• Journal of the Korean Society of Visualization
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• v.19 no.1
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• pp.81-87
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• 2021

Extensional flow of viscoelastic fluids is widely utilized in various industrial processes such as electrospinning, 3D printing and plastic injection molding. Extensional rheological properties, such as apparent viscosity and relaxation time, play an important role in the design and evaluation of the viscoelastic fluid-involved processes. In this work, we propose a lab-built capillary breakup extensional rheometer (CaBER) based on flow image processing to investigate the capillary breakup of polyethylene oxide (PEO) solution and its extensional rheological properties. We found that the apparent extensional viscosity and extensional relaxation time of the PEO solution are independent of the strike time. The proposed CaBER is expected to be applied to characterization of the extensional rheological properties of viscoelastic fluids at low cost with high precision.

• Journal of the military operations research society of Korea
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• v.36 no.2
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• pp.11-24
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• 2010

Quick precision-strike capability of the artillery will be an important factor in modern and future war and it's represented by NCW and EBO. This study is based on artillery which has time limitation of firing, such as artillery which hides when not firing, and modeling various situations to decide firing order and who to shoot. The main purpose of this study is to suggest a mathematical programming model and a genetic algorithm which satisfies the limitation of firing time. The objective function is to minimize the total firing time to spend. The results of the suggested algorithm quickly gives a best solution for a large scale field artillery targeting problems.

• Journal of Positioning, Navigation, and Timing
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• v.4 no.1
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• pp.9-16
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• 2015

The applications of Global Navigation Satellite System (GNSS) receivers are becoming wider in various commercial and military systems including even small weapon systems such as artillery shells. The precision-guided munitions such as Small Diameter Bomb (SDB) of United States can be used for pinpoint strike by acquiring and tracking GNSS signals in high mobility situation. In this paper, a small GNSS receiver with embedded interference suppression capability working under high dynamic stress is developed which is applicable to the various weapon systems and can be used in other several harsh environments. It applies a kind of matched filter and multiple correlator schemes for fast signal acquisition and tracking of even weak signals and frequency domain signal processing method to eliminate the narrowband interference. To evaluate the performance of the developed GNSS receiver, the test scenario of high mobility and interference environment with the GNSS simulator and signal generator is devised. Then, the signal acquisition time, navigation accuracy, sensitivity, and interference suppression performances under high dynamic operation are evaluated. And the comparison test with the commercial GNSS receiver which has high sensitivity is made under the same test condition.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.50 no.4
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• pp.233-240
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• 2022

The smart weapon system is a new weapon system of the future battlefield environment as a miniature guided weapon that performs precision strike missions through terminal phase guidance. However, it has small coverage to guide due to its low maneuverability because the smart weapon is controlled by using actuator of piezoelectric drive type due to the structural limitations. In this paper, we propose a firing data calculation algorithm under non-standard conditions to increase the effectiveness of the smart weapon. The proposed algorithm calculates firing data under non-standard conditions by calibrating firing data under standard conditions using information acquired in battlefield environments. The performance of the proposed algorithm is verified by numerical simulations under various conditions.

• Journal of the Korean Society for Precision Engineering
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• v.27 no.2
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• pp.145-152
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• 2010

Gait phase detection is important for evaluating the recovery of gait ability in patients with paralysis, and for determining the stimulation timing in FES walking. In this study, three different motion sensors(tilt sensor, gyrosensor and accelerometer) were used to detect gait events(heel strike, HS; toe off, TO) and they were compared one another to determine the most applicable sensor for gait phase detection. Motion sensors were attached on the shank and heel of subjects. Gait phases determined by the characteristics of each sensor's signal were compared with those from FVA. Gait phase detections using three different motion sensors were valid, since they all have reliabilities more than 95%, when compared with FVA. HS and TO were determined by both FVA and motion sensor signals, and the accuracy of detecting HS and TO with motion sensors were assessed by the time differences between FVA and motion sensors. Results show of that the tilt sensor and the gyrosensor could detect gait phase more accurately in normal subjects. Vertical acceleration from the accelerometer could detect HS most accurately in hemiplegic patient group A. The gyrosensor could detect HS and TO most accurately in hemiplegic patient group A and B. Valid error ranges of HS and TO were determined by 3.9 % and 13.6 % in normal subjects, respectively. The detection of TO from all sensor signals was valid in both patient group A and B. However, the vertical acceleration detected HS validly in patient group A and the gyrosensor detected HS validly in patient group B. We could determine the most applicable motion sensors to detect gait phases in hemiplegic patients. However, since hemiplegic patients have much different gait patterns one another, further experimental studies using various simple motion sensors would be required to determine gait events in pathologic gaits.

