• 한국초전도ㆍ저온공학회논문지
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• 제11권2호
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• pp.1-6
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• 2009

We report a successful fabrication of $high-J_c\;NdBa_2Cu_3O_{7-{\delta}}$ (NdBCO) films on $SrTiO_3$(STO) (100) substrates by pulsed laser deposition (PLD) in a relatively wide processing window. Under various oxygen pressures controlled by either 1%$O_2$/Ar mixture gas or pure $O_2$ gas, strongly c-axis oriented NdBCO films were grown at the substrate temperature $(T_s)\;of\;800^{\circ}C$ in 800 mTorr with 1%$O_2$/Ar gas and also in 400 and 800 mTorr with pure $O_2$ gas. These samples exhibited $T_c$ values over 90K and $J_c$ values of $2.8-3.5MA/cm^2$ at 77K in self-field (77K, sf). On the other hand, $J_c$ values over $1A/cm^2$ were obtained at the temperature regions of $700-830^{\circ}C$ in 800 mTorr with 1%$O_2$/Ar gas at those of $750-830^{\circ}C$ in 800 mTorr with pure $O_2$ gas. Unlike previous reports, resent results support that the PLD processing window for high-Jc NdBCO films is not narrow.

• 대한치과의사협회지
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• 제54권6호
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• pp.414-428
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• 2016

Objectives: The aim of this study was to assess the morphologic characteristics of two types of stainless steel crowns (SSCs) for the first primary molar using a 3D scanner. Study design: Two types of SSCs, KIDS CROWN (KC) and 3M ESPE ND-96 (ND), for the first primary molars were scanned using a 3D scanner. The mesiodistal and buccolingual diameters at the height of the contour and the cervical margin, occlusocervical diameters on the mesial, distal, buccal, and lingual aspects were measured, and the crown shape ratio, the smooth surface crown height ratio, and the cervical convergence were calculated. Results: In the crown shape ratio of the mandibular SSC, KC was larger buccolingually compared with ND. In the smooth surface crown height ratio, ND was larger than KC in all of the maxilla and mesial, distal, and lingual aspects of the mandible. ND was more convergent to the cervical mesiodistally and buccolingually compared with KC. Conclusion: In the superimposed images of the maxillary SSC, the mesiolingual and distolingual line angles of KC were more prominent compared with ND. In the mandible, ND demonstrated higher cusps and more obvious buccal developmental lobes than KC. ND showed a larger cervical undercut than KC.

• 한국광학회:학술대회논문집
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• 한국광학회 2000년도 제11회 정기총회 및 00년 동계학술발표회 논문집
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• pp.44-45
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• 2000

GHz 급의 아주 높은 반복율을 가지면서, 피코초 단위의 펄스 열을 발진시키는 레이저를 만들기 위해 능동형 모드록킹 방법을 이용하였다. 이 방법은 공진기안에 광 변조기를 삽입하고, RF 신호를 가하여 시간적으로 공진기내에서의 손실을 변화시키는 방법이다.$^{(1)}$ 공진기 길이를 충분히 길게 하면서도 고 반복율을 가지는 레이저를 만들기 위해 조화 모드록킹 방법을 사용했는데, 이는 레이저 펄스의 반복율을 공진기 길이에 의한 기본 반복율의 정수배가 되도록 하는 방법이다.$^{(2),(3)}$ 3차 조화 모드록킹 방법을 이용한 Nd:YLF 레이저 시스템을 그림 1에서 나타내었다. (중략)

• 한국광학회지
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• 제14권5호
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• pp.515-520
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• 2003

수 KHz의 반복율로 발진하는 레이저광을 증폭하는 증폭기를 제작하고, 특성을 조사하였다. 증폭기로는 연속 방전하는 섬광등으로 펌핑되는 Nd:YAG 헤드를 사용하였고, 레이저 매질에서 발생하는 열 복굴절을 보상하여 이중통과 증폭기를 구성한 경우, 복굴절에 의한 레이저광 손실을 5%로 감소시켰다. 4 중통과 증폭기를 구성을 하였을 때, 반복율 5-10 KHz에서 이득은 약 3.2이었고, 펄스폭은 40 ns에서 48 ns로. 20%증가하였다.

• 한국해양공학회지
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• 제14권3호
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• pp.41-45
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• 2000

In solving the unsteady potential flow problem of the ship in waves with the panel method, in general one can consider the basic flow as the free stream or double body solution. For the double body solution, the body boundary condition has the 2nd derivatives of the velocity potential. Low order panel methods are known to suffer from the significant error in the 2nd derivatives computed at the body surface. This paper analyzes the numerical error in the 2nd derivatives for a 2-D cylinder and a 3-D sphere problem, and an extrapolation method to obtain the correct derivatives on the body surface is suggested.

