• Clean Technology
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• v.26 no.4
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• pp.311-320
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• 2020

In this study, the photocatalytic degradation of rhodamine B (RhB), methyl orange (MO) and methylene blue (MB) was carried out under visible light irradiation using CdS and CdZnS/ZnO photocatalysts prepared by a simple precipitation method. This study focused on examining the effect of physicochemical properties of dye and photocatalyst on the reaction pathway of photocatalytic degradation. The prepared photocatalysts were characterized by XRD, UV-vis DRS and XPS. Both the CdS and CdZnS/ZnO photocatalysts exhibit an excellent absorption in the visible light and the UV light regions. It was observed that the photocatalytic degradation of MO proceeds via the same reaction mechanism on both the CdS and CdZnS/ZnO photocatalysts. However, the photocatalytic degradation of RhB and MB was found to proceed through a different reaction pathway on the CdS and CdZnS/ZnO catalysts. It is interesting to note that MB dimer was formed on the CdS catalyst at the beginning of the photocatalytic reaction, while the MB monomer was degraded during the overall photocatalytic reaction on CdZnS/ZnO. The above results may be mainly ascribed to the difference of band edge potential of the conduction band in the CdS and CdZnS/ZnO semiconductors and the adsorption property of dye on the catalysts.

• Journal of Korean Home Economics Education Association
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• v.20 no.4
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• pp.19-42
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• 2008

The purpose of this study was to develop practical problem-based home economics teaching.learning process plans about a unit 'the youth and consumer life' of middle school eighth-grade Technology and Home Economics by applying blended learning(BL) strategy. According to ADDIE instructional design model, this study was conducted in the following procedure: analysis, design/development, implementation, and evaluation. In the stage of design and development, the selected unit was converted into a practical problem-based unit, and practical problem-based teaching. learning process plans were designed in detail by using BL strategy. An online study room for practical problem-based home economics instruction grounded in BL strategy was prepared by using Edunet(http://community.edunet4u.net/${\sim}$consumer2). Eight-session lesson plans were mapped out, and study aids for students and materials for teachers were prepared. In the implementation stage, the first-session teaching plans that dealt with a minor question 'what preparations should be made to become a wise consumer' were utilized when instruction was provided to 115 eighth graders who were in three different province, and the other one was in a middle school in the city of Daejeon. The experimental teaching was implemented for two weeks in the following procedure: preliminary program, pre-online learning, main instruction and post- online learning. The preliminary program was carried out in a session in the classroom, and pre-online learning was provided before the main instruction was given in a session in the classroom. After the main instruction was completed, post-online learning was offered. In the evaluation stage, a survey was conducted on all the learners and teachers to find out their opinions and suggestions.

• Journal of the Society of Naval Architects of Korea
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• v.32 no.4
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• pp.38-47
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• 1995

The three-dimensional multi-layer computer simulation technology for tidal current developed in the previous study is updated to a new version. many improvements are achieved by following changes : (1) No-reflection condition is adopted instead of no-gradient condition as an open boundary condition. (2) Time marching algorithm is changed so that velocity and pressure(surface movement) might be salved in turn at different time step (3) Convection term in equation of motion is estimated by upwind differencing scheme instead of central differencing. The stability is improved considerably and the steady state is achieved within 2 tidal periods which is about 3 times shorter than that of the old version. Moreover, fluctuations in time disappeared by introducing the new time marching technique. An application to the real near shore area(near Inchon harbor) is performed by the new version. Simulated results are compared with those by the simulation total developed in the University of Tokyo. Validity and effectiveness of the two simulation technologies are chocked through the comparative research works.

• Journal of Wetlands Research
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• v.24 no.3
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• pp.185-195
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• 2022

This study conducted a survey over spring and autumn from 2014 to 2020 to confirm the ecological characteristics of the size of streams and habitats, centering on the ecological landscape conservation area, and a total 256 species of benthic macroinvertebrates in 105 families, 25 orders, 8 classes, and 5 phyla appeared. In terms of appearance species, by region, the rate of appearance of Ephemeroptera and Trichoptera was high in regions consisting of lotic area and the rate of appearance of Coleoptera and Odonata was high in regions consisting of lentic areas. When comparing the population of Ephemeroptera-Plecoptera-Trichoptera (EPT) groups by region, they were classified into three groups: upstream area, mainstream area, and lentic areas, and it was confirmed that the population ratio of EPT changed as it moved from upstream to downstream. As the stream order increased, the number of species and populations increased. The Shredder group (SH) tended to decrease as the size of stream increased(r=0.9925), and the Collector-Filtering (CF) tended to increase as the size of stream increased(r=0.9319). It was confirmed that the Scraper (SC) replaced each other between species with the same ecological status as it went downstream from upstream, and it is thought that the SC did not differ significantly by stream order. In order to maintain a healthy ecosystem in the designation and management of ecological landscape conservation areas, it is necessary to consider ecological factors such as competition and physico-chemistry factors such as water quality and substrate conditions. Therefore, if the competent authority designated survey areas including buffer areas that include streams and physical habitats of various sizes, it will be advantageous to the conservative area and securing more biological resources.

