• Journal of the Korea Institute of Information and Communication Engineering
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• v.16 no.4
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• pp.785-792
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• 2012

In this paper, a current-voltage characteristics of n-channel junctionless and inversion mode(IM) MuGFET, and p-channel junctionless and accumulation mode(AM) MuGFET has been measured and analyzed for the application in high speed and low power switching devices. From the variation of the threshold voltage and the saturation drain current with the substrate bias voltages, their variations in IM devices are larger than junctionless devices for n-channel devices, but their variations in junctioness devices are larger than AM devices for p-channel devices. The variations of transconductance with substrate biases are more significant in p-channel devices than n-channel devices. From the characteristics of subthreshold swing, it was observed that the S value is almost independent on the substrate biases in n-channel devices and p-channel junctionless devices but it is increased with the increase of the substrate biases in p-channel AM devices. For the application in high speed and low power switching devices using the substrate biases, IM device is better than junctionless devices for n-channel devices and junctionless device is better than AM devices for p-channel devices.

• Journal of Microbiology and Biotechnology
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• v.4 no.2
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• pp.146-150
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• 1994

Production of poly-$\beta$-hydroxybutyrate (PHB) in fed-batch fermentation was studied. Utilization of carbon for PHB biosynthesis was investigated by using feeding solutions with different ratios of carbon to nitrogen (C/N). It was observed that at a high C/N ratio carbon source was more preferably utilized for PHB accumulation while its consumption for cellular metabolism appeared to be more favored at a low C/N value. A high cell concentration (184 g/l) was achieved when ammonium hydroxide solution was fed to control the pH, which was also utilized as the sole nitrogen source. For the mass production of PHB, two-stage fed-batch operations were carried out where PHB accumulation was observed to be stimulated by switching the ammonium feeding mode to the nitrogen limiting condition. A large amount of PHB (108 g/l) was obtained with cellular content of 80% within 50 hrs of operation.

• Proceedings of the Korea Concrete Institute Conference
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• 1999.10a
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• pp.389-392
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• 1999

Fatigue is a process of progressive permanent internal structural change in a material subjected to repeitive stresses. These change may be damaging and result in progressive growth of cracks and complete fracture if the stress repetitins are sufficiently large. For structural members subjected to cyclic loads, the continuous and irrecoverable damage processes are taking place. These processes are referred as the cumulative damage processes due to fatigue loading. Moreover, increased use of high strength concrete makes the fatigue problem more important because the cross-section and dead weight are reduced by using high strength concrete. The purpose of this study is to investigate the shear fatigue behavior of reinforced concrete beams according to shear reinforcement ratio and concrete compressive strength under repeated loadings. For this purpose, comprehensive static and fatigue tests of reinforced concrete beams were conducted. The major test variables for the fatigue teats are the concrete strength and the amount of shear reinforcements. The increase of deflections and steel strains according to load repetition has been plotted and analyzed to explore the damage accumulation phenomena of reinforced concrete beams. An analytical model for shear fatigue behavior has been introduced to analyze the damage accumulation under fatigue loads. The failure mode and fatigue lives have been also studied in the present study. The comparisons between analytical results and experimental data show good correlation.

• Tribology and Lubricants
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• v.34 no.6
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• pp.292-299
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• 2018

The objective of this research is to investigate the impact of engine oil aging on PM(Particulate Matter), exhaust gases, and DPF. It is widely known that the specification of a lubricant and its consumption in an ICE considerably influences the release of regulated harmful emissions under normal engine operating conditions. Considering DPF clogging phenomena associated with lubricant-derived soot/ash components, a simulated aging mode is designed for DPF to facilitate engine dynamometer testing. A PM/ash accumulation cycle is developed by considering real-world engine operating conditions for the increment of engine oil consumption and natural DPF regeneration for ash accumulation. The test duration for DPF aging is approximately 300 h with high- and low-SAPs engine oils. Detailed engine lubricant properties of new and aged oils are analyzed to evaluate the effect of engine oil degradation on vehicle mileage. Furthermore, physical and chemical analyses are performed using X-CT, ICP, and TGA/DSC to quantify the engine oil contribution on the PM composition. This is achieved by sampling with various filters using specially designed PM sampling equipment. Using high SAPs engine oil causes more PM/ash accumulation compared with low SAPs engine oils and this could accelerate fouling of the EGR in the engine, which results in an increase in harmful exhaust gas emissions. These test results on engine lubricants under operating conditions will assist in the establishment of regulated and unregulated toxic emissions policies and lubricant quality standards.

