• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.10 no.5
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• pp.535-549
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• 1998

A numerical study for performance analysis of a counterflow type forced draft tower and natural draft cooling tower has been performed based on the method using the finite volume method with non-orthogonal body fitted and non-staggered grid system. For solving the coupling problem between water and air, air enthalpy balance, moisture fraction balance, water enthalpy balance, and water mass balance equations are solved with Navier-Stoke’s equations simultaneously. For the effect of turbulence, the standard k-$\varepsilon$ turbulent model is implied in this analysis. The predicted result of the present analysis is compared with the experimental data and the commercial software result to validate the present study, The predicted results show good agreement with the experimental data and the commercial software result. To investigate the influence of the cooling tower design parameters such as approach, range and wet bulb temperature, parametric studies are also peformed.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.5 no.3
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• pp.204-211
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• 1993

Boundary element method is applied to simulate nonlinear water waves using Green's identity formula in a numerical wave flume. A system of linear equations is formulated from the governing equation and free surface boundary conditions in order to calculate velocity potential and water surface elevation at each nodal point. The velocity square terms are included in the dynamic free surface boundary condition. The free surface is treated as a moving boundary. the vertical variation of velocity potential being considered in calculating the time derivative of the velocity potential at the free surface. The present method is applied to simulate solitary wave and Stokes 2nd order wave, and shows excellent agreements with their theoretical values.

• Journal of the Korean Society of Safety
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• v.24 no.6
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• pp.27-31
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• 2009

An experimental study on the unsteady effect of the extinction limit was performed in ethene jet diffusion flames. To impose the unsteadiness on jet flames, the amplitude and frequency of a co-flow velocity was varied, and the two inert gases, $N_2$ and $CO_2$, were used to dilute the oxidizer for extinguishing concentration. The experimental results shows that large amplitude of velocity induces a low extinguishing concentration, which implies that flow variation affects the blow out mechanism. Also, the flow oscillation effects under high frequency attenuates the flame extinction. These results means that flow unsteadiness extends the extinction limit and finally minimum extinction concentration by inert gases. When the Stoke's 2nd Problem is introduced to explain the flow unsteadiness on extinction concentration, the solution predicts the effect of amplitude and frequency of velocity well, and hence it is concluded the effect of low frequency velocity excitation was attributed only to flow effect.

• International Journal of Air-Conditioning and Refrigeration
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• v.8 no.1
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• pp.1-13
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• 2000

A numerical study for performance analysis of a crossflow-type forced draft cooling tower has been performed based on the finite volume method with non-orthogonal body fitted, and non-staggered grid system. For solving the coupling problem between water and air, air enthalpy, moisture fraction, water enthalpy, and water mass balance equations are solved with Navier-Stoke's equations simultaneously. For the effect of turbulence, the standard k-$\varepsilon$ turbulent model is implied in this analysis. The predicted result of the present analysis is compared with the experimental data and the commercial software result to validate the present study. The predicted results show good agreement with the experimental data and the commercial software result. To investigate the influence of the cooling tower design parameters such as approach, range and wet bulb temperature, parametric studies are also performed.

• 유체기계공업학회:학술대회논문집
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• 1999.12a
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• pp.301-308
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• 1999

The present study investigates numerically particle laden flow through compressor cascades and a rocket nozzle. Engines are affected by various particles which are suspending in the atmosphere. Especially in the case of aircraft aviating in volcanic, industrial and desert region including many particles, each components of engine system are damaged severely. That damage modes are erosion of compressor blading and rotor path components, partial or total blockage of cooling passage and engine control system degradation. Numerical prediction and experimental data, erosion rates are predicted for two materials - ceramic, soft metal - on compressor blade surface. Aluminum oxide ($Al_2O_3$) Particles included in solid rocket propelant make ablative the rocket motor nozzle and imped the expansion processes of propulsion. By the definition of particle deposition efficiency, characteristics of particles impaction are considered quantitatively Stoke number is defined over the various particle sizes and particle trajectories are treated by Lagrangian approach. Particle stability is considered by definition of Weber number in rocket nozzle and particle breakup and evaporation is simulated in a rocket nozzle.

• Journal of Korean Medicine Rehabilitation
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• v.28 no.4
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• pp.103-112
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• 2018

Pathological laughing and crying (PLC) is a condition defined by relatively uncontrollable episodes of laughter, crying or both. PLC is an uncommon symptom usually caused by cerebral lesions. Midbrain involvement causing PLC is extremely unusual and the exact mechanism by which this condition develops is poorly understood. We recently experienced a 51-year-old woman who were diagnosed as PLC after midbrain infarction. She was treated by acupuncture, pulsed electromagnetic therapy (PEMT). After 6 weeks treatment, Pathological Laughter and Crying Scale (PLACS), Korean version of the Scale for the Assessment and Rating of Ataxia (K-SARA) are decreased and Korean version of Modified Barthel Index (K-MBI) is increased. Treatment of traditional Korean Medicine could be effective for stoke rehabilitation including post-stroke PLC. And we have considered mechanism of PLC associated with midbrain lesion, dysfunction of cortex-thalamus-hypothalamus-basal ganglia-mesencephalon and faciorespiratory nuclei pathways, cerebro-ponto-cerebellar pathways and damaged serotonergic neurotransmission can cause this based on recent neurobiology of emotion. To define exact mechanism and find effective treatment, further studies are needed.

