• 전기학회논문지
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• 제62권4호
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• pp.437-443
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• 2013

This paper was developed a monitoring and control system to use reactive power control algorithm. This algorithm could be improved voltage stability in power system. This method was controlled the voltage for stability improvement, effective usage of reactive power, and the increase of the power quality. PMS(Power Management System) has been calculate voltage sensitivity, and control reactive power compensation device. The voltage control was used to the FACTS, MSC/MSR(Mechanically Switched Capacitors/Reactors), and tap of transformer in power system. The reactive power devices in power system were control by voltage sensitivity ranking of each bus. Also, to secure momentary reactive power, it had been controlled as the rest of reactive power in the each bus. In here, reactive power has been MSC/MSR. The simulation result, First control was voltage control as fast response control of FACTS. Second control was voltage control through the necessary reactive power calculation as slow response control of MSR/MSR. Third control was secured momentary reactive reserve power. This control was method by cooperative control between FACTS and MSR/MSC. Therefore, the proposed algorithm was had been secured the suitable reactive reserve power in power system.

• 한국의류학회지
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• 제38권6호
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• pp.857-872
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• 2014

This study investigates the effect of service ubiquity perceptions on consumers' responses to virtual stores such as benefit and risk perceptions, shopping value perceptions, and service usage intention. Data were collected via a self-administered online survey from nationwide consumer panels of an online marketing research firm. Questionnaire items were adopted from previous literature and developed by authors via pretesting to measure variables. The results revealed that virtual store service ubiquity affects consumer benefit perceptions as well as risk perceptions. All benefit perceptions (including time effectiveness, user control, and compatibility) had significant mediating effects between service ubiquity and hedonic/utilitarian shopping service value perceptions. The mediating effect of financial risk was significant only in the relationship between service ubiquity and utilitarian value perception. The findings offer retailers and marketers information in regards to consumers' perception of a virtual store usage, which can enhance service and product strategy.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2007년도 추계학술대회논문집
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• pp.1266-1271
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• 2007

General coil spring has linearity. However, disc spring has non-linearity so that using this non-linearity disc spring can be designed to do shock-absorbing in cases we need because shock response also has non-linearity. By changing the shape and stacking number, it is satisfactory with response of displacement, velocity and acceleration. Conventionally, disc spring was used to control the vibration against huge load and limited space. However, it is limitedly used because of difficulty of the designing guidance. Therefore, disc spring is needed to study further in order to apply it widely. Response of disc spring is compared to response of coil spring by changing ho/t radio with computer simulation and the usage of disc spring is increased through analysis of effect of design factors. The purpose of this paper is that the shock response of disc spring is calculated through numerical simulation and effect of ho/t and stiffness is analyzed to broad usage so that design factor of disc spring is presented.

• 한국물환경학회지
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• 제28권1호
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• pp.50-56
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• 2012

In this study, loess composites, loess with lanthanum and with aluminum, were made and evaluated for treatment of phosphorus removal in natural water system. Desiccation method for production of loess composite was superior to centrifugation method in obtaining high concentrated composites of lanthanum and aluminum. Washing of loess lanthanum composite by water did not deteriorat the lanthanum concentration in the composite, but this lowered the aluminum concentration of loess aluminum composite. Total of 15 and 37.5% of aluminum contents were removed after first washing treatment in aluminum loess of 0.05% and 0.1% respectively. However, no more aluminum loss was monitored with increase of washing times. Phosphorus removal efficiencies were not decreased with washed loess aluminum composite. Phosphorus removal was successfully achieved by adsorption of phosphate to loess composite at pH range of 5.0 ~ 8.0. Freundlich and Langmuir adsorption isotherm was observed in the adsorption of phosphate for loess composite. Dosages of 0.05% and 0.1% lanthanum composite for 95% of phosphorus removal could reduce its usage amount to 25% and 50%, respectively, comparing with dosage of loess alone. Dosages of 0.05% and 0.1% aluminum composite could reduce its usage amount to 48% and 63%, respectively.

• 펄프종이기술
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• 제48권1호
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• pp.134-141
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• 2016

Dampening in printing is not only used with plain water but also used with various substances like dampening additive, in order to improve the wetting property by lowering the surface tension and to control material for modifing the ink transfer characteristic with proper emulsification. We have studied the printing quality according to these, looking into interrelationship among the dampening solution's pH, electrical conductivity and IPA content, prescribing the proper usage and minimum usage of fountain solution and dampening additive. In this study, it shows good result when mixing at the 7 wt% dampening with additive solution, which is result from the color density of printed sheets in accordance with the change of dampening solution condition. And the printed density value calculated 1 hour after printing, it shows relatively safe value at the etch liquid 4 wt% and IPA addition 2 wt%. The dry down at this test showed similar results regardless of various dampening conditions on coated paper, but in case of uncoated paper, the dry down showed a quite gap of different due to the fast penetration to the paper.

