• Journal of the Korea Academia-Industrial cooperation Society
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• v.11 no.5
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• pp.1735-1740
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• 2010

The propellant KM10, a single propellant manufactured nitrocellulose, is known to cause natural degradation phenomena at long term storage. The self-life was estimated using generally used high temperature acceleration aging tests to analyze the content of stabilizer and using the Arrhenius equation & Berthelot equation to calculate reaction rate constants. According to the result of this study, self-life of propellant KM10 using the Arrhenius equation & Berthelot equation appear significantly different as 43.73, 16.53years and when compared with the paper of E. R. Bixon, self-life of propellant KM10 predicted using the Arrhenius equation was reasonably determined.

• Structural Engineering and Mechanics
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• v.39 no.4
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• pp.465-498
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• 2011

Concrete structures are generally cracked in flexural tension at working loads. Concrete beams with asymmetric section details and crack patterns exhibit different flexural rigidity depending upon the sense of the applied flexural moment. In this paper, three different models, having the same natural period, of such SDOF bilinear dynamical systems have been proposed. The Model-I and Model-II have constant damping coefficient, but the latter is characterized by two stiffness coefficients depending upon the sense of vibration amplitude. The Model-III, additionally, has two damping coefficients as well. In this paper, the dynamical response of Model-III to sinusoidal loading has been investigated and compared with that of Model-II studied earlier. It has been found that Model-III exhibits regular and irregular sub-harmonics, jump phenomena and strong sensitivity to initial conditions, forcing frequency, system period as well as the sense of peak sinusoidal force. The constant sustained load has been found to affect the natural period of the dynamical system. The predictions of Model-I have been compared with those of the approximate linear model adopted in present practice. The behaviour exhibited by different models of the SDOF cracked elastic concrete structures under working loads and the theoretical and practical implications of the approach followed have been critically evaluated.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.23 no.7
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• pp.662-668
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• 2013

In this paper, possibility of controlling motion of a floating structure using a tuned liquid damper (TLD) is numerically investigated. A TLD is a tank partially filled with liquid. Sloshing motion of liquid inside a tank is known to suppress movement of the tank subject to external excitations at specific frequency. The effects of sloshing phenomena inside a rectangular floating body on its surge motion are investigated by varying external excitation frequency. First, a grid-refinement study is carried out to ensure validity of grid independent numerical solutions using present numerical techniques. Then, surge motion of the floating body subjected to external wave is simulated for five different excitation frequencies of which the center frequency equals to the natural frequency of internal liquid sloshing. The normalized amplitudes of surge motion of the target floating body are compared according to the excitation frequency, for the cases with and without water inside the floating body. It is shown that the motion of the floating body can be minimized by matching the sloshing natural frequency to the excitation frequency.

• The Journal of Natural Sciences
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• v.12 no.1
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• pp.41-48
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• 2002

Atomic coherences can be induced via atom-light interaction and can exhibit new interesting phenomena. Electromagnetically-induced-absorption (EIA) is one of such phenomena where the absorption of probe beam is increased due to the presence of strong coupling beam. EIA can be observed in multiple-V type atomic systems. This paper present a method to study EIA when the frequencies of probe beam and coupling beam are both near resonant to the same transition line. Time-varying interaction Hamiltonian was introduced and density matrix equations were solved and the amplitude of oscillations was used to calculate the EIA.

• Nuclear Engineering and Technology
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• v.56 no.2
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• pp.611-623
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• 2024

The ISP-47 TOSQAN experiment was analyzed with containmentFOAM which is an open-source CFD code based on OpenFOAM. The containment phenomena taking place during the experiment are gas mixing, stratification and wall condensation in a mixture composed of steam and non-condensable gas. The k-ω SST turbulence model was adopted with buoyancy turbulence models. The wall condensation model used is based on the diffusion layer approach. We have simulated the full TOSQAN experiment which had a duration 20000 s. Sensitivity studies were conducted for the buoyancy turbulence models with SGDH and GGDH and there were not significant differences. All the main features of the experiments namely pressure history, temperature, velocity and gas species evolution were well predicted by containemntFOAM. The simulation results confirmed the formation of two large flow stream circulations and a mixing zone resulting by the combined effects of the condensation flow and natural convection flow. It was found that the natural convection in lower region of the vessel devotes to maintain two large circulations and to be varied the height of the mixing zone as result of sensitivity analysis of non-condensing wall temperature. The computational results obtained with the 2D mesh grid approach were comparable to the experimental results.

