• Journal of Biosystems Engineering
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• v.41 no.1
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• pp.43-50
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• 2016

Purpose: The present study is aimed at examining the drying characteristics of sea tangle through a combination of microwave and far-infrared drying experiment and finding the optimal drying conditions. Methods: Sea tangle was cleaned and cut into fine pieces (5mm) before they were subjected to combinational drying by microwave and far-infrared ray. The amount of specimen per drying is 2 kg. The finely cut pieces of sea tangle were preheated in a microwave dryer for three different lengths of time (10, 15, and 20 min). Subsequently, they were dried using a far-infrared dryer at tow temperatures ($90^{\circ}C$ and $100^{\circ}C$) at an air velocity of 0.8 m/s until the final moisture content reduced to 10%. Results: Sea tangle dried under the condition of 20 min of preheating in the microwave dryer and drying at $100^{\circ}C$ by the far-infrared dryer. Of the drying models verified in this study, the logarithmic model showed high accuracy with the coefficient of determination $R^2>0.7825$ and RMSE<0.1095. The rehydration ratio of sea tangle was the highest (12.87 g water/g dry matter) under the condition of 15 min of preheating in the microwave dryer and drying at $100^{\circ}C$ by the far-infrared dryer. The energy consumption for the combination of microwave and far-infrared drying was the lowest (4.78 kJ/kg water) under the condition of 20 min of preheating in the microwave dryer and drying at $100^{\circ}C$ by the far-infrared dryer. Conclusions: Considering the drying time, discoloration during drying, rehydration ratio, and energy consumption for the drying of sea tangle, the optimal drying conditions for high-quality sea tangle are 15 min of preheating in a microwave dryer and drying at $100^{\circ}C$ by a far-infrared dryer.

• Journal of Wetlands Research
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• v.16 no.4
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• pp.477-486
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• 2014

Integrated sand control including sediment discharge from hinterland rivers is necessary to maintain coastal sand resources over a long term. In this regard, the following subjects should be considered; efficient ways to transfer discharged sand from a river to the neighboring coast, measures to improve storage efficiency of the discharged sand at the river delta and/or river terrace, measures to prevent the sand resources from being discharged into the deep sea during flooding. From the 1997 to January 2004, the jetty of 156 m length was constructed the Heoya-river mouth to protect the blockade of river mouth. Several tests were carried out to investigate the characteristics of sediment transport and morphological change due to the construction of the jetty at the Heoya-river mouth. Firstly, The sand discharge from Heoya river is quantified by one-dimensional numerical analysis assuming the mixed sand of three different particle diameters. Also the numerical mode system, which predicts the sea bed changes obtained from the Bailard's energy model(1981), was combined with the wave, wave-induced currents and sediment transport models. Then, to understand the changes to the blockade of the river mouth, several aerial photographs were compared, which showed that the changes were significant.

• Journal of the Korean earth science society
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• v.33 no.2
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• pp.170-182
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• 2012

The purpose of this study was to develop learning materials based on the Kepler's abductive reasoning and to identify high school students' rule-inferring strategies on the law of planetary motion. The learning materials including the concepts of solar magnetic field, conservation of figure skater's angular momentum and Kepler's polyhedral theory were developed and the questions about Kepler's 2nd and 3rd law of planetary motion were also created. The participants were 79science high school students and 83general high school students. The patterns and properties of their abductive inference were analyzed. The findings revealed that the students showed 'incomplete analogy abduction', 'analogy abduction' and 'reconstruction' to generate the hypotheses concerning the Mars' motion related to the solar magnetic field. There were more general high school students who showed the incomplete analogy abduction than science high school students. On the other hand, there were more science high school students who showed the analogy abduction and reconstruction strategy than general high school students. Also, they showed 'incomplete analogy abduction', 'analogy abduction' and 'model construction and manipulation' to generate the hypotheses concerning Kepler's second law. A number of general high school students showed the incomplete analogy. It is suggested that because the analogy of figure skater cause the students' alternative framework to use, more detailed demonstration is necessary in class. In addition, students combined Kepler's polyhedral theory with their prior knowledge to infer Kepler's third law.

