• Nutrition Research and Practice
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• 제14권3호
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• pp.203-217
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• 2020

BACKGROUND/OBJECTIVE: Centella asiatica, also known as Gotu kola, is a tropical medicinal plant native to Madagascar, Southeast Asia, and South Africa. It is well known to have biological activities, including wound healing, anti-inflammatory, antidiabetic, cytotoxic, and antioxidant effects. The purpose of this study was to determine the efficacy of extracts of C. asiatica against age-related eye degeneration and to examine their physiological activities. MATERIALS/METHODS: To determine the effects of CA-HE50 (C. asiatica 50% EtOH extract) on retinal pigment cells, we assessed the cytotoxicity of CoCl₂ and oxidized-A2E in ARPE-19 cells and observed the protective effects of CA-HE50 against N-methyl-N-nitrosourea (MNU)-induced retinal damage in C57BL/6 mice. In particular, we measured factors related to apoptosis and anti-oxidation and the protein levels of rhodopsin/opsin. We also measured glucose uptake to characterize glucose metabolism, a major factor in cell protection. RESULTS: Induction of cytotoxicity with CoCl₂ and oxidized-A2E inhibited decreases in the viability of ARPE-19 cells when CA-HE50 was administered, and promoted glucose uptake under normal conditions (P < 0.05). In addition, CA-HE50 inhibited degeneration/apoptosis of the retina in the context of MNU-induced toxicity (P < 0.05). In particular, CA-HE50 at 200 mg/kg inhibited the cleavage of pro-caspase-3 and pro-poly (ADP-ribose)-polymerase and maintained the expressions of nuclear factor erythroid 2-related factor 2 and heme oxygenase-1 similar to normal control levels. Rhodopsin/opsin expression was maintained at a higher level than in normal controls. CONCLUSION: A series of experiments confirmed that CA-HE50 was effective for inhibiting or preventing age-related eye damage/degeneration. Based on these results, we believe it is worthwhile to develop drugs or functional foods related to age-related eye degeneration using CA-HE50.

• Preventive Nutrition and Food Science
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• 제5권4호
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• pp.219-224
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• 2000

Dieary effects of sea tangle on immune functions were investigated in diabetic mice. Four groups of ICR mice weighing 33.36$\pm$1.01 g were fed either an AIN-76 diet only (control), or with additional sea tangle powder, sea tangle water extract, and alginate at the level of 13.6%, 4%, and 1%, respectively by weight. Cellulose was omitted in sea tangle powder and alginate diets. After 10 days of feeding respective experimental diets, all mice were made diabetic by five consecutive intramuscular injections of streptozotocin (40mg/kg body weight per day) and fed the diets for four more weeks. Plasma IgG concentrations but not those of IgM were significantly higher in mice fed sea tangle powder, extract or alginate than those on the control diet. Plasma TNF$\alpha$ levels were, however, lower in those fed sea tangle power or water extract than control and alginate fed groups. TNF$\alpha$ releases from macro phages isolated from four groups and cultured with 5 $\mu\textrm{g}$/mL LPS for 24 hors showed a similar tendency to the results of plasma concentrations in the respective groups, but IL-1$\beta$ releases were not different among four groups. Lymphocyte proliferation in response to LPS (10$\mu\textrm{g}$/mL) measured using splenocytes cultured for 3 days was highest in the alginate fed group (594$\pm$38%) and those of sea tangle powder (536$\pm$47%) and extract (547$\pm$34%) fed groups tended to be higher than the control (523$\pm$30%). It is concluded that sea tangle contains immunomodulatory components besides alginate that could enhance humoral immunity of itself. The immunomodulatory effects of sea tangle constituents is regarded as beneficial for diabetic subjects.

• Nutrition Research and Practice
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• 제10권6호
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• pp.623-628
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• 2016

BACKGROUND/OBJECTIVES: Obesity-induced steatohepatitis accompanied by activated hepatic macrophages/Kupffer cells facilitates the progression of hepatic fibrinogenesis and exacerbates metabolic derangements such as insulin resistance. Heme oxyganase-1 (HO-1) modulates tissue macrophage phenotypes and thus is implicated in protection against inflammatory diseases. Here, we show that the flavonoid quercetin reduces obesity-induced hepatic inflammation by inducing HO-1, which promotes hepatic macrophage polarization in favor of the M2 phenotype. MATERIALS/METHODS: Male C57BL/6 mice were fed a regular diet (RD), high-fat diet (HFD), or HFD supplemented with quercetin (HF+Que, 0.5g/kg diet) for nine weeks. Inflammatory cytokines and macrophage markers were measured by ELISA and RT-PCR, respectively. HO-1 protein was measured by Western blotting. RESULTS: Quercetin supplementation decreased levels of inflammatory cytokines ($TNF{\alpha}$, IL-6) and increased that of the anti-inflammatory cytokine (IL-10) in the livers of HFD-fed mice. This was accompanied by upregulation of M2 macrophage marker genes (Arg-1, Mrc1) and downregulation of M1 macrophage marker genes ($TNF{\alpha}$, NOS2). In co-cultures of lipid-laden hepatocytes and macrophages, treatment with quercetin induced HO-1 in the macrophages, markedly suppressed expression of M1 macrophage marker genes, and reduced release of MCP-1. Moreover, these effects of quercetin were blunted by an HO-1 inhibitor and deficiency of nuclear factor E2-related factor 2 (Nrf2) in macrophages. CONCLUSIONS: Quercetin reduces obesity-induced hepatic inflammation by promoting macrophage phenotype switching. The beneficial effect of quercetin is associated with Nrf2-mediated HO-1 induction. Quercetin may be a useful dietary factor for protecting against obesity-induced steatohepatitis.

