• Journal of Wetlands Research
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• v.9 no.1
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• pp.69-78
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• 2007

Constructed wetlands and other aquatic systems have been successfully used for waste and wastewater treatment in either temperate or tropical regions. To treat waste or wastewater in a sustainable manner, the integrated eco-engineering designs are explained in this paper with 2 case studies: (i) a combination of vertical-flow constructed wetland (CW) with plant irrigation systemfor fecal sludge management and (ii) integrated CW units with landscaping at full-scale application for domestic wastewater treatment. The pilot-scale study of fecal sludge management employed 3 vertical-flow CW units, each with a dimension of $5{\times}5{\times}0.65m$ (width ${\times}$ length ${\times}$ media depth) and planted with cattails (Typha augustifolia). At the solid loading rate of 250 kg total solids (TS)/$m^2.yr$ and a 6-day percolate impoundment, the CW system could achieve chemical oxygen demand (COD), TS and total Kjeldahl nitrogen (TKN) removal efficiencies in the range of 80 - 96%. The accumulated sludge layers of about 80 - 90 cm was found at the CW bed surface after operating the CW units for 7 years, but no clogging problem has been observed. The CW percolate was applied to 16 irrigation Sunflower plant (Helianthus annuus) plots, each with a dimension of $4.5{\times}4.5m$ ($width{\times}length$). In the study, the CW percolate were fed to the treatment plots at the application rate of 7.5 mm/day but the percolate was mixed with tap water at different ratio of 20%, 80% and 100%. Based on a 1-year data of 3-crop plantation were experimented, the contents of Zn, Mn and Cu in soil of the experimental plots were found to increase with increasing in CW percolate ratios. The highest plant biomass yield and oil content of 1,000 kg/ha and 35%, respectively, were obtained from the plots fed with 20% or 50% of the CW percolate, whereas no accumulation of heavy metals in the plant tissues (i.e. leaves, stems and flowers) of the sunflower is found. In addition to the pilot-scale and field experiments, a case study of the integrated CW systems for wastewater treatment at Phi Phi Island (a Tsunami-hit area), Krabi province, Thailand is illustrated. The $5,200-m^2$ CW systems on Phi Phi Island are not only for treatment of $400m^3/day$ wastewater from hotels, households or other domestic activities, but also incorporating public consultation in the design processes, resulting in introducing the aesthetic landscaping as well as reusing of the treated effluent for irrigating green areas on the Island.

• Magazine of the Korean Society of Agricultural Engineers
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• v.35 no.4
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• pp.55-66
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• 1993

Upon freezing a soil swells due to phase change and its compression stress increase a lot. As the soil undergo thawing, however, it becomes a soft soil layer because the 'soil changes from a solid state to a plastic state. These changes are largely dependent on freezing temperature and repeated freezing-thawing cycle as well as the density of the soil and applied loading condition. This study was initiated to describe the effect of the freezing temperature and repeated freezing-thawing cycle on the unconfined compressive strength. Soil samples were collected at about 20 sites where soil structures were installed in Kangwon provincial area and necessary laboratory tests were conducted. The results could be used to help manage effectively the field structures and can be used as a basic data for designing and constructing new projects in the future. The results were as follows ; 1. Unconfined compressive strength decreased as the number of freezing and thawing cycle went up. But the strength increased as compression speed, water content and temperature decreased. The largest effect on the strength was observed at the first freezing and thawing cycle. 2. Compression strain went up with the increase of deformation speed, and was largely influenced by the number of the freezing-thawing cycle. 3. Secant modulus was responded sensitivefy to the material of the loading plates, increased with decrease of temperature down to - -10$^{\circ}$C, but was nearly constant below the temperature. Thixotropic ratio characteristic became large as compression strain got smaller and was significantly larger in the controlled soil than in the soil treated with freezing and thawing processes 4. Vertical compression strength of ice crystal(development direction) was 3 to 4 times larger than that of perpendicular to the crystal. The vertical compression strength was agreed well with Clausius-Clapeyrons equation when temperature were between 0 to 5C$^{\circ}$, but the strength below - 5$^{\circ}$C were different from the equation and showed a strong dependency on temperature and deformation speed. When the skew was less then 20 degrees, the vertical compression strength was gradually decreased but when the skew was higher than that, the strength became nearly constant. Almost all samples showed ductile failure. As considered above, strength reduction of the soil due to cyclic freezing-thawing prosses must be considered when trenching and cutting the soil to construct soil structures if the soil is likely subject to the processes. Especially, if a soil no freezing-thawing history, cares for the strength reduction must be given before any design or construction works begin. It is suggested that special design and construction techniques for the strength reduction be developed.

