• Journal of the Korea Institute of Military Science and Technology
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• v.25 no.3
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• pp.231-238
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• 2022

Mine detection has been mainly studied with images of the forward-looking sonar. Forward-looking sonar assumes the propagation path of the sound wave as a straight path, creating the surrounding images. This might lead to errors in the detection by ignoring the refraction of the sound wave. In this study, we propose a mine localization method that can robustly identify the location of mines in an underwater environment by considering the refraction of sound waves. We propose a method of estimating the elevation angle of arrival of the target echo signal in a single receiver, and estimate the mine location by applying the estimated elevation angle of arrival to ray tracing. As a result of simulation, the method proposed in this paper was more effective in estimating the mine localization than the existing method that assumed the propagation path as a straight line.

• The Journal of the Acoustical Society of Korea
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• v.42 no.4
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• pp.320-328
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• 2023

Underwater active target detection is vital for defense systems, requiring accurate detection and estimation of distance and velocity. Sequential transmission is necessary at each beam angle, but divided pulse length leads to range ambiguity. Multi-frequency transmission results in time-bandwidth product losses when bandwidth is divided. To overcome these problem, we propose a novel method using Generalized Sinusoidal Frequency Modulation (GSFM) for rapid target detection, enabling low-correlation pulses between subpulses without bandwidth division. The proposed method allows for rapid updates of the distance and velocity of target by employing GSFM with minimized pulse length. To evaluate our method, we simulated an underwater environment with reverberation. In the simulation, a linear frequency modulation of 0.05 s caused an average distance estimation error of 50 % and a velocity estimation error of 103 % due to limited frequency band. In contrast, GSFM accurately and quickly tracked targets with distance and velocity estimation errors of 10 % and 14 %, respectively, even with pulses of the same length. Furthermore, GSFM provided approximate azimuth information by transmitting highly orthogonal subpulses for each azimuth.

• Journal of Life Science
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• v.34 no.6
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• pp.418-425
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• 2024

Solid tumors are heterogeneous populations of multiple cell types. While the majority of the cells that comprise cancer are unable to divide, cancer stem cells have self-renewal and differentiation properties. Normal stem cell pathways that control self-renewal are overactivated in cancer stem cells, making cancer stem cells important for cancer cell expansion and progression. Dick first proposed the definition of cancer stem cells in acute myeloid leukemia, according to which cancer stem cells can be classified based on the expression of cell surface markers. Cancer stem cells maintain their potential in the tumor microenvironment. Multiple cell types in the tumor microenvironment maintain quiescent cancer stem cells and serve as regulators of cancer growth. Since current cancer treatments target proliferative cells, quiescent state cancer stem cells that are resistant to treatment increase the risk of recurrence or metastasis. Various signals of the tumor microenvironment induce changes to become a tumor-supportive environment by remodeling the vasculature and extracellular matrix. To effectively treat cancer, cancer stem cells and the tumor microenvironment must be targeted. Therefore, it is important to understand how the tumor microenvironment induces reprogramming of the immune response to promote cancer growth, immune resistance, and metastasis. In this review, we discuss the cellular and molecular mechanisms that can enhance immunosuppression in the tumor microenvironment.

• Journal of the Korea Convergence Society
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• v.10 no.1
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• pp.285-290
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• 2019

AHR regulates the expression of xenobiotics metabolizing enzymes (XMEs) as a transcription fact upon binding of ligands that are mainly aryl hydrocarbons. The role of AHR in human physiology has been intensively investigated for the past decades, however our understanding on AHR yet to be elucidated largely due to the lack of proper chemical agents. It has been demonstrated that AHR correlates to pathogenesis for some diseases in recent studies suggesting that the study on the AHR may provide a valid therapeutic target. Classical antagonists in current use are reported to be partially agonistic whereas a pure antagonist is yet to be found. In this study, phenyldiazenylaniline has been designed based on the structure of two known AHR antagonist, Resveratrol and CH223191. The derivatives of phenyldiazenylaniline have been prepared and subjected to assessment as an AHR antagonist in order to optimize the AHR antagonistic activity of the designed structure by means of convergence study of organic synthesis and molecular biology.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.30 no.6
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• pp.487-497
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• 2019

It is very difficult to detect ballistic missiles because of small cross-sections of the radar and the high maneuverability of the missiles. In addition, it is very difficult to recognize and intercept warheads because of the existence of debris and decoy with similar motion parameters in each flight phase. Therefore, feature vectors based on the maneuver, the micro-motion according to flight phase are needed, and the two types of features must be fused for the efficient recognition of ballistic warhead regardless of the flight phase. In this paper, we introduce feature vectors appropriate for each flight phase and an effective method to fuse them at the feature vector-level and classifier-level. According to the classification simulations using the radar signals predicted by the CAD models, the closer the warhead was to the final destination, the more improved was the classification performance. This was achieved by the classifier-level fusion, regardless of the flight phase in a noisy environment.

