陸軍航空 操從士의 動機賦與에 관한 硏究 : F. Herzberg의 二要因理論을 中心으로

이기환 建國大學校 1990 국내석사

배양액의 종류가 생쥐 난포난자의 체외성숙 및 체외수정에 미치는영향

이기환 충남대학교 1990 국내박사

Murine immature oocytes were cultured in vitro in Ham's F-10, MEM, or WM solution with or without either FCS or BSA supplement. The effect on maturation and fertilization of the immature oocytes was evaluated. Also the effect of FCS on maturation of cumulus, zona pellucidae, or oocyte was evaluated. The results obtained were as follows 1. Fewer eggs were fertilized when Ham's F-10, MEM or WM solution without FCS or BSA supplement. 2. Addition of FCS (10%, v/v) to Ham's F-10 or MEM solution increased fertilization of mouse oocytes matured in vitro as well as that of ovulated oocytes (control) 3. Addition of BSA (5-20 mg/ml) to Ham's F-10 or MEM solution failed to increase fertilization of mouse oocytes matured in vitro. 4. Addition of FCS or BSA to solution failed to increase fertilization of mouse oocytes matured in vitro. 5. Addition of FCS to Ham's F-10 solution increased fertilization of mouse oocytes matured in vitro. 5. Addition of FCS to Ham's F-10 solution increased fertilization of mouse oocytes matured in vitro with the increase in the concentration of FCS. 6. Addition of FCS to Ham's JF-10 medium for oocyte maturation improved cumulus expansion, incidence of sperm penetration through zona pellucidae, shortened the time of enzymatic dissolution of the zona pellucidae, formation of the male pronucleus and resumption of meiosis. These results suggest that FCS is found necessary for in vitro maturation and fertilization of mouse immature oocytes and it also improved the maturation of cumulus, zona pellucidae, oocyte's cytoplasm and oocyte's nucleus.

나리류 養液裁培時 培地種類 및 養液濃度가 球根肥大와 切花品質에 미치는 影響

李基煥 공주대학교 산업개발대학원 1998 국내석사

다량원소의 시비농도가 오리엔탈 백합 'Casa Blanca'의 생장 및 무기원소 흡수에 미치는 영향

이기환 배재대학교 대학원 2003 국내박사

CA 125항원의 임상적 연구

이기환 忠南大學校 大學院 1986 국내석사

CA 125 is antigenic determinant associated with human epithelial ovarian carcinomas. It was reported that 82% was positive in epithelial ovarian cancer and rising or falling level of CA 125 was correlated with progression or regression of disease in 90%. However, recently reports revealed that CA 125 was not specific for the epithelial ovarian cancer. Thus this study was performed to evaluate the serum level of CA 125 in 78 cases of benign or malignant gynecologic and nongynecologic tumors. The following results were obtained. 1. Among 26 cases of benign ovarian tumor, including 14 cases of dermoid cyst, 4 cases of serous cyst, 2 cases of mucinous cyst, 1 case of fibroma, 3 cases of follicular cyst, and 2 cases of corpus luteum cyst, 1 case (3.8%) was positive for CA 125 antigen. 2. Among 5 cases of benign gynecological tumor other than ovarian tumor, including 1 case of parovarian cyst, 2 cases of carcinoma in situ, cervix, and 2 cases of myoma uteri, 1 case (10%) was positive for CA l25 antigen. 3. Among 10 cases of preganancy related conditions, including 5 cases of first trimestar pregnancy, 4 cases of ectopic pregnancy, and 1 case of partial mole, 1 case (10%) was positive for CA 125 antigen. 4. Among 11 cases of gynecological malignancy other than ovarian cancer, including 1 case of leiomyosarcoma, 1 case of hemangiopericytoma, 6 cases of squamous cell carcinoma, cervix, 1 case of adenocarcinoma, cervix, 1 case of adenocarcinoma, endometrium, and 1 case of malignant mixed mullerian tumor, 2 cases (18.1%) were positive for CA 125 antigen. 5. Among 10 cases of nongynecological malignancy, including 4 cases of stomach cancer, 3 cases of sigmoid cancer, 1 case of rectal cancer, and 2 cases of leukemia, 1 case (10%) was positive for CA 125 antigen. 6. Among 3 cases of nenepithelial ovarian cancer, including 1 case of dysgerminoma, 1 case of endodermal sinus tumor, and 1 case of granulosa cell tumor, 1 case (33.3%) was positive for CA 125 antigen. 7. Among 13 cases of epithelial ovarian cancer, 9 cases (69.2%) were positive for CA 125 antigen. This study suggest that CA l25 is high positive rate in epithelial ovarian cancer. However, other diseases must be excluded when CA 125 is used as a diagnostic or monitoring method in woman with epithelial ovarian cancer.

