• Journal of the Korea Institute of Information and Communication Engineering
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• v.18 no.9
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• pp.2109-2116
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• 2014

This paper presents the implementation and design of the advanced WI-FI systems with beam-forming antenna that radiate their power to the direction of user equipment to improve the overall throughput, contrast to the general WI-FI systems equipped with omni-antenna. The system consists of patch array antenna, DSP, FPGA, and Qualcomm's commercial chip. The beam-forming system on the FPGA utilizes the packet information from Qualcomm's commercial chip to control the phase shifters and attenuators of the patch array antenna. The PCI express interface has been used to maximize the communication speed between DSP and FPGA. The directions of arrival of users are managed using the database, and each user is distinguished by the MAC address given from the packet information. When the system wants to transmit a packet to one user, it forms beams to the direction of arrival of the corresponding user stored in the database to maximize the throughput. Directions of arrival of users are estimated using the received preamble in the packet to make its SINR as high as possible. The proposed beam-forming system was implemented using an FPGA and Qualcommm's commercial chip together. The implemented system showed considerable throughput improvement over the existing general AP system with omni-directional antenna in the multi-user communication environment.

• Journal of the Korean Institute of Gas
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• v.7 no.1 s.18
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• pp.19-23
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• 2003

The purpose of this thesis is to investigate the BLEVE probability of LP gas storage tanks which are relatively more dangerous, by the deductive calculating method using the results of Birk's pilot tank test and the required heat capacity of BLEVE. The result that BLEVEs can occur in only above 43.68 percent of liquid filling level under $600^{\circ}C$ of tank pate temperature and $53^{\circ}C$ of inner liquid temperature, was obtained and will be useful for preventing the BLEVE of LP gas storage tanks in fire sites. In addition, this research showed conditions of external leak and fire causing BLEVE, based on 15ton capacity of LP gas tank which has the same specifications as those in Puchon LP gas filling station accident. The result of the calculation is that the minimum pool fire conditions of BLEVE are above 7.2mm equivalent diameter under a liquid release condition and above 17.6mm equivalent diameter under a two-phase release condition. In the end, the result of calculating the pool size corresponding the above conditions using EFFECTS version 2.1, concludes that a minimum of 3.3 meters of diameter and 10.4 meters of height should be needed for BLEVE outbreak.

• Journal of Microbiology and Biotechnology
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• v.22 no.10
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• pp.1330-1335
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• 2012

Foot and mouth disease (FMD) is one of the acute infectious diseases in hoofed and even-toed mammals, including pigs, and it occurs via acute infection by Aphthovirus. When FMD is suspected, animals around the location of origin are typically slaughtered and buried. Other methods such as rendering, composting, and incineration have not been verified in practice in Korea. After the FMD incident, the regular monitoring of the microbial community is required, as microorganisms greatly modify the characteristics of the ecosystem in which they live. This is the result of their metabolic activities causing chemical changes to take place in the surrounding environment. In this study, we investigated changes in the microbial community during a 24 week period with DNA extracts from leachate, formed by the decomposition of buried pigs at a laboratory test site, using denaturing gradient gel electrophoresis (DGGE) with a genomic DNA. Our results revealed that Bacteroides coprosuis, which is common in pig excreta, and Sporanaerobacter acetigenes, which is a sulfur-reduced microbe, were continuously observed. During the early stages (0~2 weeks) of tissue decomposition, Clostridium cochlearium, Fusobacterium ulcerans, and Fusobacterium sp., which are involved in skin decomposition, were also observed. In addition, various microbes such as Turicibacter sanguinis, Clostridium haemolyticum, Bacteroides propionicifaciens, and Comamonas sp. were seen during the later stages (16~24 weeks). In particular, the number of existing microbial species gradually increased during the early stages, including the exponential phase, decreased during the middle stages, and then increased again during the later stages. Therefore, these results indicate that the decomposition of pigs continues for a long period of time and leachate is created continuously during this process. It is known that leachate can easily flow into the neighboring environment, so a long-term management plan is needed in burial locations for FMD-infected animals.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.40 no.12
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• pp.1086-1092
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• 2012

It has been studied for DGPS/INS(Differential Global Positioning System/Inertial Navigation System) to offer the more precise and reliable navigation data with the aviation industry development. The flight performance evaluation of navigation system is very significant because the reliability of navigation data directly affect the safety of aircraft. Especially, the high-level navigation system, as DGPS/INS, need more precise flight performance evaluation method. The performance analysis is performed by comparing between the DGPS/INS navigation data and reference trajectory which is more precise than DGPS/INS. The GPS receiver, which is capable of post-processed CDGPS(Carrier-phase DGPS) method, can be used as reference system. Generally, the DGPS/INS is estimated the CG(Center of Gravity) point of aircraft while the reference system is output the position of GPS antenna which is mounted on the outside of aircraft. For this reason, estimated error between DGPS/INS and reference system will include the error due to lever arm. In order to more precise performance evaluation, it is needed to compensate the lever arm. This paper presents procedure and result of flight test which includes lever arm compensation in order to verify reliability and performance of DGPS/INS more precisely.

