• Proceedings of the Korean Society of Precision Engineering Conference
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• 2002.10a
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• pp.776-779
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• 2002

A bellows diaphragm design program for mechanical seal was developed in this study. This program was written in AutoLISP on the AutoCAD system with a personal computer. Basic design concept used in this program is composition of a convolution that is tangent to two lines and five circles from given design parameters(initial radius, inner and outer diameter, thickness, pitch, etc.). The effects of altering some design parameters on stress distribution of bellows were estimated using commercial FEM code, NISAII. As a result, the bellows diaphragm for mechanical seal was successfully designed by the program. The FEM result shows that stress is dependent on straight line length and bellows diameter with same span.

• Journal of International Academy of Physical Therapy Research
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• v.3 no.2
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• pp.458-463
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• 2012

This study is to examine the effects of a feedback breathing device exercise and diaphragm breathing exercise on pulmonary functions of chronic strokes patients. The selection of 20 subjects was divided equally and placed into a experiment group and a control group and the intervention was applied four times per a week for five weeks. In each session, both groups received rehabilitative exercise treatment for 30 minutes, and a feedback breathing device exercise for 15 minutes. In addition, experimental group conducted a combination of diaphragm breathing exercise for 15 minutes. Prior to and after the experiment, patients' pulmonary functions were measured using a spirometer. The pulmonary function tests included FVC, FEV1, FEV1/FVC, PEF, VC, TV, IC, ERV, IRV. With respect to changes in the pulmonary functions of both groups, the experimental group significantly differed in FVC, FEV1, TV, ERV but did not in PEF, FEV1/FVC, VC, IRV. The control group did not significantly differ in any of the tests. There were significant differences in FEV1, FEV1/FVC, TV, ERV between the two groups, but no significant differences in FVC, PEF, FEV1/FVC, VC, IRV between them after the experiment. The experimental group, which conducted a combination of a feedback breathing device exercise and diaphragm breathing exercise, saw their respiratory ability increase more significantly than the control group. The breathing exercise was found to improve pulmonary function in chronic stroke patients.

• Proceedings of the Korean Geotechical Society Conference
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• 2008.10a
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• pp.605-613
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• 2008

Application of anchored or strutted wall system for the earth retention of excavation works in a populated urban area or a poor soil deposit can be limited due to various restrictions. Since the strut becomes longer in a wide excavation site, the stability of an earth retaining wall is decreased, the wall deformation is increased, and the ground settlement is also increased due to an increased buckling or bending deformation of struts. Especially, in a populated urban area, the installation of anchors can be problematic due to the property line of adjacent structures or facilities. Thus, a new concept of earth retaining system like Self-Supported diaphragm Wall can solve several problems expected to occur during excavation in the urban area. Application of self-supported counterfort diaphragm wall was verified in this paper though comparing the design of self-supported counterfort diaphragm wall with the data monitored during excavation in Singapore.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2010.11a
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• pp.474-478
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• 2010

Hybrid rocket combustion experiments using liquefying diaphragm made by blended liquefying fuel with 10 wt% of LDPE were performed. Results of experiments were compared to the those of pure paraffin. In case of using liquefying diaphragm, regression rate of rear fuel grain, characteristic velocity and specific impulse highly increased due to the induced turbulent intensity and heat transfer. The serious combustion instability was not observed in analysis of combustion instability. These results can imply that the liquefying diaphragm is efficient to improve low combustion efficiency in hybrid rocket using liquefying fuel.

• Steel and Composite Structures
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• v.10 no.3
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• pp.261-279
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• 2010

Generally, a box tube, which is used for an existing square CFT structure, is made by welding four plates. The manufacturing efficiency of this steel tube is poor, and it also needs special welding technology to weld its internal diaphragm and the through diaphragm. Therefore, an interior-anchor-type square steel tube was developed using the method of cold-forming thin plates to prevent welding of the stress concentration position, and to maximize the section efficiency. And, considering of the flow of beam flange load, the efficiency of erection and the weldability of the diaphragm to thin walled steel column, the external diaphragm connection was selected as the suitable type for the welded built-up square CFT column to beam connection. And, an analytical study and tests were conducted to evaluate the structural performance of the suggested connection details and to verify the suggested equations for the connection details. Through this study, the composite effect of the internal anchor to concrete, the resistance and stress distribution of the connections before and after the existing column is welded to the beam, the effective location of welding in connection were analyzed.

