• Journal of the Korea Concrete Institute
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• v.29 no.4
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• pp.353-360
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• 2017

The objective of this study is theoretical and empirical evaluation of the flexural performance of concrete filled pretensioned spun high strength concrete pile with ring type composite shear connectors (CFP pile). The specimens are comprised of standard CFP pile, PHC pile+composite shear connector+filed concrete (CFP-N-N), standard CFP pile with $1^{st}$ reinforcements (H13-8ea), and standard CFP pile with $1^{st}$ and $2^{nd}$ reinforcements(H19-8ea). Flexural performance evaluation results showed that the ductility is improved with increased steel ratio, which leads to the increased maximum load by 46.4% (with $1^{st}$ reinforcement) and 103.9% (with $1^{st}$ and $2^{nd}$ reinforcements) compared to standard CFP ( CFP-N-N). Comparing with the predicted ultimate limit state values of the CFP pile design method and the experimental results, the design method presented in this study is reasonable since safety factor of 1.23 and 1.40 times for each reinforcement step are secured.

• Journal of Korea Water Resources Association
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• v.30 no.6
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• pp.679-690
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• 1997

The risk assessment model for hydrlolgic safety analysis of dam and levee in developed by using Monte-Carlo and AFOSM (Advanced First-Order Second-Moment) method. The fault tree analysis and four phases approach are presented for the safety eveluation of risk of dam and levee. The risk model consists of rainfall-runoff analysis, reservoir routing and channel routing considering the variations in the model parameter. For the rainfall-runoff analysis, KRRL method is adopted with 200-year precipitation and PMP (Probable Maximum Precipitation). Reservoir routing is performed by fourth order Runge-Kutta method and channel routing by standard step method. The suggested model will contribute to safety evaluation of dam and levee and their rehabilitation decision problem.

• Journal of Korean Society of Steel Construction
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• v.16 no.5 s.72
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• pp.683-694
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• 2004

Advanced analysis and optimal design of semi-rigid space steel frames were presented. The advanced analysis can predict the combined nonlinear effects of connection, geometry, and material on the behavior and strength of semi-rigid frames. The Kishi-Chen power model was used to describe the nonlinear behavior of semi-rigid connections. Geometric nonlinearity was determined using stability functions. Material nonlinearity was determined using the Column Research Council (CRC) tangent modulus and the parabolic function. The direct search method proposed by Choi and Kim was used as optimization technique. One by one, the member with the largest unit value evaluated using the LRFD interaction equation were placed adjacent to a larger member selected from the database. The objective function was assumed to be the weight of steel frame, while the constraint functions were load-carrying capacities, deflections, inter-story drifts, and the ductility requirements. The member sizes determined using the proposed method were compared to those derived from the conventional LRFD method.

• Journal of Korean Society of Steel Construction
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• v.15 no.6 s.67
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• pp.661-672
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• 2003

The advanced analysis and optimal design of semi-rigid frame were presented. Advanced analysis can predict the combined nonlinear effects of connection, geometry, and material on the behavior and strength of semi-rigid frames. The Kishi-Chen power model was used to describe the nonlinear behavior of semi-rigid connections. Geometric nonlinearity was determined using stability functions. On the other hand, material nonlinearity was determined using the Column Research Council (CRC) tangent modulus and parabolic function. The direct search method proposed by Choi and Kim was used as optimization technique. The member with the largest unit value evaluated using the LRFD interaction equation was replaced one by one with an adjacent larger member selected from the database. The objective function was assumed as the weight of steel frame, with the constraint functions accounting for load-carrying capacities, deflections. inter-story drifts, and ductility requirement. Member sizes determined by the proposed method were compared with those derived using the conventional LRFD method.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.42 no.3
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• pp.229-236
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• 2014

In this paper, the guidance laws and controllers for the gliding guided artillery munition is studied. The gliding guided artillery munition has wings for gliding to increase a range; therefore previous guidance laws and controllers for the guided munition could not be applied. Concepts of vector field guidance and proportional navigation guidance are applied for mid-term and terminal guidance, respectively. The gliding guided artillery munition is operated within wide altitude and speed areas; therefore, the controllers are designed for each area, and gain-scheduling and the linear interpolation technique is applied to compute the appropriate gains.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.19 no.2
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• pp.243-253
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• 2019

First steps of Planetary exploration are usually conducted with the use of autonomous rovers. These rovers are capable of finding its own path and perform experiments about the planet's surface. This paper makes a proposal for a multi-agent system which effectively take the advantage of a blackboard system for share knowledge and effort of each agent. Agents use Reactive Model with the combination of Belief Desire Intension (BDI) Model and also use a Path Finding Algorithm for calculate shortest distance and a path for travel on the planet's surface. This approach can perform a surface exploration on a given terrain within a short period of time. Information which are gathered on the blackboard are used to make an output with detailed surface soil variance results. The developed Multi-Agent system performed well with different terrain sizes.

