• Journal of the Korea institute for structural maintenance and inspection
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• v.13 no.6 s.58
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• pp.135-147
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• 2009

In order to develop the ultra high strength concrete over 400Mpa at 28 day, Low-heat portland cement, ferro-silicon, silica-fume and steel fiber were mixed and tested under the special autoclave curing conditions. Considering the influence of Ultra high strength concrete. normal concrete is used as a comparison with low water-cement ratio possible Low-heat portland cement. Additionally, as a substitution of aggregates, we analyzed the compressive strength of Ferro Silicon by making the states of mixed and curing conditions differently. In addition, SEM films testified the development of C-S-H hydrates of Type III & Type IV, and tobermolite, zonolite due to the high temperature, high pressure of autoclave curing. Fineness of aggregate, filler and reactive materials in concrete caused 420Mpa compressive strength at 28day successfully.

• Journal of Powder Materials
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• v.19 no.2
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• pp.127-133
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• 2012

The sintering behaviors and process parameters of some compounds (carbides, oxides, sulfides, borides) were investigated experimentally. These compounds were successfully consolidated and showed high densities. Some unique phenomena such as retardation of grain growth, suppression of thermal decomposition and maintenance of initial non-equilibrium phases, were observed by the proper control of process in spark sintering.

• Proceedings of the KIEE Conference
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• 2015.07a
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• pp.1060-1061
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• 2015

This paper presents the control method of MPPT (Maximum Power Point Tracking) using back-to- back converter. The windturbine system use PMSG(ermanent Magnet Synchronous Generator) system considering low maintenance costs and driving performance at low wind. This paper use the adaptive sliding mode control to the torque control. Proposed method was analyzed mathematically.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.14 no.9
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• pp.4560-4571
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• 2013

Current global issue of climate change is growing and greenhouse gases occur in most cities. To solve the problem of climate change, the city should be changed to low-carbon structure. Low-carbon city planning is a step-by-step plan from the initial establishment, from design and operation of urban structure, to maintenance and management should be considered as an integrated whole process. Under this background, this study evaluated the whole process of low-carbon urban planning ways. For this step, divided into three steps and eight divisions, 30 sub-indicators are derived. Through domestic and foreign cases analysis studies and survey of the relevant experts, results were derived. In order to improve these points, in the intial planning establishment stage, planning of urban policy and institutional steps should be made and the plan should be appropriate to the local characteristics. In the design and operation of urban structure stage, detailed and feasible approach is needed and maintenance and management stage, participation of various stakeholders, including establishing governance and management practices could see the need.

• Asian-Australasian Journal of Animal Sciences
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• v.25 no.3
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• pp.410-420
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• 2012

A trial was conducted to: i) evaluate the BW growth, energy intakes and energetic efficiency of pigs fed high and low density diets from 27 to 141 kg BW, ii) evaluate sire line and sex differences when fed both diets, and iii) to compare ME to NE as predictor of pig performance. The experiment had a replicated factorial arrangement of treatments including four sire lines, two sexes (2,192 barrows and 2,280 gilts), two dietary energy densities and a light or heavy target BW, 118 and 131.5 kg in replicates 1 to 6 and 127 and 140.6 kg in replicates 7 to 10. Pigs were allocated to a series of low energy (LE, 3.27 Mcal ME/kg) corn-soybean meal based diets with 16% wheat midds or high energy diets (HE, 3.53 to 3.55 Mcal ME/kg) with 4.5 to 4.95% choice white grease. All diets contained 6% DDGS. The HE and LE diets of each of the four phases were formulated to have equal lysine:Mcal ME ratios. Pigs were weighed and pen feed intake (11 or 12 pigs/pen) recorded at 28-d intervals. The barrow and gilt daily feed (DFI), ME (MEI) and NE (NEI) intake data were fitted to a Bridges function of BW. The BW data of each sex were fitted to a generalized Michaelis-Menten function of days of age. ME and NE required for maintenance (Mcal/d) were predicted using functions of BW (0.255 and 0.179 BW^0.60 respectively). Pigs fed LE diets had decreased ADG (915 vs. 945 g/d, p<0.001) than pigs fed HE diets. Overall, DFI was greater (p<0.001) for pigs fed the LE diets (2.62 vs. 2.45 kg/d). However, no diet differences were observed for MEI (8.76 vs. 8.78 Mcal/d, p = 0.49) or NEI (6.39 vs. 6.44 Mcal/d, p = 0.13), thereby indicating that the pigs compensated for the decreased energy content of the diet. Overall ADG:DFI (0.362 vs. 0.377) and ADG:Mcal MEI (0.109 vs. 0.113) was less (p<0.001) for pigs fed LE compared to HE diets. Pigs fed HE diets had 3.6% greater ADG:Mcal MEI above maintenance and only 1.3% greater ADG:Mcal NEI (0.152 versus 0.150), therefore NEI is a more accurate predictor of growth and G:F than MEI.Pigs fed HE diets had 3.4% greater ADG:Mcal MEI and 0.11% greater ADG:NEI above maintenance than pigs fed LE diets, again demonstrating that NEI is a better predictor of pig performance than MEI. Pigs fed LE diets had similar daily NEI and MEI but grew slower and less efficiently on both ME and NE basis than pigs fed HE diets. The data suggest that the midds NE value (2.132 Mcal/kg) was too high for this source or that maintenance was increased for pigs fed LE diets.

