Investigation of biomimetic shear stress on cellular uptake and mechanism of polystyrene nanoparticles in various cancer cell lines

Taehee Kang,박철훈,Beom-Jin Lee 대한약학회 2016 Archives of Pharmacal Research Vol.39 No.12

Cancer cells in the tumor microenvironment areaffected by fluid shear stress generated by blood flow in thevascular microenvironment and interstitial flows in thetumor microenvironment. Thus, we investigated how fluidicshear stress affects cellular uptake as well as theendocytosis mechanism of nanoparticles using a biomimeticmicrofluidic system that mimics the human dynamicenvironment. Positively charged amino-modified polystyrenenanoparticles (PSNs) at 100 lg/mL were deliveredto cancer cells under static and biomimetic dynamic conditions(0.5 dyne/cm2). Additionally, the experiment wasdone in the presence of endocytosis inhibitors specific forone of the endocytosis pathways. To evaluate cellularuptake of cationic PSNs, the fluorescence intensity ofcationic PSNs in cancer cells was measured by flowcytometer and fluorescence images were taken using confocallaser scanning microscopy. Cancer cells in dynamicconditions exhibited higher cellular uptake of PSNs andshowed different cellular uptake mechanisms comparedwith those in static conditions. From these results, it suggestedthat biomimetic dynamic conditions stimulatedspecific endocytosis and prompted cellular uptake. It wasalso important to consider fluidic shear stress as one of thecritical factors because cellular uptake and drug deliverycould play a key role in cancer cells and metastasis.

Resonance tuning of electric field enhancement of nanogaps

Kang, Taehee,Rhie, Jiyeah,Park, Joohyun,Bahk, Young-Mi,Ahn, Jae Sung,Jeon, Hyeongtag,Kim, Dai-Sik JAPAN SOCIETY OF APPLIED PHYSICS 2015 Applied physics express Vol.8 No.9

중등 예비 화학교사의 수행평가 개발 과정에서 나타나는 교과교육학 지식(PCK) 요소의 특징

노태희 ( Taehee Noh ),이재원 ( Jaewon Lee ),강석진 ( Sukjin Kang ),한재영 ( Jaeyoung Han ),강훈식 ( Hunsik Kang ) 한국과학교육학회 2017 한국과학교육학회지 Vol.37 No.2

이 연구에서는 예비 화학교사의 수행평가 개발 과정에서 나타나는 교과교육학 지식(PCK) 요소의 특징을 분석하였다. 예비교사 8명이 연구에 참여하였고, 이들은 수행평가 워크숍 후 구상 단계, 구체화 단계와 조별 논의 단계를 거쳐 수행평가를 개발하였다. 활동 과정에 대한 녹음 및 녹화와 반구조화된 면담을 실시하였다. 분석 결과, 개별적인 개발 단계에서 나타난 PCK 요소는 과학 평가에 관한 지식에 편중되어 있었다. 교육과정, 교수 전략, 학생에 관한 지식의 비중은 낮았으며 학생에게 제공되는 피드백도 고려되지 않았다. 구상 단계보다 구체화 단계에서 평가의 공정성과 객관성을 중시하는 전통적 평가 지향이 강하게 나타났다. PCK 요소 사이의 연계는 구상 단계에서 과학 교수 전략에 관한 지식을 중심으로 이루어졌다. 구체화 및 조별 논의 단계에서 PCK 요소 사이의 연계는 거의 나타나지 않았다. 조별 논의에서 나타난 PCK 요소의 특징은 구체화 단계와 유사하였다. 조별 논의를 통하여 예비교사들이 고려하지 못했던 일부 PCK 요소가 보완되었으나 논의가 주로 전통적 관점에서 이루어졌다. In this study, we investigated the characteristics of the PCK components of pre-service chemistry teachers considered in the processes of developing performance assessment. Eight pre-service teachers participated in this study. After the workshop for performance assessment, they developed performance assessment through the planning, embodying and small group discussion step. Their activities were recorded and videotaped. Semi-structured interviews were also conducted. It was found that the PCK component considered in developing performance assessment individually was mainly the knowledge of assessment in science. The proportions of knowledge of curriculum, instructional strategies and students were found to be relatively low. The feedback on students` performance was not considered at all. The orientation to traditional assessment which emphasized on the objectivity of assessment, was stronger in the embodying step rather than in the planning step. During the planning step, the integrations among the PCK components mainly appeared with the knowledge of instructional strategies. However, they hardly appeared in the embodying and discussion steps. The main characteristics of the PCK in small group discussion were similar with those in the embodying step. Some PCK components were considered more in small group discussion, but most discussions were in the traditional perspectives.