• 한국초등수학교육학회지
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• 제19권1호
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• pp.39-56
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• 2015

본 연구에서는 초등학교에서 수학 수업을 효율적으로 진행하기 위해 요구되는 교사 지식의 다양한 범주들 중 하나인 수학과 교수 학습 관련 이론에 대해 현재 교사들이 얼마나 알고 있는 가를 조사하였다. 초등학교 교사의 수학과 교수 학습 관련 이론에 대한 지식을 측정하기 위해, 수학과 교수 학습 이론과 관련한 27개의 문항을 자체 개발, 317명의 초등학교 교사를 대상으로 설문을 실시하였다. 독립표본 T-검증과 일원배치분산분석을 이용한 설문지 통계 분석 결과, 수학과 교수 학습 관련 이론에 대한 지식은 교사의 교직 경력 및 초등학교 교사 자격증의 등급과 음의 상관관계가 있으며, 성별, 학위 여부와는 특별한 연관성이 없는 것으로 조사 되었다. 본 연구의 결과는 초등학교 수학 수업과 연관된 교사의 지식에 대한 이해의 폭을 넓히는 데 도움을 줄 것으로 기대되며, 교사 연수 및 학위 과정 프로그램의 개선 방향과 관련하여 의미 있는 시사점을 제공할 것으로 기대된다.

• 센서학회지
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• 제24권1호
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• pp.15-21
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• 2015

Transparent and conductive multilayer thin films consisting of three alternating layers FZTO/Ag/$WO_3$ have been fabricated by radio-frequency (RF) sputtering for the applications as transparent conducting oxides and the structural and optical properties of the resulting films were carefully studied. The single layer fluorine doped zinc tin oxide (FZTO) and tungsten oxide ($WO_3$) films grown at room temperature are found to have an amorphous structure. Multilayer structured electrode with a few nm Ag layer embedded in FZTO/Ag/$WO_3$ (FAW) was fabricated and showed the optical transmittance of 87.60 % in the visible range (${\lambda}=380{\sim}770nm$), quite low electrical resistivity of ${\sim}10^{-5}{\Omega}cm$ and the corresponding figure of merit ($T^{10}/R_s$) is equivalent to $3.0{\times}10^{-2}{\Omega}^{-1}$. The resultant power conversion efficiency of 2.50% of the multilayer based OPV is lower than that of the reference commercial ITO. Asymmetric D/M/D multilayer is a promising transparent conducting electrode material due to its low resistivity, high transmittance, low temperature deposition and low cost components.

• 한국초등수학교육학회지
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• 제23권3호
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• pp.289-303
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• 2019

본 연구에서는 비판적 인종 이론의 관점에서 학교 수학 교육에서 인종 문제를 다룬 연구들을 분석하였다. 본 연구는 두 부분으로 구성 된다. 첫 번째 부분에서는 국내외 문헌 연구를 바탕으로 사회 정의를 위한 수학의 의미와 이를 주제로 한 연구들의 동향을 분석한다. 이를 통해 사회 정의를 위한 수학 교육의 의의와 방향을 도출한다. 두 번째 부분에서는 비판적 인종 이론을 토대로 사회 정의를 위한 국내 수학 관련 연구를 검토한다. 본 연구에서는 비판적 인종 이론의 기본 원리인 인종적 영속성 또는 인종 사실주의, 자유주의 비판, 교차성의 관점에서 기존 연구들을 검토하였다. 분석 결과 현재 인종 문제와 관련한 사회 정의를 위한 수학 교육에서는 학생들 스스로 문제를 찾고 이를 수학 수업에서 논의하는 과정에 대한 연구가 부족하며, 수학 교실 안에서 학생 스스로 차별의 요소를 자각하고 이를 해결하는 접근법에 대한 고민이 필요하다는 점을 발견할 수 있었다. 또한 그동안 수학 교육 연구에서 인종 문제가 다른 차별 요소와 필연적으로 연결되어있다는 관점은 충분히 다루어지지 않은 부분으로 후속 연구의 필요성을 확인할 수 있었다. 이러한 시사점은 향후 인종 문제와 관련한 사회 정의를 위한 수학 교육 연구 방향을 설정하는데 근거 자료로 활용될 수 있다.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제10권2호
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• pp.769-786
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• 2016

