Growth and Temperature Dependence of Band Gap for CdIn2S4 Epilayers byHot Wall Epitaxy

Sukjin Yun,Kwangjoon Hong 한국물리학회 2004 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.45 No.3

High quality CdIn2S4 epilayers on GaAs(100) substrate were rst grown by using the hot wall epitaxy (HWE) method. The grown CdIn2S4 epilayer was found to be in the <110> direction. The optimum growth temperatures of the substrate and the source turned out to be 420 and 630 C, respectively. From measurement of the temperature dependence of the Hall mobility, scattering in the high-temperature range was mainly related to the acoustic mode of lattice vibration, and scattering at the low-temperature range was most pronounced, due to the impurity eect. The temperature dependence of the energy band gap on the CdIn2S4/GaAs epilayer, obtained from optical-absorption measurement, was found to be Eg(T) = 2.7116 eV - (7.65 10က4 eV/K)T2/(425 + T).

한국 텔레비전 장르드라마 연구

윤석진 ( Yun Sukjin ),박상완 ( Park Sangwan ),권양현 ( Kwon Yanghyun ) 전북대학교 인문학연구소 2017 건지인문학 Vol.0 No.18

Television dramas are cultural contents in which both artistic and industrial properties coexist. In this article, I looked at genre drama in terms of television drama planning, which considers both artistic and industrial attributes. The main sub-genres of TV dramas that have been discussed so far are divided into two types in terms of `what` and `how`. First, it typified the genres of `history, medicine, court, investigation, and politics`, which are genuine concepts such as background, person, This type induces viewers` interest through discriminatory sanctions, which is characterized by the fact that discriminatory sanctions are related to contemporary consciousness of the problem. In other words, it is a type showing the possibility of creating discourse of TV drama in that the sanctions are not consumed once but are aimed at reflection on the reality. Next, I typed the melodrama, action comedy, romantic comedy, mystery, and sitcom genre, which is a genre concept with narrative elements such as message, emotion, plot, and format, as genres of emotion. This type emphasizes the cumulative emotional aspect over time rather than immediate sanctions. It is a type that has a significance in itself to indirectly experience the emotions such as sadness, pleasure, laughter, and fear that the work emits while the viewer is immersed in the situation and characters. There has been a limitation that the standard of the genre drama so far has not been uniform. In reality, it is impossible to find an absolute criterion that can be applied collectively to all sub-genres. However, as discussed in this article, once the genre has been recognized by recognizing materials, backgrounds, settings, subjects, and plots that have become the existing criteria, a new approach to genre dramas will be possible if they are reclassified according to their characteristics do.

최대출력을 얻기 위한 유도급전장치의 형태에 따른 전자장 해석

최석진(Sukjin Choi),오윤상(Yun-Sang Oh),이상진(Sangjin Lee),이병송(Byung Song Lee),박찬배(Chan-Bae Park),이형우(Hyung-Woo Lee) 한국철도학회 2010 한국철도학회 학술발표대회논문집 Vol.2010 No.7

The equivalent circuits intended to analyze the characteristics of IPT systems can be shown in structures similar to those of existing transformers. IPT systems are composed of combinations of the primary and secondary coils based on magnetic coupling, and the performances are determined by the lengths or the degrees of magnetic coupling of current collecting conductors(secondary) and feeding rails (primary) and system performances become the maximum when they are coupled under the optimum condition. To maximize the output currents of the secondary side, the shapes of iron cores and the structures of coils etc should be considered. To this end, three types of IPT system simulation models were selected and they were analyzed using an electromagnetic field analyzing program. To compare the types with each other, the sizes of the IPT systems and the primary side voltages etc were made to be the same. The electromagnetic fields were analyzed while changing the thicknesses of the cores and the lengths of the air gap etc and the results were analyzed in order to derive the optimum specifications.

The temperature-dependent behavior of the photocurrent spectra of CdIn2S4 films

홍광준,Sukjin Yun,Jangbok Kim 한양대학교 세라믹연구소 2006 Journal of Ceramic Processing Research Vol.7 No.4

