• Transactions of the Korean Society of Mechanical Engineers A
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• v.37 no.1
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• pp.25-30
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• 2013

In military vehicles moving over poor roads, severe vibration of the chassis can damage internal components. Currently, many studies have focused on active and semi-active suspensions to reduce the vibration of the chassis. In this study, a vibration reduction technique is suggested by applying a unique rotating suspension structure. SH-ADD, a type of modified Skyhook, was selected as a controller for vibration reduction. A random ISO class E road was selected as the driving road. The simulation was performed using ADAMS Control and Matlab Simulink. The control result was compared with the RMS acceleration with a focus on the cumulative fatigue of the internal equipment.

• Journal of Advanced Navigation Technology
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• v.24 no.4
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• pp.261-266
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• 2020

When a KW-class power control unit is installed in an aircraft installation, a heat dissipation design for a large amount of heat generated during power conversion should be considered. Failure to provide adequate heat dissipation can lead to equipment malfunction and fire, which can be a fatal factor in aviation operations. This paper describes the heat dissipation design of a KW-class power control unit installed in aircraft installation. The design and manufacturing test were conducted through computerized analysis, and the analysis model was corrected by confirming the rapid heat generation phenomenon of the heating element due to high power control. After the model revision, the design was improved, and the high-temperature operation test of the US military standard MIL-STD-810G was performed to confirm the feasibility of the improved design.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.12 no.12
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• pp.2307-2314
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• 2008

The study that automates the variety of equipment using the USN(Ubiquitous Sensor Networks) has been executed, and the research field is ranged to almost all fields including a road, harbors. building, military affairs, agriculture and home. By deploying these sensors into the greenhouse environment, we can monitor the environmental change and the growth of plants 24 hours a day. However, the limited resources of a sensor node like limited energy, short transmission range etc, make it difficult to expand the size of the sensor networks. In this paper, we studied to expand the site of sensor networks by using WMN(Wireless Mesh Networks) with simulation. With this simulation, we could validate that using the Wireless Mesh Networks technology for expanding sensor networks is more efficient in the energy aspect than the normal sensor network.

• Journal of the Korea Society for Simulation
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• v.25 no.4
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• pp.77-84
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• 2016

This paper proposes a methodology for creating a function based reliability prediction model. Although, there are various works for reliability prediction, one of the features of their research is that the research is based on hardware-centered reliability prediction. Reliability is often defined as the probability that a device will perform its intended function, under operating condition, for a specified period of time, there is a profound irony about reliability prediction problem. In this paper, we proposed four-phase modeling procedure for function-centered reliability prediction. The proposed modeling procedure consists of four models; 1) structure block model, 2) function block model, 3) device model, and 4) reliability prediction model. We performed function-centered reliability prediction for electronic ballast using the proposed modeling procedure and MIL-HDBK-217F which is the military handbook for reliability prediction of electronic equipment.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.31 no.6
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• pp.1261-1266
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• 2021

Existing information security risk assessment methods focus on evaluating the vulnerability of information assets. However, when the form of information assets changes and new types of information assets emerge, there is a limitation in that the evaluation standards for them are also added or deleted. Existing methods have insufficient research on the path through which cyber threats are introduced. In particular, there is very little research on blocking the inflow path for web-based information systems with public IPs. Therefore, this paper introduces the main research contents of the BDLA (Blockade and Defense Level Analysis)-based information security risk assessment model. In addition, by applying the BDLA-based information security risk assessment model, the information security risk level was studied by measuring the blockade level and security equipment level of 17 public institutions.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.43 no.4
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• pp.190-197
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• 2020

Recently there was an incident that military radars, coastal CCTVs and other surveillance equipment captured a small rubber boat smuggling a group of illegal immigrants into South Korea, but guards on duty failed to notice it until after they reached the shore and fled. After that, the detection of such vessels before it reach to the Korean shore has emerged as an important issue to be solved. In the fields of marine navigation, Automatic Identification System (AIS) is widely equipped in vessels, and the vessels incessantly transmits its position information. In this paper, we propose a method of automatically identifying abnormally behaving vessels with AIS using convolutional autoencoder (CAE). Vessel anomaly detection can be referred to as the process of detecting its trajectory that significantly deviated from the majority of the trajectories. In this method, the normal vessel trajectory is gridded as an image, and CAE are trained with images from historical normal vessel trajectories to reconstruct the input image. Features of normal trajectories are captured into weights in CAE. As a result, images of the trajectories of abnormal behaving vessels are poorly reconstructed and end up with large reconstruction errors. We show how correctly the model detects simulated abnormal trajectories shifted a few pixel from normal trajectories. Since the proposed model identifies abnormally behaving ships using actual AIS data, it is expected to contribute to the strengthening of security level when it is applied to various maritime surveillance systems.

