Electron Cyclotron Resonance O_2 Plasma에서 증착한 규소 산화 박막의 특성

안명환,서문석,장재선,서성모,이기방,윤창주,이형재,남기석,최규현,손춘배,김용섭,강석희 全北大學校 基礎科學硏究所 1994 基礎科學 Vol.17 No.-

규소 산화막을 ECR-CVD(electron cyclotron resonance-chemical vapor deposition) 증착방법으로 5인치 기판위에 상온에서 증착하고, 증착공정조건인 증착율, 기판온도, 마이크로파의 세기변화 및 플라즈마 혼합기체의 비에 따른 규소 산화막의 특성을 조사하였다. 또한 산화막의 구조적인 특성을 비교하기 위해 FTIR을 이용하여 ECR-CVD 증착한 산화막, RPE-CVD(remote plasma enhanced-CVD) 증착한 산화막 및 열 산화막의 stretching frequency를 측정하였다. 측정된 결과 ECR-CVD로 증착된 산화막이 구조적인 면에서 열 산화막과 거의 같음을 보였다. ECR-CVD로 증착된 산화막의 전기적인 특성을 전류-전압 및 축전-전압 측정에의하여 분석하였다. 축전된 산화막의 전기적인 특성은 산화막의 전하 밀도는 1×10 exp (11)/㎠이였고, 평균 절연 파괴 전압은 약 6 MV/㎝이다. We have grown thin films of SiO_2 at room temperature by using an ECR-CVD system and have investigated the changes in the properties of the deposited films with changes in the processing conditions such as the deposition rate, the substrate temperature, the microwave power and the plasma gas mixing ratio. We also measured the stretching frequency of three kinds of oxides, and ECR-CVD-grown oxide, a PECVD-grown oxide, and a thermally grown oxide, using FTIR analysis to compare their structural properties. The result shows that the structural properties of the ECR-grown oxide are similar to those of the thermally grown oxide. Additionally, the electrical properties of the ECR-grown oxide were investigated by using current-voltage and capacitance-voltage measurements. These electrical results indicate that the oxide charge density and the average breakdown voltage are 1×10 exp (11) ㎝^-2 and 6 MV/㎝, respectively.

다중경로를 갖는 헬리콥터 회전익 설계를 위한 진동 특성 연구

이기형,지창헌,정인성 全北大學校 1994 論文集 Vol.37 No.-

The bearingless rotorcraft offers reduced weight, less complexity and superior flying qualities. The bearingless rotors are presently being developed and it is most likely that the next generation rotorcraft would be equipped with these rotors. Almost all practical designs of bearingless rotors include multiple load paths. The flexure of a bearingless blade consists of multiple beams(flexbeads and torque tube) leading to redundancy. Numerical results are presented for several analytical models of the bearingless blade.

TGA를 이용한 가교폴리에틸렌의 방사선 열화 평가

이청,김기엽,류부형,임기조 한국안전학회 2003 한국안전학회지 Vol.18 No.2

Radiation degradation of crosslinked polyethylene(XLPE) was investigated using thermogravimetric analysis (TGA), The results of TGA were compared with FT-IR, melting temperature, oxidation induction time, and elongation al break on the XLPE exposed by γ-ray. 5% decomposition temperature of γ-ray irradiated XLPE showed similar tendencies with the case of elongation at break. Both properties agreed below 1000 kGy, however, did not show any remarkable characteristics above 1000 kGy, these properties can be useful to evaluate the radiation degradation of XLPE for only low irradiated region. Above 1000 kGy, the thermal decomposition activation energy showed decreased, on the contrary, increasing below 1000 kGy. Compared with FT-IR spectrum of irradiated XLPE, it was confirmed that the oxidation reaction was still occurring below 1000 kGy. Radiation degradation of XLPE was dependent upon the irradiation doses, TGA can be a useful tool to evaluate the degradation.