정보환경과 기업가치가 기관투자자의 소유지분율에 미치는 영향에 관한 연구

이기환 경기대학교 2005 국내박사

본 연구는 IMF이후 우리나라 자본시장에서 정보환경이 기관투자자의 소유지분비율에 미치는 영향과 기관투자자의 소유지분비율이 기업가치에 미치는 영향에 대하여 분석하였다. 기존의 연구들에 의하면 자본시장에서 정보중개자로서의 재무분석가의 예측정확성은 정보환경의 질적인 대용치로 재무분석가의 수는 정보환경의 양적인 대용치로 인식하고 있으므로 본 연구에서도 정보환경의 대용치로써 재무분석가의 예측정확성과 재무분석가의 수의 개념을 도입하였다. 기관투자자의 투자의사결정에 미치는 정보환경의 요인들을 일반회귀모형과 2단계 연립방정식 모형을 모두 사용하여 기관투자자와 재무분석가 두 시장참여자의 의사결정 간의 내생적(endogenous) 관계를 밝혀내고자 하였다. 또한 기관투자자의 소유지분비율의 증가가 경영자에 대한 감시역할의 증대로 인하여 기업가치의 증가의 결과로 나타났는지를 검정하였다. 기업가치의 대용치로는 Tobin's Q를 사용하였다. 분석결과에 따르면 기관투자자의 소유지분율이 높으면 재무분석가의 예측정확성은 높고 재무분석가의 수 역시 증가함을 보였다. 그러나 재무분석가의 예측정확성은 기관투자자의 투자의사결정에 영향을 미치지 못하였으며, 재무분석가의 수는 기관투자자의 소유지분비율과 유의한 양(+)의 관계를 보였다. 이로써 기관투자자 들은 투자의사결정 시에 정보환경의 대용치로 재무분석가의 예측정확성보다는 재무분석가의 수를 우선적으로 고려함을 알 수 있었다. 그리고 기관투자자의 소유지분비율이 높으면 기업가치가 크다는 결과를 보였다. 기관투자자의 역할이 중요시되고 있는 현 시점에서 국내 기관투자자의 소유지분 비율에 영향을 미치는 시장에서의 요인(재무분석가의 기업이익예측, 재무분석가의 수)에 대하여 분석하고 기업가치와의 관계를 고찰하는 본 연구는 시의 적절하며 향후 기관투자자를 육성하는 데 바람직한 근거자료를 제공할 것으로 본다. The purpose of this study is to analyze 1) the effect of the availability of information in the capital market on the level of institutional ownership in listed companies and 2) the impact of institutional ownership level of listed companies on the corporate value of those companies. To quantify so-called "availability of information," 1) the accuracy of financial analysts' forecasts and 2) the number of financial analysts were employed as surrogates of the qualitative and quantitative aspects of information, respectively. The object of this study is to find the endogenous relationship between two market participants' - financial analysts and institutional investors - decision making process, by applying both general regression model and two stage simultaneous equations model. The study also examines that increases in institutional investors' holding share result in increase of companies' value by enhancing supervision on management. Tobin's Q was employed as substitution for company value. The result indicated that high portion of institutional ownership increased both the accuracy of financial analysts' forecasts and the number of financial analysts. Although the accuracy of financial analysts' forecasts did not turn out to have affected the investment decision making of institutional investors, the number of financial analysts turned out to have a significantly positive relationship with the level of institutional ownership. The findings proved that institutional investors consider the number of financial analysts as a substitution for information availability rather than the accuracy of financial analysts' forecast. This study found out that companies' value tends to increase as institutional ownership level of companies increase. The findings of this study out of analyzing market factors, which have significant effect on the level of domestic institutional ownership in companies such as financial analysts' earnings forecast of companies and the number of financial analysts, and the relationship between the level of institutional ownership in companies and the value of corporations could possibly offer a compelling evidence of the importance of fostering institutional investors in the future at a time when the importance of the role of institutional investors is on the rise.

