• Korean Journal of Optics and Photonics
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• v.14 no.1
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• pp.44-50
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• 2003

This paper describes the thermal effect at Nd:YAG using a laser-diode side-pumping. To detect the depolarization loss and the retardation caused by the thermal effect, a λ/4 plate is inserted between the polarizer and the Nd:YAG laser material. Using a CCD has allowed detection of the variation of the beam pattern that could analyze the change of the refractive index of the Nd:YAG laser material by the thermal effect. Through the change of the probe beam power, we know that 21% of the pumping power was converted into heat in the material. The depolarization loss was 24.7% under a temperature of $25^{\circ}C$ of the laser material and a pumping power of 15 W. The inhomogeneous distribution showed that the retardation angle was 7$^{\circ}$ in the center of the material and 19$^{\circ}$ on the edge of it. It is confirmed that the thermal effect is analyzed at the each point of the laser material and it suggests an effective method to reduce the thermal effect on the LD side-pumped laser material.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2007.11a
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• pp.493-494
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• 2007

• Korean Journal of Optics and Photonics
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• v.20 no.5
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• pp.276-280
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• 2009

A Cr:YAG crystal was used as a saturable absorber for passive Q-switching of a Nd:$YVO_4$ laser which was pumped by a 1-W continuous wave laser diode. The first surface of the Cr:YAG was high-reflection coated for the pump wavelength. The high-reflection coating improved the absorption efficiency of the pump beam in the Nd:$YVO_4$ through double pass absorption. It also prevented pump beam induced partial bleaching of the Cr:YAG. The peak-to-peak pulse fluctuation of passively Q-switched laser output was approximately 4 %. The minimum pulse-width was measured to be 7.11 ns. Also, the average pulse repetition rate was 9 kHz and the maximum output power was 16.27 mW.

• Korean Journal of Organic Agriculture
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• v.6 no.1
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• pp.99-108
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• 1997

The aim of this experiment was to investigate the effect of applying times of cattle slurry on dry matter yield of Orchardgrass, when cattle slurry applied at rates of 30m3(average mineral nitrogen fertilizer equivalent to 120kg) per ㏊ in different dressing times, such as S1(1st and 2nd growth), S2(1st and 3rd growth), S3(1st and 4th growth), S4(2nd and 3rd growth), S5(2nd and 4th growth) and S6(application for 3rd and 4th growth). The results were as follows. 1. The average annual yields of dry matter were produced 6.36~7.42 ton per ㏊ in 1995~1997 when cattle slurry applied at rates of 30m3(average mineral nitrogen fertilizer equivalent to 120kg) per ㏊ in different dressing times, especially these tendency were shown higher annual dry matter in S4 plot9application for 2nd and 3rd growth). Those were higher 2.48~3.54 tons or 1.22~2.28 tons per ㏊ than the yields from non-fertilizing or phosphrous and potassium fertilizing. 2. Relative yields of annual dry matter in cattle slurry application plots were 164(S2 plot)~191(S4 plot)% in comparing with non-fertilizing plot. 3. Dry matter yields according to cutting frequency were highest at the 2nd cut(1.50 ton) and were in the order 3rd cut(0.95 ton)>4th cut(0.75 ton)>1st cut(0.69 ton/㏊). Also, those of cattle slurry application plot per ㏊ were in the order 2nd cut(2.02~2.73 tons)>3rd cut(1.56~2.08 tons)>4th cut(1.07~1.68 tons)>1st cut(1.11~1.45 tons/㏊). 4. Relative yields of annual dry matter in cattle slurry application plots were 164~219, 161~210, 143~212 and 135~182% at the 3rd, 1st, 4th and 2nd cut, respectively in comparing with non-fertilizing plot. 5. The efficiencies of nitrogen on dry matter yield(kg DM/kg N) were 18.1, 21.3 and 34.5kg DM/kg N when cattle slurry applied to Orchardgrass at rates of 30m3 (average mineral fertilizer equivalent to 120 kg) per ㏊ in 1993, 1994 and 1995, respectively, especially these tendency were shown higher efficiencies in S4 plot(application for 2nd 3rd growth). On the other hand, those of the same level fertilization of mineral nitrogen were 43.8, 19.2 and 13.4 kg DM/kg N in 1993, 1994 and 1995, respectively.

