• Journal of Plant Biology
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• v.15 no.1
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• pp.1-12
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• 1972

As part of the study of the structure and the successional trends of our temperate forests, a quantitative survey was made of the relatively well conserved forest stands on Mt. Kwanak, Seoul. Three community types were observed; the Pinus densiflora-Quercus mongolica community, the Pinus densiflora community, and the Quercus mongolica community. Evidence suggests that the dominance of Pinus densiflora and quercus mongolica will continue in the Pinus densiflora-Quercus mongolica community, however, in the Pinus densiflora community the dominant species, Pinus densiflora, is now being replaced by Quercus mongolica. The trend toward an increased in Acer pseudo-sieboldianum var. koreanum, Fraxinus rhynchophylla, Carpinus cordita, and Acer mono is observed in the Quercus mongolica community. An analysis of the overall composition of the forest reveals that the upper story is mostly occupied by Quercus mongolica and Pinus densiflora, the shrub layer by Rhododendron schlippenbachii and Lespedeza maximowiczii, and the herb layer by Spodiopogon cotulifer and Artemisia keiskeana. Quercus mongolica may cover most part of the forest, gradually excluding Pinus densiflora. Acer pseudo-sieboldianum var. koreanum, Fraxinus rhynchophylla, Carpinus coradata, and Acer mono are increasing in importance with the potentiality of developing into major canopy components. With the diversification of the physical habitat Cephalotaxus koreana and Magnolia sieboldii, the species which had almost completely been eliminated form the forest through the severe interferences, have reappeared.

• The Journal of Korea Robotics Society
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• v.6 no.3
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• pp.274-283
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• 2011

A simplified linearized dynamic equation for the propulsion force generation of an Ostraciiform fish robot with elastically jointed double caudal fins is derived in this paper. The caudal fin is divided into two segments and connected using an elastic joint. The second part of the caudal fin is actuated passively via the elastic joint connection by the actuation of the first part of it. It is demonstrated that the derived equation can be utilized for the design of effective caudal fins because the equation is given as an explicit form with several physical parameters. A simple Ostraciiform fish robot was designed and fabricated using a microprocessor, a servo motor, and acrylic plastics. Through the experiment with the fish robot, it is demonstrated that the propulsion force generated in the experiment matches well with the proposed equation, and the propulsion speed can be greatly improved using the elastically jointed double fins, improving the average speed more than 80%. Through numerical simulation and frequency domain analysis of the derived dynamic equations, it is concluded that the main reason of the performance improvement is resonance between two parts of the caudal fins.

• Publications of The Korean Astronomical Society
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• v.26 no.1
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• pp.25-35
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• 2011

A diagnostic tool has been proposed to convert the observed surface distribution of hydrogen recombination line intensities into the radial distributions of the electron temperature and the density in HII regions. The observed line intensity is given by an integral of the volume emission coefficient along the line of sight, which comprises the Abel type integral equation for the volume emission coefficient. As the emission coefficient at a position is determined by the temperature and density of electrons at the position, the local emission coefficient resulted from the solution of the Abel equation gives the radial distribution of the temperature and the density. A test has been done on the feasibility of our diagnostic approach to probing of HII regions. From model calculations of an HII region of pure hydrogen, we have theoretically generated the observed surface brightness of hydrogen recombination line intensities and analyzed them by our diagnostic tool. The resulting temperatures and densities are then compared with the model values. For this case of uniform density, errors in the derived density are not large at all the positions. For the electron temperature, however, the largest errors appear at the central part of the HII region. The errors in the derived temperature decrease with the radial distance, and become negligible in the outer part of the model HII region.

• Journal of Electrical Engineering and Technology
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• v.13 no.2
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• pp.892-901
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• 2018

Because of excellent electrical properties, epoxy resin is widely used in packaging and casting power equipment. Moisture and temperature in the environment are inclined to seriously affect the insulation tolerance of epoxy resin. This work focuses on the aging characteristics of epoxy resin in hygrothermal environment. Scanning electron microscopy images show that there are micro-crack, micro-slit and holes inside aged samples. The moisture absorption process undergoes three equilibrium stages and it does not follow the Fick's second law. Observing the change of hydrogen bonds in the infrared spectra of the dried samples, it is found that chemically moisture absorption immerges when the physical moisture absorption entered the third equilibrium stage. By Debye equation to fit the imaginary part of the dielectric constant, it is concluded that the uniformity of water molecule has a great influence on the electrical conductivity loss. Furthermore, the polarization loss can be more easily affected by water molecules than small free molecules. After the aged samples being dried, their real and imaginary part of the dielectric constant descend, but their original electrical properties cannot completely restored. After chemical moisture absorption appears inside the material, the residual space charges increase significantly and the charge dissipation rate slow down obviously.

• Publications of The Korean Astronomical Society
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• v.30 no.2
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• pp.113-114
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• 2015

Recent high-resolution, high-sensitivity observations of protostellar jets have shown many to possess an underlying 'wiggle' structure. HH 211 is one such example where recent sub-mm observations revealed a clear reflection-symmetric wiggle. An explanation for this is that the HH211 jet source is moving as part of a protobinary system. Here we test this assumption by simulating HH211 through 3D hydrodynamic simulations using the pluto code with a molecular chemistry and cooling module, and initial conditions based on an analytical model derived from SMA observations. Molecular chemistry allows us to accurately plot synthetic molecular emission maps and position-velocity diagrams for direct comparison to observations, enabling us to test the observational assumptions and put constraints on the physical parameters of HH211. Our preliminary results show that the reflection-symmetric wiggle can be recreated through the assumption of a jet source being part of a binary system.

