• Journal of Korea Society of Industrial Information Systems
• /
• v.17 no.2
• /
• pp.19-27
• /
• 2012

In railway tunnel environment, the reliability of a high-data-rate and real-time train-to-wayside communication should be maintained especially when high-speed train moves along the track. In China and Europe, the communication frequency around 900 MHz is widely used for railway applications. At this carrier frequency band, both of the solutions based on continuously laid leaky coaxial cable (LCX) and discretely installed base-station antennas (BSAs), are applied in tunnel radio coverage. Many available works have concentrated on the radio-wave propagation in tunnels by different kinds of prediction models. Most of them solve this problem as natural propagation in a relatively large hollow waveguide, by neglecting the transmitting/receiving (Tx/Rx) components. However, within such confined areas like railway tunnels especially loaded with train, the complex communication environment becomes an important factor that would affect the quality of the signal transmission. This paper will apply a full-wave numerical method to this case, for considering the BSA or LCX, train antennas and their interacted environments, such as the locomotive body, overhead line for power supply, locomotive pantograph, steel rails, ballastless track, tunnel walls, etc.. Involving finite-difference time-domain (FDTD) method and uni-axial anisotropic perfectly matched layer (UPML) technique, the entire wireless RF downlinks of BSA and LCX to tunnel space to train antenna are precisely modeled (so-called integrative modeling technique, IMT). When exciting the BSA and LCX separately, the field distributions of some cross-sections in a rectangular tunnel are presented. It can be found that the influence of the locomotive body and other tunnel environments is very significant. The field coverage on the locomotive roof plane where the train antennas mounted, seems more homogenous when the side-laying position of the BSA or LCX is much higher. Also, much smoother field coverage solution is achieved by choosing LCX for its characteristic of more homogenous electromagnetic wave radiation.

• Asian Pacific Journal of Cancer Prevention
• /
• v.13 no.4
• /
• pp.1675-1682
• /
• 2012

Aim: The study aim was to determine the frequency with which women decline clinicians' treatment recommendations and variations in this frequency by age, cancer and service descriptors. Design: The study included 36,775 women diagnosed with early invasive breast cancer in 1998-2005 and attending Australian and New Zealand breast surgeons. Rate ratios for declining treatment were examined by descriptor, using bilateral and multiple logistic regression analyses. Proportional hazards regression was used in exploratory analyses of associations with breast cancer death. Results: 3.4% of women declined a recommended treatment of some type, ranging from 2.6% for women under 40 years to 5.8% for those aged 80 years or more, and with parallel increases by age presenting for declining radiotherapy (p<0.001) and axillary surgery (p=0.006). Multiple regression confirmed that common predictors of declining various treatments included low surgeon case load, treatment outside major city centres, and older age. Histological features suggesting a favourable prognosis were often predictive of declining various treatments, although reverse findings also applied with women with positive nodal status being more likely to decline a mastectomy and those with larger tumours more likely to decline chemotherapy. While survival analyses lacked statistical power due to small numbers, higher risks of breast cancer death were suggested, after adjusting for age and conventional clinical risk factors, (1) for women not receiving breast surgery for unstated reasons (RR=2.29; p<0.001); and (2) although not approaching statistical significance $p{\geq}0.200$), for women declining radiotherapy (RR=1.22), a systemic therapy (RR1.11), and more specifically, chemotherapy (RR=1.41). Conclusions: Women have the right to choose their treatments but reasons for declining recommendations require further study to ensure that choices are well informed and clinical outcomes are optimized.

