• Journal of the Korean Academy of Child and Adolescent Psychiatry
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• v.14 no.2
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• pp.229-237
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• 2003

Objectives：Among the studies related to excessive computer use, the studies for elementary school students are relatively rare. Because children have relatively poor ability to recognize and express themselves, the carers' information is important to assess the children. This study attempted to investigate the relationship between children's computer use and sociopsychiatric characteristics on the basis of carers' reports. Methods：The subjects of this study were 287 5th- and 6th-grade students in the elementary school in Seoul. The student carers were asked to answer the questions for children's computer use, the computer addiction test modified from Young's parent-child internet addiction test, Korean Personality Inventory for Children(K-PIC). SPSS(version 10) was used to analyse the differnece of computer use between genders and the relation of the computer addiction test with K-PIC. Results：1) The score of computer addiction test was significantly higher in male children than in female children and more male children compared to female children were distributed in the excessive user group. 2) The score of computer addiction test correlated with the scores of most clinical scales of K-PIC and the average scores of most clinical scale were significantly higher in the excessive user group than in the general user group. 3) More children with score above 65 in HPR, DLQ, FAM scale were distributed in excessive user group than in general user group. Conclusion：The 5th- and 6th-grade elementary school students with excessive computer use were found to show more sociopsychiatric problems. With these finding we suggest that social and clinical attention to the children who use computer excessively shoud be required.

• The Journal of the Korea Contents Association
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• v.19 no.11
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• pp.365-374
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• 2019

Loss of Control in Flight(LOC-I) due to aircraft upset attitude has the highest air accident rate, and International Aviation Institute such as ICAO and FAA recommended flight crew to operate aircraft safely through UPRT(Upset Prevention & Recovery Training) program. ICAO has selected Loss of Control(LOC) as key safety indicator, and recommended to respond using TEM(Threat and Error Management). However there are not much specific treats and errors classified for UPRT programs using real TEM based on evidences. This study intends to consider the importance of UPRT through the introduction of UPRT and accident analysis using TEM. Typical upset accidents were classified to common threats as IFR, inadequate training, Automation surprise, and inexperienced copilots. The common errors were cross-check, speed and altitude deviation, callouts, communication, thrust and stall action fail. The undesired aircraft states were inadequate automation mode, Deviation of speed and vertical, stall, and crash. These suggest areas to improve UPRT.

• Journal of the Korean Society of Marine Environment & Safety
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• v.27 no.6
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• pp.867-874
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• 2021

The IoT (Internet of Things) technology is rapidly becoming an important consideration in many engineering fields in the current 4th industrial era. In recent years, the concepts of digital shipbuilding and smart factories have been adopted as trends in shipyards. However, there is active interest in research on implementing autonomous driving in autonomous vehicles and airplanes, which is currently available in commercial form in a limited capacity. The present study is regarding the path-tracking performance of a boat to accomplish an autonomous driving mission using a flight controller (FC) and real-time kinematic (RTK) global positioning system (GPS) based on an open-source Ardupilot; an actual sea test is also performed using this system on a calm lake. The boat's mission is to evaluate the maneuverability of the self-driving process to a specific point and returning to the home position. For a given speed, the difference between the preset mission trajectory and actual operational trajectory was analyzed, and a series of studies were conducted on the applicability of the system to ships. In addition, the movements and maneuverability of the OmniX-type hull with four propellers were investigated, and the driving path-tracking performance was observed to increase by a maximum of 48%.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.21 no.5
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• pp.103-111
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• 2021

The purpose of this study is to study a method for preventing collisions of multiple drones in controlled airspace. As a result of the study, it was proved that it is appropriate as a method to control drone collisions after setting accurate information on the ROI (Region of Interest) area estimated based on the expected drone path and time in the control system as a method to avoid drone collision. As a result of the empirical analysis, the diameter of the flight path of the operating drone should be selected to reduce the risk of collision, and the change in the departure time and operating speed of the operating drone did not act as an influencing factor in the collision. In addition, it has been demonstrated that providing flight priority is one of the appropriate methods as a countermeasure to avoid collisions. For collision avoidance methods, not only drone sensor-based collision avoidance, but also collision avoidance can be doubled by monitoring and predicting collisions in the control system and performing real-time control. This study is meaningful in that it provided an idea for a method for preventing collisions of multiple drones in controlled airspace and conducted practical tests. This helps to solve the problem of collisions that occur when multiple drones of different types are operating based on the control system. This study will contribute to the development of related industries by preventing accidents caused by drone collisions and providing a safe drone operation environment.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.20 no.5
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• pp.627-635
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• 2019

A programmable drone is a drone developed not only to experience the basic principles of flight but also to control drones through Arduino-based programming. Due to the nature of the training drones, the main users are students who are inexperienced in controlling the drones, which often cause frequent collisions with external objects, resulting in high damage to the drones' frame. In this study, the structural stability of the drone was evaluated by means of a structural dynamics based collision simulation for educational drone frame. Collision simulations were performed on three cases according to the impact angle of $0^{\circ}$, $+15^{\circ}$ and $-15^{\circ}$, using an analytical model with approximately 240,000 tetrahedron elements. Using ANSYS LS-DYNA, which provides excellent functions for the simulation of the dynamic behavior of three-dimensional structures, the stress distribution and strain generated on the drone upper, the drone lower, and the ring assembly were analyzed when the drones collided against the wall at a rate of 4 m/s. Safety factors resulting from the equivalent stress and the yield strain were calculated in the range of 0.72 to 2.64 and 1.72 to 26.67, respectively. To ensure structural stability for areas where stress exceeds yield strain and ultimate strain according to material properties, the design reinforcement is presented.

