• Journal of the Korea Institute of Information and Communication Engineering
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• v.15 no.10
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• pp.2149-2156
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• 2011

In this paper, design of a new 3-dimensional (3-D) 16-ary signal constellation with constant envelope is presented and analyzed. Unlike the conventional 16-ary constellations, all signal points of the new constellation are uniformly located on the surface of a sphere so that they have a unique amplitude level and a symmetrical structure. When average power of the constellations is normalized, the presented 16-ary constellation has around 11.4% increased minimum Euclidean distance (MED) as compared to the conventional ones that have non-constant envelope. As a result, a digital communication system which exploits the presented constellation has 1.2dB improved symbol error rate (SER). While signal points of the conventional constant-envelope constellation are not distributed uniformly on the surface of a sphere, those of the proposed constellation has a completely symmetric distribution. In addition, the new signal constellation has much lower computational complexity for practical implementation than the conventional one. Hence, the proposed 3-D 16-ary signal constellation is appropriate for the application to a communication system which strongly requires a constant-envelope characteristic.

• Microbiology and Biotechnology Letters
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• v.33 no.3
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• pp.200-206
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• 2005

A bacterium with high productivity of poly-$\gamma$-glutamic acid (PGA) was isolated from the traditional Korean seasoning, ChungKookJang. The 16s ribosomal RNA sequence of isolated strain showed 97.6, 98.9 and $90.3{\%}$ of similarity to those of Bacillus sp. WL-3, Bacillus subtilis; ENV1 and B amy-loliquefaciens (T), respectively. Accordingly, this bacterium was identified as a Bacillus sp. However, some biochemical characteristics of this strain were different from those of B. subtilis: D-xylose fermentation and glycogen utility were negative. Maximum production of PGA was achieved when it was grown aerobically in a culture medium containing glutamic acid ($3{\%}$) and fructose ($4{\%}$) as carbon sources. The volumetric yield of PGA reached up to 27 g/l in the optimum culture medium. These results suggest that the present strain can be applicable for industrial purposes such as a prototype strain for food or cosmetics industry.

• Journal of Nutrition and Health
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• v.43 no.1
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• pp.5-11
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• 2010

We conducted comparative study on metabolizable energy content of extracts of angelica keiskei and its byproduct. Total six different groups consisting of five test groups treated with angelica keiskei and one control group were compared. Each of the five test groups were given 30% of one of whole plant, extracts, fermented of extracts, byproduct and extracts plus byproduct, respectively, mixed with AIN93M. After 3 days of adjustment period, all groups were subjected to 4 days of test period during which the amounts of feed intake and excretion were measured everyday. All feces were treated for the prevention of decomposition and changes before its energy content were measured using a bomb calorimeter. The amount of excretion was $4.8\;{\pm}\;0.3\;g$/rat/3 days in control group and 9.9-15.0 g/rat/3 days in the groups were added with extracts of angelica keiskei indicating that the angelica keiskei-treated groups produce 2-3 times more excretion. Metabolic energy of control diet was 4,133.3 kcal. This was found to be 15 to 20% higher compared with the metabolic energy content ranging from 3,117.0 kcal/kg (extracts of angelica keiskei) to 3,259.8 kcal/kg (extracts plus byproducts) angelica keiskei-treated groups. This is interpreted as the result of the decreased metabolic energy in the test diets were substituted with 30% of ngelica keiskei-treated ingredient which has low metabolic content itself. One notable finding is that the metabolic content of the group mixed with byproducts and extracts (1,763.0 kcal/kg) is 27% higher than that of extracts of angelica keiskei (1,286.8 kcal/kg) indicating that mechanical grinding increases the rate of digestion and absorption increasing, in turn, the energy content used in the body. The results of analysis of overall caloric absorption showed absorption rate in order of Whole plant < extracts < byproduct < extract plus byproduct < fermented of extract.

