• Proceedings of the KSME Conference
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• 2002.08a
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• pp.317-320
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• 2002

The effect of vibration on the viscosity of a shear-thinning fluid was investigated with a newly designed pressure-scanning capillary viscometer. The viscometer was designed to measure non-Newtonian viscosity continuously over a range of shear rates at a time. Low frequency vibration was applied perpendicularly to the direction of the flow. The effect of the transversal vibration was investigated for both Newtonian fluids and non-Newtonian fluids. The experimental results showed that the vibration had no effect on the viscosity of the Newtonian fluids. However, the vibration caused a significant reduction of the shear-thinning fluid viscosity. The viscosity reduction was strongly dependent on both vibration frequency and shear rate. In addition, the viscosity reduction was affected by the amplitude of vibration, and, the bigger amplitude applied, the more viscosity reduction occurred.

• Journal of the Korean Society of Hazard Mitigation
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• v.10 no.2
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• pp.123-133
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• 2010

Due to climate change and difficulty in construction of large dam, it is on the increase to use small hydraulic facilities such as washland for the flood control purpose. Since there can be many potential locations for washland in a basin, it is important for determination of optimal location to calculate flood reduction effect of washlands substantially and exactly. In this study, a new scheme to increase flood reduction effect of washlands is suggested. Suggested scheme uses sensitivity analysis of flood reduction effect depending on washland characteristics such as storage volume, spillway elevation and spillway width. The characteristics of the washland is determined by results of sensitivity analysis to maximize flood reduction effect at basin outlet and downstream of a washland. The methodology is applied to Anseong river basin to show its applicability and applied result is compared with those of another studies.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.17 no.12 s.115
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• pp.1231-1239
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• 2006

In this research magnetic field reduction effect of each passive loop was analyzed by using the scale down models of transmission lines. This paper examined magnetic field reduction effect of the passive loop that will be applied to actual facility through the experiment, which is about double vertical transmission line and horizontal transmission line. Consequently, by confirming the fact that magnetic field reduction effect can be obtained to 50 % by passive loop without reactive compensation, we insured technology about application of passive loop. And the case of 3 turns of loop showed two times reduction effect than that of 1 turns of loop in reducing magnetic field. Vertical passive loop is more efficient than horizontal passive loop in the aspect of reducing magnetic field on double vertical transmission lines. What is more, vertical passive loop showed good effect of reducing magnetic field in a far distance as well as in a short distance.

• Journal of Korean Medicine for Obesity Research
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• v.5 no.1
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• pp.87-95
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• 2005

Objectives : The weight reduction program with very low calorie diet(VLCD) for women generally reduce bone mineral density(BMD). So many treatments were done to prevent side effect of the weight reduction program and herbal diet meditation were often used in oriental medicine. This research were done in order to study the effect of VLCD and herbal diet meditation, Chegamuiyiin­tang on BMD. Methods : This clinical research carried out 22 cases of pre-menopausal outpatients with obesity during 1 month. To evaluate the effect Chegamuiyiin-tang with VLCD on BMD, the weight, BMI, percent body fat, WHR, BMD(T-score) were estimated in pre-treatment and post-treatment. Results : The mean weight reduction after 1 month was $6.87{\pm}1.54\;Kg$(10.28 % of initial weight), BMI reduction was $2.35{\pm}0.65\;Kg/m^2$, percent body fat reduction was $3.40{\pm}1.01%$, WHR reduction was $0.04{\pm}0.01$. But BMD(in T-score) had significant increase. Conclusions : Generally VLCD were estimated to reduces BMD, but VLCD with herbal diet meditation, Chegamuiyiin-tang has positive effect on BMD in pre-menopausal women during short term(1 month).

• Journal of Korean Society on Water Environment
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• v.25 no.6
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• pp.886-895
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• 2009

The guideline of selection of Integrated Management Practices (IMPs), such as wood, green roof, lawn, and porous pavement, for Low Impact Development (LID) design was proposed by ranking the reduction rate of surface runoff using LIDMOD1.0. Based on the guideline, LID was designed with several scenarios at two apartment complexes located at Songpa-gu, Seoul, Korea, and the effect of LID on surface runoff was evaluated during last 10 years. The effect of runoff reduction of IMP by land use change was highly dependent on the kind of hydrologic soil group. The wood planting is the best IMPs for reduction of surfac runoff for all hydrologic soil groups. Lawn planting is an excellent IMP for hydrologic soil group A, but reduction rate is low where soil doesn't effectively drains precipitation. The green roof shows constant reduction rate of surface runoff because it is not influenced by hydrologic soil group. Compared to the rate of other IMPs, the green roof is less effect the surface runoff reduction for hydrologic soil group A and is more effect for hydrologic soil group C and D followed to planing wood. The porous pavement for the impervious area is IMPs which is last selected for LID design because of the lowest reduction rate for all hydrologic soil group. As a result of LID application at study areas, we could conclude that the first step of the strategy of LID design at apartment complex is precuring pervious land as many area as possible, second step is selecting the kind of plant as more interception and evapotranspiration as possible, last step is replacing impervious land with porous pavement.

