• Asian Pacific Journal of Cancer Prevention
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• 제16권18호
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• pp.8271-8279
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• 2016

Background: Hepato-carcinogenesis is multifaceted in its molecular aspects. Among the interplaying agents are altered gap junctions, the proteasome/autophagy system, and mitochondria. The present experimental study was designed to outline the roles of these players and to investigate the tumor suppressive effects of curcumin with or without mesenchymal stem cells (MSCs) in hepatocellular carcinoma (HCC). Materials and Methods: Adult female albino rats were divided into normal controls and animals with HCC induced by diethyl-nitrosamine (DENA) and $CCl_4$. Additional groups treated after HCC induction were: Cur/HCC which received curcumin; MSCs/HCC which received MSCs; and Cur+MSCs/HCC which received both curcumin and MSCs. For all groups there were histopathological examination and assessment of gene expression of connexin43 (Cx43), ubiquitin ligase-E3 (UCP-3), the autophagy marker LC3 and coenzyme-Q10 (Mito.Q10) mRNA by real time, reverse transcription-polymerase chain reaction, along with measurement of LC3II/LC3I ratio for estimation of autophagosome formation in the rat liver tissue. In addition, the serum levels of ALT, AST and alpha fetoprotein (AFP), together with the proinflammatory cytokines $TNF{\alpha}$ and IL-6, were determined in all groups. Results: Histopathological examination of liver tissue from animals which received DENA-$CCl_4$ only revealed the presence of anaplastic carcinoma cells and macro-regenerative nodules. Administration of curcumin, MSCs; each alone or combined into rats after induction of HCC improved the histopathological picture. This was accompanied by significant reduction in ${\alpha}$-fetoprotein together with proinflammatory cytokines and significant decrease of various liver enzymes, in addition to upregulation of Cx43, UCP-3, LC3 and Mito.Q10 mRNA. Conclusions: Improvement of Cx43 expression, nonapoptotic cell death and mitochondrial function can repress tumor growth in HCC. Administration of curcumin and/or MSCs have tumor suppressive effects as they can target these mechanisms. However, further research is still needed to verify their effectiveness.

• Journal of Periodontal and Implant Science
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• 제50권5호
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• pp.327-339
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• 2020

Purpose: The purpose of this study was to examine the local tissue reactions associated with 3 different poly(lactic-co-glycolic acid) (PLGA) prototype membranes and to compare them to the reactions associated with commercially available resorbable membranes in rats. Methods: Seven different membranes-3 synthetic PLGA prototypes (T1, T2, and T3) and 4 commercially available membranes (a PLGA membrane, a poly[lactic acid] membrane, a native collagen membrane, and a cross-linked collagen membrane)-were randomly inserted into 6 unconnected subcutaneous pouches in the backs of 42 rats. The animals were sacrificed at 4, 13, and 26 weeks. Descriptive histologic and histomorphometric assessments were performed to evaluate membrane degradation, visibility, tissue integration, tissue ingrowth, neovascularization, encapsulation, and inflammation. Means and standard deviations were calculated. Results: The histological analysis revealed complete integration and tissue ingrowth of PLGA prototype T1 at 26 weeks. In contrast, the T2 and T3 prototypes displayed slight to moderate integration and tissue ingrowth regardless of time point. The degradation patterns of the 3 synthetic prototypes were similar at 4 and 13 weeks, but differed at 26 weeks. T1 showed marked degradation at 26 weeks, whereas T2 and T3 displayed moderate degradation. Inflammatory cells were present in all 3 prototype membranes at all time points, and these membranes did not meaningfully differ from commercially available membranes with regard to the extent of inflammatory cell infiltration. Conclusions: The 3 PLGA prototypes, particularly T1, induced favorable tissue integration, exhibited a similar degradation rate to native collagen membranes, and elicited a similar inflammatory response to commercially available non-cross-linked resorbable membranes. The intensity of inflammation associated with degradable dental membranes appears to relate to their degradation kinetics, irrespective of their material composition.

• 한국직업건강간호학회지
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• 제26권3호
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• pp.142-150
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• 2017

Purpose: The purpose of this descriptive, cross-sectional study was to identify the factors affecting health-related quality of life by examining the relationships among posttraumatic stress, health-related work limitations, and family support in firefighters. Methods: The data were collected from 390 firefighters working in four fire stations located in the G district using self-report questionnaires. The collected data were analyzed using descriptive statistics, t-test, one-way ANOVA along with the $Scheff{\acute{e}}$ test, and multiple regression. Results: As per the results of multiple regression analysis, the factors affecting health-related quality of life in firefighters were posttraumatic stress, health-related work limitations, and family support. This model explained 31% of the variance in health-related quality of life (F=30.03, p<.001). Conclusion: Considering the findings of this study, there is a need to reduce posttraumatic stress and health-related work limitations and develop family support toward firefighters.

