• Proceedings of the KSME Conference
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• 2001.06d
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• pp.201-207
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• 2001

We modeled the liquid film dryout(LFD) process for both tube and annulus which have uniformly heated vertical channels. We set phenomenological initial conditions in the model. The initial void fraction on the onset of the annular flow location is derived from the physical chum-to-annular flow criterion with the help of the drift-flux-model. The initial thermodynamic-equilibrium-quality is calculated by iteration with the flow quality to find the onset of the annular-flow location. Present model tends to predict very well at the lower exit quality but under-estimates at the higher exit quality. We found that the prediction error of the present model is gradually bigger as the inlet subcooling approaches near the saturation. We obtained excellent results for both tube and annulus channels as the mean of 0.97 and root-mean-square error of 11% for the number of 3883 experimental data on tubes, and of 0.96 and of 12% for 593 on annuli. The present model extended the applicable range to the relatively low exit quality region than previous LFD models.

• Knowledge Management Research
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• v.10 no.3
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• pp.1-16
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• 2009

Recent trends in business are characterized by recognition of the importance of knowledge assets. Especially, this phenomenon is receiving more momentum as our society goes digital rapidly. The concept of Knowledge Management has long been used as an effective way of restructuring the management process of a firm. In literature regarding knowledge management, a number of successful cases were reported, where knowledge-based management activities could dramatically enhance a firm's strategic performance for years. However, there exists very little research investigating the effect of knowledge management on corporate competitiveness. Researchers as well as practitioners need more rigorous results about such issues, especially how much the knowledge management strategic initiatives may have an influence on the firm's competitiveness. In this sense, we need an empirical study adopting statistical approaches due to the existence of abundant knowledge management case studies. To fill this research void, this study proposes a research model testing whether knowledge management activities could improve corporate competitiveness. We collected 321 valid questionnaires from participants in knowledge management activities in the tourism industry and applied a structural equation model. Empirical results showed that knowledge management activities have a positive impact on knowledge management efficiency and finally corporate competitiveness. We hope that this study will shed light on further rigorous studies considering tourism industry as a major strategic activity.

• The Transactions of the Korean Institute of Electrical Engineers C
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• v.55 no.4
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• pp.178-182
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• 2006

Five model coils of 6.6 kV motor were manufactured with several defects. These stator coils have artificial defects such as void of groundwall insulation, removal of semi-conductive coating and damage of strand insulation. Epoxy-mica coupler(80 pF) was connected to five model coil terminals. The voltage applied to the coils was 3.81 kV, 4.76 kV, 6.0 kV and 6.6 kV, respectively. Partial discharge(PD) tests performed in the laboratory and shield room. Digital PD detector(PDD) and turbine generator analyzer(TGA) were used to measure PD activity. TGA summarizes each plot with two quantities such as the normalized quantity number(NQN) and the peak PD magnitude(Qm). The PD levels in pC were measured with PDD. PD patterns of model coils were indicated the internal and slot discharges. PD patterns are consistent with the result of measurement using PDD and TGA instruments. AC breakdown test was performed on five model coils in order to confirm the result of PD measurements. All the failures were located in a line-end coil at the exit from the core slot.

• Journal of the Korean Geotechnical Society
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• v.20 no.5
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• pp.27-35
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• 2004

The goal of this study is to investigate the feasibility of the reference state approach in determining the generalized soil-water characteristic curve that is essential fur characterization of unsaturated soil behavior. The soil-water characteristic curves are obtained from a number of specimens of fine-grained residual soils compacted with different void ratios. Based on the experimental test results, the feasibility of using the liquid limit state as the reference state for predicting the soil-water characteristic curve is verified. Finally, through the regression analysis of experimental data using the equation of Fredlund and Xing (1994), a reliable method is proposed to predict the generalized soil-water characteristic curve of fine-grained residual soils using the liquid limit state as the reference state.

• Geomechanics and Engineering
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• v.31 no.6
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• pp.623-635
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• 2022

This paper presents the re-evaluation of existing piezocone penetration test (CPTu)-based shear wave velocity (V_s) equations through their application into well-documented data obtained at nine sites in six countries. The re-evaluation indicates that the existing equations are appropriate to use for any specific soil, but not for various types of clays. Existing equations were adjusted to suit all nine clays and show that the correlations between the measured and predicted V_s values tend to improve with an increasing number of parameters in the equations. An adjusted equation, which comprises a CPTu parameter and two soil properties (i.e., effective overburden stress and void ratio) with the best correlation, can be converted into a CPTu-based equation that has two CPTu parameters and depth by considering the effect of soil cementation. Then, the developed equation was verified by application to each of the nine soils and nine other worldwide clays, in which the predicted V_s values are comparable with the measured and the stochastically simulated values. Accordingly, the newly developed CPTu-based equation, which is a time-saving and economical method and can estimate V_s indirectly for any type of naturally deposited clay, is recommended for practical applications.

