• Title/Summary/Keyword: Close reduction

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Evaluation of Accelerated Retirement Program for In-use Diesel Vehicles based on their NOx Emission Characteristics (노후 운행경유차의 NOx 배출특성분석 및 조기폐차대책을 통한 삭감 방안 검토)

  • Keel, Jihoon;Lim, Yunsung;Kim, Hyungjun;Roh, Hyungu;Yun, Boseop;Lee, Sangeun;Lee, Taewoo;Kim, Jeongsoo;Choi, Kwangho
    • Journal of ILASS-Korea
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    • v.22 no.3
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    • pp.122-128
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    • 2017
  • Currently, the proportion of diesel vehicles in all automobile has grown significantly over the past few years. Air pollutant also grew up and became a social problem. In particular, the issue of NOx emissions caused by NOx high emission in real driving has become a global issue. Despite the fact that the regulatory and reduction project of the new vehicle is actively carried out, there are no existence regulations of In-use diesel vehicle's NOx emission. Therefore, the emission characteristics of the in-use diesel vehicles were investigated to seek ways to reduce NOx emissions in this study. The test targets were used in 237 close inspection of exhaust gases and model year varied from 1996 to 2011. However, the classification of emissions by emission standards differed considerably from NOx emissions. This means that the selection method for early retirement targets should be converted from model year to amount of emissions. If the current early retirement program was applied to the existing system, pre-Euro 3 was 22.530 g/km and Euro 4 was 21.810 g/km to NOx reduction. However, when the vehicle was changed to high emission target vehicle, NOx reduction increase maximum 84.705 kg/yr. According to the study results, an effective reduction in NOx emissions can be achieved if an earlier target in expanded to Euro 4 vehicles.

Strain-based stability analysis of locally loaded slopes under variable conditions

  • Wang, Jia-Chen;Zhu, Hong-Hu;Shi, Bin;Garg, Ankit
    • Geomechanics and Engineering
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    • v.23 no.3
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    • pp.289-300
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    • 2020
  • With the rapid development of the distributed strain sensing (DSS) technology, the strain becomes an alternative monitoring parameter to analyze slope stability conditions. Previous studies reveal that the horizontal strain measurements can be used to evaluate the deformation pattern and failure mechanism of soil slopes, but they fail to consider various influential factors. Regarding the horizontal strain as a key parameter, this study aims to investigate the stability condition of a locally loaded slope by adopting the variable-controlling method and conducting a strength reduction finite element analysis. The strain distributions and factors of safety in different conditions, such as slope ratio, soil strength parameters and loading locations, are investigated. The results demonstrate that the soil strain distribution is closely related to the slope stability condition. As the slope ratio increases, more tensile strains accumulate in the slope mass under surcharge loading. The cohesion and the friction angle of soil have exponential relationships with the strain parameters. They also display close relationships with the factors of safety. With an increasing distance from the slope edge to the loading position, the transition from slope instability to ultimate bearing capacity failure can be illustrated from the strain perspective.

Noise Reduction of PDP TV Using Multi-dimensional Spectral Analysis Method (다차원 스펙트럼 해석법을 이용한 PDP TV의 저소음화)

  • Yang, In-Hyung;Jeong, Jae-Eun;Kwak, Hyung-Taek;Oh, Jae-Eung
    • Transactions of the Korean Society for Noise and Vibration Engineering
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    • v.21 no.1
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    • pp.81-88
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    • 2011
  • The method is introduced for estimating the noise source contribution on the noise of PDP TV in a multiple-input system where the input sources may be coherent with each other. By the coherence function method, it is found that the biggest part of the noise source in the PDP TV noise is generated by the PCB boards which consume high power and produce high heat. This analysis is modeled as three-input/single-output system because the noise is generated by three main boards, X-board, Y-board, SMPS that are located close to each other. The coherence function method is proved to be useful tool for identifying of noise source. In this study, Transfer Path Analysis using MDSA is implemented to determine the quantitative noise contribution of each board for PDP TV with the rear case closed and with the rear case open. And the possibility of noise reduction is confirmed through the experimental method that isolates the most contributing board by adding sound-absorbing materials to it.

