• The KSFM Journal of Fluid Machinery
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• v.14 no.3
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• pp.23-27
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• 2011

Due to a roots type medium vacuum pump is operated in condition of $1{\sim}10^{-3}$ torr vacuum, it could be applied for production and process of industrial parts, such as precise processing, vaporization, enrichment, separation, casting, metaling, welding, transportation. Therefore, the demand of this pump is increasing nowadays in our industrial markets of semiconductor, electric, electronic, automobile, material, environmental and transporting industries. However, the pumps are almost imported, because the domestic pumps are inferior in fields of vacuum range as under $10^{-1}$torr, relevant techniques(design, fabrication, casting, test, etc.) to the imported ones. In this study, essential parts of the development pump are designed with using of CFD and 3D decodes, FEM for analysing strength and deformation, generated heat, vibration and noise control, and are casted with using of mechanochemistry techniques for decreasing of weights, increasing of heat resistances and abrasion durability of materials for pump caing and impellers especially. Besides, in order to achieve ultimate vacuum around $10^{-3}$torr, this pump is composed of 6 stages, among which 1st stage is operated separately from remained stages. Additionally, a test rig for prototype pumps(300$m^3/h$ and 2,500$m^3/h$) is designed and procured as to apply for multi-staged rootz type vacuum pump, with modification of the test method recommended by KS B 6314 "Positive-displacement oil-sealed rotary vacuum pumps".

• Journal of the Korea institute for structural maintenance and inspection
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• v.17 no.4
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• pp.75-83
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• 2013

This paper presents a series of test result in order to study fire resistance capacity of the Near-Surface-Mounted (NSM) Carbon Fiber Reinforced Polymer (CFRP) plate, which are tensile test of CFRP under various temperature loading, temperature loading test of epoxy and bond test of NSM CFRP to concrete under various temperature loading. From the tests, it was found that NSM retrofit method had high efficiency in strengthening concrete under ordinary temperature. However, the strength of the system was able to be drastically decreased even a little increase of surrounding temperature. Especially, bond capacity begins to disappear when the surrounding temperature approaches the glass transition temperature of epoxy. Therefore, it is necessary to improve the fire resistance capacity of both fiber reinforced polymer reinforcement and epoxy for bonding in order to develop safe fire resistance design of structure.

• Journal of Korean Society of Steel Construction
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• v.17 no.4 s.77
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• pp.481-490
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• 2005

This paper summarizes the full-scale test results on the CFT column-to-flat plate connections subjected to gravity loading. CFT construction has gained wide acceptance in a relatively short time in domestic building construction practice due to its various structural and construction advantages. Constructing an underground parking floor as a flat plate system is often regarded as essential for both cost savings and rapid construction. Efficient details for CFT-column-to-flat-plate connections have not been proposed yet, however, and their development is urgently needed. Based on some strategies that maximize economical field construction, several connecting schemes were proposed and tested based on a full-scale model. The test results showed that the proposed connection details can exhibit punching shear strength and connection stiffness comparable to or greater than those of their R/C flat plate counterpart.

• Journal of Korean Society of Steel Construction
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• v.19 no.2
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• pp.211-221
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• 2007

A structural reliability analysis of fatigue truck model for fatigue failure of highway steel bridges was performed by applying the Miner's fatigue damage rule expressed as a function of various random variables affecting fatigue damage. Among the variables, the statistical parameters for equivalent moment, impact factor, and loadometer were obtained by analyzing recently measured domestic traffic data, whereas the parameters on fatigue strength, girder distribution factor, and headway factor of the measured data available in the literature were used. The effects of various fatigue truck models, fatigue life, ADTT, fatigue detail category, loadometer, and gross vehicle weight of fatigue truck on the reliability index of fatigue damage were analyzed. It is expected that the analytical results presented herein can be used as a basic background material in the calibration of both fatigue design truck and fatigue load factor of LRFD specification.

• Tunnel and Underground Space
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• v.18 no.4
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• pp.289-299
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• 2008

Based on the case study on the causes for the failure of cutting slope composed of weathered rock and soil, the factors influencing the design of a cutting slope have been examined, This type of rock and soil is widely distributed on the region whose parent rock is granite. To analyze the stability of the cutting slope, the following series of progress has been conducted: (1) ground characterization by geological survey and ground investigation, (2) the safety factor examination by limit equilibrium analysis and numerical analysis and (3) the comparison and analysis of rainfall and failure history. As a result, the main factors to cause the failure is determined to be the decrease of shear strength in the upper parts whose ground condition is weakened during localized heavy rain. Moreover, the analysis indicates the failure is also closely related to the groundwater inflow path. On the base of this investigation, a reinforcement method is proposed to ensure the stability of the cutting slope.

