• Journal of the Korean Wood Science and Technology
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• v.20 no.2
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• pp.61-72
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• 1992

This study was carried out to investigate the fracture behavior and the fracture criterion of yellow lauan(Shorea spp.), when has used for furniture and wood structures, and to offer a reliability for wood structure and basic data for wood fracture criterion in experiments which are fracture tested under mode I, mode II and mixed mode loading condition. The results were summarized as follows; 1. Fractures in specimens which have inclined grain in yellow lauan procedeed from crack tip in the radial direction along the grain. 2. In yellow lauan, $K_{IC}RL$ was 42.1kg/$cm^{3/2}$ and $K_{IIC}RL$ was 15.8kg/$cm^{3/2}$. 3. The fracture criteria of lauan were; ($K_I/K_{IC}$)+($K_{II}/K_{IIC}$)=1 in RL system with inclined grain at $45^{\circ}$, ($K_I/K_{IC}$)+$(K_{II}/K_{IIC})^2$=1 with inclined grain at $15^{\circ}$ and $(K_I/K_{IC})^2$+$(K_{II}/K_{IIC})^2$=1 with inclined grain at $30^{\circ}$, $60^{\circ}$, $75^{\circ}$ and $90^{\circ}$, respectively. 4. The fracture criterion of wood could vary with the species, and the load applying condition. In order to measure the fracture criterion strictly, along with standardization of specimen geometry a large amount of experimental data is needed. 5. $K_{IC}$(critical stress intensity factor) can be predicted by grain angle. As the grain inclined angle increased, $K_{IC}$ and $K_{IIC}$ are increased.

• Journal of the Korean Geotechnical Society
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• v.30 no.3
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• pp.73-85
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• 2014

The strength parameters used in rock mass design are mainly estimated by equations using Hoek-Brown failure criterion because the tests to obtain the values are limited and expensive. To estimate the strength parameters, the Hoek-Brown failure criterion should be transformed to the Mohr-Coulomb failure criterion. But the processes are more or less cumbersome due to the several stages including the computation and the analyzing steps. In this study, several rock states of various conditions were modeled and then the strength parameters were estimated using the Hoek-Brown failure criterion. Thereafter by analyzing the results, some charts and equations estimating the strength parameters through only one step or easily in the field using the values of RMC, the uniaxial compressive strength and the rock constant ($m_i$), were suggested. And then the suggested method was compared and discussed with the existing method.

• Geomechanics and Engineering
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• v.37 no.1
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• pp.9-19
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• 2024

This study presents an energy analysis for large-strain cavity expansion problem based on the general strength criterion and energy theory. This study focuses on the energy dissipation problem during the cavity expansion process, dividing the soil mass around the cavity into an elastic region and a plastic region. Assuming compliance with the small deformation theory in the elastic region and the large deformation theory in the plastic region, combined with the general strength criterion of soil mass and energy theory, the energy dissipation solution for cavity expansion problem is derived. Firstly, from an energy perspective, the process of cavity expansion in soil mass is described as an energy conversion process. The energy dissipation mechanism is introduced into the traditional analysis of cavity expansion, and a general analytical solution for cavity expansion related to energy is derived. Subsequently, based on this general analytical solution of cavity expansion, the influence of different strength criterion, large-strain, expansion radius, cavity shape and characteristics of soil mass on the stress distribution, displacement field and energy evolution around the cavity is studied. Finally, the effectiveness and reliability of theoretical solution is verified by comparing the results of typical pressure-expansion curves with existing literature algorithms. The results indicate that different strength criterion have a relatively small impact on the displacement and strain field around the cavity, but a significant impact on the stress distribution and energy evolution around the cavity.

• Tunnel and Underground Space
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• v.24 no.5
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• pp.366-372
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• 2014

The generalized Hoek-Brown (H-B) function provides a unique failure condition for a jointed rock mass, in which the strength parameters of rock mass are deduced from the intact values by use of the GSI value. Since it is actually the only failure criterion which accounts for the rock mass conditions in a systematic manner, the generalized H-B criterion finds many applications to the various rock engineering projects. Its nonlinear character, however, limits more active usage of this criterion. Accordingly, many attempts have been made to understand the generalized H-B condition in the framework of the M-C function. This study presents the closed-form expression relating the tangential cohesion to the tangential friction angle, which is derived by the non-dimensional stress transformation of the generalized H-B criterion. By use of the derived equation, it is investigated how the relationship between the tangential cohesion and friction angle of the generalized H-B criterion varies with the quality of rock masses. When only the variation of GSI value is considered, it is found that the tangential friction angle decreases with the increase of GSI, while the tangential cohesion increases with GSI value.

• Journal of Veterinary Clinics
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• v.23 no.4
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• pp.416-420
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• 2006

