• Advances in concrete construction
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• 제10권2호
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• pp.127-140
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• 2020

This study explores the feasibility of granite waste aggregate (GWA) as a partial replacement of natural fine aggregate (NFA) in binary blend self-compacting concrete (SCC) prepared with fly ash. Total of nine SCC mixtures were prepared wherein one was Ordinary Portland cement (OPC) based control SCC mixture and remaining were fly ash based binary blend SCC mixtures which included the various percentages of GWA. Fresh properties tests such as slump flow, T₅₀₀, V-funnel, J-ring, L-box, U-box, segregation resistance, bleeding, fresh density, and loss of slump flow (with time) were conducted. Compressive strength and percentage of permeable voids were evaluated in the hardened state. All the SCC mixtures exhibited sufficient flowability, passing ability, and resistance to segregation. Besides, all the binary blend SCC mixtures exhibited lower fresh density and bleeding, and better residual slump (up to 50% of GWA) compared to the OPC based control SCC mixture. Binary blend SCC mixture incorporating up to 40% GWA provided higher compressive strength than binary blend control SCC mixture. The findings of this study encourage the utilization of GWA in the development of binary blend SCC mixtures with satisfactory workability characteristics as a replacement of NFA.

• 한국치위생학회지
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• 제15권2호
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• pp.319-324
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• 2015

Objectives: The purpose of this study was to verify the oral environmental change in using the natural oral cleaner containing propolis and prevention effect of oral disease. Methods: The subjects were 60 university students in Gangwon province. The groups consisted of 30 students of experimental group and 30 students of control group. The subjects were those who did not take the antipsychotic, diuretic, antihistamine, and anesthetic. The students rinsed their mouth with propolis mixture of oral cleanser for 4 weeks after receiving informed consent from October 1 to November 2, 2012. Collected saliva was measured for amount, salivary consistency, pH, plague index, gingival index, and halitosis. Results: The amount of salivary in propolis mixture of oral cleansing group remarkably increased (t=2.16, p<0.05). pH was alkaline in the group with oral cleaner containing the propolis (t=2.80, p<0.01). The bad breath remarkably decreased in the group with oral cleaner containing the propolis (t=-5.77, p<0.001). Conclusions: The use of the oral cleaner containing the propolis increased the amount of salivary and pH. The use of oral cleaner containing the propolis reduces halitosis and maintains good quality of oral hygiene.

• 대한화학회지
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• 제33권3호
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• pp.326-331
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• 1989

Sol-gel법으로 고온 초전도체인 $YBa_2Cu_3O_{7-{\sigma}}$의 세선을 제작하였다. Y, Ba, Cu 질산염을 1:2:3의 몰비로 수용액을 제조한 후 구연산 수용액을 첨가하고, 암모니아 수용액을 첨가하여 pH를 $5.8{\sim}6.2$로 조절함으로써 균일한 colloid sol을 제조할 수 있었다. 이를 358K 로 가열하면 점차 점도가 증가하면서 gel화 반응이 진행되고 이 gel화 반응이 완결되기 전에 구연산염 precursor gel fiber를 임의의 길이 및 두께로 뽑을 수 있었다. 이 precursor를 1223K, $Po_2$=1atm. 하에서 8시간 열처리한 후 723K로 서냉하고 13시간 동안 annealing 하여 약 95K에서 전기저항이 급격히 감소($T_c$, onset), 약 82K에서는 저항 0($T_c$, offset)을 나타내었고 액체질소 비등점에서 Meissner-effect를 보임으로써 초전도체 임을 확인하였다.

• Bulletin of the Korean Chemical Society
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• 제9권1호
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• pp.1-4
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• 1988

Rates of solvolysis of trans-[Co$(N-eten)_2Cl_2$]$^+$ have been investigated using spectrophotometric method at various pressures and temperatures in the mixtures of water with the t-butyl alcohol which possesses a high structure inducing capacity in water. The values of ${\Delta}V^{\neq}$ obtained from pressure effect on the rate constants were 2.55∼ 5.83 $cm^3mol^{-1}$. These values were discussed in terms of dissociative mechanism. Extrema found in the variation of ${\Delta}H^{\neq}$ and ${\Delta}S^{\neq}$ with solvent composition correlated with extrema in the variation of the physical properties of the mixtures. The logarithms of rate constants correlated linearly with both Grunwald-Winstein parameter and the reciprocal of dielectric constant ($Ds^{-1}$). The gradient, m of Grunwald-Winstein plot for the trans-[Co$(N-eten)_2Cl_2$]$^+$ was 0.09, which is significantly lower than those for the other cobalt (Ⅲ)-dichloro complexes. It was suggested that the reaction is an Id mechanism with long extension of Co-Cl bond in the transition state, as found for the C-Cl bond in the transition state for the solvolysis of t-butyl chloride.

