• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2001년도 추계학술대회 논문집 Vol.14 No.1
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• pp.213-216
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• 2001

Etching behaviors of ferroelectric $YMnO_3$ thin films were studied by an inductively coupled plasma (ICP). Etch characteristic on ferroelectric $YMnO_3$ thin film have been investigated in terms of etch rate, selectivity and etch profile. The maximum etch rate of $YMnO_3$ thin film is $300{\AA}/min$ at $Ar/Cl_2$ of 2/8, RF power of 800W, dc bias voltage of 200V, chamber pressure of 15mTorr and substrate temperature of $30^{\circ}C$. Addition of $CF_4$ gas decrease the etch rate of $YMnO_3$ thin film. From the results of XPS analysis, YFx compounds were found on the surface of $YMnO_3$ thin film which is etched in $Ar/Cl/CF_{4}$ plasma. The etch profile of $YMnO_3$ film is improved by addition of $CF_4$ gas into the $Ar/Cl_2$ plasma. These results suggest that fluoride yttrium acts as a sidewall passivants which reduce the sticking coefficient of chlorine on $YMnO_3$.

• Progress in Superconductivity
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• 제8권2호
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• pp.175-180
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• 2007

High temperature superconductor $YBa_2Cu_3O_{7-x}$ (YBCO) films have been grown by in-situ electron beam evaporation on artificial metal tapes such as ion-beam assisted deposition (IBAD) and rolling assisted biaxially textured substrates (RABiTS). Deposition rate of the YBCO films is $10{\sim}100{\AA}/sec$. X-ray diffraction shows that the films are grown epitaxially but have inter-diffusion phases, like as $BaZrO_3\;or\;BaCeO_3$, at their interfaces between YBCO and yttrium-stabilized zirconia (YSZ) or $CeO_2$, respectively. Secondary ion mass spectroscopy depth profile of the films confirms diffused region between YBCO and the buffer layers, indicating that the growth temperature ($850{\sim}900^{\circ}C$) is high enough to cause diffusion of Zr and Ba. The films on both the substrates show four-fold symmetry of in-plane alignment but their width in the -scan is around $12{\sim}15^{\circ}$. Transmission electron microscopy shows an interesting interface layer of epitaxial CuO between YBCO and YSZ, of which growth origin may be related to liquid flukes of Ba-Cu-O. Resistivity vs temperature curves of the films on both substrates were measured. Resistivity at room temperature is between 300 and 500 cm, the extrapolated value of resistivity at 0 K is nearly zero, and superconducting transition temperature is $85{\sim}90K$. However, critical current density of the films is very low, ${\sim}10^3A/cm^2$. Cracking of the grains and high-growth-temperature induced reaction between YBCO and buffer layers are possible reasons for this low critical current density.

• Archives of Plastic Surgery
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• 제39권3호
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• pp.232-237
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• 2012

Background : Skin injuries, such as lacerations due to trauma, are relatively common, and patients are very concerned about the resulting scars. Recently, the use of ablative and non-ablative lasers based on the fractional approach has been used to treat scars. In this study, the authors demonstrated the efficacy and safety of ablative fractional resurfacing (AFR) for traumatic scars using a 2,940-nm erbium: yttrium-aluminum-garnet (Er:YAG) laser for traumatic scars after primary repair during the early posttraumatic period. Methods : Twelve patients with fifteen scars were enrolled. All had a history of facial laceration and primary repair by suturing on the day of trauma. Laser therapy was initiated at least 4 weeks after the primary repair. Each patient was treated four times at 1-month intervals with a fractional ablative 2,940-nm Er:YAG laser using the same parameters. Posttreatment evaluations were performed 1 month after the fourth treatment session. Results : All 12 patients completed the study. After ablative fractional laser treatment, all treated portions of the scars showed improvements, as demonstrated by the Vancouver Scar Scale and the overall cosmetic scale as evaluated by 10 independent physicians, 10 independent non-physicians, and the patients themselves. Conclusions : This study shows that ablative fractional Er:YAG laser treatment of scars reduces scars fairly according to both objective results and patient satisfaction rates. The authors suggest that early scar treatment using AFR can be one adjuvant scar management method for improving the quality of life of patients with traumatic scars.

• 한국세라믹학회지
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• 제41권7호
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• pp.541-547
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• 2004

일반적으로 혼합분말의 소결에서 작은 입자에 큰 입자의 첨가는 소결성의 저하를 가져온다. 본 연구에서는 이러한 원리를 이용하여 작은 SiC 입자에 큰 SiC 휘스커 또는 큰 SiC 입자를 첨가하여 소결성을 저하시키고, YAG(Y$_3$A1$_{5}$O$_{12}$)상을 소결 첨가제로 사용함으로서 다공질 SiC 세라믹스를 제조하였다. 제조된 다공질 SiC 세라믹스의 기공율은 큰 입자의 함량과 소결 압력을 제어함으로서 0.3-39% 범위에서 제어할 수 있었다. 기공율은 큰 입자의 함량이 증가함에 따라 증가하였고, SiC 휘스커를 첨가하는 것이 큰 SiC 입자를 첨가하는 것 보다 기공율을 높이는데 효과적이었다. 제조된 다공질 세라믹스에서 기체의 통기성은 기공율이 증가함에 따라 증가하였고, 굽힘강도는 기공율이 증가함에 따라 감소하였다. 기공율이 18% 이상인 다공질 SiC 세라믹스의 경우에 주목할 만한 변형율이 관찰되었다.

