• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• 2004.04a
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• pp.55-60
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• 2004

The paper describes measurement techniques for an acoustic transfer characteristic of ship's bridge stimulated by a whistle sound. The response sounds, according to the opening-shutting conditions of bridge doors for T／S ‘SAENURI’, are measured by B＆K 2260D equipment, and then extracted the frequency responses by B＆K 7830 software. To evaluate the measured transfer characteristic, the 128th order FIR (Finite Impulse Response) filters, containing the frequency characteristic, are constructed based on the frequency sampling-based design method. Using evaluation indexes with six scales, psychological assessments by five subjects are carried out with test sounds which are convolved source sound and FIR filters. As results of tests, the test sounds gives A／sub s／=3.3∼4.7 which means the psychological sense of 'it is almost similar sound as original ones in a real world', and thus it is cleary seen tint the proposed method can be suit for the measurement of an acoustic transfer characteristic of ship's bridg.

• Journal of the Korean Society of Propulsion Engineers
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• v.24 no.1
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• pp.9-16
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• 2020

A performance evaluation of the 200 N-class GCH₄/LOx small rocket engine was performed through ground hot-firing test. As a result, the combustion pressure and thrust raised with the increase of the oxidizer supply pressure, and thus the specific impulse, characteristic velocity, and their efficiency increased. The characteristic velocity was measured at about 90% performance efficiency. The change of chamber aspect ratio did not affect the performance of the rocket engine in the test condition specified. In addition, uncertainty evaluation was conducted to ensure the reliability of the test results.

• Communications for Statistical Applications and Methods
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• v.7 no.2
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• pp.447-456
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• 2000

In this paper, we considered three methods for outlier identification sample surveys. First, we studied method of handling and adjusting outliers in normal population. Second, we studied existing methods using mean, maximum and minimum and proposed a test using of median which well reflects characteristic of data regardless of sampling distribution. Finally, we showed our test using median works better than Dixon and mean test through simulation.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2012.10a
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• pp.587-591
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• 2012

Review of practical vibration test methods those applied in various industrial fields - such as automotive industry, electrics and electronics industry, defense industry and aerospace industry - is described on this paper. Swept sine test, random vibration test and advanced vibration techniques are explained according to their parametric values and also application fields of each test method are suggested by the characteristic of each method. For more proper application of each test method, standardized test specifications should be always reviewed and revised according to the transition of environmental factors.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.59 no.9
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• pp.1652-1657
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• 2010

This paper analyzes optimal stirrer parameter to improve field uniformity in a mode-stirred reverberation chamber. Stirrer parameter is varied about stirrer height and stirrer angle. Also we analyze quality factor, number of excited modes and stirrer efficiency that affect field uniformity. The results show good performance as higher as stirrer height. Isotropic field distribution is formed at $45^{\circ}$ stirrer angle. When stirrer angle varies, scattering characteristic of incident wave are changed. So electric field distribution in a mode-stirred reverberation chamber is also changed. Therefore, it affect field uniformity. The results expect to help that designs stirrer for get better field uniformity. Immunity test performed designed mode-stirred reverberation chamber for semiconductor that categorized by technology. Test result shows that good recurrence compared wave-guide immunity test.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2003.07b
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• pp.744-746
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• 2003

A ZnO varistor with reference voltage 250V/mm was fabricated through the control of particle size in slurry and the variation of sintering conditions. It was found that to measure the flatness of the V-I characteristic curve in the small-current region and the flatness of the V-I characteristic curve in a large-current region was improved nonlinearity of the fabricated ZnO varistor. According to the IEC 60099-4 was measured the accelerated aging test and high current test of the distribution class surge varistor which is excellent in respect to the property of ZnO varistor.

• Proceedings of the KWS Conference
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• 2006.05a
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• pp.68-70
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• 2006

For the aluminum material of the thick-thickness more than 100mm Penetration depth Electron beam welding is effectively applicable with a characteristic of high energy intensity. But Al 6061 alloy has high crack sensitivity due to minor alloys, which are silicon, magnesium, copper etc. With a sample block of 135mm thickness EBW test was performed in vertical position. As tensile strength has $210{\sim}220N/mm^2$ with weld area broken. Bend test shows low ductility with fracture of partly specimens. Chemical contents of alloys show no difference between weld and base metal. Defect in middle weld area figures out typical hot crack due to low melting materials. Micro structure of weld area has some difference compare to HAZ and base metal. As a result of EBW test for Al 6061 alloy, it shows that weld defect could be occurred even though establishing of optimum weld parameter condition.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.59 no.10
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• pp.1770-1775
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• 2010

An acceleration life test for rubber gasket of pole transformer was performed. The Arrhenius method was applied as an accelerated degradation test. The failure mode was considered as an elongation, and the failure mechanism is counted as a heat. It is found that both the current material(NBR: Nitrile Butadiene Rubber) and recommended alternative material(HNBR: Hydrogenated Nitrile Butadiene Rubber) have the same Weibull distribution as a life characteristic. For life expectation 95% reliability level of characteristic life is used at using temperature. The test results for NBR and HNBR are 7.7 years and 28.0 years on $50^{\circ}C$ of using temperature, respectively.

• Korean Journal of Veterinary Research
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• v.47 no.4
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• pp.437-441
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• 2007

The cases of feline panleukopenia virus (FPLV) infection were diagnosed in three imported cats. All cats died within one week after mild emaciation, depression and anorexia. One cat showed yellowish watery diarrhea. At necropsy, all cats had segmental hemorrhage on the serosa and mucosa of the small intestine. Histopathologically, severe diffuse necro-hemorrhagic enteritis was observed in small intestine especially in jejunum and ileum. The crypts of Lieberkuhn were dilated and contained necrotic epithelia. Severely damaged epithelia of crypts were transformed into bizarre shapes. Multifocal lympholysis and lymphoid depletion were found in Peyer's patches and other lymphoid tissues. Direct fluorescent antibody (FA) test revealed the characteristic FPLV antigen in the cytoplasms of crypt epithelial cells. Based on the clinical signs, characteristic pathologic findings and FA test, these cases were diagnosed as FPLV infection. In our best knowledge, this study is the first case report for FPLV infection in imported cats in Korea.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2005.10a
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• pp.440-443
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• 2005

Recently the usage of galvanealed steel sheet was increased in order to protect corrosion in automobile industry. So, the alternative of steel sheet was investigated in a point of formability. Generally it was known that uncoated steel sheet has better mechanical properties than coated steel sheet. But, contrary results were sometimes occurred in workplace. This reason is the effect of friction. In this study, the formability of steel sheet considering friction characteristics was investigated with tensile test, cup drawing test and finite element method.