• Journal of the Korean Society of Hazard Mitigation
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• v.11 no.3
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• pp.183-189
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• 2011

In this study sediments reduction effects on dam have been analyzed in the case of check dam installation in the upstream. Analyzed sediment reduction effects of 27 points conducted for 10 multi-purposes dam, which is target of this study. According to regression analysis result, Sediment reduction effect by installing check dam has shown inclination which increase as area ratio rises. According to analysis result, sediment reduction effect was greatest in Geum-river point at Daecheong-dam. The life-time is estimated to increases about 60% by installing check dams. When Area ratio increases, it was deduced through regression analysis that rise Sediment Reduction Effect by installing check dam. This study can be useful for the management and design plans like the dam's site or priority for placing. Furthermore, it would be able to construct an efficient sand depositing dam if complementary is provided by being considered catchment area and lucrative property.

• Journal of Korean Society of Disaster and Security
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• v.11 no.2
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• pp.61-67
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• 2018

Scour protection methods can be categorized as two types: The first is to reduce the horseshoe and wake vortices which are the main reasons for local scour. Either small cylindrical structures or separated vertical deflectors can be placed in front of the pier or the horizontal deflector (or collar) can be attached to the pier like the spoiler to reduce the dynamics of vortical structures. The second is to employ the protection layer to keep the bed material in place, which is a common method with a merit of immediate effect by using block mat or tetrapod. This study examined the effect of scour reduction using the former method. The relationship between the reflector interval and reduction of scour was not clear. It is assumed that the width of the reflector is somewhat correlated with the reduction of the scour. As the KC numbers increases, the Effect of Scour reduction rate is shown to decrease. Also, Scour reduction rate showed a rapid change at $U_R=25$ or KC = 8.

• Transactions on Electrical and Electronic Materials
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• v.7 no.2
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• pp.53-57
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• 2006

In this paper, a Symmetric Dual-gate Single-Si TFT, which includes three split floating n+ zones, is simulated. This structure drastically reduces the kink-effect and improves the on-current. This is due to the separated floating n+ zones, the transistor channel region is split into four zones with different lengths defined by a floating n+ region. This structure allows effective reduction in the kink-effect, depending on thy length of the two sub-channels. The on-current of the proposed dual-gate structure is 0.9 mA, while that of the conventional dual-gate structure is 0.5 mA, at both 12 V drain and 7 V gate voltages. This result shows an 80% enhancement in on-current. In addition, the reduction of electric field in the channel region compared to a conventional single-gate TFT and the reduction of the output conductance in the saturation region, is observed. In addition, the reduction in hole concentration, in the channel region, in order for effectively reducing the kink-effect, is also confirmed.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.20 no.9
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• pp.791-796
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• 2010

Installing noise barriers is the most common method for reducing the highway traffic noise to the road side residential area. After the report about edge potential concept of a noise barrier, various types of noise reducing devices(NRDs) called "noise reducers" have been suggested for getting more shielding effect on the top of highway noise barriers. But, it has been doubtful about effect of the NRDs in field because there was no appropriate and unified method to estimate the acoustic performance by using field measurement of the NRDs in Korea. In this study, the authors have considered to setup a practical method to test and estimate the acoustic performance of NRDs. For eliminating the noise reduction effect of the NRDs height itself, the source and measuring points are adjusted as highly as the NRDs height. For the frequency weighting in the estimation of the NRDs effect, the highway noise spectra were measured at asphalt and concrete road side and then averaged for a unit spectral parameter.

• Tribology and Lubricants
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• v.16 no.3
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• pp.223-230
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• 2000

Factors influencing friction reduction with MODTP(molybdenum dialkyl dithiophosphate) lubricant were investigated through a frictioning experiment using two-cylinder edge surface frictioning tester and XPS surface analysis. The friction reduction effect gained with MoDTP lubricant appeared to be largely attributable to MoS$_2$ formation on the frictioning interface. Under N$_2$ atmosphere, Mo diffused into the metal substrate, easily escaping from MoS$_2$ so the friction reduction effect from MoDTP was not gained. However, when an oxide surface film was preliminary prepared on frictioning surface, this Mo diffusion to metal substrate from MoS$_2$ was effectively inhibited. Then desired lubulication effect of MoDTP was gained even under N$_2$atmosphere. As such, the existence of a surface oxide film on the frictioning surface was concluded to be of essential importance in order to gain a lubrcating effect with MoDTP.