• 한국세라믹학회지
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• 제26권4호
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• pp.459-470
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• 1989

Single crystals of rare-earth iron garnets were grown from solutions of molten lead oxide, lead fluoride, baric oxide, iron oxide, and the oxides of yttrium, samarium orgadolinium. The crystals were grown by slow cooling technique. A convenient composition was 41.8mol% PbO, 20.59mol% PbF2, 8.23mol% B2O3, 20.00mol% Fe2O3 and 10.00mol% R2O3 where R is Y, Sm or Gd. For this experiment, platinum crucibles of size 20, 30cc and a vertical siliconit tube furnace were used. The precipitation temperature of YIG was observed in the range of 115$0^{\circ}C$-112$0^{\circ}C$ and the optimum growth conditions in this experiment were determined. The nucleation rate was controlled by the holding time after the fast colling, the growth rate by the slow cooling conditiions. The form of the grown YIG crystals showed a combination of {110} and {211}, and the size of the crystals grown in this experiment was up to about 9mm under the conditions of holding time 16hour, cooling rate 2$^{\circ}C$/hr. and temperature range 115$0^{\circ}C$-90$0^{\circ}C$. The precipitatin temperature of SmIG was observed in the range of 105$0^{\circ}C$-98$0^{\circ}C$ and the size of the crystals grown in this experiment was up to about 5mm under the conditiions of holding time 16hours, cooling rate 2$^{\circ}C$/hr. and temperature range 100$0^{\circ}C$-80$0^{\circ}C$.

• 한국환경과학회:학술대회논문집
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• 한국환경과학회 1996년도 봄 학술발표회 초록집
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• pp.22-22
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• 1996

;The Kwinana Shoreline Fumigation Experiment(KSFE) took place in Fremantle, WA, Australia between 23 January and 8 February, 1995. All measurement systems performed to expectation. The CSIRO DAR(Division of Atmospheric Research) LIDAR measured plume sections from near the Kwinana Power Station(KPS) stacks to up to about 5 km downstream. It also measured boundary layer aerosols and the structure of the boundary layer on some occasions. Both stages A and C of KPS were used as tracers at different times. Radiosonde and double theodolite sounding systems measured temperature, humidity, air pressure and wind structure at the coast(Woodman Point) and at the inland(ALCOA residue dump) site at intervals of roughly two hours. These were supplemented by mid afternoon soundings(radiosonde and single theodolite) by Department of Environmental Protection(DEP) at Swanbourne. The Flinders aircraft measured wind, turbulence and temperature structure of the atmospheric boundary layer, concentrations of $C0_2,\;0_3,\;S0_2\;and\;NO_x$ in the smoke plumes and surface radiation over both land and sea. CSIRO DCET(Division of Coal and Energy Technology) vehicle successfully interceptde many smoke plumes and using a range of tracers will be able to identify the various sources much of the time. Routine data from the DEP and Kwinana Industrial Council(KIC) air quality monitoring networks were also automatically logged. Murdoch University measured surface heat flux at Hope Valldy monitoring station and also at Wattleup monitoring station for the last five days. The heart of the LIDAR system is a Neodymium-doped Yttrium-aluminumgarnet(Nd:Y AG) laser operating at a fundamental wavelength of 1064 nm, with harmonics fo 532 nm and 355 nm. A small fraction of the laser beam is scattered back to the LIDAR, collected by a telescope and detedted by a photomultiplier tube. The intensity of the signal as a function of time is a measure of the particle concentration as a function of distance along the line of the laser shot. The results of nine days special field observations are summarized in detail.etail.

• 한국표면공학회:학술대회논문집
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• 한국표면공학회 2016년도 추계학술대회 논문집
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• pp.120-120
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• 2016

