• Journal of Environmental Science International
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• v.8 no.1
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• pp.51-59
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• 1999

Chemical composition of atmospheric aerosols was measured at 4 sites in Pusan. All the samples were collected with a high volume air sampler from January to October 1996, to analyze major ions and heavy metals. Dominant ions of aerosols were S $O_4$$^{2-}$ in anion and N $a^{+}$ in cation. Sulfate, nitrate and ammonium ions in aerosols showed high enrichment factor to soil and seawater composition. The concentrations of heavy metals in aerosols was lowest at the site PI near the coast. The lowest concentrations of major ions and heavy metals mainly appeared in August, probably due to scavenging by frequent rains. Especially, the concentrations of total suspended particulate matter(TSP) and heavy metals in aerosols showed good correlations in Pusan. Based on crustal Al, enrichment factors for some metals(Zn, Cu, Pb, Cd) in aerosols were significantly greater than unity, and the order was Cd ＞ Pb ＞ Zn ＞ Cu. This evidence suggests that Cd and Pb are derived predominantly from non-crustal sources.s.

• Korean Journal of Soil Science and Fertilizer
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• v.48 no.5
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• pp.515-521
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• 2015

There is an increasing concern over heavy metal(loid) contamination of soil in agricultural areas including paddy soils. This study was conducted to monitor the background levels of heavy metal(loid)s, arsenic (As), cadmium (Cd), copper (Cu), mercury (Hg), nickel (Ni), lead (Pb), and zinc (Zn) in major rice growing soils and its accumulation in brown rice in Korea. The samples were collected from 82 sites nationwide in the year 2012. The mean and range values of As, Cd, Cu, Hg, Ni, Pb, and Zn in paddy soils were 4.41 (0.16-18.9), 0.25 (0.04-0.82), 13.24 (3.46-27.8), 0.047 (0.01-0.20), 13.60 (3.78-35.0), 21.31 (8.47-36.7), and 54.10 $(19.19-103.0)mg\;kg^{-1}$, respectively. This result indicated that the heavy metal(loid) levels in all sampled paddy soils are within the permissible limits of the Korean Soil Environment Conservation Act. The mean and range values of As, Cd, Cu, Hg, Ni, Pb, and Zn in brown rice were 0.146 (0.04-0.38), 0.024 (0.003-0.141), 4.27 (1.26-16.98), 0.0024 (0.001-0.008), 0.345 (0.04-2.77), 0.113 (0.04-0.197), and 22.64 $(14.1-35.1)mg\;kg^{-1}$, respectively. The mean and range BCF (bioconcentration factor) values of As, Cd, Cu, Hg, Ni, Pb, and Zn in brown rice were 0.101 (0.01-0.91), 0.121 (0.01-0.70), 0.399 (0.05-2.60), 0.061 (0.016-0.180), 0.033 (0.004-0.44), 0.005 (0.003-0.013), and 0.473 (0.19-1.07), respectively, with Zn showing the highest. The results show that the levels of all metal(loid)s in all sampled brown rice are generally within the acceptable limit for human consumption.

• The Transactions of the Korean Institute of Electrical Engineers C
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• v.48 no.5
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• pp.349-353
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• 1999

In this paper, to fabricate the AC power electroluminescent device (PELD) with high brightness, new structure that constructed single emissive layer between electrodes was proposed. Dielectric and phosphor material structure that constructed single emissive layer between electrodes was proposed. Dielectric and phosphor material were BaTiO3 and ZnS:Cu respectively. Fabricated AC power EL devices were estimated by optical and electrical properties of EL spectrum, brightness, CIE coordinate system, transferred charge density and EL emission wave in time domain. With above results, we found that brightness of newly proposed AC powder EL power EL device was 2754 cd/m2 at 100V, 400 Hz and compared with conventional device structure.

