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Rationalization of Network Segregation for Continuity of Financial Services Following COVID-19
( Manyong Choi ),( Jin Kwak ) 한국인터넷정보학회 2021 KSII Transactions on Internet and Information Syst Vol.15 No.11
As measures for protecting users and ensuring security of electronic financial transactions, such as online banking, financial institutions in South Korea have implemented network segregation policies. However, a revision of such domain-centered standardized network segregation policies has been increasingly requested because of: 1) increased demand for remote work due to changes resulting from COVID-19 pandemic; and 2) the difficulty of applying new technologies of fintech companies based on information and communications technologies (ICTs) such as cloud services. Therefore, in this study, problems of the remote work environment arising from the network segregation policy currently applied to the financial sector in South Korea and those from the application of new ICTs such as fintech technology have been investigated. In addition, internal network protection policies of foreign financial sectors, such as those of the United States, United Kingdom, European Union, and Russia, and internal network protection policies of non-financial sectors, such as control systems, have been analyzed. As measures for the effective improvement of the current network segregation policy, we propose a policy change from domain-based to data-centric network segregation. Furthermore, to resolve threats of hacking at remote work, recently emerging as a global problem due to COVID-19 pandemic, a standard model for remote work system development applicable to financial companies and a reinforced terminal security model are presented, and an alternative control method applicable when network segregation is not applied is proposed.
A Method to Simulate Frictional Heating at Defects in Ultrasonic Infrared Thermography
Choi, Wonjae,Choi, Manyong,Park, Jeonghak The Korean Society for Nondestructive Testing 2015 한국비파괴검사학회지 Vol.35 No.6
Ultrasonic infrared thermography is an active thermography methods. In this method, mechanical energy is introduced to a structure, it is converted into heat energy at the defects, and an infrared camera detects the heat for inspection. The heat generation mechanisms are dependent on many factors such as structure characteristics, defect type, excitation method and contact condition, which make it difficult to predict heat distribution in ultrasonic infrared thermography. In this paper, a method to simulate frictional heating, known to be one of the main heat generation mechanisms at the closed defects in metal structures, is proposed for ultrasonic infrared thermography. This method uses linear vibration analysis results without considering the contact boundary condition at the defect so that it is intuitive and simple to implement. Its advantages and disadvantages are also discussed. The simulation results show good agreement with the modal analysis and experiment result.
위상잠금 초음파 적외선열화상에 의한 겹치기 마찰교반용접부의 결함 평가
최만용(Manyong Choi),박희상(Heesang Park),박정학(Jeonghak Park),강기수(Kisoo Kang) 한국비파괴검사학회 2010 한국비파괴검사학회지 Vol.30 No.2
겹치기 마찰교반용접은 새로운 고상접합법이다. 알루미늄 합금 6061-T6는 좋은 내식성과 중량 대비 높은 기계적 강도로 인해 넓은 분야에서 경량부재로 사용되고 있다. 본 논문에서 사용한 검사 방법인 위상잠금 초음파 적외선열화상기법은 넓은 면적을 동시에 검사할 수 있으며, 결함부와 건전부 사이의 위상차로부터 결함의 유무를 판단할 수 있다. 본고의 연구로부터, 위상잠금 적외선열화상기술을 이용하여 용접부의 열영상을 검출하여 기계적 강도와 비교 평가하였다. Lap joint friction stir welding(LFSW) is an relatively new solid state joining process. A6061-T6 aluminium alloy has gathered wide acceptance in the fabrication of light weight structures requiring a high strength to weight ratio and good corrosion resistance. Test methods used in this paper, lock-in thermography, a phase difference between the defect area and the healthy area indicates the qualitative location and size of the defect. In this paper, the defects detected from the thermal image of mechanical properties for weld were evaluated and compared by the lock-in infrared thermography technique.
초음파-적외선 열화상 기법에 의한 피로균열 검출에 있어 발열 메커니즘 분석
최만용(Manyong Choi),이승석(Seungseok Lee),박정학(Jeonghak Park),김원태(Wontae Kim),강기수(Kisoo Kang) 한국비파괴검사학회 2009 한국비파괴검사학회지 Vol.29 No.1
초음파 적외선 비파괴 열화상 검사기술의 발열 메커니즘은 정확히 규명되지 않았으나, 열-기계 연성효과와 결함 계면 사이의 마찰효과가 주요한 원인인 것으로 추정되고 있다. 본 논문에서는 피로균열을 갖는 알루미늄 합금 시험편에서 결함을 검출하고, 실험조건으로부터 각각의 메커니즘에 따라 온도 변화를 수치 예측하였다. 시험결과와 수치예측 결과로부터 발열의 주요한 원인이 마찰이라는 것을 밝혔다. Heat generation mechanism of ultrasound infrared thermography is still not well understood, yet and there are two reliable assumptions of heat generation, friction and thermo-mechanical effect. This paper investigates the principal cause of heat generation at fatigue crack with experimental and numerical approach. Our results show most of heat generation is contributed by friction between crack interface and thermo-mechanical effect is a negligible quantity.
