AA1100의 부식에 미치는 Na2S, NaCl, H2O2 농도의 영향

장희진,이주희 한국부식방식학회 2019 Corrosion Science and Technology Vol.18 No.6

The objective of this study was to investigate the corrosion behavior of aluminum (AA1100) in a mixed solution of 0 ~ 0.1 g/L Na2S + 0.3 ~ 3 g/L NaCl + 0 ~ 10 mL/L H2O2. Potentiodynamic polarization tests were performed. Effects of solution compositions on corrosion potential, corrosion rate, and pitting potential of aluminum were statistically analyzed with a regression model. Results suggested that localized corrosion susceptibility of aluminum was increased in the solution with increasing concentration of NaCl because the pitting potential was lowered linearly with increasing NaCl concentration. On the contrary, H2O2 mitigated the galvanic corrosion of aluminum by increasing the corrosion potential. It also mitigated localized corrosion by increasing the pitting potential of aluminum. Na2S did not exert a noticeable effect on the corrosion of aluminum. These effects of different chemical species at various concentrations were independent of each other. Synergy or offset effect was not observed.

Effects of Mo on the Passive Films Formed on Ni-(15, 30)Cr-5Mo Alloys in pH 8.5 Buffer Solution

장희진,권혁상 한국전기화학회 2009 한국전기화학회지 Vol.12 No.3

The composition and semiconducting properties of the passive films formed on Ni- (15, 30)Cr-5Mo alloys in pH 8.5 buffer solution were examined. The depth concentration profile of passive films formed on Ni-(15, 30)Cr-5Mo in pH 8.5 buffer solution showed that Mo enhances the enrichment of Cr. The Mott-Schottky plot for the passive film on Ni-(15, 30)Cr- 5Mo closely resembled that for the film on Cr, whereas those for the less Cr-enriched film on Mo-free alloys showed similar behavior to that for the film on Ni. The acceptor density was reduced by increasing Cr content in Ni-(15, 30)Cr-(0, 5)Mo alloys, but addition of Mo considerably increased the acceptor density.

녹조류와 적니의 이산화탄소환경 공동열분해를 통한 탄소-철 복합체 생성 및과황산염 활성화를 통한 수중 염료 제거

장희진,권기훈,윤광석,송호철 한국지하수토양환경학회 2022 지하수토양환경 Vol.27 No.1

The common algae and industrial waste, chlorella and red mud, were co-pyrolyzed in carbon dioxide condition to fabricateiron-biochar composite. In order to investigate the direct effect of chlorella and red mud in the syngas generation and theproperty of biochar, experiments were performed using mixture samples of chlorella and red mud. The evolution offlammable gasses (H2, CH4, CO) was monitored during pyrolysis. The produced biochar composite was employed as acatalyst for persulfate activation for methylene blue removal. BET analysis indicated that the iron-biochar compositemainly possessed meso- and macropores. The XRD analysis revealed that hematite (Fe2O3) contained in red mud wastransformed to Fe3O4 during co-pyrolysis. The composite effectively activated persulfate and removed methylene blue. Among the composite samples, the composite fabricated from the mixture composed of 1:2 chlorella:red mud showed thebest performance in syngas generation and methylene blue removal.

Determination of the Diffusivity of Cation Vacancy in a Passive Film of Ni Using Mott-Schottky Analysis and in-situ Ellipsometry

장희진,Kkoch-Nim Oh,안세진,권혁상 대한금속·재료학회 2014 METALS AND MATERIALS International Vol.20 No.2

The diffusivity of cation vacancies in a passive film formed on Ni in a pH 8.5 buffer solution was estimatedbased on the Point Defect Model with high field migration equations. The parameters required tocalculate the diffusivity of the cation vacancies include the flux of cation vacancies, the acceptor density,and the thickness of the passive film as functions of the film formation potential and they were measuredfrom potentiostatic polarization, a Mott-Schottky analysis, and in-situ ellipsometry, respectively. The passivecurrent density, proportional to the flux of the point defects, linearly increased with an increase of the passivationpotential, while the acceptor density was reduced with the potential. The thickness of the passivefilm appeared to increase very rapidly and the growth became stable in thousands of seconds, and increasedlinearly with an increase of the potential. The dependence of all parameters investigated in this study onthe passivation potential corresponded well to the theory. The diffusivity of the cation vacancies in thepassive film of Ni was determined to be 2.7×10−18 cm2s−1.

