• Title/Summary/Keyword: bottom temperature

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A Basic Study on Efficient Acrylic Plate Light Transmission Road Machining (효율적인 아크릴판 광전송로 가공에 관한 기초 연구)

  • Han, Su-Won;Hong, Jun-Hee
    • Journal of the Korean Society of Manufacturing Process Engineers
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    • v.21 no.1
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    • pp.95-101
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    • 2022
  • This paper proposes a method to process the shape of an optical transmission road and attempts to determine the most suitable single processing method for an acrylic plate optical transmission road. In addition, by manufacturing an automatic pattern processing device to generate certain shapes on the acrylic plate at regular intervals, and measuring the illuminance of the patterned acrylic plate optical transmission road, the measured illuminance was confirmed to fall under the KS illuminance values presented in Table 1. In conclusion, when an incident light of approximately 20,000 lx is applied, the transmission illumination is approximately 200 lx, which represents a transmission rate of approximately 1% for incident light and corresponds to the KS illumination criterion F. Additionally, the right-angle triangular pyramid base size (A) processed at a temperature of 350 ℃ for one second was 2 mm, exhibiting the largest transmission illumination of 280 lx. When the transparent acrylic plate was set to a constant size of 1.6 mm at the bottom of the right-angle triangular pyramid, the fastest response occurred at a processing tip temperature of 350 ℃ (0.04 s). On the other hand, it took 10 s to process the size of the bottom of the right-angled triangular pyramid at a temperature of 200 ℃ to 1.6 mm, and it was confirmed that the optical transmission efficiency was significantly reduced because of the burr that occurred at this time.

Sensitivity of Simulated Water Temperature to Vertical Mixing Scheme and Water Turbidity in the Yellow Sea (수직 혼합 모수화 기법과 탁도에 따른 황해 수온 민감도 실험)

  • Kwak, Myeong-Taek;Seo, Gwang-Ho;Choi, Byoung-Ju;Kim, Chang-Sin;Cho, Yang-Ki
    • The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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    • v.18 no.3
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    • pp.111-121
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    • 2013
  • Accurate prediction of sea water temperature has been emphasized to make precise local weather forecast and to understand change of ecosystem. The Yellow Sea, which has turbid water and strong tidal current, is an unique shallow marginal sea. It is essential to include the effects of the turbidity and the strong tidal mixing for the realistic simulation of temperature distribution in the Yellow Sea. Evaluation of ocean circulation model response to vertical mixing scheme and turbidity is primary objective of this study. Three-dimensional ocean circulation model(Regional Ocean Modeling System) was used to perform numerical simulations. Mellor- Yamada level 2.5 closure (M-Y) and K-Profile Parameterization (KPP) scheme were selected for vertical mixing parameterization in this study. Effect of Jerlov water type 1, 3 and 5 was also evaluated. The simulated temperature distribution was compared with the observed data by National Fisheries Research and Development Institute to estimate model's response to turbidity and vertical mixing schemes in the Yellow Sea. Simulations with M-Y vertical mixing scheme produced relatively stronger vertical mixing and warmer bottom temperature than the observation. KPP scheme produced weaker vertical mixing and did not well reproduce tidal mixing front along the coast. However, KPP scheme keeps bottom temperature closer to the observation. Consequently, numerical ocean circulation simulations with M-Y vertical mixing scheme tends to produce well mixed vertical temperature structure and that with KPP vertical mixing scheme tends to make stratified vertical temperature structure. When Jerlov water type is higher, sea surface temperature is high and sea bottom temperature is low because downward shortwave radiation is almost absorbed near the sea surface.

