• Nuclear Engineering and Technology
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• 제29권2호
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• pp.93-98
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• 1997

Air-oxidation experiments on unirradiated and irradiated UO$_2$ were performed at temperature from 150 to 375$^{\circ}C$ for investigating the long-term storage behavior of spent PWR fuel. The rate of oxidation was monitored by a thermogravimetric analyzer(TGA) and an X-ray diffraction(XRD). The correlation between the onset-time for U$_3$O$_{8}$ formation and temperature was given as follows, logt(hr) = -12.89+7650/T(K), 423$_2$ pellet, the oxidation rate of irradiated UO$_2$ increase more rapidly at the initial stage and shows a lower saturation point at the later Stage. The Oxidation rate of high bumup UO$_2$ and gadolinia-doped UO$_2$(Gd$_2$O$_3$-UO$_2$) were observed to be much slower than that of unirradiated UO$_2$ pellets.s.

• 한국생활과학회지
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• 제22권2호
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• pp.375-389
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• 2013

This survey was conducted to compare the housewife's food habit and food purchase behavior on healthy dietary life. The questionnaires were collected from 151 working housewives and 159 housewives in Daejeon. The average meal time was 20~30 min., 67.6% of respondents ate breakfast and bap with guk(72.9%) was the most favourite foods. Almost half of them ate egg, fruit, vegetable everyday. They concerned highly about less intake of frozen foods(64.2%) and food additives(61.6%) for wellbeing dietary life. Because of close distance and various foods items, big discount store was chosen as food purchase place. The most considering purchase factor was food additives in working housewife and nutrition in housewife(p<0.05). In grocery shopping, working housewife considered children and their husbands(p<0.05). The most important purchase factor was the freshness in vegetables fishes fruits seaweeds eggs. TV or Radio was utilized the most frequently to obtain the useful knowledge on healthy foods. It is suggested that practical information should be offered housewives to purchase proper foods within their income and to manage dietary life according to their family's health condition.

• 한국재료학회지
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• 제31권7호
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• pp.375-381
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• 2021

Chitosan powder is synthesized by a deasetylation process of chitin, obtained from processing of dried shrimp shell powder. Subsequently, chitosan (CS) membranes filled by montmorillonite (MMT) particles and phosphotungstic acid are prepared, and characterized by FT-IR and SEM. The morphology, obtained by SEM for the composite membrane, showed that MMT filler is successfully incorporated and relatively well dispersed in the chitosan polymer matrix. Water and methanol uptake for the CS/MMT composite membranes decrease with increasing MMT loadings, but IEC value increases. In all prepared CS/MMT composite membranes, the CS membrane filled by 5 wt% MMT particles exhibits the best proton conductivity, while that with 10 wt% MMT loading exhibits the lowest methanol permeability; these values are 2.67 mS·cm^-1 and 3.40 × 10^-7 cm²·s^-1, respectively. The best membrane selectivity is shown in the CS/MMT10 composite membrane; this shows that 10 wt% filled MMT is the optimum loading to improve the performance of the chitosan composite membrane. These characteristics make the developed chitosan composite membranes a promising electrolyte for direct methanol fuel cell (DMFC) application.

• Coupled systems mechanics
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• 제2권4호
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• pp.375-387
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• 2013

Soils consist of an assemblage of particles with different sizes and shapes which form a skeleton whose voids are filled with water and air. Hence, soil behaviour must be analyzed by incorporating the effects of the transient flow of the pore-fluid through the voids, and therefore requires a two-phase continuum formulation for saturated porous media. The present paper presents briefly the Biot's basic theory of dynamics of saturated porous media with u-P formulation to determine the responses of pore fluid and soil skeleton during cyclic loading. Kelvin elements are attached to transmitting boundary. The Pastor-Zienkiewicz-Chan model has been used to describe the inelastic behavior of soils under isotropic cyclic loadings. Newmark-Beta method is employed to discretize the time domain. The response of fluid-saturated porous media which are subjected to time dependent loads has been simulated numerically to predict the liquefaction potential of a semi-infinite saturated sandy layer using finite-infinite elements. A settlement of 17.1 cm is observed at top surface. It is also noticed that liquefaction occurs at shallow depth. The mathematical advantage of the coupled finite element analysis is that the excess pore pressure and displacement can be evaluated simultaneously without using any empirical relationship.

• Kyungpook Mathematical Journal
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• 제58권2호
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• pp.361-375
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• 2018

The object of the present paper is to study super quasi-Einstein manifolds. Some geometric properties of super quasi-Einstein manifolds have been studied. We also discuss $S(QE)_4$ spacetime with space-matter tensor and some properties related to it. Finally, we construct an example of a super quasi-Einstein spacetime.

• 한국추진공학회:학술대회논문집
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• 한국추진공학회 2009년도 춘계학술대회 논문집
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• pp.263-266
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• 2009

본 연구는 GE 7FA+e DLN 2.6 가스터빈 연소기를 축소 제작한 모형 가스터빈 연소기의 연소 동특성 및 연소불안정 현상을 알아보고 위해 진행되었다. 모형 연소기에 사용된 연료노즐은 1/3 크기로 상사하여 제작되었으며, 실제 연료노즐과 동일한 2단 스월러(swirl vane)를 가지고 있다. Plenum과 연소기의 형상은 실 가스터빈과 유사한 음향학적 특성을 가질수 있도록 설계되었다. 실험은 공기온도 $200{\sim}400^{\circ}C$, 대기압, 노즐출구 속도 $30{\sim}75\;m/s$, 당량비 $0.4{\sim}1.2$, 연소실 길이 $375{\sim}700\;mm$,에서 이루어졌으며, 그 결과 소염영역 근처의 저 당량비 영역과 당량비 1.1 이상인 연료 과농 상태에서 연소 불안정 현상이 관찰 되었다.

