• Journal of Korean Tunnelling and Underground Space Association
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• v.19 no.5
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• pp.685-703
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• 2017

Recently, as the number of high-rise building and earthquake occurrence are increasing, it is more important to consider horizontal load such as wind and seismic loads, earth pressure, for the pile foundation. Also, development of underground space in urban areas is more demanded to meet various problem induced by growing population. Many studies on pile subjected to horizontal load have been conducted by many researchers. However, research regarding interactive behavior on pile subjected to horizontal load with tunnel are rare, so far. In this study, therefore, study on the behaviors of ground and horizontal and vertical loads applied to single pile was carried out using laboratory model test and numerical analysis. The pile axial force and ground deformation were investigated according to offset between pile and tunnel (0.0D, 1.0D, 2.0D: D = tunnel diameter). At the same time, close range photogrammetry was used to measure displacement of underground due to tunnelling during laboratory model test. The results from numerical analysis were compared to that from laboratory model test.

• Korean Chemical Engineering Research
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• v.48 no.2
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• pp.224-231
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• 2010

In GvdW EOS, a recently presented paper, shows that the characteristic status for spherical non-linear particle, of which the mutual behavior is known to be vdWf(van der Waals force) only, could be described well enough in the critical region. However, in current papers, analysis has not been done on GvdW about whether it is accurate or not, even for the particles in the linear form or those with the additional mutual behavior such as static-electricity, so there's some argument about the wide use of that. Therefore, in this paper, for the simulation in the critical region of Normal-alkane group(R=methane, ethane, propane, butane) which are the particles that has a linear charateristic and Normal-amine group($RNH_2$, R=methyl-, ethyl-, propyl-amine) where static-electricity is extremely shown, GvdW parameter values about these particles are defined, and based on this simulation, we compared results to the current EOS presented recently, and analyzed them. Through the simulation, it was shown that in case of Normal-alkane group and Normal-amine group molecules, GvdW presents an accurate critical region characteristic which is far more close to the measurement compared to current EOSs. Especially for butane with big amount in molecules, we found out that only GvdW EOS can reach close enough to the critical point.

• Journal of Institute of Control, Robotics and Systems
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• v.22 no.9
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• pp.705-709
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• 2016

Micro-electro-mechanical systems (MEMS) gyroscopes are widely used in various robot applications. However, these conventional gyroscopes need to vibrate the proof mass using a built-in actuator at a fixed resonance frequency to sense the Coriolis force. When a robot is not moving, the meaningless vibration of the gyroscope wastes power. In addition, this continuous vibration makes the sensor vulnerable to external sound waves with a frequency close to the proof-mass resonance frequency. In this paper, a feasibility study of a new type of gyroscope inspired by insect halteres is presented. In dipterous insects, halteres are a biological gyroscope that measures the Coriolis force. Wing muscles and halteres are mechanically linked, and the halteres oscillate simultaneously with wing beats. The vibrating haltere experiences the Coriolis force if the insect is going through a rotational motion. Inspired by this haltere structure, a gyroscope using a thin mast integrated with a robot actuation mechanism is proposed. The mast vibrates only when the robot is moving without requiring a separate actuator. The Coriolis force of the mast can be measured with an accelerometer installed at the tip of the mast. However, the signal from the accelerometer has multiple frequency components and also can be highly corrupted with noise, such that raw data are not meaningful. This paper also presents a suitable signal processing technique using the amplitude modulation method. The feasibility of the proposed haltere-inspired gyroscope is also experimentally evaluated.

• Korean Security Journal
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• no.24
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• pp.125-146
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• 2010

The G20 summit is the premier forum for international economic cooperation and it will be held in Seoul in November 2010. However, protests are expected during the Seoul summit, as a part of the deepening global war against capitalism. The Korean Police need to deal with these protests effectively in order to provide security to the participating leaders and make the meeting run on wheel as planned. The current study attempts to analyze the death of Ian Tomlinson who died in the context of a heavily policed protest during 2009 G20 London summit. There are number of unique features regarding this incident, such as the public scrutiny of police conduct through video footage, the police use of excessive force, and the process to hold the police to account for misconduct. This incident caused serious damages to the public's faith in the British police. Based on the analysis, this study found that during the G20 London summit British police had the problems such as the lack of the clear standards on the use of force, improper training in the use of force, poor communications with the media and protesters, inappropriate use of the close containment tactic, and the failure to display police identification. Therefore, this study suggests the inducement of peaceful protests, the adoption of a set of standards on the use of force, public order training that is more directed and more relevant to the public order challenges facing the Korean police, improvement of the communication with the media and protesters, enhancement of individual officer's accountability as public order policing strategies for G20 Seoul summit meeting. However, the most fundamental principle is that Korean police must place a high value on tolerance and winning the consent of the public.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.29 no.1
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• pp.85-93
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• 2016

In this study, finite element analyses of masonry infilled frames using a general purpose FE program, ABAQUS, were conducted. Analysis models consisted of the bare frame, infilled frames with masonry wall thickness of 0.5B and 1.0B, respectively. The masonry walls were constructed using the concrete bricks which were generally used in Korea as infilled wall. The material properties of frames and masonry for the analysis were obtained from material tests. However, four times increased the tensile strength was used for 1.0B wall, which is seemingly due to the differences in locating the bricks. The force-displacement relation and development of crack from the FE analysis were very similar to those from the experiments. From the FEA results, contact force between the frame and masonry, distribution of shear force and bending moments in frame members were analyzed. Obtained contact stress shows a trianglur distribution, and the contact length for 0.5B speciment and 1.0B specimen were close to the value estimated using ASCE 41-06 equation and ASCE 41-13 equation, respectively. Obtained shear force and bending moment distribution seems to replicate actual behavior which originates from the contact stress and gap between the frame and masonry.

