• Journal of Nuclear Fuel Cycle and Waste Technology(JNFCWT)
• /
• v.5 no.2
• /
• pp.123-132
• /
• 2007

This study was performed to evaluate the co- and mutual separation for Am, Cm and RE elements from the simulated multi-component solution equivalent to real HLW level by a Zr-DEHPA(di-(2-ethylhexyl) phosphoric acid containing Zirconium)/$NDD(n-dodecane)-HNO_3$ extraction system. Zr-DEHPA was self-synthesized and the optimal condition of (15g/L Zr-1M DEHPA)/NDD-1M $HNO_3$ was selected taking into consideration of prevention of the third phase, and effects of concentration of DEHPA, nitric acid and impregnant amount of Zr on the co-extraction of Am, Cm and RE. In that condition, the extraction yields were 81% (Am), 85% (Cm), more than 80% (RE elements), 98% (Mo), 85% (Fe), 98% (U), 73% (Np), and less than 5% (other elements) so that the system developed for the co-extraction of Am-Cm/RE was proved to be available. For that, however, U, Np, Mo and Fe was elucidated to have to be removed in advance, and Zr inducing the third phase formation was found to be practically excluded. The co-extracted Am-Cm/RE were sequentially separated in an order of Am-Cm (stripping agent : 0.05 M DTPA-1M Lactic acid of pH 3.6)${\rightarrow}RE$ (stripping agent : 5M $HNO_3$), and then their separation factors were evaluated. At above conditions, Am of 65.4%, Cm of 63.9%, RE (except for Y) of more than 85% were stripped.

• Journal of the Korean Chemical Society
• /
• v.27 no.4
• /
• pp.279-286
• /
• 1983

An apparatus was made for the electrodeposition of alpha emitting actinide nuclides, $^{207}Bi$ and $^{210}Po$. The electrodeposition was made on a polished stainless steel plate cathode. The anode was made of platinum wire and to stir the solution. With the ammonium chloride as electrolyte initial pH = 4, chloride concentration = 0.6M and solution volume = 15ml, a current of 1.5 ampere(current density = 0.59A/$cm^2$) was flowed for 100 minutes for the quantitative recovery of electrodeposition and on average recovery of 98.3% was obtained within ${\pm}$0.7% uncertainty. Alpha spectrometry of the electrodeposited sample showed alpha peaks from $^{210}Po, ^{234}U$ and $^{239}Pu$ having energy resolution (FWHM) of 18.3, 21.8 and 36.0 keV respectively. The electrodeposition and alpha spectrometry for a natural uranium sample of domestic origin gave $^{238}U : ^{234}U = 1 : 6.1{\times}10^{-5}$ and for a neutron-irradiated uranium sample did $^{238}U : ^{239}Pu : ^{241}Am = 100 : 0.0263 : 5.20{times}10^{-5}$. The result of $^{238}U$ determination in the irradiated sample by electrodeposition-alpha spectrometry was in accord within ${\pm}1.6%$ of relative error with the results of solid fluorimetry and mass spectrometry. For $^{239}Pu$ the result of electrodeposition-alpha spectrometry was in accord within ${\pm}$4.0% of relative error with the results of anion exchange separation and the thenoyltrifluoroacetone(TTA) extraction both followed by alpha spectrometries.

• Analytical Science and Technology
• /
• v.8 no.1
• /
• pp.1-7
• /
• 1995

Spectrophotometric determination of U(VI) and Th(IV) by Flow injection method is described. Chrome Azurol S forms water soluble complexes with U(VI) and Th(IV) in the presence of cethyltrimethylammonium bromide. The maximum adsorption of U(VI) and Th(IV) complexes are at 600nm with molar absorptivity of $2.3{\times}10^5Lmol^{-1}cm^{-1}$ and 611nm with molar absorptivity of $3.8{\times}10^5Lmol^{-1}cm^{-1}$ in acetate buffer medium having pH 5.0 and 5.5. The calibration curves of U(VI) and Th(IV) are linear over the range of 0.1~0.8ppm and the correlation coefficients are ca. 0.9960 and 0.9930 respectively. The detection limits(S/N) are 20ppb for U(VI) and 15ppb for Th(IV). The relative standard deviation are ${\pm}1.8%$ for U(VI) and ${\pm}2.1%$ for Th(IV). The sample throughput was ca. $50hr^{-1}$.

