• Proceedings of the KSME Conference
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• 대한기계학회 2002년도 학술대회지
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• pp.687-690
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• 2002

Multimode boundary-layer transition on a NACA0012 airfoil is experimentally investigated under periodically passing wakes and the moderate level of free-stream turbulence. The periodic wakes are generated by rotating circular cylinders clockwise or counterclockwise around the airfoil. The free-stream turbulence is produced by a grid upstream of the rotating cylinder, and its intensity(Tu) at the leading edge of the airfoil is $0.5\;or\;3.5\;{\%}$. The Reynolds number ($Re_c$) based on chord length (C) of the alrfoil is $2.0{\times}10^5$, and Strouhal number ($St_c$) of the passing wake is about 0.7. Time- and phase-averaged streamwise mean velocities and turbulence fluctuations are measured with a single hot-wire probe, and especially, the corresponding wall skin friction is evaluated using a computational Preston tube method. The wake-passing orientation changes pressure distribution on the airfoil in a different manner irrespective of the free-stream turbulence. Regardless of free-stream turbulence level, turbulent patches for the receding wakes propagate more rapidly than those for the approaching wake because adverse pressure gradient becomes larger. The patch under the high free-stream turbulence ($Tu=3.5{\%}$) grows more greatly in laminar-like regions compared with that under the low background turbulence ($Tu=0.5{\%}$) in laminar regions. The former, however, does not greatly change the original turbulence level in the very near-wall region while the latter does it. At further downstream, the former interacts vigorously with high environmental turbulence inside the pre-existing transitional boundary layer and gradually lose his identification, whereas the latter keep growing in the laminar boundary layer. The calmed region is more clearly observed under the lower free-stream turbulence level and for the receding wakes. The calmed region delays the breakdown further downstream and stabilizes more the boundary layer.

• Progress in Medical Physics
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• 제17권4호
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• pp.260-267
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• 2006

A retinal ganglion cell's receptive field is defined as that region on the retinal surface In which a light stimulus will produce a response. A retinal ganglion cell peers out at a small patch of the visual scene through its receptive field and encodes local features with action potentials that pass through the optic nerve to higher centers. Therefore, defining the receptive field of a retinal ganglion cell is essential to understand the electrical characteristics of a ganglion cell. Distribution of receptive fields over retinal surface provides us an Insight how the retinal ganglion cell processes the visual scene. In this paper, we provide the details how to reconstruct the receptive field of a retinal ganglion cell. We recorded the ganglion cell's action potential with multielectrode array when the random checkerboard stimulus was applied. After classifying the retinal waveform Into ON-cell, OFF-cell, ON/OFF-cell, we reconstructed the receptive field of retinal ganglion cell with Matlab. Here, we show the receptive fields of ON-cell and OFF-cell.

• Journal of the Korean Applied Science and Technology
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• 제29권4호
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• pp.552-560
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• 2012

Drug delivery technologies are patent protected formulation technologies that modify drug release profile, absorption, distribution, and elimination for the benefit of improving product efficacy and safety, as well as patient convenience and compliance. The most commonly used transdermal system is the skin patch using various types of technologies. Compared with other method of dosage, it is possible to use for a long term. It is also possible to stop the drug dosage are stop if the drug dosage lead to side effect. Polysaccharide, such as karaya gum and locust bean gum(LBG)/water-soluble chitosan oligomer(WSCO) were selected as base materials of TDS. Also, these polymers were characterized in terms of enhancers, tacrine contents. Among these polysaccharide, the permeation rate of karaya gum matrix was fastest in tacrine such as lipophilic drug in vitro. We used glycerin, PEG 400, and PEG 800 as enhancers. Therefore, transdermal absorption of tacrine could be improved by changing vehicle composition or by using penetration enhancers. Especially it would be anticipated that the high permeation efficacy could be obtained by using vehicle that has enhancing effect for itself and by adding enhancers to it.

