• The Journal of Korean Institute of Communications and Information Sciences
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• v.23 no.4
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• pp.901-913
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• 1998

This paper presents a new analytical approach for the evaluation of the reverse link interference in a CDMA cellular system with unequal cell loading. In particular, the dynamic nature of the reverse link power control has been taken into account in the proposed approach so that a realistic effect of unequal cell loading, including the shadowing and soft handoff, on system capacity may be precisely captured. This is aspect that has not beensuccessfully formmulated and rarely attempted tosolve in any previous analytical approach. Our computational result shows that as the loading of every tier of surrounding cells is doubled, the subscriber capacity of the reference cell can be reduced as much as 27% of that obtained in the case that the effect of power control is not appropriately modeled.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.24 no.11
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• pp.840-845
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• 2014

Vibration profiles consist of two kinds of pattern, random and harmonic, at general engineering problems and the detailed vibration test mode of a target system is decided by the spectral condition that is exposed under operation. In moving mobility, random responses come generally from road source; whereas the harmonic responses are triggered from rotating machinery parts, such as combustion engine or drive shaft. Different spectral input may accumulate different damage in frequency domain since the accumulated fatigue damage dependent on the pattern of input spectrum in high cyclic loading condition. To evaluate the sensitivity of spectral damage according to different loading conditions, a linear elastic system is introduced to conduct a uniaxial vibration testing. Measured data, acceleration and strain, is analyzed using energy isocline function and then, the calculated fatigue damage is compared by different loading cases, random and harmonic.

• Earthquakes and Structures
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• v.17 no.4
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• pp.399-409
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• 2019

This paper presents the experimental investigations on the seismic performance of a peculiar steel-concrete vertical hybrid structural system referred to as steel truss-RC tubular column hybrid structure. It is typically applied as the supporting structural system to house air-cooled condensers in thermal power plants (TPPs). Firstly, pseudo-dynamic tests (PDTs) are performed on a scaled substructure to investigate the seismic performance of this hybrid structure under different hazard levels. The deformation performance, deterioration behavior and energy dissipation characteristics are analyzed. Then, a cyclic loading test is conducted after the final loading case of PDTs to verify the ultimate seismic resistant capacity of this hybrid structure. Finally, the failure mechanism is discussed through mechanical analysis based on the test results. The research results indicate that the steel truss-RC tubular column hybrid structure is an anti-seismic structural system with single-fortification line. RC tubular columns are the main energy dissipated components. The truss-to-column connections are the structural weak parts. In general, it has good ductile performance to satisfy the seismic design requirements in high-intensity earthquake regions.

• Advances in concrete construction
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• v.15 no.6
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• pp.377-389
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• 2023

In this study, an improved modular arch system with the lower arch space composed of a precast arch block and an outrigger was proposed as an underground culvert, and its applicability and structural behaviors were confirmed. This modular arch culvert structure with vertical walls was designed using precast blocks and by adjusting the placement spacing of concrete blocks to the upper part form an arch shape and the lower part form a vertical wall shape, based on previously researched modular arch systems. Owing to the vertical wall of the proposed modular arch system, it is possible to secure a load-carrying capacity and an arch space that can sufficiently resist the earth pressure generated from the backfill soil and loading on the arch system. To verify the structural characteristics, and applicability of the proposed modular precast arch culvert structure, a full-scale modular culvert specimen was fabricated, and a loading test was conducted. By examining its construction process and loading test results, the applicability and constructability of the proposed structure were analyzed along with its structural characteristics. In addition, its the structural predictability and safety for the applicability were evaluated by comparing the construction process and loading test results with the FE analysis results.

• The Journal of Korean Academy of Prosthodontics
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• v.33 no.2
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• pp.335-353
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• 1995