• Restorative Dentistry and Endodontics
• /
• v.26 no.4
• /
• pp.263-272
• /
• 2001

The aim of this study was to investigate the influence of four different light curing modes on the marginal leakage of Class V composite resin restoration. Eighty extracted human premolars were used. Wedge-shaped class Y cavities were prepared on the buccal surface of the tooth with high-speed diamond bur without bevel. The cavities were positioned half of the cavity above and half beyond the cemento-enamel junction. The depth, height, and width of the cavity were 2 mm, 3 mm and 2 mm respectively. The specimens were divided into 4 groups of 20 teeth each. All the specimen cavities were treated with Prime & Bond$^{R}$ NT dental adhesive system (Dentsply DeTrey GmbH, Germany) according to the manufacturer's instructions and cured for 10 seconds except group VI which were cured for 3 seconds. All the cavities were restored with resin composite Spectrum$^{TM}$ TPH A2 (Dentsply DeTrey GmbH, Germany) in a bulk. Resin composites were light-cured under 4 different modes. A regular intensity group (600 mW/${cm}^2$, group I) was irradiated for 30 s, a low intensity group (300 mW/${cm}^2$, group II) for 60 s and a ultra-high intensity group (1930 mW/${cm}^2$, group IV) for 3 s. A pulse-delay group (group III) was irradiated with 400 mW/${cm}^2$ for 2 s followed by 800 mW/${cm}^2$ for 10 s after 5 minutes delay. The Spectrum$^{TM}$ 800 (Dentsply DeTrey GmbH, Germany) light-curing units were used for groups I, II and III and Apollo 95E (DMD, U.S.A.) was used for group IV. The composite resin specimens were finished and polished immediately after light curing except group III which were finished and polished during delaying time. Specimens were stored in a physiologic saline solution at 37$^{\circ}C$ for 24 hours. After thermocycling (500$\times$, 5-55$^{\circ}C$), all teeth were covered with nail varnish up to 0.5 mm from the margins of the restorations, immersed in 37$^{\circ}C$, 2% methylene blue solution for 24 hours, and rinsed with tap water for 24 hours. After embedding in clear resin, the specimens were sectioned with a water-cooled diamond saw (Isomet$^{TM}$, Buehler Co., Lake Bluff, IL, U.S.A.) along the longitudinal axis of the tooth so as to pass the center of the restorations. The cut surfaces were examined under a stereomicroscope (SZ-PT Olympus, Japan) at ${\times}$25 magnification, and the images were captured with a CCD camera (GP-KR222, Panasonic, Japan) and stored in a computer with Studio Grabber program. Dye penetration depth at the restoration/dentin and the restoration/enamel interfaces was measured as a rate of the entire depth of the restoration using a software (Scion image, Scion Corp., U.S.A.) The data were analysed statistically using One-way ANOVA and Tukey's method. The results were as follows : 1. Pulse-Delay group did not show any significant difference in dye penetration rate from other groups at enamel and dentin margins (p>0.05) 2. At dentin margin, ultra-high intensity group showed significantly higher dye penetration rate than both regular intensity group and low intensity group (p<0.05). 3. At enamel margin, there were no statistically significant difference among four groups (p>0.05). 4. Dentin margin showed significantly higher dye penetration rate than enamel margin in all groups (p<0.05).

• Proceedings of the Korea Water Resources Association Conference
• /
• 2022.05a
• /
• pp.476-476
• /
• 2022