• Journal of Korean society of Dental Hygiene
• /
• v.15 no.4
• /
• pp.565-574
• /
• 2015

Objectives: The purpose of the study is to investigate the oral health of the elderly people receiving nursing care and home care services in Chungnam. Methods: The subjects were 350 elderly people receiving 21 nursing care and home care services in Chungnam. The direct interview with the elderly people and oral examination was carried out from July, 2012 to December, 2013 after explanation fo the purpose of the study. The subjects consisted of 178 elderly people receiving nursing care services and 172 elderly people receiving home care services. Except incomplete answers, 315 data were analyzed. The questionnaire consisted of general characteristics of the subjects, characteristics by facility, oral condition, oral care behavior, correlation by factors on oral health, influencing factor on dental caries, influencing factor on periodontal disease, and influencing factor on elasticity of gingival muscle. Data were analyzed by frequency analysis, chi-square test, and multiple regression analysis using SPSS 21.0 program. Results: Multivariate analysis of influencing factors on oral health revealed that the elderly people with low education level tended to have higher incidence rate of dental caries. The influencing factors on oral health were the elasticity of gingival muscle, periodontal disease, educational level, and economic level. (p<0.05). The explanation power was 26.2%. Conclusions: Oral Health Promotion should be obligatorily established as one of the medical system and medical fee system to promote oral health condition for the aged.

• Journal of Korean society of Dental Hygiene
• /
• v.15 no.4
• /
• pp.695-703
• /
• 2015

Objectives: The purpose of the study is to investigate the relationship between dental fear and subjective oral health-related quality of life. Methods: A self-reported questionnaire was filled out by 320 subjects in Seoul and Gyeonggido from June to August, 2014 after permission from Institutional Review Board (IRB). Except incomplete 9 copies, 311 data were analyzed using SPSS WIN 19.0 program. The questionnaire consisted of five questions of the general characteristics of the subjects, twelve questions of oral health related quality of life, eighteen questions of dental fear, and one question of awareness toward subjective health status. Results: The explanation power of subjective oral health-related quality of life on dental fear was 26.2 percent. As the subjective oral health-related quality of life increased by 1 point, the dental fear decreased at the rate of 0.645 (p<0.001). Conclusions: Higher subjective oral health-related quality of life will diminish the dental fear. Regular dental checkups and preventive treatment are very important to enhance the oral health-related quality of life in those who visit the dental clinic.

• Journal of the Institute of Electronics Engineers of Korea SD
• /
• v.45 no.5
• /
• pp.58-64
• /
• 2008

A 6Gbps 1:2 demultiplexer(DEMUX) IC using $0.18{\mu}m$ CMOS was designed and fabricated. For high speed performance current mode logic(CML) flipflop was used and inductive peaking technology was used so as to obtain higher speed than conventional Current mode logic flipflop. On-chip spiral inductor was designed to maximize the inductive peaking effect using stack structure. Total twelve inductors of $100{\mu}m^2$ area increase was used. The measurement was processed on wafer and 1:2 demultiplexer with and without micro stacked spiral inductors were compared. For 6Gbps data rate measurement, eye width was improved 7.27% and Jitter was improved 43% respectively. Power consumption was 76.8mW and eye height was 180mV at 6 Gbps

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
• /
• v.29 no.7
• /
• pp.429-434
• /
• 2016

This paper deals with the characteristics of partial discharge (PD) for the purpose of a condition based maintenance (CBM) of gas insulated switchgears (GIS) in power equipment. Four types of electrode systems such as a protrusion on enclosure (POE), a particle on spacer (POS), a free particle (FP) and a Floating were designed and fabricated. PD pulses were measured using UHF sensor with a frequency range of 300 MHz~1.4 GHz and a DAQ with a sampling rate of 250 MS/s. Discharge inception voltage (DIV), discharge extinction voltage (DEV), and phase resolved partial discharge (PRPD) were analyzed depending on electrode systems. The average DIV in the POS was 28.8 kV. It was about 1.7 times higher than that in the FP, which was the lowest value of 17.2 kV. The FP shuffled and jumped at the applied voltage of 23.5 kV. Over 95% of PD pulses in the POE were generated in the negative polarity ($181^{\circ}{\sim}360^{\circ}$) of applied voltage. The results showed the phase (${\Phi}$)-magnitude (dBm) of PD pulses by UHF sensor, a cluster was formed separately depending on electrode systems.

