• Journal of Korea Technical Association of The Pulp and Paper Industry
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• v.47 no.5
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• pp.5-14
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• 2015

Recently, the use of wood resources has been limited due to global environmental change, like global warming and desertification. It is very critical in Korea's paper industries because lots of virgin pulp are dependant on direct import from abroad for printing grade of paper. In this work, the alternatively best available technique for reducing the import amounts of BKP (bleached Kraft pulp) was considered by mixing DIP (deinked pulp) and TMP (thermomechanical pulp) for the manufacture of high quality paper. Generally known, the sheet prepared from fibrous raw materials of DIP and TMP has lower strength and optical properties than that prepared from BKP. This study was aimed to improve the sheet quality by using DIP and TMP. 4 kinds of polyelectrolytes were approached to find out the best effects on physical strength and optical brightness improvements, and high retention behaviors with GCC (ground calcium carbonate). In conclusion, amphoteric PAM with 1,000,000 molecular weight (g/mol) and 0.5 charge density (meq/g) was best for the improvement of strength properties with the mixture of DIP and TMP. GCC retention rate was also the highest with cationic-PAM of above 2,000,000 molecular weight (g/mol) and about 2.0-3.0 charge density (meq/g) of strengthening agent.

• Journal of the Korean Society of Propulsion Engineers
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• v.18 no.6
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• pp.19-26
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• 2014

A ground hot-firing test (HFT) was carried out to make a close examination into the pressure instability for the 70 N-class hydrazine thruster under development. Monopropellant grade hydrazine was adopted as a propellant for the HFT, and catalyst-bed was filled with $Ir/Al_2O_3$ catalyst. In order to investigate the effects of thrust-chamber diameter on combustion stability, evaluation tests for the development models were performed on three kinds of lower thrust chambers having the length-to-diameter ratio (L/D) of 1.03, 1.13, and 1.26. As results, it was found that low frequency instability (~ 50 Hz) was inherent in the models, and in addition, increase of the L/D and decrease of the operating pressure led to an amplification of pressure oscillation in the test condition specified.

• Journal of the Society of Disaster Information
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• v.16 no.1
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• pp.60-69
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• 2020

Purpose: Cavity growth process monitoring is to periodically monitor changes in common size and topography for general and observational grades to predict the rate of common growth. The purpose of this study is to establish a systematic cavity management plan by evaluating the general and observational class community in a non-destructive method. Method: Using GPR exploration equipment, the acquired surface image and the surrounding status image are analyzed in the GPR probe radargram in depth, profile, and cross section of the location. The exact location is selected using the distance and surrounding markings shown on the road surface of the initial detection cavity, and the test cavity is analyzed by calling the radar at the corresponding location. Result: As a result of monitoring tests conducted at a cavity 30 sites of general and observation grade, nine sites have been recovered. Changes in scale were seen in 21 cavity locations, and changes in size and grade occurred in 13 locations. Conclusion: The under road cavity is caused by various causes such as damage to the burial site, poor construction, soil leakage caused by groundwater leakage, waste and ground vibration. Among them, indirect factors could infer the effects of groundwater and localized rainfall.

• Journal of the Korean Society of Environmental Restoration Technology
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• v.15 no.3
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• pp.45-54
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• 2012

This study intended to analyze growth condition of each object by protected tree's ground for 45 places registered to Pyeongtaek protected tree list in locational characteristics, conduct exchange analysis for impediment extent rate in crown area and tree type to the result and suggest the measures to manage artificial impediment which is an effect on protected tree condition. In this study, the tree whose area of impediment for crown area is less than 21% is tree condition of grade 1~2, less than 21~50% is grade 2~3 and more than 50% is grade 3~5. The more impediment is, the more inconvenience causes on growth and development. So, it verified that the area rate must maintain less than 21% for the root system management of protected tree. For the standard of managing artificial impediment which is an effect on the tree condition of protected trees, the below matters intend to be suggested. The first, the impediment in crown area should be less than 21%. But, if there is not artificial impediment out of crown area, the rate of impediment area is considered to increase somewhat. The second, growth space of protected tree should be maintained by crown area at least and impediment should be established out of the crown area. The third, during the national project and land development, surroundings of protected tree must be applied as park, resting place, etc. and the establishment area of impediment (artificial impediment and natural impediment) in crown area must be limited. The forth, publicity for regional people (especially, land owner) is necessary for the protection of natural inheritance and the value of dependence on local government and village which are the subject of management must be announced widely through the internet media, etc, so its importance must be recognized. The fifth, the matters related to protected tree management must be able to limit artificial damage which is for surroundings of protected tree through the mutual connection among the local governments; construction, civil engineering, architecture, water and sewage, agriculture and forest and others. Also, following studies on the effects of kinds, thickness, etc. of impediment around the protected tree on trees should be continued.

