• 한국표면공학회지
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• 제52권2호
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• pp.72-77
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• 2019

To study the characteristics of AC driven OLED, we fabricated the fluorescent OLEDs and analyzed the electroluminescence characteristics of OLEDs with AC negative voltage. The luminance and the current density of the OLED decreased, and the number and size of the dark spots increased in proportion to the duration time and level of the applied AC negative voltage. The current efficiency of the OLED was improved when high AC negative voltage was applied within a short time. When the AC negative voltage of 10 V was applied for 1 minute, the efficiency was improved by 12.4%. Also, the degradation of luminance and current efficiency due to the duration of light emission was improved in the case of OLED applied for 1 minute with 10 V AC negative voltage. These are expected as a result of the improvement of the leakage current characteristics by eliminating the short-circuit region formed by the defect of the OLED at the AC negative high voltage. As a result, the continuous application of AC negative voltage reduced the luminance and the current density of OLED, but the temporary application of AC negative voltage with the proper time and voltage could improve the efficiency and lifetime of OLED.

• 한국해양바이오학회지
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• 제12권2호
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• pp.99-107
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• 2020

Osteoarthritis (OA) is an inflammatory degenerative joint disease that is accompanied by irreversible joint cartilage destruction. Recently, the antioxidant effects of Carpomitra costata, which is a type of brown algae, have been reported, but their effects on OA have not been investigated. In this study, the anti-osteoarthritic effect of the ethanol extract of C. costata (EECC) on SW1353 human chondrocytes was studied. Results showed that EECC significantly attenuated the interleukin-1β (IL-1β)-induced release of pro-inflammatory mediators, including prostaglandin E2 and nitric oxide (NO), as well as expressions of cyclo-oxygenase-2 and inducible NO synthase. EECC also inhibited the IL-1β-induced expressions of matrix metalloproteinase-1, -3, and -13 in SW1353 chondrocytes, which reduced their extracellular secretion. In addition, the oxidative stress induced by IL-1β was confirmed to be blocked by EECC due to the inhibition of reactive oxygen species generation. Moreover, EECC suppressed IL-1β-mediated translocation of nuclear factor-kappa B (NF-κB) from cytosol into the nucleus and the degradation of IκB-α, which indicates that EECC exhibits anti-inflammatory effects by inhibiting the NF-κB signaling pathway. These results are the first to demonstrate the anti-inflammatory activities of C. costata extracts in chondrocytes, thus suggesting that this algae extract may be used in the treatment of OA.

• 한국압력기기공학회 논문집
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• 제17권1호
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• pp.28-35
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• 2021

The flow accelerated corrosion (FAC) is one of significant aging and degradation mechanism and can affect structural integrity of CANDU feeder pipes. Pipe burst can occur under normal operation pressure (min. 10 MPa) if wall-thinning of the feeder pipe due to FAC is accumulated. Previous studies considered simple shapes of feeder pipe with local wall-thinning in order to conservatively assess structural integrity of wall-thinned feeder pipe. In this paper, a new FE model is developed, having an actual shape of the feeder pipe (double bent) as well as the actual wall-thinning shape and location based on the in-service inspection result. Then, the burst pressure assessment of the wall-thinned feeder pipe is performed using lower bound limit load analysis considering elastic-perfectly plastic material. In addition, an improved formulation to predict the burst pressure of the wall-thinned feeder pipe is presented and the safety margin is compared with an existing assessment method.

• Nutrition Research and Practice
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• 제17권4호
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• pp.641-659
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• 2023

BACKGROUND/OBJECTIVES: The skin is the outermost organ of the human body and plays a protective role against external environmental damages, such as sunlight and pollution, which affect anti-oxidant defenses and skin inflammation, resulting in erythema or skin reddening, immunosuppression, and epidermal DNA damage. MATERIALS/METHODS: The present study aimed to investigate the potential protective effects of red orange complex H extract (ROC) against ultraviolet (UV)-induced skin photoaging in Skh:HR-2 mice. ROC was orally administered at doses of 20, 40, and 80 mg/kg/day for 13 weeks, along with UV irradiation of the mice for 10 weeks. RESULTS: ROC improved UV-induced skin barrier parameters, including erythema, melanin production, transepidermal water loss, elasticity, and wrinkle formation. Notably, ROC inhibited the mRNA expression of pro-inflammatory cytokines (interleukin 6 and tumor necrosis factor α) and melanogenesis. In addition, ROC recovered the UV-induced decrease in the hyaluronic acid and collagen levels by enhancing genes expression. Furthermore, ROC significantly downregulated the protein and mRNA expression of matrix metalloproteinases responsible for collagen degradation. These protective effects of ROC against photoaging are associated with the suppression of UV-induced phosphorylation of c-Jun NH2-terminal kinase and activator protein 1 activation. CONCLUSIONS: Altogether, our findings suggest that the oral administration of ROC exerts potential protective activities against photoaging in UV-irradiated hairless mice.

