Realization of a Low-Threshold-Voltage Field Emitter by Using High-Quality ZnO Nano-Tetrapods

Mina Jung,Dongchul Oh,고항주,Hyunchul Ko,Jiho Chang,Sunyeo Ha,Takafumi Yao,Wookhyun Lee 한국물리학회 2006 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.48 No.6

High-performance ZnO tetrapods-type field emitters with low turn-on voltage are realized. Systematic investigations of the formation conditions are performed. Tetrapod-shaped ZnO nanostructures are formed on Si substrates by using a vapor phase transportation method. The effects of two important growth parameters, the growth temperature and the VI/II ratio, are investigated. The growth temperature is controlled in the range from 600 C to 900 C while the VI/II ratio is adjusted by changing the flux of the carrier gas. ZnO tetrapods, formed at 800 C under a carrier gas flux of 0.5 cc/mm2min, show a uniform shape with 100-nm-thick and 1 1.5-μm- long legs. Also, the growth condition confirms a stoichiometric chemical composition (O/Zn 1) without any second phases. The excellent luminescence properties, a strong excitonic UV emission at 3.25 eV without deep-level emission, indicate that tetrapod structures with high crystallinity can be formed under optimized growth conditions.쵇

Ultraviolet Properties of Dwarf Galaxies in the Ursa Major Cluster

Mina Pak,Soo-Chang Rey,Suk Kim,Youngdae Lee,Wonhyeong Yi,Eon-Chang Sung,Jaemann Kyung 한국천문학회 2010 天文學會報 Vol.35 No.2

Predictive value of sperm motility before and after preparation regarding pregnancy outcome of intrauterine insemination cycle: a retrospective cohort study

( Mina Jeong ),( Hoon Kim ),( Seung Yup Ku ),( Chang Suk Suh ),( Seok Hyun Kim ),( Young Min Choi ) 대한산부인과학회 2018 대한산부인과학회 학술대회 Vol.104 No.-

Objective: To investigate the value of sperm motility before and after preparation for predicting pregnancy outcome in couples with intrauterine insemination (IUI) cycles. Methods: This retrospective cohort study included 187 infertile couples who underwent 300 IUI cycles with ovarian stimulation from January 2012 to December 2017 at a single tertiary center. Patients with severe endometriosis or severe male factor infertility were excluded from analysis. The main outcomes measured were clinical pregnancy and live birth. Sperm characteristics, especially motility before and after sperm preparation on insemination day, were assessed and compared according to the pregnancy outcome. Results: Overall clinical pregnancy rate was 15.3% and live birth rate was 10.3%. Patient and cycle characteristics were not significantly different according to the pregnancy outcome. Initial or inseminated total motile sperm count (TMC), and post-preparation sperm motility showed no significant difference according to the pregnancy outcome. Sperm motility (%) before preparation was significantly higher in patients with live birth than in those without live birth (71.60 ± 12.58 vs. 67.27 ± 11.68, p<.05). Probably in the same vein, change of the sperm motility through preparation process was significantly less in patients with live birth than in those without live birth. These relationships were still significant after adjusting for confounding variables such as female age or level of Anti-Mullerian hormone (AMH). According to the logistic regression analysis, predicted odds of live birth was the greatest when pre-preparation sperm motility was at least 75% (aOR=2.686, 95% CI: 1.222-5.902). Conclusion: Motility of the inseminated sperm dose not reliably predict the pregnancy outcome in intrauterine insemination cycles. Sperm motility before preparation, especially when higher than 75%, predicts the probability of live birth fairly well regardless of the degree of improvement in motility before and after sperm preparation.

The Relationship Between Language Use and Thematic Play Themes over the Course of Child Psychotherapy

Mina Cho,Young Seok Seo,Chang H. Lee 한국상담학회 2012 Journal of Asia Pacific counseling Vol.2 No.2

The purpose of this exploratory study is to examine child`s verbal expressions through language use and nonverbal expressions through play themes in the course of therapy sessions. A single case was used for providing in-depth descriptions of how the client`s language style and play themes actually changed during therapy and contributed to effective therapeutic outcomes. Results from this study revealed that there were changes in language use patterns and thematic plays over the course of 30 therapy sessions. Significant patterns of some variables in the Korean Linguistic Inquiry and Word Count (KLIWC) program, especially psychological dimensions could be found. These variables were: emotion/affect process, cognitive process, negative emotions, sensation/perceptional process, physical states/function, and bodily symptoms. Also, several moderate correlations between play themes and language use emerged. Implications for counseling practice and future research are discussed.