• Journal of muscle and joint health
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• v.15 no.1
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• pp.62-72
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• 2008

Purpose: There has been a need to integrating the self-help program for arthritis with the Tai Chi for arthritis(SHTCA). The purpose of this study was to develop and to examine the effect of SHTCA for arthritis applying the nine movement Tai Chi. Method: This study was designed the pre-post test, quasi-experimental design. A total 47 participants were recruited in W-city in Korea, an experimental group(26) and a control group(21) at pre-test, but after the eight weeks the composition of the groups were changed to 22 experimental group and 15 control group. The experimental group participated in the SHTCA once a week for eight weeks. SHTCA program consisted of understanding of the arthritis, contracting of the promise, exercise for muscle strength and joint flexibility and the nine movements of Tai Chi exercise. The measures used to examine the effect of the SHTCA were shoulder flexibility, back flexibility, grasping power, balance, abdominal obesity rates, perception of health status, and EQ-5D standardized five dimensions, mobility, self-care, usual activities, pain/discomfort, and anxiety/depression. Results: At The completion of the eight weeks of SHTCA applying the nine movement Tai Chi, the experimental group reported a significance in a number of variables compared to those of the control group: the right shoulder flexibility(p=.018), left shoulder flexibility(p=.031), right grasping power(p=.014), left grasping power(p=.024), the perception of health status(p=.005) and abdominal obesity rates(p=.027). Conclusion: This SHTCA applying the nine movement Tai Chi would be helpful on right shoulder flexibility, left shoulder flexibility, right grasping power, left grasping power, abdominal obesity rates and the perception of health status for arthritis patients.

• Journal of Biomedical Engineering Research
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• v.24 no.6 s.81
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• pp.501-507
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• 2003

Medical devices for helping the rehabilitation of the patients such as orthoses and prostheses should be designed to be strong enough. For the strength design, operational load should be identified first. Furthermore. medical devices are susceptible to dynamic load or shock frequently due to its characteristics. These type of the load may be identified by installing the sensors directly. However, it can modify the natural properties of the structures. Therefore, operational load should be identified indirectly from the system characteristics and responses such as vibrations. In this paper, the basic formulation of the indirect load identification is reviewed and the problems of conventional approach are checked. Then, the new approach based upon the principal component analysis is proposed and the validity of the proposed method is demonstrated using experiments.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.13 no.8
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• pp.3301-3306
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• 2012

In LED chip packaging, die bonding is a very important process which fixes the LED chip on the lead frame to provide enough strength for the next process. Conventional pick-up device of the die bonder is simply operated by up and down motion of a collet and an ejector pin. However, this method may cause undesired problems such as position misalignment and/or severe die damage when the pick-up device reaches the die. In this study, to minimize the position alignment error and die damage, a die bonder is developed by adopting a new pick-up head for precise alignment and high speed feeding. To evaluate structural stability of the designed system, required finite element model of the die bonder is generated, and structural analysis is performed. Vibration analysis of the pick-up head is also performed using developed finite element model at operation frequency range. As a result of the analysis, deformation, stress, and natural frequency of the die bonder are investigated.

• Journal of Distribution Science
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• v.19 no.12
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• pp.33-43
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• 2021

Purpose: This paper aims to determine features of the relationship between human development, tourism and national brand. Research design, data and methodology: ranking indicators, cluster analysis, K means method, correlation analysis. Results: The analysis covers data for 95 countries for 2019. The number of countries is justified by the availability of comparable data for calculations. A direct relationship between the indicators for the entire sample has been revealed in the result of the correlation analysis. However, this relationship has not been confirmed for the groups of countries that were formed through the cluster analysis. Spearman Rank Order and Kendall Tau Correlations have been calculated for the five obtained clusters. In two of the five clusters, the relationship between the indicators has not been found. A strong negative link between all the indicators has been detected in the cluster with average index values. A strong positive link between TTCI and BSI has been revealed in the group of countries with the best index values. A strong positive link between TTCI and HDI has been found in the group of countries with the worst index values. Conclusions: The analysis demonstrates that there is a relationship between BSI, TTCI and HDI, and while this link is observed for the sample as a whole, it is not homogeneous for groups of countries.

• Nano
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• v.13 no.12
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• pp.1850147.1-1850147.14
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• 2018

In this work, water-soluble and blue-emitting carbon nanodots (CDs) were synthesized from apple peels for the first time via one-step hydrothermal method. The synthetic route is facile, green, economical and viable. The as-prepared CDs were characterized thoroughly by transmission electron microscopy (TEM), X-ray diffraction (XRD), Raman, Fourier transform infrared (FT-IR), X-ray photoelectron (XPS), fluorescence and UV-Vis absorption spectroscopy in terms of their morphology, surface functional groups and optical properties. The results show that these CDs possessed ultrasmall size, good dispersivity, and high tolerance to pH, ionic strength and continuous UV irradiation. Significantly, the CDs had fast and reversible response towards temperature, and the accurate linear relationship between fluorescence intensity and temperature was used to design a novel nanothermometer in a broad temperature range from 5 to $65^{\circ}C$ facilely. In addition, the fluorescence intensity of CDs was observed to be quenched immediately by Cr(VI) ions based on the inner filter effect. A low-cost Cr(VI) ions sensor was proposed employing CDs as fluorescent probe, and it displayed a wide linear range from 0.5 to $200{\mu}M$ with a detection limit of $0.73{\mu}M$. The practicability of the developed Cr(VI) sensor for real water sample assay was also validated with satisfactory recoveries.