농업용수는 전통적 기능으로 농업용수 그 자체로서의 기능과 시대적 요구에 따른 지역용수로서의 기능을 가진다. 농업용수 그 자체의 기능으로 가장 중요한 것은 관개용수이며, 논, 밭관개, 하우스 시설농업에의 용수공급이다. 농업용수의 실 수요량 측면에서는 논용수가 전체용수 수요량의 60.1%로 가장 많은 양을 차지하고 있으며, 다음으로는 밭용수가 18.6%, 그 외 생활용수, 공업용수, 환경용수, 축산용수 등으로 이용되고 있다. 농업용수 수요 측면에서 논용수의 비중이 가장 높게 나타나기 때문에 본 연구에서는 농업용수 공급에 따라 농업용저수지-관개수로-논에 이르는 공급단계별 수질변화를 분석하였다. 본 연구는 경기, 충남 권역의 오염도가 높은 3개 농업용저수지를 대상으로 하였으며, 농업용수를 본격적으로 공급하는 5월부터 관개가 종료되는 10월까지 농업용저수지와 관개수로, 논을 대상으로 수온, TOC, Chl-a 등 10개 항목을 분석하여 나타내었다. 연구기간동안 수온의 변화는 18.6~34.6 ℃로서 관개수로에 가장 낮고, 논에서 가장 높은 값을 보여 주었으며, 공급단계별 평균 수온은 저수지(R) 27.6 ℃, 관개수로(C) 26.4 ℃, 논(P) 28.4 ℃로 논에서 수온증가가 나타났다. pH는 7.4~9.7의 범위로 저수지에서 최고값, 논에서 최저값을 보였으며, 공급단계별 평균값은 R 9.1, C 8.3, P 8.0으로 저수지, 수로, 논으로 이동하면서 감소하였다. 전기전도도(EC)는 저수지 수질오염도에 따라 다양하게 나타났으며, 공급단계별 평균값은 R 706.3 uS/cm, C 585.5 uS/cm, P 771.2 uS/cm로 논에서 가장 높은 값으로 보였으며, 이는 논에서 추가적인 영양분 공급에 의한 것으로 보였다. 평균 용존산소량(DO)은 R 6.3, C 4.0, P 4.5로 저수지에서 가장 높고, 수로에서 가장 낮게 나타났다. 유기물 지표인 COD와 TOC의 변화를 보면 평균 COD R 21.7 mg/L, C 14.5 mg/L, P 22.7 mg/L, 평균 TOC R 11.2 mg/L, C 8.5 mg/L, P 12.3 mg/L로 두 항목 모두 논에서 가장 높은 값을, 수로에서 가장 낮은 값을 나타내었다. 반면 엽록소 a 평균 농도는 R 128.4 mg/m³, C 54.3 mg/m³, P 31.7 mg/m³로 저수지의 내부생산으로 다량 발생한 조류가 수로와 논으로 이동하면서 급격하게 감소하여 나타났다. 이는 저수지와 논의 유기물 성상이 다름을 보여준다. 영양염류인 총인(TP)의 평균값 변화를 보면 R 0.302 mg/L, C 0.374 mg/L, P 0.384 mg/L로, 저수지에서 수로, 논으로 이동하면서 점차 증가하여 나타났다. 이는 농업용저수지에서 수로, 논으로 관개용수가 이동하면서 오염수 유입 또는 비료 등의 투입이 이루어진 결과로 판단된다. 이와 같이, 농업용저수지의 수질이 논에 그대로 유지되어 유입되지 않고 공급단계에 따라 변화하고 있으므로 항목별 수질 변화 특성을 이해한 후 농업용수 수질관리가 이루어 져야 할 것이다.

• Proceedings of the Korean Vacuum Society Conference
• /
• 2015.08a
• /
• pp.250.2-250.2
• /
• 2015

