• Journal of the Korean Society of Industry Convergence
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• v.26 no.1
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• pp.175-181
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• 2023

In offshore plants, various equipments including cranes and davits are used for safety management. Hydraulic cylinder type actuators are mainly used for luffing operations such as cranes and davits. However, in the case of a cylinder using hydraulic pressure, a separate power pack is required to supply hydraulic pressure. When used for a long time, maintenance costs such as sticking of hydraulic valves, contamination of hydraulic oil and deterioration of hydraulic hoses occur. In addition, a lot of hydraulic oil is used in the handling of cranes and davits, which causes marine pollution due to management problems. As a result, as interest in marine pollution prevention has increased recently, interest in actuators that do not use hydraulic pressure is also increasing. Therefore, in this study, we intend to develop a davit with an electric cylinder type actuator that uses electricity rather than hydraulic pressure by the SOLAS regulation. In other words, the conceptual design of the davit driven through the linear motion of the ball screw using electricity is performed, and the structural safety of the drive is also reviewed so that it can be utilized in the industrial field.

• The Magazine of the Society of Air-Conditioning and Refrigerating Engineers of Korea
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• v.8 no.3
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• pp.131-150
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• 1979

Recently only a few correlations between various factors due to the different grades of surface roughness for the nucleate pool boiling have been proposed. The main purpose of this work is to test the validity of these types of correlations between related factors to nucleate pool boiling phenomena. The boiling experiments using distilled water were carried out at the heat flux ranging from $7.4\times10^4\;to\;2.4\times10^5kcal/m^2h$ on the sintered porous metal surface with the cavity diameter of 10, n, 40, 70, $100{\mu}$, respectively, at the atmospheric pressure, To determine the bubble sizes, number of nucleation sites, delay and growth time, frequency of bubble emission and rising velocities of bubbles, the high speed motion picture technique was employed. In the correlation $f{\propto}D_b^n$, where f denotes frequency of bubble emission and $D_b$ departure diameter, n, the power factor of $D_b$, have been found to be from -2 to -10/3. The correlation C in the correlation between heat flux q and density of nucleation sites $\frac{N}{A}$, $q=C(\frac{N}{A})^n$, was appeared to be more crucial than the power factor n. The correlation of the heat flux q to the temperature difference ${\Delta}T$ and the density of nucleation sites$\frac{N}{A}$, was proposed to be $$q-460{\Delta}T^{\frac{5}{4}}=K{\Delta}T{\frac{5}{3}}(\frac{N}{A})^{\frac{2}{3}}$$. The values of heat transfer coefficient obtained in this experiments for the porous sintered metal surface appeared to be very high in comparison with the formerly obtained results for the other surfaces.

• International conference on construction engineering and project management
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• 2009.05a
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• pp.250-256
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• 2009

This paper presents a robotic tower-crane system using encoder and gyroscope sensors as path tracking devices. Tower crane work is often associated with falling accidents and industrial disasters. Such problems often incur a loss of time and money for the contractor. For this reason, many studies have been done on an automatic tower crane. As a part of 5-year 23-million-dollar research project in Korea, we are developing a robotic tower crane which aims to improve the safety level and productivity. We selected a luffing tower crane, which is commonly used in urban construction projects today, as a platform for the robotic tower crane system. This system comprises two modules: the automated path planning module and the path tracking module. The automated path planning system uses the 3D Cartesian coordinates. When the robotic tower crane lifts construction material, the algorithm creates a line, which represents a lifting path, in virtual space. This algorithm seeks and generates the best route to lift construction material while avoiding known obstacles from real construction site. The path tracking system detects the location of a lifted material in terms of the 3D coordinate values using various types of sensors including adopts encoder and gyroscope sensors. We are testing various sensors as a candidate for the path tracking device. This specific study focuses on how to employ encoder and gyroscope sensors in the robotic crane These sensors measure a movement and rotary motion of the robotic tower crane. Finally, the movement of the robotic tower crane is displayed in a virtual space that synthesizes the data from two modules: the automatically planned path and the tracked paths. We are currently field-testing the feasibility of the proposed system using an actual tower crane. In the next step, the robotic tower crane will be applied to actual construction sites with a following analysis of the crane's productivity in order to ascertain its economic efficiency.

