• Computers and Concrete
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• v.8 no.5
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• pp.491-510
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• 2011

Before deciding if structures exposed to high temperature are to be repaired or demolished, their final state should be carefully examined. Destructive and non-destructive testing methods are generally applied for this purpose. Compressive strength and color change in mortars are observed as a result of the effects of high temperature. In this study, ordinary and pozzolan-added mortar samples were produced using different aggregates, and exposed to 100, 200, 300, 600, 900 and $1200^{\circ}C$. The samples were divided into two groups and cooled to room temperature in water and air separately. Compression tests were carried out on these samples, and the color change was evaluated by the Munsell Color System. The relationships between the change in compressive strength and color of mortars were determined by using a multi-layered feed-forward Neural Network model trained with the back-propagation algorithm. The results showed that providing accurate estimates of compressive strength by using the color components and ultrasonic pulse velocity design parameters were possible using the approach adopted in this study.

• Journal of the Korean Society for Nondestructive Testing
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• v.31 no.6
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• pp.656-664
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• 2011

In this work, a numerical model is proposed for the relation between the magnitudes and the depth residual stress with the velocity of Rayleigh wave. Three cases, stress-free, uniform stress and layered stress, are investigated for the change tendency of the Rayleigh wave speed. Using the simulated signal with variation of residual stress magnitude and depth, investigation of the parameters for fitting residual stress and velocity change are performed. The speed change of Rayleigh wave shows a linear relation with the magnitude and an exponential relation with the depth of residual stress. The combination of these two effects could be used for the depth profile evaluation of the residual stress.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.8 no.3
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• pp.413-422
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• 1996

Freezing of water in von-$K{\acute{a}}rm{\acute{a}}n$ swirling flow is considered. The transient behavior of the temperature distribution in both solid and liquid phases and freezing rate are determined. The fluid flow induced by the rotation of solid strongly inhibits the freezing process. The thickness of frozen layer is inversely proportional to the square root of the angular velocity of solid. As the angular velocity or initial liquid temperature becomes larger, the freezing process is more strongly inhibited by the fluid flow. When phase change is present, the transient heat transfer rate is greater than the case with no phase change.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.35 no.2
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• pp.9-15
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• 2012

The purpose of this study was to investigate the effects of the secondary tasks such as sending text message (STM) and searching navigation (SN) on skin conductance level (SCL) and driving performance of relatively aged and high-experienced drivers. The subjects included 26 taxi drivers; 12 males aged $56.3{\pm}4.4$ with $28.4{\pm}6.4$ years of driving experiences and 14 females aged $55.5{\pm}3.5$ with $19.4{\pm}5.0$ years of driving experiences. All subjects were instructed to keep a constant following distance (30m) from the car ahead and a given vehicle speed (80km/h or 100km/h) in a driving simulator. The relative change of SCL, vehicle velocity deviations, and average following distances were measured during driving only and driving with secondary tasks. The relative change of SCL, average following distance, and vehicle velocity deviation were more increased during the driving with secondary tasks than driving only. The relative change of SCL, vehicle velocity deviation, and average following distance were more affected by driving with 100km/hr than 80km/hr of a given vehicle speed. Secondary tasks increased a work load of drivers in term of SCL change, and decreased driving performance in terms of the vehicle velocity deviation and average following distance.

• Journal of Pharmacopuncture
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• v.6 no.2
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• pp.91-104
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• 2003

Objective : This study was carried to make out the connection between cerebral artery blood flow velocity and ischemic theory that presumed the cause of Bell's palsy. Method : We measured cerebral artery blood flow velocity each external carotid artery, internal carotid artery, common carotid artery, siphon, superficial temporal artery by TCD to 20 patients who diagnosed as facial nerve palsy from march 2001 to July 2001 and all objectives devided two groups as palsy side. A group is right side facial nerve palsy and B group is left facial nerve palsy. Results : 1. There is no effective change of blood flow in external carotid artery either A, B group. 2. There is no effective change of blood flow in internal carotid artery either A, B group. 3. There is no effective change of blood flow in common carotid artery either A, B group. 4. There is no effective change of blood flow in siphon artery either A, B group. 5. There is no effective change of blood flow in superficial temporal artery either A, B group.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2017.05a
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• pp.127-128
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• 2017

Tests are conducted according to the ISO TS 16774, Part 3 standard for quality management of leakage repair materials used in cracks in underground concrete structures. These test methods are performed indirectly using a nonwoven fabric on a chalet containing leak repair materials. However, it is considered that it is appropriate to verify the resistance of the repair material, which is required to be applied directly to the cracks in the actual field and to exhibit the resistance of the flow velocity. In this study, mass change was measured by using nonwoven fabric and nonwoven fabric. As a result, both methods showed an increase in mass, which indicated that the maintenance material itself contained a large amount of water, and that the mass change occurred depending on the drying state. Also, depending on the use of nonwoven fabric, the error due to the indirect test could not be ruled out. Therefore, further verification is needed, and it is considered that the test for change of mass reduction measurement is necessary according to the drying time of other types of the same series.

