New Process Development and Practical Applications for Binder Jet Printing (BJP)

Patrick Kwon 한국생산제조학회 2018 한국생산제조시스템학회 학술발표대회 논문집 Vol.2018 No.10

Predicting semantic features in Chinese: Evidence from ERPs

Kwon, Nayoung,Sturt, Patrick,Liu, Pan Elsevier 2017 Cognition Vol.166 No.-

<P><B>Abstract</B></P> <P>This article reports two ERP studies that exploited the classifier system of Mandarin Chinese to investigate semantic prediction. In Mandarin, in certain contexts, a noun has to be preceded by a classifier, which has to match the noun in semantically-defined features. In both experiments, an N400 effect was elicited in response to a classifier that mismatched an up-coming predictable noun, relative to a matching classifier. Among the mismatching classifiers, the N400 effect was graded, being smaller for classifiers that were semantically related to the predicted word, relative to classifiers that were semantically unrelated to the predicted word. Given that the classifier occurred before the predicted word, this result shows that fine-grained semantic features of nouns can be pre-activated in advance of bottom-up input. The studies thus extend previous findings based on a more restricted range of highly grammaticalized features such as gender or animacy in Indo-European languages (Szewczyk & Schriefers, 2013; Van Berkum, Brown, Zwitserlood, Kooijman, & Hagoort, 2005; Wicha, Bates, Moreno, & Kutas, 2003).</P> <P><B>Highlights</B></P> <P> <UL> <LI> Using the classifier system of Mandarin, this study investigated semantic prediction. </LI> <LI> N400s were elicited at the classifier position before the predicted noun. </LI> <LI> In addition, the effect was modulated by semantic relatedness to the predicted noun. </LI> <LI> The results suggest semantic features are pre-activated before the bottom-up input. </LI> <LI> They also suggest that prediction of semantic features could be fine-grained. </LI> </UL> </P>

Nanocrystal heterostructures of LiCoO₂ with conformal passivating shells

Kwon, Bob Jin,Phillips, Patrick J.,Key, Baris,Dogan, Fulya,Freeland, John W.,Kim, Chunjoong,Klie, Robert F.,Cabana, Jordi The Royal Society of Chemistry 2018 Nanoscale Vol.10 No.15

<P>Stabilization of electrode-electrolyte interfaces is required to increase the energy stored in battery electrodes. Introducing redox-inactive ions on the electrode surface minimizes deleterious side reactions without affecting the bulk properties. A synthetic challenge exists to grow such layers conformally at each primary particle, to fully passivate interfaces that are buried in the final electrode architecture. The development of methods of sequential colloidal growth of complex oxides and overlayers, enabled by surfactant interactions, would provide novel means to advance toward this goal. Here, nanocrystals composed of LiCoO2, a commercially relevant material for high energy devices, were grown with a shell enriched in Al<SUP>3+</SUP>, deposited conformally through a one-pot colloidal synthetic method. The effects of synthetic conditions on the composition of the Al-rich shell and the corresponding electrochemical performance were investigated. The modified nanocrystals showed enhanced electrochemical properties, while maintaining carrier transport.</P>

Wear Characteristic on BAM Coated Carbide Tool in Drilling of Composite/Titanium Stack

박경희,Patrick Kwon,Dave (Dae-Wook) Kim 한국정밀공학회 2012 International Journal of Precision Engineering and Vol. No.

This paper studied characteristics on a BAM coated carbide, which comes from a ceramic alloy of boron, aluminum,magnesium, etc., in drilling of CFRP and titanium (Ti) stacks. A series of drilling test was performed starting from drilling of CFRP (top) to Ti (bottom) in the stacks using uncoated tungsten carbide (WC) and BAM coated WC. The BAM coating,which is known for one of the hardest and slipperiest materials. In this regard, BAM coating can be used for cutting tool by reducing the adhesion of work material and interfacial friction. Tool surfaces were periodically measured during the drilling tests using scanning electron microscope (SEM), energy dispersive X-ray spectroscopy (EDS) and confocal laser scanning microscope (CLSM) in order to analyze the tool wear evolution and metallurgical changes on the tool surface. From the experiment, it was observed that no major wear occurred on rake surface and center of the tool while flank wear was significant. The wear mechanisms on flank surface were abrasion and titanium adhesion. The abrasion wear took place by the hard carbon fibers in CFRP and the hard inclusions in titanium. On the other hand, the adhesive wear occurred by pulling out the carbide grains when the adhered titanium layers detached from the tool surface. BAM coated carbide tool showed substantially reduced Ti adhesion especially at high cutting speed. In addition, the lower flank wear was observed for BAM coated tool compared with for uncoated carbide tool.

