• Advances in environmental research
• /
• 제6권4호
• /
• pp.241-254
• /
• 2017

This study was conducted to investigate the levels of heavy metals in twelve species of vegetables and assessment of health risk. Samples were analyzed using inductively coupled plasma mass spectrometer (ICP-MS). The ranges of Cr, Ni, Cu, As, Cd and Pb in vegetables species were 0.37-5.4, 0.03-17, 0.35-45, 0.01-2.6, 0.001-2.2, and 0.04-8.8 [mg/kg, fresh weight (fw)], respectively. The concentrations of As, Cd and Pb in most vegetable species exceeded the maximum permissible levels, indicating unsafe for human consumption. Health risks associated with the intake of these metals were evaluated in terms of estimated daily intake (EDI), and carcinogenic and non-carcinogenic risks by target hazard quotient (THQ). Total THQ of the studied metals from most of the vegetables species were higher than 1, indicated that these types of vegetables might pose health risk due to metal exposure. The target carcinogenic risk (TR) for As ranged from 0.03 to 0.48 and 0.0004 to 0.025 for Pb which were higher than the USEPA acceptable risk limit (0.000001) indicating that the inhabitants consuming these vegetables are exposed to As and Pb with a lifetime cancer risk. The findings of this study reveal the health risks associated with the consumption of heavy metals through the intake of selected vegetables in adult population of Bangladesh.

• 한국전기전자재료학회논문지
• /
• 제14권1호
• /
• pp.20-25
• /
• 2001

To develop the piezoelectric actuator, the structural, dielectric and piezoelectric properties and electric fieldinduced strain of the ceramics(Pb$\_$1-2/Ba$\_$x/)[Mg$\_$1/2/W$\_$1/2/)$\_$0.03/-Ni$\_$1/3/Nb$\_$2/3/)$\_$0.12/-(Zr$\_$0.5/Ti$\_$0.5/)$\_$0.85/]O$_3$(x=0, 0.01, 0.03, 0.05, 0.07, 0.1) were investigated with the substitution of Ba. The tetragonality of crystal structure and grain size decreased by the substitution of Ba. Curie temperature decreased due to the decrease of the tetragonality, and dielectric constants increased with the substitution of Ba. The coercive field, remnant polarization and electromechanical coupling factor also decreased, whereas the piezoelectric constatns d$\_$33/ and d$\_$31/ were showed the highest value of 430 and 209(x10$\^$-12/C/N), respectively, because of the increase of dielectric constant. The strain induced by 60Hz AC electric field had the maximum value of 204x10$\^$-6/Δℓ/ℓ at the substitution of Ba 3mol%. As the applied electric field approaches to the coercive field, the piezoelectric element is depolarized and the electric field induced strain revealed non-linearity.

• 한국전기전자재료학회논문지
• /
• 제28권3호
• /
• pp.160-164
• /
• 2015

In this study, $(1-x)Pb(Mg_{1/2}W_{1/2})_{0.03}(Ni_{1/3}Nb_{2/3})_{0.09}(Zr_{0.5}Ti_{0.5})_{0.88}O_3+xCeMnO_3$ (x= 0~0.02) ceramics were prepared by Columbite precursor method. The phase structure, ferroelectric and piezoelectric properties were systematically investigated. It was found that PMW-PNN-PZT possessed superior electrical properties due to its composition close to the MPB (morphotropic phase boundary). Coercive electric field of 10.05 [kV/cm] and density of 7.88 [$g/cm^3$] were obtained when the substitution amount of $CeMnO_3$ is x=0.02. In contrast, specimens with x=0.01 showed the mechanical quality factor($Q_m$) of 1,091 and the electromechanical coupling factor($k_p$) of 0.613.

• 한국전기전자재료학회:학술대회논문집
• /
• 한국전기전자재료학회 2008년도 추계학술대회 논문집 Vol.21
• /
• pp.222-223
• /
• 2008

Recently, piezoelectric transformer is applied to wide fields. Multi layer piezoelectric transformer has the advantage of high step up ratio, high electromechanical coupling coefficient(Kp) and high mechanical quality factor(Qm), however it shows the peeling-phenomenon of electrode, and high price due to high sintering temperature. Therefore this study focus on the method for fabrication of high power rosen type piezoelectric transformers. The composition of $0.01Pb(Ni_{1/3}Nb_{2/3)O_3$ - 0.08Pb$(Mn_{1/3}Nb_{2/3})O_3$-0.91Pb$(Zr_{0.505}Ti_{0.495})O_3$(abbreviated as PNN-PMN-PZT) ceramics is employed for this study.

