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粉體의 燒結擧動에 영향을 주는 인자는 많으나 그중에서 原料粉末의 특성은 매우 중요하다. 본 연구에서는 α-Fe_(2)O_(3)粉末의 특성이 燒結擧動에 미치는 영향을 구명하고자,針狀 및 球狀의 α-Fe_(2)O_(3)粉末을 제조하고 그 특성을 조사하였으며 이들 粉末의 粒子形態와 成形特性 및 燒結特性과의 상관관계를 검토하였다. 脫水溫度가 증가함에 따라 針狀의 α-Fe_(2)O_(3) 粒子形態는 붕괴되어 球狀으로 바뀌며 α-Fe_(2)O_(3)粉未粒子내의 氣孔은 소별되고 一次粒子가 급격히 성장하여 粒子 比表面續이 크게 감소하였다. 針狀粉末 成戒形體내의 氣孔의 양은 球狀粉末의 成形體 보다 많았고 氣孔의 크기는 작았으며, 針狀粉末은 球狀粉末보다 成形密度는 낮았으나 대체적으로 燒結密度는 높았다. α-Fe_(2)O_(3)粉末의 緻密化 擧動은 成形體의 氣孔構造에 의해 영향을 받았다. 燒結溫度가 900℃에서 1,000℃로 증가함에 따라 針狀 α-Fe_(2)O_(3) 粉未 燒結體의 密度는 球狀의 경우보다 큰 변화율로 증가하였고 그 이후의 溫度에서는 반대로 球狀粉末 燒結體의 密度 변화율이 크게 나타났다. 부피 收縮率은 針狀 α-Fe_(2)O_(3)粉未의 燒結體가 球狀의 경우보다 크게 나타났다. 燒結溫度 1,100℃이상에서 針狀粉求의 燒結體는 氣孔이 粒界에 존재하였고 球狀粉求은 粒子內部와 粒界에 존재하였다. Among many factors of influencing to sintering behavior, the characterization of powder of a starting material plays very important role to the sintering behavior. In this study, acicular and spherical α-Fe_(2)O_(3) powder were prepared, and studied their properties and the effects of their green characteristics on the properties of sintered body. With increase in dehydration temperature the specific surface area of α-Fe_(2)O_(3) particle was largely decreased due to the changes in skeleton particles, acicular particle was collapsed and turned into spherical, the micropores were vanished, and the primary particles were rapidly grown. The interparticle pore of acicular powder compacts showed larger in amount, smaller in size and wider in pore size distribution than spherical one. The acicular powder had relatively low green density but high sintered density than the spherical powder. The densification behavior of α-Fe_(2)O_(3) powder was attributed to the pore configuration in the green compacts. The sintered density of acicular α-Fe_(2)O_(3) powder was largely increased, faster than that of spherical one, with firing temperature from 900℃ to 1,000℃, but the rate of density increase for spherical powder became larger than for the acicular powder above 1,000℃. The volume shrinkage in sintered α-Fe_(2)O_(3) of acicular powder was larger than that of spherical one. Above 1,100℃ of firing temperature, intergranular pores in the sintered body of acicular powder were dehydrated at 300℃, both intergranular and intragranular pores were in the sintered body of spherical powder dehydrated at 800℃.
