• Korean Journal of Materials Research
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• v.11 no.10
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• pp.879-888
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• 2001

The effects of final annealing temperature on the microstructure and creep characteristics were investigated for the Zr-lNb-0.2X (X=0, Mo, Cu) and Zr-lNb- 1Sn-0.3Fe-0.1X (X=0, Mo, Cu) alloys. The microstructures were observed by using TEM/EDS, and grain size and distributions of precipitates were analyzed using a image analyzer. The creep test was performed at $400^{\circ}C$ under applied stress of 150 MPa for 10 days. The $\beta$-Zr was observed at annealing temperature above $600^{\circ}C$. In the temperature above$ 600^{\circ}C$, the grain sizes of both alloy systems appeared to be increased with increasing the final annealing temperature. The creep strengths of Zr-1Nb-1Sn-0.3Fe-0.1X alloys were higher than those of Zr-1Nb-0.2X ones due to the effect of solid solution hardening by Sn in Zr-lNb-lSn-0.3Fe-0.1X alloy system. Also, Mo addition showed the strong effect of precipitate hardening in both alloy systems. The creep strength rapidly decreased with increasing the annealing temperature up to $600^{\circ}C$. However, a superior creep resistance was obtained in the sample that annealed to have a second phase of $\beta$-Zr. It was considered that the appearance of $\beta$-Zr would play an important role in the strengthening mechanism of creep deformation.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.12 no.4
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• pp.217-224
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• 1979

The main purpose of the present study is to measure the sound spectra of the underwater noises generated by moving trawl net. An underwater recording system was designed to detect underwater noise generated by moving trawl net. The acoustic analysis was made by a heterodyne analyzer (B & K 2010) and level recorder (B & K 2307). The noises generated by the trawl net are appreciably higher (about 10dB) than the background noise in the presence of the fishing vessel. The frequency distribution of underwater noise was DC-6,300 Hz and predominant frequency range was 100-200 Hz, and maximum sound pressure level was $137\;db(re\;1{\mu}Pa)$. Sound pressure level recorded at the ground rope was higher than that recorded at the head rope. The sound pressure level meosured in the course of hawling was higher than that measured in the course of towing. When tile net is being casted tile sound pressure level showed the lowest value.

• Archives of Plastic Surgery
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• v.47 no.3
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• pp.242-249
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• 2020

Background The Exoscope is a novel high-definition digital camera system. There is limited evidence signifying the use of exoscopic devices in microsurgery. This trial objectively assesses the effects of the use of the Exoscope as an alternative to the standard operating microscope (OM) on the performance of experts in a simulated microvascular anastomosis. Methods Modus V Exoscope and OM were used by expert microsurgeons to perform standardized tasks. Hand-motion analyzer measured the total pathlength (TP), total movements (TM), total time (TT), and quality of end-product anastomosis. A clinical margin of TT was performed to prove non-inferiority. An expert performed consecutive microvascular anastomoses to provide the exoscopic learning curve until reached plateau in TT. Results Ten micro sutures and 10 anastomoses were performed. Analysis demonstrated statistically significant differences in performing micro sutures for TP, TM, and TT. There was statistical significance in TM and TT, however, marginal non-significant difference in TP regarding microvascular anastomoses performance. The intimal suture line analysis demonstrated no statistically significant differences. Non-inferiority results based on clinical inferiority margin (Δ) of TT=10 minutes demonstrated an absolute difference of 0.07 minutes between OM and Exoscope cohorts. A 51%, 58%, and 46% improvement or reduction was achieved in TT, TM, TP, respectively, during the exoscopic microvascular anastomosis learning curve. Conclusions This study demonstrated that experts' Exoscope anastomoses appear non-inferior to the OM anastomoses. Exoscopic microvascular anastomosis was more time consuming but end-product (patency) in not clinically inferior. Experts' "warm-up" learning curve is steep but swift and may prove to reach clinical equality.

• Tribology and Lubricants
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• v.32 no.5
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• pp.141-146
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• 2016

The diketopyrrolopyrrole (DPP) pigment is a bicyclic 8-π-electron system containing two lactam units. Typical DPP derivative pigments have melting points of over 350°C and very low solubility in most solvents, and show absorption in the visible region with a molar extinction coefficient of 33,000 dm²mol⁻¹ and strong photoluminescence with maxima in the range 500–600 nm. X-ray structure analyses of DPP show that the whole molecule is almost in one plane. The phenyl rings are twisted out of the heterocyclic plane and the intermolecular hydrogen bonding between neighboring lactam NH and carbonyl units influences the structure of the DPP pigment in the solid state. In this study, mono-N-alkylation and mono-N-arylation were undertaken for Pigment Red 264 or Pigment Orange 73 with alkyl halide and aryl halide, respectively, in the presence of sodium tert-butoxide as a base catalyst to improve the solubility of DPP pigments and their application as CO₂ indicators. The synthetic yield was in the range 11–88%. The indicator dyes are highly soluble in organic solvents and shows pH-dependent absorption (λ_max 501 and 572 nm for the protonated and deprotonated forms, respectively) and emission (λ_max 524 and 605 nm for the protonated and deprotonated forms, respectively) spectra. The mono-N-alkylated and mono-N-arylated DPP pigment was identified by ¹H-NMR (¹H-Nuclear Magnetic Resonance Spectrometer), FT-IR (Fourier Transform Infrared Spectroscopy), and MS (Mass Spectrometry). According to the results of color and hue properties obtained by a color matching analyzer, the synthesized DPP pigment material can be used as a CO₂ indicator.

