우리나라 경제의 성장을 이끈 기계산업은 2015년 현재 생산액 100조원, 사업체수 9,526개사, 종사자수 31만 5천명, 부가가치 39조원으로써 제조업 중 생산액 5위, 사업체수 2위, 종사자수 3위, 부가가치 4위에 위치하고 있다. 이러한 기계산업에 있어 공작기계를 이용해 금속을 원하는 모양으로 만드는 금속가공은 반드시 필요한 공정으로 금속가공 시 가공 장비의 수명 연장 및 가공물의 품질 향상을 위해 칩이 형성되는 영역에 적용되어 윤활 및 냉각작용을 하는 절삭유(Soluble Cutting Fluids, SCF)가 이용되고 있다. 절삭유는 수용성 및 비수용성으로 나뉘는데 비수용성 절삭유의 경우 윤활성은 우수하나 경제성 및 발연, 발화등의 문제점이 있으며, 수용성 절삭유는 윤활성은 비교적 떨어지나 냉각성과 경제성이 우수하다는 장점이 있다. 또한 절삭유는 기능 향상을 위해 PAH, 방부제, 파라핀계 염소, 아질산염 등 20~30개의 첨가제가 사용된다. 이는 중추신경계 장애, 이비인후 자극, 피부염 발생 등을 일으킬 위험성이 크다고 알려져 있으며, 고농도의 유기성분 및 질소화합물로 인해 수계에 유출시 부영양화, 녹조현상 등과 같은 문제를 일으킬 수 있다. 따라서 본 연구에서는 전기화학적 처리를 통해 반응시간에 따른 폐수용성 절삭유의 COD 및 T-N의 제거율 변화를 분석하였다. 전기화학적 처리의 중요 인자인 전극은 비교적 가격이 저렴하고 용출량이 낮은 것으로 알려져 있는 SUS316전극을 이용하였으며 자세한 실험 조건을 Table 1에, 연구에 사용한 장치의 모식도를 Fig. 1에 나타내었다.

보일러 시스템에서의 부식 현상은 다양한 산업 분야에서 중대한 문제 중 하나로 인식되어왔다. 부식에 주된 원인으로는 높은 온도와 염소 가스와 같은 부식을 촉진시키는 특정한 가스인자들을 꼽을 수 있다. 많은 연구자들은 부식 현상을 억제하기 위한 재료 개발과 방법들에 대해 주목해서 연구해왔지만 각각의 내부식방법들을 비교 분석한 연구 사례는 흔치 않다. 이번 연구에서 우리는 보일러 시스템 고유의 온도 및 가스 조건을 구현할 수 있는 장치를 고안하여 각각의 내부식 방법들을 평가해보았다. 대부분의 보일러 시스템에서는 보일러 관의 외부(~800℃)와 내부(~500℃)가 내부의 스팀생성으로 인해 온도가 다르게 구현되는 독특한 특징이 있다. 우리가 새롭게 고안된 장치를 이용하면 내부식 방법들(ceramic coating, silica taping, plasma coating, high velocity oxygen fuel coating and overlay Inconel welding)에 대한 평가뿐만 아니라 부식을 유발시키는 염소 가스에 대한 영향도 구분해서 분석할 수 있다. 본 연구를 통해 보일러 튜브 표면에서 발생하는 고온 부식의 메커니즘에 대한 분석 및 고찰을 비롯해 각각의 내부식 방법들에 대한 보일러 튜브의 수명연장효과(잔여 수명 분석)을 FE-SEM, EDS, 무게감량법들을 통해 비교･평가할 수 있었다.

