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김상철,Kim, Sang-Cheol 대한석유협회 2014 석유와 에너지 Vol.292 No.-
개인 차량을 유지하기위해 지불해야 하는 것으로 차량구입비용, 보험료, 자동차세, 차량정비 비용 등 그 규모가 만만치 않다. 그러다 보니 한 대의 차를 여러 사람이 시간을 쪼개어 활용하면 더 효율적이겠다는 생각을 하는 사람들이 생겨났고, 그래서 생겨난 새로운 자동차 이용방법이 카셰어링이다. 카셰어링은 원하는 시간에, 원하는 만큼, 필요한 최소의 금액만을 지불하는 자동차에 대한 현명한 소비를 하는 하나의 방법이 될 것이다.
김상철,김연태,신동철 한국구조물진단유지관리공학회 2012 한국구조물진단유지관리공학회 논문집 Vol.16 No.6
The high-flowing concrete requires additionally or excessively more expensive admixture than conventional concrete. So, the concrete has not to be widely used in practical field due to the increase of production price, need of additional facilities, and excessive development of concrete strength in associate with addition of too much cementitious material even though it has more significant advantages than conventional concrete. Thus, this study aims at developing high-flowing concrete with general strength unlike high strength which has been carried out in conventional study. To observe the role of aggregate in the concrete quantitatively and to increase the performance of high-flowing concrete effectively, parametric studies were carried out such as W/C, s/a, fineness modulus of aggregate, contribution degree of particle sizes, and the effect of 13mm aggregate and fine stone powder as a partial replacement of aggregates. And the effect of these factors on performance of the concrete was evaluated by measuring slump-flow and gap of penetration height in U-typed instrument. As a result, it was found that flowability of high-flowing concrete depends upon grading of fine aggregate more significantly than that of coarse aggregate and is enhanced greatly as fineness modulus of fine aggregate decreases and the value of s/a increases. In addition, the application of 13mm aggregate and fine stone powder are expected as a partial replacement of aggregate in order to increase the performance of high-flowing concrete more effectively. 고유동 콘크리트는 일반 콘크리트에 비해 고가의 각종 혼화재료를 과량 혹은 추가로 사용하여야 하기 때문에 재료비 단가 상승, 추가 설비의 필요 등의 문제점이 있고, 재료분리를 방지하기 위해 분체량을 증가시킴으로써 과잉 강도발현 등 고유동 콘크리트가 갖고 있는 많은 장점이 있음에도 특수 목적이외에는 그 사용에 있어 제약이 있었다. 이에 본 연구에서는 기존에 개발된 고강도성 고유동 콘크리트와 달리 일반 강도의 고유동 콘크리트의 상용화를 위해 콘크리트 구성 재료 중에서 골재를 중심으로 이들의 합리적 활용과 콘크리트의 성능향상 모색을 위해 정량적 인자별 실험을 수행하였다. 사용한 실험변수로 물-시멘트비, 잔골재율, 골재의 조립률, 입자 크기의 중요도, 13mm 골재와 미립분의 활용에 대해 검토하였으며, 슬럼프플로와 U형 충전시험의 충전고차로 평가하였다. 연구결과, 고유동 콘크리트 성상은 굵은 골재보다 잔골재 입도에 대한 의존도가 높으며, 잔골재율이 높을수록, 조립률이 낮을수록 충전성과 유동성 확보에 유리하였다. 또한, 골재의 대체재로써 13mm 골재 및 미립의 석분을 활용함으로써 보다 효율적으로 충전성과 유동성을 향상시킬 수 있음이 본 연구를 통해 확인되었다.
김상철,홍근식,황선일,김지은,김아로,조중양,박희경,박지현,구자성,박종무,배희준,한문구,강동화,오미선,유경호,이병철,이지성,조용진 대한신경과학회 2012 Journal of Clinical Neurology Vol.8 No.4
Background and Purpose Stroke requires consistent care, but there is concern over the “weekend effect”, whereby a weekend admission results in a poor outcome. Our aim was to determine the impact of weekend admission on clinical outcomes in patients with acute ischemic stroke in Korea. Methods The outcomes of patients admitted on weekdays and weekends were compared by analyzing data from a prospective outcome registry enrolling 1247 consecutive patients with acute ischemic stroke admitted to four neurology training hospitals in South Korea between September 2004 and August 2005. The primary outcome was a poor functional outcome at 3 months,defined as modified Rankin Scale (mRS) of 3-6. Secondary outcomes were 3-month mortality,use of thrombolysis, complication rate, and length of hospitalization. Shift analysis was also performed to compare overall mRS distributions. Results On weekends, 334 (26.8%) patients were admitted. Baseline characteristics were comparable between the weekday and weekend groups except for more history of heart disease and shorter admission time in weekend group. Univariate analysis revealed poor functional outcome at 3 months, 3-month mortality, complication rate, and length of hospitalization did not differ between the two groups. In addition, overall mRS distributions were comparable (p=0.865). After adjusting for baseline factors and stroke severity, weekend admission was not associated with poor functional outcome at 3 months (adjusted odds ratio, 1.05; 95% CI, 0.74-1.50). Furthermore, none of secondary endpoints differed between the two groups in multivariate analysis. Conclusions Weekend admission was not associated with poor functional outcome than weekday admission in patients with acute ischemic stroke in this study. The putative weekend effect should be explored further by considering a wider range of hospital settings and hemorrhagic stroke.