• Journal of the Korean Society for Nondestructive Testing
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• v.25 no.1
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• pp.9-14
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• 2005

The angular dependence(profile) of backward radiated ultrasound was measured for glass specimens with random surface roughness using ultrasonic goniometer that ran changes the incident angle continuously. It was concluded that the roughened region had greater acoustic impedance than the unperturbed region. The comparison of backward radiations showed that the amplitude of peak and the area of radiation profile were increased with surface roughness. It was suggested from the sensitive dependence of the profile area that the profile of backward radiation could be applied to in the nondestructive evaluation of sulfate region. Inclined C-scan technique with the transducer inclined at Rayleigh angle showed the reverse of luminosity and the high signal to noise ratio so that it provided high resolution.

• Journal of Electrical Engineering and information Science
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• v.2 no.3
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• pp.105-112
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• 1997

The performance of a shared memory multiprocessor system is very sensitive to process scheduling. w can enhance the performance of a whole system as well as of an individual process by taking the multiprocessor characteristics into account in the design of the process scheduler. In this paper, we proposed a general purpose scheduler for a shared memory multiprocessor, called the Two-Level Multi-Scan (TLMS) process scheduler, that considers the processor affinity loosely and decreases the interference among multiple processors greatly. The TLMS scheduler is composed of a local scheduler at each processor and a semi-global scheduler that balances the load among processors. In particular, the semi-global scheduler tries to minimize priority inversion, which is an important factor of the system performance. The TLMS scheduler also tries to reduce the number of resources to be shared and improves the processor utilization. to meet these requirements, th semi-global scheduler interacts with the operation of the local scheduler when a need arises, thus the name is loose processor-affinity. We also show that the proposed scheduling technique can be extended for other types of resources making it a general purpose resource management queue.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.28 no.9
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• pp.593-597
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• 2015

Ni ink for electrohydrodynamic (EHD) continuous jet printing has been developed by using Ni nanoparticles mixed with conhesiveness provider. EHD continuous jet printing was used in order to realize $20{\mu}m$ pattern width. Ink stability was investigated by using Turbi-scan which monitors agglomeration and precipitation of nanoparticles in the ink for three days. The Turbi-scan results showed that the formulated Ni ink had been stable for 3 days without any indication of precipitation across the entire ink. Antireflection coating (ARC) layer in crystalline solar cell wafers was removed by laser ablation technique leading to the formation of 84 grooves where the Ni ink was printed by EHD continuous jet printing. The printability and microstructure of EHD-jet-printed Ni lines were investigated by using optical and electron microscopes. 84 Ni lines with the width less than $20{\mu}m$ were successfully printed by one-time printing without any misalignment and fill the laser-ablated ARC grooves.

• Journal of the Korean Society for Precision Engineering
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• v.15 no.7
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• pp.149-159
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• 1998

The importance of soundness and safety evaluation in weld zone using by the ultrasonic wave has been recently increased rapidly because of the collapses of huge structures and safety accidents. Especially, the ultrasonic method that has been often used for a major non-destructive testing(NDT) technique in many engineering fields plays an important role as a volume test method. Hence, the defecting any defects of weld Bone in austenitic stainless steel type 304 using by ultrasonic wave and neural network is explored in this paper. In order to detect defects, a distance amplitude curve on standard scan sensitivity and preliminary scan sensitivity represented of the relation between ultrasonic probe, instrument, and materials was drawn based on a quantitative standard. Also, a total of 93％ of defect types by testing 30 defect patterns after organizing neural network system, which is learned with an accuracy of 99％, based on ultrasonic evaluation is distinguished in order to classify defects such as holes or notches in experimental results. Thus, the proposed ultrasonic wave and neural network is useful for defect detection and Ultrasonic Non-Destructive Evaluation(UNDE) of weld zone in austenitic stainless steel 304.

• Fashion & Textile Research Journal
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• v.24 no.4
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• pp.443-450
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• 2022

This study developed a three-dimensional helmet mold design software that can design helmets for treating the infant plagiocephaly (flat head syndrome) using three-dimensional head scan data. For this, the three-dimensional head data of sixth SizeKorea body measurement project as well as the data produced by a head modeling software were used to prepare the head shape data of plagiocephaly patients. A total of 14 landmarks and 10 dimensions of heads required for helmet mold shape design and plagiocephaly diagnosis were automatically measured using an anthropometric analysis software. Using the software developed in this study, plagiocephaly can be diagnosed not only visually by three-dimensional head data visualization but also quantitatively by calculating the medically defined indices such as cranial index, which measures the proportions of the head, and the cranial vault asymmetry index, which measures the asymmetry of the head. The basic shape of the helmet mold was automatically generated based on the head scan data. Additionally, it is possible to fine tune the shape of the mold to reflect individual characteristics by using a free form deformation technique. Finally, the designed helmet mold was converted into the data that can be printed on a three-dimensional printer for generating the actual prototype.

