• 대한기계학회:학술대회논문집
• /
• 대한기계학회 2003년도 춘계학술대회
• /
• pp.1736-1741
• /
• 2003

The characteristics plasma flow of an atmospheric plasma torch used for thermal plasma processing is studied. In general, it is produced by the arc-gas interactions between a cathode tip and an anode nozzle. The performance of non-transferred plasma torch is significantly dependent on jet flow characteristics out of the nozzle. In this work, the distribution of gas flow that goes out to the atmosphere through a plenum chamber and nozzle is analyzed to evaluate the performance of atmospheric plasma torch. Numerical analysis is carried out with various angles of an inlet flow which can create different swirl flow fields. Moreover, the size of plasma plume is experimentally depicted.

• 한국전기전자재료학회:학술대회논문집
• /
• 한국전기전자재료학회 2005년도 추계학술대회 논문집 Vol.18
• /
• pp.80-81
• /
• 2005

Chalcogenide phase change memory has high performance to be next generation memory, because it is a nonvolatile memory processing high programming speed, low programming voltage, high sensing margin, low consumption and long cycle duration. We have developed a sample of PRAM with thermal protected layer. We have investigated the phase transition behaviors in function of process factor including thermal protect layer. As a result, we have observed that set voltage and duration of protect layer are more improved than no protect layer.

• Food Science and Biotechnology
• /
• 제15권4호
• /
• pp.499-505
• /
• 2006

Clostridium botulinum spores are widely distributed in nature. Type A and proteolytic type B bacteria produce heat-resistant spores that are primarily involved in most of the food-borne botulism outbreaks associated with low-acid canned foods. Food-borne botulism results from the consumption of food in which C. botulinum has grown and produced neurotoxin. Growth and toxin production of type A and proteolytic type B in canned foods can be prevented by the use of thermal sterilization alone or in combination with salt and nitrite. The hazardousness of C. botulinum in low-acid canned foods can also be reduced by preventing post-process contamination and introducing hazard analysis and critical control point (HACCP) practices during production. Effectiveness of non-thermal technologies such as high pressure processing with elevated process temperatures on inactivation of spores of C. botulinum will be discussed.

• 한국광학회지
• /
• 제16권3호
• /
• pp.209-216
• /
• 2005

전차 조준경으로 사용될 수 있는 2세대 열상장비를 개발하였다. 설계된 장비는 프랑스 Sofradir사의 $480\times6$ 배열 원적외선$(7.7{\mu}m-10.3{\mu}m)$ MCT(HgCdTe) 검출기를 이용하였고, $2.67^{\circ}\times2^{\circ}$의 고배율 협시계와 $10^{\circ}\times7.5^{\circ}$의 저배율 광시계의 이중배율을 가지고 있다. 또한 넓은 운용 온도 범위에서도 시스템의 성능이 저하되지 않도록 비열화 기술을 적용하였다. 설계된 장비는 고효율의 주사장치로 47만 화소의 실시간 영상 재현이 가능하며, 이는 1세대 열상장비에 비하여 화소수가 대폭 증가한 것이다. 적외선 검출소자들의 불균일 보정을 위해서 열전 냉각 소자를 이용한 두 점 보상 기법을 제시하여 실시간 보정이 이루어지게 하였고, 열영상 분포 히스토그램 가변 방식의 처리 기법을 제안하여 적용함으로써 대조비가 매우 낮은 표적의 식별도 용이하게 하였다. 설계 및 제작된 2세대 열상장비의 고배율에서 최소분해가능온도차를 측정한 결과, 2cycles/mrad의 공간주파수에서 0.05K 이하의 우수한 결과를 보였다.

• 소성∙가공
• /
• 제14권9호통권81호
• /
• pp.751-755
• /
• 2005

This paper is concerned with spring back after sheet forming of bulk amorphous alloys in the super cooled liquid state. The temperature-dependence and strain-rate dependence of Newtonian/non-Newtonian viscosities as well as the stress overshoot/undershoot behavior of amorphous alloys are reflected in the thermo-mechanical Finite Element simulations. Hemispherical deep drawing operations are simulated for various forming conditions such as punch velocity, die comer radius, friction, blank holder force, clearance and initial funning temperature. Here, spring back by an instantaneous elastic unloading was followed by thermal deformation during cooling, and two modes of spring back are examined in detail. It could be concluded that the superior sheet formability of an amorphous alloy can be obtained by taking the proper forming conditions for loading/unloading.

