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On the Application of CFD Codes for Natural Gas Dispersion and Explosion in Gas Fuelled Ship

  • Kim, Ki-Pyoung;Kang, Ho-Keun;Choung, Choung-Ho;Park, Jae-Hong
    • Journal of Advanced Marine Engineering and Technology
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    • v.35 no.7
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    • pp.946-956
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    • 2011
  • The main objectives of this study are to analyze the leaked gas dispersion and quantify the potential overpressures due to vapor cloud explosions in order to identify the most significant contributors to risk by using Computational Fluid Dynamics (CFX & FLACS) for gas fuelled ships. A series of CFD simulations and analyses have been performed for the various gas release scenarios in a closed module, covering different release rates and ventilating methods. This study is specially focused on the LNG FGS (Fuel Gas Supply) system recently developed for the propulsion of VLCC crude oil carriers by shipyards. Most of work presented is discussed on the gas dispersion from leaks in the FGS room, and shows some blast prediction validation examples.

Electrical and Dielectric Properties of ZPCCY-Based Varistor Ceramics with Sintering Time (ZPCCY계 바리스터 세라믹스의 소결시간에 따른 전기적, 유전적 특성)

  • 남춘우;김향숙
    • Journal of the Korean Institute of Electrical and Electronic Material Engineers
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    • v.15 no.11
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    • pp.946-952
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    • 2002
  • The electrical and dielectric characteristics of ZPCCY-based varistor ceramics were investigated in the sintering time range of 1∼3 h. Increasing sintering time deteriorated the nonlinearity, in which nonlinear exponent is decreased from 51.2 to 23.8 and leakage current is increased from 1.3 to 5.6 $\mu$A. As sintering time increases, the donor concentration was decreased in the range of (1.25∼l.73)$\times$10$\^$18/cm$\^$-3/ and the density of interface states is (3.64∼94.19)$\times$10$\^$12/cm$\^$-2/ with increasing sintering time. The increase in sintering time caused tan $\delta$ to increase in the range of 0.043 to 0.062 and relaxation time to increase in the range of 1.55 to 2.23 ㎲.

A Finite Element Heat Transfer Analysis with Coupling of Roll and Molten Metal in Direct Rolling Process (직접압연공정에 있어서 롤과 용탕을 연계한 유한요소 열전도해석)

  • 김영도;강충길
    • Transactions of the Korean Society of Mechanical Engineers
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    • v.18 no.4
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    • pp.946-957
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    • 1994
  • In the steel industries, direct rolling process for production of strip from molten metal has been investigated to simplify processes, to minimize energy consumption, and to improve quality of the strip. In this study, two kinds of practicable scale cooling rollers are proposed. And heat transfer analysis of pool region and cooling roller considering flow of molten metal and roll rotation respectively using the finite element method are performed to obtain the proper initial condition and to observe cooling characteristics of cooling roller. From the results, variations of solidification final points and temperature distribution in roller are observed quantitatively according to roll rotation.

A Study on Decision-making Criteria in Industrial Sector for Electric Load Aggregation (수요반응자원으로서 산업용 부하의 매집 우선순위 결정 기준에 관한 연구)

  • Kim, Sung-Yul;Kim, Dong-Min
    • The Transactions of The Korean Institute of Electrical Engineers
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    • v.65 no.6
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    • pp.946-954
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    • 2016
  • Energy industry is undergoing a paradigm shift in customer participation in the smartgrid. Customers traditionally consume electrical power. But nowadays not only do they generate electricity from private distributed generations, they can participate in demand response programs with their negawatt power which means a theoretical unit of power representing an amount of energy saved. Therefore development of decision-making criteria for electric load aggregation becomes a greater consideration as an amount of energy saved from demand response resources increases. This paper proposes load aggregators' decision-making criteria in the industrial sector where it made up the largest portion in demand response portfolio in order to assure reliability performance for demand response resources.

The Dielectric loss Properties of Mini-model Superconducting Cable (Mini-model 초전도 케이블의 유전손실 특성)

  • 김영석;곽동순;한철수;김해종;김동욱;김상현
    • Journal of the Korean Institute of Electrical and Electronic Material Engineers
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    • v.16 no.10
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    • pp.946-951
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    • 2003
  • A high-Tc superconducting cable(HTS cable) is expected as an underground power line supplying the electrical power the densely populated city in future. The electrical insulation is very important for develop HTS cable system because it is operated a high voltage and in cryogenic temperature. We manufactured a mini-model cable and measured a tan$\delta$ of cable using schering bridge. The tan$\delta$ of PPLP was lower than that of Tyvek and Kraft at a given temperature, the tan$\delta$ of PPLP was 1.16${\times}$10-3. According to the increase of electric stress the tan$\delta$ increased because partial discharge occurred inside butt gap of mini-model cable. However, the tan$\delta$ decreased by increase of liquid nitrogen pressure. This reason is thought by decrease of part discharge between butt gap by increase of liquid nitrogen pressure.

Lateral Vibration Analysis of a Nonuniform Beam by Ritz's Method (Ritz법에 의한 비균일 단면 외팔보의 횡진동 해석)

  • Park, Sok-Chu
    • Transactions of the Korean Society for Noise and Vibration Engineering
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    • v.17 no.10
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    • pp.946-949
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    • 2007
  • This paper discusses the lateral vibration of a beam with boundary condition of one end fixed and the other end free. The uniform beam has a solution by summation of some simple exponential functions. But if its shape is not uniform, its solution could be by Bessel's function or mathematical solution could not exist. Even if the solution of Bessel's function exists, as Bessel function is a series function, we must get the solution by numerical method. Author had proposed the solution of the matrix method by Ritz's method and a new mode shape function, and had earned the good results for a wedge beam. Hereby a vibration analysis for the tapered beam with circle cross section was executed, and so good results were showed.

Gamification of Cultural Experience (게이미피케이션(Gamification) 문화체험 플랫폼 구축)

  • Park, Gwang-Deok;Kwon, Gu-Yoon;Shin, Jae-Yoon;Lim, Jong-Deok
    • Proceedings of the Korea Information Processing Society Conference
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    • 2017.11a
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    • pp.946-949
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    • 2017
  • ICT의 융합과 4차 산업혁명이 도래하면서 이론만으로 존재하던 기술들이 실현가능해졌다. 우리는 이 중에서 가상현실 기술에 초점을 맞추었고, SNL Korea에서 방영한 GTA조선에서 영감을 받아 VR기술을 게임이라는 컨텐츠와 융합하였다. 이는 공간적인 제약성을 극복하고, 생동감 있는 경험을 제공해 다문화 가정 및 관광객들에게 손쉽게 전통문화를 체험할 수 있는 좋은 기회를 마련할 것이다.

A Study on the Speed and Torque Control of Propulsion Motor for Electric Propulsion Ship by Direct Torque Control (직접토크제어에 의한 전기추진선박의 추진전동기 속도 및 토크제어에 관한 연구)

  • Kim, Jong-Su;Oh, Sae-Gin;Kim, Seung-Hwan
    • Journal of Advanced Marine Engineering and Technology
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    • v.33 no.6
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    • pp.946-951
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    • 2009
  • An induction motor based on DTC(Direct Torque Control) is being increasingly used in various industrial applications. DTC offers faster torque response and better speed control with lesser hardware and processing costs in compared with other controlled drives. This study was to evaluate performance of DTC for induction motor of electric propulsion ship. The simulation results indicated good speed and torque response from the low to middle speed range. Also, DTC has advantages such as the independency on motor parameter.