• Proceedings of the Korean Vacuum Society Conference
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• 1998.02a
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• pp.133-133
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• 1998

In the thin film alloy formation of the transition metals ion-beam-mixing technique forms a metastable structure which cannot be found in the arc-melted metal alloys. Sppecifically it is well known that the studies about the electronic structure of ion-beam-mixed alloys pprovide the useful information in understanding the metastable structures in the metal alloy. We studied the electronic change in the ion-beam-mixed ppt-Ct alloys by XppS and XANES. These analysis tools pprovide us information about the charge transfer in the valence band of intermetallic bonding. The multi-layered films were depposited on the SiO2 substrate by the sequential electron beam evapporation at a ppressure of less than 5$\times$10-7 Torr. These compprise of 4 ppairs of ppt and Cu layers where thicknesses of each layer were varied in order to change the alloy compposition. Ion-beam-mixing pprocess was carried out with 80 keV Ae+ ions with a dose of $1.5\times$ 1016 Ar+/cm2 at room tempperature. The core and valence level energy shift in these system were investigated by x-ray pphotoelectron sppectroscoppy(XppS) pphotoelectrons were excited by monochromatized Al K ａ(1486.6 eV) The ppass energy of the hemisppherical analyzer was 23.5 eV. Core-level binding energies were calibrated with the Fermi level edge. ppt L3-edge and Cu K-edge XANES sppectra were measured with the flourescence mode detector at the 3C1 beam line of the ppLS (ppohang light source). By using the change of White line(WL) area of the each metal sites and the core level shift we can obtain the information about the electrons pparticippating in the intermetallic bonding of the ion-beam-mixed alloys.

• Korean Journal of Veterinary Research
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• v.44 no.2
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• pp.287-292
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• 2004

The objective of present study was to ascertain genetic diversity for cattle parentage testing. A total of 59 random cattle samples(29 Korean native cattle and 30 dairy cows) were genotyped by using 11 microsatellite loci(BM1824, BM2113, ETH10, ETH225, EH3, INRA23, SPS115, TGLA122, TGLA227, TGLA53, and TGLA126). This method consisted of multiplexing PCR procedure and showed reasonable amplification of all PCR products. Genotyping was performed with an ABI 310 genetic analyzer. The number of alleles per locus varied from 5 to 11 with a mean value of 6.73 in the Korean native cattle(KNC), 4 to 9 with a mean of 5.91 in dairy cows(DC). Expected heterozygosity was ranged 0.534~0.855(mean 0.732), 0.370~0.866(mean 0.692) in the KNC and DC, respectively. PIC value was ranged 0.485~0.821(mean 0.684), 0.336~0.834(mean 0.640) in the KNC and DC, respectively. Of the 11 markers, 7 markers(ETH10, EH3, INRA23, SPS115, TGLA122, TGLA227, TGLA53) and 3 markers(INRA23, TGLA227, TGLA53) have relatively high PIC value (>0.7) in the KNC and DC, respectively. The total exclusion probability of 11 microsatellite loci was 0.9997 and 0.9991 in the KNC and DC, respectively. These results present basic information for developing a system for parentage verification and individual identification in the KNC and DC.

• Transactions of the Korean Society of Mechanical Engineers
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• v.10 no.6
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• pp.823-829
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• 1986

The Large-scale structure of the circular jet in the transition region, which influences the subsequent flow in the turbulent region, was studied experimentally. Measuring equipments are composed of the two channel hot-wire anemometer, the computer controlled two-directional traverse mechanism, the data acquisition system, and FFT-analyzer. The circular jet has 50mm diameter. The mean velocity distribution, the velocity fluctuation, the auto 'cross correlations and the power spectra were acquired at moderate Reynolds number of 10$^{4}$. And the VITA method was used to measure the convection velocity of Large-scale eddy. The phase of u'is in advance of that of v'in all regions. .over bar. $R_{u}$(.tau.=0) is approximately zero in the potential core region, but a small regular deviation is observed. At a position in the mixing layer region the convection velocity is different along the part of the eddy, and in this experiment the convection velocity of the inner region is larger than the outer region. The averge convection velocity of the eddy along y/D=0 was approximately constant in the transition region.D=0 was approximately constant in the transition region.

