• Applied Microscopy
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• v.45 no.4
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• pp.208-213
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• 2015

Nanomanipulators installed in focused ion beam (FIB), which is used in the lift-out of lamella when preparing transmission electron microscopy specimens, have recently been employed for electrical resistance measurements, tensile and compression tests, and in situ reactions. During the pick-up process of a single nanowire (NW), there are crucial problems such as Pt, C and Ga contaminations, damage by ion beam, and adhesion force by electrostatic attraction and residual solvent. On the other hand, many empirical techniques should be considered for successful pick-up process, because NWs have the diverse size, shape, and angle on the growth substrate. The most important one in the in-situ precedence, therefore, is to select the optimum pick-up process of a single NW. Here we provide the advanced methodologies when manipulating NWs for in-situ mechanical and electrical measurements in FIB.

• Journal of the Korean Vacuum Society
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• v.1 no.1
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• pp.168-175
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• 1992

The surface and interface morphology as well as the sheet resistance, and uniformity of TiSiz film are significantly improved and the lateral titanium silicide growth over the oxide spacer is minimized by the use of ion beam mixing and rapid thermal annealing in nitrogen ambient. In addition, TiSiz film formations on TiISi and TiISiOz system were also studied.

• Korean Journal of Plant Resources
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• v.18 no.3
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• pp.359-366
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• 2005

Effects of neutron beam irradiation on seed germination, growth and RAPD pattern of tobacco (Nicotiana tabacum L. cv.; N. plumbaginifolia) and rice (Orya sativa L. cv.) plants were estimated. Seed germination rate was not significantly changed by the neutron beam treatment in both tobacco and rice seeds. And there was no significant differance in growth of the plants by the neutron beam treatment. Interestingly, however, some of morphological changes, including leaf shape (about $36\%$), stem color and leaf color were observed in neutron beam treated tobacco plants. In addition, abnormal flower in petal was observed in the neutron beam treated plant. This results indicate that neutron beam is able to use as an effective mutagen in plant mutations. Scorable products from 20 primers were obtained by RAPD analysis in the leaves of the beam irradiated tobacco plants and most of the plants showed the similar band patterns.

• Journal of the Korean Vacuum Society
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• v.6 no.S1
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• pp.110-114
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• 1997

Development of metal ion source growth of high quality Cu metal film formation of non-stoichiometric $SnO_2$ films of Si(100), and modification fo polymer surface by low enregy ion beam have been carried out at KIST Ion Beam Lab. A new metal ion source with high ion beam flux has been developed by a hybrid ion beam (HIB) deposition and non-stoichiometric $SnO_2$ films are controlled by supplying energy. The ion assisted reaction (IAR) in which keV ion beam is irradiated in reactive gas environment has been deveolped for modifying the polymers and enhancing adhesion to other materials and advantages of the IAR have been reviewed.

• Structural Engineering and Mechanics
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• v.72 no.3
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• pp.367-382
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• 2019

This paper presents experimental and analytical investigations on additional fixed-end rotations resulting from the strain penetration of high-strength reinforcement in reinforced concrete (RC) beam-column connections under monotonic loading. The experimental part included the test of 18 interior beam-column connections with straight long steel bars and 24 exterior beam-column connections with hooked and headed steel bars. Rebar strains along the anchorage length were recorded at the yielding and ultimate states. Furthermore, a numerical program was developed to study the effect of strain penetration in beam-column connections. The numerical results showed good agreement with the test results. Finally, 87 simulated specimens were designed with various parameters based on the test specimens. The effect of concrete compressive strength ($f_c$), yield strength ($f_y$), diameter ($d_b$), and anchorage length ($l_{ah}$) of the reinforcement in the beam-column connection was examined through a parametric study. The results indicated that additional fixed-end rotations increased with a decrease in $f_c$ and an increase in $f_y$, $d_b$ and $l_{ah}$. Moreover, the growth rate of additional fixed-end rotations at the yielding state was faster than that at the ultimate state when high-strength steel bars were used.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2002.11a
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• pp.796-799
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• 2002

BSCCO thin films are fabricated via a co-deposition process at an ultra-low growth rate using ion beam sputtering. The sticking coefficient of Bi element exhibits a characteristic temperature dependence. This temperature dependence of the sticking coefficient was explained consistently on the basis of the evaporation and sublimation processes of Bi$_2$O$_3$.

