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산소의 첨가가 박막 백금측온저항체의 온도저항계수에 미치는 영향
설철규,김영진,장경훈,이건환,이정희 경북대학교 센서기술연구소 1997 센서技術學術大會論文集 Vol.8 No.1
A thin film Pt-RTD(resistance temperature device) was fabricated by using DC magnetron sputtering and laser patterning. A study was fulfilled to adjust the TCR(temperature coefficient of resistance) to 3850 ppm/℃ which is IEC751 standard and the influence of oxygen addition(0 ~ 20 %) on TCR was measured. The resistance of Pt-RTD was set to 1000 Q at 0 ℃ using laser patterning and trimming. The analyses of XRD and AES were used to characterise the platinum thin film. The TCR of Pt-RTD was measured by a high precision oil bath. When the addition of oxygen flow rate was 1 %, TCR was 3850 ppm/℃.
소아에서의 Nd : YAG Laser를 이용한 치은착색제거술 YAG Laser in children
모경희,박헌동,박종휘,김효석,정현구,설재헌,이병채 조선대학교 구강생물학연구소 2003 口腔生物學硏究 Vol.27 No.1
Melanin is normally found in the skin of all people, and normal pigmentation of the intraoral tissues is a relative frequent finding. Gingival hyperpigmentation may cause esthetic problems and embarrassment, especially in patients with a gummy smile. Melanin pigmentation is related to etiologic factor such as hormon, systemic factor, drug, smoking and gingival inflamation. Depigmentation procedure can be Performed by gingival epithelium removing procedure, gingivectomy, free gingival graft, laser therapy, dry ice, Vitamin C and phenol-alcohol method. We could obtain favorable esthetic results by procedures such as Nd: YAG laser. The Nd:YAG laser was set at 4 watt, 50mJ, 80 pulse per second. The procedures were performed with contact mode in all pigmented areas by using a handpiece with a 320㎛ diameter fiber optic. Ablation of the gingival hyperpigmented gingiva appeared healthy, pink, and firm. No recurrence of hyperpigmentation had been found in 6 months of follow-up.
열공형과 비열공형 피질하 혈관성 치매에서 위험인자의 차이에 관한 비교 연구
배희준,정지향,유경호,나덕렬,김상윤,최경규,양동원,손의주,이상도,김재우,박경원,김응규,이재홍,박미영,한일우,함동석,최문성,하충건,최성혜,이애영,이병철,한설희 대한치매학회 2003 Dementia and Neurocognitive Disorders Vol.2 No.2
Backgrounds and Objectives: Vascular dementia is a group of dementing disoders arising from various stroke syndrome. Among these. subcortical ischemic vascular dementia (SIVD) is regarded as a relatively distinct clinical entity. However, MRI patterns of SIVD are not homogenous. In some patients, lacunes are dominant, and in others, subcortical white matter changes are. This study was designed to compare risk factor profiles between SIVD with and without multiple lacunes. Methods: We divided 47 subjects (22 males, mean age. 68 years) recruited from VADAPET (Multicenter Trial For Evaluation Of The Changes In the PET Images Of Subcortical Vascular Dementia Patient) study into two groups one with more than 5 lacunes in deep gray matter (lacune group) and the other with 5 or less(non-lacune group) Clinical characteristics and laboratory findings of two groups were compared. Results: Nineteen of 47 patients (40%) belonged to the lacune group. The lacune and non-lacune groups d d not differ in the following variables: age, hypertension, diabetes mellitus, hyperlipidemia heart disease, history of stroke or TIA, history of trauma or major surgery, family history of hypertension stroke, or dementia, age at diagnosis of dementia, body mass index, white blood cell count, ESR, CRP, fibrinogen, hemoglobin A1C, total cholesterol. LDL cholesterol creatinine, proteinuria, glucosuria, and microhematuria. However, male sex, smoking alcohol. hemoglobin, and HDL cholesterol were possibly associated more with lacune group SIVD than with non-lacune group (p<0 1) Multivariate analyses revealed that smoking, hemoglobin, and HDL cholesterol were independent predictors of SIVD with multiple lacunes Conclusion: Our study suggests that SIVD with multiple lacunes may be significantly different in smoking habits hemoglobin, and HDL cholesterol from SIVD without multiple lacunes.
배동화,설효정,이희경,김형일 대한치과기재학회 1999 대한치과재료학회지 Vol.26 No.1
The hardening behavior and phase transformation process of a dental high carat gold alloy by isothermal ageing treatment were investigated by means of hardness testing, X-ray diffraction study and scanning electron microscopic observations. The following results were obtained. The a single phase with a face centered cubic structure was finally transformed into the coexistence of the Ag-rich α₁phase with a face centered cubic structure and the AuCu I' type ordered phase with a face centered tetragonal superlattice structure by ageing of the solution-treated specimen at 400℃ and 500℃. By ageing at 500℃, the metastable Ag-rich α₁' and AuCu I' type ordered phases were formed prior to the final formation of the equilibrium Ag-rich α₁ and AuCu I type ordered phases . The hardening effect was more significant and the overageing with softening was slower by ageing at 400℃ than 500℃. By ageing at 500℃, the hardening was attributed to the formation of the metastable AuCu I' type ordered phases from the a phase, the overageing with softening was due to the formation of the AuCu I type ordered phase from the metastable Ag-rich α₁' and AuCu I' type ordered phases. By ageing at 500℃, the incubation period which limited the beginning of the hardening in the early stage of ageing existed, and the formation and growth of the precipitates which contributed the overageing with softening were observed concurrently at the grain boundaries and within grains. By ageing at 400℃, the hardening was attributed to the formation of the AuCu I type ordered phase from the a phase, the overageing with softening was due to the growth of the grain boundary precipitates of the lamellar structure composed of the Ag-rich α₁and AuCu I type ordered phases into the grain interior.