• 한국농공학회논문집
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• 제65권4호
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• pp.45-52
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• 2023

This study was conducted to examine the possibility of use as a structural material for ginseng cultivation facilities of recycled plastics. In order to determine the possibility that recycled plastic can replace timber used as a structural material for ginseng cultivation facilities, the specimens collected by elapsed time were compared with timber through bending tests. In addition, in order to analyze the effect of external environmental conditions on recycled plastic products, bending test was conducted with the specimens that had completed weathering test and accelerated heat aging test respectively. As a result, the bending strength of recycled plastic specimens with the elapsed time of 360 days was lower than that of timber. But bending strength of recycled plastic specimens exceeded the design allowable stress standard set by the Korea design standard (MOLIT, 2016). There was no degradation in quality of recycled plastic due to the external environment, and it was found that there would be no problem even if it was used as a structural material for ginseng cultivation facilities.

• Restorative Dentistry and Endodontics
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• 제47권3호
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• pp.28.1-28.12
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• 2022

Objectives: Metalloproteinase-inhibiting agents, such as chitosan, can prevent collagen degradation in demineralized dental substrates, thereby improving the adhesive interface. This study evaluated the bond strength (BS) and chemical and morphological characterization of the adhesive interface after applying chitosan solution to demineralized dentin. Materials and Methods: The 80 third molars were selected. Forty teeth underwent caries induction using the pH cycling method. The teeth were divided according to the treatment: distilled water (control) and 2.5% chitosan solution. The surfaces were restored using adhesive and composite resins. Half of the specimens in each group were aged, and the other half underwent immediate analyses. The teeth were sectioned and underwent the microtensile bond strength test (µTBS), and chemical and morphological analyses using energy-dispersive spectroscopy and scanning electron microscopy, respectively. Data analysis was performed using 3-way analysis of variance. Results: For µTBS, sound dentin was superior to demineralized dentin (p < 0.001), chitosan-treated specimens had higher bond strength than the untreated ones (p < 0.001), and those that underwent immediate analysis had higher values than the aged specimens (p = 0.019). No significant differences were observed in the chemical or morphological compositions. Conclusions: Chitosan treatment improved bond strength both immediately and after aging, even in demineralized dentin.

• 한국공간구조학회논문집
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• 제23권4호
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• pp.81-88
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• 2023

Numerous factors contribute to the deterioration of reinforced concrete structures. Elevated temperatures significantly alter the composition of the concrete ingredients, consequently diminishing the concrete's strength properties. With the escalation of global CO2 levels, the carbonation of concrete structures has emerged as a critical challenge, substantially affecting concrete durability research. Assessing and predicting concrete degradation due to thermal effects and carbonation are crucial yet intricate tasks. To address this, multiple prediction models for concrete carbonation and compressive strength under thermal impact have been developed. This study employs seven machine learning algorithms-specifically, multiple linear regression, decision trees, random forest, support vector machines, k-nearest neighbors, artificial neural networks, and extreme gradient boosting algorithms-to formulate predictive models for concrete carbonation and thermal impact. Two distinct datasets, derived from reported experimental studies, were utilized for training these predictive models. Performance evaluation relied on metrics like root mean square error, mean square error, mean absolute error, and coefficient of determination. The optimization of hyperparameters was achieved through k-fold cross-validation and grid search techniques. The analytical outcomes demonstrate that neural networks and extreme gradient boosting algorithms outshine the remaining five machine learning approaches, showcasing outstanding predictive performance for concrete carbonation and thermal effect modeling.

• 치위생과학회지
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• 제14권1호
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• pp.29-34
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• 2014

본 연구는 최근 심미보철물 제작에 널리 사용되는 지르코니아의 저온열화가 수복물의 안정성 및 내구성에 영향을 미치는 여부를 확인하기 위하여 전단결합강도를 측정하였다. 디스크 형태의 시편을 각각 7개씩 제작한 후 전장도재를 축성하여, ISO 13356 규격에 의거한 조건으로 고압증기 멸균기에 저온열화의 정도를 조절하기 위하여 3, 5, 10시간 동안 수열처리를 진행하였다. 제한된 조건하에 시행된 실험을 통해 전단결합강도를 확인하였으며, 측정 후 파절양상을 관찰 하였다. 저온열화 처리 전후의 시편에 대한 전단결합강도의 변화는 각 실험군별 유의한 차이가 있었다(p<0.05). 10시간을 저온열화 처리한 시편이 가장 낮은 전단결합강도로 나타났으며, 처리시간이 길어질수록 전단결합강도가 낮아지는 경향을 보였다. 파절 양상으로 저온열화 처리를 하지 않은 시편에서 응집성 파절을 보였으며, 저온열화 처리가 길어질수록 혼합형 파절 경향으로 전환되었다. 결론적으로 본 연구는 저온열화 현상이 진행될수록 지르코니아 코어와 전장도재 간의 결합강도가 낮아지는 경향을 확인하였다. 본 실험결과를 토대로 치과용 지르코니아를 이용한 보철물 제작과정과 환자에게 장착 후 안정적인 사용을 위하여 저온열화 현상에 대한 주의가 필요할 것으로 생각된다.

