• Environmental Engineering Research
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• v.18 no.2
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• pp.91-94
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• 2013

Recently Ibadan in southwestern Nigeria has been facing severe water shortage due to the increase of population, social and economic activities. In order to meet the shortfall, attempts to utilize rainwater harvesting (RWH) have been made to provide an alternative source of water supply. A desk study was conducted to review various RWH technologies locally, regionally and globally. A hydrological analysis was also carried out using rainfall data for 30 years from two meteorological stations, with the aim of providing a more sustainable RWH system for water supply to private individuals, organizations, and government agencies. RWH is found to be technically feasible based on the prevailing rainfall pattern with over 90% of households having a rooftop constructed from technically appropriate materials. Results of the study indicate that an average roof of $80m^2$ will collect 82,835 L/yr (45 L/person/day) for a family of five people which is about the required water demand for drinking and cooking purposes. Hence, the capacity of storage tanks and the catchment area required for an all-purpose water supply system based on RWH are quite large. These can be reduced to affordable sizes, by collecting and storing water for cooking and drinking only while non-potable uses are supplemented by water from other sources. However, it must be highlighted that due to the type of roofing material, rainwater should go through proper treatment in order to be used for potable purposes. This study clearly shows that Ibadan city has a good rainwater harvesting potential.

• Journal of Power System Engineering
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• v.14 no.3
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• pp.5-12
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• 2010

The purpose of this study is to analyze heterogeneous distribution of branch-like structure at downstream region of inner spray. The previous many studies about diesel spray structure have yet stayed in the analysis of 2-D structure, and there are very few of informations which are concerned with 3-D analysis of the structure. The heterogeneous distribution of droplets in inner spray affects the mixture formation of diesel spray, and also the combustion characteristics of the diesel engines. Therefore, in order to investigate 3-D structure of evaporative spray the laser beam of 2-D plane was used in this study. Liquid fuel was injected from a single-hole nozzle (l/d=5) into a constant-volume vessel under high pressure and temperature in order to visualize the spray phenomena. The incident laser beam was offset on the central axis. From the images analysis taken by offset of laser beam, we examine formation mechanism of heterogeneous distribution by vortex flow at the downstream of the diesel spray. As the experimental results, the branch-like structure formed heterogeneous distribution of the droplets consists of high concentration of vapor phase in the periphery of droplets and spray tip of branch-like structure. Also the 3-D spatial structure of the evaporative diesel spray can be verified by images obtained from 2-D measurement methods.

• Journal of Korean Society for Quality Management
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• v.41 no.2
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• pp.277-288
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• 2013

Purpose: This study aims to analyze the success factors of information systems and the moderating effect of individual factors in mandatory environment. Methods: In order to test the model, a questionnaire survey is delivered from salespersons of an insurance company in Seoul, Korea. 200 questionnaires are finally analyzed. Structural Equation Modeling (SEM) is adopted to analyze the data and Smart PLS 2.0 is used for examining the moderator effect. Results: The extended model proposed in this paper adopted individual factors and examined their moderator effect among constructs. An empirical test is carried out accordingly in order to test the model proposed in this paper. The results reveal that individual factors (i.e. Computer Self-Efficacy, Anxiety, Personal Innovativeness in IT) have a significant moderating effect on individual performance in the environment of mandatory information system usage. Conclusion: This paper extended the research field of information system success model to information systems in mandatory environment regarding differences of individual factors.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.13 no.4
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• pp.427-436
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• 2000

This study presents the nonlinear responses of a hinged-clamped beam under broadband random excitation. By using Galerkin's method the governing equation is reduced to a system or nonautonomous nonlinear ordinary differential equations. The Fokker-Planck equation is used to generate a general first-order differential equation in the joint moments of response coordinates. Gaussian and non-Gaussian closure schemes are used to close the infinite coupled moment equations. The closed equations are then solved for response statistics in terms of system and excitation parameters. The case of two mode interaction is considered in order to compare it with the case of three mode interaction. Monte Carlo simulation is used for numerical verification.

• Asia pacific journal of information systems
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• v.13 no.3
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• pp.173-193
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• 2003

As the interest in the business-to-business(B2B) electronic commerce is increasing, some companies are participating in the B2B eMarketplaces(electronic marketplaces). The eMarketplace has an effect on the method of B2B transactions or the purchasing performance. The academy and the industry are focused on the cause and the result of this effect. The purpose of this research is to analyze the effects of the relational exchange with eMarketplace on the purchasing performance, considering the supply externality and system integration as intervening variables. This study investigates the second-order effect of eMarketplace in which the degree of improvements in two aspects of purchasing activity(price reduction, purchasing efficiency) depends on the degree of the relational exchange with eMarketplace, namely, the governance of eMarketplace. Our hypotheses on this second order effect were supported. We found that the higher the relational governance, the lower in price reduction, and the better in purchasing efficiency. In more details, the high relational governance lowers the supply externality, and in turn deteriorates the improvement in price reduction. Meanwhile, the high relational governance accelerates the information system integration, and brings the better purchasing efficiency. Our findings suggest that organizations can improve their purchasing activities better if they choose the appropriate eMarketplace governance.