한국형발사체를 기반으로 한 확장-굴절(E-D) 로켓 노즐의 설계 변수 특성 연구

이기환 忠南大學校 大學院 2020 국내석사

In this study, numerical and experimental studies are performed to investigate the characteristics of Expansion-Deflection(E-D) nozzle according to the design parameters. The parameter study is performed numerically to investigate the effect of the design variables of the E-D nozzle on nozzle performance. The E-D nozzle is designed based on the Korean Space Launch Vehicle(KSLV-II) by selecting the pintle inflection angle and the pintle radius as the main variables. The grid sensitivity analysis is performed to select the optimal grid and then the numerical analysis is performed. As a result, as the pintle inflection angle of the E-D nozzle design variables decreased, the flow separation at the nozzle tip occurred first and the thrust performance of a model with a larger angle of pintle inflection is shown higher. In addition, the larger the pintle radius, the better thrust performance is confirmed. These results are the same as those of the previous research. Through this study, it is confirmed that the thrust performance of the E-D nozzle can be improved by adjusting the pintle inflection angle and pintle radius. After studying the pintle design parameters, eight models are designed to analyze the nozzle length reduction effect of E-D nozzle. Five models reduced nozzle length by 10% based on the ED1017 model, and three nozzles adjusted the overall design parameters. Numerical results showed that the best thrust performance was achieved when the nozzle length was reduced by 10-12%, and the longer length reduction reduced the thrust performance due to the under-expansion effect. And it is confirmed that the weight reduction of up to 30 kg can be obtained by calculating the weight of the E-D nozzle. After the numerical study, an experimental study of the E-D nozzle is performed. The experimental system of the previous study is improved and the surface post-processing of the E-D nozzle made with the metal 3D printer is carried out. After surface post-processing, the E-D nozzle eliminated disturbances in the flow field and improved thrust performance. As a result, the model with the larger pintle inflection angle showed higher thrust performance than the small model. At this time, the measurement uncertainty is calculated and the thrust is shown at 95% reliability. And the experimental results are compared with the numerical results of previous studies to confirm the usefulness of numerical analysis in closed wake.

