• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.40 no.5
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• pp.446-453
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• 2012

As part of the integration phases in developing a UAV, a System Integration Laboratory (SIL) has been developed to provide integrated test capability for the verification of avionics system requirements. The SIL has realized primary functions that are common in manned aircraft SIL's, and specialized laying stress on test data visualization and test automation under the closed-loop structure of the ground control simulation, aircraft simulation and flight simulation components. Those design results have led to easy and sure verification of lots of complex requirements of the UAV avionics system. The functions and performances of the SIL have been proved in four gradational test steps and checked to operate successfully in aircraft System Integration Test Environment for the integration of UAV ground station and aircraft.

• Journal of Korean Classical Literature and Education
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• no.15
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• pp.265-301
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• 2008

In this writing, issued beauty as Hyangga(향가) creative motivation into the focus, its expression modality is discussed and then an aesthetic sense of Sil-la is considered. For its research, in "Samkukyusa"("삼국유사") some Hyangga - , , , - that have phraseologies for beauty meaning are choose for the discuss. First, beauty as Hyangga(향가) creative motivation were expressed by above methods. 1. Beauty as desires for acquisition and confirmation in 2. Beauty that the subject (the writer) looked upon in 3. Beauty that felt pathetic for declining in 4. Beauty that arouse from disillusion in Second, an aesthetic sense of Sil-La in "Samkukyusa"("삼국유사") showed as the above. 1. Physical beauty that Sil-La were attracted by 2. Beauty as the glorified object that Sil-La were attracted by 3. Beauty as the virtue notion that Sil- La were attracted by In consequence, it is discussed that Sil-La had an aesthetic sense as the perfect virtue united the transcendence and the real.

• Proceedings of the Korean Information Science Society Conference
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• 2012.06d
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• pp.340-342
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• 2012

국제 인터넷주소 할당기관인 IANA(Internet Assigned Numbers Authority)는 2011년 2월 4일 글로벌 IPv4 주소 할당 중지를 선언하였다. 이로 인해 IPv4를 대신할 차세대 인터넷 주소체계인 IPv6로의 전환이 시급한 상황이다. 하지만 IPv4/IPv6 전환 과정에서 IPv4 네트워크와 IPv6 네트워크의 공존으로 인해 인가 되지 않은 터널링과 같은 보안 위협이 발생할 수 있다. 본 논문에서는 IPv6로의 전환을 위해 최근 새롭게 연구되고 있는 전환기술의 보안취약성 및 강화방안에 대해 논의하였다.

• Proceedings of the Korea Information Processing Society Conference
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• 2012.04a
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• pp.761-763
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• 2012

기존 IPv4 주소의 고갈로 인해 IPv6로의 주소 전환이 예상되며, 이는 IPv4 네트워크와 IPv6 네트워크의 혼재 상황을 야기시킨다. 이는 IPv4 주소체계와 IPv6 주소체계가 다르므로 주소 전환 문제와 이에 따른 보안상의 문제가 발생 할 수 있다. 이를 해결하기 위해서 NAT-PT, NAT64와 같은 변환기술이 개발되었고, 각 네트워크에서의 보안기술도 개발되었다. 그러나 기존 연구는 각 네트워크에서의 보안 취약점 분석과 보안성 강화방안을 연구하였지만, IPv4/IPv6 혼재 상황에서의 보안 취약점에 관한 연구들은 부족한 실정이다. 본 논문에서는 향후 도래할 IPv4/IPv6 네트워크 혼재 상황에서 사용될 전환 기술 중 변환 기술인 NAT-PT와 NAT64를 중심으로 보안 취약점을 분석하고, 보안성 강화방안을 제시하였다.

• Proceedings of the IEEK Conference
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• 2002.06a
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• pp.413-416
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• 2002

중앙집중식 구조의 기존 내용기반 요구분산의 문제점인 확장성 및 성능을 향상시키기 위해, 본 논문에서 는 2단계로 구성된 분산구조로 된 L4/L7 방법을 사용한다. L4 스위치를 이용하여 1차적으로 부하를 분산시키고, 이들에 대해 Proxy의 성능상의 단점을 보완한 TCP splicing을 적용하여 2차로 L7 스위치 기능을 수행하도록 한다. 리눅스 환경에서 제안한 시스템을 구현하고 클러스터형 웹서버 시스템을 구성하여 실험하였다. 제안한 분산구조 방법이 중앙집중 방식에 비해 확장성, 성능면에서 우수함을 확인하였다.