• 한국정보디스플레이학회:학술대회논문집
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• 2003.07a
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• pp.885-886
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• 2003

A bilayer is used as an anode electrode for organic electroluminescent devices. The bilayer consist of an ultrathjn ZnO layer adjacent to an hole-transporting layer and an Indium tin oxide(ITO) outerlayer. We tried to bring low the barrier between the devices as deposited ZnO films on ITO substrates. We fabricated the organic EL structure consisted of Al as cathode, $Al_{2}O_{3}$ as electro transport layer, Alq3 as luminously layer, triphenyl diamine(TPD) as hole transport layer and ZnO(l nm )/ITO(l50 nm) as anode. The result of this experiment was not good compared with the case of using ITO, Nevertheless, at this structure we obtained the lowest turn-on voltage as the value of 19 V and the good brightness (6200 $cd/m^{2}$) of the emission light from the devices. Then the quantum efficiency was to be 1.0%.

• Applied Microscopy
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• v.27 no.3
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• pp.257-263
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• 1997

Microstructural characterizations of II-VI blue laser diodes which consist of quaternary $Zn_{1-x}Mg_xS_ySe_{l-y}$ cladding layer, ternary $ZnS_ySe_{l-y}$ guiding layer and $Zn_{0.8}Cd_{0.2}Se$ quantum well as active layer were carried out using the transmission electron microscope working at 300 kV. Even though the entire structure is pseudomorphic to GaAs substrate, the structure had contained numerous extended stacking faults and dislocations which had created at ZnSe/GaAs interfaces and then further grown to the top of the epilayers. These faults might be expected to cause the degradation and shortening the lifetime of laser devices.

• Korean Journal of Environmental Agriculture
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• v.4 no.2
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• pp.88-94
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• 1985

In order to investigate the pollution potential of soils after the construction of Onsan Industrial Complex(non-ferrous metal refineries), concentrations of hazardous heavy metals were analyzed for soil samples collected from paddy, upland, orchard and forest soils around the Complex during the period of March 1978 to May 1979. The results are summarized as follows. 1) The concentrations of heavy metals (air-dry basis) for cultivated soil samples from 46 sites were obtained in the range of trace-9.3 ppm As, trace-0.6 ppm Cd, 4${\sim}$22 ppm Cu, trace-0.37 ppm Hg, 6${\sim}$43 ppm Pb and 27${\sim}$93 ppm Zn, which were regarded as non-polluted when compared with the whole Korea data for non-polluted paddy soils. 2) When the heavy metal concentrations were compared with respect to paddy, upland and orchard soils, no significant difference was observed in As, Cd, Cu and Zn whereas significant difference was observed in Hg and Pb. When they were compared with respect to region surrounding the Complex, no significant difference was observed in As, Cd, Hg whereas significant difference was observed in Cu and Pb. 3) Soil samples from several sites near Korea Zinc Refinery were contaminated with Cd, Pb and Zn, due to the accidental emission during its testing operation. Any further contamination was not observed after regular operation of the Refinery.

• Proceedings of the Korean Vacuum Society Conference
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• 2011.02a
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• pp.379-379
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• 2011

본 연구에서는 황화납(PbS)을 감응 물질로 하는 양자점 감응형 태양전지를 제작하고 효율을 측정해보았다. 기판에 진공증착을 통해 seed layer를 형성하고 수열합성법으로 산화아연(ZnO) 나노선 어레이를 기른 후 SILAR(Successive ionic layer adsorption and reaction)법으로 PbS 양자점을 합성하였고, 농도와 cycle에 따른 특성의 변화를 주사전자현미경(SEM), X-선 회절, UV-visible spectrometer를 통해 확인하였다. SILAR법을 통해 PbS가 ZnO 나노선 위에 film 형태로 균일하게 성장한 것을 확인할 수 있었고, 이렇게 합성한 물질을 직접 태양전지로 제작하여 그 효율을 측정하였다. 또한 co-sensitizer 물질로 CdS를 합성하여 두 물질의 감응 물질로서의 성능을 확인하였다. PbS는 비교적 작은 밴드갭을 가지며 양자 제한 효과가 커 밴드갭 조절이 용이하며 여러 종류의 태양전지에서 이용되고 있다. 이러한 PbS를 감응 물질로 하는 양자점 감응형 태양전지 제작을 통해 태양전지에의 적용 가능성을 살펴보고 그러기 위해 필요한 부분들을 모색해보았다.