PERFORMANCE OF AN OSCILLATING SUBSOILER IN BREAKIN HARD PAN

  • Bandalan, E.P.;Gupta, C.P.;Salokhe, V.M.;Niyamapa, T.
    • Proceedings of the Korean Society for Agricultural Machinery Conference
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    • 1993.10a
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    • pp.1043-1052
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    • 1993
  • Field experiments were conducted to determine the optimum combination of performance parameters of a single-shank, tractor-mounted oscillating subsoiler. Tests were conducted at frequencies of oscillation of 3.7 , 5.67, 7.58, 9.48 and 11.456Hz ; amplitudes of 18, 21, 23.5, 34 and 36.5 mm ; and forward speeds of 1.84, 2.19 and 3.42 kmph at moisture content close to the plastic limit of the soil. It was observed that there was a reduction in average draft but an a increase in average total power requirement for oscillating than non-oscillating subsoiling. The draft and power ratios were significantly affected by the forward speed, frequency and amplitude. Their combined interaction expressed in terms of the velocity ratio parameter( the ratio of peak tool velocity and forward speed) however has the strongest influence. At the same velocity ratio, the draft reduction and power increase were less at higher amplitude of oscillation . As the oscillating frequency is increased toward the soil resonance the draft requirement becomes less. For the field conditions tested. the optimum operation was obtained at an amplitude of 36.5mm, frequency of 9.48Hz and speed of 2.19 kmph with a draft ratio of 0.33 and a power ratio of only 1.24.

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Characteristic of Tantalum Powder and Effect of Reaction Temperature on the amount of Diluent (희석제량에 따른 탄탈륨 분말 특성 및 반응온도의 영향)

  • 윤재식;박형호;배인성;정성만;김병일
    • Journal of Powder Materials
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    • v.9 no.5
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    • pp.315-321
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    • 2002
  • Pure tantalum powder has been produced by combining Na as a reducing agent, $K_2TaF_{7}$ as feed material, KCl and KF as a diluent in a stainless steel(SUS) bomb, using the method of metallothermic reduction. The present study investigated the effect of the amount of the diluent and reaction temperature on the characteristics of tantalum powder in the production process. The temperature applied in this study $850^{\circ}C$ and the amount of the additional reductant from +5% of the theoretical amount used for the reduction of the entire $K_2TaF_{7}$. The results showed that as the amount of the diluent increased, the reaction temperature became lower because the diluent prevented a temperature rise. Also, according to the mixture ratio of the feed materials and the diluent changed from 1 : 0.25 to 1 : 2, the particle size decreased from $5\mutextrm{m}$ to $1\mutextrm{m}$ and a particle size distribution which is below 325 mesh in fined powder increases from 71% to 83%. The average size of Tantalum powder, $2-4\mutextrm{m}$, was close to that of the commercial powders($2-5\mutextrm{m}$). Also under this condition, impurities contained in the powder were within the range allowed for the commercial Ta powders.

Comparison of Blooming Artifact Reduction Using Image Segmentation Method in CT Image (CT영상에서 이미지 분할기법을 적용한 Blooming Artifact Reduction 비교 연구)

  • Kim, Jung-Hun;Park, Ji-Eun;Park, Yu-Jin;Ji, In-Hee;Lee, Jong-Min;Cho, Jin-Ho
    • Journal of Biomedical Engineering Research
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    • v.38 no.6
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    • pp.295-301
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    • 2017
  • In this study, We subtracted the calcification blooming artifact from MDCT images of coronary atherosclerosis patients and verified their accuracy and usefulness. We performed coronary artery calcification stenosis phantom and a program to subtract calcification blooming artifact by applying 8 different image segmentation method (Otsu, Sobel, Prewitt, Canny, DoG, Region Growing, Gaussian+K-mean clustering, Otsu+DoG). As a result, In the coronary artery calcification stenosis phantom with the lumen region 5 mm the calcification blooming artifact was subtracted in the application of the mixture of Gaussian filtering and K- Clustering algorithm, and the value was close to the actual calcification region. These results may help to accurately diagnose coronary artery calcification stenosis.

Field Application of Insulation Curing Method with Double Bubble Sheets Subject to Cold Weather (이중버블시트를 이용한 단열양생공법의 한중콘크리트 현장적용)

  • Hong, Seak-Min;Baek, Dae-Hyun;Kim, Jong;Jeon, Chung-Kun;Han, Min-Cheol;Han, Cheon-Goo
    • Proceedings of the Korean Institute of Building Construction Conference
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    • 2008.05a
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    • pp.57-60
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    • 2008
  • This study investigated the results of insulation heat curing method using double layer bubble sheet in slab concrete and mass concrete in cold weather environment. First of all, when double bubble sheets are applied, it was shown that slab concrete was protected from early freezing by remaining between 6 and 15℃ even in case outside temperature drops -9℃ below zero until the 2nd day from piling, and in the case of mass concrete, with the maximum temperature difference between the center and surface less than 4℃, crack occurrence index was close to 2 and no hydration heat crack occurred by internal constraint. The insulation heat preservation curing method using the double bubble sheet applied in this field prevented early freezing owing to stable curing temperature management, deterring concrete strength development delay at low temperature, and obtained the needed strength. Also, it was proven that the method is highly effective and economic for cold weather concrete quality maintenance through curing cost reduction like construction period shortening and labor cost reduction, etc by reducing the process of temporary equipment installation and disassembling.