• Journal of the Korean Regional Science Association
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• v.11 no.1
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• pp.79-91
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• 1995

As an exit to solve the economic depression of the development countries in the early twentieth century, the 'old international division of labor' developed. The economic crisis(i.e., under-consumption crisis) was due to the absence of the mode of regulation compatible with the extensive regime of accumulation(i.e., "Fordist" regime). The crisis was solved by the state intervention through the creation on institutions in order to increase the level of consumption. Until the late 1960s when "high Fordism" reached(i.e., a harmonious relation between the monopoly mode of regulation and the intensive accumulation of capital), the developed core countries enjoyed a remarkable economic growth. The external market was not a necessity for the economic growth because there were increases in labor productivity and proportional increases in real wages and thus increases in consumption level. In the 1970s, however, the core faced with economic crisis again. Due to the breakdown of the postwar "Fordist" regime of capital accumulation and the post 1973 world depression, the core needed the Third World as a solution for their internal and international economic crisis. Thus the 'new international division of labor'(NIDL) arose. The "Fordist" method of production(i.e., the divisions of production process) led to the territorial division of labor and to the detailed division of labor. The aim of the NIDL is to exploit reserve armies of labor on a world scale and thus to reduce production costs. According to the NIDL model, the Third World countries have been developing by the core countries' investment on mainly labor-intensive industries and thus have been playing an important role in the global economy. And the NIDL theorists argue that multinational corporations have increasingly invested in the Third World nations and contributed to the economic growth in those regions. Tables presented in the paper show that the global trend since the 1970s does not follow the argument exactly as the NIDL theorists predicted. On the contrary, the core countries focus on developing technology, adopting the automation of production process, and trading within the core countries rather than on investing in the periopheral countries. The continuing investment of multinational corporations into the periphery is not because of cheap labor force but because of the market potentials in the regions. Majority of corporations of the core tries to reduce production costs by investing in technological development more intensively and also by changing regional strategies (i.E., investment from metropolitan areas to medium - or small - size cities, focusing on agglomeration economy, boosting regional diversification, etc.) within their own countries. The main purpose of the paper is to review and to criticize the NIDL theory based on some empirical data.IDL theory based on some empirical data.

• Transactions of the Korean Society of Mechanical Engineers
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• v.16 no.5
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• pp.838-848
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• 1992

The objective of the study is to provide a theoretical tools for analyzing the fracture of leyered composites with a center crack. It is assumed that the composite is composed of successive accumulation of the fiber layer and resin layer with the fiber layer being perfectly bonded to the resin layer except the region of a center crack. In-plane shear loading (Mode II) and the anti-plane shear loading (Mode III) are considered separately. Boundary value problems are formulated by using a plane theory of elasticity and governing equations are reduced to a Fredholm integral equation of a second kind. The equation is solved numerically and the stress intensity factors are obtained. The normalized Mode II and Mode III stress intensity factors are evaluated for various combinations of material properties and for various geometrical parametes.