• Korean Journal of Ecology and Environment
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• v.43 no.3
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• pp.356-368
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• 2010

In this study, we applied approach of integrative star-plot area (SPA), chemical water quality and habitat conditions (QHEI) to diagnoze ecological conditions at the eight sampling sites of Sapkyo Stream. These outcomes were compared with biological health based on the Index of Biological Integrity (IBI) using fish assemblage. And then, we evaluated the integrative ecological health condition using the star-plot method. This approach based on the sum of all the star-plot areas over these water and habitat characteristics. It was developed to reflect an integrative assessment of the ecological health in the stream. The biological health, based on the model values of IBI indicating "fair-poor" condition according to the criteria. Physical habitat health, based on the QHEI, averaged 123 indicating a "good-fair" condition. Also, chemical health, based on simply BOD values indicating "poor grade" according to the criteria of the Ministry of Environment Korea (MEK). The SPA indicating that 50% of the all was impaired condition and the most sampling sites were downstream sites influenced by the point and non-point sources. Overall our results suggest that the ecological health impact was a combined effect of eutrophication and habitat degradations in the stream. The approach of SPA can be used as a tool to evaluate the integrative health of stream environment and to identify possible causes of observed effects.

• The Journal of the Korea Contents Association
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• v.16 no.2
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• pp.186-199
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• 2016

The shoe last which is the framework for the shoemaking is intensively combined with the 3D data and technologies. International shoe companies have already commercialized 3D printing technology in producing the shoe, but domestic shoe companies are still in their early stages. This study used the 3D scanning, 3D modeling and 3D printing of the high-technology to make the shoe last. This 3D producing processes should be helpful in building competitiveness in domestic shoe industry. The 3D foot scanning data of men in 30s(n=200) were collected in SizeKorea(2010). The basic statistics, factor and cluster analysis were performed. They were categorized in 3 groups by 3D foot measurement data, and the standard models were selected in each group. The cross sections in XY, YZ and XZ planes sliced from 3D scan data of the standard model were used in the sketches of the 3D shoe last modeling. The 3D shoe last was modeled by Solidworks CAD and printed by MakerBot Replicator2; a desktop 3D printer. This research showed the potential for utilization of 3D printing technology in the domestic shoe industry. The 3D producing process; 3D scanning, 3D modeling and 3D printing is expected to utilized widely in the fashion industry within the nearest future.

• Journal of Korean Society of Environmental Engineers
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• v.27 no.6
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• pp.642-650
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• 2005

This research investigates the effects of adding oxidants such as $Fe^0$, $Fe^{2+}$, and ${S_2O_8}^{2-}$ in the sonolysis of 1,4-D. Results indicate that the degradation could be divided into two steps (initiation and acceleration) kinetically. The initial portion agreed with zero-order expression, while the second portion could be fitted with pseudo first-order expression. In the presence of ${HCO_3}^-$, as a radical scavenger, the degradations of 1,4-D and TOC were suppressed, indicating that OH radical is an important factor in the sonolysis. The overall degradation efficiency of 79.0% in the sonolysis was achieved within 200 minutes. While $Fe^0$, $Fe^{2+}$, and ${S_2O_8}^{2-}$ were individually combined with sonication, the degradation efficiency of 1,4-D increased 18.6%, 19.1%, and 16.5% after 200 min, respectively. The addition of oxidants not only changed the kinetic model from zero to pseudo first order at initiation step, but also increased the rate constants in the acceleration step. The addition of oxidants in the sonolysis of 1,4-D also improved the mineralization of 1,4-D, however, the effect of adding oxidants on the rate increase was similar regardless of the oxidants.

