• Journal of the Korean Society for Aviation and Aeronautics
• /
• v.22 no.2
• /
• pp.60-70
• /
• 2014

This paper has tried to research the perception of pilots in a commercial airliners or full service carriers focusing on the airliner's safety management system (SMS). ICAO requires the airliners to set up the basic standards of SMS since the SMS is believed to be the core of the aviation risk management. According to the previous study, it was proved safety climate of an airline affects the safety behavior of cockpit crews. Safety climate is different from safety culture and the safety climate has an advantage to be measured more quantitatively than the culture. That is, the safety climate could be represented as SMS. As the results of the empirical study based on Chen & Chen(2014)'s SMS practice sacle, it had been assumed at the beginning the major factors such as Clarification of SMS, Safety Training for Crews and Sharing of SMS Information have positive effects on the motivation for safety behaviors. The motivation is directly correlated to crews' safety behaviors. However, the result showed the clarification of SMS has not a significant effect on their safety behaviors. The main reason is cockpit crews, through the survey, perceived airline seemed to have no definite standards of SMS and the senior management to have less interest in aviation safety.

• The Transactions of The Korean Institute of Electrical Engineers
• /
• v.66 no.8
• /
• pp.1250-1256
• /
• 2017

In this research, a high-performance ultrasonic positioning system is proposed to track the positions of an indoor mobile object. Composed of an ultrasonic sender (mobile object) and a receiver (anchor), the system employs three ultrasonic time-off-flights (TOFs) and trilateration to estimate the positions of the object with an accuracy of sub-centimeter. On the other hand, because ultrasonic waves are interfered by temperature, wind and various obstacles obstructing the propagation while propagating in air, ultrasonic pulse debounce technique and Kalman filter were applied to TOF and position calculation, respectively, to compensate for the interference and to obtain more accurate moving object position. To perform tasks in real time, ultrasonic signals are processed full-digitally with a Zynq SoC, and as a software design tool, Vivado IDE(integrated design environment) is used to design the whole signal processing system in hierarchical block diagrams. And, a hardware/software co-design is implemented, where the digital circuit portion is designed in the Zynq's fpga and the software portion is c-coded in the Zynq's processors by using the baremetal multiprocessing scheme in which the c-codes are distributed to dual-core processors, cpu0 and cpu1. To verify the usefulness of the proposed system, experiments were performed and the results were analyzed, and it was confirmed that the moving object could be tracked with accuracy of sub-cm.

• Journal of Internet Computing and Services
• /
• v.7 no.3
• /
• pp.93-105
• /
• 2006

The instant messenger is not only a wonderful tool for individuals. It is also a great tool which provides real-time dialogue and file transfers for individuals via the Internet and improves an enterprise productivity. However, it has many security risks that may have significant impact in corprate environments. This paper provides an overview of the security risks of the instant messenger with a risk analysis method and the controls that can be used to make it secure. It's hard to eliminate the instant messenger from enterprise environments because of its benefits. If we cannot avoid using it, we must make it secure and reap the full benefits of it.

• Journal of Korean Tunnelling and Underground Space Association
• /
• v.6 no.3
• /
• pp.199-211
• /
• 2004

As the length of local tunnels is getting longer, the demand for tunnel safety attracts more attention. But only a few information can be found concerning traffic and fire accidents occurred in local tunnel, and full-fledged studies had not been carried out to fulfill the expectation of the tunnel users. This study aims at collecting and analyzing the data on traffic and fire accidents in local road tunnels and providing the fundamental data for the tunnel fire safety evaluation. Focus is placed on quantifying the relationship among traffic accidents, fire occurrences and tunnel characteristics.

• International Journal of Aeronautical and Space Sciences
• /
• v.11 no.2
• /
• pp.69-79
• /
• 2010

This paper describes the experimental framework for the control system design and validation of a rotorcraft unmanned aerial vehicle (UAV). Our approach follows the general procedure of nonlinear modeling, linear controller design, nonlinear simulation and flight test but uses an indoor-installed multi-camera system, which can provide full 6-degree of freedom (DOF) navigation information with high accuracy, to overcome the limitation of an outdoor flight experiment. In addition, a 3-DOF flying mill is used for the performance validation of the attitude control, which considers the characteristics of the multi-rotor type rotorcraft UAV. Our framework is applied to the design and mathematical modeling of the control system for a quad-rotor UAV, which was selected as the test-bed vehicle, and the controller design using the classical proportional-integral-derivative control method is explained. The experimental results showed that the proposed approach can be viewed as a successful tool in developing the controller of new rotorcraft UAVs with reduced cost and time.

