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- 저자 : Jeongyeon Kim (검색결과 140 건)
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Kim,Jeongyeon,Smith,Hye Young 한국사회언어학회 2019 사회언어학 Vol.27 No.2
This study examines multiple language-identities embedded within the emerging professional teacher identity of international graduate students teaching Korean as a foreign language (KFL). Situated in the context of Korean classrooms at an American university, this study draws data from two rounds of interviews with three instructors (one nonnative and two native Korean speakers). The qualitative analysis reveals that their professional teacher identity revolves around multiple language identities grounded in their L1 cultural norms and perceived English language proficiencies. Their views and undertakings of local cultural norms indicate the varying ways in which these instructors projected their L1 and L2 identities onto their emergent teacher identity. Given the vexed relationship between notions of teacher authority in her L1 Japanese culture and the local norms of interaction, the nonnative teacher maintained authority by establishing a certain distance from her students. By contrast, the native teachers accommodated the local understandings of teacher authority and (re)shaped their view of a teacher to the locally-defined professionalism, a teacher like ‘a friend’. The negotiated identity of the KFL teachers improved classroom interaction and engendered positive view about teaching. The findings are discussed to highlight foreign language teacher identity in a teacher education program.
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EFL Learners’ Perceptions of Learning Context, Writing Achievement, and Gender
Jeongyeon Kim 한국영어어문교육학회 2016 영어어문교육 Vol.22 No.2
For the past decade, Korean higher education has vigorously adopted English-medium instruction (EMI) and web-based learning as key strategies to foster international competitiveness. This study investigates how EFL learners' perceptions of this emerging learning context interplay with their achievements in English writing by gender. The contextual factors include the blended learning approach, an EMI policy, a native and a nonnative English-speaking instructor. The data consisted of questionnaire responses of 95 college students (64 male students and 31 female students) taking an English writing course, their final scores, and qualitative interviews with six students. The analyses of data revealed that the gender difference in the perceptions of the native English-speaking instructor (NI) and the blended learning was significant with their scores being higher in the female group than the male group. Although the difference in participants’ writing achievements was not significant by gender, achievement correlated with contextual factors in a different manner. In the male group, achievement correlated negatively with students’ perceptions of the offline classes taught by a nonnative English-speaking professor. Female students' achievements correlated significantly with the NI and the EMI policy. Pedagogical implications of the findings are proposed for effective, technology-incorporated EFL curriculum and successful implementation of EMI.
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Kim, Jihye,An, Bobae,Kim, Jeongyeon,Park, Sewon,Park, Sungmo,Hong, Ingie,Lee, Sukwon,Park, Kyungjoon,Choi, Sukwoo American College of Neuropsychopharmacology 2015 Neuropsychopharmacology Vol.40 No.13
Various subtypes of metabotropic glutamate receptors (mGluRs) have been implicated in fear extinction, but mGluR2/3 subtype has not been tested. Here, we found that microinjection of an mGluR2/3 antagonist, LY341495, into the lateral amygdala (LA), but not into the adjacent central amygdala (CeA), impaired extinction retention without affecting within-session extinction. In contrast, we failed to detect any significant changes in motility and anxiety during a period when extinction training or retention was performed after LY341495 injection, suggesting that the effect of LY341495 is specific to conditioned responses. Subsequently, on the basis of a previous finding that a long-term potentiation of presynaptic efficacy at cortical input synapses onto the lateral amygdala (C-LA synapses) supports conditioned fear, we tested the hypothesis that activation of mGluR2/3 leads to fear extinction via a long-term weakening of presynaptic functions at C-LA synapses. Fear extinction produced a decrease in C-LA synaptic efficacy, whereas LY341495 infusion into the LA blocked this extinction-induced C-LA efficacy decrease without altering synaptic efficacy at other LA synapses. Furthermore, extinction enhanced paired pulse ratio (PPR) of EPSCs, which inversely correlates with presynaptic release probability, whereas LY341495 infusion into the LA attenuated the extinction-induced increase in PPR, suggesting the presence of mGluR2/3-dependent presynaptic changes after extinction. Consistently, extinction occluded a presynaptic form of depression at C-LA synapses, whereas the LY341495 infusion into the LA rescued this occlusion. Together, our findings suggest that mGluR2/3 is required for extinction retention and that the mGluR2/3 action is mediated by the long-term weakening of release probability at C-LA synapses.
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Kim, Dongwon,Kim, Jong Min,Jeon, Youngmoo,Lee, Jeongyeon,Oh, Jiseop,Hooch Antink, Wytse,Kim, Daekyu,Piao, Yuanzhe Elsevier 2018 Sensors and actuators. B, Chemical Vol.259 No.-
<P><B>Abstract</B></P> <P>The determination of the concentration of acetaminophen (AC) in the human body is of significant importance to carefully monitor and regular drug safety and public health. However, most conventional methods are insufficient due to their time-consuming, expensive and complicated nature. In this study, we report a novel two-step activation of biomass-derived carbon for the electrochemical determination of AC. The electrode material is prepared by a two-step activation process, which involves the initial activation of kelp powder with ZnCl<SUB>2</SUB>, followed by an activation step with KOH. The activation procedure greatly increased the overall pore volume and specific surface area. The characterizations of ZnCl<SUB>2</SUB>-KOH activated kelp carbon (ZKAKC) were conducted with scanning electron microscopy (SEM), transmission electron microscopy (TEM), Raman spectroscopy, Brunauer-Emmett-Teller (BET) surface area analysis, and electrochemical impedance spectroscopy (EIS). The electrochemical characterization of ZKAKC was performed with cyclic voltammetry (CV) analysis of potassium ferricyanide. The sensing ability of ZKAKC/GCE toward acetaminophen was conducted using CV analysis and differential pulse voltammetry (DPV). The modified electrode showed high sensitivity, selectivity and a good detection limit for the determination acetaminophen with the detection limit of 0.004 μM. Also, the modified electrode showed good result toward acetaminophen even in the presence of ascorbic acid and dopamine with the detection limit of 0.007 μM. For the evaluation of sensing ability as an actual electrochemical sensor, a real sample test was conducted. The electrochemical performance was enhanced due to the increased physical and electrochemical surface area, which occurred during the two-step activation process. This approach for producing activated carbon is crucial for future development and can be applied to different carbon source materials.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Activated carbon was prepared with a novel two-step activation process. </LI> <LI> Kelp is used as source material for the biomass-derived activated carbon. </LI> <LI> The modified electrode was used for the electrochemical determination of acetaminophen. </LI> <LI> High sensitivity toward acetaminophen and a low detection limit were achieved. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>
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Reactivation of fear memory renders consolidated amygdala synapses labile.
