Reconstruction of Rabbit Corneal Epithelium on Lyophilized Amniotic Membrane Using the Tilting Dynamic Culture Method

Ahn, Jae-Il,Lee, Doo-Hoon,Ryu, Yang-Hwan,Jang, In-Keun,Yoon, Mun-Young,Shin, Youn Ho,Seo, Young-Kwon,Yoon, Hee-Hoon,Kim, Jae-Chan,Song, Kye-Yong,Yang, Eun-Kyung,Kim, Ki-Ho,Park, Jung-Keug Blackwell Publishing Inc 2007 Artificial Organs Vol.31 No.9

<P>Abstract: </P><P>Rabbit corneal epithelium was reconstructed using tilting dynamic culture with a self-manufactured, amniotic membrane (AM) supporter and a lyophilized amniotic membrane (LAM). Rabbit corneal epithelial (RCE) cells were cultured and cryopreserved after isolation from the limbus. The second- and third-passage RCE cells were plated onto the epithelial side of the LAM of Ahn's AM supporter. Two days later, the air–liquid interface culture was maintained with third-passage RCE cells for 6 days and second-passage corneal epithelial cells for 9 days. The average viability of thawed RCE cells, assessed using trypan blue dye exclusion, was 77.42%. The reconstructed corneal epithelium was characterized by histological (hematoxylin and eosin) and immunohistochemical staining (proliferating cell nuclear antigen) for light microscopy, and by reverse transcriptase-polymerase chain reaction, glucose assay, and transmission electron microscopy. The basal layer of the reconstructed corneal epithelium was well formed, and the epithelium was tightly constructed due to the increase in cell proliferation and differentiation caused by the tilting dynamic culture, as opposed to static culture. Tilting dynamic culture was useful for the reconstruction of the epithelium using easily damaged epithelial cells and resulted in more stratum cell layers. Moreover, cytokeratin (CK3) mRNA expression in tilting dynamic cultured third-passage RCE cells seeded onto AM was greater than in static cultured third-passage RCE cells. The morphology of the reconstructed corneal epithelium on LAM by tilting dynamic culture for 9 days resembled that of the skin epidermis. This was thought to be because the tilting dynamic culture not only accelerated the proliferation and differentiation of cells by physical or mechanical stimulation, but also ensured that the supply of medium was delivered to the basal cells more efficiently. Thus, the reconstruction of the corneal epithelium using LAM and tilting dynamic culture was considered to be a good in vitro model for autologous or allogeneic transplantation of corneal epithelium and skin epidermis in patients with damaged epithelia. </P>

Ecological characteristics of areas naturally inhabited by Dolbae trees(Pyrus pyrifolia) on Mt. Kaya

Ahn, Young-Hee,Chung, Kyu Hwan 한국환경과학회 2002 한국환경과학회지 Vol.11 No.11

The ecological characteristics of Dolbae trees, a valuable genetic resource for native Pyrus fruit trees, were investigated at four naturally inhabited areas on Mount Kaya, Gyeongsangnam-Do. Most Dolbae trees were found on the southwest side of an old hiking path to a mountain valley at altitudes of 610~670 m. The surrounding flora consisted of 46 families, 69 genera, 75 species, and 10 varieties. The natural habitat of the Dolbae trees was basically a deciduous broad-leaved forest with a predominance of Quercus serrata and ligneous plants(xylophytes) from the Fagaceae and Betulaceae families. The habitat was also found to be in a second transition resulting from forest disturbance and exhibited a degree of diversity of 2.901-5.065, based on Shannon-Weiner's index. Examination of the Dolbae trees found in Mount Kaya revealed diameter breast heights(DBHs) ranging from 10 to 60 cm, including six old and large Dolbae trees with a DBH of 50~60 cm, which will be particularly valuable as a genetic resource. Accordingly, the current results suggest that the study areas are a secondary forest in a typical mid-temperate zone resulting from forest damage about 10 years earlier.