• Transactions of the Korean Society of Mechanical Engineers B
• /
• v.35 no.9
• /
• pp.869-874
• /
• 2011

In a CNG/diesel dual-fuel engine, CNG is used as the main fuel and a small amount of diesel is injected into the cylinder to provide ignition priming. In this study, a remodeling of the existing diesel engine into a CNG/diesel dual-fuel engine is proposed. In this engine, diesel is injected at a high pressure by common rail direct injection (CRDI) and CNG is injected at the intake port for premixing. The CNG/diesel dual-fuel engine had an equally satisfactory coordinate torque and power as the conventional diesel engine. Moreover, the CNG alternation rate is over 89% throughout the operating range of the CNG/diesel dual-fuel engine. PM emission by the dual-fuel engine is 94% lower than that by the diesel engine; however, NOx emission by the dual-fuel engine is higher than that by the diesel engine.

• Journal of Microbiology and Biotechnology
• /
• v.9 no.6
• /
• pp.773-777
• /
• 1999

Scale-up experiments for hydrolysis of beef tallow, fat, and palm kernel with lipase derived from Candida cylindracea were carried out in 1-1, 100-1, and 10,000-1 reactors. The optimum agitation speed for the hydrolysis of the 1-1 reactor was investigated and found to be 350rpm, and this was a basis for the scale-up of agitation speed. The hydrolysis system in this work was the oil-water system in which the hydrolysis seems to process a heterogeneous reaction. An emulsion condition was the most important factor for determining the reaction rate of hydrolysis. Therefore, the scale-up of agitation speed was performed by using the power n = 1/3 in an equation of the rules of thumb method. The geometrical similarity for scaling-up turned out to be unsatisfactory in this study. Thus, the working volume per one agitator was used for the scale-up. In the case of scale-up from a 1-1 reactor to a 100-1 reactor, the hydrolysis of palm kernel was very much scaled-up by initiating the rules of thumb method. However, the hydrolysis of fat and beef tallow in a 100-1 reactor was a little higher than that of the 1-1 reactor because of the difference of geometrical similarity. The scale-up of hydrolysis from the 100-1 reactor to the 10,000-1 reactor was improved compared to that of the 1-1 to 100-1 reactor. The present results indicated that the scale-up of hydrolysis in the oil-water system by the rules of thumb method was more satisfactory under the condition of geometrical similarity. Even in the case where geometrical similarity was not satisfactory, the working volume per one agitator could be used for the scale-up of a heterogeneous enzyme reaction.

• Journal of Advanced Navigation Technology
• /
• v.16 no.1
• /
• pp.96-102
• /
• 2012

The goal of mobile internet system is to provide a high-data-rate, low-latency and optimized packet radio access technology supporting flexible bandwidth deployments. Therefore, network architecture is designed with the goal to support packet-switched traffic with seamless mobility, quality of service and minimal latency. An important requirement for the mobile internet system is improved cell-edge BER performance and data throughput. This is to provide some level of service consistency in terms of geographical coverage as well as in terms of available data throughput within the communication coverage area. In a cellular system, however, the signal to interference plus noise power ratio gap between cell-center and cell-edge users can be of the order of 20 [dB]. The disparity can be even higher in a communication coverage limited cellular system. This leads to vastly lower data throughputs for the cell-edge users relative to cell-center users creating a large QoS gap. This paper proposes a analytical approach that tries to reduce inter-cell interference, and shows the SIR and BER performance according to the OFDM system parameters in mobile Internet environment.

• Journal of Wetlands Research
• /
• v.22 no.2
• /
• pp.121-129
• /
• 2020

This paper described a laboratory investigation of micro hydropower at lower head water in a free vortex flow. The vortex height, turbine rotation and torque for straight blade with inner curved edge, twisted blade and curved blade were investigated at the flow rate of 0.0069 ㎥/s in the inlet channel. The results showed that the optimum vortex strength occurred within the range of the diameter of basin to the outlet diameter ratios of 0.17~18.5. The power output and efficiency of straight blade were higher as compared to other blades. The highest amount of generated energy was 12.33 W, the torque was 0.91 N·m and the highest efficiency by considering effective head was 29.5 %, whereas the highest efficiency by considering vortex height was 80.5 % at the rotational speed of 132 rpm. The water vortex velocity of straight blade was about 2.8 times larger than the mean velocity in the inlet channel.