가격 경직성과 사회후생

본고는 신축적 가격하에서의 경제, 즉 인플레이션이 왜곡을 유발하지 않고 총생산이 항상 자연산출량 수준을 달성하는 경제가 과연 경직적 가격하에서의 경제보다 사회후생측면에서 항상 더 바람직한지에 대해 논의한다. 특히 금융시장이 불완전하고,부문 간 명목 경직도가 유의하게 다르며, 사회후생 최대화를 목적으로 통화정책이 운영되는 경우, 경직적 가격이 가계 후생에 더 유리하다는 점을 밝힌다. 불완전 금융시장은 소비와 생산의 비효율적인 배분을 초래한다. 통화정책은 명목 경직성 및 불완전금융시장으로 인한 후생손실을 완화할 수 있으나, 이는 경직적 가격하에서의 경제에 서만 유효하다

(The) mechanical, physical and biological safety study of dense calcium phosphate ceramics for the application of dental implant

치의학과/박사[한글] 인체내의 골조직과 치아의 성분에 가장 가깝고 골조직과 연조직간의 친화력이 우수한 생물학적인 치과이식 재료로써 최근에 많은 관심을 갖고 응용되는 Calcium phosphate를 Isostatic press를 이용한 소결법으로 1000℃, 1100℃, 1200℃의 온도에서 각각 소결한 후 Vitallium 침봉을 접착시킨 원주형의 시편을 제작하여 기공율, 부피비중, 상대비중, X-선 회절분석, 압축강도, 전단강도, 미세강도, 전자현미경 소견등의 기계적, 물리적 성질과 HeLa 세포를 이용한 조직배양법으로 생물학적안전성을 관찰하여서 다음과 같은 결론을 얻었다. 1. 1200℃에서 소결한 tricalcium phosphate ceramics는 다른 온도에서보다 높은 기계적 강도를 나타내었다. 2. 소결온도가 상승함에 따라 전체적인 기공율은 감소하나 반대로 기공의 크기는 크게 나타났다. 3. 1200℃에서 소결한 tricalcium Phosphate ceramics의 상대밀도는 96.65%로써 다른 온도에서보다 높게 나타났다. 4. Tricalcium phosphate를 1000℃∼1200℃ 범위에서 소결한 경우 모두 β-whitlockite로 상변태 하였다. 5. Triealcium phosphate ceramics는 소결온도에 상관없이 모두 vitallium과함께 생물학적인 안전성을 보였다. [영문] The calcium phosphate ceramics are bioactive materials for dental implant that resembles those of dental enamel, dentin and bone, which forming tight bond resembles ankylosis with surrounding bone and soft tissue. Dense calcium phosphate ceramics were made of commercially available tricalcium phosphate salts by compression and subsequent sintering at each temperature 1000℃, 1100℃ and 1200℃. Subsequently artificial teeth were made of cylindrical form that consist of a vitallium rod for post & core and a surface of sintered dense calcium phosphate ceramics for interfacing with alveolar bone. In this experimental study, mechanical and physical properties of sintered calcium phosphate ceramics were obtained from measurement of bulk density, relative density, apparent porosity, compressive strength, modulus of rupture strength, vickers hardness, average pore and grain size. The biological safety of these materials was tested from the tissue culture method using HeLa Cells. The results of this study were obtained as follows; 1. Tricalcium phosphate ceramics sintered at temperature 1200℃ exhibited better mechanical strengths. 2. As much as sintering temperature arised, apparent porosity was reduced, but avarage pore size was larged. 3. The relative density of tricalcium phosphate ceramics sintered at 1200℃ was 96.65%. 4. When tricalcium phosphate salts sintered at temperature between 1000℃ and 1200℃, they were transformed to β-whitlockite. 5. Tricalcium phosphate ceramics exhibited biological safety regardless of sintering temperature.restrictio

(An) Experimental histopathologic study of the tissue reaction to non-precious alloys which implanted in and contacted on the oral mucosa