• Korean Journal of Optics and Photonics
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• v.12 no.6
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• pp.463-467
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• 2001

In this study, we developed a FFPI (fiber optic Fabry-Perot interferometer) pressure sensor using the Si diaphragm which measures pressure in vivo. The diaphragm and its supporting structure were etched in KOH solution and were fabricated with micromachining technology. For the configuration of the sensor, the length of the cavity of the Fabry-Perot etalon is 15 mm and one end of the etalon was bonded to a Si diaphragm with 507m thickness. When the area of the Si diaphragm was 2$\times$2 mm2 (cavity length 15 mm), it turns out that the pressure sensitivity was about 1.5 degree/kPa. The pressure sensor developed in this study showed that the phase change was linearly proportional to the increasing pressure in the range of 80 kPa.

• Elastomers and Composites
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• v.55 no.3
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• pp.222-228
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• 2020

Rubber materials, used in nuclear power plants, need high heat-oxidation resistance to curing or cracking under a heat aging environment. This is because they are applied to environments with high temperature, high humidity, and radiation exposure. Nuclear radiation causes additional hardening or degradation, therefore, rubber materials need radiation resistance that satisfies the general and any accidental conditions produced in the power plant. Therefore, in this study, we developed a rubber material with excellent heat and radiation resistance for the diaphragm seal of a nuclear steam generator nozzle dam. The rubber material greatly improved the reliability of the steam generator nozzle dam. In addition, 30 inch and 42 inch diaphragm seals were manufactured using the developed rubber material. A nozzle dam was installed in a nuclear power plant and tested under the same conditions as a steam generator to evaluate safety and reliability. In the future, the performance and safety of diaphragm seals developed through field tests of nuclear power plants will be evaluated and applied to currently operating and new nuclear power plants.

• Journal of Chest Surgery
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• v.44 no.1
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• pp.86-88
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• 2011

Bronchogenic cysts are developmental foregut anomalies usually located within the mediastinum or lung parenchyma. An isolated bronchogenic cyst of the diaphragm is very rare. Our case was a 56-year-old female patient who presented with pleuritic chest pain in her right chest. Chest and abdominal computed tomography revealed a large lobulated cystic mass that was accompanied with pleural effusion in the right lower hemithorax. The tumor showed focally calcified areas in the wall and abutted against the diaphragm. We performed complete excision of the cyst including a portion of the diaphragm attached to it. The pathological diagnosis was established as the bronchogenic cyst originating from the diaphragm. We report this case with a review of the literature.

• Korean Journal of Materials Research
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• v.21 no.7
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• pp.403-409
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• 2011

Micro speakers are used to reproduce sound in small electric and information and communications devices, such as cellular phones, PMPs, and MP3 players. The acoustical properties and sound quality, which are changed due to the decreased size of the speaker, are often adjusted varying the type and thickness of the diaphragm. The most widely used diaphragm material is thin polymer. It was previously reported by the author of this paper that the resonance frequency of a micro speaker is changed by the type and thickness of a polymer diaphragm. In this paper, the frequency response near the resonance frequency of a micro speaker was studied as functions of the type and thickness of the polymer diaphragm. While $R_{max}$ and $R_{DC}$ were affected by the type and thickness, an analysis of the electrical impedance curve revealed that $R_o(= R_{max}/R_{DC})$ and ${\Delta}f$ were not changed. Thus, $Q_{TS}$ which was function of $R_o$, ${\Delta}f$, and the resonance frequency, is only related to the resonance frequency. The increase of the resonance frequency led to a proportional rise of $Q_{TS}$. The change of the frequency response near the resonance frequency was not dependent on the type or thickness of the polymer diaphragm, but was affected by the resonance frequency.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2004.11a
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• pp.763-766
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• 2004

Recently, various acoustic artifacts that contains speaker have been produced such as cellular phone. Speaker consists of diaphragm generating sound and coil vibrating diaphragm. Generally, good speaker means that it has a wide frequency range, high output power rate to input power and flat sound pressure level in specified frequency range. Acoustic characteristic was estimated through the experiment and computer simulation, or sound power was controlled with acoustic sensitivity in a natural frequency range fer last decade. However, the flatness of sound pressure level has not been considered to enhance the sound quality of a speaker. Tn this study, a method for speaker design is proposed for a good acoustic characteristic, which is flatness of SPL(sound pressure level) and wideness between the first and second natural frequency. SYSNOISE is used fer acoustic analysis and ANSYS is used for harmonic response analysis and modal analysis. Optimization for acoustic characteristics of a speaker diaphragm is performed using ModelCenter. All analyses are done within a frequency domain. And we confirm that the experimental and computational simulations have similar trend.