• 한국세라믹학회지
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• 제48권1호
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• pp.52-56
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• 2011

Silicon carbide (SiC) is a candidate material for heat exchangers for VHTR (Very High Temperature Gas Cooled Reactor) due to its refractory nature and high thermal conductivity. This research has focused on demonstration of physical properties and mock-up fabrication for the future heat exchange applications. It was found that the SiC-based components can be applied for process heat exchanger (PHE) and intermediate heat exchanger (IHX), which are operated at $400{\sim}1000^{\circ}C$, based on our examination for the following aspects: optimum fabrication technologies (design, machining and bonding) for compact design, thermal conductivity, corrosion resistance in sulfuric acid environment at high temperature, and simulation results on heat transferring and thermal stress distribution of heat exchanger mock-up.

• 한국세라믹학회지
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• 제43권8호
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• pp.451-457
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• 2006

The solid solutions of ${\alpha}-Si_3N_4$, i.e. ${\alpha}$-sialons, are represented by a general formula of $M_x(Si,Al)_{12}(O,N)_{16}$, in which metal ions (M) dissolve into interstitial sites to stabilize the structure. Processing methods for the fabrication of ${\alpha}/{\beta}$-sialon composites, ${\alpha}-sialon/{\beta}Si_3N_4$ composites, refractory or tough ${\alpha}$-sialon ceramics have been developed to tailor the mechanical properties. Translucent and photoluminescent properties have been investigated recently. A number of applications of ${\alpha}$-sialon ceramics as engineering and optical ceramics are also presented.

• 한국전기전자재료학회논문지
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• 제15권4호
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• pp.349-355
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• 2002

The ionic conductivity of cubic solid solutions in the systems of CaO-$ZrO_2$, $Y_2O_3-ZrO_2$ prepared by SHS was examined. The higher conductivity appears to be related to a lower activation energy rather than to the number of oxygen vacancies dictated by composition. Conductivity-temperature data was obtained at 1000 $^{\circ}C$ in atmosphere of low oxygen partial pressure (~$10^{-40}$ atm) for $Y_2O_3-ZrO_2$ cubic solid solutions. The data indicated that these materials could be reduced, and the decree of reduction would be related with the measuring electric field.

• 한국결정성장학회지
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• 제11권2호
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• pp.78-84
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• 2001

The binary forsterite($Mg_2SiO_4$)/spinel ($MgAl_2O_4$) system, a possible refractory for industrial applications, is investigated for their density and grain growth the same firing conditions as the each component material between $1400^{\circ}C$ and $1700^{\circ}C$ ($1650^{\circ}C$). The forsterite grain growth exponent is established to be equal to 5 for all compositions within this binary system. Generally; the spinel addition to forsterite inhibited the forsterite grain growth. The activation energies for the forsterite grain growth of the eight compositions(weight ratio of forsterite/spinel) within the binary system are determined to be: 952$\pm$79(95/5), 363$\pm$37(90/10), 219$\pm$21(80/20), 220$\pm$44(70/30), 112$\pm$16(50/50), 112$\pm$23(30/70), 198$\pm$26(10/90), and 121$\pm$12(5/95) KJ/mol. The more forsterite is contained within the binary system, the higher value the activation energy for forsterite grain growth. It is considered that the forsterite grain growth at the higher forsterite compositions are more inhibited by spinel than that of the lower forsterite compositions.

• 복합신소재구조학회 논문집
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• 제6권1호
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• pp.21-29
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• 2015

Other countries(USA, Europe) have performed the fire resistance design of buildings by the alternative performance design methods, which are based on fire engineering theories. However, in Korea, the process on the alternative fire resistance performance design has only suggested without any applications for real steel structures. Therefore, In the case of steel structures stagnant research on refractory measures face difficulties in introducing fire resistance design. In this study, first of all, Intumescent paint was analyze the thermal properties(thermal conductivity, specific heat and density). In Sequence, using the section factor by H-standard section propose of section concrete filled steel tube and hollow. finally presents a reasonable thickness Intumescent paint takes time to target performance of the proposed cross-section steel tube.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2002년도 춘계학술대회 논문집 센서 박막재료 반도체재료 기술교육
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• pp.74-77
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• 2002

Ferroelectric Random Access Memory(FRAM) and MEMS applications require noble metal or refractory metal oxide electrodes. In this study, Ru thin films were etched using $O_2$+10% $CF_4$ plasma in an inductively coupled plasma(ICP) etching system. The etch rate of Ru thin films was examined as function of rf power, DC bias applied to the substrate. The enhanced etch rate can be obtained not only with increasing rf power and DC bias voltage, but also with small addition $CF_4$ gas. The selectivity of $SiO_2$ over Ru are 1.3. Radical densities of oxygen and fluorine in $CF_4/O_2$ plasma have been investigated by optical emission spectroscopy(OES). The etching profiles of Ru films with an photoresist pattern were measured by a field emission scanning electron microscope (FE-SEM). The additive gas increases the concentration of oxygen radicals, therefore increases the etch rate of the Ru thin films and enhances the etch slope. In $O_2$+10% $CF_4$ plasma, the etch rate of Ru thin films increases up to 10% $CF_4$ but decreases with increasing $CF_4$ mixing ratio.

