• The korean journal of orthodontics
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• v.47 no.4
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• pp.268-274
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• 2017

The purpose of this article is to introduce a simple appliance that uses a setup model and a nickel-titanium (Ni-Ti) wire for correcting the mesial rotation and drift of the permanent maxillary first molar. The technique involves bonding a Ni-Ti wire to the proper position of the target tooth on a setup model, followed by the fabrication of the transfer cap for indirect bonding and its transfer to the patient's teeth. This appliance causes less discomfort and provides better oral hygiene for the patients than do conventional appliances such as the bracket, pendulum, and distal jet. The treatment time is also shorter with the new appliance than with full-fixed appliances. Moreover, the applicability of the new appliance can be expanded to many cases by using screws or splinting with adjacent teeth to improve anchorage.

• International Journal of Concrete Structures and Materials
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• v.9 no.4
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• pp.439-451
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• 2015

This study analyzed the isolation effect for a 15-story reinforced concrete (RC) building with regard to changes in the beam-column stiffness ratio and the difference in the vibration period between the superstructure and an isolation layer in order to provide basic data that are needed to devise a framework for the design of isolated RC buildings. First, this analytical study proposes to design RC building frames by securing an isolation period that is at least 2.5 times longer than the natural vibration period of a superstructure and configuring a target isolation period that is 3.0 s or longer. To verify the proposed plan, shaking table tests were conducted on a scaled-down model of 15-story RC building installed with laminated rubber bearings. The experimental results indicate that the tested isolated structure, which complied with the proposed conditions, exhibited an almost constant response distribution, verifying that the behavior of the structure improved in terms of usability. The RC building's response to inter-story drift (which causes structural damage) was reduced by about one-third that of a non-isolated structure, thereby confirming that the safety of such a superstructure can be achieved through the building's improved seismic performance.

• Journal of the Korean Society of Marine Environment & Safety
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• v.5 no.1
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• pp.29-36
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• 1999

A field experiment of the leeway of person-in-water(man with wetsuit) was conducted during October 1997∼ April 1998. The experiment area was northeast side of Cho Do island in Pusan. The college students whose weight ranges 60∼87 kg, height 170∼178 cm were actually drifted for the experiment. The person-in-water wore 5 mm neoprene diving wetsuit to prevent heat loss of the body. The current near the target was measured using a colored vinyl bag. To compare the result a scuba diver equipped with scuba gear and with his BC(buoyancy compensator) fully inflated was drifted alongside. The average leeway speed of man with wetsuit and that of scuba diver were about 0.4 percent and 1.3% of the 10 m wind speed above the water respectively.

• Earthquakes and Structures
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• v.8 no.6
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• pp.1277-1297
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• 2015

Post-tensioned precast segmental bridge columns have shown high level of strength and ductility, and low residual displacement, which makes them suffer minor damage after earthquake loading; however, there is still lack of confidence on their lateral response against severe seismic loading due in part to their low energy dissipation capacity. This study investigates the influence of major design factors such as post-tensioning force level, strands position, columns aspect ratio, steel jacket and mild steel ratio on seismic performance of self-centring segmental bridge columns in terms of lateral strength, residual displacement and lateral peak displacement. Seismic analyses show that increasing the continuous mild steel ratio improves the lateral peak displacement of the self-centring columns at different levels of post-tensioning (PT) forces. Such an increase in steel ratio reduces the residual drift in segmental columns with higher aspect ratio more considerably. Suggestions are proposed for the design of self-centring segmental columns with various aspect ratios at different target drifts.

• Earthquakes and Structures
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• v.7 no.1
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• pp.101-117
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• 2014

This paper presents a reliability-based analysis on seismic performance of timber-steel hybrid shear wall systems. Such system is composed of steel moment resisting frame and infill wood frame shear wall. The performance criteria of the hybrid system with respect to different seismic hazard levels were determined through a damage assessment process, and the effectiveness of the infill wood shear walls on improving the seismic performance of the hybrid systems was evaluated. Performance curves were obtained by considering different target non-exceedance probabilities, and design charts were further established as a function of seismic weight. Wall drift responses and shear forces in wood-steel bolted connections were used as performance criteria in establishing the performance curves to illustrate the proposed design procedure. It was found that the presence of the infill wood shear walls significantly reduced the non-performance probabilities of the hybrid wall systems. This study provides performance-based seismic evaluations on the timber-steel hybrid shear walls in support of future applications of such hybrid systems in multi-story buildings.

