Study on Electroconductive Tribological Properties of Ag-based Composite Coating

Yuzhen Liu,Mingyu Gao,Shusheng Xu,김대은 한국정밀공학회 2019 International Journal of Precision Engineering and Vol.20 No.8

Electrical contacts are widely utilized in numerous engineering applications that require high reliability. However, fretting wear due to repeated contact may lead to increased electrical contact resistance that can cause failure of the electrical system. Herein, an Ag-based coating was prepared by an electroless co-deposition technique in order to improve the electroconductive properties under fretting conditions. By carefully controlling the deposition time, a relatively smooth and continuous Ag coating could be obtained. The structure of the coating was analyzed using X-ray diffraction, 3D confocal microscopy, and scanning electron microscopy techniques. The electroconductive tribological properties of the coating were assessed using a custom-built fretting tester. The Ag coating possessed good crystallinity and exhibited improved electroconductive properties compared with the Ni interlayer deposited on a steel substrate. The high temperature of the contact zone generated by friction contributed to the reduced electric resistance. Furthermore, incorporation of graphene as a dopant could improve the coating wear resistance, resulting in more reliable electroconductive properties in the fretting condition. The wear mechanism of the coating was also investigated through wear track analysis. The experimental results are expected to aid in understanding the electroconductive tribological properties of Ag coatings used in electrical contact applications.

Investigating the Wear Mechanisms and Tribochemical Reactions of W-Based Coatings

Yuzhen Liu,Shusheng Xu 한국표면공학회 2023 한국표면공학회 학술발표회 초록집 Vol.2023 No.11-1

탄소 기반 코팅의 바이오트라이볼로지적 특성

류우진(Yuzhen Liu),김대은(Dae-Eun Kim) 한국트라이볼로지학회 2019 한국트라이볼로지학회 학술대회 Vol.2019 No.10

Analysis on the Details of Korean Family Ethics Drama

Guo Yuzhen(곽옥진) 한국엔터테인먼트산업학회 2016 한국엔터테인먼트산업학회논문지 Vol.10 No.5

전통적으로 분류한 세부 형태로 진행되는 것은, 그 외적인 것이 보통 세 가지 유형으로 분류된다. 세부 디테일 세부 사항은 언어세부,동작세부, 물건세부. 세부적 기능을 분류할 수 있고 세부 사항과 세부적으로 표현한 세부와 재현한 세부가 두 종류가 있다. 재현한 세부가 주된 세부 묘사와 인물의 환경을 사용하고 세부적인 목적으로 사용할 수 있는 디테일한 일종의 예술적 진실성을 본다. 세부적이란 표현이 반복되는 동작과 언어, 이런 대상으로 세부 기능과 뛰어난 인물은 독특한 환경적이다. 한국 가정 윤리적 드라마와 인물을 재현한 세부적인 공통성을 보여 환경적으로 표현한 디테일과 개성을 본. 자세한 정보 환경 두 가지를 결합시켜 세부 사항을 알렸다 인형 같은 전형적인 공통성과 개성이 풍부하다. 전형적인 이미지와 환경을 가지고 있다. 특히 디테일을 사용한 대량의 재현성은 물론 세부 사항은 한국 드라마의 특징 가정도 일종의 윤리 그에 대한 일종의 스타일이다. 이로서 이 표현은 물론 세부 사항 디테일한 수단을 강한 자신도 심미적 가치를 사용한 세부 사항을 추진해 많은 한국문화의 대외 전파된다. Details are usually classified into three categories based on the external form: action details, language details and object details; The details can also be classified as reproducing details and expressing details based on function. Reproducing details mainly refer to the details used for shaping the environment and characters, the purpose of using these details is to make the story and the scene like real. Expressing details are the recurring language, action and object .The value of this kind of detail is to highlight the personality and the typical character. Korean family ethics dramas present the common features and the environment by using reproducing details and shape the character"s personality by using expressing details. The reproducing details and expressing details together create typical environments and typical images which are full of personality and common features. The usage of massive details especially the reproducing details is not only the characteristics of Korean family ethics drama but also a style of Korean family ethics drama. These details do not only be used as an expressing method, the details themselves are also have esthetic value and have promote the transmission of Korean culture.