• The Korean Journal of Applied Statistics
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• v.23 no.5
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• pp.857-870
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• 2010

This study was conducted to investigate the relationship between the socio-demographic factors and the Korean consumers palatability evaluation grades with Hanwoo sensory evaluation data from 2006 to 2008 by National Institute of Animal Science. The dichotomy logistic regression model and the multinomial logistic regression model are fitted with the independent variables such as the consumer living location, age, gender occupation, monthly income, beef cut and the the palatability grade as the categorical dependent variable and tenderness, 리avor and juiciness as the continuous dependent variable. Stepwise variable selection procedure is incorporated to find the final model and odds ratios are calculated to nd the associations between categories.

• Journal of Korean Tunnelling and Underground Space Association
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• v.19 no.2
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• pp.109-120
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• 2017

Groundwater seepage into a tunnel is one of the main causes triggering tunnel collapse and the consequent ground subsidence. Thus, it is important to estimate adequately the groundwater inflow rate and porewater pressure change during tunneling with time elapse. In current practice, Goodman's analytical solution (or image tunnel method) assuming homogeneous ground condition around a tunnel is commonly used for estimating groundwater inflow rate. However, the generally-used analytical solution for estimating groundwater inflow rate does not consider groundwater level drawdown and permeability change with depth, and the inflow rate can be overestimated in design phase. In this study, parametric study was performed in order to investigate the effect of groundwater level drawdown and permeability reduction with depth, and transient flow analysis was carried out for studying the inflow rate change as well as groundwater level and porewater pressure change around a tunnel with time elapse.

• Proceedings of the Korean Radioactive Waste Society Conference
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• 2004.06a
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• pp.137-146
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• 2004

Laser Induced Breakdown Spectroscopy(LIBS) system is being developed as an in-situ analysis system for the radioactive waste glass in the cold crucible melter. In order to complete the LIBS system, a spectrometer, a detector, and a laser were structured. An ESA 3000 (LLA Instruments GmbH, Germany) including a calibrated Kodak KAF-1001 CCD detector was selected as the spectrometer. A Q-switched Nd-YAG Brilliant(Quantel, France) laser was selected as an energy source. As the first research stage, the excitation temperatures of Fe(I) as a function of the detector's delay intervals(500, 1000, 1500, 2000ns) were evaluated using the Einstein-Boltzmann equation. The optimized excitation temperature of Fe (I) was 7820k at the delay time of 1500㎱ using the 532nm Nd-YAG laser pulse. This LIBS system will be optimized under the real environment vitrification facility in the near future and then used to be in-situ analyzed the glass compositions in the melter qualitatively.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.12 no.4
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• pp.157-165
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• 1992

IMS, a precision coordinate measuring system using theodolites, is being used to survey and align precision mechanical structures. Compared to conventional mechanical devices for precision measurement, such as CMM (Coordinate Measuring Machine), the target objects of IMS have little limitations in their sizes and shapes, and can be measured in place. Also since IMS displays the coordinate values in real-time, it is possible to perform measurement and alignment of the objects simultaneously. In this paper, the elements and functions of IMS are introduced and a mathematical model of the new software, which utilizes an altered version of the 'Bundle' adjustment algorithm of analytical photogrammetry for the specific use of IMS, is demonstrated. Differences of the mathematical model of IMS from that of analytical photogrammetry are discussed by following the steps of the 'Measurement' option in the 'Main Menu' of the software. A new IMS calibration method is proposed to calculate better first approximations for the 4 unknown theodolite parameters and the coordinates of target objects. The software provides the 'Bundle' procedure for the first approximations of the unknowns before the real-time measurement. It also provides an opportunity of 'bundling' to re-adjust the collected positional data at the end of the measurement.