• Smart Media Journal
• /
• v.4 no.4
• /
• pp.9-17
• /
• 2015

Recently the need for advanced security technologies are increasing as the occurrence of intelligent crime is growing fastly. Previous liveness detection and fake face detection methods are required for the improvement of accuracy in order to be put to practical use. In this paper, we propose a new liveness detection method using pupil reflection, and new fake image detection using Adaboost detector. The proposed system detects eyes based on multi-scale Gabor feature vector in the first stage, The template matching plays a role in determining the allowed eye area. And then, the reflected image in the pupil is used to decide whether or not the captured image is live or not. Experimental results indicate that the proposed method is superior to the previous methods in the detection accuracy of fake images.

• Proceedings of the Korean Geotechical Society Conference
• /
• 2009.03a
• /
• pp.444-455
• /
• 2009

Great concerns on geotechnical risk & hazard assessment have been increased due to human and economic damage by natural disasters with recent global climate changes. In this paper, geotechnical problems in particular, landslides which is interested in European countries and North America, were mainly discussed. For these, 18 key topics on geotechnical risk and hazards which had been discussed at the LARAM 2008 workshop in Italy were analyzed after grouping by subjects. Main topic contents consisted of applications such as field measurement, early warning systems, uncertainty analysis of parameters using radar, optical data and statistical theory and so on. And the problems related to analysis of vulnerability and deformation due to earthquakes, investigation of gas zone using seismic reflection data in a landslide area, risk quantification and hazard assessment of landslide movements and multi-dimensional analysis for stability of complex slopes were attracted. Also, there were studies on risk matters of cultural heritage, the blockglide of clayey ground, simulations of debris flows based on GIS, quantification of the failure processes of rock slopes, a meshless method for 3D crack modelling, and finally risk assessment for cryological processes due to global warming.

• Journal of the Society of Naval Architects of Korea
• /
• v.32 no.2
• /
• pp.84-92
• /
• 1995

To understand how low-frequency sound waves propagate axially in drilling boreholes, the propagation modes and speeds including the effect of interaction among layers are obtained by analyzing an infinitely-long, uniform, and cylindrically multi-layered waveguide which is consisted of fluid layers and solid layers. Assuming low frequency(wave length considered is very long compared to the borehole diameter), axisymmetry, non-viscosity, and etc., analytical solutions are obtained. Also, sound reflection due to the changes in the cross section is analyzed. Results for typical drilling boreholes show the usefulness of the method developed in this research, and are compared with FEM results showing good agreements.

• Geophysics and Geophysical Exploration
• /
• v.7 no.1
• /
• pp.70-79
• /
• 2004

We have examined the applicability of the triaxial drill-bit VSP method (TAD-VSP) to the geological survey of possible sites for a high-level radioactive waste disposal repository. The seismic energy generated by a drill bit is measured by a downhole multi-component detector, and the resulting signals are processed to image the geological structure deep underground. In order to apply the TAD-VSP method to civil-engineering-scale drilling, we have developed a small but highly sensitive and precise three-component downhole seismic measurement system, and recorded drill-bit signals at a granite quarry. We have successfully imaged discontinuities in the granite, possibly related to fractures, as highly reflective zones. The discontinuities imaged by the TAD-VSP method correlate well with the results of other borehole observations. In conclusion, the TAD-VSP method is usable in geological investigations for civil engineering because the equipment is compact and it is simple to acquire the drill-bit signal.

• Journal of Welding and Joining
• /
• v.35 no.2
• /
• pp.13-22
• /
• 2017

In laser full penetration welding process, full penetration hole(FPH) is formed as a result of force balance between the vapor pressure and the surface tension of the surrounding molten metal. In this work, a three-dimensional numerical model based on a conserved-mass level-set method is developed to simulate the transport phenomena during laser full penetration welding process, including full penetration keyhole dynamics. Ray trancing model is applied to simulate multi-reflection phenomena in the keyhole wall. The ghost fluid method and continuum method are used to deal with liquid/vapor interface and solid/liquid interface. The effects of processing parameters including laser power and scanning speed on the resultant full penetration hole diameter, laser energy distribution and energy absorption efficiency are studied. The model is validated against experimental results. The diameter of full penetration hole calculated by the simulation model agrees well with the coaxial images captured during laser welding of thin stainless steel plates. Numerical simulation results show that increase of laser power and decrease of welding speed can enlarge the full penetration hole, which decreases laser energy efficiency.

• Journal of the Korean Geophysical Society
• /
• v.6 no.1
• /
• pp.31-38
• /
• 2003

Multi-channel seismic survey, which has been mainly employed in oil prospecting, is carried out as a high resolution shallow marine seismic exploration. Fault drop as small as 1 m can be resolved by employing high-resolution seismic survey. Similar to the effect of shallow inhomogenities in the land seismic data, due to occurrence of swell quite often higher than 1 m, shallow marine seismic data tend to be severely degraded. Suppression of such a swell effect is critical in processing of steps of marine seismic shallow high-resolution data. Compared to the moving average depth method, a newly developed method using cross-correlation technique is found out to be very effective in increasing the resolution of the shallow reflection events by accuratly elucidating the depth of sea bottom.