Failure of circular tunnel in saturated soil subjected to internal blast loading

Han, Yuzhen,Liu, Huabei Techno-Press 2016 Geomechanics & engineering Vol.11 No.3

Explosions inside transportation tunnels might result in failure of tunnel structures. This study investigated the failure mechanisms of circular cast-iron tunnels in saturated soil subjected to medium internal blast loading. This issue is crucial to tunnel safety as many transportation tunnels run through saturated soils. At the same time blast loading on saturated soils may induce residual excess pore pressure, which may result in soil liquefaction. A series of numerical simulations were carried out using Finite Element program LS-DYNA. The effect of soil liquefaction was simulated by the Federal Highway soil model. It was found that the failure modes of tunnel lining were differed with different levels of blast loading. The damage and failure of the tunnel lining was progressive in nature and they occurred mainly during lining vibration when the main event of blast loading was over. Soil liquefaction may lead to more severe failure of tunnel lining. Soil deformation and soil liquefaction were determined by the coupling effects of lining damage, lining vibration, and blast loading. The damage of tunnel lining was a result of internal blast loading as well as dynamic interaction between tunnel lining and saturated soil, and stress concentration induced by a ventilation shaft connected to the tunnel might result in more severe lining damage.

중국에서의 소비자 불안과 소비자 행동: 향수 감성의 매개 효과를 중심으로

리위쩐 ( Li Yuzhen ),김우형 ( Kim Woohyoung ),조용석 ( Cho Yongseok ) 현대중국학회 2020 現代中國硏究 Vol.22 No.3

최근 국가적 불안이 현대 사회에서 가장 중요한 사회심리학적 현상이 되었다. 저자들은 소비자 행동에 있어 소비자 불안의 영향을 끼치는 메커니즘에 대해 실증분석을 수행하였다. 본 논문은 SPSS 25.0과 AMOS 21.0 및 구조방정식모델링을 이용해 348개의 유효한 샘플을 실증분석에 적용하였다. 실증분석 결과 소비자 불안은 향수 소비자 행동에 긍정적 영향을 주었다. 소비자들이 높은 수준의 향수를 갖고 있을수록 그들의 소비결정과 소비 정체성이 높은 수준을 유지하였다. 또한 향수는 사회적 불안, 성공, 그리고 향수 소비자 의사결정과 정체성에 있어 긍정적 관계의 매개효과를 보였다. Nowadays, national anxiety has become one of the most significant psychosocial phenomena in current society. We conduct empirical research on the mechanism of the influence of consumer anxiety on consumer behavior. This paper applies an empirical analysis to 348 valid samples of the survey with structural equation modelling and related assumptions through SPSS25.0 and AMOS21.0. Consumer anxiety has a positive impact on nostalgic consumer behavior. When customers have a higher level of nostalgia, their consumption decision and consumption identity will maintain at a high level. Nostalgia mediates the positive relationship between social anxiety, achievement and development anxiety in consumer anxiety on nostalgic consumer decision-making and identity.

Overexpression of a LAM Domain Containing RNA-Binding Protein LARP1c Induces Precocious Leaf Senescence in Arabidopsis

Bangyue Zhang,Yuzhen Han,Jianheng Jia,Min Yang,Chunxia Yan 한국분자세포생물학회 2012 Molecules and cells Vol.34 No.4

Leaf senescence is the final stage of leaf life history, and it can be regulated by multiple internal and external cues. La-related proteins (LARPs), which contain a well-con-served La motif (LAM) domain and normally a canonical RNA recognition motif (RRM) or noncanonical RRM-like motif, are widely present in eukaryotes. Six LARP genes (LARP1a-1c and LARP6a-6c) are present in Arabidopsis, but their biological functions have not been studied previously. In this study, we investigated the biological roles of LARP1c from the LARP1 family. Constitutive or inducible overexpression of LARP1c caused premature leaf senescence. Expression levels of several senes-cence-asso-ciated genes and defense-related genes were elevated upon overexpression of LARP1c. The LARP1c null mutant 1c-1 impaired ABA-, SA-, and MeJA-induced leaf senescence in detached leaves. Gene expression profiles of LARP1c showed age-dependent expression in rosette leaves. Taken together, our results suggest LARP1c is involved in regulation of leaf senescence.

