• Proceedings of the KOSOMBE Conference
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• v.1997 no.05
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• pp.72-74
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• 1997

We have developed a 3-D image processing and display technique that include image resampling, modification of MIP, and fusion of MIP image and volumetric rendered image. This technique facilitates the visualization of the three-dimensional spatial relationship between vasculature and surrounding organs by overlapping the MIP image on the volumetric rendered image of the organ. We applied this technique to a MR brain image data to produce an MRI angiogram that is overlapped with 3-D volume rendered image of brain. MIP technique was used to visualize the vasculature of brain, and volume rendering was used to visualize the other structures of brain. The two images are fused after adjustment of contrast and brightness levels of each image in such a way that both the vasculature and brain structure are well visualized either by selecting the maximum value of each image or by assigning different color table to each image. The resultant image with this technique visualizes both the brain structure and vasculature simultaneously, allowing the physicians to inspect their relationship more easily. The presented technique will be useful for surgical planning for neurosurgery.

• 한국정보디스플레이학회:학술대회논문집
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• 2005.07b
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• pp.944-947
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• 2005

Highly stable gate driver circuit using a-Si TFT has been developed. The circuit has dual-pull down structure, in which bias stress to the TFTs is relieved by alternating applied voltage. The circuit has been successfully integrated in 4-in. QVGA and 14-in. XGA TFT-LCD with a normal a-Si process, which are stable for over 2,000 hours at $60^{\circ}C$. The enhancement of stability of the circuit is attributed to retarded degradation of pull-down TFTs by AC driving.

• Transactions of the Korean Society of Mechanical Engineers
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• v.10 no.1
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• pp.96-101
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• 1986

The average heat transfer coefficient of 2-D impinging jet has been augmented as much as 60% on the wall with large-scale wavy roughness. The mechanism of this heat transfer augmentation is studied with emphasis on two primary flow structures in the impinging flow region by using either the surface floating method or the smoke-wire technique. They are the stream-wise vortex-like structure, which is characteristic to the impining jet, and the spanwise vortiecs associated with the flow separation around the roughness. The combined effect of these structures can effectively augment the heat transfer particularly in the downstream region where the teat transfer usually deteriorates consicerably.

• The Journal of Korean Physical Therapy
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• v.13 no.3
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• pp.719-726
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• 2001

Transdermal drug delivery offers various advantages over conventional drug delivery systems, such as avoidance gastrointestinal degradation and hepatic first-pass effect. encourages patient compliance. and possible sustained release of drugs. However, transdermal transport of drugs is low permeability of the stratum corneum, the superficial layer of the skin. Many physicochemical and biological factors influencing transdermal transport is described together with the corresponding experimental and clinical results. Phonophoresis is medical treatment with drugs introduced into the skin by ultrasound energy. Enhanced drug penetration is through to result from the biophysical alterations of skin structure by ultrasound waves. The frequency used for phonophoresis is usually from 20 kHz to 15MHz. Phonophoresis can be categorized in to three ranges: low-frequency range(below 1 MHz). therapeutic frequency range(1 to 3MHz), and high-frequency range(above 3 MHz). The depth of penetration of ultrasound into skin is inversely proportional to the frequency. Cavitation may cause mechanical stress. temperature elevation, or enhanced chemical reactivity causing drug transport. One theory is that ultrasound affects the permeation of the stratum corneum lipid structure as the limiting step in permeating through the skin. The range of indications for phonophoresis is wide. Aspecific classification of the range of indications is obtained by classification of pathological conditions. The continuous research is needed for many interesting issucs of phonophoretic transdermal delivory in new future.

• IEMEK Journal of Embedded Systems and Applications
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• v.11 no.3
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• pp.163-171
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• 2016

Lane detection is a widely researched topic. Although simple road detection is easily achieved by previous methods, lane detection becomes very difficult in several complex cases involving noisy edges. To address this, we use a Convolution neural network (CNN) for image enhancement. CNN is a deep learning method that has been very successfully applied in object detection and recognition. In this paper, we introduce a robust lane detection method based on a CNN combined with random sample consensus (RANSAC) algorithm. Initially, we calculate edges in an image using a hat shaped kernel, then we detect lanes using the CNN combined with the RANSAC. In the training process of the CNN, input data consists of edge images and target data is images that have real white color lanes on an otherwise black background. The CNN structure consists of 8 layers with 3 convolutional layers, 2 subsampling layers and multi-layer perceptron (MLP) of 3 fully-connected layers. Convolutional and subsampling layers are hierarchically arranged to form a deep structure. Our proposed lane detection algorithm successfully eliminates noise lines and was found to perform better than other formal line detection algorithms such as RANSAC

• Economic and Environmental Geology
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• v.29 no.5
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• pp.615-622
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• 1996

