• Journal of Sensor Science and Technology
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• v.30 no.5
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• pp.320-325
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• 2021

Biochemical oxygen demand (BOD) and chemical oxygen demand (COD) methods are conventional analytical methods to analyze water quality. Both of these methods are technically indirect measurement methods, require complicated preconditions, and are time-consuming. On the other hand, the total organic carbon (TOC) method is a direct and fast measurement method which is more intuitive and accurate than the BOD and COD methods. However, general TOC analysis methods involve complicated processes and high power consumption owing to the process of phase transition from liquid to gas by a high-temperature heater. Furthermore, periodic consumables are also required for the removal of inorganic carbon (IC). Titanium dioxide (TiO₂) is one of the most suitable photocatalysts for simple processes. Its usage involves low power consumption because it only reacts with the organic carbon (OC) without the requirement of any other reagents and extra processes. We investigated a TiO₂ photocatalyst-based TOC analysis for simple and affordable products. TiO₂-coated fiber substrate maintained under carbon included water was exposed to ultraviolet (UV) radiation of wavelength 365 nm. This method is suitable for the real-time monitoring of water pollution because of its fast reaction time. Its linear property is also sufficient to match the real value.

• Proceedings of the Materials Research Society of Korea Conference
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• 2012.05a
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• pp.73-73
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• 2012

Modern technology-driven society largely relies on hybrid electric vehicles or electric vehicles for eco-friendly transportation and the use of high technology devices. Lithium rechargeable batteries are the most promising power sources because of its high energy density but still have a challenge. Graphite is the most widely used anode material in the field of lithium rechargeable batteries due to its many advantages such as good cyclic performances, and high charge/discharge efficiency in the initial cycle. However, it has an important safety issue associated with the dendritic lithium growth on the anode surface at high charging current because the conventional graphite approaches almost 0 V vs $Li/Li^+$ at the end of lithium insertion. Therefore, a fundamental solution is to use an electrochemical redox couple with higher equilibrium potentials, which suppresses lithium metal formation on the anode surface. Among the candidates, $Li_4Ti_5O_{12}$ is a very interesting intercalation compound with safe operation, high rate capability, no volume change, and excellent cycleability. But the insulating character of $Li_4Ti_5O_{12}$ has raised concerns about its electrochemical performance. The initial insulating character associated with Ti4+ in $Li_4Ti_5O_{12}$ limits the electronic transfer between particles and to the external circuit, thereby worsening its high rate performance. In order to overcome these weak points, several alternative synthetic methods are highly required. Hence, in this presentation, novel ways using a synergetic strategy based on 1D architecture and surface coating will be introduced to enhance the kinetic property of Ti-based electrode. In addition, first-principle calculation will prove its significance to design Ti-based electrode for the most optimized electrochemical performance.

• Science of Emotion and Sensibility
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• v.18 no.1
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• pp.49-58
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• 2015

This paper investigated far-infrared emission characteristics of ZrC imbedded heat storage knitted fabrics for emotional garment. For this purpose, ZrC imbedded heat storage PET was spun with high viscosity PET imbedded ZrC powder on the core part and low viscosity PET on the sheath part by conjugated spinning method. Ingredient analysis and far-infrared emission characteristics assessment of spun filament were carried out by EDS and FT-IR spectrometer. Two kinds of knitted fabrics were made using texturized ZrC imbedded PET for measuring thermal characteristics of ZrC imbedded heat storage PET. Zr peak was certified by EDS measurement and it was confirmed that content of Zr was 19.29%. Far-infrared analysis revealed that emission power at the range of wavelength, $5{\sim}20{\mu}m$ was $3.65{\times}10^2W/m^2$, and emissivity was 0.906. Heat storage analysis by KES-F7 system revealed that $Q_{max}$ of ZrC imbedded PET knitted fabric was lower than that of regular PET one and warmth keepability rate was higher than that of regular one, which means that ZrC imbedded PET knitted fabric has heat storage property. Thermal conductivity of ZrC imbedded PET knitted fabric was higher than that of regular PET one which was caused by high thermal conductivity of Zr itself. Hand property of ZrC imbedded knitted fabric was not inferior compared to regular PET knitted fabric, which preferably was found to be dependent on knit structure and surface property.