• International journal of advanced smart convergence
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• v.4 no.2
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• pp.20-28
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• 2015

In this paper, we propose an effective tracking algorithm with an appearance model based on features extracted from a video frame with posture variation and camera view point adaptation by employing the non-adaptive random projections that preserve the structure of the image feature space of objects. The existing online tracking algorithms update models with features from recent video frames and the numerous issues remain to be addressed despite on the improvement in tracking. The data-dependent adaptive appearance models often encounter the drift problems because the online algorithms does not get the required amount of data for online learning. So, we propose an effective tracking algorithm with an appearance model based on features extracted from a video frame.

• Journal of the Korea institute for structural maintenance and inspection
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• v.10 no.3
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• pp.106-114
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• 2006

This study proposed the applicability of inverse stiffness method on the seismic design for steel frame with buckling restrained braces and the design results were compared with former research's. The concept of this method is simple and efficient. Furthermore it is able to reflect the high mode's effect and control the ductility factors of each story individually. Design results using the proposed method showed that according to increase of the given target drift, the areas of brace generally decreased but partially increased in some stories of the tall structure with very large ductility. And the post yield stiffness ratio's variation had more effect on the design results in the small post yield stiffness ratio.

• Journal of Ocean Engineering and Technology
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• v.30 no.5
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• pp.374-380
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• 2016

The large drift and angle of attack motion of an ROV (Remotely operated vehicle) cannot be modeled using the typical hydrodynamic coefficients of conventional straight running AUVs and specific slender bodies. In this paper, the ROV hull is divided into several simple-shaped components to model the hydrodynamic force and moment. The hydrodynamic force and moment acting on each component are modeled as the components of added mass force and drag using the known values for simple shapes such as a cylinder and flat plate. Since an ROV is operated under the water, the only environmental force considered is the current effect. The target ROV dealt with in this paper has six thrusters, and it is assumed that its maneuvering motion is determined using a thrust allocation algorithm. Tracking simulations are carried out on the ship’s surface near the stern, bow, and midship sections based on the modeling of the hydrodynamic force and current effect.

• Journal of the Architectural Institute of Korea Structure & Construction
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• v.34 no.1
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• pp.19-26
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• 2018

After the Gyeongju earthquake, school buildings were designated as earthquake shelters. However, the ratio of designed for seismic of domestic school buildings is only 23.2% in Korea, and it is necessary to secure the seismic safety of those. Therefore, in this paper, a target building was selected before the seismic design criteria was established and the seismic performance of the building was evaluated. After the evaluation, reinforcement of the building was carried out using seismic retrofit systems which was previously tested. For this purpose, the evaluation was carried out using OpenSees program and the reliability of the seismic retrofit systems was also verified. In this way, we can more precisely reproduce the response of the building in case of actual earthquake and predict damage of the earthquake in the future.

• Journal of the Society of Naval Architects of Korea
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• v.59 no.6
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• pp.338-344
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• 2022

Roll moment usually is ignored when analyzing the maneuverability of surface ships. However, it is well known that the influence of roll moment on maneuverability is significant for ships with small metacentric height such as container ships, passenger ships, etc. In this study, a pure roll test is performed to determine the hydrodynamic derivatives with respect to roll motion as added mass and damping. The target ship is an autonomous surface ship designed to carry containers with a small drift and large freeboard. The commercial code of STAR CCM+ software is applied as a specialized tool in naval hydrodynamic based on RANS equation for simulating the pure roll of the ship. The numerical uncertainty analysis is conducted to verify the numerical accuracy. By distinguishing the in-phase and out-of-phase from hydrodynamic forces and moments due to roll motion, added mass derivatives and damping derivatives relative to roll angular velocity are obtained.