• 대한가정학회지
• /
• 제18권1호
• /
• pp.41-46
• /
• 1980

In order to verify to what extent the rancidity of the soybean oil is occurred and how the various metal ions effect on the rancidity-as a result of applying heat to the soybean oil-the followings are obtained through experiments : 1. From analyzing the refractive index of soybean oil, The results are: the specific gravity-0.925 refractive index-1.475, saponification value-190, acetyl value-5.0, iodine value-120, peroxide value-5.0. 2. The degree of expediting rancidity take the following order : $Cu^{++}$/$Fe^{++}$/$Cr^{++}$/$Zn^{++}$/$Ni^{++}$/$Al^{+++}$. 3. The degree of expediting rancidity of $Cu^{++}$and $Fe^{++}$ is showed the abrubt increase of peroxide value in accordance with the increase of densidity. The most abrubt increase of peroxide show when the duration of heating reaches to the range between 20 minutes and 30 minutes. After heating for 60 minutes no definite variation is showed. 4. The degree of rancidity in heating the soybean oil added $Cu^{++}$, Fe and BHA shows the decrease of peroxide value by 2, 3 after adding $Cu^{++}$0.5 ppm. and heating for 30 minutes. As the result of measuring the value of peroxide after adding $Cu^{++}$ by 1.0 ppm and BHA by 0.01% and heating, peroxide shows the decrease by 7.8 when adding anti-oxidant. $Fe^{++}$ as well as $Cu^{++}$ shows that BHA prevents the metal ions from the expedition of rancidity.

• 한국환경과학회:학술대회논문집
• /
• 한국환경과학회 2005년도 추계 학술발표회 발표논문집
• /
• pp.29-32
• /
• 2005

주거지역 A와 주거지역 B의 PM10 평균농도 비교에서 산업지역과 인접한 주거지역 A에서 계절에 관계없이 26-32% 높은 농도를 나타내어 산업지역에 인접한 주거지역 A가 먼 주거지역 B 보다 PM10의 영향에 더 크게 노출된 것을 확인 할 수 있었다. PM10에 포함된 Cd, Cr, Cu, Fe, Mn, Ni, Pb, Zn 등의 무기성분은 대부분 인위적인 발생원과 관련성이 있는 대기 오염물질로, 인위적인 배출원의 영향정도를 파악하기 위하여 풍성계수 분석결과 높은 풍성계수를 나타내어 인위적인 오염원임을 확인 할 수 있었고, 그 평균농도는 주거지역 A가 주거지역 B 보다 높게 나타나 주거지역 A가 주거지역 B 보다 산업 오염원의 노출에 더 많은 영향을 받는 다는 것을 확인 할 수 있었다. 또한 이들 무기화합물질의 상관성 분석결과 높은 상관성과 통계적인 유의성 (p<0.01)이 있었으며, 공통의 오염원을 추정 할 수 있었다. PM10의 가능한 오염원 기여도 평가에 있어서, 주거지역 A에서는 제철관련 오염원과 토양오염원의 공통 오염원 기여도가 33.4%로 나타나 산업관련 오염원의 기여도를 뚜렷하게 분리하여 평가하기는 곤란하였으나, 주거지역 B에서 토양관련 오염원의 독립적인 농도 기여도가 54%로 높게 나타났기 때문에, 상대적으로 산업지역과 인접한 주거지역 A에서 산업관련 오염원 기여도가 높은 것을 알 수 있었다.