Ten-Year Changes in the Hepatitis B Prevalence in the Birth Cohorts in Korea : Results From Nationally Representative Cross-Sectional Surveys

Park, Boyoung,Jung, Kyu-Won,Oh, Chang-Mo,Choi, Kui Son,Suh, Mina,Jun, Jae Kwan Williams & Wilkins Co 2015 Medicine Vol.94 No.41

<P><B>Abstract</B></P><P>To compare the prevalence of hepatitis B virus (HBV) infection over a 10-year period in terms of population-level trends, we established hypothetical birth cohorts that represented each 10-year interval age group.</P><P>We used data from the Korean National Health and Nutrition Examination Surveys conducted between 1998 to 2001 and 2008 to 2011. Trends in the HBV infection were calculated using data from individuals aged 20 to 59 years in 1998 to 2001 and those aged 30 to 69 years in 2008 to 2011.</P><P>In 2008 to 2011, the prevalence of HBV infection, as measured using serum HBV surface antigen (HBsAg) seroprevalence, among participants aged 30 to 69 years was 4.2% (95% CI = 3.7–4.7%), which represents a 1.3% absolute change and 20% change in prevalence ratio, which was significant compared with the prevalence among those aged 20 to 59 years in 1998 to 2001 (5.5%, 95% CI = 4.7–6.3%). The prevalence of HBV infection decreased most in the lowest income group, with marginal significance in males (<I>P</I> = 0.06) and significance in females (<I>P</I> = 0.03). In terms of education, females with at least a high school education showed a significant decrease (<I>P</I> = 0.03).</P><P>Using a birth cohort approach, the prognosis for HBV infection in terms of death or hospitalization, or resolution upon antiviral treatment of their HBV infections, identified by a decrease in the HBsAg seroprevalence was worse in the lower income group and in females with higher education. We postulate that these socioeconomic inequalities were caused by alcohol consumption, disparities in liver cancer surveillance, and access to antiviral treatment because of cost and reimbursement guidelines.</P>

Characteristics of Humidifier Use in Korean Pregnant Women

Moon-Hee Chang,Hyesook Park,Mina Ha,Yangho Kim,Eun-Hee Ha 환경독성보건학회 2012 환경독성보건학회지 Vol.27 No.-

Objectives: The current use of humidifier detergent and its harmful impact on humans has arisen as a societal environmental health issue. Therefore, in this study we aimed to explore the relationship between demo-socio characteristics and humidifier use, as well as the monthly usage changes in pregnant women; thus, we report the actual status of humidifier usage of Korea’s pregnant population. Methods: From a birth cohort of a Mothers and Children’s Environmental Health (MOCEH) study, 1,144 pregnant women who responded through questionnaires including demo-socio characteristics, obstetric status and household environment including whether they use humidifier and frequency of use were included in this study. Statistical analyses were performed to explore the relationship between maternal characteristics and the relevance of the use of humidifiers was performed using a chi-square test, a t-test and univariate logistic regression analysis. The monthly usage rate was demonstrated in the graph. Results: The humidifier usage rate in pregnant women was 28.2%. The average frequency of humidifier usage was 4.6 days per week, 7.3 hours per day. The usage rate was higher in the multipara group and the above the age of 34 age group than in the primipara and below the age of 34 groups. Seoul showed a higher usage rate than Cheonan and Ulsan and as the education level and income increased, the usage rate of humidifiers among pregnant women also increased. In the monthly trend of usage rate, the winter season showed the highest usage rate of over 45% and the lowest in late summer and beginning of fall with a value of 12% or less. Conclusions: During pregnancy, the mother’s body is especially vulnerable to hazardous environmental exposure that not only affects the pregnant woman but also the fetus. Further research is still needed to elucidate the route and effect of environmental risk factors. Therefore, based on precautionary and preventive principles, special interest and caution in harmful environments are strongly needed not only at an individual level but also at a national level.