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상기 논문은 국제경제합작의 개념을 기본 이론화하고 동북아 경제합작의 목 적, 방법, 향후 전망을 통하여 두만강 지역개발 사업의 현황, 개발, 모식 및 대책을 논의하고 두만강 지역개발 사업이 한·중 (韓·中)경제합작에 미치는 영향을 심층 분석하였다. 구체적인 결론은 다음과 같다. 첫째, 국제 경제합작은 생산 요소의 이동과 재배치를 통하여 지역 경제발전 을 촉진시키고, 지역화 및 세계경제 글로벌화에 직접 영향을 미친다. 둘째, 동북아 지역경제합작의 필요성이 점층 증대되고 있다. 동북아 경제 합작의 모식은 국제협업형 모식인 두만강 지역개발 사업이 최우선적 으로 개발되는 것이 바람직하다. 셋째, 두만강 지역개발 사업의 개발 모식으로는 "성장 삼각"이론에 입각하 여 두만강 경제지역 (TREZ) 특구성질의 다국 경제합작지역을 건설한 후 두만강 경제개발지역 (TREDA) 내 주요 도시의 중심성을 강화시키 는 모식이 바람직하다. 또한 동북아지역 국제관계의 복잡성과 각국 의 이익이 첨예하게 대립되고 있는 현실적 상황에서 동 사업을 원활 하게 추진하기 위해서는 단계적 (3단계)으로 나누어 추진하는 것이 효율적이다. 넷째, 두만강 지역개발 사업이 한·중(韓·中)경제합작발전에 있어 지역개 발, 물류 교통, 경제 방면에 지대한 영향을 미친다. 지역경제합작 관점에서 볼때, 자원이용의 효율성 제고와 양국 경제발전을 증진시키 며 사회안전에 기여할 수 있다. 구체적으로 중국 동북지역개발을 촉진시켜 동북현상 (東北現象)을 타파하여 투자환경을 개선할 수 있다. 한국 동해안 지역개발을 촉진시켜 국토의 균형 적인 발전을 꾀하고 21세기 동북아 물류 중심국가로 발전할 수 있는 토대를 마련할 수 있다. This dissertation is to develop a new culture theory and its typology which can be useful both for national culture studies and for comparative culture studies. The focus in theory and typology development is on the role of cultural syntaxes which connect all the different cultural biases, or subcultures, within a society into a meaningful whole, a societal culture. The thesis of this study is that, since subcultures within a society are interconnected, they function together, and that the patterns of interconnectedness among subcultures determine conflicts potential among them. To develop my own version of typology, I use Mary Douglas culture typology which divides a societal culture into five different subcultures -hierarchy, egalitarianism, individualism, fatalism, and hermitude. The typology is applied to a typical collectivistic society, the Korean dynastic society (1392-1910), to describe its cultural characteristics and to discuss its social and political stability. The main argument in the application part of the study is that, among members of the society, hierarchical and egalitarian preferences were interconnected to each other, and that the interconnectedness between the two collectivistic subcultures was the secret of the dynastic stability.
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심부전 환자의 심근 수축력과 혈중 단핵 백혈구의 βARK1 발현에 대한 연구
Background: Cardiac responsiveness of contractility is modulated by the βARK1(beta-adrenergic receptor kinase 1) activiy and the increased level of βARK1 of the myocardium in heart failure is responsible for depressed cardiac function. But the relationship between cardiac responsiveness and the βARK1 level of peripheral mononuclear leukocytes(MNL) is uncertain. The study was designed to clarify the role of the βARK1 in MNL for the cardiac contractility. Methods: Seventeen congestive heart failure patients and ten control people were subjected to this study. Symptomatic heart failure patients who had EF(Ejection Fraction) less than 45% and did not take β-blocker were included. GBP(Gated Blood Pool) scan was performed at rest (GBPrest) and after dobutamine infusion (10 μg/kg/min) for fifteen minutes (GBPdobu). And the difference between GBPrest and GBPdobu was calculated (ΔGBP) to estimate the responsiveness of myocardial contractility. Before beginning of GBPrest, patients were laid calmly over thirty minutes and their peripheral bloods were collected. MNLs were separated by Ficol gradient centrifuge and total RNA was isolated. For competitive RT-PCR(Reverse Transcription-Polymerase Chain Reaction), internal control was generated by deleting 135 bp from human βARK1 cDNA. Primers were used to get a 645 bp PCR product. The amount of expressed mRNA was estimated with standard curve. Results: EF measured by GBPrest was much lower in heart failure than control (32%±10 vs. 65%±9). Basal heart rate and NE(Norepinephrine) level were similar in two groups. The amount of mRNA of βARK1 in MNL was not different in two group. Myocardial contractile responsiveness expressed by ΔGBP was not correlated with the level of βARK1 expression of MNL in all study subjects, but well inversely correlated in only heart failure group. Conclusion: These findings suggest that the level of βARK1 expression of peripheral MNL may reflect the state of myocardial desensitization to adrenergic system and implys that the new role of the βARK1 of MNL in evaluation of heart failure.
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