• Journal of the Korean Society of Radiology
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• v.82 no.6
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• pp.1493-1504
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• 2021

Purpose This study aimed to evaluate the utility of the 16-cm axial volume scan technique for calculating the coronary artery calcium score (CACS) using non-enhanced chest CT. Materials and Methods This study prospectively enrolled 20 participants who underwent both, non-enhanced chest CT (16-cm-coverage axial volume scan technique) and calcium-score CT, with the same parameters, differing only in slice thickness (in non-enhanced chest CT = 0.625, 1.25, 2.5 mm; in calcium score CT = 2.5 mm). The CACS was calculated using the conventional Agatston method. The difference between the CACS obtained from the two CT scans was compared, and the degree of agreement for the clinical significance of the CACS was confirmed through sectional analysis. Each calcified lesion was classified by location and size, and a one-to-one comparison of non-contrast-enhanced chest CT and calcium score CT was performed. Results The correlation coefficients of the CACS obtained from the two CT scans for slice thickness of 2.5, 1.25, and 0.625 mm were 0.9850, 0.9688, and 0.9834, respectively. The mean differences between the CACS were -21.4% at 0.625 mm, -39.4% at 1.25 mm, and -76.2% at 2.5 mm slice thicknesses. Sectional analysis revealed that 16 (80%), 16 (80%), and 13 (65%) patients showed agreement for the degree of coronary artery disease at each slice interval, respectively. Inter-reader agreement was high for each slice interval. The 0.625 mm CT showed the highest sensitivity for detecting calcified lesions. Conclusion The values in the non-contrast-enhanced chest CT, using the 16-cm axial volume scan technique, were similar to those obtained using the CACS in the calcium score CT, at 0.625 mm slice thickness without electrocardiogram gating. This can ultimately help predict cardiovascular risk without additional radiation exposure.

• Korean Journal of Remote Sensing
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• v.38 no.5_1
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• pp.447-460
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• 2022

It is well known that satellite synthetic aperture radar interferometry (InSAR) has been widely used for the observation of surface displacement owing to earthquakes, volcanoes, and subsidence very precisely. In wetlands where vegetation exists on the surface of the water, it is possible to create a water level change map with high spatial resolution over a wide area using the InSAR technique. Currently, a number of imaging radar satellites are in operation, and most of them support a ScanSAR mode observation to gather information over a large area at once. The Cienaga Grande de Santa Marta (CGSM) wetland, located in northern Colombia, is a vast wetland developed along the Caribbean coast. The CGSM wetlands face serious environmental threats from human activities such as reclamation for agricultural uses and residential purposes as well as natural causes such as sea level rise owing to climate change. Various restoration and protection plans have been conducted to conserve these invaluable environments in recognition of the ecological importance of the CGSM wetlands. Monitoring of water level changes in wetland is very important resources to understand the hydrologic characteristics and the in-situ water level gauge stations are usually utilized to measure the water level. Although it can provide very good temporal resolution of water level information, it is limited to fully understand flow pattern owing to its very coarse spatial resolution. In this study, we evaluate the L-band ALOS-2 PALSAR-2 ScanSAR mode to observe the water level change over the wide wetland area using the radar interferometric technique. In order to assess the quality of the interferometric product in the aspect of spatial resolution and coherence, we also utilized ALOS-2 PALSAR-2 stripmap high-resolution mode observations.

• Journal of Korean Neurosurgical Society
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• v.40 no.3
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• pp.206-209
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• 2006

Objective : Traditionally, standard access to the posterior fossa was a suboccipital craniectomy. After introducing the technique and benefit of posterior fossa craniotomy, several surgeons have used this procedure to manage various pathologies in posterior fossa in children. Though this approach offers several advantages over conventional suboccipital craniectomy, the elevation of bone flap is not easy in adult because of the irregular contour of inner bone surface and tight adhesion of dura to the skull. The aim of this article is to describe the technical aspects of this approach and to delineate the important landmarks for a safe and quick performance in adult. Methods : We report on our series of twenty-five adult patients who underwent craniotomy for posterior fossa pathologies between 2002 and 2005. The maximal follow-up period was 4 years. Results : None of the patients complained of persistent headache and no CSF leaks have occurred postoperatively. We have encountered only two cases of transient subcutaneous CSF retention after craniotomy. Three-dimensional reconstruction of the CT scan confirmed the well-fitted suboccipital bone contour after craniotomy. And patients were satisfied with the cosmetic results. Conclusion : This method is safer and simpler. It restores normal anatomical planes and improves protection of the contents of the posterior fossa. The authors recommend craniotomy as an alternative method of access to the posterior fossa in all age groups.

• Journal of Magnetics
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• v.21 no.1
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• pp.148-152
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• 2016

The main goal was to evaluate effectiveness of a modified TSE sequence compared with DIR (double inversion recovery) sequence in acquisition of fast flow brain vessel images using signal void effect. 32 healthy volunteers (10 men and 22 women; mean age of 31 years; ranging between 28-43 years) who underwent black blood DIR sequence (group A) and the modified TSE sequence (group B) were enrolled in our study. Signal to Noise Ratio (SNR) and Contrast to Noise Ratio (CNR) of the internal carotid arteries' lumen were compared in T1 and T2 weighted images for both group A and B. The images obtained from group B showed lower SNR values in internal carotid artery than the group A in both of the T1 and T2 weighted images (11.49% and 13.66% respectively). While the CNR values were higher in the group B than the group A in both of the T1 and T2 weighted images (8.69% and 7.55 % respectively). The qualitative score of all categories were not significantly different between the two groups. Furthermore approximately 49% of the total scan time was reduced from group B. Our study is to shorten the scanning time and minimize the inconveniences of the patients in acquisition of the black blood images of brain by using the signal void effect in the modified TSE technique while keeping the diagnostic value of the test.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.48 no.2
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• pp.44-54
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• 2011

The goal of this paper is reducing the test time for AMBA-based SoC. To achieve this goal, the design technique that can test several cores concurrently by reusing AMBA as TAM is proposed. The additional control logic for structural parallel core test is minimized by reusing TIC which is originally used for functional test of AMBA. SoC reliability and test time reduction can be significantly achieved with the concurrent core test technique as well as functional test.