• E2M - 전기 전자와 첨단 소재
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• 제10권5호
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• pp.434-439
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• 1997

It this paper, the piezoelectric and electro-induced strain properties of (P $b_{1-}$2x/3/B $i_{x}$ )[N $i_{1}$3/N $b_{2}$3/)$_{0.4}$( $Ti_{0.6}$Z $r_{0.4}$)$_{0.6}$] $O_3$ceramics (x=0, 0.005, 0.02) were investigated with the substitution of B $i^{3+}$, and the feasibility of the application for bimorph actuator was evaluated by measuring the dynamic properties of the piezoelectric bimorph fabricated with above ceramics. Dielectric constant was enhanced with the increase of B $i^{3+}$ substitution, and appeared the maximum value of 5032 at x=0.01 composition. Increasing the substitution of B $i^{3+}$, the electromechanical coefficient( $k_{p}$ , $k_{31}$ ) was increased up to the substitution of 0.5 mol% B $i^{3+}$, showed the value of 0.656, 0.439, respectively. The piezoelectric constant( $d_{33}$ $d_{31}$ ) had the highest value of 344, 825 with the substitution of 0.5 mol% B $i^{3+}$. The strain, generated by 60 Hz AC electric field, had the largest value of 1200($\times$10$^{-6}$ $\Delta$1/1) in the composition with the substitution of 0.5 mol% B $i^{3+}$. The dynamic properties of the bimorph actuator, fabricated with the composition substitution of 0.5 mol% B $i^{3+}$, showed the largest value of 325 $\mu$m at $\pm$150 V square pulse. square pulse.are pulse..

• 대한화학회지
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• 제41권7호
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• pp.337-342
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• 1997

본 연구에서는 benzo-15-crown-5(B15C5)와 poly(acryloylmethylbenzo-15-crown-5)[poly(AMB15C5)] 화합물을 이온선택성 물질로 이용해서 $Pb^{2+}$를 전위차법으로 정량할 수 있는 탐침형 이온선택성 전극(coated wire-ion-selec-tive electrode[CWISE])을 개발하였다. 각각 감지막의 최적 조성은 B15C5의 경우에는 리간드 20 mg, 가소제인 tris(2-ethylhexyl) ester 165 mg, 지지체인 polyvinylchloride 75 mg 및 용매인 THF 0.7 mL이었으며 poly(AMB15C5) 경우에는 리간드 35 mg, 가소제인 tris(2-ethylhexyl) ester 160 mg, 지지체인 PVC [Polyvinyl Chloride] 70 mg 및 용매인 THF 2 mL이었다. 이 때 코팅용액의 리간드에 대한 무게함량은 각각 7.7%와 13.1%이었다. 각각의 전극은 $10^{-5} M{\sim}10^{-1}$ M 농도 범위에서 기울기가 28{\pm}1$ mV/decade인 직선성이 잘 성립하는 감응을 나타내었다. 또한 전극의 감응시간은 poly(AMB15C5) 경우에는 5분 이내였으며 B15C5의 경우에는 3분이내로 비교적 빠른 편이었다. 전극의 안정성은 크라운 에테르의 물에 대한 용해도 때문에 좋은 편은 아니었다. 최적 pH 조건은 pH 3~6이었으며 $Mg^{2+},\; Ca^{2+},\; Co^{2+},\; Ni^{2+},\; Cu^{2+},\; Zn^{2+}$ 및 $Cd^{2+}$는 방해가 거의 없었으나 $Na^+$와 $K^+$는 방해효과가 컸다. 그리고 본 연구에서 제조한 탐침형 이온선택성 전극을 이용하여 $Pb^{2+}$ 이온을 전위차 적정법으로 정량분석해 보았을 때 이론적인 당량점과 종말점이 잘 일키하는 결과를 얻었다.

