• Journal of the Korean Society of Fisheries and Ocean Technology
• /
• v.40 no.2
• /
• pp.138-143
• /
• 2004

This experimental paper deals with the performance of tanks that are turned the active A.R.T(Anti-Rolling Tank) when the fluid transfers from wing tank to the opposite tank by the power developed by the automatic control system (INTERING Stabilizer), which was installed in the fishery training ship T/S. A - RA (G/T:990 tons) of Cheju National University. In this paper, the author has tested the performance of INTERING Stabilizer for the signals obtained by the inclinometer in irregular waves and compared with the results obtained in passive mode operation at stop and at various ship speeds. The performances of the system were confirmed the results as follows through the tests: 1. The average amplitude and significant roll (${\pi}$1/3) of the passive and active mode operations in the condition of stoped engine and underway were obtained 8.30$^{\circ}$, 4.37$^{\circ}$, 8.30$^{\circ}$, 4.37$^{\circ}$, and 5.01$^{\circ}$, 4.36$^{\circ}$, 5.50$^{\circ}$, 5.10$^{\circ}$, respectively. 2. The rates of performance of active mode operations were carried out during a sea trial in the condition of stop engine and underway resulted in 47.5%, 12.7%, respectively, therefore the active mode operation estimated to be improved more than passive mode operation. 3. Active - A.R.T by INTERING Stabilizer didn't affect the amplitude of pitching.

• Korean Journal of Optics and Photonics
• /
• v.9 no.3
• /
• pp.142-145
• /
• 1998

It is shown that the optical system with Gaussian pupil e, diffraction amplitude distribution is not affected by the presence of residual aberrations. The case of spherical aberration is treated, as an example, and the complex diffraction amplitude distribution at the neighbourhood of the image point is described analytically by using a recurrence formula.

• The Journal of the Acoustical Society of Korea
• /
• v.9 no.6
• /
• pp.15-21
• /
• 1990

유-무-묵음 분류 과정은 음성분석시에 아주 중요한 문제중의 하나이다. 음성에너지, ZCR, 자기 상관계수, LPC 계수, 예측에러 에너지등을 퍼래미터로 사용하여 지금까지 많은 분류기법이 제안되어져 왔다. 이런기법들은 기본적으로 퍼래미터를 추출해야 하고, 이 때문에 많은 계산량이 요구되고, 이들 퍼 래미터는 음성 본래의 정보들의 대부분을 상실하게 된다. 이 때문에 각 프레임의 진폭분포를 사용하는 새로운 앨고리즘을 제안하였다. 첫째로 V-U-S 영역은 개별 진폭분포형태를 가지기 때문에 주어진 프레 임에서 진폭분포를 구한다. 그런 다음에는 신경망을 통해 분류를 하게 된다. 신경망은 문덕값을 별도로 선정할 필요없고, 배경잡음에 강력하며, 또한 실시간 처리에 적합하다.

• 한국해양학회지
• /
• v.29 no.1
• /
• pp.28-41
• /
• 1994

The hourly sea level data are analyzed in order to find the general characteristics of the storm surges at the coasts of Korea, Japan and Russia. the surges are calculated by removing the predicted tides from the observed sea level at 44 tidal stations. In korea, positive and negative surges of the west coast are larger than those of the south and east coasts. The magnitudes of negative surges are larger than those of positive surges at the west of Japan. The surges of the northern Russian coast are relatively larger than those of the southern west coast of japan. The yearly maximum positive surges at the west coast of Korea, are found to be caused by extratropical storm, but the maximum positive surges at the south or the east coast of Korea are due to the summer typhoon. Mostly the yearly maximum negative surges occur at the west coast of Korea (particularly Inchon), and they are caused by extratropical storm.

• Journal of Digital Convergence
• /
• v.19 no.12
• /
• pp.339-345
• /
• 2021

In this paper, estimation angle performance analysis of amplitude-comparison monopulse radar under additive noise effect is dealt with. When uncorrelated white noises are added to the squinted beams, the angle estimation performance is analyzed through the mean square error(MSE). The numerical integration-based mean square error result completely overlaps the Monte Carlo-based mean square error result, which corresponds to 99.8% of the Monte Carlo-based mean square error result. In addition, the mean square error analysis method based on numerical integration has a much faster operation time than the mean square error method based on Monte Carlo. the angle estimation performance of the amplitude comparison monopulse radar can be efficiently analyzed in various noise environments through the proposed numerical integration-based mean square error method.

