• Journal of Mechanical Science and Technology
• /
• v.16 no.4
• /
• pp.501-511
• /
• 2002

This paper presents a study of the effect of rolling temperature, roll gap (pass height), initial specimen size and steel grades of specimens on the roll force in round-oval-round pass sequence by applying approximate method and verifications through single stand pilot rod rolling tests. The results show that the predicted roll forces are in good agreement with the experimentally measured ones. The approximate model is independent of the change of roll gap, specimen size and temperature. Thus, the generality of the prediction methodology employed in the approximate model is proven. This study also demonstrates that Shida's constitutive equation employed in the approximate model needs to be corrected somehow to be applicable for the medium and high carbon steels in a lower temperature interval (700∼900$\^{C}$).

• Journal of Korea Foundry Society
• /
• v.11 no.5
• /
• pp.406-413
• /
• 1991

Ductile cast iron(DCI) with a multi-phase(ferrite-bainite-martensite) structures was produced by various special heat treatment. Intercritical heat treatment(I. C.), intermediate heat treatment(I. M.) and step quenching(S. Q.) were used to strengthen and toughen the fracture initiation sites such as graphite-marix interfaces and eutectic cell boundaries in DCI. The purpose of this study was to investigate of DCI by the special heat treatment. (I. C., I. M., and S. Q.) At a result, bainite nucleation rate at higher temperature was higher than that of at lower temperature, and shapes of bainite and martensite became bar /spheroidal type with increase of isothermal transformation time.

• Fisheries and Aquatic Sciences
• /
• v.3 no.1
• /
• pp.1-7
• /
• 2000

Different substrata fixed as the roof (for shadow) on artificial iron reef had been developed as a tool for valuable fishery resources. The experiment was set up on a sandy bottom substratum at 8m depth in Muronohana, Ikata, Japan. Within one month of placement of the plates, diatoms dominated the experimental plates with a coverage of $100\%$ approximately. Enteromorpha intestinalis and Colpomenia sinuosa dominated within three months after the placement. E. intestinalis coverage on substrata was estimated $7\%$ on the plate shaped iron bar, $12-14\%$ on concrete plates, $18\%$ on the plate fixed pebble, $61\%$ on the plate to accumulated wood, and 80-100% on the steel materials plate. Whereas after four months of placement, C. sinuosa coverage on plates became $1-36\%$ on different plates, and $100\%$ on the plate to accumulated wood. The differences in E. intestinalis and C. sinuosa colonization on the different substrata were probably due to variations in their surface roughness influencing the settlement of zoospores, and thus gametophyte. development. After five months of placement, the above two species slowly disappeared.

• Journal of Korea Foundry Society
• /
• v.4 no.2
• /
• pp.96-101
• /
• 1984

The morphologies of eutectic cell formed during solidification affect on the mechanical properties in high Cr cast iron. In order to investigate the influence of Si on the structure, five kinds of specimen containing 16.42% Cr with varying amount of Si (0.51%, 1.17%, 2.22%, 2.71%, 3.56%) were poured into shell mould preheated $330^{\circ}C$ at $1510^{\circ}C$. The effect of Si on matrix in hypo-eutctic Cr cast iron (2.48% C, 16.42%) were studied through its mechanical tests and observation of microstructure using of metallurgical microscope, EPMA, SEM and Image analyzer systematically. The results obtained from the above studies are as follows: 1. Because of ${\Delta}T$ decreasing with increasing Si content, the morpologies of colony change into uniform bar-type carbide from plate-type ones, moreover eutectic colony size (Ew) becomes narrow and spacing of carbide wider. 2. As Si content increases, the amount of carbides also increases and most of Cr were dissolved in carbides while Si in matrix. 3. The hardness, tensile strength and wear resistance were increasing while impact value decreased with increasing Si content. 4. In fracture section, small amount of dimple pattern was observed in less than 1.17% Si but more than 2.22% Si river pattern was presented.

• Corrosion Science and Technology
• /
• v.18 no.4
• /
• pp.121-128
• /
• 2019

Electrochemical Impedance Spectroscopy (EIS) was used to predict corrosion behaviour of metallic Cultural Heritage assets in two monitoring campaigns: 1) an iron bar chain exposed indoor from over 500 years in the Notre Dame Cathedral in Amiens (France); and 2) a large weathering steel sculpture exposed outdoor from tens of years in Ferrara (Italy). The EIS portable instrument employed was battery operated. In situ EIS measurements on the iron chain could be used to investigate the phenomena involved in the electrochemical interfaces among various corrosion products and assess and predict their corrosion behaviour in different areas of the Cathedral. Meanwhile, the sculpture of weathering steel, like most outdoor artefacts, showed rust layers of different chemical composition and colour depending on the orientation of metal plates. The EIS monitoring campaign was carried out on different areas of the artefact surface, allowing assessment of their protective effectiveness. Results of EIS measurements evidenced how employing a simple test that could be performed in situ without damaging the artefacts surface is possible to quickly gain knowledge of the conservation state of an artefact and highlight potential danger conditions.