• Journal of the Korean Society of Safety
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• v.31 no.5
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• pp.141-148
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• 2016

There exists required safety integrity level (SIL) to assure safety in accordance with international standards for every electrical / electronics / control equipment or systems with safety related functions. The SIL is allocated from lowest level (level 0) to highest level (level 4). In order to guarantee certain safety level that is internationally acceptable, application of methodology for SIL allocation and demonstration based on related international standards is required. Especially, in case of the SIL allocation method without determining of quantitative tolerable risk, the additional review is needed to check whether it is suitable or not is required. In this study, the quantitative risk reduction model based on the safety integrity allocation results of railway platform screen door system using Risk Graph method has been examined in order to review the suitability of quantitative risk reduction according to allocated safety integrity level.

• Transactions of the Society of Information Storage Systems
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• v.3 no.1
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• pp.1-4
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• 2007

A high density optical data storage device has been required for many years. In the field of the optical data storage, a near-field recording (NFR) technology is considered as a next generation one for achieving the high data density. Due to an evanescent wave effect occurred under 100nm distance which is the excessively small distance between the SIL and the disc, the most significant and difficult problem in this technology is to maintain a gap between a solid immersion lens (SIL) and a disc. Also, maintaining the gap under at least 50nm is required in the NFR gap servo system to use the evanescent wave effect efficiently. There are some institutes that have shown the novel gap servo control. In general, they use a mode switching servo method which consists of approach, hand-over and gap control mode. However there is a critical problem such as an overshoot at the tuning point from the approach mode to the hand-over mode, which may cause a collision between the SIL and the disc. In this paper, we show our NFR system and an improved gap servo system using an exponential function as the approach mode which can reduce the overshoot.

• Journal of the Korean Chemical Society
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• v.43 no.4
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• pp.375-377
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• 1999

• Proceedings of the KSR Conference
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• 2010.06a
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• pp.838-849
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• 2010

It is inevitable to control the systematic failure to obtain the software safety integrity of embedded software installed in rolling stock. Because it is not possible to assess systematic failure integrity by quantitative methods, SILs are used to group documentation, methods, tools and techniques throughout software development lifecycle which, when used effectively, are considered to provide an appropriate level of confidence in the realization of a system to a stated integrity level. Normally, safety approval process is through generic product, generic application and specification application for. For safety approval on generic application of software based system, it is required to apply the certified software processes from the planning stage for the assigned SIL. As such, we will develop project specific application with high safety integrity within time limit of contractual delivery schedule through software assessment to the modified area with the re-use of certified software module and documentation. At this point, Hyundai Rotem has developed software processes applicable to support SIL 4 based on EN50128 which was assessed and certified by TUV SUD. This paper introduces the Hyundai Rotem's detailed approach and prospective action to achieve software safety integrity level.

• Journal of the Korean Society of Safety
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• v.32 no.4
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• pp.7-15
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• 2017

International standards such as IEC-61508 and IEC-61511 require Safety Integrity Levels (SILs) for Safety Instrumented Functions (SIFs) in process industries. SIL verification is one of the methods for process safety description. Results of the SIL verification in some cases indicated that several Safety Instrumented Functions (SIFs) do not satisfy the required SIL. This results in some problems in terms of cost and risks to the industries. This study has been performed to improve the reliability of a safety instrumented function (SIF) installed in hydrodesulfurization reactor heater using Partial Stroke Testing (PST). Emergency shutdown system was chosen as an SIF in this study. SIL verification has been performed for cases chosen through the layer of protection analysis method. The probability of failure on demands (PFDs) for SIFs in fault tree analysis was $4.82{\times}10^{-3}$. As a result, the SIFs were unsuitable for the needed RRF, although they were capable of satisfying their target SIL 2. So, different PST intervals from 1 to 4 years were applied to the SIFs. It was found that the PFD of SIFs was $2.13{\times}10^{-3}$ and the RRF was 469 at the PST interval of one year, and this satisfies the RRF requirements in this case. It was also found that shorter interval of PST caused higher reliability of the SIF.