Cathodic Functional Layer via Sputtering and Atomic Layer Deposition for Thin-Film Solid Oxide Fuel Cells

이재윤(Jaeyoon Lee),이상혁(Sanghyeok Lee),김현택(Hyeontaek Kim),박용찬(Yongchan Park),이근진(Geunjin Lee),이창헌(Changheon Lee),최성규(Sunggyu Choi),홍순욱(Soonwook Hong) Korean Society for Precision Engineering 2022 한국정밀공학회지 Vol.39 No.2

In this study, Yttria-stabilized zirconia (YSZ) functional layers were applied with different thin-film fabrication process such as sputtering and atomic layer deposition (ALD) to enhance oxygen reduction reaction (ORR) for solid oxide fuel cells. We confirmed that the YSZ functional layer deposited with sputtering showed relatively low grain boundary density, while the YSZ functional layer deposited with the ALD technique clearly indicated high grain boundary density through scanning electron microscopy (SEM) and X-ray diffractometry (XRD) results. The YSZ functional layer coated with the ALD technique revealed that more ORR kinetics can occur using high grain boundary density than the functional layer deposited with sputtering. The peak power density of the SOFC deposited with ALD YSZ indicates 2-folds enhancement than the pristine SOFC.

A cryopreservable cell-laden GelMa-based scaffold fabricated using a 3D printing process supplemented with an in situ photo-crosslinking

JaeYoon Lee,GeunHyung Kim 한국공업화학회 2020 Journal of Industrial and Engineering Chemistry Vol.85 No.-

Scaffolds consisting of cylindrical struts are one of the high-potential tissue engineering materialsbecause the highly porous structure can easily induce cell infiltration/migration and efficiently delivernutrients to the cells. In addition, cryopreservable scaffolds have attracted much interest in tissueengineering because they can be prospective ready-to-use “living” biomaterials consisting of a patient’sown cells. In this study, we investigated a cryopreservable cell-printed scaffold consisting of microscalecylindrical struts. To fabricate the scaffold, we developed a 3D cell-printing system supplemented withmicrofluidic channels, a core-shell nozzle, UV treatment system, and low-temperature working plate. The scaffold consisted of a cell-laden collagen/dimethyl sulfoxide (DMSO) mixture in the core region anda methacrylate gelatin (GelMA)/DMSO mixture in the shell region. After cryopreservation, thepreosteoblasts (MC3T3-E1) loaded in the scaffold showed reasonable cell viability ( 85%). Moreover,no significant difference was observed in the cell proliferations and ALP activities of the cryopreservedscaffold and non-cryopreserved scaffold. Based on these results, we believe that the fabrication processcan be one of the potential techniques for fabricating cryopreservable scaffolds consisting of cylindricalstruts.

New BER Expression of Hierarchical M-ary Phase Shift Keying

Jaeyoon Lee,윤동원,Kyongkuk Cho 한국전자통신연구원 2007 ETRI Journal Vol.29 No.6

In-phase/quadrature (I/Q) imbalances, which are generated by non-ideal transceiver components, are inevitable physical phenomena that cause the performance of practical communication systems to be degraded. In this paper, we provide a new closed-form expression for the bit error rate of hierarchical M-ary phase shift keying with I/Q phase and amplitude imbalances and analyze the effect of I/Q imbalances on BER performance over an additive white Gaussian noise channel.

Enhanced Performance of Field-Effect Transistors Based on Black Phosphorus Channels Reduced by Galvanic Corrosion of Al Overlayers

Lee, Sangik,Yoon, Chansoo,Lee, Ji Hye,Kim, Yeon Soo,Lee, Mi Jung,Kim, Wondong,Baik, Jaeyoon,Jia, Quanxi,Park, Bae Ho American Chemical Society 2018 ACS APPLIED MATERIALS & INTERFACES Vol.10 No.22