• Journal of the Society of Naval Architects of Korea
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• v.46 no.4
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• pp.382-390
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• 2009

The submerged body near the free surface is disturbed by the 1st and 2nd order wave forces, which results in unstable movements when no control is applied. In this paper, the vertical motions of the submerged body are analyzed, and the time-variant nonlinear system for the vertical motions of the submerged body is transformed to the time-invariant linear system in state space. Next, depth controller of the submerged body is designed by using LQR control, one of the modern optimal control technique. Numerical simulation shows that effective depth controls can be achieved by LQR control.

• Journal of Information Technology Applications and Management
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• v.12 no.4
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• pp.133-155
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• 2005

This Paper makes an attempt to suggest a process of automatically generating application software based on the Entity-Relationship model 1. The designer develops an E-R model of an real-world system. 2. The designer inputs the entity and relationship types, and attributes shown in the E-R model, and also the basic operations of the application system to the software generator. 3. The application generator produces database schema and link information between application programs, and then automatically generates a stereo-type application system. In order for the automated application generator to build the application system in a systematic way, four basic program generation rules have been suggested. A set of computer programs have been developed in order to show the applicability of the automated software generation process suggested in this paper. By following each rule with the generator, the designer can build an application in an efficient manner compared with traditional (manual programming) approaches. It has been demonstrated from the case study that the idea of applying an automated generator in systems development based upon the E-R model is feasible.

• 전자공학회논문지 IE
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• v.44 no.3
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• pp.12-22
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• 2007

In this paper, we designed of the high speed digital neuron processor in order to digital neural networks. we designed of the MAC(Multiplier and Accumulator) operation unit used residue number system without carry propagation for the high speed operation. and we implemented sigmoid active function which make it difficult to design neuron processor. The Designed circuits are descripted by VHDL and synthesized by Compass tools. we designed of MAC operation unit and sigmoid processing unit are proved that it could run time 19.6 nsec on the simulation and decreased to hardware size about 50%, each order. Designed digital neuron processor can be implementation in parallel distributed processing system with desired real time processing, In this paper.

• Proceedings of the KIPE Conference
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• 2001.10a
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• pp.518-522
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• 2001

In recent years, natural energy has attracted growing interest because of environmental concerns. Many studies have been focused on photovoltaic power generation systems because of the ease of use in urban areas. On the conventional system, many photovoltaic modules (PV modules) are connected in series in order to obtain the sufficient DC-bus voltage for generating AC output voltage at the inverter circuit. However, the total generation power on the PV modules sometimes decreases remarkably because of the shadows that partially cover the PV modules. In order to overcome this drawback, an AC module strategy is proposed. On this system, a small power DC-AC utility interactive inverter is mounted on each PV module individually and the inverter operates so as to generate the maximum power from the corresponding PV module. This paper presents a novel flyback-type utility interactive inverter circuit suitable for AC module systems. The feature of the proposed system are, (1) small in volume and light in weight, (2) stable AC current injection, (3) enabling a small DC capacitor. The effectiveness of the proposed system is clarified through the simulation and the experiments.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.18 no.9
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• pp.738-744
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• 2006

In order to utilize the condensation heat of refrigerants in condenser on the absorption chiller system, the solution cooled condenser (SCC) was proposed using the weak solution of absorber as a cooling medium. The increase of COP with the increase of UA of the solution cooled condenser was approximately 0.009 in maximum with single effect one, and is about maximum 0.008 in occasion of double effect one with series flow compared to that without. In the case of heat exchanger, effectiveness is about 0.85, it's increments are 0.008 and 0.0072, respectively. And solution cooled condenser is more effective device in the single effect absorption system than double effect system for the principle of operation. On the other hand, as the solution split ratio increases when the value of UA is fixed, COP is increased and as the solution split ratio increases when the value of UA is fixed, COP is increased. If the flow rate of cooling water or the value of UA is reduced in order to increases the heat recovery of solution cooled condenser, heat recovery of solution cooled condenser is increased a little but COP is decreased as the system pressure is increased.