• Korean Journal of Materials Research
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• v.5 no.7
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• pp.794-801
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• 1995

To connect the driver IC and Al coated glass, a method has been developed to plate electrolessly Ni on Al/PR system. It Is necessary to pretreat Al to remove oxide film before plating. In order to find pretreatment process which does not damage photoresist or glass, alkaline and fluoride zincate process have been investigated. Because photoresist and aluminum thin film can easily dissolve in alkaline solution, it is considered that the fluoride zincate process was a suitable one. After immersion in the zincate solution containing 1.5 g/$\ell$ ammonium bifluoride and 100 g/$\ell$ zinc sulfate, electroless nickel plating could be performed. The additive in the zincate solution and thiourea in the plating solution increased smoothness of the plated surface. Acld dip could improve the uniformit of the surface.

• Proceedings of the Korean Institute of Surface Engineering Conference
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• 2017.05a
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• pp.96.2-96.2
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• 2017

This research was conducted to investigate the electrochemical properties of the thin air-formed oxide film-covered AZ31 Mg alloy. In this work, native air-formed oxide films on AZ31 Mg alloy samples were prepared by knife-abrading method and the changes in the electrochemical properties of the air-formed oxide film were investigated in seven different electrolytes containing the following anions $Cl^-$, $F^-$, $SO{_4}^{2-}$, $NO_3{^-}$, $CH_3COO^-$, $CO{_3}^{2-}$ and $PO{_4}^{3-}$. It was observed from open circuit potential (OCP) transients that the potential initially decreased before gradually increasing again in the solutions containing only $CO{_3}^{2-}$ or $PO{_4}^{3-}$ ions, indicating the dissolution or transformation of the native air-formed oxide film into new more protective surface films. The Nyquist plots obtained from electrochemical impedance spectroscopy (EIS) showed that there was growth of new surface films with immersion time on the air-formed oxide film-covered specimens in all the electrolytes; the least resistive surface films were formed in fluoride and sulphate baths whereas the most protective film was formed in phosphate bath. The potentiodynamic polarization curves illustrated that passive behaviour of AZ31 Mg alloy under anodic polarization appears only in $CO{_3}^{2-}$ or $PO{_4}^{3-}$ ions containing solutions and at more than $-0.4V_{Ag/AgCl}$ in $F^-$ ion containing solution.

• Korean Journal Plant Pathology
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• v.10 no.2
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• pp.112-118
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• 1994

Forth microbial isolates out of 167 isolates from the soil of controlled cultivation areas inhibited mycelial growth of Rhizoctonia solani AG2-1 causing the strawberry bud rot in vitro. Among the isolates, Kr013 and Kr020 showed suppressive effect to R. solani AG2-1 on seedlings of chinese cabbage treated by root immersion, charcoal carrier granule and drenching on 1.0% infested soil in pot. Furthemore, the corresponding effect was also revealed when the charcoal carrier granule of the isolates were treated on the seedling of strawberry that were planted on the planting hole in pot. To examine the effects of biological control in green house, it had been tested the infection rates by using two different treatments. First, the strawberry runner were planted on the nursery soil mixed with 20% charcoal carrier granule of Kr013 and Kr020 isolate respectively, and grown for 20 days before transplanting. Then the young plants form the mother plant were separated and transplanted on the 1.0% infested soil. Another method was that the charcoal carrier of Kr013 and Kr020 isolates applied to planting hole of 1.0% infested soil just before transplanting. Then the young plants were grown for 20 days on the sterilized nursery soil before transplanting. From the results, the effects of biological control was significantly higher on former treatment (e.g. the infection rates were 7.3 and 5.7%, respectively) than on the latter treatment (e.g. the corresponding value were 16.7 and 15.7%, respectively). The antagonistic isolates of Kr013 and Kr020 were respectively identified as Pseudomonas cepacia with the similarity of 55.0% and 60.0% by using the Biolog GN Microplate system.

• Journal of the Korean Society for Nondestructive Testing
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• v.37 no.1
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• pp.37-43
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• 2017

Ultrasonic transducers with high resolution and resonant frequency are required to detect small defects (less than hundreds of ${\mu}m$) by ultrasonic testing. The resonance frequency and resolution of an ultrasonic transducer are closely related to the thickness of piezo-electric materials, backing materials, and the electric impedance matching technique. Among these factors, electrical impedance matching plays an important role because it can reduce the loss and reflection of ultrasonic energy differences in electrical impedance between an ultrasonic transducer and an ultrasonic defects detecting system. An LC matching circuit is the most frequently used electric matching method. It is necessary for the electrical impedance of an ultrasonic transducer to correspond to approximately $50{\Omega}$ to compensate the difference in electrical impedance between both connections. In this study, a 15 MHz immersion ultrasonic transducer was fabricated and an LC electrical impedance circuit was applied to that for having broad-band frequency characteristic.

• Proceedings of the Korean Vacuum Society Conference
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• 2011.08a
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• pp.202-202
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• 2011

The research of 3-dimensional (3-D) scaffold for tissue engineering has been widely investigated as the importance of the 3-D scaffold increased. 3-D scaffold is needed to support for cells to proliferate and maintain their biological functions. Furthermore, its architecture defines the shape of the new bone and cartilage growth. Polycaprolactone (PCL) has been one of the most promising materials for fabricating 3-D scaffold owing to its excellent mechanical property and biocompatibility. However, there are practical problems for using it, in vitro and in vivo; extracellular matrix components and nutrients cannot penetrate into the inner space of scaffold, due to its hydrophobic property, and thus cell seeding and attachment onto the inner surface remain as a challenge. Thus, the surface modification strategy of 3-D PCL scaffold is prerequisite for successful tissue engineering. Herein, we utilized a mussel-inspired approach for surface modification of 3-D PCL scaffold. Modification of 3-D PCL scaffolds was carried out by simple immersion of scaffolds into the dopamine solution and stimulated body fluid, and as a result, hydroxyapatite-immobilized 3-D PCL scaffolds were obtained. After surface modification, the wettability of 3-D PCL scaffold was considerably changed, and infiltration of the pre-osteoblastic cells into the 3-D scaffold followed by the attachment onto the surface was successfully achieved.