• Current Optics and Photonics
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• 제3권2호
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• pp.172-176
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• 2019

The work reports on the fabrication of an optical planar waveguide in the Nd:CNGG crystal by the 0.4-MeV hydrogen ion implantation with a fluence of $8.0{\times}10^{16}ions/cm^2$. The nuclear energy loss of the implanted hydrogen ions was derived by using SRIM 2013 code. The microscope image of the proton-implanted Nd:CNGG crystal cross section was captured by a metallographic microscope. The transmittance spectra were recorded before and after the ion implantation. The light intensity distribution of the planar waveguide at 632.8 nm was experimentally measured to validate its effect on one dimension confinement. The investigation shows that the proton-implanted Nd:CNGG waveguide is a candidate for an optoelectronic integrated device.

• 한국분말재료학회지
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• 제18권1호
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• pp.29-34
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• 2011

In order to increase the coercivity of (Nd, Dy)-Fe-B sintered magnets without much reduction of remanence, small amount of Dy compounds such as $Dy_2O_3$ and $DyF_3$ was mixed with (Nd, Dy)-Fe-B powder. After mixing, the coercivity of (Nd, Dy)-Fe-B sintered magnets apparently increased with the increase of Dy compound in the mixture. Addition of $DyF_3$ was more effective than $Dy_2O_3$ for the improvement of coercivity. Reduction of the remanence by the addition of Dy compound, however, was larger than expected mostly due to unresolved coarse Dy compound in the magnet. EPMA analysis revealed that Dy was diffused throughout the grains in the magnet mixed with $DyF_3$ whereas Dy was rather concentrated around grain boundaries in the magnet mixed with $Dy_2O_3$.

• Journal of Magnetics
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• 제4권2호
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• pp.60-64
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• 1999

The addition of Co into $Nd_4Fe_{77.5-x}Co_x(HfGa)_yB_{18.5}(0$\leq$x$\leq$5, y=0, 0.5)4 was found to enhance the magnetic properties of $Fe_3B/Nd_2Fe_{14}B$ nanocomposite magnets. The enhancement resulted from the fact that Co retarded the crystallization of $\alpha$-Fe or Fe3B but accelerated that $Nd_2Fe_{14}B$. The decreased interval between the onset of crystallization temperature of Fe3B and $Nd_2Fe_{14}B$. phases enabled the grain growth of each phase to be uniform dufing a post annealing of the melt spun ribbons. The addition of 3~5 at. % Co into ternary composition $Md_4Fe_{77.5}B_{18.5}$ increased the coercivity (iHc) from 3.27 to 3.54 kOe with the enhanced remanence value (4$\pi$Mr) around 11.54 kG. From the ribbon magnets of Nd4Fe71.5Co5Hf0.5B18.5 made at 26 m/sec and annealed at 68$0^{\circ}C$ for 10 min, the magnetic properties of Br=11.54 kG, iHc=3.54 kOe, and (BH)max=14.35 MGOe were obtained from volume production line.

• Progress in Superconductivity
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• 제10권2호
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• pp.133-138
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• 2009

The $Nd_{1+x}Ba_{2-x}Cu_3O_{7-{\delta}}$(Nd123) superconductor exhibits high performance in high magnetic field and high temperature. We have studied phase stability for Nd123 under reduced oxygen partial pressure and various heat-treatment conditions. The main phase is Nd123 and some samples contain small amounts of Nd422 depending on the temperature and oxygen partial pressure. The decomposition temperature decreases with decreasing oxygen partial pressure from $1052^{\circ}C(P(O_2)$=150 Torr) to about $845^{\circ}C(P(O_2)$=0.1 Torr). The liquidus line was steeper temperature with decreasing oxygen partial pressure. In same condition of oxygen partial pressure, the region of stable Nd123 phase was formed at slightly higher temperature than the region of stable YBCO phase.

• 한국식품과학회지
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• 제36권6호
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• pp.872-878
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• 2004

스웨덴에서 발암 가능성이 높은 물질 아크릴아마이드가 굽거나 튀긴 음식에서 검출되었다고 발표한 후 아크릴아마이드에 대한 연구가 전세계적으로 진행되고 있다. 본 연구에서는 국내 식품에 대한 모니터링을 위해 다양한 식품을 선택하여 327개 식품을 분석하였다 모티터링 결과 원료식품은 ND-17 ppb, 밥은 ND-14 ppb, 떡은 ND-<10 ppb, 빵은 <10-33 ppb, 유탕면은 ND-27 ppb, 영유아식은 ND-15 ppb, 후렌치 후라이는 141-1,118 ppb, 뻥튀기 누룽지 강냉이 및 건빵은 15-587 ppb,단백질 식품은 ND-<10 ppb, 포테이토 칩, 포테이토 스낵은 278-3,277 ppb, 크래커, 스낵, 비스킷은 13-459 ppb, 시리얼은 <10-236 ppb, 차 및 음료는 ND-24 ppb, 커피는 394-1026 ppb, 초콜릿은 13-30 ppb, 사탕, 캐러멜은 ND-34 ppb, 통조림은 ND-20 ppb, 버터, 마가린 및 유제품은 ND-<10 ppb, 장류은 ND-60 ppb, 소스는 ND-51 ppb, 기타(땅콩, 호두)는 ND-13 ppb 범위의 아크릴아마이드가 검출되었다 국내 제품의 아크릴아마이드 함량은 외국에서 분석된 아크릴아마이드 함량과 비슷하였다.