• Nuclear Engineering and Technology
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• 제49권6호
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• pp.1135-1142
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• 2017

The applicability of the algebraic collapsing acceleration (ACA) technique to the method of characteristics (MOC) in cases with scattering anisotropy and/or linear sources was investigated. Previously, the ACA was proven successful in cases with isotropic scattering and uniform (step) sources. A presentation is first made of the MOC implementation, available in the DRAGON5 code. Two categories of schemes are available for integrating the propagation equations: (1) the first category is based on exact integration and leads to the classical step characteristics (SC) and linear discontinuous characteristics (LDC) schemes and (2) the second category leads to diamond differencing schemes of various orders in space. The acceleration of these MOC schemes using a combination of the generalized minimal residual [GMRES(m)] method preconditioned with the ACA technique was focused on. Numerical results are provided for a two-dimensional (2D) eight-symmetry pressurized water reactor (PWR) assembly mockup in the context of the DRAGON5 code.

• 한국기계가공학회지
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• 제12권5호
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• pp.157-162
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• 2013

To analyze the dynamic acceleration characteristics, it is necessary to identify the acceleration model using some methods that can represent the dynamic properties well. In this sense, fractal methods were used for the verification of characteristics of an acceleration signal. To estimate and analyze the geometry of acceleration signal, a fractal interpolation and its analysis was introduced in this paper. The chaotic nature of acceleration signal was considered in fractal modeling. In this study the fractal signal modeling has brought a focus within the scope of the fractal interpolation and fractal dimension. And a new idea of fractal dimension has been introduced and discussed considering the damping ratio and amplitude for its dynamic properties of the signal. The fractal dimension of acceleration with respect to the scaling factor using fixed data points of 1000 points was calculated and discussed. The acceleration behaviors of this results show some different characteristics. And this fractal analysis can be applied to other signal analysis of several machining such as pendulum type grinding and milling which has many dynamic properties in the signal.

• 산업경영시스템학회지
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• 제22권52호
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• pp.43-52
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• 1999

In this study, the vibration damping characteristics of the powered hand tools transmitted in hand-arm system were examined and compared. The types of powered tools for the experiment are general typed drill, impact drill, grinder, and wire brush. To analyze the characteristics of vibration damping, the magnitude of acceleration of vibration on X, Y, and Z direction at tool, hand, wrist, and the joint between forearm and upper arm were measured respectively. The results indicated that impact drill generated the highest value of acceleration of vibration among the four types of tools used in the experiments. The highest value of the amount of acceleration of vibration was found in the direction of Y. And the amount of acceleration of vibration was significantly affected by the type of tool, type of work, and pushing forces. As become the more distant from the tool, the smaller the amount of acceleration of vibration. Also, the bigger the pushing force at the tool, the higher the acceleration of vibration.

• Structural Engineering and Mechanics
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• 제90권6호
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• pp.591-600
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• 2024

This study investigated the acceleration response and shape change characteristics of a gravity quay wall according to the magnitude of the applied acceleration. The quay wall was defined as a port facility damaged by the Kobe earthquake. Four experimental scenarios were established based on the inclination condition grades, considered to be a significant defect factor in the quay wall. Then, the shaking table test was conducted using scaled-down quay wall models constructed per each scenario. The ground acceleration was gradually increased from the peak ground acceleration (PGA) of 0.1 g to 0.7 g. After each ground acceleration test, acceleration installed on the wall and backfill ground and inclination on the top of the wall were measured to assess the amplification of peak response acceleration and maximum response amplitude and the change in the inclination of the quay wall. This study also analyzed the separation of the quay wall from the backfill and the crack pattern of the backfill ground according to PGA values and inclination condition grades. The result of this study shows that response acceleration could provide a reasonable prediction for the changes in the inclination of the quay wall and the crack generation and propagation on the backfill from a current inclination condition grade.

• 천문학회보
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• 제40권1호
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• pp.63.3-64
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• 2015

In our previous work (Kim et al., 2015), we suggested a new classification scheme, which categorizes the SPEs into four groups based on association with flare or CME inferred from onset timings as well as proton acceleration patterns using multienergy observations. In this study, we have tried to find whether there are any typical characteristics of associated events and acceleration sites in each group using 42 SPEs from 1997 to 2012. We find: (i) if the proton acceleration starts from a lower energy, a SPE has a higher chance to be a strong event (>5000pfu) even if the associated flare and CME are not so strong. The only difference between the SPEs associated with flare and CME is the location of the acceleration site. For the former, the sites are very low (~1Rs) and close to the western limb, while the latter has a relatively higher and wider acceleration sites. (ii) When the proton acceleration starts from the higher energy, a SPE tends to be a relatively weak event (<1000pfu), in spite of its associated CME is relatively stronger than previous group. (iii) The SPEs categorized by the simultaneous proton acceleration in whole energy range within 10 minutes, tend to show the weakest proton flux in spite of strong related eruptions. Their acceleration heights are very close to the locations of type II radio bursts. Based on those results, we suggest that the different characteristics of the four groups are mainly due to the different mechanisms governing the acceleration pattern and interval, and different condition such as the acceleration location.

