• Journal of Power Electronics
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• v.17 no.2
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• pp.490-500
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• 2017

Fuel cell (FC) is a promising power supply in electric vehicles (EV); however, it has poor dynamic performance and short service life. To address these shortcomings, a super capacitor (SC) is adopted as an auxiliary power supply. In this study, the frequency decoupling control method is used in electric vehicle energy system. High-frequency and low-frequency demand power is provided by SC and FC, respectively, which makes full use of two power supplies. Simultaneously, the energy system still has rapidity and reliability. The distributed power system (DPS) of EV requires DC-DC converters to achieve the desired voltage. The stability of cascaded converters must be assessed. Impedance-based methods are effective in the stability analysis of DPS. In this study, closed-loop impedances of interleaved half-bridge DC-DC converter and phase-shifted full-bridge DC-DC converter based on the frequency decoupling control method are derived. The closed-loop impedance of an inverter for permanent magnet synchronous motor based on space vector modulation control method is also derived. An improved Middlebrook criterion is used to assess and adjust the stability of the energy system. A theoretical analysis and simulation test are provided to demonstrate the feasibility of the energy management system and the control method.

• Journal of the Korean Geosynthetics Society
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• v.14 no.4
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• pp.45-58
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• 2015

Even though the plate bearing test (PBT) to evaluate the load baring capacity and the field density test to evaluate the relative density are mainly used for quality control of soil compaction in Korea, use of the dynamic cone penetrometer test (DCPT) and the dynamic plate bearing test (DPBT) considering economic feasibility, rapidity, and suitability for field conditions increase to use for quality control of soil compaction. In this study, bearing capacity and relative density of subgrade with thickness of 20 cm, 30 cm, and 40 cm are estimated using PBT, DCPT, DPBT and field density test in three field compaction tests, and the relationship among various compaction evaluation methods is analyzed and discussed.

• Journal of Korean Society of Forest Science
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• v.80 no.2
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• pp.232-236
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• 1991

The efficacy of berberine sulphate, a fluorochrome having binding properties with both DNA and RNA, was investigated for the detection of mycoplasma-like organisms(MLOs) in jujube(Zizyphus jujuba), paulownia(Paulownia tomentosa), mulberry(Morus alba) trees and periwinkle (Catharanthus roseus) plant. When examined under fluorescence microscope, berberine sulphate-stained sections of diseased samples showed distinct MLO-specific fluorescent particles in the phloem area, while such fluorescence was absent in the healthy ones. This staining technique was proved to be a very accurate method for the diagnosis of MLO infections in woody and herbaceous plants. Furthermore, the cheap and easy procedure could be used to test a great number of samples on MLO infections with reliability and rapidity.

• Journal of Internet Computing and Services
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• v.10 no.3
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• pp.95-101
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• 2009

As RFID technology has been developed rapidly, its technical potential has it be widely used in many industrial fields. Particularly, in the physical distribution industry, the introduction of RFID has enormously contributed to effectively monitoring locations and information of products in real-time. Also, a significant decline in tag prices and RFID related technical competitiveness enabled each tag to be managed much more minutely by attaching it to an item, not a pallet nor a container. However, if a very large volume of tag data are continuously flowed into a RFID middleware with limited hardware resources, its entire data processing time may become considerably longer. Therefore, specific technologies are in great demand to handle and further to reduce the load of the middleware. In this paper, we proposed a mobile agent-based software module to efficiently reduce the load of the middleware by pre-processing a lot of tag data while items are in transit. Simulation results show that using the proposed software module considerably enhances the speed of processing tag data than otherwise. This behavior increases the tag recognition rate in a certain time limit and improves reliability of RFID middlewares.

• Journal of The Korean Society of Grassland and Forage Science
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• v.15 no.1
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• pp.13-18
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• 1995

Seedling development among reciprocal FI hybrids and their parents, Lotus comiculatus and L renuis, were studies using a simple method of measuring cotyledon area. Cotyledon area attached to the plant could be measured with simple rapid method. Cotyledons expanded very rapidly during the first week, then slightly expanded until maximum size was reached around 3 weeks after emergence. Cotyledon area upon emergence was correlated with seed size (P=0.05), but after emergence there was a divergence in cotyledon expansion rate. Rapidity of photosynthetic area development was determinant factor for seedling growth of trefoil species. 2 $\times$ m2 and 1 $\times$ m2 among the hybrids promised the possibility increasing seedling vigor of birdsfoot trefoil.

