• Journal of the Korean Society of Safety
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• v.32 no.1
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• pp.15-20
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• 2017

A large amount of research has been performed on the rolling contact fatigue(RCF) life of bearings, since it directly affects the safety and reliability of mechanical systems. It is well known that rolling contact fatigue life is influenced by several parameters including contact pressure, oil contamination by water or metal particles, and the surface conditions of bearings. However, the detailed damage mechanisms involved in rolling contact fatigue have not been clearly identified yet. In this paper the effects of water contamination of the lubricant and surface roughness of bearing steel on the rolling contact fatigue life were investigated. Two types of specimens with different surface roughness values were prepared through turning and lapping operations. They were tested under two different lubrication conditions, i.e. oil lubricant with 100% of oil and the water contaminated condition with 80% of oil and 20% of water using the rolling contact fatigue testing machine. The surface damage induced by the rolling contact fatigue was observed by using atomic force microscope(AFM). Experimental results show that the rolling contact fatigue life, $L_{10}$ was reduced by 24 to 33% depending on the lubrication condition. The reduction of fatigue life in the range of 53 to 57% was also observed at different surface roughness conditions.

• Bioinformatics and Biosystems
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• v.1 no.1
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• pp.67-72
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• 2006

The aim of this paper is to discuss the effect of missing values in detecting differentially expressed genes in a cDNA microarray experiment in the context of a one sample problem. We conducted a cDNA micro array experiment to detect differentially expressed genes for the metastasis of colorectal cancer based on twenty patients who underwent liver resection due to liver metastasis from colorectal cancer. Total RNAs from metastatic liver tumor and adjacent normal liver tissue from a single patient were labeled with cy5 and cy3, respectively, and competitively hybridized to a cDNA microarray with 7775 human genes. We used $M=log_2(R/G)$ for the signal evaluation, where Rand G denoted the fluorescent intensities of Cy5 and Cy3 dyes, respectively. The statistical problem comprises a one sample test of testing E(M)=0 for each gene and involves multiple tests. The twenty cDNA microarray data would comprise a matrix of dimension 7775 by 20, if there were no missing values. However, missing values occur for various reasons. For each gene, the no missing proportion (NMP) was defined to be the proportion of non-missing values out of twenty. In detecting differentially expressed (DE) genes, we used the genes whose NMP is greater than or equal to 0.4 and then sequentially increased NMP by 0.1 for investigating its effect on the detection of DE genes. For each fixed NMP, we imputed the missing values with K-nearest neighbor method (K=10) and applied the nonparametric t-test of Dudoit et al. (2002), SAM by Tusher et al. (2001) and empirical Bayes procedure by $L\ddot{o}nnstedt$ and Speed (2002) to find out the effect of missing values in the final outcome. These three procedures yielded substantially agreeable result in detecting DE genes. Of these three procedures we used SAM for exploring the acceptable NMP level. The result showed that the optimum no missing proportion (NMP) found in this data set turned out to be 80%. It is more desirable to find the optimum level of NMP for each data set by applying the method described in this note, when the plot of (NMP, Number of overlapping genes) shows a turning point.

• Proceedings of the Korean Geotechical Society Conference
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• 2009.03a
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• pp.1225-1234
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• 2009

As the Wenchuan Earthquake was of high magnitude and shallow seismic focus, it caused great damage and serious geo-hazards. By the field investigation and remote-sensing interpretation after the earthquake and by using means of GIS, the distribution of geo-hazards triggered by the earthquake was analyzed and the conclusions are as follows: (1) the earthquake geo-hazards showed the feature of zonal distribution along the earthquake fault zone and linear distribution along the rivers; (2) the distribution of earthquake geo-hazards had a marked hanging wall effect, for the development density of geo-hazards in the hanging wall of earthquake fault was obviously higher than that in the foot wall and the width of strong development zone in the hanging wall was about 10 km; (3) the topographical slope was a main factor which controlled the development of earthquake geo-hazards and a vast majority of geo-hazards were distributed on the slopes of 20 to 50 degrees; (4) the earthquake geo-hazards had a corresponding relationship with the elevation and micro-landform, for most hazards happened in the river valleys and canyon sections below the elevation of 1500 to 2000 m, particularly in the upper segment of canyon sections (namely, the turning point from the dale to the canyon). Thin ridge, isolated or full-face space mountains were most sensitive to the seismic wave, and had a striking amplifying effect. In these areas, collapses and landslides were most likely to develop; (5) the study also showed that different lithologies determined the types of geo-hazards, and usually, landslides occurred in soft rocks, while collapses occurred in hard rocks.

