• Journal of the Korean Vacuum Society
• /
• v.12 no.S1
• /
• pp.60-62
• /
• 2003

In this study we report the results of ab initio first-principles calculations to investigate the possibility of metamagnetic behavior in Fe$_3$Al alloy. We used the WIEN2k package of full-potential linearized-augmented- plane-wave method within the local-spin-density approximation to the density-functional theory. The exchange-correlation functional is the generalized-gradient approximation of Perdew-Burke-Ernzerhof. The theoretical lattice constant, which is about 0.5% smaller than the experimental one, is obtained by minimizing the total energy. If the volume decreases about 9 % from the equilibrium, the total magnetic moment decreases abruptly from 4.6 $\mu_{B}$/f.u. to 4.0 $\mu_{B}$/f.u. Since this change is considerably large (∼14%), it is possible to measure by a simple high-pressure experiment at about 180 kbar.

• Proceedings of the KIEE Conference
• /
• 2003.11c
• /
• pp.998-1001
• /
• 2003

In this paper, a entertainment biped robot controlled by R/C servo motors is built using the embedded RTOS (Real Time Operating System). uC/OS-II V2.00 is used for RTOS and control algorithm of R/C servo motors is proposed based on uC/OS-II's preemptive and deterministic property without any extra PWM module. The realized biped robot has 19 DOF, and a board 80C196KC as main CPU. To verify the proper walking process, ZMP(Zero Moment Point) theory is applied and ADAMS is used for simulation.

• Journal of applied mathematics & informatics
• /
• v.39 no.5_6
• /
• pp.689-701
• /
• 2021

The purpose of this paper is to optimize the number of source places required for the unique representation of the destination using the tools of graph theory. A subset S of vertices of a graph G is called a rational resolving set of G if for each pair u, v ∈ V - S, there is a vertex s ∈ S such that d(u/s) ≠ d(v/s), where d(x/s) denotes the mean of the distances from the vertex s to all those y ∈ N[x]. A rational resolving set is called minimal rational resolving set if no proper subset of it is a rational resolving set. In this paper we study varieties of minimal rational resolving sets defined on the basis of its complements and compute the minimum and maximum cardinality of such sets, respectively called as lower and upper rational metric dimensions for power of a path P_n analysing various possibilities.

• Communications of the Korean Mathematical Society
• /
• v.37 no.3
• /
• pp.735-748
• /
• 2022

The global well-posedness for the fourth-order modified Zakharov equations in 1-D, which is a system of PDE in two variables describing interactions between quantum Langmuir and quantum ionacoustic waves is studied. In this paper, it is proven that the system is globally well-posed in (u, n) ∈ L² × L² by making use of Bourgain restriction norm method and L² conservation law in u, and controlling the growth of n via appropriate estimates in the local theory. In particular, this improves on the well-posedness results for this system in [9] to lower regularity.

• Asia pacific journal of information systems
• /
• v.32 no.3
• /
• pp.514-536
• /
• 2022

Online reviews offer valuable information to businesses by reflecting consumer experiences about their products and services. Two crucial aspects of online reviews are the topics consumers choose to address, and the sentiments expressed in their reviews. Building upon previous literature that shows online reviews are context-dependent, we employ the Expectation-Confirmation Theory (ECT) to examine the impact of topic distribution on review sentiment in South Korea and the U.S. during pre- and post-pandemic periods. After applying a topic modeling to Airbnb app review data, we measure the contribution of each topic on review sentiment using SHAP values. Our results indicate variations in topic distribution trends between 2018 and 2021. In addition, the order and magnitude of topics' impact on review sentiment change between pre- and post-pandemic periods for both countries. This study can help businesses understand how topics and sentiments associated with their products and services changed after the pandemic and thus identify areas of improvement.

• Journal of the East Asian Society of Dietary Life
• /
• v.15 no.3
• /
• pp.346-356
• /
• 2005

This study was conducted to investigate how to apply the theories of oriental medicine appropriately, which direction should be taken, and how it should be developed The results are as follows. First, to develop medicinal cuisine, it is necessary to grasp the theoretical system, considering Ohaeng and Omi, the five viscera and the six entrails, organs and body, by raising the level of understanding comprehensively about the relationship between the characteristics of each groups of Sasang Constitutions and the theories of Eumyangohaeng, and the relationship between the theory of Kimi. and food, and then to explain developed medicinal cuisine and apply those theories to inventing new ones. Secondly, to develop medicinal cuisine for health enhancement, it is also required not only to consider constitutions but also to suggest the need of knowledge for moderation in terms of regimen along with the theory of Kimi. Thirdly, to develop medicinal cuisine according to the perspective of Kimi. Theory, what should be taken into account is not only the understanding of the characteristics of food materials, but also the properties of them that the theory of Kimi, Eumyangohaeng, and Sasang Constitutions share so that it is possible to invent medicinal cuisine which is good for anybody to protect disease specific to a certain group of constitutions with, and serves as the dietary regimen customed to each constitution group. Lastly, the scientific effect of the medicinal cuisine which is developed according to the theory of Kimi., Eumyangohaeng, and Sasang Constitutions should be verified by scientific researches and clinical experiments. And it is believed to be essential for the government to make efforts to set a standard and laws to validate the medicinal effects and the process of assessment so that the systematic development can be encouraged, and to prepare guidance to food development for national health improvement.

