• Journal of the Korea institute for structural maintenance and inspection
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• v.19 no.4
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• pp.1-9
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• 2015

This study is on the shear strength of the internal joints of RCS composite structure consisting of reinforced concrete column and steel beam. As a newly structure system, the composite system has been developed to fully utilize the advantages of reinforced concrete column and steel beam, which also include economic and practical joint detail. Nevertheless stress transfer mechanism and structural behavior of the joints had not been still clearly revealed and shown much difference from the proposed equation. In this study, by observing the crossing of reinforced concrete column through steel beam to the RCS structure beam type, thirty seven shear failure specimens were selected and applied to the 5 major equations which is used to calculate the shear strength of RCS joint. Through the regression analysis, modified equation which is more reliable and approximate results for shear strength of RCS joints was proposed.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.32 no.3C
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• pp.121-127
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• 2012

This paper investigates the response of frame structures with the consideration of tunnel construction (ground loss) conditions. The response of four-story open frame structure and block-infilled frame structures, which are subjected to tunnelling-induced ground movements, has been investigated in different construction (ground loss) conditions using numerical analysis. The open frame structure has been modelled as an elastic structure, while the block-infilled frame structure has been modelled to have real cracks when the shear and tensile stress exceed the maximum shear and tensile strength. The response of the two different frame structures has been investigated in terms of construction (ground loss) conditions considering the magnitude of deformations and cracks in structures. In addition, the damage levels, which are possibly induced in the structures, has been provided in terms of construction (ground loss) conditions using the state of strain damage estimation criterion (Son and Cording, 2005). The results of this study will provide a background for better understandings for controlling and minimizing building damage on nearby frame structures due to tunnelling-induced ground movements.

• Journal of the Korea Institute of Military Science and Technology
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• v.21 no.2
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• pp.173-179
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• 2018

Estimating reliability of a non-repairable system using the degradation data, variance assumption such as homogeneity (constant) or heteroscedasticity (time-variant) could affect accuracy of reliability estimation. This paper showed reliability estimation and comparison results under normal conditions using accelerated degradation data obtained from destructive measurements, according to variance assumption of the data at each measurement time. Degradation data from three accelerated conditions with stress factors of temperature and humidity were used to estimate reliability. The $B_{10}$ lifetime was estimated as 1243.8 years by constant variance assumption, and 18.9 years by time-variant variance. And variance assumption provided different analysis results of important stresses to reliability. Thus, accurate assumption of variance at each measurement time is required when estimating reliability using degradation data of a non-repairable system.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.14 no.9
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• pp.4142-4148
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• 2013

Because of effective fruit growing and management in the slope land, the use of orchard vehicle with lifting utilities has been increased. For this reason the study on the stability of that vehicle for worker's safety is needed. This study is investigated on the stability estimation of orchard vehicle with four wheels and dual rectangular-type lifting utilities which can be moved on the dirt sloping load. Through the multi-body dynamics analysis on the vehicle mechanism, overturning angles of 19.2 and $34.6^{\circ}$ in the right-left and front-rear direction can be calculated. It is determined tractive resistances and required powers of the wheels. And through the finite element analysis on the frame of lifting utility its maximum von-Mises stress is 146 MPa and it is structural stable. Therefore it is known that the orchard vehicle with wheels and lifting utilities has static and dynamic stability.

• Journal of the Korean Geophysical Society
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• v.7 no.4
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• pp.313-324
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• 2004

The finite element method and statistics of the convergence measurement are useful method of the stability analysis of the tunnel adjacent to the pier. It is the purpose of the this case study to certificate of validity of the application of those methods. The safety of the pilot tunnel method and LW pre-grouting has been evaluated from the FEM analysis. The three-dimensional finite element method is carried out for the decision of the level of stress redistribution at the two-dimensional numerical analysis. An analysis of the convergence is carried out by the estimation of preceding convergence at tunnel excavation. F-examination is applied for this estimation. As results of that analysis, The F-value is from 10.81 to 158.74 and the coefficient of determination is from 0.82 to 0.99. An analysis of convergence is carried out by using regression analysis. Consequently, it is shown that the convergence can be modeled as following function C(t) = a[1-exp(-bt)].

