• 콘크리트학회논문집
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• 제14권3호
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• pp.430-439
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• 2002

콘크리트 내 이형철근 정착의 중요성은 철근콘크리트 구조에서 필수적인 요소이다. 표준갈고리는 인장정착을 위하여 광범위하게 사용되어 왔으나 콘크리트의 고강도화에 따라 부재 단면이 작아지는 추세 등으로 인하여 보-기둥 접합부에서는 좁은 공간에 철근이 과밀하게 배근됨으로써 시공 상의 어려움이 제기되고 있다. 단부 기계적 정착장치를 갖는 철근(단부보강철근)을 사용하는 경우 정착길이를 감소시키고, 정착부 상세를 단순화하며, 반복하중에 대한 저항능력을 증가시키는 등의 이점으로 인하여 공사비와 공사시간을 단축시킬 수 있을 것으로 사료된다. 본 연구는 단부보강철근의 뽐힘강도 및 거동에 대한 실험적 연구이다. D25 이형철근을 사용하여 수행된 총 33회의 뽑힘강도시험에서 실험변수는 철근 묻힘깊이, 철근중심과 콘크리트 가장자리간 거리, 단부보강 철물의 크기, 그리고 횡보강근(전단철근)의 간격이었다. 실험적으로 결정된 뽐힘강도는 CCD 방법에 의해 계산된 예측값에 관전하는 결과를 얻을 수 있었다. 철근 묻힘깊이가 증가하거나 철근과 콘크리트 가장자리간 거리가 증가할수록 뽑힘강도도 증가하였고 단부보강 철물의 크기가 증가함에 따라 뽑힘강도도 대체로 증가하는 경향을 보였다. 전단철근의 영향에 대한 연구로부터 뽑힘강도에 대한 파괴변에 걸친 전단철근의 영향을 나타내기 위하여 CCD 방법을 이용한 뽑힘강도 예측시 보정계수의 사용이 제안되었다.

• 한국산학기술학회논문지
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• 제17권9호
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• pp.552-558
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• 2016

최근 노후화된 콘크리트 건축물에 대한 보수 및 보강에 대한 관심이 높아지고 있는데 이러한 건축물에 대한 안전성을 정확히 평가하기 위해서는 콘크리트 강도를 필수적으로 알아야 한다. 이러한 콘크리트 강도를 평가하는 방법으로 코어채취 방법이 가장 효과적이며 많이 사용되는 방법이다. 그런데 구조물에 따라 경우에 따라서는 어쩔 수 없이 철근이 포함된 코어가 채취되는데 코어 강도를 평가하기 위한 규정에는 이러한 철근이 포함된 코어 사용을 인정하지 않고 있다. 따라서 본 연구는 콘크리트 구조물의 건전성을 평가하고자 하는 안전진단 및 보수 보강 관련 업체에 철근이 포함된 코어 공시체에 대한 콘크리트 강도를 정확하게 평가할 수 있도록 우리나라 실정에 맞는 정량적인 강도 판정기준을 제시하고자 하였다. 이러한 연구를 수행하기 위하여 1종류의 무 배근과 14종류의 배근을 한 공시체를 준비 하였고 압축강도 시험을 실시하였다. 결과적으로 철근체적으로 약 $50cm^3$까지 배근된 경우(직경 13mm인 철근 4개 정도)의 공시체의 강도는 무배근 공시체 강도의 80% 정도 이상이라는 것을 예측할 수 있다.

• Journal of Biosystems Engineering
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• 제33권6호
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• pp.446-452
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• 2008

