• Geophysics and Geophysical Exploration
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• v.23 no.3
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• pp.178-191
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• 2020

Unmanned aerial vehicle (UAV) technologies have grown rapidly over the past decade. Simultaneously, there is an increasing need for efficient high-resolution exploration techniques in complex environments. As a result, exploration technology using UAVs is gaining attention as an efficient method to complement and replace existing exploration technologies. In particular, magnetic exploration technology with UAVs is rapidly gaining ground in the field of exploration and is expected to be actively used in this field in the future. To properly use such technology in domestic exploration, it is necessary to review the latest research trends. Accordingly, this paper introduces the current state of UAV-based magnetic exploration technology studies and, based on this, discusses future research directions.

• Journal of the Korean Society of Propulsion Engineers
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• v.19 no.1
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• pp.42-49
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• 2015

The pressure oscillation induced by inhibitor in a solid rocket motor has been investigated by 3D large eddy simulation(LES) and proper orthogonal decomposition(POD). The vortex generation and breakdown at inhibitor are periodically observed between the inhibitor and the nozzle by flow-acoustic coupling mechanism. The excitation of pressure oscillation occurs as the flow impinges on the submerged nozzle head which recirculate in the cavity in rear dome of the motor chamber. The vortex generation frequency is closely related with the shedding frequencies of the detached vorticities at the inhibiter, which fairly compared with the experimental data.

• The Mathematical Education
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• v.52 no.3
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• pp.271-301
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• 2013

The purpose of the study was to investigate how students generalize and prove the factoring of $x^n-1$ using a Computer Algebra System application and the role of CAS in this process. The theoretical framework consists of the anthropological and the instrumental approach. In particular, the basis of the Task-Technique-Theorization(T-T-T) frame adapted form Chevallard's anthropological approach of Didactics is utilized. We found that Technique-Theorization emerges in mutual interaction between paper-and-pencil techniques and computer algebra techniques. And this interaction led to the students' theoretical reflection and conceptual understanding. In this process, we could identify three epistemic role of CAS : the role of checking the result, the role of cognitive stimulation and the role of extending thinking. Therefore CAS plays on a epistemic role of checking the result of a task, stimulating the student' cognition and extending their thinking as well as pragmatic role of producing the result of a input.

• Journal of the Korean Society of Visualization
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• v.6 no.2
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• pp.14-19
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• 2008

In this paper, the recirculation flow motion and mixing characteristics driven by air bubble flow in a rectangular water tank is studied. The Time-resolved PIV technique is adopted for the quantitative visualization and analysis. 532 nm Diode CW laser is used for illumination and orange fluorescent particle images are acquired by a PCO 10bit high-speed camera. To obtain clean particle images, 545 nm long pass optical filter and an image intensifier are employed and the flow rates of compressed air is changed from 2 l/min to 4 l/min at 0.5 MPa. The recirculation and mixing flow field is further investigated by the POD analysis technique. It is observed that the large scale counterclockwise rotation and main vortex is generated in the upper half depth from the free surface and one quarter width from the sidewall. When the flow rates are increased, the main vortex core is moved to the side and bottom wall direction.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.49 no.2
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• pp.32-38
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• 2012

In this paper, we design on nonliner 3 user Dirty Paper Precoding for MIMO adjacant interference signal cancellation based on 3 GPP LTE Release 10. In this paper, in order to reduce the inter-channel interference at the transmitted side, we propose the Dirty Paper Precoding scheme for 3-user MIMO wireless systems using LQ decomposition and Gram-Schmidt algorithm based in its orthonormal basis.

• Polymer(Korea)
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• v.30 no.1
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• pp.1-9
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• 2006

The development of functional polymeric materials for biomedical application has progressed on the basis of functionality, biocompatibility and biodegradability. In this paper we review the functional polymeric biomaterialsbased systems and propose a range of biomedical applications in the near future. These systems include the functional biodegradable polymers synthesized in our research laboratory, biodegradable polymeric materials, thermosensitive polymeric materials, cationic polymeric materials, non-condensing polymeric biomaterials, bio-polymeric DNA matrix for tissue engineering, and polymeric biomaterials for RNA interference (RNAi) technology.

• KIPS Transactions on Software and Data Engineering
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• v.3 no.7
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• pp.271-276
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• 2014

Short message service(SMS) in a mobile communication environment is a very convenient method. However, it caused a serious side effect of generating spam messages for advertisement. Those who send spam messages distort or deform SMS sentences to avoid the messages being filtered by automatic filtering system. In order to increase the performance of spam filtering system, we need to recover the distorted sentences into normal sentences. This paper proposes a method of normalizing the various types of distorted sentence and extracting keywords through automatic word spacing and compound noun decomposition.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.36 no.8A
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• pp.741-747
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• 2011

Matrix Pencil method is one of the promising method to estimate DOA in non-stationary, multi-path coherent environment. Not only the Matrix Pencil Method offers better resolution than the conventional approach using covariance matrix, but also it is computationally very efficient. In this paper, we presented an effect of unbalanced data weighting in the formulation of the Matrix Pencil method. A new formulation has been suggested to mitigate the effect of unbalanced data weighting. Numerical simulation demonstrated that the proposed method can successfully eliminate the problem of unbalanced data weighting.

• Journal of the Korean Society for Nondestructive Testing
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• v.23 no.2
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• pp.125-132
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• 2003

This study introduces a simulation model of radar responses from subsurface voids in concrete for their frequency variations. In this model, resolution and attenuation characteristics due to frequency variations are analyzed at each material interface which has different electromagnetic property. This model aims at the selection of best frequency of radar which can analyze the thickness of voids in concrete from radar responses. It can also be applied to estimate the limitation of propagation depth of radar on subsurface voids in concrete. The computed results show the radar images obtained by using a radar signal processing technique using convolution.

• Transactions of the Korean Society of Mechanical Engineers
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• v.18 no.2
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• pp.339-350
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• 1994

This paper presents a method for automatic generation of line balanced assembly sequences based on disassemblability and proposes a method of evaluating an assembly work time using neural networks. Since a line balancing problem in flexible assembly system requires a sophisticated planning method, reasoning about line balanced assembly sequences is an important field of concern for planning assembly lay-out. For the efficient inference of line balanced assembly sequences, many works have been reported on how to evaluate an assembly work time at each work station. However, most of them have some limitations in that they use cumbersome user query or approximated assembly work time data without considering assembly conditions. To overcome such criticism, this paper proposes a new approach to mathematically verify assembly conditions based on disassemblability. Based upon the results, we present a method of evaluating assembly work time using neural networks. The proposed method provides an effective means of solving the line balancing problem and gives a design guidance of planning assembly lay-out in flexible assembly application. An example study is given to illustrate the concepts and procedure of the proposed scheme.