• Proceedings of the Earthquake Engineering Society of Korea Conference
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• 2003.09a
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• pp.133-140
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• 2003

The objective of this study is to clarify the seismic capacity and the characteristics in the hysteretic behavior of RC structures with non-seismic detailing. Interior and exterior beam-column subassemblages were selected from a ten-story RC building and six 1/3-scale specimens were constructed with three variables; (1) with and without slab, (2) with and without hoop bars in the Joint region, (3) upward and downward direction of anchorage for the bottom bar in beams of exterior beam-column subassemblage. The test results have shown; (1) in case of interior beam-column subassemblage, there is no almost difference between nonseismic and seismic details in the strength and ductility capacity; (2) the Korean practice of anchorage (downward and 25 $d_{b}$ anchorage length) in the exterior Joint caused the 10％~20％ reduction of strength and 27％ reduction of ductility iii comparison with tile case of seismic details; and the existence of hoop bars in the joint region shows no effect in shear strain.n.

• Nuclear Engineering and Technology
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• v.51 no.3
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• pp.761-768
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• 2019

Understanding the phenomena of formation of single drops is necessary to understand the hydrodynamics in solvent extraction equipment which are used for separation of nuclear materials. In this work, the phenomena of aqueous phase and organic phase drop formation at submerged nozzles are compared by conducting experiments with 30%TBP (v/v) in dodecane as the organic phase and nitric acid as the aqueous phase. Two different nozzles and three different nitric acid concentrations are used. For each nozzle and nitric acid concentration, velocity of the dispersed phase is varied. Drops of aqueous phase formed at downward oriented nozzles submerged in organic phase are observed to be smaller than the drops of organic phase formed at upward oriented nozzles submerged in aqueous phase. Correlations to estimate drop diameter are proposed.

• Journal of Urban Science
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• v.9 no.2
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• pp.13-20
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• 2020

The Recently, several countries have been affected by respiratory diseases, resulting in renewed research interest in their prevention and control. One such example was the 2015 outbreak of Middle East Respiratory Syndrome (MERS) in South Korea and COVID-19. In this study, we performed experiments and simulations based on concentration decay using CO2 as the tracer gas to elucidate the pollutant-removal efficiency for different inlet and exhaust locations and outdoor air-supply ratios. The wall inlet exhibited a higher pollutant-removal efficiency, owing to the upward movement of the air from the lower zone to the upper one. In conclusion, it is recommended that a total air-conditioning plan for isolation rooms be established as well as efficient system operation for pollutant removal and air-flow control to prevent the transmission of infections from the patients to others.

• Journal of Oral Medicine and Pain
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• v.21 no.2
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• pp.393-405
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• 1996

This study was performed to investigate the effects of changes of head posture and cervical spine shape on the mandibular resting or clenching electromyographic(EMG) activity in anterior temporalis(TA), masseter(MM), sternocleidomastoid muscle(SCM) and trapezius insertion(TI). 30 patients with Temporomandibular Disorders(TMDs) participated in this study. EMG activity($\mu$V) at rest and clenching was observed in four head postures, namely natural head posture(NHP), forward head posture(FHP), upward head posture(UHP), and downward head posture(DHP). For taking in upward or downward head posture head was inclined 10$^{\circ}$ upward or downward and CROM$^\textregistered$(cervical-range-of motion, Performance attainment Inc., USA) was used to maintain same posture during the procedure, and BioEMG$^\textregistered$ (Bioelectromyograph, Bioresearch Inc., USA) was used to record EMG activity in the above four muscles at eight locations on both sides. The recorded EMG activity($\mu\textrm{V}$) were compared and analyzed by cervical spine shape such as the head position from plum line, cervical curvature, and cervical inclination. Head position from plum line was measured in vertical plate calibrated with cm scale, comical curvature by radius was measured with adjustable curved ruler, and cervical inclination by cervical vertebrae tangent(CVT)was measured in lateral cephalograph. The results obtained were as follows : 1. Mean value of head position from plum line, cervical curvature, and cervical inclination were 4.8cm, 26.7cm, and 86.6$^{\circ}$, respectively, And There were no correlationship among these items. 2. For resting EMG activity by head posture, the value in anterior temporalis was higher at FHP than at DHP, the value in masseter was higher at FHP than at NHP, and DHP, the value in sternocleidomastoid muscle was higher at UHP than at NHP, and the value in trapezius insertion was higher at FHP and DHP than, NHP and UHP. The clenching EMG activity, however, did not show any difference by head posture. 3. Comparison of resting and clenching EMG activity between higher and lower groups by head position from plum line, cervical curvature, and cervical inclination did not show any significant difference. From this result, the author concluded that the cervical spine shape had not significantly affected to EMG activity in usual patients with TMDs.

• Science of Emotion and Sensibility
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• v.11 no.3
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• pp.365-374
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• 2008

Using flight simulator tasks with 48 air force cadets, this research examined the effects of pilots' flight skill and self-esteem on risk-taking behavior in the context of social comparison with their cohorts. Flight skill and self-esteem were assessed for individual cadets and three conditions of social comparison (upward-, downward-, and no-comparison) were devised. Flight simulator situations inappropriate for further approach or landing were designed to assess pilots' risk-taking behavior. Weather conditions in the simulator were inadequate to make a landing and the recommended strategy was to break off the approach and attempt a go-around. In this experiment, pilots' risk taking was measured in terms of their approach altitudes; the lower approach altitudes indicative of the higher risk-taking. Our results showed interaction effects of flight skill, self-esteem, and social comparison on risk-taking behaviors. For pilots who were either high or low in both self-esteem and flight skill, social comparison had no effect on risk-taking behavior. However, pilots with high self-esteem but low flight skill showed more risk-taking behaviors in social comparison conditions. And, pilots with low self-esteem but high flight skill showed risk-aversive behaviors in the downward-comparison condition.

