• The korean journal of orthodontics
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• v.26 no.3
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• pp.281-290
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• 1996

Determination of force system and prediction of side effects from unbent straight wire engaged in edgewise bracket is clinically very difficult because it is statically indeterminate system. This study is to develop a linear beam theory that explains the force system for straight wire engaged in edgewise bracket regardless of geometry(a/b), material, cross section of wire, and interbracket distance. 1. Formula for force system of bilateral fixed end beam was derived. 2. It is possible to calculate force system of each tooth engaged in continuous straight wire. 3. The possibility and location of permanent deformation can be predicted.

• Journal of the Korean Vacuum Society
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• v.18 no.1
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• pp.44-48
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• 2009

The effect of temperature gradient between the substrate and ambient gas on the structural characteristics of GaN nanorods grown on r-plane sapphire substrates by hydride vapor phase epitaxy was investigated. The density, diameter, and length strongly depended on the tempearture gradient. In addition, the cross-sectional shape of the nanorrods at the end of growth was found to be more dependedent on the temperature of a substrate itself than the temperature gradient.

• Journal of the Korean Geotechnical Society
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• v.19 no.2
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• pp.15-25
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• 2003

To evaluate the effect of trapped air bubbles in horizontal drains on discharge capacity, unsaturated discharge capacity tests are carried out for four types of drains selected according to the size of section as well as the shape of core. Unsaturated discharge capacities with the elapse of time, the increase of confining pressures, and hydraulic gradients are examined and are compared with saturated discharge capacities. It is found that the unsaturated discharge capacities at a hydraulic gradient of 0.01 decreased by 17%~80% due to the remained air bubbles in the drains compared with the saturated discharge capacities. It is caused by the fact that the horizontal direction of water flow is not consistent with the direction of movement of floating air bubbles in case of horizontal drains. Especially, far the drain with filament shaped core, discharge capacities decreased significantly due to the difficulty in removing air bubbles.

• Journal of the Korean Wood Science and Technology
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• v.31 no.4
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• pp.1-7
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• 2003

Anatomical and physical characteristics of damaged wood by forest fire and sound wood of Pinus densiflora were examined. Granular substances were found in resin canals, epithelial cells and ray parenchyma cells of damaged wood, but the other distinctive marks of wood structure in damaged wood were not observed. Damaged wood showed slightly higher relative crystallinity in outermost growth ring than sound wood. Green moisture content and water absorptions both in tangential and radial sections of damaged wood were lower than those of sound wood. There were no significant differences in shrinkage, swelling and basic density between damaged and sound woods.

• Journal of the Korean Society of Radiology
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• v.2 no.2
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• pp.31-38
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• 2008

Line scan diffusion weighted imaging (LSDI) pulse sequence for 0.32 T magnetic resonance imaging (MRI) system was developed. In the LSDI pulse sequence, the imaging volume is formed by the intersection of the two perpendicular planes selected by the two slice-selective $\pi$/2-pulse and $\pi$-pulse and two diffusion sensitizing gradients placed on the both side of the refocusing $\pi$-pulse and the standard frequency encoding readout was followed. Since the maximum gradient amplitude for the MR system was 15 mT/m the maximum b value was $301.50s/mm^2$. Using the developed LSDI pulse sequence, the diffusion weighted images for the aqueous NaCl solution phantom and triacylglycerol solution phantom calculated from the line scan diffusion weighted images gives the same results within the standard error range (mean diffusivities = $963.90{\pm}79.83({\times}10^{-6}mm^2/s)$ at 0.32 T, $956.77{\pm}4.12({\times}10^{-6}mm^2/s)$ at 1.5 T) and the LSDI images were insensitive to the magnetic susceptibility difference and chemical shift.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.17 no.3
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• pp.319-332
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• 2004

Due to their high strength to weight ratios and excellent durability, fiber reinforced polymer(FRP) is widely used in construction industries. In this paper, a shape optimum design of FRP bridge decks haying pultruded cellular cross-section is presented. In the problem formulation, an objective function is selected to minimize the volumes. The cross-sectional dimensions and material properties of the deck of FRP bridges are used as the design variables. On the other hand, deflection limits in the design code, material failure criteria, buckling load, minimum height, and stress are selected as the design constraints to enhance the structural performance of FRP decks. In order to efficiently treat the optimization process, the cross-sectional shape of bridge decks is assumed to be a tube shape. The optimization process utilizes an improved Genetic Algorithms incorporating indexing technique. For the structural analysis using a three-dimensional finite element, a commercial package(ABAQUS) is used. Using a computer program coded for this study, an example problem is solved and the results are presented with sensitivity analysis. The bridge consists of a deck width of 12.14m and is supported by five 40m long steel girders spaced at 2.5m. The bridge is designed to carry a standard DB-24 truck loading according to the Standard Specifications for Highway Bridges in Korea. Based on the optimum design, viable cross-sectional dimensions for FRP decks, suitable for pultrusion process are proposed.