• 천문학회보
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• 제42권2호
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• pp.66.2-66.2
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• 2017

The Korea Astronomy and Space Science Institute plans to develop a coronagraph in collaboration with National Aeronautics and Space Administrative (NASA) and install it on the International Space Station (ISS). The coronagraph is an externally occulted one stage coronagraph with a field of view from 2.5 to 15 solar radii. The observation wavelength is approximately 400 nm where strong Fraunhofer absorption lines from the photosphere are scattered by coronal electrons. Photometric filter observation around this band enables the estimation of 2D electron temperature and electron velocity distribution in the corona. Together with the high time cadence (< 12 min) of corona images to determine the geometric and kinematic parameters of coronal mass ejections, the coronagraph will yield the spatial distribution of electron density by measuring the polarized brightness. For the purpose of technical demonstration, we intend to observe the total solar eclipse in 2017 August for the filter system and to perform a stratospheric balloon experiment in 2019 for the engineering model of the coronagraph. The coronagraph is planned to be installed on the ISS in 2021 for addressing a number of questions (e.g. coronal heating and solar wind acceleration) that are both fundamental and practically important in the physics of the solar corona and of the heliosphere.

• 한국수학교육학회지시리즈A:수학교육
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• 제44권2호
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• pp.307-323
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• 2005

The purpose of this study was to develop a program to cultivate mathematical creativity based on open-ended problem and to investigate its effect. The major features of this innovative program are (a) breaking up fixations, (b) multiple answers, (c) various strategies, (d) problem posing, (e) exploring strategies, (f) selecting and estimating, (g) active exploration through open-ended problems. 20 units for 7th grade mathematics were developed. This study hypothesizes that experimental students may develop more divergent thinking abilities than their traditional counterparts. The participants were 7th grade students attending middle schools in Seoul. Instruments were pre and post tests to measure mainly divergent thinking skills through open-ended problems. The results indicated that the experimental students achieved better than the comparison students on overall and each component of fluency, flexibility, and originality of divergent thinking skills, when deleting the effect of covariance of the pretest. The developed program can be a useful resource for teachers to use in enhancing their students' creative thinking skills. Further this open-ended approach can be served as a model to implement in classes. This study suggests that further investigations are needed in order to examine effects on affective domains such as motivation and task perseverance which are also considered as important factors of creativity.

• 대한기계학회논문집
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• 제10권1호
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• pp.34-42
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• 1986

본 논문에서는 균열면이 원호(circular arc)를 이루고, Comninou 모델과 같이 균열면의 일부가 접촉되어 있는 경우 L적분이 적분경로에 무관함을 증명하고 이를 이용하여 재료가 서로 다른 원형 개재물과 기재와의 경계면에 존재하는 계면 균열에서의 응력확대계수를 구하는 방법에 대해 살펴보았다. 기지가 무한 고체이고 접촉역이 작아 접촉역의 존재가 균열선단에서 멀리 떨어진 곳에서의 응력장에 거의 영향을 끼치지 아`는 경우에는 접촉역을 가정하지 않은 문제에 대한 해, 즉 진동특성을 나타내는 해로 부터, L적분의 성질을 이용하여, 접촉역을 가정하였을 때의 응력확대 계수를 간단한 꼴로 표시할 수 있었고, 유한의 기지에 원형 개재물이 존재하는 문제에 대해서는 F.E.M을 사용하여 L적분을 계산함으로써 응력확대계수를 구할 수 있었다.

• 한국추진공학회지
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• 제1권2호
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• pp.74-83
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• 1997

본 연구에서는 원통형 연소실에서 발생하는 고주파 연소불안정을 연소응답함수와 n-$\tau$ 음향 불안정 해석방법을 사용하여 예측하였다. 열역학적 변수들과 속도는 시간 평균성분 및 변화성분으로 분리하여 선형으로 전개하였으며, 유동은 비회전류로 가정하여 속도 포텐샬 함수를 위한 지배방정식으로 수식화하였다. 연소응답의 계산에는 화염면 상, 하류에서의 연소실반응과 화염면에서의 연속조건이 적용되었다. 연소응답은 압력간섭계수 n과 감응시간지연 $\tau$로 변환되어 중립불안정한계를 결정하였다. LOX-RP1 추진제 조합의 원통형 연소실에서 연소압력 및 추진제 혼합비의 변화는 연소 음향반응과 중립불안정에 영향을 주지 않으나, 긴 거주시간에 의한 화염면 발생의 지연과 화염면 하류에서의 공간은 고주파 연소불안정의 발생에 강한 영향을 주는 것으로 예측되었다. 결과적으로 연소의 음향응답에는 추진제의 거주시간, 연소실 형상조건과 노즐에 의한 감쇠효과가 중요한 파라메터인 것으로 나타났다.

