• Proceedings of the Korean Fiber Society Conference
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• 1990.06b
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• pp.38-38
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• 1990

• Fibers and Polymers
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• v.2 no.2
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• pp.98-107
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• 2001

The phase transition behavior isothermal micro-phase separation kinetics of polyester-based thermoplastic elastomer were studied using the synchrotron X-ray scattering(SAXS) method. The structural changes occurring during heating period were investigated by determining the changes of the one-dimensional correlation function, interfacial thickness and Porod constant. Based on the abrupt increases of the domain spacing and interfacial thickness, a major structural change occurring well below the melting transition temperature is suggested. Those changes are explained in terms of melting of the thermodynamically unstable hard domains or/and the interdiffusion of the hard and soft segments in the interfacial regions. SAXS profile changes during the micro-phase separation process were also clearly observed at various temperatures and the separation rate was found to be sensitively affected by the temperature. The peak position of maximum scattering intensity stayed constant during the entire course of the phase separation process. The scattering data during the isothermal phase separation process was interpreted with the Cahn-Hilliard diffusion equation. The experimental data obtained during the early stage of the phase separation seems to satisfy the Cahn-Hilliard spinodal mechanism. The transition temperature obtained from the extrapolation of the diffusion coefficient to zero value turned out to be about 147$\pm$$2^{\circ}$, which is close to the order-disorder transition temperature obtained from the Porod analysis. The transition temperature was also estimated from the inveriant growth rate. By extrapolating the inveriant growth rate to zero, a transition temperature of about 145$\pm$$\pm$$2^{\circ}$ was obtained.

• Journal of the Korean Society for Aviation and Aeronautics
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• v.14 no.4
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• pp.24-30
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• 2006

An experimental study was carried out in order to investigate the influence of boundary layer behavior on the near-wake at low Reynolds numbers. An X-type hot-film probe(55R51) was used to measure the near-wake of an NACA 0012 airfoil at static angles of attack ${\alpha}=0^{\circ}$, $3^{\circ}$, and $6^{\circ}$, and the Reynolds numbers Re=2.3${\times}10^4$, 3.3${\times}10^4$, and 4.8${\times}10^4$. The results of the study show that the characteristics of the boundary layer on the airfoil surface have a close relationship with the mean velocity and turbulence intensity profiles of a near-wake. Therefore, the development of the boundary layer, the position of the separation point, and the existence and non-existence of reattachment on the airfoil surface were represented by the differences in mean velocity and turbulence intensity profiles of the near-wake.

• Korean Journal of Health Education and Promotion
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• v.14 no.2
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• pp.17-42
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• 1997

From September 2, 1995 through October 31, this questionnaire was made by the 1, 200 industrial workers who work for 15 enterprises of 5 types of business. And it was for helping to devise a policy and to develop a program for industrial workers' health promotion by understanding the consciousness behavior level of industrial workers in our country and the related factors which are under the influence of it and health promotion behavior. The summary and conclusions are as follows. 1. In health promotion score level by related factors, the health diagmosis level score was 7. 37(81.9/100) of the perfect score 9, nutrition level score was 7.00(77.8/100), health education behavior level score was 6.00(66.7/100), exercise behavior level score was 6.01(66.8/100), occupational disease knowledge level score was 6.00(66.7/100). 2. Health diagnosis behavior level was significantly high when the age is older, when the occupation term is longer, when the economic status is better. And wjem tje satosfoed degree for vocational aptitude, working environment, and the education contents. 3. Nutrition (dietary habit) status level was high in men, in the age group of 40 over, in the group of having their spouse, in the group of being paid over one million won a month, in the upper economic classes (P〈0.001). It was also high in graduates middle school and in daytime workers (P〈0.05). 4. Health education behavior level was high in the older ahe hroup, in a single life (separation by death, divouce, separation) and in the longer occupation term(P〈0.001). 5. Exercises behavior level was high in men, in the workers who are paid 500～990 thousand won a month, in the better economic classes(P〈0.01). 6. Knowledge level on an occupational disease was high in men, in the older age group, in the group of having a spouse, In the workers who are paid 500～990 thousand won a month, in the group of having a longer occupation term, and in the residents living not in a large city(P〈0.01). 7. When health status was higher, health promotion behavior, behavior level, health diagnosis (P〈0.001), nutrition(P〈0.05), health education behavior (P〈0.05), exercise behavior(P〈0.01) and the knowledge level on an occupation disease was high. 8. The main factors which are under the influence on the degree of practicing healthy life were the level of knowledge and behavior, sex, his/her health status, and the satisfied degree of working environment. These variables could explain it 18.0%. 9. The factors which are under the influence on health promotion behavior and behavior levels were the variables of the satisfied degerr of education contents, sex, health knowledge, economic status, health status, occupation terms, monthly income, working tiredness. These variables could explain it 21.3%. By these results, it is inportant for industrial workers' health promotion to level up the health diagnosis behavior, dietary habit considering nutrition, behavior on health education, behavior for exercise, and knowledge on an occupational disease. Especially we should develop the proper program considered sex, health status, satisfied degree of working environment and education contents, economic status, eccupation terms, knowledge on health, and behavior level. Because health promotion business gies in gear with productivity promotion.

