• Korean Journal of Materials Research
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• v.5 no.4
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• pp.483-489
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• 1995

Nd-(Fe, Co)-B합금에 Ni, Al, Ti등을 복합치환하여 그에 따른 산화거동과 자기적 성질의 변화를 조사하였다. 이들 리본의 산호거동은 parabolic한 거동을 나타내고 있으며, Ni 첨가시 매우 낮은 산화량을 나타내었다. 또한 산화된 리본은 Nd-rich상의 우선적 산화에 의해 표면에 요철이 관찰되었으며 Ni 첨가시 그러한 요철은 많이 줄어들었다. 표면의 산화층은 Nd산화물이었고, 이는 입계에 있는 Nd-rich상이 산화되고 이것이 확산 통로로 작용하였다고 생각된다. 산화가 진행됨에 따라 입계상에 의한 domain wall pinning이 약해져 자기특성이 저하하였다. 그러나 Ni 첨가시 이러한 산화거동이 크게 억제되었으며 Ni의 첨가는 Nd-rich상의 산화저항성을 증가시킴으로써 리본의 산화를 억제해 자기특성의 저하를 억제하였다.

• Economic and Environmental Geology
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• v.37 no.2
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• pp.245-253
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• 2004

The 36km-long Daebo-Campo coast has a well-developed marine terraces divided to six steps by elevation of paleoshoreline : 0.5 m(T1), 10 m(T2), 30 m(T3), 40 m(T4), 60 m(T5) and 75 m(T6). The 2$^{nd}$ and 3$^{nd}$ platforms in Daebo to Guryongpo are wider and more distinctive than those of Guryongpo to Gampo. The 3$^{nd}$ terrace of 30 m high is subdivided to two flights as lower(T3b) and upper(T3a) by old sea cliff. Platform age is unclear because of coral fossil free. However, the terrace age could be determined with convergent OSL ages from beach sediments on 2$^{nd}$ step(T2). OSL ages of the terrace of 10 m high range in 60-70 ka. It reveals that the 2$^{nd}$ -step platform correlates to Oxygen Isotope Time scale, substage 5a(ca. 80 ka), and that uplift rate is ca. 0.19 m/ka for 2$^{nd}$ terrace at Daebo-Campo coast. If considering equivalent uplift rate for all terraces since the Late Pleistocene, the 3$^{rd}$ and 4$^{th}$ terraces would be 5e substage and 7 stage. The 30 m-high terrace provides a good indicator for uplift at Daebo-Gampo coast since 125,000 yrs(MIS 5e). It suggests that the local neotectonic deformation might cause an optional uplift rate of ca. 0.19 m/ka along the SE coast of Korea.

• Korean Journal of Crystallography
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• v.11 no.4
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• pp.231-237
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• 2000

CMR Materials RE/sub 1-x/Ca/sub x/MnO₃(RE=La, Nd, A=Ca, Sr) were grown using the floating zone image furnace with halogen lamps as heat source. The growth condition was at 2∼10 mm/hr growth rate in air atmosphere, were 445∼50 rpm and 20∼25 rpm of rotation rate of feedrod and growing crystal, respectively. The grown crystals showed shiny black color and annealed at 1500℃ in a box furnace to release the residual stress during cooling. Characterization analyses of the crystal were carried out using XRD and SEM. The crystal structure of Nd/sub 0.7/Ca/sub 0.3/MnO₃ was analyzed with smart CCD XRD was lattice parameter of a=5.425(4)Å, b=5.434(4)Å, and c=7.712(5)Å, an orthorombic system with space group of pbnm.

• Korean Journal of Optics and Photonics
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• v.1 no.2
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• pp.178-184
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• 1990

The fiber laser was fabricated using Nd doped single mode fiber. The fiber was made by MCVD and solution doping method, and the Fabry-Perot resonator was composed with two dichroic mirrors. It was operated at 1.096 um with 15 nm bandwidth. When the reflectivity of the output copuling mirror was 67.5%. the maxiurn output power 1.88 mw and its slope efficiency 1.28%. was obtained.

• Journal of Magnetics
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• v.5 no.4
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• pp.130-134
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• 2000

Using the current-applied pressure-assisted (CAPk) process, we could obtain fully dense isotropic and anisotropic NdFeB magnets from rapidly quenched MQP-A powder. The Nd content is found to play an important role during the current applied (CA)-pressing and CA-deformation processes. The $(BH)_max$ of CA-pressed and CA-deformed magnets are 131 kJ/$m^3$ (16.5 MGOe) and 352 kJ/$m^3$(44.2 MGOe), respectively. The change in texture of CA-deformed anisotropic NdFeB magnets with thickness reduction was investigated by pole figures and the (006) texture was found to increase with greater thickness reductions. As the thickness reduction increases from 50% to 60% to 80%, $W_50$ (the average angle of the contour with 50% intensity) decreases from $76^\circ$to $62.5^\circ$to $17^\circ$.

