• Journal of Advanced Navigation Technology
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• v.16 no.3
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• pp.440-448
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• 2012

Optimal net residual dispersion (NRD) and effective launching power range of optical transmission links with optical phase conjugator (OPC) and dispersion management (DM) for compensating the distorted wavelength division multiplexing (WDM) signals due to interaction of group velocity dispersion (GVD) and optical nonlinear effects. WDM systems considered in this research have optical links with the random distribution of residual dispersion per span (RDPS) in each single mode fiber (SMF) spans of only one half transmission section for designing the adaptive optical transmission system configurations. It is confirmed that optimal NRD is 10 ps/nm and effective launching power range is obtained to be -8~1 dBm under NRD = 10 ps/nm in optical links with total dispersion controlled by precompensation. And, it is also confirmed that optimal NRD is -10 ps/nm and effective launching power range is obtained to be -7.5~1 dBm under NRD = -10 ps/nm in optical links with total dispersion controlled by postcompensation.

• Journal of Advanced Navigation Technology
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• v.12 no.4
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• pp.311-316
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• 2008

A configuration scheme of optical link effectively compensating chromatic dispersion and nonlinear effects accumulated in optical link with single mode fibers (SMFs) is proposed. The proposed optical link configuration consist of optical phase conjugator (OPC) placed at middle of total transmission length and inline dispersion management (DM) as a role of compensating cumulated in each optical repeater of SMF by dispersion compensating fiber (DCF). Net residual dispersion (NRD) of this optical link is designed to be controlled through precompensation and postcompensating. The precompensation and postcompensation are designed to be determined by DCF after transmitter and before receiver, respectively. It is confirmed that optical link configuration with symmetric dispersion map with respect to OPC, which is implemented by controlling NRD through both precompensation and postcompensation, is better to be effective and adaptive than other configuration with NRD controlled by only precompensation or postcompensation.

• Journal of KIISE:Information Networking
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• v.35 no.5
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• pp.367-373
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• 2008

Recently, the NAT middlebox widely deployed in the home network environment prohibits DM operations from reaching user devices behind NAT. In this article, we focus on NAT issues to manage home network devices. Particularly, we discuss standardization efforts, and present our proposal to deploy DM services for VoIP and IPTV devices under NAT. By slightly changing behaviors of Simple Network Management Protocol (SNMP) Manager and Agent, and defining additional Management Objects (MOs) to gather NAT binding information, we could solve the NAT traversal problem under symmetric NAT. Moreover, we propose an enhanced method to search the UDP hole binding time of the NAT box. We applied our method to randomly selected 22 VoIP devices out of 194 NATed hosts in the real broadband network and have achieved 99% of the success ratio for exchanging SNMP request messages and 26% of enhancement for searching the UDP hole binding time.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.13 no.5
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• pp.959-966
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• 2009

Effective transmission distance depending on transmission capacity of WDM systems with inline dispersion management (DM) and optical phase conjugator (OPC) at middle of total transmission length is investigated. The range of net residual dispersion (NRD) resulting 1 dB eye opening penalty (EOP) in 1 Tbps WDM system, in which NRD controlled by only postcompensation, is also investigated. It is confirmed that effective transmission distances are increasedto longer than several hundreds kilometers by applying optimal NRD depending on transmission capacity and distance. And it is confirmed that in 1 Tbps WDM system if NRD is determined to +17 ps/nm, the maximum transmission distance is achieved, and, especially, in long-haul 1 Tbps WDM system the effective NRD range will be determined within positive value.

