• Journal of the Institute of Electronics Engineers of Korea SP
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• v.44 no.5
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• pp.45-53
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• 2007

To recover transmitted signal perfectly at DTV receiver, we have to acquire carrier frequency synchronization to compensate pilot signal which located in wrong position and rotated phase. Also, we need a symbol timing synchronization to compensate sampling timing error. Conventionally, to synchronize symbol timing, we use Gardner's scheme which used in multi-level signal. Gardner's scheme is well known for its sampling the timing error signal from every symbol and it makes easy to detect and keep timing sync in multi-path channel. In this paper, to discuss the problem when the received power level is out of range and we cannot get synchronization information. With this problem, we use 2 step procedures. First, we put a received signal power compensation block before Garder's timing error detector. Second, adaptive loop filter to get a fast synchronization information and averaging loop filter's output value to reduce the amount of jitter after synchronization in PLL(Phased Locked Loop) circuit which is used to get a carrier frequency synchronization and symbol timing synchronization. Using the averaging value, we can estimate offset. Based on offset changing ratio, we can adapt adaptive loop filter to carrier frequency and symbol timing synchronization circuit.

• Journal of Animal Science and Technology
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• v.58 no.10
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• pp.37.1-37.10
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• 2016

Background: Providing of insufficient nutrients limits the potential growth of pig, while feeding of excessive nutrients increases the economic loss and causes environment pollution. For these reasons, phase feeding had been introduced in swine farm for improving animal production. This experiment was conducted to evaluate the effects of dietary energy levels and phase feeding by protein levels on growth performance, blood profiles and carcass characteristics in growing-finishing pigs. Methods: A total of 128 growing pigs ([Yorkshire ${\times}$ Landrace] ${\times}$ Duroc), averaging $26.62{\pm}3.07kg$ body weight, were assigned in a $2{\times}4$ factorial arrangement with 4 pigs per pen. The first factor was two dietary energy level (3,265 kcal of ME/kg or 3,365 kcal of ME/kg), and the second factor was four different levels of dietary protein by phase feeding (1growing(G)-2finishing(F) phases, 2G-2F phases, 2G-3F phases and 2G-3F phases with low CP requirement). Results: In feeding trial, there was no significant difference in growth performance. The BUN concentration was decreased as dietary protein level decreased in 6 week and blood creatinine was increased in 13 week when pigs were fed diets with different dietary energy level. The digestibility of crude fat was improved as dietary energy levels increased and excretion of urinary nitrogen was reduced when low protein diet was provided. Chemical compositions of longissimus muscle were not affected by dietary treatments. In backfat thickness ($P_2$) at 13 week, pigs fed high energy diet had thicker backfat thickness (P = 0.06) and pigs fed low protein diet showed the trend of backfat thinness reduction (P = 0.09). In addition, water holding capacity was decreased (P = 0.01) and cooking loss was increased (P = 0.07) as dietary protein level reduced. When pigs were fed high energy diet with low subdivision of phase feeding, days to 120 kg market weight was reached earlier compared to other treatments. Conclusion: Feeding the low energy diet and subdivision of growing-finishing phase by dietary protein levels had no significant effect on growth performance and carcass characteristics. Also, phase feeding with low energy and low protein diet had no negative effects on growth performance, carcass characteristics but economical profits was improved.

• Korean Journal of Optics and Photonics
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• v.14 no.6
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• pp.649-656
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• 2003

In this paper we confirm the relation between the phase and phase error of the beat signal at the lock-in region of the dither type ring laser gyroscope by numerical calculation. We also study the requirement of the dither noise of an amplitude modulation type for statistical zero averaging of the beat signal phase error, without accumulation. As a result, we find that the dither noise requires the increase and decrease gradients of the dither amplitude, and those gradients should be combined with similar white noise. The slope of the gradient and maximum/minimum amplitude must be changed randomly. We confirm the error accumulation characteristic related to the dither noise by comparison of the two outputs during temperature change, by operating the two kinds dither noise, one is satisfied with the requirement and the other is not.

