• 제목/요약/키워드: safety reflector

검색결과 39건 처리시간 0.024초

Modeling and characterization of beryllium reflector elements under irradiation conditions

  • Ahmed H. Elhefnawy;Mohamed A. Gaheen;Hanaa H. Abou Gabal;Mohamed E. Nagy
    • Nuclear Engineering and Technology
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    • 제55권12호
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    • pp.4583-4590
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    • 2023
  • This study aims at modeling the beryllium reflector poisoning under neutron irradiation conditions and calculating the impact of beryllium poisoning on the core parameters of ETRR-2 research reactor. The CITVAP code was used to calculate the neutron flux and parameters of ETRR-2 core with beryllium reflector elements. The neutron flux in each reflector element was calculated to solve the modeling equations for the atomic densities of lithium-6 (6Li), tritium-3 (3H), and helium-3 (3He) using the BERYL program. The results are discussed based on CITVAP calculations of the core excess reactivity and cycle length Full Power Days (FPD). Possible solutions to minimize the degradation due to beryllium poisoning are also discussed and compared based on calculations.

재귀반사 안전소재를 활용한 아동복 개발에 관한 연구 - 가시성 향상을 위한 적절한 위치 파악을 중심으로 - (Safety Reflectors in Children's Wear - The Proper Position for Improving Visibility -)

  • 정진아;조진숙
    • 대한가정학회지
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    • 제44권2호
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    • pp.93-101
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    • 2006
  • Children's wear needs extra safety features to avoid unexpected dangers. On the way to school, children are exposed to traffic very often. Especially in the early morning or late evening, or on dark cloudy days, they might be unrecognized by drivers without safety reflectors on their clothing as a means of raising visibility. Therefore, safety reflectors on clothing can protect children from traffic accidents. The research was carried out as follows. 1. Reflector manufacturers were interviewed regarding how Reflective and Reflexite reflect light back to the light source, what kind of safety reflector products are available, and how these materials are being used in the clothing industry. 2. Mothers of primary school children were interviewed to find out what they think about the effect of safety reflectors, the need for clothing using safety reflectors and the design preferences. 3. In order to apply safety reflectors efficiently, the position on the clothing of the greatest visibility from the light source must be determined. 4. Shirts, pants and jumpers for 8-year-old girls and boys were designed as a case study of applying safety reflectors to clothing. The designs were verified through wearing test.

Infrared Thermography Characterization of Defects in Seamless Pipes Using an Infrared Reflector

  • Park, Hee-Sang;Choi, Man-Yong;Park, Jeong-Hak;Lee, Jea-Jung;Kim, Won-Tae;Lee, Bo-Young
    • 비파괴검사학회지
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    • 제32권3호
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    • pp.284-290
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    • 2012
  • Infrared thermography uses infrared energy radiated from any objects above absolute zero temperature, and the range of its application has been constantly broadened. As one of the active test techniques detecting radiant energy generated when energy is applied to an object, ultrasound infrared thermography is a method of detecting defects through hot spots occurring at a defect area when 15~100 kHz of ultrasound is excited to an object. This technique is effective in detecting a wide range affected by ultrasound and vibration in real time. Especially, it is really effective when a defect area is minute. Therefore, this study conducted thermography through lock-in signal processing when an actual defect exists inside the austenite STS304 seamless pipe, which simulates thermal fatigue cracks in a nuclear power plant pipe. With ultrasound excited, this study could detect defects on the rear of a pipe by using an aluminium reflector. Besides, by regulating the angle of the aluminium reflector, this study could detect both front and rear defects as a single infrared thermography image.

사각면 코너 큐브 재귀 반사체의 반사출력광 특성 및 응용 (Analysis of the Reflection Characteristics of a Rectangular Corner Cube Retro-Reflector)

  • 정용범;김영훈;오범환
    • 한국광학회지
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    • 제26권1호
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    • pp.17-22
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    • 2015
  • 재귀 반사체(Retro Reflector)는 그 반사특성을 살려 베네치안 블라인드 슬랏, 디스플레이, 그리고 교통 안전 분야 등에서 활용 영역이 넓어져 가고 있다. 재귀 반사율 분포를 조절할 수 있는 코너 큐브 재귀 반사체를 정의하고, 입사각도에 따라 그 재귀반사광의 특성을 분석하여 교통 안전 분야에 적용하고자 하였다. 특성 분석 결과를 용이하게 파악할 수 있도록 시각화한 특성 도표를 고안하였으며, 이를 이용하여 다양한 교통 안전 분야의 재귀 반사 시트를 정량적으로 설계할 수 있음을 보였다.

도로표지병의 형태 및 기능 개선에 관한 연구 (A Study on Improvement of the Shape and Performance of Raised Pavement Marker)

  • 김상범;권용석
    • 한국안전학회지
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    • 제21권6호
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    • pp.82-87
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    • 2006
  • The existing raised pavement marker, however, have some limitations. Most of them are square-shaped which makes only forward and backward retro-reflection, their orientation can be easily changed by impact of vehicle, and the surface reflector can be readily contaminated leading poor functioning. In addition, maintenance for broken raised pavement marker is not easy. The purpose of the study is to design and manufacture a new and improved type of raised pavement marker. The new raised pavement marker has round-shaped upper structure. Its body was separated from the holder and the reflector was surrounded by acrylic cover. We tested performances of the constituent parts, optimum load after installation, and reflection efficiency. The new raised pavement marker will be an initiation of studies on the improvement of the shape and performance of raised pavement markers.

