• Nutritional Sciences
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• v.9 no.4
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• pp.310-316
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• 2006

The objective of this study was to examine the effect of acculturation stage on dietary intake of Korean American women (0=124) living in California and to compare the dietary intake with that of Korean women (0=191) in Seoul, Korea. The dietary intake of the subjects was collected by 24-hour recall method at cross-sectional surveys. Ouster analysis performed on immigration variables (e.g., length of residency, age at immigration, etc.) classified Korean American women into less (0=73) or more (n=51) acculturated group. Acculturation stage did not have a significant effect on macro nutrient intake. However, vitamin C intake was higher in the more acculturated group, while intakes of folate, calcium, iron, and zinc were higher in the less acculturated group. In comparison of three groups (the more and the less acculturated Korean American, and the Korean group), the more acculturated the women were, the less frequently they consumed rice and kimchi (p<0.05). Korean American women ate bread/noodle, meat/meat products, fruit juice, and soda more often and consumed vegetables less frequently, compared with Korean women (p<0.05). For breakfast, Western dishes were preferred in both more and less acculturated groups. Korean dishes were favored for dinner by both groups, even though the less acculturated group ate more Korean dishes than did the more acculturated group. The acculturation measured by immigration variables influenced nutrient intakes, food consumptions, and types of dishes eaten in Korean Americans. Cultural and health implications of dietary acculturation need to be studied in the future.

• Journal of Korean Elementary Science Education
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• v.24 no.3
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• pp.249-258
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• 2005

The purpose of this study was to identify the type of thinking and generating processes of causal questions which were generated in preservice elementary teachers' observing activities. To find the generating processes of causal questions, 4 observing tasks, the task of grapes in soda, the candlelight, the celery, and the rock tasks, were administered to 7 preservice elementary teachers majoring in science education. The results of this study were as follows: The types of thinking in generating explicans exploration questions were classified as 8 types and explicans verification questions were classified as 9 types. The generating processes of explicans exploration questions were classified as 6 steps and explicans verification questions were classified as 5 steps. The results of this study may be used as a teaching strategy for guiding the direction and the method of scientific questions and developing the teaching-teaming programs that help student to generate scientifc questions.

• Proceedings of the Korean Vacuum Society Conference
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• 2010.08a
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• pp.298-299
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• 2010

Cu(In, Ga)Se2 (CIGS) 박막 태양전지는 Soda lime glass/Mo/CIGS/CdS/ZnO/ITO/Al 의 구조를 가지고 있다. CIGS 화합물은 direct bandgap 구조를 하고 있으며, 광흡수율이 다른 어떤 물질들 보다 뛰어나 박막으로도 충분히 태양광을 흡수할 수 있다. 또한 Ga의 도핑 농도에 따른 밴드갭 조절도 가능하다. 이러한 성질들로 인해 현재 박막태양전지로서 20.1%의 최고효율을 가지고 있다.[1] CIGS 박막 태양전지에서 p-CIGS layer와 스퍼터링으로 증착되는 n-ZnO layer사이의 buffer 층으로 chemical bath deposition (CBD)-CdS 박막을 주로 사용한다. CBD-CdS 박막은 n-ZnO 스퍼터로 증착 시킬 때, CIGS 층의 손상을 최소화하고, 이 두 층 사이에서의 격자상수와 밴드갭의 차이를 줄여주어 CIGS 박막태양전지의 효율을 증가 시키는 역할을 한다. 하지만, Cd (카드뮴)의 심각한 독성과 낮은 밴드갭(2.4eV)으로 인해 CIGS 층에서의 광흡수율을 줄여, CdS를 대체할 새로운 buffer 층의 필요성이 대두되었다.[2] 그 대안으로 ZnS, Zn(O, S, OH), (Zn, Mg)O, In2S3 같은 물질이 연구되고 있다. 현재 CBD-ZnS를 buffer 층으로 사용한 CIGS 박막태양전지의 효율은 최고 18.6%로 CBD-CdS의 최고효율보다는 약 1.5% 낮지만, ZnS가 높은 밴드갭(3.7~3.8eV)과 Cd-free 물질이라는 점에서 CdS를 대체할 물질로 각광받고 있다. 본 연구에서는 기존의 CdS 박막을 제조하는 방법과 같은 방법인 CBD를 이용하여 ZnS 박막을 제조하였다. ZnS 박막을 제조하기 위해서는 Zinc sulfate, Thiourea, 암모니아가 사용된다. 암모니아의 mol 농도에 따른 CBD-ZnS/CIGS 박막태양전지의 효율 변화를 관찰하기 위해 암모니아의 mol 농도는 1 mol, 2 mol, 3 mol, 4 mol, 5 mol, 6 mol, 그 이상의 과량을 사용하여 실험하였다. 실험 결과, 암모니아농도 5 mol에서 효율 13.82%를 확인할 수 있었다. 최고효율을 보인 조건인 암모니아 농도가 5 mol 일 때, Voc는 0.602V, Jsc는 33.109mA/cm2, FF는 69.4%를 나타내었다.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.31 no.5
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• pp.212-217
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• 2021

