• Title/Summary/Keyword: Drop-in Test

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Study on the Impact Analysis of Front Loader for Tractor (트랙터용 프론트 로더의 충격해석에 관한 연구)

  • Lim, Gi-Soo;Lee, Boo-Youn
    • Journal of the Korea Academia-Industrial cooperation Society
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    • v.16 no.8
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    • pp.5051-5059
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    • 2015
  • Structural behaviour of the front loader for an agricultural tractor was analyzed for three impact test conditions: drop and catch, corner pull, and corner push. Rigid-body dynamic, transient structural, and static structural analyses were conducted using a commercial finite element software. Analysis of the drop and catch test dealt with the case that the bucket located at the maximum elevation was dropped and catched through three steps. Analysis of the corner pull test dealt with the case that the bucket constrained to the ground by a chain at its corner was raised suddenly. Analysis of the corner push test dealt with the case that the corner of the bucket collided with an obstacle. Results of analyses of the three test conditions showed that maximum stress occurs at the geometrically discontinuous location in the mount and is caused from local stress concentration. Results of the present research can be utilized as a guideline to achieve more reliable and safe structural design of the front loaders.

A Study on Finned Tube Used in Turbo Refrigerator(III) -for Pressure Drop- (터보 냉동기용 핀 튜브에 관한 연구 (III) -압력 손실에 관하여-)

  • Han, Kyu-Il;Kim, Si-Young;Cho, Dong-Hyun
    • Journal of Fisheries and Marine Sciences Education
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    • v.6 no.1
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    • pp.58-76
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    • 1994
  • Heat transfer and pressure drop measurements are made on low integral-fin tubes in turbulent water flow condition. The integral-fin tubes investigated in this paper are nominally 19mm in diameter. Eight tubes have been used with trapezoidally shaped integral-fins having fin density from 748 to 1654 fpm and 10, 30 grooves. Plain tube having same diameter as finned tube is also tested for comparison. Experiments are carried out using R-11 as working fluid. The refrigerant condensates at a saturation state of 30C on the outside tube surface cooled by coolant. The amount of noncondensable gases present in the test loop is reduced to a negligible value by repeated purging. For a given heat input to the boiler and given cooling water flow rate, all test data are taken on steady state. The heat transfer loop is used for testing single long tubes and cooling water is pumped from a storage tank through filters and flowmeters to the horizontal test section where it is heated by steam condensing on the outside of the tube. The pressure drop across the test section is measured by means of pressure gauge and manometer. Each tube tested is cleaned with sodium dichromate pickling solution and well rinsed with water prior to installation in the test section. The results obtained in this study is as follows : 1. Based on inside diameter and nominal inside area, heat transfer of finned tube is enhanced up to 4 times as that of a plain tube at constant Reynolds number and up to 2 times at constant pumping power. 2. Friction factors are up to 1.6~2.1 times those of plain tube. 3. At a given Reynolds number, Nusselt number decrease with increasing pitch to diameter. 4. The constant pumping power ratio for low integral-fin tubes increase directly with the effective area to the nominal area ratio, and with the effective area diameter ratio.

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Fall Impact Analysis of Type 4 Composite Pressure Vessels Using SPH Techniques (SPH 기법을 활용한 Type 4 복합재료 압력용기 낙하 충격 해석)

  • SONG, GWINAM;KIM, HANSANG
    • Journal of Hydrogen and New Energy
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    • v.32 no.3
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    • pp.172-179
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    • 2021
  • The drop impact analysis was carried out on Type 4 pressure containers, and the degree of damage to the falling environment was predicted and determined using smoothed particle hydrodynamics (SPH) techniques. The purpose of the design and the optimization process of the winding pattern of the pressure vessel of the composite material is to verify the safety of the container in actual use. Finally, an interpretation process that can be implemented in accordance with domestic test standards can be established to reduce the cost of testing and containers through pre-test interpretation. The research on the fall analysis of pressure vessels of composite materials was conducted using Abaqus, and optimization was conducted using ISIGHT. As a result, the safety of composite pressure vessels in the falling environment was verified.

