• Title/Summary/Keyword: time of loading

검색결과 2,555건 처리시간 0.049초

Drop Performance Test of Conceptually Designed Control Rod Assembly for Prototype Generation IV Sodium-Cooled Fast Reactor

  • Lee, Young-Kyu;Lee, Jae-Han;Kim, Hoe-Woong;Kim, Sung-Kyun;Kim, Jong-Bum
    • Nuclear Engineering and Technology
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    • 제49권4호
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    • pp.855-864
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    • 2017
  • The control rod assembly controls reactor power by adjusting its position during normal operation and shuts down chain reactions by its free drop under scram conditions. Therefore, the drop performance of the control rod assembly is important for the safety of a nuclear reactor. In this study, the drop performance of the conceptually designed control rod assembly for the prototype generation IV sodium-cooled fast reactor that is being developed at the Korea Atomic Energy Research Institute as a next-generation nuclear reactor was experimentally investigated. For the performance test, the test facility and test procedure were established first, and several free drop performance tests of the control rod assembly under different flow rate conditions were then carried out. Moreover, performance tests under several types and magnitudes of seismic loading conditions were also conducted to investigate the effects of seismic loading on the drop performance of the control rod assembly. The drop time of the conceptually designed control rod assembly for 0% of the tentatively designed flow rate was measured to be 1.527 seconds, and this agrees well with the analytically calculated drop time. It was also observed that the effect of seismic loading on the drop time was not significant.

고차원 색인 구조를 위한 효율적인 벌크 로딩 (An Efficient Bulk Loading for High Dimensional Index Structures)

  • 복경수;이석희;조기형;유재수
    • 한국정보처리학회논문지
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    • 제7권8호
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    • pp.2327-2340
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    • 2000
  • 다차원 색인 구조를 위한 기존의 벌크 로딩 알고리즘은 색인 구성 시간과 검색 성능 모두를 향상시키지 못하는 문제점을 갖는다. 이 논문은 이와 같은 문제점을 해결한 대량의 고차원 데이터에 대한 색인 구조를 위한 새로운 벌크 로딩 알고리즘을 제안한다. 제안한는 알고리즘은 색인을 구성하는 시간을 단축시키기 위해 전체 데이터 집합을 정렬하는 것이 아니라 데이터의 특성을 파악하여 피벗 값에 따라 분할하는 기법을 이용한다. 또한 검색 성능을 향상시키기 위해 데이터들의 분포 특성에 따라 분할 위치를 선택한다. 실험을 통해 제안하는 알고리즘의 기존의 알고리즘보다 색인 구성 시간과 검색 성능 측면에서 우수함을 보인다.

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비글견에서 아래턱 작은어금니 Implant의 즉시 부하에 대한 평가 (Evaluation of the Osseointegration in Immediatedly Loaded Implants in the Premolar Socket of the Mandible in Beagles)

  • 김대진;김정은;성윤상;장환수;권영삼;장광호
    • 한국임상수의학회지
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    • 제27권1호
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    • pp.55-61
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    • 2010
  • Tooth restoration with implant placement have been interested in modern veterinary dentistry. It is important to reduce the interval between the tooth extraction and the insertion of the implants, to determine the restoration time after implant placement in dogs The aim of the this study was to compare the bone mineral apposition rate of immediately loaded implants with an unloaded control during the early healing state in the artificial extraction mandible. In four Beagles, two premolar sockets (PM2 and PM3) of the both sides of the mandible were installed with a one stage titanium mini-implant with a length of 11 mm and a diameter of 3.37 mm immediately after tooth extraction. Provisional restroration was given to implants, 3 weeks after implant placement in the left side (immediate loading) and 12 weeks in the right side (delayed loading), respectively. Radiographic and histologic examinations were performed. Radiographic evaluation revealed no significant difference between two groups. Bone-implant contact was $47.1{\pm}8.9$ in immediate loading and $50.2{\pm}8.2$ in delayed loading, interthread bone density was $78.7{\pm}10.9$ in immediate loading and $73.1{\pm}15.5$ in delayed loading, and peri-implant bone density was $95.4{\pm}7.1$ in immediate loading and $95.0{\pm}5.2$ in delayed loading, respectively. Three histologic analyses showed no significant difference between delayed and immediate loading. Followed by this study, the immediate loading of implants insterted into fresh extraction sockets after tooth extraction could be considered in veterinary dentistry.