• Journal of Oriental Neuropsychiatry
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• v.20 no.1
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• pp.199-214
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• 2009

Objectives : This study was performed to change of blood flow in In-Young(ST9) after treatment on chronic daily headache patients. Methods : Monitoring of TCD was examined in 10' s chronic daily headache patients before and after treatment. Mean velocity flow, systolic velocity and pulsatility index were analyzed from TCD at In-Young(ST9). The patients was laid for 20 minutes before treatment and also for treatment. Results : The results showed a significant(p<0.05: Paired T-test) decrease in mean velocity flow and systolic velocity. but there were no significant differences in pulsatility index. Conclusions : These results suggest that there were significant change on blood flow in In-young of chronic daily headache patients.

• Journal of Advanced Marine Engineering and Technology
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• v.24 no.6
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• pp.15-23
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• 2000

In the present study, flow characteristics of turbulent pulsating flow in the square-sectional $180^{\circ}$curved duct are investigated experimentally. In order to measure axial direction velocity and secondary flow distributions, experimental studies for air flow are conducted in the square-sectional $180^{\circ}$curved duct by using the LDV system with the data acquisition and the processing system of the Rotating Machinery Resolver (RMR) and the PHASE software. The experiment is conducted on seven sections form the inlet($\phi=0^{\circ}$) to the outlet($\phi=180^{\circ}$) at $30^{\circ}$intervals of the duct. The results obtained from the experimentation are summarized as follows : In the axial direction velocity distributions of turbulent pulsating flow, when the ratio of velocity amplitude (A1) is less than one, there is hardly any velocity change in the section except near the wall and in axial velocity distribution along the phase. The secondary flow of turbulent pulsating flow has a positive value at the bend angle of $150^{\circ}$regardless of the ratio of velocity amplitude. The dimensionless value of secondary flow becomes gradually weak and approaches zero in the region of bend angle $180^{\circ}$without regard to the ratio of velocity amplitude.

• Journal of the Korean Society of Physical Medicine
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• v.10 no.1
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• pp.115-120
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• 2015

PURPOSE: Vertebrobasilar insufficiency (VBI) should be carefully assessed in patient for whom manipulation of the cervical spine is to be undertaken. The purpose of this study was to investigate the changes in posterior cerebral artery blood flow velocity following head and body positioning by transcranial doppler ultrasonography (TCD) in healthy subjects. METHODS: Twenty two healthy female (mean age $20.77{\pm}1.30yrs.$) participants volunteered to participate in the study. None of the participants had a history of neck pain or headache within the last 6 months. To evaluate the cerebral blood flow, we measured the mean flow velocity of the posterior cerebral artery unilaterally (right side). The blood flow velocity was measured under 3 different head positions (in a neutral head position, ipsilateral head rotation and contralateral head rotation position) and 2 different body conditions (supine position and sitting position). RESULTS: The mean blood flow velocity of posterior cerebral artery was decreased in body positioning from supine to sitting (p<.05), but the decreased rate of blood flow velocity in posterior cerebral artery did not change significantly between ipsilateral head rotation and contralateral head rotation (p>.05). CONCLUSION: These result of our study show that body positioning (sitting and supine) affect the blood flow velocity in posterior cerebral artery.

• Fire Science and Engineering
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• v.21 no.3
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• pp.61-68
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• 2007

The purpose of this study analyzes heat flows and fire behavior through a reduced-scale model experiments about change of wind velocity in underground life space. When the wind velocity is increased the temperature rise time of the fire room was risen fast. And temperature of fire room was increased. And increase of wind velocity displayed maximum temperature at an opening of the fire room. Heat flows by fire spread increase size of smoke occurrence and flame, and displayed high temperature distribution in passageway than inside of neighborhood department promoting eddy flow spread as wind velocity increases. Finally, heat flows are decided by wind and wind velocity at fire of underground life space, and Wind velocity increases, temperature increase and decrease could confirm that is gone fast.