• Journal of the Korean Society of Radiology
• /
• 제14권5호
• /
• pp.715-723
• /
• 2020

Cross-talk artifacts occur in two adjacent groups of axial imaging of lesions lumbar 4-5 and sacrum 1 in lumbar spine MRI. This causes problems in reading lesions in areas corresponding to the posterior vertebra. In this study, we are going to completely remove the cross-talk artifacts through optimal concatenation TR. The region of interested were measured by averaging them into fat (ROI1), erector spinal muscle(lateral tract: iliocostalis lumborum muscle) (ROI2), erector spinal muscle(lateral tract: longissimus muscle) (ROI3), and spinous process (ROI4). The mean signal intensity (SI) was 163.43 ± 25.08 at C4 for ROI1, ROI 2 and ROI 3 at C6, 67.89 ± 11.75 and 69.99 ± 10.91 and ROI4 at C5, respectively (p<0.000). The mean signal to noise ratio (SNR) was 135.45 ± 35.90, 56.92 ± 15.90, 58.77 ± 15.59, and 54.91 ± 118.95 for SNR 1, 2, 3 and 4 (p<0.000). The contrast-to-noise ratio (CNR) was CNR1 78.52 ± 24.11, CNR2 was 76.67 ± 24.38 and CNR3 was 80.54 ± 26.33 in concatenation 6, respectively (p<0.000). The SNR, CNR, and the most efficient concatenation TR value over time are 6, and it is considered to help reduce cross-talk artifact if this is applied to T1 axial images.

• Pediatric Infection and Vaccine
• /
• 제6권1호
• /
• pp.101-106
• /
• 1999

Purpose : Tuberculosis, a major public health problem, is an important cause of childhood infectious diseases. To decrease the tuberculosis morbidity rate, BCG vaccination and chemoprophylaxis are performed. Recently 2TU PPD skin test was introduced as a diagnostic method for tuberculous infection. We studied the positive conversion rate of 2TU PPD test after percutaneous multiple puncture BCG vaccination. Methods : Four hundred seventy six infants from well baby clinic of Samsung Cheil Hospital were enrolled. They were immunized with percutaneous multiple puncture technique BCG(Japan BCG laboratory, Japan) at 1 month of age. Approximately 6 months later, tuberculin skin test using RT23 2TU PPD was performed. Induration size, family history of tuberculosis and number of BCG scars were evaluated. Induration greater than or equal to 5mm was defined as positive conversion. Results : Among 476 infants, 248(52.1%) were male and 228(47.9%) were female. PPD skin tests were performed $6.2{\pm}0.5$($mean{\pm}S.D.$) months after BCG vaccination. Mean induration size was $7.3{\pm}3.2mm$ and positive conversion rate was 85.5%. Total number of BCG scars was $15.5{\pm}3.2$. Conclusion : The seroconversion rate by 2TU PPD test after percutaneous multiple puncture BCG vaccination was high. But, more comparative studies with various age groups may be needed for 2TU PPD test used as diagnostic method of tuberculosis in the hospitals.

• Journal of Korean Society of Forest Science
• /
• 제65권1호
• /
• pp.68-73
• /
• 1984

The purpose of this paper was to figure out the efficiencies of two sampling techniques, a simple random sampling and a two-stage P.P.S. (probability proportional to size) sampling, in estimating the volume of the mature coniferous stands near Salzburg, Austria. With black-and-white infrared photographs at a scale 1:10,000, the following four classes were considered; non-forest, young stands less than 40 years, mature beech and mature coniferous stands. After the classification, a field survey was carried out using a relascope with a BAF (basal area factor) 4. For the simple random sampling, 99 points were sampled, while for the P.P.S. sampling, 75 points were sampled in the mature coniferous stands. The following results were obtained. 1) The mean standing coniferous volume estimate was $422.0m^3/ha$ for the simple random sampling and $433.5m^3/ha$ for the P.P.S. sampling method. However, the difference was not statistically significant. 2) The required number of sampling points for a 5% sampling error were 170 for the two stage P.P.S. sampling, but 237 for the simple random sampling. 3) The two stage P.P.S. method reduced field survey time by 17% as compared to the simple random sampling.

