• Journal of Advanced Navigation Technology
• /
• v.19 no.2
• /
• pp.98-102
• /
• 2015

In this paper are This paper is about the efficient use operational management plan for the metropolitan public Jamsil heliport. First, understand the general operations and facilities to Jamsil heliport and raised the issue for them. And, in cases such as urban offshore heliport Jamsil heliport in New York and Texas (USA), for example, which was presented for comparative analysis and Jamsil heliport in London (UK). Operations, research is seen against a facility to install and manage a couple of airfield operations based on the subject by presenting the alternatives, thereby causing the principal operating facilities, infrastructure and security facilities even suggest ways to enhance the standards. Unlike other countries, Jamsil heliport location characteristics were excluded from the study on the safety aspects related to flight operations and for this I'm a military airport facilities coexist in the neighborhood.

• Journal of Ship and Ocean Technology
• /
• v.12 no.3
• /
• pp.26-35
• /
• 2008

Recognition of real time locations of crews for a naval ship is important, not only for the operation efficiency but also for the safety of onboard crews in the ship. More than 100 crews are dwelling in a modem naval ship and they are involved in various duties. Moreover many visitors come in and out frequently while the ship is moored in a harbor. It sometimes requires considerable time and efforts to find a person for urgent mission. It would enhance the operational efficiency if locations of onboard crews are recognized and monitored in real time. An active type RFID tag, which has a specific ID number, is distributed to each crew member, which should be carried during his stay in the ship. A number of fixed type RFID readers are to be located at the major passages of the ship, which are connected to the main computer via Local Area Network. The location of a crew would be identified by the ID number of his RFID tag and the location of the RFID reader which detected the RFID tag. A middleware is needed to process the collected data in the main computer. The data is fed to application softwares, which actually display locations of the concerned crews. The software is coded using GUI (Graphic User Interface) for better user friendliness, which has the function of storing the location history of a crew, and sending warning messages to appropriate persons, if unallowable behavior is detected. An auxiliary naval ship is selected for an experimental application study of the proposed system. It turns out that the required budget and time for the realization of the system is within the allowable limits. But complementary measures to protect the privacy of onboard crews should be considered and adopted, before the application of the system is realized.

• Journal of IKEEE
• /
• v.25 no.3
• /
• pp.578-583
• /
• 2021

This paper describes acceleration tests for reliability of semiconductors. It also describes AEC-Q100, international test standard for reliability of automotive semiconductors. Semiconductors can be used for dozens of years. So acceleration tests are essential to test potential problems over whole period of product where test time is minimized by applying intensive stresses. AEC-Q100 is a typical acceleration test in automotive semiconductors, and it is designed to find various failures in semiconductors and to analyze their causes of occurance. So it finds many problems in design and fabrication as well as it predicts lifetime and reliability of semiconductors. AEC-Q100 consists of 7 test groups such as accelerated environmental stress tests, accelerated lifetime simulation tests, package assembly integrity tests, die fabrication reliability tests, electrical verification tests, defect screening tests, and cavity package integrity tests. It has 4 grades from grade 0 to grade 3 based on operational temperature. AEC-Q101, Q102, Q103, Q104, and Q200 are applied to discrete semiconductors, optoelectronic semiconductors, sensors, multichip modules, and passive components, respectively.

• Journal of the Korea Convergence Society
• /
• v.10 no.3
• /
• pp.177-184
• /
• 2019

The Defense Technology Security Act was enacted in 2015 to protect the defense industrial technology from being duplicated or interfering technologies being developed, which prevents its value and utility from deterioration and prevents inappropriate export. Defense industrial technology refers to technology that should be protected for national security among the national defense science and technology related to the defense industry. However, technical identification criteria of identification and management system of protection technology are not regulated. Therefore, in this study, through the Delphi survey, diesel engine core technology identification criteria related to the high efficiency internal combustion engine propulsion technology among the 141 defense industrial technologies is established to improve the identification and management system of the technology to be protected among the defense industrial technology protection system. As a result of the study, operational operability, durability, safety, sequencing and modularization were established as diesel engine core technology identification criteria.

