(BiNa)_(0.5)TiO₃ 세라믹스의 미세구조 및 전기적 성질에 미치는 La₂O₃의 영향

이재성,이계송 경남대학교 신소재연구소 1993 論文集 Vol.3 No.-

(BiNa)_(0.5)TiO₃ 세라믹에 La₂O₃를 1∼7㏖%까지 첨가했을 때 미세구조와 유전 및 압전성에 미치는 영향을 연구하였다. 1150℃에서 소결함으로써 ∼95% 이상의 치밀한 소결체를 얻었고, La₂O₃를 첨가함에 따라 입경은 3㎛에서 0.7㎛까지 감소하였다. 3㏖%첨가시 부터는 침상 및 판상 모양의 결정립이 표면에서 관찰되었는데 이는 내부로부터 스며나온 액상의 고화와 재결정화에 관련이 잇는 것으로 생각된다. 큐리온도에서 유전상수는 1㎒의 경우 3657에서 873으로 La₂O₃가 증가함에 따라서 감소하는 경향을 보였다. 이것은 입경과 유전율의 관점에서보면 정유전율을 갖는 입계부피가 증가해서 전체적으로 유전율이 감소한 것으로 생각된다. 상전이 온도는 첨가량이 3㏖% 되기까지는 증가하다가 그 이상 첨가시에는 특별한 경향성을 조이비 않았다. 3㏖% 이상 첨가의 경우 분극이 어려워서 자료를 얻을 수 없었지만 BNT-0L BNT-1L을 비교면, 각각 압전상수(e_(33))는 65pC/N 43pC/N이고, 전기기계결합계수(k_(p))는 0.139와 0.104였으며, 그리고 가계적품질계수(Q_(m))는 227과 111의 값을 보였다. The effects of La₂O₃addition ranging up to 7mol% on the microstructure, dielectric and piezoelectric properties of the (BiNa)_{05}TiO₃[BNT] ceramics have been inestigated. Sintering at about 1150 C gave rise to dense samples of -95% relative density and grain size decreased from 3μm to 0.7μm with La₂O₃addition. At above 3mol% addition, needle-shaped and plate- like grains were observed on the specimen surfaces. This is considered to be related to the solidification and recrystallization of the liquid phase excluded from the interior. Dielectric constant at Curie temperature decreased from 3657 to 873 at 1 MHz with La₂O₃addition. This was considered to be related to the increase in grain boundary area having low dielectric constant. Phase transition temperature increased until 3mol% addition but above that there was no clear tendency. Comparison of the data between BNT-OL and BNT- 1L was as follows. Piezoelectric constant(d_{33}) was 65pC/N vs 43pc/N, electromechanical coupling factor(k_{p}) 0.139 vs 0.104, and mechanical quality factor(Q_{m}) 217 vs 111, respectively.

전기도금한 교정용 스테인레스스틸 선재의 세포독성에 관한 연구

이계형,황현식,이옥,성영은 전남대학교 치의학연구소 2003 구강과학 Vol.15 No.1

The purpose of this study was to evaluate the possible clinical application through examining the cytotoxicity of orthodontic wire, which was increased diameter using electroplating. First, nickel plating was done on the commercially available stainless steel wire using a electroplating technique. And for the comparison electroplated wire with ready made stainless steel wire and titanium or copper. each wire was incubates for 72 hours on the medium. The release of the metal ion was measured using ICP-AES. The incubated medium was diluted 75%, 50%, 25% and added on the microplate each with Balb/c 373 mouse fibroblast for MTT analysis and compared with medium only. Through the measuring of the change in absorbency value of each wire group and the difference of absorbency value according to change of dilution, following results were obtained. 1. The results of ICP-AES analysis showed that lots of nickel ions were isolated from electroplated orthodontic wires and lots of copper ions were isolated from copper. 2. The inverted microscope showed that numbers of cells were decreased at the electroplated wire and copper. 3. The results of MTT analysis showed that there was no difference of the absorbency value of titanium at any dilution. 4. The results of MTT analysis showed that the absorbency values of the electroplated wires were lower than those of medium only at all dilutions, and showed statistically significant differences(p<0.001). 5. The results of MTT analysis showed that the absorbency value of the stainless steel wires were lower than those of medium only at all dilutions, and showed statistically significant differences(p<0.05). 6. The results of MTT analysis showed that the absorbency value of the copper were lower than those of medium only at all dilutions, and showed statistically significant differences(p<0.001). 7. Assessment as per ISO 10993, part 5, titanium and stainless steel wire investigated corresponded to "non-cytotoxic". Whereas copper was "highly cytotoxic", electroplated wire was alloted to "moderate cytotoxic". The results of this study indicate that the electroplated orthodontic wires need additional efforts in order to decrease cytotoxicity for their clinical applications.