Machine vision system was used for analyzing leaf color disorders of tomato plants in a greenhouse. From the day when a few leave of tomato plants had started to wither, a series of images were captured by 4 times during 14 days. Among several color image spaces, Saturation frame in HSI color space was adequate to eliminate a background and Hue frame was good to detect infected disease area and tomato fruits. The processed image ($G{\sqcup}b^*$ image) by OR operation between G frame in RGB color space and $b^*$ frame in $La^*b^*$ color space was useful for image segmentation of a plant canopy area. This study calculated a ratio of the infected area to the plant canopy and manually analyzed leaf color disorders through an image segmentation for Hue frame of a tomato plant image. For automatically analyzing plant leave disease, this study selected twenty-seven color patches on the calibration bars as the corresponding to leaf color disorders. These selected color patches could represent 97% of the infected area analyzed by the manual method. Using only ten color patches among twenty-seven ones could represent over 85% of the infected area. This paper showed a proposed machine vision system may be effective for evaluating various leaf color disorders of plants growing in a greenhouse.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2001년도 봄 학술발표회 논문집
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• pp.1017-1022
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• 2001

The bend resistance of coated reinforcing bar is greatly influenced by adhesion strength of bar and coating materials and transformation of coating materials to the bar. Expecially, tearing state or a limited microscopic cracks are predicted on the inside and outside of bending angle because of adhesion strength and elongation is very different with types of polymer materials using bar coating, and these parts are accelerated corrosion as penetration of bar corrosion effects factor. In this study, cement modified polymer are prepared four types and differ from polymer cement ratio of 50% and 100%, coating thickness of 250$\mu$m and 450$\mu$m, coating number, curing age of 3, 7, 14 and 280days, and then tested bend resistance as bending angle $90^{\circ}$, $135^{\circ}$ and $180^{\circ}$ for observe the microscopic demage effect according as bar bend. From the test results, when is used cement modified polymer as coating materials of bar, St/BA is showed excellent bend resistance than a polyacrylic emulsion and SBR because of softness. But it is to need attention because as coating parts are pressed down and tearing, also experimental study is proceeded to corrosion potential on the inside and outside of coated reinforcing bar.

• Journal of the Korean Association of Oral and Maxillofacial Surgeons
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• 제30권1호
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• pp.49-55
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• 2004

The management of mandibular condylar fractures in children has long been a matter of controversy. The fracture, if not treated appropriately, may result in complications such as disturbance of mandibular growth and temporomandibular joint ankylosis. They are usually treated nonsurgically, which has been proved to be satisfactory in the long term results. Nineteen children with 25 condylar fractures experienced during their growth period (age at trauma from 10 months to 12 years, mean 7.0 years) were studied. All patients were treated by arch bars and intermaxillary fixation for $7{\sim}14$ days. They have been evaluated with clinical and radiographic examination. The maximum mouth opening and lateral movement of the mandible were within normal limits. There was no malocclusion or ankylosis. Beginning of remodelling was evident at postoperative $1{\sim}3$ months. Remodelling of the condyle was good in 21, while partial adjustment occured in the other 4 condyles. These results suggest that the conservative treatment of condylar fractures in growing children results in good functional results and good remodelling of the condyle.

• Membrane and Water Treatment
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• 제11권2호
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• pp.111-121
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• 2020

The fouling of Nanofiltration membrane (NF) was examined using wastewater containing reactive black dye RB5 of 1500 Pt/Co color concentrations with 16890 mg/l TDS collected from El-alamia Company for Dying and Weaving in Egypt. The NF-unit was operated at constant pressure of 10 bars, temperature of 25℃, and flowrate of 420 L/min. SEM, EDX, and FTIR were used for fouling characterization. Using the ROIFA-4 program, the total inorganic fouling load was 1.07 mM/kg present as 49.3% Carbonates, 10.1% Sulfates, 37.2% Silicates, 37.2% Phosphates, and 0.93% Iron oxides. The permeate flux, recovery, salt rejection and mass transfer coefficients of the dye molecules were reduced significantly after fouling. The results clearly demonstrate that the fouling had detrimental effect on membrane performance in dye removal, as indicated by a sharp decrease in permeate flux and dye recovery 68%. The dye mass transfer coefficient was dropped dramatically by 34%, and the salt permeability increased by 14%. In this study, all the properties of the membrane used and the fouling that caused its poor condition are identified. Another study was conducted to regeneration fouled membrane again by chemical methods in another article (Abdel-Fatah et al. 2017).