Background: In this study, we evaluated the anti-cancer activity and potential molecular mechanism of 70% ethanol extracts of the root of Aralia cordata var. continentalis (Kitagawa) Y. C. Chu (RAc-E70) against human colorectal cancer cells. Methods and Results: RAc-E70 suppressed the proliferation of the human colorectal cancer cell lines, HCT116 and SW480. Although RAc-E70 reduction cyclin D1 expression at the protein and mRNA levels, RAc-E70-induced reduction in cyclin D1 protein level occurred more dramatically than that of cyclin D1 mRNA. The RAc-E70-induced downregulation of cyclin D1 expression was attenuated in the presence of MG132. Additionally, RAc-E70 reduced HA-cyclin D1 levels in HCT116 cells transfected with HA-tagged wild type-cyclin D1 expression vector. RAc-E70-mediated cyclin D1 degradation was blocked in the presence of LiCl, a GSK3β inhibitorbut, but not PD98059, an ERK1/2 inhibitor and SB203580, a p38 inhibitor. Furthermore, RAc-E70 phosphorylated cyclin D1 at threonine-286 (T286), and LiCl-induced GSK3β inhibition reduced the RAc-E70-mediated phosphorylation of cyclin D1 at T286. Conclusions: Our results suggested that RAc-E70 may downregulate cyclin D1 expression as a potential anti-cancer target through GSK3β-dependent cyclin D1 degradation. Based on these findings, RAc-E70 maybe a potential candidate for the development of chemopreventive or therapeutic agents for human colorectal cancer.

In this study, we investigated the variation in free sugars, organic acids, antioxidant activity and anti-inflammatory effect of Solanum nigrum Linne fruits according to harvest time. Four kinds of free sugars (fructose, glucose, sucrose, maltose) were detected in S. nigrum fruit, and the free sugar contents varied significantly with harvest time. Organic acid content of S. nigrum fruit showed the highest in malic acid and acetic acid, and the highest content of total organic acids was found in S. nigrum fruit harvested on October 18th and October 25th. For the total polyphenol content, S. nigrum fruit harvested on October 18th was the highest. The strongest DPPH and ABTS radical scavenging activity was showed in S. nigrum fruit harvested on October 11th and October 18th. The anti-inflammatory activity and antioxidant effects were the highest in the ethanol extract from S. nigrum fruit collected on October 18th and October 11th. Thus, it seems the best to harvest of S. nigrum fruit harvested on October 11th and October 18th.

Soluble Cutting Fluids (SCFs) have been used in metal machining processes to improve the quality of metal processing equipment and products. Although SCFs are useful and essential material, wasted soluble cutting fluids are harmful in hydroecological systems because of the high concentration of COD and nitrogen material. If discharged to hydroecological systems without specific treatment, they may cause eutrophication in rivers and lakes. Therefore, the removal efficiency of the COD contained in the SCFs is investigated in this study using electrochemical treatment with an insoluble electrode. The electrode was made of titanium with iridium plating, made from a perforated metal sheet to agitate the sample in the reactor. Cathode and anode electrodes were inserted into acrylic reactor alternately and the reaction time was one hour. The experimental results were as follows: First, for 60 A/m2, 80 A/m2, and 100 A/m2 current densities, the COD removal efficiencies were 42.0%, 63.9%, and 78.4%, respectively.

Soluble cutting fluids (SCFs) have been used in metal machining processes to improve the quality of metal processing equipment and products in modern society. Because the characteristics among metal machining processes differ, various types of cutting fluids are manufactured to enhance the cutting efficiency of different metals. Although SCFs are useful and essential materials, particular treatment is required attributable to the high concentration of nitrogen materials and chemical oxygen demand (COD). In this study, the removal efficiency of total nitrogen (T-N) contained in SCFs was analyzed using electrochemical treatment. The electrode was made of 316 stainless steel, which had been perforated to prevent an imbalanced sample concentration in the reactor. Cathodic and anodic electrodes were alternately inserted into an acrylic reactor. The removal efficiency of T-N in SCFs using 40 A/m2, 60 A/m2, and 80 A/m2 current density, was 48.2%, 61.5% and 69.3%, respectively. The removal efficiency of T-N in SCFs with the addition of 0, 5 mM, and 10 mM NaCl was 69.3%, 74.6%, 77.6%, respectively.