컴퓨터 게임에 대한 학부모·교사·학생간의 인식의 차이에 관한 연구 : 부산광역시 중학교 남학생을 중심으로

안성진,김영환,정지언 부산대학교 과학교육연구소 2007 교사교육연구 Vol.46 No.1

본 연구의 목적은 컴퓨터 게임에 대한 청소년과 그들의 교사, 학부모의 인식을 조사하여 각 집단별 인식 간에 차이가 있는지, 있다면 어떤 영역에서 가장 큰 차이를 보이는 지를 알아보는 것이다. 이를 위해 남자 중학생 297명, 이들의 교사 124명, 학부모 278명을 표집하여 컴퓨터 게임시의 자기 통제력에 대한 인식, 컴퓨터 게임이 학습활동, 교우관계, 부모님과의 관계, 자아존중감, 건강에 미치는 영향에 대한 각 집단별 인식의 차이를 분석하였다. 연구결과를 보면, 중학생들은 대체적으로 컴퓨터게임에 대해 긍정적으로 인식하고 있었다. 컴퓨터 게임은 스트레스 해소를 위해 가장 필요하고, 성적에는 별로 영향을 주지 않는 것으로 인식하고 있었지만 교우관계에는 부정적 영향을 주는 것으로 보고 있었다. 교사들은 대체적으로 컴퓨터 게임이 중학생들에게 부정적으로 작용한다고 보고 있었다. 특히 게임에 대한 자제력 부족으로 성적에 부정적인 영향을 줄 것이고 이로 인해 학부모들과 갈등이 초래될 것으로 인식하고 있었다. 부모들은 대체적으로 교사보다는 긍정적으로, 그러나 학생보다는 다소 부정적으로 컴퓨터게임에 대해 인식하고 있었다. 교사들은 컴퓨터게임이 학생과 학부모의 관계형성에 부정적일 것으로 보고 있었으나 실제 학생과 학부모들은 그렇지 않은 것으로 나타났다 Generally, the middle school students play the computer games in their spare times or for pleasure. But, their parents and teachers emphasize on the negative effect of the computer games and restrict the students to play the games. This difference comes from different standpoints on the computer games among parents, teachers, and students. In this context, this study aims at investigating the different views of the computer games among parents, teachers, and students. Regarding a view of the computer games, this thesis puts it as being influenced by the conditions of the self-control on playing the computer games, the students' associates, the relations between the students and their parents, the self-respect, and the health. According to the results, the middle school students play the computer games in forty three percent of their leisure times for pleasure and getting rid of stress. In addition, they can not find an alternative but the computer games in their spare times. As to the difference of the views on the computer games, the middle school students and the parents are positive but the teachers are not. The students are the most positive of the computer games. In particular, they take the affirmative to the self-control on playing the computer games and the effect on their health, but regard the computer games as keeping bad company. The teachers have the most negative assertion toward the computer games. Mostly, except the students' associates and self-respect, the teachers do not agree to the computer games to bring positive effect on the students. Comparatively, the parents are positive of the computer games but less than the students are. They believe that the computer games have the positive effect on the self-control on playing the computer games and the students' health. Nevertheless, they make an negative assertion in relations to the learning and the students' associates. Therefore, this study is able to form a conclusion that it might be needed for the parents and teachers who have the negative attitude toward the computer games to put themselves in the position of the students to find the positive effects of the computer games and suggest appropriate guidelines for the students as maximizing positive effects of the computer games.

공기 양정(air lift) 펌프를 응용한 슬러지 배출장치에 대한 연구

안갑환,박영식 한국환경과학회 2004 한국환경과학회지 Vol.13 No.10

Sludge discharger applied the principle of the air lift pump was investigated experimentally for the different design(diameter of discharge pipe, diameter and height of the inside and outside wall) and operating parameters(air flow rate, water level). And it was conducted that performance comparison about sludge discharger and conventional air lift pump. The result indicated that discharged liquid were increased with the increase of air flow rate and water level and decrease distance between inside and outside wall. The discharge pressure was increased with an increase of air flow rate and a decrease of the diameter of the discharge pipe, for both the sludge discharger and the airlift pump. The discharge pressures of the sludge discharger were 3-6 times higher than those of the air lift pump.