• Proceedings of the KSME Conference
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• 2007.05b
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• pp.3395-3400
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• 2007

Heat transfer experiments at a vertical annulus passage were carried out in the SPHINX(Supercritical Pressure Heat Transfer Investigation for NeXt Generation) to investigate the heat transfer behaviors of supercritical $CO_2$. The collected test data are to be used for the reactor core design of the SCWR (SuperCritical Water-cooled Reactor). The mass flux was in the range of 400${\sim}$1200 kg/$m^2$s and the heat flux was chosen up to 150 kW/$m^2$. The selected pressures were 7.75 and 8.12 MPa. The heat transfer data were analyzed and compared with the previous tube test data. The test results showed that the heat transfer characteristics were similar to those of the tube in case of a normal heat transfer mode and degree of heat transfer deterioration became smaller than that in the tube. Comparison of the experimental heat transfer coefficients with the predicted ones by the existing correlations showed that there was not a distinct difference between the correlations.

• Bulletin of the Korean Space Science Society
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• 2011.04a
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• pp.27.3-27.3
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• 2011

The plasmasphere is filled with the ions and electron transported mostly from the mid-latitude ionosphere. In the topside ionosphere where the $O^+$ ions are still major ions, the $O^+$ ions are in chemical equilibrium with the $H^+$ ions and exchange their charges with each other's parent atoms with similar rates in both reactions. During the day, the newly produced $H^+$ ions flow upward to fill the plasmasphere while they flow downward and contribute to the maintenance of the ionospheric density at night under the geomagnetically quiet condition. The ionosphere and plasmasphere are coupled by these plasma fluxes and therefore strongly affect each other. In order to study these coupling we utilized the plasma density measurements from JASON satellite. This satellite measures vertical total electron content (TEC) from the ground to the satellite orbit (about 1336 km) and slant TEC from the satellite orbit to much higher GPS satellites by using the on-board dual-frequency altimeter and GPS receiver, respectively. The former measurement can represent the ionospheric TEC while the latter can represent the plasmaspheric TEC in the equatorial region. We compared these data with different seasons, solar activities and local times, and the results will be presented.

• The Journal of Korean Physical Therapy
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• v.24 no.6
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• pp.388-392
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• 2012

Purpose: Muscle imbalance between upper trapezius (UT) and serratus anterior (SA) during arm elevation is a factor causing shoulder dysfunction. However, there is no study to compare the muscle activities of the UT and middle deltoid (MD). The purpose of this study was to compare the muscle activities of the UT and MD between with and without elevation of shoulder girdle (ESG) during shoulder abduction. Methods: The subjects without (control group=9) or with (ESG group=8) participated in this study. The muscle activities of the UT and MD were measured using a electromyography during $90^{\circ}$ shoulder abducted position in both group. The data in middle of 3-second of the 5-second periods were used. The mean value of three trials was used in the data analysis. For each muscle, independent t-tests were performed to compare for group differences. Results: The muscle activity of UT was significantly greater in ESG group, compared to that of the control group (p<0.05). The muscle activity of MD was significantly smaller in ESG group, compared to that of the control group (p<0.05). Conclusion: These findings showed that low muscle activation of MD as well as SA may contribute to hyperactivity of UT during arm elevation.

• Journal of Advanced Marine Engineering and Technology
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• v.24 no.3
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• pp.79-87
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• 2000

This paper describes experimental investigations of helium-air exchange flow through openings with vertical partitions. Such exchange flows may occur following rupture accident of stand pipe in high temperature gas cooled reactor. Exchange flow rates are investigated experimentally by using partitioned opening and opening with extended partition to assess fluids interference of the exchange flow at the stand pipe rupture accident. A tests vessel with the two types of opening on top of test cylinder is used in the experiments. An estimation method of mass increment is developed and applied to measure the exchange flow rate. A technique of flow visualization by Mach-Zehnder interferometer is provided to recognize the exchange flows. Amplitude and progress of interference fringes of the flows are observed and used as a support in comparison with the exchange flow rates. Flow passages of upward flow of the helium and downward flow of the air for both two types of the opening are separated by inserted partition within the opening, but in the case of partitioned opening, unseparated flow is formed at the opening entrance and the two flows interface. The exchange flow rate for the partitioned opening is not greater than that of the opening with extended partition because of the fluids interference at the entrance of opening. Finally, the fluids interference at the opening entrance is found to be one of important factors on the helium-air exchange flow rate.

• Ocean Systems Engineering
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• v.8 no.2
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• pp.167-182
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• 2018

RTI (Rayleigh-Taylor instability) is investigated by a multi-liquid MPS (Moving Particle Semi-implicit) method for both viscous and inviscid flows for various density differences, initial-disturbance amplitudes, viscosities, and surface tensions. The MPS simulation can be continued up to the late stage of high nonlinearity with complicated patterns and its initial developments agree well with the linear theoretical results. According to the relevant linear theory, the difference between inviscid and viscous fluids is the rising velocity at which upward-mushroom-like RTI flow with vortex formation is generated. However, with the developed MPS program, significant differences in both growing patters and developing speeds are observed. Also, more dispersion can be observed in the inviscid case. With larger Atwood (AT) number, stronger RTI flows are developed earlier, as expected, with higher potential-energy differences. With larger initial disturbances, quite different patterns of RTI-development are observed compared to the small-initial-disturbance case. If AT number is small, the surface tension tends to delay and suppress the RTI development when it is sufficiently large. Interestingly, at high AT number, the RTI-suppressions by increased surface tension become less effective.