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
• /
• 제26권3호
• /
• pp.241-253
• /
• 2008

Recently, it is appearing that new paradigm of urban planning that ubiquitous concept such as the u-City, uECO-City is introduced while is rising necessity about third dimensional geo-spatial information of high quality for urban area. Orthophoto can manufacture by expense and time that is less easily than digital map using personal computer even if is not highly technician and according as position relation between manmade feature and natural feature is equal, can get information of distance, angle, horizontal and vertical position coordinate of topographic, area etc.. directly through orthophoto. Also, visual effect is good that orthophoto is expressed by image and interpretation is easy to detailed part of topographic. Manufacture and practical use are consisting in various field, for it is having advantage that can recognize information effectively than digital map. Therefore, this study presents a way of generating a detailed DSM for producing a true-orthphoto of the urban area, and this study also presents a way to produce an optimum true-orthophoto for an urban area by investigating through experiment the optimum variable for the geometric and radiometric correction of the orthophoto. This study also examined the potentials of the thesis by building a 3-dimensional city model of the model region with the above thesis on optimum generating method.

• Journal of KIISE:Databases
• /
• 제29권1호
• /
• pp.34-43
• /
• 2002

Since traditional static metadata set like Dublin Core has static metadata attributes about bibliography information, integration of metadata for various metadata, problems about standard and extension of metadata must be considered for applying it to new environment. Specially, as event-driven metadata write method included the notion of e-commerce come out for interoperability in digital libraries, traditional metadata management which cannot distinguish between different kinds of update operations to new extension of metadata set occurs unsuitable waiting of update operation. So, improvement is needed about it. In this paper, we show whether alleviative transaction consistency can be applied to digital library or not. Also it would divide newer metadata into static metadata attribute connected in read operation within user read-only transaction and dynamic metadata attribute in update operation within dynamic(e-commerce) update transactions. We propose newer metadata management algorithm considered in classfication of metadata attributes and dynamic update transaction. Using two version for minimal maintenance cost and ARU(Appended Refresh Unit) for dynamic update transaction, to minimize conflict between read and write operations shows fast response time and high recency ratio. As a result of the performance evaluation, we show our algorithm is proved to be better than other algorithms in newer metadata environments.

• Journal of Radiation Protection and Research
• /
• 제26권1호
• /
• pp.7-12
• /
• 2001

Sintered LiF:Mg,Cu,Na,Si thermoluminescence (TL) pellets were developed for application in radiation dosimetry. In the present study, the TL dosimetric properties of LiF:Mg,Cu,Na,Si TL pellets have been investigated for emission spectrum, dose response, energy response, and fading characteristics. LiF:Mg,Cu,Na,Si TL pellets were made by using a sintering process, that is, pressing and heat treatment from TL powders. Photon irradiations for the experiments were carried out using X-ray beams and a $^{137}Cs$ gamma source at the Korea Atomic Energy Research Institute (KAERI). The average energies and the dose were in the range of 20-662 keV and $10^{-6}-10^{-2}\;Gy$, respectively. The glow curves were measured with a manual type TLD reader(System 310, Teledyne) at a constant nitrogen flux and a linear heating rate. For a constant heating rate of $5^{\circ}C\;s^{-1}$, the main dosimetric peak of glow curve appeared at $234^{\circ}C$, the activation energy was 2.34 eV and frequency factor was $1.00{\times}10^{23}$. TL emission spectrum is appeared at the blue region centered at 410 nm. A linearity of photon dose response was maintained up to 100 Gy. The photon energy responses relative to $^{137}Cs$ response were within ${\pm}20%$ at overall photon energy region. The fading of TL sensitivity of the pellets stored at the room temperature was not found for one year.