• KIPS Transactions on Software and Data Engineering
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• v.7 no.10
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• pp.377-382
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• 2018

This study deals with internal state and tissue density analysis methods for red ginseng grade determination. For internal measurement of red ginseng, there have been various studies on nondestructive testing methods since the 1990s, It was difficult to grasp the most important inner hole and inside whites in the grading. So in this study, we developed a closed capturing device for infra-red illumination environment, and developed an internal measurement system that can detect the presence and diameter of inner hole and inside whites. Made devices consisted of infrared lights with a high transmission rate of red ginseng in 920 nanometer wave band, a infra-red camera and a Y axis actuator with a red ginseng automatically controlled focus on the camera. The proposed algorithm performs an auto-focus system on the Y-axis actuator to automatically adjust the sharp focus of the object according to the size and thickness. Then red ginseng is rotated $360^{\circ}$ at $1^{\circ}$ intervals and 360 total images are acquired, and reconstructed as a sinogram through Radon transform and Back-projection algorithm was performed to acquire internal images of red ginseng. As a result of the algorithm, it was possible to acquire internal cross-sectional image regardless of the thickness and shape of red ginseng. In the future, if more than 10,000 different shapes and sizes of red ginseng internal cross-sectional image are acquired and the classification criterion is applied, it can be used as a reliable automated ginseng grade automatic measurement method.

• Geophysics and Geophysical Exploration
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• v.17 no.1
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• pp.21-27
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• 2014

We analyzed response patterns of test field data acquired with new small loop electromagnetic (EM) system using three-dimensional (3D) electromagnetic modeling code. The size and shape of a conductor was adopted as experimental parameters for EM modeling to understand influencing factors of the response patterns due to a metallic object on the seafloor. Obtaining the responses for four models of difference sizes and shapes through 3D EM modeling, we confirmed that the shape of the object have a more critical factor on the response pattern than size. We also calculated "ppm" values with respect to different altitudes of the sensor and source frequencies. The modeling results show that the consistency of sensor altitude is important and imaginary part of ppm response is more sensitive than real part. We also visualized the contour map of the real and imaginary part of ppm value as a function of frequency and altitude so that we can estimate proper altitude for source frequency band of our survey system. The results of this paper are anticipated to give proper parameters in survey construction for seafloor massive sulfide deposit.

• Korean journal of applied entomology
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• v.34 no.3
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• pp.266-277
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• 1995

The adult brown planthopper possesses tow oval shaped compound eyes which, on their ventral borders, curve around the base of the antennae. Compound eye of the adult brown planthopper is recognised apposition eye which each ommatidium is optically isolated from it surroundings, the rhabdoms receiving light only from their own corneal lens. Each ommatidium possesses its own dioptric apparatus formed from the cuticular cornea and an underlying crystalline cone. The retinula cells lying immediately beneath the crystalline cone have their individual rhabdomeres tightly opposed to form one central, closed rhbdom. The rhabdom stretches from the spex of the crystalline cone nearly to the basement membrane and is approximately 110~120 $\mu\textrm{m}$ in length. The crystalline cone is surrounded by a pair of primary pigment cells an these in turn are surrounded by accessory pigment cells. Accessory pigment cells extend beyond the crystalline cone surrounding the retinular cells in the distal region of the eye. The crystalline cone is surrounded by the distal-most regions of the retinula cells show the presence of seven cells and sections taken proximally in the last quarter of the omatidium before the basement membrane is reached, reveal the presence of a small, eighth retinula cell which also contributes to the central rhabdom. Each ommatidium has a central rhabdom formed from the modified inner border of all of the retinula cells. Th rhabdom consists of micrvilli arising from the inner wall of each retinula cell. In cross section th microvilli exhibit a characteristic honeycomb appearance. Pigment cells comprise the primary pigment cells enveloping the crystalline cone, the accessory pigment cells extending from the inner surface of the comea to the basement membrane and the small pigment cells of the basement membrane.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.17 no.4
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• pp.325-331
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• 2016

Computational fluid numerical analysis using the commercial code CFX was performed to develop a Pelton turbine for a pico hydro power generator using the circulating water of a cooling tower in a large building. The performance of the Pelton turbine was examined for different design factors, such as the bucket shape, in which the Pelton wheel was connected in an appropriate manner to the pipe section, and the number of buckets in order to find the optimal design of Pelton turbine for a pico hydro power using surplus water. A benchmark test was carried out on the manufactured small scale Pelton turbine to validate the design method of the Pelton turbine by numerical analysis. The results obtained by comparing the flow characteristics and power output measured using the ultrasonic flowmeter, the pressure transducer and the oscilloscope with the numerical results confirmed the validity of the analytical design method. The possibility of developing Pelton turbines for kW class pico hydro power generators using surplus water with an average circulation velocity of 1.2 m/s for the chosen bucket shape and number of buckets in a 30 m high building was confirmed.