Kim, Jeongyeon,Song, Beomjong,Hong, Ingie,Kim, Jihye,Lee, Junuk,Park, Sungmo,Yong Eom, Jae,Lee, C Justin,Lee, Sukwon,Choi, Sukwoo The Society 2010 The Journal of neuroscience Vol.30 No.28
<P>It is believed that memory reactivation transiently renders consolidated memory labile and that this labile or deconsolidated memory is reconsolidated in a protein synthesis-dependent manner. The synaptic correlate of memory deconsolidation upon reactivation, however, has not been fully characterized. Here, we show that 3,5-dihydroxyphenylglycine (DHPG), an agonist for group I metabotropic glutamate receptors (mGluRI), induces synaptic depotentiation only at thalamic input synapses onto the lateral amygdala (T-LA synapses) where synaptic potentiation is consolidated, but not at synapses where synaptic potentiation is not consolidated. Using this mGluRI-induced synaptic depotentiation (mGluRI-depotentiation) as a marker of consolidated synapses, we found that mGluRI-depotentiation correlated well with the state of memory deconsolidation and reconsolidation in a predictable manner. DHPG failed to induce mGluRI-depotentiation in slices prepared immediately after reactivation when the reactivated memory was deconsolidated. DHPG induced mGluRI-depotentiation 1 h after reactivation when the reactivated memory was reconsolidated, but it failed to do so when reconsolidation was blocked by a protein synthesis inhibitor. To test the memory-specificity of mGluRI-depotentiation, conditioned fear was acquired twice using two discriminative tones (2.8 and 20 kHz). Under this condition, mGluRI-depotentiation was fully impaired in slices prepared immediately after reactivation with both tones, whereas mGluRI-depotentiation was partially impaired immediately after reactivation with the 20 kHz tone. Consistently, microinjection of DHPG into the LA 1 h after reactivation reduced fear memory retention, whereas DHPG injection immediately after reactivation failed to do so. Our findings suggest that, upon memory reactivation, consolidated T-LA synapses enter a temporary labile state, displaying insensitivity to mGluRI-depotentiation.</P>
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Kim, Dongwon,Kim, Daekyu,Jeon, Youngmoo,Li, Yong,Lee, Jeongyeon,Kang, Jeongmin,Lee, Lawrence Yoon Suk,Piao, Yuanzhe Elsevier 2019 ELECTROCHIMICA ACTA Vol.299 No.-
<P><B>Abstract</B></P> <P>The development of highly effective and low-cost non-noble metal electrochemical catalysts for oxygen evolution reactions (OER) is a major challenge for overall water splitting and rechargeable metal-air batteries. In this study, we develop a novel hollow cobalt-borate modified cobalt oxide composite (denoted by Co-B-O@Co<SUB>3</SUB>O<SUB>4</SUB>) catalyst derived from zeolitic imidazolate framework-67 (ZIF-67) for electrochemical OER. The Co-B-O@Co<SUB>3</SUB>O<SUB>4</SUB> was easily synthesized via pyrolysis of ZIF-67 in Ar and air to produce hollow Co<SUB>3</SUB>O<SUB>4</SUB> (denoted by h-Co<SUB>3</SUB>O<SUB>4</SUB>), followed by simple NaBH<SUB>4</SUB> treatment at ambient temperature for 4 h. The unique polyhedral morphology was well preserved during the NaBH<SUB>4</SUB> treatment. Benefiting from its structural and compositional merit, the as-synthesized Co-B-O@Co<SUB>3</SUB>O<SUB>4</SUB> exhibit excellent electrocatalytic activity and long-term stability for OER. Also, we conducted the OER test using a Co-B-O@Co<SUB>3</SUB>O<SUB>4</SUB> catalyst in a neutral pH environment for further investigation. Our study can provide an insight into catalyst modification step to enhance the overall performance while keeping its physical structure simultaneously. using metal-organic framework for the electrochemical catalyst thus can be recognized as a method for producing a highly active, long-term working and novel engineered electrocatalyst for OER applications.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Co-B-O@Co<SUB>3</SUB>O<SUB>4</SUB> was prepared using calcination-NaBH<SUB>4</SUB> treatment strategy with a facile and energy efficient method. </LI> <LI> A distinctive polyhedral morphology of Co-B-O@Co<SUB>3</SUB>O<SUB>4</SUB> was well preserved after the NaBH<SUB>4</SUB> treatment of its precursor material. </LI> <LI> Co-B-O@Co<SUB>3</SUB>O<SUB>4</SUB> was employed for the electrochemical oxygen evolution reaction. </LI> <LI> Co-B-O@Co<SUB>3</SUB>O<SUB>4</SUB> showed excellent catalytic performance and long-term durability for oxygen evolution reaction in basic media. </LI> </UL> </P>
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