• Membrane Journal
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• v.30 no.6
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• pp.385-394
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• 2020

In the gas separation process, the separation membranes have to not only show high gas transport and selectivity but also exhibit exceptional stability at high temperature and pressure. However, when the polymeric membranes (particularly, glassy polymers) are exposed to the condensable gases (i.e., CO2, H2S, hydrocarbon, etc.), the polymer chains are prone to swell, leading to low stability. As a result, the plasticization behavior reduces the gas selectivity in the separation of mixture gases at high pressures and thus results in limited applications to the separation processes. To address these issues, many strategies have been studied such as thermal treatment, polymer blending, thermally rearrangement, mixed-matrix membranes, cross-linking, etc. In this review, we will understand the plasticization behavior and suggest potential methods based on the previously reported studies.

• Journal of the Korean Geotechnical Society
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• v.24 no.7
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• pp.5-16
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• 2008

Most of roadway tunnels have been constructed in the form of parallel twin tunnel in Korea. If parallel twin tunnel does not have a sufficient separation distance between tunnels, the problem of tunnel stability can occur. Generally, it is reported that tunnels are not influenced by each other when a center distance between tunnels is two times longer than tunnel diameter under the complete elastic ground and five times under the soft ground. In this study, the scaled model tests of closely-spaced parallel twin tunnel using homogeneous material are performed and induced displacements are measured around the tunnel openings during excavation. The influence of separation distance between tunnels on the behavior of closely-spaced tunnel is investigated. The experimental results are expressed by the induced displacement vector and progress of crack during construction and at failure. The results show that based on the analysis of induced displacement at the crown during construction, the additional displacement of the preceding tunnel induced by the excavation of following tunnel decreases as the separation distance between twin tunnel increases until the center to center distance is two times of tunnel diameter. Beyond this point, however, the additional displacement has become stabilized.

• Journal of computational fluids engineering
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• v.13 no.4
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• pp.80-85
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• 2008

The prediction of the separation trajectories of external stores released from a military aircraft is an important task in the aircraft design area having the objective to define the operational and release envelopes. This paper presents the results obtained for store separation by employing commercial softwares, FLUENT and CFD-FASTRAN. FLUENT treats the rigid body motion by employing a remeshing scheme. CFD-FASTRAN uses Chimera(overset) grid and interpolations. It was found that, for the prediction of the trajectories and behavior of the stores separated from the wing, both codes show the good agreement with the experimental results.

• Journal of Korean Society of Water and Wastewater
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• v.18 no.5
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• pp.649-655
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• 2004

The behavior of biological particles in DAF (dissolved air flotation) process was analyzed by employing PBT (Population balance theory). After decline growth phase of activated sludge, the value of the initial collision-attachment efficiency was increased over than 0.35 corresponding relatively high value in the whole life cycle of microorganism. For practical application of DAF as a solid separation process. It is desirable that microbial particles should be operated to perform high solid removal efficiency in biological wastewater treatment.

• Environmental Engineering Research
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• v.14 no.4
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• pp.262-269
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• 2009

This study examined the separation characteristics of particles in the rainfall runoff from paved roads using a ${\varphi}7.5$ cm hydrocyclone. The volume fraction and total suspended solids concentrations in the overflow and underflow from the hydrocyclone, as well as the separation efficiency were determined. The results indicated that the overflow volume increased with increasing operational pressure, but decreased with decreasing ratio of underflow outlet to inlet sizes ($D_u/D_i$), while the underflow to overflow volumes showed contrary behavior. The total suspended solid (TSS) concentration ratio between the overflow and inflow ($TSS_{over/in}$) decreased as a function of the operational pressure, while the corresponding ratio of underflow to inflow ($TSS_{under/in}$) increased. There was no visible difference in the $TSS_{over/in}$ with increasing $D_u/D_i$ ratio, but the $TSS_{under/in}$ decreased sharply. The particle removal efficiency was mainly affected by the particle size.

• Journal of the Korean Magnetic Resonance Society
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• v.24 no.2
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• pp.47-52
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• 2020

Liquid-liquid phase separation (LLPS) of biomolecules, a newly-found phase behavior of molecules in the liquid phase, has shown to its relationship to various biological function and misfolding diseases. Extensive studies have increasingly revealed a general mechanism of LLPS and characterized the liquid droplet; ho wever, intermolecular interactions of proteins and structural states of LLPS-inducing proteins inside of the droplet remain largely unknown. Solution NMR spectroscopy has emerged as a powerful approach as it provides invaluable information on protein intermolecular interactions and structures at the atomic and residue level. We herein comprehensively address useful techniques of solution NMR including the effect of paramagnetic relaxation enhancement for the study on the LLPS and droplet based on recent studies.