• Journal of the Korea Convergence Society
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• v.9 no.9
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• pp.123-133
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• 2018

This study aims to evaluate the overall health of the disabled and oral health behavior to determine its relevance to DMFT index. Based on the National Health Nutrition Survey. The survey was conducted on disabled adults over 19years old age in 2013 the first of 6th phase. The data analysis included a general characteristics, disability factors, social economy factors, health factors, oral health behavior factors were cross-analyzed on a composite sample. The general linear model of the combined sample was analyzed to determine the factors affecting the DMFT index of the disabled. The analysis shows that the DMFT index is higher for men than for women, the higher age, the lower level of education, the worse condition of whole body(EQ-5D), the difficulty of Stomatognathic system, the uncomfortable of chewing and the worse oral health conditions subjectively. Therefore, the study objectively identified the overall oral health condition of the adult disabled in Korea, Through this study, a measure should be made to development of comprehensive oral health education program to promote oral health of disabled people and policy measures should be prepared for prevention and care of oral health of disabled people.

• Journal of the Korean Geotechnical Society
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• v.27 no.3
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• pp.41-54
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• 2011

The present study analyzes the stability of waterfront quay wall under the combined action of earthquake and tsunami. Adopting the limit equilibrium method, the stability of waterfront quay wall is checked for both the sliding and overturning. Forces due to tsunami are compared with the proposed formula and the 3-D one-field Model for immiscible TWO-Phase flows (TWOPM-3D). Variations of the stability of wall are also proposed by the parametric study including tsunami water height, horizontal seismic acceleration coefficient, internal friction angle of soil, friction angle between the wall and the soil and the pore water pressure ratio. The present study about the stability of wall is also compared with the case when earthquake and tsunami are not considered. As a result, the result of numerical analysis about the tsunami force is similar to that of proposed formula. When earthquake and tsunami are simultaneously considered, the stability of wall in passive case significantly decreases and tsunami forces in active case are affected as a resistance force on the wall and so the stability of wall increases.

• Tunnel and Underground Space
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• v.24 no.4
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• pp.255-274
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• 2014

The target of this study is large scale rock slope collapsed by around 7 pm on August, 2012, which is located at ${\bigcirc}{\bigcirc}$ limestone quarries of Gangneung city, Gangwondo. The slope prior to the collapse is formed as the height of about 200 m and the average inclination of $45^{\circ}$. The estimated amount of the collapse is about $1,500,000m^3$ with respect to the slope after the collapse. Geotechnical and field investigations such as boring, geophysical prospecting, surface geological survey, geological lineaments, borehole imaging, metric 3D imaging, experimental and field test, mining work by year, and daily rainfall were performed to find the cause of rock slope failure. Various analyzes using slope mass rating, stereonet projection, limit equilibrium method, continuum and non-continuum model were conducted to check of the stability of the slope. It is expected that the cause of slope failure from the results of various analysis and survey is due to the combined factors such as topography, rainfall, rock type and quality, discontinuities, geo-structural characteristics as the limestone cavity and fault zones, but the failure of slope in case of the analysis without the limestone cavity is not occurred. Safe factor of 0.66 was obtained from continuum analysis of the slope considering the limestone cavity, so the ultimate causes of slope failure is considered to be due to the influence of limestone cavity developed along fault zone.

• Journal of the Korean Geographical Society
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• v.46 no.6
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• pp.707-723
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• 2011

The purpose of this study was to quantitatively evaluate the effectiveness of learning management systems (LMS) in the physical geography class. The study adopted the experimental design and three classes participated in this study. The first class was controlled using only classroom lectures, the second class used PPT slides along with the classroom lectures, and the third class used online video clips along with the lectures. The experiments were conducted from the Spring Semester 2007 to the Spring Semester 2008 for the introductory physical geography course. The study results showed that online learning tools help students improve academic performance and their attitudes towards the class and the instructor. Compared to simple PowerPoint slides, voice recording attached to the visual lecture slide materials enhanced students' motivation. Class lectures with lecture slides did not improve students' scores. However, when the visual materials were combined with voice recording, the number of internet access to online class materials increased, and class attendance and students' final grades were improved. Based on the results, the instructional design model that combines classroom and online learning was suggested.