• Convergence Security Journal
• /
• v.18 no.4
• /
• pp.73-79
• /
• 2018

Since 1910s, the drones were mainly used for military purposes for reconnaissance and attack targets, but they are now being used in various fields such as disaster prevention, exploration, broadcasting, and surveillance of risk areas. As drones are widely used from military to civilian field, hacking into the drones such as radio disturbance, GPS spoofing, hijacking, etc. targeting drones has begun to occur. Recently, the use of drones in hacking into wireless network has been reported. If the artificial intelligence technology is applied to the drones in the military, hacking into unmanned combat system using drones will occur. In addition, a drone with a hacking program may be able to relay a hacking program to the hacking drone located far away, just as a drone serves as a wireless communication station. And the drones will be equipped with a portable GPS jamming device, which will enable signal disturbance to unmanned combat systems. In this paper, we propose security threats and the anticipated hacking scenarios using the drones on the battlespace to know the seriousness of the security threats by hacking drones and prepare for future cyberspace.

• The Journal of the Convergence on Culture Technology
• /
• v.8 no.6
• /
• pp.775-785
• /
• 2022

By analyzing the operation status of fire safety management of small construction site workers, deriving problems, and suggesting improvement measures, this study was conducted to present practical basic data for their efficient use in the future, and the following conclusions were drawn. First, it was analyzed that small construction site workers are elderly in the age group of construction workers, have short construction skills, most of the jobs are working in the construction industry, and the employment type is non-regular workers. Second, the fire safety management improvement plan of small construction site workers is systematized, fire safety manager is deployed to manage fire risk, fire escape routes and emergency warning facilities are provided to inform all workers at the construction site. In addition, measures to reduce industrial accidents are needed through realistic evacuation training, fire VR training, and interesting educational programs.

• Journal of the Korea institute for structural maintenance and inspection
• /
• v.27 no.1
• /
• pp.86-94
• /
• 2023

In this study, a supplementary detail capable of restraining out-of-plane deformation was proposed for steel slit dampers, and a constant amplitude cyclic loading test was performed with the application of the proposed detail and the shape ratio of the damper as variables. Repeated hysteresis and cumulative plastic deformation according to the test results were analyzed. Repeated hysteresis of the slit damper with the proposed detail showed a stable spindle-shaped hysteresis within the set variable range, and no out-of-plane deformation of the damper was observed until ultimate state. It was confirmed that the restraining panel effect through the application of the proposed details is effective in terms of both the strength and deformation capacity of the damper. In addition, experimental parameters for the fatigue curve evaluation of slit dampers were derived in this study. Based on the results, it is judged that quantitative comparison of structural performance with various types of seismic devices will be possible in the future.

• Proceedings of the Korea Water Resources Association Conference
• /
• 2023.05a
• /
• pp.198-198
• /
• 2023