Experimental and numerical analyses on determination of indirect (splitting) tensile strength of cemented paste backfill materials under different loading apparatus

  • Komurlu, Eren;Kesimal, Ayhan;Demir, Serhat
    • Geomechanics and Engineering
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    • 제10권6호
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    • pp.775-791
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    • 2016
  • The indirect tensile strengths (ITSs) of different cemented paste backfill mixes with different curing times were determined by considering crack initiation and fracture toughness concepts under different loading conditions of steel loading arcs with various contact angles, flat platens and the standard Brazilian test jaw. Because contact area of the ITS test discs developes rapidly and varies in accordance with the deformability, ITSs of curing materials were not found convenient to determine under the loading apparatus with indefinite contact angle. ITS values increasing with an increase in contact angle can be measured to be excessively high because of the high contact angles resulted from the deformable characteristics of the soft paste backfill materials. As a result of the change of deformation characteristics with the change of curing time, discs have different contact conditions causing an important disadvantage to reflect the strength change due to the curing reactions. In addition to the experimental study, finite element analyses were performed on several types of disc models under various loading conditions. As a result, a comparison between all loading conditions was made to determine the best ITSs of the cemented paste backfill materials. Both experimental and numerical analyses concluded that loading arcs with definite contact angles gives better results than those obtained with the other loading apparatus without a definite contact angle. Loading arcs with the contact angle of $15^{\circ}$ was found the most convenient loading apparatus for the typical cemented paste backfill materials, although it should be used carefully considering the failure cracks for a valid test.

FastIO: 스마트 TV 앱의 고속 구동 기법 (FastIO: High Speed Launching of Smart TV Apps)

  • 이철희;황태호;원유집;이성진
    • 정보과학회 논문지
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    • 제43권7호
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    • pp.725-735
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    • 2016
  • 스마트 TV는 콘텐츠를 제공하기 위해 웹 브라우저로 웹킷을 사용한다. 웹킷은 앱을 실행하기 위해 HTML, CSS, 자바스크립트, 이미지와 같은 웹 자원을 사용한다. 따라서 애플리케이션이 시작될 때 웹킷은 메모리로 자원을 적재하고 돔트리와 렌더트리를 생성한다. 하지만 스마트 TV 앱은 웹 자원을 디스크에 저장하기 때문에 돔트리와 렌더트리는 변하지 않는다. 그러므로 만약 돔트리와 렌더트리를 재사용할 수 있다면 앱의 로딩 시간을 단축할 수 있다. 본 논문은 동적으로 할당 받은 메모리에 영속성을 부여하는 기법인 FastIO를 제시하고 웹킷 기반의 웹 브라우저에 적용하였다. 따라서 웹 자원을 스토리지로부터 메모리로 적재하고 in-memory 구조로 변환하는 과정을 제거 하였다. 실험 결과로 돔트리와 렌더트리가 생성 과정까지의 시간을 비교하였고, FastIO를 적용한 웹 브라우저가 기존 웹 브라우저보다 SSD, Ramdisk, eMMC에서 7.9배, 44.8배, 2.9배의 속도가 향상되었다.

휠오프로딩을 고려한 동서 위치유지 기동 계획 연구 (A Study on the East/West Station Keeping Planning Considering Wheel Off-Loading)

  • 이상철;주광혁;김방엽;박봉규;박영웅
    • 한국항공우주학회지
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    • 제34권9호
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    • pp.60-66
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    • 2006
  • 현재 개발 중인 통신해양기상위성은 남쪽면에만 태양전지판이 장착되어 있기 때문에 태양복사압에 의하여 누적되는 모멘텀을 줄이기 위해 휠오포로딩을 정기적으로 수행해야 한다. 일반적으로 정지궤도 위성은 경도와 이심률을 보정하기 위해서 2번의 위치유지 기동을 매 주기마다 수행하는데, 본 논문에서는 기상센서와 해양센서의 충분한 관측시간을 확보하기 위해서 2번의 동서위치보정 기동 중 1번의 기동을 휠오포로딩과 동시에 수행될 수 있다. 선형 궤도기동 방정식을 적용하여 기동시각과 기동크기를 얻었다. 이렇게 구한 기동을 적용하여 수치적분으로 시뮬레이션을 수행하였다. 또한 이를 휠오프로딩과 동시에 수행하지 않는 일반적 방법과 비교 검토 하였다.

미세금속입자의 루멘충전 특성평가 (Evaluation of Lumen-loaded Fiber with Micro Metal Particles)

  • 성용주;정웅기;이지영
    • 펄프종이기술
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    • 제44권4호
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    • pp.99-107
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    • 2012
  • In this study, the lumen loading technology for preparing magnetic papers were evaluated. The rice husk fiber, softwood kraft pulp, hardwood kraft pulp were applied and the morphological properties of pits on the those fibers were investigated with SEM. The softwood kraft pulp had the bigger size of pits, $3{\sim}5{\mu}m$ in diameter, which resulted in higher loading amount. The comparison of two methods for lumen loading such as the low concentration method with the disintegrator and the high concentration method with the Hobart mixer showed the Hobart mixer could resulted in the higher efficiency. The conditions of lumen loading process such loading time, addition amount of metal particles and addition of PEI were also evaluated. The magnetic hysteresis loop of handsheet samples made of lumen loaded fiber with $Fe_3O_4$ and $Fe_2O_3$ were examined. The differences in magnetic properties could be found according to the ferrite types.

