• Journal of the Korean earth science society
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• v.25 no.4
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• pp.222-231
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• 2004

The purpose of this study is to analyze the seventh curriculum textbooks and teacher's guides of high school science courses in relation to the generation (mechanism) of magma in subduction boundary and find the incorrect descriptions of the texts and the figures (illustrations) and then suggest some improved schemes. According to the result there are many discrepancies in definition of 'magma' among the textbooks and further little scientific explanations about the formation mechanism of magma in most textbooks, and even no descriptions about that. In addition, the figures are inconsistent with the description of the text and also have some incorrect depiction which might contribute to the forming and reinforcing misconceptions about Plate Tectonics as well as a volcanic activity in subduction boundary. On the basis of the previous researches, therefore, some improved schemes (text descriptions and figures) are suggested. The results of this study should be used as a reference for publishing science textbook, developing science curriculum, and teaching effectively in the high school.

• Proceedings of the Korean Vacuum Society Conference
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• 2014.02a
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• pp.161-161
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• 2014

열플라즈마는 주로 아크 방전에 의해 발생시킨 전자, 이온, 중성입자(원자 및 분자)로 구성된 부분 이온화된 기체로, 국소열평형상태를 유지하여 구성입자가 모두 수천에서 수만도에 이르는 같은 온도를 갖는 고속의 제트 화염 형태를 이루고 있다. 이렇게 고온, 고열용량, 고속, 다량의 활성입자를 갖는 열플라즈마의 특성을 이용하여, 종래 기술에서는 얻을 수 없는 다양하고 효율적인 산업적 이용이 활발히 진행되고 있다. 용사코팅은 노즐 출구를 통해서 외부로 방출되는 열 플라즈마 화염을 이용하는 것으로 이 화염의 와류 특성으로 인하여 외기의 가스가 화염내부로 침투하는 특성을 가진다. 이러한 현상은 열원의 냉각효과 외에도 외기를 구성하는 기체 분자의 내부 유입을 의미하는 것으로 대기 상태에서 공정이 이루어진다면 열원 내로 유입되는 대기 내의 산소가 모재 표면과 반응하여 산화가 진행된다. 이러한 산화과정은 용사 코팅의 품질을 저하시키는 요인이 되므로, W, Ti 등과 같은 반응성이 높은 재료의 코팅은 산화과정을 방지하기 위하여 진공에서 코팅을 하여야만 한다. 진공 플라즈마용사코팅은 진공 또는 저압의 불활성 분위기 중에서 열플라즈마 화염에 용사재료를 투입하여 플라즈마 화염 내부에서 순간적으로 이를 용융시킨 후 고속으로 분출, 모재에 적층시키는 코팅공정이다. 이때 분말상의 용사재료를 고속으로 화염 중심에 투입하여 최대 에너지 전달이 이루어지도록 하는 것이 적층효율 및 코팅품질을 향상에 필수적이다. 하지만 플라즈마 화염 내부를 고속으로 이동하는 입자의 온도와 속도 및 궤적을 측정하여 제어하는 것은 매우 어렵기 때문에, 통상 형성된 코팅의 구조와 두께로부터 경험적으로 파라미터를 결정하는 것이 일반적이다. 본 연구에서는 초고속 레이저 카메라와 이미지 분석용 소프트웨어를 이용하여 플라즈마 화염내의 비행입자 궤적을 추적하고, 이를 통해 분말 이송가스의 유량이 코팅 효율 및 미세구조에 미치는 영향을 조사하였다. 플라즈마 화염은 중심부가 가장 높은 온도와 속도를 가지고 있기 때문에, 분말 이송가스의 유량이 적을 경우 투입된 분말은 단지 플라즈마 화염의 상부 경계면을 지나는 궤적을 갖게된다. 이로 인해 분말의 용융이 충분히 이루어지지 않아 적층 효율이 낮고 미용융 입자 및 기공이 많은 미세구조를 보였다. 이송가스 유량을 증가시키게 되면, 분말의 궤적은 플라즈마 화염의 중심부를 지나게 되어 적층 효율이 증가하고 미세구조 또한 개선되었다. 하지만 이송가스 유량이 지나치게 클 경우, 투입된 분말 입자는 플라즈마 화염을 조기에 관통하게 되어 비행궤적은 온도와 속도가 낮은 영역에 형성되었다.

