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Experiments on the Heat Transfer and Pressure Drop Characteristics of a Channel with Pin-Fin Array (핀-휜을 삽입한 채널의 열전달 및 압력강하 특성 실험)

  • 신지영;손영석;김상민;이대영
    • Korean Journal of Air-Conditioning and Refrigeration Engineering
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    • v.16 no.7
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    • pp.623-629
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    • 2004
  • Rapid development of electronic technology requires small size, high density packaging and high power of electronic devices, which result in more heat generation by the electronic system. Present cooling technology may not be adequate for the thermal management in the current state-of-the-art electronic equipment. Forced convective heat transfer in a channel filled with pin-fin array is studied experimentally in this paper as an alternative cool-ing scheme for a high heat-dissipating equipment. Various configurations of the pin-fin array are selected in order to find out the effect of spacing and diameter of the pin-fin on the heat transfer and pressure drop characteristics. In the low porosity region, interfacial heat transfer and pressure drop seem to show different trend compared to the conventional heat transfer process.

A Study on Terminology of Metal Handles in Traditional Korean Furniture - Focusing on Korean and Western Furniture - (한국전통가구의 금속 손잡이 영문표기 연구 - 한국 및 서구를 중심으로 -)

  • Moon, Sun-Ok
    • Journal of the Korea Furniture Society
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    • v.23 no.4
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    • pp.449-459
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    • 2012
  • The article aims to making a comparison between traditional Korean and Western furniture metal handles to give the detail information of the handle terms by analyzing the related literature including internet and interviews. In terms of that, the Korean and Western metal handles are compared in the types, components, materials, methods, and terms affecting the development made by the craftsmen before the Industrial Revolution about the mid or late 18th century. As a result, first, ring and drop pull handles were mostly and wooden knobs were a little used to open the furniture doors and drawers. The Korean drop pulls, Deulswae, came out after the ring pulls, Gori, while the Western drops called loop or bail handles as well, came out before the ring pulls. Second, the components were composed by ring, Gori, loop or bail, Deulswae, Post, Baemok, washer, Baemokbatchim, and backplate, Deulswaebatchim. Most of the Western handles were fastened by the bolt and nut, while the post of two strips, Baemok, fastened the Korean metal handles. Third, the metal handles were created of brass and iron mostly, gilded gold and silver. Forth, the method were largely used by casting, engraving, forging, plating, and hammering in the Korean handles, and by casting, molding, engraving, and stamped in the Western handles. Finally, the terms such as "knobs, pulls, drops, ring and drop pulls, loop or bail handles, posts, washers, backplate, casting, molding, engraving, forging, plating, and stamped" were clarified by the two comparison in Korean and English.

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Performance Analysis of Random Early Dropping Effect at an Edge Router for TCP Fairness of DiffServ Assured Service

  • Hur Kyeong
    • The Journal of Korean Institute of Communications and Information Sciences
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    • v.31 no.4B
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    • pp.255-269
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    • 2006
  • The differentiated services(DiffServ) architecture provides packet level service differentiation through the simple and predefined Per-Hop Behaviors(PHBs). The Assured Forwarding(AF) PHB proposed as the assured services uses the RED-in/out(RIO) approach to ensusre the expected capacity specified by the service profile. However, the AF PHB fails to give good QoS and fairness to the TCP flows. This is because OUT(out- of-profile) packet droppings at the RIO buffer are unfair and sporadic during only network congestion while the TCP's congestion control algorithm works with a different round trip time(RTT). In this paper, we propose an Adaptive Regulating Drop(ARD) marker, as a novel dropping strategy at the ingressive edge router, to improve TCP fairness in assured services without a decrease in the link utilization. To drop packets pertinently, the ARD marker adaptively changes a Temporary Permitted Rate(TPR) for aggregate TCP flows. To reduce the excessive use of greedy TCP flows by notifying droppings of their IN packets constantly to them without a decrease in the link utilization, according to the TPR, the ARD marker performs random early fair remarking and dropping of their excessive IN packets at the aggregate flow level. Thus, the throughput of a TCP flow no more depends on only the sporadic and unfair OUT packet droppings at the RIO buffer in the core router. Then, the ARD marker regulates the packet transmission rate of each TCP flow to the contract rate by increasing TCP fairness, without a decrease in the link utilization.

A study on the design of High current and Low Drop Out-voltage Regulator IC using BCD Technology (BCD 기술을 이용한 고전류 및 Low Drop Out-voltage Regulator IC 설계에 관한 연구)

  • Park, Tae-Su;Choi, In-Chul;Lee, Jo-Woon;Koo, Yong-Seo
    • Proceedings of the IEEK Conference
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    • 2005.11a
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    • pp.937-940
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    • 2005
  • In this paper, the design of high current and high performance Regulatior IC using BCD Technology are presented. We design the 5A class regulator IC including the VDMOS Pass Tr. of N-sink array structure. Also, to obtain the high current and low power characteristics, the PMOS and BJT device are adapted for the Pass Tr. It is shown that simulation results of Regulator IC with VDMOS Pass Tr. have the Iout=4.5092A, LDO=7.3mV.

