• KSCE Journal of Civil and Environmental Engineering Research
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• v.13 no.1
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• pp.161-171
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• 1993

The aim of this study is to provide the stress-strain behavior of hardening geological materials such as rock or concrete on three dimensional spaces by using Desai model based on plastic theory. To validate proposed model, truly triaxial tests with high pressure under variety of stress paths in which three principal stresses were controlled independently using concrete materials were performed. The main results are summerized as follows: 1. Various stress paths for hardening materials used are satisfactorily explained by performing the truly triaxial test with high pressure. This is very important to investigate constitutive equations for materials like rock or concrete. 2. Since the proposed yield function is continuous, it avoids the singularity point at the intersection of two function in the previous models, thus, reducing the difficulties for computer implementation. 3. Analytic predictions for yielding behavior on $J_1-{\sqrt{J_{2D}}}$ octahedral and triaxial plane, as well as volumetric strain and stress-strain behavior agree well with experimental results.

• Journal of the Earthquake Engineering Society of Korea
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• v.3 no.1
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• pp.67-74
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• 1999

In this study, coda Q has been determined by the single scattering model in the Kyeongsang Basin region using the decay of the amplitudes of coda waves on bandpass-filtered seismograms of local microearthquakes in the frequency range 1.5~18 Hz. Reported frequency dependence of Q is of the form $Q_C=Q_O^n$$(83.9{ll}Q_0{ll}155.9,;0.76{ll}n{ll}1.05$. Considering a model incorporating both scattering and intrinsic attenuation, and assuming that the attenuation is entirely due to the scattering loss, the minimum mean free paths are about 51~56 km and the coefficients of inelastic attenuation(${\gamma}$) are between 0.0093 and 0.0098 were found. Earthquake-station paths pass through the fault zone show high attenuation and strong frequency dependency compared to other ones.

• Journal of Communications and Networks
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• v.16 no.5
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• pp.548-558
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• 2014

Load distribution is vital to the performance of multipath transport. The task becomes more challenging in real-time multimedia applications (RTMA), which impose stringent delay requirements. Two key issues to be addressed are: 1) How to minimize end-to-end delay and 2) how to alleviate packet reordering that incurs additional recovery time at the receiver. In this paper, we propose sub-packet based multipath load distribution (SPMLD), a new model that splits traffic at the granularity of sub-packet. Our SPMLD model aims to minimize total packet delay by effectively aggregating multiple parallel paths as a single virtual path. First, we formulate the packet splitting over multiple paths as a constrained optimization problem and derive its solution based on progressive approximation method. Second, in the solution, we analyze queuing delay by introducing D/M/1 model and obtain the expression of dynamic packet splitting ratio for each path. Third, in order to describe SPMLD's scheduling policy, we propose two distributed algorithms respectively implemented in the source and destination nodes. We evaluate the performance of SPMLD through extensive simulations in QualNet using real-time H.264 video streaming. Experimental results demonstrate that: SPMLD outperforms previous flow and packet based load distribution models in terms of video peak signal-to-noise ratio, total packet delay, end-to-end delay, and risk of packet reordering. Besides, SPMLD's extra overhead is tiny compared to the input video streaming.

• Korean Journal of Occupational Health Nursing
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• v.10 no.1
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• pp.93-109
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• 2001

The purposes of this study are to identify stress and coping strategies of married working women. Data were collected from 185 married working women, living in the metropolitan area. The results were as follows: 1. Low family function and high occupational stress affected stress symptoms of married working women significantly, but type A personality was not related to the stress symptoms. 2. The more the married working women perceived stress symptoms, the more they utilized organizational coping strategies. 3. The women who used personal coping strategies effectively also used more effective organizational coping strategies. 4. Two paths were statistically significant : family function$\rightarrow$stress symptoms, occupational stress$\rightarrow$stress symptoms. But the others were not. Based on those results, the model was modified by adding four paths : A type personality$\rightarrow$personal coping strategies, occupational stress$\rightarrow$organizational coping strategies, personal coping strategies$\rightarrow$organizational coping strategies, organizational coping strategies$\rightarrow$stress symptoms. 5. The modified model produced a better fit than hypothetical model(GFI=0.9985, ACFI=0.9893, NFI=0.9920, NNFI=1.1330, RMSR=0.0030, PNFI=0.1984). In conclusion, the stress management for married working women needs to focus on both organizational coping strategies and personal coping strategies.

• Journal of KIISE:Software and Applications
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• v.30 no.1_2
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• pp.140-152
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• 2003

An XML document has a structure which may be irregular. It is difficult for end-users to comprehend the irregular document structure exactly. For these XML documents, an end-user has a difficulty in using structured query. Therefore, an end-user formulates no structured query or a query which has a little structure information. In this context, we propose new retrieval models which use the structured information for ranking and compensate the difference between user query structure and document structure. To ease with querying, we assume the independence among querying paths which represent structural constraints. Since this assumption makes degradation of the expression power of a query language, we also propose a model which overcome this problem. As there had been no test collections for XML documents, we made a small test collection from TIPSTER of the RTEC and experimented on this collection without a structured query, From this experiment, we showed that our models improve average precision about 67% over conventional Vector-Space model.

