• 수산해양기술연구
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• 제38권2호
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• pp.101-109
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• 2002

본 논문에서 알루미늄 하니콤 샌드위치판 구조(AHSP)의 특성에 대해 해석한 결과는 다음과 같다. 1) AHSP의 H/T비가 낮아질수록 응력이 감소하며, 셀 크기(H)보다는 코어의 두께(T)가 두꺼워질수록 강도와 강성이 증가함을 알 수 있다. 2) AHSP 구조가 동일한 질량에서부터 증가하면서 EASP 구조에 비해 2.5～6.0배 정도의 높은 강도를 보이는 것을 알 수 있다. 3) AHSP의 면재의 두께변화는 AHSP 전체의 강성에 별로 영향을 미치지 못했으나, 심재의 두께가 증가할수록 단면 2차 모멘트의 값이 커지기 때문에 AHSP의 강성이 매우 커짐을 알 수 있다. 4) EASP보다 강성이 큰 AHSP의 고유진동수가 크며, 진동 모드 사이의 차도 커짐을 알 수 있다. 5) 비교연구 결과 AHSP 구조가 EASP 구조보다 적은 질량으로 훨씬 더 높은 강성을 갖는, AHSP 구조의 우수성이 입증된다. 따라서 중량경감이 가장 중요한 문제 중의 하나인 초고속선 및 대형선의 경우 AHSP 구조가 높은 굽힘강성을 갖고 다른 재료에 비해 상대적으로 적은 중량이 필요하므로 구조 재료로서의 적합성을 알 수 있다.

• 한국표면공학회지
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• 제36권5호
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• pp.406-412
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• 2003

FT-IR and thermography were used to investigate the infrared radiation characteristic of SiO$_2$ film and SiO$_2$/Fe$_2$O$_3$film coated on aluminum. Through FT-TR spectrum, SiO$_2$film showed high infrared absorption in accordance with the stretching vibration of Si-O-Si, and as$ Fe_2$$O_3$was mixed additional absorption band appeared resulting from the stretching vibration of Fe-O at $590cm^{-1}$ and the bond of Si-O-Fe at $900 cm^{-1}$ The two kinds of film measured by the integration method and the reflective method coincided with each other in the wavelength area of infrared absorption and radiation, and corresponded well with Kirchhoff's law as the infrared emissivity is high in wavelength where infrared absorption rate is high. The emissivity of $SiO_2$ film was 0.65 and that of $SiO_2$/Fe$_2$$O_3$film was 0.77, so the addition of$ Fe_2$$O_3$ raised the infrared emissivity by approximately 13%.$ SiO_2$$Fe_2$$O_3$ film is efficient as an infrared radiator at below $100^{\circ}C$. The temperature of heat radiation after 7 minutes was 117$^{\circ}C$ in aluminum plate and $155^{\circ}C$ in $SiO_2$$Fe_2$$O_3$ film, $38^{\circ}C$ higher than the former.

• 한국구조물진단유지관리공학회 논문집
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• 제17권5호
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• pp.136-145
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• 2013

최근 발생한 대규모 지진으로 구조물의 내진보강에 대한 사회적 관심도가 높아지고 있다. 특히 내진 설계가 반영되지 않은 기둥은 취성적인 파괴로 구조물 전체붕괴를 유발하기 때문에 내진보강이 적용 되어야한다. 과거에는 단면증설법, 강판보강법등이 주로 적용되었고 최근에는 복합재료의 장점을 이용한 섬유보강법이 선호되고 있다. 그러나 이러한 보강법들은 구조물의 물리적 손상을 유발하며, 작업공간과 시간소비가 크다는 단점이 있다. 본 연구에서는 기존 보강법의 단점을 보강하여 복합재료 (Fiber reinforced polymer)와 Aluminum 체결부 이용한 FRP 내진보강재를 개발하였다. 비선형 유한요소 해석프로그램을 통해 개발된 FRP 내진보강재의 최적 보강량을 결정하였다.

• 한국기계가공학회지
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• 제20권5호
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• pp.69-75
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• 2021

Fuel economy has always been a major issue for the automotive industry due to environmental concerns. In particular, it is known that only 5-20% of the energy generated in a car that mainly uses an internal combustion engine is converted to increase fuel efficiency, many methods have been proposed. Among these methods, weight reduction is most commonly used because it is the simplest and cheapest. Weight is always the main reason for energy consumption, therefore, reducing weight is the best way to increase fuel efficiency while simultaneously saving on material costs. To reduce the weight of a compressor, material substitution is used. However, aluminum (a lighter metal substitute) is more fragile than steel, therefore, structural stability must be verified through testing. In this paper, we performed a 3D analysis to investigate whether aluminum can be used without compromising structural stability. Our investigation included static analysis and thermal analysis. As a result, we found that an aluminum swash plate can be safely applied on a shaft instead of steel; it reduces weight while maintaining stability that is equal to or better than steel.

