• Journal of Power Electronics
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• v.16 no.5
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• pp.1689-1697
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• 2016

Continuous conduction mode (CCM) boost converters are commonly used in home appliances and various industries because of their simple topology and low input current ripples. However, these converters suffer from several disadvantages, such as hard switching of the active switch and reverse recovery problems of the output diode. These disadvantages increase voltage stresses across the switch and output diode and thus contribute to switching losses and electromagnetic interference. A new topology is presented in this work to improve the switching characteristics of CCM boost converters. Zero-current turn-on and zero-voltage turn-off are achieved for the active switches. The reverse-recovery current is reduced by soft turning-off the output diode. In addition, an input current sensorless control is applied to the proposed topology by pre-calculating the duty cycles of the active switches. Power factor correction is thus achieved with less effort than that required in the traditional method. Simulation and experimental results verify the soft-switching characteristics of the proposed topology and the effectiveness of the proposed input current sensorless control.

• ETRI Journal
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• v.33 no.5
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• pp.752-758
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• 2011

This paper presents a clock and data recovery circuit that supports dual data rates of 5.4 Gbps and 3.24 Gbps for DisplayPort v1.2 sink device. A quarter-rate linear phase detector (PD) is used in order to mitigate high speed circuit design effort. The proposed linear PD results in better jitter performance by increasing up and down pulse widths of the PD and removes dead-zone problem of charge pump circuit. A voltage-controlled oscillator is designed with a 'Mode' switching control for frequency selection. The measured RMS jitter of recovered clock signal is 2.92 ps, and the peak-to-peak jitter is 24.89 ps under $2^{31}-1$ bit-long pseudo-random bit sequence at the bitrate of 5.4 Gbps. The chip area is 1.0 mm${\times}$1.3 mm, and the power consumption is 117 mW from a 1.8 V supply using 0.18 ${\mu}m$ CMOS process.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.23 no.2
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• pp.120-125
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• 2011

As an effort to secure economically viable heat recovery units, innovative fin shapes for industrial boilers are studied for better performance. In the present study a numerical modeling for the analysis of heat exchanger performance is conducted using a commercial software, ANSYS CFX and the results are compared with the experimental data. Out of several candidate fin shapes curved wavy fin is selected for the present study. Both numerical and experimental data are directly compared for heat transfer rate and pressure drop with the assumed constant surface temperature of $60^{\circ}C$. Exhaust gas is obtained from a test apparatus which supplies variable flow rates. The numerical results show reasonable agreements with the experimental data within 10% in terms of both total heat transfer and pressure loss.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.9 no.2
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• pp.620-636
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• 2015

Survivability is a necessary property of network system in disturbed environment. Recovery ability is a key actor of survivability. This paper concludes network survivability into a novel composite metric, i.e. Network Recovery Degree (NRD). In order to measure this metric in quantity, a concept of Source-Destination Pair (SD Pair), is created to abstract end-to-end activity based on end nodes in network, and the quality of SD Pair is also used to describe network performance, such as connectivity, quality of service, link degree, and so on. After that, a Survivability Test method in large scale Network based on SD pairs, called STNSD, is provided. How to select SD Pairs effectively in large scale network is also provided. We set up simulation environment to validate the test method in a severe destroy scenario and evaluate the method scalability in different large scale network scenarios. Experiment and analysis shows that the metric NRD correctly reflects the effort of different survivability strategy, and the proposed test method STNSD has good scalability and can be used to test and evaluate quantitative survivability in large scale network.

• Journal of Preventive Medicine and Public Health
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• v.5 no.1
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• pp.17-23
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• 1972

Carbon Monoxide poisoning is one of the most serious Public health problems in Korea. The incidence rate. officially reported has been known to be the highest in the world. This high incidence is mainly due to the wide prevalence of anthracite coal briquette as the domestic fuel for unique Korean heating system called 'ondol,' The coal briquette gas contains around 3-5% of Carbon Monoxide. A nation-wide effort to eliminate or reduce this serious hazards has produced little effect and the most hospitals are offering very ineffective measures such as oxygen inhalation through nasal catheter. Author has believed that this preventable accident should be approached by the secondary preventive measure because of our socio-economic status do not allow us optimistic results from primary preventive measure as far as the problem of CO poisoning is concerned. Author has treated 466 patients during 30 months period by Hyperbaric Oxygenation at Seoul National University Hospital. The results found are as follows. 1. Female has a higher incidence rate than male and the age group between 15-29 years showed highest incidence. 2. The recovery time depends on the time when the patients arrived at hospital. Earlier the arrival time, shorter the recovery time. 3. Some objective signs are representing typical physiological response to tissue hypoxia. 4. Therapeutic effectiveness of Hyperbaric Oxypenation is confirmed by such indices as recovery rate, Admission rate and average stay in hospital. Futher, these results are cocordant with other reports on the clinical value of Hyperbaric Oxygenation in the treatment of CO poisoning.

• Journal of the Korea institute for structural maintenance and inspection
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• v.20 no.3
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• pp.42-48
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• 2016

Extensive research effort has been made during the last decade to utilize wireless smart sensors for evaluating and monitoring structural integrity of civil engineering structures. The wireless smart sensor commonly has sensing and embedded computation capabilities as well as wireless communication that provide strong potential to overcome shortcomings of traditional wired sensor systems such as high equipment and installation cost. However, sensor malfunctioning particularly in case of long-term monitoring and unreliable wireless communication in harsh environment are the critical issues that should be properly tackled for a wider adoption of wireless smart sensors in practice. This study presents a wireless smart sensor network(WSSN) that can estimate unmeasured responses for the purpose of data recovery at unresponsive sensor nodes. A software program that runs on WSSN is developed to estimate the unmeasured responses from the measured using the Kalman filter. The performance of the developed network software is experimentally verified by estimating unmeasured acceleration responses using a simply-supported beam.