유역 내 수자원 계획을 효율적으로 수립하기 위해서는 장기간에 걸친 수문 모델링 뿐만 아니라 미래 기후 시나리오에 따른 수문학적 기후변화 영향 분석도 중요하다. 이를 위해서는 관측 값에 기반한 고품질 및 고해상도 격자형 기상자료 생산이 필수적이다. 하지만, 우리나라는 종관기상관측시스템(ASOS)과 방재기상관측시스템(AWS)으로 이루어진 고밀도 관측 네트워크가 2000년 이후부터 이용 가능했기에 장기간 격자형 기상자료가 부족하다. 이를 보완하고자 본 연구는 가정적인 상황에 기반하여 만약 2000년 이전에도 현재와 동일한 고밀도 관측 네트워크가 존재했다면 산출 가능했을 장기간 일 단위 고해상도 격자형 기상자료를 생산하는 것을 목표로 한다. 구체적으로, 2000년을 기준으로 최근과 과거 기간의 격자형 기상자료를 딥러닝 알고리즘으로 모델링하여 과거 기간을 대상으로 기상자료(일 단위 기온, 강수량)의 공간적 변동성 및 특성을 재구성한다. 격자형 기상자료의 생산을 위해 우리나라의 고도에 기반하여 기상 인자들의 영향을 정량화 하는 보간법인 K-PRISM을 적용하여 고밀도 및 저밀도 관측 네트워크로 두 가지 격자형 기상자료를 생산한다. 생산한 격자형 기상자료 중 저밀도 관측 네트워크의 자료를 입력 자료로, 고밀도 관측 네트워크의 자료를 출력 자료로 선정하여 각 격자점에 대해 Long-Short Term Memory(LSTM) 알고리즘을 개발한다. 이 때, 멀티 그래픽 처리장치(GPU)에 기반한 병렬 처리를 통해 비용 효율적인 계산이 가능하도록 한다. 최종적으로 1973년부터 1999년까지의 저밀도 관측 네트워크의 격자형 기상자료를 입력 자료로 하여 해당 기간에 대한 고밀도 관측 네트워크의 격자형 기상자료를 생산한다. 개발된 대부분의 예측 모델 결과가 0.9 이상의 NSE 값을 나타낸다. 따라서, 본 연구에서 개발된 모델은 고품질의 장기간 기상자료를 효율적으로 정확도 높게 산출하며, 이는 향후 장기간 기후 추세 및 변동 분석에 중요 자료로 활용 가능하다.

• Journal of the Korean Geotechnical Society
• /
• v.22 no.12
• /
• pp.77-88
• /
• 2006

A series of model tests were performed to investigate the ground deformation during trench excavation for diaphragm walls. An apparatus was manufactured to observe the failure pattern of a slurry-supported trench in sandy ground. Ground deformations including settlement and lateral displacement of the surrounding ground adjacent to the trench were carefully monitored during excavation. Experimental observations indicated that the settlement of the adjacent ground increased with closing to the trench. Especially, the considerable settlement occurred at the distance which was equal to 40% of the excavation depth. And, the higher settlement was obtained when the relative density of ground was looser and the ground water table was higher. Also, the lateral wall face of excavated trench was bulged with lowering the slurry level In stages and then the upper part of trench failed finally. The envelope of ground surface settlement could be represented as a hyperbolic line and the measured settlement was smaller than those predicted by Clough and O'Rourke (1990).

• Journal of Korean Tunnelling and Underground Space Association
• /
• v.20 no.2
• /
• pp.423-432
• /
• 2018

Since the Daegu subway fire accident, people's perception of safety has increased, and all materials inside the train have been changed to incombustible materials. However, there is still a lack of development of fire extinguishing systems. Train components are mostly made of steel plates, and therefore it is very difficult to extinguish the train fire by using general fire extinguishing equipment. In this regard, this paper investigated rapid and easy methods of extinguishing the train fire by using compressed air foam systems through full-scale fire tests. To extinguish the fire of train at rescue station, window breakers were used to quickly destroy the train windows, and the compressed air foam system was inserted inside the train. As a result, the train windows were destroyed in 5 seconds, and the 11.88-MW fire was put out in 30 seconds by the compressed air foam discharged from the compressed air foam system inserted inside the train. For the future work, there is a need for further experimental studies to prevent the spread of fire and protect tunnel structures with the use of compressed air foam systems.

• Journal of Korean Tunnelling and Underground Space Association
• /
• v.19 no.5
• /
• pp.705-715
• /
• 2017

In this study, applicability of compressed air form (CAF) fire water was verified in a bid to use the undersea effluent as fire water. Foam collector was fabricated in accordance with KS B ISO 7203-1 (Specification for low expansion foam concentrates for top application to water-immiscible liquids) and the test was conducted using fresh water as fire water for 19 times and using seawater as fire water 15 times that totaled 34 times. Foam reduction time was 237.73 seconds on average with fresh water and 215.60 seconds with seawater, which proved the applicability of CAF fire water using seawater. Besides, window breaker was fabricated to directly extinguish the fire in train and a full-scale fire test was conducted three times. At the final 3rd test, window glass was broken in 2 seconds to make the hole for fire extinguishing and suppressed the fire in 3 seconds using CAF fire extinguisher.