• The Journal of Art Theory & Practice
• /
• no.10
• /
• pp.133-158
• /
• 2010

Der Beitrag befasst sich mit der partizipatorischen Inszenierung von Medienkunst im $\"{o}$ffentlichen Raum. Das Medienkunstprojekt' Energie-Passagen' von Monika Fleischmann und Wolfgang Strauss ist ein Ausdruck des Ubergangs zwischen realer und virtueller $\"{U}$mgebung. In der Verbindung von physikalischem Raum und digitalen Artefakten er$\"{o}$ffnet die Installation einen real/virtuell $\"{u}$berlagerten Wahrnehmungsraum und misst die Energie der Stadt auf metaphorische Weise. Die gemeinsame Erfahrung des Lesens und Schreibens t$\"{a}$glicher Nachrichten und ihrer Transformation in ein Sprachspiel assoziativer Splitter und Plateaus zu einer rhizomatischen Verweisstruktur bestimmt die interaktive Handlung. Das Publikum wird zu kommunikativer Performanz eingeladen und die Interaktivit$\"{a}$t des Geschehens wird als Statistik der Ereignisse im Internet dokumentiert und als Energie-Bild der Stadt visualisiert. Inszeniert als ein Fluss von Worten, wird die Installation zu einem begehbaren Informationsbrowser, der zum Flanieren in den Nachrichten einl$\"{a}$dt. Die Idee einer Mixed-Reality-B$\"{u}$hne bestimmt den interaktiven Denkraum zum Lesen und Be-Schreiben der Stadt.

• Bulletin of the Korean Mathematical Society
• /
• v.33 no.4
• /
• pp.603-611
• /
• 1996

Let consider the following problem: find an element u(t) in a Banach space U from the equation $$ x'(t) = Ax(t) + f(t,x(t)) + \Phi_0 u(t), 0 \leq t \leq T $$ with initial and terminal conditions $$ x(0) = 0, x(T) = \phi $$ in a Banach space X where $\phi \in D(A)$. This problem is a kind of control engineering inverse problem and contains nonlinear term, so that it is difficult and interesting. Thee proof main result in this paper is based on the Fredholm property of [1] in section 3. Similar considerations of linear system have been dealt with in many references. Among these literatures, Suzuki[5] introduced this problem for heat equation with unknown spatially-varing conductivity. Nakagiri and Yamamoto[2] considered the identifiability problem, which A is a unknown operator to be identified, where the system is described by a linear retarded functional differential equation. We can also apply to determining the magnitude of the control set for approximate controllability if X is a reflexive space, i.e., we can consider whether a dense subset of X is covered by reachable set in section 4.

• Bulletin of the Korean Mathematical Society
• /
• v.57 no.3
• /
• pp.649-660
• /
• 2020

This paper proves a new regularity criterion for solutions to the Cauchy problem of the 3D Boussinesq equations via one directional derivative of the horizontal component of the velocity field (i.e., (∂_iu₁; ∂_ju₂; 0) where i, j ∈ {1, 2, 3}) in the framework of the anisotropic Lebesgue spaces. More precisely, for 0 < T < ∞, if $$\large{\normalsize\displaystyle\smashmargin{2}{\int\nolimits_o}^T}({\HUGE\left\|{\small{\parallel}{\partial}_iu_1(t){\parallel}_{L^{\alpha}_{x_i}}}\right\|}{\small^{\gamma}_{L^{\beta}_{x_{\hat{i}}x_{\bar{i}}}}+}{\HUGE\left\|{\small{\parallel}{\partial}_iu_2(t){\parallel}_{L^{\alpha}_{x_j}}}\right\|}{\small^{\gamma}_{L^{\beta}_{x_{\hat{i}}x_{\bar{i}}}}})dt<{{\infty}},$$ where ${\frac{2}{{\gamma}}}+{\frac{1}{{\alpha}}}+{\frac{2}{{\beta}}}=m{\in}[1,{\frac{3}{2}})$ and ${\frac{3}{m}}{\leq}{\alpha}{\leq}{\beta}<{\frac{1}{m-1}}$, then the corresponding solution (u, θ) to the 3D Boussinesq equations is regular on [0, T]. Here, (i, ${\hat{i}}$, ${\tilde{i}}$) and (j, ${\hat{j}}$, ${\tilde{j}}$) belong to the permutation group on the set 𝕊₃ := {1, 2, 3}. This result reveals that the horizontal component of the velocity field plays a dominant role in regularity theory of the Boussinesq equations.

• Proceedings of the KSME Conference
• /
• 2003.11a
• /
• pp.616-621
• /
• 2003

Fluid-elastic instability is believed to be a cause of the large-amplitude vibration and resulting rapid wear of heat exchanger tubes when the flow velocity exceeds a critical value. For sub-critical flow velocities, the random turbulence excitation is the main mechanism to be considered in predicting the long-term wear of steam generator tubes. Since flow-induced interactions of the tubes with tube supports in the sub-critical flow velocity can cause a localized tube wear, tube movement in the clearance between the tube and tube support as well as the normal contact force on the tubes by fluid should be maintained as low as possible. A simplified method is used for predicting fretting-wear damage of the double $90^{\circ}$U-bend tubes. The approach employed is based on the straight single-span tube analytical model proposed by Connors, the linear structural dynamic theory of Appendix N-1300 to ASME Section III and the Archard's equation for adhesive wear. Results from the presented method show a similar trend compared with the field data. This method can be utilized to predict the fretting-wear of the double $90^{\circ}$U-bend tubes in steam generators.