Quantitative iDPC-STEM observations of oxygen octahedral connectivity control at perovskite oxide interfaces via epitaxial strain engineering

Junsik Mun,Eun Kyo Ko,Tae Won Noh,Miyoung Kim 한국자기학회 2021 한국자기학회 학술연구발표회 논문개요집 Vol.31 No.2

Since the oxygen octahedral rotation (OOR) of ABO₃ perovskite oxide provides various functionalities, controlling the OOR plays an important role in device applications development and fundamental physics exploration. One of the most efficient ways to control the OOR is using the oxygen octahedral coupling at heterointerfaces which have two different structural symmetries. Thanks to the interfacial coupling, structures that cannot be accessed in bulk can be realized in thin films. For exploring further functionalities, investigating and engineering the length-scale of the interfacial coupling is an important issue. However, precise length-scale and control method of the oxygen octahedral coupling remain open questions. Here, we made SrRuO₃/SrTiO₃ (SRO/STO) heterostructure on various substrates by pulsed laser deposition and succeeded controlling the length-scale of the oxygen octahedral coupling via epitaxial strain. Since SRO has a<SUP>-</SUP>b<SUP>+</SUP>c<SUP>-</SUP> (in pseudo-cubic notation) and STO has a<SUP>0</SUP>a<SUP>0</SUP>c<SUP>0</SUP> rotating pattern, we could observe how the a<SUP>0</SUP>a<SUP>0</SUP>c<SUP>0</SUP> symmetry of STO penetrates into SRO. The precise OOR angle depending on the each atomic layer was investigated using integrated differential phase contrast-scanning transmission electron microscopy (iDPC-STEM) technique. We found that the critical thickness for saturated OOR angle is engineered via epitaxial strain from 3 unit cells to 13 unit cells of SRO. This study provides an effective method to control the oxygen octahedral interfacial coupling, and suggests a potential model system for investigating how the interfacial coupling occurs between the two different symmetries.

Enhanced Superconductivity of Sr₂RuO₄ and La<SUB>2-x</SUB>Sr<SUB>x</SUB>CuO₄ Thin Films by Atomic-Scale Interface Engineering

Jinkwon Kim,Junsik Mun,Youngdo Kim,Bongju Kim,Jeong Rae Kim,Lingfei Wang,Miyoung Kim,Changyoung Kim,Jason W. A. Robinson,Yoshiteru Maeno,Tae Won Noh 한국자기학회 2021 한국자기학회 학술연구발표회 논문개요집 Vol.31 No.2

Ruddlesden-Popper (RP) phase oxides (An+1BnO3n+1, n = 1, 2, ...) have been spotlighted with versatile physical properties such as high-temperature superconductivity, colossal magnetoresistance. These emergent phenomena provide a platform for novel oxide-based electronic devices including spintronics application. However, high-quality RP-phase thin film growth has been disturbed by extended structural defects, such as out-of-phase boundaries (OPBs). OPB is a translational boundary between neighboring unit cells, shifted in a specific crystallographic direction. For instance, if RP-phase thin films grown on ABO₃ perovskite substrates, the structural mismatch between film and substrates induces a crystallographic shift in the c-axis direction, thus OPBs form at the film-substrate interface. Since OPB formation hampers the physical properties of RP-phase thin films, the suppression of the structural defects is highly required to carry out the high-performance RP-phase based functional devices. In this study, we suppressed OPB suppression in RP-phase oxide thin films by atomic-scale interface engineering. As model systems, the unconventional superconductor Sr₂RuO₄ (bulk Tc ~ 1.5 K) and La2-xSrxCuO₄ (bulk Tc ~ 39 K) thin films were employed. Despite the structural similarities between films and substrates, Sr2RuO4 and La2-xSrxCuO₄ films exhibited huge OPB formations. By controlling the atomic-scale interface engineering, the OPBs were significantly suppressed in the film structure. Notably, these OPB-free Sr₂RuO₄ and La2-xSrxCuO₄ thin films exhibited highly enhanced superconductivity than the film with huge OPB formation. Our study suggests a comprehensive method to suppress OPB formation in RP thin films, enabling superconducting spintronics devices based on the unconventional superconductivity.