MHD Pressure Drop of a Liquid-Metal Flow under a Transverse Magnetic Field (자기장하의 액체금속 유동의 차압 측정)

  • Cha, Jae-Eun;Kim, Hee-Reyoung;Kim, Jong-Man;Nam, Ho-Yoon;Kim, Sung-O;Kim, Byung-Ho
    • Proceedings of the KSME Conference
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    • 2007.05b
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    • pp.2638-2641
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    • 2007
  • The magnetohydrodynamic(MHD) pressure drop along a liquid sodium flow was measured in a rectangular duct under a transverse magnetic field. The test section was made of a 3 mm thick stainless steel SUS304 with a 74×5mm2 rectangular flow channel. The range of experimental parameters was roughly B=00.18T and U=00.9m/s at around 200C. The differential pressure was measured by a diaphragm seal-type pressure transmitter filled with a high temperature silicon oil within 0.1MPa. The experimental results show a similar pressure drop with the theoretical estimation according to a change of the flow velocity and the magnetic field.

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Analysis of Package Drop and its Application for Optical Disc Drives (광 디스크 드라이브용 완충포장재의 낙하충격 해석 및 활용)

  • 석기영;윤기원;나정민;박창배
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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    • 2004.05a
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    • pp.177-182
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    • 2004
  • Electronic products are subjected to many different types of shock environment. As the Optical Disc Drive (ODD) market grows, the number of failures related to shock increases. Therefore, it is necessary to improve the performance of cushion package as well as the product design. Cushion materials such as expanded polystyrene are often used to protect electronic products from shock environment. In this paper, the drop analysis of the cushion package f3r optical disc drives was carried out with the explicit method of LS-DYNA and verified by the drop test. For the optimization of package, response surface approximation model was created using central composite design. As a result, cushioning performance was improved under the critical condition and practical design guidelines of cushion package were suggested.

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Centrifuge modeling of dynamically penetrating anchors in sand and clay

  • An, Xiaoyu;Wang, Fei;Liang, Chao;Liu, Run
    • Geomechanics and Engineering
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    • v.30 no.6
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    • pp.539-549
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    • 2022
  • Accidental anchor drop can cause disturbances to seabed materials and pose significant threats to the safety and serviceability of submarine structures such as pipelines. In this study, a series of anchor drop tests was carried out to investigate the penetration mechanism of a Hall anchor in sand and clay. A special anchor drop apparatus was designed to model the inflight drop of a Hall anchor. Results indicate that Coriolis acceleration was the primary cause of large horizontal offsets in sand, and earth gravity had negligible impact on the lateral movement of dropped anchors. The indued final horizontal offset was shown to increase with the elevated drop height of an anchor, and the existence of water can slow down the landing velocity of an anchor. It is also observed that water conditions had a significant effect on the influence zone caused by anchors. The vertical influence depth was over 5 m, and the influence radius was more than 3 m if the anchor had a drop height of 25 m in dry sand. In comparison, the vertical influence depth and radius reduced to less than 3 m and 2 m, respectively, when the anchor was released from 10 m height and fell into the seabed with a water depth of 15 m. It is also found that the dynamically penetrating anchors could significantly influence the earth pressure in clay. There is a non-linear increase in the measured penetration depth with kinematic energy, and the resulted maximum earth pressure increased dramatically with an increase in kinematic energy. Results from centrifuge model tests in this study provide useful insights into the penetration mechanism of a dropped anchor, which provides valuable data for design and planning of future submarine structures.

Evaluation of Impact Energy Absorption Characteristics of Flexible Sand Asphalt Pavement for Pedestrian Way (보도용 연성 샌드 아스팔트 포장의 충격흡수 특성 평가)

  • Choi, Chang-jeong;Dong, Baesun;Kim, Kwang W.;Kim, Sungun
    • Journal of The Korean Society of Agricultural Engineers
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    • v.61 no.3
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    • pp.31-41
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    • 2019
  • More than 90% of roadway in the world are paved as asphalt concrete pavement due to its excellent properties compared with other paving materials; excellent riding quality, flexibility, anti-icing property and easy maintenance-ability. In this study, to make best use of the softer property of the asphalt mixture, the flexible sand asphalt mixture (FSAM) was developed for pedestrian ways. The mix design was conducted to prepare FSAM using PG64-22 asphalt, screenings (sand) less than 5mm, crumb rubber, hydrated lime and limestone powder without coarse aggregate. The deformation strength (SD), indirect tensile strength (ITS) and tensile strength ratio (TSR) tests were conducted to make sure durability of FSAM performance. The impact energy absorption and flexibility were measured by drop-boll test and the resilient modulus (MR) test. The impact energy absorption of FSAM was compared with normal asphalt pavement, concrete pavement, stone and concrete block for pedestrian way. As a result of drop-boll test, FSAM showed higher impact energy absorption compared with other paving materials with the range of 18% to 43%. Impact energy absorption of FSAM increased with increasing test temperature from 5 to 40C. The results of MR test at 5C showed that the flexibility of FSPA was increased further, because the MR value of the sand asphalt was measured to be 38% lower than normal dense-graded asphalt mixture (WC-1). Therefore, it was concluded that the FSAM could provide a high impact absorbing characteristics, which would improve walking quality of the pedestrian ways.

