• Particle and aerosol research
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• v.7 no.3
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• pp.87-97
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• 2011

In this study, we organized the test results obtained from the performance tests for the CA certificated air cleaners which had been commercially available in Korea since 2003, and analyzed the correlation among the test parameters such as flow rate, particle collection efficiency, clean air delivery rate (CADR), ozone emission, odor removal efficiency and noise level etc. The noise level of 267 air cleaners were increased as concentrated at the 45, 50, 55 dB, which are the required noise level for CA certification according to flow rate, and ozone emissions from the CA air cleaners were significantly lower than the requirement limit, 50 ppb for 24 hour operation. The average particle collection efficiency and odor removal efficiency were 89.3 and 80.8%, approximately 20% higher than the requirement of CA certification, regardless of flow rates. The particle removal performance of an air cleaner was clearly discriminated by its CADR, and the CADR was obtained with a simple calculation: 0.79 x flow rate. The low differentiation of gas removal performance of air cleaners by the current CA gas test method was improved by 3.2, 751.3, 13.4 times for ammonia, acetic acid, respectively, by adopting the CADR concept and the real time measurement method, FTIR, for gas removal performance test.

• The Korean Journal of Applied Statistics
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• v.22 no.5
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• pp.961-969
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• 2009

Water absorption in water-cooled generator stator windings can cause serious accidents such as insulation breakdown and it brings a generator to the unexpected sudden outage. Accordingly, it is important to diagnose the water absorption of them in the effective operation of power plant. Especially, the capacitance value which is measured for diagnosis is very small so the special diagnosis methods like stochastic theory are needed. KEPRI developed the water absorption test equipment and diagnosis technology for them. In this paper we propose that water absorption test of generator stator windings using probability distributions. The proposed diagnosis technology is applied to the real system and the results of water absorption test for stator windings are agreed to them of water leak test.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.41 no.6
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• pp.495-501
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• 2013

Korean Utility Helicopter (KUH) has been designed to avoid the blade passing frequency and any instability due to a coupling of dynamic characteristics between the main rotor and the airframe in ground operation. For these design objectives, the vibration analysis and the ground resonance analysis were performed to analyze the dynamic characteristics of the airframe and the main rotor. Then, the whirl-tower test was conducted to identify the dynamic characteristics of the main rotor and the ground vibration test (GVT) was conducted to identify the dynamic characteristics of the airframe. The GVT for KUH was conducted with the test conditions and test articles established in consideration of each flight and ground condition. This paper shows the method and technique for performing the GVT for KUH and presents the correlation technique and the results for the correlated analysis model.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.24 no.6 s.177
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• pp.1398-1407
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• 2000

The structural steels of power plant show the decrease of mechanical properties due to degradation such as temper embrittlement, creep damage and softening during long-term operation at high temper ature. The typical causes of material degradation damage are the creation and coarsening of carbides(M23C6, M6C) and the segregation of impurities(P, Sb and Sn) to grain boundary. It is also well known that material degradation induces the cleavage fracture and increases the ductile-brittle transition temperature of steels. So, it is very important to evaluate degradation damage to secure the reliable and efficient service condition and to prevent brittle failure in service. However, it would not be appropriate to sample a large test piece from in-service components. Therefore, it is necessary to develop a couple of new approaches to the non-destructive estimation technique which may be applicable to assessing the material degradation of the components with not to influence their essential strength. The purpose of this study is to propose and establish a new electrochemical technique for non-destructive evaluation of material degradation damage for Cr-Mo steels which is widely used in the high temperature structural components. And the electrochemical anodic polarization test results are compared with those of semi-nondestructive SP test.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2009.11a
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• pp.353-358
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• 2009

For the successful development of 75 tonf class liquid rocket engine, a plenty of tests on each engine component has to be performed and this is equally true for a combustor. However the test facility which is in operation at Korea Aerospace Research Institute lacks its capacity to perform fire tests of a 75 tonf class combustor at its nominal thrust. Since the test facility has to be ready prior to the start of development tests, it is very urgent to establish the test facility. The preliminary design of a test facility for a 75 tonf class combustor which was performed according to the urgent necessity is described in the paper.

