• Korea Journal of Hospital Management
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• v.26 no.2
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• pp.17-26
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• 2021

Purposes: This study aims to identify factors affecting dental university hospitals' profitability and understand recent their business condition. Methodology: Data from 2016 to 2019 was collected from financial statement, public open data in 8 dental university hospitals. For the study, multiple regression test with stepwise selection was applied. Findings: First of all, 9 out of 19 independent variables were selected by stepwise selection. As a result of multiple regression test with selected independent variables and the dependent variable(operating profit margin ratio), the factors affecting hospitals' profitability were the number of dental unit chair, hospital location, debt ratio, total capital turnover ratio, employment cost rate, material cost rate, management expense rate, the number of patient per a dentist. Practical Implication: To improve dental university hospitals' profitability, hospitals specifically analysis and manage their cost such as employment, material and management cost and seek effectiveness by managing the proper number of patient per a dentist.

• Nuclear Engineering and Technology
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• v.55 no.5
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• pp.1533-1540
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• 2023

Self-Powered Neutron Detectors(SPNDs) are used to calculate core power distributions, an essential factor in the safe operation of nuclear power plants. Some detectors may fail during normal operation, and signals from failed detectors are isolated from intact signals. The calculated detailed power distribution accuracy depends on the number of available detector signals. Failed detectors decrease the operating margin by enlarging the power distribution measurement error. Therefore, a thorough reconstruction of the failed detector signals is critical. This note suggests a compressive sensing based methodology that rationally reconstructs the readings of failed detectors. The methodology significantly improves reconstruction accuracy by sorting signals and removing high-frequency components from conventional compressive sensing methodology.

• The Journal of Korean Academy of Prosthodontics
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• v.49 no.1
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• pp.38-48
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• 2011

Purpose: Dentists suffer back, neck and shoulder pain during their careers due to bad operating posture. If dentists have a good operating posture ergonomically, there would be less pain and discomfort in the shoulder and back. Therefore, dentists should learn the Home position which enables dentists to approach a stable posture ergonomically. This study was to compare tooth preparation in the Home position and the Random position, and evaluate the clinical efficacy of the Home position. Materials and methods: Tooth preparation for fixed partial denture was performed on the maxillary left 2nd premolar and maxillary left 2nd molar at the two different operating positions were compared. The amount of occlusal reduction, marginal width, subgingival margin depth, and convergence angle were measured. A T-test was performed separately to compare the results of the Random position and the Home position. Results: 1. The amounts of average thickness of occlusal reduction on fossa were deficient to the ordered ones in the Random position and the Home position (P > .05). 2. The average subgingival margin depth of prepared margin on maxillary left 2nd premolar, maxillary left 2nd molar were excessive in the Random position than in the Home position. On the maxillary left 2nd premolar, there was no statistical difference in the Random position and the Home position except Distal midline, DL line angle, Lingual midline, ML line angle (P< .05). On the maxillary left 2nd molar, there was no statistical difference in the Random position and the Home position (P < .05). 3. Average convergence angle in the Random position and the Home position were excessive compared to the ordered angle. There was no statistical difference in the Random position and the Home position (P > .05). 4. Analysis of pearson correlation : In the Random position, the amounts of average thickness of occlusal reduction, the average subgingival margin depth of prepared margin, convergence angle were significantly associated with each other (P < .05). But in the Home position, they were not significantly associated with each other (P < .05). 5. The time needed for preparation in the Home position was faster or equal than that of the Random position as time went on. Conclusion: In conclusion, there were no significant differences between Home position and Random position in measures of occlusal reduction, marginal width, marginal depth, convergence angle. However, preparation time and incidence of damaging adjacent teeth were less in Home position than in Random position. Therefore, if trained properly, Home position which is more ergonomically stable can be adopted for clinical use.

• Journal of the Korean Data Analysis Society
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• v.20 no.6
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• pp.3037-3048
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• 2018

This study tried to test the result of recent study reporting that there is no the effect of cross-subsidization by applying it to the Korean banks. Besides, the study also did the research to test the previous study that diversification toward non-interest operating sector is related with the motivation of reduction of bank risk. Main results are as follows. First, there is the effect of cross-subsidization between non-interest operating sector and interest one. The higher non-interest profit to total asset is, the lower loan growth and provision to total loan are. Second, the effect of cross-subsidization is related with the fee revenue to operating revenue rather than the fiduciary revenue to operating revenue because high fee revenue results in shrinking the lending business. Third, diversification toward non-interest sector is associated with reducing risk, and risk is not increased when the high performance of non-interest sector is occurred. This evidence is not line with DeYoung, Torna (2013) arguing that non-interest operating activities lead to increasing risk. Finally, Korean banks have to expand the activities in non-interesting sector focusing on boosting fee revenue to increase the effect of cross-subsidization against the possibility of cutting net interest margin.

• Journal of the Microelectronics and Packaging Society
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• v.17 no.4
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• pp.73-76
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• 2010