• Journal of the Korean Society of Manufacturing Process Engineers
• /
• v.18 no.6
• /
• pp.98-105
• /
• 2019

In order to improve the fuel economy and dynamic behavior of automobiles, the weight reduction tendency of automobile parts is obvious. Also, in order to maximize assembly and maintenance convenience, various parts are integrated and modularized. Multi-piece methods require many manufacturing processes and become a factor of lowering the strength of parts. It is advantageous to overcome the disadvantages by integrally manufacturing to reduce the processing steps and ensure the strength of the parts. However, when it is necessary to process in a narrow space inside the part, it is impossible to process with the existing spindle. The angle head spindle is only a component of a machine tool, but it is a core part that requires high technology and is highly utilizable in products requiring high precision machining. Therefore, various and continuous studies needs for angle head spindles in areas such as vibration absorption, operational safety, excellent dimensional stability, and strength. In this paper, we propose an optimal design for angle head spindle by performing structural analysis and shape optimization for angle head spindle gear and case.

• Convergence Security Journal
• /
• v.19 no.2
• /
• pp.123-128
• /
• 2019

In March 2016, the Korean National Assembly passed the Counterterrorism Act called as "Counterterrorism Law for the Protection of the People and Public Safety", and relevant functions and roles of the counterterrorism institution were granted based on the law. However, a number of problems have been raised in the course of the job performance of the counterterrorism related institution, and various improvements have been discussed. This study conducted 'Analytic Hierarchy Process(AHP)' on the experts to identify the issues related to the improvement possibilities of the counterterrorism system that had been discussed previously. The results of the analysis to improve the current counterterrorism system are as follows. First, the priorities of the top factors were identified as in the order of legal institutions, cooperation, and operational aspect. Next, the priorities of the individual sub-factors were identified as the reorganization of the counterterrorism task force, the organic cooperation of domestic counterterrorism institution, and the cultivation of specialized human resources for anti-terrorism work. It was found that we should discuss the reorganization of counterterrorism institution as a policy consideration to improve the counterterrorism system.

• Journal of Korean Society of Water and Wastewater
• /
• v.33 no.2
• /
• pp.111-119
• /
• 2019

Electro-coagulation process has been gained an attention recently because it could overcome the membrane fouling problems in MBR(Membrane bio-reactor). Effect of the key operational parameters in electro-coagulation, current density(${\rho}_i$) and contact time(t) on membrane fouling reduction was investigated in this study. A kinetic model for ${\rho}_i$ and t required to reduce the membrane fouling was suggested under different MLSS(mixed liquor suspended solids) concentration. Total 48 batch type experiments of electro-coagulations under different sets of current densities(2.5, 6, 12 and $24A/m^2$), contact times(0, 2, 6 and 12 hr) and MLSS concentration(4500, 6500 and 8500mg/L) were carried out. After each electro-coagulation under different conditions, a series of membrane filtration was performed to get information on how much of membrane fouling was reduced. The membrane fouling decreased as the ${\rho}_i$ and t increased but as MLSS decreased. Total fouling resistances, Rt (=Rc+Rf) were calculated and compared to those of the controls (Ro), which were obtained from the experiments without electro-coagulation. A kinetic approach for the fouling reduction rate (Rt/Ro) was carried out and three equations under different MLSS concentration were suggested: i) ${\rho}_i^{0.39}t=3.5$ (MLSS=4500 mg/L), ii) ${\rho}_i^{0.46}t=7.0$ (MLSS=6500 mg/L), iii) ${\rho}_i^{0.74}t=10.5$ (MLSS=8500 mg/L). These equations state that the product of ${\rho}_i$ and t needed to reduce the fouling in certain amounts (in this study, 10% of fouling reduction) is always constant.