Rapid and Tunable Reductive Degradation of Disulfide‐Labeled Polyesters

Pinnel, Patrick,Mendez‐,Nelson, Andrew,Noh, Seung Man,Nam, Joon Hyun,Oh, Jung Kwon WILEY‐VCH Verlag 2012 Macromolecular chemistry and physics Vol.213 No.6

<P><B>Abstract</B></P><P>A new approach for rapid and tunable degradation of reductively degradable polyesters (ssPESs) with multiple disulfides on the polymer backbones is reported. The approach centers on the control of the amount of disulfides in the synthesis of ssPESs by polycondensation of a disulfide‐containing diacid with various single and mixed diols having different molecular weights and disulfides. The disulfide concentration in ssPESs is tuned by incorporation of diols labeled with disulfides or diols with different MWs. The degradation rate is enhanced with increasing ssPES molecular weight. With ssPESs bearing disulfides positioned repeatedly along the backbone, the rapid and controlled degradation is compared with the slow degradation of polyesters with only a single disulfide in the center.</P>

Synergistic protective effect of a BN-carbon separator for highly stable lithium sulfur batteries

Kim, Patrick Joo Hyun,Seo, Jihoon,Fu, Kun,Choi, Junghyun,Liu, Zhiming,Kwon, Jiseok,Hu, Liangbing,Paik, Ungyu Nature Publishing Group 2017 NPG Asia Materials Vol.9 No.-

<P>Lithium sulfur (Li-S) batteries have drawn much attention as next-generation batteries because of their high theoretical capacity (1672 mAh g(-1)), environmental friendliness and low cost. However, several critical issues, which are mainly associated with the polysulfide shuttling effect, result in their poor electrochemical performance. Carbon-modified separators have been introduced to attempt to address these systemic challenges. However, this approach focused only on the suppression of dissolved polysulfides on the cathodic side without considering the further entrapment of polysulfides on the anodic side. In this study, we first designed a multifunctional trilayer membrane comprising a carbon layer and a boron nitride (BN) layer to facilitate the electrochemical performance of Li-S batteries and protect the Li anode from unexpected side reactions. When a BN-carbon separator was employed, the sulfur cathode delivered stable capacity retention over 250 cycles and an excellent specific capacity (702 mAh g(-1)) at a high current density (4 C). The BN-carbon separator also facilitated the uniform plating/striping of Li and, thus, suppressed the severe growth of dendritic Li on the electrode; this led to the stable operation of the Li anode with a high Coulombic efficiency and improved cycling performance.</P>

Functionally Gradient Coatings using Double Feeding in Thermal Plasma Spraying

Neo Kang,Patrick Choo,Tedd Hwang,Yven Chung,Sik-Chol Kwon 한국표면공학회 2023 한국표면공학회 학술발표회 초록집 Vol.2023 No.11-1

Area-Time Efficient Implementation of the Elliptic Curve Method of Factoring in Reconfigurable Hardware for Application in the Number Field Sieve

Gaj, Kris,Soonhak Kwon,Baier, Patrick,Kohlbrenner, Paul,Hoang Le,Khaleeluddin, Mohammed,Bachimanchi, Ramakrishna,Rogawski, Marcin IEEE 2010 IEEE Transactions on Computers Vol.59 No.9

<P>A novel portable hardware architecture of the Elliptic Curve Method of factoring, designed and optimized for application in the relation collection step of the Number Field Sieve, is described and analyzed. A comparison with an earlier proof-of-concept design by Pelzl et al. has been performed, and a substantial improvement has been demonstrated in terms of both the execution time and the area-time product. The ECM architecture has been ported across five different families of FPGA devices in order to select the family with the best performance to cost ratio. A timing comparison with the highly optimized software implementation, GMP-ECM, has been performed. Our results indicate that low-cost families of FPGAs, such as Spartan-3 and Spartan-3E, offer at least an order of magnitude improvement over the same generation of microprocessors in terms of the performance to cost ratio, without the use of embedded FPGA resources, such as embedded multipliers.</P>

