• 한국신재생에너지학회:학술대회논문집
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• 한국신재생에너지학회 2010년도 추계학술대회 초록집
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• pp.111.2-111.2
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• 2010

One-dimensional nanostructures such as carbon nanotubes could be ideal templates for formation of metallic nanoparticles. Furthermore, bimetallic component nanoparticles have recently been interesting issues for having high catalytic activity. This work provides both a facile method to synthesize bimetallic catalysts via N atoms of carbon nanotubes and also a picture about how to design the optimal bimetallic catalyst for hydrogen generation from the hydrogen storage material. In principle, the ratio of one component to another component could be generically extended to fabricate the high-performance bimetallic catalysts on host nanostructures. Indeed, we demonstrate that the bimetallic catalyst composed of the optimum composition results in the excellent hydrogen generation property from an aqueous borane ammonia solution, thus being capable of satisfying the Depart of Energy in USA target required for many advanced applications even with the small amount of our bimetallic catalysts attached onto the N-doped carbon nanotubes. This high hydrogen generation rate is found to be attributed to the optimal distance between active Pt and cheap Ni atoms for effective hydrogen generation.

• 한국경영과학회지
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• 제27권4호
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• pp.41-65
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• 2002

We study a multi-component production/inventory system in which individual components are made to meet various demand types. We assume that the demands arrive according to a Poisson process, but there is a fixed probability that a demand requests a particular kit of different components. Each component is produced by a flow line with several stations in which the processing times of each station follow a two-stage Coxian distribution. The production of each component is operated by an independent base-stock policy with blocking. We assume that the time needed to assemble final products follows a general distribution and the capacity of an assembling facility is sufficiently large. The objective of this study is to obtain key performance measures such as the distribution of the number of each orders for each final product and the mean time of fulfilling a customer order. The basic principle of the proposed approximation method is to decompose the original system into a set of subsystems, each subsystem being associated with a flow line. Each subsystem is analyzed in isolation using a Marie's method. An iterative procedure is then used to determine the unknown parameters of each subsystem. Numerical results show that the accuracy of the approximation method is acceptable.

• 한국군사과학기술학회지
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• 제2권1호
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• pp.38-60
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• 1999

The main objective of this study is systemization of the technique of ROC quantification and optimization of baseline design by applying CE principle to the acquisition process of a weapon system. QFD and TOA techniques can be employed to a good working example of the conceptual design of a future main battle tank. In this paper, Product Planning Phase, the first phase of four QFD phases, is deployed in terms of eight steps including customer requirements and final product control characteristics. TOA is carried out considering only combat weight. In order to perform combat weight analysis and performance TOA, Preliminary Configuration Synthesis Methodology is used. Preliminary Configuration Synthesis Methodology employs the method of least squares and described linear equations of weight interrelation equation for each component of tank. As a result of QFD based upon the ROC, it was cleared that armor piercing power, main armament, type of ammunition, cruising range, combat weight, armor protection, power loading, threat detection and cost are primary factors influencing design and that combat weight is the most dominant one. The results of TOA based on the combat weight constraint show that 5100 lb reduction was required to satisfy the ROC. The baseline design of a future main battle tank is illustrated with assumption that all phases of QFD are employed to development and production process of subsystems, components, and parts of main battle tank. TOA is applied in iterative process between initial baseline design and ROC. The detailed design of each component is illustrated for a future main battle tank.

• 한국실내디자인학회논문집
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• 제16호
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• pp.29-35
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• 1998

The purpose of this study is to analyze the elements forming interior design and to examine dimensional relationship among the elements which form space through the comparison of the spatial language and semiotics of space for the component of interior design. In addition to that it indtends to derive the principle of design which dominate interior design and the inherent diversified meaning by comparing those elements with the square of semiotic used in semiotics. Through this comparsion the meaning of constituent forming space which can be observed through the comparsion of square of semiotic has redefined flexbility among relational system of elements and this flexible concept make the scope of environment including human being broad and enriched. This study fist of all analyzes various phenomena of social culture review semiotics meta-learning and examines back theoretical ground of semiotics which is needed for space analysis. Second of all in the area of presenting an analysis tool for meaningful analysis this report introduces the square of semiotics which was invented,. A. J. Greimas in order to analyze the meaning of literary work and defind three categories of the progressive research method for the analysis of interior design and research itself. Finally as for the analysis of meaning for interior design this report sets the space and analyzed the space in accordance with the method and research procedure. being

• Journal of Power Electronics
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• 제19권4호
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• pp.881-893
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• 2019

This paper proposes a practical sliding-mode controller design for shaping the impedances of cascaded boost-converter power decoupling circuits for reducing the second order harmonic ripple in photovoltaic (PV) current. The cascaded double-boost converter, when used as power decoupling circuit, has some advantages in terms of a high step-up voltage-ratio, a small number of switches and a better efficiency when compared to conventional topologies. From these features, it can be seen that this topology is suitable for residential (PV) rooftop systems. However, a robust controller design capable of rejecting double frequency inverter ripple from passing to the (PV) source is a challenge. The design constraints are related to the principle of the impedance-shaping technique to maximize the output impedance of the input-side boost converter, to block the double frequency PV current ripple component, and to prevent it from passing to the source without degrading the system dynamic responses. The design has a small recovery time in the presence of transients with a low overshoot or undershoot. Moreover, the proposed controller ensures that the ripple component swings freely within a voltage-gap between the (PV) and the DC-link voltages by the small capacitance of the auxiliary DC-link for electrolytic-capacitor elimination. The second boost controls the main DC-link voltage tightly within a satisfactory ripple range. The inverter controller performs maximum power point tracking (MPPT) for the input voltage source using ripple correlation control (RCC). The robustness of the proposed control was verified by varying system parameters under different load conditions. Finally, the proposed controller was verified by simulation and experimental results.