• The Journal of Asian Finance, Economics and Business
• /
• v.7 no.3
• /
• pp.235-243
• /
• 2020

The research aims to examine the impact of leadership style on accountants' commitment with FDI firms in Vietnam based on theory of Bass and Avolio (2004). A survey with 110 accountants in FDI firms was conducted. The total of 110 respondents with full information were used for data entry and analysis. Through quantity methodology, we used Cronbach's Alpha, EFA and correlation analysis to determine the relationship between leadership style and three dependent variables including affective, normative and continuance commitment. The results showed that the leadership style had positive relationships with accountants' commitments. In particular, normative commitment with FDI firms of accountants is the most strongest. In addition, there is no statistically difference in the level of three commitments with FDI firms of accountants for three groups of job description. From the findings, this study suggests several recommendations to improve accountants' commitments such as intellectually stimulating, individualized consideration, inspirational motivation, idealized influence, and idealized influence behavior. The results are considered as a useful reference for establishing policies to attract talent personnel toward to sustainable development of firms. Commitment with the organization is a crucial factor to gain a competitive advantage and guide the success of organizations by satisfying customers, maintaining productivity and efficiency.

• Journal of Satellite, Information and Communications
• /
• v.8 no.4
• /
• pp.30-36
• /
• 2013

Recently the globalization of the media content industry, various activities have been made in the field of art and the speaker system is very important in the sound industry which is one of the arts. The directional characteristics of a loudspeaker refer to the radiation of sound in certain directions and are among the most important features of a loudspeaker. Designing a loudspeaker that can keep all of its constant directivity at all frequencies is difficult due to the wavelengths of audio frequencies and the size of horns and transducers. This study proposed gradient array methods to improve low frequency pattern control of full-range speakers to maximize Direct to Reverberant Ratios at the listeners.

• Journal of Korea Multimedia Society
• /
• v.7 no.4
• /
• pp.532-541
• /
• 2004

Computer game has become the core part of multimedia area in our knowledge and information based society Recently, computer game has been evolving into on-line 3D games which give players more realism from the existing on-line 2D games. We are competitive in developing on-line 2D games. However, we have difficulties in maintaining the competitive edge in the area of 3D game technologies owing to the limited technologies. In this paper, we design and develop Aria Online, an on-line 3D prototype game using Dream3D. The on-line game supports simultaneous connections of multi -users on each game server and full flexibility on user's view.

• Structural Engineering and Mechanics
• /
• v.23 no.3
• /
• pp.279-292
• /
• 2006

Natural hazards, including the wind hazard and others, threaten the integrity of the modern society. A transportation system usually consists of roadways, bridges and related vehicles. Harsh environmental conditions, caused by such as wind, exist in the real world frequently and affect the dynamic performance of the transportation system through their interactions. Long-span bridges are usually the backbones of transportation lines. In windy conditions, the information about the dynamic performance of bridges and vehicles considering full interactions of environmental factors is very essential for people to assess the overall operational conditions and safety risks of the transportation lines. Most of existent approaches target specifically at several isolated tasks considering partial interaction effects. In order to improve the understanding of these related-in-nature problems integrally as well as the consistency of different approaches, a unified approach to integrally predict the dynamic performance of long-span bridges and vehicles under wind is introduced. Such an approach can be used as a general platform to predict the dynamic responses of vehicles and bridges under various situations through adopting both commercial and in-house software. Dynamic interaction effects can be fully considered automatically for each situation. An example of a prototype bridge in US is given for the purpose of demonstration.

• Wind and Structures
• /
• v.20 no.3
• /
• pp.469-488
• /
• 2015

A full-scale instrumented low-rise building with gable roof was built at a coastal site with a high incidence of tropical cyclones for monitoring of wind effects on the building during windstorms. This paper presents the field measurements of the wind velocity field around and the wind-induced pressures on the low-rise building during the passage of severe tropical storm Soudelor. Near-ground wind characteristics such as wind speed, wind direction, turbulence intensity, gust factor, turbulence integral length scale and wind velocity spectra were investigated. The wind-induced pressures on the roof of the building were analyzed and discussed. The results revealed that the eave and ridge edges on the roof were subjected to the most severe suction pressures under quartering winds. These suction pressures showed obvious non-Gaussian behavior. The measured results were compared with the provisions of ASCE 7-10 to assess the suitability of the code of practice for the wind-resistant design of low-rise buildings under tropical cyclones. The field study aims to provide useful information that can enhance our understanding of the extreme wind effects on low-rise buildings in an effort to reduce tropical cyclone wind damages to residential buildings.