오메푸라졸 함유 직장좌제의 제제설계

이창현,황성주,오세종,이계주 충남대학교 약학대학 의약품개발연구소 1993 藥學論文集 Vol.9 No.-

In order for formulation of rectal containing OMZ, the OMZ suppositories were prepared using water-soluble base, PEG 4000 base and oil-soluble base, Witepsol H 15. Chemical stability of OMZ in suppositories was increased when Witepsol H 15 was used as a suppository base and arginine was added as a stabilizer. The decomposition of OMZ in suppository bases followed the first-order kinetics and their rate constants were 0.11 day^-1(t_1/2 = /6.25 days) for Witepsol H 15 suppository and 0.48 day^-1(t_1/2=/1.43 days) for PEG 4000 suppository, respectively. On the other hand, the decomposition rate constants of Witepsol suppository and PEG suppository stabilized with arginine were 3.89×10 exp(-3)(t_1/2=171.1 days) and 8.76×10 exp(-3) day^-1(t_1/2=79.9 days), respectively. Shelf-lives of the Witepsol and PEG suppositories stabilized with arginine were t_90% = 291.8 days and t_90% = 282.1 days at 35℃ and 75% RH, respectively. The dissolution test of OMZ suppositories was performed by rotating dialysis cell(RDC) method and the release rate constant was calculated by the simplified Higuchi's equation, Q'=K't^1/2. Dissolution of OMZ from suppositories was augmented as arginine was added, particle size of OMZ was reduced and a suitable surfactant such as SLS was added. RDC method was more appropriate and available than Paddle method to evaluate the dissolution rate of lipophilic-base suppositoies. Arginine was found to be a very useful exipient for the enhancement of stability and dissolution of OMZ in suppositories.

오메프라졸제제의 최근 동향

이기명,황성주,이계주 충남대학교 약학대학 의약품개발연구소 1993 藥學論文集 Vol.9 No.-

오메프라졸 함유 직장좌제의 약물속도론적 연구

이창현,황성주,권광일,이계주 충남대학교 약학대학 의약품개발연구소 1993 藥學論文集 Vol.9 No.-

The pharmacokinetics and relationship between in vitro dissolution and in vivo fraction absorbed were investigated after intravenous(iv) injection of omeprazole(OMZ), oral administration of OMZ capsules and rectal administration of 8 types of suppositories. The plasma concentration of OMZ (C_p)-time (t) curve after iv. administration fitted a two-compartment open model and the equation which best fitted the pharmacokinetics of OMZ was C_p=13.936 e^-8.78t+2.973 e^-0.716t. The bioavailabilities of OMZ in Witepsol H15 base (Supp-2) and PEG 4000 base (Supp-6) suppositories were 40.7% and 33.4%, respectively, which are higher(p<0.001) than 13% of oral administration of capsule. The avoidance fractions of the first-pass metabolism for Supp-2 and Supp-6 suppositiories were 31.8% and 23.4%, respectively, suggesting that the rectal application of OMZ may be a more adequate route of adminstration than oral one.

운동형태가 골밀도에 미치는 영향

이계영,김성수 대한스포츠의학회 1995 대한스포츠의학회지 Vol.13 No.1

The objective of present study was evaluate the influence of physical activity on bone mineral density in young men. Included in the study were 21 athletes who participated in a full-scale physical exercise program. The control group consisted of 7 healthy men of the same age distribution. The athletes were classified into three categories; baseball players, gymnastic players, swimmers. On the basis of the results of Dual Energy X-ray Absorptiometry, bone mineral content of each body region, total bone calcium content and bone mineral density were analyzed. The results statistically analyzed on these data were summarized as follows; 1. Arms and spine ribs bone mineral density in gymnastic players were significantly higher that in baseball players, swimmers and non-athletes. 2. Legs and pelvis bone mineral density in baseball players were significantly higher than in non-athletes. 3. Lumbar and total bone mineral density in gymnastic players, baseballplayers were significantly higher that in non-athletes. 4. Legs, ribs, pelvis, spine, lumbar and total bone mineral density in swimmers showed no significant difference from non-athletes.

