Sound transmission analysis of plate structures using the finite element method and elementary radiator approach with radiator error index

Jung, Jaesoon,Kook, Junghwan,Goo, Seongyeol,Wang, Semyung Elsevier 2017 Advances in engineering software Vol.112 No.-

<P><B>Abstract</B></P> <P>In this paper, an accurate and efficient numerical method for sound transmission analysis is presented. As an alternative to conventional numerical methods, such as the Finite Element Method (FEM), Boundary Element Method (BEM) and Statistical Energy Analysis (SEA), the FE-ERA method, which combines the FEM and Elementary Radiator Approach (ERA) is proposed. The FE-ERA method analyzes the vibrational response of the plate structure excited by incident sound using FEM and then computes the transmitted acoustic pressure from the vibrating plate using ERA. In order to improve the accuracy and efficiency of the FE-ERA method, a novel criterion for the optimal number of elementary radiators is proposed. The criterion is based on the radiator error index that is derived to estimate the accuracy of the computation with used number of radiators. Using the proposed criterion a radiator selection method is presented for determining the optimum number of radiators. The presented radiator selection method and the FE-ERA method are combined to improve the computational accuracy and efficiency. Several numerical examples that have been rarely addressed in previous studies, are presented with the proposed method. The accuracy and efficiency of the proposed method are validated by comparison with the results of the three dimensional (3D) FEM structure-acoustic interaction models.</P> <P><B>Highlights</B></P> <P> <UL> <LI> An efficient and accurate numerical method (i.e. FE-ERA method) is proposed to compute the sound transmission loss. </LI> <LI> The FE-ERA method combines the finite element method (FEM) and elementary radiator approach (ERA). </LI> <LI> The radiator error index is derived to estimate the accuracy of the computation using ERA. </LI> <LI> The accuracy and efficiency of the FE-ERA method are further improved using radiator error index. </LI> <LI> The results of several numerical examples validate the accuracy and efficiency of the FE-ERA method. </LI> </UL> </P>

와이베이즈 분석을 통한 건설기계용 라디에이터의 내구성 평가

박태국(Tae-Kook Park),장무성(Mu-Seong Chang),성백주(Baek-Ju Sung),최병오(Byung-Oh Choi),양청광(Cheong-Kwang Yang) 대한기계학회 2014 대한기계학회 춘추학술대회 Vol.2014 No.11

The radiator emits high-temperature heat generated in the engine. The aluminum radiator that is light-weighted and has an excellent heat transfer is used for high efficiency engines. The aluminum radiator was introduced in the construction equipment in the late 2000s, and since then the reliability of radiator has been improved by the efforts of manufacturers. The radiator is exposed to a high temperature when the engine is running and to a low temperature when the engine stops. The radiator is failed by the fatigue due to the cyclic expansion and contraction. In this paper, we estimate a reliability parameter for the radiator by performing the life test with the thermal shock by alternatively circulating high temperature fluid and low temperature fluid directly to the radiator. And the durability of the improved radiator is evaluated using a Weibayes analysis.

Establishment of the Monoenergetic Fluorescent X-ray Radiation Fields

Chang,Si-Young,Kim,Bong-Hwan,Kim,Jang-Lyul,Lee,Jae-Ki 대한방사선 방어학회 1998 방사선방어학회지 Vol.23 No.1

한국원자력연구소 교정시설에 설치되어 있는 MG325 X-선 발생장치와 ISO-4037에서 제시하고 있는 라디에이터 및 필터 8종을 조합하여 8.6 keV 까지의 단일 에너지 형광 X-선을 제작하였다. 1차 X-선에 의하여 라디에이터에서 발생된 형광 X-선중 K를 필터를 사용하여 제거한 후 단지 K만의 형광 X-선 스펙트럼을 고순도 평판형 반도체검출기와 휴대용 다중파고분석기로 분석하였으며 35 cc 전리함을 이용하여 이때의 선량률 (air kerma rates)를 측정하여 계산결과와 비교하였다. 또한 방사선장의 균일도분포를 전리함과 사진현상을 통하여 결정하였으며, 산란 X-선의 영향도 측정하여 실제 적용가능성을 검토하였다. 실험결과 순도가 90% 이상되는 8.6 keV 부터 75 keV 까지의 단일에너지 형광 X-선을 얻었으며 라디에이터 중심으로부터 43 cm 위치에서의 선량률은 1.91 mGy/h(라디에이터 : Au, 필터 : W)로 부터 54.2 mGy((라디에이터 : Mo, 필터 : Zr) 까지였다. 선량률은 측정지점에서 방사선장의 유효면적은 12 cm ×12 cm로 계측기의 교정이나 개인선량계의 조사에 전혀 문제가 없음을 확인하였고 산란방사선의 영향도 3% 이하였다. Using a combination of an X-ray generator installed radiation calibration laboratoryof Korea Atomic Energy Research Institute (DAERI) and a series of 8 radiators and filters described in ISO-4037, moneoenergetic fluorescent X-ray from 8.6 keV to 75 keV were produced. This fluorescent X-rays generated by primary X-rays from radiator were discriminated K lines with the aid of filter material and the only K X-rays were analyzed with the high purity Ge detector and portable MCA. The air kerma rates were measured with the 35 cc ionization chamber and compared with the calculationa results, and the beam uniformity and the scattered effects of radiation fields were also measured. The beam purities were more than 90 % for the energy range of 8.6 keV to 75 keV and the air kerma rates were from 1.91 mGy/h (radiator : Au, filter : W) to 54.2 mGy (radiator : Mo, filter : Zr) at 43 cm from center of the radiator. The effective area of beam at the measurement point of air kerma rates was 12 cm ×12 cm and the influence of scattered radiation was less than 3 %. The fluorescent X-rays established in this study could be used for the determination of energy response of the radiation measurement devices and the personal dosemeters in low photon energy regions.