• Journal of the Korean Society for Precision Engineering
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• v.13 no.10
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• pp.154-160
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• 1996

The control of diamond turning is usually achieved through a laser-interferometer feedback of slide position. The limitation of this control scheme is that the feedback signal does not account for additional dynamics of the tool post and the material removal process. If the tool post is rigid and the material removal process is relatively static, then such a non-collocated position feedback control scheme may surfice. However, as the accuracy requirement gets tighter and desired surface cnotours become more complex, the need for a direct tool-tip sensing becomes inevitable. The physical constraints of the machining process prohibit any reasonable implementation of a tool-tip motion measurement. It is proposed that the measured force normal to the face of the workpiece can be filtered through an appropriate admittance transfer function to result in the estimated dapth of cut. This can be compared to the desired depth of cut to generate the adjustment control action in additn to position feedback control. In this work, the design methodology on the admittance model-based control with a conventional controller is presented. The recursive least-squares algorithm with forgetting factor is proposed to identify the parameters and update the cutting process in real time. The normal cutting forces are measured to identify the cutting dynamics in the real diamond turning process using the precision dynamoneter. Based on the parameter estimation of cutting dynamics and the admitance model-based nanodynamic control scheme, simulation results are shown.

• Proceedings of the Korea Information Processing Society Conference
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• 2011.04a
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• pp.544-546
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• 2011

Due to the explosive growth of online social network users, large numbers of users discover these social network sites are a place where they can be able to spend their spare time, share feelings, ideas freely, and to search for new friends or partners. These web sites give an opportunity for its users to socialize with new people and to keep in touch or reconnect with current or old friends and families across disperse continents via these web sites, which traditionally replace the traditional methods. These social network web sites need careful investigations and findings on the usability for effective interactivity and more usability. However, little research might have previously invested on the usability of these on social network web sites. Therefore, we propose a new framework to study the usability of these social network sites. We namely call our framework "Interactivity". This framework will enable us to assess the usability of the social network sites. It will provide an overview of the user's behavior while interacting in these social network web sites. Measurement of the interactivity will be measured using Camtasia software. This software will entirely capture the interactivity of users including the screen and the movements, which the screen and the motion of the user action will undergo to analysis at the end of our research.

• Design Convergence Study
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• v.14 no.5
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• pp.31-45
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• 2015

Recently, due to the development of interactive media, Interactive Typography, which explores user input and interaction is under development. Unlike traditional typography which has a fixed nature, the flexible and fluid nature of Interactive Typography and Interactive System, enables diverse results. In this study, I have developed an Interactive Typography art piece based on theoretical research. By reviewing books, papers and articles, I have tried to define the meaning and characteristics of Interactive Typography. In understanding the concept of Interactive System, I have borrowed the concept of mathematical function. Based on the research, I have designed and developed an Interactive Typography piece, 'Interactive floral type' by using Adobe flash action script. This piece explores the beautiful shape of each alphabet letters and transforms individual character into a 'flower' shape through user's mouse and keyboard input. Depending on the input the size, color, and layout and motion of text changes in real time to change the letters into beautiful flowers.

• Progress in Medical Physics
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• v.33 no.4
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• pp.121-128
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• 2022

