• Geophysics and Geophysical Exploration
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• v.12 no.1
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• pp.41-48
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• 2009

Natural magnetic fields are attenuated by electrically conductive water. For that reason, marine magnetotelluric surveys have collected data at long periods (1000-100 000 s). The mantle structure has been the main target of seafloor magnetotelluric measurements. To ascertain crustal structure, however, electromagnetic data at shorter periods are important, e.g. in investigations of megathrust earthquake zones, or in natural resource surveys. To investigate of the former, for example, electromagnetic data for periods of less than 1000 s are necessary. Because no suitable ocean bottom electromagnetometer (OBEM) has been available, we have developed a small OBEM and ocean bottom electrometer (OBE) system with a high sample rate, which has an arm-folding mechanism to facilitate assembly and recovering operations. For magnetic observation, we used a fluxgate sensor. Field observations were undertaken to evaluate the field performance of our instruments. All instruments were recovered and their electromagnetic data were obtained. Results of the first experiment show that our system functioned well throughout operations and observations. Results of other field experiments off Tottori support the claim that the electromagnetic data obtained using the new OBEM and OBE system are of sufficient quality for the survey target. These results suggest that this device removes all instrumental obstacles to measurement of electromagnetic fields on the seafloor.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2003.10a
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• pp.277-280
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• 2003

It was investigated that the "ㄱ" type angle product could be bended with a curvature during extrusion by extru-bending process. The bending process for the "ㄱ" type angle product can be developed by the hot metal extru-bending machine with the two punches moving in the different velocity. Because of non-symmetry of product, it is important to design the ruled surface contour of dies cavity for the welding and bending with two billets. So it is designed that the multi-hole container has two non-symmetric holes and non-symmetric contour of dies entrance. The results of the experiment show that "ㄱ" type angle product can be bended by the extrusion process and that the curvature of the product can be controlled by the velocity of punch and that the defects such as the distortion of section and the thickness change of the product and the folding and wrinkling of the product did not happen after the bending processing by the extrusion bending machine.

• Proceeding of Spring/Autumn Annual Conference of KHA
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• 2011.04a
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• pp.231-235
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• 2011

The purpose of this study was to analyze the types and characteristics of temporary small-sized housing units for single-person households. A document research method and case studies were used to analyze and classified the spatial characteristics and types of the temporary dwelling spaces since 2000. Findings of this study were as follows: temporary and simplified dwelling spaces were developed by the concept of impermanence for single-person households in modern society. In order to conform the concept of temporary dwelling for small-sized housing units of single-person households, the characteristics were divided into three aspects. 'Transporting' by wheel and rotation and vehicles, 'Transforming' by adapting, assembling disassembling, and folding unfolding, and 'Wearing Carrying' by inflatable and tented types. It attempted to resolve the concept of temporarity through the experiment so that they might apply to the space of contemporary city.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2003.05a
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• pp.359-362
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• 2003

The bending phenomenon has been known to be occurred by the different of velocity at the die exit. The difference of velocity at the die exit section can be obtained by the different velocity of billets through the multi-hole container and by the cohesion of billet inside the porthole die chamber. The bending phenomenon can be controlled by the different hole diameter. The experiments using aluminium material for the curved tube product had been done. The results of the experiment show that the curved tube product can be formed by the extru-bending process without the defects such as the distortion of section and the thickness change of the wall of tube and the folding and wrinkling. It is known that the welding and extruding of each billet has done simultaneously although the curved tube is extruded with four billets.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2003.05a
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• pp.371-374
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• 2003

The bending process for the "ㄱ" section product can be developed by the hot metal extrusion machine with the two punches moving in the different velocity. The bending phenomenon can be controlled by difference of velocity at the die exit section by the different velocity of billets through the two-hole container. The results of the experiment show that "ㄱ" section product can be bended by the extrusion process and that the curvature of the product can be controlled by the velocity of punch and that the defects such as the distortion of section and the thickness change of the product and the folding and wrinkling of the product did not happen after the bending processing by the extrusion bending machine.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.63 no.7
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• pp.940-944
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• 2014

In this research, we designed representative motion patterns that possibly occurred in sleep situation and evaluated the feasibility of the smartphone based movement recording technique. For this, we designed 7 motions such as posture change, head movement, arm movement (vertical, horizontal), leg movement and hand movement (flipping, folding). Movement was recorded by using the smartphone and the actimetry device simultaneously for comparing the feasibility of smartphone based recording. As a result of experiment, we found that the smartphone based movement recording well reflects the body movement, however, it shows the limitation in recording the small local movement such as hand motion compared with the reference actimetry device, Actiwatch.

• Journal for History of Mathematics
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• v.26 no.5_6
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• pp.345-353
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• 2013

Some teachers do not regard the computation of the sum of the angles of a triangle by using a cut-and-paste or paper-folding method as providing a proof that the sum of the angles of a triangle is equal to two right angles. Some even think that this way of working is not mathematics but more like an experiment in physics. Some see the method as no better than measurement of the angles by a protractor. The author will examine this issue in the teaching and learning of school geometry and more generally as a specific example from the perspective of HPM (History and Pedagogy of Mathematics).

• Proceedings of the Korean Society of Precision Engineering Conference
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• 1997.04a
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• pp.952-956
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• 1997

This paper describes the method that can expand the forming limit of T type forging products used in aircraft and automotive forged products. The forming limitis determined by the ratio of web thickness to rib width in T type and the reduction in height of workpiece and especially depends on the ratio of web thickness to rib width. For this method, the geometric condition that consists of triangle type was introduced and FEM simulations and model exoeriments were carried out and compared with each other. The objective of this paper is to give the method not only that sink mark and folding phenomenon are eliminated but also that the forming limit and the structural strength of rib and web is increased.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2001.10a
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• pp.204-207
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• 2001

The bending process for the circular curved tube and rectangular curved tube with fins can be developed by the hot metal extrusion machine with the multiple punches moving in the different velocity. The bending phenomenon can be controlled by the two variables. The one of them is the difference of velocity at the die exit section by the different velocity of billets through the multi-hole container. The other is the one by the different hole diameter. The results of the experiment show that the circular curved tube with fins and rectangular curved tube with pins can be formed by the extrusion process and that the curveture of the product can be controlled by the velocity of punch and diameter of container hole and that the defects such as the distortion of section and the thickness change of the wall of tube the folding and wrinkling of thin tube and fins did not happen after the bending processing by the extrusion bending machine.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2001.10a
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• pp.212-215
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• 2001

The bending process for the rectangular curved tube can be developed by the hot metal extrusion machine with the multiple punches moving in the different velocity. The bending phenomenon can be controlled by the two variables, the one of them is the difference of velocity at the die exit section by the different velocity of billets through the multi-hole container. The other is the difference by the different hole diameter. The results of the experiment show that the rectangular curved tube can be formed by the extrusion process and that the curvature of the curved product can be controlled by the velocity of punch and the diameter of container hole and that the defects such as the distortion of section and the thickness change of the wall of tube and the folding and wrinkling of thin tube did not happen after the bending processing by the extrusion bending machine.