• Journal of the Korean Society of Radiology
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• v.9 no.5
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• pp.279-285
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• 2015

The eye of human is a radiation sensitive organ and this organ should be shielded from radiation exposure during brain CT procedures. In the brain CT procedures, bismuth protector using to reduce the radiation exposure dose for eye. But protecting the bismuth always accompanies problem of the image quality reduction including artifact. This study aim is the eye radiation exposure dose and image quality evaluation of the new tube current modulation such as new organ based-tube current modulation, longitudinal-TCM, angular-TCM between shielding scan technique using bismuth and lead glasses. As a result, radiation dose of eye is reduced 25.88% in new OB TCM technique then reference scan technique and SNR new OB TCM is 6.05 higher than bismuth shielding scan technique and lower than reference scan technique. In clinical brain CT, new OB TCM technique will contribute to reduction of radiation dose for eye without decrease of image quality.

• Journal of KIISE:Computing Practices and Letters
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• v.16 no.6
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• pp.732-736
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• 2010

Processing a large amount of data becomes more important than ever. Particularly, the information queries which require multi-dimensional record scan can be efficiently implemented with SIMD instruction sets. In this article, we present a SIMD record scan technique which employs row-based scanning. Our technique is different from existing SIMD techniques for predicate processes and aggregate operations. Those techniques apply SIMD instructions to the attributes in the same column of the database, exploiting the column-based record organization of the in-memory database systems. Whereas, our SIMD technique is useful for multi-dimensional record scanning. As the sizes of registers and the memory become larger, our row-based SIMD scan can have bigger impact on the performance. Moreover, since our technique is orthogonal to the parallelization techniques for multi-core processors, it can be applied to both uni-processors and multi-core processors without too many changes in the software architectures.

• Journal of Advanced Information Technology and Convergence
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• v.9 no.1
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• pp.1-10
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• 2019

In recent years, information collection of attacks through stealth port scanning technology has become more sophisticated. The most commonly used Nmap port scanner supports a variety of stealth scanning technologies along with the existing scanning techniques. Nmap also supports Idle scan that is different from conventional stealth scans. This is a more sophisticated stealth scan technique by applying the SYN scan and ACK scan techniques. In previous studies, the detection of Idle scanning was on zombie system, but was not on victim system. In this paper, we propose an effective detection method of Idle scan on victim system. The Idle scanning is composed of two stages; they are probing the zombie and victim system and scanning the victim system. We analyzed the characteristics of the two stages. The characteristics, we captured, are that SYN and RST packets are different from normal packet. We applied them to detection method, then Idle scanning is detected effectively.

• Investigative Magnetic Resonance Imaging
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• v.10 no.2
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• pp.108-116
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• 2006

Purpose : High-resolution spiral-scan imaging is performed at 3 Tesla MRI system. Since the gradient waveforms for the spiral-scan imaging have lower slopes than those for the Echo Planar Imaging (EPI), they can be implemented with the gradient systems having lower slew rates. The spiral-scan imaging also involves less eddy currents due to the smooth gradient waveforms. The spiral-scan imaging method does not suffer from high specific absorption rate (SAR), which is one of the main obstacles in high field imaging for rf echo-based fast imaging methods such as fast spin echo techniques. Thus, the spiral-scan imaging has a great potential for the high-speed imaging in high magnetic fields. In this paper, we presented various high-resolution images obtained by the spiral-scan methods at 3T MRI system for various applications. Materials and Methods : High-resolution spiral-scan imaging technique is implemented at 3T whole body MRI system. An efficient and fast higher-order shimming technique is developed to reduce the inhomogeneity, and the single-shot and interleaved spiral-scan imaging methods are developed. Spin-echo and gradient-echo based spiral-scan imaging methods are implemented, and image contrast and signal-tonoise ratio are controlled by the echo time, repetition time, and the rf flip angles. Results : Spiral-scan images having various resolutions are obtained at 3T MRI system. Since the absolute magnitude of the inhomogeneity is increasing in higher magnetic fields, higher order shimming to reduce the inhomogeneity becomes more important. A fast shimming technique in which axial, sagittal, and coronal sectional inhomogeneity maps are obtained in one scan is developed, and the shimming method based on the analysis of spherical harmonics of the inhomogeneity map is applied. For phantom and invivo head imaging, image matrix size of about $100{\times}100$ is obtained by a single-shot spiral-scan imaging, and a matrix size of $256{\times}256$ is obtained by the interleaved spiral-scan imaging with the number of interleaves of from 6 to 12. Conclusion : High field imaging becomes increasingly important due to the improved signal-to-noise ratio, larger spectral separation, and the higher BOLD-based contrast. The increasing SAR is, however, a limiting factor in high field imaging. Since the spiral-scan imaging has a very low SAR, and lower hardware requirements for the implementation of the technique compared to EPI, it is suitable for a rapid imaging in high fields. In this paper, the spiral-scan imaging with various resolutions from $100{\times}100$ to $256{\times}256$ by controlling the number of interleaves are developed for the high-speed imaging in high magnetic fields.