Effects of sintering temperature and alkaline elements excess on the structure and electrical properties of (K_0.462Na_0.48Li_0.058)_(1+x)NbO_3 lead-free piezoelectric ceramics

Rongxia Huang,Yuzhen Zhao,Yongjie Zhao,Rongzheng Liu,Heping Zhou 한국물리학회 2011 Current Applied Physics Vol.11 No.5

Lead-free (K_0.462Na_0.48Li_0.058)_(1+x)NbO_3(0 ≤ x ≤ 0.03) ceramics with excessive alkaline elements were synthesized by conventional ceramics processes as functions of sintering temperatures and quantities of excess alkaline elements. X-ray diffraction results reveal a transformation from tetragonal phase to orthorhombic phase with increasing the contents of excessive alkaline elements. The grain size and the piezoelectric properties were enhanced when a certain amount of excessive alkaline elements were added. Further elevation in the amount of alkaline elements added resulted in excessive liquid phase in the ceramics and deteriorated the piezoelectric properties. With x = 0.01, the ceramics sintered at 1050 ℃ show better properties of planar electromechanical coupling factor k_p = 43.4%, piezoelectric constant d_33 = 204 pC/N, dielectric constant ε^T_33/ε_0 = 704.4, and loss tangent tan δ = 2.8%.

Fabrication and dielectric properties of CCTO/PF dielectric composites: CCTO with different particle size

Yang Zhao,Yuzhen Zhao,Yuhua Niu,Yongming Zhang,Zongcheng Miao 한양대학교 세라믹연구소 2020 Journal of Ceramic Processing Research Vol.21 No.3

Calcium copper titanate (CaCu3Ti4O12, CCTO) particles with three types of particle size (CCTO–i, CCTO–ii, CCTO–iii) areprepared by wet chemical method. And then the dielectric composites based on CCTO particles and Phenol formaldehyderesin (PF) are fabricated by mixing and mould pressing. This paper mainly studies the microstructure and dielectric propertiesof CCTO/PF dielectric composites (CCTO–i, CCTO–ii and CCTO–iii composites). XRD, FTIR and SEM indicate that theCCTO particles are dispersed in the polymer matrix. In addition, the effect of particle size on the dielectric properties ofCCTO/PF composites is also discussed. By comparing the CCTO/PF composites with different particle sizes, it is found thatthe CCTO–i composite has a high maximum dielectric constant and low loss at room temperature of 100 Hz, while the CCTOvolume fraction was 0.5 in the measurement frequency range, which shows a very weak frequency dependence. On this basis,the CCTO–i composite with relatively small particle size has excellent dielectric properties, which may imply that the effectof interface will be changed by smaller particle size.

Efect of Shape, Surface Modifcation and Concentration of Al2O3 Nanoparticles on Breakdown Performance of Transformer Oil

Muhammad Rafq,Yuzhen Lv,Chengrong Li 대한전기학회 2020 Journal of Electrical Engineering & Technology Vol.15 No.1

The Al2O3 nanoparticles (NPs) with favorable features were prepared in our lab to develop transformer oil/paper insulation system with better insulation performance. The nanofuids (NFs) were prepared with diferent shapes (nanorods, nanoplates), surface modifcations (oleic acid, C2, C18) and concentrations (0.6 g/L, 0.8 g/L, 1.2 g/L) of Al2O3 NPs. The positive lightning impulse (LI) breakdown voltages (VBDs) of mineral oil were improved by 1.11 times with nanorod shape, oleic acid surface modifcation and 0.8 g/L concentration of NPs. The efects of Al2O3 NPs with diferent gap distances on insulating properties of NFs under LI voltage were examined. It was noted that after Al2O3 NPs suspension, the positive LI VBDs of transformer oil (TO/MO) were enhanced but the negative LI VBDs of were decreased. The signifcant improvement in insulating performance of NFs is interpreted in light of electron traps theory. It was found that suspended NPs can enhance the shallow trap desity. The generated electrons would lose their kinetic energy through repeatedly trapping and de-trapping process, leading to decline in elcetron mobility. The higher trap density of NPs will lower average energy, and lower mobility of electrons are obtained. The electrons with lower energy are easy to be captured by those molecules with high electron afnity, and be converted into negative space charges. These negative space charge decreases the electrical feld strength at the front of positive streamer and therefore reduce the propagating velocity of positive streamer.