Slope stability analysis was conducted using remote sensing and Geoscientific Information System (GIS) as a part of natural hazard assessment around Chungju area. Landsat TM band 5 and 7 which contain more information about geological structure and geography are chosen and processed to analyse regional geological structure. Through image processing technique such as PCA, HFF, edge detection and enhancement, regional lineament can be mapped and identified. The lineament density map is constructed based on summed length of lineaments per unit area and the study area can be divided into 7 structural domains. Various factors of slope stability analysis such as geology, slope aspect, degree of slope, landcover, water shed as well as characterized structural domain are constructed as a database of GIS. Rating and weighting of each factor for slope stability analysis is decided by considering environmental geological characteristics of study area. Spatial analysis of regional slope stability is examined through overlaying technique of the GIS. The result of areal distribution of slope stability shows that the most unstable area is all over Jaeogae-ni, Hyangsan-ni and Mt. Daedun.

• Journal of Industrial Technology
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• v.6
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• pp.33-38
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• 1986

The aim of this study is to find out the relationships between the microstructures of SM45C(AISI1045) steel and fatigue crack propagation behaviour. Three microstructures such as (i) as received (fully annealed). (ii) water quenched and tempered, and (iii) oil quenched and tempered were used for fundamental mechanical testing and fatigue crack proagation test. The microstructures of (ii) and (iii) showed superior in tensile strength to (i). Resistance against fatigue crack propagation was higher in structure (i), while tensile properties were better in structures (ii) and (iii). It is believed due to that the enhancement of roughness of fracture surface obsered in structure (i) increases ${\Delta}Kth$ and lowers fatigue crack growth rate. However it does not necessarily mean the quenched and tempered structures (ii) and (iii) are undesirable for the engineering component because fatigue limit in low cycle test appears usually higher in the microstructures of higher strength.

• Advances in materials Research
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• v.5 no.3
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• pp.181-192
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• 2016

In this work effect of high energy milling on the structural and electrical properties of $Ba(Fe_{1/2}Ta_{1/2})O_3$ (BFT) ceramic synthesized using standard solid-state reaction method were investigated. X-ray diffraction studies indicated that the unit cell structure for all the samples to be hexagonal (space group: P3m1). FTIR spectra also confirmed the formation of BFT without any new phase. The milled (10 h) BFT ceramic showed the formation of small grain sizes (<$2{\mu}m$) which is beneficial for dielectric applications in high density integrated devices. Besides, the milled (10 h) BFT ceramic sample exhibited superior dielectric properties (enhancement in ${\varepsilon}^{\prime}-value$ and reduction in $tg{\delta}-value$) compared to un-milled one. Impedance analysis indicated the negative temperature coefficient of resistance (NTCR) character. The correlated barrier hopping model (jump relaxation type) is found to successfully explain the mechanism of charge transport in present ceramic samples.

• Proceedings of the KSME Conference
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• 2003.11a
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• pp.508-513
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• 2003

Experiments are performed to investigate the detailed structure of underexpanded twin jet impinging on a perpendicular flat plate. The major parameters, such as nozzle operating pressure and nozzle spacing, are varied to create different jet flow fields resulted from the complicated interactions of the twin jets. From the surface pressure measurements and shadowgraphs taken by schlieren optical system, the jet structure is strongly dependent on the nozzle operation pressure and the spacing. The results obtained show that the closer nozzle spacing may induce to decrease the diameter of the Mach disk within the first shock cell in the underexpanded twin jet. With the increasing nozzle operating pressure and decreasing the nozzle spacing, a new shock wave appears at the entrainment region between the two jets, due to the enhancement of mixing effect of the both jets. The closer nozzle spacing makes the overall impinging pressure level higher, while severe pressure oscillation along the axis of symmetry. Furthermore it is recommended the wider spacing to obtain higher thrust under the present experimental conditions.

• Atmosphere
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• v.19 no.4
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• pp.297-307
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• 2009

The synoptic structures and the dynamic and thermodynamic characteristics of Changma in 2007 are investigated using the ECMWF analysis data and the radiosonde data from KEOP-2007 IOP. The enhancement of the North-Pacific High into the Korean peninsula and the retreat of the Okhotsk High are shown during the onset of Changma and the change of wind component from southwesterly to northwesterly is appeared during the end of Changma. The baroclinic atmosphere is dominant during Changma at most regions over the Korean peninsula except at Gosan and Sokcho. The quasi-barotropic atmosphere is induced at Gosan by warm air mass and Sokcho by cold air mass. Precipitation in the Korean peninsula occurs when dynamic instability is strengthened as the baroclinic and qusi-barotropic structure is weakened. An empirical orthogonal function (EOF) analysis is performed to find the dominant modes of variability in Changma. The first EOF explains the onset of Changma. The second EOF is related to the discrimination for existence and nonexistence of precipitation during Changma period according to the alternation of equivalent potential temperature between middle and lower atmosphere.