• Journal of Digital Convergence
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• v.14 no.9
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• pp.485-493
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• 2016

This study analyzes the collision occurring in the daily life of the United States where diverse ethnicities live side by side, as portrayed in the film 'crash'. The analysis is followed by a counseling method necessary for a diverse society. To analyse the essence of conflict in the film, a convergence psychological analysis was conducted based on desire theory. The result was that the desire to survive and innovate always collided with frustration. This is because of the obstacles in real life that suppresses desire. The process of frustrated desires and their distortion was structurized. In the conclusion, a counseling method and theory with 'a recovery model that promotes change' was presented for problematic personalities that are entrenched widely in the United States about pain by conflict.

• Journal of the Korean Society of Propulsion Engineers
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• v.6 no.1
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• pp.21-29
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• 2002

Hybrid propulsion systems provide many advantages in terms of stable operation and safety. However, classical hybrid rocket motors have lower fuel regression rate and combustion efficiency compared to solid propellant rocket motor. The recent research efforts are focused on the improvement of volume limitation and regression rate in the hybrid rocket engine. The present study has numerically investigated the combustion processes in the hybrid rocket engine. The turbulent combustion is represented by the eddy breakup model and Hiroyasu and Nagle and Strickland-Constable model are used for soot formation and soot oxidation. Radiative heat transfer is modeled by finite volume method. To reduce the uncertainties for convective heat transfer near solid fuel surface having strong blowing effect, the Low Reynolds number $\kappa-\varepsilon$ turbulent model is employed. Based on numerical results, the detailed discussion has been made for the turbulent combustion processes in the vortex hybrid rocket engine.

• Economic and Environmental Geology
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• v.46 no.3
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• pp.267-278
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• 2013

The East African Rift System(EARS) is known to be hosted epithermal Au-Ag deposits, and the best-known example is Main Ethiopian Rift Valley(MER) related to Quaternary bimodal volcanism. Large horst-graben system during rifting provides open space for emplacement of bimodal magmas and flow channel of geothermal fluids. In recent, large hydrothermally altered zones(Shala, Langano, and Allalobeda) and hot spring related to deeply circulating geothermal water have been increasing their importance due to new discoveries in MER and Danakil depression. The hot springs in Shala and Allalobeda occur as boiling pool and geyser on the surface, whereas some areas didn't observe them due to decreasing ground water table. The host rocks are altered to quartz, kaolinite, illite, smectite, and chlorite due to interaction with rising geothermal water. The hot springs in MER are neutral to slightly alkaline pH(7.88~8.83) and mostly classified into $HCO_3{^-}$ type geothermal water. They are strongly depleted in Au, and Ag, but show a higher Se concentration of up to 26.7 ppm. In contrast, siliceous altered rocks around hot springs are strongly enriched in Pb(up to 33 ppm, Shala), Zn(up to 313 ppm, Shala), Cu(up to 53.1 ppm, Demaegona), and Mn(up to 0.18 wt%t, Shala). In conclusion, anomalous Se in hot spring water, Pb, Zn, Cu, and Mn in siliceous altered rocks, and new discoveries in MER have been increasing potential for epithermal gold mineralization.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.39 no.2
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• pp.135-146
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• 2015

This paper is the fourth on the combustion characteristics of the landfill gas in a constant volume combustion chamber for a large displacement volume commercial engine and the second dealing with torch ignition. It discusses the combustion characteristics of torch ignition on the basis of the heat release and visualization. The results show that the jet and/or spout from the torch promote combustion by accelerating the flame front in the main combustion chamber. In addition, a hot gas jet exists when the orifice diameter is 4 mm, whereas the flame passes directly through the orifice if the diameter is 6 mm or greater. In addition, the effect of torch ignition differs according to the combination of the methane fraction, torch volume, and orifice size because various combustion processes occur as a result of the interaction of these parameters. Finally, it was found that the most suitable torch should have an orifice diameter of not less than 6 mm and an area ratio of not more than 0.15 to secure a consistent combustion process in a real engine.