• Journal of The Korean Society of Grassland and Forage Science
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• v.6 no.1
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• pp.65-70
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• 1986

This experiment was carried out to identify the main pathogens infected with Piper sudangrass and to evaluate the qualitative and quantitative damage of the plants infected with leaf blight (Helminthosporium turcicum PASS) under different levels of nitrogen fertilizer (20, 30 and 40 kg/10a). The experiment was design as a randomized block design with 4 replications at experimental field of Livestock Experiment Station in Suweon, 1984. The results obtained are summarized as follows: 1. The main fungi isolated from sudangrass were identified as Helminthoporium turcicum and Collectotricum graminicolum, but 1 species fungus was not identified. 2. Leaf blight was first found on June 20 and appeared extremely in the regrowth plants from July to September. The rate of attack was associated with increasing of nitrogen fertilization (P<0.01). 3. Fresh and dry matter yields were as much as 47 and 38 percentage lower in leaf blight infected plants (disease severity: V) than those of no visible infection. 4. Concentrations of crude fat and crude protein were decreased in the plants infected with Helminthosporium leaf blight, but lignin content was increased. Dry matter and organic matter digestibility of the plants were negative correlated with the infection of leaf blight(P<0.01).

• Journal of the Korea institute for structural maintenance and inspection
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• v.22 no.1
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• pp.81-89
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• 2018

Austenitic stainless steels have excellent corrosion resistance, durability and fire resistance. Especially, since STS304L among austenitic types is a low-carbon variation of STS304 and has excellent intergranular corrosion resistance, it can often be used under the welded condition without heat treatment after field welding. This paper investigated ultimate behaviors such as ultimate strength and weld metal fracture mechanism of STS304L fillet-welded connections with TIG(tungsten inert gas) welding through test results. Main variables of specimens are weld length and welding direction against loading. Fracture of specimens are classified into three modes(tensile fracture, shear fracture and block shear fracture). Ultimate strengths were compared according to the welding direction and weld length and TFW series with transverse fillet weld had the highest strength compared with other types(LFW series with longitudinal fillet weld and FW series with all round weld). It is known that current design specifications such as KBC 2016 and AISC2010 underestimated the strength of TFW and LFW specimens and provided unconservative estimates for FW specimens. Finally, strength equations were proposed considering material properties of STS 304L material.

• Journal of the Korea institute for structural maintenance and inspection
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• v.22 no.4
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• pp.1-9
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• 2018

The development of new technology and process in industrial Plant which builds integrated structures, facilities and systems. Has become a key element for strengthening its competitiveness. Although domestic industrial Plant has demonstrated excellence in technology with a persistent increase in order quantity and orders received, the technology gap between countries has narrowed due to global construction trend. Therefore, it is necessary to develop new technology that could help overcome constraints and limitations of the current one to follow the trend in the age of unlimited competition. This study has focused on assembly technology of Pipe-rack joint connection in an effort to strengthen technological competitiveness in industrial Plant. Through an analysis of earlier studies on Pipe-rack and a coMParative analysis of strengths and weaknesses of current assembly technology of it, a new design plan has been made to improve it efficiently. In doing this, standards for design factors of both structural and performance features have been drawn, and value of stress, strain, moment and rotation has been calculated using finite element analysis. As a result, installation technology of modular type Pipe-rack, which has not been developed in Korea and is differentiated from the current one, has been developed. It is considered that the technology reduces work time and saves cost due to simplified joint connection of steel structure, unlike the current one. Moreover, since it is installed without a welding process in the field, industrial accidents would be reduced, which is likely to have economic competitiveness and satisfy.

• Journal of the Korea Institute of Building Construction
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• v.11 no.4
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• pp.326-332
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• 2011

Carbon, Aramid, Boron and Glass fibers are used as fibrous materials to promote structural bearing strength. Of these fiber types, carbon fiber is the most commonly used material, and is characterized by having a one-way direction, which is strengthened by tensile strength due to the attached direction only, while other types of fibers are two-way. Therefore, when applied in the field, the attachment direction of fiber is a very important factor. However, when fiber direction is not mentioned in the design drawing, there sometimes is no improvement in structural strength, as the fiber is being installed by a site engineer or workers who lack structural knowledge. The purpose of this study was to propose an optimal direction of carbon fiber through a comparison & analysis of reinforcing efficiency with reinforced experimental columns that used carbon fibers in each of the inclined, horizontal and vertical directions. According to the results, horizontal direction in the reinforced column was improved by 153.43%, but vertical direction was 104.61% only, and it was understood this was due to increased tensile strength along the fiber direction. For this reason, it is necessary to include information regarding fiber direction in design and site management.

• Journal of dental hygiene science
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• v.18 no.4
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• pp.201-209
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• 2018

The aim of this study was to identify bibliographic characteristics and research trends of articles published on the elderly people in dental hygiene. An analysis was done of 191 articles published from 1999 to 2017. Bibliographic characteristics were nine items such as publication journal, research design, research participants, number of researchers, data analysis method, keywords, research topic, and validity and reliability report. The collected data were analyzed using descriptive statistics of statistical program. First, the research on the elderly, which was published in dental hygiene, started to be published in 1999 and on going. Though major publications have been published in Journal of Korean Society of Dental Hygiene and Journal of Dental Hygiene Science, the kinds of journals are becoming diverse. Second, cross-sectional research was the most. Third, the elderly were the most studied subjects, but the criteria varied. Fourth, the number of authors was largest in order of two and three person. Fifth, data analysis method was in order of descriptive statistics, t-test, and ANOVA. Sixth, there were many duplication of keywords about oral, elderly, and health. Seventh, oral health behavior science was the most studied subject. Eighth, validity and reliability were reported at 27.4% and 51.6%, respectively. Ninth, only 15.7% of study was founded research funding. Based on the results of this study, we consider increase experimental research further. Therefore, it is recommeded that validity and reliability should be reported in research paper, and the keywords used in the field of dental hygiene should be agreed upon.

