• 한국신재생에너지학회:학술대회논문집
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• 2011.05a
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• pp.96.1-96.1
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• 2011

Solid oxide fuel cells(SOFCs) can convert the chemical energy of fuel into electricity directly. With the rising fuel prices and stricter emission requirement, SOFCs have been widely recognized as a promising technology in the near future. In this study, lean premixed flame using the orifice swirl burner was analyzed numerically and experimentally. We used the program CHEMKIN and the GRI 3.0 chemical reaction mechanism for the calculation of burning velocity and adiabatic flame temperature to investigate the effects of equivalence ratio on the adiabatic flame temperature and burning velocity respectively. Burning velocity of hydrogen was calculated by CHEMKIN simulation was 325cm/s, which was faster than that of methane having 42 cm/s at the same equivalence ratio. Also Ansys Fluent was used so as to analysis the performance with alteration of swirl structure and orifice mixer structure. This experimental study focused on stability and emission characteristics and the influence of swirl and orifice mixer in Solid Oxide Fuel Cell Systme burner. The results show that the stable blue flame with different equivalence ratio. NOx was measured below 20 ppm from equivalence ratios 0.72 to 0.84 and CO which is a very important emission index in combustor was observed below 160 ppm under the same equivalence region.

• Journal of the Korean Society of Propulsion Engineers
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• v.22 no.2
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• pp.131-137
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• 2018

This paper analyzes the probability of failure for the equivalence ratio error. The control error of the equivalence ratio is affected by the aleatory and epistemic uncertainties. In general, reliability analysis techniques are easily incorporated to handle the aleatory uncertainty. However, the epistemic uncertainty requires a new approach, as it does not provide an uncertainty distribution. The Bayesian inference incorporates the reliability analysis results to handle both uncertainties. The result gives a distribution of failure probability, whose equivalence ratio does not meet the requirement. This technique can be useful in the analysis of most engineering systems, where the aleatory and epistemic uncertainties exist simultaneously.

• 제어로봇시스템학회:학술대회논문집
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• 1992.10b
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• pp.405-412
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• 1992

The problem we consider in this paper is more demanding than the problem of input-output linearization with state equivalence recently solved by Cheng, Isidori, Respondek, and Tarn. We request that the MIMO nonlinear system, for which the problem of input-output linearization with state-equivalence is solvable, can be decoupled. In exchange for further requirement like this, our problem produces more usable and informative results than the problem of input-output linearization with state-equivalence. We present the necessary and sufficient conditions for our problem to be solvable. We characterize each of the nonlinear systems satisfying these conditions by a set of parameters which are invariant under the group action of state feedback and transformation. Using this set of parameters, we can determine directly the unique one, among the canonical forms of decouplable and controllable linear systems, to which a nonlinear system can be transformed via appropriate state feedback and transformation. Finally, we present the necessary and sufficient conditions for our problem to be solvable with internal stability, that is, for stable decoupling.

• Journal of Arbitration Studies
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• v.23 no.2
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• pp.81-113
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• 2013

The World Trade Organization (WTO) offers remedies for non-compliance by the introduction of compensation or retaliation in the Dispute Settlement Understanding (DSU). There are no the provisions under the WTO DSU and it seems unclear what retaliation is attempting to achieve. Therefore, it is unclear whether the goal of WTO retaliation is to induce compliance or to restore the balance between the rights and the obligations of WTO members. It has been claimed the WTO has a strong dispute settlement system by providing retaliation when the recommendations and rulings of Dispute Settlement Body (DSB) are not complied with. But this seems to be inadequate to bring about effective and timely compliance. Especially there is a problem with free riding by a violating member because the level of retaliation is determined from the expiration of a reasonable period of time, providing an incentive to delay compliance. Also the level of the suspension of concessions or other obligations authorized by the DSB is equivalent to the level of nullification or impairment, according to DSU Article 22.4. However, if the member concerned objections to the level of the suspension proposed, the matter shall be referred to arbitration. The arbitrator shall not examine the nature of the suspension of concessions or other obligations to be suspended but shall determine whether the level of such suspension is equivalent to the nullification or impairment. The arbitrator makes an assessment standard of equivalence by comparing the suspension of concessions or other obligations and the nullification or impairment calculated in terms of the amount of trade. But it is necessary that other standards replace the quantitative standards when the level of the nullification or impairment cannot be quantified by concrete damages.

