• Journal of the Korea Academia-Industrial cooperation Society
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• v.16 no.2
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• pp.1381-1387
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• 2015

This paper proposes a sketch drawing system called m-shaper for musical shape generation. Through simple sketch drawing, users can generate musical shape configuration which can be played by a computer. One key ingredient of the process is a unique concept for the interactive musical shape generation that combines shape and sound based on the designers' manual inputs. m-shaper captures the numerical values of drawing characteristics and determines how the musical notes and shapes can be generated. Using a tablet, four sketch movements are captured such as pressure, tilt, rotation and speed. Each point of a shape corresponds to a certain musical note that represents a type of instrument, duration, pitch, and octave. The current m-shaper has been developed as a computational tool for supporting the schematic design process. Designers in m-shaper draw geometric sketches with a musical inspiration and explore possible conceptual forms. They also can control the parameters for results and transform their sketch drawing.

• Journal of Technology Innovation
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• v.2 no.1
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• pp.170-190
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• 1994

The importantce of a development of competitiveness in domestic construction industry is growing as some of domestic construction markets is scheduled to open to foreign competing firms with higher level of construction technology and management. A national level of competitiveness in domestic construction industry and firms are partially, but significantly, affected by a technology level and a characteristics of production pattern. The purpose of the study is mainly to analyze and identify a technology level, production pattern and a development stage of R&D activities of domestic construction industry and firms. Based on these findings the study draws on a concluding remarks and derives technology policy implications. Results of analysis in the study impliy that (1) competitiveness of domestic construction firms(industry) in terms of technology level is relatively weak as compare to that of advanced foreign competing firms, (2) degrees of substitution of capital for labor are seemed to be relatively high, (3) R&D (investment) activities of domestic construction firms are generally spread out in forms of import, adjustment and betterment, and (4) only a small number of big domestic construction firms are seemed to afford to R&D investment for research facilities and equipments, but not enough for higher level of R&D man-power. The study suggests that technology policy for construction industry should be based on a fundamental policy directions. For example the increase in size and heightened quality level of R&D man-power should be placed in a top priority in policy agenda. Sound and specific policy items should be developed for planning and design, and maintenace and inspection technology in order to lead domestic industry to compete with foreign firms with full strength.

• Journal of the Korean Society for Nondestructive Testing
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• v.19 no.3
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• pp.207-216
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• 1999

A phased array is a multi-element piezoelectric device whose elements are individually excited by electric pulses at programmed delay time. One of the advantages of using phased array in nondestructive evaluation (NDE) application over conventional ultrasonic transducers is their great maneuverability of ultrasonic beam. There are some parameters such as the number and the size of the piezoelectric elements and the inter-element spacing of the elements to design phased array transducer. In this study, the characteristic of ultrasonic beam for phased array transducer due to the variation of the number of elements has been simulated for ultrasonic SH-wave on the basis of Huygen's principle. Ultrasonic beam directivity and focusing due to the change of time delay of each element were discussed due to the change of the number of piezoelectric elements. It was found that ultrasonic beam was much more spreaded and hence its sound pressure was decreased as steering angle of ultrasonic beam was increased. In addition, the ability of ultrasonic bean focusing decreased gradually with the increase of focal length at the same piezoelectric elements. However, the ability of beam focusing was improved as the number of consisting elements was increased.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.14 no.7
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• pp.604-611
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• 2004

It is well known that wall impedance essentially determines how sound wave transmits from one place to another. The wall impedance is related with its dynamic properties : for example, the mass, stiffness, and damping characteristics. It is noteworthy, however, that the wall impedance is also function of spatial characteristics of two spaces that is separated by the wall. This is often referred that the wall is not locally reacting. In this paper, we have attempted to see how the acoustic characteristics of the two spaces is affected by various structure parameters such as density, applied tension, and a normalized length of the wall. Calculations are conducted for two different modally reacting boundary conditions by modal expansion method. The variation of the Helmholtz mode and the structural-dominated mode are analyzed as the structure parameters vary. The displacement distribution of the structure, pressure and active intensity of the inside and outside cavity are presented at the Helmholtz mode and the structure-dominated mode. It is shown that the frequency characteristics are governed by both structure-and fluid-dominated mode. The results exhibit that the density of the structure is the most sensitive design parameter on the frequency characteristics for the coupling system as we could imagine in the beginning. The Helmholtz mode frequency decrease as density increases. However. it increases as applied tension and an opening size increase. The bandwidth of the Helmholtz mode is mainly affected by density of the structure and its opening size.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2000.11a
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• pp.396-402
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• 2000

Porous structures of aluminum foam have been studied. The apparent foam shape, foam hight, density, pore size, shape, and their distributions in various section areas of the experimental samples have been investigated. The sample have been cast into metallic mold, using aluminum foam prepared from a precursor based on pure Al ingot mixed with various amount of 1-2wt% increasing viscosity and foam agent materials. The process provides for flexibility in design of foam structures via relatively easy control over the amount of hydrogen evolution and the drainage processes which occur during foam formation. This is facilitated by manupulating parameters such as the foaming agent, thermal histories during solidification and mix melt viscosities. The acoustical performance of the panel made with the foamed aluminum is considerably improved; its absorption coefficient shows NRC 0.6-0.8. It has been found that the Al foam is very preferable for the compactness of the thermal system.

