Effects of Si on the Microstructure and Work Hardening Behavior of Fe‒17Mn‒1.1C‒xSi High Manganese Steels

Renlong Xiong,Yi Liu,Haitao Si,Huabei Peng,Shanling Wang,Binhan Sun,Hanxin Chen,Hyoung Seop Kim,Yuhua Wen 대한금속·재료학회 2021 METALS AND MATERIALS International Vol.27 No.10

In order to improve the work hardening capacity under low stresses and the yield strength of conventional Hadfield steels, theeffects of Si on the microstructure and work hardening behavior of the Fe‒17Mn‒1.1C‒xSi steels under both quasi-statictensile and low load impact are investigated. It is shown that the increase of the Si contents remarkably improves the yieldstrength by 36 MPa per 1 wt% Si in the investigated steel system without significant sacrifice of ductility. The decreasingeffect of Si on the stacking fault energy is strongly affected by carbon, although the variation of carbon content was small. This led to the unexpected similar stacking fault energy between 1Si and 2Si steel. With the increase of the Si contents forthe steels, the critical strain for the onset of mechanical twinning was lowered, which was controlled by the cooperationbetween the stacking fault energy and solid solution strengthening of Si. This resulted in the earlier initiation of mechanicaltwins and an increase in the twin volume fraction. Therefore, the work hardening capacities under both quasi-static tensileand low load impact tests were enhanced. It was also found that the impact deformation decreased as more mechanical twinsabsorbed the impact energy.

Improved Adhesion of Metal Electrode Layer on Si₃N₄ Substrate through an All-Wet Process

Kim, Danbi,Eom, Nu Si A,Kim, Jiwon,Lee, Kyu Hyoung,Park, Sung Heum,Lee, Ju Ho,Chao, Yong-Ho,Lim, Jae-Hong Electrochemical Society 2019 ECS journal of solid state science and technology Vol.8 No.2

<P>Electroless deposition requires preliminary surface treatment to effectively adsorb a metal electrode layer onto a ceramic substrate. Herein, a simple surface treatment using an all-wet process was performed to achieve adhesion stability between a Si<SUB>3</SUB>N<SUB>4</SUB> substrate and Ni film. The method involved deposition of an interfacial Pd-TiO<SUB>2</SUB> buffer between the two layers. Surface pretreatment via silanization was initially performed to improve surface wettability, thereby enhancing uniform deposition of Pd-TiO<SUB>2</SUB>. Subsequently, a thin Ni layer was directly deposited onto the Pd-TiO<SUB>2</SUB> layer without necessitating sensitization or activation. The synthesized Ni/Pd-TiO<SUB>2</SUB>/Si<SUB>3</SUB>N<SUB>4</SUB> heat sink exhibited excellent adhesion property in the cross-hatch, scratch, and thermal shock tests. The mechanism of adhesion enhancement involved chemical bonding of Pd-TiO<SUB>2</SUB> with the self-assembled monolayer on the substrate and reduced internal stress due to removal of residual hydrogen between the layers of the heat sink. Thus, the fabricated heat sink has a promising application in electronic devices operated at high temperatures.</P>

Artificial cathode-electrolyte interphases on nickel-rich cathode materials modified by silyl functional group

Song, Hye Ji,Jang, Seol Heui,Ahn, Juhyeon,Oh, Si Hyoung,Yim, Taeeun Elsevier 2019 Journal of Power Sources Vol.416 No.-

<P><B>Abstract</B></P> <P>Nickel-rich nickel-cobalt-manganese layered oxides receive significant attention as advanced cathode materials, however, they suffer from poor cycling performance at elevated temperature because of surface instability. In this study, we develop nickel-rich cathode materials modified by an artificial cathode-electrolyte interphase layer embedding silyl ether functional groups. An artificial cathode-electrolyte interphase layer-functionalized nickel-rich cathode materials are simply synthesized via a wet-coating-based thermal treatment using a dimethoxydimethylsilane as an organic precursor. The task-specific silyl ether functional groups are effective in selectively scavenging nucleophilic fluoride species, which potentially triggers the dissolution of transition metal components into the electrolyte. Microscopic analyses indicate that the artificial cathode-electrolyte interphase layer is well developed on the surface of the nickel-rich cathode materials with several nanometers-thickness. The cells cycled with functionalized nickel-rich cathodes exhibit much higher cycling retentions (∼70.0%) than the cell cycled with bare nickel-rich cathode (47.1%) at high temperature. Additional systematical analyses indicate that the artificial cathode-electrolyte interphase layers effectively mitigate the electrolyte decomposition and the dissolution of transition metal components, thereby improving the cycling behavior of the cell on the basis of increased interfacial stability of nickel-rich cathode materials.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Artificial CEI layer was introduced by Si-based precursor on Ni-rich NCM cathode. </LI> <LI> Si-based artificial CEI layer was provided by wet coating-based one-step process. </LI> <LI> Task-specific Si–O functional groups on CEI layer were effective in F<SUP>−</SUP> scavenging. </LI> <LI> Si-based CEI layer improved interfacial stability of Ni-rich NCM cathode. </LI> <LI> Si-based artificial CEI layer allowed enhanced cycle retention at high temperature. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>

