• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2012.10a
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• pp.743-749
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• 2012

Grunt (Stick-slip) noise happens between rear lining and drum on braking condition while vehicle is returning to steady position after nose-dive. The study presents a new testing and analysis methods for improving brake grunt noise on vehicle. Grunt noise is called a kind of stick slip noise with below 1kHz frequency that is caused by the surfaces alternating between sticking to each other and sliding over each other with a corresponding change in friction force. This noise is typically come from that the static friction coefficient of surfaces is much higher than the kinetic friction coefficient. For the identification of the excitation mechanism and improvement of grunt noise, it is necessary to study variable parameters of rear drum brake systems on vehicle and to implement CAE analysis with stick slip model of drum brake. The aim of this study has been to find solution parameters throughout test result on vehicle and dynamo test. As a result of this study, it is generated from stick slip between rear lining and rear drum and it can be solved to reduce contact angle of lining with asymmetric and is effected not only brake drum strength but also rear brake size and brake factor.

• Journal of Astronomy and Space Sciences
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• v.29 no.2
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• pp.103-113
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• 2012

The ButterStar Observatory at the Dongducheon High School has been working for photographic observations of the Sun since October 16, 2002. In this study, we observed the Sun at the ButterStar observatory for 3,364 days from October 16, 2002 to December 31, 2011, and analyzed the photographic sunspot data obtained in 1,965 days. The correction factor $K_b$ for the entire observing period is 0.9519, which is calculated using the linear least square method to the relationship between the daily sunspot number, $R_B$, and the daily international relative sunspot number, $R_i$. The yearly correction factor calculated for each year varies slightly from year to year and shows a trend to change along the solar cycle. The correction factor is larger during the solar maxima and smaller during the solar minima in general. This implies that the discrepancy between a relative sunspot number, R, and the daily international relative sunspot number, $R_i$, can be reduced by using a yearly correction factor. From 2002 to 2008 in solar cycle 23, 35.4% and 64.6% of sunspot groups and 35.1% and 64.9% of isolated sunspots in average occurred in the northern hemisphere and in the southern hemisphere, respectively, and from 2008 to 2011 in solar cycle 24, 61.3% and 38.7% of sunspot groups and 65.0% and 35.0% of isolated sunspots were observed, respectively. This result shows that the occurrence frequency for each type of sunspot group changes along the solar cycle development, which can be interpreted as the emerging and decaying process of sunspot groups is different depending on the phase of solar cycle. Therefore, it is considered that a following study would contribute to the efforts to understand the dependence of the dynamo mechanism on the phase of solar cycle.

• Journal of Astronomy and Space Sciences
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• v.29 no.2
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• pp.181-189
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• 2012

To broaden the understanding of classical Cepheid structure, evolution and atmospheres, we have extended our continuing secret lives of Cepheids program by obtaining XMM/Chandra X-ray observations, and Hubble space telescope (HST) / cosmic origins spectrograph (COS) FUV-UV spectra of the bright, nearby Cepheids Polaris, ${\delta}$ Cep and ${\beta}$ Dor. Previous studies made with the international ultraviolet explorer (IUE) showed a limited number of UV emission lines in Cepheids. The well-known problem presented by scattered light contamination in IUE spectra for bright stars, along with the excellent sensitivity & resolution combination offered by HST/COS, motivated this study, and the spectra obtained were much more rich and complex than we had ever anticipated. Numerous emission lines, indicating $10^4$ K up to ${\sim}3{\times}10^5$ K plasmas, have been observed, showing Cepheids to have complex, dynamic outer atmospheres that also vary with the photospheric pulsation period. The FUV line emissions peak in the phase range ${\varphi}{\approx}0.8-1.0$ and vary by factors as large as $10{\times}$. A more complete picture of Cepheid outer atmospheres is accomplished when the HST/COS results are combined with X-ray observations that we have obtained of the same stars with XMM-Newton & Chandra. The Cepheids detected to date have X-ray luminosities of log $L_X{\approx}28.5-29.1$ ergs/sec, and plasma temperatures in the $2-8{\times}106$ K range. Given the phase-timing of the enhanced emissions, the most plausible explanation is the formation of a pulsation-induced shocks that excite (and heat) the atmospheric plasmas surrounding the photosphere. A pulsation-driven ${\alpha}^2$ equivalent dynamo mechanism is also a viable and interesting alternative. However, the tight phase-space of enhanced emission (peaking near 0.8-1.0 ${\varphi}$) favor the shock heating mechanism hypothesis.

