• Journal of Power Electronics
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• v.1 no.2
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• pp.117-126
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• 2001

A synchronous motor(SM) with q-axis special field winding of which the q-axis field-current compensates and cancels armature reaction can be driven at unity power factor under the conditions of transient state as well as steady state. The motor operates in high efficiency in all conditions. However, in order to obtain maximum performance of the motor, it is required that the time constant of armature circuit corresponds to that of q-axis field circuit. Inverse LQ(ILQ) design method on a basis of the pole assignment is suitable for this problem:(1) The time constants of the output responses can be designed for desired specifications, (2) Relations between feedback gains and response of closed loop system are very clear and (3) Optimal solutions can be given by simple procedure of ILQ method without solving the Ricaati's equation, compared to the usual LQ design method. Accordingly, the ILQ method can make the responses of armature current and q-axis field-current correspond. In this paper, it is proved by numerical simulations and experiments that the ILQ method is very effective for optimal regulator design of this plant and realizes a high-performance motor with unity power factor and high efficiency.

• Geotechnical Engineering
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• v.2 no.3
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• pp.5-14
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• 1986

The results of stabilization process in silty.clays and sand-silts, which were, respectively, treated with Calcium hydroxide of the Calcium series and Aluminium Sulphate of the Aluminium series are follows. 1) In the former case used calcium hydrate and calcium cabonate for silty-clays, calcium aluminnium cabonate oxide hydrate and calcium carbonate for sandy-silts were produced 2) In the latter case used Aluminium Sulphate, by X-ray diffraction test, it was found that Aluminium Oxide was produced both in silty-clays and sandy-silts 3) As the results of stabilization process, in the former case, unconfined compression strength was increased greatly but in the latter case it was little increased.

• Journal of Ocean Engineering and Technology
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• v.11 no.3
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• pp.76-88
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• 1997

Constant .DELTA.K fatigue crack growth rate experiments were performed by applying an intermediate single and multiple overload for structural steel, SM45C. The purpose of the present study is to investigate the influence of multiple overloads at various stress intensity factor ranges and the effect of statistical variability of crack retardation behavior. The normalized delayed load cycle, delayed crack length and the minimum crack growth rate are increased with increasing baseline stress intensity factor range when the overload ratio and the number of overload application were constant. The crack retardation under low baseline stress intensity factor range increases by increasing the number of overload application, but the minimum crack growth rate decreases by increasing the number of overload application. A strong linear correlation exists between the minimum crack growth rate and the number of overload applications. And, it was observed that the variability in the crack growth retardation behavior are presented, the probability distribution functions of delayed load cycle, delayed crack length and crack growth life are 2-parameter Weibull. The coefficient of variation of delayed load cycle and delayed crack length for the number of 10 overload applications data are 14.8 and 9.2%, respectively.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.14 no.2
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• pp.312-320
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• 2010

Most online monitoring systems of running currently based on the wired network and local area wireless network generate an increase of administrative costs such as synchronization of data protocol conversion, flexible operation of measurement devices and maintenance. To solve this problem, this paper proposes the SMS data transmission protocol which allows multiple data collecting device to manage effectively including implementation method of cdma-based environmental information monitoring system. Also this paper shows operational safety of the proposed protocol and analyzes efficiency of data transfer and operating using SMS.

• Proceedings of the KIEE Conference
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• 2003.07c
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• pp.1903-1905
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• 2003

전자기력을 이용하여 탐침형 정보저장장치의 미디어를 제어할 수 있는 초정밀 구동기를 제작하였다. 탐침형 정보저장장치는 데이터 비트의 크기가 10nm 수준이고, 단일 캔틸레버가 점유하는 영역의 크기가 수십 ${\mu}m$${\times}$수십${\mu}m$ 수준이므로, 미디인 구동기는 수 nm의 위치 정확도 및 수십 ${\mu}m$ 수준의 변위 그리고 100Hz이상의 공진 주파수를 확보하여야한다. 본 연구에서 제작한 탐침형 정보저장장치의 미디어 구동기는 고저항 Si wafer 표면을 Deep RIE로 patterning한 후 그 내부를 도금으로 채워 구리 코일을 형성하고 이를 영구자석과 결합시킨 후, 구리 코일에 전류를 흘려 미디어를 구동하는 방식이다. 사용된 영구자석은 SmCo 자석이며 코일의 폭은 $100{\mu}m$이고 간격은 $20{\mu}m$, 높이는 $70{\mu}m$로 결정하였으며, 100Hz 이상의 공진 주파수를 확보하기 위하여 스프링 재질은 구리보다 상대적으로 stiff한 Si을 사용하였다. 미디어의 크기는 $20{\times}20mm^2$, 전체 구동기의 크기는 $30{\times}30mm^2$이며 측정결과 최대변위는 140mA 인가 시 약 ${\pm}127{\mu}m$이다.

