• 한국광학회지
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• 제13권4호
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• pp.275-282
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• 2002

2매 접합렌즈와 단렌즈로 구성된 2군 렌즈계의 구면수차, 코마, 종색수차 보정을 위한 3차수차 전개식을 얇은렌즈 근사를 이용하여 해석적으로 유도하였다. 유도된 3차수차 전개식은 telephoto렌즈계의 설계에 적용되었다. 초기설계에서 광학유리 조합은crown-flint-crown조합과 flint-crown-flint 조합에 관하여 조사하였다. Crown-flint-crown조합의 경우 2가지 형태의 achromatic aplanat 존재하였다. Flint-crown-flint조합의 경우에서도 2종류의 해가 존재하였으나, 해의 형태가 유용하지 못하였다.

• 한국응용과학기술학회지
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• 제22권1호
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• pp.50-55
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• 2005

A comparison of alkali metal cation and alkaline earth cation solvent extraction was made for three additional monoionizable crown ethers and one diionizable crown ether. sym-(n-Octyldibenzo)-16-crown-5-oxyacetic acid $\underline{1}$ exhibited high efficiency and selecvity in solvent extraction of alkali metal cations with respect to that observed with alkaline earth cations. Sizes of $Na^+$ and $Ca^{2+}$ appropriately match with the cavity size of monoethyl sym-bis[4(5)-tert-butylbenzo]-16-crown-5-oxymethylphosphonic acid $\underline{3}$. As the result, $Na^+$ and $Ca^{2+}$ are the best extracted. sym-(n-Octyldibenzo)-16-crown-5-oxymethyldiphosphonic acid $\underline{4}$was found to be somewhat selective for $Na^+$ over $Li^+$ and other alkaline earth metal cations. In the complexation of alklaine earth cations by crown ether diphosphonic acid $\underline{4}$, $Ca^{2+}$ and $Sr^{2+}$ are the appropriate sizes, but lager $Ba^{2+}$ may be due to favorable formation of a sandwich type complex between the crown ether cavity and the dianion of the deprotonated crown ether phoaphonic acid moiety.

• 대한화학회지
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• 제32권1호
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• pp.71-78
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• 1988

20,21,24,25-Tetranitrodibenzo-18-crown-6에 알코올성 염기를 가하여 친핵성 치환반응을 유도하면 crown ether 화합물을 이루는 polyether 고리가 끊어져서 주생성물로 2,4,5-trialkoxynitrobenzene 유도체, 4,5-dialkoxy-1,2-dinitrobenzene 유도체 그리고 crown ether 고리가 부분적으로 끊어져 생긴 bis[(alkoxynitrophenoxy)ethyl]ether 유도체가 부생성물로 얻어졌다. 이가 알코올성 염기에서는 polyether 고리가 끊어진 생성물과 분자내 치환반응이 다시 진행되어 고리축소 현상이 일어나 12-crown-4의 유도체를 얻게 되거나 출발물질이 도로 생성되었다. 이상의 실험은 다양한 알코올의 농도에서 염기의 종류를 달리하여 그 선택성을 알아보았다.

• 대한치과보철학회지
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• 제30권1호
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• pp.103-124
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• 1992

The purpose of this study was to investigate the effect on the fracture strength and color of ceramic by the design of the metal coping in ceramo metal crown. In this study, four types of ceramic crowns were made for fracture strength : standard ceramo metal crown, collariess ceramo metal crown, modified ceramo metal crown, and ceramic jacket crown. And three types of disk formed-specimens were made to compare the dentin shade owing to aluminous opaque powder and palladium alloy. Fracture strength was measured by universal testing machine(Instron Co. Ltd., U.S.A) and color was measured by color and color difference meter(Yasuda Seiki Seisakusho, Ltd., Japan). The results were as follows : 1. The fracture strength of ceramic was affected significantly by the design of metal coping in ceramo metal crown. The mean fracture strength(192.0 Kg) of standard ceramo metal crown was about 1.7 times higher than that(111.5 Kg) of collarless ceramo metal crown, and about 2.8 times higher than that(67.8 Kg) of ceramic jacket crown. 2. Modified ceramo metal crown that has metal band in the labio cervical had the lowest fracture strength. 3. Lightness, yellowness and redness of the dentin fired were decreased by the metal coping.

• 대한치과기공학회지
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• 제29권2호
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• pp.79-85
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• 2007

In this study, We tried to find out the fracture strength of zirconia coping all ceramic crown and collarless porcelain fused gold alloy crown as the compared group. Each of the collarless porcelain fused gold crown and zirconia all ceramic crown has been produced specimen 10 each. And after pasting them on the steel jig, it had load given at porcelain incisal edge by 130$^{\circ}$ and measured fracture strength by Universal Testing Machine and then We have results from that. 1. The average value of fracture strength suggested 950.49 N at collarless porcelain fused gold alloy crown, 656.81 N at zirconia coping all ceramic crown. 2. Fractured pattern showed that the whole of labial part was exposed in collarless porcelain fused gold crown, but porcelain of margin part did not show fracture in advance. In the practice, the concern that collarless might cause fracture strength to be weaken does not matter, we concluded zirconia all ceramic crown made fracture that only a part of labial porcelain was fractured. The combination of zirconia all ceramic crown and turned out to be excellent.