Compare to testing sera individually, pooled-serum testing has considered as a cost-effective method, particularly on a large population-based seroprevalence studies. This study was to determine the relationship between individual sera and pooled sera titers for detection of avian infectious bronchitis virus (IBV) and to evaluate suitability of pooled sera by comparing prevalences estimated from both samples. A total of 5,000 individual samples were collected from 500 flocks in Chungcheong, Gyunsgi, and Kangwon provinces between January 2005 and February 2006. Ten samples were randomly selected from each flock. Five-hundred pooled sera were prepared by mixing equal amount of each 10 individual serum from the original samples. IBV antibody titers were measured by hemagglutination inhibition (HI) test. The least squares regression analysis was performed to construct equation between pooled and mean individual titers. To determine whether the flock is infected 4 arbitrary criteria were used: detection of at least 1 chicken with HI titer ${\ge}$ 9 (criterion 1), detection of at least 2 samples with HI titer ${\ge}$9 (criterion 2), detection of at least 1 sample with HI titer ${\ge}$ 10 (criterion 3), and filially detection of at least 1 sample with HI titer ${\ge}$ 11 (criterion 4). The receiver operating characteristic (ROC) curve was used to examine the cut-off points of pooled titers showing optimal diagnostic accuracy. The area under the curve (AUC), sensitivities (Se), specificities (Sp), and positive (PPV) and negative (NPV) predictive values were calculated. The regression equation between pooled titers (pool) and mean individual titers (mean) was: $pool= 1.2498+0.8952{\times}mean$, with coefficient of determination of 87% (p< 0.0001). The optimal cut-off points of pooled titers were titer 8 for criterion 1 (AUC=0.975, Se=0.883, Sp=0.959, PPV=0.985, NPV=0.728), titer 8 for criterion 2 (AUC=0.969, Se=0.954, Sp=0.855, PPV=0.926, NPV=0.907), titer 9 for criterion 3 (AUC=0.970, Se=0.836, Sp=0.967, PPV=0.978, NPV=0.772), and titer 9 for criterion 4 (AUC= 0.946, Se=0.928, Sp=0.843, PPV=0.857, NPV=0.921). The difference of 'prevalence estimated by individual and pooled sample showed a minimum of 2% for criteria 2 and a maximum of 9.1:% for criteria 3. These results indicate that the use of pooled sera in HI test for screening IBV infection in laying hen flocks is considered as a cost-effective method of testing large numbers of samples with high diagnostic accuracy.

• Journal of the Korean Institute of Landscape Architecture
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• v.13 no.2
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• pp.71-90
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• 1985

^x This study is composed of four Process. Process 1 suggests the background, purpose and necessity to provide with criteria for establishing Korean-style house preservation area including the present situation of the established area in our country. Also it is provided with the approach and the substantial realm to discuss the established criteria for the subject of this thesis. Process 2 dealt with theoretical parts as a premise to suggest the established criteria for the Korean- style house preservation area : 1) Original background of the Korean- style house, characteristic of the Korean traditional housing, changed situation of the Korean- style house based on the epoch, classified into the characteristic of the Korean- style house. 2) The characteristic of the Korean- style house and its values existed in the present urban areas are investigated by synthesizing such contents. 3) The significance for establishing the preservation area of the Korean- style houses in urban areas which is insufficient systematically in suggested as follows : First, establishment of the preservation area of the Korean- style houses with regard to the traditional succession of cultural properties. Second, acknowledging preservation problems of cultural properties in our country due to the world- wide tendency, preservation of historical environment of new comprehensive concept for the preservation of cultural properties. Process 3, as a case study on the establishment of the preservation area, describes a framework for investigating and analyzing the status by reviewing the present situation of the Korean- style preservation area in Seoul city which is established as the preservation area. Process 4 suggests seven criteria with regard to the establishment of the preservation area. 1) A decisive criterion for the Korean- style house to divide into Korean- style house and non- Korean style house (proper building and nonproper building) for the preservation. 2) A concrete decisive criterion for the Korean- style house with regard to valuable endowment with dominent factors in its landscape. 3) A decisive criterion for the review of the landscape preservation for the nonproper building. 4) Suggesting logical evidences for the above second and third criterion (suggesting appropriateness). 5) Dividing into following two criteria for the decision of the building condition. a) A decisive criterion of the Korean- style house's condition. b) A decisive criterion of non- Korean style house's condition. 6) A selective criterion for the preservation building after synthesizing above five criteria. 7) Final criterion for establishing the preservation area with regard to systematic particulars.

• Korean Journal of Culture and Social Issue
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• v.14 no.4
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• pp.103-117
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• 2008

The polygraph test administered by the Korean Prosecutors Office for crime investigations customarily uses the score of -12 as the cutoff point separating the subjects who lie from those who tell the truth. The criterion used by the KPO is different from the one (-13) suggested by Backster (1963) who invented the particular method for lie detection. Based on the signal detection theory applied to the real polygraph test data obtained from real crime suspects by the KPO, the present study identified the score of -8 as an optimal criterion resulting in the highest overall accuracy of the polygraph test. The classification of the subjects with the score of -8 as the criterion resulted in the highest accuracy (83.17%) compared with the accuracies of classifications with the Backster's criterion (76.24%) and the KPO's criterion (80.20%). However, the new criterion was also found to result in more false-positive cases. Based on the results from the present study, it was recommended to use the score of -8 as the criterion when the overall accuracy is important but the score of -12 or -13 when avoiding false-positive is more important than securing the overall accuracy.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2012.05a
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• pp.725-726
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• 2012

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 1992.03a
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• pp.59-70
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• 1992

Appropriate yield criteria are necessary to perform computer simulation for densification processes of powder compacts and sintered metals. Various yield functions have been reviewed and a new form for yield criterion has been advanced. The yield criterion satisfies experimental results from combined tension and torsion tests of sintered porous iron specimens.

• Korean Journal of Mathematics
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• v.18 no.4
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• pp.369-380
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• 2010

We give a criterion for vertex extremal length parabolicity of locally finite planar graphs, and use it to show that a disk triangulation graph is circle packing parabolic if and only if its immediate finer graphs are circle packing parabolic.