• Structural Engineering and Mechanics
• /
• v.5 no.4
• /
• pp.471-490
• /
• 1997

In this paper, the classical Irons' patch tests which have been generally accepted for the convergence proof of a finite element are performed for Mindlin plate bending elements with a special emphasis on the nonconforming elements. The elements considered are 4-node and 8-node quadrilateral isoparametric elements which have been dominantly used for the analyses of plate bending problems. It was recognized from the patch tests that some nonconforming Mindlin plate elements pass all the cases of patch tests even though nonconforming elements do not preserve conformity. Then, the clues for the Mindlin plate element to pass the Irons' patch tests are investigated. Also, the convergent characteristics of some nonconforming Mindlin plate elements that do not pass the Irons' patch tests are examined by weak patch tests. The convergence tests are performed on the benchmark numerical problems for both nonconforming elements which pass the patch tests and which do not. Some conclusions on the relationship between the patch test and convergence of nonconforming Mindlin plate elements are drawn.

• Transactions of the Korean Society of Automotive Engineers
• /
• v.16 no.3
• /
• pp.144-150
• /
• 2008

This research aims to develop parts for advanced fuel/oil filtering re-circulation applicable to this kind of regulation proof engines. These parts can playa role of converting traditional air emission type crankcase into recovery type crankcase so that the engine can deal with environmental regulations, which do not allow minimal amount of toxic gas discharge. For the experiment, test method and specially made testing equipment are prepared. The results showed that oil separation efficiency of the cone type CCV(Crank Case Ventilation) system was higher than one of cylinder type both in bench test and in engine.

• Transactions of the Korean Society for Noise and Vibration Engineering
• /
• v.15 no.2 s.95
• /
• pp.213-218
• /
• 2005

It is well known that the loss factor and Young's modulus are fundamental mechanical properties of materials. Recently, the use of complex plastics is increasing for vibration proof. In this study, we evaluated two mechanical values of polycarbonate and acrylonitrile butadiene styrene by using two different standard test methods of ASTM E 756 and ISO 6721. Because damping properties of material generally depend on temperature, test specimen‘s temperature were controlled in the temperature range between - $10^{\circ}C\;and\;60^{\circ}C$. The results shown that the loss factor of polycarbonate gradually increased as increasing temperature, while the Young's modulus decreased. However, the loss factor and the Young's modulus of acrylonitrile butadiene styrene are varied somewhat at $60^{\circ}C$.

• Proceedings of the Korea Concrete Institute Conference
• /
• 1997.04a
• /
• pp.676-681
• /
• 1997

The purpose of this study is to evaluate the thermal Conductivity and Foolr Impact Sound of Polyurethane Concretes. The Polyurethane Concretes are prepared with various resin content, Fine and Coarse aggregates content, and its thickness, and tested for the Thermal Conductivity and Impact Sound. From the test results. the sound insulation grade of polyurethane concretes by the floor impact sound test on high frequency band is L-60, and its effect is considerable Polyurethane concretes have high degree of solidity compared with other heat shield materials, and its thermal conductivity is 0.05kcal/$mh^{\cire}C$. And it is suitable for sound proof floor materials.

• Tribology and Lubricants
• /
• v.16 no.3
• /
• pp.173-181
• /
• 2000

Friction, wear and corrosion characteristics of various MoS$_2$ bonded film lubricants were investigated to apply them to automotive wheel joints. MoS$_2$ bonded film lubricants were formulated by combinations of several additives and binders, and they were coated onto the pre-treated surfaces of specimens. Friction and wear characteristics were evaluated with Falex pin & vee-block test and LFW-1 block-on-ring test. For the corrosion resistant characteristics of the films, salt solution spray corrosion tests were performed. Results showed that MoS$_2$ bonded films containing both inorganic and organic corrosion-resistant additives yielded a synergy effect on anti-corrosion resistance. Also, binders having the better water-proof and thermal stability showed the lower friction and higher corrosion resistance.