• Journal of the Society of Naval Architects of Korea
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• v.58 no.5
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• pp.330-338
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• 2021

This paper focuses on the improvement of the influence coefficient matrix method for estimation of local ice load on the icebreaking research vessel ARAON. The influence coefficient matrix relates ice pressure on the hull plate to the measured/calculated hull strain/stress. Conventionally von Mises equivalent stresses representing hull stresses and ice pressure acting on the hull plate are utilized to assemble the influence coefficient matrix. Because of the three dimensional features of the ship-ice collision process, an enhanced method to assemble the influence coefficient matrix is derived considering ice loads in the X, Y, and Z direction simultaneously. Furthermore the location of ice loads acting on hull-plate may fall outside the measuring sensor area, and the enhanced influence coefficient matrix is modified to reduce the difference between the actual and the estimated ice loads by expanding the domain outward from the sensor area. The developed method for enhanced influence coefficient matrix is applied to IBRV ARAON during the 2019 Antarctic ice field test and the local ice loads in three directions are efficiently calculated compared to those by a conventional method.

• Journal of Radiation Protection and Research
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• v.46 no.4
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• pp.170-177
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• 2021

Background: The International Commission on Radiological Protection is preparing to provide reference dose coefficients for environmental radioiodine intake based on newly developed age-specific biokinetic models. However, the biokinetics of iodine has been reported to be strongly dependent on the dietary intake of stable iodine; for example, the thyroidal uptake of iodine may be substantially lower in iodine-rich regions than in iodine-deficient regions. Therefore, this study attempted to establish a system of age-specific thyroid dose estimation for South Koreans, whose daily iodine intakes are significantly higher than that of the world population. Materials and Methods: Korean age-specific biokinetic parameters and thyroid masses were derived based on the previously developed Korean adult model and the Korean anatomical reference data for adults, respectively. This study complied with the principles used in the development of age-specific biokinetic models for world population and used the ratios of baseline values for each age group relative to the value for adults to derive age-specific values. Results and Discussion: Biokinetic model predictions based on the Korean age-specific parameters showed significant differences in iodine behaviors in the body compared to those predicted using the model for the world population. In particular, the Korean age-specific thyroid dose coefficients for ¹²⁹I and ¹³¹I were considerably lower than those calculated for the world population (25%-76% of the values for the world population). Conclusion: These differences stress the need for Korean-specific internal dose assessments for infants and children, which can be achieved by using the data calculated in this study.

• Journal of the Korean Geotechnical Society
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• v.24 no.11
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• pp.133-141
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• 2008

In this study, a new method for estimating the undrained shear strength $s_u$ of saturated clays using piezocone penetration test (CPTu) result is proposed. This is to develop more effective CPTu-based $s_u$ estimation method at lower cost with less uncertainty. For this purpose, a marine clay deposit is selected and tested through extensive experimental testing program including both in-situ and fundamental laboratory tests. The proposed method is based on a correlation between the undrained shear strength $s_u$ and the cone resistance $q_t$, without introduction of the total overburden stress into the $s_u-q_t$ correlation. As a result, no additional testing procedure for collecting undisturbed soils samples is required, which can reduce overall testing cost. To verify the proposed method, 4 test sites, which consist of a variety of soil conditions, are selected and used for comparison between measured and predicted undrained shear strength. From comparison, it is seen that predicted values of $s_u$ using the proposed method match well those from measured results.

• Journal of the Korean Geotechnical Society
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• v.23 no.5
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• pp.89-100
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• 2007

In this study, various field and laboratory tests were performed to investigate the characteristics of shear strength and bearing behavior to be considered in the estimation of stability and trafficability in early stage of stabilization process in marine clay dredged deposit. Site characterization was carried out to grasp the basic properties of the deposit. Field vane test, unconfined compression test and direct shear test were conducted to evaluate the shear strength distribution for varied depths, and the characteristics of shear strength and stress-strain behavior of the crust layer. Plate load tests were also performed to estimate the bearing capacity and to assess load-settlement behavior and failure pattern of the deposit. The bearing capacity was also estimated using previously proposed methods for double-layered clay deposit. The estimated bearing capacity was compared with the results of the plate load tests and then, the applicability of the estimation method was discussed.

• Journal of the Korean Geotechnical Society
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• v.39 no.5
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• pp.5-12
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• 2023

This study investigates the existing models for estimating the shear strength of rock joints, presents related problems, and introduces a newly proposed model to overcome the problems. The results of many experimental tests show that the shear strength of a rock joint depends on many complex factors, including asperity angle, compressive strength, applied normal stress, friction angle, asperity cohesive strength, and progressive damage of asperities. However, the existing models do not account for these factors enough. To overcome these problems, Son (2020) developed a new model to estimate the shear strength of rock joints and confirmed its reliability by comparing with experimental results and existing models. In this paper, the developed model was used to investigate the various factors that affect the joint shear strength, and the results were compared and analyzed. Through this study, the factors that affect the shear strength of the rock joint could be identified in more detail.