Snapshot of carrier dynamics from amorphous phase to crystal phase in Sb₂Te₃ thin film

Hyejin Choi,Seonghoon Jung,Min Ahn,Won Jun Yang,Jeong Hwa Han,Hoon Jung,Kwangho Jeong,Jaehun Park,Mann-Ho Cho 한국진공학회 2016 한국진공학회 학술발표회초록집 Vol.2016 No.2

Skin corrosion and irritation test of sunscreen nanoparticles using reconstructed 3D human skin model

Choi, Jonghye,Kim, Hyejin,Choi, Jinhee,Oh, Seung Min,Park, Jeonggue,Park, Kwangsik The Korean Society of Environmental Toxicology 2014 환경독성보건학회지 Vol.29 No.-

Objectives Effects of nanoparticles including zinc oxide nanoparticles, titanium oxide nanoparticles, and their mixtures on skin corrosion and irritation were investigated by using in vitro 3D human skin models ($KeraSkin^{TM}$) and the results were compared to those of an in vivo animal test. Methods Skin models were incubated with nanoparticles for a definite time period and cell viability was measured by the 3-(4, 5-dimethylthiazol-2-yl)-2.5-diphenyltetrazolium bromide method. Skin corrosion and irritation were identified by the decreased viability based on the pre-determined threshold. Results Cell viability after exposure to nanomaterial was not decreased to the pre-determined threshold level, which was 15% after 60 minutes exposure in corrosion test and 50% after 45 minutes exposure in the irritation test. IL-$1{\alpha}$ release and histopathological findings support the results of cell viability test. In vivo test using rabbits also showed non-corrosive and non-irritant results. Conclusions The findings provide the evidence that zinc oxide nanoparticles, titanium oxide nanoparticles and their mixture are 'non corrosive' and 'non-irritant' to the human skin by a globally harmonized classification system. In vivo test using animals can be replaced by an alternative in vitro test.

Evolution of the surface state in Bi2Se2Te thin films during phase transition

Choi, Hyejin,Kim, Tae Hyeon,Chae, Jimin,Baeck, Juheyuck,Kee, Chul-Sik,Jeong, Kwang-Ho,Jeong, Hong-Sik,Kang, Chul,Cho, Mann-Ho The Royal Society of Chemistry 2015 Nanoscale Vol.7 No.36

Enhancement in thermoelectric properties of Te-embedded Bi₂Te₃ by preferential phonon scattering in heterostructure interface

Choi, Hyejin,Jeong, Kwangsik,Chae, Jimin,Park, Hanbum,Baeck, Juheyuck,Kim, Tae Hyeon,Song, Jae Yong,Park, Jaehun,Jeong, Kwang-Ho,Cho, Mann-Ho Elsevier 2018 Nano energy Vol.47 No.-

<P><B>Abstract</B></P> <P>A comprehensive understanding of the nano-structural effects that cause reduction in thermal conductivity represents important challenges for the development of thermoelectric materials with an improved figure of merit ZT. Bismuth telluride (Bi<SUB>2</SUB>Te<SUB>3</SUB>)-based thermoelectric materials exhibit very low levels of thermal conductivity. In this study, a Te crystal-embedded Bi<SUB>2</SUB>Te<SUB>3</SUB> (Te–Bi<SUB>2</SUB>Te<SUB>3</SUB>) thin film was formed by establishing a specific annealing temperature for a Te-rich Bi/Te multilayered structure. Modulations in structure and composition were observed at the boundaries between the two phases of Te and Bi<SUB>2</SUB>Te<SUB>3</SUB>. Furthermore, the samples contained regularly shaped nanometer-scale Bi<SUB>2</SUB>Te<SUB>3</SUB> single grains. Therefore, we obtained a dramatic ZT value of 2.27 (+ 0.04, − 0.08) at 375 K from the Te–Bi<SUB>2</SUB>Te<SUB>3</SUB> thin film. Finally, we confirmed that interface phonon scattering between the Te–Bi<SUB>2</SUB>Te<SUB>3</SUB> boundaries plays an important role in inter-grain phonon transport, which results in a reduction in the lattice thermal conductivity.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Te-Bi<SUB>2</SUB>Te<SUB>3</SUB> nano-grain structure is synthesized by multi-layer deposition and simple annealing process. </LI> <LI> Obtain a dramatic zT value of 2.27 (+ 0.04 − 0.08) at 375 K in Te embedded-Bi<SUB>2</SUB>Te<SUB>3</SUB> thin film. </LI> <LI> The Te-Bi<SUB>2</SUB>Te<SUB>3</SUB> heterojunction has high electrical conductivity and low thermal conductivity. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>