• Steel and Composite Structures
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• v.20 no.4
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• pp.913-930
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• 2016

It is common practice to use Reduced Web Beam Sections (RWBS) in steel moment resisting frames. Perforation of beam web in these members may cause stress and strain concentration around the opening area and facilitate ductile fracture under cyclic loading. This paper presents a numerical study on the cyclic fracture of these structural components. The considered connections are configured as T-shaped assemblies with beams of elongated circular perforations. The failure of specimens under Ultra Low Cycle Fatigue (ULCF) condition is simulated using Cyclic Void Growth Model (CVGM) which is a micromechanics based fracture model. In each model, CVGM fracture index is calculated based on the stress and strain time histories and then models with different opening configurations are compared based on the calculated fracture index. In addition to the global models, sub-models with refined mesh are used to evaluate fracture index around the beam to column weldment. Modeling techniques are validated using data from previous experiments. Results show that as the perforation size increases, opening corners experience greater fracture index. This is while as the opening size increases the maximum observed fracture index at the connection welds decreases. However, the initiation of fracture at connection welds occurs at lower drift angles compared to opening corners. Finally, a probabilistic framework is applied to CVGM in order to account for the uncertainties existing in the prediction of ductile fracture and results are discussed.

• Electrical & Electronic Materials
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• v.10 no.5
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• pp.425-433
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• 1997

BSCCO thin films have been fabricated by co-deposition at an ultralow growth rate using ion beam sputtering(IBS) method. The growth rates of the films was set in the region from 0.17 to 0.27 nm/min. MgO(100) was used as a substrate. In order to appreciate stable existing region of Bi 2212 phase with temperature and ozone pressure, the substrate temperature was varied between 655 and 82$0^{\circ}C$ and the highly condensed ozone gas pressure(PO$_3$) in vacuum chamber was varied between 2.0$\times$10$^{-6}$ and 2.3$\times$10$^{-5}$ Torr. Bi 2212 phase appeared in the temperature range of 750 and 795$^{\circ}C$ and single phase of Bi 2201 existed in the lower region than 785$^{\circ}C$. Whereas, PO$_3$dependance on structural formation was scarcely observed regardless of the pressure variation. And high quality of c-axis oriented Bi 2212 thin film with T$_{c}$(onset) of about 90 K and T$_{c}$(zero) of about 45 K is obtained. Only a small amount of CuO in some films was observed as impurity, and no impurity phase such as CaCuO$_2$was observed in all of the obtained films.lms.

• Proceedings of the Materials Research Society of Korea Conference
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• 2003.03a
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• pp.99-99
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• 2003

The growth of GaN on Si is of great interest due to the several advantages : low cost, large size and high-quality wafer availability as well as its matured technology. The crystal quality of GaN is known to be much influenced by the surface pretreatment of Si substrate[1]. In this work, the properties of GaN overlayer grown on ion beam modified Si(111) have been investigated. Si(111) surface was treated RIB with 1KeV-N$_2$$\^$+/(at 1.9 ${\times}$ 10$\^$-5/) to dose ranging from 5${\times}$10$\^$15/ to 1${\times}$10$\^$17/ prior to film growth. GaN epilayers were grown at 1100$^{\circ}C$ for 1 hour after growing AlN buffer layers for 5∼30 minutes at 1100$^{\circ}C$ in Metal Organic Chemical Vapor Deposition (MOCVD). The properties of GaN epilayers were evaluated by X-Ray Diffraction(XRD), Raman spectroscopy, Photoluminescence(PL) and Hall measurement. The results showed that the ion modified treatment markedly affected to the structural, optical and electrical characteristic of GaN layers.

• The Plant Pathology Journal
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• v.31 no.2
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• pp.176-180
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• 2015

Postharvest diseases cause losses in a wide variety of crops around the world. Irradiation, a useful nonchemical approach, has been used as an alternative treatment for fungicide to control plant fungal pathogens. For a preliminary study, ionizing radiations (gamma, X-ray, or e-beam irradiation) were evaluated for their antifungal activity against Botrytis cinerea, Penicillium expansum, and Rhizopus stolonifer through mycelial growth, spore germination, and morphological analysis under various conditions. Different fungi exhibited different radiosensitivity. The inhibition of fungal growth showed in a dose-dependent manner. Three fungal pathogens have greater sensitivity to the e-beam treatment compared to gamma or X-ray irradiations. The inactivation of individual fungal-viability to different irradiations can be considered between 3-4 kGy for B. cinerea and 1-2 kGy for P. expansum and R. stolonifer based on the radiosensitive and radio-resistant species, respectively. These preliminary data will provide critical information to control postharvest diseases through radiation.