순시 공진 전압 합성형 DC-DC 컨버터에 관한 연구

이상호,이봉섭,정도영,황계호,남승식,노채균 嶺南大學校 工業技術硏究所 1998 工業技術硏究所論文集 Vol.26 No.2

This paper describes a DC-DC converter connected two unit inverters, a half-bridge high frequency resonant inverters, at the input with parallel. It estimated characteristics such as the average power, the average output voltage etc, for the design of the device with the normalized parameter values. Also, This paper confirms a rightfulness of circuit analysis by comparing a simulation and experimental results of proposal converter. The proposed paper certified that the theoretical waveforms are equal to the experimental waveforms. In the future, it is expected that proposal converter can be applicated for the system of fixed DCvoltage source.

당밀의 첨가가 갈근탕박 사일리지의 품질과 산양의 기호성에 미치는 영향

김성복,문계봉,이봉덕,오홍록,배형철,이수기 충남대학교 농업과학연구소 2006 농업과학연구 Vol.33 No.1

Two experiments were conducted to investigate the effects of molasses supplementation to silage materials in ensiling Galgeuntang (herbal medicine) meal on the quality of silage, and its palatability in Korean native goats. In experiment Ⅰ, molasses was added at the levels of 0, 0.5, and 1.0% to Galgeuntang meal with three replicates per treatment. In experiment Ⅱ, three 1.5-yr-old Korean native goats were used to measure palatability. In experiment Ⅰ, lactic acid contents in molasses treatments were significantly(p<0.05) higher, and pH and butyric acid contents were lower than those of non-molasses treatment. In addition, molasses treatment increased total microbial cell counts in MRS medium for lactobacillus, but decreased total microbial cell counts in PDA medium for fungi. Molasses supplementation to silage materials increased in vitro dry matter disappearance. Molasses supplementation tended to increase silage intake in Korean native goat (experiment Ⅱ), but the difference was not significant(p>0.05). It is concluded that molasses supplementation to silage materials in ensiling herbal medicine meal could improve its preservability and palatability, the higher the better.

컴퓨터 정보시스템 교육용 멀티미디어 시스템 개발

이계성 단국대학교 1998 論文集 Vol.33 No.-

In this paper, we investigate the changes in the education through computers and benefits of new technologies brought into education from internet and multimedia applications. We propose the application of agent technologies to building student models which during the interactions guide the student with appropriate learning materials selected with respect to student’s behavior and performance. A system design is also proposed with an integration of interne technologies and intelligent tutoring system technologies, as well as multimedia tools. The system partially installed with the subject of computer information systems.

장애 유·아동의 자기 관리 행동 중재 연구

박계신,이상복 대구대학교 특수교육재활과학연구소 2000 특수교육재활과학연구 Vol.39 No.2

장애 유·아동은 중재를 통해 변화된 행동을 지도자가 없는 상황에서 자발적으로 수행하고, 일반화하는 것에 어려움을 나타낸다. 이러한 결과는 장애 유·아동을 가르치는 교사나 그들을 양육하는 부모에게 지속적인 부담감을 주는 것이며, 나아가 장애 유·아동의 교육적 통합 및 사회적 통합을 저해하는 것이다. 따라서 장애 유·아동이 새로이 습득한 행동을 자발적으로 수행하고 다양한 상황에 적용할 수 있는 능력을 증진시킬 수 있는 중재 방법이 절실히 필요하다. 자기 관리 행동 중재는 주축 반응(pivotal response)적인 특성을 지니고 있기 때문에, 장애 유·아동들이 새로이 습득한 행동을 독립적으로 수행하며, 아울러 다양한 상황에 일반화하는데 효과적으로 사용될 수 있는 방법이다. 본 연구에서는 선행 연구와 관련 문헌을 통하여 자기 관리 행동 중재의 특성 및 효과에 대해 살펴보았고, 아울러 보다 효과적인 자기 관리 행동 중재 방법의 실현을 위한 발전적인 대안을 제시하였다. Self-management is a technique that facilitates independence by systematically fading reliance in external control to the child. Self-management has been effective at improving a variety of behaviors, including appropriate vocational, academic, social, and recreational skills. In addition, self-management procedure appear to have indirect effects on other nontargeted behaviors such as reducing disruptive behavior and increasing motivation to learn, thus resulting in extremely widespread and effective intervention gains. The development of intervention programs with these effects is very important because in order for infants and children with severe disabilities to approximate the knowledge of their peers, or even learn the necessary skills required by society to live independent lives, they will need to engage in interventions that accelerate learning and promote generalization. In turn, a more active involvement with the environment has the potential to improve neurological development, autonomy, and functional independence and therefore results in positive overall lifestyle changes. Finally, it is expected that when infants and children with disabilities are able to function independently and their life styles are improved, stress on parents, teachers, and other concerned individuals will decrease. In this article I made some suggestions for future researches on self-management intervention for infants and children with disabilities.