• Proceedings of the Korean Society of Propulsion Engineers Conference
• /
• 2004.03a
• /
• pp.774-778
• /
• 2004

The atomization process of a circular $SF_{6}$ liquid jet issued into an otherwise quiescent, high-pressure $N_2$ gas was observed to explore the breakup mechanism of liquid ligaments involved in turbulent atomization. Both liquid and gas temperatures were fixed at a room temperature but the gas pressure was elevated to more than twice the critical pressure of $SF_{6}$. Therefore, the liquid surface was in a thermodynamic state close to a critical mixing condition with suppressed vaporization. Since the surface tension and the surface gas density approach zero and the surface liquid density, respectively, phenomena equivalent to those which would appear when a very high speed laminar flow of water were injected into the atmospheric-pressure air can be observed by issuing $SF_{6}$ liquid at low speeds in micro-gravity environment which avoid disturbances due to gravity forces. The instability ob near-critical mixing surface jet was quantitatively characterized using a newly developed device, which could issue a very small amount of $SF_{6}$ liquid at small constant velocity into a very high-pressure $N_2$ gas.

• Journal of the Korean Society of Propulsion Engineers
• /
• v.22 no.5
• /
• pp.32-39
• /
• 2018

Supercritical injection behavior of liquid hydrocarbon compounds, which are used as main components of propellant fuel, was analyzed. Decane and Methylcyclohexane (MCH) with different critical points were selected as experimental fluid and Shadowgraphy technique was used. Decane and MCH behave differently in the initial state under the subcritical condition. However, near the critical point, the enthalpy of evaporation became close to 0, so that phase change into supercritical fluid occurred, not vaporization process, and no breakup of both fluids occurred.

• Korean Journal of Culture and Social Issue
• /
• v.28 no.4
• /
• pp.627-659
• /
• 2022

This study aimed to translate and validate the Positive and Negative Ex-Relationship Thoughts (PANERT), a scale measuring the positive and negative valence of thoughts about past relationships in early adulthood. For this purpose, PANERT was translated into Korean and the study surveyed on 337 single male and female adults in their 20. Then, the gender difference between major variables was analyzed. After going through item analysis, all twelve original items were used to construct the Korean version of PANERT. The confirmatory factor analysis(CFA) supported the two factors structure of the Korean version of PANERT: positive vs, negative thought content valence. Also, the reliability coefficients of each two factors were all satisfactory. As a result of a correlation analysis, the criterion-related validity of the two sub-factors was good with other related scales(Intrusive rumination scale of K-ERRI, K-DASS-21-D, and K-PANAS-Revised) except for changes of self-perception. Finally, the research model was built to examine the mediating effect of two affect responses(positive and negative) in the relationship between two thought content valences and depression. In this process, the convergence and discriminant validity of the Korean version of PANERT were confirmed and the indirect effect was also confirmed in the structural equation model. In conclusion, the Korean version of PANERT consists of two factors and twelve items in total. Also, it is a reliable and valid tool for measuring the thought content valences in the romantic relationship breakup experience of early adults.

• Nuclear Engineering and Technology
• /
• v.49 no.7
• /
• pp.1442-1450
• /
• 2017

In liquid metal fast breeder reactors, postulated failures of the plant protection system may lead to serious unprotected accidental consequences. Unprotected transients are generically categorized as transient overpower accidents and transient under cooling accidents. In both cases, core meltdown may occur and this can lead to a molten fuel coolant interaction (MFCI). The understanding of MFCI phenomena is essential for study of debris coolability and characteristics during post-accident heat removal. Sodium is used as coolant in liquid metal fast breeder reactors. Viewing inside sodium at elevated temperature is impossible because of its opaqueness. In the present study, a methodology to depict MFCI phenomena using a flat panel detector based imaging system (i.e., real time radiography) is brought out using a woods metal-water experimental facility which simulates the $UO_2-Na$ interaction. The developed imaging system can capture attributes of the MFCI process like jet breakup length, jet front velocity, fragmented particle size, and a profile of the debris bed using digital image processing methods like image filtering, segmentation, and edge detection. This paper describes the MFCI process and developed imaging methodology to capture MFCI attributes which are directly related to the safe aspects of a sodium fast reactor.

• Proceedings of the Korean Institute Of Construction Engineering and Management
• /
• autumn
• /
• pp.517-520
• /
• 2003

Recently there is a used a word-outsourcing-in the corporation circumstance. Continuous recession impelling with IMF permitted restructuring measures downsizing unnecessary organization and offered opportunity to breakup structure of 'High cost and Low efficiency' -inefficient and uneconomic production method- in our corporation. Due to the effect of such circumstance change, the construction industry have already introduced and implemented outsourcing in many parts. For successful outsourcing in the construction industry, a mutually close relations and the cooperation are preceded and JIT system is needed to improve these relations. The study recognizes the importance and proportion that outsourcing is occupyed in the construction industry, and suggests the method to improve the productivity by evaluating the factors and usefulness for JIT system to apply to the construction industry.

