십자형 점용접부의 피로강도 평가에 관한 연구

최덕호,양경탁,김호경 서울産業大學校 2005 논문집 Vol.54 No.2

In this study, SPCC cross-tension type specimens produced under various welding conditions were tensile and fatigue tested. Decrease of 2 kA in normal current condition of 10 kA caused a large amount of reduction in both static joining strength and fatigue life. And 2 kA increase resulted in increase of static joining strength and an increase in low cycle regime but a decrease in high cycle regime, revealing the fact that fatigue strength rather than static joining strength would be a major factor during design process in view of the body endurance. As a results of estimating the fatigue lifetimes of various types of specimens, equivalent stress intensity factor is the proper parameter for predicting the lifetimes of various types of specimens, which can be expressed as ΔK_(eq) (N/mm^(1.5)) = 11550N_(f)^(-0.36)

분광 앨립소미트리를 이용한 유리기판 위의 박막 분석

성덕경,방경윤,오영륙,최은호,안일신,김옥경 한양대학교 이학기술연구소 2003 이학기술연구지 Vol.6 No.-

Spectroscopic ellipsometry 은 다양한 물질의 광학적 특징을 연구할 수 있는 강력한 기술이다. 현재 실리콘 웨이퍼 위의 박막 분석에는 그 효율성이 확실히 입증되어 있다. 그러나 현재 산업은 유리 기판위의 박막을 분석하기를 원하고 있다. Ellipsometry로 투명기판을 분석하기 위해서는 후면 반사에의한 비간섭성 효과를 고려해야 한다. 기존의 반사공식을 투명기판의 비간섭성을 고려하여 수정하였다. 투명기판 위의 샘플과 scratch를 낸 같은 샘플을 측정 분석하여 정확성을 확인하였다. 수정된 반사공식을 이용하면 디스플레이와 같은 투명재료를 이용하는 곳에 유용하게 사용될 것으로 기대되고 있다. A Spectroscpic ellipsometry is very strong technology to study optical properties of many materials. It has already substantiated a analytic efficiency about thin films above wafers to be made of silicon. However, the current industry needs thin films analyzed on a glass. When we analyze a glass using a ellipsometry, we have to consider a efficiency of incoherence due to reflect at the back side. So then, we slightly altered the original formula. We compared a scratched sample with a sample on the glass, because off getting a exactitude. Our technical development, using the changed formula, is expected the useful utilization in a part of using gIasses such as display.

광중합형 글라스아이오노머 시멘트와 복합레진과의 전단결합강도에 관한 연구

김덕,민병순,최호영,박상진,최기운 慶熙大學校 齒科大學 1994 慶熙齒大論文集 Vol.16 No.1

The purpose of this study is to evaluate of shear bond strength of light-curing composite resin to light-curing glass ionomer cement. Composite resin and glass ionomer cement have been widely used as an esthetic filling materials in dental clinics. To achieve better clinical results, sandwich technic was developed with conpensating for disadvantages of these two materials. Especially, light-curing glass ionomer cement provided greately improved bonding strength of teeth or composite resin, and then excellent clinical results can be acquired. In this study, 6 commercial light-curing glass ionomer cements(3 commercial restorative materials Fuji II LC, Vanglass VLC, Vitremer, and 3 commercial lining materials : Fuji Lining LC, Baseline VLC, Vitrebond) were devided two groups. According to manufacturer's appointment, no surface treatment was referred to N groups. Supposing of clinical practice, surface grinding with water ;spray at 320 grit sand paper, 40 seconds etching with 37% phosphoric acid, 20 seconds washing 20 seconds air drying was referred to E groups. Totally 12 experimental groups were devided, and all 120 specimens from 10 specimens of each groups were made. After light-curing composite resin was bonded to right-curing glass ionomer cement, shear bond strength was tested by Instron universal testing machine between glass ionomer cement and composit resin. The data were analyzed statistically by Student's t-test and ANOVA. The obtained results were as follows; 1. In light-curing glass ionomer cement, restorative materials showed higher shear bond strength to composite resin than lining matenals(p<0.05). 2. Variglass VLC of restorative material group and Baseline VLC of lining material group have highest shear bond strength to composite resin(p<0.001). 3. In light-curing glass ionomer cement:, surface grinding and acid etching reduced shear bond strengthto composite resin(p<0.001). 4. VGN group is highest shear bond strength to composite resin, VBE group is lowest shear bond strength to composite resin(p<0.001).