<P>Two-dimensional (2D)-layered semiconducting materials with considerable band gaps are emerging as a new class of materials applicable to next-generation devices. Particularly, black phosphorus (BP) is considered to be very promising for next-generation 2D electrical and optical devices because of its high carrier mobility of 200-1000 cm<SUP>2</SUP> V<SUP>-1</SUP> s<SUP>-1</SUP> and large on/off ratio of 10<SUP>4</SUP> to 10<SUP>5</SUP> in field-effect transistors (FETs). However, its environmental instability in air requires fabrication processes in a glovebox filled with nitrogen or argon gas followed by encapsulation, passivation, and chemical functionalization of BP. Here, we report a new method for reduction of BP-channel devices fabricated without the use of a glovebox by galvanic corrosion of an Al overlayer. The reduction of BP induced by an anodic oxidation of Al overlayer is demonstrated through surface characterization of BP using atomic force microscopy, Raman spectroscopy, and X-ray photoemission spectroscopy along with electrical measurement of a BP-channel FET. After the deposition of an Al overlayer, the FET device shows a significantly enhanced performance, including restoration of ambipolar transport, high carrier mobility of 220 cm<SUP>2</SUP> V<SUP>-1</SUP> s<SUP>-1</SUP>, low subthreshold swing of 0.73 V/decade, and low interface trap density of 7.8 × 10<SUP>11</SUP> cm<SUP>-2</SUP> eV<SUP>-1</SUP>. These improvements are attributed to both the reduction of the BP channel and the formation of an Al<SUB>2</SUB>O<SUB>3</SUB> interfacial layer resulting in a high-<I>k</I> screening effect. Moreover, ambipolar behavior of our BP-channel FET device combined with charge-trap behavior can be utilized for implementing reconfigurable memory and neuromorphic computing applications. Our study offers a simple device fabrication process for BP-channel FETs with high performance using galvanic oxidation of Al overlayers.</P> [FIG OMISSION]</BR>

Presence of Night Pain, Neuropathic Pain, or Depressive Disorder Does Not Adversely Affect Outcomes After Total Knee Arthroplasty: A Prospective Cohort Study

Lee Na-Kyoung,Won Samuel Jaeyoon,Lee Jun-Young,Kang Seung-Baik,Yoo So Young,Chang Chong Bum 대한의학회 2022 Journal of Korean medical science Vol.37 No.43

Background: A considerable proportion of patients warranting total knee arthroplasty (TKA) have night pain, neuropathic pain, and/or depressive disorder, which may not be resolved by TKA. This prospective, longitudinal cohort study aimed to document the prevalence of night pain, neuropathic pain, and depressive disorder in patients with advanced knee osteoarthritis undergoing TKA and to determine whether the specific coexisting pain and/or disorder at the time of TKA adversely affected postoperative outcomes. Methods: In this study, 148 patients undergoing TKA were longitudinally evaluated. The presence of night pain, neuropathic pain (determined using Douleur Neuropathique 4 [DN4]) and depressive disorder (determined using the Patient Health Questionnaire-9 [PHQ-9]) was determined before and 6 weeks, 3 months and 1 year after TKA. In addition, Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) and EuroQol-5 Dimension (EQ-5D) scores were assessed before and 1 year after TKA. Potential associations of night pain, neuropathic pain, and/or depressive disorder with pre- and postoperative WOMAC and EQ-5D scores were examined in subgroup analyses. Results: Preoperatively, 72% (n = 106) of patients reported night pain, and the prevalences of neuropathic pain and depressive disorder were 15% and 17%, respectively. Preoperatively, compared with patients without night pain, those with night pain had significantly poorer preoperative WOMAC scores, but no significant difference was seen between groups 1 year after TKA. Preoperatively, the WOMAC, EQ-5D, and EQ-5D health scores of patients with neuropathic pain were not significantly different from those of patients without neuropathic pain, and there was no difference in clinical outcome scores 1 year after TKA between these groups. Preoperatively, the patients with depressive disorder showed significantly poorer preoperative WOMAC, EQ-5D, and EQ-5D health scores than those without depressive disorder, but no significant differences in scores were observed 1 year after TKA between these groups. Conclusion: This study revealed a considerable prevalence of night pain, neuropathic pain, and depressive disorder in patients undergoing TKA and that patients with these specific conditions reported poorer functional and quality of life scores preoperatively. However, such adverse effects disappeared after TKA. Our study findings suggest that TKA can provide satisfactory outcomes for patients with these specific conditions.

Error Performance Analysis of <tex> $M$</tex>-ary <tex> $\theta$</tex>-QAM

Jaeyoon Lee,Dongweon Yoon,Kyongkuk Cho IEEE 2012 IEEE TRANSACTIONS ON VEHICULAR TECHNOLOGY Vol.61 No.3

<P>In this paper, we derive new exact and general expressions for the symbol error rate (SER) and bit error rate (BER) of M-ary θ-quadrature amplitude modulation (QAM) for M = 2<SUP>l</SUP> , I ≥ 4, based on not only square-QAM (SQAM) for M = 2<SUP>2l</SUP>, I ≥ 2 but cross-QAM (CQAM) as well, for M = 2<SUP>2l</SUP>+1, I ≥ 2 in additive white Gaussian noise (AWGN) and various fading channels; we also present the optimum angle and constellation of M-ary θ-QAM. Through computer simulations, we confirm the results of the theoretical analysis. Because the SER and BER expressions are provided in terms of 2-D Gaussian Q-function in AWGN and various fading channels, they will be very useful for numerical evaluations in various cases of practical interest in QAM systems.</P>

Experimental realization of a four-photon seven-qubit graph state for one-way quantum computation.