With the goal of developing a new functional fermentation milk using green tea powder (GP), milk was fermented with direct vat set (DVS) starter culture containing Streptococcus salivarius subsp. thermophilus, Lactobacillus paracasei and L. delbrueckii subsp. bulgaricus. We investigated fermentation characteristics and antioxidative activities of fermented milk supplemented with different concentrations (0.5, 1, 2, 3%) of GP. All samples were evaluated for pH, total acidity, viable cell count, and sugar contents. The pH of all samples decreased during fermentation, and the final pH ranged from 4.35 to 4.51. The acidity increased during fermentation, after the fermentation was completed, the titratable acidity was 0.8 to 1.1%. And viable cell count of all samples increased during fermentation, and the final viable cell count was 8.57 to 8.89 log CFU/mL. The sugar content decreased as the fermentation proceeded and finally reached 12 to 13 ˚Brix. And increasing GP, decreased brightness and increased yellowness. Increasing GP concentration added to milk, improved DPPH free radical scavenging activity and ferric ion reducing activity of fermentation milk. The fermentation milk kept their pH, total acidity and viable cell counts standard of fermentation milk during the storage period at 4℃. These findings confirmed the possibility of development of the novel functional fermentation milk through the investigation of the quality characteristics of the fermentation milk added with GP.

In this study, we investigated the disease, insect damage, growth, and yield characteristics of sorghum and foxtail millet in an organic paddy-upland rotation system at Anseong-si Gyeonggi province, Korea, in 2016. Seven varieties of sorghum and foxtail millet are used in this study. A rotational upland field and continuously cropped upland field were compared in order to establish an optimum cultural method and to select the best sorghum and foxtail varieties for a paddy-upland rotation system. The incidence rate of major diseases was higher for sorghum than for foxtail millet. Moktaksusu (22.8%) had the highest incidence rate among sorghum varieties. Hwanggeumchal (7.0%) had the highest incidence rate among foxtail millet varieties. DS202 (89.3%) was the most severely damaged by Ostrinia furnacalis larva, which is the main pest of sorghum and maize. The weed numbers, and the weed fresh and dry weights were lower in the rotational upland field than in the continuously cropped upland field. Futhermore, the number of weed plants decreased by 42% and the dry weight of weeds decreased by 33% in the rotational upland field compared to the continuously cropped upland field. The culm length of sorghum and foxtail millet were 7.9 cm, and 3.4 cm longer, respectively, in the rotational upland field than in the continuously cropped upland field. The average yield of sorghum per 10 a increased by 90% in the rotational upland field compared to continuously cropped upland field. However, there was no significant difference between the rotational upland field and the continuously cropped upland field for foxtail millet. The most suitable varieties for a paddy-upland rotation system were judged to be Hwanggeumchal, Donganmae, and DS202 for sorghum, and Samdachal, Samdamae, Dahwangmae for foxtail millet.

국경을 초월한 국제이주 현상이 급격하게 증대함에 따라 각국의 이주민과 그 자녀의 수 또한 증가하고 있다. 이러한 이주민 수의 증가에 맞춰 이주민의 사회통합을 위한 담론과 정책적 노력이 세계적으로 확산되고 있다. 그러나 이주배경 학생 가운데 상당수는 사회로 부터의 차별 및 소외를 경험하며 정착 국가에 낮은 수준의 자긍심과 애착을 보이고, 적응 의 어려움을 겪는 것으로 보고되고 있다. 국가에 대한 자긍심이 개인적⋅사회적 차원에서 사회통합의 주요한 기제임을 고려하였을 때 미래사회의 시민으로서 성장할 이주배경 학생 의 정착 국가에 대한 낮은 자긍심은 사회통합의 걸림돌로 작용할 수 있다. 이주민 반차별 정책은 이와 같은 문제에 선제적으로 대응하기 위한 일련의 정책적⋅제도적 노력이다. 본 비교정책연구는 이주민 반차별정책의 제도화 수준이 사회통합의 한 지표인 이주배경 학생 의 국가 자긍심에 미치는 영향을 실질적으로 탐구하였다. ICCS 2009, MIPEX Ⅲ 두 자료를 활용하여 24개국의 8학년 학생 7만 3천여 명 자료를 분석한 결과, 이주민 반차별정책을 높 은 수준에서 제도화하고 있을 때 학생의 이주배경 지위가 갖는 국가 자긍심에 대한 부적 효과가 유의미하게 낮아지는 것으로 나타났다. 이러한 결과는 이주민 사회통합을 위한 정 책적 노력이 이주배경 학생의 국가 자긍심을 높여 실제적으로 사회통합에 긍정적인 역할을 수행할 수 있음을 시사한다.