Ti-6Al-4V alloy have been used for dental implant because of its excellent biocompatibility, corrosion resistance, and mechanical properties. However, the integration of such implant in bone was not in good condition to achieve improved osseointergraiton. For solving this problem, calcium phosphate (CaP) has been applied as coating materials on Ti alloy implants for hard tissue applications because its chemical similarity to the inorganic component of human bone, capability of conducting bone formation and strong affinity to the surrounding bone tissue. Various metallic elements, such as strontium (Sr), magnesium (Mg), zinc (Zn), sodium (Na), silicon (Si), silver (Ag), and yttrium (Y) are known to play an important role in the bone formation and also affect bone mineral characteristics, such as crystallinity, degradation behavior, and mechanical properties. Especially, Zn is essential for the growth of the human and Zn coating has a major impact on the improvement of corrosion resistance. Plasma electrolytic oxidation (PEO) is a promising technology to produce porous and firmly adherent inorganic Zn containing $TiO_2(Zn-TiO_2)$coatings on Ti surface, and the a mount of Zn introduced in to the coatings can be optimized by altering the electrolyte composition. In this study, corrosion behavior of Ti-6Al-4V alloy after plasma electrolytic oxidation in solutions containing Ca, P and Zn were studied by scanning electron microscopy (SEM), AC impedance, and potentiodynamic polarization test. A series of $Zn-TiO_2$ coatings are produced on Ti dental implant using PEO, with the substitution degree, respectively, at 0, 5, 10 and 20%. The potentiodynamic polarization and AC impedance tests for corrosion behaviors were carried out in 0.9% NaCl solution at similar body temperature using a potentiostat with a scan rate of 1.67mV/s and potential range from -1500mV to +2000mV. Also, AC impedance was performed at frequencies ranging from 10MHz to 100kHz for corrosion resistance.

• 한국세라믹학회지
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• 제25권2호
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• pp.143-153
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• 1988

김천규석으로부터 합성한 질화규소와 시약급의 AIN과 $Y_2O_3$를 출발원료로 하여 $Si_3N_4-0.1Y_2O_3-0.9AIN$의 tie line에서 X=0.6, 0.4(금속고용량)인 조성으로부터 AIN 의 양을 감소시킨 조성과 $Y_2O_3$를 증가시키는 조성으로 1750~1800도에서 소결시켜 부분 안정화 $\alpha$-Sialon을 제조하였다. $\alpha$-Sialon 생성에는 $Y_2O_3$ 첨가량보다 AIN 첨가량에 밀접하게 관련되며 AIN은 $\beta$단위격자 보다 $\alpha$ 단위격자로 우선적으로 고용되었으며 $Y_2O_3$가 과잉으로 첨가된 조성에서는 melillite 형성과 입자 조대화 및 $\alpha$-Sialon의 분배로 인하여 yttrium silicide 와 금속 Si를 형성하였으며 기계적 물성은 저하하였다. 본 실험에서 얻은 기계적 물성의 최고 값은 모두 1780도에서 얻어졌으며 그 값은 꺽임강도 723MPa, 파괴 인성 4.5MN/m^3/2, 경도 19.3GPa이었다.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2008년도 하계학술대회 논문집 Vol.9
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• pp.441-442
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• 2008

For this study, Yttrium aluminum garnet (YAG) particles co-doped with $Ce^{3+}$ and $Eu^{3+}$ were prepared via the combustion process using the 1:1 ratio of metal ions to reagents. The characteristics of the synthesized nano powder were investigated by means of X-ray diffraction (XRD), Scanning Electron Microscope (SEM), and photoluminescence (PL). The various YAG peaks, with the (420) main peak, appeared at all Eu concentrationin XRD patterns. The YAG phase crystallized with results that are in good agreement with the JCPDS diffraction file 33-0040. The SEM image showed that the resulting YAG:Ce,Eu powders had uniform sizes and good homogeneity. The grain size was about 50nm. The photoluminescence spectra of the YAG:Ce,Eu nanoparticles were investigated to determine the energy level of electron transition related to luminescence processes. It was composed a broad band of $Ce^{3+}$ activator into the weak line peak of $Eu^{3+}$ in YAG host. The PL intensity of $Ce^{3+}$ has the wavelengths of 480-650 nm and The PL intensity of $Eu^{3+}$ has main peak at 590nm.

• 한국결정성장학회지
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• 제30권3호
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• pp.110-116
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• 2020

MLCC(Multi-Layer Ceramic Capacitor)의 유전체 층에 사용되는 BaTiO₃ 입자는 안정한 TCC(Temperature Characteristics of Capacitance) 거동을 갖기 위해 core/shell 구조를 갖는다. 지금까지 shell의 특성은 core/shell 구조의 전체 특성에서 유추해 왔다. 이는 core/shell 구조가 겨우 수 ㎛의 작은 크기로 shell 특성만 구별해서 측정하기가 어렵기 때문이다. 본 실험에서는 micro-contact법을 이용하여 확산쌍 시편의 계면에 형성된 확대된 core/shell 구조에 Pt 전극을 증착하여 35~135℃ 에서 shell 영역의 독립적인 TCC 거동을 측정하였다. 그 결과, 65℃에서 최대 유전율 값을 갖는 완만한 피크의 확산 상전이(Diffusion Phase Transition) 거동인 core의 특성과 구별되는 거동을 관찰하였으며, 이는 core/shell 구조의 온도-유전거동을 묘사하는 모델링에서 실험 자료로 활용될 것으로 본다.