• Korean Management Science Review
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• v.24 no.2
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• pp.157-176
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• 2007

Fuzzy cognitive map(FCM) has long been used as an effective way of constructing the human's decision making process explicitly. By taking advantage of this feature, FCM has been extensively used in providing what-if solutions to a wide variety of business decision making problems. In contrast, the goal-seeking analysis mechanism by using the FCM is rarely observed in literature, which remains a research void in the fields of FCM. In this sense, this study proposes a new type of the FCM-based goal-seeking analysis which is based on utilizing the genetic algorithm. Its main recipe lies in the fact that the what-if analysis as well as goal-seeking analysis are enabled very effectively by incorporating the genetic algorithm into the FCM-driven inference process. To prove the empirical validity of the proposed approach, valid questionnaires were gathered from a number of experts on software sales, and analyzed statistically. Results showed that the proposed approach is robust and significant.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.14 no.4
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• pp.77-82
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• 2000

This paper describes the self healing characteristics of a metalized polypropylene film(MPPF) by voids under a.c condition. PDIVs were increased with the number of pre-self healing due to void defects, and several pre-self healing events took place at lower voltage than the critical breakdown voltage of a PPF. Self healing mainly occurred at pin tips, wrinkle sides, and cross points of wrinkles, and the main self healing voltage was increased with PPF thickness. The burn out area at self healing was increased with the applied voltage, and the peak currents in a grounding conductor at self healing was also increased with the applied voltage.

• The Journal of Information Systems
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• v.18 no.3
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• pp.27-46
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• 2009

Korean society frenzy about ubiquitous computing is in a rapid change into so called 'Nomadic' information environment. In many previous studies, a number of intrinsic and extrinsic motivation factors were empirically found to affect users' continuance to use mobile hand-held devices. However, the role of device attachment, a new intrinsic motivation factor with which users are known to care about their own mobile devices personally, in determining users' post-adoption behavior was not explored yet to the full scale. To fill the research void like this, this study proposes a new research model in which device attachment as well as perceived value are positively linked to satisfaction and continuance to use. The statistical results obtained by applying PLS to the valid 137 questionnaires showed that the device attachment has stronger positive influence on satisfaction and continuance to use than the perceived value. Therefore, a practical implication is suggested thai the mobile devices need 10 be designed in a way of arousing users' device attachment more strongly.

• Journal of the Korean Geosynthetics Society
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• v.9 no.4
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• pp.39-45
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• 2010

The effects of non-woven geotextiles on mechanical behavior of sand were investigated. A comprehensive series of triaxial compression tests were performed for these investigation on unreinforced and reinforced sand with geotextiles. The Joomunjin standard sand was used and non-woven geotextiles were included into sand specimen with three layers. The inclusion of non-woven geotextile reinforcement into sand increased the peak strength of sand significantly and the reinforced samples exhibited a greater axial strain at failure. Also the effect on number of reinforcement layers was studied and found as increasing the number of reinforcement layers resulting in more ductility by clogging developed in the shear band within the specimens. It was also found that the tendency of samples to dilate is restricted by non-woven geotextile inclusion. The effect of nunber of reinforcement layer increasing is just same to the effect of decreasing void ratio of sand in this case.

• Solar Energy
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• v.12 no.3
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• pp.28-36
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• 1992

The performance of a latent heat storage system using a thermosyphon as the heat transfer device between the heat source and the phase change material was investigated experimentally. In order to increase the effective conductivity of the phase change material, layers of copper wire mesh were immersed in the paraffin wax(Sunoco P-116) in such a way that they also may be considered as fins of the thermosyphon. The important results are as follows : (1) The void space of the wire mesh allowed the convection to occur, thus enhanced the performance of the system : (2) The increase of the number of layer of wire mesh increased the conduction heat transfer. However, it also had adverse effect of subduing convective motion of liquid wax : and (3) Overall heat transfer coefficient and thermosyphon conductance increased with the increase of the number of layer of wire mesh, whereas the heat transfer coefficient between the thermosyphon and the wax decreased.