• Journal of the Korean Society for Nondestructive Testing
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• v.36 no.5
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• pp.391-398
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• 2016

Acoustic emission (AE) is one of the most powerful techniques for detecting damages and identify damage location during operations. However, in case of the source location technique, there is some limitation in conventional AE technology, because it strongly depends on wave speed in the corresponding structures having heterogeneous composite materials. A compressed natural gas(CNG) pressure vessel is usually made of carbon fiber composite outside of vessel for the purpose of strengthening. In this type of composite material, locating impact damage sources exactly using conventional time arrival method is difficult. To overcome this limitation, this study applied the previously developed Contour D/B map technique to four types of CNG storage tanks to identify the source location of damages caused by external shock. The results of the identification of the source location for different types were compared.

• Journal of Korea Multimedia Society
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• v.21 no.2
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• pp.188-198
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• 2018

With recent development of high-speed wide-area wireless networks and wide spread of highperformance wireless devices, the demand on seamless video streaming services in Long Term Evolution (LTE) network environments is ever increasing. To meet the demand and provide enhanced Quality of Experience (QoE) with mobile users, the Dynamic Adaptive Streaming over HTTP (DASH) has been actively studied to achieve QoE enhanced video streaming service in dynamic network environments. However, the existing DASH algorithm to select the quality of requesting video segments is based on a procedural algorithm so that it reveals a limitation to adapt its performance to dynamic network situations. To overcome this limitation this paper proposes a novel quality selection mechanism based on a Deep Q-Network (DQN) model, the DQN-based DASH ABR($DQN_{ABR}$) mechanism. The $DQN_{ABR}$ mechanism replaces the existing DASH ABR algorithm with an intelligent deep learning model which optimizes service quality to mobile users through reinforcement learning. Compared to the existing approaches, the experimental analysis shows that the proposed solution outperforms in terms of adapting to dynamic wireless network situations and improving QoE experience of end users.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.16 no.12
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• pp.8830-8835
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• 2015

As the smallest unit in the composition of any melody, motive forms the basis for melodic tunes and establishes a starting point for any creation. Among other melody composition methods, how to form a motive, change it, and refine it to develop a solo is important in playing solos, and in an impromptu jazz solo, analyzing how motive is changed and developed and using it can be a method or idea to approach a more melodic solo. This thesis consists of a thorough analysis of the kinds of developmental methods that were used to change and advance motives in three solos by Larry Grenadier, a musician who is active with creative ideas in many genres of contemporary jazz music. After such analysis, these motive development methods were applied to a rendition. Since judgment was used in the motive development methods mentioned in the introduction, elements in the methods that appeared to be motives but were impossible to analyze were excluded from the analysis, therefore making it one limitation of this study. There will be a need for future studies to overcome this limitation.

• Journal of Korean Physical Therapy Science
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• v.13 no.1
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• pp.29-38
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• 2006

The purpose of this study lies in finding out the effect that variation of pain and body deflection posture has an influence on the static spinal stabilization after having performed spinal stabilization exercise making degenerative disc disease patients an object over 8 weeks using $CENTAUR^{(R)}$, 3-D spinal stabilization training implement. Subjects : 61 of DDD patients were made as an object of this study (mean age: 45.46 years, SD: ${\pm}12.78$, range: 16-68), their average height was 161.87cm, average weight 60.70kg, 12 males and 49 females were involved. Methods: 8 various investigations were performed and varied values were compared with reinvestigation done after having exercised 8 weeks using 3-D $CENTAUR^{(R)}$. We used VAS(Visual Analog Scale) in order to see the variation of pain intensity, MOS(Modified Oswestry Scale) in order to see activities of daily life. Results VAS was lessened from 7.50 to 2.71, limitation of routine life(MOS) from 20.26 to 9.32, there were remarkable differences statistically(p<0.05). As a result of muscular investigation for static spinal stabilization by 8 variations of body deflection, muscular strength were all increased and there were remarkable differences statistically(p<0.05). Conclusions : It has been turned out that pain and limitation of daily life was lessened as a result of making 61 of degenerative disc disease patients exercised 8 weeks using $CENTAUR^{(R)}$, 3-D spinal stabilization training implement, deep muscular power was increased. Thus it has been turned out that 3-D lumbar stabilization exercise has an effect on the spinal muscles strengthening and alleviation of their pain for degenerative disc disease.

• Journal of Korean Academy of Nursing
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• v.39 no.3
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• pp.349-356
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• 2009

Purpose: The purpose of this study was to identify the influence of the type-D personality on quality of life and illness intrusiveness. Methods: This study was a cross-sectional study. Data were collected using self-reported questionnaire from 200 patients with coronary artery disease(CAD). Variables were measured with the Type-D Scale-14(DS14), Korean Health Related Quality of Life Scale(KoQoLS), and the Illness Intrusiveness Rating Scale(ILRS). Results: Of the patients, 38% were classified as type-D personality. Among the 10 subcategories of quality of life, the highest mean score was bodily pain($5.84{\pm}2.85$) and the lowest was role limitation($1.52{\pm}1.20$). Among 13 item of illness intrusiveness, the highest mean score was health($3.78{\pm}1.73$) and the lowest was family relationships($2.14{\pm}1.58$). There were significant differences in all the subcategories of quality of life between type-D and non type-D except for subcategories of bodily pain and role limitation. However, there were no significant differences in illness intrusiveness between type-D and non type-D. Conclusion: Type-D is an important factor in quality of life in patients with CAD, but no correlations between type-D and illness intrusiveness were found. These results can be used as basic data for developing cardiac rehabilitation programs to improve quality of life in type-D patients.

