• Journal of the Korea Academia-Industrial cooperation Society
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• v.22 no.4
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• pp.345-352
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• 2021

The Republic of Korea Army (ROK Army) is trying to improve the effectiveness of education and training. On the other hand, there are many restrictions in actual training, limiting their practical education and training. Virtual reality technology is being used to overcome these limitations. Virtual reality technology is developing in various types, and the ROK Army needs to introduce a virtual reality training system for cost-effective education. The ROK Army mainly uses high-cost simulator-types that are similar to real equipment. Recently, a low-cost immersive-type virtual reality training system wearing an HMD is also being used. This study analyzed the cost education effectiveness of simulator-type and immersive-type virtual reality training systems in operation at the ROK Army air defense school. First, the research method used AHP to analyze the educational effects. Second, the cost was applied to the production cost of the virtual reality training system to analyze the cost-effectiveness of the education. The immersion-type was 3.4 times higher than the simulator-type in terms of cost effectiveness. These results can be used as basic data for analyzing the cost-effectiveness of a virtual reality training system.

• Clean Technology
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• v.28 no.4
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• pp.331-338
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• 2022

The objective of this study is to prepare bead-type and pellet-type Pt (1 wt%)/Kieselguhr catalysts as hydrogenation catalysts for the polycyclic aromatic hydrocarbons (PAHs) included in pyrolysis fuel oil (PFO). The optimal reaction temperature to maximize the yield of saturated cyclic hydrocarbons during the PFO-cut hydrogenation reaction in a trickle bed reactor was determined to be 250 ℃. A hydrogen/PFO-cut flow rate ratio of 1800 was found to maximize 1-ring saturated cyclic compounds. The yield of saturated cyclic compound increased as the space velocity (LHSV) of PFO-cut decreased. The difference in hydrogenation reaction performance between the pellet catalyst and the bead catalyst was negligible. However, the catalyst impregnated by Pt after molding the Kieselguhr support (AI catalyst) showed higher hydrogenation activity than the catalyst molded after Pt impregnation on the Kieselguhr powder (BI catalyst), which was a common phenomenon in both the pellet catalysts and bead catalysts. This may be due to a higher number of active sites over the AI catalyst compared to the BI catalyst. It was confirmed that the pellet catalyst prepared by the AI method had the best reaction activity of the prepared catalysts in this study. The majority of the PFO-cut hydrogenation products were cyclic hydrocarbons ranging from C₈ to C₁₅, and C₁₁ cyclic hydrocarbons had the highest distribution. It was confirmed that both a cracking reaction and hydrogenation occurred, which shifted the carbon number distribution towards light hydrocarbons.

• Journal of Aerospace System Engineering
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• v.16 no.4
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• pp.60-67
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• 2022

An Electro-Optical Tracking System (EOTS) is an electric optical system with EO/IR cameras, laser sensors, and an IMU. The EOTS calculates coordinates of targets, using attitude and acceleration measured by the IMU. In particular for an armed aircraft, the performance of the weapon system depends on how quickly and accurately it acquires the target coordinates. The IMU should be operated after alignment is complete, to meet the coordinate accuracy required by the weapon system so the initial stabilization time of the IMU should be reduced, by quickly measuring the attitude and acceleration. Alignment is the process of determining the initial attitude by resolving the attitude error of the IMU, and the IMU of mission equipment such as an airborne EOTS, uses velocity matching based on the velocity from GPS/INS for aircraft navigation. In this paper, a method is presented to improve the transfer alignment performance of the airborne EOTS, by maneuvering aircraft and the mission equipment. First, the performance factor of the alignment was identified, as a heading error through the velocity matching model and simulation results. Then acceleration maneuvers and attitude changes were necessary, to correct the error. As a result of flight tests applied to an EOTS on a OOO aircraft system, the transfer alignment performance was improved as the duration time was decreased, by more than five times when the aircraft accelerated by more than 0.2g and the EOTS was moving until 6.7deg/s.

