• Transactions of the Korean Society of Mechanical Engineers A
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• v.38 no.3
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• pp.295-302
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• 2014

An internal gear pump is required to improve the flow rate and noise. Furthermore, such pumps are durable and small in size. In this study, equations of the rotor shape with multiple profiles (ellipse 1-involute-ellipse 2) were derived, and relevant performance parameters (pressure angle, irregularity, and specific sliding) of the internal gear pump to noise were predicted and compared. Rotor profiles and performance parameters were obtained by a prediction algorithm for theoretical analysis, and the effects between the design parameters and the performance parameters were analyzed. Based on the analysis results of the effects, an optimal design of the rotor profile was proposed, and a noise test of the prototype was performed to evaluate the reliability of the design.

• Journal of the Korean Society for Marine Environment & Energy
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• v.3 no.3
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• pp.34-40
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• 2000

A multisample extraction device was newly designed for efficient extraction of dissolved lipophillic organic compounds from sea water sample. This device allowed extraction of organic compounds from up to 96 sample at a time using 96 multifolder on the principle of solid phase extraction with commercially available octadecyl silane (ODS) cartridges. The recovery yield of the new divice was higher than 90 % while that of conventional liquid-liquid extraction process are only 60 - 70 %. The amount of solvent required for the new device could be reduced to less than 20㎖ per 1ℓ of sample while 1 - 2 ℓ of solvent were used in the conventional liquid-liquid extraction process. The usefulness of this novel method was demonstrated with sea water samples collected from Yellow sea, and the qualitative and quantitative analyses results of the dissolved hydrocarbon showed this method was superior to that of conventional liquid-liquid extraction process in efficiency and reliability.

• The Journal of the Korea Contents Association
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• v.5 no.3
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• pp.19-28
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• 2005

It is true that internet provides consumers with an efficient way to search information with minimal effort and cost, which facilitates better decision making. Especially, previous studies revealed that the online word-of-mouth marketing is widely used as a source of consumers' information seeking and purchase decision making. Even with this importance of the online word-of-mouth communication on internet few researches have systematically addressed the issue. This study investigates the effect of consumers' motives on perceived usefulness of word-of-mouth marketing in online shopping mall contents. The results are as follows: First, choice uncertainty, perceived sacrifice, and social pressure play an important role for perceived usefulness of word-of-mouth marketing. Second, perceived usefulness has directly affected consumers' quality perception. Thus, it is essential for internet companies to find ways to encourage their customers to engage in word-of-mouth communication on their websites.

• Journal of the Korean Institute of Telematics and Electronics
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• v.25 no.11
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• pp.1342-1349
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• 1988

The dependence of the etch rates of differently doped poly-Si films on the gas composition, the chamber pressure and the RF power was investigated in detail. The highest anisotropy and the lowest CD loss were achieved at the $SF_6$-rich compositions, i.e., $Cl_2:SF_6$=17:33 (SCCM), in the $POCl_3$-doped poly-Si. The etch rates increased for n-type dopant (phosphorus), while decreased for p-type (boron) with increasing the doping levels irrespective of plasma parameters. And from the results of the activation of doped poly-Si films the active carrier concentrations as well as the doping concentrations were found to be responsible for the increase of the etch rate of the phosphorus-doped poly-Si.

• The Journal of Information Systems
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• v.22 no.4
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• pp.23-48
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• 2013

This study shows that a sustainable competitive advantage and entrepreneurial characteristics are necessary for a software company to achieve competitive innovation and growth. This study investigates various software company characteristics and the effects of various company factors as its main research objectives. The data used in this research model were collected from software companies in South Korea. A total of 211 questionnaires were collected over a period of two months in 2013. EXCEL, AMOS, and SPSS were used to derive the study results. The hypothesis testing results of this study are as follows. First, a software company's entrepreneurial innovativeness and risk-taking behaviors have a positive influence on software innovativeness. A greater sense of innovativeness and entrepreneurial orientation leads to a higher propensity to take risks in software development. Second, the characteristics of software innovativeness, and flexibility have a significant influence on software company performance. Innovation during the initial periods of software usage can create a high demand for improvements and new features, requiring a flexible software design. Finally, this study analyzes the software features of entrepreneurial characteristics and the influence of institutional factors on the characteristics of individual innovativeness and software development. Entrepreneurial characteristics can affect governmental or institutional support, policies, and legal frameworks to promote the role of software innovativeness. The results of this study imply that software companies can adopt an entrepreneurial approach to promote technology development and product development for achieving a competitive advantage in the industry. This study also analyzes the environmental factors that affect the software industry and their implications for policy makers.

