• Journal of the Korean GEO-environmental Society
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• v.16 no.7
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• pp.35-42
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• 2015

Grouting method has been widely used for the ground improvement and stabilization: mostly to block or control the ground water in the early years and to improve the ground, repair the structure in recent years, ever increasing its use. Despite many advantages so far, the existing grouting method also has some shortcomings including uncertain permeation of grouting with gravity type if the voids between the soil particles are narrow, and problems due to the relaxation of the neighboring ground when injected using injection pressure. As an alternative, a vibration injection method with constant amplitude and frequency has been developed in recent years, with the vibration grouting being reported to have a permeability increasing effect of grout material compared with the positive pressure injection type. Accordingly, the purpose of this study is to investigate the improvement effect of the vibration grouting that applies short-period vibration energy by varying vibration cycle, vibration time and ground conditions to evaluate the strength enhancing effect of grouting materials, expansion effect of grouting body, ground improvement effect of the grouting and the penetration characteristics of the rock joint. The findings of this study show the improved compressive strength of grout, expansion of grouting body and increased penetration rate, according to the vibration compared with non-vibration under the loose soil condition.

• Journal of the Korean GEO-environmental Society
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• v.23 no.5
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• pp.33-39
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• 2022

For a slag-cement-bentonite (slag-CB) cut-off wall, GGBS replaces a part of the cement mixed to build a CB cut-off wall, which is used to block the flow and leakage of pollutants or groundwater; prevent seawater infiltration; and repair or reinforcement an aged embankments. Slag-CB cut-off walls are used in various applications in different fields where groundwater control is required due to its excellent characteristics. Such properties include high strength, low permeability, high durability and chemical resistance. However, despite these advantages, slag-CB cut-off walls are not extensively studied in Korea and thus are not applied in many cases. Particularly, GGBS, which replaces cement in a mixture, has different properties depending on its country of production. Consequently, it is necessary to perform various studies on slag-CB cut-off walls that use GGBS produced in Korea in order to increase its usability. This study has evaluated the bleeding rate, setting time, strength, and permeability in relation to the cement replacement rate of GGBS produced in Korea for slag-CB cut-off walls, with the aim to increase its usability. The evaluation found that slag-CB cut-off walls, made of a mixture containing GGBS produced in Korea, have a lower bleeding rate and permeability, and higher strengththan CB cut-off walls. It was also analyzed that such improved performance is more effective with a higher cement replacement rate of GGBS.

• Journal of Practical Engineering Education
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• v.16 no.3_spc
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• pp.391-399
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• 2024

All highway toll gates in Korea use low-speed WIM(Weight-In-Motion) to block overloaded cargo vehicles from entering the main highway, but some cargo vehicle owners are illegally modifying vehicles to operate variable axles and evading crackdowns by manipulating the axles. In previous studies detect all tires of a running vehicle were detected to determine whether there is axle manipulation. However, because the vehicle entry area at the highway toll gate checkpoint is very narrow, there is a problem that it is realistically difficult to film all tires of the entering vehicle in one video frame. In this paper, we proposed a system that can determine whether the axle is being operated through changes in the height of the vehicle's cargo box rather than by detecting tires. To detect changes in the height of a cargo box, we propose a method to extract the representative line of the cargo box using Hough transform and then measure the change in height of the representative line to detect the change in height of the cargo box. In addition, we propose a method to detect changes in the vertical height of a cargo box by accumulating motion vectors of pixels within a certain area of the image using optical flow. And the two methods were compared and their advantages and disadvantages were analyzed and presented.

• Journal of Advanced Navigation Technology
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• v.13 no.3
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• pp.459-465
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• 2009

Digital watermarking is a technique to insert a visually imperceptible information into an image so that the information can be extracted for the purposes of ownership verification or authentication. And watermarking techniques can be classified as either fragile or robust. Robust watermarks are useful for copyright and ownership assertion purposes. They cannot be easily removed and should resist common image manipulation procedures such as rotation, scaling, cropping, etc. On the other hand, fragile watermarks are easily corrupted by any image processing procedure, it can detect any change to an image as well as localizing the areas that have been changed. In this paper, we propose a fragile watermarking algorithm using a special hierarchical structure for integrity verification of image and detection of manipulated location. In the proposed method, the image to be watermarked is divided into blocks in a multi-level hierarchy and calculating block digital signatures in this hierarchy. The proposed method thwarts the cut-and-paste attack and the experimental results to demonstrate the effectiveness of the proposed method.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• 2004.04a
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• pp.443-449
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• 2004

In this paper, we established a simulation model for transport vehicle that carries the container transportation between apron and yard block on automated container terminal with a perpendicular yard layout. Usually, the efficiency of container terminal is evaluated by productivity of container cranes at apron, and though there are enough support of transport vehicles and yard cranes, can improve the productivity of container cranes. Especially, transport vehicle is very important factor in productivity of container cranes and has variable work productivity according to loading and unloading situation of container cranes. Therefore, a method that can estimate work productivity of transport vehicle efficiently is required. We analyzed work productivity of transport vehicle using simulation model that has state transition of transport vehicle. We performed various simulation experiment and analyzed work productivity of transport vehicle and calculated the required number of transport vehicle by container crane additionally.

