• Advances in nano research
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• 제6권3호
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• pp.243-255
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• 2018

Polystyrene granules were combined with nanosilver to form a nanocomposite film. One-side migration was conducted to test into three food simulants (3% acetic acid, 10% ethanol and 95% ethanol) at $40^{\circ}C$ temperature on different period of time (2, 4, 6, 8 and 10 days). It was found that, among the simulants, the highest migration amount was obtained with 3% acetic acid, while the 95% ethanol revealed the least migration level. Diffusion coefficients of nanosilver particles into simulants were estimated by inverse simulation using experimental data of concentration variation in the simulants. The finite element method used to solve the mass transfer equation and the numerical results indicates the sameresponse with the experimental data. The numerical results confirmed that the highest diffusion coefficient for acetic acid 3% (1.82E-10 to $1.76E-9m^2\;s^{-1}$) and the lowest diffusion coefficient for ethanol 95% from 2 to 10 days were obtained, respectively. Also, results of diffusion coefficient - concentration relation showed, the diffusion coefficient had in direct correlation with time and concentration. The results indicated that, in the 3% acetic acid, due to the increasing of diffusion coefficient of silver nanoparticles, they are released faster and distributed uniformly.

• Molecules and Cells
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• 제37권10호
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• pp.759-765
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• 2014

N-myc downstream-regulated gene 2 (NDRG2), which is known to have tumor suppressor functions, is frequently down-regulated in breast cancers and potentially involved in preventing the migration and invasion of malignant tumor cells. In the present study, we examined the inhibitory effects of NDRG2 overexpression, specifically focusing on the role of cyclooxygenase-2 (COX-2) in the migration of breast cancer cells. NDRG2 overexpression in MDA-MB-231 cells inhibited the expression of the COX-2 mRNA and protein, the transcriptional activity of COX-2, and prostaglandin $E_2$ ($PGE_2$) production, which were induced by a treatment with phorbol-12-myristate-13-acetate (PMA). Nuclear transcription factor-${\kappa}B$ (NF-${\kappa}B$) signaling attenuated by NDRG2 expression resulted in a decrease in PMA-induced COX-2 expression. Interestingly, the inhibition of COX-2 strongly suppressed PMA-stimulated migration and invasion in MDA-MB-231-NDRG2 cells. Moreover, siRNA-mediated knockdown of NDRG2 in MCF7 cells increased the COX-2 mRNA and protein expression levels and the PMA-induced COX-2 expression levels. Consistent with these results, the migration and invasion of MCF7 cells treated with NDRG2 siRNA were significantly enhanced following treatment with PMA. Taken together, our data show that the inhibition of NF-${\kappa}B$ signaling by NDRG2 expression is able to suppress cell migration and invasion through the down-regulation of COX-2 expression.

• 한국축산식품학회지
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• 제35권4호
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• pp.507-514
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• 2015

Deer velvet antler (DVA) is one of the most popular medicines in China. Numerous studies have demonstrated that velvet antler possess biological effects. However, data regarding its anti-migration activity on prostate cancer is scarce. In this study, we investigated the inhibitory effect of top DVA (T-DVA) on the expression of prostate-specific antigen (PSA) and migration-related genes in the human prostate cancer cell, LNCaP. The T-DVA down-regulated the expression of PSA. In addition, the Radius^TM assay revealed that T-DVA inhibited the migration behavior of prostate cancer cells. Furthermore, the expression of matrix metalloproteinase (MMP)-9 and vascular endothelial growth factor (VEGF) was also decreased with T-DVA. On the contrary, T-DVA increased the tissue inhibition of metallo-proteinase (TIMP)-1 and (TIMP)-2. Taken together, our findings indicate that the T-DVA possesses anti-migration activity on prostate cancer cells. This is the first study of DVA to report the anti-migration activity on prostate cancer.

