Design and Implementation of Memory-Access-Effective and Power-Consumption-Effective H.264 Decoder

Jongsik Park,Wonjoon Choi,Jeonhak Moon,Hyeon-Cheol Yang,Seok Lee,Seongsoo Lee 대한전자공학회 2008 ICEIC:International Conference on Electronics, Inf Vol.1 No.1

This paper proposes a memory-access-effective and power-consumption-effective H.264 decoder for mobile multimedia applications. To reduce area and power, the proposed H.264 decoder is designed and implemented in fully hardwired architecture. The variable length decoder is implemented without embedded processors, and the common input buffer is used between CAVLC decoder and exp-Golomb decoder. In the deblocking filter, filtering can be skipped on several pixels when some skipping conditions meet. Furthermore, to minimize memory access, intra predictor is merged with motion compensator exploiting internal buffer instead of external memory access.

Iridium-Based Multimetallic Nanoframe@Nanoframe Structure: An Efficient and Robust Electrocatalyst toward Oxygen Evolution Reaction

Park, Jongsik,Sa, Young Jin,Baik, Hionsuck,Kwon, Taehyun,Joo, Sang Hoon,Lee, Kwangyeol American Chemical Society 2017 ACS NANO Vol.11 No.6

<P>Nanoframe electrocatalysts have attracted great interest due to their inherently high active surface area per a given mass. Although recent progress has enabled the preparation of single nanoframe structures with a variety of morphologies, more complex nanoframe structures such as a double-layered nanoframe have not yet been realized. Herein, we report a rational synthetic strategy for a structurally robust Ir-based multimetallic double-layered nanoframe (DNF) structure, nanoframe@nanoframe. By leveraging the differing kinetics of dual Ir precursors and dual transition metal (Ni and Cu) precursors, a core shell-type alloy@alloy structure could be generated in a simple one-step synthesis, which was subsequently transformed into a multimetallic IrNiCu DNF with a rhombic dodecahedral morphology via selective etching. The use of single Ir precursor yielded single nanoframe structures, highlighting the importance of employing dual Ir precursors. In addition, the structure of Ir-based nanocrystals could be further controlled to DNF with octahedral morphology and CuNi@Ir core shell structures via a simple tuning of experimental factors. The IrNiCu DNF exhibited high electrocatalytic activity for oxygen evolution reaction (OER) in acidic media, which is better than Ir/C catalyst. Furthermore, IrNiCu DNF demonstrated excellent durability for OER, which could be attributed to the frame structure that prevents the growth and agglomeration of particles as well as in situ formation of robust rutile II, phase during prolonged operation.</P>

Janus Nanoparticle Structural Motif Control <i>via</i> Asymmetric Cation Exchange in Edge-Protected Cu_1.81S@Ir_<i>x</i>S_<i>y</i> Hexagonal Nanoplates

Park, Jongsik,Park, Jisol,Lee, Jaeyoung,Oh, Aram,Baik, Hionsuck,Lee, Kwangyeol American Chemical Society 2018 ACS NANO Vol.12 No.8

<P>Post-synthetic transformation of nanoparticles has received great attention, because this approach can provide an unusual route to elaborately composition-controlled nanostructures while maintaining the overall structure of the template. In principle, anisotropic heteronanoparticles of semiconductor materials can be synthesized <I>via</I> localized, that is, single site, cation exchange in symmetric nanoparticles. However, the differentiation of multiple identical cation exchange sites in symmetric nanoparticles can be difficult to achieve, especially for semiconductor systems with very fast cation exchange kinetics. We posited that single-site cation exchange in semiconductor nanoparticles might be realized by imposing a significant kinetic hurdle to the cation exchange reaction. The different atomic arrangements of the core and crown in core-crown structures might further differentiate the surface energies of originally identical cation exchange sites, leading to different reactivities of these sites. The first cation exchange site would be highly reactive due to the presence of a formed interface, thereby continuing to act as a site for cation exchange propagation. Herein, we present the proof-of-concept synthesis of Janus nanoparticles by using edge-protected Cu<SUB>1.81</SUB>S@Ir<SUB><I>x</I></SUB>S<SUB><I>y</I></SUB> hexagonal nanoplates. The Janus nanoparticles comprising {Au<SUB>2</SUB>S-Cu<SUB>1.81</SUB>S}@Ir<SUB><I>x</I></SUB>S<SUB><I>y</I></SUB> or {PdS-Cu<SUB>1.81</SUB>S}@Ir<SUB><I>x</I></SUB>S<SUB><I>y</I></SUB> exhibited dissimilar structural motifs due to the disparate cation exchange directions. This synthetic methodology exploiting cation exchange of surface-passivated semiconductor nanoparticles could fabricate the numerous symmetry-controlled Janus heterostructures.</P> [FIG OMISSION]</BR>

FeOF ellipsoidal nanoparticles anchored on reduced graphene oxides as a cathode material for sodium-ion batteries

