• Tribology and Lubricants
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• 제39권5호
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• pp.183-189
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• 2023

A bearing is a mechanical component that transmits rotation and supports loads. According to the type of rotating mechanism, bearings are categorized into ball bearings and tapered roller bearings. Tapered roller bearings have higher load-bearing capabilities than ball bearings. They are used in applications where high loads need to be supported, such as wheel bearings for commercial vehicles and trucks, aircraft and high-speed trains, and heavy-duty spindles for heavy machinery. In recent times, the demand for reducing the driving friction torque in automobiles has been increasing owing to the CO₂ emission regulations and fuel efficiency requirements. Accordingly, the research on the driving friction torque of bearings has become more essential. Researchers have conducted various studies on the lubrication, friction, and contact in tapered roller bearings. Although researchers have conducted numerous studies on the friction in the lips and on roller misalignment and skew, studies considering the influence of roller shape, specifically roller shape errors including lips, are few. This study investigates the driving friction torque of tapered roller bearings considering roller geometric uncertainties. Initially, the study calculates the driving friction torque of tapered roller bearings when subjected to axial loads and compares it with experimental results. Additionally, it performs Monte Carlo simulations to evaluate the influence of roller geometric uncertainties (i.e., the effects of roller geometric deviations) on the driving friction torque of the bearings. It then analyzes the results of these simulations.

• Journal of Microbiology and Biotechnology
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• 제33권12호
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• pp.1648-1656
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• 2023

We have previously observed that feeding with single-cell hemoprotein (heme-SCP) in dogs (1 g/day for 6 days) and broiler chickens (1 ppm for 32 days) increased the proportion of lactic acid bacteria in the gut while reducing their body weights by approximately 1~2%. To define the roles of heme-SCP in modulating body weight and gut microbiota, obese C57BL/6N mice were administered varied heme-SCP concentrations (0, 0.05, and 0.5% heme-SCP in high fat diet) for 28 days. The heme-SCP diet seemed to restrain weight gain till day 14, but the mice gained weight again later, showing no significant differences in weight. However, the heme-SCP-fed mice had stiffer and oilier bodies compared with those of the control mice, which had flabby bodies and dull coats. When mice were dissected at day 10, the obese mice fed with heme-SCP exhibited a reduction in subcutaneous fat with an increase in muscle mass. The effect of heme-SCP on the obesity-associated dyslipidemia tended to be corroborated by the blood parameters (triglyceride, total cholesterol, and C-reactive protein) at day 10, though the correlation was not clear at day 28. Notably, the heme-SCP diet altered gut microbiota, leading to the proliferation of known anti-obesity biomarkers such as Akkermansia, Alistipes, Oscillibacter, Ruminococcus, Roseburia, and Faecalibacterium. This study suggests the potential of heme-SCP as an anti-obesity supplement, which modulates serum biochemistry and gut microbiota in high-fat diet-induced obese mice.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2012년도 제42회 동계 정기 학술대회 초록집
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• pp.434-435
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• 2012

Plasma enhanced chemical vapor deposition (PECVD) silicon dioxide thin films have many applications in semiconductor manufacturing such as inter-level dielectric and gate dielectric metal oxide semiconductor field effect transistors (MOSFETs). Fundamental chemical reaction for the formation of SiO2 includes SiH4 and O2, but mixture of SiH4 and N2O is preferable because of lower hydrogen concentration in the deposited film [1]. It is also known that binding energy of N-N is higher than that of N-O, so the particle generation by molecular reaction can be reduced by reducing reactive nitrogen during the deposition process. However, nitrous oxide (N2O) gives rise to nitric oxide (NO) on reaction with oxygen atoms, which in turn reacts with ozone. NO became a greenhouse gas which is naturally occurred regulating of stratospheric ozone. In fact, it takes global warming effect about 300 times higher than carbon dioxide (CO2). Industries regard that N2O is inevitable for their device fabrication; however, it is worthwhile to develop a marginable nitrous oxide free process for university lab classes considering educational and environmental purpose. In this paper, we developed environmental friendly and material cost efficient SiO2 deposition process by substituting N2O with O2 targeting university hands-on laboratory course. Experiment was performed by two level statistical design of experiment (DOE) with three process parameters including RF power, susceptor temperature, and oxygen gas flow. Responses of interests to optimize the process were deposition rate, film uniformity, surface roughness, and electrical dielectric property. We observed some power like particle formation on wafer in some experiment, and we postulate that the thermal and electrical energy to dissociate gas molecule was relatively lower than other runs. However, we were able to find a marginable process region with less than 3% uniformity requirement in our process optimization goal. Surface roughness measured by atomic force microscopy (AFM) presented some evidence of the agglomeration of silane related particles, and the result was still satisfactory for the purpose of this research. This newly developed SiO2 deposition process is currently under verification with repeated experimental run on 4 inches wafer, and it will be adopted to Semiconductor Material and Process course offered in the Department of Electronic Engineering at Myongji University from spring semester in 2012.