• The Journal of Korean Association of Computer Education
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• v.7 no.2
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• pp.77-84
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• 2004

In this thesis, We propose the self-directed learning and test-performing abilities assessment method to evaluate the learning and the test-performing abilities in which learners can not only control their own learning abilities for themselves, but also judge objectively learning and test-performing abilities. This method shows the membership degree of learning and test-performing abilities by using both the triangle-type membership function and the fuzzy logic. In addition, it gives the fuzzy grades to each item. The final membership degrees are calculated and the fuzzy grades are decided by the operation and composition of fuzzy relations on the membership degrees of learning and test-performing abilities. In this method, which is applicable to a writing subject for information searchers, learners are asked to analyse the membership degrees of the learning and test-performing abilities and the final fuzzy grades and to adjust a learning process for themselves.

• Journal of Korean Elementary Science Education
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• v.25 no.1
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• pp.27-38
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• 2006

The purpose of this study was to develop a test of a creative problem solving (CPS) for the selection of gifted science students in elementary school. For this, the methods and procedures of the selection of gifted science students was investigated through the internet homepages 23 gifted science education centers of universities and 16 city. province offices of education. The results of this study were as follows: Most of the gifted science students were selected through a multi-step examination process. They were selected on the basis of their records by recommendation of a principal or a classroom teacher in their school, by operation of standardized tests (ex. intelligence quotient score, achievements in science and mathematics, interest and attitude/aptitude for science as well as through other means), as well as through intensive observation of those gifted science students who are selected by interview and oral tests. The selection of gifted students was not evaluated through creativity testing; giftedness in city. province office of education. Testing of CPS was found to be especially lacking in these organizations. For the development of the test items of CPS in science, the five elements were extracted through the framework for the content analysis of the CPS: problem exploration, problem statement, solution thinking, experiment design, and assesment. In addition, suggestions were made regarding an appropriate scoring system for the test of the CPS. As the result of the developed test was applied to the 4th grade of the gifted and general student, we found that gifted students were superior to general students. In conclusion, it was that the CPS test developed in this study should be used to evaluate the CPS for the selection of gifted students.

• Proceedings of the KSME Conference
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• 2000.04a
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• pp.49-54
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• 2000

Cr-Mo-V steel is widely used as a material for the turbine structural component in fossil power plants. It is well known that this material shows the various material degradation phenomenons such as temper embrittlement, carbide coarsening. and softening etc. or ins to the severe operation conditions as high temperature and high pressure. These deteriorative factors cause tile change of mechanical properties as reduction of fracture toughness. Therefor it is necessary to evaluate tile extent of degradation damage for Cr-Mo-V steel in life assessment of turbine structural components. In this paper. the electrochemical potentiokinetic reactivation(EPR) test in $50wt%-Ca(NO_3)_2$ solution is performed to develop the newly technique for degradation damage evaluation of Cr-Mo-V steel. The results obtained from the EPR test are compared with those in small punch(SP) tests recommended by semi-nondestructive testing method using miniaturized specimen. The evaluation parameters used in EPR test are tile reactivation current density$(I_R)$ and charge$(Q_{RC})$ reactivation rate$(I_R/I_{Crit},\;Q_R/Q_{Crit})$. The results suggest that $I_R/I_{Crit}$ in these parameters shows a good correlation with SP test results.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.41 no.4
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• pp.289-295
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• 2005

This study is intended to provide navigator with specific information necessary to assist in the avoidance of collision and in operation of ships to evaluate the manoeuvrability of own ship. The actual manoeuvering characteristics of ship can be adequately judged from the results of typical ship trials manoeuvres. Author carried out sea trials based full scale for turning test, zig-zag test, spiral tests and crash-stop test at actual sea going condition. The turning circle manoeuvres were performed on starboard and port sides with $35^{\circ}$ rudder angle at the service speed, and Zig-zag procedures were performed on both sides with $10^{\circ}$ and $20^{\circ}$ rudder angle respectively. Spiral tests were carried out on the both sides and crash stop test was also carried out. The results from tests could be compared directly with the standards of manoeuverability of IMO and consequently the manoeuvring qualities of the ship is fully satisfied with its.

• Journal of the Korean Society of Propulsion Engineers
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• v.21 no.4
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• pp.1-11
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• 2017

TPTF (Turbopump Real Propellant Test Facility) at Naro Space Center has used alcohol burner system to simulate the gas flow of gas generator of liquid rocket engine. During the test at TPTF, the temperature and pressure at turbine inlet were smoothly increased while those of the gas generator of engine were constant. Present research developed a simulation code for the burner and the piping system and applied to the system. The calculation results were in good agreement with the test, and confirmed quantitatively that the non-steadiness is due to the heat transfer of the pipe. While the insulation of the pipe is ineffective, the length has a large impact on the turbine inlet condition. The present research clarified the empirically estimation of test condition, and can be applied to determination of the following test conditions.