• Journal of The Korean Society of Integrative Medicine
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• v.9 no.1
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• pp.109-121
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• 2021

Purpose : The first case of coronavirus disease-2019 (COVID-19) disease outbreak in Korea occurred in January 2020, and the cumulative number of confirmed cases by the Central Defense Response Headquarters of the Quality Management Administration as of November 30 was 34,201. Looking at the incidence trend of domestic confirmed cases by age, the incidence rate of COVID-19 in the age group of 20-29 years, which corresponds to college students, was 27.4 %, the highest compared by age group. Considering the current status of the infection rate, universities will become the centers of new COVID-19 cases if face-to-face lectures are recommenced without preparatory measures and analysis of infection prevention (e.g., infection awareness and education for university students). Thus, this study intended to investigate the level of knowledge, educational needs, and preventive behavior performance of college students about COVID-19 and provide basic data for the development of an education program for the prevention of COVID-19 for college students. Methods : This study is a descriptive correlational study aimed to investigate the correlation between knowledge about COVID-19, educational needs, and degree of preventive behavior performance in 407 college students attending one University in Gyeonggi-do. Results : The subjects' knowledge score about COVID-19 was 12.46±1.39 points, average educational needs score was 29.16±3.14 points, and prevention behavior performance survey result was 35.50±3.61 points. Moreover, positive correlation was observed between the knowledge about COVID-19 and educational needs (r=.203, p<.001) and knowledge and preventive behavior performance (r=.140, p=.005). Further, educational needs and preventive behavior performance demonstrated a statistically significant positive relationship (r=.311, p<.001). Conclusion : Therefore, organizing an educational program to acquire accurate knowledge is necessary to make it a habit for college students to practice preventive behavior against COVID-19.

• Journal of the Korea Society for Simulation
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• v.31 no.4
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• pp.11-22
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• 2022

Unlike a short-range, a long-range underwater acoustic communication(UWAC) uses low frequency signal and deep sound channel to minimize propagation loss. In this case, even though communication signals are modulated using a covert transmission technique such as spread spectrum, it is hard to conceal the existence of the signals. The unconcealed communication signal can be utilized as active sonar signal by enemy and presence of underwater vehicles may be exposed to the interceptor. Since it is very important to maintain stealthiness for underwater vehicles, the detection probability of friendly underwater vehicles should be considered when interceptor utilizes our long-range UWAC signal. In this paper, we modeled a long-range UWAC environment for analyzing the detection performance of underwater vehicles and proposed the region of interest(ROI) setup method and the measurement of detection performance. By computer simulations, we yielded parameters, analyzed the detection probability and the detection performance in ROI. The analysis results showed that the proposed detection performance analysis method for underwater vehicles could play an important role in the operation of long-range UWAC equipment.

• Composites Research
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• v.37 no.2
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• pp.108-114
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• 2024

Due to the continuously increasing global demand for electricity, the demand for high-voltage submarine cables is also increasing. One of the issues that need to be addressed for submarine cables is the high production cost and expensive laying costs. Submarine cables exposed to the marine environment encounter external forces such as wave and current, leading to issues such as cable damage due to external factors or high maintenance costs in the event of an accident. Therefore, we are preparing for the uncertainty of the submarine environment through many protective materials and protective equipment. In this study, we examined the bending performance of piggyback clamps (PBC) and strap, which are representative protective equipment, in response to the submarine environment through analytical methods. To examine the structural performance of PBC, the bending performance were assessed under the maximum bending moment criterion of 15 kN·m for the flexible protection tube. As a result, it was confirmed that the structural performance regarding the bending moment of both PBC and straps was ensured.

• Korean Journal of Poultry Science
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• v.39 no.3
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• pp.223-232
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• 2012

The effects of dietary supplementation of dried coffee meal (CM) on growth performance, blood biochemical profiles, the weights of immune-related organs, and the antioxidant defense system in broiler chicks were examined. A total of 162, 3-day-old male broiler chickens were assigned to three dietary groups: control group (CON), control diet added with 0.5% CM (CM0.5), and control diet added with 1.0% CM (CM1.0). In vitro antioxidant activity test, coffee extracts showed concentration-dependent increase in radical scavenging activity. Dietary addition of 0.5 and 1.0% of CM did not have negative effects on growth performance and feed conversion during the experimental periods, whereas dietary CM significantly (P<0.05) increased the relative weight of thymus without changes in the other organ weights. In addition, birds fed the diet supplemented with CM (0.5 and 1.0%) significantly increased blood albumin without affecting other components including glucose, triglyceride and cholesterol compared with those fed control diet. In antioxidant defense system, the specific activities of superoxide dismutase, glutathione peroxidase and glutathione S-transferase and the level of glutathione in the small intestine and liver were not affected by dietary supplementation of CM. However, hepatic lipid peroxidation in birds fed the diet supplemented with 0.5% CM was significantly (P<0.05) decreased compared with that in control birds. In conclusion, dietary supplementation of CM(0.5~1.0%) has potential for use as a natural antioxidant source without negative effect on growth performance in broiler chickens.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.20 no.10
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• pp.1061-1070
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• 2009