Dietary wheat germ oil and age influences fatty acid compositions in adult oriental fruit flies

Chiou Ling Chang,Eric Haas,Athena M.M. Mina,Josephione A. Bustamante,Danielle Schneider,Emma Mitchel,Morgan Freilich,David Stanley 한국응용곤충학회 2013 Journal of Asia-Pacific Entomology Vol.16 No.3

The oriental fruit fly, Bactrocera dorsalis (Hendel) (Diptera: Tephritidae) is a serious pest of fruit crops in Asia,several Pacific Islands and sometimes the western United States, particularly California. Sterile insect technique programs have been developed for management of several tephritid fruit fly pests. These programs are based on continuous production of adult fruit flies. The high expense of mass-rearing oriental fruit flies drives research to improve the cost effectiveness of rearing programs. One recent improvement for mass rearing oriental fruit flies involves adding wheat germ oil (WGO) to the larval culture medium, which improved several parameters of biological performance. The performance enhancing influence of WGO is due to the presence of polyunsaturated fatty acids (PUFAs), some of which are nutritionally essential for many insect species. We considered the issue of whether WGO supplementation of the larval culture medium influences the fatty acid make up of adult tissues. We report that WGO supplementation led to substantial increases in adult tissue C18 PUFAs. Unlike the outcomes of unrelated nutritional studies on moths, the PUFA components of WGO did not improve adult fruit fly performance. Taken with recent publications reporting that WGO in larval diets influences gene expression, we conclude that dietary WGO improves biological performance of adults through changes in tissue C18 PUFAs and gene expression.

Comparison of the estimated breeding value and accuracy by imputation reference Beadchip platform and scaling factor of the genomic relationship matrix in Hanwoo cattle

Soo Hyun Lee,Chang Gwon Dang,Mina Park,Seung Soo Lee,Young Chang Lee,Jae Gu Lee,Hyuk Kee Chang,Ho Baek Yoon,Chung-il Cho,Sang Hong Lee,Tae Jeong Choi 충남대학교 농업과학연구소 2022 Korean Journal of Agricultural Science Vol.49 No.3

Novel nanoporous N-doped carbon-supported ultrasmall Pd nanoparticles: Efficient catalysts for hydrogen storage and release

Koh, Katherine,Jeon, Mina,Chevrier, Daniel M.,Zhang, Peng,Yoon, Chang Won,Asefa, Tewodros Elsevier 2017 Applied Catalysis B Vol.203 No.-

<P><B>Abstract</B></P> <P>The reversible reactions involving formate and bicarbonate can be used to store and release hydrogen (H<SUB>2</SUB>), allowing H<SUB>2</SUB> to serve as an effective energy carrier in energy systems such as fuel cells. However, to feasibly utilize these reactions for renewable energy applications, efficient catalysts that can reversibly promote both reactions are required. Herein we report the synthesis of novel polyaniline (PANI)-derived mesoporous carbon-supported Pd nanoparticles, or materials that can efficiently catalyze these reversible reactions. The synthesis involves pyrolysis of PANI/colloidal silica composite materials at temperatures above 500°C, followed by removal of the colloidal silica from the carbonized products with an alkaline solution and finally deposition of Pd nanoparticles within the mesoporous carbon products. The resulting nanomaterials efficiently catalyze the reversible reactions, <I>i.e</I>., the dehydrogenation of formate (HCO<SUB>2</SUB>‾+H<SUB>2</SUB>O→H<SUB>2</SUB> +HCO<SUB>3</SUB>‾) and the hydrogenation of bicarbonate (H<SUB>2</SUB> +HCO<SUB>3</SUB>‾→H<SUB>2</SUB>O+HCO<SUB>2</SUB>‾). The porosity and the catalytic property of the materials can be tailored, or improved, by changing the synthetic conditions (in particular, the pyrolysis temperature and the amount of colloidal silica used for making the materials). The study further reveals that having an optimum density of N dopant species in the catalysts makes Pd to exhibit high catalytic activity toward both reactions. Among the different materials studied here, the one synthesized at 800°C with relatively high amount of colloidal silica template gives the best catalytic activity, with a turnover frequency (TOF) of 2,562h<SUP>−1</SUP> for the dehydrogenation reaction and a turnover number (TON) of 1,625 for the hydrogenation reaction.</P> <P><B>Highlights</B></P> <P> <UL> <LI> N-doped nanoporous carbon-supported Pd nanoparticles are synthesized. </LI> <LI> The materials efficiently catalyze the formate-bicarbonate reversible reactions. </LI> <LI> The materials allow the storage and release of hydrogen (H<SUB>2</SUB>) on demand. </LI> <LI> The catalytic property of the materials is improved by changing synthetic conditions. </LI> <LI> Catalytic activity of the materials depends on the N dopant species and surface area. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>

Efficient catalysts for hydrogen production from ammonia

Mina Jeon(전미나),Nguyen Thi Bich Hien,Hyo Young Kim(김효영),Jin Hee Lee(이진희),Muhammad Ridwan,Rizcky Tamarany,Chang Won Yoon(윤창원) 한국신재생에너지학회 2015 한국신재생에너지학회 학술대회논문집 Vol.2015 No.6