• International Journal of Concrete Structures and Materials
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• v.4 no.1
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• pp.3-8
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• 2010

This paper present the results of investigation on the use of rice husk ash as a partial substitute for cement in construction. One hundred and eighty specimens of concrete cubes were cast. 0, 5, 10, 15, and 20% partial replacement of cement with rice husk ash were carried at 1:2:4 mixes by weight with 0.60, 0.65, 0.70 water/cement ratio. The results indicated that compressive strengths of cubes at 0.6, water/cement were higher than 0.65 and 0.70. Also 5% partial replacement cement with rice husk ash at $28^{th}$ day average compressive strength value of $25.4\;N/mm^2$ compared well with 0% partial replacement of cement with rice husk ash of $26.28\;N/mm^2$. This shows that at 5% partial replacement of cement with rice husk ash can be used for structural concrete and at 15% replacement or more it can be used for non - structural construction works or light weight concrete construction. The cost analysis shows substantial amount of savings for the country.

• Tunnel and Underground Space
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• v.10 no.4
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• pp.544-552
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• 2000

Norway has the geological of condition of hard bedrocks, high mountains, deep valleys and fjords. In this background many tunnels and rock caverns are developed. In this process of constructing tunnels and rock caverns Norway seems to have strong competitiveness in the construction of tunnels. In spite of high salaries to the tunnel workers, Norwegian contractors are probably producing the cheapest tunnels and rock caverns in the world. Besides benefit of hard-rock geology, Norwegian cost-saying is owing to the Norwegian excavation technique in hard rocks such as unlined pressure tunnels, air cushion chambers, underwater piercing, and reasonable contract system and organization of workers developed from the accumulated experience. Brief analytical description of them are given in this paper in order to stimulate the utilization of the underground spaces.

• Journal of Electrical Engineering and Technology
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• v.8 no.5
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• pp.1070-1077
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• 2013

Owing to the consistent increase in energy efficiency issues, studies for improving regenerative energy utilization have been receiving attention in the Urban DC railway systems, where currently, the utilization of regenerative energy is low due to the lack of a specific plan for using this energy. The regenerative energy in railway systems has a low efficiency problem which results in the increase of the catenary voltage and a possibility to create problems to the electrical devices connected to the system. This paper deals with the power integration of large urban railway subsystems to improve regenerative energy utilization where the railway subsystems are integrated with other railway subsystems to improve the energy efficiency. Through the case studies, to find the realistic effect of integrated operation, the Seoul Metro subsystems, namely Line 5 and Line 7, has been applied. Also, evaluation for the electricity cost saving has been performed by using KEPCO electricity cost table.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.9 no.7
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• pp.2530-2547
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• 2015

In the recent years, femtocell technology has received a considerable attention due to the ability to provide an efficient indoor wireless coverage as well as enhanced capacity. However, under the spectrum sharing between femtocell user equipment (FUEs) and the owner of spectrum macrocell user equipment (MUEs), both may experience higher uplink interference to each other. This paper proposes a novel distributed power control algorithm for the interference management in two-tier femtocell networks. Due to the assignment of licensed radio frequency to the outdoor macrocell users, the access priority of MUEs should be higher than FUEs. In addition, the quality of service (QoS) of MUEs that is expressed in the target signal-to-interference-plus-noise ratio (SINR) must always be achieved. On the other hand, we consider an efficient QoS provisioning cost function for the low-tier FUEs. The proposed algorithm requires only local information and converges even in cases where the frontiers of available power serve the target SINRs impossible. The advantage of the algorithm is the ability to implement in a distributed manner. Simulation results show that the proposed algorithm based on our cost function provides effective resource allocation and substantial power saving as compared to the traditional algorithms.

• Journal of the Korean Institute of Rural Architecture
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• v.14 no.3
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• pp.101-108
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• 2012

The purpose of this study was to set and analyze the feasibility and survey of the Hanok(The traditional Korean style house) housing complex project within Seoul metropolitan area. The results of this study were as follows. First of all, a survey was carried out to find out the optimum Hanok style. The survey showed that many people chose a frond and back yard garden as a merit of Hanok and pointed out the weak crime prevention as a weakness of Hanok. The optimum size for a Hanok was from $264m^2$ to $330m^2$ and living space was from $100m^2$ to $132m^2$. And people considered about 120% of what the apartment sells for as the reasonable price of a Hanok. Based on the survey, this study planned a Hanok housing complex on a lot that has competitive price and analysed the feasibility of the housing plan. The result was that Hanok's construction cost per $3.3m^2$ to be a marketable product has to be below about 6 million Won. As a result, the construction cost-saving through the advanced technology and planning to meet the changing customers' needs are needed to vitalize Hanok's supply.

