• 대한간호학회지
• /
• 제53권4호
• /
• pp.453-467
• /
• 2023

Purpose: This study investigated the cumulative effects of depressive symptoms on cognitive function over time in community-dwelling older adults. Methods: Data were investigated from 2,533 community-dwelling older adults who participated in the Korean Longitudinal Study of Aging (KLoSA) from the 5th (2014) to the 8th wave (2020). The association between cumulative depressive symptoms and cognitive function was identified through multiple regression analysis. Results: When the multiple regression analysis was conducted from each wave, the current depressive symptoms scores and cognitive function scores were negatively associated, regardless of the waves (B5th = - 0.26, B6th = - 0.26, B7th = - 0.26, and B8th = - 0.27; all p < .001). Further, when all the previous depressive symptoms scores were added as explanatory variables in the 8th wave, the current one (B8th = - 0.09, p < .001) and the previous ones (B5th = - 0.11, B6th = - 0.09, and B7th = - 0.13; all p < .001) were also negatively associated with the cognitive function score. The delta R², which indicates the difference between the model's R² with and without the depressive symptoms scores, was greater in the model with all the previous and current depressive symptoms scores (6.4%) than in the model with only the current depressive symptoms score (3.6%). Conclusion: Depressive symptoms in older adults have a long-term impact. This results in an accumulated adverse effect on the cognitive function. Therefore, to prevent cognitive decline in older adults, we suggest detecting their depressive symptoms early and providing continuous intervention to reduce exposure to long-term depressive symptoms.

• Journal of Korean Neurosurgical Society
• /
• 제63권6호
• /
• pp.707-716
• /
• 2020

Objective : The function of B7H3, a member of the B7 family of proteins, in neuroblastoma (NB) remains poorly characterized. Here we examine the expression pattern of B7H3 in clinical NB specimens and characterize the phenotype of B7H3 knock-down in NB cell line. Methods : Immunohistochemical (IHC) staining was carried out to assess the expression of B7H3 in clinical NB specimens. Survival association was analyzed using five Gene Expression Omnibus (GEO) datasets (GSE85047, GSE45480, GSE62564, GSE16476, GSE49710). Clonogenic survival and flow cytometry were performed after B7H3 knockdown to assess the cellular proliferation and cell survival in vitro. Impact of B7H3 silencing on NB growth was examined in vivo using the SH-SY5Y xenograft model. Results : On IHC staining, B7H3 was widely expressed in clinical NB specimens. Analysis of the transcriptional profiles of five GEO datasets clinically annotated NB specimens revealed that decreased B7H3 expression was associated with improved overall survival. B7H3 knockdown suppressed the proliferation of the SH-SY5Y NB model in vitro and in vivo. Cell cycle analysis revealed that B7H3 silencing induced G1/S arrest. This arrest was associated with the suppression of E2F1 expression and induction of Rb expression. Conclusion : Our results demonstrate that B7H3 expression correlate with clinical survival in NB patients. Preliminary studies suggest that B7H3 may mediate the G1/S transition.

• 한국수자원학회논문집
• /
• 제44권3호
• /
• pp.231-248
• /
• 2011

본 연구에서는 기후변화 요소를 반영하여 홍수취약성지표 (Flood Vulnerability Index, FVI)를 개발하였고 이를 북한강 유역의 6개 중권역에 적용하였다. 기후변화 요소를 고려하기 위해 IPCC의 CGCM3 모형의 A1B와 A2 시나리오를 이용하였고 일단위로 축소화하기 위해 SDSM (Statistical Downscaling Model) 모형을 이용하였다. 홍수취약성 인자를 선정하기 위해 지속가능성 평가모형인 추진력-압력-상태-영향-반응 (Driver-Pressure-State-Impact-Response, DPSIR) 모형을 이용하였고 기후변화로 인한 홍수유출의 특성분석은 연속유출모의모형인 HSPF (Hydrological Simulation Program-Fortran)를 이용하였다. 본 연구에서 개발된 홍수취약성지수는 유역의 현상태 및 기후변화의 영향으로 인한 잠재적 취약성을 정량적인 하나의 지수로 간결하게 표현할 수 있어서 장기 수자원 및 유역관리 정책수립에 사용될 수 있을 것으로 기대된다.