(AgCu)_0.43-Au_0.54Pd_0.03 합금의 시효경화 특성
배동화,설효정,이희경,김형일,김교한 대한치과기재학회 2001 대한치과재료학회지 Vol.28 No.3
팔라디움이 함유된, 시효경화성 치과주조용 고금합금의 연구를 위한 기초자료를 얻기 위하여, 4원계 □ 합금의 등온시효경화 거동과 상변태를 경도 시험, X선회절 실험으로 조사하여, 다음과 같은 결과를 얻었다. 본 합금을 250~350℃에서 등온시효처리하면, 면심정방구조를 갖는 준안정상 AuCu Ⅰ'형 규칙상이 면심정방구조를 갖는 AuCu Ⅰ형 규칙상과 면심입방구조를 갖는 Ag-rich a₁상이 생성되기 전에 생성되었다. 본 합금은 시효처리 온도에 따라 다른 시효경화 거동을 보여주었다. 350℃에서 시효처리를 하면, 경도는 시효 초기에 상승하지 않았고, 최고 경도에 도달하여 유지되고나서 시효시간을 연장함에 따라 경도가 급격히 저하하였다. 250℃에서 시효처리를 하면, 경도는 시효 초기부터 뚜렷히 상승하기 시작하였다. 그 후, 약간의 경도 하강을 보이고나서 경도는 다시 서서히 상승을 지속하였다. 350℃에서 경화는 준안정상 AuCu Ⅰ'형 규칙상의 균일핵생성에 기인하였다. 낮은 시효온도에서의 초기 경화는 다른 상변태에 의해 초래되었고, 이어서 일어나는 경화는 준안정상 AuCu Ⅰ'형 규칙상의 생성에 기인하였다. 시효시간을 연장함에 따라 생기는 과시효 연화는 평형상 AuCu Ⅰ형 규칙상의 생성에 기인하는 것으로 생각된다.
치과주조용 Ag-Pd-Zn-Sn-In 합금의 시효경화 특성
이재호,김명진,이희경,김형일,설효정 大韓齒科器材學會 2004 대한치과재료학회지 Vol.31 No.1
Cu가 첨가되어 있지 않고, 대신에 상대적으로 많은 양의 Zn 그리고 소량의 Sn과 In이 첨가된 치과주조용 Ag-Pd-Zn-Sn-In 합금의 시효경화 특성을 경도 시험, X선회절 실험, 주사전자현미경 관찰, 전자탐침 미소분석법으로 조사하여, 다음과 같은 결과를 얻었다. 1. 950℃에서 용체화처리된 시편을 500℃와 550℃에서 등온시효처리하면, 시효 초기에 경도가 완만히 상승하여 최고 경도에 도달하였고 최고 경도를 일정 기간 유지하고 나서 서서히 하강하였다. 2. 용체화처리된 시편은 Pd 원자가 고용된 Ag-rich α1상, Pd3Sn인 α2상, Pd2Zn인 α3상의 3상 공존이었고, 등온시효처리함에 따라 Ag-rich α1상에서 Pd-rich 상으로 추정되는 β상이 석출하였다. 3. 시효 초기의 경화는 Ag-rich 기지에서 Pd-rich 상의 석출로 인한 격자변형에 기인하는 것으로 추정된다. 4. 시효처리 시간을 연장함에 따른 과시효 연화는 입계에 Ag-rich α1상과 Pd-rich β상으로 된 층상조직의 석출과 조대화에 기인하였다. 5. Pd3Sn인 α2상과 Pd2Zn인 α3상은 시효경화에 기여하지 않았다. Age-hardening characteristics of a dental casting Ag-Pd-Zn-Sn-In alloy without copper (52.0 wt% Ag - 39.9 wt% Pd - 4.0 wt% Zn - 2.0 wt% Sn - 2.0 wt% In - 0.1 wt% Ir) was investigated by means of hardness test, X-ray diffraction study, scanning electron microscopic observations and electron probe microanalysis. The specimen solution-treated at 950℃ was three phases of the Ag-rich α1 phase containing Pd element, the α2 phase based on Pd3Sn and the α3 phase based on Pd2Zn, and the Pd-rich β phase was precipitated from the Ag-rich α1 phase by the isothermal ageing,. The initial hardening seemed to be attributed to coherency strains which were formed in the Ag-rich matrix by the precipitation of Pd-rich phase. Overageing with softening was due to the formation and coarsening of the lamella precipitates at grain boundaries, which were composed of the Ag-rich α1 and Pd-rich β phases. The α2 phase based on Pd3Sn and the α3 phase based on Pd2Zn did not contribute to the age-hardening of this alloy.