• Journal of the Korean Society of Environmental Restoration Technology
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• v.22 no.3
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• pp.55-71
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• 2019

The purpose of this study is to propose an evaluation method to assess green environments of streetscapes to improve urban street green spaces in Jeonju City. Through a rapid assessment of urban street green spaces, we suggest an objective basis for expanding street green space as well as for adopting sustainable maintenance and improvement measures. We choose 12 sections of streetscapes (roads and sidewalks) to investigate existing street conditions which have more than four lanes and function as major road axes. Six large roads and six medium roads of Jeonju City center area are investigated as pilot assessment study sites. Site inventory checklists consist of environmental characteristics of streetscape, street tree status, and planting condition evaluation. Environmental characteristics of streetscapes are composed of physical and neighborhood factors. For instance, items for physical factors are types and width of road/sidewalks, paving materials, tree protection materials, and green strip. And surrounding landuse is a neighborhood factor. Assessment items for street tree status are street plant names (tree/shrubs/ground cover), size, and planting intervals. Planting condition evaluation items are tree shape, damage, canopy density, and planting types with existence of adjacent green space. Evaluation results are classified into three levels such as A(maintain or repair), B(greening enhancement), and C(structural improvement). In case of grade A, streetscapes have enough sidewalk width for maintaining green strip and a multi-layered planting(in large road only) with fairly good growing conditions of street trees. For grade B and C, streetscapes have a moderate level of sidewalk width with a single street tree planting. In addition, street tree growing conditions are appeared poor so that green enhancement or maintenance measures are needed. For median, only grade B and C are found as its planting growing foundations are very limited in space. As a result, acquiring enough sidewalk space is essential to enhance ecological quality of urban street green. Especially, it is necessary to have green strip with reasonable widths for plant growing conditions in sidewalks. In addition, we need to consider native species with multi-layer plant compositions while designing street green.

• Korean Journal of Materials Research
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• v.26 no.6
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• pp.306-310
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• 2016

To produce 4N grade high-purity silica powder from natural ore, the mineralogical characteristics of natural silica ore were investigated and their effects on the purification process were revealed. The Chinese silica mineral ore used was composed of iron and aluminum as main impurities and calcium, magnesium, potassium, sodium, and titanium as trace impurities; these trace impurities generally exist as either single oxides or complex oxides. It was confirmed that liberation and acidic washing of the impurities were highly dependent on the particle size of the ground silica ore and on its mineralogical characteristics such as the distribution and phases of existing impurities. It is suggested that appropriate size reduction of silica ore should be realized for optimized purification according to the origin of the natural silica ore. A single step purification process, the mechano-chemical washing (MCW) process, was proposed and verified in comparison with the conventional multi step washing process.