• Human Ecology Research
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• v.52 no.4
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• pp.325-336
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• 2014

The purpose of this study is to investigate the relationship between self-esteem and the view of the afterlife of the elderly by focusing on mediating effects of positive satisfaction and death preparation. Therefore, this study emphasizes the importance of the rest of life and contributes as exploratory research toward strengthening the psychological and emotional well-being of the elderly. After using a structural equation model, we found that self-esteem influenced their view of the afterlife through mediating effects such as positive satisfaction and the level of death preparation. The results of this study will present not only in recovering from death anxiety through an understanding of the level of death preparation and, the view of the afterlife but also in the development of practical intervention materials, which can be useful in social work for the elderly. The elderly's view of the afterlife should be strengthened according to the educational programs on death preparation that deal with the existence of the afterlife and life after death. However, this study has the limitation that only people living in Seoul and Gyeonggi Province and not in the other areas of the country were considered in this research. Nevertheless, within its limitation, this study's findings are promising, as they contribute to our understanding of the view of life and death of the elderly; further, the study has academic meaning with respect to helping the elderly successfully carry out their life development tasks and significantly prepare for the rest of their life.

• KSBB Journal
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• v.11 no.2
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• pp.246-253
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• 1996

An obligatory methanotroph Methylosinus trichosporium OB3b was cultivated for the production of poly-${\beta}$-hydroxybutyric acid(PHB) in shake-flask using liquefied natural gas(LNG) as the sole source of carbon and energy. The maximal specific growth rate decreased by 40% using LNG compared with that obtained with pure methane. This is attributed to the inhibition by ethane and propane presents in the LNG as impurities. For the production of PHB, two-stage culture separating the production stage from the growth stage was carried out. PHB accumulation was observed after switching nutrient-sufficient to nutrient-limited condition of non-carboneous component (NO3-, PO43-, K+, Na+, Fe2+, or Mg2+). The limitation of K+ or Mg2+ resulted in relatively high PHB content, but the highest content was obtained by nitrate limitation. The optimal pH and temperature for PHB accumulation was 7.0 and $30^{\circ}C$. Under the optimal condition the maximal PHB content was about 45% after 4-day cultivation.

• Korean Journal of Construction Engineering and Management
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• v.8 no.1 s.35
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• pp.124-131
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• 2007

Project management means usually managing the rate of construction progress. But it also contains preparing scheme of execution and establishing plan for equipment, material, labor force to finish project within expected duration. In this paper to establish effective project planning a road pavement operation is selected as a case and simulation method is used for analyzing it. Next probability distributions are created after analyzing collected data and these are reflected in simulation model. Simulated result is compared with real project planning using models of lean concrete pavement process and concrete slab pavement process to verify efficiency of this model. In the event we know that project planning using simulation is more effective than one of the field in the aspects of duration and cost. Meanwhile simulated result in this paper has a limitation in accuracy because various constraints of filed are not reflected in it. However if we reflect this constraints in model through examining field in future this limitation is expected to be improved.

• Proceedings of the Korean Institute Of Construction Engineering and Management
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• 2008.11a
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• pp.753-757
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• 2008

The objects of this study are to increase the efficiency and competitiveness for construction management and field supervision by using IT technology which is a trend of construction industry thesedays. Using RFID technology can play an important role to achieve the goal, but it is necessary to research a standard of using frequency, specific, protocol, package method and reading method because it is hard to apply RFID to physical, chemical, environmental specifics. In this study as a part of planning research to standardize, a limitation item Is conducted with RFID tag attached building materials, and RFID Tag goods which solve the restriction are produced to conduct a field application test. From the result, available reading distance is different according to physical and environmental specifics. Furthermore because the different application method and attaching method make a various management efficiency, the current management of construction materials is analyzed and applied to a construction field to provide to various limitation items and recovery plan.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.33 no.9
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• pp.709-717
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• 2009

Heat transfer rate is a very important factor for the performance of a steam reformer because a steam reforming reaction is an endothermic reaction. Coaxial cylindrical reactor is the reactor design which can improve the heat transfer rate. Temperature, fuel conversion and heat flux in the coaxial cylindrical steam reformer are studied in this paper using numerical method under various operating conditions. Langmuir-Hinshelwood model and pseudo-homogeneous model are incorporated for the catalytic surface reaction. Dominant chemical reactions are assumed as a Steam Reforming (SR) reaction, a Water-Gas Shift (WGS) reaction, and a Direct Steam Reforming (DSR) reaction. Although coaxial cylindrical steam reformer uses 33% less amount of catalyst than cylindrical steam reformer, its fuel conversion is increased 10 % more and its temperature is also high as about 30 degree. There is no heat transfer limitation near the inlet area at coaxial-type reactor. However, pressure drop of the coaxial cylindrical reactor is 10 times higher than that of cylindrical reactor. Operating parameters of coaxial cylindrical steam reformer are the wall temperature, the inlet temperature, and the Gas Hourly Space Velocity (GHSV). When the wall temperature is high, the temperature and the fuel conversion are increased due to the high heat transfer rate. The fuel conversion rate is increased with the high inlet temperature. However, temperature drop clearly occurs near the inlet area since an endothermic reaction is active due to the high inlet temperature. When GHSV is increased, the fuel conversion is decreased because of the heat transfer limitation and short residence time.