• 한국축산시설환경학회지
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• 제18권3호
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• pp.201-206
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• 2012

말의 성장단계별 분뇨의 시료를 채취하여 비료성분 및 오염물질 성분을 채취하여 분석하여 본 결과 다음과 같았다. 1. 말의 분뇨의 수분함량은 각각 76.1%, 96.0%로 조사되었다. 2. 또한 말의 분 중 유기물함량은 21.3%로 조사되었으며, 뇨는 약 2.0%로 조사되었다. 3. 또한 말의 분뇨 중 비료성분인 T-N, T-P, T-K의 성분이 각각 0.18%, 0.10% 및 0.23% 이며, 뇨는 각각 2.88%, 0.0015% 및 0.84%로 조사되었다. 4. 말 분뇨의 오염물질을 조사한 결과, 말의 분뇨의 pH는 각각 7.10, 8.48이며, BOD는 분이 26,906.2 $mg/{\ell}$, 뇨는 14,298.9 $mg/{\ell}$, COD는 분이 36,642.3 $mg/{\ell}$, 뇨는 7,484.3 $mg/{\ell}$, SS (Suspended Solid, 부유물질)은 분에서 89,375.0 $mg/{\ell}$, 뇨에서 6,987.0 $mg/{\ell}$로 조사되었다. 5. 말의 분과 뇨의 중금속함량 중 Cr은 각각 2.65 mg/kg, 1.52 mg/kg으로 조사되었으며, Cu 성분도 7.05 mg/kg, 1.62 mg/kg 으로 조사된 반면에 Ni 성분은 말의 분뇨에서 각각 1.24 mg/kg, 0.0 mg/kg으로 조사되었다. 6. 따라서 말의 분뇨는 퇴비원료물로 사용이 가능한 것으로 조사 분석되었으며, 향후 승마사업의 급격한 발전으로 말의 분뇨 발생량이 증가될 것으로 전망되며, 이를 적정 처리하기 위해서는 퇴비화 방법으로 자원화가 가능 할 것으로 조사되었다.

• 한국토양비료학회지
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• 제46권3호
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• pp.193-202
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• 2013

The concentrations of heavy metals such as cadmium (Cd), chromium (Cr), copper (Cu), lead (Pb), zinc (Zn), nickel (Ni), and arsenic (As) in sand samples collected from selected children's playground and their correlation with environmental parameters, such as concentration of particulate matter in the atmosphere ($PM_{10}$), apartment age (> 5 years), clay and organic matter contents in sand samples, were analyzed. The average heavy metal concentration in samples was 0.040 mg $kg^{-1}$ for Cd, 0.200 mg $kg^{-1}$ for Cr, 1.75 mg $kg^{-1}$ for Cu, 15.1 mg $kg^{-1}$ for Ni, 3.42 mg $kg^{-1}$ for Pb, 66.7 mg $kg^{-1}$ for Zn and 0.750 mg $kg^{-1}$ for As, all of which were below the environmental regulatory level established by Korea Ministry of Environment. However, in the consideration of direct and oral exposure by children to playground sand, the risk of the concentration range in the samples might be greatly enhanced. Heavy metal concentration in samples collected from high $PM_{10}$ (> $70{\mu}gm^{-3}$) area was slightly greater than in samples from low $PM_{10}$ (< $70{\mu}gm^{-3}$), indicating the contribution of particulate matter in air phase to heavy metal concentration in playground sand samples. The concentrations of both Cd and Pb were the highest in apartments older than 21 years (0.050 mg $kg^{-1}$ and 5.28 mg $kg^{-1}$ for Cd and Pb respectively) and showed positive correlation with apartment age (p<0.01 and p<0.001 for Cd and Pb, respectively). Clay content in playground sands ranged 3.8~11.2% and was positively correlated with heavy metal concentration. Organic matter content was negligible (mostly < 0.1%) and showed poor correlation with heavy metal concentration. In conclusion, concentration of heavy metals in playground sand was found to be predominantly influenced by the apartment age and clay content in sand samples and supplemented by dust deposition of particulate matter ($PM_{10}$) from atmosphere.