• Korean Journal of Soil Science and Fertilizer
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• v.50 no.2
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• pp.106-114
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• 2017

There is an increasing concern over heavy metal(loid) contamination of soil in agricultural areas including paddy soils. This study was conducted to determine the bioconcentration factor (BCF) for heavy metal(loid)s to brown rice grown in paddy soils vulnerable to heavy metal(loid)s contamination, for the quantitative health risk assessment to the residents living nearby the metal contaminated regions. The samples were collected from 98 sites nationwide in the year 2015. The mean and range BCF values of As, Cd, Cu, Ni, Pb, and Zn in brown rice were 0.027 (0.001 ~ 0.224), 0.143 (0.001 ~ 2.434), 0.165 (0.039 ~ 0.819), 0.028 (0.005 ~ 0.187), 0.006 (0.001 ~ 0.048), and 0.355 (0.113 ~ 1.263), respectively, with Zn showing the highest. Even though the relationship between heavy metal(loid) contents in the vulnerable soils and metal contents in brown rice collected at the same fields was not significantly correlated, the relationship between log contents of heavy metal(loid)s in the vulnerable soils and BCF of brown rice wes significantly correlated with As, Cd, Cu, and Zn in rice. In conclusion, soil environmental risk assessment for crop uptake should consider the bioconcentration factor calculated using both the initial and vulnerable heavy metal(loid) contents in the required soil and the crop cultivated in the same fields.

• Journal of the Korean Vacuum Society
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• v.6 no.S1
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• pp.34-42
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• 1997

Hg-Te-CdTe superlattices have received much interests over the last several years as a potential material for its applications for detecting devices and optoelectronics. We have grown the HgTe-CdTe superlattice using MBE. in our lab. We have carried out DCRC spectroscopy after growth of HgTe-CdTe superlattice with varying the superlattice periods and controlling the barrier thickness and we have that the presence of the main peak and the satellite peaks. We obtained 20 arcsec of FWHM over 100 periods of superlattice. We also note that high peak intensity shows the high quality of the sample and each layer of superlattice has abrupt interfaces. The angular separation between the main peak(m=0) and the first satellite peak(m=$\pm$1) is increased when the barrier layer thickness in superlatice layers are decreased. The separation between the first setellite peak(m=$\pm$1) and the second satellite peak(m$\pm$2) is increased similarly. The number of the satellite peak is a qualitative measure of the interfacial abruptness of the superlattice.

• Electrical & Electronic Materials
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• v.17 no.5
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• pp.13-20
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• 2004

1996년 GaN와 near band edge emission(NBE) 및 yellow deep-defect level emission의 발광 기구가 ZnO의 greene mission과 매우 유사하다는 점이 발견된 이 후［1,2］, II-VIZnO반도체에 대한 광학적 성질에 많은 관심이 집중되기 시작하였다. 1960년대 C. Klingshirin［3］에 의해 bulk ZnO의 exciton luminescence가 관측된 이래로, 1980년대 후반부터 적층 박막 성장 법들이 급속도로 발전을 하여 오고 1988 S. Bethke등이 CVD로 성장한 ZnO의 NBE emission에 관심을 갖기 시작하였고［4］, 1996년 2K에서 GaN, ZnO사이의 유사한 발광기구가 알려졌고［5］, 도호쿠 및 일본 공업대에서 ZnO의 적층 성장 및 상온에서 defect에 기인한 emission이 없는 깨끗한 PL 의 관측, 상온 lasing, 육방정계 결정 구조에서 비롯된 6-fold symmetry PL 등이 보고되기 시작하였다. ［6-8］ 2000년에 들어서면서 MgO와 CdO와의 solid solution에 의한 밴드갭을 2.6-4.2 eV 까지 조절하는 가능성이 보고되었고 이를 이용한 ZnO/MgZnO MQW 구조에 대한 연구도 병행되었다.(중략)