• 지구물리
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• 제4권1호
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• pp.47-55
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• 2001

한반도를 중심으로 32～44°N, 123～133°E 사이에서 발생한 지진 중 M_0와 함께 m_b 또는 M_s가 결정된 50개의 계기지진을 이용하여 실체파(m_b), 표면파(M_b), 또는 둘 다로부터 지진 모멘트(M_0)를 계산하는 환산식을 개발하였다. 진원깊이 70km 이상은 심발지진으로, 이하는 천발지진으로 분류하였으며, M_0의 단위는 dyne-cm이다. 표면파규모의 경우 심발지진이 천발지진보다 큰 지진모멘트를 갖는 것으로 나타났다. 심발지진과 천발지진 환산식에 수반된 표준편차는 모멘트 규모로 각각 0.25과 0.16이며 그 관계식은 각각 다음과 같다. (심발지진) (천발지진) 실체파규모의 경우 환산식은 진원깊이에 크게 영향을 받지 않는 것으로 나타났다. 환산식에 수반된 표준편차는 모멘트 규모로 0.28이며 그 관계식은 다음과 같다. 실체파와 표면파가 동시에 결정된 경우 새로운 규모 을 정의하여 별도의 환산식을 구했다. 천발지진만이 분석에 이용되었으며, 환산식에 수반된 표준편차는 모멘트 규모로 0.14이고 그 관계식은 다음과 같다. 이상의 분석결과는 한반도 및 인근 지역의 지진 크기를 하나의 지진규모, 즉 모멘트 규모로 통일하는데 이용될 수 있다.

• 지구물리
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• 제7권3호
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• pp.185-192
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• 2004

2001년 1월부터 2004년 2월까지 한반도 남부 지역에서 발생한 지진의 모멘트규모를 계산하여 기상청과 한국지질자원연구원의 지역규모와의 관계를 분석하였다 분석 결과 기상청의 지역규모는 한국지질자원연구원의 지역규모에 비해 모멘트규모와의 상관성이 낮은 것으로 나타났다 또한 발표된 지역규모와 계산된 모멘트규모의 회귀 분석을 통해 모멘트규모 환산식을 유도하였다 유도된 모멘트규모 환산식은 지진목록의 규모 단일화에 이용될 수 있고 규모가 단일화된 지진목록은 지진활동 특성 분석 지진재해도나 감쇄식 등에 필요한 인자로서 활용될 수 있다

• 한국전산구조공학회:학술대회논문집
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• 한국전산구조공학회 2001년도 가을 학술발표회 논문집
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• pp.417-424
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• 2001

It is very important to know the magnitude of the restraint moment which is appeared at the inner-support of the continuous PSC girder. The Age-adjusted Effective Modulus Method(AEMM) is used to get the magnitude of the restraint moment for the purpose of the time-dependent analysis of the concrete. The important factors for computing the restraint moment, the creep coefficient and the shrinkage strain are computed by comparing Korean specification with AC1209. The restrain moment is created by the individual continuity load. The main purpose of this paper is ensuring the safety of structure by acquiring the time-dependent stress acting on the concrete because the process of construction is getting difficult due to the advance of technology. The negative moment at the inner-support is decreased about 55% by introducing the process of making the continuous bridge relatively early.

• Structural Engineering and Mechanics
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• 제23권5호
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• pp.563-577
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• 2006

This study involves a series of experiments on the buckling strength of eccentrically compressed cold-formed stainless steel square hollow-section columns. The principal parameters in this study are slenderness ratios ($L_k/r$ = 30, 50, 70) and magnitude of eccentricity e (0, 25, 50, 75, 100 mm) on the symmetrical end-moment. The objectives of this paper are to obtain the buckling loads by conducting a series of experiments and to compare the behavior of the eccentrically compressed cold-formed stainless steel square hollow-section columns with the results of the analysis. The ultimate buckling strength of the square-section members were determined with the use of a numerical method in accordance with the bending moment-axial force (M-P) interaction curves. The behavior of each specimen was displayed in the form of a moment-radian (M-${\theta}$) relationship. The numerically obtained ultimate-buckling interaction curves of the beam columns coincided with the results of the experiments.