• Journal of the Korean Geotechnical Society
• /
• v.26 no.7
• /
• pp.161-170
• /
• 2010

For the development of load and resistance factor design, reliability analysis is required to calibrate resistance factors in the framework of reliability theory. The distribution of measured-to-predicted pile resistance ratio was obrained based on only the results of load tests conducted to failure for the assessment of uncertainty regarding pile resistance and used in the conventional reliability analysis. In other words, successful pile load test (piles resisted twice their design loads without failure) results were discarded, and therefore, were not reflected in the reliability analysis. In this paper, a new systematic method based on Bayesian theory is used to update reliability indices of driven steel pipe piles by adding more proof pile load test results, even not conducted to failure, to the prior distribution of pile resistance ratio. Fifty seven static pile load tests performed to failure in Korea were compiled for the construction of prior distribution of pile resistance ratio. The empirical method proposed by Meyerhof is used to calculate the predicted pile resistance. Reliability analyses were performed using the updated distribution of pile resistance ratio. The challenge of this study is that the distribution updates of pile resistance ratio are possible using the load test results even not conducted to failure, and that Bayesian updates are most effective when limited data are available for reliability analysis.

• Journal of the Korean Society for Aeronautical & Space Sciences
• /
• v.38 no.6
• /
• pp.605-611
• /
• 2010

The geostationary satellite COMS is going to be launched in 2010, and, in the series of test, there are some high-pressure tests concerning the vessel tank filled with helium gas of hundreds atmospheric pressure. In this paper, authors evaluates risk associated with accidental rupture of the test system. Two possible scenarios are considered: 1) the 310-bar helium tank ruptures at the center of the acoustic chamber, and 2) the 116-bar reduced-pressure helium tank ruptures in the test room shielded by bullet-proof glasses. Using the theory of blast wave propagation and computational simulation, the dynamics of wave reflected in a confined space is investigated for highly complex unsteady flow physics.

• Journal of the Korean Society for Aeronautical & Space Sciences
• /
• v.30 no.6
• /
• pp.31-38
• /
• 2002

This paper presents the analysis of the flight test data measured by the sensors installed on a four-seat canard aircraft. The inherent stall proof characteristics of canard aircraft was verified from the stall test. The dihedral effect, adverse yaw and roll control power were examined and the neutral point that determines the longitudinal stability of the aircraft was investigated. The dynamic characteristics such as dutch roll mode were also examined. Without relying on the parameter identification method, the aerodynamic derivatives or the relations between the aerodynamic derivatives were obtained by analyzing the steady state flight data.

• Proceedings of the Korean Society of Propulsion Engineers Conference
• /
• 2009.11a
• /
• pp.293-297
• /
• 2009

Valves, which are used to supply or block the flow of cryogenic pressurant in the pressurization system of liquid-propellant propulsion system in a launch vehicle, are pneumo-actuated valve, solenoid valve, pyro-valve, etc. Both pneumo-actuated valve and solenoid valve have more complex structure and are heavier than pyro-valve. For this study, a couple of pyro-valves, which are applicable to cryogenic and high-pressure fluid (cryogenic gaseous helium), have a simple structure, and are comparably light, are designed, manufactured, and tested (proof-pressure/leakage tests, performance test, vibration test, helium supply tests).

• Current Optics and Photonics
• /
• v.1 no.5
• /
• pp.538-543
• /
• 2017

Progressive addition lenses (PAL) have very wide application in the modern glasses market. The unique progressive surface can make a lens have progressive refractive power, which can meet the human eye's different needs for distance-vision and near-vision. According to the national glasses fabrication standard, the difference between actual optical power after fabrication and nominal design value should be less than 0.1D over the lens effective area. The optical power distribution of PAL is determined directly by the surface. Consequently, the surface processing accuracy requirement is proposed. Beginning from the surface expressions of progressive addition lenses, the relationship equations between the surface sag and optical power distribution are derived. They are demonstrated through tolerance analysis and test of an example progressive addition lens with addition of 2.09D (5.46D-7.55D). The example addition surface is fabricated under given accuracy by a single-point diamond ultra-precision machine. The optical power of the PAL example is tested with a focal-meter after fabrication. The optical power addition difference between test result and design nominal value is 0.09D, which is less than 0.1D. The derived relationship between the surface error and optical power is verified from the PAL example simulation and test result. It can provide theoretical tolerance analysis proof for the PAL surface fabricating process.