• The Journal of the Acoustical Society of Korea
• /
• v.18 no.8
• /
• pp.32-41
• /
• 1999

In this paper, an inversion method using chirp signals and two near field receivers is proposed. Inversion problems can be formulated into the probabilistic models composed of signals, a forward model and noise. Forward model to simulate chirp signals is chosen to be the source-wavelet-convolution planewave modeling method. The solution of the inversion problem is defined by a posteriori pdf. The wavelet matching technique, using weighted least-squares fitting, estimates the sediment sound-speed and thickness on which determination of the ranges for a priori uniform distribution is based. The genetic algorithm can be applied to a global optimization problem to find a maximum a posteriori solution for determined a priori search space. Here the object function is defined by an L₂norm of the difference between measured and modeled signals. The observed signals can be separated into a set of two signals reflected from the upper and lower boundaries of a sediment. The separation of signals and successive applications of the genetic algorithm optimization process reduce the search space, therefore improving the inversion results. Not only the marginal pdf but also the statistics are calculated by numerical evaluation of integrals using the samples selected during importance sampling process of the genetic algorithm. The examples applied here show that, for synthetic data with noise, it is possible to carry out an inversion for sedimentary layers using the proposed inversion method.

• Geotechnical Engineering
• /
• v.13 no.4
• /
• pp.95-108
• /
• 1997

For normally consolidated clay, several researchers have developed a number of theoretical time factors to determine the coefficient of consolidation However, depending on the assumptions and analytical techniques, it could considerably vary even for a specific degree of consolidation. In this paper, a method is proposed to determine a consistent coefficient of consolidation over all ranges of degree of consolidation by applying the concept of the Optimum Design Technique. The initial excess pore pressure distribution is assumed to be obtainable by the successive spherical cavity expansion theory. The dissipation of pore pressure is simulated by means of two dimensional linear-uncoupled axisymmetric consolidation analysis. The minimization of the differences between the measured and the predicted excess pore pressures was carried by BFGS unconstrained optimum design algorithm with one dimensional golden section search technique. By analyzing numerical and real field examples, it can be found that the adopted optimum technique gives a consistent and convergent results.

• Journal of the Korea Institute of Information and Communication Engineering
• /
• v.7 no.8
• /
• pp.1792-1801
• /
• 2003

In these days, image mosaic is getting interest in the field of advertisement, tourism, game, medical imaging, and so on with the development of internet technology and the performance of personal computers. The main problem of mage mosaic is searching corresponding points correctly in the overlapped area between images. However, previous methods requires a lot of CPU times and data processing for finding corresponding points. And they need repeated recording with a revolution of 360 degree around objects or background. This paper presents a new image mosaic method which generates a panorama image from a video sequence recorded by a general video camera. Our method finds the corresponding points between two successive images by using a new direction oriented 3­step block matching methods. Experimental results show that the suggested method is more efficient than the methods based on existing block matching algorithm, such as full search and K­step search algorithm.

• Proceedings of the KSRS Conference
• /
• 2002.10a
• /
• pp.766-771
• /
• 2002

Automatic change detection based on the vector-to-raster comparison is hard especially in high-resolution image. This paper proposes a method to designate roads in high-resolution image in sequential manner using the information from vector map in which Hough transform is used for reliability. By its linearity, the road of urban areas in a vector map can be easily parameterized. Following some pre-processing to remove undesirable objects, we obtain the edge map of raster image. Then the edge map is transformed to a parameter space to find the selected road from vector map. The comparison is done in the parameter space to find the best matching. The set of parameters of a road from vector map is treated as the constraints to do matching. After designating the road, we may overlay it on the raster image for precise monitoring. The results can be used for detection of changes in road object in a semi-automatic fashion.

• Survey Research
• /
• v.11 no.3
• /
• pp.103-114
• /
• 2010

It is difficult to obtain the population information of target variables when a new sampling design for successive survey is executed. In a research of the Korea National Tourism Survey, we propose a method for selection of efficient stratification variables which are found in a combination of a existing sample data and a new frame list. At first, if there isn't common identification number between the frame list and the sample data, we find a device to substitute for absence of identification number. At second, we suggest a method to search stratification variables correlated with target variables using statistical methods like regression analysis.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
• /
• v.17 no.2
• /
• pp.88-94
• /
• 2003

In this paper, we propose a hierarchical triangular mesh generation method based on the motion information and a fast rude convergence method. From the variance of Image difference we decide the region that subdivision is required and perform the adequate triangulation method that is possible to yield a successive hierarchical triangulation. For fast node convergence, in initial search, we use the refinement method that separate the backgroung and object region and maintain the mesh connection by using the bilinear interpolation. The simulation result demonstrate that proposed triangulation method have performance in PSNR than the conventional BMA or order mesh based method and refinement is appropriate for the case of the mesh size is small.