• 대한치과교정학회지
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• 제16권2호
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• pp.123-133
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• 1986

The purpose of this study was to collect the information of the straight-wire appliance and to determine the amount of second-order bends in clinical orthodontics. The author analysed the study model of 50 individuals with normal occlusion and results were obtained as follows. 1. The crown angulation was 4 degree in upper central incisor, 7 degree in upper lateral incisor, and 0 degree in lower central incisor and lateral incisor. 2. The crown angulation was 8 degree in upper cuspid and 2 degree in lower cuspid. 3. The crown angulations were 4 degree in upper first bicuspid, upper second bicuspid and lower second bicuspid and 1 degree in lower first bicuspid. 4. The crown angulation was 3 degree in upper first molar, 0 degree in upper second molar, 5 degree in lower first molar and 8 degree in lower second molar. 5. The crown angulations in lower arch were progressively increased from first premolar to second molar. 6. In upper arch, as the crown angulation of one tooth was increased, those of adjacent teeth were increased, too. 7. In the case of lower arch, the crown angulation of cuspid was increased as that of lateral incisor was increased, the crown angulation of second premolar was increased as that of first premolar was increased, and similarity the crown angulation of second molar was increased as that of first molar was increased.

• 구강회복응용과학지
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• 제31권1호
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• pp.45-49
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• 2015

본 증례는 기존의 국소의치에서 파절된 metal-ceramic surveyed crown을 complete contour zirconia surveyed crown으로 전환하는 간단하고 편리한 CAD/CAM 기술을 보고하고 있다. 항암치료를 받고 있는 환자의 기존 metal-ceramic surveyed crown 외형, 형태학적 특성, 레스트 시트를 complete contour zirconia surveyed crown으로 제작하는 복제 기법에 대해 보고한다.

• 구강회복응용과학지
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• 제18권2호
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• pp.101-111
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• 2002

The purpose of this study was to evaluate the fracture strength of porcelain fused to gold crown and gold electroformed crown according to incisal and incisal under 3mm. In this study, 28 gold electroformed crown and 28 porcelain fused to gold crown were fabricated. Fracture strength testing was carried out using an Instron 8871(Instron Corporation, U.S.A) at a cross head speed of 5mm/min. All of the measurements were statistically analyzed by Independent t-testing, and k-s testing. Statistical significance was set in advance at the probability level of less than 0.05. All measurements were analized with Windows $SPSS^{(R)}$ Version 10.0 software for the personal computer. The results of this study were as follows; 1. Comparison by location (1) A compared fracture strength of incisal and incisal under 3 mm, there was statistical significant difference between gold electro -formed crown and porcelain fused to gold crown (p<0.05). 2. Comparison by loading (1) When compared fracture strength of incisal, there was no significant difference between gold electroformed crown ($619.90{\pm}53.54N$)and porcelain fused to gold crown($674.68{\pm}87.42N$). (2) When compared fracture strength of incisal under 3 mm, there was significant difference between gold electroformed crown($688.29{\pm}14.88N$) and porcelain fused to gold crown($1931.81{\pm}29.64N$) (p<0.05). 3. Mode of fracture When compared of fracture mode, gold electroformed crown showed mode of fracture and fracture line reaching coping region and porcelain fused to gold crown showed only in porcelain region.

• 멤브레인
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• 제6권4호
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• pp.265-272
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• 1996

금속이온 분리를 위한 운반체 지지형 (고분자/운반체) 복합막을 수면전개법에 의하여 제조하였다. 이들 막의 형상은 전개용액의 물성에 의하여 영향을 받는다. (고분자/18-crown-6) 복합용액의 표면장력은 18-crown-6의 농도가 증가함에 따라 감소하는 경향을 나타내며, 고분자에 따른 용액의 표면장력은 PVC>PS>CA 순서로 감소하였다. 점도는 18-crown-6의 농도가 증가함에 따라 PVC계와 PS계 용액은 큰 변화가 없으나 CA계 용액은 감소하는 경향을 나타내었다. 18-crown-6 환형고리분자는 고분자쇄 사이에서 전기적인 완충역할을 하여 고분자쇄간의 분자간력을 약화시켜줌으로써 복합 용액의 전개성을 증가시켰다. 복합박막의 표면형상은 단일박막보다 균일하였으며, 18-crown-6가 증가함에 따라 전후면은 모두 균일한 구조극 나타내었다.

• 한국응용과학기술학회지
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• 제22권3호
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• pp.219-227
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• 2005

Competitive solvent extraction of the mixure of alkali metal and alkaline earth cation from water into organic solvent containing the crown ether carboxylic acid and anlogous crown ether phosphonic acid was investigated as follows. The lipophilic group is found to strongly influence to the selective extraction in the mixed systems from only alkali metal cation for sym-(n-decyldibenzo)-16-crown-5-oxyacetic acid $\underline{1}$ to mostly alkaline earth metal cation for sym-bis[4(5)-tert-butylbenzo]-16-crown-5-oxyacetic acid $\underline{3}$. Monoethyl sym-(n-decyldibenzo)-16-crown-5-oxymethylphosphonic acid $\underline{2}$. and monoethyl-sym- bis]4(5)-tert-butylbenzo]-16-crown-5-oxymethylphosphonic acid $\underline{4}$ showed good selectivity for $Na^+$ over $Mg^{2+}$, the second extracted ion. Structural variation in the crown ether phosphonic acid somewhat was influenced to the extraction selectivity in the mixed systems. when variation of the ionized group is influenced in the mixed systems, the selectivity of $Na^+$ as the second extracted ion was much better crown ether carboxylic acid $\underline{1}$ than crown ether phosphonic acid $\underline{2}$, while the efficiency of $Na^+$ extraction was better $\underline{2}$ (83% total loading) than $\underline{1}$ (32%).