• Journal of the Korean Mathematical Society
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• v.45 no.4
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• pp.1075-1087
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• 2008

We study a class of KMS-symmetric quantum Markovian semigroups on a quantum spin system ($\mathcal{A},{\tau},{\omega}$), where $\mathcal{A}$ is a quasi-local algebra, $\tau$ is a strongly continuous one parameter group of *-automorphisms of $\mathcal{A}$ and $\omega$ is a Gibbs state on $\mathcal{A}$. The semigroups can be considered as the extension of semi groups on the nontrivial abelian subalgebra. Let $\mathcal{H}$ be a Hilbert space corresponding to the GNS representation con structed from $\omega$. Using the general construction method of Dirichlet form developed in [8], we construct the symmetric Markovian semigroup $\{T_t\}{_t_\geq_0}$ on $\mathcal{H}$. The semigroup $\{T_t\}{_t_\geq_0}$ acts separately on two subspaces $\mathcal{H}_d$ and $\mathcal{H}_{od}$ of $\mathcal{H}$, where $\mathcal{H}_d$ is the diagonal subspace and $\mathcal{H}_{od}$ is the off-diagonal subspace, $\mathcal{H}=\mathcal{H}_d\;{\bigoplus}\;\mathcal{H}_{od}$. The restriction of the semigroup $\{T_t\}{_t_\geq_0}$ on $\mathcal{H}_d$ is Glauber dynamics, and for any ${\eta}{\in}\mathcal{H}_{od}$, $T_t{\eta}$, decays to zero exponentially fast as t approaches to the infinity.

• Journal of Animal Science and Technology
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• v.57 no.11
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• pp.39.1-39.5
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• 2015

The effects of castration time on growth and carcass traits of elk bulls were investigated. Twelve bulls at 5 years old were raised and fed on concentrate with ad libitum hay. All animals were allocated randomly to each of four treatment groups (3 heads/group). Groups of each treatment were castrated surgically in March, April or June and managed together with non-castration (entire) treatment. All elk bulls in the trial were slaughtered at same time. Growth parameters, carcass yield and composition were recorded. The total gain and average daily gain was higher when castrated in April (p < 0.05). The entire elk produced heaviest and highest in saddle and brisket portions (p < 0.05). It is apparent that the castrate animals carried more total fat weight and percentages than the entire males (p < 0.05). It was found that loin muscles from non-castrated elk, in comparison with those from castrated one, had higher content of moisture and lower content of fat (p < 0.05). In this study, growth parameters, carcass yields and chemical composition were greatly affected by castration time.

• Geomechanics and Engineering
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• v.15 no.1
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• pp.645-657
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• 2018

The paper aims to analyze the behaviour of torsional type surface waves propagating through fluid saturated inhomogeneous porous media clamped between two inhomogeneous anisotropic media. We considered three types of inhomogeneities in upper anisotropic layer which varies exponentially, quadratically and hyperbolically with depth. The anisotropic half space inhomogeneity varies linearly with depth and intermediate layer is taken as inhomogeneous fluid saturated porous media with sinusoidal variation. Following Biot, the dispersion equation has been derived in a closed form which contains Whittaker's function and its derivative, for approximate result that have been expanded asymptotically up to second term. Possible particular cases have been established which are in perfect agreement with standard results and observe that when one of the upper layer vanishes and other layer is homogeneous isotropic over a homogeneous half space, the velocity of torsional type surface waves coincides with that of classical Love type wave. Comparative study has been made to identify the effects of various dimensionless parameters viz. inhomogeneity parameters, anisotropy parameters, porosity parameter, and initial stress parameters on the torsional wave propagation by means of graphs using MATLAB. The study has its own relevance in connection with the propagation of seismic waves in the earth where fluid saturated poroelastic layer is present.

• Smart Structures and Systems
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• v.21 no.5
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• pp.669-675
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• 2018

Under braking forces of a freight train, there are great longitudinal structural responses of a large freight railway cable-stayed bridge. To alleviate such adverse reactions, viscous dampers are required, whose parametric selection is one of important and arduous researches. Based on the longitudinal dynamics vehicle model, responses of a cable-stayed bridge are investigated under various cases. It shows that there is a notable effect of initial braking speeds and locations of a freight train on the structural responses. Under the most unfavorable braking condition, the parameter sensitivity analyses of viscous dampers are systematically performed. Meanwhile, a mixing method called BPNN-NSGA-II, combining the Back Propagation neural network (BPNN) and Non-Dominated Sorting Genetic Algorithm With Elitist Strategy (NSGA-II), is employed to optimize parameters of viscous dampers. The result shows that: 1. the relationships between the parameters of viscous dampers and the key longitudinal responses of the bridge are high nonlinear, which are completely different from each other; 2. the longitudinal displacement of the bridge main girder significantly decreases by the optimized viscous dampers.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.17 no.4
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• pp.377-385
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• 2005

An analytical model was developed using the lumped mass parameter method to estimate temperature distribution of metal parts and refrigerant of the hermetic reciprocating compressor, All of the lumped mass has been equated with the first law of thermodynamics. In the delivered equation, correlations of heat transfer coefficient in the heat transfer equation were taken from open literature. The equations are solved by Gauss-Jordan method simultaneously. To verify the developed numerical program, an experiment was conducted with a domestic refrigerator. The compressor which had been installed at the bottom of the experimental refrigerator was modified to measure internal temperature. Model verification test was conducted at $30^{\circ}C$ outdoor temperature with variation of compressor cooling conditions. As a result, there is a good consistency between calculated temperature and measured one.