• Journal of the Korean Geotechnical Society
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• v.28 no.5
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• pp.67-76
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• 2012

This study is a research about cutter bits arrangement of shield-TBM and carried out a scale model test and numerical analysis according to a space of cutter bits. A cutter head pressures and an advance time are measured to be followed by the space of cutter bits with an advance speed through the scale model test. We conducted the numerical analysis to verify the result of the scale model test, and to compare with the scale model test. There are three cases of space : unification 1.0D and 1.5D. In case TBM is excavated and space is 1.0D, the advance speed is much faster than the other cases, and pressure of face of ground deformation and cutter head is maintained stably. If additional researches about bits arrangement of cutter head of sand ground based on the result of this research are performed, substantial results may be obtained.

• Journal of Korean Foot and Ankle Society
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• v.24 no.1
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• pp.14-18
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• 2020

Purpose: Chronic ankle instability is a very common abnormality of the ankle, but there is still controversy regarding its evaluation criteria. The stress view has difficulties in reflecting the patient's symptoms and treatment progress. Therefore, this study examined the relationship between the center of pressure (COP) measured by a pedobarograph and the symptoms of the patient. Materials and Methods: Thirty patients with chronic ankle instability from February to August 2018 were included. Each patient was surveyed with the foot and ankle outcome score (FAOS). The COP was measured with a foot pressure scanner, and the travel distance and ellipse area of the COP were calculated. Each patient was measured on one foot and on two feet with his or her eyes closed and open. The relationship between the COP measurement and FAOS score was analyzed using the Pearson correlation coefficient. Results: The participants were consisted of 21 male and nine female, with a mean age of 30 years, mean weight of 72 kg, and mean foot size of 259 mm. With the eyes open, the correlation coefficient between the FAOS and travel distance of the affected side was -0.394 (p<0.05) and that between the FAOS and the ellipse area of the affected side was -0.425 (p<0.05). On the other hand, no significant correlations were found between the travel distance and ellipse area of the affected side when patients closed their eyes. Conclusion: Measurement of the COP using foot pressure scanner could evaluate objectively patients with chronic ankle instability, with measurements in patients with their eyes open being more significant. Based on the findings of this study, an analysis of the COP with the patients with their eyes open and standing on one foot may help determine the management strategy and assess the progress of the patients.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.39 no.2
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• pp.169-177
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• 2015

Because technology of the sintering process is highly advanced, the gerotor used in the internal gear pumps of vehicles has advantages for manufacturing complex profiles and obtaining durability and minimization. However, it has been necessary to continuously improve the flow rate and noise of internal gear pumps for better fuel efficiency. The existing rotor was designed using a translation algorithm. This caused a discontinuity of the rotor profile, which had adverse effects on the performance. In this study, to improve the discontinuity of the profile, a new design program using a rotation and translation algorithm was developed, and two types of combined multiple profiles (three-ellipses and ellipse 1-involute-ellipse 2) were generated. Then, the performances (flow, flow rate, specific sliding, and pressure angle) of these profiles were calculated. On the basis of the calculation results for the performances, optimal designs of the two types were carried out and verified by comparing their performances with those of the existing rotor profiles.

• Journal of the Korean Society of Propulsion Engineers
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• v.17 no.1
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• pp.1-8
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• 2013

A liquid-monopropellant hydrazine thruster has several outstanding advantages such as relatively-simple structure, long/stable propellant storability, clean exhaust products, and so on. Therefore hydrazine thruster has such a wide application as orbit and attitude control system (ACS) for space vehicles. A hydrazine thruster with the medium-level thrust to be used in the ACS of space launch vehicles (SLV) has been developed, and its ground firing test result is presented in terms of thrust, impulse bit, temperature, and chamber pressure. It is verified through the performance test that the response and repeatability of thrust are very excellent, and the thrust efficiencies compared to its ideal requirement are larger than 93%.

• Journal of the Korean Society for Nondestructive Testing
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• v.28 no.1
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• pp.64-69
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• 2008

In order to detect the internal defects which occur in welding parts of pressure vessel and structures, radiographic testing and ultrasonic testing is applied. However, because of the risks of radiation exposure and film processing, radiographic testing takes a relatively long time to verify the test results and it has affected in the production process. Typically, the manual ultrasonic testing is not easy to reproduce the result and it is highly dependent on the tester's skills. The TOFD technique, one of the automatic ultrasonic testings is spreading alternatively. This research describes the comparing test results by applying radiographic testing and TOFD technique to a mock-up specimen incruding the flaws. The TOFD technique will contribute to improve the objective reliability of the ultrasonic technique.