(A) STUDY ON METHOD OF UTILIZATION YOUTH GROUP ACTIVITY PROGRAM

The need for group activity is stronger in youth than other ages. In order to be matured, the youth intend to find the path to independence from the people who heretofore protected, nourished and taught them. Even after their physical appearance is completely matured, there still remain some emotional and social conflicts and anxieties. In order to balance some extent against such unstable status, the youth look for the identity relationship with followers in the group activity work. Thus the youth will need. group activity program for better exploration chances and let out the youth energy toward proper direction. 2. METHOD OF RESEARCH STUDY : Research materials for youth group activity programs have been collected and analized. What is the kind of program needed for the youth group activity was determined and method of utilization, PERT system program, was established. It followed the processes stated below for the establishment of such program : a. Several alternative plans were initially prepared and the best adaptable program was selected. b. If the selected plan faces any problems, the alternative plan has immediately been substituted. c. The plan outlines were drawn into the detailed plan and then it was reoutlined in a summary. d. Multiple review of various elements and rearrangement thereof were systematically conducted. 3. CONCLUSION : To experience is the most important factor in the social group work. The group activity is to experience relationship between leaders and fellow youth, one's own emotion, skill and taste. Therefore, the group activity should always allow group member to experience something and should provide opportunity to learn something. Thus, each individual member should be able to increase his experience and to rectify his errors through the medium of group activity program which will help each individual member grow and develop through normal course. Further assistance should. be given to emotionally and mentally disturbed persons. However, the group leader should not use subjective guidance for the group activity works but should give sufficient consideration to the desire of the individual group member and to difference in each, individual cultural backgrounds.영문초록 제1장 서론 = 5 제1절 연구의 목적과 방법 = 5 (1) 연구조사의 목적 = 5 (2) 자료수집 및 처리 = 6 (3) 결과 및 해석 = 11 제2장 본론 = 15 제1절 청소년과 집단 = 15 (1) 청소년의 개념 = 15 (2) 집단 = 18 제2절 PROGRAM의 활용방안 = 23 (1) PROGRAM의 유형 = 23 (2) PERT식 PROGRAM의 계획 = 29 (3) PROGRAM의 방법 = 36 A. Group discussion = 36 B. Recreation = 51 C. Role playing = 62 (4) PROGRAM 활용상의 문제 = 69 (5) PROGRAM 활용상의 주의점 = 73 제3장 결론(요약 및 결어) = 77 참고문헌 = 8