중심 정맥 삽관법에 의한 동정맥루: 증례 및 문헌 고찰

이 근,원형섭,양기창,박철완,김상일,정호성,이종호 대한응급의학회 1995 대한응급의학회지 Vol.6 No.1

A 36-year old woman with end stage renal failure and hypertension was transferred from a university hospital to our emergency department due to a enlarging right cervical mass associated with a palpable thrill and a bruit. Over a 2 month period, she required hemodialysis for severe azotemia at a university hospital in Seoul. 3 days after a difficult attempt at a internal jugular cannulation, she developed a progressive swelling in the right lower cervical area. An arch and primary branch arteriogram revealed a arteriovenous fistula between right innominate artery and internal jugular vein with a large intervening pseudoaneurysm. She underwent vascular surgery within 1 week of injury and subsequent postoperative angiogram showed complete resolution of the fistula. This rare condition is reported with a review of the literature.

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.

알루미늄 연속주조 용탕의 탈 가스 일체화 장치 개발

이용중,김태원,김기대,류재엽,이형우 한국공작기계학회 2004 한국공작기계학회 추계학술대회논문집 Vol.2004 No.-

It is necessary for managing a perfect process for degasing aluminum molten metal according to the increase of a grade of aluminum and its alloy products. There are some methods that have been used to manage a degasing process in recent years, such as an injection method that uses aluminum molten metal powder and chemicals supplier and input method that supplies argon and nitrogen, or chlorine gas by using a gas blow-tube. However, these methods show some problems, and it shows that it is a difficult process to handle, pollution due to the producing a lot of toxic gases like chlorine and fluoride gas, irregular effects, and lowering work efficiency due to the excessive processing time. The problems that are the most fatal are the producing a lot of sludge due to the reaction of aluminum molten metal with chemicals, loss of metals, and decreasing the life of refractory materials. In order to solve these problems, this paper develops a technology that is related to aluminum continuous casting molten metal and monolithic degasing apparatus. A degasing apparatus developed in this study improved the existing methods and prevented environmental pollution with smokeless, odorless, and harmlessness by using a new method that applies argon and nitrogen gas in which the methods used in the West and Japan are eliminated. The developed method can significantly reduce product faults that are caused by the production of gas and oxidation because it uses a preprocessed molten metal with chemicals. In addition, the amount of the produced sludge can also be reduced by 60~80% maximum compared with the existing methods. Then, it makes it possible to minimize the loss of metals. Moreover, the molten metal processing and settling time is also shortened by comparing it with the existing methods that are applied by using chemicals. In addition, it does much to improve the workers' health, safety and environment because there is no pollution. The improvement of productivity and prevention effects of disaster from the results of the development can be summarized as follows. It will contribute to the process rationalization because it does not have any unnecessary processes that the molten metal will be moved to an agitator by using a ladle and returned to process for degasing like the existing process due to the monolithic configuration. There are no floating impurities due to the oxidation caused by the contact with the air as same as the existing process. In addition, it can protect the blending of precipitation impurities. Because it has a monolithic configuration, it can avoid the use of additional energy to compensate the temperature decreasing about 60? that is caused by the moving of molten metal. It is not necessary to invest an extra facilities in order to discharge the gas generated from a degasing process by using an agitator. The working environment can be improved by the hospitable air in the factory because the molten metal is almost not exposed in the interior of the area.

