• Education of Primary School Mathematics
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• v.19 no.2
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• pp.113-125
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• 2016

The concept and measuring activities of the height of figures are essential to find the areas or volumes of the corresponding figures. For plane figures, the height of a triangle is defined to be the line segment from a vertex that is perpendicular to the opposite side of the triangle, whereas the height of a parallelogram(trapezoid) is defined to be the distance between two parallel sides. For the solid figures, the height of a prism is defined to be the distance of two parallel bases, whereas the height of a pyramid is defined to be the perpendicular distance from the apex to the base. In addition, the height of a cone is defined to be the length of the line segment from the apex that is perpendicular to the base and the height of a cylinder is defined to be the length of the line segment that is perpendicular to two parallel bases. In this study, we discuss some pedagogical problems on the concepts and measuring activities of the height of figures to provide alternative activities and suggest their educational implications from a teaching and learning point of view.

• Journal of the Korean earth science society
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• v.34 no.6
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• pp.470-478
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• 2013

There have been a number of observed precursors of volcanic activities- such as volcanic earthquake, surface inflation, specific volcanic gas emission, temperature of hot spring- at Mt. Baekdusan since 2002. We identified the increase of the volume of magma chamber beneath Mt. Baekdusan as we observed an inflation trend of vertical and horizontal surface displacement around Cheonji caldera lake by using precise leveling data from 2002 to 2009. The surface displacement trend changed to deflation in 2010, and the trend changed to inflation again after a while. Utilizing the data of inflated surface (46.33 mm) on the northern slope of Mt. Baekdusan from 2002 to 2003, we calculated the volume change of magma chamber beneath the Mt. Baekdusan. The volume change was about 0.008 $km^3$ ($7.7-8.0{\times}10^6m^3$) from 2002 to 2003. It indicated that a new magma (0.008 $km^3$) injected to the magma chamber 5 km below Mt. Baekdusan.

• School Mathematics
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• v.6 no.4
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• pp.389-409
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• 2004

This article presents a case study in which three middle school students developed models in modeling activity using a tool. We research the interaction of model development process and the activities operating a tool in the modeling. And we investigate whether students are able to create generalizable model, after a tool mediates students' thought process and students internalize the perceptive activity operating a tool. The analysis of our case study led to three results. First, as students were able to integrate perceptive activity operating a tool and cognitive activity, they reasoned about the relationships among changing quantities and developed the model. Second, students corrected and refined developed models with reflecting the perceptive activity operating a tool. Third, as students internalized perceptive activity, students were able to create generalizable model, which is a graph of height as a function of the amount of water that's in the beaker.

• Bulletin of Food Technology
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• v.8 no.3
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• pp.106-112
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• 1995

최근의 물류 환경은 교통 체증, 3D 업무 기피 현상으로 인한 인력난, 법적 규제등으로 지속적으로 악화되고 있어 기업의 물류비 부담은 매년 증가하고 있다. '94년 대한상공회의소에서 실시한 '기업 물류 관리 실태 조사'(대상업체; 513개사)에 의하면 총 매출액 중 물류비가 차지하는 비중은 14.3%에 이르고 있다. 이 같은 매출액에 대한 물류비의 비율은 '93년도의 8.5%보다 5.8%가 높아진 것으로 기업의 물류비 부담이 한 해에 19%나 증가 했음을 의미한다. 특히 음료업종은 저단가이면서 상대적으로 부피가 크고 무게가 무겁기 때문에 타 업종에 비해 물류비의 비율이 훨씬 높은 17.1%나 차지하고 있으며, 처리해야 하는 물동량도 상대적으로 많음으로 인해 물류관리상 개선의 필요성도 많고 개선에 따른 효과도 크다고 하겠다. 따라서 대부분의 음료업체들은 합리적인 물류활동을 통해 물류비용을 절감하고 서비스의 질을 높여 경쟁력을 강화하기 위해 노력하고 있는 것으로 알려져 있다. 과거 음료업체는 생산성 향상을 통한 원가 절감과 품질 향상으로 매출 증대와 이익을 이룰 수 있었다. 그러나 앞서 말한 바와 같이 물류환경의 지속적 악화와 소비자의 다양한 욕구에 의해 물류 부문에 대한 기업의 대응은 점점 어려워지고 있으며 사회적 문제화가 되고 있는 것이다.

• Proceedings of the Korean Society of Computer Information Conference
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• 2014.01a
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• pp.253-254
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• 2014

현재 시장의 구매활동은 소비자가 직접 물건을 보고 구매하거나 인터넷을 통해 물품의 대략적인 이미지를 보고 구매하는 방식이다. 특히, 부피가 크거나 무게가 무거운 가구 같은 것은 소비자들이 직접 찾아가서 보는 경우가 많다. 하지만 소비자들이 실제로 보고 구입해도 실제로 가구를 배치 할 때는 주변의 어울림과 맞지 않아 마음에 들지 않는 경우가 많다. 그 이유는 실제로 가구들을 미리 놓아보지 못한다는 점 때문이다. 이에 따라 대중화된 스마트기기에서 가구들을 미리 배치해보고 해당 정보를 미리 볼 수 있도록 함으로써 구매자들의 욕구를 충분히 충족시키고 소비자들이 물품을 구매한 뒤 불만을 없앨 필요가 있다. 따라서 본 연구에서는 증강현실을 이용하여 가구배치 애플리케이션을 개발하여 변화하는 스마트사회에서 소비자들이 좀 더 삶의 질을 향상시킬 수 있는 구매 방식을 제안한다.