• Journal of the Korean Vacuum Society
• /
• 제9권3호
• /
• pp.258-262
• /
• 2000

$YMnO_3$thin films are deposited on Si(100) and $Y_2O_3/Si(100)$ substrate by radio frequency sputtering. The deposition condition of oxygen partial pressure and annealing temperature have significant influences on the preferred orientation of $YMnO_3$film and the size of memory window. The results of x-ray diffraction show that the film deposited in the oxygen partial pressure of 0% is highly oriented along c-axis after annealing at $870^{\circ}C$ for 1 hr in oxygen ambient. However, the films deposited on Si and $Y_2O_3/Si$ in the oxygen partial pressures of 20% show $Y_2O_3$ peak, the excess $Y_2O_3$ in the $YMnO_3$film suppresses the c-axis oriented crystallization. Especially memory windows of the $Pt/YMnO_3/Y_2O_3/Si$ capacitor are 0.67~3.65 V at applied voltage of 2~12 V, which is 3 times higher than that of the film deposited on $Y_2O_3/Si$ in 20% oxygen (0.19~1.21 V) at the same gate voltage because the film deposited in 0% oxygen is well crystallized along c-axis.

• Journal of the Institute of Electronics Engineers of Korea SC
• /
• 제47권3호
• /
• pp.48-55
• /
• 2010

Hearing impairment is one of the most common birth defects among infants. Significant bilateral hearing impairment have profound effects on speech and language development. But it can be prevented, if a hearing impairment is identified and treated in its early stage. ABR (auditory brainstem response) is useful screening tool for new born hearing test. However, the interpretation of conventional ABR should be done by a experienced audiologist and testing takes some time. Therefore, A-ABR(automated ABR) which detect ABR peak automatically have been developed recently. In contrast to A-ABR researches became active in overseas, there has been little study in Korea. In this study, we have developed a portable A-ABR system based on the results of our previous study. For the evaluation of the developed system, the clinical trials were performed on adults and infants. As a results, it showed good sensitivity (94.4%) and specificity (92.2%), and accuracy (93.0%) between clinical diagnosis and the developed A-ABR test.

• Journal of Korean Tunnelling and Underground Space Association
• /
• 제24권4호
• /
• pp.341-353
• /
• 2022

Pipelines are buried in urban area, and the position (depth and orientation) of buried pipeline should be clearly identified before ground excavation. Although various geophysical methods can be used to detect the buried pipeline, it is not easy to identify the exact information of pipeline due to heterogeneous ground condition. Among various non-destructive geo-exploration methods, ground penetration radar (GPR) can explore the ground subsurface rapidly with relatively low cost compared to other exploration methods. However, the exploration data obtained from GPR requires considerable experiences because interpretation is not intuitive. Recently, researches on automated detection technology for GPR data using deep learning have been conducted. However, the lack of GPR data which is essential for training makes it difficult to build up the reliable detection model. To overcome this problem, we conducted a preliminary study to improve the performance of the detection model using finite difference time domain (FDTD)-based numerical analysis. Firstly, numerical analysis was performed with homogeneous soil media having single permittivity. In case of heterogeneous ground, numerical analysis was performed considering the ground heterogeneity using fractal technique. Secondly, deep learning was carried out using convolutional neural network. Detection Model-A is trained with data set obtained from homogeneous ground. And, detection Model-B is trained with data set obtained from homogeneous ground and heterogeneous ground. As a result, it is found that the detection Model-B which is trained including heterogeneous ground shows better performance than detection Model-A. It indicates the ground heterogeneity should be considered to increase the performance of automated detection model for GPR exploration.

• Journal of the Korean GEO-environmental Society
• /
• 제23권8호
• /
• pp.29-36
• /
• 2022

The importance of subsurface information is becoming crucial in urban area due to increase of underground construction. The position of underground facilities should be identified precisely before excavation work. Geophyiscal exporation method such as ground penetration radar (GPR) can be useful to investigate the subsurface facilities. GPR transmits electromagnetic waves to the ground and analyzes the reflected signals to determine the location and depth of subsurface facilities. Unfortunately, the readability of GPR signal is not favorable. To overcome this deficiency and automate the GPR signal processing, deep learning technique has been introduced recently. The accuracy of deep learning model can be improved with abundant training data. The ground is inherently heteorogeneous and the spacially variable ground properties can affact on the GPR signal. However, the effect of ground heterogeneity on the GPR signal has yet to be fully investigated. In this study, ground heterogeneity is simulated based on the fractal theory and GPR simulation is carried out by using gprMax. It is found that as the fractal dimension increases exceed 2.0, the error of fitting parameter reduces significantly. And the range of water content should be less than 0.14 to secure the validity of analysis.