• Asian-Australasian Journal of Animal Sciences
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• v.12 no.4
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• pp.554-557
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• 1999

Hatchery waste including infertile eggs, dead embryos in shell, dead or low grade chicks was cooked at $100^{\circ}C$ for 15 minutes and then oven dried and ground. Hatchery waste meal (HWM) thus prepared contained 44.25% protein, 4,573 kcal/kg gross energy, 3,600 kcal/kg metabolizable energy, 30% ether extract, 1.9% fibre, 14% ash, 9.8% nitrogen free extract, 7.26% Ca, 0.84%P, 1.86% lysine and 0.66% methionine with no Salmonella and E. coli. In biological evaluation trial, significantly higher weight gain was observed in ration containing 12% HWM compared with that containing similar amount of fish meal. Protein efficiency ratio on the two rations was 3.96 vs 2.85; protein digestibility, 86.02 vs 71.9; net protein utilization, 64.9 vs 42.37 and biological value, 75.37 vs 58.84, respectively, indicating better balance of amino acids in HWM compared with fish meal. Growth performance trial on broiler chicks also revealed better weight gain and feed efficiency on ration containing 12% HWM than that containing similar level of fish meal.

• Geomechanics and Engineering
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• v.9 no.4
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• pp.427-445
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• 2015

By means of finite element numerical simulation and pseudo-static method, the shallow-buried bilateral bias twin-tube tunnel subject to horizontal and vertical seismic forces are researched. The research includes rupture angles, the failure mode of the tunnel and the distribution of surrounding rock relaxation pressure. And the analytical solution for surrounding rock relaxation pressure is derived. For such tunnels, their surrounding rock has sliding rupture planes that generally follow a "W" shape. The failure area is determined by the rupture angles. Research shows that for shallow-buried bilateral bias twin-tube tunnel under the action of seismic force, the load effect on the tunnel structure shall be studied based on the relaxation pressure induced by surrounding rock failure. The rupture angles between the left tube and the right tube are independent of the surface slope. For tunnels with surrounding rock of Grade IV, V and VI, which is of poor quality, the recommended reinforcement range for the rupture angles is provided when the seismic fortification intensity is VI, VII, VIII and IX respectively. This study is expected to provide theoretical support regarding the ground reinforcement range for the shallow-buried bilateral bias twin-tube tunnel under seismic force.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.10 no.6
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• pp.2689-2708
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• 2016

Multi-camera systems which integrate two or more low-cost digital cameras are adopted to reach higher ground coverage and improve the base-height ratio in low altitude remote sensing. To guarantee accurate multi-camera integration, the geometric relationship among cameras must be determined through platform calibration techniques. This paper proposed a combined two-step platform calibration method. In the first step, the static platform calibration was conducted based on the stable relative orientation constraint and convergent conditions among cameras in static environments. In the second step, a dynamic platform self-calibration approach was proposed based on not only tie points but also straight lines in order to correct the small change of the relative relationship among cameras during dynamic flight. Experiments based on the proposed two-step platform calibration method were carried out with terrestrial and aerial images from a multi-camera system combined with four consumer-grade digital cameras onboard an unmanned aerial vehicle. The experimental results have shown that the proposed platform calibration approach is able to compensate the varied relative relationship during flight, acquiring the mosaicing accuracy of virtual images smaller than 0.5pixel. The proposed approach can be extended for calibrating other low-cost multi-camera system without rigorously mechanical structure.

• Journal of Soil and Groundwater Environment
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• v.22 no.3
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• pp.1-9
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• 2017

The numerical analysis of groundwater flow is indispensable for predicting problems associated with water resource development, civil works, environmental hazards, and nuclear power plant construction. Korea lacks public regulatory procedures and guidelines for groundwater flow modeling, especially in nuclear facility sites, which makes adequate evaluation difficult. Feasible step-by-step guidelines are also unavailable. Consequently, reports on groundwater flow modeling have low-grade quality and often present controversial opinions. Additionally, without public guidelines, maintaining consistency in reviewing reports and enforcing laws is more challenging. In this study, the guidelines for groundwater flow modeling were reviewed for three countries - the United States (Documenting Groundwater Modeling at Sites Contaminated with Radioactive Substances), Canada (Guidelines for Groundwater Modelling to Assess Impacts of Proposed Natural Resource Development Activities), and Australia (Australian Groundwater Modelling Guidelines), with the aim of developing groundwater flow modeling regulatory guidelines that can be applied to nuclear facilities in Korea, in accordance with the Groundwater Act, Environmental Impact Assessment Act, and the Nuclear Safety Act.