• 한국세라믹학회지
• /
• 제34권4호
• /
• pp.351-356
• /
• 1997

The origin of the variation of initial permeability in manganese-zinc ferrite polycrystals with a content of hematite was investigated. Initial permeability showed maximum with hematite content while there was no significant change in microstructure. Saturation magnetization increased with hematite content. So the variation of initial permeability was not explained on the basis of microstructural change or saturation magnetization. Temperature dependence of initial permeability revealed magnetocrystalline anisotropy was the origin of the variation of initial permeability. The change in magnetocrystalline anisotropy was ascribed to the variation in ferrous ion concentration. Therefore the variation of initial permeability in manganese-zinc ferrite polycrystals with a content of hematite was due to ferrous ion concentration via magnetocrystalline anisotropy.

• 한국정보통신설비학회:학술대회논문집
• /
• 한국정보통신설비학회 2006년도 하계학술대회
• /
• pp.235-240
• /
• 2006

In order to enhance receive sensitivity in noisy environment, the previous initial synchronization method of GPS receiver for reference stations adopts not only the coherent integration method but also the non-coherent integration method. However, the previous GPS initial synchronization method causes the non-coherent integration loss, which is a dominant factor among the signal acquisition losses in noisy environment. And the non-coherent integration loss increases with the strength of noise signal. In this pa-per, a GPS initial synchronization method is proposed to enhance receive sensitivity of GPS receiver for reference stations in noisy environment. This paper presents that the proposed GPS initial synchronization method suppresses the non-coherent integration loss. Furthermore, with regard to the mean acquisition time, it is shown that the number of the search cells of the proposed GPS initial synchronization method is much fewer than that of the previous GPS initial synchronization method.

• 한국농공학회논문집
• /
• 제46권2호
• /
• pp.67-75
• /
• 2004

This study aims to investigate the dynamic behaviour of a parabolic arch with initial deflection by using the elasto-plastic finite element model where the von-Mises yield criteria have been adopted. The initial deflection of arch was assumed by the high order polynomial of ${\omega}_i$ = ${\omega}_o$${(1-{(2x/L)}^m)}^n$) and the sinusoidal profile of ${\omega}_i$ = ${\omega}_o$$\sin$(n$\pi$x/L). Several numerical examples were tested considering symmetric initial deflection modes when the maximum initial deflection of an arch is fixed as L/500, L/1000, L/2000 or L/5000. The effects of polynomials order on the dynamic behavior of arch were not conspicuous. The most unfavorite dynamic response occurs when the maximum initial deflection varies from L/1000 to L/4000 if the initial deflection mode is represented by high order polynomials.

• Structural Engineering and Mechanics
• /
• 제6권2호
• /
• pp.173-183
• /
• 1998

In the shape design of flexible structures, it is useful to predict the initial shape from the desirable large deformed shapes under some loading conditions. In this paper, we present a numerical procedure of an initial shape determination problem for hyperelastic materials which enables us to calculate an initial shape corresponding to the prescribed deformed shape and boundary condition. The present procedure is based on an Arbitrary Lagrangian-Eulerian (ALE) finite element method for hyperelasticity, in which arbitrary change of shapes in both the initial and deformed states can be treated by considering the variation of geometric mappings in the equilibrium equation. Then the determination problem of the initial shape can be formulated as a nonlinear problem to solve the unknown initial shape for the specified deformed shape that satisfies the equilibrium equation. The present approach can be implemented easily to the finite element method by employing the isoparametric hypothesis. Some basic numerical results are also given to characterize the present procedure.

• 한국농공학회지
• /
• 제41권4호
• /
• pp.77-85
• /
• 1999

In this study, a computer program considering initial imperfection of axisymmetric reinforced concrete shell which plastic deformation by large external loading was developed . Initial imperfection of dome was assumed as 'dimple type' which can be expressed as Wi=(Wo/h)(1-x$^2$)$^3$. The developed model applied to the analysis of dynamic response of axisymmetric reinforced concrete shell when it has initial imperfection. The initial imperfection of 0.0, -5.0, and 5cm and steel and steel layer ratio 0,3, and 5% were tested for numerical examples . The results can be summarized as follows ; 1. Dynmaic response of vertical deflection at dome crown showed slow increased if it has not inital imperfection . But the response showed relatively high amplitude when initial imperfection was inner directed (opposite direction to loading). Similar trends also appeared for different steel layer ratios. 2. Dynamic responses of radial displacement at the junction of dome and wall showed the highest amplitude when initial imperfection was inward directed (opposite direction to loading). The lowest amplitude occurred when initial imperfection was outward directed (same direction to loading). Vibration period also delayed for inward directed initial imperfection . These trends were obvious as steel layer ratio increasing. 3. The effects of imperfection for the dynamic response of radial displacement a the center of wall scarely appeared. The effects of initial imperfection of dome on the dynmaic response of the wall can be neglected. 4. Effect of steel on the dynmic response of axisymmetric shell structure was great when initial imperfection did not exist. And the effect of direction of initial imperfection (inward or outward) did not show big difference.