• Journal of Climate Change Research
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• v.5 no.1
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• pp.61-70
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• 2014

The amount of greenhouse gas (GHG) emissions has been increasing steadily over the last 3 years (2009~2011), averaging 5.7 percent a year, due to the growth of low cost carriers and the increased demand for air transportations. The present study attempts to investigate the aviation fuel consumption and GHG emissions of Tier 3a type by the flight phase from three aircraft type such as B737-600(routes between Gimpo-Jeju airport), B737-700(routes between Gimpo-Jeju airport and Inchon-Narita), B737-800(routes between Inchon-Narita) using the Flight Operation Quality Assurance(FOQA) data of the year 2011.

• Journal of Animal Science and Technology
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• v.59 no.8
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• pp.18.1-18.8
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• 2017

Background: In 2006, the European Union (EU) has decided to forbid use of antibiotics as growth promoters. Although many researches had been conducted about fiber source as alternatives of antibiotics, there are still lack of reports in the literature about the optimum level of sugar beet pulp supplementation, affecting growth performance and nutrient digestibility in weaning pigs. Therefore, different level of sugar beet pulp was added to diets to determine the effects of sugar beet pulp supplementation on growth performance, nutrient digestibility, fecal microflora, blood profile and incidence of diarrhea in weaning pigs. Methods: A total of 200 weaning pigs [$(Yorkshire{\times}Landrace){\times}Duroc$], averaging $9.01{\pm}1.389kg$ of initial body weight were, allotted to 5 treatments in a randomized complete block (RCB) design. Each treatment was composed of 4 replicates with 10 pigs per pen. The treatments were control treatment: Corn-SBM basal diet + ZnO (phase 1: 0.05%; phase 2; 0.03%) and four different levels of sugar beet pulp were supplemented in Corn-SBM basal diet (3, 6, 9 or 12%). Two phase feeding programs (phase 1: 1-2 weeks; phase 2: 3-5 weeks) were used for 5 week of growth trial. Results: In feeding trial, there were no significant differences in growth performance and incidence of diarrhea among treatments. The E.coli counts were not significantly different among dietary treatments but linear response was observed in Lactobacillus counts as sugar beet pulp supplementation increased (P < 0.05). In addition, IGF-1, IgA and IgG were not affected by dietary treatments. However, the BUN concentration was decreased when pigs were fed the treatments of diets with SBP compared to that of control treatment (P < 0.05). In nutrient digestibility, crude fiber and NDF digestibilities were improved as the sugar beet pulp increased (P < 0.05). However, digestibilities of crude ash, crude fat, crude fiber and nitrogen retention were not affected by dietary sugar beet pulp levels. Conclusion: This experiment demonstrated that sugar beet pulp can be supplemented in weaning pigs' diet instead of ZnO to prevent postweaning diarrhea without any detrimental effect on growth performance.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.24 no.1
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• pp.93-101
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• 2000

The characteristics of spray nozzle have been quantified with the measurement of fluorescence and Mie scattering images. To correct the attenuation of the incident light sheet, a sequential double-pass light sheet system and the geometrical averaging of two images was implemented. Quantitative mass flux distribution of spray was obtained from fluorescence image. 3-D image is reconstructed using 2-D radial images. Sauter mean diameter (SMD) distribution was determined using the ratio of fluorescence signal intensity and Mie scattering signal intensity and the values were quantified with PDP A data. The measurement of mass flux and SMD using planar imaging technique agee with PDP A data fairly well in the low density region. However, in dense region， there are significant errors caused by secondary scattering. It was found that the planar imaging technique provides many advantages over the point measurement technique, such as PDP A, and can be implemented for quantitative measurement, especially in low density region.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.31 no.7 s.262
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• pp.611-619
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• 2007