연료별 자동차의 주행모드 조건에 따른 연비 및 배출가스 특성 평가

강은정(Eunjeong Kang),전문수(Mun Soo Chon),엄준식(Junsik Um),김경훈(Kyounghun Kim),서영호(Youngho Seo) 한국자동차공학회 2015 한국자동차공학회 부문종합 학술대회 Vol.2015 No.5

Currently the vehicle exhaust gas regulation has been strengthened, Research to improve the exhaust gas after-treatment device development technology and the exhaust performance of the vehicle is making efforts In order to satisfy the regulatory. The purpose of this study is analysis to Characteristics evaluation of fuel economy and emission according to driving mode conditions of The vehicle by fuel type. The test vehicles were selected by each of the fuel according to the difference in displacement volume. These were used four representative mode(FTP-75, NEDC, US06 and SC03) in order to evaluation fuel economy and emission gas. Domestic certification emissions measurement test mode was conduct after the vehicle was soaking for a long time. It is standard condition. Additionally, the test conditions were carried out for warm-up air conditioner condition. Warm-up air conditioner condition was performed the test while it is running the air conditioner after the engine fully warmed up.

Enhanced functionalities in Ruddlesden-Popper oxide thin films employing single-terminated substrate surfaces

Jinkwon Kim,Youngdo Kim,Junsik Mun,Jeong Rae Kim,Miyoung Kim,Changyoung Kim,Tae Won Noh 한국자기학회 2021 한국자기학회 학술연구발표회 논문개요집 Vol.31 No.1

Over the past decades, Ruddlesden-Popper (RP) phase oxides (A_n+1B_nO_3n+1, n = 1, 2, ...) have been spotlighted with advantageous physical properties such as high-temperature superconductivity, giant magnetoresistance. ^[1-2] These emergent phenomena provide a platform for novel oxide-based electronic devices including spintronics application. However, high-quality RP-phase thin film growth has been disturbed by extended structural defects, so-called out-of-phase boundaries (OPBs).^[3] OPB is a translational boundary between neighboring unit cells, shifted in a specific crystallographic direction. For instance, if RP-phase thin films grown on ABO₃ perovskite substrates, the structural mismatch between film and substrates induces a crystallographic shift in the c-axis direction, thus OPBs form at the film-substrate interface. Since OPB formation hampers the physical properties of RP-phase thin films, the suppression of the structural defects is highly required to carry out the high-performance RP-phase based functional devices.^[4-5] In this study, we suppressed OPB suppression in RP-phase oxide thin films by using single-terminated LaSrAlO4 substrate (n = 1 RP phase, a = b= 3.756 Å and c =12.636 Å). As a model system, the high-T_c cup rates superconductor La_1.85Sr_0.15CuO4 thin film (n = 1 RP phase, a = b= 3.777 Å and c =13.226 Å) was employed. Despite the structural similarities between films and substrates, the La_2-xSr_xCuO₄ films exhibited huge OPB formations when deposited on mixed-terminated LaSrAlO4 substrate. In contrast, when the La_2-xSr_xCuO₄ films were deposited on single-terminated LaSrAlO4 substrates, the OPBs were significantly suppressed in the film structure. Notably, these OPB-free La_2-xSr_xCuO₄ films exhibited highly enhanced superconductivity (T_c^zero ~ 30 K) than the film with huge OPB formation (T_c^zero ~ 5 K) under the same thickness (~ 6.5 nm). Our study suggests a comprehensive method to suppress OPB formation in RP thin films, enabling superconducting spintronics devices based on RP-phase high-T_c superconductors.[5-6]

MPEG-4 ER-BSAC decoder의 복잡도 감소방안

최진호(Jinho Choi),문경란(Kyoungran Mun),장달원(Dalwon Jang),최준식(Junsik Choi),예상준(Sangjun Ye),유창동(Chang D. Yoo) 대한전자공학회 2006 대한전자공학회 학술대회 Vol.2006 No.11

Complexity reduction method of MPEG-4 ER-BSAC audio decoder is proposed in this paper BSAC audio codec is standard audio codec of terrestrial DMB. Terrestrial DMB receiver is a digital signal processor(DSP) in this paper. When BSAC audio decoder is ported on DSP, floating point operation takes so long time in fixed point processor. The filter bank module takes a lot of time since it has many floating point operation in this module. Thus, in this paper, the floating point operations of filter bank module are converted to fixed point operations. And floating point operations of PNS and TNS part also are converted to fixed point operations. And many repetition structure are unrolled by unrolling method and nisu inline function. The proposed method performed better than former process.

