• Journal of Biosystems Engineering
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• v.12 no.3
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• pp.30-41
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• 1987

The geometrical shape of a plow bottom may be the most important factor affecting the performance of a plow for a given soil and operating conditions. There are various designs of the Jaenggi (Korean plow) available commercially, which may be different from each other and from the plow (Western plow) in respect to the shape and performance. This study was intended to investigate the geometrical characteristics of Jaenggi. The coordinate digitizer equipped with 3 potentiometers was designed and manufactured for measurement of the shape of curved plane of moldboard and share. The digitizer was connected to a microcomputer having the data acquisition system. This device was used to analyze the plow bottoms of 5 differently-made Jaenggis and one cylindrical plow. The results of the study are summarized as follows: 1. It was possible to measure easily and quickly the curved plane of plow bottom and to plot the view on three major plans using the coordinate digitizer electrically connected to a microcomputer system. 2. The shape of five Jaenggi bottoms analyzed could be characterized by the cutting angle having the range of $33-42^{\circ}$, the maximum share-lift angle of $41-50^{\circ}$, and the setting angle of moldboard wing of $46-70^{\circ}$. The most critical difference of the shape factors between the Jaenggi and the plow was found in the maximum share-lift angle, the former was more than twice as much as the latter. 3. The analysis of the shape of Jaenggi bottoms showed that the share projections on 3 major plans had a varied triangle, which was quite different from that of plow bottom. Especially, it was analyzed that the shape of furrow slice for the Jaenggi had a skewed rectangle, leaving a considerable height of the ridge at the furrow bottom. 4. The dihedral angle was similar range of $30-85^{\circ}$ for the all bodies investigated, but the directional angle was somewhat different from each other. The difference in directional angle was $5^{\circ}$ for the plow, $20^{\circ}$ for the Jaenggi A and $30^{\circ}$ for the Jaenggi B. 5. Area of the spherical representation region was 0.0328 for the plow, 0.1194 for the Jaenggi A and 0.1716 for the Jaenggi B. This may indicate that the plow came close to a working surface and the Jaenggi A and the Jaenggi B departed from a working surface to a somewhat greater extent.

• Journal of Engineering Education Research
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• v.4 no.1
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• pp.57-78
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• 2001

Due to developments in information technology and ensuing changes in the concept of time and space, the significance of national boundaries has been weakened, bringing to attention the heightened competition among nations. In order to respond to these transformations, the Korean government is increasing its efforts to raise the authenticity of the National Technology Qualification System(NTQS) by closely linking NTQS testing method and procedure to practical knowledge and skills in the industry field. This initiative is based on the recognition that the human resources development is a crucial factor in determining a nation's competitiveness. This study aimed, first of all, to diagnose the problems directly and indirectly affecting the testing method in the current NTQS. And then, differentiated solutions according to grade and improvements in the testing infrastructure were suggested. The ultimate purpose was to provide a blueprint for enhancing national competitiveness through increased authenticity and efficiency of the NTQS. Research methods applied during this study include: the collection and review of qualification-related literature; a series of conferences with leading experts; interviews with vocational educators and researchers from qualification-related institutes; a survey of national qualification holders from a variety of professions and industries; and participatory observation at qualification exam centers. This research suggested policy recommendations as follows; First, measures to improve for testing method of professional engineer Second, measures to improve for testing method of Master craftsman Third, measures to improve for testing method of Engineer, Industrial Engineer, Craftsman Fourth, plans for the establishment of operation system for a computerized testing Fifth, institutional perspective on establishing qualification infrastructure Sixth, operational perspective on establishing qualification infrastructure

• Journal of Environmental Impact Assessment
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• v.6 no.1
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• pp.105-110
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• 1997

