• Proceedings of the Korean Geotechical Society Conference
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• 2008.10a
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• pp.708-712
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• 2008

Piles and pile foundations have been in common use since very early times. Usually function of piles is to carry load to a depth at which adequate support is available. Another important use of piles is to furnish lateral support and nowadays it is getting highlighted due to the wind load, lateral action of earthquake, and so on. After Broms (1964), many researchers have been suggested methods for estimating lateral capacity of pile. But each method assumes different earth pressure distribution and lateral earth pressure coefficient and it gives confusion to pile designers. Lateral earth pressure, essential in lateral capacity estimation, influenced by pile's behavior under lateral load. Prasad and Chari (1999) assumed the rotation point of pile and suggested an equation of ultimate lateral load capacity. In this study, we investigate the depth of rotation point in both homogeneous soil and multi layered soil, and compare to the estimation value by previous research. To model the pile set up in the sand, we use the chamber and small scale steel pile, and rain drop method. Test results show the rotation point is formed where the Prasad and Chari's estimation value, and they also show multi layered condition affects to location of rotation point to be scattered.

• Journal of the Korean Geotechnical Society
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• v.30 no.3
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• pp.17-28
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• 2014

In this study, the seepage behavior has been analyzed, which is the most important in determining the stability of the embankment. Large-scale embankment of weathered granite has been installed and TDR (time domain reflectory) sensors were used to detect the seepage lines. The TDR graphs could be separated into 3 sections, which are initial, unsaturated and saturated zones. TDR sensor can detect seepage line more easily than point sensor without analysis. Comparisons of the results of numerical analyses and the TDR sensors showed differences at water level rising condition, and then Comparisons of the results generally showed good agreement at another condition.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.20 no.2
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• pp.385-393
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• 2016

This paper presents the new position estimation method which contains the optical displacement sensor and the dead reckoning based position estimation algorithm for automation of hull cleaning robot. To evaluate feasibility of the proposed position estimation method on the hull cleaning robot, it was applied on the small scale robot model which has an identical drive method with the hull cleaning robot and then a set of the position estimation experiments were performed. The experimental results of the position estimation demonstrate that the estimated results with the optical displacement sensors is more accurate than used rotary encoder method. In addition, it continuously calculated the robot position quite close to the real robot driving path. In a follow-up study, the proposed position estimation method will be complemented and exploited on the actual hull cleaning robot by adding additional sensor modules that correct measurement errors.

• The Transactions of the Korean Institute of Power Electronics
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• v.15 no.6
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• pp.451-459
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• 2010

This paper describes the performance comparison results for a hybrid back-to-back converter, which is composed of a 3-level 24-pulse converter and a 3-level PWM converter, in order to interconnect a large scale wind farm with the power grid. Also it describes the performance comparison results when the 24-pulse converter operates in only firing-angle control, and both firing-angle and the zero-voltage control. For the purpose of systematic performance comparison, computer simulations with PSCAD/EMTDC software were carried out, and based on simulation results a scaled hardware model with 2 kVA rating was built and tested.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.37 no.4C
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• pp.307-312
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• 2012

In this paper, we perform a complexity analysis for implementation of the ISO/IEEE 11073 Personal Health Device (PHD) standards in order to check the required system resources when ISO/IEEE 11073 PHD standards are implemented on the embedded system. Base on the implemented programs complying the PHD standards for a weighing scale, a blood pressure monitor, and a glucose meter among the various personal health devices, we make a pseudo-code. And then from the two different points of view such as program memory space and data memory space, we make a complexity analysis model. Because system resources or capability are strongly restricted in the personal health devices, our research work is very useful to estimate the required system resources.