• The Korean Journal of Physiology and Pharmacology
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• 제15권4호
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• pp.211-216
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• 2011

Glioblastoma multiforme is one of the most common and aggressive tumors in central nervous system. It often possesses characteristic necrotic lesions with hemorrhages, which increase the chances of exposure to thrombin. Thrombin has been known as a regulator of MMP-9 expression and cancer cell migration. However, the effects of thrombin on glioma cells have not been clearly understood. In the present study, influences of thrombin on glioma cell migration were examined using Boyden chamber migration assay and thrombin-induced changes in MMP-9 expression were measured using zymography, semi-quantitative RT-PCR, and Western blotting. Furthermore, underlying signaling pathways by which thrombin induces MMP-9 expression were examined. Thrombin-induced migration and MMP-9 expression were significantly potentiated in the presence of wortmannin, a PI3K inhibitor, whereas MAPK inhibitors suppressed thrombin-induced migration and MMP-9 expression in C6 glioma cells. The present data strongly demonstrate that MAPK and PI3K pathways evidently regulate thrombin-induced migration and MMP-9 expression of C6 glioma cells. Therefore, the control of these pathways might be a beneficial therapeutic strategy for treatment of invasive glioblastoma multiforme.

• 정보처리학회논문지D
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• 제12D권2호
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• pp.289-302
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• 2005

이동 에이전트는 호스트 간의 통신 횟수, 전송 데이터의 양, 에이전트의 크기, 네트워크 상태 등의 요소에 따라 매우 다양한 성능을 보이며 특히, 이주 방식은 분산 시스템의 전체 성능에 큰 영향을 준다. 대부분의 기존 이주 방식은 고정된 순서대로 호스트를 방문하고 방문한 호스트에서 작업을 수행한 후, 결과를 계속 누적시키면서 이주하는 단순 구조를 가지고 있다. 그러므로 호스트의 결점 및 장애, 서비스 부재 등과 같은 상황이나 방문해야할 호스트의 수가 많을 경우, 네트워크 소요시간이 증가되어 이동 에이전트를 사용하는 것 자체가 비효율적일 수 있다. 따라서 본 논문에서는 이러한 문제들을 해결하여 네트워크 소요시간을 최소화하기 위한 멀티캐스트 이주 모델을 설계 및 구현한다. 멀티캐스트 이주 모델은 분산된 서버의 위치 투명성 및 에이전트 객체 복제 정보를 제공하는 네이밍 에이전트와 호출 모듈만을 포함한 이동 에이전트 등과 같은 요소를 포함한다. 그리고 구현된 이주 모델을 검증하기 위해 프로토타입 시스템에 적용하여 기존 이주 방식과 비교 평가한다.

• 대한토목학회논문집
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• 제13권5호
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• pp.173-181
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• 1993

자연하천에 대한 합리적인 하천개수계획수립 및 유로의 유지관리면에서 반드시 규명되어야 할 유로만곡부에서의 정량적인 해석은 여러가지 접근방법이 있으며, 사행하천의 유로이동에 대한 예측은 도로, 교량 등의 위치선정과 기존하천구조물의 방재에 필수적이다. 하상계수가 큰 우리나라의 하천에 유로이동 예측모형을 적용할 때 유량은 기간별-지배유량을 고려하는 것이 타당할 것으로 사료되며, 본 연구대상 유역에 대한 침식계수, 유로이동에 대한 평균오차량, 하상세굴계수 등을 비교검토한 결과 유로이동을 지배하는 유량이 존재함을 알 수 있으며, 연구대상유역에서 유로이동에 대한 지배유량은 재현기간 4년에 해당하는 6,000CMS 이상으로 사료된다. 유로이동모형을 실측값이 있는 남한강의 연구대상유로에 적용하여 침식계수를 구하였으며, 계산된 침식계수를 이용하여 그 유로에서의 2000년에 대한 유로이동을 예측하였다.

• 한국지역사회생활과학회지
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• 제18권3호
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• pp.455-467
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• 2007

Recently, there has been a gradual growth of retired in-migrants in high-amenity, rural areas in Korea. However, little has known about that the retirement migration is a blessing or a blight for a local economy in Korea. Therefore, in this study, we intend to explore the relationship between retirement migration and economic development of rural communities in Korea. For this purpose, we used the 1995 and 2000 census data and annual regional statistics for 138 counties in Korea. Based on the previous empirical studies, economic development was measured by 3 indicators such as GRDP (Gross Regional Domestic Product), job creation in the wholesale and retail sector, and the increase of local tax. Also, cross-tab, scatter plot, and correlation were analyzed using the SPSS Windows Program. The finding are as follows: First, from 1995 to 2000, nearly 11 percent of rural counties showed 10 percent and over increase of in-migration rate among retirees. Second, correlation statistics showed a close relationship between retirement in-migrant flows and economic resurgence. In particular, retirement in-migration rates were significantly tied to the job creation of the wholesale and retail sector (r=.19, p<.05) as well as car ownership rate (r=.58, p<.001) resulting in the increase of local tax. However, there was non-significantly positive correlation between retirement in-migrant flows and GRDP change (r=.13). Knowledge of these relationships will be important to policy-makers and for understanding the role that retirement in-migration play in stimulating economic growth of rural communities in Korea.