연극과 영화의 상호 수용 : 핀터의 『배신』과『프랑스 중위의 여자』

이기환 계명대학교 교육대학원 2001 국내석사

수온 스트레스 대응 빨강해면맨드라미 유생의 초기 발생 및 차등 유전자 발현 연구

이기환 우석대학교 일반대학원 2023 국내석사

급격하게 변화하고 있는 기후변화에 해양생태계가 위협받고 있다. 산호는 이러한 해양생태계에서 다른 해양생물들의 은신처, 먹이, 번식을 위한 장소 제공 등 중요한 역할을 한다. 이와 관련하여 국내 서식하고 있는 산호류들에 대한 보존에 필요한 기초 연구가 미진하며, 산호의 초기 발생 단계인 유생과 관련된 연구는 더 미흡하다. 본 연구는 국내 서식종인 빨강해면맨드라미(Chromonephthea hirotai) 유생을 대상으로 특정 온도 구간의 수온 스트레스에 7일간 배양하여 생존율을 분석하였으며, 대조군 21°C 와 실험군 26°, 28°C에 1일간 수온 스트레스에 노출시킨 유생을 대상으로 차등 발현 유전자(DEGs) 분석을 진행하였다. 생존율 분석은 빨강해면맨드라미의 생식시기인 7월과 8월 실제 해수 온도를 기반으로 수온 스트레스 조건을 20°C-29°C로 설정하였다. 20°C-22°C 수온에서 7일간 배양한 유생 생존율은 90% 이상이였으며, 23°C와 24°C의 생존율은 약 80-70%, 25°C는 55%, 26°C 이상의 수온에서는 생존율이 50% 미만으로 나타났다. 배양 7일 기준 유생 생존율이 50% 이하가 되는 수온인 26°C와 28°C를 조건으로 빨강해면맨드라미 유생 50마리로부터 RNA를 추출하였다. 대조군 21°C와 실험군 26°C, 28°C의 조건별 각 RNA 시료 2개를 만들었으며, 만들어진 RNA는 RNA sequencing과 de novo assembly를 통해 차등 발현 유전자(Differentially Expressed Genes) 분석을 진행하였다. 공통으로 나타난 DEG를 제거한 전체 DEG 수는 16,169개였으며, 21°C 대 26°C는 2,450개, 21°C 대 28°C는 14,518개가 나타났다. 각 데이터베이스별 1개 이상 annotation된 DEG는 총 10,444개였다. 21°C 대 26°C에서 annotation 된 고유 DEG는 653개였으며, 21°C 대 28°C에서 annotation 된 고유 DEG는 7,971개였다. 두 집단에서 공통으로 나온 DEG는 1,820개였다. 그 중 수온 스트레스에 의해 발현되는 열충격단백질(heat shock protein, Hsp)와 면역과 관련된 유전자 발현을 중점으로 확인하였다. Hsp의 경우 21°C 대 26°C에서 hsp-16.1/hsp-16.11는 9.68배, 21°C 대 28°C에서 hsp-16.1/hsp-16.11는 103.72배 발현되었으며, 면역과 관련된 렉틴과 세포 사멸을 막아주는 여러 유전자가 발현됨을 알 수 있었다. 본 연구를 통해 급격하게 일어나는 기후변화로 인한 해수온 상승으로부터 빨강해면맨드라미 유생은 26°C 이상의 수온에서 높은 사망률과 열충격단백질 및 면역 관련 유전자 발현량이 높게 발현하는 것으로 밝혀졌다. The marine ecosystem is threatened by a rapidly changing climate. Coral plays an important role in the marine ecosystem. It provides shelter, food, and place for reproduction of other marine life. In this regard, basic studies on preservation of coral living in Korea are insufficient. Studies on larvae, the initial stage of occurrence of coral, are even more insufficient. This study analyzed survival rates by incubating Chromonephthea hirotai larvae, a domestic habitat, under water temperature stress in a specific temperature section for 7 days and analyzed differentially expressed genes (DEGs) for those exposed to water temperature stress for 1 day in the control group at 21°C and experimental groups at 26°C and 28°C. In the survival rate analysis, the water temperature stress condition was set at 20°C-29°C based on the actual seawater temperature in July and August, the reproductive time of Chromonephthea hirotai. The survival rate of larvae cultured at 20°C-22°C for 7 days was 90% or higher. The survival rate at 23°C and 24°C was about 80-70%. It was 55% at 25°C. However, at water temperatures above 26°C, the survival rate was less than 50%. RNA was extracted from 50 Chromonephthea hirotai larvae under conditions of 26°C and 28°C, which were water temperatures with a survival rate of 50% or less as of the 7th day of culture. Two RNA samples were prepared for each condition of the control group at 21°C and experimental groups at 26°C and 28°C. Differentially expressed genes were analyzed through RNA sequencing and de novo assembly. The total number of DEGs from which duplicate values were removed was 16,169 (2,450 at 21°C vs. 26°C and 14,518 at 21°C vs. 28°C). A total of 10,444 DEGs were annotated (at least one for each database). There were 653 unique DEGs annotated at 21°C vs. 26°C, and 7,971 unique DEGs annotated at 21°C vs. 28°C. In both groups, 1,820 DEGs were duplicated. Among them, heat shock protein (Hsp) expressed by water temperature stress and immune-related gene expression were identified as the focus. In the case of Hsp, hsp-16.1/hsp-16.11 showed a difference of 9.68 times in the comparison between 21°C and 26°C and hsp-16.1/hsp-16.11 showed a difference of 103.72 times in the comparison of 21°C vs. 28°C. Several genes that could prevent immune-related lectins and apoptosis were found. Through this study, it was found that Chromonephthea hirotai larvae have a high mortality with high thermal shock proteins and immune-related gene expression at water temperatures above 26°C due to rapid increase in sea temperature associated with climate change.

카메라 보정과 자동화상분리를 고려한 단일촬영 화상처리법에 의한 변형률 측정

이기환 建國大學校 大學院 1997 국내석사

To the image processing of 3-D geometry and strain measurement, camera calibrations such as coordinates rotation and translation, lens distortion and image extension are considered for accurate data acquisition. Tsai's model was followed to calibrate camera. Instead of the commonly used double view method single view image processing technique is adopted because the latter is simpler in equipment setup. An image separation algorithm was developed to get 3-D informations automatically from single frame of double images.