Rapid drug susceptibility test of Mycobacterium tuberculosis using microscopic time-lapse imaging in an agarose matrix

Choi, Jungil,Yoo, Jungheon,Kim, Ki-jung,Kim, Eun-Geun,Park, Kyung Ock,Kim, Hyejin,Kim, Haeun,Jung, Hyunju,Kim, Taeyoung,Choi, Myungjin,Kim, Hee Chan,Ryoo, Sungweon,Jung, Yong-Gyun,Kwon, Sunghoon Springer-Verlag 2016 Applied microbiology and biotechnology Vol.100 No.5

<P>Tuberculosis (TB) is a major global health problem, and multi-drug-resistant TB (MDR-TB) and extensively drug-resistant TB (XDR-TB) are spreading throughout the world. However, conventional drug susceptibility test (DST) methods, which rely on the detection of the colony formation on a solid medium, require 1-2 months to the result. A rapid and accurate DST is necessary to identify patients with drug-resistant TB and treat them with appropriate drugs. Here, we used microscopic imaging of Mycobacterium tuberculosis (MTB) immobilized in an agarose matrix for a rapid DST. The agarose matrix, which was molded in a microfluidic chip, was inoculated with MTB, and TB drugs in liquid culture medium diffused throughout the agarose to reach the MTB immobilized in the agarose matrix. After the responses of MTB to drugs were tracked with an automated microscopic system, an image-processing program automatically determined the susceptibility and resistance of MTB to specific doses of TB drugs. The automatic DST system was able to assess the drug susceptibility of various drug-resistant clinical TB strains within 9 days with an accuracy comparable to that of conventional method. Our rapid DST method based on microscopic time-lapse imaging greatly reduces the time required for a DST and can be used to rapidly and accurately treat TB patients.</P>

Spore-forming probiotic bacterium Bacillus coagulans influences on the flavor of Gouda cheese using micro-cheese platform

Hyejin Choi,Sangdon Ryu,Daye Mun,Woongji Lee,An Na Kang,Mingeun Kang,Hayoung Kim,Daniel Lee,Sangnam Oh,Younghoon Kim 한국식품영양과학회 2021 한국식품영양과학회 학술대회발표집 Vol.2021 No.10

Bacillus coagulans is a gram-positive, spore-forming and potential probiotic bacterium in food industry. Spore-forming bacteria is enable to survive in the host"s gastrointestinal tract functioning as probiotics that could play a beneficial role in the host health. We evaluated the probiotic characteristics including acid, bile and heat tolerance of B. coagulans SRCM121381 isolated from human breast milk. SRCM121381 showed high resistance to acid and bile, heat tolerance. We employed FIMM (Fermentor for Intestine Microbiota Model) system to evaluate effects of SRCM 121381 on the microbial dynamics in gut environments. SRCM121381 resulted in increased population of Romboutsia and Turicibacter at the genus level, while the abundance of Escherichia decreased significantly. We added SRCM 121381 with starter strains for Gouda cheese using micro-cheese platform and evaluated on the change of cheese flavor. SRCM121381 increased acetic acid (Vinegar) and decreased esters and ketone as undesirable flavor such as bitter taste. Our results propose that potential probiotic bacterium B. coagulans SRCM121381 could be applied on dairy foods as an adjunct starter with flavor productivity.

Diagnostic imaging of malignant insulinoma in a dog

Choi, Jihye,Keh, Seoyeon,Kim, Sungsoo,Lee, Su-Hyung,Kim, Hyejin,Choi, Heeyeon,Lim, Younji,Kim, Hyunwook,Kim, Ahyoung,Kim, Dae-Yong The Korean Society of Veterinary Science 2012 大韓獸醫學會誌 Vol.52 No.3

Endocrine test data from a 13-year old intact female Maltese was indicative of the presence of an insulinoma, however ultrasonography identified a pancreatic mass only after 10 months after the first admission. Following identification of both pancreatic tumor and hepatic metastasis on computed tomography (CT), surgical excision of the mass was attempted. However, total excision failed because of tumor adhesion to adjacent large vessels. The pancreatic mass was monitored over the next 25 months via ultrasonography, CT, and positron emission tomography-computed tomography (PET-CT). Histopathological and immunohistochemical data confirmed the diagnosis of insulinoma with hepatic metastasis.