치의학과/석사[한글]치과용 비귀금속 합금의 임상에서의 성공적인 사용을 위해서는 좋은 물리적 성질뿐만 아니라, 조직과의 친화상도 좋아야 할 것이다. 저자는 이러한 치과용 보철물 제작에 Tm이는 수종비귀금속 합금이 구강점막에 미치는 생체반응에 관한 병리조직학적 관찰을 하기 위하여,Ni-Cr합금계, Ag-Pd합금계, 그리고, 제 3형 주조금으로 금속편을 제작하여 한국산 재래종 성견 2마리의 구강점막하에 매식후 10일, 30인, 60일 간격으로, 연결고정 금관을 이용하여, 금속편을 구강점막에 접촉한 후 30일, 60일 간격으로 조직반응을 관찰한 결과 다음과 같은 결론을 얻었다. 1. 구강점막하 매식군 10일에서는 급만성 염증세포의 침윤과 섬유아세포의 증식상을 보였고, 30일 이후에는 이물질로 인한 만성육아종 염증소견을 볼 수 있었다. 2. 구강점막에 접촉군에서는 급만성 염증세포의 침윤을 보였으며, 상피세포의 극세포증과 국소적으로 궤양이 형성된 것을 관찰하였다. 3. 구강점막에 첩촉군에서는 매식군에서 보여주는 생체의 방어기전인 섬유화를 볼 수 없었다. 4. 구강점막하 매식군에서 WASHI A-LOY는 다른 금속에 비해 비교적 경미한 염증반응을 보였으며, Rexillium Ⅲ는 가장 심한 염증반응을 보였다. 5. 구강점막에 접촉군에서는 Ag-Pd합금이 Ni-Cr합금보다 조직손상이 적은 것을 관찰하였다. [영문]This study was undertaken to observe the histopathalogic reaction to non-precious alloys when the alloys were implanted in and contacted on the oral mucosa The alloys used were Nickel Chromo alleys, Silver Palladium alloys and Casting gold Ⅲ tyre alloys. Two dogs of the experiment were decided into implanted and contacted groups. Experiment groups were serially performed under a general anesthesia using Secobarbital Sodium at the fellowing postimplantation time intervals: 10, 30, and 60 days and postcontact time intervals: 30 and 60 days. Under anesthesia, the oral mucosa was dissected out and stained wish Hematoxylin and Eosin. After examination and comparision of all specimens, the results of this study were obtained as follows. 1. In the after 10th days implantation, acute and chronic inflammatory cells were infiltrated ,and fibroblasts were proliferated. After 30th days, chronic granulomatous inflammation as a foreign body reactions was present. 2. The reaction to contacted group, the acanthosis of the epithelial cells and the formation of the localized ulcerations were observed, and acute and chronic inflammatory cells were infiltrated. 3. The contacted group did not show fibrosis considered as a defence mechanism of the host which was seen in implanted group. 4. The reaction to implanted group, WASHI A-LOY showed more mild inflammatory reaction than any other alleys but Rexillium Ⅲ showed the most severe inflammatory reaction. 5. The reaction to contacted group, Silver Palladium alloys induced less tissue damage than Nickel Chrome alloys.restrictio

Enhancement of Signal Reliability through Optimizing Contact Condition of CLECDiS

MasterNanotechnology is said to include varieties of technological researchs such as new fabrication technologies to modeling tools for nano-scale physical phenomena. Among them the utra-precision positioning systems may be one of the main technologies for realizing experimental toolds for nanotechnology. It is also a key technology for fabrication of devices with nano-scale size components in the current industries.In order for upgrading the positioning technology, long-range displacement sensors with ultra-precision might be inevitable because the repeatability of a positioning system usually relies on the displacement sensor adopted in it. The Contact-type Linear Encorder-Like Capacitive Displacement Sensor (CLECDiS) has been developed for this purpose: to provide a compact low-cost urtra-precision long-range displacement sensor.Evern though the resolution of 0.35nm have been proved to be achieved based on the SNR(Signal-to-Noise Ratio) of its detection cuircuitry, it is required to develop the methods to implement the CLECDiS into a positioning system in order to use it stably as the displacement sensor of a system. In this study, the contact conditions of the two facing electrodes of CLECDiS and their effects are evaluated and the methods are proposed and tested to improve their contact conditions. Basically the supporting jigs and stages are redesigned to improbe the contact conditions and the testing results show that improvement in the contact condtions may considerably stabilize the output signals from CLECDiS.In this thesis, as a part of researches on improment of the contact conditions, the repeatability of the output signals is improved about 28 times of the signals obtained from the previous samples. It suggests that the repeatability could be improved enormously because the results presented in this thesis could be obtained just by adopting the new mechanism to control the contact conditions

Drift Compensation Technique of an Area-varying Capacitive Displacement Sensor for Nanometer Resolution

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접촉식 면적변화형 정전용량 변위센서의 접촉 안정성을 위한 기구의 개발

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A technique for drift compensation of an area-varying capacitive displacement sensor for nano-metrology

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