• 소성∙가공
• /
• 제24권1호
• /
• pp.13-19
• /
• 2015

For an accurate analysis of hot stamping, a coupled simulation with different aspects of the process(i.e. mechanical, thermal, and phase transformation) is needed. However, coupled simulations are time consuming and costly. Therefore, the current study proposes a simplified method focused on the forming for the hot stamping simulation of a coupled torsion beam axle (CTBA) tubular beam. In this simplified method, non-isothermal conditions were assumed and only conduction was considered, since it represents the majority of the heat transfer during hot stamping. In addition, temperature and strain rate effects were also included. Moreover, an isothermal simulation was conducted and compared with a non-isothermal simulation. Finally, the simulations were verified by experiments. In conclusion, the proposed method is shown to be effective for the development of tube-type parts, and it effectively predicts the deformation of the tubular beam during hot stamping.

• Journal of the Optical Society of Korea
• /
• 제7권3호
• /
• pp.160-164
• /
• 2003

Materials processing by ultrashort pulsed laser is actively being applied to micromachining technology due to its advantages with regard to non-thermal machining. In this study, materials processing with ultrashort pulses was studied by using the high repetition rate of a 800 nm Ti:sapphire regenerative amplifier. This revealed that the highly precise micromachining of metallic thin film and bulk glass with a minimal heat affected zone (HAZ) could be obtained by using near damage threshold energy. Grooves with diffraction limited sub-micrometer width were obtained with widths of 620 nm on Cr thin film and 800 nm on a soda-lime glass substrate. The machined patterns were investigated through SEM images. We also phenomenologically examined the influence of variations of parameters and proposed the optimal process conditions for microfabrication.

• Computers and Concrete
• /
• 제19권6호
• /
• pp.701-710
• /
• 2017

In this study, the thermoelastic beam in modified couple stress theory due to laser source and heat flux is investigated. The beam are heated by a non-Guassian laser pulse and heat flux. The Euler Bernoulli beam theory and the Laplace transform technique are applied to solve the basic equations for coupled thermoelasticity. The simply-supported and isothermal boundary conditions are assumed for both ends of the beam. A general algorithm of the inverse Laplace transform is developed. The analytical results have been numerically analyzed with the help of MATLAB software. The numerically computed results for lateral deflection, thermal moment and axial stress due to laser source and heat flux have been presented graphically. Some comparisons have been shown in figures to estimate the effects of couple stress on the physical quantities. A particular case of interest is also derived. The study of laser-pulse find many applications in the field of biomedical, imaging processing, material processing and medicine with regard to diagnostics and therapy.

• 대한전기학회:학술대회논문집
• /
• 대한전기학회 2001년도 합동 추계학술대회 논문집 정보 및 제어부문
• /
• pp.450-452
• /
• 2001

In this paper, we proposed the automatic postal drop-off system based on the microprocessor board or PC. The weight of the small postal package is transmitted from the electronic scale and user-entered addresses and delivery rate are processed by the controller to calculate the fee. For 24 hour out-door operation and maintenance, non-cash payment methods such as credit card payment is used. The post stamp and receipt are printed by the thermal printer. For the electronic processing of the parcel, serial code is also printed on the stamp and receipts in bar code format. The parcel information obtained by the automatic postal drop-off system is transferred to remote central system by dial-up modem shared by the on site office. The proposed system and its control software are built for prototype model operation and the result met the design requirements. For real time processing, data reception through three serial ports is handled by interrupt routine. The proposed system is expected to be applied for commercial logistics system and pc automation system.

• KSII Transactions on Internet and Information Systems (TIIS)
• /
• 제8권10호
• /
• pp.3475-3489
• /
• 2014

Here we present a simple flame detection method for an infrared (IR) thermal camera based real-time fire surveillance digital signal processor (DSP) system. Infrared thermal cameras are especially advantageous for unattended fire surveillance. All-weather monitoring is possible, regardless of illumination and climate conditions, and the data quantity to be processed is one-third that of color videos. Conventional IR camera-based fire detection methods used mainly pixel-based temporal correlation functions. In the temporal correlation function-based methods, temporal changes in pixel intensity generated by the irregular motion and spreading of the flame pixels are measured using correlation functions. The correlation values of non-flame regions are uniform, but the flame regions have irregular temporal correlation values. To satisfy the requirement of early detection, all fire detection techniques should be practically applied within a very short period of time. The conventional pixel-based correlation function is computationally intensive. In this paper, we propose an IR camera-based simple flame detection algorithm optimized with a compact embedded DSP system to achieve early detection. To reduce the computational load, block-based calculations are used to select the candidate flame region and measure the temporal motion of flames. These functions are used together to obtain the early flame detection algorithm. The proposed simple algorithm was tested to verify the required function and performance in real-time using IR test videos and a real-time DSP system. The findings indicated that the system detected the flames within 5 to 20 seconds, and had a correct flame detection ratio of 100% with an acceptable false detection ratio in video sequence level.