The laser power has been continually increased since the laser was developed in the mid-20th century. Achieving higher laser power requires not only enhancing the cooling performance of laser systems but also addressing the potential degradation of optical characteristics due to thermal deformation induced by laser beam absorption in a mirror. This study delves into the thermal deformation characteristics of mirrors in high-power laser systems. To minimize thermal deformation by heat absorption, Zerodur, known for its low coefficient of thermal expansion, was employed as the mirror material. Various configurations including circular, rectangular, and spline shapes were implemented on a solid mirror structure. Furthermore, two different diameter of a mirror, 300mm and 400mm, were considered to investigate the size effect of the high-power laser beams. Also, three different transmitted beam power were adopted: 50W, 250W, and 500W. Based on the finite element analysis for the thermal deformation, the deformation characteristics of the different types of mirror structures were investigated and analyzed for high-power laser systems.

Radiant tubes heat exchangers are critical components that facilitate the heat transfer process to steel in an annealing furnace, and it addresses several engineering problems, such as thermal stress and mechanical failure due to long-term thermal cycling, which can significantly affect the longevity of the tubes and maintenance requirements. In this study, we used commercial software (ANSYS) to simulate the thermal stress and deformation of radiant tubes subjected to extreme thermal conditions and pressure loads. We evaluated both thermally induced deformation and creep deformation, which is a time-dependent deformation under constant stress over the long term. The results showed that uneven temperature conditions and pressure loads lead to significant deformation and potential failures. To mitigate these engineering challenges, we also tested several designs that include supporting brackets. This study provides valuable insights for designing radiant tube heat exchangers in annealing furnaces to extend their lifespan and ensure system safety.

The wastegate valve regulates the maximum boost pressure inside the turbocharger to prevent damage to the engine and turbocharger which can occur from overload. However, even though the opening and closing behaviors of the valve should be controlled accurately, thermal deformations of the turbocharger system can lead to excessive distortion of the actuator rod, which can have a significant effect on the turbocharger performance. In this study, thermal deformation analysis of the turbocharger assembly has been analyzed through finite element analysis under operation condition. The result shows that the deformation in the turbine housing is relatively large and actuator rod is bent by thermal load. It causes rotational deformation at the wastegate valve face connected to the rod. And it is efficient to increase the stiffness of the EWGA rod to minimize the rotational deformation of the valve face. It means that the actuator rod should be placed in a position close to the center of the turbocharger to minimize the length of the rod that has the greatest effect on stiffness enhancement.

Mineral filler is used for resin compounds, because it increases the stiffness and thermal stability of a resin compound, and it also cuts down the cost. Calcium carbonate, silica, magnesium oxide, and others are used as filler materials in general, and the type of filler material, the size, and content can affect the physical properties of compounds. Those factors also influence the viscosity of resin mixtures and the workability, and should be adjusted by changing the contents of the filler, which depends on the size. In this study, five kinds of ground calcium carbonate, which were different in size, were used to produce polyester compounds ; the physical properties were compared with the filler size and contents. The mechanical properties were measured by bending strength and tensile strength, and the heat deflection temperature was obtained for thermal stability.

절삭가공에서 가공양의 과다 및 가공부위와 형상은 절삭저항에 의한 절삭 열을 발생시키고 이 열로 인해 가공품의 정밀도에 변형을 가져온다. 절삭가공 시 공작기계에서 발생하는 오차의 40~70%는 열 변형 오차에 의해서 발생한다. 박판 박판 블레이드는 절삭 열을 받아들이는 공작물의 두께가 얇기 때문에 열 변형 오차에 쉽게 정밀도가 저하된다. 이때에 뒤틀림이 발생하면 정밀도는 매우 큰 오차를 포함하게 된다. 본 연구의 목적은 박판의 절삭가공에서 열 변형이 발생함을 예측하고 발생 부위에 따라 어떤 변형이 발생하는 지를 측정하여 파악하고자 한다. 또한, 측정된 결과를 통해 열 변형을 최소화하는 가공방법을 제시한다.

일부 소스류 제품에 사용된 스탠딩 파우치에서 전자레인 지 가열조리 시 열변형이 발견되어 이의 원인을 규명하고자 온도 변화 패턴을 조사하였다. 전자레인지로 포장된 식품 을 가열 시 포장재의 온도 변화는 식품 자체의 온도보다 높고 국소적인 온도 측정 기술을 요한다. 공시 시료로 매운 맛 닭 소스와 인도카레의 전자레인지 가열 시 포장재와 시료의 온도를 열화상 카메라, 온도센서 테이프 및 광섬유 온도계를 이용하여 측정하였다. 스탠딩 파우치 형태의 포 장은 전자레인지 가열 조리 시 내용물의 불균일한 가열이 관찰되어 특정 부위, 특히 액위선 상단과 측면 sealing layer 에 열이 집중되는 현상이 발생하였다. 열화상 카메라를 이 용한 온도 측정 방법은 식품의 표면 온도를 측정하는 제약 이 있고 실제 식품의 온도보다 낮게 측정되는 경향을 보였 다. 온도센서 테이프를 이용할 경우 200℃까지 온도까지 측정되어 전자레인지 가열 과정 중 포장재 변형 현상이 야기될 수 있는 가능성을 확인할 수 있었다. 그리고 전자레 인지 가열 시 포장재 표면의 온도 변화를 기존 광섬유 온도 계로 측정할 경우 실제 온도보다 낮게 측정되는 결과가 초래되므로, 좁은 범위에서의 hot spot의 온도 변화를 감지할 수 있는 방법으로 GaAS crystal 센서를 사용함으로서 기존 센서보다 더 민감하고 정확한 온도 측정이 가능하였다.