• Journal of Electrical Engineering and Technology
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• 제13권6호
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• pp.2145-2157
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• 2018

Congestion Management (CM) is an attractive research area in the electrical power transmission with the power compensation abilities. Reconfiguration and the Flexible Alternating Current Transmission Systems (FACTS) devices utilization relieve the congestion in transmission lines. The lack of optimal power (real and reactive) usage with the better transfer capability and minimum cost is still challenging issue in the CM. The prediction of suitable place for the energy resources to control the power flow is the major requirement for power handling scenario. This paper proposes the novel optimization principle to select the best location for the energy resources to achieve the real-reactive power compensation. The parameters estimation and the selection of values with the best fitness through the Symmetrical Distance Travelling Optimization (SDTO) algorithm establishes the proper controlling of optimal power flow in the transmission lines. The modified fitness function formulation based on the bus parameters, index estimation correspond to the optimal reactive power usage enhances the power transfer capability with the minimum cost. The comparative analysis between the proposed method with the existing power management techniques regarding the parameters of power loss, cost value, load power and energy loss confirms the effectiveness of proposed work in the distributed renewable energy systems.

• 경영과학
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• 제27권3호
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• pp.117-135
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• 2010

The purpose of this study is to segment the mobile phone users based on the flow types and to understand the differences in mobile phone usage behavior between the segmented groups. The 'flow' construct, which was introduced first in marketing by Hoffman and Novak[44], has been used as an important keyword for understanding consumer behavior on the World Wide Web. In this paper, we will try to use the flow aspect for the mobile market segmentation, which is one of the most fundamental tools for developing a successful marketing strategy on the mobile phone service market. We collected survey data from consumers and analyzed the data with the SPSS 12.0 package where we did ${\chi}^2$-test, factor analysis, one-way ANOVA and cluster analysis. Main results of this study are as follow. First, the flow types of the mobile phone users were classified into five types, which are named as the 'Flow' type, 'Apathy' type, 'Anxiety' type, 'Boredom' type, 'Control' type. Second, most of the results related to the usage of mobile phone service showed statistically significant differences between flow types. These findings suggest that the mobile phone service marketers should consider the various flow types of users and work out effective market segmentation strategies based on these consumer flow types.

• Fisheries and Aquatic Sciences
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• 제22권12호
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• pp.29.1-29.7
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• 2019

Veterinary drugs are widely used to protect production-related diseases and promote the growth of farmed fish. The use of large amounts of veterinary drugs may have potential risk and cause adverse effects on both humans and the environment. In this study, we developed risk-based ranking based on a scoring system to be applied in the national residue program. In this approach, the following three factors of veterinary drugs that may occur as residues in fishery products were considered: potency (acceptable daily intake), usage (number of dose and withdrawal period), and residue occurrence. The overall ranking score was calculated using the following equation: potency × usage (sum of the number of sales and withdrawal period) × residue occurrence. The veterinary drugs that were assigned high score by applying this approach were enrofloxacin, amoxicillin, oxolinic acid, erythromycin, and trimethoprim. The risk-based approach for monitoring veterinary drugs can provide a reliable inspection priority in fishery products. The developed ranking system can be applied in web-based systems and residuemonitoring programs and to ensure safe management of fishery products in Korea.

• 한국IT서비스학회지
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• 제15권2호
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• pp.157-167
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• 2016

Task environment for enterprises and public institutions are moving into cyberspace-based environment and structing the LTE wireless network. The applications "App" operated in the LTE wireless network are mostly being developed with Android-based. But Android-based malwares are surging and they are the potential DDoS attacks. DDoS attack is a major information security threat and a means of cyber attacks. DDoS attacks are difficult to detect in advance and to defense effectively. To this end, a DMZ is set up in front of a network infrastructure and a particular server for defensive information security. Because There is the proliferation of mobile devices and apps, and the activation of android diversify DDoS attack methods. a DMZ is a limit to detect and to protect against DDoS attacks. This paper proposes an information security method to detect and Protect DDoS attacks from the terminal phase using a Preemptive military strategy concept. and then DDoS attack detection and protection app is implemented and proved its effectiveness by reducing web service request and memory usage. DDoS attack detection and protecting will ensure the efficiency of the mobile network resources. This method is necessary for a continuous usage of a wireless network environment for the national security and disaster control.

• 한국컴퓨터산업학회논문지
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• 제5권1호
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• pp.49-56
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• 2004

인터넷 사용의 급증에 따라 대부분의 사용자들은 여러 웹 서버의 서비스를 사용하고 있으며 각 서버의 접속 사용자 ID 및 패스워드의 상이함으로 인해 혼선을 초래하기도 한다. 이러한 문제를 해결하기 위한 방법이 SSO(Single Sign-On)이다. 본 논문은 네트워크에 존재하는 다양한 서버 및 호스트에 접근하기 위한 550를 적용하여 침입 탐지 시스템과 침입 차단 시스템 등과 같은 보안 시스템의 관리를 수월하게 하고 네트워크 사용 및 관리를 효과적으로 수행하기 위한 모델링 방법을 제안한다 본 연구진이 제안하는 방법은 소규모 네트워크에서 적용하여 사용하기 수월하도록 구성하였으며 조직의 여러 데이터를 효과적으로 처리할 수 있도록 구성되었다. SSO의 구성은 인증서 기반의 PKI (Public Key Infrastructure)를 사용하여 구성하였으며 인증 통신을 위한 데이터 암호화를 SSL (Secure Socket Layer) 기반의 SHTTP (Secure Hyper Text Transfer Protocol)을 적용한다.