결정질 태양전지의 변환효율은 이미 이론적 한계에 가까워져, 최근 산업에서는 이 대신 제조공정 단가를 낮추려는 연구가 진행되고 있다. 본 연구에서는 태양전지 도핑공정에 대기압 DBD 플라즈마를 응용하여 저렴하게 태양전지를 제작할 수 있는 방법을 모색한다. 대기압 DBD 플라즈마를 발생시키기 위해 DC-AC 인버터 구조의 전원을 사용하여 수십 kHz의 주파수, 수 kV의 전압을 인가하여 $5cm{\times}1cm$ 직사각형 모양의 아노다이징된 알루미늄 전극을 사용하였다. 전극과 Ground 사이에 Argon 가스를 주입하여 플라즈마를 발생시켰으며, 출력전류는 수십 mA의 전류가 측정되었다. $3cm{\times}3cm$의 P-type wafer에 스핀코팅 방식으로 H3PO4를 도포한 후, Wafer 표면에 플라즈마를 조사하여 대기압 DBD 플라즈마를 이용한 태양전지 도핑 가능성을 확인하였다. 플라즈마 출력 전류와 플라즈마 조사시간을 변수로 도핑된 Wafer의 특성을 확인하였다. 도핑 프로파일은 SIMS (Secondary Ion Mass Spectrometry)를 통해 측정하였으며, 전기적인 특성은 4 point probe로 면저항을 측정하였다. 대기압 DBD 플라즈마를 이용해 도핑된 wafer에 전극을 형성하여, 같은 도펀트를 사용하여 Furnace로 열 확산법을 이용해 도핑 공정을 진행한 wafer와 변환효율(Conversion efficiency)을 측정하여, 대기압 플라즈마를 이용한 도핑 가능성을 확인하였다.

• Electrical & Electronic Materials
• /
• v.9 no.9
• /
• pp.885-890
• /
• 1996

Undoped p-type and Te doped n-type GaSb crystals were grown by the vertical Bridgman method. The lattice constant of the GaSb crystals was 6.096.+-.000373.angs.. The carrier concentration, the resistivity, and the carrier mobility measured by the van der Pauw method were p.iden.8*10$^{16}$ c $m^{-3}$ , .rho..iden.0.20 .ohm.-cm, .mu.$_{p}$ .iden.400c $m^{2}$ $V^{-1}$ se $c^{-1}$ for p-type, n.iden.1*10$^{17}$ c $m^{-3}$ , .rho..iden.0.15 .ohm.-cm, .mu.$_{n}$ .iden.500c $m^{2}$ $V^{-1}$ se $c^{-1}$ for n-type at 300K. In case of treatment with metal ion of R $u^{+3}$, P $t^{+4}$, the carrier concentration, resistivity and carrier mobility of the GaSb crystals were p.iden.2*10$^{17}$ c $m^{-3}$ , .rho..iden.0.08.ohm.-cm, .mu.$_{p}$ .iden.420c $m^{2}$ $V^{-1}$ se $c^{-1}$ for p-type, n.iden.2.5*10$^{17}$ c $m^{-3}$ , .rho..iden.0.07.ohm.-cm, .mu.$_{n}$ .iden.520c $m^{2}$ $V^{-1}$ se $c^{-1}$ for n-type respectively. GaSb crystals had a tendency to lower resistivity and higher mobility, for surface treatment with metal ion effectively diminished surface recombination centers.s.

• Proceedings of the KIEE Conference
• /
• 2005.07c
• /
• pp.2410-2412
• /
• 2005

In this study, two types of PS substrate were fabricated for sensing of chemical and biological substances. For sensing of the humidity and chemical analyzes such as $CH_3OH$ or $C_2H_5OH$, PS layers are prepared by photoelectrochemical etching of silicon wafer in aqueous hydrofluoric acid solution. To evaluate their sensitivity, we measured the resistance variation of the PS diaphragm. As the amplitude of applied voltage increases from 2 to 6Vpp at constant frequency of 5kHz, the resistance variation for humidity sensor rises from 376.3 to $784.8{\Omega}$/%RH. And the sensitivities for $CH_3OH$ and $C_2H_5OH$ were 0.068 uA/% and 0.212 uA/%, respectively. For biological sensing application, amperometric urea sensors were fabricated based on porous silicon(PS), and planar silicon(PLS) electrode substrates by the electrochemical methods. Pt thin film was sputtered on these substrates which were previously formed by electrochemical anodization. Poly (3-methylthiophene) (P3MT) were used for electron transfer matrix between urease(Urs) and the electrode phase, and Urs also was by electrochemically immobilized. Effective working area of these electrodes was determined for the first time by using $Fe(CN)_6^{3-}/Fe(CN)_6^{4-}$ redox couple in which nearly reversible cyclic voltammograms were obtained. The $i_p$ vs $v^{1/2}$ plots show that effective working electrode area of the PS-based Pt thin film electrode was 1.6 times larger than the PLS-based one and we can readily expect the enlarged surface area of PS electrode would result in increased sensitivity by ca. 1.6 times. Actually, amperometric sensitivity of the Urs/P3MT/Pt/PS electrode was ca 0.91uA/$mM{\cdot}cm^2$, and that of the Urs/P3MT/Pt/PLS electrode was ca. 0.91uA/$mM{\cdot}cm^2$ in a linear range of 1mmol/L to 100mmol/L urea concentrations