• 한국실내디자인학회논문집
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• 제21호
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• pp.139-146
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• 1999

Small art museums are important objects in the point of view that they are museums to speak for the general architectural culture of current Korea and immediate factors to have an effect on urban street view and urban people's life. In small art museums, form has had plural transfigurational process when we analyze the external component elements or form types, we will find various aspects. In past, composition of form was expressed by simple partition of surface and columv. Now a days, it is expressed with unnumerable formal vocabularies. Although these forms being looked plural, form principle of composition that prescribe it can be rather simple. This study aims to grasp the characteristics and the composition technique of form in small art museums by analyzing compositional elements of it.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 1996년도 한국자동제어학술회의논문집(국내학술편); 포항공과대학교, 포항; 24-26 Oct. 1996
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• pp.399-402
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• 1996

The electrodynamic loudspeakers should have a wide dynamic range to reproduce various sound levels. When the input signal is small, the radiated sound from the loudspeaker is not so much distorted. However, for large input signal with low frequency component the radiated sound is significantly distorted due to the nonlinearities of the loudspeaker. The suspension, damping, and magnetic flux of loudspeaker are the main sources of the nonlinearity. Such electromechanical parameters related to harmonic distortion have been represented by a polynomial model for diaphragm displacement, while each of the polynomial coefficient is evaluated by using the principle of harmonic balance experimentally. Based on the polynomial model, we designed a compensator for nonlinear harmonic distortion of direct radiator loudspeaker. Than observer is used to estimate the displacement of the loudspeaker diaphragm, which is rather difficult to measure directly in the conventional setting. The usefulness of the designed compensator is demonstrated by numerical simulations. Simulation results show about 30db decrease at the second and third higher harmonic distortions. We carry out an experiment on speaker to verify designed controller and nonlinear observer.

• 동력기계공학회지
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• 제10권2호
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• pp.68-74
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• 2006

In the development of new automobiles, the efforts to reduce environmental problems like air pollution have been risen. Blowby gas consists of about $20{\sim}35%$ of total amount of Hydrocarbon (HC), one of dangerous pollutants issuing from automobiles. A PCV valve is a very small component in an automotive engine but it is a very important part. Because that a PCV valve is used to control blowby gas and to recirculate it into a manifold automatically. Although it has very simple operating principle, designing a PCV valve is so difficult due to interaction between fluid and solid. In this study, our purpose is to develop a design program for a PCV valve and to verify its efficiency. Both Bernoulli equation and 4th order Runge-Kutta method were adopted to predict spool displacements and flow patterns. Comparing with experiments, it was found that both spool diameters and displacements were predicted well, however, flow rates showed a little differences because of the assumption of non viscous flow.

• 동력기계공학회지
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• 제14권2호
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• pp.55-59
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• 2010

In the study, it is considered sporty car as 1400cc entry cars using sound generator. These cars are required special sound quality, also sporty sound quality. The operational principle of this sound generator system is that on the operation of the engine intake valves caused pulsating is to shake the membrane of the sound generator on the inside of the driver front dash panel through the intake manifold, which will deliver the required sound quality and tone. For the component constructed sound generator, main design parameters are selected and optimized using the daguchi's method. The results are as follows; The C2 sound level must be minimized and C4 level must be maximized. And also overall level keeps linear characteristics.

• Child Health Nursing Research
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• 제4권1호
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• pp.128-149
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• 1998

Cigarette smoking has been identified as the single most important source of preventable morbidity and mortality. Smoking behavior varies each individual, so individuality & subjectivity of smoking behavior must be specially focused upon to understand smoking behavior. The purpose of this study was to find attitudes of university students in the prediction of smoking behavior. Q-Methodological method was used as a research design and data were collected during the period from Jan.1, 1997 to Feb. 28, 1998. As the research method, Q-statements were collected through in- depth interviews and a literature review. For the study 33 Q-statements were selected. There were 45 university students as subjects for the research. The 45 university students sorted the 33 statements using the principle of Forced Normal Distribution. The principle of Forced Normal Distribution, which has nine scales to measure the individual opinions, Pc Quanl program was used for analysis and Q-factors were analyzed by using principal component analysis. According to the results of this study, there were four categories of opinion about the smoking behavior in university students. The first type is seeking the habitual dependency. The second type is seeking the stress relief : The third type is seeking the active disapproval : The fourth type is seeking the self control. As a result, The meaning of the smoking behavior is affected by perceived subjective experience, so we need to understand each persons meaning of the smoking behavior and to develop appropriate nursing interventions based on the typology of smoking behavior. Finally, The result of the study will provide basic data for smoking prevention and cessation program.