• 대한후두음성언어의학회지
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• 제30권2호
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• pp.82-86
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• 2019

In the field of otolaryngology-head and neck surgery, botulinum toxins are widely used for the treatment of spasmodic dysphonia and vocal tremors. Recently, the applications of botulinum toxin have gradually expanded with time, to include vocal fold granuloma, mutational falsetto, bilateral vocal cord paralysis, and chemical reduction for arytenoid dislocation as an adjunctive modality. According to a nation-wide multicenter study conducted by the Korean Society of Laryngology, Phoniatrics and Logopedics for treatment modality of contact granuloma, among the various treatment modalities, botulinum toxin injection showed the highest response rate and lowest recurrence rate in both primary and refractory cases. Therefore, botulinum toxin could be reserved as a second-line treatment for contact granuloma in which the first treatment was not effective, but also could be used as a first-line treatment depending on the patient's and institution's situation. For recalcitrant nodules, injection of botulinum toxin into the bilateral thyroarytenoid muscle will reduce glottal contact force and result in a forceful chemical voice rest. In special situations, botulinum toxin injection could be one of the alternative treatment options for recalcitrant vocal nodules.

• Advances in materials Research
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• 제7권1호
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• pp.17-28
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• 2018

Niobium is a candidate base for new alloys devoted to applications at especially elevated temperatures. Elaborating and shaping niobium-based alloys by conventional foundry may lead to mechanically interesting microstructures. In this work a series of charges constituted of pure elements were subjected to high frequency induction melting in cold crucible to try obtaining cast highly refractory Nb-xCr and Nb-xCr-0.4 wt.%Calloys(x=27, 34 and 37 wt.%). Melting and solidification were successfully achieved. The as-cast microstructures of the obtained alloys were characterized by electron microscopy and X-ray diffraction and their hardness were specified by Vickers macro-indentation. The obtained as-cast microstructures are composed of a body centered cubic (bcc) niobium dendritic matrix and of an interdendritic eutectic compound involving the bcc Nb phase and a $NbCr_2$ Laves phase. The obtained alloys are hard to cut and particularly brittle at room temperature. Hardness is of a high level (higher than 600Hv) and is directly driven by the chromium content or the amount of {bcc Nb - $NbCr_2$} eutectic compound. Adding 0.4 wt.% of carbon did not lead to carbides but tends to increase hardness.

• Journal of Plant Biotechnology
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• 제42권1호
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• pp.6-12
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• 2015

Medicinal plants resources are becoming important assets since their usages have been expanded to the development of functional foods for human health, more attractive cosmetics, and pharmaceutical industries. However, their phylogenetic origins and names are different from each country and quite often they are mixed each other resulting in the confusion for consumers. In particular, when they are very similar based on their morphological characteristics and distributed as dried roots, it is extremely difficult to differentiate their origins even by specialists. Recently, "DNA barcodes" have been extensively applied to identify their origin of medicinal plant species. In this review, we tried to overview the current research achievements for the development of suitable "DNA barcodes" regarding to the differentiation of medicinal plant species. Furthermore, more advanced techniques including amplification refractory mutation system (ARMS)-PCR, multiplex single base extension (MSBE), high-resolution melting (HRM) curve analyses are also discussed for their practical applications in the authentification of particular medicinal plant species.

• 한국건축시공학회:학술대회논문집
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• 한국건축시공학회 2008년도 추계 학술논문 발표대회
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• pp.199-203
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• 2008

With recent trend in domestic and global market requiring architectures' conversion into skyscrapers seasoned with the features of landmarks, structural problems in relation with explosive spatting during fire emergencies are arising as controversial issues. Accordingly, many productive researches have been made in relation to the reinforcement techniques for improving fire resistance and the number of applications in the field is gradually increasing. In this study, a ductile outline form using ECC (Engineered Cementations Composites) was made with improvements on the structure and fire resistance to examine its applicability. Also, currently in Japan, the number of studies and applications is increasing focusing on reduction of construction time and improvement of workability with application of Half-PCa method. However, using such method of construction, large structural members decrease the utilization of space and architecture-wise, there is a disadvantage of the weight increase. Therefore, in such context, it would be worth reducing the weight of the structural members by reducing the size using ECC. In addition, its excellent pseudo strain-hardening due to fiber may have great effects on seismic designs. In the mean time, this study planned 3 equal conditions for mix water, PVA fiber and additives excluding binder and refractory to evaluate the mechanical properties of resistance against pressure and internal force. Finally, an evaluation was executed on the fire resistance of the newly made ductile outline form. As a result, from ECC-I to ECC-III, all showed excellent mechanical properties due to pseudo strain-hardening and in the fire resistance test conducted with ISO 834 heating curve, most of them tended to be in the range of the reference temperature (538℃-180min), so there was no occurrence of any explosive spatting.