• The Transactions of the Korean Institute of Electrical Engineers B
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• v.53 no.12
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• pp.691-699
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• 2004

SRM(Switched Reluctance Motor) drives require the accurate position information of the rotor. These informations are generally provided by a tacho generator or digital shaft-position encoder These speed sensors lower the system reliability and require special attention to noise. This paper describes a new approach to estimating SRM speed from measured terminal voltages and currents for speed sensorless control. The described method is based on the sliding mode observer. The rotor speed and position observers are estimated by the adaptation law using the real and estimated currents. However, the conventional adaptive sliding mode observer based on the variable structure control theory has some disadvantages that the estimated values including the high-frequency chattering and the steady state error generated due to the infinite feedback gain chosen and the discontinuous control input. To reduce the chattering and steady state error, an integrator is also inserted in the sliding mode observer strategy. The described adaptive sliding mode observer decreases the vibration to the switching hyper-plane of the sliding mode by adding integrator. The described methodology incorporates the Lyapunov algorithm to drive the rotor speed and the stator resistance such that it can overcome the problem of sensitivity in the face of SRM parameter variation. Also, without any mechanical information. The rotor speed of SRM is obtained form adaptive scheme. The described method is verified through the simulation and experiment.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.13 no.4
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• pp.131-140
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• 1993

A new model which requires one branch of main curves for the model calibration is developed based on the assumption that the weighting factor accounting for the pore blockage effect against air entry, $P_a({\theta})$, in Mualem's Model III-1 has a linear relation to the dimensionless pore radius r. The proposed model simulates experimental data more accurately than existing models which require one branch of main curves for the model calibration. Previous study showed that Model III-1 is the most appropriate model among domain models which require two branches of main curves for the model calibration. In comparison of the proposed model with Model III-1, both simulate hysteresis curves with almost the same accuracy. The proposed model can be applied efficiently in analyzing the unsaturated flow.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.32 no.1
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• pp.130-136
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• 2009

Estimation of mortality behavior of a industrial property are useful for calculating depreciation and making management decisions relating to property. The common methods of computing depreciation require an estimation of service life, and some methods may require an estimate of life expectancy. Estimation of service life and life expectancy can be computed from a smoothed and extended life table of original life tables developed through life analysis techniques. Several actuarial techniques are available to construct a life table for depreciation application. Of these methods, the graphic approach and graduation by mathematical formula are the most widely used in the field of depreciation. A commonly used technique of smoothing and of extending the life table is to fit a lows type survivor curves to the observed retirement rate by the least square method. In this paper, estimates of depreciation rate based on directly observed data of the domestic petrochemical equipments are presented.

• Journal of Photoscience
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• v.8 no.2
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• pp.61-66
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• 2001

Using maize green- and white-leaf tissue, we have examined the effect of various chemicals on cytoplasmic leakage with respect to the light requirement or chloroplast targeting for their activities. Oxyfluorfen, oxadiazon, diuron, and paraquat, which are known as representative herbicides acting on plant chloroplasts, caused the electrolyte leakage only in the green tissues, whereas 2, 4-dinitrophenol, rose bengal (singlet oxygen producing chemical) and methyl-jasmoante (senscence-stimulating chemical) play a role both in green- and white-tissue. Benzoyl(a) pyrene, generating superoxide radical upon light illumination, functions only in white tissues. Tralkoxydim, metsulfuron-methyl and norflurazon showed no effect in two tested plant samples. In terms of light requirement in electrolyte leakage activity, diuron, oxyfluorfen, oxadiazon, rose bengal, and benzoyl(a) pyrene absolutely require the light for their functions, but other chemicals did not. based on these results, we could classify into four different response types according to whether chemicals require light or chlroplasts for their action. This classification is likely to be applied to simply and rapidly identify the requirement of light and chlroplasts for the actions of chemicals, thereby it makes easy to characterize many new herbicides that their action mechanisms are unclear, and to elucidate the mode of action of them.

• Radiation Oncology Journal
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• v.34 no.3
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• pp.209-215
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• 2016

Purpose: We sought to determine if organ preservation (OP) with neoadjuvant chemoradiation (CRT) was feasible in patients with sinonasal cancer determined to require exenteration. Materials and Methods: Twenty patients were determined to require exenteration for definitive treatment from 2005 to 2014. Fourteen patients underwent OP and 6 patients received exenteration with adjuvant CRT. Exenteration free survival (EFS), locoregional control (LRC), progression-free survival (PFS), and overall survival (OS) were estimated. Results: Five patients (36%) receiving OP had complete disease response at time of surgery. With a median follow-up of 18.8 months, EFS was 62% at 2 years for patients undergoing OP. At 2 years, there were no significant differences in LRC, PFS or OS (all all p > 0.050) between the groups. Less grade 3 or greater toxicity was seen in patients undergoing OP (p = 0.003). Visual function was preserved in all patients undergoing OP. Conclusion: For patients with sinonasal cancer, OP may avoid exenteration, offering similar disease control and improved toxicity.

