 63%, respectively. Of those patients treated with 200, 300 and 500mg BID who achieved a RVR, 33%, 33% and 80% achieved undetectable HCVRNA within two weeks of treatment, respectively. Conclusions: The addition of FBV to pegIFN/RBV was well tolerated and markedly increased the percentage of patients achieving RVR. Assessment of response to pegIFN/RBV therapy subsequent to Week 4 is ongoing.

Delay and data rate decoupled fair queueing for multimedia services in wireless networks

This paper proposes a delay and data rate decoupled fair queueing scheme for wire-less multimedia, where two separate scheduling algorithms are applied respectively for real time and non-real time flows. For real time flows, we propose an explicit-delay-guarantee algorithm to guarantee the delay deadline, while a conventional fair queuing algorithm is adopted for non-real time flows to guarantee fairness and throughput requirements. In erroneous wireless channel, resource swapping is further adopted to guarantee the required quality of service. In addition, a real time flow can easily react to varying channel error condition by controlling the trans-mission order using allocation window and accelerating factor without degrading the performance of other real time flows. Through simulations, it is shown that the proposed scheme provides not only improved performance in terms of delay but also simplified control operation in dynamic channel error condition.