• Korean journal of applied entomology
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• v.50 no.2
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• pp.131-139
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• 2011

This study investigated the adverse effects of sound treatment on physiological processes of the American leafminer, Liriomyza trifolii, during several developmental stages. Larval feeding activity was analyzed by measuring feeding tunnel length. It was significantly suppressed by sound treatment (5,000 Hz, 95 dB). Sound treatment delayed the pupal period at 315 - 5,000 Hz and prevented adult emergence at 1,000 - 5,000 Hz. Female oviposition was also inhibited by the stress sound treatments. However, phototactic adult movement was not affected by sound treatment. Pupae treated with 5,000 Hz showed marked changes in protein patterns analyzed by two dimensional electrophoresis. MALDI-TOF analysis of specific protein spots indicated that trafficking protein particle complex I, triosephosphate isomerase, hypothetical protein TcasGA2_TC013388, polycystin-2, paraneoplastic neuronal antigen MA1, and tropomyosin I (isoform M) were predicted in the control insects and disappeared in the insects treated with sound. By contrast, DOCK9, cytoskeletal keratin II, and F0F1-ATP synthase beta subunit were predicted only in the sound-treated insects. Furthermore, stress sound significantly increased the susceptibility of L. trifolii to insecticides. These results suggest that physiological processes of L. trifolii are altered by sound stress, which may be exploited to develop a novel physical control tactic against L. trifolii.

• Food Science of Animal Resources
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• v.24 no.3
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• pp.209-215
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• 2004

In a trial involving 120 pigs, the growth performance of finishing pigs and proximate composition, physicochemical properites and fatty acid composition of loin muscle were investigated by feeding the high-energy density diet and low-energy density diet. The treatments included feeding 1) the low-energy density diet (3,290 cal/kg DE, 14.50% CP, 0.70% lysine and 0.78% Ca) for 38 days and 2) the hight-energy density diet (3,350 cal/kg ME, 15.0% CP, 0.70% lysine and 0.78% Ca) for 27 days. The average daily gains were significantly higher for pigs fed the high-energy density diet than those fed the low-energy density diet, but average daily feed intake and feed conversion rate were significantly lower than those fed the low-energy density diet (p<0.05). The cooking loss and yellowness of pork were significantly (p<0.05) lower for pigs fed the low-energy density diet than those fed the high-energy density diet. There were no significant differences in carcass characteristics, proximate composition and fatty acid composition of pork. In conclusion, the results of the experiment suggested that the high-energy density diet for pigs tended to improve the growth performance, but the cooking loss and yellowness of pork were higher for pigs fed the high-energy density diet than those fed the low-energy density diet.

• Journal of the Korean Geotechnical Society
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• v.27 no.7
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• pp.17-33
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• 2011

Recently, the utilization of recycled aggregates for backfilling a power transmission pipeline trench has been considered due to the issues of eco-friendly construction and a lack of natural aggregate resource. It is important to identify the physical and thermal properties of domestic recycled aggregates that can be used as a backfill material. This paper evaluated thermal properties of concrete-based recycled aggregates with various particle size distributions. The thermal properties of the recycled aggregates and river sand provided by local vendors were measured using the transient hot wire method and the transient needle probe method after performing the standard compaction test. The needle probe method considerably overestimated the thermal resistivity of recycled aggregates especially at the dry of optimum water content because of experiencing disturbance while the needle probe is being inserted into the specimen. Similar to silica sand, the thermal resistivity of recycled aggregates decreased when the water content increased at a given dry density. Also, this paper evaluated some of the existing prediction models for the thermal resistivity of recycled aggregates with the experimental data, and developed a new prediction model for recycled aggregates. This study shows that recycled aggregates can be a promising backfill material substituting for natural aggregates when backfilling the power transmission pipeline trench.

