• Bulletin of the Korean Chemical Society
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• 제31권9호
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• pp.2503-2508
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• 2010

ZnO thin films were grown on Si or $SiO_2$/Si substrates, at growth temperatures ranging from 150 to $400^{\circ}C$, by atomic layer deposition (ALD) using diethylzinc and water. Despite the large band gap of 3.3 eV, the ALD ZnO films show high n-type conductivity, i.e. low resistivity in the order of $10^{-3}\;{\Omega}cm$. In order to understand the high conductivity of ALD ZnO films, the films were characterized with X-ray diffraction, transmission electron microscopy, X-ray photoelectron spectroscopy, elastic recoil detection, Rutherford backscattering, Photoluminescence, and Raman spectroscopy. In addition, the various analytical data of the ZnO films were compared with those of ZnO single crystal. According to our analytical data, metallic zinc plays an important role for the high conductivity in ALD ZnO films. Therefore when the metallic zinc was additionally oxidized with ozone by a modified ALD sequence, the resistivity of ZnO films could be adjusted in a range of $3.8{\times}10^{-3}\;{\sim}\;19.0\;{\Omega}cm$ depending on the exposure time of ozone.

• 한국강구조학회 논문집
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• 제28권2호
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• pp.97-108
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• 2016

금속용사 또는 도장은 강구조물의 방식에 널리 사용되고 있다. 금속용사와 도장의 복합피복방식법은 혹독한 부식환경하에 놓인 강구물의 새로운 일반적 피복방식법으로 선택되고 있다. 본 연구에서는 아연, 아연-15%알루미늄 합금, 알루미늄, 알루미늄-5%마그네슘 합금의 4종류 금속용사 후 실링 처리한 시편, 4종류 금속용사 후 중방식 도장한 시편과 도장한 시편에 대해 175일간의 NORSOK M-501 부식촉진실험, 250일간의 해수 Wet/dry 반복 부식실험, 3년간의 해양환경 옥외노출실험을 실시하였다. 그 결과, 외관관찰에 근거하여 각 방식법의 내후성능을 비교, 검토하였다.

• 대한전기학회논문지:전기물성ㆍ응용부문C
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• 제55권5호
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• pp.257-262
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• 2006

To evaluate the change in protective levels of zinc oxide (ZnO) varistors after the surge absorption, this paper investigated the effects of the number of injection and amplitude of lightning surges on the life of ZnO varistors for low voltages. Leakage currents flowing through ZnO varistors subjected to the $8/20{\mu}s$ impulse currents under 60 Hz AC voltages were measured. The surge simulator system ECAT that can generate $8/20{\mu}s$ impulse currents with a peak short-circuit of 5 $[kA_p]$ was used. The ZnO varistor leakage current increases with exposure to impulse current, and the number of injection of $8/20{\mu}s$ impulse currents to breakdown was inversely proportional to the amplitude of the test current. Behaviors of ZnO varistor leakage currents were strongly dependent on the number of injection and amplitude of $8/20{\mu}s$ impulse currents. ZnO varistors degrade gradually when subjected to impulse current, and the resistive leakage current flowing through ZnO varistors subjected to the $8/20{\mu}s$ impulse currents under 60 Hz AC voltages was significantly increased after a certain number of injection that is dependent on the amplitude of the test impulse current. As a result, the life of ZnO varistors mainly depends on the amplitude and occurrence frequency of lightning surges.

• The Korean Journal of Ecology
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• 제26권3호
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• pp.91-96
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• 2003

집비둘기 Columba livia 깃털의 중금속 농도를 파악하기 위하여 서울시에 서식하는 집비둘기를 서식지 환경에 따라 공단, 상업, 공원 및 주거지역으로 나누어 각 지역에 서식하는 개체들을 채집, 중금속 농도를 측정하였다. 깃털 중 철(Fe)의 농도는 공원지역에서, 망간(Mn)은 공업지역과 공원지역에서, 구리(Cu)는 공원지역에서 다른 지역에 비해 월등히 높게 나타났으며, 각 원소별로 지역간에 유의차가 존재하였다(ANOVA, p<0.05). 또한 아연(Zn)은 도심상업지역에서, 납(Pb)은 공업지역에서, 카드뮴(Cd)은 주거지역이 다른지역에 비해 약간 높았지만 지역별로 유의적인 차이가 나타나지 않았다. 간에서의 중금속농도와 깃털에서의 중금속농도와의 상관관계는 구리(r²=0.983, p<0.01)와 카드뮴(r²=0.632, p<0.01)에서 고도의 유의차가 나타났지만, 다른 원소에서는 유의성이 나타나지 않았다.

