• Journal of the Korean Society for Aviation and Aeronautics
• /
• v.29 no.3
• /
• pp.34-43
• /
• 2021

Wake turbulence generated by the lead aircraft has a significant impact on the following aircraft and it is has been considered a key factor to consider whenin determining the longitudinal separation between the aircraft. ICAO classifies aircraft into four wake turbulence categories based on the maximum takeoff weight and provides the longitudinal separation minima for each category. Due to richer measured data and better understanding of physical processes, it is raised that classifying aircraft with only four wake turbulence grades is imprecise and leads to over-separation in many instances. In this regards, much research on a new method of classifying Wake Turbulence Category(Re-CAT) has been done by EURO-CONTROL, FAA, and ICAO. The main purpose of this study is to conduct a comparative analysis of the existing wake turbulence separation standards with Re-CAT in terms of departure capacity and the resulting benefits of Re-CAT using the data from the Incheon International Airport. The results show that EUROCONTROL and new ICAO standards have the greater effect on reducing wake turbulence separation, compared to the FAA RE-CAT standards. It is also concluded that Re-CAT presents different results of wake turbulence separation depending on the flight characteristics of each airport.

• Restorative Dentistry and Endodontics
• /
• v.37 no.4
• /
• pp.201-206
• /
• 2012

Objectives: The purpose was to investigate the preference and usage technique of NiTi rotary instruments and to retrieve data on the frequency of re-use and the estimated incidence of file separation in the clinical practice among general dentists. Materials and Methods: A survey was disseminated via e-mail and on-site to 673 general dentists. The correlation between the operator's experience or preferred technique and frequency of re-use or incidence of file fracture was assessed. Results: A total of 348 dentists (51.7%) responded. The most frequently used NiTi instruments was ProFile (39.8%) followed by ProTaper. The most preferred preparation technique was crown-down (44.6%). 54.3% of the respondents re-used NiTi files more than 10 times. There was a significant correlation between experience with NiTi files and the number of re-uses (p = 0.0025). 54.6% of the respondents estimated experiencing file separation less than 5 times per year. The frequency of separation was significantly correlated with the instrumentation technique (p = 0.0003). Conclusions: A large number of general dentists in Korea prefer to re-use NiTi rotary files. As their experience with NiTi files increased, the number of re-uses increased, while the frequency of breakage decreased. Operators who adopt the hybrid technique showed less tendency of separation even with the increased number of re-use.

• Journal of Nuclear Fuel Cycle and Waste Technology(JNFCWT)
• /
• v.5 no.2
• /
• pp.123-132
• /
• 2007

This study was performed to evaluate the co- and mutual separation for Am, Cm and RE elements from the simulated multi-component solution equivalent to real HLW level by a Zr-DEHPA(di-(2-ethylhexyl) phosphoric acid containing Zirconium)/$NDD(n-dodecane)-HNO_3$ extraction system. Zr-DEHPA was self-synthesized and the optimal condition of (15g/L Zr-1M DEHPA)/NDD-1M $HNO_3$ was selected taking into consideration of prevention of the third phase, and effects of concentration of DEHPA, nitric acid and impregnant amount of Zr on the co-extraction of Am, Cm and RE. In that condition, the extraction yields were 81% (Am), 85% (Cm), more than 80% (RE elements), 98% (Mo), 85% (Fe), 98% (U), 73% (Np), and less than 5% (other elements) so that the system developed for the co-extraction of Am-Cm/RE was proved to be available. For that, however, U, Np, Mo and Fe was elucidated to have to be removed in advance, and Zr inducing the third phase formation was found to be practically excluded. The co-extracted Am-Cm/RE were sequentially separated in an order of Am-Cm (stripping agent : 0.05 M DTPA-1M Lactic acid of pH 3.6)${\rightarrow}RE$ (stripping agent : 5M $HNO_3$), and then their separation factors were evaluated. At above conditions, Am of 65.4%, Cm of 63.9%, RE (except for Y) of more than 85% were stripped.

• Journal of the Korean Society of Visualization
• /
• v.18 no.3
• /
• pp.69-76
• /
• 2020

In the present study, we investigate the flow separation characteristics of a paraglider canopy model by tuft visualization. The experiment is conducted at Re = 3.3×105 in a wind tunnel large enough to contain the three-dimensional paraglider canopy model, where Re is Reynolds number based on the mean chord length and the free-stream velocity. The flow separation characteristics of the canopy model near the wing root are similar to those of a two-dimensional airfoil with a cross-section similar to the model. On the other hand, near the wingtip region, the flow separation is suppressed by the downwash induced by the wingtip vortex. As a result, as the angle of attack increases, the flow separation occurs from the wing root region of the canopy model and develops toward the wingtip.