• Journal of the Korean institute of surface engineering
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• v.45 no.6
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• pp.219-225
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• 2012

The aim of the present study was to investigate the corrosion resistance and characteristics of passive layer between naturally passivated and chemically passivated duplex stainless steel, UNS S31803 (EN 1.4462) using CPT, XPS, and EIS. The treatment of $HNO_3$(II) and $HNO_3$(III) in ASTM A 967 was applied. In case of chemically passivated specimen, CPT of $HNO_3$(II) and $HNO_3$(III) were higher than that of naturally passivated specimen. In addition, from XPS results, the protectiveness index (Cr/(Fe+Cr)) of chemically passivated specimens was also higher than that of naturally passivated specimen. The reason for this result is considered due to post-cleaning treatment in chemical passivation process, that is, immersion in $Na_2Cr_3O_7$ solution. The fact that $HNO_3$(II) passivation treatment showed the highest film resistance and 'n', which is exponent related with constant phase element (CPE) of passivation film, was in good agreement with results of CPS and XPS. The chemical passivation treatment was an effective method to improve corrosion resistance of duplex stainless steel.

• Transactions of the Korean Society of Automotive Engineers
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• v.16 no.5
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• pp.1-7
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• 2008

A study of new materials that are light-weight, high in strength has become vital to the machinery of auto industries. But then, there are a lot of problems with developing such materials that require expensive tools, and a great deal of time and effort. Therefore, the improvement of fatigue strength and fatigue life are mainly focused on by adopting residual stress. And Influence of corrosive condition for corrosion fatigue crack was investigated, after immersing in 3.5%NaCl, $10%HNO_3$+3.5%HF, $6%FeCl_3$. The immersion period was performed for 365days. The compressive residual stress was imposed on the surface according to each shot velocity based on shot peening, which is the method of improving fatigue life and strength. Fatigue life shows more improvement in the shot peened material than in the un peened material in corrosion conditions. The threshold stress intensity factor range was decreased in corrosion environments over ambient. Compressive residual stress of surface on the Shot-peen processed operate resistance force of fatigue crack propagation. The fatigue crack growth rate of the Shot-peened material was lower than that of the un peened material. Also m, fatigue crack growth exponent and number of cycle of the shot peened material was higher than that of the un peened material. That is concluded from effect of da/dN.

• Food Science and Preservation
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• v.6 no.3
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• pp.308-312
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• 1999

To develop the effective method for chestnut peeling, we examined the effect of peeling by acid and alkali treatment on their concentration, immersion temperature and time. Furthermore the physical properties of chestnut were investigated. In alkali treatment, 9% NaOH treated at 40$^{\circ}C$ for 9min was the most efficient for peeling outer peel, while acid treatment was less effective. But in the peeling of inner peel, acid treatment was more effective than alkali, especially, 3% HCIO$_4$ treated at 50$^{\circ}C$ for 30 min was the most effective. The correalation coefficient between weight and inner(outer) peel weight was higher than other physical properties, and multiple regression equation was established for predicting inner(outer) peel weight.

• Membrane Journal
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• v.22 no.3
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• pp.178-190
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• 2012

Flat sheet membranes were prepared with polysulfone (PSF) by an immersion precipitation phase inversion method. Membranes were prepared with PSF/N-methylpyrrolidone (NMP)/polyvinylpyrrolidone (PVP)/phosphoric acid casting solution and water coagulant. By using the successive process of the vapor-induced phase inversion (VIPS) followed by the nonsolvent-induced phase inversion (NIPS), the effect of phosphoric acid addition to casting solution on morphology and permeability of membrane was studied. The mean pore size, the porosity, and the water flux of membranes were increased by the addition of small amount of phosphoric acid. Furthermore, the morphology of the prepared membranes were changed from a dense sponge-like structure to highly enhanced asymmetric structure. PSF/NMP/PVP/phosphoric acid/2-butoxyethanol (BE) casting solution were prepared and cast the successive VIPS-NIPS process with same experimental condition. Due to the addition of BE to casting solution, the mean pore size and almost 0.1 ${\mu}m$ and the water flux increased about 10 to 12 $L/cm^2{\cdot}min{\cdot}bar$.

• The Journal of the Korea Contents Association
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• v.18 no.1
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• pp.250-257
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• 2018

Today, the integration of the rapid development of ICT and the smart devices moves our lives quickly into an online community environment through not only quick and easy information search but also various social media. Accordingly, individual activities in the smart media environment are pouring out vast quantities of data in many fields, accumulating a tremendous amount of data. The everyday data of individuals is reproducing different values from the previous ones, while suggesting new customized services that utilize them in various fields. Recently, big data utilization has attracted a great attention in the field of healthcare. Especially, development of healthcare service linked with mobile is expected to bring a new paradigm in this field. In this study, creation of a 3D avatar character model as a means to transfer information to individuals more efficiently is proposed in the development of mobile customized service for health promotion and growth prediction of children and adolescents, at the same time, an effective visual expression method to have a sense of immersion and unity is searched.