• Natural Product Sciences
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• 제25권1호
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• pp.11-15
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• 2019

Lauraceae is a family medicinal plant whose tubers possesses antimicrobial, and cytotoxic, such as antiparasitic and anti-inflammatory special effects and has been used for the medicine in the cure of hepatitis and rheumatism. The antimicrobial activities of bioactive compounds including one neolignan; kunstlerone (1) and two alkaloids include isocaryachine (2) and noratherosperminine (3) as well as crude hexane, methanol and dichloromethane extracts were evaluated. Additionally, the effect of compounds 1, 2 and 3 were evaluated on A549, PC-3, A375, HT-29 and WRL-68 cell lines. In conclusion, kunstlerone 1 showed moderate cytotoxicity against various cancer cell lines such as A549, PC-3, A375, HT-29 and WRL-68, respectively with $EC_{50}$ values of 28.02, 26.78, 33.78, 33.65 and $16.46{\mu}g/mL$. The crude methanol extract showed antigrowth activity against S. pyogenes II and B. cereus, with MICs of $256{\mu}g/mL$. The compounds kunstlerone (1), isocaryachine (2) and noratherosperminine (3) showed complete inhibition against P. shigelloides, with MIC ${\leq}60{\mu}g/mL$ compare to ampicillin, as a positive control, which showed antigrowth activity against P. shigelloides at MIC $10{\mu}g/mL$.

• Nutrition Research and Practice
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• 제5권5호
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• pp.375-380
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• 2011

This study investigated the effects of inorganic sulfur on metastasis in MDA-MB-231 human breast cancer cells. MDA-MB-231 cells were cultured in the absence or presence of various concentrations (12.5, 25, or 50 ${\mu}mol$/L) of inorganic sulfur. Cell motility, invasion, and the activity and mRNA expression of matrix metalloproteases (MMPs) were examined. Numbers of viable MDA-MB-231 cells did not differ by inorganic sulfur treatment from 0 to 50 ${\mu}mol$/L within 48 h. Inorganic sulfur significantly decreased cell motility and invasion in the MDA-MB-231 cells in a dose-dependent manner (P<0.05), as determined using a Boyden chamber assay and a Matrigel chamber. The activities of MMP-2 and MMP-9 were significantly reduced by inorganic sulfur in a dose-dependent manner (P<0.05). The inorganic sulfur also significantly inhibited MMP-2 and MMP-9 expression in the cells (P<0.05). These data suggest that inorganic sulfur can suppress cancer cell motility and invasion by inhibiting MMP-2 and MMP-9 activity and gene expression in MDA-MB-231 cells.

• Structural Engineering and Mechanics
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• 제87권4호
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• pp.375-389
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• 2023

In many fiber concrete beams with Carbon Fiber Reinforced Polymer (CFRP), debonding occurs between the carbon sheets and the concrete due to the low strength of the bonding resin. A total of 42 fiber concrete beams with a cross-section of 10×10 cm with a span length of 50 cm are fabricated and retrofitted with CFRP and subjected to a 4-point bending test. Graphene Oxide (GO) at 1, 2, and 3 wt% of the resin is used to improve the mechanical properties of the bonding resins, and the effect of length, width, and the number of layers of CFRP and resin material are investigated. The crack pattern, failure mode, and stress-strain curve are analyzed and compared in each case. The results showed that adding GO to polyamine resin could improve the bonding between the resin and the fiber concrete beam. Furthermore, the optimum amount of nanomaterials is equal to 2% by the weight of the resin. Using 2% nanomaterials showed that by increasing the length, width, and number of layers, the bearing and stiffness of fiber concrete beams increased significantly.

• 디지털융복합연구
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• 제19권6호
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• pp.199-211
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• 2021

본 연구는 스마트팩토리를 도입한 국내 중소제조기업이 질적 고도화를 위해 현재 대비 상위단계의 스마트팩토리 고도화 수용의도에 영향을 미치는 요인을 분석하고자 한다. 이를 위하여 스마트팩토리를 도입한 중소기업을 대상으로 통합기술수용이론과 확장된 2단계 정보시스템 지속사용모델을 이용하여 온라인 설문조사를 통해 수집된 375부를 SPSS와 AMOS를 활용하여 실증적으로 분석하였다. 연구결과 성과기대, 노력기대, 사회적 영향, 촉진조건은 사용자 만족도에 통계적으로 유의한 영향이 있었으며, 사용자 만족도와 경영자의 의지는 고도화 수용의도에 영향을 미치는 것으로 나타났다. 다만 공급사의 기술력은 고도화 수용의도에 직접적인 영향이 없는 것으로 나타났으며 스마트팩토리 사용자의 만족도는 성과기대, 노력기대, 사회적 영향, 촉진조건과 고도화 수용의도 간에 매개효과를 가지는 것을 확인하였다. 향후 국내 중소제조기업의 스마트팩토리 고도화를 위해서는 사용단계에서의 만족도 향상과 경영자의 스마트화 의지를 지속 향상시키는 노력이 중요하다고 판단된다.