• Title/Summary/Keyword: Drop time

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Performance of Automotive Cabin Air Filter for Passenger Cars (승용차용 Cabin Air Filter의 성능)

  • 박영옥;구철오;임정환;김홍룡;손재익
    • Journal of Korean Society for Atmospheric Environment
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    • v.12 no.3
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    • pp.279-287
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    • 1996
  • Pressure drop and fractional collection efficiency of automotive cabin air filters were examined to obtain the basic data for the development of high performance domestic cabin air filters. Pressure drop of MA-V100 was higher than that of VF-V100, and it increased with the air flow rate. VF-V100 had longer time to rise the critical pressure drop than that MA-V100 had. Total collection efficiency of MA-V100 for initial and dust loaded conditions was higher than that of VF-V100. Also, fractional collection efficiency of MA-V100 for the fine particles was higher than that of VF-V100. Particla size distribution for the minimum collection efficiency ranged from 0.02 $\mu$m to 0.04 $\mu$m for MA-V100 and it ranged from 0.02 $\mu$m to 0.15 $\mu$m for VF-V100.

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A study on the method of OLED device's lifetime test (OLED 소자의 수명 평가법에 관한 연구)

  • Choi, Young-Tae;Cho, Jai-Rip
    • Journal of the Korea Safety Management & Science
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    • v.10 no.4
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    • pp.145-152
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    • 2008
  • According to the Korea Agency for Technology and Standards under the Commerce Ministry, OLED device's lifetime is defined 50% drop of luminance. OLED device is self-emitting operating device, that means it becomes different color between pixels under using environment. That's reason of the different luminance drop ratio & chromaticity coordinates shift ratio with time. The problem is there is not recovered after luminance drop and color shift. We can recognize the difference of color as image sticking. First we studied when human recognize the difference of color and second we apply the method of OLED device's lifetime test that's able to check different color between pixels.

A study on the strengthening of Sodalime glass using ion exchange method (이온강화법을 이용한 소다라임 글라스 강화에 관한 연구)

  • Ahn, H.W.;Oh, J.H.;Kweon, S.G.;Choi, S.D.
    • Journal of the Korean Society of Manufacturing Process Engineers
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    • v.13 no.6
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    • pp.145-151
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    • 2014
  • The glass used for mobile display windows is required to have high strength. Chemical strengthening by means of ion exchange is widely used glass. The depth of the layer and the compressed stress are affected by tempering temperature and time. The purpose of this study is to investigate the range of DOL and CS, which to less breakage during reliability tests such as the ball drop test, hole drop test, 3-point bending test, drop test, and tumble test with Soda-lime Glass.

Rockfall Impact Analysis of Typical Roadway Using Finite Element Simulation

  • Woo, Jin-Ho;Na, Won-Bae
    • International Journal of Ocean System Engineering
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    • v.2 no.2
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    • pp.92-96
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    • 2012
  • This study presents a rockfall impact analysis of a typical roadway. Dynamic finite element analyses using ANSYS AUTODYN are conducted to determine the effect of the drop heights (5 m, 10 m) on the damage to a roadway model. The Rockfall is modeled as a spherical shape with a weight of 400 kg, and each drop height is converted to a corresponding impact velocity to save computational time. The roadway model is comprised of an asphalt layer, base layer, sub-base layer, and sub-grade layer. In this paper, the asphalt is modeled using a linear elastic model. The base layer, sub-base layer, and sub-grade layer are modeled using a Mohr-Coulomb model. From the analyses, the effects of the drop height on the damages and stresses are examined and discussed.

A study on the method of OLED device's lifetime test (OLED 소자의 수명 평가법에 관한 연구)

  • Choi, Young-Tae;Cho, Jai-Rip
    • Proceedings of the Safety Management and Science Conference
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    • 2008.11a
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    • pp.131-143
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    • 2008
  • According to the Korea Agency for Technology and Standards under the Commerce Ministry, OLED device's lifetime is defined 50% drop of luminance. OLED device is self-emitting operating device, that means it becomes different color between pixels under using environment. That's reason of the different luminance drop ratio & chromaticity coordinates shift ratio with time. The problem is there is not recovered after luminace drop and color shift. We can recognize the difference of color as image sticking. First we studied when human recognize the difference of color and second we apply the method of OLED device's lifetime test that's able to check different color between pixels

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A Study of Dust Effect on Performance of Heat Exchangers with Louver and Wavy Fins (루버형과 파형핀 열교환기에서 분진이 성능에 미치는 영향에 관한 연구)

  • Lee, Young-Lim;Hwang, Soon-Ho
    • Transactions of the Korean Society of Automotive Engineers
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    • v.17 no.4
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    • pp.126-132
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    • 2009
  • Automotive heat exchangers use louver fins for their high efficiency. However, the efficiency can significantly drop for constructional vehicles or heavy equipments due to dust deposited on the louver fins with narrow slits. Thus it is necessary to develop new fins that lead to less fouling, so that a better performance can be achieved after exposure to a dusty environment over long period of time. New wavy fins were considered in the study and numerically analysed to compare with louver fins in the areas of air-side pressure drop, heat release rate, and particulate deposition. In addition, an experiment was done on the pressure drop and the particulate deposition. The results showed that the wavy fins would be a better choice for long-term use due to the excellent dust-proof performance in comparison to louver fins, in spite of the initial inferior performance of heat release.