• International Journal of Fuzzy Logic and Intelligent Systems
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• v.4 no.2
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• pp.249-253
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• 2004

When we decide the software quality on the basis of the software measurement, the transitive property which is a requirement for an equivalence relation is not always satisfied. Therefore, we propose a scheme for classifying the software quality that employs a tolerance relation instead of an equivalence relation. Given the experimental data set, the proposed scheme generates the tolerant classes for elements in the experiment data set, and generates the tolerant ranges for classifying the software quality by clustering the means of the tolerance classes. Through the experiment, we showed that the proposed scheme could product very useful and valid results. That is, it has no problems that we use as the criteria for classifying the software quality the tolerant ranges generated by the proposed scheme.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.43 no.7
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• pp.593-600
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• 2015

In this study, a combined hybrid rocket system is newly introduced which has characteristics of both gas generators and afterburner type hybrid rockets. In particular, a combined gas generator utilizing solid fuel and liquid/gas oxidizer was designed as a primary combustor of the system. Combustion tests were carried out with various equivalence ratio affected by parameters such as fuel length, oxidizer flow rate, fuel port diameter and fuel type. In general, fuel-rich gas generator produces low combustion gas temperature to meet the temperature requirement and the target temperature was transiently set less than 1600 K. Since it was found that controlling parameters showed limited effects on the change of equivalence ratio, mixture of $O_2$ and $N_2$ as an oxidizer was additionally introduced. As a result, a combined gas generator successfully produced combustion gas temperature of less than 1600 K Future studies will carry out more combustion tests to attain fuel-rich combustion gas temperature less than 1200 K, which was a temperature requirement of a gas generator system in the previous studies.

• Proceedings of the KSR Conference
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• 2011.10a
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• pp.3019-3026
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• 2011

The pantograph on HEMU400 perform the simulation of following characteristics for pantograph's performance prediction and confirming the EN50119's requirement. To meet the performance requirements for the input data are proposed. Simulation result of the performance requirements are satisfied from proposed input data. The new model was developed by proposed data base on the simulation result. A new developed model data used in following characteristics meet to be sure about what the test was done to count the equivalence of mass. Depending on the results of test to performance prediction, and propose research directions.

• Bulletin of the Korean Mathematical Society
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• v.55 no.4
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• pp.1303-1315
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• 2018

For principal component analysis (PCA) to efficiently analyze large scale matrices, it is crucial to find a few singular vectors in cheaper computational cost and under lower memory requirement. To compute those in a fast and robust way, we propose a new stochastic method. Especially, we adopt the stochastic variance reduced gradient (SVRG) method [11] to avoid asymptotically slow convergence in stochastic gradient descent methods. For that purpose, we reformulate the PCA problem as a unconstrained optimization problem using a quadratic penalty. In general, increasing the penalty parameter to infinity is needed for the equivalence of the two problems. However, in this case, exact penalization is guaranteed by applying the analysis in [24]. We establish the convergence rate of the proposed method to a stationary point and numerical experiments illustrate the validity and efficiency of the proposed method.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.25 no.6
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• pp.406-413
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• 2015

The piezoelectric coupling in piezoelectric vibration energy harvesters with load resistance induces electrical damping as well as increase in the system stiffness. Starting from analytically deriving the explicit relations through governing equations in the frequency domain, this work identifies the characteristics of the electrically induced damping mechanism and shows that the electrically induced damping serves as a structural hysteretic damping on condition that a piezoelectric vibration energy harvester is excited at its short-circuit resonant frequency and its load resistor is optimally impedance- matched at the same time. Finally, it is analytically verified that the equivalence of a mechanical and an electrically induced damping ratio is required for the maximum power generation at a load resistor, which was claimed in some literature.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2019.05a
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• pp.51-52
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• 2019

Currently in domestic, it is difficult to the evacuation in fire due to the building is higher. Therefore it is necessary to evacuation safety design of building. To conduct the evacuation fire design of building, it should be done the Evacuation Safety Verification. But it is not sufficient the Study about Evacuation Safety Verification in currently domestic. Therefore in this study, we conducted the evacuation safety verification using people who they can't the evacuation themselves. The method of verification, we suggest the comparative that people who they can't the evacuation themselves and available safety evacuation time. Available safety evacuation time is determined by determined method from disaster statistics of casualties or equivalence with current standard requirement. it is doing to objectively judge of evacuation safety design validity in building.