In this paper, we have designed TDL(True-time Delay Line) for eliminating beam-squint occurring in active phased array antenna with large electrical size operated in wide bandwidth, and have tested its electrical performance. The proposed TDL device is composed of 4-bit microstrip delay line structure and MMIC amplifier for compensation of the delay-line loss. The measured results of gain and phase versus delay state satisfy the electrical requirements, also P1dB output power and noise figure meet the requirement. To verify the performance of fabricated TDL, we have simulated the beam patterns of wide-band active phased array antenna using the measured results and have certified the beam pattern compensation performance. As a result of simulated beam pattern compensation with respect to the 675.8 mm size antenna which is operated in X-band, 800 MHz bandwidth, we have reduced the beam squint error of ${\pm}1^{\circ}$ with ${\pm}0.1^{\circ}$. So this TDL module is able to be applied to active phase array antenna system.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.17 no.12
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• pp.193-197
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• 2016

The performance of Precision Guided Missiles is estimated by using hit probability only, which is calculated by hits against total amounts of fires in current domestic live-fire tests. It has a limitation in judging the performance of all produced Precision Guided Missiles by using the calculated hit probability according to the result of live-fire test, because the overall characteristics of the produced Precision Guided Missiles are not considered. In other words, a method is needed to estimate the confidence level which is more reliable than simply calculated hit probability according to the result of live-fire test for guaranteeing the hit probability of Precision Guided Missiles by certain level, which is already being operated or produced. This paper introduces a method to estimate the confidence level of Precision Guided Missiles by minimum live-fire tests using Hypergeometric distribution and Bayes' rule suitable for the characteristics of Precision Guided Missiles, which are small production, high costs and unable to check whether the missile hits the target or not before the live-fire tests. Also, this paper suggests a reasonable confidence level for showing the performance of the Precision Guided Missiles using the results of live-fire tests and domestic and foreign literature, when the result of live-fire tests will be decided.

• Journal of the Korean Society of Propulsion Engineers
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• v.19 no.5
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• pp.1-14
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• 2015

In case of a gas turbine engine for supersonic operation, the engine have a wide range of operating inlet mass flow rate and required high performance such as thrust and fuel consumption. Therefore, variable system and its optimal control logic are essentially needed. In this work, a method for performance prediction of a gas turbine engine with variable system compressor and its control scheme were developed. Conceptual design of compact acuation system for the operation of the variable system was also conducted. The performance of a low-bypass ratio mixed flow turbofan engine was analyzed, and it was observed that the surge margin of the engine is improved at off-design condition by applying the control scheme.

• Journal of the Institute of Electronics and Information Engineers
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• v.50 no.6
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• pp.62-71
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• 2013

The passive emitter location method using TDOA and FDOA measurements has higher accuracy comparing to the single TDOA or FDOA based method. Moreover, it is able to estimate the velocity vector of a moving platform. Recently, several non-iterative methods were suggested using the nuisance parameter but the common reference sensor is needed for each pair of sensors. They show also relatively low performance in the case of a long range between the sensor groups and the emitter. To solve this, we derive the estimation method of the position and velocity of a moving platform based on the Gauss-Newton method. In addition, to analyze the estimation performance of the position and velocity, respectively, we decompose the CRLB matrix into each subspace. Simulation results show the estimation performance of the derived method and the CEP planes according to the given geometry of the sensors.

• Journal of the military operations research society of Korea
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• v.33 no.2
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• pp.101-113
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• 2007

The period of military personnel service will be phased down by 2014 according to 'The law of National Defense Reformation' issued by the Ministry of National Defense. For this reason, the ROK army provides discrimination education to 'newly recruited privates' for more effective individual performance in the on-the-job training. For the training to be more effective, it would be essential to predict the degree of achievements by new privates in the training. Thus, we used data mining techniques to develop a classification model which classifies the new privates into one of two achievements groups, so that different skills of education are applied to each group. The target variable for this model is a binary variable, whose value can be either 'a group of general control' or 'a group of special control'. We developed four pure classification models using Neural Network, Decision Tree, Support Vector Machine and Naive Bayesian. We also built four hybrid models, each of which combines k-means clustering algorithm with one of these four mining technique. Experimental results demonstrated that the highest performance model was the hybrid model of k-means and Neural Network. We expect that various military education programs could be supported by these classification models for better educational performance.

• Journal of the Korea Society for Simulation
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• v.29 no.3
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• pp.57-72
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• 2020

To respond to the threat of Long range artillery of North Korea, it is necessary to establish the Korean counter long range artillery intercept system(CLRAIS). The purpose of this study is to study the operational concept of the CLRAIS against the threat of long range artillery of North Korea, and to develop the operational effectiveness process of the CLRAIS. First, we set up the operating concept of the CLRAIS and established the concept of an effectiveness in a many-to-many engagement situation and a process to derive it. Based on this, a tool was developed to analyze the actual effectiveness. In order to find out the factors influencing the effectiveness in many-to-many engagement situations, simulation experiments were performed by combining various variables such as detection assets, engagement control, and launchpad performance. As a result, it was found that in addition to the missile performance, the performance of the detection assets and the engagement control center had a significant impact on the intercept rate and the defense success rate. These findings can be used to understand important indicators in terms of effectiveness in many-to-many engagement situations in the future development of weapon system, and to determine the development direction and target value of each element necessary for the level of defense success rate to be achieved.