• Composites Research
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• 제14권3호
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• pp.77-89
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• 2001

초고속 일체형 주축의 공진주파수가 일체형 주축 시스템의 모터 회전자의 질량과 주축의 굽힘 강성에 의존하기 때문에 초고속 주축 시스템의 동적 특성을 향상시키기 위해 주축과 회전자를 각각 고분자 기지 섬유강화 복합재료와 자성분말이 함침된 에폭시 수지를 이용하여 설계하였다. 설계된 복합재료 회전자의 자기 특성을 향상시키기 위해 내부에 강철 코어를 삽입하였으며, 강철 코어와 전도체 봉의 기하학적 형상의 변화가 전동기의 성능에 미치는 효과를 파악하기 위해 자기 해석을 수행하였다. 유한요소해석을 통해 복합재료 회전자의 최적의 기하학적 조건을 제안하였다. 또한 복합 재료 회전자 재료의 열특성을 파악하기 위해 TMA, DMA및 VSM을 이용한 기계적, 전자기적 물성측정을 수행하여 복합재료 회전자의 최적 설계에 적용하였다.

• 한국어류학회지
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• 제12권4호
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• pp.259-263
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• 2000

1998년 8월 14일부터 18일 까지 전라남도 신안군 우이군도의 조간대에 서식하는 어류를 채집하였다. 조사기간 동안 채집된 어류는 한국미기록 1종을 포함하여 모두 5목 15과 22속 25종이였다. 이 가운데 망둑어과 Gobiidae 어류가 6종, 청베도라치과 Blenniidae 어류가 3종이었고, 출현 빈도가 가장 높은 어종은 망둑어과의 점망둑 Chasmichthys dolichognathus, 두줄망둑 Tridentiger trigonocephalus, 풀망둑 Synechogobius hasta 였다. 한편 성촌(St. 2)에서 채집된 1개체는 Pomacentridae (자리돔과)의 자리돔속에 포함되는 Abudefduf bengalensis로 동정되었고, 이 종은 몸에 검은 가로줄무늬를 가진 특징으로 "흑줄돔"으로 명명하고자 한다.

• Wind and Structures
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• 제20권1호
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• pp.75-93
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• 2015

This work is focused on a parametric numerical study of the barrier's bar inclination shelter effect in crosswind scenario. The parametric study combines mesh morphing and design of experiments in automated manner. Radial Basis Functions (RBF) method is used for mesh morphing and Ansys Workbench is used as an automation platform. Wind barrier consists of five bars where each bar angle is parameterized. Design points are defined using the design of experiments (DOE) technique to accurately represent the entire design space. Three-dimensional RANS numerical simulation was utilized with commercial software Ansys Fluent 14.5. In addition to the numerical study, experimental measurement of the aerodynamic forces acting on a vehicle is performed in order to define the critical wind disturbance scenario. The wind barrier optimization method combines morphing, an advanced CFD solver, high performance computing, and process automaters. The goal is to present a parametric aerodynamic simulation methodology for the wind barrier shelter that integrates accuracy and an extended design space in an automated manner. In addition, goal driven optimization is conducted for the most influential parameters for the wind barrier shelter.

• 한국해양공학회지
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• 제20권3호
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• pp.7-14
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• 2006

This paper discusses the structural design and analysis of a 6,000 meters depth-rated capable deep-sea unmanned underwater vehicle (UUV) system. The UUV system is currently under development by Maritime and Ocean Engineering Research Institute(MOERI), Korea Ocean Research and Development Institute (KORDI). The UUV system is composed of three vehicles - a Remotely Operated Vehicle (ROV), an Autonomous Underwater Vehicle (AUV) and a Launcher - which include underwater equipment. The dry weight of the system exceeds 3 tons hence it is necessary to carry out the optimal design of structural system to ensure the minimum weight and sufficient space within the frame for the convenient use of the embedded equipments. In this paper, therefore, the structural design and analysis of the ROV and launcher frame system were carried out, using the optimizing process. The cylindrical pressure vessels for the ROV were designed to resist the extreme pressure of 600 bars, based on the finite element analysis. The collapse pressure for the cylindrical pressure vessels was also checked through a theoretical analysis.