• 대한기계학회논문집B
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• 제22권8호
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• pp.1052-1063
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• 1998

The performance database of small-sized centrifugal compressors is needed for the design of high performance machines and also for the verification of design tools and analysis software. An impeller is designed, manufactured and tested. The effects of several parameters on the evaluation of performance are investigated and the performance test of parallel diffuser is also carried out. The proper estimation of static pressure, total temperature and blockage at the impeller exit is important for performance evaluation. 4 method in cooperation with 3-D calculation is suggested. The measured performances are in a good agreement with the predicted results. However, there are some discrepancies in efficiency.

• 한국기계가공학회지
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• 제18권12호
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• pp.104-110
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• 2019

A nanosatellite designed by the Korea Microgravity Science Laboratory (KMSL) is currently under development. The KMSL nanosatellite is designed to perform two different scientific missions in space. To successfully complete missions, a variety of tests must be conducted to verify the performance of the designed satellite before launch. As part of the qualification test campaign, the KMSL nanosatellite underwent high level vibrational tests (to comply with Falcon 9 qualification level) to demonstrate the integrity of the system. The purpose of this study is to demonstrate that the primary structure and all electronic and mechanical components can withstand the vibrations and the loads experienced during the launch period. To this end, the KMSL nanosatellite was exposed to static and dynamic loads and various types of vibrations that are inevitably produced during the space vehicle launch period. The vibration test results clearly demonstrated that all avionics and mechanical components can withstand the vibrations and the loads applied to the KMSL nanosatellite's body through a Pico-satellite Orbital Deployer (POD).

• 한국전기전자재료학회논문지
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• 제26권9호
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• pp.662-668
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• 2013

Reported here are results of the mechanical and electrical properties of both of intact and thermally degraded epoxy-coated copper busducts that are made by fluidized bed process. To elucidate and compare the properties mentioned above, electrical breakdown by thermal and water aging, v-t characteristic, bending test, impact test and cross cut test are carried out. Although the performance of electrical and mechanical properties are gradually decreased in increasing the severe conditions such as temperature, aging time, and so forth, sample C has a better performance in both mechanical and electrical properties.

• Wind and Structures
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• 제29권2호
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• pp.87-98
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• 2019

As a regenerated turbulent wind field process, wind tunnel test has proven to be a promising approach for investigating the transmission tower-line system (TTLS) performance in view of experimental scaled models design, simulation techniques of wind field, and wind induced responses subjected to typhoon. However, the challenges still remain in using various wind tunnels to regenerate turbulent wind field with considerable progress having been made in recent years. This review paper provides an overview of the state-of-the-art of the wind tunnel based on active or passive controlled simulation techniques. Specific attention and critical assessment have been given to: (a) the design of experimental scaled models, (b) the simulation techniques of wind field, and (c) the responses of TTLS subjected to typhoon in wind tunnel. This review concludes with the research challenges and recommendations for future research direction.

• Nuclear Engineering and Technology
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• 제55권7호
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• pp.2642-2649
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• 2023

A real-time unmeasured dynamic response prediction process for the nuclear power plant pressure pipeline is proposed and its performance is tested in the test-loop system (KAERI). The aim of the process is to predict unmeasurable or unreachable dynamic responses such as acceleration, velocity, and displacement by using a limited amount of directly measured physical responses. It is achieved by combining a well-constructed finite element model and robust inverse force identification algorithm. The pressure pipeline system is described by using the displacement-pressure vibro-acoustic formulation to consider fully filled liquid effect inside the pipeline structure. A robust multiphysics modal projection technique is employed for the real-time sensor synchronized prediction. The inverse force identification method is also derived and employed by using Bathe's time integration method to identify the full-field responses of the target system from the modal domain computation. To validate the performance of the proposed process, an experimental test is extensively performed on the nuclear power plant pressure pipeline test-loop under operation conditions. The results show that the proposed identification process could well estimate the unmeasured acceleration in both frequency and time domain faster than 32,768 samples per sec.

• 설비공학논문집
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• 제25권8호
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• pp.438-442
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• 2013

The alternative refrigerant R436B is applied, to assess the application feasibility for a commercial cooling water system. The characteristic stability was verified by Sealed glass tube test and Autoclave test. R436B is chemically stable with the compressor material. The Oil miscibility test shows the usual compressor oil mixed well with R436B. Through the life acceleration test, the cooling performance is maintained. Though slight changes in oil and capillary tube diameter were found, they were within the permitted range. R436B should be applied to commercial cooling water systems as a simple replacement for the usual refrigerant.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2001년도 춘계학술대회논문집E
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• pp.668-671
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• 2001

For the saving of energy consumption, it is necessary that the high efficient energy transfer machine. We found the optimum operating condition of screw water chiller during this performance test. The specifications of compressor for this performance test are as follows. Built-in volume ratio; Vi=2.4, using refrigerant; HCFC-22, nominal motor output; 60kW(80Hp). We found the test results on water cooled chiller standard test condition that the evaporating capacity is increased 8% maximum and 5.6% under same operating condition. and COP is increased 11 % max. and 8% under same operating condition with change of the evaporating inlet/outlet condition. For the results of these test, we can estimate the optimum operating condition of water cooled type screw chiller.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2002년도 학술대회지
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• pp.427-430
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• 2002

The present parer outlines the system identification and vibration control performance of air traffic control tower of Yangyang international airport with tuned mass damper(TMD). From the free vibration test, natural frequency, damping ratio and mode shape of tower are obtained and these values are compared with the values from numerical analysis. In the vibration control test to evaluate the vibration control performance, equivalent damping ratio increased by tuned mass damper are obtained in case the TMD is operated as passive mode. Damping ratio of tower evaluated from free vibration test is about $1.0{\%}$. It is very low value than damping ratio recommended in general code. Damping ratio of passive mode is about $5{\%}$. These equivalent damping ratio increased by TMD is enough to enhance the serviceability of tower structure under wind load.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2004년도 춘계학술대회
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• pp.745-750
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• 2004

For the safety of railway, it should be evaluated for the running safety by measuring the derailment coefficient. Although railway has run the fixed and maintained rail, some of railway is derailed. This report shows the results that performed the static load test, wheelset manufacturing for test, main line running test on the basis of the derailment theory and experience. It is executed main line test into more than 80km/h for estimating the curving performance and running safety of Gwangju EMU. As the test results, could confirm the curving performance and running safety of Gwangju EMU from the results of the wheel unloading, lateral force, derailment coefficient etc. Derailment coefficient was less than 0.8, and lateral force allowance limit and wheel load reduction ratio were enough safe.

• 한국산학기술학회논문지
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• 제11권3호
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• pp.787-794
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• 2010

본 논문은 육상트랙용 복합탄성포장재의 고무칩층의 최적 배합조건을 결정하기 위하여 기계적 및 동적 성능에 대한 각 구성요소의 영향을 평가한 것이다. 이에 소요되는 시험 횟수의 최소화를 위하여 실험계획법을 적용하였으며 이에 따라 기계적 및 국제육상연맹(IAAF)에서 요구하는 동적성능에 대한 시험을 수행하였다. 마지막으로 반응표면법을 이용하여 기계적 특성 및 동적 성능을 최적화하기 위한 배합조건을 결정하였다.