• Journal of Korean Neurosurgical Society
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• v.58 no.5
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• pp.442-447
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• 2015

Objective : Ossification of the ligamentum nuchae (OLN) is usually asymptomatic and incidentally observed in cervical lateral radiographs. Previous literatures reported the correlation between OLN and cervical spondylosis. The purpose of this study was to elucidate the clinical significance of OLN with relation to cervical ossification of posterior longitudinal ligament (OPLL). Methods : We retrospectively compared the prevalence of OPLL in 105 patients with OLN and without OLN and compared the prevalence of OLN in 105 patients with OPLL and without OPLL. We also analyzed the relationship between the morphology of OLN and involved OPLL level. The OPLL level was classified as short (1-3) or long (4-6), and the morphologic subtype of OLN was categorized as round, rod, or segmented. Results : The prevalence of OPLL was significantly higher in the patients with OLN (64.7%) than without OLN (16.1%) (p=0.0001). And the prevalence of OLN was also higher in the patients with OPLL (54.2%) than without OPLL (29.5%) (p=0.0002). In patients with round type OLN, 5 of 26 (19.2%) showed long level OPLL, while in patients with larger type (rod and segmented) OLN, 22 of 42 (52.3%) showed long level OPLL (p=0.01). Conclusion : There was significant relationship between OLN and OPLL prevalence. This correlation indicates that there might be common systemic causes as well as mechanical causes in the formation of OPLL and OLN. The incidentally detected OLN in cervical lateral radiograph, especially larger type, might be helpful to predict the possibility of cervical OPLL.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.38 no.4
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• pp.443-449
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• 2014

To check the characteristics of nuclear fuels during an irradiation test, the nuclear fuel rod needs to be disassembled from the test rig located in the pool of the research reactor. Then, the disassembled fuel rod is delivered to the hot cell for intermediate examination. A fuel rod that passes the intermediate examination is delivered to the reactor pool to be reassembled into the test rig. The irradiation test is resumed with the reassembled test rig. Because nuclear fuel rods irradiated by neutrons are highly radioactive, all the disassembly and reassembly processes should be carried out in the pool of the research reactor to prevent operators being exposed to radiation. In particular, because a test rig is 5.4-m long and the reactor pool of HANARO is 6-m deep, special tools need to be developed for performing the disassembly and reassembly processes. In this study, a new assembly design of nuclear fuel rods for intermediate examination is introduced. Furthermore, tools for treating the irradiated fuel rod assembly are introduced, and their performance is verified by an out pile test.

• Proceedings of the Korean Society of Surveying, Geodesy, Photogrammetry, and Cartography Conference
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• 2004.04a
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• pp.77-82
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• 2004

This study deals with the estimation of dredged soil-quantity using DGPS＆Echo-Sounder method. In measurement of topography, surveyors have been surveying the depth with rod and sounding lead. This method, however, is not effective because of long time and a lot of human power, in addition it is incorrect. This paper has studied on the solution of those problems using DGPS＆Echo-sounder data to calculate the dredged soil-quantity. This paper says the effective and economical methods using DGPS＆Echo-Sounder data there.

• Macromolecular Research
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• v.17 no.4
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• pp.280-283
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• 2009

• Korean Journal of Optics and Photonics
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• v.16 no.3
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• pp.191-195
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• 2005

An optical fiber device is fabricated that is formed LPFGs only where pressure is applied, and the characteristics of the device are investigated. The fabricated device is composed of a 60cm-long metallic rod, with long period gratings of $720\;{\mu}m$ on the upper side and a rubber cover. In this device, gratings are only formed when pressure was applied to a spot, to which pressure was applied, and the formed gratings had the same transmission property regardless of spot, to which pressure was applied. We measured the optical transmission property of the fabricated device and found its usability as an optical fiber load sensor to measure weight.

