• Journal of the Korean institute of surface engineering
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• v.55 no.6
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• pp.319-327
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• 2022

Ion exchange membranes have been developed from laboratory tools to industrial products with significant technical and trade impacts in the last 70 years. Today, ion exchange membranes are successfully applied for water and energy for different electro-membrane processes. Hydrogen could be produced by electrochemical water splitting using renewable energy, for example, solar, biomass, geothermal and wind energy. This review briefly summarizes the recent studies reporting the state-of-the-art anion-exchange membrane water electrolysis, especially focusing on the enhancement of the durability of anion-exchange membranes. Anion-exchange membrane water electrolysis could be used as inexpensive non-noble metal electrocatalysts that are capable of producing low cost of hydrogen. However, the main challenge of anion-exchange membrane water electrolysis is to increase the performance and durability. In this mini review, the limiting factors of the durability and the technology enhancing the durability will be discussed for anion exchange membrane water electrolysis.

• Bulletin of the Korean Chemical Society
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• v.27 no.7
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• pp.961-971
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• 2006

Shape controlled synthesis of inorganic nanocrystals is one of the important issues in materials chemistry due to their novel shape dependent properties. Although various shapes of nanocrystals have been developed, a systematic account on the shape control of these nanocrystals still remains an important subject in materials chemistry. In this article, we will overview the recent developments in the geometrical shape evolution of semiconductor and metal oxide nanocrystals obtained by nonhydrolytic synthetic methods. Many structurally unprecedented motifs have appeared as zero-dimesional (D) polyhedrons, one-D rods and wires, two-D plates and prisms, and other advanced shapes such as branched rods, stars, and inorganic dendrites. Important parameters which determine the geometrical shapes of nanocrystals are also illustrated. In addition, as a possible application of such nanocrystals for biomedical sciences, we further describe their utilizations for cancer diagnosis through nanocrystal-assisted magnetic resonance imaging (MRI).

• The Journal of the Korean dental association
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• v.58 no.7
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• pp.448-459
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• 2020

In addition to extensive research on polymer and metal three-dimensional (3D) printing, ceramic 3D printing has recently been highlighted in various fields. The biggest advantage of 3D printing has the ability to easily create any complex shape. This review introduces the 3D printing technology of ceramics according to the type of material and deals with the latest related research in the industrial field including the biomedical engineering field. Finally, the future of ceramic 3D printing technology available in dentistry will be discussed.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2007.11a
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• pp.492-493
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• 2007

Organic field-effect transistors (OFETs) are of interest for use in widely area electronic applications. We fabricated a copper phthalocyanine(CuPc) based field-effect transistor with different metal electrode. So we need the effect of the substituent group attached to the phthalocyanine on the surface potential was investigated by Kelvin probe method with varying temperature of the substrate. We were obtained the positive shift of the surface potential for CuPc thin film. We observed the electron displacement at the interface between Au electrode and CuPc layer and we were confirmed by the surface potential measurement.

• Biomedical Science Letters
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• v.24 no.4
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• pp.329-333
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• 2018

The purpose of this study is to investigate the anti-inflammation effect of the mixture, consisting of a series of different ratio of Ecklonia cava extract and scoria. Also, to make more functional scoria powder into cosmetic material, studies on the toxicity by cell viability assay. Scoria is found in large amounts in Jeju Island, as an adsorbent of heavy metal ions ($Ni_2{^+}$, $Zn_2{^+}$, and $Cr_3{^+}$) in an aspect of its efficient utilization. Marine plants such as Ecklonia cava contain high amounts of polyphenolic antioxidants. The purpose of this study was to examine the anti-oxidative and anti-inflammation effects of combination of mixture of Eckloina cava extrat and scoria with optimal ratio. Therefore, this study suggested that combination of mixture of Eckloina cava extrat and scoria and its attenuated the oxidative and inflammatory reactions.

• The Journal of Korean Academy of Prosthodontics
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• v.53 no.4
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• pp.295-300
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• 2015

