• Proceedings of the Korea Information Processing Society Conference
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• 2001.10b
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• pp.1319-1322
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• 2001

본 논문에서는 WAN 환경에서의 선도시험망 기반 QoS 테스트베드를 구성하고 차등화 서비스에 의한 QoS 의 성능을 측정하였다. 전송율, RTT, 패킷 손실, FTP 소요시간을 대상으로 QoS 보장 서비스와 베스트-에포트 서비스에 대한 성능을 비교 분석하였다. 모든 측정대상에 대하여 QoS 보장 트래픽이 좋은 성능을 보여주었으며, 특히 멀티미디어 어플리케이션의 비디오 트래픽에 대해서도 QoS 보장 서비스에 의한 전송서비스가 고품질의 영상을 제공하였다.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.26 no.9A
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• pp.1492-1498
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• 2001

DS-CDMA 시스템에서 다중 사용자간섭에 의한 성능 저하를 방지하기 위하여 비교적 구조가 간단하고, 성능이 우수한 병렬 간섭제거기가 이용된다. 본 논문에서는 병렬간섭제거기에 이용되는 기존 검파기의 파라미터의 최적화를 통하여 적응 병렬간섭제거기의 성능을 분석하고, 새로운 시험검파기인 HTNZ 검파방식을 제안한다. 적응 병렬간섭제거기는 기존의 부분 병렬간섭제거기에서 사용하는 고정된 값의 가중치를 NLMS 적응 알고리즘을 이용하여 적응적으로 계산하는 방법을 사용하였다. 시뮬레이션 결과 제안하는 방법이 기존의 hard 검파방식에 비해 사용자 용량이 57% 증가하는 향상된 결과를 얻었다.

• Korean Security Journal
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• no.36
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• pp.255-292
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• 2013

Burglary (also called breaking and entering and sometimes housebreaking) is a crime, the essence of which is illegal entry into a building for the purposes of committing an offence. It is one of the most common types of crime and also a serious issue for every society. A house that is left insecure is an accessible and attractive target for burglars and therefore burglary resistance test & certification system for doors and windows has been developed in many countries. This paper explores several advanced foreign burglary resistance test/certifcation cases (the British SBD, the Dutch KOMO SKH/SKG, the Japanese CP mark, the Australian Standard Certification) for security products and domestic test/certification systems for fire safety products as a comparative study so that any improvement points can be gained for South Korea in the field of security product performance. The comparative analysis results show that South Korea is far behind the security product certification system and needs a lot of improvement in the system by benchmarking foreign cases. The domestic test/certification systems for fire safety products also give some insights for burglary-related security products' performance certification system in Korea. Overall, the need for relevant rules and regulations, the establishment of standards regarding testing and certification, including certified security +hardware product in building security certification system, performance testing as well as production testing (i.e. quality management system evaluation), the basic competency of testers, incentive system for certified/high quality security products were suggested in order to make an optimal model for the security production performance testing and certification system in Korea.

• Resources Recycling
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• v.18 no.1
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• pp.44-51
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• 2009

The purpose of this study is to investigate the performance of shock absorption of recycled bumper applied to the standard of shock absorption for newly-developed bumper. For the experiment, two different passenger cars which have different types of bumper were selected. In this work, two kinds of reused bumpers were tested in accordance with an automotive safety regulation to verify exterior bumpers' impact energy absorption performance. The performance results of reused bumper test show that the shock absorption performance indicated the almost same performance and similar characteristics of 2.5 miles bumper test compared to the absorption performance of new bumper of test vehicles.

• Journal of the Society of Disaster Information
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• v.11 no.4
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• pp.607-614
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• 2015

This study evaluated the flexural performance of steel and PP fiber reinfroced shotcrete using round panel test according to ASTM that can consider the actual stress of fiber reinforced shotcrete in tunnel and under ground structures. The results of round panel test are converted to the square panel test results according to the EFNARC. The energy absorptions of each fiber reinforced shotcrete were classified according to the EFNARC toughness classification. Test results show that the PP fiber reinforced shotcrete has better flexural performance compared with the steel fiber reinforced shotcrete.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.31 no.10
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• pp.112-119
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• 2003

Design analysis and grow1d test on propellers for 50 m-long airship propulsion were conducted. The design analysis code developed by adopting the vortex-blade-element theory was applied to the design of optimum propeller at the condition of maximum flight speed at sea level. In order to validate the performance of the propeller, ground test of the propeller was performed, and thrust and torque were measured for several different pitch angles at static condition. The power coefficients and thrust coefficients obtained by the test compared well with the analysis results.

• Tunnel and Underground Space
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• v.20 no.5
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• pp.378-389
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• 2010

Submarine tunnels are affected by the surrounding environments more than regular tunnels. Especially, they are often vulnerable to damage by salt in seawater. Seawater is more likely to affect reinforcing rods and steel fibers than concrete. Recently the usage of anti-corrosive fibers increases in the tunnel which is subject to the possibility of damage. By comparing the capability of polypropylene fibers with that of steel fibers, the proper mixture ratio is decided and the supporting capability of polypropylene fibers was tested using round panel and beam specimens. The results of this study can be of great use in selecting the fiber material and designing of fiber reinforced shotcrete of submarine tunnels.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.19 no.4
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• pp.105-111
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• 2019

In this paper, a performance analysis of waveguide broad-wall slot array antenna for millimeter-wave seeker in Ka-band was performed as using near-field measurement. The measurement of slot array antenna was conducted in both far-field and near-field. And the validation of near-field test in millimeter band was confirmed. It was confirmed that the beam pattern characteristics including beam width and side lobe level of the slot array antenna that performed the verification were the same. Differenced in the side lobe level of azimuth and elevation beam pattern were verified to be less than 1dB. Additionally, the new antenna aperture distribution was extracted as using back-projection method modifying the near-field data and then introduced the method conducting performance analysis of array antenna.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.30 no.5
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• pp.118-126
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• 2002

The Altitude Engine Test Facility(AETF) was built at the Korea Aerospace Research Institute and has been being operated for the gas turbine engines in the class of 3,000 lbf thrust. To enhance the confidence level of AETF to the international level, a series of studies and facility modification have been conducted to improve the measurement uncertainty and reliability. In this paper, some part of the facility evaluation tests performed with a single spool turbojet engine are introduced. Tests were performed simulating the flight conditions as steady state, sea level for various flight speeds (i.e., Mn=0.3, 0.5, 0.7, 0.9). The obtained test results are compared with the predicted values of the engine DECK. The measurement uncertainties of airflow, net thrust, fuel flow and SFC showed 0.791~0.914%, 0.851~1.706%, 1.372~7.348% and 1.642~5.205%, respectively. Thus, from this research, the improvement methods of uncertainties on AETF has been confirmed.

• Journal of the Korea institute for structural maintenance and inspection
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• v.9 no.3
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• pp.87-92
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• 2005

The permeability of concrete affects largely on the durability of concrete, therefore it is required that the correct assessment and improvement of permeability. Therefore it is rational method that the permeability of concrete structures is estimated in the common use states under loading than in the early sound conditions. In this study, to improve the permeable efficiency of concrete, some kinds of fiber and resin are mixed in making of concrete specimens. And also, for the reasonable assessment of permeability, after 50% and 70% pre-loadings of its compressive strength were acted on the specimens, the tests were executed. From the results of this study, in the case of 50% pre-loading coefficients of permeability were increased about 1.4times against the nonpre-loading specimens and in the case of 70% pre-loading they were increased about 17.8times. And it turned out that hybrid steel fiber reinforcement is most effective for the improvement of permeable efficiency of concrete.