• Journal of Astronomy and Space Sciences
• /
• v.30 no.4
• /
• pp.291-298
• /
• 2013

The concept of the satellite formation flight is area where it is actively study with expandability and safety compare to existing satellite. For execution of duty with more safety issue, it needs to consider hot topic of space debris for operation of formation flight. In this paper, it suggests heuristic algorithm to have avoidance maneuver for space debris towards operating flight formation. Indeed it covers, using common software, operating simulation to nearest space environment and not only to have goal of avoidance but also minimizing the usage of fuel and finding optimization for maximizing cycle of formation flight. For improvement on convergence speed of existing heuristic algorithm, it substitute to hybrid heuristic algorithm, PSOGSA, and the result of simulation, it represents the satisfaction of minimum range for successful avoidance maneuver and compare to not using avoidance maneuver, it keeps more than three times of formation maintenance performance. From these, it is meaningful results of showing several success goals like simple avoidance collision and fuel usage and decreasing number of times of maintaining formation maneuver.

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.20 no.3
• /
• pp.49-55
• /
• 2019

An open office or a shared office is emerging as the emphasis on the collaborative and communicative work environments is increasing. In the past, the user maintained the space, but the maintenance of indoor space became difficult because there is no fixed user. Indoor space information can be collected using the ICBM framework system. The facility management can achieve this with data. Therefore, this study proposed a framework based on ICBM (Internet of Things, Cloud, Big Data, and Mobile) for verifying the possibility of a smart facility management system for indoor space. IoT (Internet of Things) technology was used to measure the indoor temperature, humidity, occupancy, and brightness continuously, and provided the data to Web API via WiFi. Data acquired automatically via IoT, existing maintenance data, and spatial information were integrated through the Cloud. Big data collected by sensors were processed as meaningful spatial information for maintenance. Indoor space information and maintenance information can be delivered to the manager through the mobile. Based on the collected data, room occupancy recognition is limited due to a range of ultrasonic wave sensors. On the other hand, brightness represents the space conditions. The difference between lighting on/off, weekday and weekend can be shown. The temperature data and the relative humidity data were collected steadily to evaluate the comfort.

• Journal of the Korean Institute of Educational Facilities
• /
• v.17 no.6
• /
• pp.23-30
• /
• 2010

Because the effort to solve space shortage in academic libraries has never been successful, the rapid development of digital technology is being considered as a panacea to revolutionize analog libraries and to open a new era for digital libraries. However, this technology is yet to be perfected. Even with the use of digital technology, we are currently still looking for more space to accommodate newly printed materials and at the same time store valuable resources that are seldomly used. In 1985, Harvard adopted the industrial high-density shelving system into their library. No other retrieving system has proven to be more successful as the Harvard model. Presently, more than 50 colleges have built over 70 high-density library storage facilities. Rice University Library Service Center (RLSC) can be examined as an example of the Harvard-model. This paper will focus on assessing the operating system and architectural requirements of the RLSC which may allow for a more efficient, economical, and fundamental resolution to the library space shortage problem.

• Journal of Power Electronics
• /
• v.10 no.5
• /
• pp.468-476
• /
• 2010

This paper proposes and develops a new direct voltage control (DVC) approach. This method is designed to be applied in various applications for AC drives fed with a three-phase voltage source inverter (VSI) working with a constant switching time interval as in the standard direct torque control (DTC) scheme. Based on a very strong min(max) criterion dedicated to selecting the inverter voltage vector, the developed DVC scheme allows the generation of accurate voltage forms of waves. The DVC algorithm is implemented on a dSPACE DS1104 controller board and then compared with the space vector pulse width modulation technique (SVPWM) in an open loop AC drive circuit. To demonstrate the efficiency of the developed algorithm in real time and in closed loop AC drive applications, a scalar control scheme for induction motors is successfully implemented and experimentally studied. Practical results prove the excellent performance of the proposed control approach.

• International Journal of Aeronautical and Space Sciences
• /
• v.17 no.4
• /
• pp.526-534
• /
• 2016

A MEMS solid propellant thruster array shall be operated within an allowable range of operating temperatures to avoid ignition failure by incomplete combustion due to a time delay in ignition. The structural safety of the MEMS thruster array under severe on-orbit thermal conditions can also be guaranteed by a suitable thermal control. In this study, we propose a thermal control strategy to perform on-orbit verification of a MEMS thruster module, which is expected to be the primary payload of the STEP Cube Lab mission. The strategy involves, the use of micro-igniters as heaters and temperature sensors for active thermal control because an additional heater cannot be implemented in the current design. In addition, we made efforts to reduce the launch loads transmitted to the MEMS thruster module at the system level structural design. The effectiveness of the proposed thermo-mechanical design strategy has been demonstrated by numerical analysis.