• Korea Journal of Hospital Management
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• v.10 no.2
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• pp.1-25
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• 2005

This study purports to investigate the determinants of patient satisfaction and intent to revisit at national university hospitals in Korea. A total of 8 independent variables for outpatients, 9 independent variables for inpatients, and an intervening variable of overall patient satisfaction were selected through literature review. The independent variables for outpatients contain the level of satisfaction with physicians, nurses, ancillary staff, administrative procedure, medical cost, physical environment, facility convenience. and health recovery. With regard to the independent variables for inpatients, the quality of ward services was added to those of outpatients. Each variable contains 3 to 8 items measuring the level of satisfaction with various aspects of the variable. The sample used in this study consisted of 879 outpatients and 821 inpatients. Data were collected with interview survey and analyzed using path analysis. The major findings of the study are as follows: 1) The following variables have significantly positive effect on the intent to revisit of outpatients: health recovery, overall satisfaction, satisfaction with physicians, and ancillary staff. 2) The following variables have significantly positive effect on the intent to revisit of inpatients: health recovery, satisfaction with nurses and physicians, overall satisfaction, and administrative procedure. 3) The following variables of admission procedure, satisfaction with ancillary staff, facility convenience, quality of ward services were found to have significantly positive effect only on the level of overall satisfaction, even though they do not have significant total effect on the intent to revisit. The results of the study indicate that national university hospitals in Korea should make an effort to improve the satisfactory level of patients with clinical outcome, services provided by physicians, nurses, and ancillary staff, and the quality of administrative procedure for enhancing the intent to revisit of patients.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.28 no.9B
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• pp.760-773
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• 2003

The Internet is evolving from best-effort service toward an integrated or differentiated service framework with quality-of-service (QoS) assurances that are required for new multimedia service applications. Given this increasing demand for high bandwidth Internet with QoS assurances in the coming years, an IP/MPLS-based control plane combined. with a wavelength-routed dense-wavelength division multiplexing (DWDM) optical network is seen as a very promising approach for the realization of future re-configurable transport networks. This paper proposes a differentiated lambda establishment process for QoS guarantees based on the differentiated MPLS service (DMS) model. According to the QoS characteristics of wavelength in optical links and the type of used Optical Cross-Connect (OXC) nodes in DWDM next generation optical Internet backbone network, a differentiated wavelength assignment strategy that considers QoS recovery capability is also suggested.

• International Commerce and Information Review
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• v.15 no.1
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• pp.3-34
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• 2013

This research, which was experimented by dividing tangible and intangible products, established the influence that affects recovery for consumers' complaint behavior and behavioral intention as per each different compensation program. In Experiment 1, the consumers, who experienced complaint behavior owing to company's mistake, have preferably recovered through the compensation program offered by the company. However, there was a significant difference in preference recovery between products that caused complaint behavior. According to the study result, the more clear preference recovery was shown in the case of purchasing laptop than the case of dining in family restaurant. Additionally, the consumers' emotion recovery was possible through compensation.; There was a emotion recovery disparity depending on product type between purchasing laptop case and dining in family restaurant case. The consumers, who experienced complaints, were only able to recover their preference, emotion, and behavioral intention through compensation of which recovery was greater in tangible product case than ordinary service. Meanwhile, there was no distinct difference between recovery compensation types even though the products were identical-type ones whereas it appeared that such tangible product which showed greater purchasing effort as laptop computer was more effective in stimulating emotion response. In Experiment 2, the purpose was to find out the difference between complaint behavior and its recovery process shown after purchase by Korean and Japanese college students, who have different consumer purchasing habits. The both consumers of the two countries, who experienced complaint behavior, demonstrated precise difference in preference recovery while the emotion and behavioral intention exhibited no disparity between the two consumer groups. In this experiment, it was learned that Korean college students were show-off purchase type consumers while on the other hand, the Japanese college students were famous product purchase type consumers. Thus, there was a clear difference in laptop computer purchase process and post-purchase evaluation between these two groups. In particular, the Korean college students had quicker preference recovery through compensation than the Japanese college students on account of their tendency to be consciousness of others. Nevertheless, there was no difference between the emotion recovery and re-purchase recovery and therefore, the compensation program for complaints was proven to affect the emotion and behavioral intention.

• 제어로봇시스템학회:학술대회논문집
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• 2003.10a
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• pp.1629-1632
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• 2003

A technique is presented for generating a compound human motion from its primitive motions obtained by a motion capture system. Some human fundamental motions are modeled in a 3-D way and registered as primitive motions. Because the factorization method is used for the motion capture, calibration of video cameras and connection of the motion in the direction of time is both unnecessary. Employing these motions, various compound human motions are generated by connecting the motions after having applied rotation and parallel transformation to them. Linear interpolation is done at the discontinuous boundary between primitive motions and smooth connection is achieved. Experimental results show satisfactory performance of the proposed technique. The technique may contribute to producing various complicated human motions without much effort using a strict motion capture system.