• Korean Journal of Construction Engineering and Management
• /
• v.5 no.5 s.21
• /
• pp.117-125
• /
• 2004

Recently, the word 'outsourcing' is used frequently in the corporation circumstance. Continuous recession with IMF caused restructuring measures which made unnecessary organization be downsized, and offered opportunity to breakup structure of $^{\circ}A$EHigh cost and Low efficiency, which is inefficient and uneconomic production method' in our corporation. Due to the effect of such circumstance change, the construction industry have already introduced and implemented outsourcing in many parts. For successful outsourcing in the construction industry, close relation and mutual cooperation should be preceded and JIT system is needed to improve the relation. In this study, the importance and proportion in which outsourcing is occupied in the construction industry are recognized, and the method for improving the productivity is suggested through evaluating the factors and usefulness of JIT system which can be applied to the construction industry.

• Proceedings of the Korean Society of Propulsion Engineers Conference
• /
• 2003.10a
• /
• pp.168-172
• /
• 2003

The effects of injection conditions on the droplet sizes resulting from the disintegration of a liquid jet by a fast annular gas stream have been investigated using PDPA. The gas/liquid momentum ratio M = $\rho$$_{g}$ $U_{g}$$^2$/$\rho$$_1$ $U_1$$^2$ and Weber number We = $\rho$$_{g}$ $g^2$ $D_1$/$\sigma$ are selected as key parameters in atomization of shear coaxial spray from the fluid mechanics standpoint. It is revealed that SMD( $D_{32}$) varies inversely with gas/liquid momentum ratio(M), whereas Weber number(We) has little effect on the droplet sizes as gas velocities increase. It is found that gas/liquid momentum ratio is more dominant factor controlling the breakup and atomization process of shear coaxial spray. Finally, an empirical correlation between SMD and injection conditions(i.e. gas/liquid momentum ratio M and Weber number We) is proposed based on the experimental results.

• Journal of the Korea Computer Graphics Society
• /
• v.24 no.2
• /
• pp.11-20
• /
• 2018

We propose a new method particle-based method that explicitly preserves thin liquid sheets for animating liquids on CPU-GPU heterogeneous computing framework. Our primary contribution is a particle-based framework that splits at thin points and collapses at dense points to prevent the breakup of liquid on GPU. In contrast to existing surface tracking methods, the our method does not suffer from numerical diffusion or tangles, and robustly handles topology changes on CPU-GPU framework. The thin features are detected by examining stretches of distributions of neighboring particles by performing PCA(Principle component analysis), which is used to reconstruct thin surfaces with anisotropic kernels. The efficiency of the candidate position extraction process to calculate the position of the fluid particle was rapidly improved based on the CPU-GPU heterogeneous computing techniques. Proposed algorithm is intuitively implemented, easy to parallelize and capable of producing quickly detailed thin liquid animations.

• The Journal of the Korea Contents Association
• /
• v.5 no.5
• /
• pp.43-50
• /
• 2005

POS system that become that is supply net administration and computerization fetters of customer management that become point in istribution network constructed database and use XML-Encryption that is certificate techniques of PKI and standard of security for security that is XML's shortcoming and design distributed processing POS system using XML for data integration by introduction of Ubiquitous concept. This POS system has four advantages. First, Because there is no server, need not to attempt authentication and data transmission every time. Second, can integrate data base by XML and improve portability of program itself. Third, XML data in data transmission because transmit data after encryption data safe .Fourth, After encode whenever process data for data breakup anger of POS system client program and elevation of the processing speed, transmit at because gathering data at data transmission.

• Journal of the Korean Ceramic Society
• /
• v.49 no.6
• /
• pp.528-534
• /
• 2012

In this study, the densification behavior and microstructural evolution of CuO were examined when this material was sintered at different temperatures in $O_2$, air and Ar atmospheres. The CuO samples maintained their phases even after prolonged sintering at $900-1100^{\circ}C$ in an oxygen atmosphere. When sintering in air, the densification was faster than it was when sintering in oxygen. However, when the samples were sintered at $1100^{\circ}C$, large pores were observed in the sample due to the phase transformation from CuO to $Cu_2O$ which accompanies the generation of oxygen gas. The pore channels in the sample became narrower as the sintering time increased, eventually undergoing a Rayleigh breakup and forming discrete isolated pores. On the other hand, CuO sintering in Ar did not contribute to the densification, as all CuO samples underwent a phase transformation to $Cu_2O$ during the heating process.