A Method to Simulate Frictional Heating at Defects in Ultrasonic Infrared Thermography
Wonjae Choi,Manyong Choi,Jeonghak Park 한국비파괴검사학회 2015 한국비파괴검사학회지 Vol.35 No.6
Ultrasonic infrared thermography is an active thermography methods. In this method, mechanical energy is introduced to a structure, it is converted into heat energy at the defects, and an infrared camera detects the heat for inspection. The heat generation mechanisms are dependent on many factors such as structure characteristics, defect type, excitation method and contact condition, which make it difficult to predict heat distribution in ultrasonic infrared thermography. In this paper, a method to simulate frictional heating, known to be one of the main heat generation mechanisms at the closed defects in metal structures, is proposed for ultrasonic infrared thermography. This method uses linear vibration analysis results without considering the contact boundary condition at the defect so that it is intuitive and simple to implement. Its advantages and disadvantages are also discussed. The simulation results show good agreement with the modal analysis and experiment result.
A STUDY ON CULTURE CONTENT EXPRESSION WITH SYMBOLISM OF FOLK PAINTING
Soojung Choi,Kim Cheeyong,Manyong Song,Chongki Kim 한국멀티미디어학회 2007 한국멀티미디어학회 국제학술대회 Vol.2007 No.-
Recently content of Korean traditional designs is increasing. Also, folk painting subjects are being reorganized into modern graphics. The cultural content becomes visual language that provides visual information to anyone, anywhere, and anytime in an easy way. The visual language binds the world as a cultural network. The study here analyzed symbols, structures and colors of content components of 'Yeonhwado (蓮花圖, drawing of lotus flowers)' in order to suggest various expressions of folk paintings. Based on the analysis, case studies of 2D, 3D and VR content production were conducted. A Yeonhwado clock was manufactured with 2D content by connecting it to time data of a computer based on the most frequently appearing subjects in Yeonhwado, In addition, 3D content was produced as a video that can be seen anywhere in our ordinary life based on subjects and colors of Yeonhwado. Finally, VR content was expressed as a visual space where people can interact with Yeonhwado by entering into, touching and experiencing it. Like this, the study provides a starting point of Yeonhwado as content by drawing upon its visual symbolic elements.
Infrared Thermography Characterization of Defects in Seamless Pipes Using an Infrared Reflector
Heesang Park,Manyong Choi,Jeonghak Park,Jeajung Lee,Wontae Kim,Boyoung Lee 한국비파괴검사학회 2012 한국비파괴검사학회지 Vol.32 No.3
Infrared thermography uses infrared energy radiated from any objects above absolute zero temperature, and the range of its application has been constantly broadened. As one of the active test techniques detecting radiant energy generated when energy is applied to an object, ultrasound infrared thermography is a method of detecting defects through hot spots occurring at a defect area when 15~100 kHz of ultrasound is excited to an object. This technique is effective in detecting a wide range affected by ultrasound and vibration in real time. Especially, it is really effective when a defect area is minute. Therefore, this study conducted thermography through lock-in signal processing when an actual defect exists inside the austenite STS304 seamless pipe, which simulates thermal fatigue cracks in a nuclear power plant pipe. With ultrasound excited, this study could detect defects on the rear of a pipe by using an aluminium reflector. Besides, by regulating the angle of the aluminium reflector, this study could detect both front and rear defects as a single infrared thermography image.
금속재료 시편의 결함평가에 대한 전단위상 Lock-in 적외선열화상 연구
박정학(Jeonghak Park),최만용(Manyong Choi),김원태(Wontae Kim) 한국비파괴검사학회 2010 한국비파괴검사학회지 Vol.30 No.2
본 연구는 전단위상 위상잠금 적외선열화상기술을 이용한 금속재료 시편의 내부결함을 평가하는 방법에 대한 연구 결과이다. 특히, STS304와 Cu-Zn 시편에 대한 비파괴시험 및 평가는 종래에는 적정한 실험 조건하에서 주로 시행됨에 따라 결항의 형태나 존재를 알 수 없는 상황에서는 최적실험조건을 찾는 일은 오랜 시간이 걸리는 단점이 있었다. 본 연구에서는 위상잠금방볍과 전단위상검출방법을 활용하여 60 MHz 신호로 설정된 가열 조건에서 결함의 위치 및 크기를 평가하였다. 전단위상분포는 시편 내부결함의 크기와 위치를 정량적으로 결정하기 위하여 최대, 최소, 영점을 이용하는 방법이다. 연구 결과로써 인공결함을 갖는 STS 304와 Cu7-Zn3 시험편에 대하여 제안된 기법의 적용을 검증하였으며, 결함평가에 영향을 주는 인자를 추출하고 그 영향을 분석하였다. This paper proposes method to evaluate the location and size of the internal defects of metallic specimens by the shearing phase lock-in infrared thermography. Until now, infrared thermography test for metal specimen of STS304 and Cu-Zn were conducted to find the best test conditions. However, In unspecified situation of the form and existence of defects, there was a disadvantage to takes a long time for finding the optimal experimental conditions. The defect detection and evaluation was performed at 60 MHz signal using lock-in and shearing-phase method under limited heating conditions. By shearing-phase distribution method, Defects for the maximum, minimum and zero points were quantitatively detected at the size and location of the subsurface. As results, application of the proposed technique was verified for STS304 and Cu7-Zn3 with artificial defect and factors affected defect evaluation were searched and analyzed.