• Journal of the Korean Society for Precision Engineering
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• v.18 no.9
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• pp.165-170
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• 2001

In normal grinding abrasive particles of a grinding wheel rotate on planes parallel to the direction of workpiece fred. which may induce continued scratch lines on ground surface as the workpiece feeds. Instead in helical scan grinding the planes make an angle, called a helical angle, with the feeding direction. Thus scratch lines produced by abrasive particles per one revolution are discontinued which implies that the generation of scratch lines are suppressed by the helical scan grinding. In this study some experimental works have been done on the helical scan grinding of glass to find the effects of grinding conditions on the surface roughness and estimate the optimal grinding conditions. The helical angle, fred rate, material removal rate and the wheel speed are taken as factors for three kinds of grinding wheels i.e., coarse(#140 mesh), medium(#400) and fine(#800) diamond wheels. The experiments are scheduled by Taguchi technique and ANOVA has been carried out for the interpretation of the results. As a result of this study effects of the factors are verified quantitatively showing that the major factors are changed according to the wheel's mesh size and the helical angle is one of the influencing factors on the surface quality.

• The Journal of the Korea Contents Association
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• v.5 no.1
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• pp.229-236
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• 2005

Testing time and power consumption during testing System-On-a-Chip (SOC) are becoming increasingly important as the IP core increases in a SOC. We present a new algorithm to reduce the scan-in power and test data volume using the modified scan latch reordering. We apply scan latch reordering technique for minimizing the hamming distance in scan vectors. Also, during scan latch reordering, the don't care inputs in scan vectors are assigned for low power and high compression. Experimental results for ISCAS 89 benchmark circuits show that reduced test data and low power scan testing can be achieved in all cases.

• Journal of the Korean Society of Manufacturing Technology Engineers
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• v.5 no.4
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• pp.38-46
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• 1996

This paper discusses the feasibility of Ultrasonic Nondestructive Evaluation (UNDE) technique for sport weld quality. Ultrasonic c-scan image assisted by image processing technique was used for Nondestructive Evaluation(NDE) of spot weld quality. Ultrasonic testing results obtained were confirmed and compared by Optical Microscope and SAM(Scanning Acoustic Mircroscope) observation of the spot-weld cross section, The results show that the nugget dinameter can be successfully measured with the accuracy of 0.5mm. It was ascertained that ultrasonic c-scan technique is very effective method for the sake of the approach to the quantitative measurement of nugget diameter and the discrimination of the corona bond from nugget. Additional support for the above conclusions is provided by the results for galvanized steel. The ultrasonic results for galvanized welds generally correspond to the results for uncoated steel. Finally, it was found that the above-mentioned technique can be sufficiently applied to NDE method for securing the Quality Assurance(QA) of spot welded products in production line.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.41 no.11
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• pp.115-121
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• 2004

GenJTAG implemented in this paper is an automatic web-based boundary scan circuit generator. GenJTAG supports all the public instructions for the boundary scan technique, and also private instructions for other DFT techniques to be applied. Users can easily edit the generated boundary scan circuit code because it is described in behavioral level with the Verilog-HDL. GenJTAG has another advantage that any one can generate the boundary scan circuit by simply accessing to the web site.