Object recognition and object location have always drawn much interest. Also, recently various computational models have been designed. One of the big issues in this domain is the lack of an appropriate model for extracting important part of the picture and estimating the object place in the same environments that caused low accuracy. To solve this problem, a new Salient Based Bag of Visual Word (SBBoVW) model for object recognition and object location estimation is presented. Contributions lied in the present study are two-fold. One is to introduce a new approach, which is a Salient Based Bag of Visual Word model (SBBoVW) to recognize difficult objects that have had low accuracy in previous methods. This method integrates SIFT features of the original and salient parts of pictures and fuses them together to generate better codebooks using bag of visual word method. The second contribution is to introduce a new algorithm for finding object place based on the salient map automatically. The performance evaluation on several data sets proves that the new approach outperforms other state-of-the-arts.

• 대한조선학회논문집
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• 제57권4호
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• pp.241-253
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• 2020

The Small-Unit Riverine Craft (SURC) is a small high-speed vessel used by navies and marine corps in relatively shallow waterway environments, such as riverine areas or littoral coasts. In the past, SURCs have primarily been rigid-hulled inflatable boats constructed using composite materials such as glass fiber reinforced plastics. More recently, single-hull SURCs have been manufactured using aluminum for weight reduction. In this study, a Carbon Fiber Reinforced Polymer (CFRP) material was applied instead to examine its feasibility in the basic design of an SURC with a hull length of 10 m. The CFRP structural design was obtained using the properties of a marine CFRP laminate, determined in a previous study. Next, the designed CFRP SURC was modeled to confirm its functionality, then compared with existing aluminum SURCs, indicating that the CFRP SURC was 41.49 % lighter, reduced fuel consumption by 30 %, and could sail 50 NM further for every hour of engine operation. A method for reducing the high cost of carbon fiber was also proposed based on the adjustment of the carbon fiber content to provide the optimum strength where required. The data developed in this study can be used as a basis for further design of CFRP craft.

• Smart Structures and Systems
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• 제25권1호
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• pp.111-122
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• 2020

Researchers up to date have introduced several Structural Health Monitoring (SHM) techniques with varying advantages and drawbacks for each. Satellite positioning systems (GPS, GLONASS and GALILEO) based techniques proved to be promising, especially for high natural period structures. Particularly, the GPS has proved sufficient performance and reasonable accuracy in tracking real time dynamic displacements of flexible structures independent of atmospheric conditions, temperature variations and visibility of the monitored object. Tall structures are particularly sensitive to oscillations produced by different sources of dynamic actions; such as typhoons. Wind forces induce in the structure both longitudinal and perpendicular displacements with respect to the wind direction, resulting in torsional effects, which are usually more complex to be detected. To efficiently track the horizontal rotations of the in-plane sections of such flexible structures, two main issues have to be considered: a suitable sensor topology (i.e., location, installation, and combination of sensors), and the methodology used to process the data recorded by sensors. This paper reports the contributions of the measurements recorded from dual frequency GPS receivers and uni-axial accelerometers in a full-scale experimental campaign. The Canton tower in Guangzhou-China is the case study of this research, which is instrumented with a long-term structural health monitoring system deploying both accelerometers and GPS receivers. The elaboration of combining the obtained rather long records provided by these two types of sensors in detecting the torsional behavior of the tower under ambient vibration condition and during strong wind events is discussed in this paper. Results confirmed the reliability of GPS receivers in obtaining the dynamic characteristics of the system, and its ability to capture the torsional response of the tower when used alone or when they are combined with accelerometers integrated data.

• Molecules and Cells
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• 제43권3호
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• pp.264-275
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• 2020

Reactive oxygen species (ROS) play a significant role in intracellular signaling and regulation, particularly when they are maintained at physiologic levels. However, excess ROS can cause cell damage and induce cell death. We recently reported that eIF2α phosphorylation protects hepatocytes from oxidative stress and liver fibrosis induced by fructose metabolism. Here, we found that hepatocyte-specific eIF2α phosphorylation-deficient mice have significantly reduced expression of the epidermal growth factor receptor (EGFR) and altered EGFR-mediated signaling pathways. EGFR-mediated signaling pathways are important for cell proliferation, differentiation, and survival in many tissues and cell types. Therefore, we studied whether the reduced amount of EGFR is responsible for the eIF2α phosphorylation-deficient hepatocytes' vulnerability to oxidative stress. ROS such as hydrogen peroxide and superoxides induce both EGFR tyrosine phosphorylation and eIF2α phosphorylation. eIF2α phosphorylation-deficient primary hepatocytes, or EGFR knockdown cells, have decreased ROS scavenging ability compared to normal cells. Therefore, these cells are particularly susceptible to oxidative stress. However, overexpression of EGFR in these eIF2α phosphorylation-deficient primary hepatocytes increased ROS scavenging ability and alleviated ROS-mediated cell death. Therefore, we hypothesize that the reduced EGFR level in eIF2α phosphorylation-deficient hepatocytes is one of critical factors responsible for their susceptibility to oxidative stress.