• Journal of Soil and Groundwater Environment
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• v.27 no.1
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• pp.25-30
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• 2022

Mackinawite (FeS), as a ubiquitous reduced iron mineral, is known as a key controller of redox reactions in anaerobic subsurface environment. The reaction of FeS with redox-sensitive toxic element such as arsenic is substantially affected by pH conditions of the given environments. In this study, the interaction of As(V) with FeS was studied under strict anaerobic conditions with various pH conditions. The pH-dependent arsenic removal tests were conducted under wide ranges of pH conditions and X-ray absorption spectroscopy (XAS) was applied to investigate the reaction mechanisms under pH 5, 7, and 9. The removal efficiency of FeS for As(V) showed the higher removal of As(V) under low pH conditions and its removal efficiency decreased with increasing pH, and no As(V) reduction was observed in 1 g/L FeS solution. However, XAS analysis indicated the reduction of As(V) to As(III) occurred during reaction between FeS and As(V). The reduced form of As(III) was particularly identified as an arsenic sulfide mineral (As₂S₃) in all pH conditions (pH 5, 7, and 9). As₂S₃ precipitation was more pronounced in pH 5 where the solubility of FeS is higher than in other pH conditions. The linear combination fitting results of XAS demonstrated that As(V) removal mechanism is concerted processes of As₂S₃ precipitation and surface complexation of both arsenic species.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2008.06a
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• pp.447-448
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• 2008

In this paper, we investigated the diffraction grating efficiency on AsSeS and Ag-doped amorphous chalcogenide Ag/AsSeS thin film for used to volume hologram. The film thickness was 0.5um and diffraction efficiency was obtained from (P:P) polarized He-Ne (632.8nm)laser beam on AsSeS and Ag/AsSeS thin films. As a results, diffraction grating was not formed at AsSeS thin film but at Ag-doped AsSeS thin film, diffraction grating was formed well compare with the former.

• Journal of the Korean Society of Food Culture
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• v.14 no.3
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• pp.189-202
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• 1999

The study was carried out from March to May in 1998 to compare the food habits and food preference of 391 men in Kyung Nam area who were between twenties and sixties. The summarized results are as follow: 1. The 30's were highest(173.8cm) and the 60's were lowest(168.3cm) in their average stature. The 30's were heaviest(68.2Kg) and the 20's were lightest(62.3Kg) in their average weight(P<0.001). Average BMI was highest in the 50's and lowest in the 20's. 2. Average food habit score of the subjects(4.08) was as low as belonging to the poor group and lowest was 20's. 3. The rate of not eating was highest in the breakfast and the subjects ate breakfast more as they were older(P<0.001). The serious problem of food habit was irregular eating time. The subjects ate in the more irregular time as they were younger. 4. 88.9% of the subjects preferred cooked rice and cereals as their main food, kimchi as their side dish and fruit as their eating between meals. 5. We found great differences in the kinds and number of drinkings subjects preferred as their ages(P<0.001). 20's preferred cider and cola. 30's, 40's and 50's preferred coffee and 60's preferred ginseng tea and citron tea. The rate of smoking was higher in 30's and 40's then in 20's and 50's. 6. 72.9% of the 20's and 16.7% of the 60's ate instant food more than 2-3 times a week. They ate Ramen most often because of its convenience. They ate out more as they were younger and preferred Korean food as their eating out menu. 7. The degree of preference in a sweet taste was highest in 20's and lowest in 40's (P<0.01) and the degree in the preference of a sour taste became lower as they were older(P<0.001). Only in the preference of a salty taste, we could find the difference of the BMI level. They showed high degree in the preference of a salty taste as the order of the over-weight group, normal group, under-weight group and fat group. They showed meaningful correlationship between the level of BMI and the degree of preference of a salty taste in 20's and 40's and between the food habit score and the level of BMI in 60's (P<0.05).

• Proceedings of the Korean Vacuum Society Conference
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• 2012.02a
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• pp.325-325
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• 2012

1차원구속 반도체인 nanowires (NWs)는 전기적, 광학적으로 일반 bulk구조와 다른 특성을 가지고 있어서 현재 많은 연구가 되고 있다. 일반적으로 NWs는 Au 등의 금속 촉매를 이용하여 성장을 하게 되는데 이때 촉매가 오염물로 작용을 해서 결함을 만들어서 bandgap내에 defect level을 형성하게 된다. 본 연구는 Si (111) 기판 위에 GaAs NWs 와 InAs NWs를 촉매를 이용하지 않고 성장 하였다. vapour-liquid-solid (VLS)방법으로 성장하는 GaAs NWs는 Ga의 droplet을 이용하게 되는데 Ga이 Si 기판위에 자연 산화막에 존재하는 핀홀(pinhole)로 이동하여 1차적으로 Ga droplet 형성하고 이후 공급되는 Ga과 As은 SiO2 보다 GaAs와 sticking coefficient 가 좋기 때문에 Ga drolept을 중심으로 빠른 선택적 성장을 하게 되면서 NWs로 성장을 하게 된다. 반면에 InAs NWs를 성장 할 시에 droplet 방법으로 성장을 하게 되면 NWs가 아닌 박막 형태로 성장을 하게 되는데 이것으로 InAs과 GaAs의 $SiO_2$와의 sticking coefficient 의 차이를 추측을 할 수 있다. InAs NWs는 GaAs NWs는 달리 native oxide를 이용하지 않고 InAs 과 Si 사이의 11.5%의 큰 lattice mismatch를 이용한다. 이종의 epitaxy 방법에는 크게 3종류 (Frank-van der Merwe mode, Stranski-Krastanov mode, Volmer-Weber mode)가 있는데 각기 다른 adatom 과 surface의 adhesive force로 나누어지게 된다. 이 중 Volmer-Weber mode epitaxy는 adatom 의 cohesive force가 surface와의 adhesive force보다 큰 경우 성장 되는 방식으로 InAs NWs 는 이 방식을 이용한다. 즉 droplet을 이용하지 않는 vapour-solid (VS) 방법으로 성장을 하였다. 이 때 In 의 migration을 억제하기 위해서 VLS mode 의 GaAs NWs 보다 As의 공급을 10배 이상 하였다. FE-SEM 분석 결과 GaAs NWs는 Ga droplet을 확인 할 수 있었고 InAs NWs는 droplet이 존재하지 않았다. GaAs와 InAs NW는 density와 length가 V/III가 높을수록 증가 하였다.