• KSBB Journal
• /
• v.4 no.3
• /
• pp.281-287
• /
• 1989

The experimental study reported herein was to investigate to separation characteristics of a tangential flow membrane in a continuous recycle situation. Physical and dynamic analyses are performed on the membrane system in order to relate relevant variables to the capacity of separation. The results of separation process may be summarized by a proposed equation:Sh=A(Re.Sc.dh/L)1/3. It was shown also by the analyses that effective separation of sugar and cell was attainable by means of tangential membranes, thereby enhancing ethanol productivity in fermentation with continuous cell and substrate recycle.

• 제어로봇시스템학회:학술대회논문집
• /
• 2004.08a
• /
• pp.1350-1354
• /
• 2004

This paper proposes a simple but practically useful model for preventing fraud of users called "ERBAC03". The new model consists of qualified mandatory and discretionary features for roles and locations, including the assignment of permissions for the appropriate roles and the assignment of roles for the appropriate locations. Moreover, a static separation of duty (SSoD) principle is applied to the new model for integrity requirements of security systems. The paper also explores some extensions of ERBAC03 including the new model using the SSoD concept from some experiments. The experimental results prove the efficiency improvement of the proposed model that can make benefits for large enterprises.

• 제어로봇시스템학회:학술대회논문집
• /
• 2004.08a
• /
• pp.1360-1364
• /
• 2004

This paper propose an extended model for role-permission assignment based on locations called "Enhanced Role-Based Access Control (ERBAC03)". The proposed model is built upon the well-known RBAC model. Assigning permissions to role is considered too complex activity to accomplish directly. Instead we advocate breaking down this process into a number of steps. The concept of jobs and tasks is specifically introduced to facilitate role-permission assignment into a series of smaller steps. This model is suitable for any large organization that has many branches. Each branch consists of many users who work in difference roles. An administration tool has been developed to assist administrators with the administration of separation of duty requirements. It demonstrates how the specification of static requirements can be done based on "conflicting entities" paradigm. Static separation of duty requirements must be enforced in the administration environment. Finally, we illustrate how the ERBAC03 prototype is used to administer the separation of duty requirements.

• Proceedings of the Korean Society of Broadcast Engineers Conference
• /
• 2013.06a
• /
• pp.60-63
• /
• 2013

In this research, a mono-to-stereo upmixing algorithm based on music source separation is proposed. For the upmixing, a harmonic and percussive separation for jazz music is implemented. Then, the sources are re-panned by equalizing the loudness of left and right sides of listeners in the one proposed approach. In the other approach, the harmonic sources are spread by a decorrelator while the percussive sources are panned to the center. In the experiments, the re-panning algorithm showed advanced performance in terms of localization and timbral quality.

• Korean Journal of Social Welfare
• /
• v.66 no.4
• /
• pp.133-155
• /
• 2014

The purpose of this study was to understand the experiences of adolescent who are scheduled to discharge from child care institution. Data was gathered from 5 adolescent who are scheduled to discharge from child care institution within 1-2 years and qualitative case study used for data analysis. The analysis showed that adolescents of child care institution experienced separation from their parents and entered the institution with no consideration of their feelings. Then, they stayed in the institution for many years, even throughout their teenager-years, before they are released from the institution. Although feelings they experience of separation from the institution included worry and tension, those feelings were different from feelings they received from separation from their parents in a way that the former was more hopeful and future forwarding. Based on these findings, services sensitive to adolescent who are scheduled to discharge from the institution are suggested.

• Journal of Advanced Marine Engineering and Technology
• /
• v.34 no.1
• /
• pp.76-83
• /
• 2010

The Characteristics of the flow field through cylinders with in-line and staggered arrangements were calculated by vortex method. Vortex distributions and velocity profiles around the cylinders with in-line and staggered arrangements were simulated at the pitch ratio of Pt/D=1.25~2.0 and Reynolds number of Re=$4.0{\times}10^1{\sim}4.0{\times}10^4$. As the results the vortices of clockwise at the upper separation point cylinder and the vortices of anticlockwise at the lower separation point of each cylinder were generated at both in-line and staggered arrangements. The generation of the reverse flow in the rear region of the cylinders was caused by the pitch ratio and Reynolds number, the boundary region was at the pitch ratio of Pt/D=1.5 and Reynolds number of Re=$4.0{\times}10^2{\sim}4.0{\times}10^3$ in case of in-line arrangement and was at the pitch ratio of Pt/D=1.4 and Reynolds number of Re=$4.0{\times}10^1{\sim}4.0{\times}10^2$ in case of staggered arrangement.