• Journal of Korean Society for Atmospheric Environment
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• v.16 no.2
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• pp.89-102
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• 2000

A total of 318 particulate sample sets consisting of both fine PM(FPM : dp$\leq$2.5 ${\mu}{\textrm}{m}$) and coarse PM(CPM : 2.5${\mu}{\textrm}{m}$${\mu}{\textrm}{m}$) was collected by a dichotomous sampler in Suwon area from December 1996 to November 1997. The concentration of seven inorganic elements such as pb. Cr, Cd, Cu, Zn Fe and Na were determined from each sample using an AAS. The purpose of the study was to extensively investigate environmental behaviors of particulate matters and to provide air quality management schemes applying various statistical approaches. The mean concentrations of PM10 Results of correlation analyses indicated the existence of strong correlations among inorganic elements PM10 FPM CPM and various meterological variables. Our study also examined the degree of uncertainties whether the particular elements can be assorted into the accumulation mode or the coarse mode in their size distribution. Furthermore the analysis of the pollution rose showed graphically the direction of potential sources of particulate matters. According to statistical analyses of our data quantitative differences appeared in the pollution patterns between weekdays and weekends.

• Journal of Applied Biological Chemistry
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• v.56 no.2
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• pp.109-112
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• 2013

Azole fungicides are one of the most wide-spread antifungal compounds in agriculture and pharmaceutical applications. Their major mode of action is the inhibition of ergosterol biosynthesis, giving depletion of ergosterol, precursors and abnormal steroids. However, metabolic consequences of such inhibition, other than steroidal metabolitesare not well established. Comprehensive metabolic profiles of Saccharomyces cerevisiae has been presented in this study. Wild type yeast was treated either with glucose as control or azole fungicide (ketoconazole). Both polar metabolites and lipids were analyzed with gas chromatography-mass spectrometry. Approximately over 180 metabolites were characterized, among which 18 of them were accumulated or depleted by fungicide treatment. Steroid profile gives the most prominent differences, including the accumulation of lanosterol and the depletion of zymosterol and ergosterol. However, the polar metabolite profile was also highly different in pesticide treatment. The concentration of proline and its precursors, glutamate and ornithine were markedly reduced by ketoconazole. Lysine and glycine level was also decreased while the concentrations of serine and homoserine were increased. The overall metabolic profile indicates that azole fungicide treatment induces the depletion of many polar metabolites, which are important in stress response.

• Transactions of the Korean Society of Automotive Engineers
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• v.18 no.6
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• pp.98-104
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• 2010

An experimental investigation was conducted to analyze the effects of EGR ratio on the combustion, exhaust emissions characteristics and size distributions of particulate matter in a single cylinder diesel engine with common-rail injection system fueled with biodiesel derived from soybean. In order to analyze the combustion, exhaust emissions and measurement of size distributions of particulate matter were carried out under various EGR ratio which was varied from 20~60% and the results were compared to those of results without EGR. The experimental results show that ignition delay was extended and maximum value of rate of heat release (ROHR) was decreased according to increasing of EGR ratio. In addition, oxidies of nitrogen ($NO_x$) emissions were reduced but soot emissions were increased under increasing of EGR ratio. However, under higher EGR ratio region, soot was slightly decreased. And then the particulate size distribution shows that high exhaust gas temperature restrain the formation of soluble organic fraction (SOF) which were beyond the accumulation mode (100~300nm) and lead to increase of nuclei mode particles.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.13 no.8
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• pp.3862-3879
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• 2019

More and more problems for public security have occurred due to the limited solutions for drone detection especially for micro-drone in long range conditions. This paper aims at dealing with drones detection using a radar system. The radio frequency (RF) signals emitted by a controller can be acquired using the radar, which are usually too weak to extract. To detect the drone successfully, the static clutters and linear trend terms are suppressed based on the background estimation algorithm and linear trend suppression. The principal component analysis technique is used to classify the noises and effective RF signals. The automatic gain control technique is used to enhance the signal to noise ratios (SNR) of RF signals. Meanwhile, the empirical mode decomposition (EMD) based wavelet transform (WT) is developed to decrease the influences of the Gaussian white noises. Then, both the azimuth information between the drone and radar and the bandwidth of the RF signals are acquired based on the statistical analysis algorithm developed in this paper. Meanwhile, the proposed accumulation algorithm can also provide the bandwidth estimation, which can be used to make a decision accurately whether there are drones or not in the detection environments based on the probability theory. The detection performance is validated with several experiments conducted outdoors with strong interferences.