• KEPCO Journal on Electric Power and Energy
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• v.6 no.2
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• pp.137-143
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• 2020

The CM247LC, a Ni-based superalloy material used for gas turbine hot gas path parts, is casted using directionally solidified technology to analyze the mechanical properties and microstructures through HIP (Hot Isostatic Pressing) and post-heat treatment, and to derive optimal HIP treatment conditions. The CM247LC material is being researched in various ways as an alternative material for prototyping gas turbine blades. In particular, the blade rotating part is exposed and operated in a high temperature and high-pressure environment, and when damaged, it may cause huge economic losses. Therefore, in order to use the CM247LC material as prototyping materials for gas turbine blades, the reliability of the microstructure and mechanical properties must be verified. In this study, after casting rod test specimens using CM247LC material by directionally solidified technology, after that the specimens were performed by HIP treatment and post-heat treatment to test two HIP conditions designed by KEPCO to derive the possibility of prototyping of CM247LC material and optimization of HIP treatment conditions. Additionally, the properties of CM247LC material were compared to the GTD111DS material using for 1,300℃ class gas turbine blades.

• Journal of the Korean Society of Clothing and Textiles
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• v.31 no.12
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• pp.1672-1681
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• 2007

Cationization is effective to complement the defects of Tencel blended fabrics by introducing new functions. For this purpose, we used chitosan, which is congenial to the human body, free of pollution, and easily reacted. Then, we compared it to the Tencel single fabrics. To perform such effective cationization, the fabrics were treated with chitosan after NaOH pretreatment and enzyme treatment thereof. After that, the fabrics were treated with a crosslinking agent and a softner. The dyeing property of the cationized Tencel blended fabrics and reactive dye, which is a type of anionic dye, show a high concentration in neutral salt and excellent repulsive power between the fabrics and the decreased dyes. The dyeing property of the chitosan treated fabrics represented better performances than that of untreated fabric in the lower concentration of neutral salt. Meanwhile, when it was dyed with certain acid dyes, the dyeing property of the chitosan treated fabrics showed better results due to the reaction of an amine group, which was introduced by chitosan treatment. Thus, the verification of the cationization of the Tencel blended fabrics was performed. The washing fastness of the Tencel blended fabrics showed a little bit better than that of the Tencel single fabric, and it represented a better performance in the dye with a reactive dye than that of an acid dye.

• Food Science and Preservation
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• v.24 no.7
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• pp.965-974
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• 2017

This study was carried out to investigate the effect of particle size of naked oat flour (NOF) on physicochemical property and antioxidant activity. The NOF was passed through $250{\mu}m$ and $160{\mu}m$ size sieves to obtain three fractions (fraction A: $250{\mu}m$ or more, fraction B: $160-250{\mu}m$, and fraction C: $160{\mu}m$ or less). Moisture, crude protein, crude fat, and crude ash contents of NOF were 8.4, 15.7, 10.0, and 1.8%, respectively, and these contents were increased as the particle size of NOF decreased. The mineral and free amino acid contents of NOF also had a similar tendency. The contents of total starch, amylose, starch damage, total dietary fiber, ${\beta}$-glucan, total phenolics, and flavonoids in NOF were 56.4%, 21.4%, 11.7%, 11.0%, 4.7%, $237.8{\mu}g/g$ and $90.9{\mu}g/g$, respectively. As the particle size of NOF decreased, total starch, amylose, and starch damage contents increased, whereas total dietary fiber, ${\beta}$-glucan, total phenolic and flavonoid contents decreased. Also, three antioxidant activities of NOF were closely correlated with their total phenolics and flavonoids contents, showing high correlation coefficient values ($R^2=0.87$ and 0.81, respectively).