CdIn2S4 (110) films were grown on semi-insulating GaAs (100) by a hot wall epitaxy method. Using photocurrent (PC) measurements, the PC spectra in the temperature range of 30 to 10 K appeared as three peaks in the short wavelength region. It was found that three peaks, A-, B-, and C-excitons, correspond to the intrinsic transition from the valence band states of Γ4(z), Γ5(x), and Γ5(y) to the exciton below the conduction band state of Γ1(s), respectively. A 0.122 eV crystal field splitting and the 0.017 eV spin orbit splitting were obtained. Thus, the temperature dependence of the optical band gap obtained from the PC measurements was well described by Eg(T)=2.7116 eV−(7.65×10−4 eV/K)T2/(425+T). However, the behavior of the PC was different from that generally observed in other semiconductors. The PC intensities decreased with decreasing temperature. This phenomenon had ever been reported in a PC experiment on bulk crystals grown by the Bridgman method. From the relation of log Jph vs 1/T, where Jph is the PC density, two dominant levels were observed, one at high temperatures and the other at low temperatures. Consequently, the trapping centers due to native defects in the CdIn2S4 film were suggested to be the cause of the decrease in the PC signal with decreasing temperature. CdIn2S4 (110) films were grown on semi-insulating GaAs (100) by a hot wall epitaxy method. Using photocurrent (PC) measurements, the PC spectra in the temperature range of 30 to 10 K appeared as three peaks in the short wavelength region. It was found that three peaks, A-, B-, and C-excitons, correspond to the intrinsic transition from the valence band states of Γ4(z), Γ5(x), and Γ5(y) to the exciton below the conduction band state of Γ1(s), respectively. A 0.122 eV crystal field splitting and the 0.017 eV spin orbit splitting were obtained. Thus, the temperature dependence of the optical band gap obtained from the PC measurements was well described by Eg(T)=2.7116 eV−(7.65×10−4 eV/K)T2/(425+T). However, the behavior of the PC was different from that generally observed in other semiconductors. The PC intensities decreased with decreasing temperature. This phenomenon had ever been reported in a PC experiment on bulk crystals grown by the Bridgman method. From the relation of log Jph vs 1/T, where Jph is the PC density, two dominant levels were observed, one at high temperatures and the other at low temperatures. Consequently, the trapping centers due to native defects in the CdIn2S4 film were suggested to be the cause of the decrease in the PC signal with decreasing temperature.

과학 수업에서 스마트 기기를 활용한 소집단 학습의 효과

윤정현 ( Jeonghyun Yun ),강석진 ( Sukjin Kang ),노태희 ( Taehee Noh ) 한국과학교육학회 2016 한국과학교육학회지 Vol.36 No.4

이 연구는 스마트 기기를 활용한 소집단 학습이 학생들의 학업 성취도, 학습 동기, 과학 수업에 대한 태도, 스마트 기기를 활용한 소집단 학습에 대한 인식 측면에 미치는 영향에 관하여 조사하고자 하였다. 서울시에 소재한 남녀 공학 고등학교 2학년 4개 학급(133명)을 통제 집단과 처치 집단으로 무선 배치하였다. 스마트 기기를 활용한 소집단 학습 전략은 협력적 활동지 작성을 강조하였다. 수업 처치는 ‘산과 염기’와 ‘중화반응’에 대하여 6차시 동안 실시하였다. 수업처치 후, 학업 성취도 검사, 학습 동기 검사, 과학 수업에 대한 태도검사, 스마트 기기를 활용한 소집단 학습에 대한 인식 검사를 실시하였다. 이원 공변량 분석 결과, 학업 성취도 검사 점수에서 사전 화학 성취도와의 상호작용 효과가 유의미하게 나타났다. 스마트 기기를 활용한 소집단 학습에서 하위 수준 학생들이 상위 수준의 학생들에게 도움을 받을 기회가 많아져서 성취도가 유의미하게 향상되었을 수있다. 학습 동기, 과학 수업에 대한 태도에서 처치 집단의 교정 평균이 통제 집단에 비하여 유의미하게 높았다. 스마트 기기를 활용한 소집단 학습에 대한 학생들의 인식도 긍정적인 것으로 나타났다. 이 연구에 대한 교육적 함의를 논의하였다. The purpose of this study is to investigate the influences of small group learning using smart devices in science classes on students’ achievement, learning motivation, attitude toward science lessons, and perception of small group learning using smart devices. Four 11th-grade classes (N=133) at a coed high school in Seoul were randomly assigned to a control group and a treatment group. The intervention of small group learning using smart devices emphasized collaborative writing on activity sheet. The students were taught about acid, base, and neutralization reaction for six class periods. After the instructions, an achievement test, the learning motivation test, the attitude toward science lessons test, and a questionnaire on the perception of small group learning using smart devices were administered. Two-way ANCOVA results revealed that there was a statistically significant interaction effect by their previous chemistry achievement in the achievement test scores. Only low-level students in small group learning using smart devices significantly improved their achievement probably by having the opportunities to get help from high-level students. The adjusted means of the treatment group were significantly higher than those of the control group in learning motivation and attitude toward science lessons. Students’ perceptions of small group learning using smart devices tended to be positive. Educational implications of this study are discussed.

초등 과학 수업에서 스마트 기기를 활용한 소집단 협력 학습의 효과

강석진,윤성용,Kang, Sukjin,Yun, Sungyong 한국초등과학교육학회 2017 초등과학교육 Vol.36 No.3

In this study, the effects of the small group collaborative learning on students' achievement, the retention of the achievement, communication anxiety, and science learning motivation were investigated. The aptitude-treatment interaction between the level of students' self-directed learning ability and the intervention was also examined. Two classes (38 students) from an elementary school were respectively assigned to a control group and a treatment group. A self-directed learning ability test, a communication anxiety test, and a science learning motivation test were administered as pretests. The intervention lasted for 8 class periods. After instruction, an achievement test, the communication anxiety test, and the science learning motivation test were administered. An achievement retention test were also administered after four weeks. The results indicated that there were significant treatmentaptitude interaction effects in the achievement test scores and the achievement retention test scores. In the communication anxiety and the science learning motivation, however, any significant difference was not found between the scores of the treatment group and the control group. Educational implications are discussed.