소셜 클라우드 서비스의 운용메커니즘 분석 및 설계 방안

강태희(Taehee Kang),라현우(Hyunwoo Ra),전한구(Hangoo Jeon),서광규(Kwang-Kyu Seo) 한국산학기술학회 2014 한국산학기술학회 학술대회 Vol.2014 No.2

클라우드 컴퓨팅 서비스는 클라우드 서비스 고객에게 편리하면서도 온디맨드 (on-demand) 방식으로 풀(pool) 형태로 준비되어 있는 공유 자원을 제공한다. 클라우드 서비스 고객은 별도의 자신만을 위한 정보자산을 구입하여 운영하는 대신에, 이를 사업자로부터 임대해 사용함으로써 비즈니스 경제성을 확보할 수 있다. 소셜 네트워크 서비스(social network service)는 사람들 사이의 사회적 관계나 사회적 네트워크를 반영 또는 구성하는 것을 목적으로 하는 사이트, 플랫폼 등의 온라인 서비스이다. 최근에는 이러한 두 서비스가 결합된 새로운 비즈니스 모델인 소셜 클라우드 서비스가 제시되고 있는데 본 연구에서는 사례연구를 통하여 소셜 클라우드 서비스의 운용메커니즘의 분석을 수행하고 이를 통하여 소셜 클라우드 서비스 설계 방안을 위한 가이드라인을 제시한다.

용해와 용액 개념에 대한 학습발달과정 조사

노태희 ( Taehee Noh ),이재원 ( Jaewon Lee ),양찬호 ( Chanho Yang ),강석진 ( Sukjin Kang ),강훈식 ( Hunsik Kang ) 한국과학교육학회 2016 한국과학교육학회지 Vol.36 No.2

이 연구에서는 구인 모델링 방식을 적용하여 초등학교 5학년∼중학교 3학년 학생들의 용해와 용액 개념에 대한 학습발달과정을 조사하였다. 이를 위해 현행 교육과정과 선행연구를 분석하여 용해와 용액 개념 이해의 가설적 발달 경로인 초기 구인 구성도를 설정하였고, 이를 바탕으로 순위정렬 선다형 평가 문항으로 구성된 검사지를 제작하였다. 826명의 학생들을 대상으로 검사를 실시하였으며, 다분 문항반응이론의 모형 중 부분 점수 모형을 활용하여 분석한 결과를 바탕으로 구인 구성도를 수정하였다. 연구 결과, 현행 교육과정에서 학년에 따른 용해와 용액 개념의 제시 순서는 대체로 학생들의 학습발달과정에 부합하는 것으로 나타났다. 그러나 하위 정착점과 용액에서 입자의 균일 분포 개념, 용해도에 영향을 미치는 요인에 대한 이해는 구인 구성도를 통해 이론적으로 예상한 수준과 달랐다. 수정된 구인구성도에 따라 초·중등학생의 용해와 용액 개념에 대한 학습발달과정을 도출하였다. 하위정착점인 수준 1은 용해와 용액을 입자 관점에서 인식할 수 있으나 다양한 오개념을 지니는 수준으로, 수준 2는 용액에서 입자의 균일 분포 개념을 이해하는 수준으로, 수준 3은 용해도와 입자의 보존 개념을 이해하는 수준으로 설정되었다. 또한, 수준4는 입자간 인력을 인식할 수 있으나 다양한 오개념을 지니는 수준으로, 상위정착점인 수준 5는 입자간 인력과 용해도에 영향을 미치는 요인을 이해하는 수준으로 설정되었다. In this study, we investigated a learning progression focusing on 5th to 9th graders’ performances with dissolution and solution concepts using the construct modeling approach. We designed a construct map describing hypothetical pathways of the concept development of dissolution and solution by analyzing both National Science Curricula and related studies. A conceptions test consisting of ordered multiple-choice items was developed and administered to 826 students. A revised construct map was derived from analyses of the results based on the partial credit model, a branch of polytomous item response theory. The sequence of dissolution and solution concepts presented in the current science curriculum was found to correspond with the learning progression of the students. However, the lower anchor, the concept of the homogeneity of particles in solution, and the factors affecting solubility were not consistent with the expected levels of the construct map. After revising the construct map, we proposed a learning progression for dissolution and solution concepts with five levels: Students of level 1 (the lower anchor) recognize the particles in the solution but misunderstand various concepts; Students of level 2 understand the homogeneity of particles in solution; Students of level 3 understand solubility and the conservation of particles during dissolution; Students of level 4 partially understand the interaction between particles; and Students of level 5 (the upper anchor) understand the interaction between particles and the factors affecting solubility.