• 대한조선학회논문집
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• 제39권2호
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• pp.34-44
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• 2002

선체 외판 중 약 70% 정도가 3차원 곡면 형상으로 구성되어 있다. 이러한 3차원 형상을 자동으로 성형하기 위해서 수년간 많은 연구를 수행하여 오고 있는 실정이다. 본 연구의 목적은 가열현상을 합리적으로 대변할 수 있는 역학적 모델을 도입하여 가열 Simulator를 개발하는데 있다. 이를 위해 가열 결과에 영향을 줄 수 있는 가열 위치 ,강판의 두께, 가열 속도 등 다양한 인자로써 실험을 수행하였다. 본 연구에서 개발한 가열 Simulator의 정당성을 입증하고자 몇 가지 모델에 대해 적용하여, 실험결과와 Simulator의 추정치를 비교한 결과 만족할 만한 결과를 나타내었으며, Simulator에 적용된 이론적 배경의 합당성을 확인할 수 있었다.

• 가정과삶의질연구
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• 제9권1호통권17호
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• pp.81-94
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• 1991

The Purpose of this study is to determine how Korean and United Sates families manage resourcese. Further, socioeconomic and social psychological determinants of frequency of family resoures management will be investigated for each country. Comparision of results well be made to find similarities and differences between Korea and the U.S. Most studies of family resource management have used urban samples, so this study adds to understanding of another segment of the populations. Family resource management variables, as dependent variables, were measured by asking respondents how often they used a variety of wasys to handle finances and time. Independent variables were : (a) total household income, (b) respondents education, (c) respondents ages, (d) householder size, (e) family adaptability, (f) family cohesion, and (g) interpersonal communications. Data for the Korean sample were collected in rural areas of South Korea during summer 1989, U.S. data were collected in two counties of Illinois. The data used in this study include 473 Korean samples and 301 U.S. families. In both samples, the respondent was the financial manager, the person who usually handled the finances and paid the bills. The data were analyzed by frequencys, t-test, and multiple regression analysis methods. As a results, U.S. respondents tended to engage in family resource management more frequently than Korean respondents. This could be attributed to a longer history of consumer education and financial management education taught in the public schools and through the Cooperative Extension Service in the U.S. Social-psycological variables were significant predictors of frequency of family financial management in both samples. the differences in both samples are that, in Korea, frequency of family financial management increased as household size and educational years increased, however, in the United States, the relationships of these variables were not significant. Some similarities and differences were found in Korea and the U.S. families, and this results represents that interpersonal communications are important determinants, even in different cultures. One hadn, the difference of socio-cultural factors result as the difference of some statisical differences. Findings from this study have important implications for research and education, and can be applicated to study of family resource management in other rural areas.

• Asian-Australasian Journal of Animal Sciences
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• 제28권5호
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• pp.703-715
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• 2015

One of the challenges to increase milk production in a large pasture-based herd with an automatic milking system (AMS) is to grow forages within a 1- km radius, as increases in walking distance increases milking interval and reduces yield. The main objective of this study was to explore sustainable forage option technologies that can supply high amount of grazeable forages for AMS herds using the Agricultural Production Systems Simulator (APSIM) model. Three different basic simulation scenarios (with irrigation) were carried out using forage crops (namely maize, soybean and sorghum) for the spring-summer period. Subsequent crops in the three scenarios were forage rape over-sown with ryegrass. Each individual simulation was run using actual climatic records for the period from 1900 to 2010. Simulated highest forage yields in maize, soybean and sorghum- (each followed by forage rape-ryegrass) based rotations were 28.2, 22.9, and 19.3 t dry matter/ha, respectively. The simulations suggested that the irrigation requirement could increase by up to 18%, 16%, and 17% respectively in those rotations in El-Nino years compared to neutral years. On the other hand, irrigation requirement could increase by up to 25%, 23%, and 32% in maize, soybean and sorghum based rotations in El-Nino years compared to La-Nina years. However, irrigation requirement could decrease by up to 8%, 7%, and 13% in maize, soybean and sorghum based rotations in La-Nina years compared to neutral years. The major implication of this study is that APSIM models have potentials in devising preferred forage options to maximise grazeable forage yield which may create the opportunity to grow more forage in small areas around the AMS which in turn will minimise walking distance and milking interval and thus increase milk production. Our analyses also suggest that simulation analysis may provide decision support during climatic uncertainty.