• Proceedings of the Korean Powder Metallurgy Institute Conference
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• 2000.04a
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• pp.9-10
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• 2000

An important business-field of world-wide steel-industry is the coating of thin metal-sheets with zinc, zinc-aluminum and aluminum based materials. These products mostly go into automotive industry. in particular for the car-body. into building and construction industry as well as household appliances. Due to mass-production, the processing is done in large continuously operating plants where the mostly cold-rolled metal-strip as the substrate is handled in coils up to 40 tons unwind before and rolled up again after passing the processing plant which includes cleaning, annealing, hot-dip galvanizing / aluminizing and chemical treatment. In the liquid Zn, Zn-AI, AI-Zn and AI-Si bathes a combined action of corrosion and wear under high temperature and high stress onto the transfer components (rolls) accounts for major economic losses. Most critical here are the bearing systems of these rolls operating in the liquid system. Rolls in liquid system can not be avoided as they are needed to transfer the steel-strip into and out of the crucible. Since several years, ceramic roller bearings are tested here [1.2], however, in particular due to uncontrollable Slag-impurities within the hot bath [3], slide bearings are still expected to be of a higher potential [4]. The today's state of the art is the application of slide bearings based on Stellite\ulcorneragainst Stellite which is in general a 50-60 wt% Co-matrix with incorporated Cr- and W-carbides and other composites. Indeed Stellite is used as the bearing-material as of it's chemical properties (does not go into solution), the physical properties in particular with poor lubricating properties are not satisfying at all. To increase the Sliding behavior in the bearing system, about 0.15-0.2 wt% of lead has been added into the hot-bath in the past. Due to environmental regulations. this had to be reduced dramatically_ This together with the heavily increasing production rates expressed by increased velocity of the substrate-steel-band up to 200 m/min and increased tractate power up to 10 tons in modern plants. leads to life times of the bearings of a few up to several days only. To improve this situation. the Mechanical Alloying (MA) TeChnique [5.6.7.8] is used to prOduce advanced Stellite-based bearing materials. A lubricating phase is introduced into Stellite-powder-material by MA, the composite-powder-particles are coated by High Energy Milling (HEM) in order to produce bearing-bushes of approximately 12 kg by Sintering, Liquid Phase Sintering (LPS) and Hot Isostatic Pressing (HIP). The chemical and physical behavior of samples as well as the bearing systems in the hot galvanizing / aluminizing plant are discussed. DependenCies like lubricant material and composite, LPS-binder and composite, particle shape and PM-route with respect to achievable density. (temperature--) shock-reSistibility and corrosive-wear behavior will be described. The materials are characterized by particle size analysis (laser diffraction), scanning electron microscopy and X-ray diffraction. corrosive-wear behavior is determined using a special cylinder-in-bush apparatus (CIBA) as well as field-test in real production condition. Part I of this work describes the initial testing phase where different sample materials are produced, characterized, consolidated and tested in the CIBA under a common AI-Zn-system. The results are discussed and the material-system for the large components to be produced for the field test in real production condition is decided. Outlook: Part II of this work will describe the field test in a hot-dip-galvanizing/aluminizing plant of the mechanically alloyed bearing bushes under aluminum-rich liquid metal. Alter testing, the bushes will be characterized and obtained results with respect to wear. expected lifetime, surface roughness and infiltration will be discussed. Part III of this project will describe a second initial testing phase where the won results of part 1+11 will be transferred to the AI-Si system. Part IV of this project will describe the field test in a hot-dip-aluminizing plant of the mechanically alloyed bearing bushes under aluminum liquid metal. After testing. the bushes will be characterized and obtained results with respect to wear. expected lifetime, surface roughness and infiltration will be discussed.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.15 no.1
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• pp.299-305
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• 2014

The purpose of this study was to determine the effect of a task-related circuit training in improving the function of lower extremity and quality of life in patient with hemiplegia. A total 25 paients with hemiplegia selected, the volunteers were randomly divided into a task-related circuit training group of 13 people and a treadmill training group of 12 people. The two groups received treadmill training for 30 minutes a day, 5 days a week for 8 weeks. The experimental group was additionally received the task related circuit training for 30 minutes. The assessment comprised of testing the patient's strength, walking, balance ability(strength of knee, balance ability, 10m walking test) and making use of the stroke impact scale. Post treatment, compared to the treadmill training group, task-related circuit training group showed significantly increased strength of knee extensor, flexor and balance ability, stoke impact scale(p<.05). The findings of this study suggest that a task-related circuit training can improve function of lower extremity and quality of life in patient of hemiplegia. Further studies with a greater sample size and a various intervention are needed to generalize the findings of the present study.