성견에서 즉시 부하 후 임프란트 안정성 평가 : 임상적, 방사선학적 연구 (ASSESSMENT OF IMPLANT STABILITY AFTER IMMEDIATE LOADING IN DOGS : CLINICAL AND RADIOGRAPHIC STUDY)

  • 이주영;김수관;김상호;김완배
    • Maxillofacial Plastic and Reconstructive Surgery
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    • 제27권2호
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    • pp.131-139
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    • 2005
  • The therapeutic goal of implant dentistry is not merely tooth replacement but total oral rehabilitation. Considering dental implants as a treatment option can be provided patients with positive, long-term results. Implant dentistry has gone through many phases over the years. Modern technology and design allows us to predictably place our dental implants often load the implants at the time of placement. The purpose of this study is to evaluate the implant stability after immediate loading in dogs. The control group was performed delay loading and experimental group was immediate loading. Each group was measured periotest value(PTV) to evaluate clinical mobility and performed radiographic examination to evaluate marginal bone loss. Statistically significant difference was not founded in control group between experimental group in PTV(P>0.05) and marginal bone loss(P>0.05). Finally, implant stability after immediate loading was similar to delay loading implant.

염산 딜티아젬의 방출을 제어하기 위한 삼중 폴리머 매트릭스 시스템 (A Ternary Polymeric Matrix System for Controlled Drug Delivery of Highly Soluble Drug with High Drug Loading : Diltiazem Hydrochloride)

  • 김현조;레자 파시히
    • Journal of Pharmaceutical Investigation
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    • 제31권1호
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    • pp.19-25
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    • 2001
  • The purpose of this study was to use a ternary polymeric matrix system for high drug loading of a highly soluble drug for controlled release delivery. The controlled drug delivery of diltiazem HCl (solubility > 50% in water at $25^{\circ}C$) with high loading dose (the final loading dose of drug was 34%) from a ternary polymeric matrix (gelatin, pectin, HPMC) was successfully accomplished. This simple monolithic system with 240 mg drug loading provided near zero-order release over a 24 hour-period by which time the system was completely dissolved. The release kinetics of diltiazem HCl tablet with high loading dose from the designed ternary polymeric system was dependent on the ratios of HPMC : pectin binary mixture. The release rate increased as pectin : HPMC ratio were increased. Swelling behavior of the ternary system and the ionic interaction of formulation components with cationic diltiazem molecule appear to control drug diffusion and the release kinetics. Comparable release profiles between commercial product and the designed system were obtained. The binding study between gelatin with diltiazem HCl showed the presence of two binding sites for drug interaction with subsequent controlled diffusion upon swelling. This designed delivery system is easy to manufacture and drug release behavior is highly reproducible and offers advantages over the existing commercial product.

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Low velocity impact behavior of concrete beam strengthened with CFRP strip

  • Kantar, Erkan;Anil, Ozgur
    • Steel and Composite Structures
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    • 제12권3호
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    • pp.207-230
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    • 2012
  • Nowadays CFRP (Carbon Fiber Reinforced Polymer) became widely used materials for the strengthening and retrofitting of structures. Many experimental and analytical studies are encountered at literature about strengthening beams by using this kind of materials against static loads and cyclic loads such as earthquake or wind loading for investigating their behavior. But authors did not found any study about strengthening of RC beams by using CFRP against low velocity impact and investigating their behavior. For these reasons an experimental study is conducted on totally ten strengthened RC beams. Impact loading is applied on to specimens by using an impact loading system that is designed by authors. Investigated parameters were concrete compression strength and drop height. Two different sets of specimens with different concrete compression strength tested under the impact loading that are applied by dropping constant weight hammer from five different heights. The acceleration arises from the impact loading is measured against time. The change of velocity, displacement and energy are calculated for all specimens. The failure modes of the specimens with normal and high concrete compression strength are observed under the loading of constant weight impact hammer that are dropped from different heights. Impact behaviors of beams are positively affected from the strengthening with CFRP. Measured accelerations, the number of drops up to failure and dissipated energy are increased. Finite element analysis that are made by using ABAQUS software is used for the simulation of experiments, and model gave compatible results with experiments.