• 한국재료학회지
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• 제27권12호
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• pp.658-663
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• 2017

Urchin-structured zinc oxide(ZnO) nanorod(NR) gas sensors were successfully demonstrated on a polyimide(PI) substrate, using single wall carbon nanotubes(SWCNTs) as the electrode. The ZnO NRs were grown with ZnO shells arranged at regular intervals to form a network structure with maximized surface area. The high surface area and numerous junctions of the NR network structure was the key to excellent gas sensing performance. Moreover, the SWCNTs formed a junction barrier with the ZnO which further improved sensor characteristics. The fabricated urchin-structured ZnO NR gas sensors exhibited superior performance upon $NO_2$ exposure with a stable response of 110, fast rise and decay times of 38 and 24 sec, respectively. Comparative analyses revealed that the high performance of the sensors was due to a combination of high surface area, numerous active junction points, and the use of the SWCNTs electrode. Furthermore, the urchin-structured ZnO NR gas sensors showed sustainable mechanical stability. Although degradation of the devices progressed during repeated flexibility tests, the sensors were still operational even after 10000 cycles of a bending test with a radius of curvature of 5 mm.

• 농업과학연구
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• 제47권4호
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• pp.979-985
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• 2020

A wide range of techniques have been developed to separate X or Y- chromosome-bearing sperm. In particular, bovine semen sex-sorted by using flow cytometry based on differences in the amount of DNA between X and Y chromosome bearing sperm is used in dairy farms. The first piglets were produced using sex-sorted sperm 30 years ago. However, sexed sperm have not been commercially available in pigs because the flow cytometry technique is not capable of sorting the high number of sperm required for porcine artificial insemination (AI), and the prolonged exposure to an electrical filed might damage to the DNA in sperm. The purpose of this study was to evaluate a boar sperm sorting method based on magnetic nanoparticles. A flow cytometer assay verified the efficacy of the magnetic nanoparticles (> 90% of sex-sorted sperm). In addition, a duplex polymerase chain reaction (PCR) assay using sex chromosome specific genes including SRY (sex-determining region Y; male), ZFY (zinc finger protein Y-linked; male), and ZFX (zinc finger protein X-linked; female) showed that in vitro fertilized porcine embryos by X and Y-chromosome bearing sperm were 100% female (40/40) and 72% female (35/48), respectively, at 8-cell or morula stages, suggesting that the sex-sorted sperm were fertile. In conclusion, our findings suggest that the sex-sorted method based on magnetic nanoparticles can be utilized for porcine sex-sorted AI.

• Journal of Preventive Medicine and Public Health
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• 제22권1호
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• pp.125-135
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• 1989

정신지체아 발생의 환경인자로서의 납의 영향을 관찰하기 위하여 인제조직내의 축적된 납과 아연의 함량과 정신장애 정도와의 상관성을 보았다. 대상은 정신지체아 교육기관 2곳의 계 297명을 택하였다(부모가 있는 군 132명, 없는 군 165명). 대조군은 시내 모 국민학교에 정상적으로 수업을 받는 63명을 심의로 선택하였다. 재료는 대상자의 후두부의 모발을 채취하여 원자흡광분광광도계로 분석하였다. 두발중 납의 평균함량은 정신지체아에서 $14.97{\pm}3.71ppm$으로 정상아의 $11.36{\pm}2.83ppm$보다 유의하게 높았으며 아연 함량은 유의한 차이가 없었다. 납은 장애자 중 연령과 성별 그리고 가정이 있는 경우와 없는 경우 간에 유의한 차이가 없었으나 지능지수와는 유의한 역상관을 나타내었다. 아연은 연령에 따라서는 유의한 상관성을 보였으나 지능지수와는 유의한 상관성이 없었다. 정신지체아에 수반된 장애로 언어장애, 정서장애, 지체부자유, 이중 및 삼중장애, 감각이상, 식습관이상 등이 있으나 감각이상과 식습성을 제외하고 모두 정상군에 비하여 평균 납함량이 유의하게 높으나 정신지체아이면서 수반된 장애가 없는 군과는 유의한 차이가 없었다. 정신지체아에 수반된 질병은 몽고증, 자폐증, 뇌성마비, 간질 및 소뇌증이 있었으나 몽고증의 평균 납 함량에 비하여 뇌성마비와 수반된 질병이 없는 경우와는 유의하게 높은 차이가 있었다. 그들의 병력을 외적 요인과 내적 요인으로 구별해 보았으나 상호 유의한 차이는 없었다. 이상의 결과로 보아 정신지체와 납 사이에는 어느 정도 관계가 있는 것으로 추측되므로 이때의 접촉 기회에 대한 고찰은 모자보건학 상 중요한 과제가 된다고 생각되며 추후 계속 연구해 보아야 할 것 같다.

• 한국산업보건학회지
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• 제3권2호
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• pp.141-151
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• 1993

