• Title/Summary/Keyword: Sheet heater

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A Study on Time-Dependent Optimal Heater Control for Thermoforming Using Response Surface Method (열성형 과정에서 반응면 기법을 이용한 히터의 비정상 최적제어에 관한 연구)

  • Li, Zhen-Zhe;Heo, Kwang-Su;Seol, Seoung-Yun
    • Proceedings of the KSME Conference
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    • 2007.05b
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    • pp.2528-2533
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    • 2007
  • Thermoforming is one of the most versatile and economical processes available for the manufacturing polymer products. The drawback of thermoforming is difficult to get uniform thickness of final products. For the distribution of thickness strongly depends on the temperature distribution of sheet, the adjustment of heater power is very important In this paper, an optimization study for getting uniform temperature distribution was carried out using dual optimization steps. At first, the steady state optimal distribution of heater power is searched by numerical optimization to get uniform temperature of sheet surface. In the second step, time-dependent optimal heater inputs have been found out to decrease the temperature difference through the direction of thickness using Rseponse Surface Method and D-optimal method. The optimization results show that the time-dependent optimal heater power distribution gives acceptable uniform sheet temperature in the field of forming temperature..

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Preparation of Screen Printable Conductive MoSi2 Thick Films for Ceramic Sheet Heater (Screen Printable MoSi2 도전성 Paste를 이용한 세라믹 면상 발열체 제조)

  • Kim, Bae-Yeon;Han, Dong-Bin;Jeong, Cheol-Weon
    • Journal of the Korean Ceramic Society
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    • v.47 no.4
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    • pp.319-324
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    • 2010
  • Screen printable $MoSi_2$ paste and its ceramic sheet heater were investigated. $MoSi_2$ powder without $Mo_5Si_3$ second phase, which causes so-called pest phenomena, was synthesized by SHS technique. Over glaze was also developed for preventing pest phenomenon. The maximum temperature of $MoSi_2$ ceramic heater was over $500^{\circ}C$. After several heat up and cooling cycle, the $MoSi_2$ heater reveals pest phenomenon. Conductive $MoSi_2$ paste could be used in electronic ceramics, i.e., MLCC, LTCC, HTCC, and etc.

Time-dependent Optimal Heater Control in Thermoforming Preheating Using Dual Optimization Steps

  • Li, Zhen-Zhe;Heo, Kwang-Su;Seol, Seoung-Yun
    • International Journal of Precision Engineering and Manufacturing
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    • v.9 no.4
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    • pp.51-56
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    • 2008
  • Thermoforming is one of the most versatile and economical processes available for shaping polymer products, but obtaining a uniform thickness of the final product using this method is difficult. Heater power adjustment is very important because the thickness distribution depends strongly on the distribution of the sheet temperature. In this paper, the steady-state optimum distribution of heater power is first ascertained by a numerical optimization to obtain a uniform sheet temperature. The time-dependent optimal heater input is then determined to decrease the temperature difference through the direction of the thickness using the response surface method and the D-optimal method. The optimal results show that the time-dependent optimum heater power distribution gives an acceptable uniform sheet temperature in the forming temperature range by the end of the heating process.

Defrosting Behavior of Fin-Tube Heat Exchanger with PTC Heating Sheet

  • Jhee, Sung;Lee, Kwan-Soo
    • International Journal of Air-Conditioning and Refrigeration
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    • v.9 no.1
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    • pp.29-38
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    • 2001
  • In this paper, the defrosting characteristics of a PTC heating sheet is investigated by means of a defrosting heat source for the fin-tube heat exchanger in a refrigerator The defrosting characteristics of the PTC heating sheet are examined and compared with those of a conventional electric heater experimentally. It is found that the characteristics of the water draining rate with the defrosting time show a smoothly oscillating pattern when the PTC heating sheet Is used, and the drained water is completely melted. The defrosting efficiency of the PTC heating sheet is found to be about 75%, which is about 25% higher than that of the electric heater. Also, the reduction of the defrosting time and the increment of the defrosting efficiency may be obtained by improving the arrangement of the heating elements of the healing sheet. It is shown that the defrosting time of the PTC heating sheet increases linearly with the amount of frost, whereas the defrosting efficiency is nearly constant. When applying the PTC heating sheet to the refrigerating system, one should notice the fact that the defrosting performance of the PTC heating sheet may be degraded due to the repetitive operations.

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An experimental study of defrosting behaviors on the fin-tube heat exchanger with PTC heating sheet (PTC 전열시트를 사용한 핀-관 열교환기의 제상 특성에 관한 실험적 연구)

  • Jhee, S.;Lee, K.S.
    • Korean Journal of Air-Conditioning and Refrigeration Engineering
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    • v.11 no.1
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    • pp.147-155
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    • 1999
  • In this work, the defrosting characteristics of PTC heating sheet used as a defrosting heat source of fin-tube heat exchanger in a refrigerator have been experimentally compared with those of conventional electric heater. It is found that the characteristics of water draining rate with defrosting time show smoothly oscillating pattern when PTC heating sheet is used, and the drained water is completely melted. The defrosting efficiency of the PTC heating sheet is about 75%, which represents about 25% higher than that of the electric heater. A reduction of defrosting time and an increase of defrosting efficiency may be obtained by improving the arrangement of heating elements of the heating sheet. It is shown that the defrosting time of PTC heating sheet increases linearly with the amount of frost, however the defrosting efficiency is nearly constant. In the application to the refrigerating system, one should notice the fact that the defrosting performance of PTC heating sheet may be defraded due to the repeated operations.