• Journal of the Korean Society for Railway
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• v.14 no.2
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• pp.100-108
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• 2011

This paper investigates the structural stability and reliability on improving performance of flexible brake pad used in high speed train. To this end, an improved model of flexible pad was obtained through structural analysis. Brake pad specimens were subjected to modal, stroke and endurance tests to examine the dynamic characteristics and mechanical stability. The hot spot generation with increasing rotational speed was observed on chassis dynamometer equipment and then the structurally uniform contact between the disc and pad was achieved. The temperature distribution of flexible pad was measured using the infrared camcorder. Hence, the proposed flexible pad showed the better structural stability and thermal energy emission.

• Proceedings of the Korea Water Resources Association Conference
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• 2016.05a
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• pp.194-194
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• 2016

Gansu, located in the northwestern region, is a typical agricultural province of arid, semiarid in China. The shortage of water resources is the biggest obstacle of Gansu Province's development, and the dry farming water-saving is the eternal theme of Gansu agricultural sustainable development. In recent years, intensify reform in Gansu, has walked out a successful way in the agricultural water-saving. Using the integrated river basin governance as opportunity, the total water-using quantity was regarded as rigidity to retrain, distributed to counties (districts), irrigated areas, towns, associations, groups step by step. Agricultural water price was substantially increased, with the surface water price from about $0.1RMB/m^3$ to more than $0.2 RMB/m^3$, and the ground water from zero to more than $0.1RMB/m^3$. Simultaneously, the difference water prices and over-quota water progression price markup were carried out. The transaction of water rights was encouraged to impel the peasant to establish the consciousness of saving-water. The regulatory documents were formulated to standardize the scope, condition, mode, program etc. of agriculture water-rights transaction, to guarantees the transaction of water rights is carries out in order. The pattern of farming was optimized and adjusted, reducing the high water-consumption crop, increasing economic crops with high benefit and low water-consumption, developing industrialized agricultures such as green house. The relative engineering and measuring facility were comprehensively improved, with the anti-seepage of canal system and the enforcement of dynamo-electric well, developing high-efficient water-saving irrigation and overall metering facilities. The water fine-grained management has realized, and obvious water-saving effect has obtained: water-using rate in the irrigation area by river water has brought up to 0.57 from 0.52, and by well water up to 0.84 from 0.76. Although the water price has increased, the proportion that the water rate expenditure accounted for the cost lasts decline, and the farmers' income has gone up. The peasants express, the used water is few, and it is few to till land, but the income is many, and life is better.

• Journal of KIBIM
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• v.12 no.1
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• pp.42-54
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• 2022

BIM facilitates data transparency and consistency through three-dimensional parametric modeling and promotes the accurate managing and sharing of project information. In Korea, however, BIM-based detailed design of architectural interior finishes required during the Construction Documents phase increases the burden on architectural firms due to frequent design changes and manual workload. Therefore, the purpose of this study was to establish rule-based modules using parametric modeling that automates repetitive tasks that occur during the detailed design of interior finishing. Interviews with practitioners were conducted to analyze the major finishing elements. Of these floors, walls, and ceilings, which were the most rudimentary and common items, were selected as the subjects of the study. The modules developed in this study have two functions. One is to create new finish types, and the other is the automatic modeling of new types into rooms. For these functions, parameters that belonged to each finish and room element in a BIM model were analyzed and valid parameters directly used for parametric modeling were derived. Then, based on these parameters, rule-based modules for three elements, I.e., floors, walls, and ceilings were constructed with Revit Dynamo, and the effectiveness of the modules was verified with a pilot test. In conclusion, this study suggested a series of processes for automatic finishing to improve the efficiency of BIM-based architectural detailed design of finishes and to contribute in solving the chronic problems occuring during current design processes.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.22 no.3
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• pp.139-143
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• 2022