Blood samples obtained from 200 adults who had visited the "S" general hospital were analyzed to compare the zinc protoporphyrin (ZPP) levels quantified by high performance liquid chromatograph (HPLC) and by hematofluorometer (HF) to investigate the methodological difference if any and the relationship between the levels of blood lead and ZPP among no-lead exposed adults. Also investigated were the distribution of ZPP and protoporphyrin IX (PPIX) concentrations, the establishment of normal levels of blood ZPP and blood lead, and the contribution of age and sex factors to these values. These subjects had no previous occupational exposure to lead. The results obtained were as follows : 1. The mean values of blood lead for male and female subjects were $9.46{\pm}2.44{\mu}g/dl$ and $8.09{\pm}2.17{\mu}g/dl$, respectively. The difference observed in the mean concentrations between male and female subjects was statistically very significant. 2. The mean values of blood ZPP by HPLC for male and female subjects were $15.94{\pm}4.55{\mu}g/dl$ and $22.26{\pm}6.61{\mu}g/dl$, respectively. The difference observed in the mean concentrations between male and female subjects was statistically not significant. The mean values of blood PPIX by HPLC for male and female subjects were $2.51{\pm}1.78{\mu}g/dl$ and $2.81{\pm}1.56{\mu}g/dl$, respectively. The difference observed in the mean concentrations between male and female subjects was statistically not significant. 3. The mean values of blood ZPP by HF for male and female subjects were $28.44{\pm}7.11{\mu}g/dl$ and $37.77{\pm}8.04{\mu}g/dl$, respectively. The difference observed in the mean concentrations between male and female subjects was statistically very significant. 4. No statistically significant correlation was found between the levels of blood ZPP and blood lead. 5. The ratio of ZPP and protoporphyrin IX (PPIX) concentration to erythrocyte protoporphyrin (EP, EP=ZPP+PPIX) concentration was 87.4% and 12.6%, respectively. 6. A statistically very significant correlation was found between the ZPP concentrations determined by HPLC and the values by HF (r=0.7565). The ZPP concentraitons quantified by HF were 1.75 times as high as the values obtained by HPLC. 7. The blood ZPP concentrations quantified by HPLC, HF, and spectrofluorometer (SF) from the blood samples obtained from 14 lead-exposed workers and from 16 no-lead exposed adults showed wide variations. The ZPP concentrations by HF were the highest followed by the levels obtained by SF and by HPLC. In the exposed group, no statistically significant difference was found among three methods of quantifying blood ZPP levels. In the no-lead exposed group, however, statistically significant difference was observed among these methods. The ZPP concentrations by HF were about twice as high as those of by HPLC or by SF. Among three methods of quantifying blood ZPP (HPLC, SF and HF), the results revealed significant difference. Therefore it is suggested that objective methods of quantifying blood ZPP and a system of correcting different ZPP levels be developed by the ministry of Labor.

• 한국진공학회지
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• 제18권4호
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• pp.296-301
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• 2009

ZnO에 대한 박막증착 연구를 위하여 유도결합 플라즈마 원자층박막증착(inductively coupled plasma assisted atomic layer deposition: ICP-ALD) 장치를 제작하고, 장치에 대한 기본 공정조건을 설정하기 위하여 플라즈마를 유도하지 않은 상태에서 p-type Si(100) 기판 위에 ZnO 박막을 증착하는 다양한 실험을 수행하였다. Zn 전구체(precursor)로는 Diethyl zinc [$Zn(C_2H_5)_2$, DEZn]를, 반응가스(reaction gas)로는 $H_2O$를, 캐리어(carrier) 및 퍼지가스(purge gas)로는 Ar을 사용하였다. 기판온도 $150^{\circ}C$에서 DEZn, $H_2O$, Ar의 공급시간을 변화시켜가면서 자기제한적 표면반응(self-limiting surface reaction)에 의한 박막성장조건을 성공적으로 유도하였다. 기판온도를 변화시켜가면서($90{\sim}210^{\circ}C$) 증착실험을 반복하여, 본 장치에 대한 ALD 공정온도(thermal ALD process window)를 확립하고 성장된 ZnO박막에 대한 증착특성, 결정성, 불순물 및 내부조성비등을 조사하였다. ALD 공정온도는 기판온도 $110{\sim}190^{\circ}C$로써 이 구간에서의 박막 평균증착률은 0.29 nm/cycle로 일정하게 나타났다. 기판온도가 높아질수록 결정성이 향상되어 ZnO(002) 피크가 우세하였다. 모든 ALD 공정온도에서 Zn와 O로만 구성된 고순도의 ZnO 박막을 실현하였는데, 온도가 높아질수록 Zn와 O의 비가 1에 근접하며 안정된 hexagonal wurtzite ZnO 구조의 박막이 성장되었다.

• 한국융합학회논문지
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• 제11권10호
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• pp.147-154
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• 2020

본 연구에서는 복합 부가필터(Composite added filtration) 4가지 종류(알루미늄, 니켈, 구리, 아연)를 두께별로 조합하여 X-선 감약에 따른 선량감소와 최적의 영상을 평가하였다. 선량과 화질을 평가는 RQR9 표준 선질을 설정한 X선 발생장치, 면적선량계 그리고 ICY 프로그램이 사용되었다. 화질평가 항목(PSNR, RMSE, SSIM)에서는 PSNR값이 30 dB 이상이 되는 영상들만을 분석하였다. 그 결과 선량평가에서 가장 우수한 조합은 3 mmAl + 0.6 mmNi(0.16µGy㎡)이었고, 화질평가에서 가장 우수한 필터는 0.9 mmAl (PSNR 34.24dB, RMSE 79.52, SSIM 0.24)이었다. 본 연구에서는 선량적 측면과 화질적 측면이 언급되었기에 향후 환자의 피폭선량과 최적의 영상에 대한 더 많은 연구가 필요할 것으로 사료된다.