• KSCE Journal of Civil and Environmental Engineering Research
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• v.28 no.3A
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• pp.401-406
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• 2008

This study can be used to produce structurally efficient recycled PET fiber from used waste PET bottles and evaluated the bond performance of the three type of recycled PET fiber and cement matrix. Also, the flexural tests were performed on concrete reinforced using the three type of recycled PET fibers. The test results showed that the recycled PET fiber was significantly increased bond strength. The flexural test results are demonstrated that recycled PET fibers improved the flexural toughness of concrete. Based on the bond and flexural test results, the bond and flexural performance of embossed type recycled PET fibers were significantly better than those of the other shape fibers.

• Journal of the Society of Naval Architects of Korea
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• v.35 no.4
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• pp.11-18
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• 1998

This study describes sea trial tests for a waterjet propulsion system attached in the hybrid super high speed cargo ship named "Narae". A measuring technique of jet velocity, gross thrust and impeller torque for the waterjet system is explained. From the measured data in sea trial test, performance of the waterjet propulsion system is analyzed and compared with model test results of a similar waterjet system which was carried out in 1996. The erective horse power estimated from sea trial tests shows a good agreement with resistance test results of the model ship. The optimum rising height is estimated as 0.75 m, and the overall efficiency of the waterjet system is predicted as 0.315 at 15 knots. Useful data such as the pump performance, the jet efficiency, the losses of inlet duct and nozzle were obtained. Test results show a similar behavior to the model test results.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.18 no.2
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• pp.191-200
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• 2005

To develop composite bridge deck, comparative study on the flexural characteristics of deck fabricated with filament winding and pultrusion was performed. In this study, composite deck of triangular shape was fabricated with filament winding process and flexural tests were conducted along with pultruded 'Duraspan' deck. Failure load, maximum deflection and strains were compared with each other. Also finite element analysis for filament winding deck was carried out and the results were compared with those from experiments.

• Journal of the Korean Society of Marine Environment & Safety
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• v.27 no.6
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• pp.744-753
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• 2021

This study suggests ways to improve the standard test method and judgment criterion for the "Eco-toxicity Test" based on the rules and regulations provided in 'performance and qualifying test standards for marine pollution prevention materials and chemicals' in the Republic of Korea. Compared with the relevant references of other countries, this study attempted to find the limitations in the existing standards. As for the growth inhibition test of algae using Skeletonema costatum as an indicator, applying comparative analysis to measure specific growth rates, together with statistical analysis, instead of applying current methods, judged by the appearance of colors from the culture medium was suggested. Considering the exponential growth phase of the test species, the test duration was suggested to be reduced to less than four days. For the test with fish as an indicator, resetting the appropriate body size was suggested to, show consistent sensitivity against chenicals applied during testing. Furthermore, it is necessary to consider the criteria needs, which should be established in reasonable and objective ways. For the testing species, marine rotifer, Brachionus plicatilis could be a replacement for Artemia sp., and a bivalve for fish in the test. To improve the performance effectiveness of the "Eco-toxicity test", it is worth considering the designation of accredited testing institutes, by placing it in the same loop. Thus it is also expected to have a reliable management system in place, having the capacity of cost calculation properly and adjusting testing items if required.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2001.04a
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• pp.17-20
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• 2001

Combustion characteristics of KSR-III liquid rocket engine are investigated numerically in the standpoints of engine performance and acoustic instability. In the present calculation, engine performance for design and off-design conditions is estimated effectively with reasonable error. Numerical results of acoustic instability show that engine operation for the design condition has sufficient stability margin, but for a certain off-design condition, acoustic instability can be triggered by artificial pressure perturbation. The present results are in a good agreement with the available experimental results and can be adopted for the prediction of engine performance and stability, depending on the specific operating condition.

• Proceedings of the KIEE Conference
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• 2009.07a
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• pp.1291_1292
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• 2009

볼프레셔 시험은 세라믹 재료를 제외한 비금속 재료의 내열성을 시험하는 방법중의 하나이다. 본 볼프레셔 시험과 관련된 규격으로는 IEC 60695-10-2의 국제 규격이 있으며, 국내에는 KS C IEC 60695-10-2의 한국산업 규격이 있다. 본 논문에서는 볼프레셔의 성능확인 시험으로써, IFM이 제공한 시료를 가지고 자국의 형태 및 자국의 크기 등의 분석 방법에 대한 비교숙련도 시험에 관하여 논하였다.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2011.11a
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• pp.784-788
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• 2011

Wind tunnel test on 20" class propellers are carried out at KARI's low speed wind tunnel (LSWT). The test was done to select most efficient propeller for middle size electric propulsion UAV of KARI. The propellers are commercially available 20" class folding type propellers made of carbon fiber composite material. As the result, 21"${\times}$15.5" propeller was selected whose efficiency is 66% at cruise condition.

• Proceedings of the Computational Structural Engineering Institute Conference
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• 2010.04a
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• pp.500-503
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• 2010

본 논문에서는 산업용 용접구조물의 피로성능 평가를 위한 시간 및 비용 절감형 전산피로시험법을 개발한다. 임의의 하중에 놓인 용접구조물의 성능저하 현상(균열발생 및 진전 등)을 손상역학에 기반하여 역학적으로 기술하고 자체개발한 유한요소해석코드에 탑재하여 이를 전산적으로 시뮬레이션한다. 정도 높은 용접구조물 전산피로시험법의 개발을 위해 용접잔류응력과 재료파라미터를 자체개발한 유한요소해석코드를 통해 구현한다. 개발된 전산피로시험법은 용접구조물의 피로시험 결과와 비교함으로서 제안 기법의 적합성 및 유용성을 검증한다.

• Aerospace Engineering and Technology
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• v.1 no.1
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• pp.28-41
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• 2002

The purpose of this paper is to show and define the performance, the system mechanization and the algorithm of the Strapdown Inertial Navigation System(SDINS). First, navigation equations are derived in the Earth Fixed mechanization and this mechanization apply to the two kinds of inertial measurement units which consist of same fiber optic gyros and different accelerometers(SDINS-1 and SDINS-2). Those two accelerometers have the different bias. To evaluate its performance, two kinds of tests have been performed - static motionless test, and rectangle-route moving test. The results of the moving test are compared with the results of Differential GPS which has an accuracy with ±2.0mm. and are presented in this paper.

• Journal of Korean Tunnelling and Underground Space Association
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• v.13 no.3
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• pp.243-260
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• 2011

To predict TBM performance in design stage is indispensable for its successful application. The NTNU model, one of the representative TBM performance prediction models uses two distinct parameters such as DRI and CLI obtained from three different tests on bored rock cores. Based on DRI and CLI, it is possible to predict TBM advance rate and cutter life in the NTNU model. In this study, NTNU testing methods and their related testing equipments were introduced to measure DRl and CLI for the NTNU model. Then, in order to derive their relationships, the two key parameters measured for 39 domestic rocks were compared with physico-mechanical properties of rock such as uniaxial compressive strength and quartz content. Lastly, the experimental results were also compared with NTNU database to verify their reliability.