• Journal of Gifted/Talented Education
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• v.25 no.1
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• pp.119-138
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• 2015

This study analyzed the academic achievements on above-level testing of mathematics, physics, chemistry, and English in newly entering students of science specialized high schools. It can be expected that newly students of science high specialized schools have reached ceiling level in the middle school mathematics and science academic scores. Above-level testing(or off-level testing) is a test tool used to evaluate student's ability which are above-grade level. In this study, above-level testing tools were used to develop the same type examination paper of the 2013 Korean College Scholastic Ability Test(CSAT) in mathematics, physics, chemistry, and English. The conclusions of this study were as follow: First, the academic achievement level of science specialized high school freshmen were higher the average level of general high school senior because that over 50% of them are within the 5 grade of CSAT in mathematics, physics, and chemistry. In English, 19.3% science specialized high school freshmen have reached within the 5 grade of CSAT. Second, as a result of examining characteristics of academic achievement with respect to units of subjects, in mathematics, it was showed that the academic achievement of 'continuity and limit of a function' unit was higher, 'statistics' unit was lower. In physics, the academic achievement of 'Electricity and Magnetism' unit was higher, 'Waves and particles' unit was lower. In chemistry, the academic achievement of 'compounds in life' unit was higher, 'Air' unit was lower. In English, the academic achievement of 'practical sentence' of reading area was higher, 'Sentence' of writing area was lower. In conclusion, above-level testing provided a good strategy for identifying and determining appropriate programming interventions for gifted students who are two or more grade levels above their age-mates in achievements, aptitude, or ability.

• Geophysics and Geophysical Exploration
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• v.10 no.1
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• pp.89-97
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• 2007

A three-dimensional (3D) magnetotelluric (MT) survey has been carried out to delineate subsurface structures and possible fractures, for development of low-temperature geothermal resources in Pohang, Korea. Quite good quality MT data could be obtained throughout the survey region by locating the remote reference in Kyushu, Japan, which is ${\sim}480\;km$ from the centre of the field site. 3D modelling and inversion are performed taking into account the sea effect in MT measurements near the seashore. The nearby sea in the Pohang area affects MT data at frequencies below $1\;Hz{\sim}0.2\;Hz$, depending on the distance from the seashore. The most severe sea effects were observed in the south-east parts of the survey area, closer to Youngil Bay. 3D inversion with and without the seawater constraint showed very similar results at shallow depths, roughly down to 2 km. At greater depths, however, a strong sea effect seems to form a fictitious conductive structure in ordinary 3D inversion, especially in the south-eastern part of the survey region. Comparison between drilling results and the resistivity profiles from inversions showed that five layered structures can be distinguished the subsurface beneath the target area. They are: (a) semi-consolidated mudstones with resistivity less than $10\;{\Omega}m$, which are ${\sim}300\;m$ thick in the northern part and ${\sim}600\;m$ thick in the southern part of the survey area; (b) occasional occurrence of trachybasalt and lapilli tuff within the mudstone layer has resistivity of a few tens of${\Omega}m$, (c) intrusive rhyolite ${\sim}400\;m$ thick has resistivity of several hundreds of ${\Omega}m$, (d) alternating sandstone and mudstone down to 1.5 km depth shows resistivity of ${\sim}100\;{\Omega}m$, (e) a conductive structure was found at a depth of ${\sim}3\;km$, but more geological and geophysical study should be carried out to identify this structure.

• Korean Journal of Ecology and Environment
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• v.40 no.2
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• pp.184-192
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• 2007

This study was to evaluate ecological health of Sumjin River during April${\sim}$June 2006. The ecological health assessments was based on the Index of Biological Integrity (IBI), Qualitative Babitat Evaluation Index (QHEI), and water chemistry. For the study, the models of IBI and QHEI were modified as 10 and 11 metric attributes, respectively. We also analyzed spatial patterns of chemical water quality over the period of $2002{\sim}2005$, using the water chemistry dataset, obtained from the Ministry of Environment, Korea. In Sumjin River, values of IBI averaged 33 (n= 12), which is judged as a "Fair${\sim}$Good" condition after the criteria of Barbour at al. (1999). There was a distinct spatial variation. Mean IBI score at Site 5 was estimated as 40, indicating a "Good" condition whereas, the mean at Site 3 was 23, indicating a "Poor${\sim}$Fair" condition. Habitat analysis showed that QHEI values in the river averaged 109 (n=6), indicating a "Marginal" condition after the criteria of Harbour et al. (1999). Values of BOD and COD averaged 1.3 mg $L^{-1}$ (scope: $0.9{\sim}1.8$ mg $L^{-1}$) and 3.3 mg $L^{-1}$ (scope: $2.8{\sim}4.0$ mg $L^{-1}$), respectively during the study. It was evident that chemical pollutions by organic matter were minor in the river. Total nitrogen (TN) and total phosphorus (TP) averaged 2.5 mg $L^{-1}$ and 0.067 mg $L^{-1}$, respectively, and the nutrients did not show large longitudinal gradients between the upper and lower reach. Overall, dataset of IBI, QHEI, and water chemistry suggest that river health has been well maintained, compared to other major watersheds in Korea and should be protected from habitat disturbance and chemical pollutions.