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A Study on the Identification of Aeroacoustic Noise and Noise Reduction for a Vacuum Cleaner (청소기의 공력소음 특성 파악 및 저소음화에 관한 연구)

  • 전완호;백승조;김창준;허남건
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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    • 2002.05a
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    • pp.633-638
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    • 2002
  • The vacuum cleaner that has no dust bag generates very high level annoying noise. The dominant noise source is the 2$\^$nd/ BPF tone of the rotating impeller. In order to reduce the noise, we identify the acoustic characteristics and reduce the noise of the vacuum cleaner and centrifugal fan. The resonance phenomenon is observed in blade passages and we found out that the resonance frequency is very close to the 2$\^$nd/ BPF. In order to reduce this high-level peak noise, new impeller is designed in this paper. The trailing edge of new impeller is inclined and this makes the flow interactions between the rotating impeller and the stationary diffuser vane occurs with some phase shift. The performance of new impeller is similar to the old one but the overall SPL is reduced about 3.6dBA. The SPL of BPF is reduced about 6dBA and 2$\^$nd/ BPF is reduced about 20dBA. The vacuum cleaner, which uses newly developed centrifugal fan, generate more comfortable noise than the old model and the strong tonal sound was dramatically reduced.

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Study on a seismic slit shear wall with cyclic experiment and macro-model analysis

  • Jiang, Huanjun;Lu, Xilin;Kwan, A.K.H.;Cheung, Y.K.
    • Structural Engineering and Mechanics
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    • v.16 no.4
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    • pp.371-390
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    • 2003
  • The concept of the seismic slit shear wall was proposed in the early 1990's. A series of experimental and theoretic studies on the wall with reinforced concrete short connecting beams cast in the slit were carried out. In this paper another type of slit shear wall is studied. It is one with vertical slit purposely cast within the wall, and the rubber belt penetrated by a part of web shear reinforcement as seismic energy-dissipation device is filled in the slit. Firstly, an experiment under cyclic loading was carried out on two shear wall models, one slit and the other solid. The failure mechanism and energy-dissipation capacity are compared between the two different models, which testifies the seismic performance of the slit wall improved significantly. Secondly, for engineering practice purpose, a macroscopic analytical model is developed to predict the nonlinear behavior of the slit shear wall under cyclic loading. The mechanical properties of each constituent elements of this model are based on the actual behavior of the materials. Furthermore, the effects of both the axial force and bending moment on the shear behavior are taken into account with the aid of the modified compression-field theory. The numerical results are verified to be in close agreement with the experimental measurements.

On Customer Participation and Its Effect in Developing New Products of Foodservice Industry (외식 신상품 개발에 식품 위생과 고객 자발적 행위의 효과 측정)

  • Lee, Sun-Ho
    • Culinary science and hospitality research
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    • v.13 no.4
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    • pp.232-242
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    • 2007
  • Consumers are not simply consuming products anymore. They now take part in developing new products. Thus, it is essential that we devise a variety of consumer-oriented marketing strategies to keep close relationships with consumers. The purposes of this study were as follows: 1) to explore the relationship between customer participation and surveys on its effect, 2) to compare groups with respect to customer participation, and 3) to see whether there is a cause-effect relationship between the customer participation and surveys on its effect. Frequency analysis, correlative analysis and discriminate analysis were used to analyze the data. The results of testing hypotheses can be summarized as follows. we find that, as for customer participation factors, there is significant relationships among survey factors including customer satisfaction, cost reduction, customers' prior occupations. The current analysis exhibits favorable results in the customer participation and such factors. The analysis shows that there is significant difference between the active groups and the passive groups in all the new product development related factors; customer satisfaction, cost reduction, customers' prior occupations. Finally, this perhaps indicates that the result of the survey depends on whether firms are positive or negative in introducing customer participation.

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