장애인과 비장애인의 통합미용기술교육에 대한 뷰티종사자의 인식도조사

최혜진(Choi Hyejin),차혜옥(Cha Hyeok),이두호(Lee Dooho) 한국장애인재단 2021 장애의 재해석 Vol.2021 No.-

본 연구는 K-뷰티의 전 세계적인 파급력에 힘입어 대한민국 뷰티인들의 가능성을 입증하기 이전에 장애인과 비장애인이 함께 하는 통합미용기술교육에 대한 뷰티종사자들의 요구도를 알아보고 그 실효성을 증명하고자 하였다. 조사 대상자는 미용봉사활동 경험이 있는 뷰티샵 원장, 매니저, 디자이너, 스텝을 비롯한 헤어, 피부, 메이크업, 네일아트, 반영구 화장, 두피모발관리 분야 종사자와 뷰티전공 학생, 미용직업훈련학교 교육생 등으로 장애인식, 장애수용태도, 통합미용기술교육 요구도를 조사하였다. 조사결과 뷰티종사자들은 봉사활동의 경험을 통하여 장애인에 대한 인식도는 높으나 장애인을 수용하는 태도에 있어서 보통의 수준으로 나타났다. 따라서 장애인과 비장애인이 함께하는 통합미용기술 교육을 계기로 장애인에 대한 공감능력과 접촉경험, 재능기부를 통한 활발한 봉사활동을 함으로써 장애수용태도를 향상 시킬 필요성이 요구된다. 또한 통합미용기술교육에 대한 요구도에 대해 대부분 ‘그렇다’에 가까운 응답을 보였는데 이는 장애인과 비장애인의 통합미용기술교육이 전문 기술이기 때문에 비장애인들이 습득하기에도 시간이 많이 소요되는 현실에 근거한 것으로 보인다. 이는 아직 장애유형에 따른 뷰티 전공분야별 교육이 수준별로 체계화된 기준이 없기 때문인 것으로 사료되며 추후 장애인과 비장애인이 함께 교육 받을 수 있는 통합미용기술교육에 대한 구체적인 표준안이 마련되어야 할 것으로 해석된다. 본 연구를 통하여 장애인에게는 사회참여의 기회를 넓히고 다양한 뷰티기술교육을 통한 긍정적인 자기효능감의 향상과 사회 참여도를 높이고자 함이며 비장애인에게는 미용봉사활동을 통한 재능기부의 기회가 될 것이다. 나아가 K-뷰티와 함께하는 장애인과 비장애인의 통합교육으로 자리매김 하기를 바라며 이는 국내 뷰티 교육산업의 발전과 성장뿐만 아니라 전 세계적인 장애인 복지 분야에서 모범의 기회가 될 것으로 기대한다. Before proving the potential of Korean beauty people thanks to the global impact of K-beauty, this study tried to find out the needs of beauty workers for integrated beauty technology education for both disabled and non-disabled people and to prove its effectiveness. The subjects of the survey were selected as beauty shop managers, managers, designers, staff, hair, skin, makeup, nail art, semi-permanent makeup, scalp and hair care, beauty major students, and beauty vocational training school trainees with experience in hairdressing volunteer activities. In addition, the awareness of the disabled, the attitude toward accepting the disability, and the demand for integrated beauty technology education were investigated. As a result of the survey, beauty workers had a high awareness of the disabled through their experiences of volunteering, but showed a moderate level of attitude toward accepting the disabled. Therefore, it is necessary to improve the attitude of accepting people with disabilities through active volunteer activities through empathy, contact experiences, and talent donations with the disabled and non-disabled people as an opportunity to participate in integrated beauty technology education. In addition, most of the responses to the demand for integrated beauty technology education were ‘yes’. see. It is believed that this is because there is no systemized standard for education for each beauty major according to the type of disability. The purpose of this study is to broaden social participation opportunities for the disabled, improve positive self-efficacy through various beauty technology education, and increase social participation. Furthermore, it is hoped that K-Beauty will establish itself as an integrated education for the disabled and non-disabled people together with K-Beauty.