스마트 기기를 활용한 소집단 과학 학습에서 학생의 언어적 상호작용 분석

윤정현,강석진,안인영,노태희,Yun, Jeonghyun,Kang, Sukjin,Ahn, Inyoung,Noh, Taehee 대한화학회 2017 대한화학회지 Vol.61 No.3

이 연구에서는 스마트 기기를 활용한 소집단 과학 학습 과정에서 사전 성취 수준에 따른 언어적 상호작용을 분석하였다. 서울시의 한 남녀 공학 고등학교에서 사전 성취 수준 측면에서 이질적으로 구성된 4개의 소집단이 참여하였다. 스마트 기기를 활용한 소집단 과학 학습 과정에서 일어나는 언어적 상호작용을 녹음 및 녹화하고 기록 원고를 작성한 뒤 분석하였다. 학생들 사이의 언어적 상호작용은 개별 진술과 상호작용 단위 수준에서 분석하였다. 연구 결과, 스마트 기기를 활용한 소집단 학습에서 학생 사이의 언어적 상호작용은 과제 관련 진술의 빈도가 높았는데, 특히 정보 설명, 정보 질문, 기준 반성의 빈도가 높았다. 방향 설명, 기준 반성, 진행에서는 사전 성취 수준 상위 학생들의 진술 빈도가 높게 나타났고, 방향 질문, 정보 설명에서는 하위 수준 학생들의 진술 빈도가 높게 나타났다. 상호작용 단위에서는 지식 구성 상호작용 중 대칭적 정교화 상호작용의 빈도가 높았는데, 특히 누적형과 평가형이 높게 나타났다. In this study, we analyzed verbal interactions in small group science learning using smart devices by the level of prior achievement. Four heterogeneous groups at a coed high school in Seoul participated. Verbal interactions during small group science learning were audio- and video-taped, transcribed, and analyzed. Verbal interactions were analyzed at the levels of a turn and an interaction unit. The results revealed that the frequencies of verbal interactions were high in task category, especially at information explanation, information question, and reflection on standards subcategories. Furthermore, the frequencies of high-level students at direction explanation, reflection on standards and progress subcategories were higher than those of low-level students, and the frequencies of low-level students at direction question and information explanation subcategories were higher than their counterpart. In the analyses of the interaction units, the frequencies in symmetric elaborated interaction were high, especially at cumulative and evaluative subcategories.

Physical exercise enhances adult cortical plasticity in a neonatal rat model of hypoxic-ischemic injury: Evidence from BOLD-fMRI and electrophysiological recordings

Chae, Sun Young,Jang, Jun Ho,Im, Geun Ho,Jeong, Ji-Hyun,Jung, Won-Beom,Ko, Sukjin,Jie, Hyesoo,Kim, Ji Hye,Chang, Yun Sil,Chung, Seungsoo,Kim, Ki-Soo,Lee, Jung Hee Elsevier 2019 NeuroImage Vol.188 No.-

<P><B>Abstract</B></P> <P>Neuroplasticity is considered essential for recovery from brain injury in developing brains. Recent studies indicate that it is especially effective during early postnatal development and during the critical period. The current study used functional magnetic resonance imaging (fMRI) and local field potential (LFP) electrophysiological recordings in rats that experienced neonatal hypoxic-ischemic (HI) injury during the critical period to demonstrate that physical exercise (PE) can improve cortical plasticity even when performed during adulthood, after the critical period. We investigated to what extent the blood oxygen level-dependent (BOLD)-fMRI responses were increased in the contralesional spared cortex, and how these increases were related to the LFP electrophysiological measurements and the functional outcome. The balance of excitation and inhibition was assessed by measuring excitatory and inhibitory postsynaptic currents in stellate cells in the primary somatosensory (S1) cortex, which was compared with the BOLD-fMRI responses in the contralesional S1 cortex. The ratio of inhibitory postsynaptic current (IPSC) to excitatory postsynaptic current (EPSC) at the thalamocortical (TC) input to the spared S1 cortex was significantly increased by PE, which is consistent with the increased BOLD-fMRI responses and improved functional outcome. Our data clearly demonstrate in an experimental rat model of HI injury during the critical period that PE in adulthood enhances neuroplasticity and suggest that enhanced feed-forward inhibition at the TC input to the S1 cortex might underlie the PE-induced amelioration of the somatosensory deficits caused by the HI injury. In summary, the results of the current study indicate that PE, even if performed beyond the critical period or during adulthood, can be an effective therapy to treat neonatal brain injuries, providing a potential mechanism for the development of a potent rehabilitation strategy to alleviate HI-induced neurological impairments.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Physical exercise (PE) enhances cortical plasticity in hypoxic-ischemic (HI) injury. </LI> <LI> Cortical plasticity can be monitored by fMRI and electrophysiological recordings. </LI> <LI> Enhanced feed-forward inhibition improves the somatosensory deficits in HI injury. </LI> <LI> PE can be a therapeutic method for brain injuries in newborns and infants. </LI> </UL> </P>