치과용 금합금에 대한 금속 프라이머 처리와 열순환 처리가 교정용 브라켓의 전단결합강도에 미치는 영향

이영기,차정열,유형석,황충주 대한치과교정학회 2009 대한치과교정학회지 Vol.39 No.5

치과용 금합금에 교정용 브라켓 접착 시 금속 프라이머와 열순환 처리가 전단결합강도에 미치는 영향을 알아보기 위하여 80개의 치과용 금합금 시편을 샌드블라스팅만 처리한 군과 3종류의 금속 프라이머(Alloy Primer, Metaltite, V-Primer)처리를 시행한 군으로 분류하고, 이를 열순환 처리 시행 여부에 따라 모두 8개 군으로 분류하였다. 만능물성 시험기를 사용하여 브라켓의 전단결합강도를 측정하고, modified ARI (Adhesive Remnant Index) scores를 통해 브라켓 접착면의 파절 양상을 평가하였다. 열순환 처리 미시행 시에는 금속 프라이머의 적용 시 샌드블라스팅만 단독으로 처리한 경우에 비하여 통계적으로 유의성 있는 전단결합강도의 증가가 있었다 (p < 0.05). 열순환 처리를 시행한군에는 금속 프라이머의 처리에 의한 전단결합강도의 변화는 유의한 차이가 없었다 (p > 0.05). 금속 프라이머를 적용한 경우 열순환 처리 미시행 시에는 파절 양상이 브라켓과 접착제 계면에서의 파절 발생 빈도가 높았으나, 열순환 처리 시행 시에는 각 군 간 파절 양상에 유의한 차이가 없었다. 이상의 결과로 금속 프라이머의 적용이 치과용 금합금에 대한 교정용 브라켓 접착 시 초기 접착 강도에서는 유의성 있는 결합력의 증가를 보이나, 열순환 처리 시행 후에는 결합 강도에서는 유의한 차이가 없는 것으로 나타나 금속 프라이머에 의한 결합력 증가가 감소하는 것으로 생각한다. Objective: The aim of this study was to evaluate the effect of metal primers and thermocycling on shear bond strength between the orthodontic bracket and gold alloy. Methods: For this study, 80 specimens made of dental gold alloy were divided into 8 groups based on the combination of metal primers (none, Alloy primer, Metaltite, V-primer) and thermocycling (with and without thermocycling). Shear bond strength testing was performed with a universal testing machine. Bond failure sites were classified by a modified ARI (Adhesive Remnant Index) score. Results: All metal primer treated groups showed a significantly higher shear bond strength than the only sandblasting treated group without thermocycling (p < 0.05). There were no significant differences on shear bond strength in the groups with thermocycling (p > 0.05). Bond failure sites of the metal primer treated group without thermocycling occurred at gold alloy/adhesive interface, whereas there were no differences on bonding failure sites in the groups with thermocycling. Conclusions: These findings suggest that using metal primer on gold alloy enhances the initial bracket bond strength. But, this effect was not shown with thermocycling.

Two Stage 발효에 의한 고산도 식초 생산

이영철,이금용,김형찬,박기범,유익제,안평욱,최춘언,손세형 한국산업미생물학회 1992 한국미생물·생명공학회지 Vol.20 No.6

산업적으로 산도 17.0% 이상의 고산도 식초를 생산하기 위하여 반연속식인 1st stage와 유가식인 2nd stage로 구성된 two stage 초산 발효를 온도 30 ℃, 교반속도 600 rpm, 통기량 0.1 vvm에서 실시하였다. 1st stage에서 초기 에탄올 농도를 50.0 g/ℓ, 잔류 에탄올 농도를 5.0 g/ℓ로 정하여 반연속적으로 초산발효를 하고, 2nd stage 에서 발효시간의 경과에 따라 에탄올을 유가식으로 첨가하여 초산발효액내의 에탄올 농도를 5.0 g/ℓ에서 10.0 g/ℓ로 유지했을 때 산도가 17.6%인 고산도 식초를 생산할 수 있었으며, 또한 이 ??의 최대 초산 생산성은 3.3 g/ℓ·hr였다. The production of vinegar containing 16.0 ∼18.0% of acetic acid was examined in two stage fermentation consisting of semi-continuous and fed-batch type. The optimum conditions were obtained when the fermentation was carried out at agitation of 600 rpm, aeration of 0.1 vvm and temperature of 30℃. The initial and residual ethanol concentration in 1st stage were 50.0 g/ℓ and 5.0 g/ℓ, respectively, and the ethanol concentration in 2nd stage was maintained from 5.0 to 10.0 g/ℓ. The maximum productivity was 3.3 g/ℓ-hr and the acidity was 17.6% after the two days of acetic acid fermentation.

면역학적 접근법을 이용한 미소대장암의 진단 및 외과적 치료

이기형,이석환,고석환 경희대학교 1997 慶熙醫學 Vol.13 No.1

사립체 DNA 뉴클레오타이드 3243 A→G 돌연변이 [MTTL1^*MELAS3243G]에 의한 MELAS 증후군

박기형,김승현,이영주,김희태,김주한,김명호,박성섭 대한신경과학회 1998 대한신경과학회지 Vol.16 No.4