• Journal of Ocean Engineering and Technology
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• v.30 no.5
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• pp.400-404
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• 2016

This paper presents experimental results for the vibration characteristics of the small unmanned underwater vehicle (UUV) OPKO 300, which was designed and manufactured by Daewoo ship and Marine Engineering Ltd. The autonomy of UUVs has led to an increase in their use in scientific, military, and commercial areas because their autonomy makes it possible for UUVs to be utilized instead of humans in hazardous missions such as mine countermeasure missions (MCM). Since it is impossible to use devices based on electromagnetic waves to gather information in an underwater environment, only sonar systems, which use sound waves, can be used in underwater environments, and their performance can strongly affect the autonomy of a UUV. Since a thruster system, which combines a motor and propeller in a single structure, is widely used as the propulsion system of a UUV and is mounted on the outside of a UUV’s stern, it can generate vibration, which can be transferred throughout the shell of the UUV from its stern to its bow. The transferred vibration can affect the performance of various sonar systems such as side-scan sonar or forward-looking sonar. Therefore, it is necessary to estimate the effect of the transferred vibration of the UUV on the sonar systems. Even if various numerical methods were used to analyze the vibration problem of a UUV, it would be hard to predict the vibration phenomena of a UUV at the initial design stage. In this work, an experimental study using OKPO 300 and an impact hammer was carried out to analyze the vibration feature of a small real UUV in the air. The frequency response function of the vibration based on the experimental results is presented.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2009.05a
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• pp.535-538
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• 2009

Auto Pilot is the system which move automatically the vessel through locating operation mode to automatic after entering operating course using a electronic chart or plotter. And water jet is the a propulsion system that make a power to push the vessel through spouting the accelerated water which is absolbed by the hole in the bottom of vessel. The water jet receive the effect of the depth of water lowly, it's acceletion efficiency is higher under high speed and have an advantage on vibrating and floating sound, so it's demand is increasing as new propulsion system. However, the signal systems of auto Pilot and water jet are defferant, we need the system to communicate between each system. We propose the interface system which communicate between Auto pilot and water jet efficiently in this journal.

• The Journal of the Acoustical Society of Korea
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• v.38 no.5
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• pp.494-510
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• 2019

Underwater acoustic communication channel parameters consist of impulse response, delay spreading, scattering function, coherence bandwidth, frequency selective fading, coherence time and time variant magnitude fading statistics on which communication system modem and channel coding are designed. These parameters are influenced by sound velocity profile, platform motion and sea surface roughness in given acoustical oceanography condition. In this paper, channel model based on phasor, channel simulator, measurement and analysis method of channel parameters are given in a fixed source-to-receiver system and the parameters are analyzed using shallow water experimental data. For two different source-to-receiver ranges of 300 m and 600 m, the parameters are characterized by three multipaths such as a direct, a surface reflection path with time variant scattering and a bottom reflection path. The results present a channel modelling method of a fixed source source-to-receiver system, channel parameters measurement and analysis methods and a system design and performance assessment method in shallow water.

• Physical Therapy Rehabilitation Science
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• v.3 no.1
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• pp.27-32
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• 2014

Objective: The aim of this study was to compare the radial bone strength, sitting balance ability and global self-esteem of wheelchair martial arts practitioners and healthy control participants. Design: Cross-sectional study. Methods: Nine wheelchair martial art practitioners with physical disabilities and 28 able-bodied healthy individuals participated in the study. The bone strength of the distal radius was assessed using the Sunlight Mini-Omni Ultrasound Bone Sonometer; sitting balance was quantified using the modified functional reach test (with reference to a scale marked on the wall); and the self-administered Rosenberg self-esteem (RSE) scale was used to measure the global self-esteem of the participants. The velocity of the ultrasound wave (speed of sound, m/s) traveling through the outer surface of the radial bone was measured and was then converted into a T-score and a Z-score. These ultrasound T-score and Z-score that represent bone strength; the maximum forward reaching distance in sitting (cm) that represents sitting balance; and the RSE total self-esteem score that indicates global self-esteem were used for analysis. Results: The results revealed that there were no statistically significant between-group differences for radial bone-strength, maximum forward reaching distance, or self-esteem outcomes. Conclusions: The wheelchair martial arts practitioners had similar radial bone strength, sitting balance performance and self-esteem to able-bodied healthy persons. Our results imply that wheelchair martial arts might improve bone strength, postural control and self-esteem in adult wheelchair users. This new sport-wheelchair martial arts-might be an exercise option for people with physical disabilities.

• Journal of Internet Computing and Services
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• v.22 no.4
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• pp.29-49
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• 2021

This paper proposes the Hunminjungum Keypad that applied the creation principle of Hunminjungum to the design of keypad. The proposed keypad arranged 28 letters of Hunminjungum to have correlations with each other between consonants, between vowels, and between consonants and vowels. That is, Consonant buttons are arranged by grouping letters of the same sound by sounds of five voices. And the vowel buttons are arranged at the bottom and the right side of the consonant area according to the position where a vowel is attached to the consonant. In the meantime, Hangul keypads have mainly used 12 button keypads in 4 lines and 3 columns. These keypads have structurally disadvantageous in the touch count and moving distance. Recently, keypads with many letter buttons such as QWERTY and single-vowel are also used a lot. If the number of letter buttons provided in the keypad increases, touch count decreases. And If the letter buttons are arranged to have a correlation with each other, the moving distance becomes smaller. The experimental results show that the proposed keypad has high efficiency in all evaluation factors such as touch count, moving distance and input time.