• Nuclear Engineering and Technology
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• v.51 no.5
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• pp.1261-1271
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• 2019

Droplet size and distribution are important parameters determining venturi scrubber performance. In this paper, we proposed physical models for a maximum stable droplet size prediction and upper limit log-normal (ULLN) distribution parameters. For the proposed maximum stable droplet size prediction model, a Eulerian-Lagrangian framework and a Reitz-Diwakar breakup model are solved simultaneously using CFD calculations to reflect the effect of multistage breakup and droplet acceleration. Then, two ULLN distribution parameters are suggested through best fitting the previously published experimental data. Results show that the proposed approach provides better predictions of maximum stable droplet diameter and Sauter mean diameter compared to existing simple empirical correlations including Boll, Nukiyama and Tanasawa. For more practical purpose, we developed the simple, one dimensional (1-D) calculation of Sauter mean diameter.

• Communications of the Korean Mathematical Society
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• v.34 no.2
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• pp.685-699
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• 2019

This research is focused on a continuous epidemic model of transmission of Plasmodium vivax malaria with a time delay. The model is represented as a system of ordinary differential equations with delay. There are two equilibria, which are the disease-free state and the endemic equilibrium, depending on the basic reproduction number, $R_0$, which is calculated and decreases with the time delay. Moreover, the disease-free equilibrium is locally asymptotically stable if $R_0<1$. If $R_0>1$, a unique endemic steady state exists and is locally stable. Furthermore, Hopf bifurcation is applied to determine the conditions for periodic solutions.

• Bulletin of the Korean Chemical Society
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• v.8 no.3
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• pp.155-157
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• 1987

Parameters of intraframework potential function suitable for aluminophosphate-5($AIPO_4-5$) are obtained by the constraint method. Using these parameters, we calculated the stabilization energies and their second derivatives of framework atoms and these values are compared with those of zeolite A. It is found that the oxygen atoms in $AIPO_4-5$ framework are more stable than those of zeolite A and that the aluminum atom is also more stable than that of zeolite A. On the other hand, the phosphorus atom in $AIPO_4-5$ framework, in which the silicon atoms of aluminosilicate are replaced by the phosphorus atom, is less stable than the silicon atom of aluminosilicate framework of dehydrated zeolite A.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.22 no.1
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• pp.93-98
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• 2012

MANET composed of only moving nodes is concerned to core technology to construct ubiquitous computing environment. Also, it is a lack of security because of no middle infrastructure. So, it is necessary to intrusion detection system which can track malicious attack. In this study, cluster was used to stable intrusion detection, and rule about various attacks was defined to detect accurately attack that seems like network problem. Proposed method through experience was confirmed that stable detection rate was showed although number of nodes increase.

• Journal of the Korea Institute of Military Science and Technology
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• v.25 no.5
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• pp.545-551
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• 2022

We proposed a design method for constant current pyro squib circuit. The current method using N MOSFET for the stability problem has a weakness of the current change, requiring a new design. This paper identified the problem with conventional squib circuit where the current is reduced by 25 % when maximum resistance is 3 ohms. Thus, we proposed a stable constant current driving circuit using P MOSFET and PNP BJT. We confirmed stable constant circuit operation through simulations and measurements of the proposed circuit design where the current did not change until the resistance reached 3 ohms.

• 제어로봇시스템학회:학술대회논문집
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• 2001.10a
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• pp.151.5-151
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• 2001

Sliding mode control is investigated for a discrete-time system with uncertainties. The narrowest neighborhood of the sliding surface is shown in which the state can remain. The range is determined by the upper bound of the absolute value of the uncertainty and the equation of the sliding surface. A sliding mode control algorithm is proposed to keep the state there without requiring an enormous input. Under the presence of the system parameter variations, the origin is not always stable although the sliding surface represents the stable dynamics and the state is kept in this neighborhood. The condition for the origin to be stable is investigated. Furthermore, the problems occurring when a continuous-time sliding mode control being ...

• Journal of the Chungcheong Mathematical Society
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• v.36 no.1
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• pp.1-8
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• 2023

Let C be a smooth projective curve and W a symplectic bundle over C of degree w. Let π : 𝕃𝔾(W) → C be the relative Lagrangian Grassmannian over C and S_d(W) be the space of Lagrangian subbundles of degree w -d. Then Kontsevich's space ${\bar{\mathcal{M}}}_g$(𝕃𝔾(W), β_d) of stable maps to 𝕃𝔾(W) is a compactification of S_d(W). In this article, we give an upper bound on the dimension of ${\bar{\mathcal{M}}}_g$(𝕃𝔾(W), β_d), which is an analogue of a result in [8] for the relative Lagrangian Grassmannian.

• Bulletin of the Korean Mathematical Society
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• v.61 no.3
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• pp.585-595
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• 2024

We show that a pseudo-Anosov map constructed as a product of the large power of Dehn twists of two filling curves always has a geodesic axis on the curve graph of the surface. We also obtain estimates of the stable translation length of a pseudo-Anosov map, when two filling curves are replaced by multicurves. Three main applications of our theorem are the following: (a) determining which word realizes the minimal translation length on the curve graph within a specific class of words, (b) giving a new class of pseudo-Anosov maps optimizing the ratio of stable translation lengths on the curve graph to that on Teichmüller space, (c) giving a partial answer of how much power is needed for Dehn twists to generate right-angled Artin subgroup of the mapping class group.

• Structural Engineering and Mechanics
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• v.89 no.6
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• pp.571-578
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• 2024

The bistable thin cylindrical shell is developable structure with the ability to transition between its two stable configurations. This structure offers significant potential applications due to its excellent deformability. In this paper, the composite thin cylindrical shell consisting of the composite layer and the piezoelectric layer was investigated. The material and geometric parameters of the shell were found to influence its stable characteristics. The analysis model of the composite thin cylindrical shell incorporating the piezoelectric layer was developed, and the expressions for its strain energy were derived. By applying the minimum energy principle, the impact of the electric field intensity on the bi-stable behaviors of the cylindrical shell was analyzed. The results showed that the shell exhibited the bistability only under the appropriate electric field strength. And the accuracy of the theoretical prediction was verified by simulation experiments. This study provides an important reference for the application of deployable structures.

• Korean Circulation Journal
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• v.54 no.4
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• pp.165-171
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• 2024

Beta blockers are one of the commonest prescription drugs in medicine and they have been thought to revolutionize the treatment of heart failure (HF) with reduced ejection fraction (HFrEF) in the last century. In addition to HFrEF, they are prescribed for a variety of diseases in cardiology from hypertension to HF, angina, and stable coronary artery disease (CAD). The increased prescription of beta blockers in conditions like HF with preserved ejection fraction (HFpEF), and stable CAD may be doing more harm than good as per the data we have so far. The available data shows that beta blockers are associated with increased stroke risk and atrial fibrillation (AF) in hypertension and in patients with HFpEF, they have been associated with decreased exercise capacity. In patients with stable CAD and patients with myocardial infarction with normal systolic functions, beta blockers don't offer any mortality benefit. In this article, we critically review the common indications and the uses of beta blockers in patients with HFpEF, CAD, hypertension and AF and we propose that beta blockers are overprescribed under the shadow of their beneficial effects in patients with HFrEF.