Sanitary landfill is a general method as a final disposal of municipal solid waste(MSW), therefore leachate characteristics are very various as lime goes by because of highly concentrated organic acids are contained non biodegradable COD. So it is hard to abide by the mandatory standards of discharge eventhough applying the physicochemical and biological processes to treat the leachate. The process of treating leachate are determined by the degree of removal and components, but they are highly contained organic materials. It is a removal method to use jointly with the physicochemical process if the hard and fast rule is needed. The critical components of material are COD, ammonia, salts and heavy metals in the case of treating biologically. Biological process is to use metabolism of microorganism, therefore it is a desirable condition which heavy metals are not contained, because they acting as an inhibitor of enzyme. Of these are contained, organic decomposition and synthetic function of microorganisms decrease significantly. Consequently, this research paper lays emphasis on the concentration of heavy metals in leachate and for the purpose of forecasting the factors which are affecting the leaching of metalic waste in some degree, experimented the various reacting conditions. 1. When the concentration of heavy metals in leachate is in comparison with the level eluted after reaction, at pH 7.9 the result of reaction for PCB to CCL scrap showed that Zn, Mn, Cu was more eluted 11.6 times, 340.3 times, and 2,705.5 times respectively than the leachate undiluted solution. 2. At the condition of strong acid pH 4.7, the concentration of heavy metals in EM undiluted solution showed that Zn, Mn, Cu was more eluted 26.5 times, 147.3 times, and 3,656.3 times respectively than leachate undiluted solution. 3. When the ratio leachate to EM was 50 vs 50(V/V%), Mn was more eluted 198.7 times than leachate undiluted solution, but Zn and Cu do not show the meaningful results. 4. The color of landfill leachate was black-brown. And fulvic acid that is main ingredient of NBD COD contained, oxygen of 44~50%. For that reason, I estimated that the level of Zn, Mn, Cu was higher than the case of leachate. 5. COD of leachate from general landfill is difficult to remove. Because the solution of heavy metals is improved by the character of leachate(pH & ingredient of oxygen etc.) hence the Mn, Cu, Zn act as disturbing factor, the biochemical treatment is hard. Therefore the type of PCB & CCL scrap, iron, aluminum contained metals need to previously separate from general wastes as much as possible.

• Science of Emotion and Sensibility
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• v.9 no.2
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• pp.133-140
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• 2006

In order to investigate the sensation of the fabric sound simulating the real wear-condition, the fabric sound simulator using reciprocating friction was developed. Fabric sounds from 5 specimen were generated by the fabric sound simulator and recorded using high performance microphone. Physical sound parameters of fabrics including level pressure of total sound (LPT), level range (${\Delta}L$), and frequency differences (${\Delta}f$) were calculated. For psychological evaluation, seven adjectives for sound (softness, loudness, sharpness, clearness, roughness, highness, and pleasantness) were used as the semantic differential scale. Fabric sounds by reciprocating friction of nylon taffeta and polyester leno had the highest value of LPT and evaluated as loud, sharp, rough, and unpleasant while polyester ultra suede and silk crepe de chine haying the lower LPT and ${\Delta}f$ were perceived as soft and quite. Comparing with fabric sound by one-way friction, fabric sound by reciprocation friction was perceived as more sharp, loud, and rough. LPT was also the most important factor affecting the sensation of the fabric sound by reciprocating friction.

• Journal of the Korean Society of Environmental Restoration Technology
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• v.21 no.4
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• pp.11-23
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• 2018

The purpose of this study is to identify the ecological characteristics and biological interactions between species of the abandoned rice paddy field in mountainous areas and to suggest a management strategy for stable food chain formation and biodiversity enhancement. The study site is located in Uldae wetland of Songchu district Bukhansan National Park, site characteristics and biological habitat characteristics were identified through site survey and literature survey. With regard to physical environment, among geographical features, the Uldae Wetland and the neighborhood inside the basin was a gently sloping area($5{\sim}15^{\circ}$). And 64.0% of basin faced the north. With regard to water environment, the Uldae Wetland was wetland of rainfed paddy field depending on precipitation and the system of stream flowing into the wetland from valley. According to the results of examining flora in plant ecology, in general, they were herbaceous wetland species. 88.6% of existing plants inside the Uldae Wetland basin was a forest in the mountain. And Quercus spp. community and Pinus densiflora community accounted for 64.6% of that, and was dominant. Except for that, Salix koreensis community was distributed. The existing vegetation of Uldae Wetland inhabited wetland species and terrestrialization indicator species, and it was thought that partial terrestrialization inside the Uldae Wetland was in progress after the discontinuation of paddy cultivation, such as the expansion of Salix koreensis distribution area. In the status of appearing faunae in the Uldae Wetland with regard to wildbirds of appearing principal species, The Uldae wetland was based on a abandoned rice paddy field various wildlife, and was a wildlife feeding, spawning, and resting place. The water environment was an important factor in maintaining the wetland living creatures function, habitat of waterbirds and benthic macroinvertebrates, amphibians and odonate are spawning ground and habitat, it was affecting the vegetation ecosystem based on wetlands. In order to maintain the diversity of wildlife, it was important to maintain smooth water supply and water level. A stable food chain will be formed and the Uldae wetland biodiversity will be abundant by establishing the relationship between the species of Uldae wetland, which is abandoned rice paddy field, and the habitat environment favored by species belonging to the ecosystem stepwise linkage. The ecological characteristics of the Uldae wetlands and the relation between the species were analyzed and the environmental conditions were reflected in the planning and management plan of Uldae wetland ecology.