감마선과 Methyl Bromide 처리가 사과의 생리화학적 품질에 미치는 영향

강호진,정헌식,조덕조,변명우,최성진,최종욱,권중호 한국식품저장유통학회 ( 구 한국농산물저장유통학회 ) 2003 한국식품저장유통학회지 Vol.10 No.3

감마선(0, 0.5, 1, 2, 3 kGy) 조사와 methyl bromide(MeBr, 26 g/㎏, 4hr) 훈증 및 이들의 처리시기가 사과의 생리화학적 품질특성에 영향을 비교하여, 검역처리를 위한 ◁그림 삽입▷ (원문을 참조하세요) 감마선 조사의 응용성을 검토하였다. 감마선과 MeBr 처리에 따른 사과의 생리화학적 품질평가에서 2kGy 이상의 감마선 조사와 MeBr 훈증은 사과의 일부 생리화학적 품질특성의 변화를 촉진시키는 것으로 나타났다. 감마선과 MeBr의 처리시기별로는 수확 직후보다는 저온(0℃)에서 40일 정도 보관 후 처리한 대체적으로 품질손상이 적은 것으로 나타났다. 따라서 1kGy 이하의 감마선 조사와 지연조사는 사과 과실의 품질을 비교적 양호한 상태로 유지할 수 있어 검역처리 기술로 활용성이 있는 것으로 생각된다. 'Fuji' apples were treated by gamma irradiation (0∼3 kGy) or methyl bromide fumigation at commercial conditions (MeBr, 25 g/㎏, 4 hr) for quarantine purpose at two different treatment timing after harvest and stored under air a 0℃ for 4 months. Associated with the treatment timing of irradiation or fumigation, after 40 days of storage at 0℃ following harvest was more adequate than immediately after harvest in keeping qualities of stored apples. However, more than 2 kGy irradiation and MeBr fumigation were detrimental to physiological and chemical qualities of the fruits. These results show that less than 1 kGy irradiation at the delayed timing has a possibility to be applied as a quarantine procedure without significant changes in the quality of apples.

아르곤 레이저에 의한 복합레진의 중합시 물성 변화에 관한 연구

김덕,민병순,최호영,최기운,박상진 大韓齒科保存學會 1998 Restorative Dentistry & Endodontics Vol.23 No.1

After polymerizing composite resin with argon laser and visible light, four test, to be concretelv, measurement of compressive strength using Instron testing machine, surface microhardness using Rockwell hardness tester, quantitative analysis of residual monomer using HPLC and analysis of degree of conversion using FTIR, were accomplished. Test groups were a sort of specimen with 3mm diameter, 4㎜ thickness for measuring compressive strength, two sort of specimen with 7mm diameter, 2mm and 3㎜ thickness for measuring surface microhardness, quantitative analysing of residual monomer after curing and measuring the degree of conversion, each were divided by according to the condition of light exposure. In case of argon laser. in 1.0W and 0.5W output. the exposure time for specimen were 5 sec, 10 sec respectiyely. In case of visible light, the exposure time obtained. 1. Compressive strength of composite resin was the highest in the group of 1W output, exposing for 10 sec with argon laser, followed by the group of 0.5W, exposing for 10 sec with argon laser, the group of exposing for 40 sec with visible light. But there were statistically no significant difference between these three groups(p>0.05). 2. Surface microhardness of composite resin wasn't significantly affected by light curing conditions. 3. BIS- GMA within residual monomer was least detected in the group of exposing for 40 sec. TEGDMA was least detected in the group of 1W output, exposing for 10 sec with argon laseboth 2㎜ and 3㎜ thickness specimen. 4. The degree of conversion of all groups in the 2㎜ thickness specimen were more than 5%, similar to each other but in the group of 1W, exposing 10 sec with argon laser the degree of conversion was highest in the 3㎜ thickness specimen. 5. Argon laser could make composite resin to has similar properties with 25% lesser exposure time than visible light.

무균돈사내 급배기구의 적정위치설정에 관한 연구

권순정,손덕영,최윤호 한국의료복지시설학회 2008 의료·복지 건축 Vol.14 No.4

Construction and operation of Germ Free Pigs' facilities are very expensive because pigs' rooms and other major rooms of the facility require germfree environments. Especially, running the HVAC system of aseptic facilities requires a lot of expenses. However proper location and efficient shape of outlets/inlets for the ventilation of the room can reduce the excessive running cost. In order to do that, this study proposes alternative location and shape of ventilation outlets/inlets to the existing design pattern in germfree pigs' room. The design condition of this study is the maintenance of adequate temperature(24'C), NHs concentration level(below 1.5 ppm), and air stream speed(be1ow .25m/sec) in the pigs' room for the summer and the winter together. As the Software Program, FLUENT(Ver. 6.2) has been used for the analysis of proposed ventilation patterns, In conclusion, wall inlets and ceiling inlet/outlet are advisable in summer, wall inlets and ceiling outlets is advisable in winter. As far as the shape is concerned, diffuser type for the ceiling outlet is desirable.