대관령의 일조시간을 이용한 월별 일사량의 추정

박진기, 오시영, 백신철, 김봉섭, 신형섭, 박종화 忠北大學校 農業科學硏究所 2013 農業科學硏究 Vol.29 No.1

The monthly mean daily global solar radiation and sunshine duration, have been employed in this study to develop correlation model for Daegwallyeong during 2011. The corresponding monthly value of extraterrestrial solar radiation and possible duration of sunshine are calculated for Daegwallyeong meteorological data. Forecasting performance parameters such as coefficient of determination (R2), mean bias error (MBE) and root mean square error (RMSE) are presented as analyzed for the model. The model with multi-linear regression has the highest R2 value of 0.95 and average MBE and RMSE values of −0.11 MJ/m2day and 1.63 MJ/m2day, respectively. The model exhibited negative MBE which shows that the model resulted in underestimation of the global solar radiation relative to the meteorological measured value. The equation could be employed in the estimation of solar radiation at Daegwallyeong, other locations with similar meteorological characteristics.

종동력을 받는 양단 자유 링 보강 원통셸의 동적 안정성에 관한 연구

김지환,박시형 서울대학교 항공우주신기술연구소 2000 항공우주신기술연구소 연구보고 Vol.1 No.1

The dynamic stability of a completely free cylindrical shell under a follower force is analyzed. By attatching rings on both side of a shell, we describe the behavior of rockets or missiles more exactly. Using orthogonality, the analysis is performed about each circumferential wave number. The kinetic analysis and the static analysis are used according as the circumferential wave number is one or not.

디지털 콘텐츠 산업의 공간분포 특성에 관한 연구

김성훈,임용민,이시형,홍일영 남서울대학교 2010 남서울대학교 논문집 Vol.16 No.1-1

Digital contents industry is a developing industry which is being recognized for its growth possibility. This study is intended to understand the spacial distribution of digital contents industry. To do so, spatial range of this study is set in metropolitan regions to grasp the clustered regions. To understand the clustered regions of digital contents industry, spatial cluster analysis was enforced. As a result, total of 7 clusters were formed. 7 clusters are all located in Seoul, and 4 out of 7 are concentrated in Kangnam Gu. This study grasped the characteristics of these clusters. Locational factors of each company categories, which are the cause of such characteristic, are scheduled to be researched more specifically in the future. Key Words : digital contents industry, Spatial distribution, cluster, Locational factor, Spatial clustering

FFD를 이용한 라스트 데이터 생성 시스템 설계

임창현,안형회,박인덕,김시경 공주대학교 생산기술연구소 2001 論文集 Vol.9 No.-

This paper presents a 3D last design software that provides the 3-dimensional last data to achieve from the 3-dimensional foot data. The proposed software employes a free form deformation(FFD) with Bezier patch. The deformation factor of the FFD is constructed on the FFD lattice based on the bottom view, lateral view of the measured 3D foot data. In addition, the control points of FFD lattice is decide on the anatomical view of foot. The deformed 3D last result obtained from the proposed FFD is saved as a 3D dxf foot data. The experimental results demonstrates that the proposed? system have the descent 3D last data based on the openGL window.

폐암과 동반되어 나타난 기관기관지병증 골연골형성증 1예

이영진,전현수,박시형,김모세,김현주,이승헌,이영민,이현욱,이현경 仁濟大學校 白病院 2010 仁濟醫學 Vol.31 No.-

Tracheobronchopathia osteochondroplastica (TPO) is a rare benign disease of unknown etiology characterized by multiple cartilaginous or bony submucosal nodules, which project into the tracheobronchial lumen. Although some disorders were reported combined with TPO, these seemed to be considered casual. We report a case of TPO that combined with adenocarcinoma of lung. She was 50-year-old non smoking woman presented with chronic cough with right chest pain. Lung mass on right lower lobe was found on chest x-ray, so lung cancer was suspected. Multiple scattered whitish small elevations from trachea to bronchial trees were found on bronchoscopic exam. We mistook these lesions for metastases from lung cancer and biopsies of these lesions were done. Transbronchial biopsy for right lower lobe mass lesion was also done. But biopsies from trachea and bronchus revealed TPO rather than lung cancer. Transbronchial lung biopsy of right lower lobe mass was diagnosed adenocarcinoma of lung. So TPO combined with adenocarcinoma of lung was diagnosed.

