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Hyungwoo Lee,Kyung Eun Kang,Hyewon Chung,Hyung Chan Kim 대한안과학회 2018 Korean Journal of Ophthalmology Vol.32 No.2
Purpose: To investigate the prognostic factors of visual and anatomic outcomes in patients with diabetic macular edema (DME) treated with intravitreal injection of dexamethasone implant. Methods: We retrospectively studied 32 eyes of 31 patients with DME for best-corrected visual acuity (BCVA), central macular thickness, and height and width of both intraretinal fluid (IRF) and subretinal fluid. Logistic regression analysis was used to examine correlations between the baseline characteristics and outcomes at 3 and 6 months. Results: Baseline predictor of BCVA ≥20 / 40 at month 3 was short height of baseline IRF (p = 0.02), while good baseline BCVA was a predictor for month 6 (p = 0.01). Predictors of improvement in logarithm of minimum angle of resolution BCVA 0.2 at month 3 were the absence of baseline IRF and poor baseline BCVA (p = 0.02 and p = 0.009, respectively), while poor baseline BCVA was the sole predictor at month 6 (p = 0.01). Predictor of central macular thickness ≤300 μm at month 3 was younger age (p = 0.03), while the absence of IRF was the predictor for BCVA improvement at month 6 (p = 0.02). BCVA ≤20 / 100 at month 3 was predicted by poor baseline BCVA (p = 0.01), and increased width of total IRF was the predictor at month 6 (p = 0.02). Predictor of loss of logarithm of minimum angle of resolution BCVA 0.2 at month 6 was increased width of total IRF at baseline (p = 0.04). Additional injection within 6 months was negatively associated with the presence of baseline DME (p = 0.03). Conclusions: The visual and anatomical outcome of DME treatment with dexamethasone implant can be predicted by baseline visual acuity and IRF morphology.
Tomlinson-harashima precoder with tilted constellation for reducing transmission power
Jiwon Kang,Hyungwoo Ku,Dong-Seung Kwon,Chungyong Lee IEEE 2009 IEEE TRANSACTIONS ON WIRELESS COMMUNICATIONS Vol.8 No.7
<P>Tomlinson-Harashima precoder (THP) is being noted for an efficient alternative to dirty paper coder. THP increases the transmission power due to the use of the modulo operator. In this paper, we propose a method that reduces the transmission power by tilting the constellations of the transmit data symbols. The symbol error rate (SER) is improved for a fixed SNR by reducing the transmission power. Average transmission power is calculated asymptotically by using an extreme value distribution. We have shown that the transmission power can be significantly reduced when we use the tilted constellation THP. As the transmission power determines the SER slope, at high SNRs we achieve lower SER than in the case of a transmission over an AWGN channel. The tilted angle can be estimated at the receiver. An angle estimation algorithm is proposed that optimizes angle estimation error and SER.We use the approximation of the angle estimation error and SER to find an optimum number of tilted angles. By using the proposed angle estimation algorithm and the optimum number of tilted angles, the tilted constellation THP always outperforms the conventional THP algorithm.</P>
Ko, Hyungwoo,Kim, Jongsu,Kang, Myounggon,Shin, Hyungcheol Elsevier 2017 Solid-State Electronics Vol.136 No.-
<P><B>Abstract</B></P> <P>In this work, dual-<I>k</I> spacer structures are investigated using a variety of materials along the high-k spacer length in detail. It is known that not only the higher permittivity materials of high-<I>k</I> spacer boost the on-current but also lower permittivity materials of low-<I>k</I> spacer effectively reduce the off-current. By compared the results of other various single spacers and dual-<I>k</I> spacers, it is HfO<SUB>2</SUB>/Vacuum dual-<I>k</I> spacer that shows relatively higher I<SUB>ON</SUB>, I<SUB>ON</SUB>/I<SUB>OFF,</SUB> better immunity of short channel effects and outstanding device performances.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Using lower ε<SUB>lk</SUB> for outer-spacer of dual-<I>k</I> structure can reduce the total capacitance as the level of single ε<SUB>lk</SUB> spacer. </LI> <LI> Using higher ε<SUB>hk</SUB> for inner-spacer of dual-<I>k</I> structure boosts the on-current as the same range of single ε<SUB>hk</SUB> spacer due to the gate-fringing field effect. </LI> <LI> At the off-state, most of drain potential is dropped to the outer spacer capacitance and has little effect to the channel. Thus, using lower ε<SUB>lk</SUB> for outer spacer shows the lower off-current, SS<SUB>avg</SUB> and DIBL. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>