• Journal of the Korean Society of Hazard Mitigation
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• v.4 no.3 s.14
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• pp.33-41
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• 2004

The purpose of this study is to analyze the relationship between El Nino phenomena and the monthly rainfall variations of Seoul city which is composed of 30 year data during $1967{\sim}1996$. In this study, the monthly rainfall data at Seoul city is analyzed by applying an intervention model. As it is unavailable to get the data of El Nino phenomena, the point of intervention have been decided from the literature survey of the data observed to be the years of 1972, 1976, 1979, 1982, 1986 and 1991. As a results the El Nino was revealed more significant to the monthly rainfall at Seoul. In addition, monthly rainfall varied between the maximum 53.41mm and the minimum 2.50mm. To prevented future natural disaster, long term water planning and management is requied in consideration El $Nin\tilde{o}$.

• The Korean Journal of Quaternary Research
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• v.14 no.1
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• pp.49-55
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• 2000

The Yellow-Sand phenomena occurred during the period from l0C to 14C in Korea have been investigated using the historical record of the Koryosa. It is written as the "dust rain"or "mud" which means the falling down of dust from the sky. The authors have extracted 50 historical writings of dust rain from the Koryosa. The results show that the observation records concerning Yellow-Sand phenomenon for the period of Korea Dynasty (918~1392) are described with the scientific accuracy for the Yellow-Sand phenomena as the pure dust phenomena, the mixture of Yellow Sand with snow or rain, and the Yellow-Sand associated with fog or hail, etc. It is also found that the occurrence of Yellow-Sand phenomena was the incomprehensible natural phenomena such as Yellow-Sand were interpreted as a warning from the Heaven to the king and people of their fail in moral principles.in moral principles.

• Journal of Korean Medical classics
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• v.3
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• pp.280-398
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• 1989

The most distintive features on the Thinking Structure of the Views of the Nature and the Theories of the Medicine of the ancient Chinese are a Comprehensions to the System of the Nature which reveals in the Natural Phenomena. Nothing doesn't changed in the Nature and man also. These Changes are inevitable to the man. So it isn't easy to grasp the Essence of the Natural Phenomena which always be changed. I-Ching (易經, Book of Changes), Chung-Yung (中庸) and many other books are that has a theories about the Changes, the ancients could recognized the unchangeable constancy from the ever changeable Natural Phenomena. The unchangeable constancy on the Oriental thinking means as same as an 'Idea' on the Western thinking. These process made them shape up the Views of the Nature and the Medical theories. And Chi (氣), Yin-Yang (陰陽) and Wu-Hsing (五行) are the most important concepts of their views and theories. In the concepts of Chi as an epistemological meaning; the Nature and the Han can be appreciated as a one System, because his being is within the Changes of the Nature and should be in accord with those Changes. He was going to believe that all beings are exist as an existential rules of himself. So Chi can be thougt as an epistemological system to all beings' existence. Thinking of Yin-Yang as a existential meaning; all beings are exist having a contrary and a complementary to each other. Birth and Death, Be ginning and Finishing in a series of the process occurs in all beings are the two sides of their existential and intrinsic tendencies. That can be condensed to the Yin-Yang concepts. In the consideration of Wu-Hsing;all beings are observed and explained more deliberatively by it's own rules. By the way the concepts of Chi, Yin-Yang and Wu-Hsing which derived from the processes of the recognition to the Changes of the Nature are practiced actually by the thoughts of Harmony. And it is represented by the accordance to the Time of the Natural Changes, that is, Shiling (時令). It means a adjustments to the Time and Changes of the Nature. The health of all beings that is an aim of the Medicine can be maintained by their practical thoughts or the concepts of Shiling.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.15 no.11
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• pp.6621-6629
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• 2014

Social phenomena require the fundamentals of novel scientific epistemology and methodology due to the continual change by complex variables. A systematic understanding of paradigm shifts is also necessary for analyzing the problems currently faced in society. This study presents chaos theory, which was developed from the natural sciences, to discuss the abnormality of modern society that underscores the importance of the chaos paradigm. Chaos theory is applicable to diverse social phenomena that stretches across politics, economics, and sociology. If social science research can appropriately and effectively develop and apply chaos theory, the theory can be utilized as a useful paradigm to reinforce the fundamentals of epistemology and methodology in exploring social phenomena.

• The KIPS Transactions:PartA
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• v.16A no.5
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• pp.307-318
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• 2009

Modeling and rendering of atmospheric phenomena such as clouds is one of most difficult research themes in the field of computer graphics, mainly due to its complexity, huge volume, ubiquitousness, etc. In this paper, we represent a system for real-time modeling and rendering of clouds, mainly aiming at the computer games and flight simulation applications. Our implementation generates various kinds of clouds including cirrus, stratus, and cumulus, through intuitive real-timeuser interactions. Then, additional details are automatically attached to them, using our own methods based on meta-balls or hierarchical spherical particles. After processing multiple scattering and anisotropic scattering, resulting particles are rendered into billboards, to finally achieve real-time processing.