The applicability of the white LED from the blue LED of the coating film as a binder for surface and curved coatings were confirmed. The particle size of YAG is D₅₀: 9~10 ㎛, and the crystal structure is garnet (Y₃Al₅O₁₂), cubic. The coating film had no cracks, at the same time, the silica sol was uniformly coated with YAG phosphor, and the YAG content and thickness in the coating film showed a tendency to increase up to 40 ㎛ in proportion to the increase in the amount added. Furthermore, as the YAG content increased, the PL emission intensity increased and the color coordinate shift toward the end of the chromatic locus curve was confirmed.

• Research in Community and Public Health Nursing
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• v.29 no.4
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• pp.440-449
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• 2018

Purpose: The purpose of this study is to identify the dietary habits of Korean adolescents and to investigate their effects on sleep duration. Methods: This study is a secondary analysis drawn from the 2016 Korean Youth Risk Behavior Web-Based Survey (N=65,528). ANCOVA was used to determine the relationship between dietary habits and sleep duration. Ordinal logistic regression was used to find out the effects of dietary habits on sleep duration adjusted for general characteristics and behavioral characteristics. Results: The group that consumed no breakfast (AOR=0.89, p<.001) had less sufficient sleep duration than those who had breakfast 7 times per week. The group that had drunk no milk (AOR=0.88, p<.001) had less sufficient sleep duration than those who enjoyed it 5 times per week. On the contrary, the groups that had no soda drinks (AOR=1.18, p=.015), caffeine drinks (AOR=1.77, p<.001), and sweet drinks (AOR=1.25, p<.001) were more likely to have sufficient sleep duration than the groups that consumed those beverages 5 times per week. Conclusion: It is important to educate adolescents about healthy eating habits including drinks and optimal sufficient sleep duration through a multidisciplinary approach.

• Korean Journal of Materials Research
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• v.29 no.9
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• pp.553-558
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• 2019

$Cu_2ZnSn(S,Se)_4(CZTSSe)$ thin film solar cells areone of the most promising candidates for photovoltaic devices due to their earth-abundant composition, high absorption coefficient and appropriate band gap. The sputtering process is the main challenge to achieving high efficiency of CZTSSe solar cells for industrialization. In this study, we fabricated CZTSSe absorbers on Mo coated soda lime glass using different pressures during the annealing process. As an environmental strategy, the annealing process is performed with S and Se powder, without any toxic $H_2Se$ and/or $H_2S$ gases. Because CZTSSe thin films have a very narrow stable phase region, it is important to control the condition of the annealing process to achieve high efficiency of the solar cell. To identify the effect of process pressure during the sulfo-selenization, we experiment with varying initial pressure from 600 Torr to 800 Torr. We fabricate a CZTSSe thin film solar cell with 8.24 % efficiency, with 435 mV for open circuit voltage($V_{OC}$) and $36.98mA/cm^2$ for short circuit current density($J_{SC}$), under a highest process pressure of 800 Torr.

• Journal of Microbiology and Biotechnology
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• v.29 no.5
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• pp.765-775
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• 2019

A new ${\alpha}$-amylase-encoding gene (amySL3) of glycoside hydrolase (GH) family 13 was identified in soda lake isolate Alkalibacterium sp. SL3. The deduced AmySL3 shares high identities (82-98%) with putative ${\alpha}$-amylases from the genus Alkalibacterium, but has low identities (<53%) with functionally characterized counterparts. amySL3 was successfully expressed in Escherichia coli, and the recombinant enzyme (rAmySL3) was purified to electrophoretic homogeneity. The optimal temperature and pH of the activity of the purified rAmySL3 were determined to be $45^{\circ}C$ and pH 7.5, respectively. rAmySL3 was found to be extremely halophilic, showing maximal enzyme activity at a nearly saturated concentration of NaCl. Its thermostability was greatly enhanced in the presence of 4 M NaCl, and it was highly stable in 5 M NaCl. Moreover, the enzyme did not require calcium ions for activity, and was strongly resistant to a range of surfactants and hydrophobic organic solvents. The major hydrolysis products of rAmySL3 from soluble starch were maltobiose and maltotriose. The high ratio of acidic amino acids and highly negative electrostatic potential surface might account for the halophilic nature of AmySL3. The extremely halophilic, calcium-independent, and surfactant-resistant properties make AmySL3 a promising candidate enzyme for both basic research and industrial applications.