• Journal of the Korea Society for Simulation
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• v.30 no.2
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• pp.33-40
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• 2021

The situation of high-altitude electromagnetic pulses (HEMP) arises from high-altitude nuclear explosions. The HEMP situation can be simulated through the threat level investigation (TLI). In this paper, the induced voltage according to the antenna type of the tactical mobile radio communication system was measured and analyzed by TLI. Under the influence of HEMP, electronic equipment can be paralyzed or damaged. HEMP protection filters are commercially available for power lines and signal lines. However, commercialization of HEMP filters for antennas is insufficient, and even some of them exist for lightning protection. In order to make an appropriate HEMP protection filter according to the frequency and type of the antenna, the induced voltage was measured and the maximum induced voltage was analyzed through extrapolation. It was found that the measured induced voltage decreased as the frequency increased, such as in the HF, VHF and UHF bands of the measurement results.

• Journal of East-Asian Urban History
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• v.2 no.1
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• pp.113-128
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• 2020

Right before the outbreak of the War of Resistance Against Japanese Aggression (1937-1954), the Great Eastern Broadcasting Station (GEBS) was established in Shanghai under the aegis of the Ministry of Foreign Affairs of Japan (MOFA). Prior to the launching of the GEBS, Japan had not owned similar radio stations in China for years. As a result, the Embassy of Japan in China held rounds of discussions on the plan and Japanese governments, ranging from the MOFA, the Navy, the Army, the Ministry of Communications (MOC), and NHK-Japan Broadcasting Corporation (Nihon Hoso Kyoku) provided financial, technological, and equipment support. In the mid-1930s when the Sino-Japanese relations became intensified, the GEBS assumed the primary role of disseminating government policies to over 30,000 Japanese expatriates in Shanghai to make sure that they could remain settled while supporting military endeavors of the Japanese army once the war between China and Japanese broke out. After 1937, the GEBS became an essential propaganda tool to advance imperial policies of Japan. Although the station differed from the Army-controlled Greater Shanghai Broadcasting Station (Dai Shanhai Hoso Kyoku) in many aspects, it was in line with the latter in terms of advancing wartime ideology of the Japanese empire. As the Japanese-occupied areas were enlarged, target audience of the GEBS also expanded to Chinese people and foreign nationals when Japanese, English, Russian, and Shanghai-dialect news was broadcast by the station. Suffice it to say that the GEBS was closely related to wartime propaganda of the Japanese imperial expansion.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.27 no.1
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• pp.62-68
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• 2023

An aerial relay system utilizing an unmanned aerial vehicle(UAV) or drone is addressed for event-driven operations such as temporary communication services for disaster affected area, military and first responder support. UAV relay system (URS) targets to provide a reliable communication service to a remote user equipment or an operator, therefore, a fast UAV placement to guarantee a minimum quality of service(QoS) is important when an operation is requested. Researches on UAV utilization in communication systems mostly target to derive the optimal position of UAV to maximize the performance, however, fast deployment of UAV is much more important than optimal placement under emergency situations. To this end, this paper derives the feasible area for UAV placement, investigates the effect of performance requirements on that area, and suggests UAV placement to certainly guarantee the performance requirements. Simulation results demonstrate that the feasible area derived in this paper matches that obtained by an exhaustive search.

• Journal of Advanced Navigation Technology
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• v.27 no.2
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• pp.173-181
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• 2023

Aircraft carriers need to maintain an orderly flow of aircraft in order for military ships to conduct combat through aircraft. Maintaining aircraft flow is an important factor in strengthening ship and aviation safety. In order to maintain aircraft flow, it is essential to develop a state-of-the-art air control system that provides higher quality control information by simultaneously accommodating radar-based monitoring information and monitoring information based on CNS integrated technology. Based on this point, this study describes the function and operation method of specific control equipment for the operation of the Aviation Support System and Air Traffic Control System required to operate light aircraft carriers in Korea based on overseas cases.