Eco-Friendly Backfill Materials with Bottom Ash (바톰애시를 이용한 환경친화적 뒤채움재)

  • Lee, Kwan-Ho;Kim, Seong-Kyum
    • Journal of the Korea Academia-Industrial cooperation Society
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    • v.13 no.3
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    • pp.1385-1390
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    • 2012
  • Couple of laboratory for controlled low strength materials with bottom ash and recycled in-situ soil have been carried out. The optimum mix ratios for 4 cases with flowability and unconfined compressive strength were determined. The optimim mixing ratios were 25 to 45% of insitu soil, 30% of bottom ash, 10 to 20% of fly ash, 0 to 3% of crumb rubber, 3% of cement and 22% of water. Each mixture was satisfied the standard specification, minimum 20cm of flowability and 127 kPa of unconfined compressive strength. Two different curling methods, at room temperature and wet condition, were adopted. The average secant modulus(E50) was 0.07 to 0.08 * $q_u$. The compressive strength at wet condition showed 10% larger than at room temperature. The range of internal friction angle and cohesion for mixtures were 36.5o to 46.6o and 49.1 to 180 kPa, respectively. The mixture with crumb rubber(case 4) showed higher choesion and lower internal friction angle than the others. The pH of all the mixtures was over 12 which is strong alkine.

Effects of critical viscosity temperature and flux feeding ratio on the slag flow behavior on the wall of a coal gasifier (석탄 가스화시 회분의 임계점도온도 및 플럭스 비율 변화에 따른 벽면 슬래그 거동 특성 분석)

  • Ye, Insoo;Ryu, Changkook;Kim, Bongkeun
    • 한국연소학회:학술대회논문집
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    • 2014.11a
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    • pp.21-24
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    • 2014
  • In the entrained-flow coal gasifier, coal ash turns into a molten slag most of which deposits onto the wall to form liquid and solid layers. Critical viscosity refers to the viscosity at the interface of the two layers. The slag layers play an important role in protecting the wall from physical/chemical attack from the hot syngas and in continuously discharging the ash to the slag tap at the bottom of the gasifier. For coal with high ash melting point and slag viscosity, CaO-based flux is added to coal to lower the viscosity. This study evaulates the effect of critical viscosity temperature and ash/flux ratio on the slag behavior using numerical modelling in a commercial gasifier. The changes in the slag layer thickness, heat transfer rate, surface temperature and velocity profiles were analyzed to understand the underlying mechanism of slag flow and heat transfer.

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Temperature History of Mock-up Mass Concrete Considering Different Heat Generation Due to Mixture Adjustment (수화발열량이 다른 콘크리트조합 모의부재 매스콘크리트의 온도이력 특성)

  • Kim Jong;Jeon Chung-Keun;Shin Dong-An;Yoon Gi-Won;Oh Seon-Kyo;Han Cheon-Goo
    • Proceedings of the Korean Institute of Building Construction Conference
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    • 2005.05a
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    • pp.9-12
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    • 2005
  • This paper investigated the temperature history of mass concrete mock up structure considering different heat generation by varying with mixture proportion. Setting time difference between high early strength mixture (E-P) and retarding mixture (R-F30) was 14.5hours. Incorporation of $30\%$ of fly ash contributed to $10^{\circ}C$ of hydration heat reduction. In generally used C and D combination, bottom concrete shows earlier hydration, while E-J combination showed reverse tendency and thus, this method can reduce the crack occurrence. Therefore, heat generation difference method has beneficial effect on reducing crack induced by hydration heat resulting from heat generation difference between surface and center section.

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Prediction of the Drying Time under the Various Operational Conditions using a Sublimation Model (승화 건조모델에 대한 운전방법별 건조시간의 예측)

  • 박노현;배신철
    • Transactions of the Korean Society of Mechanical Engineers
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    • v.17 no.8
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    • pp.2088-2098
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    • 1993
  • A mathematical model of freeze drying by sublimation was suggested and used to estimate the drying time. Under the various conditions, the drying time of pure water and carrot was numerically calculated for the suggested model. Optimal policies of freeze drying were investigated experimentally in a laboratory freeze dryer. It was found that the shortest drying times could be obtained when the chamber pressure and condenser temperature were kept at their lowest values and the best method of heat transfer for sublimation was the conduction involving radiation. The sublimation drying period was finished when the bottom temperature of material could be reached at near $0^{\circ}C$ from frozen temperature.