• Journal of The Korean Association of Information Education
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• v.21 no.4
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• pp.451-462
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• 2017

This study selected 3D printing that is highly likely to be adopted in schools. This research was conducted in two stages: 1) proposing the learning activity framework for utilizing 3D printing in education, and 2) exploring the potential of integrating 3D printing in the school field. The '3D printing learning activity framework' proposed in this study includes four phases that are categorized according to the complexity of problem-solving processes and collaborative interaction: Step 1 as production through replication, Phase 2 as means of imaginary expression, Phase 3 as near problem-solving, and Phase 4 as expanded problem-solving. Next, we conducted the field study with 23 students in the 6th grade math class where they learned the various solid shapes and volumes through 3D printing-integrated activities. The lesson was considered as Phase 1, which is the production through replication. Overall, the results showed that the participants had positive perceptions about the efficacy of 3D printing activities, the quality of learning experience, and satisfaction. On the other hand, it was found that the usability of 3D printers and CAD program needs further improvement The contribution of this study can be found in the learning activity framework that can guide 3D printing activity design in school, and in the exploration of enhancing the connection between 3D printing activities and curricular relevance beyond simple interest toward a novel technology.

• Korean Journal of Agricultural and Forest Meteorology
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• v.9 no.4
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• pp.234-246
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• 2007

The role of macropore in the hydrological processes is important at the hillslope scale. Developments and distribution of macropores have not been investigated in conjunction with the characteristics of the hillslope such as topography, soil property, and soil moisture. In this study, macropore properties, such as macropore flow and saturation hydraulic conductivity were measured at a hillslope located in Gwangneung Research Forest, Pochun-gun, Gyeonggi-do, South Korea. An intensive field survey provided a refined Digital Elevation Model (DEM) for surface and subsurface topography. Spatial distributions of upslope area and topographic index were obtained through the digital terrain analysis. The total number of monitoring points was 22, and the selected points were distributed along the transect of the digital contour map. Vertical fluxes through macropores were measured using a tension infiltrometer at the depth of 0.1 m from the surface. Spatial and temporal distributions of soil moisture were obtained using an on-line measurement system, TRASE, installed in the study area. Soil moisture for the aforementioned points was measured at 0.1 and 0.3m depths below the surface. The results from tension infiltrometer experiments present that the macropore flows ranged between 21 and 94%, and the measured macroporosities varied from 1.4 to 47%. Macropore flows and macroporosities tended to increase as the measurement location moved to downslope. The ability for water conduction through macropores becomes increasingly developed as the location approaches the outlet of the hillslope.

• Journal of The Korean Association For Science Education
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• v.30 no.8
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• pp.1044-1059
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• 2010

In this study, we investigated the influences of the method of using analogy on concept understanding, mapping understanding, and mapping error by analogical reasoning ability level. We also investigated students' perception of a role-playing analogy activity. Seventh graders (N=152) at a middle school were assigned to the comparison and the experimental groups. The students of the experimental group were taught about 'the relation between pressure and volume of gas' with experience-based role-playing analogy, while those of the comparison group were taught with explanation-centered analogy. Analyses of the results revealed that the instruction using roleplaying analogy was more effective in concept understanding and retention of mapping understanding than explanation-centered analogy instruction, regardless of analogical reasoning ability level. It was also found that the students of the experimental group had fewer mapping errors than those of the comparison group. However, there was little difference in t pes of mapping errors by the method of using analogy. The students of the experimental group answered that they did not have difficulties in performing the role-playing analogy activity and they actively engaged in the activity. They perceived that the role-playing analogy activity was interesting. Educational implication of these findings are discussed.

• Economic and Environmental Geology
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• v.50 no.6
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• pp.509-515
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• 2017

Quartz is the most abundant mineral in the Earth's continental crust. Therefore, understanding of quartz dissolution and precipitation is very important to know about weathering processes and interactions between rocks and water in hydrothermal and metamorphic environments. This paper presents a basic review on the research about quartz dissolution mechanism under various physico-chemical conditions. We rearranged the relationship between each physico-chemical factor and dissolution mechanism from the results of previous researchers in this paper. From this result, we understood that quartz dissolution and precipitation are affected by each factor such as temperature, pH, and applied stress conditions at contact point. In particular, we recognized that the high pH and temperature conditions have different anion concentrations on mineral's surface. As a result, high pH and temperature conditions have a better effect than applied stress condition to the quartz dissolution mechanism.

• Korean Chemical Engineering Research
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• v.43 no.3
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• pp.387-392
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• 2005

Recently, dimethyl carbonate (DMC) is considered as an alternative of MTBE (methyl tert-butyl ether), additive for non-leaded gasoline with their fast biodegradation rate and low toxicity. DMC is usually synthesized so far by oxidative carbonylation of methanol, and recently developed synthetic process is also started with methanol. Since the phase equilibria of the system, consisted of DMC and methanol or other reaction products on different temperature and pressure is necessary for the optimum separation process design and operation. However the reported phase equilibria and physical properties for DMC mixtures in the Dortmund Data Bank (DDB; thermodynamic property data bank) are quite rare. Besides, infinitely dilute properties are not found. In this work, isothermal vapor-liquid equilibria at 333.15 K for methanol+DMC binary system and mixing properties, excess molar volume and viscosity deviation at 298.15 K are directly measured and correlated. Additionally, infinitely dilute activity coefficient of methanol in the DMC solvent at three different temperatures are measured and compared with predicted values using modified UNIFAC (Dortmund).