• 생명과학회지
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• 제20권5호
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• pp.750-759
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• 2010

지리산 청정지역에서 재배되고 있는 참당귀의 생리활성 물질과 효능을 이용한 건강 기능성 식품 또는 화장품 소재 개발을 위한 기초연구의 일환으로 참당귀의 잎, 줄기 혼합물 및 뿌리의 추출방법에 따른 phenolic compounds, flavonoids, minerals, decursin 및 decursinol angelate 등의 생리활성 물질 분석과 항산화 활성 및 환원력을 측정하였다. 당귀 뿌리의 온수 추출물 수율은 21.89%로 가장 높았다. 페놀성 화합물 및 플라보노이드 함량은 참당귀 잎, 줄기 혼합물의 에탄올 추출물에서 가장 높은 함량을 보였고, 참당귀 뿌리 보다는 잎, 줄기 혼합물에서 높았고, 수용성 추출물보다 에탄올 추출물에서 높았다. 미네랄함량은 참당귀 잎, 줄기 혼합물 및 뿌리 모두에서 K, Mg, Fe, Na, Ca, Mn, Zn 순으로 함유되어 있었다. HPLC 분석에 의한 참당귀 잎, 줄기, 뿌리의 decursin 및 decursinol angelate의 혼합 면적 비율은 각각 66.1%, 82.2%, 79.8%로 나타났으며, decursin은 13.0%, 37.6%, 47.1%로 뿌리에서 가장 높았고 decursinol angelate는 53.2%, 44.6%, 32.6%로서 잎에서 가장 높았다. Free radical scavenging 항산화활성은 참당귀 잎, 줄기 혼합물 및 뿌리 각각의 열수 추출물에서 가장 높았으며, 뿌리보다는 잎, 줄기 혼합물의 모든 추출물에서 항산화 활성이 높았다. Fe 및 Cu 환원력은 참당귀 잎, 줄기 혼합물 및 뿌리의 온수, 열수 및 에탄올 추출물 순으로 높게 나타났으며, 참당귀 잎, 줄기 혼합물의 추출물이 뿌리 추출물 보다 높은 활성을 보였는데 이는 페놀성 화합물이나 플라보노이드 함량과 밀접한 관계를 보였다. Tyrosinase 저해 활성은 참당귀 잎, 줄기 혼합물 및 뿌리의 열수 추출물에서 가장 높은 것으로 나타났다. 이상의 실험 결과 참당귀에탄올 추출물에서는 페놀성 화합물과 플라보노이드 함량 및 환원력이 높았으며, 열수 추출물에서는 항산화 효과가 높아 참당귀 유래의 생리활성물질과 그 활성을 이용한 제품 개발에 필요한 기초 자료를 제공해주는데 유용하게 사용될 수 있을 것으로 생각된다.

• 한국환경과학회지
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• 제25권11호
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• pp.1541-1554
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• 2016