• Journal of Species Research
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• v.9 no.2
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• pp.147-161
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• 2020

Seven new species of two genera Scalarispongia and Smenospongia (Demospongiae: Dictyoceratida: Thorectidae) are described from Gageo Island and Jeju Island, Korea. Five new species of Scalarispongia are compared to nine reported species of the genus by the skeletal structure. Scalarispongia viridis n. sp. has regular ladder-like skeletal pattern arranged throughout the sponge body and has pseudo-tertiary fibres. Scalarispongia favus n. sp. is characterized by the honeycomb shape of the surface and is similar to Sc. flava in skeletal structure, but differs in sponge shape. Scalarispongia lenis n. sp. is similar to Sc. regularis in skeletal structure but has fibers that are smaller in size. Scalarispongia canus n. sp. has irregular skeletal structure in three dimensions and ladder-like which comes out of the surface and choanosome. Scalarispongia subjiensis n. sp. has pseudo-tertiary fibres and its regular ladder-like skeletal pattern occurs at the choanosome. Two new species of Smenospongia are distinguished from the other 19 reported species of the genus by the skeletal structure. Smenospongia aspera n. sp. is similar to Sm. coreana in sponge shape but new species has rarely secondary web and thin and thick bridged fibres at near surface. Smenospongia mureungensis n. sp. has very simple skeletal structure.

• Natural Product Sciences
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• v.13 no.2
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• pp.105-109
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• 2007

Alcoholic extract of Terminalia arjuna [TA] was evaluated far its hepatoprotective activity against carbon tetrachloride (CCl$_4$)-induced hepatic damage in rats. The hepatoprotective activity of TA was evaluated by measuring levels of serum marker enzymes like serum glutamate oxaloacetate transaminase (SGOT), serum glutamate pyruvate transaminase (SGPT), serum alkaline phosphatase (SALP). The serum levels of total proteins(TP), total albumins (TAL) and bilirubin (BILN) were also estimated. The histological studies were also carried out to support the above parameters. Silymarin (SM) was used as standard drug. Administration of TA (250 and 500 mg/kg/po) markedly prevented CCl$_4$-induced elevation of levels of SGOT, SGPT, SALP, TP, TAL and BILN. These biochemical observations were supplemented by histopathological examination of liver sections. Alcoholic extract of TA also shown significant in-vitro free radical scavenging activity against 1, 1-diphenyl-2-picryl hydrazyl (DPPH) and nitric oxide (NO) radicals. Thus, the present study provides a scientific rationale for the traditional use of this plant in the management of liver diseases.

• Journal of the Korea Society of Computer and Information
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• v.17 no.2
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• pp.225-230
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• 2012

With a wide spread of smart phone, Smart society has been progressed through nationwide that changed way of personal daily life rapidly. As smart work has been introduced and utilized at the office, it is possible that the person in charge can handle remote transaction without restriction of time and place. Smartlization throughout the society has been progressed, member of work and system related can be linked mutually and took personalized services. This study identifies explorative moderating effect of smart environment at performance of work with employee cognition. As a result, found that smart work environment with complexity of work has increased moderating effect over collaborative work.

• Journal of Industrial Convergence
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• v.15 no.2
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• pp.37-43
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• 2017

As the number of SSM(Super Supermarket) has been growing, the conflict between large companies and small-to-medium retailers is being deeper in which large-sized market has been growing rapidly and small to medium retailers has been depressed. To solve the conflict, the government enacted the system of business limiting of large enterprises by SMEs. It brought growth of sales of small-to-medium retailers. However, unintended effects were caused by the system. This research aims to analyze underlying structure beyond conflicts between SSM and small to medium retailers using system thinking and draw relationships between key factors. Thus we can provide political alternatives through simulation model which is developed based on the factors.

• Journal of Nuclear Fuel Cycle and Waste Technology(JNFCWT)
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• v.21 no.2
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• pp.271-281
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• 2023

A study was conducted on the vitrification of the rare earth oxide waste generated from the PyroGreen process. The target rare earth waste consisted of eight elements: Nd, Ce, La, Pr, Sm, Y, Gd, and Eu. The waste loading of the rare earth waste in the developed borosilicate glass system was 20wt%. The fabricated glass, processed at 1,200℃, exhibited uniform and homogeneous surface without any crystallization and precipitation. The viscosity and electrical conductivity of the melted glass at 1,200℃ were 7.2 poise and 1.1 S·cm^-1, respectively, that were suitable for the operation of the vitrification facility. The calculated leaching index of Cs, Co, and Sr were 10.4, 10.6, and 9.8, respectively. The evaluated Product Consistency Test (PCT) normalized release of the glass indicated that the glass satisfied the requirements for the disposal acceptance criteria. Furthermore, the pristine, 90 days water immersed, 30 thermal cycled, and 10 MGy gamma ray irradiated glasses exhibited good compressive strength. The results indicated that the fabricated glass containing rare earth waste from the PyroGreen process was acceptable for the disposal in the repository, in terms of chemical durability and mechanical strength.