• Korean Journal of Materials Research
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• v.31 no.3
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• pp.150-155
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• 2021

Zinc oxide (ZnO) based transparent conducting oxides (TCO) thin films, are used in many applications such as solar cells, flat panel displays, and LEDs due to their wide bandgap nature and excellent electrical properties. In the present work, fluorine and aluminium-doped ZnO targets are prepared and thin films are deposited on soda-lime glass substrate using a RF magnetron sputtering unit. The aluminium concentration is fixed at 2 wt%, and the fluorine concentration is adjusted between 0 to 2.0 wt% with five different concentrations, namely, Al2ZnO98(AZO), F0.5AZO97.5(FAZO1), F1AZO97(FAZO2), F1.5AZO96.5(FAZO3), and F2AZO96(FAZO4). Thin films are deposited with an RF power of 40 W and working pressure of 5 m Torr at 270 ℃. The morphological analysis performed for the thin film reveals that surface roughness decreases in FAZO1 and FAZO2 samples when doped with a small amount of fluorine. Further, optical and electrical properties measured for FAZO1 sample show average optical transmissions of over 89 % in the visible region and 82.5 % in the infrared region, followed by low resistivity and sheet resistance of 3.59 × 10-4 Ωcm and 5.52 Ω/sq, respectively. In future, these thin films with excellent optoelectronic properties can be used for thin-film solar cell and other optoelectronics applications.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.34 no.1
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• pp.56-62
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• 2021

In this study, we created a DBD plasma device and a MnO2 catalyst mesh filter for evaluating ozone reduction of devices via the catalyst method. The DBD plasma device was manufactured by applying Ag paste to soda lime glass via the screen-printing method. The MnO2 catalyst mesh filter was manufactured by mixing MnO2 powder with binder with a 10% difference in concentration from 10% to 50% and then applying it using the dip-coating method. Finally, we sintered a MnO2 catalyst mesh filter in an electric furnace. We evaluated the characteristics of ozone generation according to the Ar gas flow of DBD plasma devices, the opening ratio, and ozone reduction performance of the MnO2 catalyst filters. Ozone reduction performance was approximately 20.4% at MnO2 10 wt%, 37.8% at MnO2 30 wt% and 50% at MnO2 50 wt%.

• The Korean Journal of Food And Nutrition
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• v.35 no.3
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• pp.167-177
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• 2022

The purpose of study was to examine the factors influencing fast food consumption in Korean adolescents. The analysis was conducted using cross sectional study data from the 16^th Korea Youth Risk Behavior Web-based Survey in 2020. A total 54,948 middle and high school students participated in this study. The subjects in the analysis were 28,353 males and 26,595 females, 28,961 middle school and 25,987 high school students. In total, 56.6% Korean adolescents consumed fast food once or twice weekly and 25.4% consumed fast food more than three times weekly. Logistic regression analysis revealed that fast food consumption was significantly associated with dietary behavior such as lower breakfast intake (OR: 0.930, 95%CI: 0.891~0.970, p<0.001), higher soda drinks consumption (OR: 2.563, 95%CI: 2.452~2.678, p<0.001), and higher sweet drinks consumption (OR: 1.898, 95%CI: 1.818~1.982, p<0.001). For psychological and health behavior factors, fast food consumption was also significantly associated with higher perceived stress (OR: 1.239, 95%CI: 1.163-1.321, p<0.001), higher smoking (OR: 1.300, 95%CI: 1.164~1.453, p<0.001), higher drinking (OR: 1.193, 95%CI: 1.112~1.280, p<0.001), higher depression experience, higher loneliness experience, and lower subjective health, In conclusion, fast food consumption in Korean adolescents was associated with undesirable dietary habits and psychological and health behavior, suggesting that appropriate education programs are necessary to reduce such behavior.