MEMS 기반 가변 방사율 라디에이터의 광학 물성치 최적화 설계

하헌우,한성현,이창욱,김태규,오현웅 한국항공우주학회 2014 한국항공우주학회 학술발표회 논문집 Vol.2014 No.11

기존의 MEMS 기반 루버 및 셔터 개폐형 가변 방사율 라디에이터는 온도 조건에 따라 방사율이 변하여 효율적인 열 제어가 가능하나 발사 환경에서의 기계적 구동부의 취약점과 변경된 방사율 유지를 위해 지속적인 전력 소모가 요구되는 단점을 갖는다. 본 연구에서 제안한 MEMS 기반 가변 방사율 라디에이터는 대전되는 비드를 사용하여 전극의 극성 변화에 따라 방사율 가변이 가능하기 때문에 상기의 문제점을 극복할 수 있다. 본 연구에서는 MEMS 기반 가변 방사율 라디에이터의 광학 물성치 최적화 설계를 수행하였으며, 고정 방사율 라디에이터와의 비교를 통해 MEMS 기반 가변 방사율 라디에이터의 유효성을 입증하였다. Conventional MEMS-based louver & shutter variable emissivity radiator makes it possible to control heat effectively since emissivity changes depending on temperature conditions, but requires constant power consumption to sustain the altered emissivity along with weak points of the mechanical part in launch environment. Through the MEMS-based variable emissivity radiator proposed by this study, it is possible to overcome the problem above since this new radiator can vary the emissivity, depending on the polarity change of electrodes, by using beads that can be charged. This study carried out a design of optimizing the optical properties of this radiator, and by comparing it with a fixed emissivity radiator, this study verified the effectiveness of this radiator.

염화칼슘에 의한 라디에이터 엔드 탱크 크랙에 대한 실험적 고찰

한정완(Jeongwan Han),임진석(Jinseok Lim) 한국자동차공학회 2009 한국자동차공학회 학술대회 및 전시회 Vol.2009 No.11

Radiator end tank made with PA66 is cracked under very low stress when end tank is exposed to de-icing products especially CaCl₂. This phenomenon is called as ESC (Environment Stress Cracking). The effect of radiator internal and external conditions and tank shape on radiator tank crack by CaCl₂ is studied in this paper. Down flow type radiator is more vulnerable than cross flow radiator. Lots of CaCl₂ accelerate the end tank crack.. And no coolant is in the radiator, no crack was found.

차체 라디에이터그릴의 형상에 따른 공기 유동해석

조재웅(Jae-Ung Cho),한문식(Moon-Sik Han) 한국기계가공학회 2013 한국기계가공학회지 Vol.12 No.3

This study is investigated on flow analysis according to grill configuration of radiator. The stream of flow which pass through radiator grill in car body and the contour of pressure distribution are estimated by the basis. As the magnitude of resistance force which flow affects the car body is investigated so that the power reduction can be reduced. As the pressure inside radiator grill is assessed, more efficiency can be investigated in order that the flow rate inside car body can be increased. Model 2 has the most air resistance and model 1 has the least among model 1, 2 and 3. Model 1 has the most air flow rate at inside. There are model 3 and 2 simulated according to flow rate. As the curved surface at radiator grill configuration increases in number, air flow rate becomes distributed uniformly. By considering the effect on air resistance and air flow rate at radiator grill, model 3 becomes the most effective configuration.