Purpose: The aim of this study was to evaluate the shear bond strength between Ni-Cr alloy and composite resin using universal adhesive systems coMPared to conventional method using metal primers. Materials and methods: For this study, a total of 120 cast commercial Ni-Cr alloy (Vera Bond 2V) disks were embedded in acrylic resin, and their surfaces were smoothed with silicon carbide papers and airborne-particle abrasion. Specimens of each metal were divided into 6 groups based on the combination of metal primers (Metal primer II, Alloy primer, Metal & Zirconia primer, MKZ primer) and universal adhesive systems (Single Bond Universal, All Bond Universal). All specimens were stored in distilled water at $37^{\circ}C$ for 24 hours. Shear bond strength testing was performed with a universal testing machine at a cross head speed of 1 m/min. Data (MPa) were analyzed using one-way ANOVA and the post hoc Tukey's multiple comparison test (${\alpha}$=.05). Results: There were significant differences between Single Bond Universal, All Bond Universal, Metal Primer II and Alloy Primer, MKZ Primer, Metal & Zirconia Primer (P<.001). Conclusion: Universal Adhesive system groups indicated high shear bond strength value bonded to Ni-Cr alloy than that of conventional system groups using primers except Metal Primer II. Within the limitations of this study, improvement of universal adhesive systems which can be applied to all types of restorations is recommended especially non-precious metal alloy. More research is needed to evaluate the effect of silane inclusion or exclusion in universal adhesive systems.

• Journal of Life Science
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• v.26 no.11
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• pp.1308-1312
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• 2016

Heavy metals such as gallium (Ga) cause serious physiological damage to exposed organisms, mostly of aquatic species. Ga one of the inter-metallic, transition elements increasingly being used in making high-speed semiconductors, such as Ga arsenide. The purposes of this study were to investigate the effects of Ga on acute toxicity, serum biochemical changes, and erythrocyte morphological changes in the blood stream of goldfish (Carassius auratus). Median lethal concentrations were determined in acute tests. The 96 hr $LC_{50}$ value was 9.15 mg/ml. Goldfish were exposed to different Ga concentrations (2.0, 4.0, and 8.0 mg/ml) for 30 days to assess its toxic effects. The results indicate that the measured serum biochemistry parameters (including glucose, blood urea nitrogen, creatinine, cholesterol, and triglyceride) of the Ga-exposed fish groups differed significantly from the untreated fish group. In addition, a change in the erythrocytes' morphology at a high concentration (8.0 mg/ml) of Ga exposure shows respiratory problems. Our results suggest that 2.0 mg/ml is proposed as a biologically safe concentration that can be used for establishing tentative water quality criteria concerning the same-size goldfish.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.62 no.6
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• pp.803-810
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• 2013

The purpose of this research is to analyze the effect of shape of the inductive textile electrode on the non-contact heart activity sensing, based on the magnetic-induced conductivity principle. Four types of the inductive textile electrodes were determined according to the combinations of the two shape features. A fiber-metal hybrid-typed conductive thread was developed and applied to materialization of the textile electrodes by embroidery method. The heart activity was extracted through the textile electrode sewn on a T-shirt. The experiments were implemented to constantly measure the heart activity for 20 seconds, in each case of 5 healthy male subjects. The heart activity signals acquired in each type of the inductive textile electrode were analyzed, 1)by drawing a comparison of morphology with those of ECG signal (LeadII), and 2)by calculation of the normalized mean and standard deviation of magnitude of the heart activity signals. The analysis resulted that the relatively better quality of signals were acquired in the 'square' types in the matter of whole shape, while the better results were obtained in 'donut' types in the matter of center hole. Accordingly, the relatively best quality of signals was obtained in the case of 'Square-Donut' type of the inductive textile electrode.

• Toxicological Research
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• v.32 no.2
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• pp.95-102
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• 2016

In the recent years, noble nanoparticles have attracted and emerged in the field of biology, medicine and electronics due to their incredible applications. There were several methods have been used for synthesis of nanoparticles such as toxic chemicals and high energy physical procedures. To overcome these, biological method has been used for the synthesis of various metal nanoparticles. Among the nanoparticles, silver nanoparticles (AgNPs) have received much attention in various fields, such as antimicrobial activity, therapeutics, bio-molecular detection, silver nanocoated medical devices and optical receptor. Moreover, the biological approach, in particular the usage of natural organisms has offered a reliable, simple, nontoxic and environmental friendly method. Hence, the current article is focused on the biological synthesis of silver nanoparticles and their application in the biomedical field.

• Journal of Ecology and Environment
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• v.36 no.1
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• pp.95-100
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• 2013

Many countries have adopted a single, well-described approach to the use of phototrophs for monitoring river water quality, which involves the use of indices related to diatom composition at a site. Increasingly these indices have focussed on assessing ambient phosphate concentration. However, there is a wide range of other methods which can provide additional information to make up for any weaknesses in the standard method. Some of these methods are reviewed briefly here. They can be useful, for instance, when considering temporal and spatial variability in phosphate concentration at a particular site and providing much more insight on heavy metal or pesticide pollution than revealed by routine water analysis.