• International Journal of Fuzzy Logic and Intelligent Systems
• /
• v.4 no.2
• /
• pp.135-141
• /
• 2004

This paper proposes a new heuristic search technique for obstacle avoidance of autonomous underwater vehicles equipped with a looking ahead obstacle avoidance sonar. We suggest the fuzzy relation between the sonar sections and the properties of real world environment. Bandler and Kohout's fuzzy relational method are used as the mathematical implementation for the analysis and synthesis of relations between the partitioned sections of sonar over the real-world environmental properties. The direction of the section with optimal characteristics would be selected as the successive heading of AUVs for obstacle avoidance. For the technique using in this paper, sonar range must be partitioned into multi equal sections; membership functions of the properties and the corresponding fuzzy rule bases are estimated heuristically. With the two properties Safety, Remoteness and sonar range partitioned in seven sections, this study gives the good result that enables AUVs to navigate through obstacles in the optimal way to goal.

• The Transactions of The Korean Institute of Electrical Engineers
• /
• v.59 no.2
• /
• pp.355-358
• /
• 2010

As CMOS technology continues to scale down, signal processing is favorably done in the digital domain, which requires Analog-to-Digital (A/D) Converter to be integrated on-chip. This paper presents a design methodology of 12-bit 1-MS/s Rail-to-Rail fully differential SAR ADC using Deep N-well Switch based on binary search algorithm. Proposed A/D Converter has the following architecture and techniques. Firstly, chip size and power consumption is reduced due to split capacitor array architecture and charge recycling method. Secondly, fully differential architecture is used to reduce noise between the digital part and converters. Finally, to reduce the mismatch effect and noise error, the circuit is designed to be available for Rail-to-Rail input range using simple Deep N-well switch. The A/D Converter fabricated in a TSMC 0.18um 1P6M CMOS technology and has a Signal-to-Noise-and-Distortion-Ratio(SNDR) of 69 dB and Free-Dynamic-Range (SFDR) of 73 dB. The occupied active area is $0.6mm^2$.

• Research in Community and Public Health Nursing
• /
• v.32 no.1
• /
• pp.116-129
• /
• 2021

Purpose: This study aimed to investigate the maternal health effects of internet-based education interventions on parturients during the postpartum period through a systematic review of randomized controlled trials. Methods: An electronic literature search of the Cochrane Library, CINAHL, EMBASE, Eric, PsycINFO, PubMed, RISS, and KISS databases was performed, using the combination of keywords such as 'parenthood education', '*natal education', '*birth intervention', 'internet-based intervention', 'randomized controlled trial'. The inclusion criteria were peer-reviewed papers in English regarding randomized controlled trials of internet-based postnatal education interventions. Educational interventions were delivered through any web, mobile, eHealth, mHealth, virtual reality, short message service, or social networking service platform. Quality appraisal was performed using the Risk of Bias 2 (RoB 2) for randomized controlled trials. Nine articles were yielded, and the intervention effects were analyzed. Results: Internet-based education interventions during the postpartum period affect maternal self-efficacy, postpartum depression, and successive breastfeeding; however, they do not affect maternal satisfaction and parenting confidence. Conclusion: This study demonstrated that internet-based education interventions affect maternal health status in terms of psychological, emotional, and physical wellness. Therefore, maternal health care professionals can utilize remote education using the internet or mobile-based interventions during the postpartum period.

• Advances in Traditional Medicine
• /
• v.7 no.1
• /
• pp.85-93
• /
• 2007

Free radicals are known to play important role in pathophysiology of hepatic disorders and antioxidants are employed along with other chemotherapeutic agents in treatment of such diseases. In search of natural antioxidant, successive extracts of Hypericum (H.) hookerianum (Family: Hypericaceae) were evaluated by in vitro and in vivo methods. Extracts of aerial parts of H. hookerianum were subjected for 1,1-diphenyl 2-picryl hydrazyl radical scavenging activity (DPPH assay), nitric oxide radicals scavenging assay and thiobarbituric acid reactive substances (TBARS) assay. Methanolic extract was found to be more active than other extracts in DPPH and in vitro TBARS assay with $IC_{50}$ at 5.82 ${\pm}$ 1.33 ${\mu}g/ml$ and 49.78 ${\pm}$ 3.79 ${\mu}g/ml$ respectively. While petroleum ether extract showed more potentials in scavenging the nitric oxide radicals with $IC_{50}$ 220.97 ${\pm}$ 2.69 ${\mu}g/ml$. The administration of $CCl_{4}$ to the control animals caused decrease in the level of catalase and superoxide dismutase, together with significant increase in the level of TBARS in liver and kidney. Reversal of these changes towards normal group was observed by administration of H. hookerianum methanolic extract at 50 and 100 mg/kg body weight, while other extracts were found to be less active.