• Geotechnical Engineering
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• v.13 no.5
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• pp.101-124
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• 1997

The root pile system is insitu soil reinforcement technique that uses a series of reticulately installed micropiles. In terms of mechanical improvement by means of grouted reinform ming elements, the root pile system is similar to the soil nailing system. The main difference between root piles and soil nailing are due to the fact that the reinforcing bars in root piles are normally grouted under high pressure and that the alignments of the reinforcing members differ. Recently, the root pile system has been broadly used to stabilize slopes and retain excavations. The accurate design of the root pile system is, however, a very difficult tass owing to geometric variety and statical indetermination, and to the difficulty in the soilfiles interaction analysis. As a result, moat of the current design methods have been heavily dependent on the experiences and approximate approach. This paper proposes a quasi-three dimensional method of analysis for the root pile system applied to the stabilization of slopes. The proposed methods of analysis include i) a technique to estimate the change in borehole radium as a function of the grout pressure as well as a function of the time when the grout pressure is applied, ii) a technique to evaluate quasi -three dimensional limit-equilibrium stability for sliding, iii) a technique to predict the stability with respect to plastic deformation of the soil between adjacent root piles, and iv) a quasi -three dimensional finite element technique to compute stresses and dis placements of the root pile structure barred on the generalized plane strain condition and composite unit cell concept talon형 with considerations of the group effect and knot effect. By using the proposed technique to estimate the change in borehole radius as a function of the grout pressure as well as a function of the time, the estimations are made and compar ed with the Kleyner 8l Krizek's experimental test results. Also by using the proposed quasi-three dimensional analytical method, analyses have been performed with the aim of pointing out the effects of various factors on the interaction behaviors of the root pile system.

• Journal of the Korean Mathematical Society
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• v.59 no.4
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• pp.717-731
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• 2022

We introduce the notion of quasi-roots and study their uniqueness in right-angled Artin groups.

• Journal of the Korean Mathematical Society
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• v.33 no.4
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• pp.865-878
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• 1996

We consider numerical methods for finding a solution to a nonlinear system of algebraic equations $$ (1) f(x) = 0, $$ where the function $f : R^n \to R^n$ is ain $x \in R^n$. In [10], a quasi-Gauss-Newton method is proposed and shown the computational efficiency over SQRT algorithm by numerical experiments. The convergence rate of the method has not been proved theoretically. In this paper, we show theoretically that the iterate $x_k$ obtained from the quasi-Gauss-Newton method for the problem (1) actually converges to a root by Kantorovich-type convergence analysis. We also show the rate of convergence of the method is superlinear.

• English Language & Literature Teaching
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• v.18 no.3
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• pp.191-206
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• 2012

This study examines the use of the modals and quasi-modals of obligation and necessity, which involves the layering of must, should, have (got) to, got to, and need to in a corpus of cross-cultural communication between EFL learners. The study compares the EFL learners' corpus with a sub-corpus of ICE-GB in terms of token counts and semantic/functional distributions because International Corpus of Standard varieties of English serves as common reference points for international comparison of varieties of English. The results showed that must, should, and have to were the main players in both the corpus of EFL learners and that of native speakers. However, some discrepancy exists between EFL learners' corpus and the native speakers' corpus in the use of the modals and quasi-modals of obligation and necessity. Compared to the corpus of native speakers, the corpus of EFL learners was distinctively different in the relative unpopularity of have to and in the comparative popularity of must particularly for root meaning. Suggestions were made for using computer corpora in understanding EFL learners' language use. And pedagogical implications were made for teaching English modality considering the current usage of the modals and quasi-modals in Standard varieties of English and helping the students develop pragmatic competence.

• Journal of the Korean Society of Combustion
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• v.4 no.1
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• pp.131-139
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• 1999

A Numerical Analysis of NOx production in Hydrogen-Air flame is performed using the quasi-laminar reaction modelling. As results, in low global strain rate region, $U_F/D_F\;{\leq}\;50,000$, the quasi-laminar reaction modelling reproduces the experimentally observed EINOx half power scaling that the ratio of EINOx and flame residence time, $L_f^3(D_F^2U_F)$, is proportional to the square root of global strain rate. Thus, it suggests that turbulence-chemistry interaction has a minor impact on the trend of NOx production in low global strain rate region. However, the quasi-laminar reaction modelling predicts the higher temperature and NOx than experimentally observed. This overprediction may be due to the lack of radiation and quasi-laminar reaction modelling.