• Journal of Food Hygiene and Safety
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• v.33 no.2
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• pp.110-117
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• 2018

The aim of this study was to develop an analytical method for the quantification of diazepam residues in fishery products, using liquid and gas chromatography-tandem mass spectrometry (LC-MS/MS and GC-MS/MS). The sample utilized in the study was extracted from the fish sample (crucian carp) using 0.1% formic acid in acetonitrile. For the utilization of the purification process, the dispersive solid phase extraction (dSPE) was used for LC-MS/MS, dSPE and SPE was used for GC-MS/MS, respectively. To be sure, the standard calibration curves showed a good linearity as the noted correlation coefficients, $r^2$ was > 0.99. The average recoveries for accuracy ranged in 99.8~124% for the samples which were fortified at three different levels (0.001, 0.002 and 0.010 mg/kg). The correlation coefficient for the precision effect was measured at a range of 4.01~11.8%. The limit of detection (LOD) for the diazepam analysis was 0.0004 mg/kg, and the limit of the quantification (LOQ) was 0.001 mg/kg. The proposed analytical method was characterized with a high accuracy and acceptable sensitivity to meet the established Codex Alimentarius Commission (CAC/GL71-2009) guideline requirements. We therefore established the optimal analysis method for the determination of diazepam in the fishery products using LC-MS/MS and GC-MS/MS. It would be applicable to analyze the diazepam residues in fishery products in further studies on this subject.

• Korean Journal of Poultry Science
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• v.48 no.4
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• pp.169-176
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• 2021

An experiment was conducted to investigate the effects of varying levels of hydrolyzed yeast on egg production and egg quality in aged laying randomly allotted to three dietary treatments such that egg production was similar in each treatment (6 replicates of 10 birds each). The layers were fed diets containing 0, 0.1, or 0.2% hydrolyzed yeast for eight weeks. No significant difference was observed in egg production during the first half of the experiment. Egg production and daily egg mass in groups fed diets containing hydrolyzed yeast were significantly higher (P<0.05) than those of the control groups during the second half of the experiment. Egg weight was not affected by the dietary treatment. Eggshell strength and thickness in groups fed diets containing hydrolyzed yeast were significantly higher than those of the control groups during the overall experimental period (P<0.05). Although no significant differences were observed in the Haugh units, yolk color in the group fed diets containing 0.1% hydrolyzed yeast was significantly higher than that in the control group (P<0.05). The mammillary layer thickness increased in a linear manner and significantly following treatment with dietary hydrolyzed yeast (P<0.05). Antibody titer against avian influenza virus in the group fed diets containing 0.2% hydrolyzed yeast was significantly higher (P<0.05) than that in the control group. In conclusion, dietary hydrolyzed yeast improved egg production and eggshell quality of laying hens in the late stages of production.

• Journal of the Economic Geographical Society of Korea
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• v.27 no.3
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• pp.174-191
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• 2024

This study analyzed the spatiotemporal evolution of Korean multinational corporations' (MNCs') foreign direct investment (FDI) networks from 1978 to 2023, focusing on Samsung Electronics and LG Electronics. Using data on the consolidated overseas subsidiaries of these two companies, a two-mode network was constructed to examine the status of host countries through the betweenness centrality index and to identify types of countries with similar value chain arrangements by investigating their linkage structures. The main findings are as follows. First, during the early phase of Korean electronics MNCs' overseas expansion in the 1980s, they primarily established sales bases in developed consumer markets. However, over time, they gradually expanded into other business areas, including manufacturing, producer services, and R&D, increasing complexity in their FDI networks as cross-border mergers and acquisitions (M&As) became more frequent. Second, the United States has remained central to these MNCs' FDI networks since the 1980s, but more recently, China has emerged as a significant hub, challenging the U.S. in global value chains. Third, emerging Asian economies, including India, Vietnam, and Indonesia, have strengthened their positions due to the diversification of MNCs' investment objectives from manufacturing bases to a broader range of business areas. Finally, since the 2010s, the convergence of the electronics industry with the automotive electronics sector and new industries has led to a diversification of the value chain arrangements of Korean electronics MNCs.