• Geomechanics and Engineering
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• v.11 no.6
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• pp.771-785
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• 2016

The thermal conductivity of soils is an important property in energy-related geotechnical structures, such as underground heat pumps and underground electric power cable tunnels. This study explores the effects of geotechnical engineering properties on the thermal conductivity of soils. The thermal conductivities of quartz sands and Korean weathered silty sands were documented via a series of laboratory experiments, and its variations with effective stress, porosity, and water saturation were examined. While thermal conductivity was found to increase with an increase in the effective stress and water saturation and with a decrease in porosity, replacing air by water in pores the most predominantly enhanced the thermal conductivity by almost one order of magnitude. In addition, we have suggested an improved model for thermal conductivity prediction, based on water saturation, dry thermal conductivity, saturated thermal conductivity, and a fitting parameter that represents the curvature of the thermal conductivity-water saturation relation.

• Geomechanics and Engineering
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• v.36 no.3
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• pp.247-258
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• 2024

Tailings are waste materials of mining operations, consisting of a mixture of clay, silt, sand with a high content of unrecoverable metals, process water, and chemical reagents. They are usually discharged as slurry into the storage area retained by dams or earth embankments. Poor knowledge of the hydro-mechanical behaviour of tailings has often resulted in a high rate of failures in which static liquefaction has been widely recognized as one of the major causes of dam collapse. Many studies have dealt with the static liquefaction of coarse soils in saturated conditions. This research provides an extension to the case of silty tailings in unsaturated conditions. The static liquefaction resistance was evaluated in terms of stress-strain behavior by means of monotonic triaxial tests. Its dependency on the preparation method, the volumetric water content, the void ratio, and the degree of saturation was studied and compared with literature data. The static liquefaction response was proved to be dependent mainly on the preparation technique and degree of saturation that, in turn, controls the excess of pore pressure whose leading role is investigated by means of the relationship between the -B Skempton parameter and the degree of saturation. A preliminary interpretation of the static liquefaction response of Stava tailings is also provided within the Critical State framework.

• Journal of KIISE:Computer Systems and Theory
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• v.34 no.11
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• pp.589-598
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• 2007

In the group communication which has multiple data streams and various access privileges, it is necessary to provide group access control. The group members having the same access privilege are classified into one class, and the classes form a hierarchy based on the access relations. Then each class is assigned to a secret key. In the previous schemes, a single logical key graph is constructed from the hierarchy and each member always holds all secret keys of the classes he can access in the proactive manner. Thus, higher-privileged members hold more keys then lower-privileged members. However, if the hierarchy is large, each member manages too many keys and the size of multicast message in rekeying increases in proportion to the size of the hierarchy. Moreover, most of the members access a small portion of multiple data streams simultaneously. Therefore, it is redundant to receive rekeying message and update the keys in which he is not currently interested. In this paper, we present a new key management scheme that takes a reactive approach in which each member obtains the key of a data stream only when he wants to access the stream. Each member holds and updates only the key of the class he belongs. If he wants to get the key of other class, he derives it from his key and the public parameter. Proposed scheme considerable reduces the costs for rekeying, especially in the group where access relations are very complex and the hierarchy is large. Moreover, the scheme has another advantage that it easily reflects the change of access relations.

• Korean Journal of Poultry Science
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• v.37 no.3
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• pp.207-213
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• 2010

The current study was conducted to estimate the effect of dietary pyroligneous acid (PA) on performance, noxious gas emission in excreta, blood parameter and fatty acid composition of breast meat in Korean native chicken. A total of 240 one-day-old chicks were allocated to three treatments (PA; 0, 0.1, 0.2%) with five replicate of 16 each per treatment for 10 weeks. Although there was no effect on the performance, ammonia gas concentration was significantly decreased in the PA treatments compared to the control (p<0.05). Birds fed PA had higher serum total protein and high density lipoprotein-cholesterol (HDL-cholesterol) concentration but lower triglyceride content in the PA 0.2% treatment than control (p<0.05). In fatty acids composition of breast meat, myristic and stearic acid were significantly decreased, whereas oleic and linolenic acid were significantly increased in the group fed PA compared to those of the control group (p<0.05). The result of the current study indicates that dietary PA may reduce the noxious gas emission and improve lipid levels as well as increase of monounsaturated fatty acids composition of breast meat in Korean native chickens.

• Physical Therapy Korea
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• v.17 no.3
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• pp.77-86
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• 2010

The purpose of this study was to investigate the variations in gait parameters in terms of the type of arm sling used in hemiplegic patients. Ten patients with hemiplegia and ten healthy adults participated in this study and walked at self-selected speeds on a GAITRite-instrumented carpet. The activities of the opposite shoulder girdle muscle including the latissimus dorsi, anterior deltoid, and posterior deltoid were simultaneously recorded using surface EMG during gait. They were randomly assigned a condition: without an arm sling, a single strap arm sling, a Harris hemi arm sling, a Rolyan humeral cuff arm sling, and a Bobath roll arm sling. The following gait variables were analyzed: the temporo-spatial parameters of velocity, step length, stride length, swing phase, stance phase, single support, step time and toe in/toe out. The statistical analysis was one-way ANOVA with repeated measures to compare the variation of each variable. In comparison of parameters in each trial in the hemiplegia group, the non-affected side stride length, single support, and toe in/toe out resulted in statistically significantly changes (p<.05). But without an arm sling group did not show any gait parameter differences with arm slings. This study found that several arm slings varied gait patterns in patients with hemiplegia and in healthy adults. In the EMG analysis, the Rolyan humeral cuff arm sling and the Bobath roll arm sling were higher muscle activity for the latissimus dorsi muscle than did the single strap ann sling. Further study should examine the problems that appeared in patients who worn arm slings by focusing on a larger number of subjects and by studying the variety of responses in more detail using an assessment tool that measures variation.