• Proceedings of the Korean Geotechical Society Conference
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• 2005.03a
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• pp.1335-1342
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• 2005

In this paper, there is intended to introduce the new tunnel face shape, that is concave shaped face, and discusses its effects on the tunnel stabilization. Therefore, a comparative analysis in which the stability of a concave face was compared to that of a conventional plane face on the basis of displacement patterns in the tunnel face was conducted using a model test. In order to check and confirm displacement patterns on the concave face according to the radius of curvature as well as those around the face according to lateral pressure coefficient(k), two experimental concave models, produced at a scale of 1:2 and 1:5(tunnel radius), of the forefront of the curved area extended from plane face was built and tested.

• Journal of the Korean Society of Combustion
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• v.3 no.1
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• pp.1-10
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• 1998

Lots of techniques are adopted for a flame stabilization and a high-load combustion. But the techniques being used were passive control method which have to change combustor shape like pilot flame, flame stabilizer, pressure profile, etc. Active control method which is not necessary to transform its shape is employed. Acoustical excitation is broadly used for its convenience in changing frequency and intensity. Both acoustical excitation and flame stabilizers were adopted to study their relationship. So, we investigated flammability limits. Flame visualization. And mean temperature in the condition of various frequencies, intensities, and flame stabilizers. As a consequence, flammability limit were advanced in acoustically excited flame at some frequencies. Coherent structure was extended to the downstream region through acoustical excitation and a size of vortice was curtailed. Also width of recirculation zone was magnified. In addition, Effects of acoustical excitation was stood out at 25mm flame stabilizer rather than another ones.

• Ocean Systems Engineering
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• v.1 no.3
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• pp.207-222
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• 2011

A stabilized incompressible smoothed particles hydrodynamics (ISPH) method is utilized to simulate free falling rigid body into water domain. Both of rigid body and fluid domain are modeled by SPH formulation. The proposed source term in the pressure Poisson equation contains two terms; divergence of velocity and density invariance. The density invariance term is multiplied by a relaxed parameter for stabilization. In addition, large eddy simulation with Smagorinsky model has been introduced to include the eddy viscosity effect. The improved method is applied to simulate both of free falling vessels with different materials and water entry-exit of horizontal circular cylinder. The applicability and efficiency of improved method is tested by the comparisons with reference experimental results.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.10 no.10
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• pp.1810-1814
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• 2006

In this paper, the brightmess from inside gas pressure, applied voltages, and operation frequency conditions was measured and the discharge characteristics in FFL(Flat Fluorescent Lamp) also were measured and discussed. The brightness and lifetime after vacuum exhaust ($350^{\circ}C$ and 1 hour) ate remarkably developed. When the gas pressure of lamp-inside is high, the brightness is also increased automatically. But for the stabilization of operation and driving voltage, the highest values of brightness at about 1000[V], 300[Torr] and 64(kHz) are measured and the results are shown as the optimized driving conditions for FFL.

• Journal of Advanced Marine Engineering and Technology
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• v.33 no.7
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• pp.1012-1016
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• 2009

This paper describes the control and monitoring system for OWEC (Overtopping Wave Energy Converter) which shows the characteristic of power stabilization in overtopping wave energy converter system. Overtopping waves generates different water pressure and the turbine is rotated by this pressure. As a result, overtopping wave energy converter is able to convert wave energy into electricity. Small size of overtopping wave energy converter is developed to simulate the control monitoring system which is able to control power generation and also monitor the system condition. The result shows the reduction of fluctuation from the overtopping wave energy system by the developed control monitoring system. In addition, the DB(Data Base) of test results are contributed to the research and development for OWEC.

• Journal of ILASS-Korea
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• v.1 no.3
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• pp.29-36
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• 1996

The present study systematically investigates the effect of evaporation rate on the combustion characteristics and the flame stabilization in a gasoline engine. A constant volume combustion chamber was used to elucidate a basic combustion characteristics and the premixer was installed to control temperature and equivalence ratio. And the maximum pressure, combustion duration and flame propagation according to the evaporation rate were measured to determine the optimal temperature range for evaparating a gasoline fuel. These experimental results indicate that the combustion characteristics such as combustion chamber pressure and combustion duration were deteriorated by decreasing surrounding temperature of fuel injected. It was also found that the overall gasification process for gasoline fuel was strongly influenced by a combustion chamber temperature rather than a premixer temperature.