• 노동경제논집
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• 제29권2호
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• pp.1-27
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• 2006

최근의 이민은 과거와 달리 숙련노동력이 주도하고 있으며 그 정도가 계속해서 커져가고 있다. 본 논문은 1990~2000년 사이에 발생한 세계 각국에서 OECD 국가로의 이민 흐름 결정요인을 숙련수준별로 분석하는 것을 그 목표로 한다. 이를 위해 최근 공개된 Doquier and Marfouk(2005)의 이민자료로부터 각국의 연평균 이민율을 계산하여 종속변수로 삼았고, 배출국과 유입국의 경제적 지표를 독립변수로 활용하여 횡단면 분석을 실시하였다. 분석 결과 유입국/배출국의 평균적 소득격차, 연쇄이민, 언어와 같이 기존 연구가 밝혀 낸 인구학적 경제적 요인이 고숙련 노동의 이민에도 작용하는 것이 확인되었다. 그러나 고숙련 노동력의 이민은 다른 숙련수준에 비해 배출국의 산업구조, 유입국에서의 숙련수준간 소득격차, 평균수명과 같이 경제구조의 발전 정도에 민감하게 반응하는 것으로 보인다. 특히 소득수준이 향상되면서 구조적 요인의 상대적인 중요성은 더 커진다는 점은 주목할 만하다. 그리고 이민율에 영어 사용이 미치는 영향 역시 고숙련 노동력에서 크게 나타나며, 카리브해와 서아프리카 지역 등에서는 지역적 특수성이 이민율을 높이는 작용을 하는 것으로 보인다. 또한 두뇌유출의 가장 큰 위협을 받는 것은 중간소득 집단에 속한 국가들인 것으로 보인다.

• 한국포장학회지
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• 제8권1호
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• pp.1-10
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• 2002

각 국가 권역별 이행실험방법에 따라 지방성 및 고온가열 식품 포장재에서의 시뮬란트별 항산화제와 DEHA의 특정이행량을 비교하였다. 고온 가열용 식품 포장재의 경우 일부 두께가 두꺼운 필름, 예를 들어 PP 필름에서는 각 국가 권역별 시뮬란트 종류와 온도 조건의 차이에 따른 항산화제의 이행량의 차이가 나타났다. 미국이나 유럽연합에서 지방성 식품의 시뮬란트를 이용하여 얻어진 실험치에 $2{\sim}5$의 reduction factor가 계산되는 것을 감안한다면 아시아 조건하에서의 이행치가 유의적으로 높아지는 결과를 초래하게 된다. 아시아의 이행 실험 조건은 해당포장재의 온도 노출 조건에 따라 다양하게 설정될 필요성이 제기되었다.

• 방사성폐기물학회지
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• 제19권1호
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• pp.113-121
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• 2021

A safety assessment of radioactive waste repositories is a mandatory requirement process because there are possible radiological hazards owing to radionuclide migration from radioactive waste to the biosphere. For a reliable safety assessment, it is important to establish a parameter database that reflects the site-specific characteristics of the disposal facility and repository site. From this perspective, solubility, a major geochemical parameter, has been chosen as an important parameter for modeling the migration behavior of radionuclides. The solubilities were derived for Am, Ni, Tc, and U, which were major radionuclides in this study, and on-site groundwater data reflecting the operational conditions of the Gyeongju low and intermediate level radioactive waste (LILW) repository were applied to reflect the site-specific characteristics. The radiation dose was derived by applying the solubility and radionuclide inventory data to the RESRAD-OFFSITE code, and sensitivity analysis of the dose according to the solubility variation was performed. As a result, owing to the low amount of radionuclide inventory, the dose variation was insignificant. The derived solubility can be used as the main input data for the safety assessment of the Gyeongju LILW repository in the future.