• Journal of Korea Water Resources Association
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• v.47 no.10
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• pp.867-878
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• 2014

Due to the nature of weather radar, blank areas occur due to impediments to observation, such as the ground clutter. Radar beam blockages have resulted in the underestimation rainfall amounts. To overcome these limitations, this study developed the Hybrid Scan Reflectivity (HSR) technique and compared the HSR results with existing methods. As a result, the HSR technique was able to estimate rainfalls in areas from which no reflectivity information was observable using existing methods. In case of estimating rainfalls depending on reflectivity scan techniques and beam-blockage/non beam-blockage, the HSR accuracy is superior. Furthermore, rainfall amounts derived from each method was inputted to the HEC-HMS to examine the accuracy of the flood simulations. The accuracy of the results using the HSR technique in contrast to the RAR calculation system and M-P relation was improved by 7% and 10%(based on correlation coefficients), and 18% and 34%(based on Nash-Sutcliffe Efficiency), on average, respectively. Therefore, it is advised that the HSR technique be utilized in the hydrology field to estimate flood discharge more accurately.

• Journal of KIISE:Computer Systems and Theory
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• v.26 no.9
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• pp.1177-1184
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• 1999

본 논문에서는 스캔플립프롭 선택 시간이 짧고 높은 고장 검출률(fault coverage)을 얻을 수 있는 새로운 부분스캔 설계 기술을 제안한다. 순차회로에서 테스트패턴 생성을 용이하게 하기 위하여 완전스캔 및 부분스캔 설계 기술이 널리 이용되고 있다. 스캔 설계로 인한 추가영역을 최소화 하고 최대의 고장 검출률을 목표로 하는 부분스캔 기술은 크게 구조분석과 테스트 가능도(testability)에 의한 설계 기술로 나누어 볼 수 있다. 구조분석에 의한 부분스캔은 짧은 시간에 스캔플립프롭을 선택할 수 있지만 고장 검출률은 낮다. 반면 테스트 가능도에 의한 부분스캔은 구조분석에 의한 부분스캔보다 스캔플립프롭의 선택 시간이 많이 걸리는 단점이 있지만 높은 고장 검출률을 나타낸다. 본 논문에서는 구조분석에 의한 부분스캔과 테스트 가능도에 의한 부분스캔 설계 기술의 장단점을 비교.분석하여 통합함으로써 스캔플립프롭 선택 시간을 단축하고 고장 검출률을 높일 수 있는 새로운 부분스캔 설계 기술을 제안한다. 실험결과 대부분의 ISCAS89 벤치마크 회로에서 스캔플립프롭 선택 시간은 현격히 감소하였고 비교적 높은 고장 검출률을 나타내었다.Abstract This paper provides a new partial scan design technique which not only reduces the time for selecting scan flip-flops but also improves fault coverage. To simplify the problem of the test pattern generation in the sequential circuits, full scan and partial scan design techniques have been widely adopted. The partial scan techniques which aim at minimizing the area overhead while maximizing the fault coverage, can be classified into the techniques based on structural analysis and testabilities. In case of the partial scan by structural analysis, it does not take much time to select scan flip-flops, but fault coverage is low. On the other hand, although the partial scan by testabilities generally results in high fault coverage, it requires more time to select scan flip-flops than the former method. In this paper, we analyzed and unified the strengths of the techniques by structural analysis and by testabilities. The new partial scan design technique not only reduces the time for selecting scan flip-flops but also improves fault coverage. Test results demonstrate the remarkable reduction of the time to select the scan flip-flops and high fault coverage in most ISCAS89 benchmark circuits.