• Journal of the Korea Society for Simulation
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• v.25 no.2
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• pp.41-49
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• 2016

Counter Fire Operations can be characterized as having a system of systems that key features include situational awareness, command and control systems and highly responsive strike achieved by precision weapons. Current modeling methodology cannot provide an appropriate methodology for a system of systems and utilizes modeling and simulation tools to implement analytic options which can be time consuming and expensive. We explain developing methodology and tools for the effectiveness analysis of the counter fire operations under Network Centric Warfare Environment and suggest how to support a efficient decision making with the methodology and tools. Theater Counter Fire Operations tools consist of Enemy block, ISR block, C2 block and Shooter block. For the convenience of using by domain expert or non simulation expert, it is composed of the environments that each parameter and algorithm easily can be altered by user.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.50 no.5
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• pp.359-365
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• 2022

Air-to-ground missile(AGM), which can be operated by being mounted on the outside of the aircraft, is capable of precision strikes, ensuring high survivability. Helicopter, which is one of the AGM operating platforms, is reported to experience a lightning strike once between 1000 and 20000 flight hours in average. When the lightning strikes the helicopter fuselage, lightning transient signal can be induced to internal and external electronic equipment cables through the skin of the helicopter. If the transient signal exceeding the criteria to electrically initiated device(EID) related to the explosive in the AGM can affect the safety of the helicopter by a warhead explosion, etc. In this paper, we suggest an indirect lightning test method to prove the safety of AGM on helicopter, and present the indirect lightning test results.

• Journal of Advanced Navigation Technology
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• v.26 no.5
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• pp.312-318
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• 2022

Currently, the Republic of Korea is facing the problem of a decrease in military service resources due to the demographic cliff, and is pursuing military restructuring and changes in the military force structure in order to respond to this. In this situation, the Army is pushing forward the deployment of a drone-bot combat system that will lead the future battlefield. The battlefield of the future will be changed into an integrated battlefield concept that combines command and control, surveillance and reconnaissance, and precision strike. According to these changes, unmanned combat system, including dronebots, will be widely applied to combat situations that are high risk and difficult for humans to perform in actual combat. In this paper, as one of the countermeasures to these changes, autonomous behavior software with a BDI architecture-based decision-making system was developed. The autonomous behavior software applied a framework structure to improve applicability to multiple models. Its function was verified in a PC-based environment by assuming that the target UAV is a battalion-level surveillance and reconnaissance UAV.

• The Journal of the Convergence on Culture Technology
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• v.9 no.3
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• pp.263-270
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• 2023

The Ukraine-Russia war is a testing ground for High-Tech weapons and the first full-scale drone warfare. The Ukrainian military has been aggressively deploying a variety of reconnaissance and attack drones on the battlefield, and more recently, FPV drones, also known as racing drones, have been fitted with bombs as a game-changer in small-unit combat. To better understand these FPV drones, this article reviews their definition, aircraft components, and key characteristics, and draws implications from the Ukrainian military's FPV combat experience. In the future, the combination of artificial intelligence and swarming technology will make FPV drones even more lethal. Accordingly, the need to develop FPV drones suitable for the future operational environment on the Korean Peninsula is increasing, and follow-up research is needed to specify fighting methods and optimize related technologies.

• Strategy21
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• s.31
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• pp.85-119
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• 2013

This paper asks whether the Republic of Korea (ROK) Navy should continue to focus on building ocean-going naval ships when it faces the threats of North Korean provocations in littoral areas. My position is that the ROK Navy should keep pursuing ocean-going capabilities. I provide explanations why it should do so from the perspectives of three important dimensions: capability, doctrine, and organizational identity. First, I argue that the distinction between a littoral navy and an ocean-going navy is an unnecessary dichotomy. It may lead to inefficiency in national security. The military posture should be designed in a way that it can address all external threats to national security regardless of whether they are from North Korea or not. Such capability is the one that the ROK Navy has tried to acquire with the 'Blue Water Navy' initiative since the 1990s. Second, also from the perspective of lately developed military doctrines that emphasize jointness and precision strike capability, ocean-going capabilities such as the mobile task fleet program have become a must, not an option, given today's security situations on and around the Korean peninsula. Lastly, I draw attention to the fact that the 'Blue Water Navy (BWN)' initiative meant more than just capability to the ROK navy. The BWN represents the ROK navy's organizational identity that the navy has defined since the 1980s as it emphasized promoting national interest and international standing as part of its organizational essence. Furthermore, the phrase 'blue water navy' took on symbolic meanings to the people that are associated with South Korean-ness including sovereignty, national pride, standing in the world and hopes for the future. Since 1990s, many scholars and experts have made the case for the necessity of improving South Korea's naval capability based on different rationales. They emphasized the protection of Sea Lines of Communication (SLOCs), the economic value of the sea, the potential danger associated with territorial disputes over islands, and increasing naval power of neighboring countries since the end of the Cold War. This paper adds to this debate by trying to explain the matter with different factors including naval doctrines and organizational identity. Particularly, this paper constitutes a unique endeavor in that it incorporating constructivist elements (that is, identity politics) in explaining a national security matter.