• Journal of the Korean Society of Food Culture
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• v.12 no.4
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• pp.391-400
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• 1997

To provide basic information for the development of refrigerated convenience foods for Koreans, 492 house-wives residing in Seoul and Kyunggi Province were surveyed concerning satisfaction of buying precooked convenience foods, frequency of using them, preferred Korean dishes, and willingness to buy the convenience foods if they are developed. Statistical data analysis was completed using SAS package program. The satisfaction mean score of the marketed precooked convenience foods was 2.73 out of 5 and the housewives were least satisfied with feed additives and sanitation factors. The factors affecting satisfaction in purchasing were sanitation, taste, variety of type, nutrition, price, and food additives for side-dishes sold refrigerated or at room temperature, and taste, sanitation, variety of type, price, nutrition, and food additives for frozen prepared foods in order respectively. The frequency of using the precooked convenience foods was generally low but that of using the pickled dishes, Jokbal Soondae, and frozen prepared foods was relatively high. The answer of 'the thought that meals should be prepared in households' was the primary reason for avoiding using the precooked convenience foods and 'no time to cook' was the most frequent answer among the reasons for using them. Currently, the precooked convenience foods were used for snacks mainly, but the usages to be expected to increase were for lunchbox, main dishes, snacks, side dishes, special occasions foods, and leisure foods in order. Based on preference and buying priority, the dishes needed to be developed as refrigerated convenience foods among Korean dishes were identified. The result showed that 'preference' was not consistent with buying priority and the housewives perceived the factor of 'convenience' more importantly than 'preference' in purchasing the convenience foods.

• Applied Chemistry for Engineering
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• v.18 no.5
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• pp.495-500
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• 2007

The inside wall of a coal gasifier is lined with refractory, and the corrosion of the refractory is an important factor affecting the refractory lifetime and the replacement period. This paper examines the changes in microstructure of a chromia refractory due to chemical reactions with slag having varying amounts of $Fe_2O_3$. Slag samples were prepared by adding $Fe_2O_3$ to KIDECO slag, and static corrosion experiments were carried out at $1550^{\circ}C$. The layer of $(Fe,Cr)_3O_4$ formation and the depth of Fe depletion in the infiltrating slag were determined. In addition, FactSage equilibrium calculations were carried out in order to determine the conditions of formation, and to compare with the experimental observations. In the sample exposed to KIDECO slag, which has about 10 wt% $Fe_2O_3$, the formation of $(Fe,Cr)_3O_4$ was not observed. As the $Fe_2O_3$ concentration in slag increased, $(Fe,Cr)_3O_4$ formation and Fe depletion depth increased. Increasing $Fe_2O_3$ concentration also made the slag/refractory interface indistinguishable. Equilibrium calculations predicted that higher $Fe_2O_3$ concentrations favor chromite formation at gasification temperatures. The chromite formation was most favorable when the amount of $Cr_2O_3$ was limited, as in the case of dissolved $Cr_2O_3$ in slag. When the concentration of $Fe_2O_3$ in slag was less than 20%, the formation of chromite was least favorable in the system with equal amounts of slag and refractory.