The study investigated the fluidity and compressive strength properties of cement paste containing Ferro-Nickel slag powder by different curing conditions to estimate the applicability of Ferro-Nickel slag powder for cement replacement materials.

Recently, steel has been very frequently chosen in building many civil infra-structures including bridges due to its several beneficial advantages as compared to concrete structures. However, for the most cases, damage such as section reduction, that is resulted from corrosion, was natural and inevitable. Therefore, it becomes very important to evaluate the structural safety and to estimate the life for the worst cases. In this study, the corrosion behaviors of mock-up specimen with box girder were examined by visual inspection.

All bridges are inevitably undergoing deterioration over time. Therefore, it is necessary to predict the maintenance control and to properly manage the maintenance control cost by deriving the appropriate repair and reinforcement timing. The deterioration of bridges appears to vary according to the years of use of bridges and the exposed environment. In this study, the correlation between the deterioration factor of the winter season and the damage rate of the bridge deck was derived from 1117 total bridge data collected through the GPR(Ground Penetration Radar) system.

To investigate skin-whitening effect of Adenophora triphylla var. japonica sprout extract, antioxidant activity, inhibitory effect on tyrosinase and melanin synthesis in B16/F10 melanoma cell were examined. Total phenolic content (246.25 ㎎ GAE/g) and total flavonoid content (303.94 ㎎ RE/g) of ethyl acetate fraction from Adenophora triphylla sprout (EFAT) showed the highest contents than other fractions (n-hexane, chloroform and distilled water). Antioxidant activities of EFAT has been evaluated using ABTS, DPPH radical scavenging activities, FRAP and inhibitory effect of lipid peroxidation. EFAT showed excellent radical scavenging activity and inhibitory effect on MDA production. Inhibitory effect of tyrosinase as a major enzyme of melanin synthesis was also measured. In these results, EFAT showed higher inhibitory effect against L-DOPA (51.27%) than L-tyrosine. IC50 value on α-glucosidase was 41.93 ㎍/㎖. In B16/F10 melanoma cells, EFAT inhibited melanin synthesis at 200 ㎍/㎖ concentration (about 42% decrease). Finally, main physiological compounds of EFAT were identified as a rutin and a chlorogenic acid using high performance liquid chromatography.

Background: The present study was carried out to asses whether mulberry leaves (MLs) have the potential to inhibit the mutagenic effect of cigarette smoke condensates (CSCs). Methods and Results: ML powder was extracted with 70% ethanol, and a yield of 35.1% by weight was obtained. The 70% ethanol extract of ML was further extracted sequentially using diethyl ether, chloroform, butanol, dichloromethane and water. The crude 70% ethanol extract of MLs and its solvent fractions did not show any mutagenic effect when tested at concentrations up to 1 ㎎/ plate against Salmonella typhimurium TA98. In contrast, the crude 70% ethanol extract showed an inhibitory activity against the mutagenicity of CSCs in the presence of S-9 mixture. Among the solvent fractions, the diethyl ether fraction showed the highest inhibitory activity, which increased in a dose-dependent manner, inhibiting mutagenesis by approximately 97.1% at a concentration of 1㎎/plate. Conclusions: In this study, we found that a crude 70% ethanol extract of MLs and the diethyl ether fraction themselves are potentially not mutagenic, but inhibit the mutagenic effect of CSCs.