• 대한기계학회논문집A
• /
• 제26권11호
• /
• pp.2415-2420
• /
• 2002

In the present study, a new anchor design was proposed to minimize the initial deflection of micro multi-layer cantilever beam with step-up structure, which is a key component of thin film micro-mirror array. It is important to minimize the initial deflection, caused by residual stress, because it reduces the performance of the actuation. Theoretical and experimental studies were conducted to examine the cause of the initial bending deflection. It was found that the bending deflection at the anchor of the cantilever beam was the primary source of initial deflection. Various anchor designs were proposed and the initial deflections for each design were calculated by finite element analysis. The analysis results were compared with experiments. To reduce the initial deflection a secondary support was added to the conventional structure. The optimal shapes were obtained by simulation and experiment. It was found from the analysis that the ratio or horizontal and vertical dimensions of secondary support was the governing factor, which affected the initial deflection.

• Asian Pacific Journal of Cancer Prevention
• /
• 제16권17호
• /
• pp.7871-7874
• /
• 2015

Background: There is no consensus regarding the selection of treatment options for hepatocellular carcinoma (HCC) after initial transarterial chemoembolization (TACE). This meta-analysis aimed to explore the survival benefit of hepatic resection after initial TACE for the treatment of HCC. Materials and Methods: We searched three major databases to identify all relevant papers comparing the outcomes of hepatic resection after initial TACE versus TACE alone for the treatment of HCC. Hazard ratios (HRs) with 95% confidence intervals (95%CIs) were calculated to evaluate the survival benefit of hepatic resection after initial TACE over TACE alone. Results: Three of 2037 initially identified papers were included. All of them were cohort studies from Asia. There was a significantly better overall survival (OS) in patients undergoing hepatic resection after initial TACE than in those undergoing TACE alone (HR=0.63, 95%CI=0.52-0.76, P<0.00001). The heterogeneity among studies was not statistically significant (P=0.96; I2=0%). Conclusions: Hepatic resection could improve the OS of HCC patients treated with initial TACE. Further randomized controlled trials should be necessary to identify the target population for the sequential use of hepatic resection after initial TACE and to compare the outcomes between patients undergoing hepatic resection after initial TACE session versus those undergoing TACE alone.

• Earthquakes and Structures
• /
• 제15권5호
• /
• pp.529-540
• /
• 2018

The influences of initial damage paths and aftershock (AS) spectral shape on the assessment of AS collapse fragility are investigated. To do this, a four-story ductile reinforced concrete (RC) frame structure is employed as the study case. The far-field earthquake records recommended by FEMA P695 are used as AS ground motions. The AS incremental dynamic analyses are performed for the damaged structure. To examine the effect of initial damage paths, a total of six kinds of initial damage paths are adopted to simulate different initial damage states of the structure by pushover analysis and dynamic analysis. For the pushover-based initial damage paths, the structure is "pushed" using either uniform or triangle lateral load pattern to a specified damage state quantified by the maximum inter-story drift ratio. Among the dynamic initial damage paths, one single mainshock ground motion or a suite of mainshock ground motions are used in the incremental dynamic analyses to generate a specified initial damage state to the structure. The results show that the structure collapse capacity is reduced as the increase of initial damage, and the initial damage paths show a significant effect on the calculated collapse capacities of the damaged structure (especially at severe damage states). To account for the effect of AS spectral shape, the AS collapse fragility can be adjusted at different target values of ${\varepsilon}$ by using the linear correlation model between the collapse capacity (in term of spectral intensity) and the AS ${\varepsilon}$ values, and coefficients of this linear model is found to be associated with the initial damage states.

• Journal of Welding and Joining
• /
• 제13권2호
• /
• pp.60-67
• /
• 1995

The factors affecting on the fatigue strength of spot_welded specimens have been studied. The influence of initial overloads on the fatigue life of spot_welded tensile_shear specimens is investigated by considering fatigue crack initiation and crack propagation. The change of strain range and the influence of initial overload are correlated on the basis ol strain results. The results of this study are as follows. l) The initial absolute strain range decreased with initial overloads increase, and absolute strain range decreased before transformation of waveform of strain, but increased after transformation of waveform of strain. 2) In case of subsequent point of inflection of offset strain, the increment of this strain decreased with initial overload increase. 3) As initial overloads increase, the deformation behavior of spot welded parts is restricted after overloading.

• 말소리와 음성과학
• /
• 제2권3호
• /
• pp.91-99
• /
• 2010

This paper reports on an identification test where KFL learners identified the Korean three-way laryngeal contrast in the phrase-initial position, when the phrase-initial tone was systematically manipulated. It turns out that heritage learners have some sensitivity to phrase-initial tone and show a plain-aspirated alternation in their identification according to the phrase-initial tone, as native speakers do, whereas non-heritage students do not show such tone sensitivity. However, after a weekly prosody training, second-year non-heritage students have shown a significant improvement in their performance. This paper clearly shows that the phrase-initial tone plays a critical role in distinguishing laryngeal features of Korean obstruents, and also suggests that prosody including the tone-segment correlation should be incorporated in the KFL curriculum.