• 소음진동
• /
• 제5권4호
• /
• pp.555-563
• /
• 1995

This paper proposes the method of antiresonance frequency analysis of multi-input multi-output system. The structural dynamic modification techniques by antiresonance frequency analysis are also applied to reduce the undertest at specimen attachment points on the fixture in environmental vibration test, which is resulted from the inconsistency of antiresonance frequencies at any specified points. Several computer simulations show that the proposed method can remove the undertest problem which is not removed in conventional vibration test control. And the effectiveness of the method is verified with the impact hammer excitation of aluminium fixture model.

• 오토저널
• /
• 제5권2호
• /
• pp.15-20
• /
• 1983

The nature and the sources of sound in cars is discussed in the light of many previous works, and the importance of the system resonances inside cars is suggested. An investigation of a 'boom' problem in a small size passenger car is described. It was established that the 'boom' frequencies coincided with engine firing frequency and also with several system resonances. To find out main transmission path of the noise to the car interior, various possible sources were eliminated from the investigation by means of simple modification to the vehicle. Data on the structural modes of the body, and the acoustic modes of the passenger compartment at various forcing cases were obtained to provide better understanding of the problem. It was found that the acoustic resonance responsible for the boom was controlled largely the bending motion of the floor. To investigate the effect of the structural modification to the acoustic response, center floor of the car was reinforced. a great reduction of the noise inside the car especially at the offending speed range, was achieved by this modification.

• 한국정보디스플레이학회:학술대회논문집
• /
• 한국정보디스플레이학회 2007년도 7th International Meeting on Information Display 제7권2호
• /
• pp.1771-1773
• /
• 2007

Surface modification of the gate dielectric has a strong influence on the performance of printed transistors. The surface modification occurs between the gate dielectric and semiconductor. The printed transistor with evaporated vanadium pentoxide ($V_2O_5$) modification exhibits a mobility of $0.2cm^2\;V^{-1}\;s{-1}$ and a subthreshold slope of 1.47 V/decade.

• 소성∙가공
• /
• 제13권4호
• /
• pp.307-318
• /
• 2004

Rectangular drawn case with extreme aspect ratio is widely used for electrical parts such as a lithium-ion battery container, semi-conductor case and so on. Additionally, from the recent trend towards miniaturization of the multi-functional mobile device, demands for rectangular case with the narrow width are increased. In this study, numerical and experimental approaches for the multi-stage deep drawing process have been carried out. Based on the research results of the width of 5.95mm model, finite element analysis for storage case of rectangular cup type was verified to the width of 4.95mm. Also, a series of manufacturing experiments for rectangular case is conducted and the deformed configuration of the rectangular drawn case are investigated by comparing with the results of the numerical analysis. And the modification of the initial blank is performed to minimize the trimmed material amount. By the application of the modified blank, the sound shape of the deformed parts is improved.

• Journal of Microbiology
• /
• 제34권3호
• /
• pp.270-273
• /
• 1996

Micrococcus luteus purine nucleoside phosphorylase (PNP) has been purified and characterized. The physical and kinetic properties have been described previously. Chemical modification of the enzyme was attempted to gain insight on the active site. The enzyme was inactivated in a time-dependent manner by the arginine- specific modifying reagent phenylglyoxal. There was a linear relationship between the observed rate of inactivation and the phenylglyoxal concentration. At 30 $^{\circ}C$ the bimolecular rate constant for the modification was 0.015 $min^{-1}mM^{-1}$ in 50 mM $NaHCO_3$ buffer, pH 7.5. The plot of logk versus log phenylglyoxal concentration was a strainght line with a slope value of 0.9, indicating that modification of one arginine residue was needed to inactivate the enzyme. Preincubation with saturated solutions of substrates protected the enzyme from inhibition of phenylglyoxal, indicating that reactions with phenylglyoxal were directed at arginyl residues essential for the catalytic functioning of the enzyme.