• Convergence Security Journal
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• v.23 no.3
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• pp.21-28
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• 2023

The development of information and communication technology in the 21st century has increased operational efficiency by providing hyper-connectivity and hyper-intelligence in the control systems of major infrastructure, but is also increasing security vulnerabilities, exposing it to hacking threats. Among them, the electric power system that supplies electric power essential for daily life has become a major target of cyber-attacks as a national critical infrastructure system. Recently, in order to protect these power systems, various security systems have been developed and the stability of the power systems has been maintained through practical cyber battle training. However, as cyber-attacks are combined with advanced ICT technologies such as artificial intelligence and big data, it is not easy to defend cyber-attacks that are becoming more intelligent with existing security systems. In order to defend against such intelligent cyber-attacks, it is necessary to know the types and aspects of intelligent cyber-attacks in advance. In this study, we analyzed the evolution of cyber attacks combined with advanced ICT technology.

• Journal of the Institute of Convergence Signal Processing
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• v.3 no.3
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• pp.41-46
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• 2002

We generally used electric optical sensors in order to detect and identify sea objects efficiently. However due to the limitation of view-angle, the region acquired from the sense is restricted. So it is necessary to generate panoramic image from sea images acquired from pan-tilt camera. Previous mosaicing method is not able to generate panoramic image for sea environment because intensity is similar to all region and time varying. In this paper, we proposed new algorithm for generating high-resolution panoramic image on sea environment. Proposed algorithm use single-view point model, applying mosaicing result in feature environment to in sea environment, we overcame the limitation of previous method. In the result of virtual and real experiment, we showed that proposed algorithm is efficient for generating sea panoramic image.

• Convergence Security Journal
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• v.17 no.3
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• pp.15-20
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• 2017

Cloud computing is a service that to use IT resources (software, storage, server, network) through various equipment in an Internet-enabled environment. Due to convenience, efficiency, and cost reduction, the utilization rate has increased recently. However, Cloud providers have become targets for attack Also, Abuse of cloud service is considered as the top security threat. The existing digital forensic procedures are suitable for investigations on individual terminals. In this paper, we propose a new investigation model by analyzing the vulnerable points that occur when you investigate the cloud environment with the existing digital forensic investigation procedure. The proposed investigation model adds a way to obtain account information, and can apply public cloud and private cloud together. Cloud services are also easily accessible and are likely to destroy digital evidence. Therefore, the investigation model was reinforced by adding an account access blocking step.

• Convergence Security Journal
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• v.11 no.6
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• pp.3-8
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• 2011

Advanced Persistent Threat (APT), aims a specific business or political targets, is rapidly growing due to fast technological advancement in hacking, malicious code, and social engineering techniques. One of the most important characteristics of APT is persistence. Attackers constantly collect information by remaining inside of the targets. Enterprise Security Management (EMS) system can misidentify APT as normal pattern of an access or an entry of a normal user as an attack. In order to analyze this misidentification, a new system development and a research are required. This study suggests the way of forecasting APT and the effective countermeasures against APT attacks by categorizing misidentified data in data-mining through threshold ratings. This proposed technique can improve the detection of future APT attacks by categorizing the data of long-term attack attempts.

• Convergence Security Journal
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• v.11 no.6
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• pp.53-58
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• 2011

There is increasing use of common commercial operation system and standard PCs to control industrial production systems, and cyber security threat for industrial facilities have emerged as a serious problem. Now these network connected ICS(Industrial Control Systems) stand vulnerable to the same threats that the enterprise information systems have faced and they are exposed to malicious attacks. In particular Stuxnet is a computer worm targeting a specific industrial control system, such as a gas pipeline or power plant and in theory, being able to cause physical damage. In this paper we present an overview of the general configuration and cyber security threats of a SCADA and investigate the attack tree analysis to identify and assess security vulnerabilities in SCADA for the purpose of response to cyber attacks in advance.