• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2008년도 추계 학술발표회 제20권2호
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• pp.373-376
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• 2008

The objective of this study is to investigate the properties of fresh concrete with recycled fine aggregates. Three different kinds of fine aggregate with natural, high and low quality recycled aggregates were prepared. The concrete mixtures were produced with test parameters of replacement ratio of recycled fine aggregate. The properties of the fresh concrete were measured by means of slump and air content according to elapsed time. Quality control method to maintain the constant total mixing water for recycled aggregate concrete was suggested. The all concrete mixtures were produced with approximately the same slump on the job site after an hour. Test results indicated that compressive strength of the concrete mixtures with constant slump is not affected by the replacement ratio of recycled fine aggregate. Therefore, the practical way for the quality control of recycled aggregate concrete is to maintain the constant total mixing water.

• 한국주거학회논문집
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• 제12권2호
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• pp.25-34
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• 2001

In this study, the shared facilities and space in the multi-family housing which residents could maintain contacts with their neighbors were investigated and analyzed. It could find the shared facilities and space so that residents could maintain to contact with their neighbors after surveying the dwellers requirements. Also it could specify the importance of the neighborhood common spaces and the conditions for the planning of the shared facilities. Analyzing residents requirement of set-up location, this study lead to the following suggestions concerning the facilities design: In the first neighborhood-circle, it require to be related the household affairs of housewives on the adjacent space to a dwelling-unit. In the second neighborhood-circle, it require especially the facilities for children play, study, reading, hobby etc. These facilities need establish each 4-5 floor in high-rise building estates. The roof & underground floors has been recognized in important & essential place for living facilities. Therefore, it is needed to improve to get ready to receive the various facilities.

• 유체기계공업학회:학술대회논문집
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• 유체기계공업학회 2006년 제4회 한국유체공학학술대회 논문집
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• pp.509-512
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• 2006

The propellant mixture ratio of gas generator changes when thrust control valve operate to change LRE thrust level. The mixture ratio change of gas generator result in gas temperature change and failure of turbine blade or deterioration of LRE specific impulse. The mixture ratio stabilizer has been developed to maintain propellant mixture ratio of gas generator. This article deals with design and static/dynamic characteristic of stabilizer. Also gas generator system simulation test has shown that the stabilizer can maintain propellant mixture ratio effectively within tolerable range.

• 한국공작기계학회:학술대회논문집
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• 한국공작기계학회 1998년도 춘계학술대회 논문집
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• pp.196-202
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• 1998

Recently, developments in the frontier industry have brought a rapid increase in the use of brittle materials such as silicon wafer, ferrite, sintered carbide, MgO single crystal and die steel. Because of high hardness and brittleness the cracking and chipping are apt to generate in the grinding of brittle materials, but have replaced gradually the high precision grinding. In this study, the optimum system of in-process electrolytic dressing controlled by computer was developed for improving the defects, and could maintain the optimum dressing condition at all times. The control of in-process dressing was simplified using this system, was able to maintain a stable dressing current and was unrelated to the change of dressing condition according to the variation of gap and oxide layer. Therefore, the optimum in-process electrolytic dressing system was constructed and the analysis of grinding mechanism with this system was studied.

• 한국생산제조학회지
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• 제24권5호
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• pp.548-552
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• 2015

In this paper, we describe the quadruped walking-control algorithm of the complete full-size humanoid DARPA Robotics Challenge-HUBO (DRC-HUBO) robot. Although DRC-HUBO is a biped robot, we require a quadruped walking function using two legs and two arms to overcome uneven terrains in the DRC. We design a wave-type quadruped walking pattern as a feedforward control using several walking parameters, and we design zero moment point (ZMP) controllers to maintain stable walking using an inverted pendulum model and an observed-state feedback control scheme. In particular, we propose a switching algorithm for ZMP controllers using supporting value and weighting factors in order to maintain the ZMP control performance during foot switching. Finally, we verify the proposed algorithm by performing quadruped walking experiments using DRC-HUBO.

• 전자공학회논문지B
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• 제31B권2호
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• pp.1-9
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• 1994

In distributed environments, data replication increases availability and decreases communication cost. However, it is difficult to maintain consistency and availability of data if site failure occurs. When we use the conventional hierarchical quorum consensus(HQC) method in order to maintain the consistency of data, occurrence of site failures makes it harder to perform the operation on replicated data because of insufficient votes. The objective of this paper is to improve the possibility of retaining necessary votes by reconstructing the HQC structure, when the site failure occurs. Furthermore, we compare the modified HQC method with the conventional HQC and QC methods in terms of improvement of availability.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2006년도 추계학술대회 특별세미나 특별세션
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• pp.171-180
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• 2006

The EMS system requires a very delicate suspension control to maintain constant air-gap between the magnet and the guide-way rail. To maintain a constant air-gap with attraction force, the EMS system dynamics is changed according to uncertainties and disturbances, and it also requires reliability against component failures. Since uncertainties and component failures are frequently caused in EMS system, it is very important to develop the robust and reliable control system. In this paper, we consider the design problem for robust and reliable controller in the presence of uncertainties and component failures.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제5권5호
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• pp.999-1012
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• 2011

This paper proposes an algorithm that enables mobile nodes to implement self-regulated movements in mobile ad-hoc networks (MANETs). It is important for mobile nodes to maintain a certain level of network-based stability by harmonizing these nodes' movements autonomously due to their limited transmission range and dynamic topology. Entropy methods based on relative position are suggested, as a means for mobile nodes to regulate their local movements. Simulations show that an early warning mechanism is suitable to maintain movement-based stability. Isolation can be reduced by 99%, with an increased network cost of 12% higher power consumption, using the proposed algorithm.

• 공학교육연구
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• 제18권6호
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• pp.52-56
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• 2015

Usually, students write on a paper using writing materials and submit it to teachers when they do a homework or take an exam. However, there are temporal and spacial constraints because teachers and students should be in the same place at the time in this system. In addition, it is hard for teachers to maintain numerous papers from students. Applying a digital pen produced by Pen Generations Corporation to education system, we developed a smart education system transmitting image data from written papers using digital pen. As a result, teachers and students can use this system without any constraints. In addition, teachers are able to maintain their papers from students more effectively.

• Tribology and Lubricants
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• 제23권2호
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• pp.61-65
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• 2007

It is very important to connect machinery and maintain it. This is usually done by bolt joint. There are two ways in connecting the bolt joint : the angle method and the torque method. The torque method is a method that let the clamping force maintain. The underhead of the bolt's head and the thread friction are the main influences. This study focuses on how the clamping farce and friction coefficient change under the condition in vibrating the underhead of the bolt's head part. As a result, under vibration condition, we found out that the clamping farce increases, while the friction coefficient decreases.