• Journal of the Korean Society of Clothing and Textiles
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• 제30권1호
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• pp.157-166
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• 2006

The human body, which is composed of concave and convex curvatures, makes it difficult to transfer into 2D patterns directly from 3D data. In previous studies. Jeong, et al.(2004) suggested the block method was fester and easier when dealing with the triangular patches of male's upper dress form. Although the block method is useful to make a pattern, the information(area, length, etc.) from a 2D pattern would be different depending on the direction of the block method. As a result horizontal and diagonal block methods were suggested as optimal methods for 2D tight-fitting patterns. These block methods were closer to the original area of the 3D scan data than the vertical block method. The total area of the 2D pattern obtained by the horizontal and diagonal block methods showed little differences. In case of the horizontal and diagonal block methods, the total error of the 2D pattern area ranged from $0.01\%\~0.25\%$. In comparing the length of the 2D pattern with that of the 3D scan data, the obtained 2D pattern was $0.1\~0.2cm$ shorter than the 3D scan data, which was within the acceptable range of errors in making clothes. 3D space distribution images between the body surface and the experimental clothing were also measured and $3\%$ enlargement of the original pattern was verified as the adequate adjustment.

• Journal of the Society of Naval Architects of Korea
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• 제29권2호
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• pp.48-59
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• 1992

In this paper, the effects of a skirt deformation on the responses of an Air Cushion Vehicle in waves are investigated. The air in the bag and in the plenum chamber is assumed to be compressible and to have a uniform instantaneous pressure distribution in each volume. The free surface deformation is determined in the framework of linear potential theory by replacing the cushion pressure with the pressure patch moving uniformly with an oscillating strength. And the bag-finger skirt is assumed to be deformed due to the pressure disturbance while its surface area remained constant. The restoring force and moment due to the deformation of bag-finger skirt from the equilibrium shape is included in the equations of hearse and pitch motions. The numerical results of motion responses due to various ratios of the bag and cushion pressure or bag-to-finger depth ratios are shown.

• The Transactions of The Korean Institute of Electrical Engineers
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• 제65권12호
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• pp.2270-2277
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• 2016

In modern society, creation and distribution of multimedia contents is being actively conducted. These multimedia information have come out the enormous amount daily, the amount of data is also large enough it can't be compared with past text information. Since it has been increased for a need of the method to efficiently store multimedia information and to easily search the information, various methods associated therewith have been actively studied. In particular, image search methods for finding what you want from the video database or multiple sequential images, have attracted attention as a new field of image processing. Image retrieval method to be implemented in this paper, utilizes the attribute of corner patches based on the corner points of the object, for providing a new method of efficient and robust image search. After detecting the edge of the object within the image, the straight lines using a Hough transformation is extracted. A corner patches is formed by defining the extracted intersection of the straight line as a corner point. After configuring the feature vectors with patches rearranged, the similarity between images in the database is measured. Finally, for an accurate comparison between the proposed algorithm and existing algorithms, the recall precision rate, which has been widely used in content-based image retrieval was used to measure the performance evaluation. For the image used in the experiment, it was confirmed that the image is detected more accurately in the proposed method than the conventional image retrieval methods.

• The Korean Journal of Physiology and Pharmacology
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• 제5권1호
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• pp.1-8
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• 2001