• Investigative Magnetic Resonance Imaging
• /
• v.17 no.2
• /
• pp.123-132
• /
• 2013

Purpose : We report the results of the various parameters of diffusion tensor imaging (DTI) and CSF flow study of the cervical spinal cord using magnetic resonance (MR) imaging techniques. Materials and Methods: Intramedullary FA and MD were measured in the gray matter and posterior cord of the white matter and both lateral cords of the white matter at the C2-3, C4-5, C5-6 spinal levels. For the CSF flow study, velocity encoding was obtained at the C2-3, C4-5, C5-6 spinal levels. Results: There was a significant difference of the FA and MD between the white matter and gray matter (p < 0.05). The FA of the gray matter was significantly different according to the cervical spinal cord levels (p < 0.05). Otherwise, the FA and MD parameters were not significantly different (p > 0.05). The mean peak systolic velocity and mean peak diastolic velocity were $5.18{\pm}2.00cm/sec$ and $-7.32{\pm}3.18cm/sec$, respectively from C2 to C6 spinal cords. There was no significant difference in these velocities among the cervical spinal cord (p > 0.05). Conclusion: This basic information about DTI and CSF dynamics of the cervical spinal cord may be useful for assessing cervical spinal cord abnormalities using MR imaging.

• Asian-Australasian Journal of Animal Sciences
• /
• v.24 no.4
• /
• pp.517-524
• /
• 2011

The effect on sow milk of variable levels of cassava in lactating sow diets was analyzed in an attempt to explain the beneficial effects reported by producers of including cassava as a basal feed. Twenty crossbred lactating sows were randomly assigned to five dietary treatments. The treatments were: i) broken rice (BR) as the basal feed (BR100), ii) 50% of BR replaced with cassava chip meal (CCM) (CM50), iii) 75% of BR replaced with CCM (CM75), iv) CCM as the basal feed (CM100), and v) dried boiled cassava chips (CCB) as the basal feed (CB100). The hydrocyanide (HCN) content of CCB was reduced to be intermediate between HCN in the no cassava (BR100) and the 50% cassava (CB50) diets. Hydrocyanide was 0.54, 3.24, 4.41, 5.43 and 1.77 ppm in the BR100, CM50, CM75, CM100 and CB100 diets, respectively. Increasing cassava did not affect feed intake (p>0.05), but increased HCN intake (p<0.01). Milk composition was analyzed for protein, fat, lactose, solids not fat (SNF) and total solids (TS). Milk quality was analyzed for total microbes, coliform bacteria, thiocyanate ($SCN^-$), lactoperoxidase (LPO), and glutathione peroxidase (GPx) activity. At farrowing, sow milk composition was not affected by experimental diets (p>0.05), but milk $SCN^-$ increased as the intake of HCN increased in sows diets (p<0.01), $r^2$ = 0.96. At mid-lactation (day 14), milk composition was not affected (p>0.05). The milk quality levels of $SCN^-$ were 9.4, 10.3, 10.5, 11.6 and 9.1 ppm for the BR100, CM50, CM75, CM100 and CB100 diets, respectively (p = 0.01). The LPO contents were 16.41, 42.13, 51.42, 53.94 and 22.81 unit/L, respectively (p = 0.03). There was no GPx activity found in sow milk. When BR was replaced with cassava meal, total microbes and coliforms were reduced 78% and 87%, respectively, by the influences of HCN. The reported beneficial effects of cassava chip meal as a basal feed in lactating sow diets is manifested by improved performance of suckling pigs. This is due to beneficial, non-toxic levels of HCN in the diets. Besides passing HCN to suckling pigs in the form of $SCN^-$, sow milk may also benefit suckling pigs with the observed (day 14) increase in lactoperoxidase content and reduction in coliform bacteria.