• Journal of the Korean housing association
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• v.20 no.4
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• pp.79-88
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• 2009

A planned access method on constantly-changing-community unit plan changes and develops based on the periodical situation and also plan theory. In this research, it is to present the link between the theory of complex city change and the plan factor of it, and to show how Korean residential complex plan has changed as time passed and how new concept of city plan came up and by applying new methods how can this affect our real world and the past plan. In the phase of analysis, it analyzed the flow of 'community unit plan' and its theory and investigated the factor of compositional space and built a analysis frame. The factors of community unit plan are space structure, size and shape of block, population, distribution of facilities and movement system. It chose the place that can represent the flow of community unit plan trand and that indicates the obvious development leading to Jamsil (1975), Gwa Chun (1980), Mok Dong (1983), Sang Ge (1985), Ilsan (1989), Dong tan (2001) and Eun Jung (2003) total of 7 places. And to compare a similar size of the city, it selected a small community unit. Based on the result of theoretical study and prior research, it can be said that the space composition style has change from a whole complete complex area to a linked-cross over community unit and the access of urban level was on set. Also, a pedestrian walking area was secured and the dense of building structure and pleasant environment wanting need was in balance. For facility plans, the usage of facility and functional change brought change of type, size and disposition. The walking area for pedestrian became a huge matter. Therefore, market, education, public facilities and green system collaborated to co-build a whole community unit and activated the walking environment. Also, public transportation, environment friendly city organization was built.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.11 no.1
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• pp.67-72
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• 2010

In this paper, we verify the driverless operation possibility of MBS, which could overcome the defects of conventional track-circuit-based FBS, such as additional needs of maintenance and others problems according to short-circuit sensibility and, and which could allow the minimal interval between trains. With MBS, we can expect the reduction of headway, then the increase of transportation demand, and the protection of unnecessary speed variation because it allows the real time detection of train position from central office, and direct transmission of data between preceding trains and the following ones. In addition, it is possible to reduce the number of wayside-equipment substantially, to improve the passenger service, and to the achieve the positive economic effects by comfortable ride.

• Proceedings of the KOR-KST Conference
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• 2007.05a
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• pp.399-408
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• 2007

Dedicated Short Range Communications(DSRC) is a block of spectrum in the 5.8GHz band. DSRC is the useful technology of ITS Service. Japan operates ETCS, VICS by DSRC technology and DSRC technology is used ETCS Standard in Korea. There are many kind of utilization of DSRC in ITS. This is a study for traffic information service and collection with DSRC. Traffic management server service traffic information to driving vehicle by RSE(Road Side Equipment). OBU(Onboard Unit) in vehicle send the information to PDA(Personal Digital Assistant). Client S/W show the information to driver by text, pictogram, sound and return PDA H/W ID to OBU. Server make section traffic information by the PDA H/W ID information.

• Restorative Dentistry and Endodontics
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• v.28 no.1
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• pp.41-49
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• 2003

There are increasing usage of Nickel-Titanium rotary files in modern clinical endodontic treatment because it is effective and faster than hand filing due to reduced step. This study was conducted to evaluate the effect of canal preparations using 3 different rotary Nickel-Titanium files that has different cross sectional shape and taper on the maintenance of canal curvature. Simulated resin block were instrumented with Profile(Dentsply, USA), GT rotary files(Dentsply, USA), Hero 642(Micro-Mega France), and Pro-Taper(Dentsply, USA). The image of Pre-instrumentation and Post-instrumentation were acquired using digital camera and overspreaded in the computer. Then the total differences of canal diameter, deviation at the outer portion of curvature, deviation at the inner portion of curvature, movement of center of the canal and the centering ratio at the pre-determined level from the apex were measured. Results were statistically analyzed by means of ANOVA, followed by Scheffe test at a significance level of 0.05. The results were as follows； 1. Deviation at the outer portion of curvature, deviation at the inner portion of curvature were showed largest in Pro-Taper so also did in the total differences of canal diameter(p＜0.05). 2. All the groups showed movements of center Profile combined with GT rotary files and Hero 642 has no difference but Pro-Taper showed the most deviation(p＜0.05). 3. At the 1, 2, 3mm level from the apex movements of center directed toward the outer portion of curvature, but in 4, 5 mm level directed toward the inner portion of curvature(p＜0.05). As a results of this study, it could be concluded that combined use of other Nickel-Titanium rotary files is strongly recommended when use Pro-Taper file because it could be remove too much canal structure and also made more deviation of canal curvature than others.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.7 no.8
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• pp.1933-1954
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• 2013

Multiple wireless devices are being widely deployed in Intelligent Transportation System (ITS) services on the road to establish end-to-end connection between vehicle-to-vehicle (V2V) and vehicle-to-infrastructure (V2I) networks. Vehicular ad hoc networks (VANETs) play an important role in supporting V2V and V2I communications (also called V2X communications) in a variety of urban environments with distinct topological characteristics. In fact, obstacles such as big buildings, moving vehicles, trees, advertisement boards, traffic lights, etc. may block the radio signals in V2X communications. Their impact has been neglected in VANET research. In this paper, we present a realistic and efficient radio propagation model to handle different sizes of static and moving obstacles for V2X communications. In the proposed model, buildings and large moving vehicles are modeled as static and moving obstacles, and taken into account their impact on the packet reception rate, Line-of-sight (LOS) obstruction, and received signal power. We use unsymmetrical city map which has many dead-end roads and open faces. Each dead-end road and open faces are joined to the nearest edge making a polygon to model realistic obstacles. The simulation results of proposed model demonstrates better performance compared to some existing models, that shows proposed model can reflect more realistic simulation environments.