• 한국수소및신에너지학회논문집
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• 제23권4호
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• pp.382-389
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• 2012

Power generation cycle using ammonia-water mixture as working fluid has attracted much attention because of its ability to efficiently convert low-temperature heat source into useful work. If an ammonia-water power cycle is combined with a power cycle using liquefied natural gas (LNG), the conversion efficiency could be further improved owing to the cold energy of LNG at $-162^{\circ}C$. In this work parametric study is carried out on the thermodynamic performance of a power cycle consisted of an ammonia-water Rankine cycle as an upper cycle and a LNG cycle as a bottom cycle. As a driving energy the combined cycle utilizes a low-temperature heat source in the form of sensible heat. The effects on the system performance of the system parameters such as ammonia concentration ($x_b$), turbine 1 inlet pressure ($P_{H_1}$) and temperature ($T_{H_1}$), and condenser outlet temperature ($T_{L_1}$) are extensively investigated. Calculation results show that thermal efficiency increases with the increase of $P_{H_1}$, $T_{H_1}$ and the decrease of $T_{L_1}$, while its dependence on $x_b$ has a downward convex shape. The changes of net work generation with respect to $P_{H_1}$, $T_{H_1}$, $T_{L_1}$, and $x_b$ are roughly linear.

• 생명과학회지
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• 제24권12호
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• pp.1301-1307
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• 2014

지방유래줄기세포(adipose-derived stem cell; ADSC)는 조직재생을 위한 탁월한 수단으로 인정되고 있으나 세포증식속도가 느려 ADSC의 배양용 배지에는 대게 fetal bovine serum (FBS)이 첨가된다. FBS는 세포에 다양한 영양분을 공급하지만 세포의 기능에 영향을 미칠 수 있는 미 동정 물질도 많이 함유하고 있다. FBS에 의한 예상밖의 영향과 동물유래물질의 오염을 방지하기 위해 ADSC의 무혈청 배양법에 관한 연구가 광범위하게 이루어지고 있다. 본 연구에서는 ADSC세포에 SV40의 T항원 유전자를 도입하여 증식속도를 향상시킨 ADSC-T세포주의 효율적인 무혈청 배양법을 확립하기 위해 ADSC-T의 세포증식에 미치는 아미노산복합체, 비타민 복합체 및 여러가지 영양분 혼합물(B27)의 영향을 검토하였다. 그 결과, ADSC-T세포를 DMEM/F12 무혈청 배지에 현탁하여 plate에 주입하였을 때는 증식하지 않았으며 아미노산, 비타민 및 B27 영양소복합체는 증식촉진효과를 나타내지 않았다. 그러나 ADSC-T세포를 유혈청 DMEM배지로 24시간 배양 후 DMEM/F12 무혈청 배지로 교체하여 배양했을 때는 세포가 증식하였으며 이때, 비타민 복합체와 B27 영양소복합체는 증식촉진효과를 나타내었다. 또한 Stem pro 배지를 이용하면 ADSC-T의 무혈청 부유배양이 가능한 것으로 나타났다. ADSC-T세포는 분자량 70 kDa 부근의 단백질을 다량으로 분비하였으며, 성장인자 중에서 insulin-like growth factor (IGF)와 fibroblast growth factor basic (FGF basic)는 유혈청 배양보다 무혈청 배양에서 더 많이 분비되었다.

• 대한화장품학회지
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• 제48권4호
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• pp.331-342
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• 2022

비만은 에너지의 섭취와 소비의 불균형으로 인해 지방조직이 과도하게 분화하여 과잉 축적이 되면서 발생하게 되는 대사질환 중 하나이다. 본 연구에서 저자들은 3T3-L1 지방세포를 이용해 천연 유래 6 종 혼합물인 SliMax의 항비만 효과를 확인하였다. 그 결과 SliMax는 지방분화 단계에서 후기 분화를 조절하는 것으로 알려진 PPARγ와 C/EBPα의 발현 억제를 통해 지방분화를 억제하는 결과를 보였다. 또한 지방세포 분화 유도 후 지방세포 분해 과정에서 SliMax는 지방분해 관련 단백질인 ATGL과 HSL 발현 증가를 통해 큰 사이즈의 단방성 지방구를 작은 사이즈의 수많은 다방성 지방구로 분해하였다. 마지막으로 갈색지방으로 유도하는 효능을 확인하기 위해 UCP-1의 발현과 미토콘드리아 양을 면역형광염색법으로 확인한 결과 SliMax가 지방세포의 UCP-1의 발현과 미토콘드리아 양을 증가시켰다. 결과를 종합해볼 때, 천연 유래 혼합물인 SliMax는 지방 분화억제와 지방분해 촉진을 통해 지방구의 형성을 억제하고, 열 생산과 에너지 소비와 관련된 갈색지방화 촉진 기능을 가져 항비만 소재로의 가능성을 가진다.