기업문화의 유형이 기업명성에 미치는 영향

강태희(Taehee Kang),차희원(Heewon Cha) 한국언론학회 2010 한국언론학보 Vol.54 No.1

중등 과학교사의 과학 평가 실태와 지향

노태희 ( Taehee Noh ),이재원 ( Jaewon Lee ),강석진 ( Sukjin Kang ),강훈식 ( Hunsik Kang ) 한국과학교육학회 2015 한국과학교육학회지 Vol.35 No.4

이 연구에서는 중등 과학교사들이 실시하는 과학 평가와 교사들이 지향하는 평가의 사례를 목적과 방법의 측면에서 조사하였다. 연구대상은 중등 과학교사 92명으로, 학교에서 교사가 실시했던 평가 사례와 구성주의적 평가를 실시할 수 있는 전형적인 가상 상황에 대하여 교사가 지향하는 평가 사례를 조사하기 위한 검사지를 개발하였다. 교사의 경력, 평가 관련 교육 경험의 유무, 구성주의적 과학 평가관 수준 등 교사의 특성 변인도 조사하였다. 교사들이 실시하는 과학 평가사례를 분석한 결과, 대부분의 교사는 총괄평가와 같은 전통적인 목적의 평가를 실시하는 경향이 있었고, 선다형 평가와 실험, 보고서, 논술형 평가가 가장 많이 사용되는 평가 방법이었다. 전형적인 평가 상황에서 과학교사들은 다양한 유형의 구성주의적 평가 방법을 지향한 반면, 여전히 전통적 평가 목적에서는 벗어나지 못하였다. 이때, 구성주의적 과학 평가관 수준이 높은 교사가 형성평가를 지향하는 비율은 구성주의적 과학 평가관 수준이 낮은 교사들에 비해 유의미하게 높았다. In this study, we investigated secondary school science teachers’ actual and preferred types of assessment with focus on the purpose and the method of assessment. Participants were 92 secondary school science teachers. We developed a questionnaire asking science teachers about the types of assessment they have actually used and the preferred types of assessment for hypothetical situations that have been generally reported as the prototypical examples of constructivist assessment. The characteristics of the science teachers such as teaching career, experience on in-service training about assessment, and perspective toward constructivist assessment were also examined. The analysis of the actually implemented assessments in their responses revealed that most science teachers tended to aim at traditional purposes such as summative assessment, and that multiple-choice was the most prevailing assessment method followed by experiment, report, and essay. For hypothetical assessment situations, science teachers exhibited their preferences for various types of constructivist assessment methods, whereas their purposes of the assessment still remained to be traditional. The science teachers who have had a relatively constructivist perspective toward assessment showed a statistically significant preference for using formative assessment than their counterparts in the hypothetical assessment situations.

한반도 주요 대도시의 PM₁₀ 농도 특성 및 배출량과의 상관성 분석

강민성 ( Minsung Kang ),김유근 ( Yoo-keun Kim ),김태희 ( Taehee Kim ),강윤희 ( Yoon-hee Kang ),정주희 ( Ju-hee Jeong ) 한국환경과학회 2016 한국환경과학회지 Vol.25 No.8