• Research in Plant Disease
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• v.18 no.4
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• pp.331-337
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• 2012

Citrus melanose is one of important disease in citrus cultivation, reducing quality of citrus fruits and resulting in economic loss. Like other diseases in citrus, melanose was mainly protected by chemical fungicide in the field. Recently, alternative method of disease control is highly required due to the side effect of the chemicals. In this study four rhizobacterial strains TRH423-3, MRL408-3, THJ609-3, and TRH415-2 are selected by dual-culture testing its antifungal activity against Diaporthe citri causing citrus melanose. To investigate the protection efficacy of the selected rhizobacterial strains to citrus melanose, the bacteria were pre-treated on citrus leaves following inoculation with melanose pathogen. Pre-treatment with all selected rhizobacterial strains showed disease suppression in which the levels of protection rates were different by the rhizobacterial strains. Additional treatment with the rhizobacterial strains after the pathogen inoculation enhanced protection rates in all cases. The strain MRL408-3 and TRH423-3 were identified as Burkholderia gladioli, TRH415-2 as Pseudomons fluorescens and THJ609-3 as Pseudomonas pudia as a result of analyzing the internal transcript spaces of the rhizobacterial strains rDNA. The selected rhizobacterial strains may be valuable as biological control agents in the environment-friendly citrus farm in which chemical application is limited.

• Korean Journal of Soil Science and Fertilizer
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• v.47 no.6
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• pp.457-463
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• 2014

This study was carried out to find out major factors to mitigate carbon emission using Life Cycle Assessment (LCA). System boundary of LCA was confined from sowing to packaging during vegetable production. Input amount of agri-materials was calculated on 2007 Income reference of white radish, chinese cabbage and chive produced at open field and film house published by Rural Development Administration. Domestic data and Ecoinvent data were used for emission factors of each agri-material based on the 1996 IPCC guideline. Carbon footprint of white radish was 0.19 kg $CO_2kg^{-1}$ at open fields, 0.133 kg $CO_2kg^{-1}$ at film house, that of chinese cabbage was 0.22 kg $CO_2kg^{-1}$ at open fields, 0.19 kg $CO_2kg^{-1}$ at film house, and that of chive was 0.66 kg $CO_2kg^{-1}$ at open fields and 1.04 kg $CO_2kg^{-1}$ at film house. The high carbon footprint of chive was related to lower vegetable production and higher fuel usage as compared to white radish and Chinese cabbage. The mean proportion of carbon emission was 35.7% during the manufacturing byproduct fertilizer; white radish at open fields was 50.6%, white radish at film house 13.1%, Chinese cabbage at outdoor 38.4%, Chinese cabbage at film house 34.0%, chive at outdoor 50.6%, and chive at film house 36.0%. Carbon emission, on average, for the step of manufacturing and combustion accounted for 16.1% of the total emission; white radish at open fields was 4.3%, white radish at film house 15.6%, Chinese cabbage at open fields 6.9%, Chinese cabbage at film house 19.0%, chive at open fields 12.5%, and chive at film house 29.1%. On the while, mean proportion of carbon footprint for the step of $N_2O$ emission was 29.2%; white radish at open fields was 39.2%, white radish at film house 41.9%, Chinese cabbage at open fields 34.4%, Chinese cabbage at film house 23.1%, chive at open fields 28.8%, and chive at film house 17.1%. Fertilizer was the primary factor and fuel was the secondary factor for carbon emission among the vegetables of this study. It was suggested to use Heug-To-Ram web-service system, http://soil.rda.go.kr, for the scientific fertilization based on soil testing, and for increase of energy efficiency to produce low carbon vegetable.

• Journal of Korean Tunnelling and Underground Space Association
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• v.19 no.3
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• pp.475-488
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• 2017

Wear prediction of TBM disc cutters is a very important issue for hard rock TBMs as number of cutter head intervention. In this regard, some model such as NTNU, Gehring model, CSM models have been used to predict disc cutter wear and intervention interval. There are some deficiencies in these models. This paper developed a new test method for wear prediction for TBM disc cutter and proposed a new abrasion index. In this regard, different abrasivity indices along with their testing methods are explained. A comparative study is performed to develop the predictability of different cutter life evaluation methods and index. The evaluation of the new methods proposed in this paper shows a very good agreement with the actual cutter life and intervention interval length. The proposed tester and index can be easily used to predict the intervention interval length and cutter wear evaluation in both planning and construction stages of a TBM tunneling project.