공무원의 리더십유형과 조직시민행동에 관한 연구 : 충북지역 지방자치단체를 중심으로

안관영,곽영환 한국품질경영학회 1998 품질경영학회지 Vol.26 No.3

Many empiricalresearch surveys have supported that Organizational Citizenship Behavior(OCB) is influnced by or closely related with leadership styles. The primary purpose is to test the moderating effects of structural factors (formalization, centralization) and personal factors(growth needs, sex, age, tenure, rank, occupation, school career) between 2 leadership styles and 2 OCB factors. For the analytical purpose of this article, Fisher's Z-transformation and SGC(split groups correlations) methods were introduced. Generally 2 leadership styles are found to influence on altruism and conscientiousness respectively. Out of 36 cases, only 2 cases were significant in moderating effects. Based on empirical results, there is no moderating effects in conscientiousness. But altruism is found to more closely related with employee-centered leadership in low centralized group than in high centralized group, and more closely related with job-centered leadership in low growth-needs group than in high growth-needs group.

웹문서의 텍스트 제시 유형에 따른 독해력의 비교

안영식,김영환,문창민 한국교육정보미디어학회 2003 교육정보미디어연구 Vol.9 No.3

학습의 기본적인 활동인 '읽기(Reading)'는 최근 인터넷의 확산으로 웹문서를 통해서 이루어지는 경우가 많다. 하지만 웹문서는 매우 다양하기 때문에 어떠한 웹문서가 '읽기'에 가장 적합한가를 고려해볼 필요가 있다. 따라서 본 연구는 웹문서에 따라 학습의 기본 능력인 '읽기'가 어떻게 다른가를 살펴봄으로써 '읽기'에 효과적인 웹문서 디자인의 지침을 제공하고자 한다. 먼저 다양한 웹문서를 유형화하기 위해 텍스트 위주로 운영되는 30개의 웹문서를 조사하여 웹문서 유형을 결정짓는 변인을 줄 길이와 글자 크기, 화면 밀도로 정하였고 이 변인들을 조합하여 9개의 웹문서 유형을 만들었다. 그 후 9개의 유형에 따라 독해력(Readability) 검사를 실시하여 '읽기'에 어떤 차이가 나는지 알아보았다. 연구를 통해서 웹문서(15인치 기준)에 있는 텍스트의 줄 길이와 글자 크기간에 독해력에 대한 교호작용은 일단 없는 것으로 나타났다. 텍스트의 줄 길이만을 변인으로 하였을 때, 17∼18cm, 21∼22cm, 26∼27cm 중 가장 짧은 17∼18cm에서의 독해력 점수가 가장 높았다. 텍스트의 글자 크기는 9p, 10p, 12p 중 어떤 크기를 사용하더라도 독해력에는 관계가 없었다. 화면 밀도는 기존의 분류를 바탕으로 16%이하(저밀도), 16∼32%(중), 32% 이상(고)으로 나누어 독해력을 알아본 결과 중밀도에서 가장 독해력이 높았다. This study was aimed to find the correlation between web-text presentation patterns and readability. The investigation into several variables determining web-text presentation patterns was made. Of several variables, line length and font size were major variables. Line length as the first variable could be classified into three types(17.4cm, 21.3cm, 26.4cm) and font size as the second variable could be classified into three types(9p, 10p, 12p). The 9 web-text presentation patterns were made by 3(1st variable)×3(2nd variable). CRT density was added as the third variable and was applied to the 9 web-text. How these three variables influence the readablity was found by Two-way ANOVA. Reading result test and reading process test went abreast to measure the readablity influenced by these three variables. Major findings from this study were as follows. 1. There was no interaction effect between line length and font size in web-text. It meaned that any combinations of specific line length with specific font size in web-tex could not influence improving readability. 2. Readability improved when the line length in web-text was 17∼18cm(17.4cm as average). It meaned that designing line length in web-text to be 60∼64% could enhance readablity. 3. Any font size among 9p, 10p, 12p could not influence improving readability. 4. When the level of web-text density in web-text was presented in moderate density, significant result was produced statistically. Moderate density means 16.0%∼ 32%(26.6%∼28.0% in this study) of a full web-text. A ccording to the results of this study, it is suggested that to design line length to be 60∼64% in full width of web-text and to design density to be 16.0%∼32%(26.6%∼ 28.0% in this study) can enhance readablity in web-text.

