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Effect of Plastic Anisotropy on the Formability of Aluminum 6016-T4 Sheet Material

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Chinese Journal of Mechanical Engineering 2017年第3期30卷 625-631页

作者： young-Suk KIM Seung-Han YANG kyungpook national university Daegu 41566Republic of Korea

Sheet metal formed of lightweight materials such as aluminum sheeting has received great attention related to the reduction of vehicle emissions. This paper evaluates the anisotropic yield locus using Kuwabara＇s biaxial tensile tester and stretches formability using Hecker＇s hemispheri- cal punch stretching test for aluminum 6016-T4 sheet material. The anisotropic yield locus of the A16016-T4 sheet measured is fitted well by the modified Drucker yield func- tion. Moreover the best fitting to the experimental stress- strain curve from the tensile test was obtained by taking an appropriate hardening model. Analytical study to predict the stretch formability by using Hora＇s Modified Maximum Force Criterion （MMFC） was performed. The predicted forming limit curves （FLC） based on various yield functions were compared with the experiments and discussed.

关键词： Anisotropic yield function AluminumA16016-T4 Biaxial tensile test Forming limit curve

Sliding Wear Behavior of Plasma Sprayed Alumina-Based Composite Coatings against Al_2O_3 Ball

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Journal of Materials Science & Technology 2004年第4期20卷 395-401页

作者： Minh-quyLe young-hunChae Seock-samKim GraduateSchool SchoolofMechanicalEngineeringKyungpookNationalUniversityDaeguSouthKorea EngineeringTribologyResearchInstitute KyungpookNationalUniversityDaeguSouthKorea SchoolofMechanicalEngineering KyungpookNationalUniversityDaeguSouthKorea

The sliding wear behaviors of a single layer AI2O3-30 wt pct ZrO2, a double layer AI2O3-30 wt pct ZrO2/Ni-Cr and a single layer AI2O3-13 wt pct TiO2 coating deposited on low carbon steel by plasma spraying were investigated under lubricated conditions with various normal loads. The plastic deformation, detachment and pull out of splats were involved in the wear process of the studied coatings under test conditions. Crack propagation was found in AI2O3-13 wt pct TiO2 under loads of 70 and 100 N and in AI2O3-30 wt pct ZrO2/Ni-Cr under a load of 130 N. While increasing the normal load, the wear rates of AI2O3-30 wt pct ZrO2 and AI2O3-30 wt pct ZrO2/Ni-Cr slightly increased, the wear rate of AI2O3-13 wt pct TiO2 increased rapidly. The results showed that the Ni-Cr bonding layer improved the wear resistance of the coating system even it is relatively thin compared with the outer coating layer. The influence of this bonding layer on wear behavior of the coating increased as increasing the normal load.

关键词： Coating Plasma spray Wear behavior

Effect of Ni and Mn on the Mechanical Properties of 22Cr Microduplex Stainless Steel

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Acta Metallurgica Sinica(English Letters) 2015年第1期28卷 32-38页

作者： Jun-young Park Yong-Sik Ahn Department of Materials Science and Engineering Pukyong National University

The tensile properties of 22Cr–2Ni–4Mn–0.2N micro-duplex stainless steels with different Ni and Mn contents were investigated. Duplex stainless steels were vacuum induction melted and hot rolled, then annealed at 1,000–1,100 °C, at which temperature both the austenite and ferrite phases were stable. The volume fraction of the ferrite phase was markedly affected by the alloying elements of Mn and Ni; 1 wt% of Mn was equivalent to 0.4 wt% of Ni. All of the steels tested at room temperature showed the common strain-hardening behavior, while the steels tested at lower temperatures（-30 or-50 °C）showed a distinct inflection point in their stress–strain curves, which resulted from the transformation of the austenite to straininduced martensite. The onset strain（e0） of the inflection point in the stress–strain curve depended on the Md30 value of the steel. Testing at lower temperatures resulted in smaller e0 and consequently higher strengths and fracture strains（ef）. The tensile behavior was examined from the perspective of austenite stability of the micro-duplex stainless steels with the different Ni and Mn contents.