Weight Drop Impact Tests of Earthquake-Proof Table (내진테이블의 중량물 낙하 충격실험)

  • Eom, Tae Sung;Huh, Seok Jae;Park, Tae Won;Lee, Sang Hyun
    • Journal of the Earthquake Engineering Society of Korea
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    • v.22 no.7
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    • pp.369-378
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    • 2018
  • Full-scale seismic retrofit of old and deteriorated masonry buildings requires a lot of cost and time. In such buildings, installing an emergency evacuation space can be considered as an alternative. In this study, requirements of the earthquake-proof table used as an emergency evacuation space for buildings hit by earthquake are investigated. Load conditions required for the table, including the impact effects due to building debris drop, are explained. To investigate the impact effects in more detail, weight drop test is performed for an prototype earthquake-proof table. In the test, the weight of the falling object and free fall height were considered as the main test parameters. The results showed that the duration of impact is very short (0.0226~0.0779sec), and thus the impact forces increase to 15.8~45.2 times the weight of the falling object. Based on these results, design considerations and performance verification criteria of the earthquake-proof table as an emergency evacuation space are given.

Pipe thinning model development for direct current potential drop data with machine learning approach

  • Ryu, Kyungha;Lee, Taehyun;Baek, Dong-cheon;Park, Jong-won
    • Nuclear Engineering and Technology
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    • v.52 no.4
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    • pp.784-790
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    • 2020
  • The accelerated corrosion by Flow Accelerated Corrosion (FAC) has caused unexpected rupture of piping, hindering the safety of nuclear power plants (NPPs) and sometimes causing personal injury. For the safety, it may be necessary to select some pipes in terms of condition monitoring and to measure the change in thickness of pipes in real time. Direct current potential drop (DCPD) method has advantages in on-line monitoring of pipe wall thinning. However, it has a disadvantage in that it is difficult to quantify thinning due to various thinning shapes and thus there is a limitation in application. The machine learning approach has advantages in that it can be easily applied because the machine can learn the signals of various thinning shapes and can identify the thinning using these. In this paper, finite element analysis (FEA) was performed by applying direct current to a carbon steel pipe and measuring the potential drop. The fundamental machine learning was carried out and the piping thinning model was developed. In this process, the features of DCPD to thinning were proposed.

A Study on the Electrical Characteristics with Design Parameters in 1,200 V Trench Gate Field Stop IGBT (1,200 V급 Trench Gate Field Stop IGBT 소자의 전기적 특성 향상 방안에 관한 연구)

  • Geum, Jong-Min;Jung, Eun-Sik;Kang, Ey-Goo;Sung, Man-Young
    • Journal of the Korean Institute of Electrical and Electronic Material Engineers
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    • v.25 no.4
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    • pp.253-260
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    • 2012
  • IGBT (insulated gate bipolar transistor) have received wide attention because of their high current conduction and good switching characteristics. To reduce the power loss of IGBT, the on state voltage drop should be lowered and the switching time should be shorted. However, there is Trade-off between the breakdown voltage and the on state voltage drop. To achieving good electrical characteristics, field stop IGBT (FS IGBT) is proposed. In this paper, 1,200 V planar gate non punch-through IGBT (planar gate NPT IGBT), planar gate FS IGBT and trench gate FS IGBT is designed and optimized. The simulation results are compared with each three structures. In results, we optain optimal design parameters and confirm excellence of trench gate FS IGBT. Experimental result by using medici, shows 40% improvement of on state voltage drop.

Examination of Spread-Recoil Behavior of a Shear-thinning Liquid Drop on a Dry Wall (전단희석 액적의 건조 벽면 충돌 후 전개-수축 거동의 관찰)

  • An, Sang-Mo;Lee, Sang-Yong
    • Journal of ILASS-Korea
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    • v.14 no.3
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    • pp.131-138
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    • 2009
  • In the present study, spread-recoil behavior of a drop of shear-thinning liquid (xanthan solution) on a dry wall (polished stainless-steel plate) was examined and compared with that of Newtonian liquid (glycerin solution). Nine different kinds of xanthan and glycerin solutions were tested, including three pairs of xanthan and glycerin solutions, each having the same viscosity in low shear rate region ($10^{-2}-10^0\;l/s$). The drop behavior was visualized and recorded using a CCD camera. The maximum diameter and the spreading velocity of the xanthan drops turned out to be significantly larger and the time to reach their final shape was much shorter compared to the cases with the glycerin solutions, due to the smaller viscous dissipation resulted from lower viscosity in the higher shear rate region (>$10^0\;l/s$). As a result, the maximum diameters were measured to be larger than the predicted values based on the model proposed for Newtonian liquids, and the deviation was more pronounced with the solution with the larger viscosity variation. Consequently, viscosity variation with the shear rate was found to be a dominant factor governing the spread-recoil behavior of shear-thinning drops.

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