• The Korean Journal of Nuclear Medicine
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• v.27 no.1
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• pp.104-111
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• 1993

Trace elements are important components in the biological system, as a structural material and metabolic controller. Neutron activation analysis (NAA) with high neutron flux and high energy resolution Ge (Li) detector coupled to multichannel analyzer (MCA) has been one of the most accurate method for the determination of ultra-trace level components, and is applicable to biological material. In human body, the NAA can be used for quantitation of trace elements in various organs and tissue with endocrinological and metabolic disease and industrial metal poisoning. In this study, Triga Mark III nuclear reactor in Korea Atomic Research Institute was used for quantitation of trace eleement in human lung cancer tissues by neutron activation analysis. In the squamous cell carcinoma tissues, Br, Hg, La, Sb, Sc, Cl, Fe and I content were lower than normal lung tissues, and K, Rb and Se content were higher. In the adenocarcinoma tissues, Fe, Au, La, Sc and Zn content were lower than normal lung tissues, and Rb, Co and Se content were higher. Rb content was higher in the adenocarcinoma tissues than in the squamous cell carcinoma tissues. Fe and Na content were higher in the squamous cell carcinoma tissues than in the adenocarcinoma tissues.

• Proceedings of the Korean Vacuum Society Conference
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• 2011.08a
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• pp.254-254
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• 2011

The memories with nano-particles are very attractive because they are promising candidates for low operating voltage, long retention time and fast program/erase speed. In recent, various nano-floating gate memories with metal-oxide nanocrystals embedded in organic and inorganic layers have been reported. Because of the carrier generation in semiconductor, induced photon pulse enhanced the program/erase speed of memory device. We studied photo-induced electrical properties of these metal-oxide nanocrystal memory devices. At first, 2~10-nm-thick Sn and In metals were deposited by using thermal evaporation onto Si wafer including a channel with $n^+$ poly-Si source/drain in which the length and width are 10 ${\mu}m$ each. Then, a poly-amic-acid (PAA) was spin coated on the deposited Sn film. The PAA precursor used in this study was prepared by dissolving biphenyl-tetracarboxylic dianhydride-phenylene diamine (BPDA-PDA) commercial polyamic acid in N-methyl-2-pyrrolidon (NMP). Then the samples were cured at 400$^{\circ}C$ for 1 hour in N atmosphere after drying at 135$^{\circ}C$ for 30 min through rapid thermal annealing. The deposition of aluminum layer with thickness of 200 nm was followed by using a thermal evaporator, and then the gate electrode was defined by photolithography and etching. The electrical properties were measured at room temperature using an HP4156a precision semiconductor parameter analyzer and an Agilent 81101A pulse generator. Also, the optical pulse for the study on photo-induced electrical properties was applied by Xeon lamp light source and a monochromator system.

• Proceedings of the Korean Vacuum Society Conference
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• 2011.08a
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• pp.301-301
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• 2011

최근 고밀도 메모리 반도체의 재료와 빠른 응답을 요구하는 나노입자를 이용한 비휘발성 메모리 소자의 제작에 대한 연구가 활발히 진행되고 있다. 그에 따른 기존의 플래쉬 메모리가 가지는 문제점을 개선하기 위해서 균일하고 규칙적으로 분포하는 새로운 나노소재의 개발과 비휘발성, 고속 동작, 고집적도, 저전력 소자의 공정기술이 요구되고 있다. 또한 부유게이트에 축적되는 저장되는 전하량을 증가시키기 위한 새로운 소자구조 개발이 필요하다. 한편, 실리 사이드 계열의 나노입자는 금속 나노입자와 달리 현 실리콘 기반의 반도체 공정에서 장점을 가지고 있다. 따라서 본 연구에서는 화합물 중에서 비휘발성 메모리 장치의 전기적 특성을 향상 시킬 수 있는 실리사이드 계열의 바나듐 실리사이드(V3Si) 박막을 열처리 과정을 통하여 수 nm 크기의 나노입자로 제작하였다. 소자의 제작은 p-Si기판에 실리콘산화막 터널층(5 nm 두께)을 건식 산화법으로 성장 후, 바나듐 실리사이드 금속박막을 RF 마그네트론 스퍼터 시스템을 이용하여 4~6 nm 두께로 터널 베리어 위에 증착하고, 그 위에 초고진공 마그네트론 스퍼터링을 이용하여 SiO2 컨트롤 산화막층 (20 nm)을 형성시켰다. 여기서 V3Si 나노입자 형성을 위해 급속 열처리법으로 질소 분위기에서 800$^{\circ}C$로 5초 동안 열처리하여 하였으며, 마지막으로 열 기화 시스템을 통하여 알루미늄 전극(직경 200 ${\mu}m$, 두께 200 nm)을 증착하여 소자를 제작하였다. 제작된 구조는 금속 산화막 반도체구조를 가지는 나노 부유게이트 커패시터이며, 제작된 시편은 투사전자현미경을 이용하여 나노입자의 크기와 균일성을 확인했다. 소자의 전기적인 측정을 E4980A capacitor parameter analyzer와 Agilent 81104A pulse pattern generator system을 이용한 전기용량-전압 측정을 통해 전하저장 효과 및 메모리 동작 특성들을 분석하고, 열처리 조건에 따라 형성되는 V3Si 의 조성을 엑스선 광전자 분광법을 이용하여 확인하였다.