• Journal of Advanced Marine Engineering and Technology
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• 제18권2호
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• pp.75-82
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• 1994

The existence of peroodic impulse noises in distribution line carrier (DLC) communication system is known to be the most serious obstacle for improving DLC communication quality in reliability and capacity. From the spectral points, impulse noises can be divided into baseband type and modulation type the noise width of whichs are much different each other. With each nose type, this study presents the basic characteristics in relation to what they originate from and how their spectrum properties are revealed. The baseband type impulse noise is normally caused from thyristor circuit running with low switching speed and the modulation type noise from the circuit of switching power supply. The base wave of modulation noise is shown to be the pulsuatic charging current to primary condenser in switching power circuit. The study result indicates also that placing the DLC carrier frequency away the band predominated by modulated noise especially from RCC type switching power circuit is very important in DLC design.

• 대한기계학회논문집B
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• 제27권9호
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• pp.1256-1261
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• 2003

Since the viscous effect increases as the size of device decreases, viscous-driven micropump is a promising mechanism in microscale applications. In the present study, a dual-rotor type pump which contains two counter-rotating cylinders for improving performance characteristics is proposed. First, for flows in the single-rotor type pump, the present unstructured grid simulation method is validated by comparing its results to the previous results. Next, the performance of the dual-rotor type pump is evaluated by the parametric studies and is compared to that of the previous single-rotor type pump. The flow characteristics are qualitatively similar to those of single-rotor type pump. However, the performance of the micropump with tandem rotors is still better than that of previous pumping type, e.g. much larger flow rate, smaller driving region, higher efficiency, and wider operation range.

• 전기학회논문지
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• 제56권5호
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• pp.933-937
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• 2007

A point plate type nonthermal plasma reactor, with a grounded cylindrical third electrode which closely- encompasses the needle point, have been investigated with an emphasis on the role of the third electrode. It was found that the point plate airgap, with the grounded third electrode, had a switching characteristic on its I V characteristics for negative and positive discharges, which is very different from that of a conventional point plate airgap without a third electrode. The corona discharge and ozone generation characteristics of the plasma reactor with the grounded cylindrical third electrode, such as the corona onset voltage. the breakdown voltage. the corona current. and the amount of output ozone, were influenced significantly by the height of the third electrode. and these characteristics can be controlled by adjusting the height of the third electrode.

• 수산경영론집
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• 제52권1호
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• pp.83-99
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• 2021

Fisheries policies are diversifying, including welfare programs for fishermen, revitalization of earfish and villages, and support for the sixth industrialization of fishing villages. In response to these policy changes, the purpose of this study is to categorize the fishing village fraternity, which is a local community, a fishery production organization, and a basic unit of a fishing village, and compares the characteristics of each type A number of indicators were selected by collecting data on the Categorization and evaluation of fishing villages fraternity and the statistical geographic information service. A number of indicators were extracted as representative factor variables using the principal component analysis, and then cluster analysis was performed to categorize the fishing village fraternity. This study was the first to attempt a comprehensive approach to revitalize the fishing village economy by using not only demographic and social characteristics, industrial and economic characteristics, but also regional characteristics. The characteristics of each type of fishing village fraternity find its significance in that it provides basic information that can be used in policy decisions. In order to strengthen the sustainability of the fishing community in the future and contribute to the sustainable development at the national level, the development of sustainable fishing village fraternity development indicators and follow-up studies on fishing village regeneration strategies will be needed.

• Tribology and Lubricants
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• 제20권4호
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• pp.209-217
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• 2004

Lubrication characteristics between a cylinder block and a valve plate for high speed bent-axis type hydraulic pump play an important role in volumetric efficiency and durability of pump. In this paper, a finite element method is presented for the computation of the pressure distribution between a cylinder block and a valve plate for high speed bent-axis type hydraulic pump. Also, a Runge-Kutta method is applied to simulate the cylinder block dynamics of three-degrees of freedom motion. From the results of computation, we can draw two major conclusions. One is related to the fluid film characteristics between a cylinder block and a valve plate and the other is related to the average leakage that is determined by the pressure gradient and the clearance near the discharge port. The numerical results of cylinder block dynamics were compared with the experimental results using eddy-current type gap sensors those are fixed at a pump housing.

• 한국초전도ㆍ저온공학회논문지
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• 제19권2호
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• pp.44-47
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• 2017

In this paper, the current limiting characteristics of the transformer type superconducting fault current limiter (SFCL) with the two coupled secondary windings due to its winding direction were analyzed. To analyze the dependence of transient fault current limiting characteristics on the winding direction of the additional secondary winding, the fault current limiting tests of the SFCL with an additional secondary winding, wound as subtractive polarity winding and additive polarity winding, were carried out. The time interval of quench occurrence between two superconducting elements comprising the transformer type SFCL with the additional secondary winding was confirmed to be affected by the winding direction of the additional secondary winding. In case of the subtractive polarity winding of the additional secondary winding, the time interval of the quench occurrence in two superconducting elements was shorter than the case of the additive polarity winding.