• Journal of Korean Society of Water and Wastewater
• /
• v.33 no.2
• /
• pp.95-101
• /
• 2019

High voltage impulse(HVI) has been gained attention as an alternate technique controlling $CaCO_3$ scale formation. Investigation of key operational parameters for HVI is important, however, those had not been reported yet. In this study, the effect of temperature and applied voltage of HVI on $Ca^{2+}$ concentration was studied. As the applied voltage from 0 to 15kV and the temperature increased from 20 to $60^{\circ}C$, the $Ca^{2+}$ concentration decreased, indicating that the aqueous $Ca^{2+}$ precipitated to $CaCO_3$. The $Ca^{2+}$ concentration decreased up to 81% under the condition of 15kV and $60^{\circ}C$. Rate constant for the precipitation reaction, k was determined under different temper1ature and voltage. The reaction rate constant under the 15kV and $60^{\circ}C$ condition was evaluated to $66{\times}10^{-3}L/(mmol{\cdot}hr)$, which was 5 times greater than the k of the reaction without HVI at same temperature. The increases in k by HVI at higher temperature region(40 to $60^{\circ}C$) was much greater than at lower temperature region(20 to $40^{\circ}C$), which implies temperature is more important parameter than voltage for reducing $Ca^{2+}$ concentration at high temperature region. These results show that the HVI induction accelerates the precipitation to $CaCO_3$, particularly much faster at higher temperature.

• International Journal of Naval Architecture and Ocean Engineering
• /
• v.12 no.1
• /
• pp.241-257
• /
• 2020

The rapid proliferation of oil/gas drilling and wind turbine installations with jack-up rig-formed structures increases structural safety requirements, due to the greater risks of operational collisions during use of these structures. Therefore, current industrial practices and regulations have tended to increase the required accidental collision design loads (impact energies) for jack-up rigs. However, the existing simplified design approach tends to be limited to the design and prediction of local members due to the difficulty in applying the increased uniform impact energy to a brace member without regard for the member's position. It is therefore necessary to define accidental load estimation in terms of a reasonable collision scenario and its application to the structural response analysis. We found by a collision probabilistic approach that the kinetic energy ranged from a minimum of 9 MJ to a maximum 1049 MJ. Only 6% of these values are less than the 35 MJ recommendation of DNV-GL (2013). This study assumed and applied a representative design load of 196.2 MN for an impact load of 20,000 tons. Based on this design load, the detailed design of a leg structure was numerically verified via an FE analysis comprising three categories: linear analysis, buckling analysis and progressive collapse analysis. Based on the numerical results from this analysis, it was possible to predict the collapse mode and position of each member in relation to the collision load. This study provided a collision strength assessment between attendant vessels and a jack-up rig based on probabilistic collision scenarios and nonlinear structural analysis. The numerical results of this study also afforded reasonable evaluation criteria and specific evaluation procedures.

• Journal of the Korean Society for Aeronautical & Space Sciences
• /
• v.50 no.3
• /
• pp.147-155
• /
• 2022

The accumulated ice and snow during the operation of aircraft and railway vehicles can degrade aerodynamic performance or damage the major components of vehicles. Therefore, it is crucial to predict the temporal growth of ice for operational safety. Numerical simulation of ice is widely used owing to the fact that it is economically cheaper and free from similarity problems compared to experimental methods. However, numerical simulation of ice generally divides the analysis into multi-step and assumes the quasi-steady assumption that considers every time step as steady state. Although this method enables efficient analysis, it has a disadvantage in that it cannot track continuous ice evolution. The purpose of this study is to construct a surrogate model that can predict the temporal evolution of ice shape using reduced-order modeling. Reduced-order modeling technique was validated for various ice shape generated under 100 different icing conditions, and the effect of the number of training data and the icing conditions on the prediction error of model was analyzed.