Lee, Sang Min,Park, Hee Su,Cho, Jaeyoon,Kang, Yoonshik,Lee, Jae Yong,Kim, Heonoh,Lee, Dong-Hoon,Choi, Sang-Kyung Optical Society of America 2012 Optics express Vol.20 No.7

<P>We propose and demonstrate the scaling up of photonic graph states through path qubit fusion. Two path qubits from separate two-photon four-qubit states are fused to generate a two-dimensional seven-qubit graph state composed of polarization and path qubits. Genuine seven-qubit entanglement is verified by evaluating the witness operator. Six qubits from the graph state are used to demonstrate the Deutsch-Jozsa algorithm for general two-bit functions with a success probability greater than 90%.</P>

Glycolytic Flux Signals to mTOR through Glyceraldehyde-3-Phosphate Dehydrogenase-Mediated Regulation of Rheb

Lee, Mi Nam,Ha, Sang Hoon,Kim, Jaeyoon,Koh, Ara,Lee, Chang Sup,Kim, Jung Hwan,Jeon, Hyeona,Kim, Do-Hyung,Suh, Pann-Ghill,Ryu, Sung Ho American Society for Microbiology 2009 Molecular and cellular biology Vol.29 No.14

<B>ABSTRACT</B><P>The mammalian target of rapamycin (mTOR) interacts with raptor to form the protein complex mTORC1 (mTOR complex 1), which plays a central role in the regulation of cell growth in response to environmental cues. Given that glucose is a primary fuel source and a biosynthetic precursor, how mTORC1 signaling is coordinated with glucose metabolism has been an important question. Here, we found that the glycolytic enzyme glyceraldehyde-3-phosphate dehydrogenase (GAPDH) binds Rheb and inhibits mTORC1 signaling. Under low-glucose conditions, GAPDH prevents Rheb from binding to mTOR and thereby inhibits mTORC1 signaling. High glycolytic flux suppresses the interaction between GAPDH and Rheb and thus allows Rheb to activate mTORC1. Silencing of GAPDH or blocking of the Rheb-GAPDH interaction desensitizes mTORC1 signaling to changes in the level of glucose. The GAPDH-dependent regulation of mTORC1 in response to glucose availability occurred even in TSC1-deficient cells and AMPK-silenced cells, supporting the idea that the GAPDH-Rheb pathway functions independently of the AMPK axis. Furthermore, we show that glyceraldehyde-3-phosphate, a glycolytic intermediate that binds GAPDH, destabilizes the Rheb-GAPDH interaction even under low-glucose conditions, explaining how high-glucose flux suppresses the interaction and activates mTORC1 signaling. Taken together, our results suggest that the glycolytic flux regulates mTOR's access to Rheb by regulating the Rheb-GAPDH interaction, thereby allowing mTORC1 to coordinate cell growth with glucose availability.</P>

Exact Error Performance Analysis of Arbitrary 2-D Modulation OFDM Systems with Carrier Frequency Offset

LEE, Jaeyoon,YOON, Dongweon,YOO, Hoon 'Institute of Electronics, Information and Communi 2012 IEICE TRANSACTIONS ON COMMUNICATIONS - Vol.eb95 No.4

Supramolecular fishing for plasma membrane proteins using an ultrastable synthetic host??guest binding pair

Lee, Don-Wook,Park, Kyeng Min,Banerjee, Mainak,Ha, Sang Hoon,Lee, Taehoon,Suh, Kyungwon,Paul, Somak,Jung, Hyuntae,Kim, Jaeyoon,Selvapalam, Narayanan,Ryu, Sung Ho,Kim, Kimoon Nature Publishing Group, a division of Macmillan P 2011 Nature chemistry Vol.3 No.2

Membrane proteomics, the large-scale global analysis of membrane proteins, is often constrained by the efficiency of separating and extracting membrane proteins. Recent approaches involve conjugating membrane proteins with the small molecule biotin and using the receptor streptavidin to extract the labelled proteins. Despite the many advantages of this method, several shortcomings remain, including potential contamination by endogenously biotinylated molecules and interference by streptavidin during analytical stages. Here, we report a supramolecular fishing method for membrane proteins using the synthetic receptor??ligand pair cucurbit[7]uril??1-trimethylammoniomethylferrocene (CB[7]??AFc). CB[7]-conjugated beads selectively capture AFc-labelled proteins from heterogeneous protein mixtures, and AFc-labelling of cells results in the efficient capture of membrane proteins by these beads. The captured proteins can be recovered easily at room temperature by treatment with a strong competitor such as 1,1??bis(trimethylammoniomethyl)ferrocene. This synthetic but biocompatible host??guest system may be a useful alternative to streptavidin??biotin for membrane proteomics as well as other biological and biotechnological applications.