• Journal of Welding and Joining
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• v.2 no.2
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• pp.62-69
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• 1984

In this study, cold crack susceptibility of high strength steel (ABS EH32 Steel) welded zone with shielded metal are welding was investigated by tensile restraint cracking test method. Effects of diffusible hydrogen content on root cracking, lower critical stress, crack initiation and fracture mode, hardness value distribution of welded zone and fractograph were mainly investigated. Following conclusions are made: 1. In the view of the lower critical stress level, wet electrode, containing much diffusible hydrogen content shows lower value than dried electrode. 2. Hardness value(Hv 5kg) in Heat Affected Zone of wet electrode is higher than that of dried electrode caused by hydrogen embrittlement. 3. In the case of wet electrode, root crack is initiated and propagated in Heat Affected Zone and then propagated to weld metal, but using of dried electrode, root crack is initiated in Heat Affected Zone and propagated to weld metal without propagating in HAZ. 4. For wet electrode, quasi-cleavage fracture mode is majorly observed on the fracture surface of HAZ and partially of weld metal due to hydrogen embrittlement.

• Journal of Information Management
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• v.40 no.4
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• pp.135-150
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• 2009

Existing bibliometric laws have been established on the basis of well defined science journals with a long history. However, the history of technology innovation research in Korea is young and the scope of the research is diverse compared with other fields. The main purpose of this research can be summarized as follows : Can the traditional bibliometric laws be used to explain the young and diverse data derived from technology innovation studies in Korea. Second, we want to compare the explain ability of the power law, compared with the traditional laws in the field. Third, we propose a quasi index related to the well-known impact factor to measure the contribution of a journal or a group of journals to the development of innovation research in Korea. We confirmed Lotka's and Bradford's laws which are used to measure the productivity of researchers, but we could not support the validity of Price's Square Root law as Nicholls (1998) could not. On the citations to journals, Garfield's laws is not observed. However, the power law fits well the citations to author, journal, article, and book. The estimated parameters between 1.6 and 3.5 are similar to the values in the range of 1.5 and 3 in previous studies. Finally the quasi index shows that the influence of international leading journals on innovation research in Korea is weaker than on innovation studies in the world.

• Earthquakes and Structures
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• v.21 no.6
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• pp.641-652
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• 2021

Digging well foundation has been widely used in railway bridges due to its good economy and reliability. In other instances, bridges with digging well foundation still have damage risks during earthquakes. In this study, a new type of digging well foundation with prefabricated roots was proposed to reduce earthquake damage of these bridges. Quasi-static tests were conducted to investigate the failure mechanism of the root digging well foundation, and then to analyze seismic behaviors of the new type well foundation. The testing results indicated that these prefabricated roots could effectively limit the rotation and uplift of the digging well foundation and increase the lateral bearing capacity of the digging well foundation. The elastic critical load and ultimate load can be increased by 69% and 36% if prefabricated roots were added in the digging well foundation. The prefabricated roots drived more soil around the foundation to participate in working, the stiffness of the bridge pier with root digging well foundation was improved. Moreover, the root participation could improve the energy dissipation capacity of soil-foundation-pier interaction system. The conclusions obtained in this paper had important guiding significance for the popularization and application of the digging well foundation with prefabricated roots in earthquake-prone zones.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2004.10a
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• pp.174-179
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• 2004

The paper deals with gravitational effect on dynamic stability of a cantilevered pipe conveying fluid. The eigenvalue branches and modes associated with flutter of cantilevered pipes conveying fluid are fully investigated. Governing equations of motion are derived by extended Hamilton's principle, and the solutions are sought by Galerkin's method. Root locus diagrams are plotted for different values of mass ratio of the pipe, and the order of branch in root locus diagrams is defined. The flutter modes of the pipe at the critical flow velocities are drawn at every one of the twelfth period. The transference of flutter-type instability from one eigenvalue branches to another is investigated thoroughly.

• Journal of the Korean Society for Precision Engineering
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• v.23 no.4 s.181
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• pp.67-74
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• 2006

The paper presents gravitational effect on eigenvalue branches and flutter modes of a vertical cantilevered pipe conveying fluid. The eigenvalue branches and modes associated with flutter of cantilevered pipes conveying fluid are fully investigated. Governing equations of motion are derived by extended Hamilton's principle, and the related numerical solutions are sought by Galerkin's method. Root locus diagrams are plotted for different values of mass ratios of the pipe, and the order of branch in root locus diagrams is defined. The flutter modes of the pipe at the critical flow velocities are drawn at every one of the twelfth period. The transference of flutter-type instability from one eigenvalue branches to another is investigated thoroughly.