• Journal of the Korean GEO-environmental Society
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• v.14 no.3
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• pp.35-40
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• 2013

In most cases, Geotechnical Structures installed in freezing areas require extra countermeasures for reducing freeze damage. However, in terms of domestic tunnels, studies and case reports for geotechnical structures such as tunnels and retaining walls are not fluently carried out, causing lack of research about ways to decrease freeze damage. For these causes, domestic design criteria about structures does not specifically institutionalization for geotechnical structures. This research have done on-site investigation about tunnels, cut slopes and retaining walls. Also, this research includes the process of analyzing the histories of maintenance for class 1 and class 2 structures that happened in the past 40 years, studying characteristics of structure's maintenance and reinforcement in different areas with different climate. As the result, it was analyzed that domestic geotechnical structures showed need for longer maintenance and reinforcement that are located in Gangwon mountain area, Gangwon north region and Gyeonggi north region where the temperature is relatively low. This research can be concluded in need for revision of design criteria for structures located in freeze damage area.

• Land and Housing Review
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• v.4 no.4
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• pp.303-316
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• 2013

This paper examines the achievements and limitations of housing assistance programs for low-income households. Korean public rental housing has been rapidly developing since 2000, and thereby achieved an increase in public rental housing stock, housing quality improvements, and the reduction of rent over-burden for low-income tenants. Despite some conflicting evidence, it appears that the provision of newly-built public rental housing has helped stabilize the prices of neighboring private rental housing units. But, as we are entering an era of one million long-term public rental housing units, we need to shift our focus from quantity-oriented provision to housing maintenance for tenants, and from cost-based rental housing to affordable rental housing and better access to rental housing for low-income tenants who are not beneficiaries of government assistance. Most of all, it is very important for local governments and the private sector to actively participate in the provision of public rental housing in order to ensure a stable rental housing market.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.16 no.5
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• pp.1735-1754
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• 2022

The reliability and performance of WiFi need optimization because of the rising number of WiFi users day by day. A highlighted point is saving power while transmitting and receiving packets using WiFi devices. Wake-on-Wlan (WoW) is also implemented to improve energy consumption, but it also needs betterment. This paper will introduce universal ideas to transmit and receive packets using low-power technology like Bluetooth or BLE (Bluetooth low energy). While looking for power-saving ways in this research, WiFi connection and maintenance also take care using lesser power-consuming technology. Identifying different use-cases where low power technology can help save energy and maintain 802.11 connection is part of the research. In addition, the proposed method discuss energy saving with unicast and broadcast/multicast data. Calculation of power-saving and comparison with standalone WiFi usage clearly shows the effectiveness of the proposed method.

• Journal of Korean Clinical Nursing Research
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• v.19 no.1
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• pp.45-56
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• 2013

Purpose: The purpose of this study is to identify the effect of low sodium dialysate (LSD) rather than conventional dialysate on interdialytic weight gain (IWG), blood pressure (BP), and intradialytic side-effects (ISEs) in patients on maintenance hemodialysis (HD). Methods: The study was performed in 43 patients, who were treated in the university hospital over 8 weeks. Each participant's serum sodium set point was measured using dialysate sodium 140 mEq/L during the first 4 weeks. For the next 4 weeks dialysate sodium concentrate (134,136,and138 mEq/L) was provided to each participant but only to an experimental group (EG) (n=22) based on the individual set point, although 140 mEq/L dialysate was given to all of the control group (CG) (n=21). Consequently, outcomes including IWG, BP, and ISE were evaluated. Results: In EG, difference of pre-HD SBP (p=.047) and post-HD serum sodium (p=.006) were significantly decreased compared to CG. Also, ISEs was not more frequent in EG. However, the differences were not statistically significant, IWG (kg & %), pre-HD DBP, post-HD SBP & DBP, and serum osmolality in EG. Conclusion: Individual application of LSD in patients on maintenance hemodialysis is beneficial to decrease pre-HD SBP and post-HD serum sodium without increasing ISE. Therefore, LSD can be better treatment than conventional dialysate.

• Asian-Australasian Journal of Animal Sciences
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• v.17 no.11
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• pp.1586-1590
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• 2004

An experiment was carried out with day-old "Sonali" (♂RIR$\times$♀Fayoumi) chicks to investigate the efficacy of locally made low cost brooders for brooding chicks in rural areas. Three types of indigenous brooders viz. charcoal, haricane and sawdust brooders were used for brooding chicks throughout the experimental period of 28 days. The efficiency of the brooders was observed in respect of their ability to maintain temperature, fluctuation in temperature during operation and cost effectiveness. Following initial trial of temperature maintenance for 48 h, the chicks were put under the brooder stoves and brooded up to 28 days. The experimental birds were fed on chick starter diet. Maintenance of temperature with sawdust brooders was found satisfactory and optimum for brooding the chicks at different stages of brooding and at the same time involved least cost for brooding in comparison with charcoal and haricane brooders which did not perform well in generating heat necessary for brooding and were not economically feasible for poor farmers. On the other hand, performance of charcoal brooders was better in respect of temperature maintenance during initial stage (when the brooder was started) but the temperature fluctuated rapidly, whereas fluctuation of temperature was gradual in sawdust brooders. Body weight gain and feed conversion were best in sawdust brooders. Survivability was highest in sawdust brooders and lowest in haricane brooders. Sawdust brooders may be appropriate for brooding chicks in rural areas, where electricity is not available.