• 한국수자원학회:학술대회논문집
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• 한국수자원학회 2008년도 학술발표회 논문집
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• pp.1111-1115
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• 2008

The relative magnitudes of the individual terms of the momentum equation are analyzed and compared by the analytical methods in open channel flow. The temporal variations of each term(local acceleration term, convective acceleration term, pressure force term, gravity force term, and friction force term) are analyzed for the influence factors to runoff expressed by the parameters of the momentum equation, stream slopes and roughness coefficients. The magnitudes of each term vary with the channel characteristics, especially when the roughness coefficients are dominant or for the mild stream slopes the pressure term can not be negligible. As a result of the characteristics of momentum equation in open channel flow, the acceleration terms are very small compared with the other terms. The magnitudes of local acceleration and convective acceleration offsets each other. The peak time of each term except the gravity term coincides with inflection point of the hydrograph rising limb each other.

• Earthquakes and Structures
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• 제3권5호
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• pp.629-647
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• 2012

Multiple acceleration sequences of earthquake ground motions have been observed in many regions of the world. Such ground motions can cause large damage to the structures due to accumulation of inelastic deformation from the repeated sequences. The dynamic analysis of inelastic structures under repeated acceleration sequences generated from simulated and recorded accelerograms without sequences has been recently studied. However, the characteristics of recorded earthquake ground motions of multiple sequences have not been studied yet. This paper investigates the gross characteristics of earthquake records of multiple sequences from an engineering perspective. The definition of the effective number of acceleration sequences of the ground shaking is introduced. The implication of the acceleration sequences on the structural response and damage of inelastic structures is also studied. A set of sixty accelerograms is used to demonstrate the general properties of repeated acceleration sequences and to investigate the associated structural inelastic response.

• International Journal of Automotive Technology
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• 제5권4호
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• pp.311-319
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• 2004

There are many methods to test engine emissions depending on the regulations used such as FTP-75(CYS-75) mode, 10-15 mode and ECE-15 mode. Most of these modes consist of transient conditions such as cranking, rapid acceleration or deceleration modes. In this experimental research, the transient characteristics including cranking and accelerating mode in SI engines were studied to compare pure gasoline with methanol-reformulated fuels for performance and exhaust emissions. The results show that methanol-reformulated fuels have a better emissions reduction rate than that of pure gasoline especially for HC, CO and NOx emissions during cranking mode. The acceleration performances conform to the results of the distillation curve and the CO concentration for RM50 varies slightly in acceleration mode.

• 대한전기학회논문지:전기물성ㆍ응용부문C
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• 제48권5호
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• pp.354-360
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• 1999

PCN-PZT piezoelectric acceleration sensors of annular shear mode voltage type were fabricated and their characteristics have been investigated. Field tests are also carried out. To avoid noise problems from the environmental conditions, acceleration sensors employed solid state micro-electronics for pre-amplifier. The calibration procedures based on the principle of the comparison method were adopted for investigating the characteristics of fabricated acceleration sensors. The voltage sensitivity and resonant frequency of fabricated acceleration sensors were 83mv/g, 23kHz, respectively. The lower and upper frequency limit were 4Hz and 9kHz, respectively. The variation of the voltage sensitivity showed 10% at $-406{\circ}C\; and\; 9%\; at\; 121^{\circ}C$ compared to that of reference temperature at $40^{\circ}C$.

• 대한인간공학회지
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• 제19권2호
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• pp.75-86
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• 2000

In this study, the characteristics of transmitted vibration on HAS(hand-arm system) were identified to evaluate physical load due to the work surface orientation, tool weight and push force during powered drilling tasks. The characteristics of transmitted vibration on work surface orientation showed that the acceleration of transmitted vibration on horizontal work surface was higher than that on the vertical work surface. Regarding the characteristics of transmitted vibration on tool weight, the vibration acceleration level becomes lower as the tool weight becomes heavier. The amount of transmitted vibration on hand-arm system was decreased down to the tool weight of 2.4kg. However, as the tool weight becomes heavier than 2.8kg, the amount of transmitted vibration was increased and had peak value at 3.2kg of tool weight. Regarding the characteristics of transmitted vibration on push force, the vibration acceleration level goes higher, as the push force becomes larger. The characteristics of transmitted vibration on the axis of vibration showed that the direction of $Z_h$ had the highest acceleration compared to the direction of $X_h$, and $Y_h$. The direction of $X_h$, $Y_h$ and $Z_h$ had the highest acceleration of transmitted vibration on the hand, wrist and elbow, respectively. The results of this study showed that the condition which affect the lowest physical load to the subject on the powered drilling task would be working with the 2.4kg of tool weight on the vertical work surface.