To understand the characteristics of vanadium leaching from soils formed by the weathering of basalts, paleo soil at Gosan, Jeju Island, Korea, and several present-day soils from neighboring areas were collected. Leaching experiments were carried out by two approaches: 1) batch experiments under various geochemical conditions (redox potential (Eh) and pH) and 2) continuous leaching experiments under conditions similar to those of natural environments. From the batch experiments, leached vanadium concentrations were highest under alkaline (NaOH) conditions, with a maximum value of $2,870{\mu}g/L$, and were meaningful (maximum value, $114{\mu}g/L$) under oxidizing ($H_2O_2$) conditions, whereas concentrations under other conditions (acidic-HCl, $neutral-NaHCO_3$, and $reducing-Na_2S_2O_3$) were negligible. This indicated that the geochemical conditions, in which soil-water reactions occurred to form groundwater with high vanadium concentrations, were under alkaline-oxidizing conditions. From the continuous leaching experiments, the pH and leached vanadium concentrations of the solution were in the ranges of 5.45~5.58 and $6{\sim}9{\mu}g/L$, respectively, under $CO_2$ supersaturation conditions for the first 15 days, whereas values under $O_2$ aeration conditions after the next 15 days increased to 8.48~8.62 and $9.7{\sim}12.2{\mu}g/L$, respectively. Vanadium concentrations from the latter continuous leaching experiments were similar to the average concentration of groundwater in Jeju Island ($11.2{\mu}g/L$). Furthermore leached vanadium concentrations in continuous leaching experiments were highly correlated with pH and Al, Cr, Fe, Mn and Zn concentrations. The results of this study showed that 1) alkaline-oxidizing conditions of water-rock (soil) interactions were essential to form vanadium-rich groundwater and 2) volcanic soils can be a potential source of vanadium in Jeju Island groundwater.

• 한국식품위생안전성학회지
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• 제36권6호
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• pp.528-536
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• 2021

본 연구는 십자화과 채소인 갓(Brassica juncea) 추출물을 이용하여 지표성분인 sinigrin의 함량을 분석하고, 내분비계 교란물질 환경호르몬인 비스페놀 A (BPA)로 분화를 유도한 3T3-L1 전구지방세포에서 갓 추출물과 sinigrin 처리에 대한 지방세포 분화 및 활성산소종(ROS) 생성 억제, 지방 생성 전사인자(PPARγ, C/EBPα, aP2)의 단백질 발현 감소 효능을 평가하였다. 연구 결과에 따르면 HPLC를 이용하여 측정한 갓 추출물 중 sinigrin의 함량은 21.27±0.2 mg/g 인 것으로 나타났다. BPA로 유도된 3T3-L1 전구지방세포에서 XTT assay 결과 sinigrin 180 µM 및 갓 추출물 300 ㎍/mL 농도에서 세포 독성을 보이지 않았으며, 지방세포 분화과정 중 세포 내 지방 축적량과 ROS 생성량을 비교하였을 때 갓과 sinigrin을 처리한 지방세포의 경우 지방축적량 및 ROS 생성량 모두 유의적으로 감소시키는 것으로 나타났다. 또한, 갓 추출물 및 sinigrin을 처리하였을 때 지방세포 분화를 조절하는 전사인자 PPARγ, C/EBPα 및 aP2의 발현이 억제됨을 확인하였다. 이 결과를 통해 갓은 환경호르몬 비스페놀 A로 유도된 지방세포 내 지방 축적 억제와 더불어 ROS 저감에 효과적으로 작용함을 확인하였다. 향후 sinigrin을 함유한 갓은 BPA로 인한 지질 대사 장애를 예방하는 천연물 유래 기능성 식품 소재로 활용할 가능성이 높은 것으로 기대되며, 추가로 임상 연구 및 작용기전 입증을 위한 in vivo 모델에서의 후속 연구가 진행되어야 할 것으로 사료된다.

• 미생물학회지
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• 제49권3호
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• pp.262-269
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• 2013

본 연구진은 청국장에서 수종의 미생물을 분리하였으며, 이중 소화 효소능이 뛰어난 균주를 선별하였으며, 유전학적 분석결과를 통해 본 균주가 Bacillus 속 균주임을 확인하고 Bacillus subtilis BC-P1이라 명명하였다. Bacillus subtilis BC-P1을 starter로 사용하여 청국장을 제조하였으며, protease, xylanase, chitinase activity, 혈전 분해능, 영양성분 분석 및 아미노산 분석을 통하여 B. subtilis BC-P1를 starter로 활용한 청국장 제품의 개선 가능성을 타진하였다. Bacillus subtilis BC-P1를 starter로 제조한 청국장은 기존 제품에 비해 우수한 소화효소 생성능을 보였으며, 특히 혈전분해효소 생성능이 우수함을 확인하였고, 대조군에 비해 증가된 환원당 및 총 아미노산 함량을 확인 할 수 있었다. 따라서 본 균주를 starter로 하여 청국장을 제조할 경우 기능성분, 생리활성의 증가, 품질 향상을 기대할 수 있을 것으로 판단되며, 향후 대규모 생산시 균주, 제조 조건에 관한 연구가 필요할 것으로 사료된다.

