Effects of Quenching Methods and Aging Processes on the Crushing Properties and Microstructure of Al–Zn–Mg Alloy Thin-Walled Square Extrusions

Hui Guo,Jin Zhang,Cheng Wang,Yun‑lai Deng 대한금속·재료학회 2022 METALS AND MATERIALS International Vol.28 No.8

In this study, the effects of different (online quenching and offline quenching) quenching methods and aging processes (T6and T73) on the crashworthiness and microstructural evolution of three Al–Zn–Mg alloys (G1–G3) were studied by conductingtensile test and axial compression tests at room temperature, combined with optical metallography, electron back scattereddiffraction, and transmission electron microscopy microstructural observations. The obtained results revealed that thecrushing properties of three different Al–Zn–Mg alloys subjected to different quenching methods and aging processes weresignificantly different. Their crushing energy absorption of are ranked as follows: G1 > G3 > G2. The highest total energyabsorption gap (between T6 and T73) is the G1 alloy, and the lowest one is the G3 alloy. The largest total energy absorptiongap between the two quenching methods is the G3 alloy, and the smallest one is the G1 alloy. The G2 alloy with the largesttotal amount of Zn + Mg has the highest number density of matrix precipitates, the largest precipitate gap (between T6 andT73) and the smallest precipitate gap between the two quenching methods. The G3 alloy with the largest Zn/Mg ratio hasthe smallest number density of matrix precipitates, the minimum precipitation gap (between T6 and T73) and the maximumprecipitation gap between the two quenching methods. The G1 alloy with the lowest Zn/Mg ratio has the smallest size ofgrain boundary precipitates and PFZ width, while their largest values are obtained for the G3 alloy with the maximum Zn/Mg ratio. As a crushing resistant structural material, the crushing properties is improved without reducing the strength. Theratio of Zn/Mg should be controlled within the range of 4.57–6.15, while the total amount of Zn + Mg should be controlledwithin the range of 6.18–7.01.

호이스트용 SRM의 구동시스템의 특성해석

이진국,이동희,안진우 경성대학교 공학기술연구소 2005 공학기술연구지 Vol.12 No.-

This paper presents a development of Switched Reluctance Motor (SRM) drive system for a hoist application. In the hoist system, smoothing start-up and braking are very important for a protection of goods. In order to improved a start-up and a stop performance of hoist system, the smoothing operation sequence of SRM using direct instantaneous torque control is proposed. The proposed Direct Instantaneous Torque Control (DITC) the instantaneous torque of SRM according to the switching sequence and hysteric band. In order to compare the reference and actual torque of SRM, pre-measured flux and torque look-up table are regulate used. The proposed SRM Drive system is verified by the simulation result.

4-레벨 인버터를 이용한 고속 SRM 구동시스템

이동희,이진국,안진우 경성대학교 공학기술연구소 2005 공학기술연구지 Vol.12 No.-

This paper proposes high speed SRM drive system for blower with a novel 4-level inverter and precise excitation position generator. In order to get a fast build-up and a demagnetization of excitation current, 4-level inverter system is proposed. The proposed 4-level inverter has additional charge capacitor, power switch and diode in the conventional asymmetric converter. The charged high voltage is supplied to the phase winding for fast current build- up, and demagnetization current is charged to additional capacitor of 4-level inverter. In addition, a precise excitation position generator can reduce turn-on and turn-off angle error according to sampling period of digital control system. The proposed high speed SRM drive system is verified by computer simulations and experimental results.

Synergistic Effects of Leflunomide and Benazepril in Streptozotocin-Induced Diabetic Nephropathy

Jin, Hua,Piao, Shang Guo,Jin, Ji Zhe,Jin, Ying Shun,Cui, Zhen Hua,Jin, Hai Feng,Zheng, Hai Lan,Li, Jin Ji,Jiang, Yu Ji,Yang, Chul Woo,Li, Can S.Karger 2014 The Nephron Journals Vol.126 No.3

<P>Abstract</P><P><B><I>Background:</I></B> Leflunomide (LEF) and benazepril have renoprotective effects on diabetic nephropathy (DN) through their anti-inflammatory and anti-fibrotic activities. This study investigated whether combined treatment using LEF and benazepril affords superior protection compared with the respective monotherapies. <B><I>Methods:</I></B> Diabetes was induced with streptozotocin (STZ, 65 mg/kg) by intraperitoneal injection in male Wistar rats. Two weeks after STZ injection, diabetic rats were treated daily for 12 weeks with LEF (10 mg/kg), benazepril (10 mg/kg), or a combination of both. Basic parameters (body weight, fasting blood glucose level, and 24 h urinary protein excretion), histopathology, inflammatory [inflammatory cell infiltration (ED-1), monocyte chemoattractant protein-1 (MCP-1), and Toll-like receptor-2 (TLR-2)] and glomerulosclerotic factors [transforming growth factor-β<SUB>1</SUB> (TGF-β<SUB>1</SUB>) and connective tissue growth factor (CTGF)], and oxidative stress (8-hydroxy-2'-deoxyguanosine, 8-OHdG) were studied. <B><I>Results:</I></B> Benazepril or LEF treatment significantly prevented body weight loss and 24 h urinary protein excretion induced by diabetes; combined treatment with LEF and benazepril further improved these parameters compared with giving each drug alone (all p < 0.01). Increased expression of inflammatory (MCP-1 and TLR-2) and glomerulosclerotic (TGF-β<SUB>1</SUB> and CTGF) factors in diabetic rat kidney was reduced by treatment with either LEF or benazepril and was further reduced by the combined administration of the two drugs (p < 0.01). These effects were accompanied by suppression of urinary 8-OHdG excretion. There was no significant between-group difference in blood glucose level. <B><I>Conclusions:</I></B> LEF treatment lessens DN, and combined treatment with LEF and benazepril provides synergistic effects in preventing DN.</P><P>© 2014 S. Karger AG, Basel</P>