消費者 特性이 無店鋪 販賣채널 選擇에 미치는 影響에 關한 硏究 : 카탈로그, TV 홈쇼핑, 인터넷 쇼핑몰의 상호비교를 통하여

학위논문(석사)--서울대학교 대학원 :경영학과 경영학전공,2001.Maste

Genocytotoxicity of metal oxide nanoparticles(CuO, Al2O3, CuAl2O4) in A549 cells

학위논문 (석사)-- 서울대학교 대학원 : 보건학과(보건학전공), 2012. 2. 정해원.최근 나노 기술의 발달로 나노물질의 응용범위가 급속히 확산되고 있다. 나노물질의 사용범위가 다양해질수록 나노물질의 인체 노출가능성은 높아지게 되므로 많은 나노물질의 독성 및 인체 유해성에 대해 많은 연구가 진행되고 있다. 나노산화구리나 나노산화알루미늄 또한 동물독성연구, 세포독성연구 등의 활발한 독성연구가 이루어 지고 있다. 하지만 근래에는 두 가지 이상의 나노크기의 산화금속물질들을 합성 재조합하여 만든 나노크기의 혼합산화금속물질이 많이 사용이 되고 있지만, 그 독성 연구에 대해서는 매우 부족한 실정이다. 나노혼합산화금속물질의 한 종류인 나노산화구리알루미늄은 나노산화구리와 나노산화알루미늄의 합성 재조합물질로서 반도체공정이나 투명전자분야에서 많이 사용되고 있지만, 독성연구는 전무한 상태이다. 따라서 본 연구는 나노산화구리알루미늄의 세포수준에서의 독성을 나노산화구리알루미늄을 구성하고 있는 나노산화구리와 나노산화알루미늄을 함께 세포수준에서 독성 평가를 하였다. 본 연구에서는 나노산화구리알루미늄의 세포수준에서의 독성을 그 구성물질인 나노산화구리, 나노산화알루미늄과 함께 평가하였다. 세포수준에서의 독성은 MTT assay와 Trypan blue assay를 통하여 세포생존률을 관찰하였고, Comet assay를 통하여 DNA 손상을 확인하였으며, Flow cytometry를 이용하여 활성산소종 발생수준을 확인하였다. 나노산화구리는 세포생존률이 급격히 감소하였고, 나노산화알루미늄의 세포독성은 미미한 것으로 나타났다. 나노산화구리알루미늄의 세포독성은 같은 농도에서 나노산화구리보다 작고 나노산화알루미늄 보다 크게 나타났다. 또한 DNA 손상과 활성산소종 발생수준에서도 비슷한 양상으로 나노산화구리는 DNA손상과 활성산소종의 발생이 급격히 증가하였고, 나노산화알루미늄의 DNA손상과 활성산소종 발생수준은 같은농도에서 나노산화구리 보다 낮았고, 나노산화알루미늄보다 높았다. 결론적으로, 나노산화구리, 나노산화알루미늄, 나노산화구리알루미늄은 DNA손상과 활성산소종을 유발함으로서 세포생존률을 감소시킴을 확인하였다.Recently, growing nanotechnology industry leads to concerns about unknown health effects of nanoparticles in humans. Metal and metal oxide nanomaterials are used in skin care products, abrasives, and polishers. However, the toxicity of these nanoparticles is not fully understood. The purpose of this study is to assess the toxicity of three kinds of metal oxide nanoparticles (CuO, Al2O3, and CuAl2O4). To evaluate cell death induced by the metal oxide nanoparticles, we performed MTT assay in the carcinomic human lung epithelial cell line (A549). We examined the genotoxic effects of the nanoparticles in A549 cells using alkaline single cell gel electrophoresis (Comet) assay. The level of reactive oxygen species (ROS) generation induced by the metal oxide nanoparticles in A549 cells was determined by flow cytometry using the fluorescent dye, 2', 7-dichlorofluorescin diacetate (DCF-DA). Dose-dependent decrease in cell survival was observed after treatment of CuO, Al2O3 and CuAl2O4. Dose-response trend in the nanoparticles induced DNA damage could be seen in A549 cells treated with CuO, Al2O3, and CuAl2O4. The relative levels of intracellular ROS induced by nanoparticles treatment were significantly augmented. DCF fluorescence intensity in the 50㎍/㎖ of CuO, Al2O3, and CuAl2O4 treated cells was increased by 441, 176 and 235 %, respectively, as compared to the control group. Taken together, CuO, Al2O3, and CuAl2O4 nanoparticles induced DNA damage and generation of intracellular ROS, eventually, triggering the cell death.Maste

A Study on Stability in Amorphous-InGaZnO Thin Film Transistors for Display Application