• 대한화장품학회지
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• 제40권1호
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• pp.45-54
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• 2014

각질형성세포주인 HaCaT세포에서 Lipopolysaccharide (LPS)로 유도하는 염증반응에는 tumor neurosis factor-${\alpha}$ (TNF-${\alpha}$), interleukin-1${\alpha}$ (IL-1${\alpha}$), interleukin-6 (IL-6), 및 interleukin-8 (IL-8)와 같은 염증 유발 사이토카인(pro-inflammatory cytokines)이 증가되고, 또한 염증반응을 매개하는 inducible nitric oxide synthase (iNOS), cyclooxygenase-2 (COX-2) 및 prostaglandins E2 (PGE2)도 증가된다. 본 연구에서는 이렇게 유도된 염증 반응에서 효과적으로 염증 관련인자를 조절할 수 있는 천연물을 발굴하고자 하였다. 그 결과, 마가목, 쐐기풀, 죽여 및 오배자 혼합 추출물이 IL-1${\alpha}$, TNF-${\alpha}$, IL-6 및 IL-8의 발현을 억제하고 COX-2, iNOS 및 PGE2의 발현도 억제함을 확인하였다. 아울러 IQ chamber$^{(R)}$을 이용하여 피부에 첩포할 때 sodium lauryl sulfate (SLS)로 유발한 피부자극에서 이들 혼합물이 효과적으로 그 자극을 억제함을 확인하였다. 따라서 본 연구 결과로부터 마가목, 쐐기풀, 죽여 및 오배자의 혼합물이 피부자극완화용 화장품 소재로서 민감성 피부 등을 위한 제품에 유용하게 사용될 수 있음을 확인하였다.

• 대한본초학회지
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• 제32권6호
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• pp.55-62
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• 2017

Objectives : This study aims to evaluate the effects of natural herb mixutre (NHM) on atopic dermatitis and skin regeneration using in vivo test. Methods : NHM was prepared with DW. 25% of NHM was applied to skin lesion, where atopic dermatitis was induced by DNCB in NC/Nga mice. The levels of cytokines (IL-4, IL-5, IL-6, IL-13, TNF-a, and $IFN-{\gamma}$), and IgE in serum were measured by Luminex. Immune cells (WBC, eosinophil, lymphocyte, and monocyte) in blood were counted by coulter counter. The gross investigation of atopic dermatitis index score test were performed during the NHM treatment period. Also, the histopathological change of dorsal skin was observed by H&E and M&T staining. Results : NHM showed the levels of IL-4, IL-5, IL-6, IL-13, IgE, WBC, eosinophil, lymphocyte, and monocyte in serum or blood were significantly decreased. On the contrary, the productions of FGF, and VEGF were increased in the serum. Also, atopic dermatitis index score in NHM-treated mice were observed in the similar levels to those of normal group. Histological examination demonstrated that NHM suppressed immune cell infiltration and thickening of epidermis, meanwhile the extraction induced collagen production in the dorsal skin. Conclusion : This study demonstrated that NHM is appeared to be effective on atopic dermatitis and skin regeneration efficacy based on the observations with hematologic, gross, and histologic examinations. Therefore, we suggest that NHM could be effectively used as an external therapeutics against atopic dermatitis and a consequence skin damage.

• Elastomers and Composites
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• 제39권4호
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• pp.263-273
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• 2004

The effects of zinc surfactant (ZB) on the bis(triethoxysilylpropyl)disulfide (TESPD)-silica mixture in natural rubber (NR) and solution butadiene-co-styrene rubber(S-SBR) were compared with respect to their rheological property, processability, physical properties, and silica dispersion. In the NR compound, addition of the ZB increased the reversion resistance time (T-2), the tensile modulus, and the BO time; however, lowered the viscosity, the HBU, and tans values. In the S-SBR copound, addition of the ZB increased the $tan{\delta}$ values while lowered the T-2, the tensile modulus the BO time, the viscosity, and the HBU of the compound. In the NR compounds, addition of the ZB significantly increased the processability and mechanical property. However, in the S-SBR compounds, it improved the processability the mechanical property was not improved.