• Journal of Aerospace System Engineering
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• v.16 no.1
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• pp.56-69
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• 2022

Various advanced countries are accelerating the competition in the development of hypersonic weapons. North Korea is on the verge of building a new submarine equipped with a submarine-launched ballistic missile (SLBM). A series of new guided missiles tests have continued due to political competition between the U.S. and China. The Republic of Korea is planning to boost its military capabilities, which involves the development of nuclear-powered submarines, light aircraft carriers, and new guided missiles. The northeast Asian region continues to be tense amid military rivalry between the Republic of Korea, North Korea, the United States, China, Russia, and Japan. Accordingly, these countries' competition to develop weapons is also at the world's highest level. In this paper, we examine the functioning of a hypersonic weapons system conduct a technical analysis of its components. In addition, we analyze the direction of military development that the Korean military wants to pursue through the recently announced mid-term defense plan. We conclude by highlighting the technical limitations and implementation strategies to overcome the development of hypersonic weapons.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.30 no.6A
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• pp.543-560
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• 2010

Safety-related concrete structures in a nuclear power plant must be protected against the impact of flying objects, referred to in the profession as missiles. In practice, the structural verification is usually carried out by means of empirical formulas, which relate the velocity of the impinging missile to the wall thickness needed to prevent scabbing or perforation. The purpose of this study is to reevaluate the predictability of the local effect prediction formulas for the penetration and scabbing depths and perforation thickness. Therefore, available formulas for predicting the penetration depth, scabbing thickness, and perforation thickness of concrete structures impacted by solid missiles are summarized, reviewed, and compared. A series of impact analyses is performed to predict the local effects of the projectile at impact velocities varing from 95 to 215 m/s. The results obtained from the numerical simulations have been compared with tests that were carried out at Kojima to validate numerical modelling. The simulation results show reasonable agreement with the Kojima test results for the overall impact response of the RC slabs. From these results, it seems that the Degen equation give a very good estimate of perforation thickness against a tornado projectile for test data. Finally, the results obtained from the impact analysis have been compared with Degen formula to determine the perforation thickness of the RC slab.

• Journal of Advanced Navigation Technology
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• v.27 no.6
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• pp.690-698
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• 2023

Information sharing and decision making between airport stakeholders became possible after the introduction of airport cooperative making system (A-CDM). This also resulted in optimizing aircraft handling time and increased the efficiency of aircraft operations. Technological advances have recently led to the development of urban air mobility (UAM) which is a small aircraft taking off and landing vertically. It is emerging as a new air transportation system in the future due to its advantage of saving time and solving congestion problem in the urban area. This study aims to suggest how vertiport cooperative decision making system (V-CDM) should be managed for efficient operation of UAM. By establishing procedure for decision making system based on Vertiport ecosystem of UAM. By establishing procedure for decision making system based on Vertiport ecosystem and UAM aircraft, unnecessary flight delays or cancellations can be minimized and efficiency of UAM operation will be improved as well.

• The Korean Journal of Air & Space Law and Policy
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• v.24 no.2
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• pp.211-234
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• 2009

North Korea conducted the launcher test, which, as North Korea claimed, belonged to the sovereign rights for the purpose of peaceful utilization and exploration of the outer space. The launching was allegedly done for the sole purpose of putting the satellite into earth orbit, while international community stressed the fact that the orbiting of satellite was not confirmed and that the technology used was not distinct from the purpose of building intercontinental ballistic missile. UN Security Council adopted the resolutions which took the effect that the launching was deemed as the missile launching, not the mere launcher test. North Korea declared the moratorium of suspending its test activity. Controversial issues have been raised regarding whether the launcher itself has the legal status of enjoying the freedom of space flight based upon the 1967 Outer Space Treaty. The resolutions, however, has put forward a binding instrument forbidding the launching. UN Security Council resolutions, however, should be read not as defining the missile test illegal, in that the language of resolutions, such as 'demand', should be considered as not formulating a sort of obligatory act or inact. On the other hand, the resolutions should be read as having binding force with respect to any activity relating to the weapons of mass destruction. The resolution 1718 is written in more specific language such as 'decides that the DPRK shall suspend all activities related to its ballistic missile programme and in this context re-establish its pre-existing commitments to a moratorium on missile launching'. Therefore, the lauching activity of the North Korea is banned by the UN Security Council resolution. It should be noted that the resolution does not include any specific provisions defining the space of activity of the North Korea as illegal. But, the legal effect of the moratorium is not denied as to its launching itself, which is corresponding to the missile test clearisibanned in accordance with the resolutions.

• Journal of the Korean Academy of Child and Adolescent Psychiatry
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• v.7 no.1
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• pp.34-43
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• 1996

In adolescence, the symptoms of depression are more various and different from those of adult. Conduct behaviours are frequently represented in adolescent's depression. The patients who have the depression and conduct disorder are defined as depressive condor disorder in ICD-10. We hypothesized that there might be different parental rearing patterns between the patients with depression alone and the depressive conduct disorder. We applied children's depression inventory (CDI), parental rating form for conduct disorder based on DSM-III-R, and parental bonding instrument (PBI) to patients and normal control adolescent group. The results were as follows : 1) There were no significant differences in severity of depressive symptoms, maternal care, maternal overprotection, and paternal care. 2) Paternal overprotection showed significant higher scores in depressive conduct disorder group than depression group and normal control group. 3) There were positive correlations in the severity of depressive symptoms and behavior problems in all subjects. 4) There were no correlations in maternal care and overprotecion with conduct problems, but with depressive symptoms in all subject. 4) There were no correlations in paternal care with conduct problems and depressive symptoms in all subjects. 5) There were significant correlations in patienral overprotective, intrusive attitudes with conduct problems, not with depressive symptoms in all subjects.