• The Journal of the Petrological Society of Korea
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• v.21 no.4
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• pp.415-429
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• 2012

The monitoring methods for volcanic gases are divided into remote sensing and direct gas sampling approaches. In the remote sensing approach, COSPEC and Li-COR are used to measure $SO_2$ and $CO_2$, respectively, with FT-IR for detection of a range of volcanic gases. However, the remote sensing approach is not applicable to Mt. Baegdu, where the atmospheric contents of volcanic gases are very low as a result of the strong interaction of volcanic gases with the nearby surface water and groundwater. On the other hand, the direct gas sampling approach involves the collection of volcanic gases from volcanic vents or fumaroles and the subsequent laboratory analysis, thus making it possible to measure even very low levels of volcanic gases. The direct sampling approach can be subdivided into the evacuated bottle method and the flow-through bottle method. In applying both methods, sampling bottles typically contain reaction media to trap specific volcanic gases. For example, NaOH solution(Giggenbach bottle), $NH_4OH$ solution, and acid condensates have been experimented for volcanic gas sampling. Once taken from vents and fumaroles, the samples of volcanic gases are pretreated and subsequently analyzed for volcanic gases using GC, IC, HPLC, titrimetry, TOC-IC, or ICP-MS. Recently, there has been the increasing number of evidences on the potential volcanic activity of Mt. Baegdu. However, little technical development has been made for the sampling and analysis of volcanic gases in Korea. In the present work, we reviewed various volcanic gas monitoring methods, and provided the detailed information on the monitoring methods applied to Mt. Baegdu.

• The Journal of the Petrological Society of Korea
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• v.22 no.1
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• pp.9-17
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• 2013

Trachytic cliff showing a unique appearance like noodle is located in the Mt. Bipa, Seo-myeon, Ulleung island. This cliff is named 'Guksubawi'(means noodle-like rock) by its appearance. There is cliffs on three sides except north side and each side shows semi-vertical columnar joints obviously. This columnar joint has different character in appearance and mineralogy according to their direction and this tendency is remarkable in contrast between the east side and the west side. The consideration of the cooling processes after eruption of trachytic lava based on the contrast of both columnar joints dealt in the full text. In the morphological approach, the columnar joint on the east side has narrower space and chisel-like marks than the west side. And the joint walls are sharper on the east side than west side too. In the mineralogical approach, then, trachyte on the west side has bigger phenocrysts than the east side and is showing glomeroporphyritic texture and weak trachytic textures of lath of plagioclase. Around these differences between the east side and the west side, it modelled the typical temperature gradient while the cooling processes of hot rocks and the east side, consequently, corresponds to exterior of the entire trachytic volume. The columnar joint of the Guksubawi has the value of landscape and scientific importance about the forming processes of the columnar joint of trachytic lava, and so supposed it has enough values to preserved as natural heritage.

• Journal of the Korean earth science society
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• v.32 no.7
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• pp.871-880
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• 2011

The purpose of this research is to explore preservice earth science teachers' understanding of volcanic systems using a modified version of InVEST Volcanic Concept Survey (InVEST VCS, Parham et al., 2010). Results showed that participants' understanding of volcanic concepts was rather limited. Questions requiring only basic content knowledge (e.g., terminology associated with volcano) received high scoring responses, while questions requiring higher order thinking and deeper conceptual connections as the mechanics of volcanic eruption received low scoring responses. Specifically, the prediction of hazards and impacts on the environment appeared to be poorly understood. VCS results can be applied to improve the subject content knowledge as well as the pedagogical knowledge that instructors may use when they assess students' understanding of volcanism within a solid conceptual framework.

• Culinary science and hospitality research
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• v.9 no.4
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• pp.98-112
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• 2003

Approximately 0.7 millions dining business exist all over the country and the industry gains 33 trillions sales every year. Although the characteristics, preference factors, and consuming trends of the consumers in this area are diverse and unpredictable than those in other segments, it is actual that the industry has not been divided as a specified market suited to the real state of affairs in the nation. Therefore, in order for appropriate marketing strategies, it will be necessary to focus on extending product classification, diversifying brands, health marketing, and marketing by ages, by generations, and by life patterns. In addition, economically superior position can be established by subdividing strategies meeting various needs and expectations of consumers.