Simultaneous etching and transfer — Free multilayer graphene sheets derived from C₆₀ thin films

Hudaya, Chairul,Ahn, Minjeh,Oh, Si Hyoung,Jeon, Bup Ju,Sung, Yung-Eun,Lee, Joong Kee Elsevier 2018 Journal of industrial and engineering chemistry Vol.64 No.-

<P><B>Abstract</B></P> <P>Despite the advantage of chemical vapor deposition (CVD) for realization of large area epitaxial growth of graphene on transition metal catalysts, both etching and transfer process of CVD-grown graphene sheets still remain a big challenge. Here we demonstrate the formation of multilayer graphene (MLG) sheets tailored from C<SUB>60</SUB> thin films on the top of Si/Ni substrate without etching and transfer steps based on Ni films. This self-assembled process separates the MLG sheets from the conductive Ni catalyst, embarking a possibility for direct characterizations of MLG sheets. The fine-tuned C<SUB>60</SUB> films (30nm) are transformed into approximately 17 MLG sheets, thus making it large-area MLG sheets for a variety of direct applications.</P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>

그라인더(grinder) 사용에 의한 Hand-Arm Vibration Syndrome(HAVS)의 6예

임상혁,김록호,양길승,양정인,김상섭,전형준,박시복 大韓産業醫學會 2000 대한직업환경의학회지 Vol.12 No.3

목 적 : 수지증상이 있는 진동공구 작업자 8명에 대해 객관적이고 체계화된 진단방법을 이용하여 수지진동 증후군을 진단하고자 시행하였다. 방 법 : 과거병력, 가족력 등의 문진과 혈액 및 소변, 방사선 검사를 통해 다른 원인에 의한 레이노씨병을 배제하였고, 공구 측정 결과를 이용하여 작업과의 관련성을 보았으며, 냉수 침지검사와 근전도 검사를 통하여 수지진동 증후군을 진단하고자 하였다. 결 과 : 수지증상이 있는 진동공구 작업자 8명에 대해 과거병력, 가족력, 약물복용 및 과거 직업력 등 레이노씨병을 유발하는 요인에 대하여 조사하였고 특이점은 발견하지 못하였다. 다른 원인에 의한 레이노씨병을 배제하기 위해 혈액 및 소변, 방사선 검사를 하였고 8명 모두에서 특이 소견을 발견하지 못하였다. 위의 문진과 검사결과로 다른 원인에 의한 레이노씨병을 배제할 수 있었다. 해당사업장의 진동 공구 측정결과를 근거로 피검자의 공구가 ISO의 허용기준을 초과함을 알 수 있었다. 냉수 침지검사와 근전도 검사를 이용하여 피검자 8명중 6명이 말초 혈액순환 장해와 말초 신경염이 있는 것으로 진단되었다. 위의 내용을 근거로 6명은 진동에 의한 수지 진동 증후군으로 진단할 수 있었다. 결 론 : 수지증상이 있는 진동공구 작업자 8명에 대해 객관적이고 체계화된 진단방법을 이용하여 수지진동 증후군을 진단하였다. 해당 사업장의 진동 공구 작업자의 진동에 대한 검진이 필요할 것으로 생각된다. Objectives : To confirm the HAVS In workers exposed to hand-arm vibration with using the objective diagnostic methods. Methods : Several tests were used to help substantiate a clinical diagnosis of HAVS. Some other diseases were excluded by a medical interview, hematologic assessment, urinalysis, X-rays. The hand-arm vibration acceleration level of the grinder was evaluated for considering HAVS. Peripheral vascular changes were examined by a cold provocation test. An electromyography was implemented to ascertain the peripheral neural changes. Results : 8 workers with symptoms in hands & fingers, exposed to hand-arm vibration were examined. Some other diseases (primary Raynaud's disease, secondary Raynaud's disease in not occupational origin) were excluded by a medical interview, hematologic assessment, urinalysis, X-rays. The hand-arm vibration acceleration level of the grinder was 7.9 m/sec2. The recovery time of a skin temperature followed finger cooling was significantly prolonged in 6 workers with HAVS. The nerve conduction velocity was reduced in 6 workers with HAVS. Conclusions : So we report 6 cases of HAVS in grinding workers exposed to hand-arm vibration diagnosed objectively by an exclusion of some other disease, hand- arm vibration acceleration level, cold provocation test, electromyography.