• Journal of Institute of Control, Robotics and Systems
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• v.18 no.9
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• pp.871-877
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• 2012

An error analysis of PPP (Precise Point Positioning) using IF (Ionosphere Free) combination is given in this paper. It is shown that the performance of the ordinary model with positions, clock bias, integer ambiguities and ionosphere delay as unknowns is equivalent to that of an ionosphere difference combination where ionosphere delay is cancelled out. Furthermore, it is shown that IF combination is an ionosphere difference combination but not unique. It is also proved that all difference models show same performances. The error analysis evaluated with a hardware simulator and real measurements show that the ionosphere delay is effectively eliminated by IF combination or equivalently by the ionosphere difference combination. However, if bias errors such as troposphere, clock bias or multipath are included in the measurements, the performance of the IF combination is degraded because the bias errors are amplified by the ionosphere difference operation.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.11 no.1
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• pp.81-90
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• 1999

The performance evaluation technique of a heat exchanger is described by using a transient response analysis for the determination of an average heat transfer coefficient. The model using a finite difference method can accommodate arbitrary inlet fluid temperature as well as longitudinal conduction. Temperature histories are obtained from the experiments at the inlet and outlet of test core. Heat transfer coefficient and friction factor of the plate array are obtained in short times using the data reduction program of transient response analysis in the single-blow method. The results agree very well with theoretical results. It is shown that the rms deviations are very small and the performance evaluation technique gives rapid and accurate results.

• Korean Journal of Community Nutrition
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• v.11 no.1
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• pp.116-123
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• 2006

The purposes of this study were to develop a tool for assessing internal branding performance and to identify the difference of internal branding performance between local and international hotels. The internal branding performance measure was developed through literature studies and face-to-face in-depth interviews with managers in various departments of 5 deluxe hotels. The questionnaires were distributed to 460 employees in food and beverage departments of 11 deluxe hotels in Seoul, and a total of 398 questionnaires were used for analysis ($86.5\%$). The statistical analyses were completed using SPSS Win (12.0) for descriptive analysis, reliability analysis and t-test, and AMOS (5.0) for confirmatory factor analysis. The results of this study showed that the measure developed in this study was reliable and valid for assessing internal branding performances of hotels. In addition, the internal branding performances of hotels were high at understanding of brand dimensions and relatively low at work and organizational culture and human resource management dimensions, and local hotels showed lower levels of performance than international hotels at the dimensions of work and organizational culture (t = -3.801, P < 0.001) and human resource management(t = -5.397, p < 0.001). In conclusion, it is considered that a strong internal branding strategy should be established for successful brand management, and the practical measure for internal branding performance would be a key factor.

• Proceedings of the KIEE Conference
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• 2001.07a
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• pp.249-251
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• 2001

This paper presents performance analysis on a low pass filter of a CT saturation detecting algorithm using difference. At the instants of beginning/end of saturation, the shapes of the secondary current are changed significantly though secondary currents are continuous. At the instants, the second-order or third-order difference of the secondary current has big values because of discontinuity of the first order difference. Thus, the third difference of the current is used to detect the beginning/end of CT saturation. An antialiasing low pass filter removes high frequency components and causes phase lag. A CT saturation detecting algorithm using difference of CT secondary currents is affected by the low pass filter. The algorithm is tested with cutoff frequencies of the filter for the two sampling rates of 64[S/C] and 32 [S/C]. The results of various test cases indicate satisfactory performance of the algorithm.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.29 no.6 s.237
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• pp.722-729
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• 2005

Design analysis of the solid oxide fuel cell and gas turbine combined power system is performed considering different methods for preheating cell inlet air. The purpose of air preheating is to keep the temperature difference between cell inlet and outlet within a practical design range thus to reduce thermal stress inside the cell. Three different methods considered are (1) adopting a burner in front of the cell, (2) adopting a preheater (heat transfer from the main combustor) in front of the cell and (3) using recirculation of the cathode exit gas. For each configuration, analyses are carried out for two values of allowable maximum cell temperature difference. Performance characteristics of all cases are compared and design limitations are discussed. Relaxation of the cell temperature difference (larger difference) is proved to ensure higher efficiency. Recirculation of the cathode exit gas exhibits better performance than other methods and this advantage becomes more prominent as the constraint of the cell temperature difference becomes more severe (smaller temperature difference).

