• Proceedings of the Korean Vacuum Society Conference
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• 2014.02a
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• pp.145.2-145.2
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• 2014

최근 반도체 산업의 급속한 발전으로 반도체 생산 설비 시설 또한 꾸준히 증설되어가는 추세이다. 이에 따라 반도체 산업의 핵심기술로 부각되고 있는 진공 기술은 다양한 응용목적을 위한 진공시스템 설계와 운영을 필요로 한다. 진공시스템의 알맞은 설계는 시스템 구성에 따른 진공특성을 예측하는 것이 중요하며 목적에 부합한 진공펌프를 선택하고 운영하여 최소비용으로 시스템 활용효율성을 극대화할 수 있는 설계를 해야 한다. 또한 공정의 저전력, 대유량화 추세에 따라 고유량 영역의 드라이펌프 부하 내구성 대응 요구에 부응하는 객관적 내구성평가의 정립 및 표준 측정 시험평가 방법의 필요성이 점차 대두되고 있는 경향에 있다. 본 연구에서는 드라이펌프의 공정현장 적응능력 평가를 위하여 최소 1시간에서 3시간동안 압력별 가스부하에 따른 드라이펌프의 실시간 특성을 관찰하였다. 실험은 1 mbar에서 최대 300 mbar까지의 연속적인 부하 조건에서 유량, 진동, 소음, 소비전력과 Sudden Vent Test를 실시간으로 측정하였고 드라이펌프의 특성 분석은 각 용량별 압력에 따른 유량, DP BP 소비전력, 소음, 진동, DP Body Temperature 등의 데이터를 Type에 따라 비교 분석하였다. 이에 부응하는 평가 장치 구축 및 데이터분석은 한국표준과학연구원 진공펌프 평가실험실에서 수행되었다.

• Journal of Ocean Engineering and Technology
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• v.20 no.2 s.69
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• pp.22-28
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• 2006

The motion and wave drift forces of floating BBDB (backward-bent duct buoy) wave energy absorbers in regular waves are calculated, taking account of the oscillating surface-pressure due to the pressure drop in the air chamber above the oscillating water column, within the scope of the linear wave theory. A series of model tests has been conducted in order to order to verify the motion and time mean wave drift force reponses in regular waves at the ocean engineering basin, MOERI/KORDI. The pneumatic damping through an orifice-type duct for the BBDB wave energy device are deducted from experimental research. Numerical simulation for motion and drift force responses of the BBDB wave energy device, considering pneumatic damping coefficients, has been carried out, and the results are compared with those of model tests.

• Journal of Aerospace System Engineering
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• v.13 no.6
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• pp.52-59
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• 2019

The rotor blade is a key component that generates the lift, thrust, and control forces required for helicopter flight by the torque transmitted through the hub and the blade pitch angle control, and should be designed to factor vibration characteristics so that there is no risk of resonance with structural safety. In this study, the structural design of the main rotor blade for MPUH(Multi-Purpose Unmanned Helicopter) was conducted and the sectional stiffness measurement of the fabricated blade was performed. The evaluation of the vibration characteristics of the main rotor system was then conducted factoring the measured stiffness distribution. The interior of the rotor blade comprised of the skin, spar, and torsion box, and carbon and glass fiber composites were applied. The Ksec2D program was applied to predict the stiffness of blade, and the results were compared to the measured data. CAMRADII, a comprehensive rotorcraft analysis program, was applied to investigate the natural frequency trends and resonance risks due to the rotor rotation.

• Elastomers and Composites
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• v.35 no.2
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• pp.138-148
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• 2000

In order to investigate the possibility of EPDM micro cellular pad (MCP) as an impact sound insulation product, we studied static/dynamic properties and vibration transfer characteristics of EPDM MCP depending on shape, thickness, degrees of foaming by using material test system (MTS) and lab scale mock-up test apparatus. Static/dynamic rigidity is increased when shape is simple. thickness and degrees of foaming low. We could see that dynamic stiffness is proportional to the transmissibility of EPDM MCP. When dynamic stiffness is increased, characteristic peak at transmissibility curve moves high frequency range or snows increase of maximum value of transmissibility. For lab scale mock-up test and finite element method, EPDM MCP shows low vibration velocity and superior mode shape to just concrete plus slab structure. We could confirm that possibility of EPDM MCP as a impact sound insulation product is high.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.30 no.1C
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• pp.27-35
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• 2010

Instrumented steel sheet piles being driven by vibratory pile driver were installed in granular soil deposit and behaviors of the sheet piles were investigated. One of the instrumented steel sheet pile was installed without clutch and the other was installed with clutch. Sheet pile with clutch means that of installed in connection with pre-installed sheet pile. Penetration rates of sheet piles measured from depth measuring drum has shown that interlock friction had great effect on penetration speed of sheet pile. Clutch friction shows irregular distribution along the depths of penetration and its magnitude was estimated as 19.1kN/m. According to the accelerations obtained from accelerometer, it was seen that steel sheet pile behaviored nearly as a rigid body. Efficiency factor of an isolated sheet pile was 0.42 and that of the connected sheet pile was 0.71. Shapes of dynamic load transfer curves obtained from analysis of measuring devices was similar to those suggested by Dierssen.