A two-facet approach was used to investigate the parametric performance of functional high-speed DDR3 (Double Data Rate) DRAM (Dynamic Random Access Memory) die placed in different types of BGA (Ball Grid Array) packages: wire-bonded BGA (FBGA, Fine Ball Grid Array), flip-chip (FCBGA) and lead-bonded $microBGA^{(R)}$. In the first section, packaged live DDR3 die were tested using automatic test equipment using high-resolution shmoo plots. It was found that the best timing and voltage margin was obtained using the lead-bonded microBGA, followed by the wire-bonded FBGA with the FCBGA exhibiting the worst performance of the three types tested. In particular the flip-chip packaged devices exhibited reduced operating voltage margin. In the second part of this work a test system was designed and constructed to mimic the electrical environment of the data bus in a PC's CPU-Memory subsystem that used a single DIMM (Dual In Line Memory Module) socket in point-to-point and point-to-two-point configurations. The emulation system was used to examine signal integrity for system-level operation at speeds in excess of 6 Gb/pin/sec in order to assess the frequency extensibility of the signal-carrying path of the microBGA considered for future high-speed DRAM packaging. The analyzed signal path was driven from either end of the data bus by a GaAs laser driver capable of operation beyond 10 GHz. Eye diagrams were measured using a high speed sampling oscilloscope with a pulse generator providing a pseudo-random bit sequence stimulus for the laser drivers. The memory controller was emulated using a circuit implemented on a BGA interposer employing the laser driver while the active DRAM was modeled using the same type of laser driver mounted to the DIMM module. A custom silicon loading die was designed and fabricated and placed into the microBGA packages that were attached to an instrumented DIMM module. It was found that 6.6 Gb/sec/pin operation appears feasible in both point to point and point to two point configurations when the input capacitance is limited to 2pF.

• The KSFM Journal of Fluid Machinery
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• v.3 no.1 s.6
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• pp.43-50
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• 2000

Upgrade development of a high pressure ratio centrifugal compressor in marine engine turbochargers is presented. A new matched operating point at increased speed of rotation was determined through system cycle analysis using the exisitng test data of turbine performance. Under some severe restrictions for geometric parameters, the state-of-the-art methods of both aerodynamic design and CFD analysis were applied, in which only an impeller, a vaned diffusor and some part of casing wall were modified. Prototype hardware was fabricated and assembled for system performance tests. Excellent performance in pressure ratio and efficiency was obtained over whole speed region. Reduced surge and choke margin was, however, observed at design speed of rotation.

• Journal of Biomedical Engineering Research
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• v.32 no.1
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• pp.7-14
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• 2011

This study suggested an optimized algorithm for detecting the loss of balance(LOB) in the seated position. And the sensitivity analysis was performed in order to identify the role of each design variable in the algorithm. The LOB algorithm consisted of data processing of measured signals, an internal model of the central nervous system and a control error anomaly(CEA) detector. This study optimized design variables of a CEA detector to obtain improved values of the success rate(SR) of detecting the LOB and the margin time(MT) provided for preventing the falling. Nine healthy adult volunteers were involved in the experiments. All the subjects were asked to balance their body in a predescribed seated posture with the rear legs of a four-legged wooden chair. The ground reaction force from the right leg was measured from the force plate while the accelerations of the chair and the head were measured from a couple of piezoelectric accelerometers. The measured data were processed to predict the LOB using a detection algorithm. Variables S2, h2 and hd are related to the detector: S2 represents a data selecting window, h2 a time shift and hd an operating period of the LOB detection algorithm. S2 was varied from 0.1 to 10 sec with an increment of 0.1 sec, and both h2 and hd were varied from 0.01 to 1.0 sec with an increment of 0.01 sec. It was found that the SR and MT were increased by up to 9.7% and 0.497 sec comparing with the previously published case when the values of S2, h2 and hd were set to 4.5, 0.3 and 0.2 sec, respectively. Also the results of sensitivity analysis showed that S2 and h2 had considerable influence on the SR while these variables were not so sensitive to the MT.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.20 no.4
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• pp.819-825
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• 2016

In this paper, a phase locked loop structure with parallel dual loop which have a different bandwidth has been proposed. The bandwidths depending on transfer functions are obtained through dual loops. Two different bandwidths of each loop are used to suppress noise on the operating frequency range. The proposed phase locked loop has two different voltage controlled oscillator gains to control two different wide and narrow loop filters. Furthermore, it has the locking status indicator to achieve an accurate locking condition. The phase margin of $58.2^{\circ}$ for wide loop and $49.4^{\circ}$ for narrow loop is designed for stable operation and the phase margin of $45^{\circ}$ is maintained during both loops work together. It has been designed with a 1.8V 0.18um complementary metal oxide semiconductor (CMOS) process. The simulation results show that the proposed phase locked loop works stably and generates a target frequency.

• Journal of Electrical Engineering and Technology
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• v.5 no.3
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• pp.353-362
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• 2010

This paper presents a centralized control algorithm for power system performance in the Korean power system using Flexible AC Transmission Systems (FACTS) devices. The algorithm is applied to the Korean power system throughout the metropolitan area in order to alleviate inherent stability problems, especially concerns with voltage stability. Generally, control strategies are divided into local and centralized control. This paper is concerned with a centralized control strategy in terms of the global system. In this research, input data of the proposed algorithm and network data are obtained from the SCADA/EMS system. Using the full system model, the centralized controller monitors the system condition and decides the operating point according to the control objectives that are, in turn, dependent on system conditions. To overcome voltage collapse problems, load-shedding is currently applied in the Korean power system. In this study, the application of the coordination between FACTS and switch capacitor (SC) can restore the solvability without load shedding or guarantee the FV margin when the margin is insufficient. Optimal Power Flow (OPF) algorithm, for which the objective function is loss minimization, is used in a stable case. The results illustrate examples of the proposed algorithm using SCADA/EMS data of the Korean power system in 2007.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.37C no.10
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• pp.965-976
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• 2012

Multi-Platform Image and Intelligence Common data link(MPI-CDL) systems are designed to transmit the imaginary and signal intelligence data at an aeronautical to ground line of sight(LOS) link. This paper proposes a method to predict a link availability and analyzes the required link margin to satisfy a given link availability for MPI-CDL systems. To estimate a link availability the proposed method applies the conditional probability so that both a rain attenuation and a multipath fading are considered simultaneously. Link margins to meet the link availability for MPI-CDL systems are calculated according to an operating environment including frequencies, flight altitudes and transmission ranges. The required link margins for actual unmanned air vehicle systems are also given by simulation results.