• Journal of the Korean Geotechnical Society
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• v.21 no.8
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• pp.85-93
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• 2005

Earth pressures acting on unmovable rigid walls vary according to loading-unloading conditions due to compaction experienced by backfill soil. Appropriate coefficients of earth pressure at rest with considering this influence need to be determined to estimate earth pressures more reasonably.0 this study, a single cycle hysteretic model simulating soil's loading-unloading-reloading behavior under $K_o-condition$ was reproduced by conducting a series of $K_o-triaxial$ test for compacted residual soils. Based on the results, coefficients of earth pressure at rest at each stage of stress paths such as, virgin loading, unloading and reloading were determined. Also, applicabilities of empirical equations to the estimation of the coefficients were evaluated by comparing the experimental results with those estimated by the equations. As a result, it was concluded that the empirical equations could be applied reasonably to the estimation of the coefficients for compacted residual soils in cases where some amount of error might be acceptable for the reloading stage of the hysteretic model.

• Journal of Korea Society of Industrial Information Systems
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• v.28 no.2
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• pp.31-45
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• 2023

This study deals with exploring qualitative steps and paths that appear as YouTube users' usage time increases quantitatively. For the study, I applied theories from psychology and neuroscience, subdivided the interval between the personalization algorithm of the recommendation system, and active use and analyzed the relationship between variables in this process. According to the theory behavioral model theory (FBM), variable reward, and dopamine addiction were applied. Personalization algorithms easy clicks as triggers according to associated content presentation functions in behavioral model theory (FBM). Variable rewards increase motivational effectiveness with unpredictability of the content you search, and dopamine nation is summarized as stimulating the dopaminergic nerve to continuously and actively consume content. This study is expected to make an academic and practical contribution in that it divides the purpose of use of content in the personalization algorithm and active use section into four stages from a psychological perspective: first use, reuse, continuous use, and active use, and analyzes the path.

• Management Science and Financial Engineering
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• v.4 no.2
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• pp.1-13
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• 1998

The Shortest Path Problem in Time-dependent Networks, where the travel time of each link depends on the time interval, is not realistic since the model and its solution violate the Non-passing Property (NPP:often referred to as FIFO) of real phenomena. Furthermore, solving the problem needs much more computational and memory complexity than the general shortest path problem. A new model for Time-dependent Networks where the flow speeds of each link depend on time interval, is suggested. The model is more realistic since its solution maintains the NPP. Solving the problem needs just a little more computational complexity, and the same memory complexity, as the general shortest path problem. A solution algorithm modified from Dijkstra's label setting algorithm is presented. We extend this model to the problem of Minimum Expected Time Path in Time-dependent Stochastic Networks where flow speeds of each link change statistically on each time interval. A solution method using the Kth-shortest Path algorithm is presented.

• Journal of the Korean Society of Clothing and Textiles
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• v.22 no.4
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• pp.452-459
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• 1998

The purpose of this study was to discover a conceptual framework and evaluation process of apparel quality by means-end chain theory. The theoretical study was conducted to find out a conceptual framework and build a hypothetical evaluation process model of apparel quality. Apparel quality was perceived associative network called a means-end chain and was evaluated in several stages. A conceptual framework of apparel quality evaluation was organized into hierarchical relationships among four different dimensions: physical attribute, physical function, instrumental performance, and expressive performance. The means-end structure linked tangible physical attributes and function to more abstract instrumental and expressive performance. A hypothetical evaluation process model linked dimensions of apparel quality to the selected means-end relationship. Different consumers had different means-end chains for the same apparel. Therefore different subjects are likely to have different evaluation paths. From this study we can suggest an evaluation process model of apparel quality.

• Proceedings of the Korea Concrete Institute Conference
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• 1993.04a
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• pp.65-72
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• 1993

Steel fiber reinforced concrete(SFRC) which is made by short, randomly distributed steel fibers in concrete is superior in its tensile mechanical properties to plain concrete in enhancement of tensile strength and tensile ductility. These improvements are attributed to crack arresting mechanism and formation of longer crack paths due to fibers , which as a consequence lead to increase in energy absorption capacity of SFRC. In the post-peak region under tensile stresses, major macrocrack forms at critical section. The opening of this macrocrack is mainly resisted by both of the fiber pull-out bridging the cracked surfaces and the resistance by matrix softening. In this study, micromechaincal approach has been made in order to simulate tensile behavior of SFRC and based on which the theoretical model is presented. This model reflects the features of both the composite material concept and the spacing concept in predicting tensile strength of SFRC. The model also takes into account for the effects of matrix tensile softening and fiber bridging by pull-out on the resistance for the post-peak behavior of SFRC. It has been shown that the developed model satisfactory predicts the experimental results.