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A Study on the Machining Characteristics by the Internal Quality of Heat Resisting Steel (내열강의 내부품질에 따른 절삭가공 특성에 관한 연구)

  • 채왕석
    • Journal of the Korean Society of Manufacturing Technology Engineers
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    • v.9 no.1
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    • pp.24-29
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    • 2000
  • This paper is experimental study of machining characteristics about martensitic heat resisting steel STR11. Machining characteristics are different according to internal quality(chemical compositions, microscopic structure and nonmetallic inclusion) mechanical properties(tensile strength value impact value and hardness) and dynamic cutting force. Following are the results : 1. In analyzing internal quality test materials have typical martensite structure and a minute needle-shaped structure. 2. Tensile strength and reduction of area and hardness are larger. But values of elongation and impact values are smaller. Fracture surface of tensile specimen is ductile. 3, Cutting force is decreasing with cutting speed increasing 4. Cutting force is increasing with feed speed increasing.

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Analysis of Debis Flow according to Change of Slope Angle (사면경사 변화에 따른 토석류의 거동 분석)

  • Park, Byung-Soo;Jun, Sang-Hyun;Yoo, Nam-Jae;Han, Kwang-Doo;Yoon, Young-Ho
    • Proceedings of the Korean Geotechical Society Conference
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    • 2010.03a
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    • pp.1294-1301
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    • 2010
  • This study is an experimental research for the dispersion behavior and impact characteristics of debris flow according to change of slope. Large scale experimental setup for the debris flow was established to simulate the artificial rainfall and control the ground slope. Parameters such as materials of debris flow, slope, and length of slope were used for the experiments. After the experiments, it was found that the speed of ground material components was increased about 28~47%. It was found that speed can be increased by increasing the particle size. Furthermore, maximum/final loads for ground material components were increased 89% for the coarse aggregate and 68% for the fine aggregate comparing with sand.

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Track Longitudinal Irregularities at Bridge Deck Expansion Joint with ZLR(Zero Longitudinal Restraint) (활동체결장치가 설치된 교량상판 신축이음부에서의 궤도고저틀림에 미치는 영향)

  • Eom, Jong-Woo;Kim, Si-Chul;Kim, In-Jae
    • Proceedings of the KSR Conference
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    • 2007.11a
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    • pp.1093-1098
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    • 2007
  • In designing the high-speed railroad track, it is important to utilize appropriate track components to maintain uniform stiffness and ensure track alignment within the tolerance set for that system. In this regard, continuous welded rails (CWRs) were introduced to the Korean railways. Yet the installation of CWRs can result in an adverse impact due to the track/structure interaction on bridge sections yielding variations in the stiffness at the expansion joints. It may also impose additional axial force, generate excessive stress or deflection on track, and loosen the ballast at the ends as a bridge deck contracts or expands owing to a thermally-induced dynamic response. The risk is even greater in a long bridge deck, resulting in track longitudinal irregularities, deteriorating passenger's comfort, and increasing maintenance efforts. This study evaluates the performance of ZLR and their impact on track longitudinal irregularities through the track measuring results on a test section installed the ZLR in order to minimize the thermally-induced responses and the maintenance efforts for the high speed railway bridges.

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Noise Test of High Speed Train along Test Track (경부고속전철 시험선구간에서 소음영향 시험평가)

  • 나희승;김선우;김정태;정성수;조대승;김준엽
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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    • 2002.05a
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    • pp.1104-1109
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    • 2002
  • High speed railroad noise is one of the main causes of environmental impact. An estimate of the relevant noise levels is usually required in order to evaluate the noise barrier and the anti-noise trailer. This paper introduce the test procedure and the estimate for HST noise. The aim of this is to measure, by means of a test, the level of acoustic pressure present during the passing of a KTX(Korea Train Express), in order to satisfy the contractual requirements and the noise criteria. A number of measurements are carried out in order to estimate noise impact by HST along test track.

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A Study on the Influence of the Flow by the Presence and Satisfaction Factors - Focused on Online Game - (실재감요인과 만족감요인이 몰입에 미치는 영향에 관한 연구 - 온라인게임을 중심으로 -)

  • Jo, Jin-Wan;Lee, Jong-Ho
    • Proceedings of the Korea Database Society Conference
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    • 2008.05a
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    • pp.87-106
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    • 2008
  • This study identified the properties of online game, and analyzed existing studies on the impact of the properties of online game on flow. As a result, graphics, sounds, scenarios, game speed, manipulability, and item difficulty were identified as properties of online game, which were influential factors to flow. As a result, the hypotheses on scenarios, game speed, and item difficulty were adopted as significantly influential factors to flow, Attribute of online game. Meanwhile, the hypotheses on graphics, sounds, and manipulability, which were expected to significantly impact flow, were rejected.