• Journal of the Korea Institute of Military Science and Technology
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• v.11 no.4
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• pp.13-19
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• 2008

In order to reduce the level of recoil force, new recoil technology must be employed. The present study discusses a soft-recoil system that can reduce dramatically the recoil force. The firing sequence of the soft recoil system is radically different from that of a conventional system. The gun is latched and preloaded in its out-of-battery position prior to firing. When unlatched, the gun is accelerated and forward momentum is imparted to the recoiling parts. This momentum is opposed by the ballistic force imparted by firing and the recoil force and stoke will be reduced. In the present study, the soft-recoil system with hydraulic dampers is simulated and its characteristics are investigated theoretically. The results of the simulation show that the soft-recoil system could dramatically reduce the recoil force and the recoil stroke compared to the conventional recoil systems. However, the soft-recoil system was not able to perform well when the firing fault modes like prefire, hang-fire, and misfire happen. Hence, we need to employ a control algorithm to prevent the damage of the recoil system due to these fault mode.

• The Journal of Korean Physical Therapy
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• v.19 no.4
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• pp.25-32
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• 2007

Purpose: The purpose of this study was to evaluate the effect of computerized neurocognitive function program on cognitive function about memory and attention with stroke. Methods: 24subjects with stroke were recruited. Twelve of subjects received conventional therapy including physical therapy, occupational therapy and language therapy. Another subjects received additional computer assisted cognitive training using Computer-aided Cognitive rehabilitation training system(COMCOG, MaxMedica Inc., 2004). All patients were assessed their cognitive function of memory and attention using Computerized Neurocognitive Function Test(CNT, MaxMedica Inc., 2004) before treatment and 6 weeks after treatment. Results: Before the treatment, two groups showed no difference in cognitive function(p>0.05). After 6 weeks, two groups showed significantly difference in digit span (forward, backward), verbal learning(A5, $A1{\sim}A5$), auditory CPT(n), visual CPT(n)(p<0.05). After treatment, the experimental group showed a significant improvement of digit span(forward, backward), verbal learning(A5, $A1{\sim}A5$), visual span (forward, backward), auditory CPT(n, sec), visual CPT(n, sec), and trail-making (A, B)(p<0.05). Conclusion: Computerized neurocognitive function program would be improved cognitive function of memory and attention in patients with stoke.

• PNF and Movement
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• v.13 no.2
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• pp.111-118
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• 2015

Purpose: The purpose of this study was to describe the effects of proprioceptive neuromuscular facilitation (PNF) on episodes of foot drop and the ability to cross obstacles in stoke patients. Methods: The patient was a 57-year-old man with left hemiplegia. This patient displayed episodes of foot drop while walking and issues with crossing obstacles. The patient underwent therapeutic exercises and occupational therapy twice daily at a hospital five times a week. The patient was treated with PNF outside of these therapeutic sessions. Each session, which was 60 minutes in length, was conducted 3 times a week over 8 weeks. Over the course of treatment, a pre-test and post-test were completed. The patient walked for a test time of 6M. During the testing process, the patient crossed obstacles. In addition, the number of foot drop episodes was recorded. Each test was measured three times to determine the mean value. Results: After the PNF treatments, the number of foot drop episodes decreased from five to one. The 6M walking test time during which the patient crossed obstacles also decreased from 18 seconds to 10 seconds. Conclusion: The use of PNF treatments is beneficial to reduce the number of foot drop episodes while walking and to improve the ability to cross obstacles in stroke patients.

• Journal of East-West Nursing Research
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• v.15 no.2
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• pp.102-109
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• 2009

Purpose: The study was conducted to ascertain the use of the complementary alternative medicine (CAM) in stroke patients, in order to provide the appropriate CAM information to patients recovering from stoke. Methods: Subjects were 201 stroke patients who were randomly selected from a health care center and a welfare center. Data from a self-administered questionnaire collected from February to April 2009 was analyzed using SPSS/WIN 12.0. Results: Subjects averaged 67.4-yr-of-age. Of the 201 subjects, 69.2% had used CAM. CAM use was statistically significant in diagnosis, duration of post stroke, paralysis, and education about CAM. CAM was used in the mid-portion of treatment by 47.3% of the subjects, and 41.7% used it for more than a year. Of those using CAM, 52.7% of the subjects responded that their reason was the belief in the treatment's beneficial effects. Of the subjects 89.2% reported most frequent use of oriental medicine. Conclusions: The majority of stroke patients surveyed frequently and continuously used CAM in their mid-period of treatment expecting positive effects.