• Journal of Plant Biotechnology
• /
• v.34 no.2
• /
• pp.145-152
• /
• 2007

Lactoferrin is an 80-kDa iron-binding glycoprotein known to exert many biological activities, such as facilitating iron absorption and having antimicrobial and anti-inflammatory effects. Rice can be a useful target for edible food plants to introduce human lactoferrin, because it has lower allergenicity and is likely to be safer than microorganisms or transgenic animals. A cDNA fragment encoding human lactoferrin (HLF) driven by the maize polyubiquitin promoter, along with herbicide resistance gene (bar) driven by CaMV 35S promoter, was introduced into rice (Oryza sativa L. cv. Dong Jin) using the Agrobacterium -mediated transformation system. Putative transformants were initially selected on the medium containing bialaphos. The stable integration of the bar and HLF genes into transgenic rice plants was further confirmed through polymerase chain reaction (PCR) and Southern blot analyses. The expression of the full length HLF protein from various tissues such as grains and young leaves of transgenic rice was verified by Western blot analysis. Analysis of progeny also demonstrated that introduced genes were stably inherited to the next generation at the Mendelian fashion.

• Geophysics and Geophysical Exploration
• /
• v.12 no.4
• /
• pp.338-346
• /
• 2009

Integrated analysis of GPR, impact echo (IE) and impulse response (IR) was performed to detect the rear cavity of concrete for a test-bed which was made with the same scale and component ratio to the real concrete structure. The test-bed was designed to be capable of observing various response reflecting the existence of iron reinforcing bar and cavity. GPR survey did not clearly resolve the existence of the cavity, although distinguishable responses were observed in the presence of the cavity. In contrast, IE and IR method showed distinct responses, indicating the existence of the cavity. Finally, integrated application of the three methods makes it possible to exactly identify the location of the cavity, although the iron reinforcing bar made a little variation of response.

• Journal of Conservation Science
• /
• v.33 no.6
• /
• pp.519-532
• /
• 2017

Studies on ancient ironmaking technologies are primarily based on archaeological surveys and scientific analysis data, and technological systems are examined by comparing the results of restorative experiments. In this study, to examine the ancient iron production technologies such as smelting and smithing in the Jungwon area, a restoration experiment was conducted based on archaeological data, and the iron and slag, etc. produced in the experiment were analyzed. Further, the changes in physicochemical properties due to the smelting of the raw material, specifically, iron ore were determined, and the smithing process, which involves fabrication of ironwares, was analyzed along with the characteristics of each step. In the case of smelting, increasing recovery rates and production of high-quality primary iron material were important for the following processes. For the iron bars produced through the smithing process, it was found that quality improvements made by reducing physical defects such as inclusions or gas holes were more important than the composition of the iron itself. The study also yielded comparative study data for various byproducts, such as smithing slag, which could be utilized in other ironmaking technology studies.

• Conservation Science in Museum
• /
• v.11
• /
• pp.9-16
• /
• 2010

The National Chuncheon Museum has carried out a conservation process in order to prevent corrosion of the seated iron Śākyamuni Buddha statue from Goreyo Dysnasty for its exhibition. Before the conservation process, the surface of the artifact showed exfoliation and the artifact was damaged from rear to legs so exhibition was impossible. Therefore a process to get rid of pollution and to reinforce and protect the artifact was carried out. Before the reinforcing process, a basic test was carried out using micro crystalline wax type with reference to foreign and domestic experiment results. As a result, as wax(in xylene) 5wt% of Dongnam petrochemical Ltd. showed no efflorescence and little change in surface color and was convenient to use, it was chosen as a reinforcing agent and used to suppress corrosion. For the restoration of damaged parts, an internal support was made and used with an epoxy resin, allowing removable restoration, thus increasing effectiveness for exhibition.

• Polymer(Korea)
• /
• v.24 no.4
• /
• pp.505-512
• /
• 2000

The mixture density data for poly(lactide-co-glycolide) [PLGA] with supercritical $CO_2$, CHF$_3$ and CHClF$_2$ were obtained in the temperature range of 27 to 10$0^{\circ}C$ and at pressures as high as 3000 bar (PLGA$_{x}$, Where the molar concentration of glycolide in the backbone, x, range from 0 to 50 mol%). The PLA-$CO_2$, PLA-CHF$_3$, and PLA-CHClF$_2$ systems dissolve in the pressure less than 1430 below 700, and below 100 bar, respectively. The mixture density shows from 1.084 to 1.334 g/cm$^3$ at temperatures from 27 to 93$^{\circ}C$. The PLGA$_{15}$ -$CO_2$ mixture dissolves at pressures of below 1900 bar and the mixture density is in the range of 1.158 to 1.247 g/cm$^3$ at temperatures between 37 and 92$^{\circ}C$. The solubilities of the PLGA$_{25}$ for $CO_2$, CHF$_3$, and CHClF$_2$ are shown to pressure as high as 2390, 1470, and 118 bar, respectively, and the mixture density exhibits iron 1.154 to 1.535 g/cm$^3$ at temperatures from 29 to 81$^{\circ}C$. The PLGA$_{50}$-$CO_2$ system does not dissolve at 24$0^{\circ}C$ and 3000 bar while the PLGA$_{50}$-CHCIF$_2$ does easily at 5$0^{\circ}C$ and 100 bar. The mixture density for the PLGA-CHClF$_2$ system increases even at low pressures as the glycolide molar concentration increases.es.es.