• Journal of The Korean Society of Grassland and Forage Science
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• v.40 no.2
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• pp.87-97
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• 2020

This experiment was carried out to study the effects of different environmental conditions and cultivation techniques on productivity of grasslands in central and southern area of Korea on 2017 and 2018. Average dry matter yield of grasslands at 10 actual production sites was 7,496 kg/ha. that was ranged from 4,652 to 13,292 kg/ha with least significant difference(LSD) of 1,577kg/ha between grasslands (p<0.05) on 2017. Average dry matter yield of grasslands at 10 actual production sites was 7,914 kg/ha. that was ranged from 3,927 to 12,372 kg/ha with LSD of 1,577kg/ha between grasslands(p<0.05) on 2018. Dry matter(DM) yield of grasslands have positive correlation with soil fertility (p<0.01) but not correlated with rainfall and air temperature among cultivation environments. And also DM yield of grasslands have positive correlation with grassland management techniques(p<0.01). These results suggest that practices of grassland management techniques and improvement of soil fertility are more important than cultivation environments by climate change for increasing the DM yield of grassland in central and southern area of Korea.

• Journal of The Korean Society of Grassland and Forage Science
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• v.41 no.3
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• pp.147-154
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• 2021

Cutting management has been identified as a critical factor in the alfalfa production systems because it has a significant impact on maximizing yield and maintaining the forage quality. The objective of this experiment was to determine the proper cutting height according to harvesting time for optimizing nutrient yield and forage nutritive quality of alfalfa grown in alpine regions of Korea. Alfalfa was sown at a seeding rate of 30 kg/ha in August 2018 and harvested at four cuttings in 2019 (3 May, 2 July, 11 September, and 13 October). Cutting heights were adjusted at 5, 15, and 25 cm above the soil surface. Alfalfa plant was tallest at the third cutting (109 cm), which was on average 35 cm taller than the first or second cutting. Relative feed value (RFV) remained unaffected by cutting height at the first harvest, but increased consistently in subsequent harvests as cutting height increased. Alfalfa collected at the first and fourth cuttings had the highest RFV (mean 152), which was on average 8 and 67 units higher than the second and third harvests, respectively. At each harvest, in vitro dry matter digestibility was highest in alfalfa cut at a 25-cm height. Dry matter (DM) production at each cutting height was highest in the first cutting, accounting for on average 36-37% of total annual DM production, and lowest in the fourth harvest, accounting for about 11-13% of the total DM yield. The total dry matter production (in four harvests) was 4,218 kg/ha higher when alfalfa was subjected to a cutting height of 5 cm rather than 25 cm. Cutting height had no effect on total crude protein yield, but from the first to fourth cutting, the protein yield followed a decreasing trend. Finally, there were visible declines in forage nutritive quality when alfalfa was cut at a shorter height. However, the magnitude of difference in total forage yield may outweigh the slight decline in forage quality when alfalfa is cut at a lower height. The findings of this study could help the alfalfa growers make better harvest management decisions.

• Asian-Australasian Journal of Animal Sciences
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• v.14 no.8
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• pp.1090-1097
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• 2001

Nine tons of fresh rice straw from early-maturing varieties was ensiled with 50 g urea $kg^{-1}$ DM straw in plastic bags immediately after threshing. Five months after storage, preserved straw was used to partially replace elephant grass (Pennisetum purpureum, Schumach) for lactating cows. Eight crossbred Holstein lactating cows (75% of Holstein blood) in their second to fourth lactation and in mid-lactation were arranged in a balanced design with two squares consisting of $4\;periods{\times}4\;treatments$ (100% grass ad lib. as a control; 75% grass+urea treated fresh rice straw (UTrFRS) ad lib.; 50% grass+UTrFRS ad lib.; 25% grass+UTrFRS ad libitum) in one square. A concentrate supplement was given at a rate of 400 g per day per kg of milk produced. Samples of fresh straw taken in the field and UTrFRS and elephant grass taken at feeding time were evaluated in a degradation trial with 3 fistulated heifers (undefined blood ratio of crossbred of Sindhi and local yellow cattle). Straw preserved for 5-9 months was in nearly all cases of good quality. Crude protein (CP) content was increased 2.1 fold and 48 h dry matter loss (DML) was 20% higher compared to dry straw. Elephant grass cultivated intensively was low in DM content and 10% higher in 48 h DML compared to UTrFRS. Dry matter intake (DMI) was higher for the mixture of UtrFRS and Elephant grass, and highest when one-third of the roughage was UTrFRS. Higher DMI of mixed roughage diets was probably due to the low DM content of elephant grass in the sole grass roughage diet. Increasing substitution of elephant grass with UTrFRS up to 75% of the roughage component increased milk fat content and had no effect on milk yield and other milk composition parameters. Feeding UTrFRS, partially replacing elephant grass in the diets of lactating cows in the dry season can reduce the cost of roughage.