A 3-D Steady-State Analysis of Thermal Behavior in EHV GIS Busbar

Jin Lei,Jian-ying Zhong,Shi-jin Wu,Zhen Wang,Yu-jing Guo,Xin-yan Qin 대한전기학회 2016 Journal of Electrical Engineering & Technology Vol.11 No.3

Busbar has been used as electric conductor within extra high voltage (EHV) gas insulated switchgear (GIS), which makes EHV GIS higher security, smaller size and lower cost. However, the main fault of GIS is overheating of busbar connection parts, circuit breaker and isolating switch contact parts, which has been already restricting development of GIS to a large extent. In this study, a coupled magneto-flow-thermal analysis is used to investigate the thermal properties of GIS busbar in steady-state. A three-dimensional (3-D) finite element model (FEM) is built to calculate multiphysics fields including electromagnetic field, flow field and thermal field in steady-state. The influences of current on the magnetic flux density, flow velocity and heat distribution has been investigated. Temperature differences of inner wall and outer wall are investigated for busbar tank and conducting rod. Considering the end effect in the busbar, temperature rise difference is compared between end sections and the middle section. In order to obtain better heat dissipation effect, diameters of conductor and tank are optimized based on temperature rise simulation results. Temperature rise tests have been done to validate the 3-D simulation model, which is observed a good correlation with the simulation results. This study provides technical support for optimized structure of the EHV GIS busbar.

ON RINGS WHOSE ANNIHILATING-IDEAL GRAPHS ARE BLOW-UPS OF A CLASS OF BOOLEAN GRAPHS

Guo, Jin,Wu, Tongsuo,Yu, Houyi Korean Mathematical Society 2017 대한수학회지 Vol.54 No.3

For a finite or an infinite set X, let $2^X$ be the power set of X. A class of simple graph, called strong Boolean graph, is defined on the vertex set $2^X{\setminus}\{X,{\emptyset}\}$, with M adjacent to N if $M{\cap}N={\emptyset}$. In this paper, we characterize the annihilating-ideal graphs $\mathbb{AG}(R)$ that are blow-ups of strong Boolean graphs, complemented graphs and preatomic graphs respectively. In particular, for a commutative ring R such that AG(R) has a maximum clique S with $3{\leq}{\mid}V(S){\mid}{\leq}{\infty}$, we prove that $\mathbb{AG}(R)$ is a blow-up of a strong Boolean graph if and only if it is a complemented graph, if and only if R is a reduced ring. If assume further that R is decomposable, then we prove that $\mathbb{AG}(R)$ is a blow-up of a strong Boolean graph if and only if it is a blow-up of a pre-atomic graph. We also study the clique number and chromatic number of the graph $\mathbb{AG}(R)$.

Brand Personality Recognition from Analytic Hierarchy Process Perspective

Guo Rui Jin 원광대학교 한중관계연구원 2020 韓中關係硏究 Vol.6 No.2

오늘날 세계경제의 친밀화가 점점 심화되고 있다. 생산과정의 분화와 판매지점의 국제화는 세계무역의 형세를 바꾸어 이른바 글로벌화 되고 있다. 브랜드 경제는 중요 한 무형적 가치를 가진 것으로, 이는 국가경쟁력을 제고하고, 글로벌 경제활동에서 유 리한 고지를 선점하게 하는 중요한 역할을 한다. 본 연구에서는 브랜드 아이덴티티의 관점에서 경제통합추세에 따른 브랜드 경제의 국가전략과 기업생존에 미치는 중요한 영향이 무엇인지 검토하고, 이른바 브랜드 경제 에 있어 브랜드 아이덴티티와 소비자 구매의사 간의 긴밀한 연관성을 탐구함으로써 브랜드 관리 경제에 중요한 자료로 제공될 것이다. 이를 위해 차원분석법에 기초한 서열화 알고리즘을 통해 브랜드 관리자가 특화된 브랜드의 특징을 맞춤화하고, 아이덴 티티를 계량화하여 평가함으로써 궁극적으로 브랜드의 아이덴티티를 실현할 수 있도 록 한다. 또한, 이러한 방법론의 타당성과 적용상의 논증을 위해 두 가지 전형 사례를 도입하여 검토함으로써 브랜드 아이덴티티의 개발과 관리라는 관점에서 독특한 브랜 드를 구축하기 위한 전략을 제시하였다. In the current integrated global economy, the unbundling of the production process and the distribution of production stages in multinational locations result in trade patterns being shifted and reshaped. And as one of the intangible but powerful forces, the economic importance of the brand is playing a significant role to form a nation’s core competitiveness and advantageous position in global economic activity. However, the elaboration of previous studies of brand value mostly focus on the theoretical level, and as an important attribute of the brand, the exploration of brand personality focuses on ambiguous expositional judgment, while few have concerned on the recognition methods of dimensional efficiency as an accurate quantification, which made the vital challenges of brand operators regarding the key brand personality dimension recognition and quantification to be blank and of limited help for brand operators in practical operation. In this paper, we propose an analytical hierarchy process (AHP) based ranking algorithm to recognize the key brand personality and figure out the level of importance with a clear ranking on dimensions, which fills the academic gap on brand personality quantification. To explain the feasibility and universal applicability of this method, the importance priority of brand characteristics is carried out by using the analytic hierarchy process in two different scenarios.