• Journal of the Korea institute for structural maintenance and inspection
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• v.22 no.1
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• pp.167-175
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• 2018

This research deals, The characteristics of mechanics and behavior of the tube structural systems, It has been investigated and considered conventional theory and case models, It has shown the suitability, The best location, And optimal shape of the unit module system, Considered variables materials of stiffness increase and decrease in hybrid tube structural systems this study carried out adapting analysis of statistical concepts. In a concrete way, This study exams the effect of reducing horizontal displacement and the shear lag phenomenon, Also, The purpose of this study is to utilize the basic data on the design and study of future high-rise hybrid structural system using this research. As a result, The framed- tube structural system does not effectively cope with horizontal behavior of high-rise buildings, The results of using varying material tested resistance factors and lateral loads in hybrid tube structural system, When each material is compared Bracing material is identified as a key factor in lateral behavior. In a ratio of material quantity framed-tube structural system, The level of sensitivity affecting the horizontal displacement is greater then the beam's column, In case of braced tube structural system, Braced appeared to be most sensitive in comparison of material quantity ratio in columns and beams.

• Korean Journal of Environmental Agriculture
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• v.31 no.4
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• pp.293-299
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• 2012

BACKGROUND: Soil utilization pattern can be the main factor affecting soil physico-chemical properties, especially in soil phosphorus (P). Understanding the distribution and bioavailability of P is important for developing management to minimize P release from arable soils to environment. This study was conducted to evaluate the potential bioavailability of soil organic P by using phosphatase hydrolysis method. METHODS AND RESULTS: Twenty-four soils from onion-rice double cropping and 30 soils from plastic film house were selected from Changyeong and Daegok in Gyeongnam province, respectively. The P accumulation pattern (total P, inorganic P, organic P, residual P) and water soluble P were characterized. Commercial phosphatase enzymes were used to classify water-extractable molybdate unreactive P from arable soils into compounds that could be hydrolysed by (i) alkaline phosphomonoesterase (comprising labile orthophosphate monoesters), (ii) a combination of alkaline phosphomonoesterase and phosphodiesterase (comprising labile orthophosphate monoesters and diesters), and (iii) phytase (including inositol hexakisphosphate). Available P was highly accumulated with 616 and 1,208 mg/kg in double cropping system and plastic film house, respectively. Dissolved reactive P (DRP) and dissolved unreactive P (DUP) had similar trends with available P, showing 24 and 109 mg/kg in double cropping and 37 and 159 mg/kg in plastic film house, respectively, indicating that important role of dissolved organic P in the environments had been underestimated. From the result of phosphatase hydrolysis, about 39% and 66% of DUP was evaluated as bioavailable in double cropping and plastic film house, respectively. CONCLUSION(S): Orthophosphate monoester and orthophosphate diester accounted for high portion of dissolved organic P in arable soils, indicating that these organic P forms give important impacts on bioavailability of P released from P accumulated soils.

• Journal of Environmental Impact Assessment
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• v.24 no.2
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• pp.175-189
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• 2015

The objective of this study was to analyze characteristics of distribution of amphibian species and the affecting ecological factors. For the study, habitat environment factors were determined and applied to a habitat suitability model for the data collected from the Seom River in Hoengseong County and Wonju City, Gangwon Province, Korea between March 2013 to October 2013. The analyzed amphibian species were Rana nigromaculata, Hyla japonica, Rana dybowski, and Rana rugosa Temminck and Schlegel, and a logistic regression model was used with the pseudo-absence data. The result of the model analysis suggests that the major factors for Rana nigromaculata are distance to vegetation and rock and that for Hyla japonica is waterway. Rana dybowski and Rana rugosa Temminck and Schlegel have similar habitat characteristics, but the latter is shown to be dominant due to its wider habitat preference. According to the species richness model, the analyzed amphibian species are shown to have tendency to move between valleys or streams. This study quantitatively analyzed habitat environment characteristics using species distribution model, however, there is a limitation in terms of analysis on food factor and connectivity with other species. Combined with additional density or habitat analysis on birds or fish, this study can lead to more comprehensive analysis on biological environment factors.