• Title/Summary/Keyword: absorbers

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W/O 마이크로에멀젼 졸-겔 법을 이용한 수용성 UV 흡수제를 함유한 실리카 마이크로캡슐의 제조 (Preparation of Silica Microcapsules containing Water-Soluble UV Absorbers by a W/O Microemulsion Sol-Gel Process)

  • 함경국;안복엽;석상일
    • 한국재료학회:학술대회논문집
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    • 한국재료학회 2003년도 춘계학술발표강연 및 논문개요집
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    • pp.220-220
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    • 2003
  • The microencapsulation of droplets or particles within a solid shell leads to the formation of core-shell particles. Microencapsulation provides protection and controlled release of core materials such as drugs, vitamins, enzymes, perfumes, and the like. Such particles have, therefore, found a diverse range of applications in the pharmaceutical, agricultural, cosmetic, and food industries. UV absorbers are widely used for cosmetics to screen out ultra violet (UV) rays which have side effects on human skin. The absorbers are made generally from synthetic organic compounds, which can stimulate the human skins to develop allergic phenomena.

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레이다용 광대력형 고성능 전파흡수체의 개발에 관한 연구 (A Study on Development of High Performance Microwave Absorbers in Wide-Band Type for RADAR)

  • 김동일;안영섭;정세모
    • 한국항해학회지
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    • 제15권1호
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    • pp.1-9
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    • 1991
  • The coaxial sample holder with 20mm in diameter and the adaptor from type N connector-to-20mm${\phi}$ coaxial tube are designed and manufactured which have been used for designing and measuring the fabricated microwave absorber. In addition, the measure in method of material constants of the microwave absorbers is described, which is focused on minimizing the error due to the sample's shapes, the fitting conditions, etc. After describing the design method of a single-layed microwave absorber, the microwave absorbers for X-band, C-band and S-band RADARs are designed and fabricated, respectively, which are composed of ferrite, carborn, and binder and have good performance. Futhermore, we develop the high performance microwave absorber in extremely wide-band type for RADAR, which is composed of different material and its mixing ratio and which could cover nearly from 4 to 10 GHz.

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샌드위치 구조형 섬유강화 복합재료의 전파흡수특성 (Microwave Absorbing Properties of Fiber Reinforced Composites with Sandwitch Structure)

  • 김상영;김상수
    • 한국재료학회지
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    • 제12권6호
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    • pp.442-446
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    • 2002
  • Design of microwave absorbers using high frequency properties of fiber reinforced composites are investigated. Two kinds of composite materials (glass and carbon) are used and their complex permittivity and permeability are measured by transmission/reflection technique using network analyzer. Low dielectric constant and nearly zero dielectric loss are determined in glass fiber composite. However, carbon fiber composites show the high dielectric constant and large conduction loss which is increased with anisotropy of fiber arrangement. It is, therefore, proposed that the glass and carbon fiber composites can be used as the impedance transformer (surface layer) and microwave reflector, respectively. By inserting the foam core or honeycomb core (which can be treated as an air layer) between glass and carbon fiber composites, microwave absorption above 10 dB (90% absorbance) in 4-12 GHz can be obtained. The proposed fiber composites laminates with sandwitch structure have high potential as lightweight and high strength microwave absorbers.

십자형 슬롯을 가지는 적층형 초광대역 페라이트 전파흡수체의 설계 (Design of Super Wide-Band Electromagnetic Wave Absorbers Using Cross-Slotted Ferrite in the Double-Layered Type)

  • 김동일;전상엽
    • 한국전자파학회논문지
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    • 제7권4호
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    • pp.346-352
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    • 1996
  • 초광대역 주파수 특성을 가지며, 제2층에 십자형 슬롯을 가지는 2층형 전파흡수체의 광대역 설계법을 제안하였다 이와같은 광대역 전파흡수체는 등가재료정수법을 적용한 이론 모델을 이용하여 설계할 수 있다. 제안한 모델을 바탕으로 30MHz~3,170MHz의 주파수 범위에서 우수한 반사감쇠 특성을 가지는 초광대역 전파흡수체를 설계하였다.

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Sendust를 이용한 휴대전화용 전파흡수체의 개발 (Development of Electromagnetic Wave Absorbers Using Sendust for a Portable Phone)

  • 최정현;김동일;송재만;정재현
    • 한국마린엔지니어링학회:학술대회논문집
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    • 한국마린엔지니어링학회 2005년도 전기학술대회논문집
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    • pp.429-434
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    • 2005
  • In this paper, we investigated EM wave absorption property of EM wave absorbers prepared with sendust. The EM wave absorbers have good EM wave absorption properties in 1 GHz ${\sim}$ 3 GHz. On the other hand, the absorption band of the EM wave absorber coated with $Al(OH)_3$ larger than non-coated one. Pulverization effect of sendust on EM wave absorption properties was also investigated.