• Industry Promotion Research
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• v.7 no.4
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• pp.53-61
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• 2022

This study is a phenomenological study on the dream insight process of intern counselors. The purpose of this study is to promote growth as a professional counselor based on the process of giving meaning to and recognizing their experiences through insight into the unconscious. Therefore, we used dream-integrated art therapy to have a process of recognizing unconscious dreams that clearly express expectations for oneself, others, and the world, and to explore this process more flexibly. The research participants selected three students enrolled in the master's and doctor's courses from among the applicants who applied through public relations and adopted the phenomenological Giorgi research method for data collection and analysis through in-depth interviews with the research participants. The main research results are as First, the intern counselors had a motive for wanting their own unconscious insight through dream-integrated art therapy and were able to gain insight into the problems revealed in their unconscious through dreams, music, and art media. Second, it was found that the intern counselors felt a deepening of concentration and comfort through recent dreams, music, and art media in common. Third, as a defense mechanism that was revealed without the combination of dream integrated art therapy, the avoidance tendency of not wanting to reveal oneself was common, but this showed a gradual decrease. Fourth, it was reported that intern counselors gained flexibility for themselves about the future growth direction had an opportunity to accept themselves, and had a plan for the future direction to become professional counselors. Therefore, it is suggested that follow-up studies using various media, studies to verify the effectiveness of the dream integration program, and various case studies are necessary.

• Journal of Internet Computing and Services
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• v.23 no.1
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• pp.135-145
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• 2022

This paper presented a method to build a predictable smart ammunition logistics system using the 4th industrial technology for ammunition logistics, which is the core functions in the field of defense and logistics. We have analyzed the current level of ammunition logistics with various perspectives such as domestic and overseas logistics policies, technology trends, ammunition logistics characteristics, the smart logistics certification measures by Ministry of Land, Infrastructure and Transport. As a result it is considered that the current ammunition logistics needs needs improvement. To improve this, we presented a direction based on the implications derived after analyzing various ongoing programs such as wired/wireless-based automation, smart ammunition depots, and logistics innovation of the army, navy, and air force that can be applied to the ammunition logistics. In order to implement a data-based smart ammunition logistics management system that can achieve innovation and efficiency of total life cycle while meeting changes in the battlefield environment, we presented 4 objectives such as "automation and modernization of field work", "3D-based storage management & improvement of issuing at war," and "data management for prediction-oriented ammunition management". it is expected that there will be benefits such as improvement of operational continuity, guarantee of ammunition reliability, budget reduction, improvement of inefficiencies such as delay, waiting, and double work, and reduction of accidents.

• Journal of Aerospace System Engineering
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• v.16 no.5
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• pp.62-69
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• 2022

EHA (Electro-Hydrostatic Actuator) is more energy efficiency than a centralized hydraulic system. In particular, the EHA used for aircraft has a redundant design in preparation for failure scenario. Also, due to the aircraft's internal space limitation, the actuator's length must be optimized. Therefore, a series configuration of double rod and single rod cylinder is advantageous. However, due to the asymmetry of the cross-sectional area of the piston, the force fighting phenomenon between the two cylinder areas occurs during redundant operation with a general control system. In this paper, the force fighting phenomenon of redundant EHA was simulated. A controller with load compensation and a force control-based position controller as a method to suppress its stimulation

• Composites Research
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• v.36 no.1
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• pp.16-24
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• 2023

This paper presents a multi-scale progressive fatigue damage model incorporating the model for interfacial debonding between fibers and matrix. The micromechanics model for the progressive interface debonding was adopted, which defined the four different interface phases: (1) perfectly bonded fibers; (2) mild imperfect interface; (3) severe imperfect interface; and (4) completely debonded fibers. As the number of cycles increases, the progressive transition from the perfectly bonded state to the completely debonded fiber state occurs. Eshelby's tensor for each imperfect state is calculated by the linear spring model for a damaged interface, and effective elastic properties are obtained using the multi-phase homogenization method. The fatigue damage evolution formulas for fiber, matrix and interface were proposed to demonstrate the fatigue behavior of CFRP laminates under cyclic loading. The material parameters for the fiber/matrix fatigue damage were characterized using the chaotic firefly algorithm. The model was implemented into the UMAT subroutine of ABAQUS, and successfully validated with flat-bar UD laminate specimens ([0]₈,[90]₈, [30]₁₆) of AS4/3501-6 graphite/epoxy composite.