• Structural Engineering and Mechanics
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• 제83권5호
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• pp.693-707
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• 2022

Bonded joints have proven their performance against conventional joining processes such as welding, riveting and bolting. The single-lap joint is the most widely used to characterize adhesive joints in tensile-shear loadings. However, the high stress concentrations in the adhesive joint due to the non-linearity of the applied loads generate a bending moment in the joint, resulting in high stresses at the adhesive edges. Geometric optimization of the bonded joint to reduce this high stress concentration prompted various researchers to perform geometric modifications of the adhesive and adherends at their free edges. Modifying both edges of the adhesive (spew) and the adherends (bevel) has proven to be an effective solution to reduce stresses at both edges and improve stress transfer at the inner part of the adhesive layer. The majority of research aimed at improving the geometry of the plate and adhesive edges has not considered the effect of temperature and water absorption in evaluating the strength of the joint. The objective of this work is to analyze, by the finite element method, the stress distribution in an adhesive joint between two 2024-T3 aluminum plates. The effects of the adhesive fillet and adherend bevel on the bonded joint stresses were taken into account. On the other hand, degradation of the mechanical properties of the adhesive following its exposure to moisture and temperature was found. The results clearly showed that the modification of the edges of the adhesive and of the bonding agent have an important role in the durability of the bond. Although the modification of the adhesive and bonding edges significantly improves the joint strength, the simultaneous exposure of the joint to temperature and moisture generates high stress concentrations in the adhesive joint that, in most cases, can easily reach the failure point of the material even at low applied stresses.

• 한국지진공학회논문집
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• 제10권6호
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• pp.125-132
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• 2006

본 논문에서는 사회기반시설의 손상탐지를 위한 경 방향모드 압전 오실레이터의 가능성을 연구하였다. 경 방향 모드 오실레이터 센서는 구조물의 주요부에 부착된 경 방향 모드 압전소자와 피드백 오실레이터 회로로 구성되어있다. 구조물의 손상은 구조물의 임피던스를 변화를 야기 시키며, 그 결과로 구조물의 공진 주파수가 변화하게 된다. 오실레이터 센서는 간단한 방법으로 이 공진 주파수 변화를 연속적으로 관측할 수 있다. 본 연구에서는 알루미늄 시편에 크랙의 크기와 개수를 인위적으로 변화 시키면서, FEM해석과 실험을 통해 경 방향 모드 압전 오실레이터 센서의 적용 가능성을 증명 하였다.

• 설비공학논문집
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• 제24권1호
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• pp.45-50
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• 2012

The plate fin and tube type of heat exchanger is widely used in air conditioner, and the heat exchanger is assembled by the mechanical expansion of copper tubes and fastening the aluminum fin. The objective of the present study is to investigate how the mechanical expansion of copper tube affects on the heat transfer performance of a plate fin and tube type heat exchanger. This study has been performed by experimental and numerical methods. The numerical and experimental results show that the tube expansion ratio has a influence on the heat transfer performance. Within the tested expansion ratio, the contact pressure shows the peak value and it decreases as the expansion ratio increases. Air-side heat transfer coefficient increases until the expansion ratio reaches 1.23, and then decreases with the similar pattern to the contact pressure. Also, contact heat transfer coefficient shows the maximum when the contact pressure is highest as well as the air-side heat transfer coefficient.

• International journal of advanced smart convergence
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• 제2권2호
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• pp.19-22
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• 2013

As the demand of the LED for lighting that emits light by p-n junction is increasing, studies on heatproof plate technology is being conducted to minimize the temperature of the LED lighting. As for the temperature of the LED devices, their light emitting efficiency decreases and the maximum lifespan drops down to 1/5. Therefore there are heat dissipation studies going on to minimize the heat. For LED heat dissipation, aluminum heat sink plates are mostly used. For this paper, we designed heat sink that fits residential 20W COB LED Down Light; packaged the heat sink and 20W COB and analyzed and evaluated the thermal properties through a Solidworks flow simulation. We are planning to design the optimal heat sink plate to solve the thermal agglomeration considering TIM(Thermal Interface material).

• 한국산업융합학회 논문집
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• 제20권3호
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• pp.221-232
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• 2017

In this study, bipolar plates in fuel cells are formed using rubber forming process. The effects of important parameters in rubber forming such as hardness and thickness of rubber pad, speed and pressure of punch that compress blank, and physical property of materials on the channel depth were analyzed. In the soft material sheet Al1050, deeper channels are formed than in materials STS304 and Ti-G5. Formed channel depth was increased when hardness of rubber pad was lower, thickness of rubber pad was high, and speed and pressure of punch were high. It was found the deepest channel was achieved when forming process condition was set with punch speed and pressure at 30 mm/s and 55 MPa, respectively using rubber pad having hardness Shore A 20 and thickness 60 mm. The channel depths of bipolar plates formed with Al1050, STS304 and Ti-G5 under the above process condition were 0.453, 0.307, and 0.270 mm, respectively. There were no defects such as wrinkle, distortion, and crack found from formed bipolar plates.

• 대한기계학회논문집A
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• 제22권3호
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• pp.688-694
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• 1998

The ability to locate the defects in materials is one of the major attrations of the acoustic emission(AE) technique. The most conventional method for planar AE source localization is to place three or more AE sensors on the plate and to determine the source position by measuring the differences in the arrival times of the AE wave at the sensors, which is called as triangulation method. But this method can not be applied in the material of which elastic wave propagtion velocity is not known. In this paper, we propose two methods, vector method and error minimization method, for AE source location on the material with unknown AE wave velocity. In this method, it is not needed to know the propagation velocity previously, that is, we can apply this method to arbitrary material of which properties are not known exactly. Also, in this paper, the robustness to the error in the measurement of time differences are discussed for both methods. Finally, in order to evaluate the actual performances, experiments using a pencil lead break as the AE source were carried out on the aluminum plate.