Park, Miji,Shim, Jae-Hyun,Kim, Hanah,Park, Hansol,Kim, Namyeong,Kim, Jongsik Elsevier 2018 Journal of Power Sources Vol.396 No.-

<P><B>Abstract</B></P> <P>FeOF/reduced graphene oxide (r-GO) nanocomposites are synthesized with approximately 8 and 13 wt% r-GO. The FeOF nanoparticles are fabricated using FeSiF<SUB>6</SUB>⋅6H<SUB>2</SUB>O as a precursor through solvothermal treatment with 1-propanol. This method provides a more reliable and facile wet-chemical route to synthesize phase-pure FeOF without FeF<SUB>2</SUB> and Fe<SUB>2</SUB>O<SUB>3</SUB> impurities, as compared to the annealing process in air. The FeF<SUB>2</SUB> phase is formed as an intermediate during the synthetic process. The prepared FeOF/r-GO sample with 13 wt% r-GO (FeG20) exhibits improved discharge capacity, cycling stability, and rate performance as a cathode material in sodium-ion batteries, compared to the bare FeOF at 1.2–4.0 V. The enhanced electrochemical properties for sodium-ion storage are mainly attributed to the size-controlled FeOF nanoparticles and their intimate contact with the conductive r-GO matrix.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Ellipsoidal FeOF nanoparticles anchored on r-GO were fabricated in a mild condition. </LI> <LI> The particle size of FeOF was decreased with the r-GO contents in the FeOF/r-GO composites. </LI> <LI> The FeOF/r-GO composites show superior electrochemical performances to those of bare FeOF. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>

RuO_x-decorated multimetallic hetero-nanocages as highly efficient electrocatalysts toward the methanol oxidation reaction

Park, Jongsik,Kim, Hee Jin,Oh, Aram,Kwon, Taehyun,Baik, Hionsuck,Choi, Sang-Il,Lee, Kwangyeol The Royal Society of Chemistry 2018 Nanoscale Vol.10 No.45

<P>Direct methanol fuel cell technology awaits the development of highly efficient and robust nanocatalysts driving the methanol oxidation reaction (MOR) in a CO poisoning-free fashion. Thus far, various Pt-based alloy nanoparticles have been studied as electrocatalysts toward the MOR, and it has been found that the introduction of dopants such as Ru and Cu to Pt has been particularly successful in mitigating the CO poisoning problem. Herein, we report a facile synthesis of Ru-branched RuPtCu nanocages that involves <I>in situ</I> formation of Ru-doped PtCu nanoparticles and subsequent outgrowth of Ru branches by insertion of additional Ru precursors. We show that the electrocatalytic activity and stability of Ru branched RuPtCu ternary nanocages toward the MOR are greatly improved compared to those of PtCu/C and RuPtCu/C counterparts and state-of-the-art PtRu/C and Pt/C catalysts, mainly due to the synergy between the CO-tolerant RuOx phase and the highly open and robust RuPtCu nanoframe.</P>

Highly Crystalline Pd₁₃Cu₃S₇ Nanoplates Prepared via Partial Cation Exchange of Cu_1.81S Templates as an Efficient Electrocatalyst for the Hydrogen Evolution Reaction

Park, Jongsik,Jin, Haneul,Lee, Jaeyoung,Oh, Aram,Kim, Byeongyoon,Kim, Ju Hee,Baik, Hionsuck,Joo, Sang Hoon,Lee, Kwangyeol American Chemical Society 2018 Chemistry of materials Vol.30 No.19

<P>Chemical transformations via postsynthetic modification of colloidal nanocrystals have received great attention as a rational synthetic route to unprecedented nanostructures. In particular, the cation exchange reaction is considered as an effective method to alter the composition of the starting nanostructures while maintaining the initial structural characteristics. Herein, we report the synthesis of highly crystalline Pd<SUB>13</SUB>Cu<SUB>3</SUB>S<SUB>7</SUB> nanoplates (NPs) via partial cation exchange of the Cu<SUB>1.81</SUB>S phase by Pd cations, with Cu<SUB>1.94</SUB>S NPs and Pd<SUB>13</SUB>Cu<SUB>3</SUB>S<SUB>7</SUB>/Cu<SUB>2-<I>x</I></SUB>S janus heterostructure as the intermediate phases. The highly crystalline Pd<SUB>13</SUB>Cu<SUB>3</SUB>S<SUB>7</SUB> ternary NPs exhibit excellent electrocatalytic performance toward the hydrogen evolution reaction (HER) under acidic conditions. The HER activity of Pd<SUB>13</SUB>Cu<SUB>3</SUB>S<SUB>7</SUB> NPs with its overpotential as low as 64 mV at −10 mA cm<SUP>-2</SUP> is superior to those of amorphous PdCuS and commercial Pd/C catalysts, demonstrating the importance of nanocrystal crystallinity in boosting the HER activity. They also exhibit excellent stability as compared to commercial Pt/C and Pd/C under strongly acidic conditions.</P> [FIG OMISSION]</BR>