• Journal of Korea Multimedia Society
• /
• v.17 no.12
• /
• pp.1511-1520
• /
• 2014

After 2011, with the spread of smart devices, large interfaces using the architectural space elements here and there in the cities. Recently the desire for the data has increased, and, following the increase of the range of use by the users, the communication utilizing various forms of interfaces is expected to become more active. In the past, certain range of architecture or parts of the facilities were as the interfaces, but, recently, the development of media technology and the display of various contents forced the utilization of many elements of architectural space in the interface aspects that were not used in the past. Accordingly, the research compare the relationship of the purpose, media environments, interface technology, data form and so on and consider the characteristic of what elements of architectural space are used in order to analyze the characteristic of interfaces used in digital art works. Especially,the research will consider the possibility of commercializing the trends in the interfaces of digital art works in the mediation region of city information services, and propose how to apply such possibility.

• Journal of the Korean Society for Aeronautical & Space Sciences
• /
• v.36 no.6
• /
• pp.616-620
• /
• 2008

High reliability is the important parameter on designing satellite system and it is also important to design hish speed data processing unit. To make high speed satellite processing unit, it is needed to utilize space processor, high speed data interface technology, mass memory control technology and data protection technology under space radiation environment.

• Journal of Astronomy and Space Sciences
• /
• v.36 no.2
• /
• pp.69-74
• /
• 2019

Spacecraft requires sufficient power in orbit to perform its mission. So as to comply with system requirements, the sufficient power should be made by a solar cell array by photovoltaic power conversion. A life time of space program depends on its mission considering parts reliability and parts grade. Based on the mission life time, power equipment might be designed to meet specifications. In outer space, solar cell array might generate the dc power by photovoltaic conversion effects and GaInP/GaAs/Ge solar cells are used in this study. Space programs that require more than five years should select parts for high reliability applications. Therefore, reliability analysis for high reliability applications should be performed to check its fulfilment of the requirements. This program should also require more five years for its mission and we performed its analysis using parts count method (PCM) for its reliability. Finally, we performed reliability analysis and obtained quantitative figures found out 99.9%. In this study, we presented the reliability analysis of the 300 W GaInP/GaAs/Ge solar cell array.

• Nuclear Engineering and Technology
• /
• v.54 no.12
• /
• pp.4776-4797
• /
• 2022

In the one-dimensional thermal-hydraulic (TH) codes, a subcooled boiling model to predict the void fraction profiles in a vertical channel consists of wall heat flux partitioning, the vapor condensation rate, the bubbly-to-slug flow transition criterion, and drift-flux models. Model performance has been investigated in detail, and necessary refinements have been incorporated into the Safety and Performance Analysis Code (SPACE) developed by the Korean nuclear industry for the safety analysis of pressurized water reactors (PWRs). The necessary refinements to models related to pumping factor, net vapor generation (NVG), vapor condensation, and drift-flux velocity were investigated in this study. In particular, a new NVG empirical correlation was also developed using artificial neural network (ANN) techniques. Simulations of a series of subcooled flow boiling experiments at pressures ranging from 1 to 149.9 bar were performed with the refined SPACE code, and reasonable agreement with the experimental data for the void fraction in the vertical channel was obtained. From the root-mean-square (RMS) error analysis for the predicted void fraction in the subcooled boiling region, the results with the refined SPACE code produce the best predictions for the entire pressure range compared to those using the original SPACE and RELAP5 codes.

• Fashion & Textile Research Journal
• /
• v.7 no.2
• /
• pp.143-152
• /
• 2005

A concept of 'digital' is changing a living pattern of moderners, with having influence on the whole life of modern society. The purpose of this study is arrange the frame of conformity to the 'fashion as culture' by considering the social and cultural phenomena being shown in relation to digital, which is a concept being watched most for the 21st century and by trying to analyze a tendency of digital culture being shown in the modernly fashion design based on this. The digital culture, which is a concept of generalizing the phenomena of interactional changes in the sub-structure being derived by digital technology, is being shown as a tendency of fusionization and globalization, and due to this, the culture of digital nomads is being formed. On the other hand, a tendency of amenity caused by the reaction against the coldly digital technology, is forming one axis of digital culture. As the culture, which experiences the process of a change by digital technology, is reflected even on the fashion, the fusion of technology and the human body, brought about the appearance and the development of the artificial body, by allowing the wearable computer to be introduced to fashion and by being connected directly to the body. This means the expansion of range for fashion. The destruction of a border between space and space, is making an opportunity of forming another ego inside the cyber space, with bringing about the mixed loading between the cyber space and the real space. As the border between the cyber space and the real space is being collapsed, the space of newly self-realization is being created. The collapse of gender is being shown as the pursuit of gender, which is a nomadic concept of not giving priority to anywhere of male gender and female gender. The tendency of sensitive design introduced the sports look as the largely fashion trend. Fascinated with Zen thoughts is leading to a response to the swiftly and coldly social conditions caused by machine. The digital culture by digital technology and the fashion tendency being shown by its influence, meet the needs of self-realization and self-expansion for a human being, and satisfy the needs for the expression of self-identity for a human being, and enable the search for introspection about inner existence inside the self.