• Korean Journal of Agricultural and Forest Meteorology
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• v.17 no.1
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• pp.1-14
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• 2015

Climate change caused by elevated greenhouse gases would affect crop production through different pathways in agricultural ecosystems. Because an agricultural ecosystem has complex interactions between societal and economical environment as well as organisms, climate, and soil, adaptation measures in response to climate change on a specific sector could cause undesirable impacts on other sectors inadvertently. An integrated system, which links individual models for components of agricultural ecosystems, would allow to take into account complex interactions existing in a given agricultural ecosystem under climate change and to derive proper adaptation measures in order to improve crop productivity. Most of models for agricultural ecosystems have been used in a separate sector, e.g., prediction of water resources or crop growth. Few of those models have been desiged to be connected to other models as a module of an integrated system. Threfore, it would be crucial to redesign and to refine individual models that have been used for simulation of individual sectors. To improve models for each sector in terms of accuracy and algorithm, it would also be needed to obtain crop growth data through construction of super-sites and satellite sites for long-term monitoring of agricultural ecosystems. It would be advantageous to design a model in a sector from abstraction and inheritance of a simple model, which would facilitate development of modules compatible to the integrated prediction system. Because agricultural production is influenced by social and economical sectors considerably, construction of an integreated system that simulates agricultural production as well as economical activities including trade and demand is merited for prediction of crop production under climate change.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.42 no.4
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• pp.326-335
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• 2014

Aerodynamic characteristics of the small two-stage turbo blower were investigated using commercial CFD tool(ANSYS CFX Ver. 14.5) in this paper. Turbo blower, which is a centrifugal type of turbomachinery, is used in various industries. It is used for application that required high static pressure rising at relatively small volumetric flow rate. In order to understand the mechanism of static pressure rising, the aerodynamic characteristics of the small two-stage turbo blower are analyzed at high rotating speed in this study. The k-${\omega}$ SST turbulence model, which is good at prediction of adverse pressure gradient flows, was applied. The CFD results of the turbo blower are validated by performance test. The static pressure rising of the turbo blower is nonlinearly increased over the first stage and the second stage. The secondary flow occurred at guide vanes, between the casing and the first impeller shroud, and the bottom of the impeller disk. As a result, It is required that whole fluid area is analyzed to predict aerodynamic characteristics of small two-stage turbo blower. and the result should be selected with considering for error from experiment and CFD.

• Journal of Broadcast Engineering
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• v.15 no.2
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• pp.205-216
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• 2010

In this paper, a method of MPEG-2 Transport Stream (TS) multiplexing for Ultra HDTV (UHDTV) and its design and implementation as a SW tool is described. In practice, UHD video may be divided into several HD videos and each video is encoded in parallel. Therefore, it is necessary to synchronize and multiplex multiple bitstreams encoding each HD video for transmitting and storing UHD video. In this paper, it is assumed that 4 HD videos partitioning a UHD spatially are encoded as H.264/AVC and two 5.0 channel audios are encoded by AC-3. Therefore, 4 H.264/AVC elementary streams (ESs) and 2 AC-3 ESs is mainly considered in the TS multiplexing of UHD. For the carriage of H.264/AVC and AC-3 over MPEG-2 TS, PES packetization and TS multiplexing are designed and implemented based on the extended specification of the MPEG-2 Systems and ATSC (Digital audio compressed standard), respectively. The implemented UHD TS multiplexing tool emulates real time HW operation in the time unit corresponding to the duration of one TS packet transmission in a given TS rate. In particular, in order to satisfy the timing model, the buffers defined in the TS System Target Decoder (T-STD) are monitored and their statuses are considered in the scheduling of TS multiplexing. For UHD multiplexing, two kinds of multiplexing structures, which are UHD re-multiplexing and UHD program multiplexing, are implemented and their strength and weakness are investigated. The developed UHD TS multiplexing tool is tested and verified in terms of the syntax and semantics conformance and functionalities by using a commercial analyzer and real-time presentation tools.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.47 no.12
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• pp.831-840
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• 2019