• Korean Journal of Construction Engineering and Management
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• v.14 no.2
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• pp.150-159
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• 2013

The government has focused on activation of overseas construction projects and strengthening competitiveness in the long term. In recent years Public construction contract as well as design, engineering, construction management(CM) are gradually expanding into other countries, but risk analysis cases in the field are slight. In this study, We utilized PI scale and drew a conclusion about the importance of overseas risk by participants. We compared its features from the risk factor based on Risk Matrix. As a result of this study total of 6 section 31 Country Risk factors for the importance of overseas risk by participants were drawn, and the key risk factors (17 constructor, 14 designers, 17 CMr) based on Risk Matrix were derived. By utilizing the result of this study will be used as the basic data for establishing risk management strategy to meet each business and planning evaluation model.

• Korean Chemical Engineering Research
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• v.46 no.4
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• pp.647-659
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• 2008

Colloids are a heterogeneous system in which particles of a few nanometers to hundreds micrometers in size are finely dispersed in liquid medium, but show homogeneous properties in macroscopic scale. They have attracted much attention not only as model systems of natural atomic and molecular self-assembled structures but also as novel structural materials of practical applications in a wide range of areas. In particular, recent advances in colloidal science have focused on nano-bio materials and devices which are essential for drug discovery and delivery, diagnostics and biomedical applications. In this review, first we introduce nano-bio colloidal systems and surface modification of colloidal particles which creates various functional groups. Then, various methods of fabrication of colloidal particles using holographic lithography, microfluidics and virus templates are discussed in detail. Finally, various applications of colloids in metal inks, three-dimensional photonic crystals and two-dimensional nanopatterns are also reviewed as representative potential applications.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.29 no.4
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• pp.301-308
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• 2016

In this study, a novel method referred as non-marker vision-based displacement measuring system(NVDMS) was introduced in order to measure the displacement of structure. There are two distinct differences between proposed NVDMS and existing vision-based displacement measuring system(VDMS). First, the NVDMS extracts the pixel coordinates of the structure using a feature point not a marker. Second, in the NVDMS, the scaling factor in order to convert the coordinates of a feature points from pixel value to physical value can be calculated by using the external conditions between the camera and the structure, which are distance, angle, and focal length, while the scaling factor for VDMS can be calculated by using the geometry of marker. The free vibration test using the three-stories scale model was conducted in order to analyze the reliability of the displacement data obtained from the NVDMS by comparing the reference data obtained from laser displacement sensor(LDS), and the measurement of dynamic characteristics was proceed using the displacement data. The NVDMS can accurately measure the dynamic displacement of the structure without the marker, and the high reliability of the dynamic characteristics obtained from the NVDMS are secured.

• Management & Information Systems Review
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• v.31 no.3
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• pp.97-116
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• 2012

This pager purposed to investigate the style of career anchor and influence of career satisfaction and career commitment. also to concept each variable. The empirical research questions for the study are what kind of the career anchor is selected and what impacts on career satisfaction and career commitment. To examine the model, 299 questionnaires was collected from Korean workers. Each questions is based on a 7 point Likert-type scale, and the data were analyzed by SPSS and AMOS for Windows. The results of study are summarized as follows: First, style of career anchor(technical/functional, security, pure challenge, life-style integration) has an positive influence on career satisfaction. but partial style of career anchor(managerial, creativity, autonomy/independence, service/dedication) unconnected with career satisfaction. Secondly, style of career anchor(technical/functional, managerial, security, service/dedication) has an positive influence on career commitment. but partial style of career anchor(creativity, autonomy/independence, pure challenge, life-style integration) unconnected with career satisfaction.

• Journal of Digital Convergence
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• v.11 no.11
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• pp.37-52
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• 2013

Prior to full-scale implementation of smart grid, the Korean government is conducting a smart grid testbed in Jeju island. However, the participants of the ongoing program are skeptical about the success of the expansion of smart grid. The concern rises from various reasons; the limits of the Korean electricity market mainly led by both the government and KEPCO, high stability and reliability of the existing electricity grid, insufficient utilization of renewable energy, and public fear of raised electricity bills. Five key issues in regards to facilitating the Korean smart grid market are extracted and evaluated. The issues are conflict of interest among participants, the effect of introducing real-time pricing, lack of customer participation of demand response, and absence of business models.