• Journal of the Korean Solar Energy Society
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• v.22 no.3
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• pp.47-56
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• 2002

The office is an excellent candidate for implementing daylighting techniques because of the relatively high electric lighting power densities and long daytime use pattern. The quantity of light available for a space can be translated in term of the amount of energy savings through a process of a building energy simulation. To get significant energy savings in general illumination, the electric lighting system must be incorporated with a daylight - activated dimmer control. A prototype configuration of an office interior has been established and the integration between the building envelope and lighting and HVAC systems is evaluated based on computer modeling of a lighting control facility. First of all, an energy-efficient luminaire system is designed for both a totally open-plan office interior and a partitioned office. A lighting design and analysis program, Lumen-Micro 2000 predicts the optimal layout of a conventional fluorescent lighting fixture to meet the designed lighting level and calculates unit power density, which translates the demanded amount of electric lighting energy. A dimming control system integrated with the contribution of daylighting has been applied to the operating of the artificial lighting. Annual cooling load due to lighting and the projecting saving amount of cooling load due to daylighting under overcast diffuse sky are evaluated by a computer software, ENER-Win. In brief, the results from building energy simulation with measured daylight illumination levels and the performance of lighting control system indicate that daylighting can save over 70 percent of the required energy for general illumination in the perimeter zones through the year. A 25 % of electric energy for cooling may be saved by dimming and turning off the luminaires in the perimeter zones.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.19 no.6
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• pp.1-8
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• 2005

The quantity of light available for a space can be translated in term of the amount of energy savings through a process of a building energy simulation. To get significant energy savings in general illumination, the electric lighting system must be incorporated with a daylight - activated dimmer control. A prototype configuration of an once interior has been established and the integration between the building envelope and lighting and HVAC systems is evaluated based on computer modeling of a lighting control facility. First of all, an energy-efficient luminaire system is designed and the lighting analysis program, Lumen-Micro 2000 predicts the optimal layout of a conventional fluorescent lighting future to meet the designed lighting level and calculates unit power density, which translates the demanded met of electric lighting energy. A dimming control system integrated with the contribution of daylighting has been applied to the operating of the artificial lighting. Annual cooling load due to lighting and the projecting saving amount of cooling load due to daylighting under overcast diffuse sky m evaluated by computer software ENER-Win. In brief, the results from building energy simulation with measured daylight illumination levels and the performance of lighting control system indicate that daylighting can save over 70 percent of the required energy for general illumination in the perimeter zones through the year A 25[%] of electric energy for cooling and almost all off heating energy may be saved by dimming and turning off the luminaires in the perimeter zones.

• Korean Journal of Microbiology
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• v.43 no.3
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• pp.166-172
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• 2007

ERM proteins transfer the methyl group to $A_{2058}$ in 23S rRNA, which reduces the affinity of MLS (macrolide-lincosamide-streptogramin B) antibiotics to 23S rRNA, thereby confer the antibiotic resistance on micro-organisms ranging from antibiotic producers to pathogens and are classified into monomethyltransferase and dimethyltransferase. To investigate the differences between mono- and dimethyltransferase, tirD, a representative monomethylase gene was cloned in Escherichia coli from Streptomyces fradiae which contains ermSF, dimethylase gene as well to overexpress the TlrD for the first time. T7 promoter driven expression system successfully overexpress tlrD as a insoluble aggregate at $37^{\circ}C$ accumulating to around 55% of the total cell protein but unlike ErmSF, culturing at temperature as low as $18^{\circ}C$ did not make insoluble aggregate of protein into soluble protein. Coexpression of Thioredoxin and GroESL, chaperone was not helpful in turning into soluble protein either as in case of ErmSF. These results might suggest that differences between mono- and dimethylase could be investigated on the basis of the characteristics of protein structure. However, a very small amount of soluble protein which could not be detected by SDS-PAGE conferred antibiotic resistance on E. coli as in ErmSF which was expected from the activity exerted by monmethylase in a cell.

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.15 no.2
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• pp.85-94
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• 2016

Lane Designation is defined as reasonable road management to ensure the road safety and enhance road efficiency. While the lane designation system was abolished in 1999, it was redefined because of the increasing number of large vehicles in the passing lane, violent on driving and traffic accidents in 2000. The needs of improvement on operating the lane designation has been increasing more in recent due to the low ratio of compliance with the system and difficulties to keep the right lane due to need of turning and demand of widening of designates lane for two-wheeled vehicles and truck. In this study, we presented the improvement plan through the question survey, simulation analysis, safety evaluation. It found a problem that the low-speed vehicle is to use the upper level roadway, difficulties of supervision, the imbalance in the lane use, imbalance traffic and does not match the international standards. This study suggested five different alternatives through the survey. micro simulation has used in order to examine each alternative by management effectiveness and feasibility. It analyzed the traffic speed, efficiency, traffic balance of alternatives. Also, safety evaluation conducted in terms of the range of field-of-view to ensure the easiness of field of view by various configurational difference between the vehicles. By the analysis results of such indicators, This study presents proposals for improvement in operating designated lane that low-speed-big-sized vehicles keep to the right lane, and high-speed-small sized vehicles keep to the left lane.