Execution of Mass Concrete for Mat Foundation Using Setting Time Difference with Super Retarding Agent for Reducing Hydration Heat (초지연제의 응결시간차 공법을 이용한 기초 매트 콘크리트의 수화열 저감 시공)

  • Jeon Chung Keun;Yoon Chi Whan;Song Seung Heon;Shin Dong An;Oh Seon Gyo;Han Cheon Goo
    • Proceedings of the Korea Concrete Institute Conference
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    • 2004.05a
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    • pp.144-147
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    • 2004
  • In this paper, field application of mass concreting using super retarding agent(SRA) are discussed based on setting. time difference with SRA in big discount market in Chongju. Mechanical and physical properties of .concrete are investigated. Temperature history of concrete is also measured. Slump and air content meet the requirement of target value. Compressive strength of concrete exceeded the nominal strength with 24MPa. Compressive strength of SRA concrete is higher than that of plain concrete by about $3\~4\%$. For temperature history, peak temperature of concrete at middle section at top concrete layer reached $49.6^{\circ}C$ within 24hours, and at bottom concrete layer, $54.6^{\circ}C$ within 42hours. Based on the naked eye's observation, no crack was found at mass concrete.

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Variations of Sea Level and Sea Surface Temperature in Korean Seas by Topex/Poseidon and NOAA

  • Yoon, Hong-Joo;Kang, Heung-Soon;Lee, Bong-Sic;Jeong, Young-Deok
    • Proceedings of the KSRS Conference
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    • v.2
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    • pp.880-883
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    • 2006
  • Altimeter(Topex/Poseidon) and AVHRR(NOAA) data were used to study the variations and correlations of Sea Level(SL) and Sea Surface Temperature (SST) in the North East Asian Seas from November 1993 to May 1998. This region is influenced simultaneously to continental and oceanic climate as the border of the East Sea(Japan Sea). SL and SST have increased gradually every year because the global warming, and presented usually a strong annual variations in Kuroshio extension region with the influence of bottom topography.

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Relationship Between Exothermic Heat and Carbon Contents of Pitch-based Carbon Fiber

  • Lee, Jae-Young;Oh, Jong-Hyun;Yang, Xiao Ping;Ryu, Seung-Kon
    • Carbon letters
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    • v.10 no.3
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    • pp.202-207
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    • 2009
  • Pitch-based carbon fiber tows were prepared from naphtha cracking bottom oil by reforming and carbonization. The relationship between exothermic heat and carbon contents of the fiber was investigated by changing the carbonization conditions. The carbon contents and the crystallinities of isotropic pitch-based carbon fibers were 86.8~93.8 wt% and 33.7~40.1%, respectively, which were linearly proportional to the increase of carbonization temperature from 700 to $1000^{\circ}C$. The exothermic heat (temperature increase) of fiber tows was measured in a short time, which was also linearly proportional to the increase of carbon contents due to the increase of crystallinity, even though the crystallinity was low. Therefore, the carbon contents or carbonization degree of fibers can rapidly and indirectly be estimated by measuring the surface temperature increase of fibers.

Generating Characteristics of the Cymbal Type Piezoelectric Generator (Cymbal Type 압전 발전기의 발전 특성)

  • Jun, Ho-Ik;Jeoung, Sung-Su;Chong, Hyon-Ho;Park, Tae-Gone;Kim, Myung-Ho
    • Journal of the Korean Institute of Electrical and Electronic Material Engineers
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    • v.22 no.4
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    • pp.360-365
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    • 2009
  • On this paper, piezoelectric generators using piezoelectric ceramics were designed and fabricated. Generators were made by attaching cymbal type metal plates on upper and bottom sides of a disc type piezoelectric ceramic. Generator converts wasting mechanical energy to electrical energy. Output voltage was increased when thickness of ceramic and displacement of vibration were increased. Temperature of the ceramic was increased when it generates, but the temperature rising was saturated at certain temperature.