• Safety and Health at Work
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• v.10 no.4
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• pp.482-503
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• 2019

Introduction: A new third version of the Copenhagen Psychosocial Questionnaire (COPSOQ III) has been developed in response to trends in working life, theoretical concepts, and international experience. A key component of the COPSOQ III is a defined set of mandatory core items to be included in national short, middle, and long versions of the questionnaire. The aim of the present article is to present and test the reliability of the new international middle version of the COPSOQ III. Methods: The questionnaire was tested among 23,361 employees during 2016-2017 in Canada, Spain, France, Germany, Sweden, and Turkey. A total of 26 dimensions (measured through scales or single items) of the middle version and two from the long version were tested. Psychometric properties of the dimensions were assessed regarding reliability (Cronbach α), ceiling and floor effects (fractions with extreme answers), and distinctiveness (correlations with other dimensions). Results: Most international middle dimensions had satisfactory reliability in most countries, though some ceiling and floor effects were present. Dimensions with missing values were rare. Most dimensions had low to medium intercorrelations. Conclusions: The COPSOQ III offers reliable and distinct measures of a wide range of psychosocial dimensions of modern working life in different countries; although a few measures could be improved. Future testing should focus on validation of the COPSOQ items and dimensions using both qualitative and quantitative approaches. Such investigations would enhance the basis for recommendations using the COPSOQ III.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.21 no.9
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• pp.32-38
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• 2020

Cargo train braking uses the pressure changes in the air braking pipe to operate the braking tightening and releasing service repeatedly. Air-braking release failure means partial braking caused by a failure of the variable load valve after the driver handling the brake release. This phenomenon causes wheel flaws while driving a wagon, resulting in wheel breakage or train derailment. This study developed the air-braking release failure proof valve considering the technical requirements of the railway operation corporations. In addition, a durability test of the valve was carried out using a braking performance simulator, and its operating performance was evaluated from the pneumatic history under cyclic braking conditions. The warranty life of this valve was assessed by performing 160,000 cycles of testing of 12 prototypes in accordance with the zero-failure test method, considering the number of braking cycles while driving the wagon. During the durability test, the pneumatic input time, output time, and release velocity were almost constant. The warranty life of this valve was 59,860 times the 95% confidence level, which means that it can be operated without trouble for four years when the valve is installed in the bogie of the wagon.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.11 no.4
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• pp.147-156
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• 2011

Though a dozen of different software life cycle models are suggested, there is no universal model which can satisfy all the characteristics of software. Organizations mix and match different life cycle models to develop a model more tailored for their systems and capabilities. We suggest overlapped-concurrent development life cycle model that is more suitable in various software development environment. Firstly, we divided the development process into abstract and implementation stage. Abstract stage is from software concept phase to detailed design starting time, and implementation stage is from detailed design phase to system testing phase. Next, the abstract stage introduced the overlapped phase concept that begins the next phase when the step is completed 20% by applying pareto's law. In the implementation stage, we introduced the concurrent development which the several phases are performed some time as when one use-case (UC) is completed the next development phase is started immediately. The proposed model has an advantage that it can reduce the inefficiency of development resource greatly. This model can increase the customer satisfaction with a great product at a low cost and on a short schedule. Also, this model can contribute to increase the software development success rate.

• Korean Journal of Agricultural Science
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• v.32 no.1
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• pp.29-42
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• 2005

During a long journey of agricultural products from the production area to markets, the quality of agricultural products was always affected by some degree of vibration. The vibration input during the transportation may cause serious agricultural product injury, and this damage is particularly severe whenever the vegetable inside package is free to bounce, and is vibrated at its resonant frequency. The objectives of this study were to determine the resonant frequency of the oriental melon and to investigate the relationships between resonant frequency and physical properties of the oriental melon such as mass, volume and major and minor axes. In this study vibration testing device was constructed to determine the vibration response of the oriental melon in frequency ranges of 5 to 150 Hz. The computer program for controlling the vibration shaker and the function generator and measuring the vibration characteristics of the oriental melon was developed. The ranges of resonant frequency and peak acceleration at resonance of the oriental melon were 51 to 73 Hz and 1.24 to 1.92 G-rms, respectively. The resonant frequency and the peak acceleration decreased with the increase of the sample mass, volume, major and minor axes of the oriental melon. Multiple regression models for resonant frequency and peak acceleration of the oriental melon as a function of mass, major axis and minor axis of the sample were developed and analyzed.

• Journal of the Korean Wood Science and Technology
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• v.36 no.3
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• pp.70-84
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• 2008

A series of the studies on the applied physical properties of domestic species have been conducted last three years. Pinus densiflora was one of the three species examined for the first year. Because the same apparatus and experimental procedures were used for all species, their results can be easily comparable. The experiments for sorption property were conducted with 20- and 80-mesh wood powder and resulted in their EMC's and sorption isotherms at various heating conditions. The thermal conductivity and diffusivity, and electric resistance and volumetric electric resistivity were measured with a thermal-wire device and a high electric resistance meter. The differences of the thermal and electric properties between quarter- and flat-sawn specimens were observed, which was partially attributed to their anatomical differences. An acoustic measurement system was used to evaluate dynamic MOE and internal friction. This paper provides the useful fundamental data for designing a wood structure, correcting a portable resistance-type moisture meter, and nondestructive testing wood.