• Journal of the Korea Society for Simulation
• /
• v.21 no.2
• /
• pp.19-30
• /
• 2012

In recent decades, it has been known that the Discrete Event System Specification, or DEVS, formalism provides sound semantics to design a modular and hierarchical model of a discrete event system. In spite of this benefit, practitioners have difficulties in applying the semantics to real-world systems modeling because DEVS needs to specify a large size of sets of events and/or states in an unstructured form. To resolve the difficulties, this paper proposes an extension of the DEVS formalism, called the Structured DEVS formalism, with an associated graphical representation, called the DEVS diagram, by means of structural representation of such sets based on closure property of set theory. The proposed formalism is proved to be equivalent to the original DEVS formalism in their model specification, yet the new formalism specifies sets in a structured form with a concept of phases, variables and ports. A simplified example of the structured DEVS with the DEVS diagram shows the effectiveness of the proposed formalism which can be easily implemented in an objected-oriented simulation environment.

• Journal of Sensor Science and Technology
• /
• v.13 no.6
• /
• pp.479-487
• /
• 2004

The prevention of noise induced hearing loss is very important, because there is no treatment for it. There are some kinds of devices for hearing protection, and those are effective in preventing a noise induced hearing loss. However, people often resist the use of hearing protection devices because it is difficult to have a conversation. Therefore, a hearing protection device is must effective not only in hearing protection but also in preserving communication ability. In this paper, we proposed a small acoustic filter for ITE type noise protector to solving the problem about the difficulties of conversation. That is applied a principle of acoustic filters that have been used for a muffler of automobiles, guns, and etc. To find out the sound transmission characteristic at the eardrum, we regarded an acoustic filter and external ear canal as a coupled system. So, we simulated the coupled system with OrCad, and experimented with a designed acoustic filter and a 2 cc coupler which has the same transmission characteristic as the external ear canal has. We confirmed that it is possible to adjustment acoustic transmission characteristics through simulation of electrical model for acoustic filter and external ear and experiments using designed small acoustic filters.

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

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

• Journal of Ocean Engineering and Technology
• /
• v.30 no.5
• /
• pp.400-404
• /
• 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
• /
• 2022.05a
• /
• pp.180-182
• /
• 2022

As various crimes such as theft, assault, and sex crimes are increasing, each local government is installing CCTVs to prevent them, and operating and managing control centers for emergency response. When the control center detects a dangerous situation in the field, it responds immediately in connection with the police or 911. However, since it is managed by humans, the response speed is anomalous and the reality is that it is mainly used for post-processing. Therefore, through the artificial intelligence LED signage, it notifies the emergency situation at the site, and it serves as a warning function before getting help from passers-by or an accident occurs. In this paper, we design and research a warning system such as changing the lighting color of the LED signboard or making a sound by reflecting the artificial intelligence algorithm. We intend to contribute to public safety and social safety through this study.

• Science of Emotion and Sensibility
• /
• v.21 no.3
• /
• pp.165-176
• /
• 2018

The objective of this study was to develop clothing-type wearable motion sensing and feedback systems to enhance children's sports by promoting visual and audio feedback. In this study, several applications, such as fabric sensors, sportswear integrated with various types of fabric sensors, and fabric-based motion sensing module design, as well as a visual and audio feedback system for gaining a better understanding of a child's interest in a type of exercise, were developed. An SWCNT-based stretchable fabric sensor was developed for motion sensing, and sportswear was designed using the fabric sensor that was integrated into the limbs of the garment. The sensing module was developed, and sensory performance was evaluated through a joint motion experiment for children. In addition, using the feedback system that was developed in the form of an accessory, the responses of light and sound were also examined based on the movement of the child who was wearing the sportswear prototypes. This study focused on the development and assessment of prototype designs for children's sportswear and accessory products that can help to ascertain a child's interest in a particular exercise.

• Journal of Korea Multimedia Society
• /
• v.7 no.2
• /
• pp.223-230
• /
• 2004

A shooting game is all game genres that hit targets through shooting. It include a lot of genres from a flying shot of game room to a personal shooting action game. In this point, a shooting game was regarded it as the origin of all game and it was developed from the early days of game. At present we can meet it in an electronic game room or personal computer, and mobile phone etc.. The popularity of shooting game caused to take aim by simple system, interface, and speedy play. Also it was enticed everyone to enjoy it easily. A shooting games is worked from old like ways until recently and a process of playing game is intuitive than another game. Therefore it popular with a PC player as well as persons of all levels. Beginners can train this game easily through direction such as control way of object, advent way of enemy aircraft and scroll way of background. But as an usability of working and controlling game, beginners of game development can pass over a shooting sense that shout and hit basically. And after design, they will feel that cannot convey realistic effect and thrill etc.. At a result, hitting sense happens to graphic elements and sound. Therefore a measure of effect on these elements is started from analysis of good shooting game. This study was to focus on the advance effect of hitting sense in shooting game through analysis centered for 'the Beetlewing' and '1945 Plus'.

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.19 no.12
• /
• pp.272-278
• /
• 2018

Traffic volume has been greatly increasing due to urban development and the improvement of living standards, and many complaints are being raised due to the increasing road noise. As a countermeasure against these problems, highly soundproof walls are installed on the sides of roads. However, the ability to bear wind loads is a major design requirement for soundproof walls, which contributes to the exponential increases in construction costs and restricts the height of the walls. The aim of this study is to improve the performance of soundproof walls and to dramatically reduce wind loads while maintaining excellent price competitiveness. Based on Helmholz's resonator theory, a new concept is proposed for a ventilation-type soundproofing plate that can pass through a fluid like air and reduce noise. A full-scale metal soundproofing plate was produced to satisfy the quality standards of highways by conducting a sound-pressure transmission-loss test, wind tunnel test, and material quality test. To verify the reliability, the wall was manufactured and installed, and the sound insulation effect was examined by measuring the noise over time. In the future, ventilated soundproof walls on roads could create a pleasant living environment due to the high noise-insulation effect.

• Transactions of the Korean Society of Mechanical Engineers B
• /
• v.38 no.12
• /
• pp.1057-1064
• /
• 2014

Recently, there has been a growing interest in sustainable energy. One method that has been used is an organic Rankine cycle using conventional turbine technology with a low-temperature waste heat source. A 200-kW organic Rankine cycle (ORC) system was designed for a waste heat recovery application using R245fa as the working fluid. A radial turbine running at 15,000 rpm was employed to generate more than 200 kW with an expansion ratio of nine. Because an ORC turbine uses a refrigerant as the working fluid, the ideal gas law was not employed to design the turbine. In addition, the complexity of the molecular structure of R245fa made it difficult to design the turbine. Because R245fa has an Ma value of one at a low velocity for the working fluid (about 1/3 of the speed of sound in air) at about $100^{\circ}C$, it easily reaches a supersonic flow condition with a small pressure expansion. To increase the efficiency of the turbine, a dual stage radial-type turbine with a subsonic speed was suggested. This paper will describe the design procedure and performance evaluation of the ORC turbine using R245fa.