• Asian-Australasian Journal of Animal Sciences
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• v.26 no.12
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• pp.1732-1741
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• 2013

Two experiments were conducted to determine physical and chemical properties of vermicelli waste (VW) and effect of VW inclusion levels on growth performance of broilers. In experiment 1, VW samples were randomly collected from vermicelli industry in Thailand to analyze nutritional composition. Vermicelli waste contained 9.96% moisture, 12.06% CP, 32.30% crude fiber (CF), and 0.57% ether extract (EE), as DM basis. The ratio of insoluble:soluble non-starch polysaccharide (NSP) was 43.4:8.9. A total of 120 chicks (6 pens per treatment and 10 chicks per pen) were fed a corn-soybean meal-based diet or 20% VW substituted diet to determine the apparent metabolizable energy corrected for nitrogen retention ($AME_n$) of VW. The $AME_n$ of VW was $1,844.7{\pm}130.71$ kcal/kg. In experiment 2, a total of 1,200 chicks were randomly allotted to 1 of 4 dietary treatments for 42-d growth assay. There were 300 chicks with 6 pens per treatment and 50 chicks per pen. The dietary treatments contained 0%, 5%, 10%, or 15% VW, respectively. All diets were formulated to be isocaloric and isonitrogenous. From 0 to 18 d of age chicks fed VW diets had higher (p<0.001) feed conversion ratio (FCR) compared with those fed the control diet. No difference was observed during grower and finisher phase (19 to 42 d). Chicks fed VW diets had lower relative weight of abdominal fat (p<0.001) but higher relative weight of gizzard (p<0.05) than those of chicks fed the control diet. Increasing VW inclusion levels increased ileal digesta viscosity (p<0.05) and intestinal villus height of chicks (p<0.001). For apparent total tract digestibility assay, there were 4 metabolic cages of 6 chicks that were fed experimental treatment diets (the same as in the growth assay) in a 10-d total excreta collection. Increasing VW inclusion levels linearly decreased (p<0.05) apparent total tract digestibility of DM and CF.

• Journal of Information Management
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• v.31 no.1
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• pp.12-42
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• 2000

Digital library research has attracted much attention. While many research projects are funded by government agencies and national and international bodies, some are run by specific academic and research institutions and libraries. While some digital library projects, such as the ELINOR project in the UK, the first two phases of the eLib(Electronic Libraries) programme in the UK, and the first phase of the DLI(Digital Library Initiative) in the USA, are now over, a number of other projects are currently under-way in different parts of the world. Beginning with the definitions and characteristics of digital libraries proposed by various researchers, this paper provides brief accounts of some major digital library projects that are currently in progress, or are just completed, in different parts of the world. There follows a review of digital library research under 16 major headings. Literature for this review has been identified through a search on the LISA CD-ROM database and a Dialog search on library and information science databases, and the resulting output has been supplemented by a scan of the various issues of D-Lib Magazine and Ariadne, and the Web sites of various organizations and institutions engaged in digital library research. The review indicates that we have learned a lot through digital library research within a short span of time. However, a number of issues are yet to be resolved. The paper ends with an indication of the research issues that need to be addressed and resolved in the near future in order to bring the digital library from the researcher's laboratory to the real life environment.

• Journal of Information Management
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• v.30 no.4
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• pp.39-60
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• 1999

Digital library research has attracted much attention. While many research projects are funded by government agencies and national and international bodies, some are run by specific academic and research institutions and libraries. While some digital library projects, such as the ELINOR project in the UK, the first two phases of the eLib(Electronic Libraries) programme in the UK, and the first phase of the DLI(Digital Library Initiative) in the USA, are now over, a number of other projects are currently under-way in different parts of the world. Beginning with the definitions and characteristics of digital libraries proposed by various researchers, this paper provides brief accounts of some major digital library projects that are currently in progress, or are just completed, in different parts of the world. There follows a review of digital library research under 16 major headings. Literature for this review has been identified through a search on the LISA CD-ROM database and a Dialog search on library and information science databases, and the resulting output has been supplemented by a scan of the various Issues of D-Lib Magazine and Ariadne, and the Web sites of various organizations and institutions engaged in digital library research. The review indicates that we have learned a lot through digital library research within a short span of time. However, a number of issues are yet to be resolved. The paper ends with an indication of the research issues that need to be addressed and resolved in the near future in order to bring the digital library from the researcher's laboratory to the real life environment.