자기조절 학습기능 훈련이 초등학교 4학년 학생의 학습기능 습득과 학업성취에 미치는 영향

장희진,양용칠 한국교육학회 2002 敎育學硏究 Vol.40 No.6

이 연구는 자기조절 학습기능 훈련이 초등학교 4학년 학생들의 자기조절 학습기능 습득에 영향을 미치는지 살펴보고, 영향을 준다면 그것이 학업성취에도 연결되는지 밝히고자 하였다. 이 연구를 수행하기 위하여 실험집단 40명에게 6주동안 총 24차시에 결쳐 자기조절 학습기능 훈련을 실시하였다. 자기조절 학습기능 훈련이 끝난 후에 자기조절 학습기능검사와 학업성취도의 결과를 통제집단 41명의 결과와 비교하였다. 이들 검사에서 나온 결과는, 첫째 자기조절 학습기능 훈련을 받은 집단이 이 훈련을 받지 않은 집단보다 자기조절 학습기능의 습득점수에서 유의미하게 높았고, 둘째 자기조절 학습기능 훈련으로 이 기능이 높아진 집단이 그렇지 않은 집단보다 수학 과목의 학업성취에도 유의하게 영향을 주는 것으로 나타났다. 이러한 결과는 초등학교 4학년 수준에서도 적절한 학습환경이 제공되면 자기조절 학습기능의 습득이 가능함을 시사한다. It is also known that the elementary school students' self-regulated learning skills could be acquired through the training of the skills. The purpose of this study was to explore an effect of self-regulated learning skills training at the 4th graders of elementary school, and then to investigate if acquired skills have an effect on their academic achievement. 81 elementary school students in Andong city were participated in this study. They were respectively assigned to experimental group and control group. The experimental group was trained for six weeks with the 24th sessions through the self-regulated learning skills training program. The used experimental design was the nonequivalent control group design. Before administrating the experimental procedure, both groups took the pretest for measuring their self-regulated learning skills and math achievements. After the experimental sessions, they also took the posttests to measure both of them. Data collected from the experiment were analyzed to compare effects of self-regulated learning skills training between two groups. A t-test was used, and the degree of significance was set at .05. Results drawn from this seudy showed that first, the experimental group trained through the self-regulated learning skills program has got higher scores on the self-regulated skills questionnaire than the control group, and that second, the former which got higher scores on the self-regulated dkills also gained more scores on math test than the latter. In light of these results, it gained more scores on math test than the latter. In light of these results, it stggests that the 4th graders' self-regulated learning dkills tn the elementary school could be acquired through self-regulated learning skills programs.

Photoelectrochemical Study of the Growth of the Passive Film Formed on Fe-20Cr-15Ni in a pH 8.5 Buffer Solution

장희진,박찬진,권혁상 대한금속·재료학회 2010 METALS AND MATERIALS International Vol.16 No.2

The structural change of the passive film on Fe-20Cr-15Ni at its growth stage was examined in-situ using a photoelectrochemical technique. The photocurrent spectra showed that the passive film on Fe-20Cr-15Ni for 0.5 h ~ 25 h in a pH 8.5 buffer solution was composed of (Cr, Ni)-substituted γ-Fe2O3 mixed with NiO. Photocurrent spectral analysis suggested that a crystalline film of (Cr, Ni)-substituted γ-Fe2O3 formed before 30 min, with its thickness exceeded that of the space charge layer after 1 h of passivation. NiO particles appeared to have gradually precipitated from (Cr, Ni)-substituted γ-Fe2O3 film in the early stage of passivation of 1 h.

Photoelectrochemical Analysis of the Effects of pH and Sulfate Ions on the Structure and the Composition of the Passive Film Formed on Fe-20Cr-15Ni Alloy

장희진,박찬진,권혁상 대한금속·재료학회 2009 METALS AND MATERIALS International Vol.15 No.1

The effects of pH and sulfate ions on the structure and compositions of the passive film formed on Fe-20Cr- 15Ni were examined using a photoelectrochemical technique and Mott-Schottky analysis. The photocurrent spectra for the passive film formed on Fe-20Cr-15Ni in the buffer solutions are composed of two spectral components, one of which is generated from Cr-substituted γ-Fe2O3 and the other of which is generated from NiO. However, the passive film formed in sulfate solutions showed only the photocurrent spectrum of Cr-substituted γ-Fe2O3, suggesting that the formation of NiO in the passive film is suppressed because of a severe selective dissolution of Ni in the presence of sulfate ions. Mott-Schottky plots confirmed that the base structure of the passive film on Fe-20Cr-15Ni is n-type (Cr, Ni)-substituted γ-Fe2O3 regardless of solution pH and sulfate ions. The photocurrent intensity, flat band potential, and donor density for the passive film varied depending on the solution pH or the presence of sulfate ions in the solution, due primarily to the Cr enrichment in the film caused by the preferential dissolution of Fe and Ni that is more appreciable in highly acidic solutions containing sulfate ions. The effects of pH and sulfate ions on the structure and compositions of the passive film formed on Fe-20Cr- 15Ni were examined using a photoelectrochemical technique and Mott-Schottky analysis. The photocurrent spectra for the passive film formed on Fe-20Cr-15Ni in the buffer solutions are composed of two spectral components, one of which is generated from Cr-substituted γ-Fe2O3 and the other of which is generated from NiO. However, the passive film formed in sulfate solutions showed only the photocurrent spectrum of Cr-substituted γ-Fe2O3, suggesting that the formation of NiO in the passive film is suppressed because of a severe selective dissolution of Ni in the presence of sulfate ions. Mott-Schottky plots confirmed that the base structure of the passive film on Fe-20Cr-15Ni is n-type (Cr, Ni)-substituted γ-Fe2O3 regardless of solution pH and sulfate ions. The photocurrent intensity, flat band potential, and donor density for the passive film varied depending on the solution pH or the presence of sulfate ions in the solution, due primarily to the Cr enrichment in the film caused by the preferential dissolution of Fe and Ni that is more appreciable in highly acidic solutions containing sulfate ions.

식품의 유통기한 예측기술

장희진 한국기술사회 1993 技術士 Vol.26 No.4

Poster Session : 니켈 ( Ni ) 이 Fe-20Cr-xNi 합금의 부동태 피막의 광전기화학적 특성에 미치는 영향

장희진,권혁상 한국부식방식학회(구 한국부식학회) 2002 춘계 학술발표회 초록집 Vol.- No.-

미디어 정보가 소비자에 미치는 영향에 관한 연구 동향 분석

장희진,이다은,이창현,류지혜,김영 한국식생활문화학회 2018 한국식생활문화학회학술대회논문집 Vol.2018 No.06