• Journal of the Korea institute for structural maintenance and inspection
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• v.28 no.1
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• pp.46-52
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• 2024

The structural safety of expansion joints for piping systems has been drawing attention owing to ruptures and leaks of water pipes caused by earthquakes and road subsidence at soft ground. In general, metal bellows are installed as expansion joints to prevent various damages in the piping system. In this study, the seismic performance of a valve chamber system was evaluated by performing earthquake shaking table tests. To validate the benefits to structural safety of metal bellows in connecting steel pipes to valve chambers, the seismic tests were conducted on expansion joints (bellows) and general pipping, and the results were compared for durability. Strain gauges were attached to measure the effects of the input motion. As a result of the shaking table test, it was confirmed that the strain of the valve chamber structure and inflow or outflow steel pipes were decreased in 1/100, 1/20 by applied to the expansion joints.

• 전기의세계
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• v.38 no.1
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• pp.21-30
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• 1989

가스 절연개폐장치(GIS)에 있어서 단로기 또는 차단기의 개폐조작시나 자락고장이 생겼을 때는 급준과도전압(VFT)가 발생한다. 이 급준파의 크기는 단로기의 개폐조작시 재점호가 일어날 때가 대지절연파괴를 일으킬때의 극간전압차에 의하여 결정되며, 반사와 전반에 의해 중첩된 진행파로 되는 이른바 급준과도과전압(VFTO)로 된다. 이 VFT의 상승율은 표준뢰임펄스전압보다 크며, 최초의 파두장은 4-7[ns]의 것도 있다. 또 이 VFT전압은 GIS내부 뿐만 아니라 가공 송전선과 대지간, GIS의 용기와 대지사이 등 외부에도 나타난다. 따라서 GIS의 내부와 외부에서 VFT의 스트레스가 나타나므로 GIS의 설계시에 충분히 고려하여야만 된다. 지락고장에 의해 발생되는 용기과도전압(TEV)도 불꽃방전시에는 인가전압의 2배 정도로 되는 경우도 있으므로 절연설계 및 현장시험시에 고려할 필요가 있다. 단로기의 개폐조작시 발생하는 VFT의 피이크치를 최악의 경우로 상정할 때는 절연레벨을 상당히 저하시키며, 특히 GIS내에 돌기물과 같은 이물질이 존재하여 불평등전계를 형성할 때는 절연파괴전압이 대단히 전하된다. 변압기나 부싱 등과 같은 전력기기에서는 외함과 접지사이의 전압을 제한하여 설계할 필요가 있으며 용기와 대지사이의 외부과도과전압(FTO)를 저감시키기 위해서는 GIS의 외함을 각각 분할하여 제작할 필요가 있다.

• Journal of the Society of Naval Architects of Korea
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• v.39 no.1
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• pp.1-7
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• 2002

As the existing noise measuring device was affected the flow-field and structural vibration directly, new experimental device was required. Two Hydrophone Boxes are designed and their performances are investigated. The noise level of the KRISO cavitation tunnel is compared with those of the other cavitation tunnels which have been designed for the noise study. The present experimental results show the possibility of the full-scale prediction for propeller cavitation noise and the improvement of the measurement performance at the range of low-frequency.

• Journal of the Korean Society for Railway
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• v.12 no.5
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• pp.738-743
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• 2009

Personnel maintaining or repairing the railway tracks or signaling device around tracks may experience the sensory disorder when they do routine works for many hours and they may not recognize the leading to train accidents. In order to prevent such train accidents that may occur because railway track workers are unable to recognize the approaching train, a safety-equipment is developed to make the approaching train send signals. We developed the new alarm equipment for protection of trackside maintenance workers using radio signals.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.20 no.5
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• pp.13-19
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• 2019

After the Fukushima nuclear accident, a new power supply using a lithium polymer battery has been proposed the first time in the world as the safety of the emergency battery facility has been required. It is required to have the safety of the rack system in which the battery device is installed in order to apply the proposed technology to the field. Therefore, the purpose of this study is to evaluate the seismic performance of string and rack frame for lithium-polymer battery devices developed for the first time in the world to satisfy 72 hours capacity. (1) The natural frequency of the unit rack system was 9 Hz, and the natural frequency before and after the earthquake load did not change. This means that the connection between members is secured against the design earthquake load. (2) he vibration reduction effect by string design was about 20%. (3) As a result of the seismic performance test under OBE and SSE conditions, the rack frame system was confirmed to be safe. Therefore, the proposed rack system can be applied to the nuclear power plant because the rack system has been verified structural safety to the required seismic forces.