• Journal of Food Hygiene and Safety
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• v.2 no.3
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• pp.121-136
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• 1987

As a part of continuing monitoring program since 1983, a study on pesticide residues on Korean agricultural products has been conducted to offer the tolerance of pesticide residues suiting Korean reality. The samples used in this experiment were collected from four areas in five provinces of Korea. The residue, levels of organochlorine pesticide (two kinds), organophosphoric pesticide (eight kinds) and carbamate pesticide (three kinds) on lettuce, garland chrysanthemum, radish Korean, potato, egg plant, green onion, persimmon and sweet potato, and the residue levels of captan and captafol on tomato, green pepper fresh, apple, peach, soybean, cucumber and cabbage Korean were determined by GC-NPD and ECD.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2005.11a
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• pp.130-131
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• 2005

In the era of submicron devices, super ultra thin gate oxide characteristics are required. Titanium silicide process has studied gate oxide reliability and dielectric strength characteristics as the composition of gate electrode. In this study the author observed process characteristics on MOS structure. In view point of the process characteristics of MOS capacitor, the oxygen & Ti, Si2 was analyzed by SIMS analysis on before and after annealing with 1,2 step silicidation, the Ti contents[Count/sec]of $9.5{\times}1018$ & $6.5{\times}1018$ on before and after 2'nd anneal. The oxygen contents[Count/sec] of $4.3{\times}104$ & $3.65{\times}104$, the Si contents[Count/sec] of $4.2{\times}104$ & $3.7{\times}104$ on before and after 2'nd anneal. The rms value[A] was 4.98, & 4.03 on before and after 2'nd anneal.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.18 no.1
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• pp.1-4
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• 2008

The growth of composite-structured Nd:$GdVO_4$ single crystal rods by the double die EFG method is reported. Two crucibles are combined with an outer and inner die for ascending of different melt. The composite-structured Nd:$GdVO_4$ single crystal rods with a length of 50 mm and an outer diameter of 5 mm including of inner Nd-doped core region with diameter 3 mm were grown successfully. Nd distribution in the, radial direction has graded profile from result of EPMA. Absorption coefficient in the core region at 808 nm was $42cm^{-1}$. Finally, we demonstrated the laser oscillation using our composite crystal and 2-W output was obtained.

• Proceedings of the Korea Information Processing Society Conference
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• 2012.11a
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• pp.732-735
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• 2012

본 논문은 지상에서 발생하는 전자파 잡음 신호의 유입에 의해 많은 영향을 받을 수 있는 헬기 등 항공기의 레이더경보수신기(Radar Warning Receiver)에서도 레이더 펄스 신호를 탐지할 수 있는 통신전자파잡음 동적제거 기법을 제안하였다. 본 논문은 지상의 노이즈 신호를 분류하는 방법을 제시하였고, 노이즈 신호 레벨을 판단하여 효과적으로 잡음을 제거하는 알고리즘을 제안하였다.

• Journal of the Korean Magnetics Society
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• v.8 no.5
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• pp.271-274
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• 1998

Spin reorientation and magnetocrystalline anisotropy of magnetically aligned $(Nd_{1-x}R_x)_2Fe_{14}B$ (R=Y, Pr) power were studied. The spin reorientation temperature $(T_{SR})$ of $(Nd_{1-x}R_x)_2Fe_{14}B$ decreases linearly by increasing Pr-substitution with the ratio of ${\Delta}T_{SR}=-1.35$ K/Pr at.% in composition range of 0$\leq$x$\leq$0.75. The spin reorientation temperature of $(Nd_{1-x}R_x)_2Fe_{14}B$ decreases by increasing Pr-substitution to 118 K (x=0.5) then increases to 122 K (x=0.75). The spin reorientation angle at 4.2 K decreases by increasing rare earth substitution with the ratio of $\Delta$SRA=-0.073$^{\circ}$/Y at.% and $\Delta$SRA=-0.258$^{\circ}$/Pr at.% in composition range of 0$\leq$x$\leq$0.5. The spin reorientation is expected to disappear at x$\geq$0.9 in case of $(Nd_{1-x}R_x)_2Fe_{14}B$ and at x$\geq$0.8 in case of $(Nd_{1-x}R_x)_2Fe_{14}B$.

• Transactions on Electrical and Electronic Materials
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• v.3 no.3
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• pp.21-24
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• 2002

Two kinds of $Nd_{1+X}Ba_{2-X}Cu_3O_{7-{\delta}}$, the sintering samples and zone melting samples, were heat-treated under pure Ar at 950$^{circ}C$. The substitution of Nd ion for Ba ion in the $Nd_{1+X}Ba_{2-X}Cu_3O_{7-{\delta}}$ before and after the heat treatment was investigated by XRD. In order to confirm the effects of the heat treatment, the Tc and Jc of samples with/without the heat treatment under Ar were comparatively studied. $Nd_{1+X}Ba_{2-X}Cu_3O_{7-{\delta}}$ samples were oxygenated under pure oxygen at $300^{circ}C$. From the XRD pattern it was found that the sample with x<0.4 was transferred from tetragonal phase to orthorhombic phase after the oxygenation, while the sample with x>0.4 did not show the phase transition even after a long time oxygenation. Therefore, the low oxygen partial pressure (Ar+1 % O$_2$) was used for the ambient atmosphere of the zone-melting samples, which could reduce the melting temperature and depress the substitution of Nd for Ba. After the improvement in the zone-melting process, the Jc value was increased to 2 x $10^4$A/$cm^2$ (0 T, 78 K). The particle orientation and the structure of zone-melted NdBaCuO were studied by the XRD and SEM analysis.