• Proceeding of EDISON Challenge
• /
• 2016.03a
• /
• pp.548-553
• /
• 2016

본 연구는 타원형 물체가 유체 중에서 침강할 때 물체의 형상과 밀도에 따른 침강특성을 분석하는 것이며, 이로 인해 종단속도에 미치는 영향을 평가하는 것이다. 복잡한 형태의 물체를 타원기둥으로 단순화하였고, 낮은 Reynolds 수(=0.5~100)에 대하여 연구를 진행하였다. 또한 침강형태가 종단속도에 미치는 영향을 연구하였다. 수치해석 검증을 통해 정확하고 효율적인 격자 크기를 결정하였다. 정확한 분석을 위해 단순히 종단속도의 변화를 본 것이 아니라 진동하지 않은 물체의 이론적 속도와 비교하여 이와 얼마나 차이가 있는지를 확인하였다. 수치해석 결과 장단축비에 따라 물체의 침강특성이 크게 변하였고 그 경향은 밀도비에 따라 다른 양상을 보였다. 또한 각의 진동에 대한 진폭과 진동수가 물체의 침강속도에 영향을 주는 것을 확인하고 그 원인에 대해서도 연구하였다.

• Korean Journal of Optics and Photonics
• /
• v.9 no.5
• /
• pp.277-281
• /
• 1998

One dimensional inhomogeneous aperture modulation effects on the MTF of optical system was investigated. The lens under test was a doublet made in Korea. It has 10 mm effective diameter, 87.8 mm effective focal length. The ray-fans and spot diagrams were calculated and presented on the picture for on-axis and off-axis (field of view, $1^{\circ}$ and $2^{\circ}$). Aperture modulation was carried out by positioning a aperture modulator close contacter with the lens under test. We bought two modulators from Edmud Company in U.S.A. One was linear type and the other was stepped type. The MTFs were measured on the best of focus for each modulated aperture where the MTF has the highest value for 60 line/mm and were compared with one another. For on-axis, the MTFs of some modulated apertures had higher values than the MTF of unmodulated aperture in the high frequency region. In the case of off-axis, at the field of view $1^{\circ}$, the MTF values of some modulated aperture are improved prominently and some other one are disimproved. At the field of view $2^{\circ}$ most of the MTFs of modulated apertures had lower values than the MTF of unmodulated aperture except the MTFs of linear and inverse linear type aperture in the high frequency area. But the values of MTFs in high frequency region were too low for actual use.

• Journal of the Korean Society for Nondestructive Testing
• /
• v.18 no.1
• /
• pp.1-9
• /
• 1998

The attenuation of acoustic emission (AE) waves was evaluated for injection-molded short-fiber-reinforced thermoplastic composites employing simulated AE waves. Values of attenuation coefficient (${\alpha}$) decreased more with increasing fiber volume fraction ($V_f$) than that expected from a simple linear relation between ${\alpha}$ and $V_f$. The effect of wave attenuation was taken into account in a quantitative analysis of the AE peak amplitude distribution which was obtained from each zone partitioned in a specimen gage portion. The amplitude distribution compensated for the measured attenuation loss was exhibited almost similar in every zone of the specimen. Consequently, it was, shown that the AE amplitudes obtained from fiber/plastic composites were considerably affected by the attenuation.

• Journal of Convergence for Information Technology
• /
• v.11 no.11
• /
• pp.51-56
• /
• 2021

In this paper, performance degradation in the cross-eye jamming due to amplitude mismatch of two jamming antennas is considered. The mismatch of the amplitude ratio is modeled as a random variable with a normal distribution of the difference between the actual amplitude ratio and the nominal amplitude ratio due to mechanical defects. In the proposed analytic performance analysis, the first-order Taylor series expansion and the second-order Taylor series expansion is adopted. Performance measure of the cross-eye jamming is the mean square difference (MSD). The analytically derived MSD is validated by comparing the analytically derived MSD with the first-order Taylor series-based simulation-based MSD and the second-order Taylor series-based simulation-based MSD. It shows that the analysis-based MSD is superior to the Monte-Carlo-based MSD, which has a high calculation cost.

• Computational Structural Engineering
• /
• v.6 no.4
• /
• pp.10-13
• /
• 1993

본 고에서는 불확정적 Approach에 의한 구조물 거동파악의 일례를 소개한다. 이 예에서는 극치통계와 엔트로피 최대원리를 이용하여, 부동침하를 받은 쉘구조물의 응력을 추정하는 이론을 취급한다. 부동침하는 불확정적 특성을 비교적 많이 지니고 있으며, 특히 구조물을 지지하고 있는 지반의 경우는 그 물리적 정수와 침하특성이 확정론적으로는 취급이 곤란한 경우가 많다고 생각된다. 구체적으로 극치통계법에서는 부동침하를 기초 Ring의 원주방향으로의 Fourier 계수로 가정하여, 위상각과 침하의 2승평균치가 확정치로 주어졌을 때, 진폭 Spectrum을 불확정변수로 간주하여 추정하는 방법을 소개한다. 일단 진폭 Spectrum이 구해지면 응력은 간단히 구해지므로 여기서는 Spectrum에 관해서만 언급하기로 한다.