문법성 판단 테스트를 통해 본 중국인 학습자의 부사격 조사 ‘에’의 습득 양상

Jin Guo,김영주 서울대학교 국어교육연구소 2016 국어교육연구 Vol.37 No.-

본 연구는 중국인 중‧고급 학습자를 대상으로 부사격 조사 '에'의 습득 양상을 조사하는 것을 목적으로 한다. 이를 위해 문법성 판단 테스트를 개발하여 3∼6급의 학습자 각 30명씩 총 120명과 비교 대상으로 한국어 모어 화자 20명에게 실험을 실시하였다. 본 연구 결과, (1) 전체 중국인 학습자 집단은 매우 낮은 정답률을 보여 한국어 모어 화자와 유의미한 차이를 보였다. 이는 중국인 학습자가 부사격 조사 ‘에’의 습득에서 어려움을 겪고 있음을 나타낸다. (2) 중국인 학습자들은 ‘에의 활용’에서 가장 높은 정답률을 그리고 , ‘자격, 신분’에서 가장 낮은 정답률을 보였다. (3) 숙달도별 집단 간 조사에서 3급과 4, 5, 6급간에서 유의미한 차이가 발견되었으나 4급, 5급, 6급들 간에는 유의미한 차이가 발견되지 않았다. 이는 숙달도가 향상되어도 부사격 조사 ‘에’의 습득에 지속적인 교육적 관심이 필요함을 보여주는 결과이다. IIn this study, we carried out grammaticality judgment test of “ey,” an adverb case marker in Korean, with 120 Chinese Korean learners in the intermediate or advanced levels (level 3 to 6, 30 learners in each level) of TOPIK test, with the comparison group consisting of 20 Korean native speakers, in order to figure out acquisition aspects. In the results of the study, (1) intermediate or advanced Chinese Korean learners were able to arrive at low percentage of correct answers compared to Korean native speakers and the difference was significant in the acquisition aspects of ”ey.” (2) Acquisition aspects of “ey” were shown in the order as below. “application,” “purpose,” “recognition,” “emotion,” “arrival place,” “time,” “condition,” “situation," “price,” “setting the price,” “object,” “reason,” “cause,” “criteria for comparison,” “means,” “method,” “addition,” “place,” “location,” “qualification,” and “position.” (3) For learners among 4-6 levels in TOPIK, as their proficiency improved, no significant improvement was seen in the acquisition of “ey”; however, the only significant discrepancy was found between level 3 learners and level 4-6 learners. These results proved that instructional intervention is still necessary.

Parameter identification of the phenomenological model for magnetorheological fluid dampers using hierarchic enhanced particle swarm optimization

Jin Guo,Zhendong Li,Mengxuan Zhang 대한기계학회 2021 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.35 No.3

The magnetorheological (MR) fluid damper, as a new generation of highperformance and intelligent vibration damping devices for engineering structures, has broad application prospects in structural vibration reduction. Nonlinear hysteresis is a complex phenomenon of MR dampers. In this paper, the phenomenological model is used to simulate the dynamics of MR dampers. To accurately and efficiently identify the parameters of the phenomenological model, the hierarchical enhanced particle swarm optimization (HEPSO) algorithm is proposed. This algorithm applies a hierarchical optimization mechanism and introduces media particles to the enhanced PSO (EPSO) algorithm to improve the optimization process of parameter identification and enhance the performance of the PSO algorithm without reducing the possibility of finding the optimal solution. Compared with the standard PSO (SPSO) algorithm and the EPSO algorithm, the HEPSO algorithm has a higher efficiency, accuracy and robustness in identifying a highly nonlinear hysteretic system problem.

3-D Hydrogen-Bonded Frameworks of Two Metal Complexes with Chelidamic Acid: Syntheses, Structures and Magnetism

Guo-Wei Zhou,Guo-Cong Guo*,Bing Liu,Ming-Sheng Wang,Li-Zhen Cai,Jin-Shun Huang 대한화학회 2004 Bulletin of the Korean Chemical Society Vol.25 No.5