• Proceedings of the Korean Information Science Society Conference
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• 2004.10c
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• pp.316-318
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• 2004

유선, 무선을 합하여 초고속 네트워크의 사용이 급격하게 증가됨에 따라 고속의 네트워크 통신 서비스에 대한 요구가 증가 하였으며 차별화된 인터넷 서비스에 대한 요구가 증가함에 따라 IP 기반의 스위치가 등장하게 되었다. 이러한 스위치의 이슈는 IT 포워딩, 고속 스위치 패브릭 등의 문제를 포함하게 된다. 현재까지의 모든 패킷 스위치는 그 내부적으로 HOL블로킹에 의한 성능 저하의 영향을 최소화하기 위하여 여러 가지 스케줄링 알고리즘을 사용한다. 본 논문에서는 Gigabit 으로 동작하는 패킷 스위치 중에서 Strict Priority 알고리즘, Round Robin 알고리즘을 분석하고 각각의 스케줄러가 COS 기반과 어떤 관계가 있으며 더불어 COS 기반에 따라, 스케줄러를 동적으로 변경하여 기존의 Static 하게 정책적으로 사용되던Algorithm 과의 차별성을 두어 동적 스케줄러의 선택에 의한 Packet 처리 성능향상을 보이도록 한다.

• Proceedings of the Korea Information Processing Society Conference
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• 2016.04a
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• pp.972-974
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• 2016

최근 전 세계적으로 IoT(Internet of Things) 기술이 활발히 연구되고 있다. IoT 환경은 임베디드나 센서 등의 시스템에 적용되는 경우가 많다. 그 특성으로 인해, 적용된 장치들은 경량화되기 때문에 통신을 위한 프로토콜로 UDP 기반 프로토콜을 많이 사용한다. UDP 기반 프로토콜은 TCP 기반 프로토콜보다 보안 기능이 미비하므로 UDP 상에서도 보안 기능을 제공해 줄 수 있는 DTLS(Datagram Transport Layer Security)가 권고된다. 하지만 DTLS는 저전력 IoT 환경을 고려하여 만들어진 프로토콜이 아니다. 그래서 저전력 IoT 환경에서 사용하기에는 힘들다. 하지만 HIGHT(HIGh security and light weigHT) 알고리즘을 사용하면 보안적인 측면을 고려하면서도 DTLS의 알고리즘인 AES(Advanced Encryption Standard)의 높은 에너지 소모량이 해결된다. 본 논문에서는 보안 측면을 고려하면서 에너지 효율까지 고려한 KISA(Korea Internet & Security Agency, 한국인터넷진흥원)의 HIGHT 암호화 알고리즘을 기반으로 DTLS를 경량화하여 저전력 기기에서 적용할 수 있는 방안을 제안한다.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.22 no.9
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• pp.8-16
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• 2008

We studied drivers sight and physical status change by setup type of road lighting system. Influences on drivers emotional and motional change of lighting condition was investigated and function of road lighting setup position at night was analysed. Specially we analyzed influences of line type low hight lighting have influence on driver sight.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.24 no.4
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• pp.593-605
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• 2014

In this paper, we propose the efficient HW/SW co-design method of light-weight cryptography such as HIGHT, PRESENT and PRINTcipher using GEZEL. At first the symmetric cryptographic algorithms were designed using the GEZEL language which is efficiently used for HW/SW co-design. And for the improvement of performance the HW optimization theory such as unfolding, retiming and so forth were adapted to the cryptographic HW module conducted by FSMD. Also, the operation modes of those algorithms were implemented using C language in 8051 microprocessor, it can be compatible to various platforms. For providing reliable communication between HW/SW and preventing the time delay the improved handshake protocol was chosen for enhancing the performance of the connection between HW/SW. The improved protocol can process the communication-core and cryptography-core on the HW in parallel so that the messages can be transmitted to SW after HW operation and received from SW during encryption operation.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2011.06a
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• pp.1323-1324
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• 2011