• Journal of Advanced Navigation Technology
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• v.15 no.3
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• pp.456-461
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• 2011

In this paper, design and Implementation of single antenna RFID Shelf for FIFO management of marine materials, and propose a design as one effective solution of the problem. The goals of the proposed design and system are as follows: cost saving, RFID data validation. Cost problem occurs by the use of many RFID readers. Data problems in the steel structure is generated by the use of radio wave (RFID). In addition, material data from RFID Shelf system, is expected to be used FIFO design information for the vessel information system. Through the proposed RFID Shelf System, it is expected to systematic management and efficient business processes for the vessel information system.

• Journal of the Korean Society for Precision Engineering
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• v.17 no.7
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• pp.124-131
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• 2000

Rapid Prototyping(RP) models are no longer used only for design verification. Currently, parts built utilizing layer manufacturing technology can be employed as functional prototypes and as patterns or tools for different manufacturing processes such as vacuum casting, investment casting, injection molding, precise casting and sand casting. This trend of Rapid Prototyping application meets the requirement of concurrent engineering and its range covers a more spreaded area. The aim of this paper is saving the manufacturing lead time and cost of plastic parts having hollow space shapes used by prototype-car. Using rapid prototype patterns, made by the Selective Laser Sintering(SLS) technique, a new approach of manufacturing resin-based blow mold is discussed. It has a great potential fur making prototype-car parts with the batch size of under 200 parts, in case of rapid modification due to a subsequent design changes in developing stage. So, the process proposed in this research shows reduction of process time and manufacturing cost when compared with the conventional process such as a Zinc Alloy fur Stamping(ZAS) mold.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2002.11a
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• pp.39-42
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• 2002

Recently, CMP (chemical mechanical polishing) technology has been widely used for global planarization of multi-level interconnection for ULSI applications. However, COO (cost of ownership) and COC (cost of consumables) were relatively increased because of expensive slurry. In this paper, we have studied the possibility of recycle of reused silica slurry in order to reduce the costs of CMP slurry. The post-CMP thickness and within-wafer non-uniformity(WIWNU) were measured as a function of different slurry composition. As a experimental result, the performance of reused slurry with annealed silica abrasive of 2 wt% contents was showed high removal rate and low non-uniformity. Therefore, we propose two-step CMP process as follows In the first-step CMP, we can polish the thick and rough film surface using remaked slurry, and then, in the second-step CMP, we can polish the thin film and fine pattern using original slurry. In summary, we can expect the saving of high costs of slurry.

• Journal of Korean Institute of Industrial Engineers
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• v.25 no.4
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• pp.500-509
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• 1999

In this paper, we consider an optimal routing problem when point-to-point and point-to-multipoint connection traffics are offered in an ATM network. We propose a mathematical model for cost-minimizing configuration of a logical network for a given ATM-based BISDN. Our model is essentially identical to the previous one proposed by Kim(Kim, 1996) which finds a virtual-path configuration where the relevant gains obtainable from the ATM technology such as the statistical multiplexing gain and the switching/control cost-saving gain are optimally traded-off. Unlike the Kim's model, however, ours explicitly considers the VP's QoS(Quality of Service) for more efficient utilization of bandwidth. The problem is a large-scale, nonlinear, and mixed-integer problem. The proposed algorithm is based on the local linearization of equivalent-capacity functions and the relaxation of link capacity constraints. As a result, the problem can be decomposed into moderate-sized shortest path problems, Steiner arborescence problems, and LPs. This fact renders our algorithm a lot faster than the previous nonlinear programming algorithm while the solution quality is maintained, hence application to large-scale network problems.

• International Journal of Internet, Broadcasting and Communication
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• v.13 no.1
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• pp.20-25
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• 2021

In the background of the rapid development of the IoT, smart home work is becoming more and more important to each science and technology company. Smart home provides a safe, comfortable, high-quality, high-performance smart home living space compared to general homes, and at the same time It is responding to the low-carbon, eco-friendly global trend. Growth drivers driving the smart home market are increasing the number of Internet users, increasing disposable income in developing countries, increasing the importance of remote home monitoring, and increasing the need for energy saving and low carbon. In 2013-2014, Xiaomi launched a series of smart routers and smart home hardware devices. In 2015, it announced the latest product of the Xiaomi Ecological Chain, the "Smart Home Package," and in 2016 launched the MIJIA brand to invest in various smart product companies. In 2017, Xiaomi announced a plan to build an open smart hardware MIOT platform. We investigated the management strategy of Xiaomi home smart service based on IOT. The management strategy was divided into cost lead strategy, differentiation strategy of Xiaomi home service, and AIOT strategy of Xiaomi smart home.