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Zone-Melting Recrystallization of Si Films on $SiO_2$ with a Graphite-Strip-Heater (흑연 막대 발열체를 이용한 SOI구조의 Zone-melting 재결정화 연구)

  • 김현수;김춘근;민석기
    • Journal of the Korean Institute of Telematics and Electronics
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    • v.27 no.4
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    • pp.527-533
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    • 1990
  • Zone-melting recrystallization (ZMR) system using two graphite heaters(a stationary sheet and a narrow movable bar) was constructed and implemented in recrystallization op Si films on insulating layers. The recystallized Si films were examined by Nomarski contrast optical microscopy after Dash etching, transmission electron diffraction pattern, and x-ray diffraction. With optimum conditions of process parameters(input powers of the bottom and upper heater, scanning speed of the upper heater, and the gap between sample and upper heater), the recrystallized Si layer has a (100) texture, but contains many subboundaries. The subgrains are misoriented by < 0.5\ulcorner and the average spacing between subboundaries is about 25\ulcorner.

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A Study on Risk Analysis and Acident Prevention Heater Interlock By-pass (Heater interlock by-pass로 인한 위험분석 및 사고방지에 대한 연구)

  • Son Jae-geun;Park Kyo-Shik;Kang Tae-Yeon;Yeo Yeong-Koo
    • Journal of the Korean Institute of Gas
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    • v.7 no.1 s.18
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    • pp.24-27
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    • 2003
  • In this paper it was investigated 15 heaters of CDU plant heater, NCC plant heater, CO plant heater, Aromatic plant heater and so on while running in our country. It was also analysed the standard of operation procedure, the action in alarm, the interlock system, the operating situation of the interlock by-pass and major accident about the heater and so on. This paper presents the installation of the on-line monitoring, the additional installation of the local pressure gauge and temperature gauge, the check in starting operation,'the management of the interlock by-pass, the change of manufacturer causing the disorder of instrument sensor, the management method of DCS alarm for methods of the interlock prevention and facilities improvement. It was few information about the heater interlock in the inside and outside of the country We mainly have studied with reflecting the opinion of the operator and manager on site, the sheet of process trouble and operation procedure and so on. we think that the accident relating to the interlock will significantly reduce if the companies apply the conclusion of this study(i.e. methods of the interlock prevention and facilities improvement).

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Preparation and Characterization of Cobalt Silicide Films for Printing Heater (프린팅 히터용 코발트실리사이드 박막의 형성과 특성연구)

  • 장호정;노영규
    • Journal of the Microelectronics and Packaging Society
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    • v.9 no.2
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    • pp.49-54
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    • 2002
  • Cobalt silcides thin films were prepared on Poly-Si/$SiO_2$/Si substrates by Co metal depostion using E-beam evaporation method and rapid thermal annealing for the application of inkjet printing heater. The crystal phases and composition distributions of the films were investigated as functions of the rapid thermal annealing (RTA) temperatures (600~$900^{\circ}C$) and times (20~40 sec). The high temparature thermal stability was also investigated by the analysis of sheet resistance and crystalline properties. The stable $CoSi_2$ phases were obtained by the RTA annealing at $800^{\circ}C$ for 20 seconds showing $0.8 \Omega /\Box$ of sheet resitance. However, the sheet resistances were sharply increased at below $700^{\circ}C$ due to changes of crystalline phases. The temperature resistance coefficient of heating elements was found to be about $0.0014/^{\circ}C$, and the obtained cobalt silicided films can be applied to the printer heating elements.

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Development of Control System for Transversal Temperature of Strips in Hot Strip Mills (열간압연공정에서의 스트립 폭방향 온도제어 시스템 개발)

  • Choi, Jae-Chan;Lee, Sung-Jin;Park, Bong-Su
    • Transactions of the Korean Society of Mechanical Engineers A
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    • v.20 no.4
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    • pp.1202-1215
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    • 1996
  • In this study, in order to achieve the uniformity of mechanical properties and microstructures of a hot-rolled coil in the transversal direction, the edge mask device is newly device is newly developed and installed at the upper laminar-flow cooling head in the run out table, which controls the transversal temperature of strip with enco panel and bar edge heater. The device that is transversally movable prevents the temperature drop of strip edge by blocking the cooling water into the strip edge. So, the pattern of edge mask set-up condition of the device was derived by analyzing the characteristics of strip temperature and mechanical properties according to the on-line application of edge mask.

Carbon nanotube transparent conductive film: current status and prospect

  • Han, Chang-Soo;Oh, Sang-Keun
    • 한국정보디스플레이학회:학술대회논문집
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    • 2009.10a
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    • pp.474-475
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    • 2009
  • As a substitute of ITO material, carbon nanotube (CNT) is widely studied for transparent conductive film (TCF). Current sheet resistance of CNT-TCF is about 100 ${\Omega}$/sq at 80% transmittance. But CNT-TCF performance in manufacturable level is about 500 ${\Omega}$/sq at 83% based on the Topnanosys Co's result. Therefore, critical issue in CNT-TCF research is to reduce the sheet resistance with manufacturing reliability. In this report, recent developments using CNT-TCF are introduced. Touch panel, transparent LED signboard, transparent speaker and transparent heater are representative examples. Also I describe the future issues and prospect of CNT-TCF for the flexible display.

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