• Journal of Microbiology and Biotechnology
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• 제28권11호
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• pp.1834-1845
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• 2018

The lactobacilli associated with a fermented goat milk product from Tajikistan were isolated to characterize their technological properties and antibiotic resistances in order to assess their suitability for development as starter cultures. In this study, twenty three strains were identified by 16S rRNA sequencing as typical dairy-associated lactic acid bacterial strains, i.e. L. plantarum, L. pentosus, L. delbrueckii, L. helveticus and L. paracasei. These strains were generally susceptible to most antibiotics tested in this study and this allowed a selection of strains as safe starters. The draft genomes of four representative strains were sequenced and the number of contigs of the four assembled genomes ranged from 51 to 245 and the genome sizes ranged from 1.75 to 3.24 Mbp. These representative strains showed differences in their growth behavior and pH-reducing abilities in in vitro studies. The co-inoculation of these Lactobacillus spp. strains together with a yeast Kluyveromyces marxianus MBT-5698, or together with the yeast and an additional Streptococcus thermophilus MBT-2, led to a pH reduction to 3.4 after 48 h. Only in the case of fermentation inoculated with the co-culture, the viscosity of the milk increased noticeably. In contrast, fermentations with single strains did not lead to gelation of the milk or to a decrease in the pH after 24h. The results of this study provide a comprehensive understanding of the predominant lactobacilli related to Tajikistani fermented milk products.

• BMB Reports
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• 제48권11호
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• pp.618-623
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• 2015

FK506 binding protein 12 (FK506BP) is a small peptide with a single FK506BP domain that is involved in suppression of immune response and reactive oxygen species. FK506BP has emerged as a potential drug target for several inflammatory diseases. Here, we examined the protective effects of directly applied cell permeable FK506BP (PEP-1-FK506BP) on corneal alkali burn injury (CAI). In the cornea, there was a significant decrease in the number of cells expressing pro-inflammation, apoptotic, and angiogenic factors such as TNF-α, COX-2, and VEGF. Both corneal opacity and corneal neovascularization (CNV) were significantly decreased in the PEP-1-FK506BP treated group. Our results showed that PEP-1-FK506BP can significantly inhibit alkali burn-induced corneal inflammation in rats, possibly by accelerating corneal wound healing and by reducing the production of angiogenic factors and inflammatory cytokines. These results suggest that PEP-1-FK506BP may be a potential therapeutic agent for CAI.

• Applied Biological Chemistry
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• 제24권1호
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• pp.21-28
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• 1981

전북지방(全北地方)의 전통적(傳統的)인 재래식(在來式) 고추장의 제법(製法)을 조사(調査)하고 15종(15種)의 시료(試料)를 채취(採取)하여 성분분석(成分分析)과 관능시험(官能試驗)으로 품질(品質)을 평가(評價)하였다. 고추장용 메주는 주로 멥쌀과 콩츨 혼합(混合)하여 제조(製造)하고 고추장 담금비는 메주가루에 대한 찹쌀의 비율이 80% 이상(以上)으로 전분질원(澱粉質源)의 배합비(配合比)가 높고 고춧가루의 사용량(使用量)이 많은것이 특징(特徵)이다. 또 고추장의 맛을 좋게 하기 위(爲)하여 부원료(副原料)로 적량(適量)의 간장등(等 )을 첨가(添加)하여 주(主)로 자연숙성방법(自然熟成方法)으로 고추장을 제조(製造)하고 있다. 고추장의 성분(成分)은 식염(食鹽)과 아미노질소(窒素) 함량(含量)이 낮고 총당(總糖), 환원당(還元糖)과 ethyl alcohol 함량(含量)이 대체(大體)로 높으며 효소력(酵素力)은 미약(微弱)한 편이었다. 관능시험결과(官能試驗結果) 선정(選定)된 5종(5種)의 우량(優良)고추장은 달고 매운맛이 강(强)하고 메주취(臭)나 납두취(納豆臭)가 거의 없는 alcohol성(性)의 향긋한 향기(香氣)와 윤기있는 붉은 색상(色相)의 고추장으로 감평(鑑評)되였다.