• 한국지진공학회:학술대회논문집
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• 한국지진공학회 2002년도 춘계 학술발표회 논문집
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• pp.3-11
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• 2002

Source parameters for forty nine recent earthquakes occurred in and around Korean Peninsula are determined and the relations among them are studied. The corner frequency and seismic moment are estimated from three different methods. The spectral fitting of the source displacement spectrum with the $\omega$-square source model of Brune(1970) and Snoke(1987)'s method are applied to all events and empirical Green's function method for two events are adopted. The source parameters determined in this study show different values depending on the adopted method and on the stations of which seismograms are recorded. It is interpreted that the disagreements principally originate from insufficient consideration of source radiation pattern and attenuation and amplification according to path direction. The corner frequencies and seismic moments are averaged to exclude the directional effects and other source parameters are estimated from the mean corner frequency and seismic moment. The static stress drops estimated in this study tend to be independent of seismic moment or magnitude for events above a certain size. For earthquakes with the size less than about 3.0$\times$10$^{21}$dyne-cm(nearly same as M$_{L}$=3.7), the stress drop tends to decrease with the decreasing moment. This fact suggests a breakdown of scaling law of source parameters below the threshold magnitude. The moment magnitudes calculated from source parameters appear to be slightly larger than the Richter's local magnitudes in the range above M$_{L}$=3.5.3.5.

• Geomechanics and Engineering
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• 제23권1호
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• pp.71-83
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• 2020

Cantilever sheet pile walls are subjected to surcharge loading located on the backfill soil and at different distances from the top of the wall. The response of cantilever sheet pile walls to surcharge loadings at varying distances under seismic conditions is scarce in literature. In the present study, the influence of uniform surcharge load on cantilever sheet pile wall at varying distances from the top of the wall under seismic conditions are analyzed using finite difference based computer program. The results of the numerical analysis are presented in non-dimensional form like variation of bending moment and horizontal earth pressure along the depth of the sheet pile walls. The numerical analysis has been conducted at different magnitudes of horizontal seismic acceleration coefficient and vertical seismic acceleration coefficients by varying the magnitude and position of uniform surcharge from the top of the wall for different embedded depths and types of soil. The parametric study is conducted with different embedded depth of sheet pile walls, magnitude of surcharge on the top of the wall and at a distance from the top of the wall for different angles of internal friction. It is observed that the maximum bending moment increases and more mobilization of earth pressure takes place with increase in horizontal seismic acceleration coefficients, magnitude of uniform surcharge, embedded depth and decrease in the distance of surcharge from the top of the wall in loose sand.

• 한국소음진동공학회논문집
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• 제18권1호
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• pp.35-46
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• 2008

Harmonic vibration characteristics for the general rotor model having a breathing crack are analyzed. Analyses are performed at the half critical speed ranges. The vibration characteristics are explained by using the additional slope and bending moment at the crack position and the influence coefficient showing the structural dynamic characteristics of the rotor. With the low crack depth the magnitude of the additional slope is kept constant even at the speed range at which the orbit magnitude is very sensitive to the rotational speed change. At this speed range the vibration is affected by the influence coefficient only. As the dynamic bending moment exceeds the static bending moment with the increase of crack depth. the additional slope affects the vibration amplitude of cracked rotor and the crack propagation rate increases.

• 한국안전학회지
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• 제8권4호
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• pp.21-26
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• 1993

This paper presents a method of stress analysis of golf club. We define the sweet spot of golf club by the magnitude of torsional moment. Transfer matrix method was used for optimal design on sweet spot of golf club.

• 한국운동역학회지
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• 제23권3호
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• pp.225-233
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• 2013

The purpose of this study was to estimate the potential injury via analyzing ground reaction force components that were resulted from a prolonged-run-induced fatigue. For the present study, passive and active components of the vertical ground reaction force were determined from time and frequency domain. Shear components of GRF also were calculated from time and frequency domain. Twenty subjects with rear foot contact aged 20 to 30, no experience in injuries of the extremities, were requested to run on the instrumented tread-mill for 160 minutes at their preference running speed. GRF signals for 10 strides were collected at 5, 35, 65, 95, 125, and 155 minute during running. In conclusions, there were no significant difference in the magnitude of passive force, impact load rate, frequency of the passive and active components in vertical GRF between running times except the magnitude of active force (p<.05). The magnitude of active force was significantly decreased after 125 minute run. The magnitude of maximum peak and maximum frequency of the mediolateral GRF at heel strike and toe-off have not been changed with increasing running time. The time up to the maximum peak of the anteroposterior at heel-strike moment tend to decrease (p<.05), but the maximum peak and frequency of that at heel and toe-off moment didn't depend significantly on running time.

• Journal of the Korean Data and Information Science Society
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• 제15권4호
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• pp.965-971
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• 2004

In this paper we consider several nonparametric estimators for the mean residual life by using the partial moment approximation under the proportional hazard model. Also we compare the magnitude of mean square error of the proposed nonparametric estimators for mean residual life under the proportional hazard model.