• Current Optics and Photonics
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• v.3 no.3
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• pp.243-247
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• 2019

We have developed a compact, wavelength-selectable, Q-switched Nd:YAG laser at mid ultraviolet for chemical warfare agent detection. The fundamental wave at 1064 nm is delivered by a pulsed solid state laser incorporating with a square-type Nd:YAG rod in a resonator closed by two crossed Porro prisms for environmental reliability. The output energy at 213 nm ($5{\omega}$) and 266 nm ($4{\omega}$) by ${\chi}^{(2)}$ process in the sequentially disposed BBO crystals are measured to be 6.8 mJ and 15.1 mJ, respectively. The output wavelength is selected for $5{\omega}$ and $4{\omega}$ by a motorized wavelength switch. The energy ratio of the $5{\omega}$ to the $4{\omega}$ is varied from 0.05 to 0.85 by controlling the phase matching temperature of the nonlinear crystal for sum-frequency generation without change of the output pulse parameters.

• Proceedings of the Optical Society of Korea Conference
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• 1989.02a
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• pp.32-35
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• 1989

A 150W industrial Nd:YAG laser was developed. The thermal lensing effect was examined and the radius and position of rear mirror were optimized for higher efficiency. The efficiency of 2.5% was achieved. Also, the performance of laser welding in fine thermocouples and between high-temperature-melting dissimilar metals were investigated.

• Journal of the Korean Society of Radiology
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• v.14 no.5
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• pp.695-703
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• 2020

The use of medical devices is increasing due to the development of medical technology. Among medical devices, it is often used in the human body for graft and treatment. Therefore, in medical institutions, various sterilization methods according to the type and material of medical devices are applied to prevent infection. Hydrophosphite (HA) materials are the most popular in bone grafts. We would like to present a sterilization method using Q-switch Nd:YAG laser with high output energy among non-ionizing radiation suitable for small medical devices. In this study, sterilization power was most ideally shown at UV wavelengths of 1.5 W, 266 nm, and 10 pulses. Different wavelength bands; infrared and visible light; showed passive sterilization, and ultraviolet A and C showed differences in sterilization according to the pulse. In laser sterilization were differences that found according to the wavelength bands and pulses.

• Korean Journal of Poultry Science
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• v.11 no.1
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• pp.49-64
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• 1984

During the 1978-79 Newcastle disease (ND) epizootic period, a detailed survey was conducted on the five representative farms which had been following one of the recommended vaccination programs. When the disease broke out during laying period, clinical symptoms were mild to moderate respiratory distress and greenish diarrhea. Affected flocks experienced weekly mortality from less than 1% to 17%. Egg production returned to normal 18 to 36 days after the initial signs appeared although some flocks never returned to normal. On postmortem examination,, most affected chickens showed severe hemorrhagic lesions in the duodenum, hematoma on ova, and heavy fat accmulation on various visceral organs. Most of the NO affected flocks had geometric mean hemagglutination inhibition antibody(HIA) titers of 7 log$_2$ or higher two to three weeks after the appearance of clinical signs. These HIA titers were at least 16-fold higher than those before infection. Flock mean HIA titers before infection were usually lower than 3 log$_2$. Severity of clinical signs and anamnestic antibody response were maximum in the flocks whose vaccination immunity was insufficient or waned considerably. Observations showed that even young birds, if properly vaccinated, could get effective protection from field ND exposure.

• Korean Journal of Materials Research
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• v.11 no.7
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• pp.545-549
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• 2001

Glass-ceramics were prepared and evaluated for the properties to expand the scope of application of the rare earth aluminosilicate glasses, A glass-ceramic added with $TiO_2$as a nucleating agent, which was crystallized internally and it was characterized for physical, thermal and mechanical properties of crystal and residual glass in the glass-ceramic, X-ray diffractometer reveals an unknown crystal as $Nd_{4.6}Si_{7.6}Al_{4.0}Ti_{2.4}O_{32}$ which was found in surface and internal crystals dependent on composition and heat treatments. The thermal expansion coefficients of glass-ceramics were $5.4~6.2{\times}10^{-6}/^{\circ}C$, which increased with increasing crystal growth. Considering that the hardness and the elastic constant of crystal in glass-ceramics are 12GPa and 220GPa, respectively, the application of the glass-ceramics would be applicable for structural materials at elevated temperature.