高周波 運續 熱處理한 PC 鐵線의 腐蝕機構

安英敏,吳應煥,黃龍吉 동아대학교 공과대학 부설 한국자원개발연구소 1989 硏究報告 Vol.13 No.1

This study has been carried out to investigated into corrosion of PC steel wires, heat-treated AISI1022 and AISI10B32 at set temperature by high frequency induction continuation heat-treatment, that was deposited in city water, seawater, 0.75% H₂SO₄ solution and NH₄SCN aqueous solution for the 20days.

외상성 횡격막 손상

안성국,이상목,이기형,고석환,김용호,박호철,고영관,조규석 대한응급의학회 1995 대한응급의학회지 Vol.6 No.1

Fifty two cases of traumatic diaphragmatic injuries that we have experienced from Jan. 1973 to Oct. 1994 were evaluated. The following results were obtained. The age of the patient was ranged from 1 to 74 years. Male was 38 and female was 14 in number with a ratio of 2.7 : 1. The traumatic diaphragmatic injuries were due to blunt trauma in 35 cases(motor vehicle accident 25, fall down 8, press 1, kick by fight 1) and penetrating trauma in 17 cases(stab wound 15, shot wound 1, explosion 1). In the blunt trauma, the preoperative diagnosis of the diaphragmatic injury was possible in 25 out of 35 cases(71%) and in the penetrating trauma, 15 out of 17 cases(88%). In the blunt trauma, the repture site was located in the left in 22 cases(63%) and in the right in 13 cases(31%). In the penetrating trauma, the rupture site was located in the left in 9 cases(53%) and in the right in 8 cases(47%). In the blunt trauma, 20 cases(63%) were treated within 24 hours and in the penetrating, 15 cases(88%) within 24 hours. In the blunt trauma, the herniated organs into the thorax were stomach(7), omentum(6), spleen(6), liver(5), colon(4), small bowel(2) and in the penetrating, stomach(7), colon(6), omentum(3), liver(2), and spleen(1) were herniated. Injury severity score(ISS) of 35-blunt trauma ranged from 11 to 66 with mean value of 30.6. Mean ISS of survivors and nonsurvivors was 27.6 and 52.7 respectively. The diaphragmatic repair of 49 cases was performed with thoracic approach in 23 cases, thoracoabdominal approach in 7 cases and abdominal approach in 19 cases, and 3 cases were not operated. The postoperative complication and mortality were developed in 16 out of 49 cases(33%) and in 5 cases(9.6%) respectively, and the causes of death were hypovolemic shock(1), combined head injury(2), asphyxia(1), and pulomnary edema and renal failure(1). In conclusion, the injuries of the diaphragm should be suspected in all patients with severe blunt trauma or penetrating injuries at thorax and upper abdominal area near the diaphragm. All of the cases had associated injury and most of deaths were related to the severity of associated injuries.

1990년대 평생교육 정책에 관한 고찰

안병환,이영호 대진대학교 1998 大眞論叢 Vol.6 No.-

This study analyzes the policy of Lifelong education in 1990's. Especially, in order to explore the direction of policy, it is focused on the problems of bachelor's degree examination for the self-educated, credit account system. In addition, it is examined difference between social education act and life-long education act, and the major cotents of life-long education act in order to suggest the orientation of life-long education policy.

월쉬변환에 의한 시지연계의 간단화 모델링 및 최적제어에 관한 연구

안두수,오민환,채영무 成均館大學校 科學技術硏究所 1992 論文集 Vol.43 No.1

시지연계를 지연이 없는 선형계로 모델링 할 경우에는 고차 방정식으로 표현되기 때문에 실제로 제어하기는 어렵다. 본 연구에서는 시지연요소를 직접 처리하지 않고 지연이 없는 형식을 이용하여 모델을 간략화 시키므로서 시지연계의 최적제어를 간단히 할 수 있도록 하였다. It is difficult to analyze time delay system because the system is commonly expressed by high order equations. To avoid the difficulty, the undelayed linear formulations have been used. However, it is time consuming to directly analyze the undelayed linear formulations in case of complicated system. In this paper, to prevent disadvantage of time consuming, a proper solution technique having advantage of time saving is used to solve the system.