유아교사의 직무자율성과 교수창의성의 관계에서 그릿의 매개효과

최혜진(Hyejin Choi),박리나(Reena Park) 한국생태유아교육학회 2023 생태유아교육연구 Vol.22 No.1

본 연구의 목적은 유아교사의 직무자율성과 교수창의성의 관계에서 그릿의 매개효과를 확인하고자 하였다. 이를 위해 G도에 소재하는 유아교육기관에 근무 중인 교사 224명을 대상으로 하였다. 수집된 자료는 SPSS 23.0과 Process macro 4.0을 활용하여 기술통계, 신뢰도 분석, 상관분석 및 매개효과 분석을 실시하였다. 연구결과는 다음과 같다. 첫째, 유아교사의 직무자율성, 그릿, 교수창의성은 모두 서로 간에 정적 상관관계에 있었다. 둘째, 유아교사의 직무자율성은 교수창의성에 정적 영향을 미치며, 그릿이 직무자율성이 교수창의성에 미치는 영향에서 부분매개역할을 하는 것으로 나타났다. 본 연구결과는 교수창의성에 영향을 미칠 수 있는 변인으로서 직무자율성 뿐만 아니라 그릿의 중요성을 확인함으로써 교수창의성 증진을 위한 시사점을 제공하였다. The purpose of this study was to confirm the mediating effect of grit in the relationship between job autonomy and teaching creativity of Early Childhood Teachers in South Korea. Around 224 teachers working in early childhood educational institutions located in Seoul, Gangwon, and Gyeongsang were recruited. Data were subjected to descriptive statistics, reliability analysis, correlation analysis, and mediating effect analysis using SPSS 23.0 and Process macro 4.0. The findings are as follows. First, early childhood teachers’ job autonomy, teaching creativity, and grit were all positively correlated with each other. Second, their job autonomy had a positive effect on teaching creativity, and some aspects of job autonomy were found to affect teaching creativity through grit. The results of this study provide implications for enhancing teaching creativity by confirming the role and importance of grit as well as job autonomy as variables that can affect teaching creativity.

유아수학능력검사 개발연구

최혜진(Choi HyeJin),황해익(Hwang HaeIk) 한국열린유아교육학회 2004 열린유아교육연구 Vol.8 No.4

본 연구는 수학의 포괄적인 영역을 측정할 수 있는 유아수학능력검사 도구의 개발을 통해, 수학의 하위영역들에 대한 사전지식과 수학문제를 해결하는 능력을 평가하여 현재 유아의 수준을 보다 정확하게 파악할 수 있는 자료를 제공하는 데 그 목적이 있다. 이를 위하여 유아수학능력검사의 시인을 제작하고 2차에 걸친 예비검사를 거쳐 3세-6세 유아 320명에게 실시하여 검사의 문항 양호도(문항 통과을, 문항 변별도)를 비롯한 검사의 양호도(문항내적합치도. 공인타당도, 재검사 신뢰도)를 분석하였다. The purpose of this study is to develop a valid test instrument of mathematical ability for young children. For this purpose, this study analysed the test instruments from home and abroad to measure mathematical ability of young children, the age of 3 to 6, as well as the study on literature of mathematical thinking development and the contents of mathematics education of infants and preschoolers. The subjects of this test were 320 kindergartners and the elementary students who attended their schools for less than 1 month in Busan. Stanford Early School Achievement Test was carried out to 160 children who participated in the test to examine concurrent validity of the test. After 2 weeks of the test, test-retest was carried to 80 children who didn't participated in the concurrent validity test. The result of this research is as follows; First, the final draft of the Test of Mathematical Ability for Young Children consists of 91 questions in 4 areas. Second, the result of the analysis for the adequacy shows that passing rate by age increases according to the age difference. Variation Verification between the top 27% and the bottom 27% to look into the item discrimination shows the significant difference, which means that the item discrimination is high. Third, as the result of adequacy of the test, internal consistency reliability is from .86 to .95 in the subordinate area and .97 in the total test. Test-retest reliability to the stability of the test is .96 in correlation, which means the stability is comparatively high. Concurrent validity to Stanford Early School Achievement Test indicates .56 for the age of 3, .80 for the age of 4, .73 for the age of 5, and .70 for the age of 6.