• 대기
• /
• 제29권2호
• /
• pp.131-147
• /
• 2019

On the urban scale, Micro-climate analysis models for urban scale have been developed to investigate the atmospheric characteristics in urban surface in detail and to predict the micro-climate change due to the changes in urban structure. BioCAS (Biometeorological Climate Impact Assessment System) is a system that combines such analysis models and has been implemented internally in the Korea Meteorological Administration. One of role in this system is the analysis of the health impact by heat waves in urban area. In this study, the vegetation cooling models A and B were developed and linked with BioCAS and evaluated by the temperature drop at the vegetation areas during ten selected heat-wave days. Smaller prediction errors were found as a result of applying the vegetation cooling models to the heat-wave days. In addition, it was found that the effects of the vegetation cooling models produced different results according to the distribution of vegetation area in land cover near each observation site - the improvement of the model performance on temperature analysis was different according to land use at each location. The model A was better fitted where the surrounding vegetation ratio was 50% or more, whereas the model B was better where the vegetation ratio was less than 50% (higher building and impervious areas). Through this study, it should be possible to select an appropriate vegetation cooling model according to its fraction coverage so that the temperature analysis around built-up areas would be improved.

• Structural Engineering and Mechanics
• /
• 제56권6호
• /
• pp.917-938
• /
• 2015

The nonlinear numerical analysis of the impact response of reinforced concrete/mortar beam incorporated with the updated Lagrangian method, namely the Smoothed Particle Hydrodynamics (SPH) is carried out in this study. The analysis includes the simulation of the effects of high mass low velocity impact load falling on beam structures. Three material models to describe the localized failure of structural elements are: (1) linear pressure-sensitive yield criteria (Drucker-Prager type) in the pre-peak regime for the concrete/mortar meanwhile, the shear strain energy criterion (Von Mises) is applied for the steel reinforcement (2) nonlinear hardening law by means of modified linear Drucker-Prager envelope by employing the plane cap surface to simulate the irreversible plastic behavior of concrete/mortar (3) implementation of linear and nonlinear softening in tension and compression regions, respectively, to express the complex behavior of concrete material during short time loading condition. Validation upon existing experimental test results is conducted, from which the impact behavior of concrete beams are best described using the SPH model adopting an average velocity and erosion algorithm, where instability in terms of numerical fragmentation is reduced considerably.

• 한국산학기술학회논문지
• /
• 제12권4호
• /
• pp.1552-1558
• /
• 2011

본 논문에서는 알루미늄 폼을 사용한 자동차 범퍼 빔을 설계하고 충돌해석을 수행하였다. 해석모델은 B형 단면 구조를 갖는 실제 크기의 범퍼 빔이다. 저속 정면충돌 시 알루미늄 범퍼 빔의 변형량 및 내부 에너지 거동을 예측할 수 있는 ANSYS AUTODYN을 이용하였다. 7075-T6 알루미늄 합금을 사용하여 철강 재질의 빔보다 55 %의 중량 감소를 얻을 수 있었으며 알루미늄 폼을 사용한 범퍼 빔의 변형량은 철강 빔과 비슷하지만 충돌에너지의 감소가 더 큰 것을 확인할 수 있었다. 또한, 알루미늄 폼의 완충보다는 50 % 충진 시 충돌에너지 흡수가 더 좋았다.

• 대한원격탐사학회지
• /
• 제24권1호
• /
• pp.45-55
• /
• 2008

The impact on streamflow and groundwater recharge considering future potential climate and land use change was assessed using SLURP (Semi-distributed Land-Use Runoff Process) continuous hydrologic model. The model was calibrated and verified using 4 years (1999-2002) daily observed streamflow data for a $260.4km^2$ which has been continuously urbanized during the past couple of decades. The model was calibrated and validated with the coefficient of determination and Nash-Sutcliffe efficiency ranging from 0.8 to 0.7 and 0.7 to 0.5, respectively. The CCCma CGCM2 data by two SRES (Special Report on Emissions Scenarios) climate change scenarios (A2 and B2) of the IPCC (Intergovemmental Panel on Climate Change) were adopted and the future weather data was downscaled by Delta Change Method using 30 years (1977 - 2006, baseline period) weather data. The future land uses were predicted by CA (Cellular Automata)-Markov technique using the time series land use data of Landsat images. The future land uses showed that the forest and paddy area decreased 10.8 % and 6.2 % respectively while the urban area increased 14.2 %. For the future vegetation cover information, a linear regression between monthly NDVI (Normalized Difference Vegetation Index) from NOAA/AVHRR images and monthly mean temperature using five years (1998 - 2002) data was derived for each land use class. The future highest NDVI value was 0.61 while the current highest NDVI value was 0.52. The model results showed that the future predicted runoff ratio ranged from 46 % to 48 % while the present runoff ratio was 59 %. On the other hand, the impact on runoff ratio by land use change showed about 3 % increase comparing with the present land use condition. The streamflow and groundwater recharge was big decrease in the future.

