• The Bulletin of The Korean Astronomical Society
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• v.41 no.2
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• pp.67.2-67.2
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• 2016

The Sun has diverse variations in solar atmosphere's layers due to solar activity. This solar variations can be recognized easily by sunspots which appear on the solar photosphere. Thus the sunspot on the photosphere is utilized by direct index of the solar activity. The other variation of the photosphere is center-to-limb variation (CLV). In this study, we analyze the relative intensity observed by SOHO, SDO. The data of photospheric intensity are from full disk images of SOHO/MDI intensity ($6768{\AA}$, from May 1994 to March 2011) and of SDO/HMI intensity ($6173-6174{\AA}$, from May 2010 to June 2016). As the result, we found the latitudinal variation of the intensity. The daily photospheric intensity showed the solar cyclic variation with sunspot number. It has a little difference of phase with sunspot number.

• Journal of Environmental Science International
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• v.19 no.1
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• pp.81-87
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• 2010

Cool island intensity urban green space was investigated based in Dalsung Park, that is one of the largest parks in Daegu. Cool island intensity(CII), which is defined as the temperature difference between the green space and its surrounding built-up areas, shows time variations. A through-year measurement(2008-2009) of ground level air temperature revealed seasonal variation and relationship to the atmospheric condition of CII. The temperature variation in the park and the reference downtown Daegu was as same order as CII. The noontime CII is larger in summer than that in winter due to the leaf fall of the park trees. On the other hand, seasonal variation of nighttime CII is not so clear. The nighttime CII was larger under the stable atmosphere.

• Journal of the Korean Society of Laryngology, Phoniatrics and Logopedics
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• v.8 no.1
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• pp.12-17
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• 1997

Measuring phonatory stability using MDVP(Multi-dimensional voice program, Kay Elemetrics Corp., NJ, USA) are becoming popular in many Korean clinics and laboratories, yet questions about standardization and reference values have remained. The purpose of present study was to examine the effects of frequency and intensity variation on the results of acoustic analysis related to phonatory stability. Twenty young adults(ten females and ten males) were asked to sustain vowel /a/ for more than 3 seconds under 9 different pitch and loudness conditions. Using MDVP, nine voice samples were analyzed, and jitter percent, fundamental frequency variation, shimmer percent, peak amplitude variation, noise to harmonic ratio, amplitude tremor intensity index, and degree of subharmonics were compared. The results showed that intensity changes can significantly affect various phonatory stability measures, and the lowest perturbation values can be obtained from slightly louder(10dB) phonatory condition than comfortable level phonation.

• Phonetics and Speech Sciences
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• v.2 no.4
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• pp.19-28
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• 2010

The purpose of this study was to increase the current understanding of the acoustic characteristics of voices with advancing age. The relationship between age-related changes in body physiology and certain acoustic characteristics of voice was studied in a sample of 80 men representing four chronological age groupings (20-29, 50-59, 60-69, 70-79) who were all of good physical condition. Each subject was asked to phonate the vowel /a/, /i/, and /u/ for as long as possible at comfortable frequency and intensity level and read the sentence. A promising voice analysis program (Multi-Dimensional Voice $Program^{TM}$) was used to measure the fundamental frequency ($f_0$), jitter, shimmer, $f_0$ variation, peak-amplitude variation, smoothed pitch perturbation quotient, smoothed amplitude perturbation quotient, soft phonation index, $f_0$-tremor intensity index, amplitude tremor intensity index, and noise-to-harmonics ratio from the samples.

• Journal of Welding and Joining
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• v.1 no.1
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• pp.37-46
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• 1983

This paper describes a study of fillet welded joint stressed perpendicular to the weld line. The finite element method was used to determine the stress intensity factor for cruciform joint at weld toe and root cracks according to variation of H/Tp, weld angle and main plate thickness. But, in this study, weld angle was fixed at 45.deg., since the variation of weld angle affect the stress intensity factor little, also main plate thickness was fixed. Pulsating tension fatigue test was done at the second phase of experiment. The work using the concepts of the fracture mechanics on the stable crack growth, was in the correlation of the experimental fatigue stress-life behavior because the fatigue behaviors of various joint geometries are related to the stress intensity factors calculated by F.E.M. analysis. Main results obtained are summarized as follows. 1) According to the propagation of toe crack, the variation of the stress intensity factor at root crack is obvious as H/Tp is smaller. 2) According to the propagation of root cracks, the change of the stress intensity factor of the toe is very large with propagation of root crack. 3) The calculation formula of the stress intensity factor of crack propagation at the root crack was obtained. 4) The calculation formula of the stress intensity factor at the toe cracks was obtained in similar manner. 5) From the results of experiment, the velocity of fatigue crack propagation at the weld toe and root was estimated.