Hyperpolarization of arterial smooth muscle by acetylcholine is considered to be produced by the release of an unidentified chemical substance, an endothelium-derived hyperpolarizing factor (EDHF). Several chemicals have been proposed as the candidate for EDHF. However, none of them fulfil completely the nature and property of EDHF. Ultrastructural observation with electron microscope reveals that in some arteries, gap junctions are formed between endothelial and smooth muscle cells. In small arterioles, injection of gap junction permeable dyes into an endothelial cell results in a distribution of the dye to surrounding cells including smooth muscle cells. These observations allow the speculation that myoendothelial gap junctions may have a functional significance. Simultaneous measurement of the electrical responses in both endothelial and smooth muscle cells using the double patch clamp method demonstrates that these two cell types are indeed electrically coupled, indicating that they behave as a functional syncytium. The EDHF-induced hyperpolarization is produced by an activation of $Ca^{2+}-sensitive\;K^+-channels$ that are inhibited by charybdotoxin and apamin. Agonists that release EDHF increase $[Ca^{2+}]_i$ in endothelial cells but not in smooth muscle cells. Inhibition of gap junctions with chemical agents abolishes the agonist-induced hyperpolarization in smooth muscle cells but not in endothelial cells. All these observations can be explained if EDHF is an electrotonic signal propagating from endothelium to smooth muscle cells through gap junctions.

• Korean journal of applied entomology
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• 제60권2호
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• pp.247-254
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• 2021

An outbreak of the onion thrips, Thrips tabaci, was observed in welsh onion cultured in greenhouse during winter season (Jan ~ Feb). The thrips was identified using DNA barcode. Weekly occurrence was around 240 ~ 700 adults per trap. Trap color gave significant influence on the capture efficiency with a preference on yellow compared to blue sticky trap. Subsequently, most (> 90%) onions exhibited a damage symptom induced by the thrips. This outbreak was observed only in a specific area but not in nearby greenhouses. This discontinuous occurrence pattern was further investigated by analyzing flight behavior through in- and out- door tests. About 1.5 mm-body length adults could jump up to about 5 cm and fly up to 2 m in altitude, which was the top of the greenhouse. This suggested their migrating potential to nearby (< 2 m) greenhouses. However, few were detected in the neighboring places probably due to physical hindrance with low temperatures between greenhouses. This is reasoned why the onion thrips forms a patch distribution among greenhouses during winter season.

• KOREAN JOURNAL OF CROP SCIENCE
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• 제64권2호
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• pp.159-164
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• 2019

Weed control is a crucial practice not only in organic farming, but also in modern agriculture because it can lead to loss in crop yield. In general, weed is distributed in patches heterogeneously in the field. These patches vary in size, shape, and density. Thus, it would be efficient if chemicals are sprayed on these patches rather than spraying uniformly in the field, which can pollute the environment and be cost prohibitive. In this sense, weed detection could be beneficial for sustainable agriculture. Studies have been conducted to detect weed patches in the field using remote sensing technologies, which can be classified into a method using image segmentation based on morphology and a method with vegetative indices based on the wavelength of light. In this study, the latter methodology has been used to detect the weed patches. As a result, it was found that the vegetative indices were easier to operate as it did not need any sophisticated algorithm for differentiating weeds from crop and soil as compared to the former method. Consequently, we demonstrated that the current method of using vegetative index is accurate enough to detect weed patches, and will be useful for farmers to control weeds with minimal use of chemicals and in a more precise manner.

• The Korean Journal of Ecology
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• 제27권5호
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• pp.257-261
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• 2004

Juniperus chinensis var. sargentii Henry is a short and creeping evergreen shrub which reaches about 50㎝ in height and occurs in the northeast Asia and in high mountains over the South Korea. Its distribution is restricted, and the number of individuals are gradually decreasing. This study was conducted to estimate spatial pattern, genetic diversity and spatial genetic structure of J. chinensis var. sargentii. A total of 131 clumps were studied in the study area (40m × 60m). The spatial pattern of this population was random (Aggregation index R=1.031). In spite of the small number and the limited distribution, the level of genetic diversity (Shannon's index 1=0.463) was relatively high as compared with those of other plant species with similar ecological characteristics. ISSR genotypes of all individuals were investigated to find the genetic relationship of clumps and genets. Fifteen clumps were composed to be clones, and a total of 116 unique genotypes were composed by separate genets. Spatial autocorrelation analysis using Tanimoto distance showed that the genetic patch was established within 8m. The effect of clonal reproduction on genetic structure was almost nothing.