• Journal of the Korea Institute of Military Science and Technology
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• v.20 no.5
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• pp.700-707
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• 2017

Recently, the military need more various education and training because of the increasing necessity of various operation. But the education and training of the military has the various difficulties such as the limitations of time, space and finance etc. In order to overcome the difficulties, the military use Defense Modeling and Simulation(DM&S). Although the participants in training has the empirical knowledge from education and training based on the simulation, the empirical knowledge is not shared because of particular characteristics of military such as security and the change of official. This situation obstructs the improving effectiveness of education and training. The purpose of this research is the systematizing and analysing the empirical knowledge using text mining and network analysis to assist the sharing of empirical knowledge. For analysing texts or documents as the empirical knowledge, we select the text mining and network analysis. We expect our research will improve the effectiveness of education and training based on simulation of DM&S.

• Journal of Technologic Dentistry
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• v.34 no.1
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• pp.25-36
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• 2012

Purpose: The purpose of this study is to investigate the status of oral health behaviors and oral health status, and to analysis the association between health behavior and chronic disease and oral health status of male workers. Methods: The survey used structured self administered questionnaires from September to October in 2009 in Daegu and Gyeongsangbuk-do province, randomize thirty workplace which work more than 50 workers and carry out a survey targeting 30 to 50 age male laborers who work selected workplace. Total of 1,532 replies were analysed. Results: Age, education, monthly income, job was significantly associated with number of toothbrushing, scaling experience, number of missing teeth. Smoking, amount of smoking, frequency of drinking, number of tooth brushing, unmet need and subjective oral health condition, HBP and DM was significantly associated with the number of missing teeth. In logistic regression, age(above 40), monthly income and DM were significant factors on loss of teeth. Conclusion: In conclusion, it is important to provide education on the teeth-brushing and DM management to workers engaged in a small or medium sized workplace with many tooth loss and low educational status, and to recommend a regular scaling as well as to establish policy for creating conditions upon an oral health check-up and a tooth scaling and allow the maintenance of an oral health.

• Asian-Australasian Journal of Animal Sciences
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• v.21 no.11
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• pp.1604-1609
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• 2008

A series of in vitro and in vivo experiments were conducted to investigate the effects of the mixture of Tween 80 and cellulolytic enzymes (xylanase and cellulase) on total tract nutrient digestibility and rumen cellulolytic bacterial adhesion rates in Holstein steers. Ground timothy hay sprayed with various levels of Tween 80 and cellulolytic enzymes was used as substrates in an in vitro experiment to find out the best combinations for DM degradation. The application level of 2.5% (v/w) Tween 80 and the combination of 5 U xylanase and 2.5 U cellulase per gram of ground timothy hay (DM basis) resulted in the highest in vitro dry matter degradation rate (p<0.05). Feeding the same timothy hay to Holstein steers also improved in vivo nutrient (DM, CP, CF, NDF and ADF) digesibilities compared to non-treated hay (p<0.05). Moreover, Tween 80 and enzyme combination treatment increased total ruminal VFA and concentrations of propionic acid and isovaleric acid with decreased acetate to propionate ratio (p<0.001). However, adhesion rates of Fibrobacter succinogenes and Ruminococcus flavefaciens determined by Real Time PCR were not influenced by the treatment while that of Ruminococcus albus was decreased (p<0.05). The present results indicate that a mixture of Tween 80 and cellulolytic enzymes can improve rumen environment and feed digestibility with variable influence on cellulolytic bacterial adhesion on feed.