• 한국작물학회:학술대회논문집
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• 한국작물학회 2017년도 9th Asian Crop Science Association conference
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• pp.98-98
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• 2017

Leaf senescence is the process of aging in plants. Chlorophyll degradation during leaf senescence has the important role translocating nutrients from leaves to storage organs. The functional stay-green with slow leaf yellowing and photosynthesis activity maintenance has been considered one of strategy for increasing crop productivity. Here, we have identified two QTLs on chromosome 9 and 10 for leaf senescence with chlorophyll content of RIL population derived from a cross between Hanareum 2, early leaf senescence Indica-type variety, and Unkwang, delayed leaf senescence Japonica variety. Among these QTLs, we chose qPLS1 QTL on chromosome 9 for further study. qPLS1 was found to explain 14.4% of the total phenotypic variation with 11.2 of LOD score. Through fine-mapping approach, qPLS1 QTL locus was narrowed down to about 25kb in the marker interval between In/del-4-7-9 and In/del-5-9-4. There are 3 genes existed within 25kb of qPLS1 locus: LOC_Os09g36200, LOC_Os09g36210, and LOC_Os09g36220. Among these genes, transcript level of LOC_Os09g36200 was increased during the leaf senescence stage and the expression level of LOC_Os09g36200 in Indica was higher than in Japonica. Finally, we chose LOC_Os09g36200 as candidate gene and renamed it as OsPLS1-In and OsPLS1-Jp from Indica- and Japonica-type rice, respectively. OsPLS1-In and OsPLS1-Jp overexpressing transgenic plants showed both early leaf senescence phenotype. These results indicate that OsPLS1 functions in chlorophyll degradation and the difference of expression level of OsPLS1 cause the difference of leaf senescence between Indica and Japonica in rice.

• 한국식품영양과학회지
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• 제42권3호
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• pp.389-396
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• 2013

본 연구에서는 난소절제를 통하여 폐경기가 유도된 백서 모델에서 생산지가 다른 국내산 로얄제리 식이와 이소플라본을 식이로 공급한 후 표피의 필라그린 및 유리아미노산의 함량과 관련 대사 효소의 발현 변화를 정상대조군인 SHAM군 및 난소절제군인 OVX군과 비교 분석하였다. Profilaggrin, filaggrin 및 total filaggrin의 발현은 SHAM군> RJ2군> OVX군=IF군> RJ1군 순으로 RJ1군의 profilaggrin, filaggrin의 발현량이 가장 낮게 나타났다. Profilaggrin에서 filaggrin으로, filaggrin에서 유리아미노산으로의 분해하는 과정에 관여하는 여러 효소 중에 PAD3의 발현은 RJ2군에서 가장 높았으나 SHAM군을 비롯하여 OVX군, RJ1군, IF군에서는 군간 유의성이 없었다. 전체 유리아미노산의 함량은 SHAM군에 비해 OVX군에서 다소 감소하였으나 RJ1군 및 IF군에서 SHAM군보다 높게 나타났다. 특히 RJ1군에서 aspartate와 proline의 함량이 SHAM군에 비해 현저히 높아졌다. 결론적으로 RJ1군에서는 filaggrin의 함량 감소가 있었지만 표피 보습 유지기능이 있는 aspartate 및 proline을 비롯한 전체 유리아미노산의 함량이 높아졌다. RJ1군의 로얄제리가 폐경으로 인해 감소되는 표피의 보습인자 중 궁극적으로 피부 보습에 관여하는 천연보습인자의 유리아미노산의 발현을 증가시켜 손상된 표피의 장벽기능 보완에 긍정적 영향을 보였다. RJ2군은 profilaggrin, filaggrin을 포함한 total filaggrin의 함량이 증가되었으나 그 분해산물인 유리 아미노산의 함량은 SHAM군과 유사하였다. RJ2군의 로얄제리가 유리아미노산의 전구단백질의 발현 증가를 야기하나 유리아미노산으로의 분해는 촉진시키지 못하였음을 시사한다. 이는 산지별 로얄제리의 피부 보습 기능에 미치는 영향이 다르게 나타날 수 있음을 의미하며 추후 각 산지별 유효성분의 분석과 함께 관련 효능에 대한 연구가 이루어질 필요성이 있다. 본 연구에서 국내산 로얄제리의 식이 공급이 피부 보습 관련 건강기능식품 개발 소재로서의 가능성이 있을 것으로 사료된다.