Hollow nanoparticles as emerging electrocatalysts for renewable energy conversion reactions

Park, Jongsik,Kwon, Taehyun,Kim, Jun,Jin, Haneul,Kim, Ho Young,Kim, Byeongyoon,Joo, Sang Hoon,Lee, Kwangyeol The Royal Society of Chemistry 2018 Chemical Society reviews Vol.47 No.22

<P>While the realization of clean and sustainable energy conversion systems primarily requires the development of highly efficient catalysts, one of the main issues had been designing the structure of the catalysts to fulfill minimum cost as well as maximum performance. Until now, noble metal-based nanocatalysts had shown outstanding performances toward the oxygen reduction reaction (ORR), oxygen evolution reaction (OER), and hydrogen evolution reaction (HER). However, the scarcity and high cost of them impeded their practical use. Recently, hollow nanostructures including nanocages and nanoframes had emerged as a burgeoning class of promising electrocatalysts. The hollow nanostructures could expose a high proportion of active surfaces while saving the amounts of expensive noble metals. In this review, we introduced recent advances in the synthetic methodologies for generating noble metal-based hollow nanostructures based on thermodynamic and kinetic approaches. We summarized electrocatalytic applications of hollow nanostructures toward the ORR, OER, and HER. We next provided strategies that could endow structural robustness to the flimsy structural nature of hollow structures. Finally, we concluded this review with perspectives to facilitate the development of hollow nanostructure-based catalysts for energy applications.</P>

A Comparison of Memory Beliefs, Cognitive Activity, and Depression Among Healthy Older Adults, Amnestic Mild Cognitive Impairment, and Patient with Alzheimer's Disease

JongSik Park,Jooyeon Jamie Im,송인욱,Yeonwook Kang 대한노인병학회 2019 Annals of geriatric medicine and research Vol.23 No.1

Background: Amnestic mild cognitive impairment (aMCI) is highly likely to progress to dementia of the Alzheimer type (DAT). One of the most frequently reported symptoms in aMCI and DAT patients is memory impairment. This study compared the levels of beliefs about memory efficacy and control, cognitive activity, and depression among healthy older adults (OA), patients with aMCI, and patients with DAT. Methods: This study included 21 OA (11 males, 10 females), 16 aMCI patients (6 males, 10 females), and 18 DAT patients (10 males, 8 females). The memory efficacy questionnaire, memory control questionnaire, cognitive activity questionnaire, depression questionnaire, and Seoul Verbal Learning Test were administered to all subjects. Results: DAT patients showed significantly lower scores on the recognition test than did the OA and aMCI patients, and no difference in these scores was observed between the OA and aMCI patients. Regarding the memory efficacy, memory control, and cognitive activity questionnaires, DAT and aMCI patients showed significantly lower scores than did OA. However, there were no differences in these scores between aMCI and DAT patients. Conclusion: The results of this study suggest that aMCI patients experienced impairment in memory beliefs and memory control in the same way as DAT patients did. These results suggest that the early application of cognitive rehabili-tation therapy for patients with aMCI may be effective in preventing or alleviating memory deterioration.

Design of Memory-Access-Effective H.264 Intra Predictor Integrated with Motion Compensator

Jongsik Park,Jae-Kyung Wee,Hanku Lee,Seongsoo Lee 대한전자공학회 2008 ICEIC:International Conference on Electronics, Inf Vol.1 No.1

In H.264 decoder, intra prediction is a powerful tool for higher compression efficiency from correlation removal of adjacent samples in spatial domain. Therefore, intra predictor requires reference images for adjacent samples. Also, motion compensator and deblocking filter require reference images stored in external memory. They read external frame memory very frequently. Thus, H.264 decoder suffers from frequent memory access. This paper proposes an intra predictor integrated with motion compensator without external frame memory. It was synthesized in 0.18 ㎛ standard cell library. The total gate count, the maximum operating frequency, and the maximum throughput are about 284K gates, 108㎒, CIF 30 fps, respectively.

One pot synthesis of nanoscale phase-segregated PdPt nanoarchitectures via unusual Pt-doping induced structural reorganization of a Pd nanosheet into a PdPt nanotent.

Park, Jongsik,Oh, Aram,Baik, Hionsuck,Choi, Yong Soo,Kwon, Seong Jung,Lee, Kwangyeol RSC Pub 2014 Nanoscale Vol.6 No.18

<P>Pt-doping of an ultrathin Pd nanosheet results in the unprecedented structural rearrangement of a Pd nanosheet into a PdPt nanotent structure, in which a tripod stands on a triangular nanosheet. Further growth of Pt phase on this nanotent structure is dependent on the presence of surface-stabilizing CO molecules, leading to the formation of two distinct nanoscale phase segregated structures with respective structural features of a popped out Pt facet and an overgrown Pt layer.</P>