• Journal of Korean Elementary Science Education
• /
• v.27 no.2
• /
• pp.102-116
• /
• 2008

In their teaching practice, teachers encounter multi-dimensions of pedagogical challenges. The recognition and reflection on these challenges is crucial to advance our science teaching. This study looked into science teachers' dilemmas of their teaching practical work through their written cases. Dilemma cases are teachers' narratives organized around important events of teaching and learning. It can reveal teachers' situated cognition and be used as lens to investigate complex realities of science teaching and learning. 26 pre- and in-service elementary teachers' dilemma cases of science practical work were carefully collected and analysed to interpret what constitute tensions in elementary science practical works. They were largely grouped into three: Curriculum and Institutional Relevance, Students Relevance, Nature of School Experiments Relevance and divided into 7 subheadings: 'Authority of Curriculum(textbook)', 'Disappointment at external support', 'Students' interests and safety', 'Students' unscientific and inert attitude', 'Difficulty of showing expected results', 'Generalization through experiment', 'Knowledge acquisition and authentic inquiry'. Each dilemma was interpreted in terms of the tensions which constitute contradictory beliefs, values, expectation and realities. These dilemmas enabled to expose actual conditions of elementary science practical work and teachers' challenges otherwise can not be seen easily. Science teacher educators also can get some implications to overcome the gap between theory and practice in their teacher education.

• Korean Institute of Interior Design Journal
• /
• v.15 no.6 s.59
• /
• pp.247-254
• /
• 2006

Apparently light does exist even if it does not have certain form that an object might have. The history of architecture can be told as the history of light. As various master architects as well as scholars mentioned, light has been recognized as one of the most important aspects in perceiving space. Although there are complex multi dimensions in body sense and perception, experiencing space through light is preliminary formed by the outline to the degree of brightness. Light gives space specific and unique character by limiting or enlarging the space by wrapping an object or by reflection of material surfaces or by the intensity of light itself. It is fundamentally important to recognize the essential relationship between light and perception of space through various medias such as material, form, movement and so on. Three types of space perception and cognition by light that have been categorized after studying the most significant writings on light become the core method to further analyze the selected case projects. In this research, we will study how interior space is expressed through different light conditions with above mentioned characteristics and how such expressions can be applicable to the design of interior space.

• Structural Engineering and Mechanics
• /
• v.38 no.5
• /
• pp.633-649
• /
• 2011

The paper presents a study aimed at understanding some characteristics of an interior explosion within a room with limited or no venting. The explosion may occur in ammunition storage or result from a terrorist action or from a warhead that had penetrated into this room. The study includes numerical simulations of the problem and analytical derivations. Different types of analysis (1-D, 2-D and 3-D analysis) were performed for a room with rigid walls and the results were analyzed. For the 3D problem the effect of the charge size and its location within the room was investigated and a new insight regarding the pressure distribution on the interior wall as function of these parameters has been gained. The numerical analyses were carried out using the Eulerian multi-material approach. Further, an approximate analytical formula to predict the residual internal pressure was developed. The formula is based on the conservation law of total energy and its implementation yields very good agreement with the results obtained numerically using the complete statement of the problem for a wide range of explosive weights and room sizes that is expressed through a non-dimensional parameter. This new formula is superior to existing literature recommendations and compares considerably better with the above numerical results.

• Korean Institute of Interior Design Journal
• /
• v.26 no.1
• /
• pp.63-74
• /
• 2017

This study is for the characteristic of expression of exhibition presentation in 'The Korean peninsula' which is the Golden Lion Winner at the Venice Biennale in 2014. The Korean peninsula provides two opposite political and economic systems and adaptations of modernism through various multi media images. The curator, Minsuk Cho, presented cinema montage image of Collision for analyzing dynamic exhibition organization and provides the foundation of his theory from Bergson's image and duration to Deleuze's movement-image and time-image which is mentioned from Deleuze's book "cinema 1" and "cinema 2". Furthermore, the Korean peninsula has showed perception-image and affection-image from Eisenstein & Vertov's cinemathology and systemized exhibition presentation. The montage of Collision has maximized the movement from the variety and complexity in a collision and it made difference between information images which are space, time, emotion, intelligence, the tumult between subjectivity and objectivity, fragments from reorganizing itself, and distribution and art images. The limit of montage of Collision's dialectic is not only visual but also space from organic organization but the Korean peninsula overcomes its limit and shows leap of tactile perception and time-reflection from the montage of Collision's dialectic. Therefore, the exhibition of the Korean peninsula presents the conviction of adaptations of modernism.