• The Korean Journal of Health Service Management
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• v.6 no.2
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• pp.133-140
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• 2012

This research analyzes on the difference of the management performance in public health care institution, especially between provincial medical center and national university hospital. The meaningful results of this study as follow. First of all, management performance was showed the loss in both of provincial medical center and national university hospital. but national university hospital is superior to provincial medical center in management performance. Secondly, It is noteworthy that social working expenses have influence on national university hospital. Finally, It shows that personnel expenses are the most important factor in the management performance in public health care institution. We hope that these results will be useful in the performance management of public health care institution.

• Journal of Korea Port Economic Association
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• v.30 no.3
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• pp.187-207
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• 2014

The purpose of this paper is to examine the business performance difference based on the ownership structure type in the aspect of profitability and stability. In order to conduct this analysis in two aspects, the ship financial institutions have been classified into two groups: state-owned banks and private-owned banks. First of all, the difference of ROE and ROA between private and public ship financial institutions is statistically significant, but no difference has been shown in terms of stability measured through BIS capital adequacy ratio. Second, to test the business performance difference according to the ownership structure types before and after the global financial crisis, we examined the outcome difference in the ship financial institutions in terms of profitability and stability. However, in the event that the analysis was conducted with public and private financial institutions, the business outcome difference before and after the global financial crisis has been shown in the sector of private financial institutions, but has not been shown in the sector of public financial institutions. It is meaningful that this study is the first work which examined the difference of the operating performance by the ownership structure types of ship financial institutions. However, it is noted that small sample for this empirical study is a limitation of this thesis.

• KIEAE Journal
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• v.15 no.2
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• pp.109-115
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• 2015

Purpose: The importance of building airtightness is increased as the demand and expectation of building energy efficiency is growing. Previous research only focused on airtightness of building openings only to improve building airtightness. However, the analysis of difference of airtightness performance according to the characteristic of building structure has not been performed. Therefore, this study analyzed the difference of airtightness performance according to building structural characteristics in a number of ways. Method: Airtightness that are classified as rigid-frame type or wall type are measured and analyzed the difference of airtightness performance between rigid frame type apartments and wall type apartments. This study calculated the heating energy demand and quantitatively analysis using ISO 13790. Futhermore, this study compared research trend of domestic airtightness performance with airtightness standards of the developed countries based on the field measurement. Result: Airtight performance of wall type is better than rigid frame type in terms of energy saving. The difference of heating energy demand between wall type and rigid frame type was $8.14kWh/m^2yr$.

• Journal of Korea Water Resources Association
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• v.55 no.5
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• pp.357-370
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• 2022

This study aims to analyze the differences in performance according to various operation methods (direct management, public consignment, and private agency) of public sewage treatment facilities and derive the most efficient and high level of sewage treatment services to the public based on the research results. To this end, economic performance indicators (sewage treatment cost, sewerage rate) and social performance indicators (water quality, number of civil complaints) were selected, and cross-sectional analysis and longitudinal analysis were used to verify the difference between the averages of three or more groups through one-way ANOVA. As a result of the analysis, cross-sectional analysis, there was no difference in economic performance dimension according to the operating method, but in terms of social performance dimension, it was found that there was a difference according to the operating method. In the case of water quality indicators, the results were superior to those directly managed by public consignment and private agencies in the number of civil complaints. In the longitudinal analysis examining the improvement of performance indicators, there was no significant difference by operation method in most performance indicators. In order to improve the efficiency of public services and improve the service level, various approaches suitable for the characteristics of each service are required in addition to the logic of public consignment or introduction of private agency. In the future, when local governments promote public consignment or private agency, it is necessary to understand and promote the nature of the service, the specificity of each local government, and the needs of service users.

• Journal of Communications and Networks
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• v.14 no.5
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• pp.533-539
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• 2012

The performance analysis of wireless geolocation in a non-line-of-sight (NLOS) environment is a very important issue. Since Cramer-Rao lower bound (CRLB) determines the physical impossibility of the variance of an unbiased estimator being less than the bound, many studies presented the performance analysis in terms of CRLB. Several CRLBs for time-of-arrival (TOA), pseudo-range TOA, angle-of-arrival (AOA), and signal strength (SS) based positioning methods have been derived for NLOS environment. However, the performance analysis of time difference of arrival (TDOA) and TDOA/SS based geolocation techniques in a NLOS environment is still an opening issue. This paper derives the CRLBs of TDOA and TDOA/SS based positioning methods for NLOS environment. In addition, theoretical analysis proves that the derived CRLB for TDOA is the same as that of pseudo-range TOA and the TDOA/SS scheme has a lower CRLB than the TDOA (or SS) scheme.