Feasibility study of corner reflector for radar countermeasures and deception for conventional forces

  • Kang, Hee-Jin;Yang, Hyang-Kweon;Jo, Min-Chul;Kim, Kook-Hyun
    • Journal of Advanced Marine Engineering and Technology
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    • 제41권2호
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    • pp.171-175
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    • 2017
  • The high-tech large warships are minimal and they are always monitored by opponents, and become primary targets when conflicts occur. The improvement in reducing susceptibility has significant importance because it is difficult for a ship to maintain mission capability and functionality once it is damaged. Ordinary decoys are effective only under the premise that the ship has already been exposed. Traditionally, for naval vessels, techniques related to the radar have been used in military stealth techniques to ensure confidentiality. The corner reflector, on the other hand, can produce rather large radar cross sections. Continued use of deceptive systems such as chaff during operations will help to improve survivability of naval ships. From this viewpoint, corner reflector was considered for making radar countermeasures and deception technology. This paper reviews the current status of corner reflector basis decoys and the technical feasibility of corner reflectors for developing structural decoys.

해상 안전을 위한 X밴드 능동형 레이더 반사기에 관한 연구 (A Study on the X-Band Active Radar Reflector for safety at the Sea)

  • 정종혁;김남호;양규식
    • 한국정보통신학회논문지
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    • 제3권4호
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    • pp.849-858
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    • 1999
  • 여러 가지 형태의 수동 레이더 반사기가 사용되고 있지만, 해양의 악조건 즉, 파도의 높이나 해풍의 속도에 견뎌내기 위한 크기는 한정되어질 수밖에 없으므로 유효 반사 단면적은 제한되어질 수밖에 없다. 따라서, 저전력, 저가격으로 응답의 신뢰성를 높일 수 있는 능동장치의 필요성을 검토하게 되었다. 능동형 레이더 반사기는 마이크로웨이브 증폭기와 분리된 송수신 안테나로 구성되고 수신된 레이더 신호를 자동적으로 증폭해서 재전송한다. 해상의 악조건에서도 소형선박이나 항해표지에 대한 레이더 응답의 명확성을 개선시키므로, 해상항해에서의 안전성을 직접적으로 증가시킬 것이다.

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비분산적외선 CO2 센서를 위한 DBR기반의 패브리 페로-필터 설계 및 성능 연구 (Design and performance study of fabry-perot filter based on DBR for a non-dispersive infrared carbon dioxide sensor)

  • 도남곤;이준엽;정동건;공성호;정대웅
    • 센서학회지
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    • 제30권4호
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    • pp.250-254
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    • 2021
  • A highly sensitive and selective non-dispersive infrared (NDIR) carbon dioxide gas sensor requires achieving high transmittance and narrow full width at half maximum (FWHM), which depends on the interface of the optical filter for precise measurement of carbon dioxide concentration. This paper presents the design, simulation, and fabrication of a Fabry-Perot filter based on a distributed Bragg reflector (DBR) for a low-cost NDIR carbon dioxide sensor. The Fabry-Perot filter consists of upper and lower DBR pairs, which comprise multilayered stacks of alternating high- and low-index thin films, and a cavity layer for the resonance of incident light. As the number of DBR pairs inside the reflector increases, the FWHM of the transmitted light becomes narrower, but the transmittance of light decreases substantially. Therefore, it is essential to analyze the relationship between the FWHM and transmittance according to the number of DBR pairs. The DBR is made of silicon and silicon dioxide by RF magnetron sputtering on a glass wafer. After the optimal conditions based on simulation results were realized, the DBR exhibited a light transmittance of 38.5% at 4.26 ㎛ and an FWHM of 158 nm. The improved results substantiate the advantages of the low-cost and minimized process compared to expensive commercial filters.

차량 탑재형 안테나 포지셔너의 반사판 지지대 최적설계 (Design Optimization of the Support Frame of an Antenna Positioner Mounted on a Vehicle)

  • 장태호;김영식
    • 한국정밀공학회지
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    • 제31권5호
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    • pp.411-416
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    • 2014
  • In this research we present design optimization methods for a vehicle-mounted satellite antenna positioner. Our initial antenna positioner was conservatively designed to satisfy a worst case scenario where wind blew across the positioner at the speed of 120 km/h. Investigating stresses and safety based on Finite Element Methods (FEM), we find reflector support frames can be optimized to significantly reduce the weight of the positioner system. Thus, we optimize the reflector support frame from the given initial design while considering weight, maximum stress, maximum allowable deflection, cross section, and thickness. As a result, Shape C and the thickness of 2 mm are determined for the cross section of the reflector support frame. Applying this result, the weight of the new antenna positioner is 57.343 kg, which is decreased by 10.74% compared to the initial conservative design.

연소실 직접분사식 성층급기 가솔린기관의 구동안정성에 관한 연구 -열방출율과 도시평균유효압력 변동에 미치는 연료분사압력과 부하변동의 영향- (A Study on Driving Stability of In-cylinder Direct Injection Stratified Charge Gasoline Engine - Effects on HR rate and $COV_{imep}$ of Fuel Injection Pressure and Load Variations -)

  • 이상만;이근오
    • 한국안전학회지
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    • 제13권3호
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    • pp.3-10
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    • 1998
  • In general, the stratified charge for direct injection gasoline engine should be introduced to achieve ultra-lean combustion scheme. In order to apply the concept of stratified charge into direct injection gasoline engine, a reflector was adapted on cylinder head. An installation of the reflector in front of the injector nozzle leads the mixture to be rich near spark plug. Therefore, the mixture near the spark plug is locally ich to ignite while the lean mixture is wholly introduced into the combustion chamber. In this paper, the characteristics of combustion is analyzed with the variations of injection pressure and load in a stratified-charge direct injection single cylinder gasoline engine.

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