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Measurement of Sonobuoy Transmitting Antenna System for Anti-Submarine Warfare

  • Min Kyeong-Sik
    • Journal of electromagnetic engineering and science
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    • v.5 no.2
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    • pp.97-103
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    • 2005
  • This paper describes the measured results of sonobuoy transmitting antenna system for anti-submarine warfare (ASW). Since radiation pattern and power density depend on impedance matching between transmitting RF part and antenna with termination resistance, design of matching circuit is very important for sonobuoy system performance. Matching circuit is designed by Smith chart using control of L and C. In standing wave ratio(SWR) measurement using Network Analyzer, SWR of antenna with matching circuit observed 1.5 below at the assigned VHF band. It shows very excellent performance comparison with conversional product that is used for the same object. The measured vertical and horizontal radiation patterns are also shown the satisfaction of military specifications. A drop out of sonobuoy system on the sea is happened when angle of elevation direction is over 10 degrees, and it is conformed that it takes less than I second return to original signal level. The required electric power density is $83\;mW/m^2$ in the military specification, and measured electric power density is observed over average $110\;mW/m^2$ at all frequency bands.

Applicability of Dynamic Compact Pilot Test on Waste Landfill (폐기물 매립장에서 동다짐공법의 적용성에 관한 연구)

  • 천병식;임병수;김명진
    • Proceedings of the KSR Conference
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    • 2000.11a
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    • pp.418-425
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    • 2000
  • In this study, the evaluation for utilization of waste landfill was performed by field test to use waste landfill as construction site(Nangido in Seoul). The site where dynamic compaction test was carried out was divided by 4 yards. Yard 1, 2 were not eliminated widening of cover soil and Yard 3, 4 were eliminated it. Dynamic Compaction Pilot Test was carried out by the 15ton heavy tamper with drop height of 20m in Yard 1, 3 and with drop height of 15m in Yard 2, 4 We evaluated the compaction ability, optimum compaction number and noiseㆍvibration through field test, monitoring. To make use of waste landfill as a construction site, The dynamic compaction method is suitable for using in waste landfill as a construction site among the ground improvement methods.

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Analysis of Flow and Performance of Regulator for Clean Gas Supply System (가스 조절용 레귤레이터의 유동 및 성능해석)

  • Kim, M.K.;Lee, Y.S.;Choi, W.J.;Kwon, O.B.;Park, J.
    • Journal of Power System Engineering
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    • v.13 no.1
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    • pp.13-18
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    • 2009
  • In this study, flow characteristics at the regulators, which is very important for clean gas supply systems for semiconductors and LCD industries, are investigated. Numerical simulations are carried out to visualize flows at regulators for several flow rates and to investigate pressure losses at some parts in the regulator. Velocity field at the regulator along with the detailed velocity field near the spring and near the valve is shown. New regulator models are proposed in this paper, and numerical simulations are also carried out to visualize flows at regulator for several flow rates, and to investigate pressure losses at the parts in new models. Pressure drops a lot across the valve seat. Pressure drop increases as mass flow rate increases. Especially for small opening, pressure drop increases rapidly as mass flow rate becomes large.

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A comparison of methods to reduce overfitting in neural networks

  • Kim, Ho-Chan;Kang, Min-Jae
    • International journal of advanced smart convergence
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    • v.9 no.2
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    • pp.173-178
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    • 2020
  • A common problem with neural network learning is that it is too suitable for the specificity of learning. In this paper, various methods were compared to avoid overfitting: regularization, drop-out, different numbers of data and different types of neural networks. Comparative studies of the above-mentioned methods have been provided to evaluate the test accuracy. I found that the more data using method is better than the regularization and dropout methods. Moreover, we know that deep convolutional neural networks outperform multi-layer neural networks and simple convolution neural networks.

Analysis of The Electrical Characteristics of Power IGBT According to Design and Process Parameter (설계 및 공정 변수에 따른 600 V급 IGBT의 전기적 특성 분석)

  • Kang, Ey Goo
    • Journal of the Korean Institute of Electrical and Electronic Material Engineers
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    • v.29 no.5
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    • pp.263-267
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    • 2016
  • In this paper, we analyzed the electrical characteristics of NPT planar and trench gate IGBT after designing these devices according to design and process parameter. To begin with, we have designed NPT planar gate IGBT and carried out simulation with T-CAD. Therefore, we extracted design and process parameter and obtained optimal electrical characteristics. The breakdown voltage was 724 V and The on state voltage drop was 1.746 V. The next was carried out optimal design of trench gate power IGBT. We did this research by same drift thickness and resistivity of planar gate power IGBT. As a result of experiment, we obtain 720 V breakdown voltage, 1.32 V on state voltage drop and 4.077 V threshold voltage. These results were improved performance and fabrication of trench gate power IGBT and planar gate Power IGBT.

Low Drop Out Regulator with Ripple Cancelation Circuit (잡음 제거 회로를 이용한 LDO 레귤레이터)

  • Kim, Chae-Won;Kwon, Min-Ju;Jung, Jun-Mo
    • Journal of IKEEE
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    • v.21 no.3
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    • pp.264-267
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    • 2017
  • In this paper, A low dropout (LDO) regulator that improves the power supply rejection ratio by using a noise canceling circuit is proposed. The noise rejection circuit between the error amplifier and the pass transistor is designed to reduce the influence of the pass transistor on the noise coming from the voltage source. The LDO regulator has the same regulation characteristics as the conventional LDO regulator. The proposed circuit uses 0.18um process and Cadence's Virtuoso and Specter simulator.