DoctorIn display industry, amorphous Indium-Galium-Zinc-Oxide (a-IGZO) thin film transistors (TFTs) are very promising device because of their good uniformity, transparency, low cost and high electron mobility compared to a-Si:H TFTs, which is main device in display industry. However, in spite of these advantages, a-IGZO TFTs have many reliability issues related to bias stress, illumination stress, current stress, ambient stress and temperature stress. In this thesis, among these problems, bias stress, illumination stress, current stress and moisture stress would be treated. Furthermore, I use capacitance voltage (C V) measurement and technology computer aided design tool (TCAD) simulation tool from Silvaco Cop. This doctoral dissertation is divided to two parts. Firstly, bias stress and illumination stress will be dealt with by experiment of drain bias illumination stress (DBIS). Second, analyzing the results of negative bias stress after H2O soaking stress, I will treat the topic related to reliability of moisture stress. In the first DBIS part, when drain bias stress (+40 V) is applied on a-IGZO TFTs with white LED 5000 lux, two step degradation occurred: ‘on’ current (ION) drop and re elevation. Firstly, ION dropped to 35% of its original value and mobility decreased from 11.8 cm2/(V∙s) to 3.0 cm2/(V∙s) because of acceptor-like tail states (ATAIL), which are generated by breakage of weak oxygen bonds near drain region; hot carriers are generated by the strong electric field near drain region, then these hot carriers break weak oxygen bonds near drain region. The ATAIL trap electrons, and therefore ATAIL are negatively charged when energy level of ATAIL < Fermi level. The negatively charged ATAIL cause scattering of charged carriers and decrease in FE. As DBIS time elapsed, generation of ATAIL are saturated and ionized oxygen vacancies (VO2+) are consistently generated near the drain region, so ION is re elevated to 1.57 times as high as its dropped value (i.e., to 55% of its initial value); FE increased from 3.0 cm2/(V∙s) to 6.9 cm2/(V∙s) (i.e., to 59% of its origin value);. These compensation effects between ATAIL and VO2+ happened when ATAIL and VO2+ exist in the same place, so generation of VO2+ near drain region are the main cause of the re-elevation. The mechanism of ION drop and re elevation is identified by C V measurements and Silvaco TCAD simulation. Second, I observed abnormal threshold voltage (VT) shift in a-IGZO TFTs under negative gate bias stress (NBS) after soaking them in H2O (pH 8). During application of NBS, VT decreased by -0.43 V, then increased to nearly the initial value. I hypothesize that the electrical field that is applied during NBS causes some dissociation of H2O to hydrogen ions (H+) and hydroxide ions (OH ); the effects between H+ and OH- are responsible for the abnormal changes of VT. The initial decrease is a result of trapping of H+ at the front channel; the subsequent increase is caused by neutralization of the H+ and the OH-, if the a IGZO is very thin, so the front channel and the back channel could affect each other. Therefore, neutralization of energy band bending is possible. Recovery also occurs in two phases: VT first increases then decreases to its initial value. During the recovery process, accumulation of an OH- layer generates a negatively charged field that attracts H+ so that the two species recombined. Increase in VT occurs due to desorption of H+ from the front channel interface, and decrease in VT occurs by recombination

A Study on Reliability of Amorphous Indium-Gallium-Zinc-Oxide Thin Film Transistors

MasterWe investigated the effects of positive bias temperature stress (PBTS) and positive bias illumination temperature stress (PBITS) and negative bias temperature stress (NBTS) and negative bias illumination temperature stress on the transfer characteristic of amorphous InGaZnO (a-IGZO) TFTs depending on channel width. Gate voltage stress V¬st 20 V or -20 V was applied at chuck temperature of 60, 90 or 120 °C while drain and source were grounded. Channel widths were 30, 50, 200 and 1000 m, and channel length was 4.5 m. For measurements, gate voltage was swept from -20 to +20 V at a fixed drain voltage of 0.1 V for stress durations of 100, 200, 400, 103, 2 × 103, 4 × 103 s. Positive Vst and high temperature induced positive shifts in I-V characteristics in PBTS and PBITS. The main mechanism of PBTS and PBITS is trapping mechanism because subthreshold slope was maintained at 60°C. However, as width increased, the effect of other factors could influence the VT shift. Negative Vst and high temperature induced negative shifts in I-V characteristics in NBTS and NBITS. The main mechanism of NBTS and NBITS was defect creation because subthreshold slope degradation occurred. This phenomenon is because illumination made trap-charge states on the channel/insulator interface and most charge states were electrically positive such as Vo+ and V+2. Channel width dependency was found in PBTS and PBITS. I think this is because probability of trapping increased as channel width increases. We proposed an instability mechanism based on trapping and defect generation. This mechanism will be useful to improve technology of a-IGZO TFTs