• Membrane and Water Treatment
• /
• 제8권6호
• /
• pp.575-590
• /
• 2017

PolyHIPEs membrane prepared with styrene (St), divinylbenzene (DVB), and ethylhexyl acrylate (EHA) can yield a unique pore structure provided by large voids highly interconnected by many small window throats. With the advantageous pore structure, PolyHIPE presents a potential as a support for carrier facilitated transport membrane. Tricaprylmethylammonium chloride (Aliquat 336) can be efficiently incorporated into the PolyHIPE membrane by a two-step solvent-nonsolvent method to obtain an Aliquat 336-immobilized PolyHIPE membrane with good stability. The study of Cr (VI) transport through Aliquat 336-immobilized PolyHIPE membrane indicates that the membrane has high initial flux and maxima stripping flux ($J_f^o=15.01({\mu}mol/m^2s)$, $J_s^{max}=6.15({\mu}mol/m^2s)$). The reusability study shows that the Aliquat 336-immobilized PolyHIPE membrane can maintain high Cr(VI) recovery efficiency even after 15 cycles of operations. The developed membrane was also used in the separation of Cr (VI) from other anions (i.e., $SO_4{^{2-}}$ and $NO_3{^-}$) and other cations (i.e., Ni (II), Mg (II) and Cu (II)) with good selectivity.

• Fisheries and Aquatic Sciences
• /
• 제23권7호
• /
• pp.18.1-18.10
• /
• 2020

During June 2017, we collected two postflexion larvae (6.01 and 7.56 mm in standard length [SL]) and two juveniles (7.72 and 9.62 mm SL) belonging to Myctophidae in the waters of Jejudo Island. Those four individuals were identified as Diaphus garmani, which had not been reported in Korea. They were distinguished from Benthosema pterotum by melanophores in the abdominal cavity (absent in D. garmani vs. present in B. pterotum) and the development of photophores (developed in D. garmani vs. rudimentary in B. pterotum) when shorter than 10.0 mm SL. Analysis of 16S rRNA sequences showed that the sequences of four individuals matched those of adult D. garmani (Kimura 2-parameter distance: 0.6-0.8%). This is the first record of larvae and juveniles of D. garmani in Korean waters, and we propose a new Korean name, Gar-ma-ni-sat-bi-neul-chi.

• 자원리싸이클링
• /
• 제7권2호
• /
• pp.9-15
• /
• 1998

석유 탈황 폐촉매 중의 바나듐을 습식법으로 회수한 후의 라피네이트로부터 몰리브덴을 회수하기 위한 연구를 수행하였다. 이 라피네이트의 조성은 Mo 1,100 ppm, V150ppm, Al 19 ppm, Ni 33 ppm으로 이루어져 있으며, 이 수용액 중의 몰리브덴을 효율적으로 분리.회수하기 위하여, 킬레이트수지에 의한 흡착 또는 3급 아민에 의한 용매추출법에 의하여 분리하는 방법을 적용하였다. 킬레이트수지에 의한 Mo의 흡착은 폴리에틸렌 아민형 킬레이트수지에 의하여 몰리브덴을 선택 흡착시킨 후, $3.0mol/{dm}^{3}$-$NH_4$OH을 용리제로 사용하여 $60g/{dm}^{3}$의 몰리브덴으로 농축할 수 있었다. 한편, 용매추출법으로는 2N-HCl으로 접촉시켜 전처리한 10vol%-Alamine 336에 의하여 몰리브덴이온은 전 pH 범위에서 100%의 추출율을 나타내었다.

• 한국전기전자재료학회:학술대회논문집
• /
• 한국전기전자재료학회 2005년도 추계학술대회 논문집 Vol.18
• /
• pp.212-213
• /
• 2005

In this study, in order to develop low temperature sintering piezoelectric actuator, $Pb_{0.985}Bi_{0.01}(Mg_{1/2}W_{1/2})_{0.03}(Ni_{1/3}Nb_{2/3})_{0.13}(Zr_{0.50},Ti_{0.50})_{0.84}$ (PMW-PNN-PZT) ceramic systems were fabricated using $CaCO_3-Li_2CO_3$, sintering aid through a post-annealing process. The sinterability of PMW-PNN-PZT ceranics was remarkably enhanced by liquid phase sintering of $CaCO_3$ and $Li_2CO_3$. But, it was confimed form the X-ray diffraction pattern that the secondary phase along grain boundaries, deteriorated the piezoelectric properties. The secondary phase along grain boundaries was significantly removed by annealing after sintering. The 0.2wt% $Li_2CO_3$-0.25wt% $CaCO_3$-added PMW-PNN-PZT ceramics post-annealed at 900$^{\circ}C$ for 90min exhibited the excellent electromechanical coupling factor($k_p$) of 63.3% and piezoelectric constant($d_{33}$) of 452pC/N, respectively, for multilayer piezoelectricactuatorapplication.