• Proceedings of the Korea Water Resources Association Conference
• /
• 2018.05a
• /
• pp.71-71
• /
• 2018

Sea pollution accidents have been occurred due to the increase of marine ship traffic. Oil spill from the hull hole induced by tanker collision results in the huge sea pollution. Proper and prompt reaction on such oil spill disaster is needed to minimize the damage. Thru-hull emergency wood plug is typically used to manually close small holes, while it is required to develop some mechanical devices for closing large holes in the hull due to huge fluid pressure. Accurate estimation of oil discharge and velocity from such holes are important to develop proper device to control hull hole damage. High resolution CFD modeling investigation on the configurations of hull hole of 7.5 m initial depth and 30 cm diameter, which was observed in the oil spill accident of the Hebei Sprit off the west coast of Korea in 2007, has been carried out to compute the oil spill velocity distribution in terms of flow depth. Friction loss due to the viscous flow and the discharge coefficient of crude oil with specific gravity SG = 0.85 and viscosity of $4-12cP(mPa{\cdot}s)$ at the temperature of $20^{\circ}C-100^{\circ}C$ are presented in terms of Reynolds number based on the results of high-resolution CFD modeling.

• The Journal of the Institute of Internet, Broadcasting and Communication
• /
• v.23 no.2
• /
• pp.169-174
• /
• 2023

Currently, overall power usage is also increasing as power demand such as homes, offices, and factories increases. The increase in power use also raised interest in standby power as a change in awareness of energy saving appeared. Home and office devices are consuming power even in standby conditions. Accordingly, there is a growing need to reduce standby power, and it aims to have standby power of 1W or less. An intelligent outlet uses a near-field wireless network to connect to a home network and cut or reduce standby power of a lamp or appliance connected to an outlet. This research aims to develop a monitoring system and an intelligent outlet that can remotely monitor the amount of electricity used in a lighting lamp or a home appliance connected to an outlet using a short-range wireless network (Zigbee). Also, The intelligent outlet and monitoring system developed makes it possible for a user to easily cut off standby power by using a portable device. Intelligent outlets will not only reduce standby power but also be applicable to fire prevention systems. Devices that cut off standby power include intelligent outlets and standby power cutoff switches, so they will prevent short circuits and fires.

• The Journal of the Convergence on Culture Technology
• /
• v.5 no.3
• /
• pp.43-54
• /
• 2019

In this study, results of completion inspection are investigated according to the performance of the firefighting construction supervision personnel and according to the necessity of clean air supply in a performance test of the firefighting construction supervision personnel. The results of the completion inspection are measured and the causes of defects in the fire protection facilities after issuance of a completion inspection certificate are analyzed. The findings of this investigation can be used to minimize the risk of apartment fires and improve the performance of firefighting construction supervision personnel. The results of this study are summarized as follows. First, the results of the completion inspection conducted by the firefighting construction supervision personnel varies according to particular occupation. The performance of fire facility supervisors from design companies and fire construction companies were significantly higher than the fire officers. Therefore, it is necessary to employ supervisors who have experience in supervising the construction of apartments, in order to improve the performance of fire construction supervision officers. Second, the analysis of the completion inspection results according to the necessity of a clean air supply for performance tests of firefighting construction supervision personnel showed that the necessity of a clean air supply was significantly higher for fire facility supervisors from design companies and fire construction companies than for the fire officers. In order to improve, the completion inspection should be carried out up until the completion date of the building. In addition, a system needs to be established to ensure that clients are not able to demand that a completion inspection certificate be issued on the construction completion date. Finally, it is found that defects of completion inspection after issuance of a completion inspection certificate affects the result of the completion inspection. The results of the completion inspections conducted by the fire facility supervisors from design companies and fire construction companies were affected significantly less by defects than that of the general contractors. Research shows that faults have occured in firefighting facilities after the issuance of a completion inspection certificate due to the client and the construction company demanding the issuance of the completion inspection certificate.