• 한국정밀공학회지
• /
• 제28권5호
• /
• pp.632-637
• /
• 2011

A new tooth profile which is adjusted on the amount of addendum modification factor is proposed for reducing vibration and noise of gears. The transmission error of the new profile can be designed more uniformly than that of the standard involute profile. The basic concepts of tooth profile modification are to reduce the load in contact area and to find the appropriate profile modification factor for operation condition. In this study, gears were estimated to constructive safety of bending strength and contact strength durability by using ROMAX program, and were compared with results by design formula of AGMA standard.

• 한국대기환경학회지
• /
• 제9권2호
• /
• pp.132-139
• /
• 1993

TCM has been used for many environmental impact assessments and many case studies in Korea. TCM was applied to urbvan areas and rolling terrains. But original TCM was developed for rural area, and this model could not reflect the characteristcs of these study sites. This paper analyzed the characteristics of TCM, and modified the algorithm of area source, and modified the vertical wind speed profile exponents and diffusion parameter to make it applicable in urban area. In the process of modification, an important error in area source calculation of original TCM program was found. So that was corrected as follows. $$ Before modification $QC = 0.79788456^*(0.5^*GRID)^**BA/(U(IA, IRUN)^*AA^*BA TCM09310$ After modification $QC = 0.79788456^*(500^*GRID)^**BA/(U(IA, IRUN)^*AA*BA) modified$ $$ Then original TCM and modified TCM-urban mode were compared, and it was found that predicted mean value by original TCM was 7 times higher than observed mean value. But mean value by modified TCM-urban mode was very similar to observed value.

• 한국분말재료학회지
• /
• 제6권1호
• /
• pp.36-41
• /
• 1999

The present work has attempted to investigate the dependence of Cu infiltration kinetics on in-situ structure modification of W powder skeleton in W-Cu system. In-situ structure modification of W skeleton by addition of 0.3wt%Ni-P eutectic alloy was designed to proceed during heat-up of the W compact for Cu infiltration process. It was found that the Ni-P added W skeleton underwent remarkable stucture change only during heating-up. its structure was composed of large necks of W particles above 0.5 in the ratio of neck to particle size and smooth pore channels. The infiltration experiment showed that the infiltration kinetics for the W-Ni-P followed well the linear relationship of h vs. $t^{1/2}$ the rate constant K of which was in good agreement with the theoretical value. On the other hand, in case of the pure W skeleton a lower K value by 20% than the theoretical one was obatined. Such discrepancy is discussed in terms of skeleton structure induced infiltration mechanics.

• 약학회지
• /
• 제45권5호
• /
• pp.529-536
• /
• 2001

The root of Astragalus membranaceus Bunge (Leguminosae), which has been used for the treatment of hypertension, chronic hepatitis, duodenal ulcers, chronic nephritis and promotion of immunity in folk remedies. Several lines of evidence indicate that oxidative modification of low-density lipoprotein (Ox-LDL) may play an important role in atherogenesis. Hence, the role of antioxidants in the prevention of LDL oxidation needs to be determined. To investigate the antioxidant activity. we determined the MeOH ex. and fractions of Astragali Radix on the inhibition of LDL oxidation. The CH$_2$C1$_2$ and EtOAc orations inhibited the oxidative modification of LDL by a decrease in the lipid peroxide content and the electrophoretic mobility of LDL. Calycosin-7-0-$\beta$-D -glucoside which was isolated from EtOAc fraction inhibits the oxidative modification of LDL.

• 한국항해항만학회:학술대회논문집
• /
• 한국항해항만학회 2006년도 International Symposium on GPS/GNSS Vol.1
• /
• pp.83-88
• /
• 2006

Evaluation of collision risk plays a key role in developing the expert system of navigation and collision avoidance. This paper presents a new collision risk model formula that is one modification model on the basis of one approach to the evaluation of collision risk using sech function produced by Prof. Jeong in his relevant $articles^{[2][3][4][5]}$. And as a grope in collision risk evaluation field, this paper applied the new model in appraising the collision risk, suggested how to decide the safe range of own ship’'s action. Moreover this paper also analyzed theoretically how to determine the coefficients as describes in the new modification model formula, and suggested the appropriate values as applicable.