Purpose: This study evaluated the quality of plans based on magnetic resonance-guided radiotherapy (MRgRT) tri-Co-60, linac, and conventional linac-based volumetric modulated arc therapy (linac-VMAT) for prostate cancer. Methods: Twenty patients suffering from prostate cancer with intermediate risk who were treated by MAT were selected. Additional treatment plans (primary and boost plans) were generated based on MRgRT-tri-Co-60 and MRgRT-linac. The planning target volume (PTV) of MRgRT-based plans was created by adding a 3 mm margin from the clinical target volume (CTV) due to high soft-tissue contrast and real-time motion imaging. On the other hand, the PTV of conventional linac was generated based on a 1 cm margin from CTV. The targets of primary and boost plans were prostate plus seminal vesicle and prostate only, respectively. All plans were normalized to cover 95% of the target volume by 100% of the prescribed dose. Dosimetric characteristics were evaluated for each of the primary, boost, and sum plans. Results: For target coverage and conformity, the three plans showed similar results. In the sum plans, the average value of V_65Gy of the rectum of MRgRT-linac (2.62%±2.21%) was smaller than those of MRgRT tri-Co-60 (9.04%±3.01%) and linac-VMAT (9.73%±7.14%) (P<0.001). In the case of bladder, the average value of V_65Gy of MRgRT-linac was also smaller. Conclusions: In terms of organs at risk sparing, MRgRT-linac shows the best value while maintaining comparable target coverage among the three plans.

• Bulletin of the Korean Space Science Society
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• 2009.10a
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• pp.38.1-38.1
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• 2009

In this paper we present the first results of summer-time F region irregularities during low solar condition observed using the Gadanki MST radar. Echoes were observed on all 20 nights of radar observations and were mostly confined to the post-midnight hours. Echo morphology is very different from the equinoxial post-sunset plume-like features reported earlier from Gadanki. Echo SNRs are lower by 25 dB than their equinoxial post-sunset counterpart, and are quite comparable to the equinoxial irregularities in the post-midnight hours, which are essentially the decaying post-sunset irregularities. The Doppler velocities, which lie in the range of $\pm$ 100 m s-1, show upward/northward motion of the irregularities during the initial phase in contrast to the observed predominant downward/southward velocities associated with the decaying equinoxial post-midnight F region irregularities. Spectral widths of the summer echoes, which are well below 50 m s-1 and are very similar to those of the decaying equinoxial irregularities, represent the presence of weak plasma turbulence. Simultaneous observations made using a collocated ionosonde show no ionogram trace during 2200-0530 LT except for a few occasions. Weak frequency type spread F observed during midnight hours occurred without prior occurrence of range spread F. Concurrent ionosonde observations made from magnetic equatorial location Trivandrum also show very similar result and thus no height rise of the F layer during the midnight hours could be monitored. The preliminary analysis suggests that the post-midnight irregularities reported here are mostly freshly generated ones. The observations are discussed in the light of other observational results reported earlier and the current under standing on the post-midnight occurrence F region irregularities in summer.

• Korea Science and Art Forum
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• v.30
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• pp.367-376
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• 2017

This study introduces conducting practice tool for conducting majoring students. There have been various types of related research, but most of them have not been optimized for the conducting major. In addition, we thought that it would be a tool to be able to carry like a musical instrument in order to practice conducting without restriction of place and time. And also, it will be one of the few tools to focus on queuing. The practice tool presented in this study use the Doppler effect to overcome the limitations of previous studies. It was concluded that the Doppler method, which is highly compatible, simple, and accurate, is superior to motion detection methods using existing sensors. It is expected that it will be used not only as a conducting but also as an interaction tool of various media.

• Journal of Information Technology Services
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• v.22 no.6
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• pp.87-102
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• 2023

Existing child car seats do not have a monitoring means for the driver or guardian to effectively recognize the status of whether the seat belt of car seat is fastened and whether the ISOFIX of the car seat is fastened to the inside device of the vehicle. In this paper, we propose a smart car seat system which can monitor in real time, whether the seat belt of a child seated in the car seat is fastened and whether the ISOFIX of the car seat is fastened. The proposed system has been developed with a prototype, in which a Hall sensor, magnet, Bluetooth, and display device are used to detect whether these are fastened and to display the detection results. The prototype system provides the detection results as texts and alarm signal to the display for driver or guardian' smartphone in the car in motion. With functional tests of the prototype system, it was confirmed that the detection functions are properly operated, and the detection results were transmitted to the display device and smartphone via Bluetooth within 0.5 seconds. It is expected that the development system can effectively prevent safety accidents of child car seats.