• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• 2023.11a
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• pp.95-97
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• 2023

자율운항선박(MASS)의 원격제어기술은 원격지에서 MASS를 원격제어자에 의해서 제어하기 위한 기술이다. 2023년도 현재 원격제어시스템의 통합구성이 완료되었고, 하반기부터는 해상실험을 통한 시스템 검증작업을 진행할 예정이다. 이러한 시스템 검증 이후에는 원격제어 시 발생할 수 있는 다양한 문제에 적극 대응할 수 있는 위기관리 기술의 개발이 필요하다. 현재 식별된 위기는 통신 두절에 따른 제어 불능, 간헐적 통신 불능에 따른 데이터 손실, 대용량 데이터 전송에 따른 제어명령과 제어응답 사이의 지연에 의한 선박조종의 어려움, 원격제어자의 인적오류에 의한 예상하지 못한 해양사고발생 가능성 등이다. 본 연구의 목적은 4가지 주요 요소(선박, 통신, 제어시스템, 원격 제어자)로 구성된 원격제어 시스템에서 발생 가능한 다양한 위기를 적극 억제할 수 있는 기법개발을 고찰하여 향후 원격제어기술 연구에 적용하기 위한 것이다. 특히, 통신 두절로 인한 암흑시간(blind time) 동안 원격제어 불능을 해결할 수 있는 위기대응 방법, 과도한 데이터 전송지연에 따른 위험수준 평가와 가시화 방법 등을 논의한다. 본 연구는 자율운항선박의 원격제어를 안전하게 지속가능한 상태에서 운영할 수 있는 기법의 적용할 수 있을 것으로 기대된다.

• Proceedings of the Korean Society of Computer Information Conference
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• 2024.01a
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• pp.113-115
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• 2024

최근 개발되는 드론은 사용자의 편의를 위하여, 사진이나 동영상과 같은 파일을 휴대 기기로 전송하거나 휴대 기기로 드론을 조종하는 것과 같은 휴대 기기를 통한 다양한 기능들을 제공하며, 이러한 기능들은 와이파이를 기반으로 이루어진다. 그러나, 와이파이는 인증 해제 공격이나 Evil Twin 공격과 같은 취약점이 존재하며, 이러한 취약점으로 인하여 드론에서 제공하는 다양한 기능들과 관련된 보안 위협이 발생할 가능성이 존재한다. 따라서, 본 논문에서는 와이파이를 사용하는 드론에서 발생 가능한 취약점을 미리 분석하고 방어하기 위한 목적으로, 와이파이에서 발생 가능한 취약점 중 하나인 패스워드 크래킹 취약점을 분석하였다. 실험 결과, 드론에서 제공하는 와이파이의 패스워드를 크래킹함으로써 공격자가 드론 네트워크 내부로 진입이 가능한 것을 실증하였다. 향후, 드론 환경에서 패스워드 크래킹 뿐만 아니라, 와이파이에서 발생 가능한 다양한 취약점을 분석하고 실증할 예정이다.

• Journal of Sericultural and Entomological Science
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• v.47 no.1
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• pp.36-40
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• 2005

This studies were carried out to develop the new silk degumming method by elelectrolyzed alkaline water on the silk degumming process. Using to this method, it could be collect pure sericin from the degumming water, because the degumming water by elelectrolyzed alkaline water was not contaminated by chemicals including soap. The range of elelectrolyzed alkaline water was pH 11.5 to 11.7 and maintained the first value for 8 days under the cool and closed conditions. The degumming ratio of silk was higher in elelectrolyzed alkaline water(pH 11.5~11.7)than that of soap and alkaline bath. When the pH value of elelectrolyzed alkaline water was adjusted at pH 11.0, the degumming ratio of silk was similar to that of soap and alkaline degumming. After degumming the pH value of degumming water decreased largely in the elelectrolyzed alkaline water compared to that of soap and alkaline bath. The tenacity and elongation of degummed silk by elelectrolyzed alkaline water was almost same those of soap and alkaline degumming for 90 min.

• KEPCO Journal on Electric Power and Energy
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• v.4 no.2
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• pp.115-123
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• 2018

Various types of robots running on power transmission lines have been developed for the purpose of line patrol monitoring. They usually have complex mechanism to run and avoid obstacles on the power line, but nevertheless did not show satisfactory performance for going over the obstacles. Moreover, they were so heavy that they could not be easily installed on the lines. To compensate these problems, flying robots have been developed and recently, multi-copter drones with flight stability have been used in the electric power industry. The drones could be remotely controlled by human operators to monitor power distribution lines. In the case of transmission line patrol, however, transmission towers are huge and their spans are very long, and thus, it is very difficult for the pilot to control the patrol drones with the naked eye from a long distance away. This means that the risk of a drone crash onto electric power facilities always resides. In addition, there exists another danger of electromagnetic interference with the drones on autopilot waypoint tracking under ultra-high voltage environments. This paper presents a patrol monitoring plan of autopilot drones for power transmission lines and its field tests. First, the magnetic field effect on an autopilot patrol drone is investigated. Then, how to build the flight path to avoid the magnetic interference is proposed and our autopilot drone system is introduced. Finally, the effectiveness of the proposed patrol plan is confirmed through its field test results in the 154 kV, 345 kV and 765 kV transmission lines in Chungcheongnam-do.