The kinetics of P-glycoprotein after blood-brain barrier disruption in rat brain by MRI-guided focused ultrasound

Danbi Kim,Hansol Min,Kyoungsu Jeon,Sangdong Kim,Sanghyun Ahn,Raehyung Ryu,Junsik Kim,Mun Han,Choongyong Kim,Juyoung Park 한국실험동물학회 2017 한국실험동물학회 학술발표대회 논문집 Vol.2017 No.2

Tunable Two-channel Magnetotransport in SrRuO₃ Ultrathin Films Achieved by Controlling the Kinetics of Heterostructure Deposition

Eun Kyo Ko,Han Gyeol Lee,Sangmin Lee,Junsik Mun,Jinkwon Kim,Ji Hye Lee,Tae Heon Kim,Jin-Seok Chung,Suk Bum Chung,Miyoung Kim,Seo Hyoung Chang,Tae Won Noh 한국자기학회 2021 한국자기학회 학술연구발표회 논문개요집 Vol.31 No.1

In the field of oxide heterostructure engineering, there have been extensive efforts to couple the various functionalities of each material. The Berry curvature-driven magnetotransport of SrRuO3 ultrathin films is currently receiving a great deal of attention because it is extremely sensitive to extensive physical parameters. Although this is beneficial in terms of heterostructure engineering, it renders transport behavior vulnerable to nanoscale inhomogeneity, resulting in artifacts called “hump anomalies”. Here, we develop a method to tune the magnetotransport properties of SrRuO3 ultrathin films capped by LaAlO3 layers. We systematically controlled the kinetic process by varying the pressure during LaAlO3 layer deposition and investigated the effects on nanoscale inhomogeneity in SrRuO3 films. We found that the high-kinetic energy of the capping layer adatoms induces stoichiometric modification and nano-scale lattice deformation of the underlying SrRuO3 layer. The control of kinetics provides us a way to modulate magnetization and the associated magnetotransport of the SrRuO3 layer.

Development of rotational intraperitoneal pressurized aerosol chemotherapy to enhance drug delivery into the peritoneum

박수진 ( Soo Jin Park ),( Eun Ji Lee ),( Hee Su Lee ),( Junsik Kim ),( Sunwoo Park ),( Jiyeon Ham ),( Jaehee Mun ),( Haerin Paik ),( Hyunji Lim ),( Aeran Seol ),( Ga Won Yim ),( Seung-hyuk Shim ),( Beong 대한산부인과학회 2022 대한산부인과학회 학술대회 Vol.108 No.-

This study aims to evaluate the drug distribution, tissue concentrations, penetration depth, pharmacokinetic properties, and toxicities after rotational intraperitoneal pressurized aerosol chemotherapy (RIPAC) in pigs. Because relevant medical devices have not been introduced, we developed our prototype of pressurized intraperitoneal aerosol chemotherapy (PIPAC) and RIPAC by adding a conical pendulum motion device for rotating the nozzle. RIPAC and PIPAC were conducted using 150 ml of 1% methylene blue to evaluate the drug distribution and 3.5mg of doxorubicin in 50 ml of 0.9% NaCl to evaluate the tissue concentrations and penetration depth, pharmacokinetic properties, and toxicities. All agents were sprayed as aerosols via the nozzle, DreamPenVR (Dalim Biotech, Gangwon, South Korea), with a velocity of 5 km/h at a flow rate of 30 ml/min under a pressure of 7 bars, and capnoperitoneum of 12mmHg was maintained for 30 min. As a result, RIPAC showed a wider distribution and stronger intensity than PIPAC. Compared with PIPAC, RIPAC demonstrated high values of the tissue concentration in the central, right upper, epigastrium, left upper, left lower, right lower, and right flank regions (median, 375.5-2124.9 vs. 161.7- 1240 ng/ml; p_ .05), and higher values of the depth of concentrated diffusion and depth of maximal diffusion (median, 232.5- 392.7 vs. 116.9-240.1 lm; 291.2-551.2 vs. 250.5-362.4 lm; p_ .05) in all regions except for bowels. In RIPAC, the pharmacokinetic properties reflected hemodynamic changes during capnoperitoneum, and there were no related toxicities. Conclusively, RIPAC may have the potential to enhance drug delivery into the peritoneum compared to PIPAC.