• The Journal of Korean Physical Therapy
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• v.29 no.5
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• pp.265-270
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• 2017

Purpose: This study examined the effects of neck stabilization exercises with vibratory stimulation on the neck disability index and thickness of the deep neck flexor. Methods: Thirty subjects (control group=15, experimental group=15) with mild neck pain were enrolled in the study. The control group underwent craniocervical flexion exercise (control group, CG) and the experimental group was given craniocervical flexion exercise with vibratory stimulus (experimental group, EG) (3 sets, 3 times per week for 6 weeks). To examine the effects of exercise, the subjects were evaluated using the neck disability index (NDI), the thickness of the deep neck flexor muscle, and muscle strength. An independent and paired t-test were used to compare the effects of the exercise between the groups. Results: The NDI score of the two groups increased significantly after 6 weeks of treatment (p<0.001) and there was a significant difference between the EG group at 3 weeks (p<0.05) and 6 weeks (p<0.01). The thickness of the deep neck flexor in the CG group increased significantly after 6 weeks of treatment in all pressure stages (p<0.001). The EG group showed a significant increase after 3 and 6 weeks of treatment in all pressure stage (p<0.001), and 22 mmHg, a significant difference between 3 and 6 weeks (p<0.05) and among 24, 28, and 30 mmHg at 6 weeks (p<0.05). The maximum muscle strength of the deep neck flexion muscles increased significantly in the two groups after 6 weeks of treatment (p<0.001) and there was significant difference between the EG group at 6 weeks (p<0.01). Conclusion: Craniocervical flexion exercise with vibratory stimulus decreases the NDI, and increases the thickness of the deep neck flexor and maximum muscle strength of the deep neck flexion muscles in patients with mild neck pain.

• Journal of the Korean Society of Physical Medicine
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• v.17 no.2
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• pp.29-40
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• 2022

PURPOSE: This study examined the effects of an exercise program for the thoracic spine and scapula rather than the neck, which is the primary site of pain. METHODS: Thirty-two elementary school teachers with a forward head posture (FHP) were assigned randomly to either the experimental group (n = 16) or the control group (n = 16). The experimental group performed scapular stabilization exercise (SSE) and thoracic extension exercise (TEE), and the control group performed cervical self-myofascial release exercise and stretching exercise. The pulmonary functions, pain, craniovertebral angle (CVA), and cervical range of motion (CROM) were measured before the intervention and six weeks after. RESULTS: The within-group comparisons showed that the VAS and CROM (except for extension) in both groups were significantly different before and after the intervention (p < .05). The changes in the maximum inspiratory pressure (MIP), maximum expiratory pressure (MEP), forced vital capacity (FVC), forced expiratory volume at 1 sec (FEV1), and CVA were significant only in the experimental group (p < .05). The between-group comparisons showed a significant difference in the FVC, FEV1, VAS, CVA, and left lateral flexion (p < .05). CONCLUSION: The combination of SSE and TEE in the experimental group was more effective in improving the FHP and breathing ability. Moreover, the experimental group and control combination appeared to be effective in reducing pain and improving the CROM. The combination of SSE and TEE, which are exercises that do not target the cervical spine directly, was effective in improving the posture, respiration, neck pain, and CROM in elementary school teachers with FHP.

• Physical Therapy Rehabilitation Science
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• v.9 no.1
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• pp.1-9
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• 2020

Objective: This study aimed to investigate the immediate effects of intervention using neuromuscular control, self-stretching (SS), and neck stabilization exercises (NSEs) on neck pain, range of motion (ROM), and proprioception of position sense in adults with neck discomfort. Design: Three-group pretest-posttest design. Methods: Forty-four adults who complained of neck pain participated in the experiment. They were randomly assigned to the following groups: neuromuscular control exercise (NMCE) group (n=15), SS group (n=14) and NSE group (n=15). The NMCE group did rolling with only upper limb pattern on both sides. The SS group performed neck stretching on each side, 3 sets of 30 seconds for each muscle. The NSE group had the pressure biofeedback applied with increases in pressure by 2 mmHg at a time from 20-30 mmHg while in the hook-lying position. All groups performed exercises for 10 minutes. Neck pain, ROM, and proprioception were measured to determine differences between the intervention methods. Results: Intra-group comparisons showed significant improvement after exercise in pain, ROM, and proprioception in the NMC group (p<0.05). In the comparison between groups, the NMC group had a significant decrease in pain compared to the other two groups (p<0.05). There was no difference in ROM between the groups but the NMC group showed significant improvement in left rotation compared to the stabilization exercise group (p<0.05). For proprioception, the NMC group had significantly lower error than the other two groups (p<0.05). Conclusions: NMCEs through upper extremity pattern rolling exercise is effective in improving neck pain, ROM, and proprioception.

• Journal of Energy Engineering
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• v.13 no.2
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• pp.144-151
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• 2004

Stabilization and reduction of combustion noise and NOx emission from dry low NOx combustor of GE MS7001F gas turbine were achieved. Dry low NOx gas turbines that adopt the lean premixed combustion technology frequently generate the flame instability and high NOx emissions if not adequately tuned. Dynamic pressure oscillation during the combustion mode transfer increased as ambient temperature decreased with frequency of 80㎐ and magnitude of 4-9 psi. Effects of both combustor tuning for uniform fuel flow with burner nozzles and fuel pre-filling into transfer fuel valves on stabilisation of the dry low NOx combustor were very significant. Dynamic pressure oscillation during the combustion mode change was decreased up to 2.5 psi. Also, NOx emission from GE7F DLN-1 combustor can be maintained as low as 35-43ppm (15% O$_2$) in base load operation of 150 MW.