• Journal of Environmental Science International
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• v.28 no.4
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• pp.423-433
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• 2019

This study was carried out to identify the problems of the underground watersheds on Jeju Island, and to establish the hydraulic groundwater basin to be used as basis for the analysis of the groundwater model. In order to evaluate the adequacy of the groundwater basin on Jeju Island, a correlation analysis between elevation and groundwater level was conducted using data from 125 observation wells. The analysis, conducted with an elevation step of 100 m, exhibited values of R2 in the range 0.1653-0.8011. No clear correlation was observed between elevation and groundwater level. In particular, the eastern and western areas showed an inverse proportionality between elevation and groundwater level. The Kriging technique was used to analyze the underground water level data and to define the equipotential lines for all areas of Jeju Island. Eight groundwater watersheds were delineated by considering the direction of groundwater flow, the positions of the observation wells, and the long and short axes of the watersheds.

• The Journal of the Korea Contents Association
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• v.11 no.7
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• pp.179-191
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• 2011

This study aims to elucidate the relationship between the characteristics of adult learners and flow in cyber-class along with relationships among flow, stress, and problem-solving ability. The research subjects were 1044 enrolled students at Cyber University located in Seoul through voluntary on-line questionnaire. The analysis is following: The components of flow on cyber-class including enjoyment, engagement, focused attention, and time-distortion show the significant difference upon the characteristics of adult learners such as school grade, age, marital status, and number of registered classes. In addition, the flow on cyber-class has the negative relationship with stress and the positive relationship with problem-solving ability. To improve the level of flow on cyber-class, it is important to develop the new on-line class and class materials with the consideration of characteristics and diverse backgrounds of adult learners. The incorporation of various interactive evaluation can also improve the flow level of adult learners in cyber class. Finally, the learning counselling service might be essential for adult learners to experience flow on cyber-class.

• The Korean Journal of Community Living Science
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• v.25 no.3
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• pp.349-361
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• 2014

This study was examined the general trends in social activity participation, the flow degree, and the psychological well-being of middle-aged women in Korea and explored how psychological well-being varies according to various sociodemographic variables, social activity participation, and the flow degree. This study provided practical insights into how the psychological well-being of middle-aged women can be enhanced. Data were gathered from 302 middle-aged women between the ages of 40 and 60 by using a structural questionnaire. The statistical methods included a descriptive analysis, a t-test, and a regression analysis using SPSS WIN 18.0. According to the results of the hierarchical regression analysis, the key variables influencing the psychological well-being of middle-aged women included the flow degree in terms of social activity participation and the education level. These variables explained 30% of the psychological well-being of middle-aged women. The higher the education level and the flow degree, the stronger the psychological well-being was. Social activity participation and the flow degree had greater effects on psychological well-being than sociodemographic characteristics. In particular, an increase in the flow of social activities increased psychological well-being. This suggests a need to improve the psychological well-being of middle-aged women by providing them with an environment where they can play social roles. One way to accomplish this is by linking retraining and life-long education-related activities to employment or volunteer activities. This study demonstrates the importance of the flow degree for the psychological well-being of middle-aged women. The results have important policy and theoretical implications.

• 한국해양학회지
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• v.28 no.2
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• pp.86-100
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• 1993

Three-dimensional baroclinic hydrodynamic model, BACHOM-3, is developed using ADI finite difference scheme. The model is applied to a uni-nodal standing wave in a rectagular basin. The model results for the surface elevation and velocities coincide with the analytical results. To verify the field applicability of the model and to investigate the flow patterns of the Suyoung Bay in Pusan, Korea, the model is applied to the bay. The numerically predicted velocity predicted velocity fields during spring tide at normal river flow are compared with field measurements, the comparisons show good agreement. A clockwise residual circulations at the first level (depth = 0∼2m) and the second level (depth=2∼5 m) of the central part of the bay occur, and the ebb flow is stronger than the flood flow. Computed velocity fields show that the phase difference of velocities between the surface layer and bottom layer occurs and the phase lag increases with height from the bottom. Then, the model is applied successfully for the computation of flow fields considering flood river flow and wind effects. When the wind is blowing toward the land from the sea, the flow patterns at the surface layer correspond with the wind direction, but the flow patterns at the near solid boundary of the lower layer show opposite currents to the wind direction.

• The KSFM Journal of Fluid Machinery
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• v.20 no.1
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• pp.74-80
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• 2017

Pump sump system or pumping stations are built to draw water from a source such as river and used for irrigation, thermal power plants etc. If pump sump is improperly shaped or sized, air entraining vortices or submerged vortices may develop. This may greatly affect pump operation if vortices grow to an appreciable extent. Moreover, the noise and vibration of the pump can be increased by the remaining of vortices in the pump flow passage. Therefore, the vortices in the pump flow passage have to be reduced for a good performance of pump sump station. In this study, the effect of pump intake leaning angle and flow rate on the pump sump internal flow has been investigated. There are three cases with different leaning angle. Moreover, a pipe type with elbow also has been studied. The flow rate with three classes of air entraining vortices has been examined and investigated by decreasing the water level. The result shows that the air entraining vortices easily occurs at the pump intake with large leaning angle. Moreover, the elbow type of the pump intake easily occurs air entraining vortices at the high flow rate (or velocity) in comparison to other pump intake type.