• 한국조명전기설비학회:학술대회논문집
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• 한국조명전기설비학회 1999년도 학술대회논문집-국제 전기방전 및 플라즈마 심포지엄 Proceedings of 1999 KIIEE Annual Conference-International Symposium of Electrical Discharge and Plasma
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• pp.11-16
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• 1999

Discharge characteristics research for high voltage and large current electric machinery design, the development of ozonizer with high yield and efficiency for environment improvement, generation of plasma & laser and EMI EMC are research fields of Enersy & Environment Electromagnetic Laboratory(EEEL) in the school of electrical & electronic engineering of Yeungnam University. On this paper, we would like to introduce the discharge and ozone generation characteristics of ozonizers designed and manufactured by EEEL. After starting research for fluid gas discharge characteristics early in the 1980's, high voltage nozzle(HVN) type ozonizer, neon lamp(Nelamp) type ozonizer, ozone lamp(Olamp) type ozonizer and multi-discharge type ozonizer(MDO) have been investigated since 1990.

• 한국물환경학회지
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• 제28권6호
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• pp.917-922
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• 2012

In order to improve applicability of a microbial fuel cell the laboratory-scaled study has been performed by adopting an air-cathode MFC system with high concentrated anaerobic slugies in this study. The concentrations of microbes are grouped into three types, Type A (TS 1.7%), Type B (TS 1.1%) and Type C (TS 0.51%). The open circuit voltage $(V_{oc})$ characteristics showed that the medium microbes concentration of 1.10% (Type B) kept a constant voltage of 1.0 V for 150 hours, which showed the longest time among three types (Type A and Type C). The discharge charge curves for a closed circuit with $500 \Omega$ also showed that Type B generated a stable discharge voltage of 0.8 V for a longer time as in the open circuit voltage case. This could be explained by the relatively large amount of the attached microbes. Under the $V_{oc}$condition the COD removal efficiency of Type B was found to be low for a long time, but those of Type A and C were found to be high for a short period of time. Therefore, the suspended microbes could decrease the coulombic efficiency. It was concluded that the high $V_{oc}$ was caused by low COD and the $V_{oc}$ became low after the COD removal. The COD reduction resulted in an unstable and low working voltage. From the polarization characteristics Type A was found to show the highest power density of $193\;mW/m^2$ with a fill factor of 0.127 due to the relatively high remaining COD even after the MFC reaction.

• 사상체질의학회지
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• 제15권3호
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• pp.124-138
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• 2003

Objectives : To evaluate the properness and effectiveness of the question categories concerning 'sasang constitutional characteristics of mind', used in Iksan Wonkwang Oriental Medicine. Methods : We statistically analyzed data from those 1335 patients focussing on 'relative discrimination ability' to sasang constructions and 'response ratio'. Patients included in this research are only those who had been well treated in Iksan Wonkwang Oriental Medicine during the Period of three years from 2000 to 2002. The data are obtained through the electronic chart developed by Kim Jong-Yeal, and analyzed using the statistical Package SPSS. Results: In total characteristics of mind, the question category of 'timid' has high discriminating power and effectiveness to Soeum type, more in women than men, and especially with an age of 21 or more; The category of 'hasty-tempered' to Soyang type in women with all ages and men with ages 21-40; The category of 'broad-minded' to Taeum type with ages 41 or more; The category of 'timid and broad-minded' to Soyang type, and especially high to women with ages 41 or more. Question categories concerning response type in anger were estimated to have different response patterns to sasang constructions only for ages 21 or more by $X^2$2 test. The question category of 'bear and last long' has high discriminating power and effectiveness to Soeum type, more in men than women, and increasingly to ages; The category of 'impatient and disarmed quickly' to Soyang type in both women and men, especially with ages 21 or more; The category of 'impatient' to Soyang type women or with ages 21 or more. Other categories have low discriminating power or low effectiveness. Concernig expression type of one's thought, the question category of 'straightly' has high discriminating power and effectiveness to Soyang type, more in wemen than men, and especially to ages 21 or more; The category of 'tender' to Soeum type, in women or with ages 40 or less; The category of 'indirectly' to Taeum type in men or with ages 41 or more; The category of 'straightly and stuborn' to Soyang type with ages 41 or more; The category of 'indirectly and tender' to Soeum with with ages 20 or less; The category of 'not express and tender' to Soeum type with ages 41 or more; Conclusions : Question categories concerning total characteristics of mind, response type in anger and expression type of one's thought, are partially discriminating and effective to specific constitution according to sex and ages, and some categories are more discriminating and effective when they are composited. But generally, the discriminating power of Taeum constitution group and group with ages 20 or less was too low, so it is necessary to develope question categories for those groups.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2006년도 추계 학술발표회 논문집
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• pp.809-812
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• 2006

This paper presents the results of tensile characteristics for developing FRP tendon with strand type. The performance targets were decided to compare the tensile characteristics of developing FRP tendon. Test specimens were manufactured by applying some improvements to enhance the tensile characteristics. The influence factors on the tensile characteristics have been found from the test results. Those are the fiber weight fraction, the pitch, the FRP cross sectional area, and the type of external fibers. The tensile characteristics were satisfactory compared to the performance targets.