• The Journal of Korea Institute of Information, Electronics, and Communication Technology
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• v.10 no.6
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• pp.487-495
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• 2017

The thermal characteristics of the electrodeless lamp are one of the main factors that determine the design and performance of the lamp. The coupler changes the impedance characteristic by heat and its use temperature is usually within about $150^{\circ}C$. In this study, we observed the phenomenon when the coupler was exposed at a temperature of $150^{\circ}C$ or higher, which has not been discussed so far. Two types of coupler A and coupler B with different spacing between the inner tube and the coupler were analyzed for electrical, thermal and optical properties and deterioration characteristics with different heat and heat shielding conditions. First, the impedance of the system is obtained and used as a criterion for analyzing the electrical characteristics through it. The diameters of the two types of couplers are 1 mm, and the experimental result shows that the coupler diameter is 1 mm, which can cancel out the loss of the magnetic field strength. Therefore, based on these results, when the coupler is exposed to high temperature of about $200^{\circ}C$, the efficient design method corresponding thereto is proposed.

• Journal of Korea Society of Industrial Information Systems
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• v.29 no.2
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• pp.55-68
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• 2024

Plant engineering companies create or refer to requirements documents for each related field, such as plant process/equipment/piping/instrumentation, in different engineering departments. The process-related requirements document includes not only a description of the process but also the requirements of the equipment or related facilities that will operate it. Since the authors and reviewers of the requirements documents are different, there is a possibility that inconsistencies may occur between equipment or parts design specifications described in different requirement documents. Ensuring consistency in these matters can increase the reliability of the overall plant design information. However, the amount of documents and the scattered nature of requirements for a same equipment and parts across different documents make it challenging for engineers to trace and manage requirements. This paper proposes a method to analyze requirement sentences and calculate the similarity of requirement sentences in order to identify semantically identical sentences. To calculate the similarity of requirement sentences, we propose a named entity recognition method to identify compound words for the parts and properties that are semantically central to the requirements. A method to calculate the similarity of the identified compound words for parts and properties is also proposed. The proposed method is explained using sentences in practical documents, and experimental results are described.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.34 no.1
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• pp.60-73
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• 1989

Two field experiments were carried out to assess the applicability of a central composite design (CCD) in determining optimum culture condition of an early rice cultivar, Unbongbyeo in southern Korea. A central composite design with two replicates was applied to five levels of five factors such as the number of hills per 3.3m2, the number of seedlings per hill, the levels of nitrogen, the transplanting date and the seedling age (Experiment 1). The levels of planting density were ranged from 30 hills to 150 hills per 3.3m2 ; the number of seedlings per hill from 1 seedling to 9 seedlings per hill; the levels of nitrogen application from 1 kg/l0a to 21 kg/l0a; the transplanting date from June 15 to July 5; the seedling age from 25 days to 45 days. A fractional factorial design was applied to three levels of five factors tested in CCD (Experiment 2). Yield per hill and per unit area were examined and the results obtained from both experiments were compared. The benefits from the central composite design were discussed. Maximum yield of brown rice per unit area was obtained at the combination of the central levels of one of five factors when the other four factors were fixed at central point. Furthermore, brown rice yield per unit area affected by interaction of two factors was maximized at the central point when the remain three factors being fixed at the central level. The responses of five factors to brown rice yield per hill and unit area were found to be a saddle point in both designs. Actual values of the stationary points were 107 hills per 3.3 m2, 4 seedlings per hill, 10 kg nitrogen per l0a, transplanting date of rice on June 26 and 33 days of seedling age in the central composite design. Brown rice yield per unit area at the stationary points were estimated 439 kg/l0a in the central composite design and 442 kg/l0a in the fractional factorial design. Considering the number of experimental treatment combinations, the central composite design was rather convenient in reducing the number of treatment combinations for similar information. It was more convenient for an experimenter to present the results from the central composite design than those from the fractional factorial design. Considering the optimum yields of brown rice per unit area at the stationary points being verified as saddle points in both designs. inter-heterogeneity of each of the factors should be avoided in setting up factors in pursuit of inducing unidirectional response of the factors to yield. Even though both the lower and higher levels in the central composite design being beyond the region of an experimenter's interest. they were considered highly valued in interpretation of the results. Conclusively. the central composite design was found to be more beneficial to optimize culture condition of paddy rice even with several levels of various factors were involved.