• 대한토목학회논문집
• /
• 제28권6B호
• /
• pp.653-663
• /
• 2008

본 연구에서는 안성천 공도수위관측소 상류유역을 대상으로 SWAT(Soil and Water Assessment Tool) 모형을 이용하여 현재의 유역 수문환경조건을 보다 현실적으로 분석하기 위해서 기상, 수문 자료와 점오염원 운영자료, 저수지의 방류량 자료 및 경작관리 형태의 자료를 구축하여 후속연구인 "미래 기후변화 및 토지이용 변화에 따른 안성천 유역 수문-수질 변화 분석 (II)"의 기본 자료로 활용하는데 목적이 있다. 유역 현실에 보다 가까운 분석을 위해 유역특성 자료인 점오염원 운영자료, 저수지의 방류량 자료 및 경작관리 형태의 자료를 구축, 분석한 후 모형의 검 보정을 실시하였다. 유역 특성 자료에 따른 분석 결과, 경작관리의 경우 농경지로 인한 수질 부하량의 경향과 흐름이 바뀌게 되며, 저수지 적용자료 적용시는 4-5월 시기의 관개를 위하여 방류를 시도한 패턴을 확인 할 수 있었다. 또한 환경기초시설, 경작관리를 미적용 및 적용시 약 10%의 하천수질 모의결과 차이가 발생하기 때문에 유역의 실제적인 상황에 근접하게 적용하기 위해서는 대상유역내의 정확한 자료의 구축과 적용이 중요하다고 판단되며, 유역 특성 자료를 통한 검보정 결과는 (II) 연구에서 기후변화와 토지이용에 따른 유역 수문-수질 변화 분석에 활용되어 보다 신뢰도 높은 결과를 도출 할 수 있을 것으로 판단된다.

• 환경정책연구
• /
• 제9권1호
• /
• pp.31-55
• /
• 2010

기후변화 정책 분석 모델 (PAGE, Policy Analysis of Greenhouse Effect)을 이용해 여러 온실가스 배출 시나리오에 따른 기후변화의 피해 비용을 분석했다. 국내외 기후변화 영향에 관한 선행 연구 결과에 따르면 한국의 기후변화의 민감도는 경제 협력개발기구(OECD) 회원국들과 유사한 수준이 될 것으로 전망되었으나 구체적인 한국의 분야별 영향평가가 이루어져야 보다 정량적인 기후변화의 피해함수 추정이 가능할 것이다. 온실가스 배출량, 이산화황 배출량, 적응정책의 정도, 경제 성장, 인구 성장 등 많은 인자들이 기후변화로 인한 피해 정도에 영향을 미친다. 본 연구에서는 PAGE 모델을 이용해 미래의 여러 상황에 따른 기후변화의 피해 정도를 알아보기 위하여 A2, B1, Kyoto, 3가지 시나리오에 대한 분석을 하였다. 만일 전 세계가 온실가스 감축을 위한 아무 대책도 실행하지 않는다면 2100년 한국은 약 3도 정도의 온도상승이 예측되고 이로 인해 12조에서 58조정도의 피해가 일어날 것으로 분석되었다. 1990년에서 2100년까지 기후변화로 인한 누적 피해비용은 약 143조에서 921조에 이를 것으로 분석되었다.그러나 이는 소수의 피해함수에 대한 연구결과만을 반영해 산정한 결과며 분야별로 더 많은 연구가 수행되어야 보다 신뢰도 높은 피해비용을 산정할 수 있다.

• KIEE International Transactions on Electrophysics and Applications
• /
• 제11C권4호
• /
• pp.99-106
• /
• 2001

An overview of Silicon Carbide (SiC) Static Induction Transistor (SIT) development is presented. Basic conduction mechanisms are introduced and discussed, including ohmic, exponential, and space charge limited conduction (SCLC) mechanisms. Additionally, the impact of velocity saturation and temperature effects on SCLC are reviewed. The small-signal model, breakdown voltage, power density, and different gate structures are also discussed, before a final review of published SiC SIT results. Published S-band (3-4 GHz) results include 9.5 dB of gain and output power of 120 W, and L-band (1.3 GHz) results include 400 W output power, 7.7 dB of gain, and power density of 16.7 W/cm.