The Effects of Two - Phase Swirling Flow on Void Distribution and Pressure Drop in a Vertical Tube (수직관에서 2상선회유동이 보이드분포와 압력강하에 미치는 영향)

  • Kim, I.S.;Son, B.J.;Shin, H.D.;Kwack, K.T.
    • Korean Journal of Air-Conditioning and Refrigeration Engineering
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    • v.1 no.2
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    • pp.190-201
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    • 1989
  • This experimental investigation has been conducted to determine the effects of swirling angle and flow patterns on distributions of void fraction, bubble velocity and two-phase pressure drop in a vertical straight tube. Swirling angles of 0 (non swirling), 30, and 45 were tested with air-water two components over a range of superficial air velocities. A transparent lucite tube of 38mm in internal diameter was used for the test section. The void fraction and bubble velocities were measured by means of a optical fiber probe at the upper part of the swirler in the test section. Pressure drops which seem to be closely related with flow patterns and swirling angle were measured by a differential pressure transducer. It is shown that the probability density functions of pressure drop demonstrate peculiar features for both swirling angles and flow patterns, whereas the distributions of void fraction and bubble velocities are parabolic and flat shape in the vicinity of tube center, respectively except bubbly flow in any swirling angle cases, and the void fraction increases with increasing swirling angle around the center of tube.

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Performance Characteristics of a Drop-in System for a Mobile Air Conditioner Using Refrigerant R1234yf (냉매 R1234yf 적용 자동차용 에어컨 Drop-in 성능 특성)

  • Cho, Honghyun;Lee, Hoseong;Park, Chasik
    • Korean Journal of Air-Conditioning and Refrigeration Engineering
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    • v.24 no.12
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    • pp.823-829
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    • 2012
  • In this study, the performance of mobile air conditioner(MAC) systems to which the refrigerants R134a and R1234yf were used was evaluated to compare the characteristic of automotive refrigeration cycles with refrigerant. The experimental setup of a MAC consists of an belt driven compressor, a condenser, an evaporator and a block type thermal expansion valve. The drop-in test on MAC were carried out under variable compressor speed from 800 to 2500 rpm. Performance test by using R1234yf and R134a in the same system revealed low the charge amount and mass flow rates for using R1234yf, that is, up to 10% and 17%, respectively. The compressor discharge temperature of R1234yf is 8C lower than that of R134a. The cooling capacity with R1234yf system decreased by 4~7% compared with R134a system. In addition, The COP of R1234yf system is lower 3~4% than that of R134a system.

Biomechanical Characteristic on Lower Extremity with or without Chronic Ankle Instability during Double Leg Drop Landing (양발 드롭랜딩 시 만성적인 발목 불안정성 유무에 따른 하지주요관절의 역학적 특성)

  • Jeon, Kyoungkyu;Park, Jinhee
    • Korean Journal of Applied Biomechanics
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    • v.31 no.2
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    • pp.113-118
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    • 2021
  • Objective: The purpose of this study was to investigate differences of landing strategy between people with or without chronic ankle instability (CAI) during double-leg drop landing. Method: 34 male adults participated in this study (CAI = 16, Normal = 18). Participants performed double-leg drop landing task on a 30 cm height and 20 cm horizontal distance away from the force plate. Lower Extremities Kinetic and Kinematic data were obtained using 8 motion capture cameras and 2 force plates and loading rate was calculated. Independent samples t-test were used to identify differences between groups. Results: Compared with normal group, CAI group exhibits significantly less hip internal rotation angle (CAI = 1.52±8.12, Normal = 10.63±8.44, p = 0.003), greater knee valgus angle (CAI = -6.78±5.03, Normal = -12.38 ±6.78, p = 0.011), greater ankle eversion moment (CAI = 0.0001±0.02, Normal = -0.03±0.05, p = 0.043), greater loading Rate (CAI = 32.65±15.52, Normal = 18.43±10.87, p = 0.003) on their affected limb during maximum vertical Ground Reaction Force moment. Conclusion: Our results demonstrated that CAI group exhibits compensatory movement to avoid ankle inversion during double-leg drop landing compared with normal group. Further study about how changed kinetic and kinematic affect shock absorption ability and injury risk in participants with CAI is needed.