• Journal of the Korean Society of Manufacturing Technology Engineers
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• v.21 no.4
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• pp.677-682
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• 2012

For the product with small diameter, long column, and parabolic shape, the forging formability of the high-carbon steel wire rod was investigated in this study. By using the three-dimensional finite element method, the formability of wire was reviewed by forming analysis for the desired parabolic shape of local part. Analysis results due to forging direction, forging velocity, friction coefficient and constraint location were also investigated. On the basis of these results, it is noted that the forging direction has the big influence when the product with long column is forged. As the forging velocity increases, buckling tends to be limited and formability of parabolic shape is improved. By constraining the lower parabolic shape part to suppress plastic strain, the effect depending on friction coefficient is not almost appeared. And good parabolic shape is obtained at the region of the forging velocity of more than 0.5 m/s.

• Proceedings of the KIEE Conference
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• 2005.05a
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• pp.21-23
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• 2005

NARX(Nonlinear AutoRegressive with eXogenous input) neural network was used for prediction of nuclear reactor behavior which was influenced by control rods in short-term period and also by xenon and boron in long-term period in load following operations. The developed model was designed to predict reactor power, xenon worth and axial offset with different burnup rates when control rod and boron were adjusted in load following operations. Data of UCN 3 were collected by ONED94 code. The test results presented exhibit the capability of the NARX neural network model to capture the long term and short term dynamics of the reactor core and seems to be utilized as a handy tool for the use of a plant simulation.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.40 no.3
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• pp.297-304
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• 2016

A numerical simulation has been performed for the penetration of a long-rod penetrator into a metal block (ceramic-tile-inserted 4340-steel plate). The impact velocity is 1.5km/s at a normal incidence angle. The first two validations are conducted for a semi-infinite block measuring the depth of penetration (DOP). The material model of ceramic is the JH-2 (Johnson-Holmquist) model. The predicted DOP values are in close agreement with the experimental data. Then, the primary simulation is performed by varying the position of the confined ceramic tile for three types of thickness of ceramic tile. The residual velocity, residual mass and residual kinetic energy of the long-rod are obtained from the simulation. Based on these predicted values, the trend of the ballistic performance of the protective structure is estimated. In addition, the mass efficiency is calculated in order to determine the performance of the ceramic-tile-inserted metal block. Finally, the optimum protective structure is identified.

• Advances in nano research
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• v.1 no.1
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• pp.59-70
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• 2013

ZnO nanostructures of rod-like, faceted bar, cup-end bars, and spindle shaped morphologies could be grown by a low power ultrasonic synthesis process. pH of the reaction mixture seems to plays an important role for defining the final morphology of ZnO nanostructures. While the solution pH as low as 7 produces long, uniform rod-like nanostructures of mixed phase (ZnO and $Zn(OH)_2$), higher pH of the reaction mixture produces ZnO nanostructures of different morphologies in pure hexagonal wurtzite phase. pH of the reaction as high as 10 produces bar shaped uniform nanostructures with lower specific surface area and lower surface and lattice defects, reducing the defect emissions of ZnO in the visible region of their photoluminescence spectra.

• Korean Journal of Crystallography
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• v.1 no.1
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• pp.29-34
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• 1990

Single crystals of the peritectic compound MgTiO3 up to 8 m diameter and 100mm long along the [1010] axis. were yon by the travelling solvent floating zone technique using a halogen lamp image furnace. The grown single crystal. which shows a solid solution range at high temperature, exsolves TiO2 component if it is annealed very slowly to room termperature. Grown boules were black but become translucent with pinkish brown color after tempering at 1100 t for 8-10 hours in oxygen atmosphere and showed distint chatoyancy along the (0001) plane. The grown crystal can be used as a new modified cat's eye gemstone. The optimum conditions were as follows ;Sintering temperature of the charge rod, 1300℃ the growth rate, 2-2.5mmh and the composition of the charge rod in molar ratio. MgO : TiO2 : 1:1.05.