• The Mathematical Education
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• v.20 no.3
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• pp.23-26
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• 1982

Many interesting properties of a space curve C in E$^3$ may be investigated by means of the concept of spherical indicatrix of tangent, principal normal, or binormal, to C. The purpose of the present paper is to derive the representations of the Frenet frame field., curvature, and torsion of spherical indicatrix to C in terms of the quantities associated with C. Furthermore, several interesting properties of spherical indicatrix are found in the present paper.

• The Bulletin of The Korean Astronomical Society
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• v.37 no.1
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• pp.84.2-84.2
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• 2012

We studied the controlling parameters of flux emergence with a focus on the relation between the configuration of coronal magnetic field and the pre-emeged state of subsurface magnetic field. We performed a series of magnetohydrodynamic simulations (dynamic model) and find an interesting result on the twist of coronal magnetic field, that is, the coronal magnetic field formed via flux emergence actually contains less amount of twist (relative magnetic helicity normalized by magnetic flux) than what is expected in kinematic models for global-scale solar eruptions. Based on this result, we propose another possible mechanism for producing these global-scale solar eruptions.

• Honam Mathematical Journal
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• v.33 no.3
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• pp.381-391
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• 2011

One of the main interesting things of a matroid theory is the representability by a matroid from a matrix over some field F. The representability of uniform matroid $U_{m,n}$ over some field are studied by many authors. In this paper we construct a matrix representing $U_{3,6}$ over the field GF(4). Also we find out matrix of the affine matroid AG(2, 3) over the field GF(4).

• Journal of the Korea Institute of Information and Communication Engineering
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• v.15 no.5
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• pp.1097-1104
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• 2011

In this paper, we propose a semantic web approach for personalized book recommendation. Our approach takes advantage of the content-based recommendation and improves its disadvantage that users should input their interesting fields into all book search systems they use. Our approach provides the sharing of users' profile with their interesting fields by enabling user's interesting fields to be described over each book classification ontology of various book information providers. We also provide a middleware that manages users' profiles written in RDF and analizes similarity between user's interesting field and each concept over the book classification ontology. Our approach provide better performance than traditional keyword-based search by sharing the user's profile among book recommendation systems.

• Communications of the Korean Mathematical Society
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• v.10 no.3
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• pp.661-679
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• 1995

The concept of the structure conformal vector field C on a Sasakian manifold M is defined. The existence of such a C on M is determined by an exterior differential system in involution. In this case M is a foliate manifold and the vector field C enjoys the property to be exterior concurrent. This allows to prove some interesting properties of the Ricci tensor and Obata's theorem concerning isometries to a sphere. Different properties of the conformal Lie algebra induced by C are also discussed.

• Progress in Superconductivity and Cryogenics
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• v.18 no.2
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• pp.30-36
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• 2016

For the magnetic field analysis or design, it is important to know the behavior of the magnetic field in an interesting space. Magnetic field mapping becomes a useful tool for the study of magnetic field. In this paper, a numerical way for mapping the magnetic field within the cylindrical center volume of magnet is presented, based on the solution of the Laplace's equation in the cylindrical coordinate system. The expression of the magnetic field can be obtained by the magnetic flux density, which measured in the mapped volume. According to the form of the expression, the measurement points are arranged with the parallel cylindrical line (PCL) method. As example, the magnetic flux density generated by an electron cyclotron resonance ion source (ECRIS) magnet and a quadrupole magnet were mapped using the PCL method, respectively. The mapping results show the PCL arrangement method is feasible and convenience to map the magnetic field within a cylindrical center volume generated by the general magnet.

• Journal of the Korean Mathematical Society
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• v.44 no.1
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• pp.199-210
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• 2007

Given a field K and a finite group G, it is a very interesting problem, although very difficult, to find all Galois extensions over K whose Galois group is isomorphic to G. In this paper, we prepare a theoretical background to study this type of problem when G is the Mathieu group $M_{24}$ and K is a field of characteristic two.

• The Journal of the Acoustical Society of Korea
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• v.29 no.1E
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• pp.28-37
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• 2010

This article reviews recent developments in the emerging field of cellular-level biomedical ultrasonics with the specific focus on the mechanics of ultrasound-cell interaction. Due to the nature of the field at its relative infancy, the review poses more questions than it provides answers. Discussed are topics such as the basic structure of a biological cell, the origin of cell's elasticity, a theoretical framework for ultrasound-cell interaction, and shape deformation of cells and its measurement, Some interesting problems for future study are proposed.

• Proceedings of the Optical Society of Korea Conference
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• 1989.02a
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• pp.147-151
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• 1989

A spectral inversion scheme, based on the moment-method procudure with series-expanded field within each cell by dividing the dielectric object into a small number os rectangular cells with large area, is developed to regularize the ill-posedness inherent in inverse scattering problems. One of the interesting features on the presented scheme is that the relative dielectric constant may be obtained by averaging over each cell. This averaging is expected to play an important role in regularizing the high-frequency effect due to noise.

• Journal of the Korean Society of Laryngology, Phoniatrics and Logopedics
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• v.23 no.1
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• pp.13-17
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• 2012

An understanding of the history of laryngology is both interesting and useful for those in the field so this study attempts to uncover some of the interesting aspects of its history. The oldest reference of laryngology in the Orient is in the medical documents called the "Whangjainaekyung",(황제내경) which was written over a time period between 3000-4000 B.C., and described the laryngeal function of respiration, protection of the airway and phonation. In the West, a drawing that seems to portray a tracheostomy was found in medical tombs in the plains of Saqqara in Egypt. These drawings date from approximately 3600 B.C. A watershed in laryngology occurred when a spanish music professor named Manuel Garcia in first successfully used a mirror to inspect the larynx. Since that time, laryngology has developed relatively quickly and clinical laryngology made it possible by means of a number of favorable developments. Great advances in laryngological diagnosis and treatment has occurred since the 1970s thanks to improvements in technology leading to the introduction of an operating microscope, endoscopes and lasers. Despite our recent advances in laryngology, we still have not achieved uniformly favorable outcomes and there is much that we do not know. Our future promises continued advances in the field of laryngology such as gene therapy to improve wound healing and tissue engineering to allow the recreation of normal mucosa. In this review, I divide the history of the larynx into the past, present and future. In the last section, I described the history of laryngology in Korea briefly.