• Journal of Korea Trade
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• v.27 no.3
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• pp.21-42
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• 2023

Purpose - This paper investigates the trade effect of the Korea-China Free Trade Agreement (KCFTA) which coincides with political conflicts between the two countries due to the deployment of the Terminal High Altitude Area Defense (THAAD) in Korea. The two events occurred in the same year and both are likely to affect trade between two countries but in opposite directions. Therefore, it is crucial to distinguish between the trade effects from the KCFTA event and those from the THAAD event to evaluate the true FTA effects. However, this would be difficult when using only annual data. Accordingly, ex post studies to examine the trade effects of KCFTA are lacking in trustworthiness while many ex ante studies that conjecture the positive trade effects neglect the THAAD deployment impact. This paper aims to fill that gap. Design/methodology - Given that the KCFTA and THAAD events occurred in the same year but in different months, we use the monthly data from 2000 to 2019 of Korea's exports to bracket this period. We employ the difference-in-difference (DID) method within a gravity equation specification that uses hi-dimensional fixed effects to address various endogeneity issues and seasonal effects. We identify the net impact of KCFTA ratification from these two near-simultaneous events to quantify the effects of trade liberalization between these two countries. Findings - After isolating the THAAD effects on trade, the analysis creates a positive and statistically significant coefficient estimate of the KCFTA impact. In contrast, failing to isolate the THAAD effect produced a negative and statistically significant coefficient estimate of the KCFTA impact. Our results indicate that KCFTA independently increased Korea's exports to China by 10.2%, but that this increase was fully mitigated by the THAAD event. Further, our results verify that unobserved heterogeneity and multilateral resistance are technically difficult to account for in those estimations as that rely solely upon annual data, as this type of data are inadequate to control for the potential for endogeneity. Originality/value - This paper is one of the first studies to carefully evaluate the net trade effects of the KCFTA on Korea's largest trading partner while isolating the impact of simultaneously occurred political events that may influence trade in opposing directions. Our findings indicate that the lack of prior evidence of positive trade effects of the KCFTA when using annual data may be attributed to a failure to identify the impact of each event separately. This analysis supports using the correct modeling specification to avoid misleading conclusions when evaluating any important international trade policy.

• Journal of the Society of Disaster Information
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• v.19 no.2
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• pp.270-279
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• 2023

Purpose: The purpose of this study is to examine the new drugs that recently have shown rapid increase and provide solutions to eradicate them. Method: This study used the relevant preceding studies, statistics, and overseas materials to identify the new drug problems and suggest solutions. Result: Compared to the past, the numbers of criminals detected for the administration, distribution, and production of drugs are rapidly increasing. According to the statistical data on drugs in 2021, the number of drug-related cases decreased compared to the previous year. However, there are concerns because the amount of detected drugs increased more than three times, and the age group of drugrelated criminals are getting younger. Such results are largely affected by the spread of new drugs. In particular, it is deemed to be affected by the spread of new drugs, such as fentanyl, yaba, khat, kratom, etc., as well as the new psychoactive drugs and hemp-related materials. Conclusion: In response to spread of new drugs, this study suggests simplifying the temporary classification of drugs, enforcing control of foreign drug users, strengthening the cooperation with relevant institutions, such as Korea Customs Service and the Ministry of Food and Drug Safety, and intensifying the punishment on the drug users in order to strengthen the countermeasure against the new drugs.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.36 no.2
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• pp.93-103
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• 2023

Warships widely spread numerous chaffs using a blast, which form chaff clouds that create false radar cross-sections to deceive enemy radars. In this study, we established a numerical framework based on a one-way coupling of computational fluid dynamics and discrete element method to simulate the spatiotemporal distribution of chaff clouds for warships in the air. Using the framework, we investigated the effects of wind, initial chaff cartridge angle, and blast pressure on the distribution of chaff clouds. We observed three phases for the chaff cloud diffusion: radial diffusion by the explosion, omnidirectional diffusion by turbulence and collision, and gravity-induced diffusion by the difference in the fall speed. The wind moved the average position of the chaff clouds, and the diffusion due to drag force did not occur. The direction of radial diffusion by the explosion depended on the initial angle of the cartridge, and a more vertical angle led to a wider distribution of the chaffs. As the blast pressure increased, the chaff clouds spread out more widely, but the distribution difference in the direction of gravity was not significant.