• Journal of Korea Technical Association of The Pulp and Paper Industry
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• v.30 no.2
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• pp.47-54
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• 1998

Refining is one of the most important processes of fiber treatment that provides optical and physical properties of final paper products. The evaluation method of refining progress is usually freeness (CSF) or wetness (SR) test because of its rapidity and convenience. However, there are some deficiencies in using freeness or wetness test to evaluate pulp fibers accurately because its results are more influenced by fines contents than extent of fibers treatment. The objective of this study is to show the deficiency of wetness in evaluating the refining process. For this, beating is done by varying the beating load. Handsheets are made after beating until 25 and $32^{\circ}C$ SR, and then paper properties are measured. Refined fibers are analyzed by fiber length, fines contents, curl, kink, WRV, and zero-span tensile strength. The results show that longer beating time is required to reach the same wetness at lower beating load. There are differences in the average fiber length, distribution curve of fiber length, fines contents, curl, kink, WRV of long fiber fraction, drainage time, and zero-span tensile strength of rewetted sample at different beating load. At the low beating load in the same wetness, apparent density, breaking length, burst strength, and tear strength are higher, while opacity and air permeability are lower than those of the high beating load. Using Page s equation, which shows the relationship among tensile strength, intrinsic fiber strength, and interfiber bonding strength, interfiber bonding strength is calculated and analyzed to explain final paper properties. At $25^{\circ}C$ SR, interfiber bonding strength is only slightly higher at 2.5kgf beating load, while the intrinsic fiber strength is substantially higher. At $32^{\circ}C$ SR, intrinsic fiber strength is a little bit higher at 2.5kgf beating load, and interfiber bonding strength is remarkably higher than those of 5.6kgf beating load. These results can be used to explain the different properties of the final paper at selected beating loads.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.21 no.12
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• pp.1063-1070
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• 2008

The performance of an acoustic transducer is determined by the effects of many design variables, and mostly the influences of these design variables are not linearly independent of each other. To achieve the optimal performance of an acoustic transducer, we must consider the cross-coupled effects of the design variables. In this study, the variation of the performances of underwater acoustic transducer in relation to its structural variables was analyzed. In addition, the new optimal design scheme of an acoustic transducer that could reflect not only individual but also all the cross-coupled effects of multiple structural variables, and could determine the detailed geometry of the transducer with great efficiency and rapidity was developed. The validation of the new optimal design scheme was verified by applying the optimal structure design of a flextensional transducer which are the most common use for high power underwater acoustic transducer. With the finite element analysis(FEA), we analyzed the variation of the resonance frequency, sound pressure, and working depth of a flextensional transducer in relation to its design variables. Through statistical multiple regression analysis of the results, we derived functional forms of the resonance frequency, sound pressure, and working depth in terms of the design variables. By applying the constrained optimization technique, Sequential Quadratic Programming Method of Phenichny and Danilin(SQP-PD), to the derived function, we designed and verified the optimal structure of the Class IV flextensional transducer that could provide the highest sound pressure level and highest working depth at a given operation frequency of 1 kHz.

• Archives of design research
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• v.20
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• pp.51-58
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• 1997

This paper aims to aid a practical evaluation for screening out the design proposais under applying the IRDS system, which is developed a computer aided industrial design system as a computer application system. In this study, the author adopted 3 evaluation methods with criteria which have quantitative and qualitative attributes : the Intuitive Evaluation Methods(X), the Accumulative Evaluation Method(Y), the Benchmarking Evaluation Methods(Z). The results show that the 3 Methods have reciprocal relationships under reliability(r=0.0001). In analysis on the properties of the evaluation methods, the Evaluation Method (X) shows rapidity especially, the Evaluation Method (Y); relativity, the Evaluation Method(Z); importance respectively. The correlation analysis between the evaluation methods makes the null hypothesis denying, then we could adapt the research hypothesis. Therefore the correlation between them has positive relationship, and it shows thicker than the result of the 1st study.

• Asian Oncology Nursing
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• v.12 no.2
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• pp.186-193
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• 2012

Purpose: The purpose of this narrative study was to understand how family caregivers interpreted themselves life during caring for dying patients with gliobalstoma, and how they integrated these experiences into their personal biographies. Methods: Three family caregivers were recruited for the study. Data were collected through a series of audio-taped unstructured interviews and conversations with participants. The interviews and observation were conducted between October and November, 2011. Data were analyzed using psychosocial analytical methods that combined case based, in-depth staged analysis of narratives. Results: The life experiences of the family caregivers with a dying family member were summarized as, in their own voices, 'the repetition of gliobalstoma,' 'a smart patient,' 'being obsessed with rehabilitation treatment,' 'the frustration from nothing but just looking at the suffering of the patient,' and 'a stubborn son'. Conclusion: Caregiving was characterised by various roles and life changes from the moment of diagnosis. Family caregivers of brain tumor reported experiences similar to those described by caregivers of people with other cancers. What differed for this group was the rapidity of change and the need for immediate information and support to assist with caring for a person with high-grade glioma.

• The Journal of the Acoustical Society of Korea
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• v.22 no.8
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• pp.637-644
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• 2003

In this study, with the FEM we analyzed the variation of the resonance frequency, bandwidth, and sound pressure of the Tonpilz transducer in relation to its design variables. Through statistical multiple regression analysis of the results, we derived functional forms of the resonance frequency, bandwidth, and sound pressure in terms of the design variables. By applying the constrained optimization technique, SQP-PD, to the derived function, we determined the optimal structure of the transducer that could provide the highest sound pressure level at the resonance frequency of 30,000 Hz and having the -3 dB bandwidth more than 10%, The validity of the optimized results was confirmed through comparison of the optimal performance with that of the FEA. The optimal design method proposed could reflect all the cross-coupled effects of multiple structural variables, and could determine the detailed geometry of the transducer with great efficiency and rapidity.