• Proceedings of the IEEK Conference
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• 2001.06b
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• pp.13-16
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• 2001

InP/InGaAs Heterojunction phototransistors(HPT's) with an optically transparent ITO emitter electrode were fabricated and characterized. At the same time, heterojuntion transistors(HBT's) having the same device layout were fabricated. By comparison with InP/InGaAs HBT's, the do characteristics of InP/InGaAs HPT's showed the similar electrical charateristics of HBT's. the model parameters of the device were extracted and compared.

• The Transactions of the Korean Institute of Electrical Engineers
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• v.41 no.1
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• pp.56-62
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• 1992

The GaAs bulk crystals are grown by the Synthesis Solute Diffusion(SSD) method and its properties are investigated. The crystal growth rate at optimum condition is 0.28 cm/day and their temperature dependence is R(T) = 2.92 x 10S04T exp(-1.548eV/kS1BTT) [cmS02T/day.K]. Etch pits density distribution along radial direction is order of 10S04TcmS0-2T and 10S03TcmS0-2T at the edge and middle of the wafers, respectively, and it increased exponentially along vertical direction of ingot. Moreover,it is uniformly distributed as order of 10S03TcmS0-2T in radial direction of In doped GaAs. The carrier concentration and mobilities are measured to 0.34-2.1 x 10S016T cmS0-3T and 2.3-3.3x10S03T cmS02T/V.sec, respectively.

• Journal of Families and Better Life
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• v.19 no.5
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• pp.189-202
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• 2001

The purpose of this study was to investigate the effects of perceived parents-adolescent communication style on adoescent’s self-efficacy. The subjexts of this study were 625 students selected at random from first and second grade of high school in Daegu. A questionnaire was used as survey method. Factor analysis, MANOVA and cluster analysis for data analysis and Scheffe test for post-hoc analysis were employed. The man findings were as follows: Firs, there were significant differences in the degree of adolescent’s self-efficacy according to perceive father-adolescent communication style. In case that adolescents perceived their father’s communication style as reasonable, the degree of self-control, self-confidence and attribution were higher than those of other cases such as non-interferential or impulsive communication style. The adolescents who perceived the father’s communication style as reasonable showed higher preference of difficult task than those who perceived it as non-interferential style. The adolescents who perceived father’s communication style as reasonable and non-interferential showed higher attribution than those who perceived it as impulsive style. Second, there were significant differences in the degree of adolescent’s self-efficacy according to perceived mother-adolescent communication style. In case that adolescents perceived their mother’s communication style as reasonable, the degree of self-control was higher than that of other cases such as non-interferential and impulsive communication style. The adolescents who perceived their mother’s communication style as reasonable showed higher self-confidence than those who perceived as impulsive style.

• Tribology and Lubricants
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• v.23 no.2
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• pp.66-72
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• 2007

[ $MoS_2$ ], is a well-known metal sulfide applied as solid lubricants and an additive to prolong the life of sintered bearings under severe conditions. However, the high price of $MoS_2$ limited its wide application. This study is aimed to investigate the possibility far application to solid lubricants for $Cu_2S$ as a substitute of $MoS_2$. Bronzes added $Cu_2S$ and $MoS_2$, are produced by powder metallurgy in this study, and then evaluated their friction and wear properties., as well as sintered bronze. The sliding wear test using pin-on-disc type machine, was conducted at several sliding speeds for three type test pieces sintered bronzes added $Cu_2S$ and $MoS_2$, and sintered bronze without lubricants. Addition of $Cu_2S$ to bronze leads to relatively good friction properties, although it is not so good as addition of $MoS_2$. However, the wear properies of sintered bronze added $Cu_2S$ are better than that of sintered bronze added $MoS_2$.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2006.11a
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• pp.112-113
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• 2006

In this paper. we investigated a characteristic of holographic grating data erasure with non-polarized beam at amorphous chalcogenide As-Ge-Se-S thin film. A sample of holographic grating data was formed with DPSS laser for setup. Then, the erasure process was performed with He-Ne laser vertically at sample. As-Ge-Se-S(single layer). Ag/As-Ge-Se-S(double layer) and As-Ge-Se-S/Ag/As-Ge-Se-S(multi-layer) are manufactured to compare their characteristic of erasure.

• Journal of the Korean Home Economics Association
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• v.34 no.4
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• pp.203-215
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• 1996

Using questionnaire data from a sample of 236 mothers who have 4-6 years old children in Seoul, this study examined a model of how child's temperament, mother's temperament and parenting stress influence mother's parenting behavior. In general, child's temperament affected mother's parenting indirectly, rather than directly, through its impact on parenting stress and, in turn, parenting behavior. Mother's temperament, in particular, mother's emotionality had a direct effect on parenting as well as parenting stress. As expected, mother's emotionality predicted more reject-authoritarian parenting and this relation was partially mediated by mother's parenting stress. Implications are discussed in terms of the relative contribution of child's temperament and mother's temperament on parental functioning and the importance of mother's psychological well-being.