Flush Air Data Sensing system (FADS) estimates air data states using pressure data measured at the surface of flight vehicles. The FADS system does not require intrusive probes, so it is suitable for high performance aircrafts, stealth vehicles, and hypersonic flight vehicles. In this study, calibration procedures and solution algorithms of the FADS for a sphere-cone shape vehicle are presented for the prediction of air data from subsonic to supersonic flights. Five flush pressure ports are arranged on the surface of nose section in order to measure surface pressure data. The algorithm selects the concept of separation for the prediction of flow angles and the prediction of pressure related variables, and it uses the pressure model which combines the potential flow solution for a subsonic flow with the modified Newtonian flow theory for a hypersonic flow. The CFD code which solves Euler equations is developed and used for the construction of calibration pressure data in the Mach number range of 0.5~3.0. Tests are conducted with various flight conditions for flight Mach numbers in the range of 0.6~3.0 and flow angles in the range of -10°~+10°. Air data such as angle of attack, angle of sideslip, Mach number, and freestream static pressure are predicted and their accuracies are analyzed by comparing predicted data with reference data.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.48 no.4
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• pp.255-267
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• 2020

Under SLD conditions, due to the large size of droplets, physical phenomena such as wall-droplet interaction and deformation have a significant effect on the icing process. Accordingly, many studies have been conducted in order to computationally simulate SLD effects. As one of the efforts, post-processing method have been proposed to describe wall-droplet interaction effect, which modified collection efficiency using Wright model. However, since the model doesn't properly consider the wall condition, it still overestimated collection efficiency and impingement limit. To solve this problem, impingement areas were divided into 3 different regions, and the post-processing method was introduced with the new wall-droplet interaction model developed based on Bai and Gosman rebound model. In order to consider the effect of deformation, the most suitable model was selected by comparing the deformation models used in the various icing codes. As a result, the modified post-processing method showed improved accuracy in predicting the impingement limits and collection efficiency by further estimating mass flux loss due to rebound, and it was observed that the result was the closest to the experimental data when the deformation effect was included by using Wiegand model.

• Korean Journal of Environmental Agriculture
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• v.16 no.3
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• pp.239-244
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• 1997

To develope more effective extraction methods for paraquat in soil, some modification methods were accomplished in two different types of soil. For extraction of tightly bound-paraquat, conc. HCl 70ml were added with different shaking times, and then $H_2SO_4$ reflux were performed for an hour. In this case, 60 minutes shaking were optimum and recovery were increased more $1.09{\sim}1.50$ folds(84.0% in high clay contents soil, but 96.7% in low clay contents soil) and the long-time consuming step, filtration were easily done, with decreasing filtration time were shorter 4.6 folds(ca. $11{\sim}14min.$). than general paraquat analytical method(ca. $55{\sim}65min.$). And only $H_2O_2$ digestion with different volume and refluxing time resulted in recovery increasing. Nevertheless, considering analyst's safety, 30ml of $H_2O_2$ addition and 30 minutes reflux were regarded as optimum condition. Although, Kjeldahl digestion with $H_2O_2$ showed relatively high recovery, it is not significant statistically. For extraction of loosely bound-paraquat, 0.01, 0.1, 1.0, 10.0M of $NH_4Cl$ and of $CaCl_2$ compared with $1.5{\sim}24hr$ of different shaking time. There were no loosely bound residues of paraquat.

• Journal of Energy Engineering
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• v.10 no.3
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• pp.195-205
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• 2001

A great deal of energy is necessary with emission of lots of wastewater in dyeing and finishing process, but heat recovery from wastewater is not introduced since is technology is not developed yet. In order to obtain the method utilizing hot water produced by heat source, that is, dyeing wastewater it was investigated the characteristics of dyeing and finishing process and energy basic unit. Energy basic unit of polyester/cotton (T/C), polyester/rayon (T/R) and polyester dyeing process are higher than that of the other process. The average quantity of wastewater for each dyeing company is 20,470 ton/month, the average temperature of wastewater is about 41$^{\circ}C$. Because the SS solution of wastewater in polyester dyeing process is lower than that of the other process, the effect of corrosion in heat recovery system is low. Since the energy price for 1000 kcal produced by vapor compression heat pump is presumed to be 22.50 won, it is found to be very economic heat recovery system, and its payback is 2.09 years for the factory with LNG boiler.