• 미래기술융합논문지
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• 제1권2호
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• pp.11-17
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• 2022

본 연구는 X선 검사실에서 환자와 함께 있어야 하는 상황에 의료종사자가 최소한의 선량을 받을 수 있는 위치를 알아보고자 한다. RQR 표준 선질을 설정하기 위해 가로, 세로 10 cm인 Al 1.5 mm의 부가여과판을 X선관에 부착하였다. 부가여과판은 Al 0.9 mm, Cu 0.3 mm, Ni 0.3 mm를 사용하였다. Acrylic Phantom은 각각 13.1 cm, 18.5 cm, 21.2 cm으로 설정하여 피사체 두께를 달리하였다. 그 결과 Al 0.9 mm를 사용하였을 때 Acrylic Phantom 13.1 cm의 anode low 50 cm 위치가 1853 nSv로 산란선의 영향을 가장 많이 받았고, Cu 0.3 mm를 사용하였을 때 Acylic Phantom 두께 13.1 cm의 anode low 150 cm 위치가 173 nSv로 산란선의 영향을 가장 적게 받았다. 본 연구로 X선관과 멀어질수록 공간산란선량이 감소되는 것을 확인하였다. 향후 산란선량의 피폭에 대한 더 많은 연구가 필요할 것으로 사료된다.

• Nuclear Engineering and Technology
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• 제55권3호
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• pp.1061-1070
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• 2023

Over the last few years, lead-free inorganic metal perovskites have gained impressive ground in empowering satellites in space exploration owing to their material stability and performance evolution under extreme space environments. The present work has examined the versatility of eight such perovskites as space radiation shielding materials by computing their photon, charged particles and neutron interaction parameters. Photon interaction parameters were calculated for a wide energy range using PAGEX software. The ranges of heavy charged particles (H, He, C, N, O, Ne, Mg, Si and Fe ions) in these perovskites were estimated using SRIM software in the energy range 1 keV-10 GeV, and that of electrons was computed using ESTAR NIST software in the energy range 0.01 MeV-1 GeV. Further, the macroscopic fast neutron removal cross-sections were also calculated to estimate the neutron shielding efficiencies. The examined shielding parameters of the perovskites varied depending on the radiation type and energy. Among the selected perovskites, Cs₂TiI₆ and Ba₂AgIO₆ displayed superior photon attenuation properties. A 3.5 cm thick Ba₂AgIO₆-based shield could reduce the incident radiation intensity to half its initial value, a thickness even lesser than that of Pb-glass. Besides, CsSnBr₃ and La_0.8Ca_0.2Ni_0.5Ti_0.5O₃ displayed the highest and lowest range values, respectively, for all heavy charged particles. Ba₂AgIO₆ showed electron stopping power (on par with Kovar) better than that of other examined materials. Interestingly, La_0.8Ca_0.2Ni_0.5Ti_0.5O₃ demonstrated neutron removal cross-section values greater than that of standard neutron shielding materials - aluminium and polyethylene. On the whole, the present study not only demonstrates the employment prospects of eco-friendly perovskites for shielding space radiations but also suggests future prospects for research in this direction.

• Asian Pacific Journal of Cancer Prevention
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• 제15권1호
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• pp.69-73
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• 2014

The effects of erlotinib combined with celecoxib in a lung cancer xenograft model were here explored with a focus on possible mechanisms. A xenotransplanted lung cancer model was established in nude mice using the human lung cancer cell A549 cell line and animals demonstrating tumour growth were randomly divided into four groups: control, erlotinib, celecoxib and combined (erotinib and celecoxib). The tumor major axis and short diameter were measured twice a week and after 40 days tissues were collected for immunohistochemical analyses of Bcl-2 and Bax positive cells and Western-blotting analyses for the epidermal growth factor recepto (EGFR), P-EGFR, and cyclooxygenase-2 (COX-2). Tumor size in the combined group was smaller than in the others (p<0.01) and the percentage of Bcl-2 positive cells was fewer in most cases (p<0.01), while that of Bax positive cells was greater than in the erlotinib and celecoxib groups (P>0.05). Western blotting showed decreased expression of P-EGFR and COX-2 with both erlotinib and celecoxib treatments, but most pronouncedly in the combined group (P<0.05). Simultaneous blockage of the EGFR and COX-2 signal pathways exerted stronger growth effects in our human xenotransplanted lung cancer model than inhibition of either pathway alone. The anti-tumor effects were accompanied by synergetic inhibition of tumor cell apoptosis, activation of p-EGFR and expression of COX-2.