The purpose of this study was to the determine the optimal torques values to tighten the retaining screw. 3-different implant system tested were as follows : Branemark implant system$(3.75mmD{\times}100mm)$, Steri-Oss implant system$(3.8mmD{\times}10mm)$. One fixtures of each implant system was mounted into the epoxy resin block and abutment/superstructure complex was constructed. Eighty dental college students(male : 40, female : 40) of Chosun University were selected and were asked to tighten the retaining screws. Abutment/superstructure complex of each implant system was tightened to the maximum torque by use of hand-held screw driver, and then torque value was measured with torque value was measured with torque driver(Tohnichi torque driver, model 20 FTD, Tohnichi MFG, Co., LTD., Tokyo, Japan). Abutment/superstructure complex of each implant system was titghtened to each torque of 10 N-cm, 20 N-cm and 30 N-cm, and then the dynamic load(vertical & diagonal load) was applied to the abutment / superstructure complex. The gap between abutment/superstrure in each implant system was measured with 3-dimensional measuring microscope(model No. 850, Germany). The results were as follow : 1. Torque values according to the individual subjects showed wide range. 2. Torque values according to sex showed statistical significant difference. Those are as follows : in case of male, $9.38{\pm}2.93$ N-cm ; incase of female, $7.80{\pm}2.25$ N-cm. 3. Torque values according t implant systems showed statistical significant difference. Those are as follows : in ase of Branemark implant system, $6.54{\pm}1.54$ N-cm : in ase of Steri-Oss implant system, $10.1{\pm}2.88$ N-cm ; in case of IMZ implant system, $9.18{\pm}2.17$ N-cm. 4. The more torque value of tightening screw was increased, the less the gap was after the vertical and diagonal loading. 5. The gap after the diagonal loading was greater than that after the vertical loading. 6. The magnitude of gap between abutment/superstructure in order of IMZ, Steri-Oss, Branemark implant system after the verical and diagonal loading. 7. The gap under the diagonal loading after applying 30 N-cm torque showed no statistical significant difference in cases of the Branemark system and the Steri-Oss implant system but it showed significant different in case of the IMZ implant system.

• Journal of Institute of Control, Robotics and Systems
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• v.11 no.9
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• pp.816-821
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• 2005

The remote operation of $4\~5$ cranes for container loading/unloading at a port by one operator will dramatically improve loading/unloading efficiency through productivity increase, cost reduction, and so on. This study develops a remote crane control system for container loading/unloading yard cranes. First, a wireless video and audio system to transmit views and sounds of the working field is designed by using 3 web cameras and a microphone. Next, a RSVP-based multi-path reservation method is presented with a view to improving the quality of service in the communication network for remote control. Simulation results show that a RSVP-based multi-path reservation can enhance the reservation success rate in the TCP/IP network.

• Journal of Korean Institute of Industrial Engineers
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• v.20 no.2
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• pp.19-30
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• 1994

Generally, a planning problem in a flexible manufacturing system is considered to be a composite of three interdependent tasks : part selection, loading, and routing mix. This research presents a mathematical model which can concurrently solve part selection, loading, and routing mix problems, so the problems that are caused by treating the planning problems independently are solved. The mathematical model is aimed to minimize system unbalance and the number of late parts, including constraints such as machine capacity, tool magazine capacity, and tool inventory. To illustrate the application of the model, an example is included. Solution procedure based on Lagrangian relaxation is also suggested for larger-sized problems.

• Journal of Korea Technical Association of The Pulp and Paper Industry
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• v.35 no.3
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• pp.1-12
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• 2003

The complexity of the papermaking system accelerates interactions between a large number of variables involved. The process operation, therefore, is subject to frequent perturbations by disturbance. Dynamic modelling is a useful tool for characterizing the transient behavior and selecting the best control strategies to reject disturbances. In this study we developed a dynamic simulation model of a fine paper production process, which consists of stock preparation, wire sections, white water circulations, and broke system. It focused on dynamic simulation in its role for developing control strategies and studying control loop dynamics related to filler loading for ash control. The results emphasized the importance of filler-loading position and length of control loop for rapid ash control and process stabilization.

• Structural Engineering and Mechanics
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• v.67 no.3
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• pp.267-275
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• 2018

A numerical study of soil-foundation system under monotonic and cyclic pushover loading is conducted, taking into account both material and geometric nonlinearities. A complete and refined 3D finite element (FE) model, using contact condition and allowing separation between soil and foundation, is implemented and used in order to evaluate the nonlinear relationship between applied vertical forces and induced settlements. Based on the obtained curve, a simplified model is proposed, in which the soil inelasticity is satisfactorily represented by two vertical springs with trilinear behavior law, and the foundation uplifting is insured by gap elements. Results from modeling soil-foundation system supporting a bridge pier have shown that the simplified model is able to capture irreversible settlements induced by cyclic rocking, due to soil inelasticity and vertical loading, as well as large rotations due to foundation uplifting.

• Journal of Navigation and Port Research
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• v.30 no.4
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• pp.285-290
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• 2006

Shipping companies consider most of the ship turnaround time as a critical factor when selecting a rolling port for reducing costs. So, many researchers have been studying for the optimization of preplanning and high~performance of the Gantry Cranes (GCs) in container terminals for faster loading and unloading. Therefore, in this paper, we propose an RFID (Radio Frequency Identification) based RTLS (Real-Time Location System) for reducing the ship turnaround time in ubiquitous port environment. In addition, pre-planning based on ubiquitous computing environment will support the GC and Yard Tractors (YTs), and reduce ship turnaround time more effectively. Especially, the proposed method enormously enhances the productivity of loading for the twin-lift system It will reduce the whole lead-time in the process of port logistics.