• Journal of KSNVE
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• v.3 no.2
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• pp.163-167
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• 1993

Suction and discharge valves of special type refrigerant compressor are designed by finite element method for effective valve design development procedure. It is well known that valve dynamic characteristics, for example, the natural frequencies and vibration modes, are necessary for the computer simulation of compressor valve dynamics, the analysis of flow patterns, noise, impact stresses and their propagation phenomena. This paper has analysed the natural frequencies and vibration modes for the first three orders under the given special boundary conditions and the experiments are conducted by laser holography. And also stress distribution is analysed and experiment by strain gage is followed.

• Proceedings of the Korean Nuclear Society Conference
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• 1995.10a
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• pp.383-388
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• 1995

Two-phase transient phenomena in the noncondensable gas-filled closed loop was investigated numerically using the RELAP5/MOD3 version 3.1 computer code. The condensation heat transfer correlation for noncondensable gases was studied in detail. Two modes of the reflux condensation which can be characterized by countercurrent flow of steam and its condensed water and the oscillatory between reflux condensation and natural circulation were predicted well. However, the natural circulation mode which the condensed water carried over the U-bend concurrently with steam was failed to predict.

• Korean Institute of Interior Design Journal
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• no.14
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• pp.63-73
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• 1998

The aim of this study is to understand and redefine the nature of architectural environment within the paradigm of natural science. The chaos theory non-equilibrium thermodynamics theory self-organization of modern physics offer new insights to explain not only natural phenomena but also to define creative and dynamic architectural environment. First natural laws in modern physics like the arrow of time but is related not only with certainty but also possibility so nature is understood as a constantly changing process of evolution. Second the new architectural environment is defined as a kind of fluid and irreducible organic biosytem that cannot be fully understood by modernist idea of architecture. It is conceived of as a fluid constantly changing self-oraganizing system that consists of different situations events movements and programs in uncertain and irreducible time frame. Third insights and implications of natural science offer new language and strategy for design and the two disciplines can be understood as interdependent and co-evolving

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.1 no.1
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• pp.64-72
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• 1989

Laminar natural convection heat transfer from a horizontal heat exchanger tube with one infinitely long vertical plate fin has been studied by a finite-difference numerical procedure. In predicting convective heat transfer from a circular tube, the thermal boundary condition at solid fluid interface is usually assumed to be isothermal. However, in reality, the thermal boundary condition is not isothermal, and the tube has the thickness and the conductivity. So the temperature at the interface is not known a priori to the calculation. This problem has the conjugate phenomena which occur between the tube conduction and external natural convection, and between the fin conduction and external natural convection. Numerical results are obtained to determine the effects of the conductivity of solid wall and the thickness of tube wall on heat transfer. It is found that the conduction causes significant influence on the natural convection heat transfer at low K and high ${\delta}$.

• Nuclear Engineering and Technology
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• v.54 no.3
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• pp.826-833
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• 2022

A two-phase natural circulation test using SMART integral test loop (SMART-ITL) was conducted to explore thermo-hydraulic phenomena of two-phase natural circulation in the SMART reactor. Specifically, the test examined the natural circulation in the primary loop under a stepwise coolant inventory loss while keeping the core power constant at 5% of the scaled full power. Based on the test results, three flow regimes were observed: single-phase natural circulation (SPNC), two-phase natural circulation (TPNC), and boiler-condenser natural circulation (BCNC). The flow rate remained steady in the SPNC, slightly increased in the TPNC, and dropped abruptly and maintained in the BCNC. Using a natural circulation flow map, the natural circulation characteristic in the SMART-ITL was compared with those in pressurized water reactor simulators. In the SMART-ITL, a BCNC regime appeared instead of siphon condensation and reflux condensation regimes because of the use of once-through steam generators.

• KSTLE International Journal
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• v.10 no.1_2
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• pp.43-47
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• 2009

Influences of carbonaceous ingredient as a solid lubricant in automotive friction materials on friction properties were studied. Three types of carbonaceous ingredients such as natural graphite, artificial graphite, and cokes were mixed using a constrained mixture design. A 1/5 scale brake dynamometer was used to obtain tribological properties. Results showed that cokes substantially increased the friction coefficient, and natural graphite effectively reduced stick-slip phenomena. This significant difference was attributed to the formation of the friction film on the brake pad which was shown to be strongly dependent on the graphite types. The different crystal structures of the carbonaceous solid lubricants played a significant role in the formation of friction film at the interface.

• Journal of Mechanical Science and Technology
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• v.16 no.4
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• pp.448-453
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• 2002

This paper presents a modeling method for the vibration analysis of translationally accelerated cantilever plates. An accurate dynamic modeling method, which was introduced in the previous study, is employed to obtain the equations of motion for the vibration analysis. Dimensionless parameters are identified to generalize the conclusions from numerical results. The effects of the dimensionless parameters on the natural frequencies and mode shapes are investigated. Particularly, the magnitude of critical acceleration which causes the dynamic buckling of the structure is calculated. Incidentally, the natural frequency loci veering phenomena are observed and discussed.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2003.11a
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• pp.98-103
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• 2003

This paper presents phenomena of vibration and noise due to acoustic resonance in tube bank of a HRSG. Acoustic resonance is may arise when the vortex shedding frequency coincides with the acoustic natural frequency. At this tube bank, dominant frequencies of vibration in this system were 43.5, 67.5㎐. The 3$\^$rd/ acoustic natural frequency calculated was 68.5㎐. When the difference of vortex shedding frequency and acoustic natural frequency is within ${\pm}$20%, acoustic resonance could occur. In this system, in order to prevent acoustic resonance, acoustic baffle was installed in the tube bank before operating. But acoustic resonance occurred. So, we evaluate the effect of acoustic mode due to baffle extension length. After investigating, we did revise acoustic baffle to eliminate acoustic resonance effectively.

• Proceedings of the Korea Contents Association Conference
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• 2005.11a
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• pp.572-575
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• 2005

In digital contents industry there is a high demand to convincingly mimic the appearance and behavior of natural phenomena such as smoke, waterfall, rain, and fire. Particle systems are methods adequate for modeling fuzzy objects of natural phenomena. It is clear which parameter of which action in a particular effect should be modified for a particular visual result. The generator is usable for offline animation and for real-time special effects in digital contents and virtual reality. The application programmer is able to specify different accuracy needs for different effects. This paper design special effect generator for make low-price and high-quality digital contents in reflection industry and virtual reality applications.

• Journal for History of Mathematics
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• v.27 no.3
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• pp.183-195
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• 2014

In mathematics a prime number is the natural number that has no positive factors other than 1 and itself. As natural numbers greater than 1 can be factored characterized by prime numbers, identities of a culture could be understood if its cultural phenomena are analyzed through cultural prime numbers(CPN). It is not easy to resolve cultural phenomena into CPN and analyze them through CPN due to complexities of culture. Though it is difficult, however, it is not impossible. For CPN keeps relative independence in the context of history and thought. We call 2, 3 and 5 as CPN: 2 is representative of Yin and Yang theory, 3 of Three Principles theory, and 5 of Five Elements theory. We argue that the Ten Celestial Stems and the Twelve Earthly Branches, the core principles in the oriental tradition, could be factored by the CPN. Analyzing Sil-Hah Woo's arguments, we discuss that the CNP 3 achieved more qualitative valuation than the others in Korean culture.