• Journal of Digital Convergence
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• v.15 no.7
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• pp.489-495
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• 2017

To prevent over supplying of workforce with radiologic technologist license, effort to create new jobs related to radioactive from medical field and radiation-related academia should be put first. For this, investigating present condition is required by close analysis of working force supply related to radiation. Therefore in this research, basic data useful for developing future radiation-related policy and plan is provided from analysis of present supplying condition of radiologic technologists in Korea. Results are as following. First, number of people qualified as radiologic technologists consistently increased; 15,639 more people took the license in 2014 compared with 2004, showing growth rate of 75.6%. Second, about 65.7%, most of workforce related to radiation engaged in medical area. Third, estimating supply and demand of radiologic technologists by time period of 5 years from 2015 to 2040, about 6,000 number of surplus work force was predicted around 2020. Fourth, satisfaction of graduates who majored in radiology was quite low for their first occupation. These results implicate necessity of systemic supplementation which can expand medical areas where radiologic technologists can work.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.36 no.2
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• pp.50-60
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• 2024

To promote the application of reliability-based design within the Korean coastal engineering community, the author conducted reliability analyses and optimized the design of a vertical-type breakwater, considering multiple limit states in the seas off of Pusan and Gunsan - two representative ports in Korea. In this process, rather than relying on design waves of a specific return period, the author intentionally avoided such constraints. Instead, the author characterized the uncertainties associated with wave force, lift force, and overturning moment - key factors significantly influencing the integrity of a vertical-type breakwater. This characterization was achieved by employing a probabilistic model derived from the frequency analysis results of long-term in-situ wave data. The limit state of the vertical-type breakwater encompassed sliding, overturning, and collapse failure, with the close interrelation between wave force, lift force, and moment described using the Nataf joint probability distribution. Simulation results indicate, as expected, that considering only sliding failure underestimates the failure probability. Furthermore, it was shown that the failure probability of vertical-type breakwaters cannot be consistently secured using design waves with a specific return period. In contrast, breakwaters optimally designed to meet the reliability index requirement of 𝛽-3.5 to 4 consistently achieve a consistent failure probability across all sea areas.

• Steel and Composite Structures
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• v.37 no.3
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• pp.273-289
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• 2020

Due to the unique construction method of modular steel buildings (MSBs) with units prefabricated fully off the site and assembled quickly on the site, the inter-module connection for easy operation and overall performance of the system were key issues. However, it was a lack of relevant research on the system-level performance of MSBs. This study investigated the seismic performance of two-storey modular steel structure with a proposed vertical rotary inter-module connection. Three full-scale quasi-static tests, with and without corrugated steel plate and its combination, were carried out to evaluate and compare their seismic behaviour. The hysteretic performance, skeleton curves, ductile performance, stiffness degradation, energy dissipation capacity, and deformation pattern were clarified. The results showed that good ductility and plastic deformation ability of such modular steel structures. Two lateral-force resistance mechanisms with different layout combinations were also discussed in detail. The corrugated steel plate could significantly improve the lateral stiffness and bearing capacity of the modular steel structure. The cooperative working mechanism of modules and inter-module connections was further analyzed. When the lateral stiffness of upper and lower modular structures was close, limited bending moment transfer may be considered for the inter-module connection. While a large lateral stiffness difference existed initially between the upper and lower structures, an obvious gap occurred at the inter-module connection, and this gap may significantly influence the bending moments transferred by the inter-module connections. Meanwhile, several design recommendations of inter-module connections were also given for the application of MSBs.

• Wind and Structures
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• v.20 no.3
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• pp.449-468
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• 2015

Current wind-resistance designs of large-scale indirect dry cooling towers (IDCTs) exclude an important factor: the influence of the ventilation rate for radiator shutter on wind loads on the outer surfaces of the tower shell. More seemingly overlooked aspects are the effects of various ventilation rates on the wind pressure distribution on the tower surfaces of two IDCTs, and the feature of the flow field around them. In order to investigate the effects of the radiator shutter ventilation rates on the aerodynamic interference between IDCTs, this paper established the numerical wind tunnel model based on the Computational Fluid Dynamic (CFD) technology, and analyzed the influences of various radiator shutter ventilation rates on the aerodynamic loads acting upon a single and two extra-large IDCTs during building, installation, and operation stages. Through the comparison with the results of physical wind tunnel test and different design codes, the results indicated that: the influence of the ventilation rate on the flow field and shape coefficients on the outer surface of a single IDCT is weak, and the curve of mean shape coefficients is close to the reference curve provided by the current design code. In a two-tower combination, the ventilation rate significantly affects the downwind surface of the front tower and the upwind surface of the back tower, and the larger positive pressure shifts down along the upwind surface of the back tower as the ventilation rate increases. The ventilation rate significantly influences the drag force coefficient of the back tower in a two-tower combination, the drag force coefficient increases with the ventilation rate and reaches the maximum in a building status of full ventilation, and the maximum drag coefficient is 11% greater than that with complete closure.

• Computational Structural Engineering
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• v.8 no.4
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• pp.149-158
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• 1995

When hot-rolled wide flanges are used as vertical compressive or bending member, opening web are often to take a space for equipments of pipe or duct. The Web of hot-rolled wide flange steel with opening may be analyzed as a rectangular plate, subjected to in plane force, and the buckling load is governed by the ultimate force of web. The result of the theory showed close agreement with the result of the finite element analysis. It was also shown that the buckling loads of stiffened opening plates could be larger than those of the plate. The stiffened opening plates for the 4-side simply supported case showed more stiffening effect than the Two Opposite Elastic Supports and Two Other Opposite Simply Supports case. In this study, we proposed the effective opening sizes that buckling loads of stiffened opening plate could be greater than those of the plates.