• 대한치과보철학회지
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• 제35권4호
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• pp.647-661
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• 1997

The resin modified glass ionomer cements(RMGICs) have been used for years since 1989. Recently it has been developed for luting of fixed restorations. To evaluate the bond strength and marginal leakage of RMGICs for luting usage, the 80 extracted human molars which had uniform area of exposed dentin were cemented with 3 types of RMGICs(Fuji Duet, Advance, Vitremer), a conventional Glass Ionomer Cement(GIC-Fuji I), and a resin cement (Panavia 21) to base metal alloy(Ni-Cr-Be). After thermocycling the specimens were immersed in basic fuschin dye for measuring marginal leakage. The shear bond strength was measured with Instron and the maximum dye penetration was measured to 0.1mm. The types of fractured patterns were determined with stereoscope(${\times}7.5$). The results are as follows. 1. The difference between 3 RMGICs and a conventional GIC in shear bond strength was not statistically significant. It seemed that RMGICs had lower shear bond strength than resin cement. (p<0.01) 2. The mean scores of marginal leakage had no significant difference between the resin cement and 3 RMGICs but it was much higher in conventional GIC than the RMGICs (p<0.05) 3. It was determined that the manufacturer and the methods of dentin pretreatment determined the pattern of fracture surfaces and the frequency of adhesive failure between teeth and 3 RMGICs standed as in following order - Vitremer, Advance, Fuji Duet. (p<0. 01) When the fracture pattern was analyzed, it could be said that the materials and the method of dentin pretreatment have much effect on bonding states. This means that the dentin bonding agents should be improved. But the limited products in this experiment can not evaluate the physical properties of the entire RMGICs. Therefore a further study which can evaluate various RMGICs should be in progress to develope better cements.

• 한국해양학회지
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• 제9권1_2호
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• pp.31-38
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• 1974

해저퇴적물의 물리화학적인 성질은 저서생물의 환경요인의 하나로 알려져 있다. 아울러 저서어종의 어장형성과도 밀접한 관계가 있다. 한국 근해 퇴적물의 물리적인 특성은 Zenkevitch(1963), 박과 송(1972)이 동해안의 일부에서 조사연구하였고 박과 송(1971), 권과 박(1973)이 남해안에서의 해저퇴적물 입도분석을 발표한 바 있다. 한국 연안해역 해저퇴적물의 지화학적인 특성은 Nino et al(1969)이 동해 저질중의 유기태탄소의 함량 Ishibashi and Ueda(1955, 1993)의 화학적 특성, 그리고 최(1971) 에 의한 동해 해저퇴적물의 지화학적 성분의 함량과 분포에 관한 발표가 주를 이루고 있다. 행암만과 가덕도 일원에 걸쳐 조사한 결과에 의하면 행암만내의 조석현상등에 의한 해수의 유동은 만의 동단으로 향하는 것으로 나타났다.(강, 1972, 수산진흥원, 1972). 따라서 본 연구의 목적은 육상 토사와 이에 따른 각종 중금속류의 연안유입 및 각종 산업활동에 기인하는 여러 가지 중금속류의 해수내 유입여하에 따른 침전현상과 이동범위를 조사 연구하는데 있었다.

• 한국대기환경학회지
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• 제27권5호
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• pp.523-533
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• 2011

This study had the aim of characteristics of $PM_{10}$ in subway cabins. $PM_{10}$ was measured by times of day (rush and non rush hours) and seasons with real time $PM_{10}$ sampler on the subway cabins of line 7. Filter samples were collected for evaluation of their elemental composition as well as identification of major sources of $PM_{10}$ using a receptor model, PMF. $PM_{10}$ concentration were the highest in the winter season both in the rush and non rush hours at 152.8 ${\mu}g/m^3$, 90.2 ${\mu}g/m^3$ respectively. The $PM_{10}$ concentrations in rush hour were 30% higher compared to non rush hours. Based on the chemical information, the composition rare of inorganic elements was 52.5%, anions were 10.2% and others were 37.3%. Fe was the most abundant element and significantly correlated (p.0.01) with Mn (r=0.97), Ti (r=0.91), Cr (r=0.88), Ni (r=0.89) and Cu (r=0.88). Characterized $PM_{10}$ sources by PMF in the cabin were soil and road dust related sources (27.2%), railroad related sources (47.5%), secondary nitrate sources (16.2%) and a Cl-factor mixed with a secondary sulfate source (9.1%).