• Proceedings of the KSR Conference
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• 2011.10a
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• pp.3147-3155
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• 2011

Railway bridges are highly susceptible to resonance due to the equidistant axle load with constant speed of train. Thus, it is inevitable verify dynamic characteristics and quantities against dynamic guidelines. Recently, various new-type bridges are developed and applies to medium span length between 30m and 40m. However, just steel box girder bridge is under review for span length between 45m and 50m without development any new technologies. This study investigate the dynamic properties and safety of steel box railway bridge having span length 45m in alternative girder hight and kind of ballast. Numerical analysis is performed time series analysis by mode superposition using calculated natural vibration frequency and mode after carry out a free vibration analysis and extract modal parameter to higher modes. The results are then compared to various dynamic stability standards toward target bridge's dynamic stability analysis. The result of this study is expected as a reference for design railway bridges.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2009.06a
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• pp.367-368
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• 2009

BSCCO HTS(High Temperature Superconductor) could be applied to superconducting cable, magnet and motor, using its hight critical properties. Especially, superconducting cable has a hight possibility of practical use due to the possibility of low voltage and high capacity transmission caused by its lower power loss than copper cable. In this paper, the transport characteristics of BSCCO superconducting cable, according to the change of BSCCO superconducting cable's accident point at phase $0^{\circ}$ and $45^{\circ}C$, were analyzed and compared each other. Consequently, when the accident was occur the resistance of the HTS was higher at the point phase $0^{\circ}$ than $45^{\circ}$ which means it will cause much higher load on the HTS.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.24 no.6 s.177
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• pp.1557-1564
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• 2000

When the half infinite crack in the orthotropic material strip with a large anisotropic ratio(E11>>E22) propagates with constant velocity, dynamic stress component $\sigma$y occurre d along the $\chi$ axis is derived by using the Fourier transformation and Wiener-Hopf technique, and the dynamic stress intensity factor is derived. The dynamic stress intensity factor depends on a crack velocity, mechanical properties and specimen hight. The normalized dynamic stress intensity factors approach the maximum values when normalized time(=Cs/a) is about 2. They have the constant values when the normalized time is greater than or equal to about 2, and decrease with increasing a/h(h: specimen hight, a: crack length) and the normalized crack propagation velocity( = c/Cs, Cs: shear wave velocity, c: crack propagation velocity).

• Transactions of the Korean Society of Automotive Engineers
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• v.18 no.4
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• pp.92-98
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• 2010

Virtual ground modeling is one of key topic for real-time vehicle dynamic simulation. This paper discusses about the virtual 3D road modeling process using parametric surface concept. General road data is a type of lumped position vector so interpolation process is required to compute contact of internal surface. The parametric surface has continuity and linearity within boundaries and functions are very simple to find out contact point. In this paper, the parametric surface formula is adopted to road modeling to calculate road hight. Position indexing method is proposed to reduce memory size and resource possession, and a simple mathematical method for contact patch searching is also proposed. The developed road process program is tested in dynamic driving simulation on off-road. Conclusively, the new virtual road program shows high performance of road hight computation in vast field of off-road simulation.

• Proceedings of the KIEE Conference
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• 1987.11a
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• pp.245-247
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• 1987

In this thesis, ZnO semiconductor gas sensors doped by the $Al^{3+}$ were fabricated by the miexed oxide method. The specimens were sintered for 5(hr) at $1000-1200^{\circ}C$ and the I-V, sensitivity were investigated in acetone gas or ammonia gas. As a result, I-V curves of specimens as a function of temperature variation showed characteristics of linear resistor that the current was proportional to the, temperature at constant voltage. For the sensitivity of acetone, 1Wt $Al^{3+}$-ZnO has the hight 0.91, ammonia gas, 2Wt $Al^{3+}$-ZnO specimen has the hight 0.90. Hence, the operating temperature of specimens were both $300^{\circ}C$.