In this study, Among the electromagnetic induction power generation (EMG) techniques, the design specifications of the RFPM were set, and a suitable test prototype was manufactured through finite element analysis (FEM, 2D) required for characteristic calculation. In addition, a dedicated testing device (Dynamo-Tester) was designed and manufactured to measure and analyze the test prototype. The test product was measured with a test device and the result is analyzed to suggest a method that can be applied by generating as much output power as possible to charge the battery of the wearable IT device using actual kinetic energy of the human body. As a result of the test, the output power was 1.679W and the efficiency was 79.31% under the conditions of rotation speed of 780.9rpm, torque of 0.264kgf/cm, and load current of 73.6~73.9mA. Therefore, it was analyzed that it was possible to charge the wearable device with the output of the ultra-small RFPM pendulum generator.

• Journal of the Korea Institute of Building Construction
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• v.22 no.2
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• pp.171-182
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• 2022

The regular assessment of a building is important to understand structural safety and latent risk in the early stages of building life cycle. However, methods of traditional assessment are subjective, atypical, labor-intensive, and time-consuming and as such the reliability of these results has been questioned. This study proposed a method to bring accurate results using a 3D laser scanner and integrate them in Building Information Modeling (BIM) to visualize defective condition. The specific process for this study was as follows: (1) semi-automated data acquisition using 3D laser scanner and python script, (2) scan-to-BIM process, (3) integrating and visualizing defective conditions data using dynamo. The method proposed in this study improved efficiency and productivity in a building assessment through omitting the additional process of measurement and documentation. The visualized 3D model allows building facility managers to make more effective decisions. Ultimately, this is expected to improve the efficiency of building maintenance works.

• Clean Technology
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• v.16 no.4
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• pp.265-271
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• 2010

The deactivated diesel oxidation catalyst(DOC) was remanufactured by ultrasonic wave treatment with various solutions, followed by active component re-impregnation. The catalytic performance and surface properties of remanufactured DOC were studied at various remanufacturing conditions. The proper ultrasonic-wave cleaning time at various solutions and optimal re-impregnation amounts of active component for the best catalytic performance were investigated. The catalytic performance tests on the conversions of CO and THC(total hydrocarbon) were also carried out at various temperatures by catalytic reaction test unit using bypass gas from the diesel engine dynamo system. It was found that the catalytic performance of DOC remanufactured with the high-temperature air washing, ultrasonic wave cleaning at acidic/basic solutions and active component re-impregnation method was recovered to 90% level of its activity compared to that of the fresh DOC, which was caused by removing the deactivating materials from the surface of the DOC through the analyses of catalyst performance test and their characterization by Optical microscope, EDX, ICP, TGA, and porosimeter.

• International conference on construction engineering and project management
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• 2017.10a
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• pp.14-23
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• 2017

In high-density high-rise cities such as Hong Kong, buildings account for nearly 90% of energy consumption and 61% of carbon emissions. Therefore, it is important to study the design of buildings, especially high-rise buildings, to achieve lower carbon emissions in the city. The carbon emissions of a building consist of embodied carbon from the production of construction materials and operational carbon from energy consumption during daily operation (e.g., air-conditioning and lighting). An integrated analysis of both types of carbon emissions can strengthen the design of low carbon buildings, but most of the previous studies concentrated mainly on either embodied or operational carbon. Therefore, the primary objective of this study is to develop a holistic methodology framework considering both embodied and operational carbon, in order to enhance the sustainable design of low carbon high-rise buildings. The framework will be based on the building information modeling (BIM) technology because BIM can be integrated with simulation systems and digital models of different disciplines, thereby enabling a holistic design and assessment of low carbon buildings. Structural analysis program is first coupled with BIM to validate the structural performance of a building design. The amounts of construction materials and embodied carbon are then quantified by a BIM-based program using the Dynamo programming interface. Operational carbon is quantified by energy simulation software based on the green building extensible Markup Language (gbXML) file from BIM. Computational fluid dynamics (CFD) will be applied to analyze the ambient wind effect on indoor temperature and operational carbon. The BIM-based framework serves as a decision support tool to compare and explore more environmentally-sustainable design options to help reduce the carbon emissions in buildings.