This study analyzes the PM₁₀ characteristics (particulate matter with aerodynamic diameter less than 10 ㎛), concentration, and emissions in eight large South Korean cities (Seoul, Incheon, Daejeon, Daegu, Gwangju, Ulsan, Busan, Jeju). The annual median ofPM₁₀ concentration showed a decline of 0.02~1.97 ㎍/㎥ in the regions, except for Incheon, which recorded an annual 0.02 ㎍/㎥ increase. The monthly distribution levels were high in spring, winter, fall, and the summer, but were lower in summer for all regions except for Ulsan. These differences are thought to be due to the dust in spring and the cleaning effect of precipitation in summer. The variation in concentrations during the day (diurnal variation) showed that PM₁₀ levels were very high during the rush hour and that this was most extreme in the cities (10.00 and 18.00-21.00). The total annual PM₁₀ emissions analysis suggested that there had been a general decrease, except for Jeju. On-road mobile (OM) sources, which contributed a large proportion of the particulates in most regions, decreased, but fugitive dust (FD) sources increased in the remaining regions, except for Daegu. The correlation analysis between PM₁₀ concentrations and emissions showed that FD could be used as a valid, positive predictor of PM₁₀ emissions in Seoul (74.5% (p<0.05)), Dajeon (47.2% (p<0.05)), and Busan (59.1% (p<0.01)). Furthermore, industrial combustion (IC) was also a significant predictor in Incheon (61.7% (p<0.01)), and on-road mobile (OC) sources were a valid predictor in Daegu (24.8% (p<0.05)).

Promiscuous methionyl-tRNA synthetase mediates adaptive mistranslation to protect cells against oxidative stress

Lee, Jin Young,Kim, Dae Gyu,Kim, Byung-Gyu,Yang, Won Suk,Hong, Jeena,Kang, Taehee,Oh, Young Sun,Kim, Kyung Rok,Han, Byung Woo,Hwang, Byung Joon,Kang, Beom Sik,Kang, Mi-Sun,Kim, Myung-Hee,Kwon, Nam Hoo The Company of Biologists Ltd. 2014 Journal of cell science Vol.127 No.19

<P><B>ABSTRACT</B></P><P>Aminoacyl-tRNA synthetases (ARSs) acylate transfer (t)RNAs with amino acids. Charging tRNAs with the right amino acids is the first step in translation; therefore, the accurate and error-free functioning of ARSs is an essential prerequisite for translational fidelity. A recent study found that methionine (Met) can be incorporated into non-Met residues of proteins through methionylation of non-cognate tRNAs under conditions of oxidative stress. However, it was not understood how this mis-methionylation is achieved. Here, we report that methionyl-tRNA synthetase (MRS) is phosphorylated at Ser209 and Ser825 by extracellular signal-related kinase (ERK1/2) under conditions of stress caused by reactive oxygen species (ROS), and that this phosphorylated MRS shows increased affinity for non-cognate tRNAs with lower affinity for tRNA<SUP>Met</SUP>, leading to an increase in Met residues in cellular proteins. The expression of a mutant MRS containing the substitutions S209D and S825D, mimicking dual phosphorylation, reduced ROS levels and cell death. This controlled inaccuracy of MRS seems to serve as a defense mechanism against ROS-mediated damage at the cost of translational fidelity.</P>

Toughening Epoxy Resins with Core—Shell (HTPB-PMMA/PMA) Rubber Particles

Kang, Sunghee,Kim, Daeyeon,Kim, Taehee,Lee, Wonjoo,Kim, Hyeon-Gook,Chung, Jin Suk,Lim, Choong-Sun,Chang, Sang-Mok,Seo, Bongkuk American Scientific Publishers 2017 Journal of nanoscience and nanotechnology Vol.17 No.10

<P>Epoxy resins, which are thermoset polymers, are widely used in coatings and adhesives because of their good heat and chemical resistance, as well as their adhesive strength. However, these polymers are brittle, meaning they have a poor resistance to impact. The brittleness of epoxy resins can be reduced using a variety of toughening agents, such as core-shell particles, polyurethanes, or polyester polymers. In the particular case of core-shell particles, the core part is usually composed of rubber polymers, such as polybutadiene, to improve the impact strength of the epoxy resins; while the shell part is made of glassy polymers, like poly(methylmethacrylate). In this study, core-shell rubber particles (CSRPs) synthesized by emulsion polymerization, were used to improve the physical properties of epoxy resins. Fourier transform infrared spectroscopy (FT-IR) was used to study the structure of the CSRPs. Differential scanning calorimetry (DSC) was conducted to find the glass transition temperature (T-g) of the samples. The morphology of the synthesized CSRPs was analyzed using a scanning electron microscope (SEM) and a transmission electron microscope (TEM). Furthermore, the impact strength of cured epoxy compositions, including that of CSRPs, was measured with an Izod impact tester.</P>