• Journal of Korean Society of Water and Wastewater
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• v.24 no.4
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• pp.387-394
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• 2010

The influent COD of municipal wastewater has been divided into 4 fractions; readily soluble biodegradable, slowly particulate biodegradable, soluble and particulate unbiodegradable COD. The mathematical modeling of biological wastewater treatment processes and the design and operation of nutrient removal plants require a reliable and accurate estimate of the composition of influent wastewater COD. COD utilization rate is proportional to the oxygen uptake rate(OUR), so a batch biodegradation test with OUR measurement has been effectively used for the determination of COD fractionation. But the mathematical model of COD utilization and heterotrophs synthesis is essential to interpret the OUR measurement. Mamais method is another method for determining readily biodegradable soluble COD. Like the OUR test method, batch biodegradation test is necessary but it does not require mathematical model. These two methods for determining COD fractionation are introduced here in detail. Experimental results showed that COD composition by Mamais method is not different to that by OUR test method so, either of them can be used.

• Journal of Ocean Engineering and Technology
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• v.24 no.2
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• pp.25-33
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• 2010

Collision between vessels may lead to structural damage and penetration of hulls. The structural damage of a hull may eventually bring about global collapse of the hull girder and outflow of oil, which would contaminate seawater. Therefore, various regulations require the strength of a vessel after collision to satisfy given criteria, and owners usually request collision analyses to confirm the structural safety of their vessels. In the process of designing a vessel to satisfy the collision strength criteria, the strength has been assessed mostly by conducting collision analyses using numerical techniques, such as dynamic, non-linear, finite-element analysis. Design is an inherently iterative process during which many changes are necessary due to the endless needs for reinforcement and modification. Numerical techniques are not adequate for coping with a situation in which collision analysis is frequently required to provide the revised results that reflect the repetitive changes in designs. Numerical techniques require a lot of time and money to conduct in spite of recent improvements in computing power and in the productivity of modeling tools. Therefore, in this paper, an analytical technique is introduced and a collision problem is idealized and simplified using reasonable assumptions based on appropriate background. The technique was applied to an example of an actual FPSO and verified by comparing the results with results from the numerical technique. A good correlation was apparent between the results of the analytical and numerical techniques.

• Progress in Superconductivity and Cryogenics
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• v.14 no.2
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• pp.20-23
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• 2012

With continuous development of the 2nd generation HTS conductor, the critical current of the conductor is also increasing. However, many applications require more than 2 conductors in parallel to transport large current. Applications such as HTS power cables and some HTS current leads usually need much larger transport current than that provided by a single conductor and they require more than several tens of HTS conductors. In the case of parallel connection of multiple HTS conductors, the current distribution depends on the contact resistance of each conductor at the terminals for DC operation. The non-uniform distribution of the terminal resistances results in a non-uniform distribution of the current. The resultant current non-uniformity affects on the measurement of the I-V curve and the thermal performance of the multiple conductors. This paper describes the I-V curves obtained from multiply connected HTS conductors with different terminal contact resistances to investigate the relationship between the distorted I-V curve and heat generation.

• Proceedings of the KIEE Conference
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• 1996.07c
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• pp.1582-1584
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• 1996

The polycrystalline silicon thin film transistors (poly-Si TFT) are the most promising candidate for active matrix liquid crystal displays (AMLCD) for their high mobilities and current driving capabilities. The leakage current of the poly-Si TFT is much higher than that of the amorphous-Si TFT, thus larger storage capacitance is required which reduces the aperture ratio fur the pixel. The offset gated poly-Si TFTs have been widely investigated in order to reduce the leakage current. The conventional method for fabricating an offset device may require additional mask and photolithography process step, which is inapplicable for self-aligned source/drain ion implantation and rather cost inefficient. Due to mis-alignment, offset devices show asymmetric transfer characteristics as the source and drain are switched. We have proposed and fabricated a new offset poly-Si TFT by applying photoresist reflow process. The new method does not require an additional mask step and self-aligned ion implantation is applied, thus precise offset length can be defined and source/drain symmetric transfer characteristics are achieved.

• Asia pacific journal of information systems
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• v.15 no.1
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• pp.115-133
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• 2005

This study is to develop an information security management model(ISMM) for small and medium sized enterprises(SMEs). Based on extensive literature review, a five-pillar twelve-component reference ISMM is developed. The five pillars of SME's information security are: centralized decision making, ease of management, flexibility, agility and expandability. Twelve components are: scope & organization, security policy, resource assessment, risk assessment, implementation planning, control development, awareness training, monitoring, change management, auditing, maintenance and accident management. Subsequent survey designed and administered to expose experts' perception on the importance of these twelve components revealed that five out of tweleve components require relatively immediate attention than others, especially in SME's context. These five components are: scope and organization, resource assessment, auditing, change management, and incident management. Other seven components are policy, risk assessment, implementation planning, control development, awareness training, monitoring, and maintenance. It seems that resource limitation of SMEs directs their attention to ISMM activities that may not require a lot of resources. On the basis of these findings, a three-phase approach is developed and proposed here as an SME ISMM. Three phases are (1) foundation and promotion, (2) management and expansion, and (3) maturity. Implications of the model are discussed and suggestions are made for further research.