• Tribology and Lubricants
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• v.22 no.6
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• pp.314-319
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• 2006

In this paper, the friction and wear characteristics of contact type sealing unit far a water turbine have been presented. The sealing unit for a small hydropower generation is to stop a leakage of circulating water from an outside of an impeller to an inside of a rolling bearing. The friction heating between a seal ring and a seal seat may radically increase a surface temperature in which increase a power loss and wear on the rubbing surface. The surface wear strongly affect to the seal life of a mechanical face seal. In this study, the hardness of a stainless steel in which is a heat-treated is 892.8 in Victors hardness and the hardness of silicone carbide of SiC is 714.1 in Victors hardness. The surface hardness of a heat-treated stainless steel is 25% high compared with that of a ceramic material of SiC. The contact modes of rubbing surfaces are a dry friction, a water film friction and a mixed friction that is contaminated by a dust, silt, and moistures, etc. These two factors of a contact rubbing modes and a material property are very important parameters on the tribological performance such as a friction and wear between a seal ring and a seal seat in primary sealing unit. The experimental result shows that the surface hardness of a seal material is very important on the friction coefficient and a wear volume. Thus, the results recommend higher hardness of a seal material, which may reduce a friction loss and increase a wear life of primary seal components.

• Journal of the Korean Applied Science and Technology
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• v.33 no.2
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• pp.324-332
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• 2016

The objective of this study was to investigate the antioxidant activity of Korean yam (Dioscorea batatas $D_{ECNE.}$) by different extraction solvents including 70% methanol, 70% ethanol and chloroform-methanol mixture (CM, 2:1, v/v). Raw yam was analyzed for its color property, total phenol content and antioxidant activity. Yam possessed high $L^*$ value and $H^{\circ}$ value, which were $81.64{\pm}2.59$ and $83.36{\pm}0.15$, respectively. Raw yam was found to have great antioxidant activity evaluated through ABTS [2,2′-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) diammonium salt] radical scavenging activity, DPPH (2,2-diphenyl-1-picrylhydrazyl) radical scavenging activity, reducing power, and ferric reducing antioxidant power. Total phenol contents of various extracts from raw yam increased in the following order: 70% methanol extract ($37.62{\pm}0.88mg\;CAE/g$), 70% ethanol extract ($43.38{\pm}0.66mg\;CAE/g$) and CM extract ($67.17{\pm}0.12mg\;CAE/g$), respectively. The same trend was also could be found in the ABTS radical scavenging activity, DPPH radical scavenging activity and ferric reducing antioxidant power assays. These results implied that Korean yam might play an important role in antioxidation and serve as the bio-health functional food to take a good part in prevention of human diseases and aging.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.24 no.1
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• pp.52-56
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• 2011

The ongoing Superconducting Fault Current Limiter(SFCL) development mainly has focused on the application of commercializaton and power system through combining with normal-conducting device, moving away from current-limiting method, which is solely dependant on the existing superconductor. Compared to the structural development above, on the other hand, the research on applying superconducting current-limiting element to SFCL, the heart of SFCL, still has a lot left to do, apart form traditional resistive type SFCL. In this study, we looked into the current limiting characteristic of SFCL using core and coil. YBCO coated conductor with stainless steel stabilizer layer was verified by the excellent of current-limiting element of the resistive type SFCL that has a high Jc and index as well as being superior in mechanical property. Also, we study temperature characteristics and resistance characteristics, max voltage, response time and current-limiting ability that can be an indicator as current-limiting element while applying to superconducting current-limiting element caused by variation of winding direction, winding ratio of SFCL using core and coil.

• Fashion & Textile Research Journal
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• v.15 no.2
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• pp.309-315
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• 2013

This study examines the difference of surface properties according to napping characteristic of artificial suedes, measuring surface structure observation, the contact/non-contact method roughness, warm-cool feeling of touch, and subjective hand evaluation. Surface and cross-section observations showed a discernible difference in fineness, curl, length, mount of napping, and covering power of base fabric. The surface properties of artificial suede evaluated by KES-FB4 showed that the shorter napping length the more smooth surface and the roughness increased reciprocally with friction resistance and surface contour when the nap length reaches a high level. The surface roughness measuring system applied a laser displacement sensor by a non-contact method to assess napping characteristic and the base fabric and napping height. Surface roughness decreased when napping was uniformly covered with base fabric; however, the surface roughness increased specifically with the uneven covering power of the base fabric. For qmax of the suedes, those that had short and smaller amounts of napping increased; however, the napping of length and amount at some stage generated a low qmax value. The warm sensation in all suedes were strongly perceived, but the cool sensation of the perception was lower in the subjective evaluation. Smoothness and softness were perceived when the suede has a long and large amount napping; however, smoothness and hardness were perceived when the suede was short and with the uneven covering power.