• Fashion, Industry and Education
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• v.15 no.2
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• pp.1-10
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• 2017

The purposes of this study were to explore (1) how fit reviews differ among height groups and (2) how overall numerical ratings differ depending on height groups and ifferent types of fit reviews. Content analysis was used to analyze systematically sampled online consumer reviews (OCRs) of formalwear dresses rented online. In part 1, 201 OCRs were analyzed to develop the coding scheme, which included three aspects of fit (physical, aesthetic, and functional), valence (negative, neutral, positive), and overall numerical rating. In part 2, 600 OCRs were coded and statistically analyzed. Differences in frequency were not found among height groups for any types of mentions (negative, neutral, and positive) in terms of the three aspects of fit in the OCRs. Differences in overall mean ratings were not found among height groups. Interestingly, valence of each aspect of fit reviews affected mean numeric ratings. This study is new in examining relationships among textual information (i.e., fit reviews), numerical information (i.e., numerical rating), and reviewer's characteristic (i.e., height). The results of this study offered practical implications for etailers and marketers that they should pay attention to the three aspects of fit reviews and monitor garments with negative fit evaluations for lower ratings. They may attempt to increase ratings by providing customers recommendations to get a better fit.

• Journal of Korean Institute of Industrial Engineers
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• v.29 no.3
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• pp.230-238
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• 2003

The configuration design of a mechanical product can be efficiently performed when it is based on the functional modeling. There are methodologies, which decompose function from the abstract level to the concrete level and match the functions to physical parts. But it is difficult to carry out an innovative design when the function is matched only to a pre-detined part. This paper describes the configuration design process of a mechanical product with a design expert system, which uses function taxonomy and TRIZ theory. The expert system can propose a functional modeling of a new part. which is not in the existing parts list. The abstraction levels of design knowledge are introduced, which describe the operation of mechanical product in the levels of abstraction. This is the theoretical background of using knowledge of function and TRIZ for configuration design. The expert system is adequate to control this design knowledge. which expresses knowledge of functional modeling, mapping rules between functions and parts, selection of parts, and TRIZ theory. The hierarchy of functions and machine parts are properly expressed by classes and objects in the expert system. A design expert system has been implemented for the configuration design of a train bogie, and a new brake system of the bogie is introduced with the aid of TRIZ's 30 function groups.

• Journal of the Korean Institute of Landscape Architecture
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• v.13 no.2
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• pp.27-36
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• 1985

^x In Korea, we are entering on a new phase that the use concept of urban park is extending to dynamic activities such as games and sports. This article is to investigate the significance of lawn areas, as a receptive space of such a wide range of recreation activities. As a study process, Green Styles (type of parks) such as Garden Type, Park Type and Forest Type were studied and historical review of lawn areas in park development was performed. In conclusion, the lawn areas ( greensward) are an essential part of park and open space organization. The significance as a conclusion is presented as follows : 1 ) Balance in type of parks The structures of our parks and open spaces are inclined toward the artificial Garden Type and natural Forest Type. Therefore, the intermediate Park Type and sparse wood areas should be a core part of our park and open space development. 2) Psychological effect Park Type areas, thorned by greensward(lawn area), can refresh urban dwellers with natural picturesque landscaps, and Park Type landscape is the most preferred natural landscape. It shows the essence of natural amenity as 3) Accomodation of wide range of recreation activities Lawn areas in urban park are the best place in accomodating the wide range of active and massive recreation activities. Thus, lawn areas can increase the freedom of recreation use in urban park. 4) Enlargement of physical carrying capacity. With expansion of lawn areas of euro- american concept, the structural open space can be transformed into service open space. Thus, the recreation carrying capacity of urban parks can be enlarged.

• Korean Institute of Interior Design Journal
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• v.25 no.3
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• pp.82-89
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• 2016

This study investigated the preservation status of wooden architectural heritages, designated as Chungcheongbuk-do designated heritage in Jecheon. The purpose of this paper is to find the damage cause and the preservation method of wooden architectural heritages. It was conducted using the research methods of the existing literature and field survey to compare a current status of wooden architectural heritages. The result are as followings. Firstly, it was found the problems of a break, a damage, etc. in the platform and the problems of a cracking, an exfoliation, a corrosion, a warp, etc. in the wall. And, it was found a cracking of the beam(梁) and a roof tile(瓦), a falling of Angto(仰土), a sagging roof, etc. in the roof. Secondly, the damage causes of wooden architectural heritages were mostly caused by the physical limitations of the materials. And, it was caused by a rainwater, a subsidence of ground settlement, a destruction of waterproof membrane, etc. Lastly, the repair methods are making a quicklime layer in the soil mound on a cracking and an exfoliation part, a resin treatment or strut operation on a corrosion part of column, etc.

• Korean Journal of Pharmacognosy
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• v.43 no.1
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• pp.6-9
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• 2012

The $CH_2Cl_2$ soluble part of the leaves of Helianthus tuberosus L. (Compositae) exhibited a potent cytotoxic activity against the cultured human tumor cell lines including A-549, SK-OV-3, SK-MEL-2, XF498 and HCT-15 in vitro. Bioassaydirected fractionation of the $CH_2Cl_2$ soluble part of this plant led to the isolation of four cytotoxic sesquiterpene lactones having ${\alpha}$-methylene-${\gamma}$-lactone ring in the molecule. On the basis of physical and spectral evidences, their structures were characterized as ${\Delta}^{4,15}$-isoatripliciolide tiglate (1), ${\Delta}^{4,15}$-isoatripliciolide methacrylate (2), budlein A isobutylate (3) and budlein A tiglate (4). The ${\Delta}^{4,15}$-isoatripliciolide tiglate (1) showed the most potent cytotoxic activity ($0.26{\mu}M<ED_{50}<2.16{\mu}M$) against all of the cell lines tested.