• Journal of the Korean Society of Propulsion Engineers
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• v.18 no.1
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• pp.33-41
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• 2014

In a supersonic turbine, A rotor overlap technique reduced the chance of chocking in the rotor passage, and made the design pressure ratio satisfied. However, the technique also made additional losses, like a pumping loss, expansion loss, etc. Therefore, an approximate optimization technique was appled to find the optimal shape of overlap which maximizes the improvement of the turbine performance. The design variables were shape factors of a rotor overlap. An optimal design for rotor overlap reduces leakage mass flow rate at tip clearance by about 50% and increases about 4% of total-static efficiency compared with the base model. It was found that the most effective design variable is the tip overlap and that the hub overlap size is the lowest.

• Journal of Haehwa Medicine
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• v.21 no.1
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• pp.87-96
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• 2012

Aim : Natural killer (NK) cells are cytotoxic lymphocytes that lyse certain tumor- and virus-infected cells without any prior stimulation or immunization. This article aims to review the significance of evaluating peripheral blood NK cells to predict anti-tumor immune function and prognosis in cancer patients. Methods : PubMed was used to create a database for this review. Search words of cancer, natural killer cell, prognosis were used to retrieve related articles. References of the collected articles were also reviewed. Results : Current evidence indicates that decreased or absent NK cell count or activity is mostly associated with the development or progression of cancer. In patients with various types of cancer, NK cell activity was mostly associated with the cancer prognosis and survival despite some conflicting results. Conclusion : The data shows the evaluation of anti-tumor immunity in cancer patients through natural killer cell measurement still remains a controversial matter. However, it is clear that the NK cell activity plays an important role in cancer and is associated with prevention of both early stage and metastatic cancer.

• Journal of the Institute of Electronics and Information Engineers
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• v.50 no.12
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• pp.129-137
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• 2013

As the usage of computer based systems continues to increase in our normal life, there are constant efforts to enhance the accessibility of information for handicapped people. For this, it is essential to develop new interface ways for physical disabled peoples by means of human-computer interface (HCI) or human-machine interface (HMI). In this paper, we developed HMI using electromyogram (EMG) and electrooculogram (EOG) for people with physical disabilities. Developed system is composed of two modules, hardware module for signal sensing and software module for feature extraction and pattern classification. To maximize ease of use, only two skin contact electrodes are attached on both ends of brow, and EOG and EMG are measured simultaneously through these two electrodes. From measured signal, nine kinds of command patterns are extracted and defined using signal processing and pattern classification method. Through Java based real-time monitoring program, developed system showed 92.52% of command recognition rate. In addition, to show the capability of the developed system on real applications, five different types of commands are used to control ER1 robot. The results show that developed system can be applied to disabled person with quadriplegia as a novel interface way.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.34 no.8
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• pp.41-46
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• 2006

The capability for reconstructing impact forces of an aircraft wing using impact response functions and regularization methods were examined. The impact response function which expresses the relation between the structure response and the impact force was derived using the information on mass and stiffness data of a finite element model for the wing. Iterative Tikhonov regularization method and generalized singular value decomposition method were used to inverse the impact response function that was generally ill-posed. For the numerical verification, a fighter aircraft wing was used. Strain and deflection histories obtained from finite element analysis were compared with the results calculated using impact response functions. And the impact forces were reconstructed with the strain histories obtained from finite element analysis. The numerical verification results showed that this method can be used to monitor impact forces on aircraft structures.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.34 no.1
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• pp.56-64
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• 2006

This paper presents the development and application of a conducting shape memory polyurethane (CSMPU) actuator. While conventional shape memory polyurethanes were activated by external heat source, conducting shape memory polyurethanes introduced in 2004 are activated by electric power. Conducting shape memory polyurethane actuators were manufactured by adding carbon nano tube to conventional shape memory polyurethane. The main problem of the CSMPU developed in 2004 was bad dispersion of carbon nano tubes. In this paper, we tried to find how to solve the dispersion problem, and with a lot of elaborative works, conducting shape memory polyurethane actuators which had better electrical characteristics were developed. Then the actuation performance of the conducting shape memory polyurethane actuators was also measured and assessed. Finally, the possibility of applications were examined through the installation to Micro Air Vehicle.

• Microbiology and Biotechnology Letters
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• v.26 no.4
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• pp.345-351
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• 1998

In an effort to develop a potent system for the production of various dp (degree of polymerization) chitooligosaccharides, 32 enzymes or microbial systems were screened for chitosanolytic acitivity using chitosan as a substrate. The efficiency of each enzyme system was evaluated by the changes of turbidity and viscosity of chitosan solution, the amount of precipitate and the reducing sugar-producing activity in the enzymatic reaction mixture. Based on these assay methods for the chitosanase activity, Bacillus sp. P2l out of 32 screened systems showed highly potent endochitosanase, which was comparable with a commercially available enzyme (E7). Chitooligosaccharides of dp 3-7 were separated by TLC as major enzymatic reaction products, suggesting that the chitosanase from Bacillus sp. P2l be endo-splitting type.