• 제어로봇시스템학회:학술대회논문집
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• 1996.10b
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• pp.195-198
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• 1996

The control objective of drum level of boiler in thermal power plant is to maintain drum level at constant setpoint regardless of disturbance such as main steam flow. The initial response of the drum level loop process is in a direction opposite to the final response. The drum level loop shows inverse response when the power is changed abruptly. We adopt fuzzy controller using knowledge base considering system dynamics for controlling drum level. Finally, the simulation result using the digital simulator for boiler system in Seoul Power Plant Unit 4 shows the validity of fuzzy controller.

• Proceedings of the KIEE Conference
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• 2004.11c
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• pp.322-324
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• 2004

Up to the present, digital replantation patients has appealed different symptoms due to blood circulatory failure. But, the level of blood circulatory failure has been evaluated only by clinical symptoms, or angiography. According to the cases of digit replantation is increasing, then objective evaluation methods of the level of blood circulation failure is needed other than patient's subjective symptoms and complaints. Although angiography, doppler, electromagnetic flowmeter, laser blood flowmeter, mechanical blood flowmeter has been used for the evaluation of the blood circulatory failure, the result was affected by time, place, surrounding temperature, patient's body temperature, and even emotion. Therefore, it is pointed out with lack of availability, feasibility and reproducibility. Thus, we compared digital blood flow of dominant hand to non dominant hand, and replanted fingers to opposite normal fingers from developed photo-plethysmography. The average digital blood flow showed no difference in normal digits each other, but, replanted digits showed average of 53% (9 - 100 %) compare to opposit normal digits. As it measure relative blood flow for circulatory failure of tissue such as fingers and toes more sensitively, reliably. In conclusion, it is expected that photo- plethysmography will be very useful for diagnosis, curative effect, prognosis of blood circulatory failure in digital replantation patient.

• 한국생물공학회:학술대회논문집
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• 2000.04a
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• pp.141-144
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• 2000

Highly open porous polymer matrices are required for high density cell seeding, efficient nutrient, and oxygen supply to the cells cultured in the three dimensional matrices. However, there are severe problems of mass transfer limitations within the cell/scaffolds culture system. Thus we hypothesize that continuos-flow culture conditioning of cells with the scaffolds may improve the cell viability and the differentiated function. In this study, we fabricated porous PLGA scaffolds by using gas-foaming/salt-leaching method as previous described. Viscous PLGA gel paste contains ammonium bicarbonate particulates, acting as a gas-foaming agent as well as a salt-leaching porogen, were cast into Teflon mold and dried. Ammonium bicarbonate salt upon contact to an acidic aqueous solution evloves gaseous ammonia and carbon dioxide by itself. And we conjugated galactose moiety [AGA; $N-(aminobuty1)-O-{\beta}-D-galactopyranosyl-(1{\rightarrow}4)-D-glucoamide]$ to the terminal end group of a PLGA to increase the cell adhesion and matain the differentiated function of hepatocytes. Cell-seeded scaffolds were secured in a flow bioreactor chamber and exposed to continuous flow at 5 ml/min. As a result of our study, the high yield of hepatocytes attachment was accomplished by increasing the concentration of PLGA-AGA conjugate in polymer scaffolds and cells in the scaffolds under continuos flow condition maintained a high level of viability and albumin secretion rate of cultured hepatocytes showed a higher level that of control groups.

• The Journal of Korean Physical Therapy
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• v.22 no.5
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• pp.49-56
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• 2010

Purpose: The aim of this study was to evaluate a possible role for cranial artery velocity in cervicogenic headache. Methods: We studied 13 patients with cervicogenic headaches (M=9, F=4, age=$24.50{\pm}3.50\;y$) these were compared to 20 normal subjects (M=10, F=10, age=$23.30{\pm}2.90\;y$). Cervicogenic headache patients were divided into two groups (a myofascial relaxation group, a placebo group). Pain levels were measured using a visual analog scale (VAS). Transcranial Doppler (TCD) ultrasound recordings were used to measure blood flow velocity in the cranial artery. Results: Cervicogenic headache patients exhibited a significantly lower blood flow velocity in the middle cerebral artery. The patients who received an intervention had a significantly higher blood flow velocity in the left middle cerebral artery, right vertebral artery and basilar artery. Compared to the placebo group, the myofascial relaxation group exhibited a significantly decreased level of pain. Conclusion: Cervicogenic headache is pain referred to the head from a source in the cervical spine. Manual therapy affect to cervical spine and soft tissue as well as the passage of these vessels and nerves to recover because it is thought to be able to help.

• Transactions of the Korean Society of Mechanical Engineers
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• v.18 no.5
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• pp.1253-1263
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• 1994

The experimental study is carried out to identify the combustion generated noise mechanism in free turbulent jet diffusion flames. Axial mean fluctuating velocities in cold and reacting flow fields were measured using hot-wire anemometer and LDv.The overall sound pressure level and their spectral distribution in far field with and without combustion were also measured in an anechoic chamber. The axial mean velocity is 10-25% faster and turbulent intensities are about 10 to 15% smaller near active reacting zone than those in nonreacting flow fields. And sound pressure level is about 10-20% higher in reacting flow fields. It is also shown that the spectra of the combustion noise has lower frequency characteristics over a broadband spectrum. These results indicate that the combustion noise characteristics in jet diffusion flames are dominated by energy containing large scale eddies and the combusting flow field itself. Scaling laws correlating the gas velocity and heat of combustion show that the acoustic power of the combustion noise is linearly proportional to the 3.8th power of the mean axial velocity rather than 8th power in nonreacting flow fields, and the SPL increases linearly with logarithmic 1/2th power of the heat of combustion.