• Proceedings of the KSRS Conference
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• 2007.10a
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• pp.195-198
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• 2007

GOCI(Geostationary Ocean Color Imager) is the core paryload of the geostationary satellite COMS(Communication, Ocean and Meteological Satellite) for ocean monitoring. It is scheduled to be launched at the end of 2008. GOCI observes ocean color around the Korean Peninsula over $2500km{\times}2500km$ area. Whole field of view is divided into 16 solts and scan mechanism enables to point each slot position. Tilted two-axis scan method is used to observe entire field of view with great pointing stability. Vignetting of the optical system appears when the partial obscuration by intermediate optical components occurs. It leads to the variation of the illumination in the image and gradual fading near the edge of the field. It should be prohibited for the stable radiometric performances. In this work, vignetting analysis of GOCI optical system is performed. For the systematic approach, GOCI optical system is divided into scan mechanism part and telescope part. Vignetting analysis of each part is performed and each result is combined for the overall vignetting performances. The analyzed results can be applied to the selection of slot acquisition angle of scan mechanism to minimize vignetting effects.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.43 no.10 s.352
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• pp.74-79
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• 2006

Test Interface Controller (TIC) provided by ARM Ltd. is widely used for functional testing of System-on-Chip (SoC) adopting Advanced Microcontroller Bus Architecture (AMBA) bus system. Accordingly, this architecture has a deficiency of not being able to concurrently shifting in and out the structural scan test patterns through the TIC and AMBA bus. This paper introduces a new AMBA based Test Access Mechanism (ATAM) for speedy testing of SoCs embedding ARM cores. While preserving the compatability with the ARM TIC, since scan in and out operations can be performed simultaneously, test application time through the expensive Automatic Test Equipment (ATE) can be drastically reduced.

• The Korean Journal of Nuclear Medicine
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• v.21 no.2
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• pp.213-219
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• 1987

Although the exact mechanism is not clearly understood yet, there were examples of the uptake of radiopharmaceuticals to the soft tissue lesions with $^{99m}Technetium$ methylene diphosphonate bone scan. Recently, we experienced two cases of neuroblastoma of which primary sites were imaged with $^{99m}Tc-MDP$ bone scan preoperatively and could make the diagnosis. So, we report here that $^{99m}Tc-MDP$ bone scan is the reasonable method not only to find out the bone metastasis, but also to diagnose the neuroblastoma preoperatively.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.10 no.6
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• pp.1191-1195
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• 2009

We present the efficient test wrapper design methodology considering the layout distance of scan chain. To test the scan chains in SoC, the scan chains must be assigned to external TAM(Test Access Mechanism) lines. The scan chains in IP were placed and routed without any timing violation at normal mode. However, in test mode, the scan chains have the additional layout distance after TAM line assignment, which can cause the timing violation of flip-flops in scan chains. This paper proposes a new test wrapper design considering layout distance of scan chains with timing violation free.

• Proceedings of the Korean Society of Machine Tool Engineers Conference
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• 2000.04a
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• pp.423-428
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• 2000

• Korean Journal of Remote Sensing
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• v.22 no.6
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• pp.595-600
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• 2006

GOCI is the core paryload of the geostationary satellite COMS(Communication, Ocean and Meteological Satellite) for ocean monitoring. It is scheduled to be launched at the end of 2008. GOCI observes ocean color around the Korean Peninsula over $2500km\times2500km$ area. It used tilted two-axis scan mechanism to observe entire field of view. In this work, the pointing stability of the tilted two-axis method is analyzed and compared with that of gimbal method. The analysis results show that tilted two-axis method gives great stability and it is adequate for geostationary payload. The results can also be used to determine and analyze the mechanism specifications.

• Journal of the Korean Institute of Telematics and Electronics A
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• v.31A no.6
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• pp.199-208
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• 1994

This paper proposes a delay fault test technique for ICs and PCBs with the boundary-scan architectures supporting ANSI/IEEE Std 1149.1-1990. The hybrid delay fault model, which comprises both of gate delay faults and path delay faults, is selected. We developed a procedure for testing delay faults in the circuits with typical boundary scan cells supporting the standard. Analyzing it,we concluded that it is impractical because the test clock must be 2.5 times faster than the system clock with the cell architect-ures following up the state transition of the TAP controller and test instruction set. We modified the boundary-scan cell and developed test instructions and the test procedure. The modified cell and the procedure need test clock two times slower than the system clock and support the ANSI/IEEE standard perfectly. A 4-bit ALU is selected for the circuits under test. and delay tests are simulated by the SILOS simulator. The simulation results ascertain the accurate operation and effectiveeness of the modified mechanism.

• Proceedings of the Korean Institute of Intelligent Systems Conference
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• 2002.05a
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• pp.252-255
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• 2002

As more critical services are provided in the internet, the risk to these services from malicious users increases. Several networks have experienced problems like Denial of Service(DoS) attacks recently. We analyse a network-based denial of service attack, which is called SYM flooding, to TCP-based networks. It occurs by an attacker who sends TCP connection requests with spoofed source address to a target system. Each request causes the targeted system to send instantly data packets out of a limited pool of resources. Then the target system's resources are exhausted and incoming TCP port connections can not be established. The paper is concerned with a detailed analysis of TCP SYN flooding denial of service attack. In this paper, we propose a Real Time Scan Detector(RTSD) mechanism and evaluate it\`s Performance.

• 한국정보디스플레이학회:학술대회논문집
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• 2003.07a
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• pp.130-133
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• 2003

Vertical Colour Selection (VCS) is an option for slim CRTs with increased sharpness and brightness. The direction of self-convergence of the DY is changed to vertical in order to obtain better spot uniformity, but the line scan direction remains horizontal. Hence, no video conversion is needed, contrary to transposed scan. In this paper we address two issues: First, there is a high risk of moire, since the scan lines and the phosphor stripes are parallel. We propose a feedback mechanism guiding the electron beams towards the middle of the mask slots. As positive side effects, the brightness is improved and the shadow mask can be made of a cheap type of steel. Secondly, VCS deflection coils have to satisfy different requirements than coils in ordinary CRTs. We discuss the design rules for self-convergent VCS coils and present simulation results.

• Journal of the Korean Institute of Intelligent Systems
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• v.18 no.5
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• pp.679-684
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• 2008

The slow port scan attack detection is the one of the important topics in the network security. We suggest an abnormal traffic control framework to detect slow port scan attacks using fuzzy rules. The abnormal traffic control framework acts as an intrusion prevention system to suspicious network traffic. It manages traffic with a stepwise policy: first decreasing network bandwidth and then discarding traffic. In this paper, we show that our abnormal traffic control framework effectively detects slow port scan attacks traffic using fuzzy rules and a stepwise policy.