Screening of the Positive Inotropic Activity of Medicinal Plants Used in Oriental Medicine

Deok Ho Choi,Dae Gill Kang,Seung Ju Kim,Xun Cui,Ho Sub Lee 한의병리학회 2006 동의생리병리학회지 Vol.20 No.3

Ethanol Extract of Cynanchum wilfordii Produces Endothelium-Dependent Relaxation in Rat Aorta and Anti-inflammatory Activity in Human Aortic Smooth Muscle Cells

Choi, Deok-Ho,Lee, Yun-Jung,Kim, Eun-Joo,Li, Xiang,Kim, Hye-Yoom,Hwang, Sun-Mi,Yoon, Jung-Joo,Lee, So-Min,Min, Eun-Kyeong,Kang, Dae-Gill,Lee, Ho-Sub The Society of Korean Medicine 2010 대한한의학회지 Vol.31 No.6

Objective: The present study investigated the effect of ethanol extract of Cynanchum wilfordii (ECW) on vascular relaxation and vascular inflammation in rat artery isolated from rats and anti-inflammatory activity in human aortic smooth muscle cells (HASMC). Methods: Vascular tone and guanosine 3',5'-cyclic monophosphate (cGMP) production were examined in rat artery isolated from Sprague Dawley rats, in the presence of ECW. HASMC were incubated with tumor necrosis factor-alpha (TNF-${\alpha}$) or Angiotensin II for 24 h. Matrix metalloproteinase (MMP)-2 and anti-oxidant activity of ECW was investigated by pretreatment with ECW in HASMC. Results: Cumulative treatment of ECW relaxed aortic smooth muscles of rats in a dose-dependent manner. ECW-induced vasorelaxation was significantly decreased by pretreatment of L-arginine methyl ester (L-NAME) or oxadiazolo-quinoxalinone (ODQ). Furthermore, ECW treatment of thoracic aorta significantly increased cGMP production. Incubation of ECW with ODQ or L-NAME markedly decreased ECW-induced cGMP production. ECW treatment dose-dependently suppressed TNF-${\alpha}$- or Angiotensin II-induced increase in matrix metalloproteinase-2 expression in HASMC. Also, ECW exhibited 2,2-diphenyl-1-picrylhydrazyl radical scavenging activity in vitro and reduced TNF-${\alpha}$-induced increase in reactive oxygen species production in a dose-dependent manner. Conclusions: Taken together, the results suggest that ECW exerts vascular relaxation via NO/cGMP signaling pathway and decreases MMP-2 expression via anti-oxidant activity.

Selective Epitaxial Growth of SiGe Layers with High Aspect Ratio Mask of Dielectric Films

CHOI, A-Ram,CHOI, Sang-Sik,PARK, Byung-Guan,SUH, Dongwoo,KIM, Gyungock,KIM, Jin-Tae,CHOI, Jin-Soo,CHO, Deok-Ho,HAN, Tae-Hyun,SHIM, Kyu-Hwan The Institute of Electronics, Information and Comm 2008 IEICE transactions on electronics Vol. No.

<P>This paper presents the selective epitaxial growth (SEG) properties of reduced pressure chemical vapor deposition (RPCVD) at low temperatures (LT) of 675-725°C with high aspect ratio mask of dielectric films. The SEG process could be explained in conjunction with the loading effect, the mask pattern shape/size, and the process parameters of RPCVD. The growth rates showed a large non-uniformity up to 40% depending upon the pattern size of the dielectric mask films, but as the SEG film becomes thicker, the growth rate difference converged on -15% between the narrow 2-μm and the wide 100-μm patterns. The evolution of SEG was controlled dominantly by the surface migration control at the initial stage, and converted to the surface topology control. The design of pattern size and distribution with dummy patterns must be useful to accomplish the reliable and uniform LT-SEG.</P>

Instability dependent upon bias and temperature stress in amorphous-indium gallium zinc oxide (a-IGZO) thin-film transistors

Choi, Kwang-Il,Nam, Dong-Ho,Park, Jeong-Gyu,Park, Sung-Su,Choi, Won-Ho,Han, In-Shik,Jeong, Jae-Kyeong,Lee, Hi-Deok,Lee, Ga-Won Wiley Blackwell (John Wiley Sons) 2010 Journal of the Society for Information Display Vol.18 No.1