关键词： Duplex stainless steel Microstructure Mechanical property Alloy composition

OPTIMUM ORDERING POLICY FOR PREVENTIVE AGE REPLACEMENT

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Journal of Systems Science and Systems Engineering 2009年第3期18卷 283-291页

作者： young T. PARK Jing SUN Department of Systems Management Engineering Sungkyunkwan University School of Economics and Management Tsinghua University Beijing 100084 China

Most of the spare ordering policies treated up to now have assumed that preventive and corrective replacement costs are equal, which implies in essential that there is no significant need for preventive replacement. This paper presents an ordering policy for preventive age replacement with minimal repair. Introducing the replacement, repair, inventory holding and shortage costs, the expected cost rate is derived. A procedure to determine jointly the ordering time for a spare and the preventive replacement time for the operating unit so as to minimize the expected cost rate is proposed. To explain the ordering policy and the optimization procedure, a numerical example is also included.

关键词： Ordering policy spare age replacement minimal repair

Current progress toward eradicating Helicobacter pylori in East Asian countries: Differences in the 2013 revised guidelines between China, Japan, and South Korea

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World Journal of Gastroenterology 2014年第6期20卷 1493-1502页

作者： Sun-young Lee Department of Internal Medicine Konkuk University School of Medicine

New 2013 guidelines on Helicobacter pylori(H. pylori) infection have been published in China, Japan, and South Korea. Like the previous ones, these new guidelines differ between the three countries with regard to the indications for H. pylori eradication, diagnostic methods, and treatment regimens. The most profound change among all of the guidelines is that the Japanese national health insurance system now covers the expenses for all infected subjects up to second-line treatment. This makes the Japanese indications for eradication much wider than those in China and South Korea. With regard to the diagnosis, a serum H. pylori antibody test is not recommended in China, whereas it is considered to be the most reliable method in Japan. A decrease relative to the initial antibody titer of more than 50% after 6-12 mo is considered to be the most accurate method for determining successful eradication in Japan. In contrast, only the urea breath test is recommended after eradication in China, while either noninvasive or invasive methods(except the bacterial culture) are recommended in South Korea. Due to the increased rate of antibiotics resistance, first-line treatment is omitted in China and South Korea in cases of clarithromycin resistance. Notably, the Japanese regimen consists of a lower dose of antibiotics for a shorter duration(7 d) than in the other countries. There is neither 14 d nor bismuth-based regimen in the first-line and second-line treatment in Japan. Such differences among countries might be due to differences in the approvals granted by the governments and national health insurance system in each country. Further studies are required to achieve the best results in the diagnosis and treatment of H. pylori infection based on cost-effectiveness in East Asian countries.

关键词： Helicobacter pylori Eradication Guideline Diagnosis Treatment

Organic solar cells for indoor power generation

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Science China Chemistry 2020年第1期63卷 1-2页

作者： Hwa Sook Ryu Han young Woo Department of Chemistry College of Science Korea University

During last decades,organic solar cells(OSCs)have achieved remarkable advancements via extensive studies on the optimization of photovoltaic donor/acceptor(D/A)materials,device fabrication,and the D/A bulk heterojunction *** conversion efficiencies(PCEs)up to〜16%for single junction cells and over 17%PCEs were successfully demonstrated for tandem OSC devices[1,2].OSCs may find real industrial applications soon,including building integrated photovoltaics,portable power sources and indoor power generation for low power consumption electronic devices(i.e.,internet of things(IOT)sensors).Among them,indoor applications have great potentials because OSCs can convert indoor lights into electricity more efficiently compared to inorganic counterparts[3].

关键词： D/A power portable

Separation of primary solid phases from Al-Si alloy melts

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China Foundry 2014年第4期11卷 382-395页

作者： Ki young Kim School of Energy Materials and Chemical EngineeringKorea University of Technology and EducationChungnam 330-708Korea

The iron-rich solids formed during solidification of Al-Si alloys which are known to be detrimental to the mechanical,physical and chemical properties of the alloys should be *** the other hand,Al-Si hypereutectic alloys are used to extract the pure primary silicon which is suitable for photovoltaic cells in the solvent refining *** of the important issues in iron removal and in solvent refining is the effective separation of the crystallized solids from the Al-Si alloy *** paper describes the separation methods of the primary solids from Al-Si alloy melts such as sedimentation,draining,filtration,electromagnetic separation and centrifugal separation,focused on the iron removal and on the separation of silicon in the solvent refining process.