• Journal of the Korean Geophysical Society
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• v.7 no.1
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• pp.11-21
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• 2004

The variation of geomagnetic field and absolute magnetic field at the geomagnetic observatory of King Sejong Station has been measured with 3-component ring core fluxgate magnetometer, proton magnetometer and D-I magnetometer. With data obtained from King Sejong Station during 2003, thediurnal and annual variations of geomagnetic field were researched and compared with those at other observatories. The deviation of daily variation of magnetic field in antarctica decreased gradually during winter season due to sun effect. The rates of componental annual variation of magnetic field at King Sejong Station were calculated using the least-square method under the assumption that the annual variation of magnetic field is linear. The rates are -55.93 nT/year in horizontal intensity, -0.87 min./year in declination, 58.30 nT/year in vertical intensity, and -69.85 nT/year in total intensity of magnetic field. A remarkable variation was caused by the magnetic storms occurred on 29~30 October, which were so powerful that the variation was observed in mid latitudes as well as high latitudes. The values of variation are generally 1500 2000 nT in Antarctica including King Sejong Station, 350 500 nT in East Asia. The measurement of absolute magnetic field shows that ring core fluxgate magnetometer has relatively large error range under cold temperature.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.20 no.7
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• pp.2159-2166
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• 1996

The stochastic properties of variation in fatigue crack growth are important in reliability and stability of structures. In this study,the stochastic model for the variation of fatigue crack growth rate was proposed in consideration of nonhomogeneity of materials. For this model, experiments were ocnducted on 7075-T6 aluminum alloy under the constant stress intensity factor range. The variation of fatigue crack growth rate was expressed by random variables Z and r based on the variation of material coefficients C and m in the paris-Erodogan's equation. The distribution of fatigue life with respect to the stress intensity factor range was evaluated by the stochastic Markov chain model based on the Paris-Erdogan's equation. The merit of proposed model is that only a small number of test are required to determine this this function, and fatigue crack growth life is easily predicted at the given stress intensity factor range.

• Journal of Astronomy and Space Sciences
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• v.35 no.4
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• pp.219-225
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• 2018

Cosmic rays are ions that move at relativistic speeds. They generate secondary cosmic rays by successive collisions with atmospheric particles, and then, the secondary particles reach the ground. The secondary particles are mainly neutrons and muons, and the neutrons are observed by the ground neutron monitor. This study compared the diurnal variation in cosmic ray intensity obtained via harmonic analysis and that obtained through the pile-up method, which was examined in a previous study. In addition, we analyzed the maximum phase of the diurnal variation using four neutron monitors with a cutoff rigidity below approximately 6 GV, located at similar longitudes to the Oulu and Rome neutron monitors. Expanding the data of solar cycles 20-24, we examined the time of the maximum cosmic ray intensity, that is, the maximum phase regarding the solar cyclic modulation. During solar cycles 20-24, the maximum phase derived by harmonic analysis showed no significant difference with that derived by the pile-up method. Thus, the pile-up method, a relatively straightforward process to analyze diurnal variation, could replace the complex harmonic analysis. In addition, the maximum phase at six neutron monitors shows the 22-year cyclic variation very clearly. The maximum phase tends to appear earlier and increase the width of the variation in solar cycles as the cutoff rigidity increases.

• Proceedings of the KSR Conference
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• 2010.06a
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• pp.1656-1662
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• 2010

Automatic train control systems are divided into ATC, ATP and ATS systems etc. The ATP and ATS systems offer discontinuous information for train control. While the ATC systems provide continueous information for train control. There is a method for offering continuous information by AF track circuits. Magnetic fields are formed by current through rails in the AF track circuit systems. So, the continuous information is received by the magnetic fields on a on-board antenna. Coating materials on rails are researched to decrease defects such as head check, shelling, corrugation, squats and so on in Germany. Currently, a coating method of rail construction is proposed by using the ceramics in Korea. When deciding physical characteristic of ceramics, researches are required about variation of flux density by the ceramics. In case that the flux density is much lower than existing value, the information for train control is not transmitted to the on-board antenna. In this paper, inductance on rails is calculated and a model is presented about variation of the magnetic field intensity in the AF track circuit. Standard permeability of ceramics is proposed by analyzing the variation of magnetic field intensity. It is demonstrated by using Maxwell and Matlab program.

• Journal of the Korean Institute of Intelligent Systems
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• v.24 no.5
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• pp.504-511
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• 2014

This paper presents a hybrid recognition method, which is based on the nonlinear histogram equalization and the multidimensional intensity variation of an images. The nonlinear histogram equalization based on a adaptively modified function is applied to improve the quality by adjusting the brightness of the image. The multidimensional intensity variation by considering the a extent of 4-step changes in brightness between the adjacent pixels is also applied to reflect accurately the attributes of image. The statistical correlation that is measured by the normalized cross-correlation(NCC) coefficient, is applied to comprehensively measure the similarity between the images. The NCC is considered by the intensity variation of each 2-direction(x-axis and y-axis) image. The proposed method has been applied to the problem for recognizing the 50-face images of 40*40 pixels. The experimental results show that the proposed method has a superior recognition performances to the method without performing the histogram equalization, or the linear histogram equalization, respectively.