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A Study of KHST Passenger Safety During Accidents by Computer Simulation Techniques (컴퓨터 시뮬레이션 기법을 이용한 고속전철 승객안전도 해석 및 평가)

  • 윤영한;구정서;이재완
    • Journal of the Korean Society for Railway
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    • v.6 no.1
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    • pp.15-20
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    • 2003
  • The computer simulation techniques were adopted to evaluate the effects of seating positions of passenger under various accident scenarios. The baseline of computer simulation model was tuned by the sled impact tests which conducted under the upright and standard seating positions. This study shows the effect of relative velocity between occupant and struck vehicle while occupant is impacted to a front seat's seatback. Although, base on the current accident scenarios, The KHST is performed well enough to protect average adult male occupants. However, Results from the tests indicate small size occupant or higher impact speed may cause sever neck and femur injuries.

Noise Test for High Speed Train (고속철도 소음시험평가)

  • Na, H.S.;Kim, Y.G.;Choe, K.Y.;Shim, S.D.;Kim, J.Y.
    • Proceedings of the KSME Conference
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    • 2001.06b
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    • pp.181-186
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    • 2001
  • High speed railroad noise is one of the main causes of environmental impact. An estimate of the relevant noise levels is usually required in order to evaluate the noise barrier and the anti-noise trailer. This paper introduce the test procedure and the estimate for HST noise. The aim of this is to measure, by means of a test, the level of acoustic pressure present during the passing of a KTX(Korea Train Express), in order to satisfy the contractual requirements and the noise criteria. A number of measurements are carried out in order to estimate noise impact by HST along test track.

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On the structural behavior of ship's shell structures due to impact loading

  • Lim, Hyung Kyun;Lee, Joo-Sung
    • International Journal of Naval Architecture and Ocean Engineering
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    • v.10 no.1
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    • pp.103-118
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    • 2018
  • When collision accident between ships or between ship and offshore platform occurs, a common phenomenon that occurs in structures is the plastic deformation accompanied by a large strain such as fracture. In this study, for the rational design against accidental limit state, the plastic material constants of steel plate which is heated by line heating and steel plate formed by cold bending procedure have been defined through the numerical simulation for the high speed tension test. The usefulness of the material constants included in Cowper-Symonds model and Johnson-Cook model and the assumption that strain rate can be neglected when strain rate is less than the intermediate speed are verified through free drop test as well as comparing with numerical results in several references. This paper ends with describing the future study.

Behavior Properties of Bridge by Non Destructive and Loading Test (비파괴 및 재하시험에 의한 노후 교량의 거동특성)

  • Min, Jeong-Ki;Kim, Young-Ik
    • Journal of The Korean Society of Agricultural Engineers
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    • v.46 no.1
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    • pp.61-71
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    • 2004
  • The performance evaluation and deflection of 3 spans concrete simplicity slab bridge analyzed by non-destructive and loading test. Compressive strength of slab and pier appeared in the range of each 353∼366 kgf/cm2 and 152∼215 kgf/cm2 in rebound number test. Also, it appeared that concrete quality of slab was good after performance improvement. The average compressive strength of slab by core picking appeared 229 kg/cm2. In reinforcing bar arrangement test of span and member, it appeared that horizontal and vertical reinforcing bar was arranged to fixed interval. The value of calculation deflection that carried structural analysis with deflection analysis wave in static loading test appeared higher than that of experimental deflection and it appeared that hardness of this bridge was good. Maximum impact factor that estimated from deflection by running speed in dynamic loading test appeared by 0.216 in 10 km/hr running speed.

Bouncing Phenomena of Micro-droplet Train in Inkjet Printing (잉크젯 프린팅에서 발생하는 연속 미소 액적의 바운싱 현상)

  • Ara Jo;Hyoungsoo Kim
    • Journal of the Korean Society of Visualization
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    • v.21 no.1
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    • pp.26-30
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    • 2023
  • Interaction of a droplet and substrate is important to determine the coating and final deposition pattern in inkjet printing system. In particular, an accurate deposition of the droplet should be guaranteed for high-resolution patterning. In this study, we performed high-speed shadowgraph experiments on droplet train impact in inkjet system. From the high-speed images, we observed an unexpected bouncing phenomenon. We have found two factors affecting bouncing regime; the Weber number and the curvature of deposited droplet. Experimental results indicate that there is a critical curvature diameter of deposited droplet, which splits into bouncing and merging regime. From this result, we obtained a power-law behavior between the Weber number and the curvature. The understanding of bouncing phenomena helps to improve the accuracy and productivity of inkjet printing.