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GHz 대역용 복합형 Ba 페라이트 전파흡수체의 개발 (Development of Composite Ba Ferrite EM Wave Absorbers for GHz Frequency)

  • 문상현;신승재;송재만;김동일;김기만
    • 한국전자파학회논문지
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    • 제14권12호
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    • pp.1329-1334
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    • 2003
  • 폐 처리된 Ba 페라이트를 사용하여 GHz 대역용 전파흡수체를 개발하였다. 도전 손실재인 카본의 첨가에 따른 전파흡수능의 변화와 시편 제작시 제작온도 변화에 따른 전파흡수능의 변화를 조사하였다. 이와 같은 실험을 통하여 GHz 대역용 Ba 페라이트 전파흡수체를 개발하는데 있어 카본의 첨가가 매우 유효함을 알았으며, 시편의 제작온도 또한 우수한 전파흡수체를 개발하는데 있어 반드시 고려되어야 함을 밝혔다.

Sheet형 전파흡수체에 있어 Ferrite 입자 크기의 제어에 따른 전파흡수체의 특성 (Electromagnetic Wave Absorption of Sheet Type EM Wave Absorber by Control of Ferrite Particle Size)

  • 김동일;옥승민;김수정;박우근;송재만
    • 한국항해항만학회지
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    • 제27권1호
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    • pp.71-74
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    • 2003
  • Sheet형 전파흡수체를 제조하고 그들의 전자파 흡수 특성을 조사하였다. 제조된 ferrite 흡수체의 흡수특성은 2.4~3.2GHz의 주파수범위에서 입자크기의 감소에 따라 개선되었다.

차량충돌방지 레이더의 허상방지 대책용 전파흡수체 개발에 관한 연구 (I A Study on Development of the EM Wave Absorber for Eliminating False Image in a Collision-Avoidance Radar)

  • 최창묵;김동일;박우근;고광섭
    • 대한전자공학회:학술대회논문집
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    • 대한전자공학회 2007년도 하계종합학술대회 논문집
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    • pp.107-108
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    • 2007
  • In this paper, the EM wave absorbers were designed and fabricated for collision-avoidance radars using Carbon of a dielectric material and Permalloy of a magnetic material with CPE, because radar system has some problems including false image and system-to-system interference. We fabricated some samples in different composition ratio of Carbon and Permalloy, and defined that optimum composition ratios of Carbon and Permalloy with CPE were Carbon:CPE=20:80 wt% and Permalloy:CPE=70:30 wt%. And absorption abilities at different thicknesses of the EM wave absorbers were simulated using the material properties. The EM wave absorbers were manufactured based on the simulated design. Simulated and measured results agree very well.

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십자돌기형 전파흡수체로 구성된 전파암실의 특성평가 (A Study on the Evaluation of the Characteristics of Semi-Anechoic Chamber Constructed by the Cross-Shaped Type Electromagnetic Absorbers)

  • 김민석;김동일;전상엽;민경식
    • 한국정보통신학회논문지
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    • 제3권1호
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    • pp.51-58
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    • 1999
  • 본 논문에서는 광대역 특성의 십자돌기형 페라이트 전파흡수체로 이루어지는 전파 반무향실의 특성을 영상법에 의하여 평가하였다. 그 결과, 그리드형 전파흡수체가 3 ~ 1000 MHz의 주파수 대역폭을 가지는 데 대하여, 십자돌기형 페라이트 전파흡수체는 30 MHz ~ 3,000 MHz의 주파수 대역에서 우수한 특성을 가지는 것을 확인하였다.

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병진 및 회전 감쇠동흡진기를 사용한 보의 진동저감 (Beam Vibration Suppression with Translational and Rotational Damped Dynamic Vibration Absorbers)

  • 박성규;이시복
    • 한국소음진동공학회논문집
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    • 제26권6_spc호
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    • pp.721-728
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    • 2016
  • The combined rotational and translational dynamic vibration absorbers (DVA) with no dampers for the beam vibration control can effectively isolate the vibration within the external excitation force region. This paper investigates the damping efficacy for the combined rotational and translational dynamic vibration absorbers to impose some robustness to the DVA system for the excitation force frequency variation. The beam is assumed to be subjected to a concentrated harmonic excitation force. The solution to the problem is found based on Galerkin method.