Clinical Usefulness of a Cell-based Assay for Detecting Myelin Oligodendrocyte Glycoprotein Antibodies in Central Nervous System Inflammatory Disorders

Seok Jin Myoung,Waters Patrick,Jeon Mi Young,Lee Hye Lim,Baek Seol-Hee,Park Jin-Sung,Kang Sa-Yoon,Kwon Ohyun,Oh Jeeyoung,Oh Jeeyoung,Park Kyung-Ah,Oh Sei Yeul,Kim Byoung Joon,Min Ju-Hong 대한진단검사의학회 2024 Annals of Laboratory Medicine Vol.44 No.1

Background: The clinical implications of myelin oligodendrocyte glycoprotein autoantibodies (MOG-Abs) are increasing. Establishing MOG-Ab assays is essential for effectively treating patients with MOG-Abs. We established an in-house cell-based assay (CBA) to detect MOG-Abs to identify correlations with patients’ clinical characteristics. Methods: We established the CBA using HEK 293 cells transiently overexpressing full-length human MOG, tested it against 166 samples from a multicenter registry of central nervous system (CNS) inflammatory disorders, and compared the results with those of the Oxford MOG-Ab-based CBA and a commercial MOG-Ab CBA kit. We recruited additional patients with MOG-Abs and compared the clinical characteristics of MOG-Ab-associated disease (MOGAD) with those of neuromyelitis optica spectrum disorder (NMOSD). Results: Of 166 samples tested, 10 tested positive for MOG-Abs, with optic neuritis (ON) being the most common manifestation (4/15, 26.7%). The in-house and Oxford MOG-Ab CBAs agreed for 164/166 (98.8%) samples (κ=0.883, P<0.001); two patients (2/166, 1.2%) were only positive in our in-house CBA, and the CBA scores of the two laboratories correlated well (r=0.663, P<0.001). The commercial MOG-Ab CBA kit showed one false-negative and three false-positive results. The clinical presentation at disease onset differed between MOGAD and NMOSD; ON was the most frequent manifestation in MOGAD, and transverse myelitis was most frequent in NMOSD. Conclusions: The in-house CBA for MOG-Abs demonstrated reliable results and can potentially be used to evaluate CNS inflammatory disorders. A comprehensive, long-term study with a large patient population would clarify the clinical significance of MOG-Abs.

A Tribological Study of Vegetable Oil Enhanced by Nano-platelets and Implication in MQL Machining

Trung Kien Nguyen,Patrick Kwon,Inwhan Do 한국정밀공학회 2012 International Journal of Precision Engineering and Vol. No.

Minimum Quantity Lubrication (MQL)-based machining process has many merits over not only conventional flood cooling machining but also dry machining. These merits include cost reduction, industrial hygiene, reduction of air-bourn particles etc.. However, few disadvantages make the MQL-based machining process impractical to be adopted in many industrial production settings. More specifically, the cutting speed in a typical MQL process is restricted because the MQL process does not allow efficient cooling of cutting tools. The amount of oil used in MQL processes is barely enough for less aggressive machining conditions and does not effectively cool the cutting tool essential in more aggressive cutting conditions. At high cutting speeds, the oil will simply evaporate or disintegrate as soon as the oil droplets strike the tools already heated to high cutting temperatures. In this paper, new nano-platelet-enhanced MQL oils are developed to mitigate this major deficiency of MQL process. In particular, exfoliated Graphite nano-platelet (xGnP) and XGS Hexagonal Boron Nitride (hBN) produced by XG Science, Inc. (Lansing, Michigan) were mixed into a typical vegetable oil used in MQL process. The process enhancement by these nano-platelets is possible because these nano-platelets in a multiple-layer scheme can readily slide to provide additional lubricity. When the mixture of oil and nano-platelets are applied, the nanoplatelets provide additional lubricity even after the oil droplets have been disintegrated during high speed machining. Thus,the enhancement achieved by adding nano-platelets allows us to expand the processing envelope of MQL. In this paper, not only the comparison between xGnP and XGS hBN but also multiple combinations of nano-platelet-enhanced MQL oils with varying contents have been studied with a ball-on-disc set-up in a reciprocating motion in order to study the friction and wear characteristics of these lubricants. More importantly, MQL-based ball-milling experiment has been conducted with these mixtures, which show very promising results for future MQL research.