关键词： separation Al-Si alloys primary solids iron removal silicon extraction

Integrated Testing Environment of Instructor Station for SMART Simulator

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Open Journal of Modelling and Simulation 2015年第2期3卷 33-40页

作者： Joon Ku Lee Geun Ok Park Keung Koo Kim Woo Seok huh Kwang young Sohn Korea Atomic Energy Research Institute Daejeon City Korea MIRAE Engineering Co. Ltd. Daejon City Korea

SMART is the reactor that has been researched for many years by KAERI in order to provide the small-mid scale of power for typically seawater desalination. Now Korea Atomic Energy Research Institute (KAERI) has issued Standard Safety Analysis Report (SSAR) and acquired Standard Design Approval (SDA) for SMART. In order to conduct the design verification and validation for license, the integrated simulation test environment that is composed of 1) the system specific simulation codes formerly developed in the name of Nuclear Plant Analyzer (NPA) including NSSS and BOP simulation, 2) Instructor Station (IS), 3) Supervisory Control and Data Acquisition (SCADA), 4) operator and instructor Human Machine Interface (HMI), and 5) soft-controller has been considered as an important area for operator training and system validation. These sub-components has been designed and implemented for verifying and validating the SMART design and training of operators and for generating the backup data for licensing. This paper introduces the structure of integrated simulation test environment for SMART, explains the efforts to assist system-specific simulation code interface, and also addresses the effort for implementing and optimizing the test environment by maintaining its own simulation functionality and performance in order to review the simulation results efficiently.

关键词： System-Integrated Modular Advanced Reactor (SMART) Instructor Station (IS) Nuclear Plant Analyzer (NPA) Software Development Life Cycle (SDLC)

Comparison of mesophilic and thermophilic anaerobic digestions of thermal hydrolysis pretreated swine manure: Process performance,microbial communities and energy balance

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Journal of Environmental Sciences 2023年第4期126卷 222-233页

作者： Xiaohui Liu Changmin Lee Jae young Kim Department of Civil and Environmental Engineering Seoul National UniversitySeoul 08826Korea

Anaerobic digestion (AD) of swine manure (SM) commonly shows low biogas output and unsatisfactory economic performance. In this study, thermophilic AD (TAD, 50±1℃) was combined with thermal hydrolysis pretreatment (THP, 170℃/10 bar), to investigate its potential for maximizing biogas yield, securing successful digestion and microbial diversity, as well as improving energy balance. Four lab-scale continuously stirred tank reactors were operated for 300 days and compared with each other, i.e., reactor 1 (raw SM fed in mesophilic AD:RSM-MAD), reactor 2 (THP-treated SM fed in MAD:TSM-MAD), reactor 3 (RSM-TAD),and reactor 4 (TSM-TAD). The results showed that THP was efficient to increase methane production of SM, TSM-TAD mode led to the highest methane yield (129.8±40.5 mL-CH_(4)/gVS/day) among the tests (p 700 mg/L) or volatile fatty acids (> 6000 mg/L) accumulation compared with MAD in start-up phase, TSM-TAD treatment mode behaved a sustainable digestion process in a long-term operation. For TSM-TAD scenario, higher Shannon–Weaver (3.873) and lower Simpson index (0.061) indicated this mode ensured and enlarged the diversity of bacteria communities. Phylum Bathyarchaeota was dominant (59.3%-90.0%) in archaea community,followed by Euryarchaeota in the four reactors. RSM-MAD treatment mode achieved the highest energy output (4.65 GJ/day), TSM-TAD was less effective (-17.38 GJ/day) due to increased energy demands. Thus improving the energetic efficiency of THP units is recommended for the development of TSM-TAD treatment mode.

关键词： Thermal hydrolysis pretreatment Digestion temperature Process performances Microbial communities Energy balance