CNT/PVDF 복합막을 이용한 유연소자용 안테나 방사체

김용진,임영택,이선우,Kim, YongJin,Lim, Young Taek,Lee, Sunwoo 한국전기전자재료학회 2015 전기전자재료학회논문지 Vol.28 No.3

In this paper, we fabricated flexible antenna radiator using the CNT/PVDF (carbon nanotube / polyvinylidene fluoride) composite film. We used polymer film as a matrix material for the flexible devices, and introduced CNTs for adding conductivity into the film resulting in obtaining performances of the antenna radiator. Spray coating method was used to form the CNT/PVDF composite radiator, and pattern formation of the radiator was done by shadow mask during the spray coating process. We investigated the electrical properties of the CNT/PVDF composite films with the CNT concentration, and also estimated the radiator performance. Finally we discuss the feasibility of the CNT/PVDF composite radiator for the flexible antenna.

전기력을 이용한 MEMS 가변 방사율 라디에이터의 성능 검증

한성현,강수진,오현웅,김태규 한국항공우주학회 2015 한국항공우주학회 학술발표회 논문집 Vol.2015 No.11

기존의 MEMS 기반 루버 및 셔터 가변 방사율 라디에이터는 온도 조건에 따라 방사율이 가변되어 효율적인 열 제어가 가능하나 발사 환경에서의 기계적 구동부의 취약점 과 변경된 방사율 유지를 위해 지속적인 전력 소모가 요구되는 단점을 갖는다. 본 연구에서 제안한 MEMS 기반 가변 방사율 라디에이터는 대전되는 실리콘 파우더를 사용하여 전극의 극성변화에 따라 방사율 가변이 가능하기 때문에 상기의 문제점을 극복할 수 있다. 본 연구에서는 MEMS 기반 가변 방사율 라디에이터의 성능 시험을 통하여 MEMS 기반 가변 방사율 라디에이터의 유효성을 입증하였다. Recently, MEMS-based louver and shutter variable emissivity radiators have been developed to achieve the efficient thermal control by varying their emissivity according to the temperature condition. However, they are still problematic to be applied for space missions because they consume the power continuously to maintain the intended emissivity and their actuating parts are weak in terms of the mechanical strength. In this study, to overcome above drawbacks, we proposed a MEMS-based variable emissivity radiator, which can change the emissivity property according to the polarity change of electrodes by using electric charge of the silicon powder. In this study, the effectiveness of the performance tested the MEMS-based variable emissivity radiator.

라디에이터 팬의 재질에 따른 열 내구성 해석

한문식(Moonsik Han),조재웅(Jaeung Cho) 한국생산제조학회 2013 한국생산제조학회지 Vol.22 No.5

In this study, the temperature, heat emission per unit time, and thermal stress or deformation of a radiator fan made of polyethylene or aluminum are analyzed for investigating its strength durability. Heat transfer in the case of the aluminum radiator fan is better than that in the case of the polyethylene radiator fan. Further, heat emission in the case of the aluminum fan is poorer than that in the case of the polyethylene fan. Moreover, because the thermal deformation of aluminum is much smaller than that of polyethylene, the thermal durability of the aluminum fan is better than that of the polyethylene fan. In an open space in front of the radiator and the closed space of the engine behind it, the thermal cooling effect of the polyethylene fan is better than that of the aluminum fan. Further, since polyethylene is lighter in weightthan aluminum, polyethylene, as a nonmetallic plastic, is more suitable as a material of an automotive radiator. However, because of the higher strength durability of the aluminum fan, it is better than the polyethylene fan under high-temperature conditions or in the case of a complex pipe.

라디에이터 헤더 형상에 따른 열싸이클 내구성에 대한 연구

정성우(Seong Woo Jeong),김혁(Hyuk kim),김재용(Jae yong Kim),이상옥(Sang ok Lee) 한국자동차공학회 2014 한국자동차공학회 학술대회 및 전시회 Vol.2014 No.11

Recently internal combustion engine’s efficiency has been improved dramatically from customer’s demand that is to get car of good fuel efficiency. For this reason, customers are requesting the development of lightweight and highperformance heat exchanger. As part of this effort, research and experiments have been conducted on the thickness reduction of the radiator tube in order to satisfy the light weight of the heat exchanger. Thereby radiator tube thickness is a tendency to have become thinner and thinner. It is a great advantage in the design of lightweight radiator. However, it is possible to decrease in durability occurring material becomes thinner. The thickness of the material is determined to be the most important elements of the thermal cycle test. Particularly thermal expansion and contraction of the length of the tube is different from the conventional materials, It could be possible to adversely affect the thermal cycle durability life. This paper has been started to improve the radiator thermal cycle durability by changing shape of the header without changing the thickness of the radiator tube to compensate for thermal cycle durability that may be disadvantageous for thinning of the tube material.