In this study, the droplet size distribution of a slit injector at different surrounding conditions, such as air flow and fuel temperature, were investigated. Phase Doppler anemometry (PDA) was utilized to investigate the initial droplet size distribution and the effect of fuel temperature and air flow on droplet size distribution. The entrained air motion was also evaluated by the temporal velocity profile of droplets. When the air flow velocity increased, the small droplets were more entrained to the upper and central parts of the spray and this tendency was confirmed by plotting the temporal velocity profile of droplets. This entrainment of small droplets at high airflow velocities caused relatively small mean droplet size at upper and central parts of the spray and the large mean droplet size at downstream and edge of the spray, compared to that of low airflow velocities. The total mean droplet size, obtained by averaging the size of all droplets measured at all test locations, decreased when the high airflow velocities were applied. The increased fuel temperature, with an airflow velocity of 10m/s, caused reduced droplet size at all test locations. However, the decreased value of mean droplet size at high fuel temperatures was relatively higher at upper parts of the spray, compared to downstream, as a result of enhanced entrainment of small droplets to upper parts of the spray.

• Journal of ILASS-Korea
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• v.16 no.1
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• pp.1-6
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• 2011

In recent years, the need for more fuel-efficient and lower-emission vehicles has driven the technical development of alternative fuels such as LPG (Liquefied Petroleum Gas) which is able to meet the limits of better emission levels without many modifications to current engine design. LPG has a high vapor pressure and lower viscosity and surface tension than diesel and gasoline fuels. These different fuel characteristics make it difficult to directly apply the conventional gasoline or diesel fuel pump. Self acting lubricated groove design or coating can be used in high-speed and high precision spindle system like a roller-vane type fuel pump, because of its advantages such as low frictional loss, low heat generation, averaging effect leading better running accuracy and simplicity in manufacturing. Those design method can also affect the atomization of fuel from the injector and the formation of fuel film on the intake manifold. In this study, experiments are carried out to get performance characteristics of initial and steady state operation, The characteristics of vane type fuel pump were investigated to access the applicability on LPLi engine.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2009.11a
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• pp.387-391
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• 2009

The experimental study on the ducted fan for the propulsion system of a small UAV has been performed. In this paper, to investigate the three-dimensional unsteady flow field characteristics of the ducted fan, it was measured by using a $45^{\circ}$ inclined hot-wire from hub to tip at inlet, behind the rotor and outlet of the ducted fan. The hot-wire signal data was acquired at fixed yaw angle. The data was averaged by using the PLEAT (Phase Locked Ensemble Averaging Technique), and then three of non-linear equations were solved simultaneously by using the Newton-Rhapson numerical method. Flow characteristics such as tip vortex, secondary flow and tip leakage flow were confirmed through axial, radial and tangential contour plot.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2009.11a
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• pp.395-398
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• 2009

Currently, a new generation of ducted fan UAVs (Unmanned Aerial Vehicles) is under development for a wide range of inspection, investigation and combat missions as well as for a variety of civil roles like traffic monitoring, meteorological studies, hazard mitigation etc. The current study presents extensive results obtained experimentally in order to investigate the tip clearance effects on performance characteristics of a ducted fan for small UAV systems. Three ducted fans having different tip clearance gap and with same rotor size were examined under three different yawed conditions of calibrated slanted hot-wire probe. Three dimensional velocity flow fields were measured from hub to tip at outlet of the ducted fan. The analysis of data were done by PLEAT (Phase locked Ensemble Averaging Technique) and three non-linear differential equations were solved simultaneously by using Newton -Rhapson numerical method. Flow field characteristics such as tip vortex and secondary flow were confirmed through axial, radial and tangential velocity contour plots. At the same time, the effects of tip clearance on axial thrust and input power were also investigated by using wind tunnel measurement system. For enhancing the performance of ducted fan, tip clearance level should be as small as possible.