• Journal of Gifted/Talented Education
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• v.19 no.1
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• pp.141-162
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• 2009

The purpose of this study was to find out the learner's characteristics of students of Korea Science Academy by comparing general high school students and science high school students to Korea Science Academy students in terms of scientific attitude, learning styles, preferred teaching style, and learning environment, and to find out the differences of the learner's characteristics by gnender and school number, and to establish teaching strategies based on the findings. First, scientific attitude level of Korea Science Academy students was similar with science high school students and was high level comparing with general high students. Second, for learning style, the students of Korea Science Academy had many independent, collaborative and participatory types, Third, for the prefered science teaching style, the students of Korea Science Academy had high demands for diversification and thinking at higher levels girl students had open-mindedness and cooperation and voluntariness of higher level in scientific attitude, had more independent types in leraning style, and had higher preference of teacher's support, subject convergence and permissive atmosphere than boy students. there were no difference of student's characteristics and preferences by school number. Based on the findings, we proposed 4 teaching strategies.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.50 no.8
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• pp.573-581
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• 2022

This paper deals with the development of CanSat system, which ejects two maple seed-type autorotating science payloads and collects weather information. The CanSat consists of two autorotating science payloads and a container. The container is equipped with devices for launching science payloads and communication with the ground station, and launches science payloads one by one at different designated altitudes. The science payload consists of a space for loading and a large wing, and rotates to generate lift for slowing down the fall speed. Specifically, after being ejected, it descends at a speed of 20 m/s or less, measures the rotation rate, atmospheric pressure, and temperature, and transmits the measured value to the container at a rate of once per second. The communication system is a master-slave structure, and the science payload transmits all data to the master container, which aggregates both the received data and its own data, and transmits it to the ground station. All telemetry can be checked in real time using the ground station software developed in-house. A simulation was performed in the simulation environment, and the performance of the CanSat system that satisfies the mission requirements was confirmed.

• Korean Journal of Plant Taxonomy
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• v.50 no.3
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• pp.351-355
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• 2020

Argyreia gyrobracteata Traiperm & Chitchak (Convolvulaceae) is newly recorded in Vietnam. It is similar to A. mekongensis Gagnep & Courch in having a white campanulate corolla but differs from that species by having whitish surface of the abaxial leaf, narrowly lanceolate or linear-oblong, curly, rolled up the bract with a longer length of the petiole and a shorter pedicel. It was previously known only in Thailand, but was recently found in Lam Dong Province, Vietnam, for the first time. The present study provides a detailed description, colorful photos and the distribution of the species. Furthermore, a comparison of the diagnostic characters between this species and a related species in Vietnam, A. mekongensis Gagnep & Courch, is provided.

• Archives of Pharmacal Research
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• v.28 no.10
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• pp.1131-1134
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• 2005

Two new benzopyrans 6-[1'-oxo-3'(R)-hydroxy-butyl]-5,7 -dimethoxy-2,2-dimethyl-2H-1-ben-zopyran (1) and 6-[1'-oxo-3'(R)-methoxy-butyl]-5,7 -dimethoxy-2,2-dimethyl-2H-1-benzopyran (2) were isolated from the leaves of Mallotus apelta Muell.-Arg., (Euphorbiaceae). Their chemical structures were elucidated by spectroscopic analyses, especially by 1D-, 2D-NMR and MS spectra. Compound 1 was found to have strong cytotoxic effect against two human cancer cell lines as human hepatocellular carcinoma (Hep-2, $IC_{50}\;:\;0.49\;{\mu}g/mL$) and rhabdosarcoma (RD, $IC_{50}\;:\;0.54\;{\mu}g/mL$), while compound 2 showed moderate activity against Hep-2 cell line ($IC_{50}\;:\;4.22\;{\mu}g/mL$) by in vitro assay.

• Journal of the Korea Institute of Military Science and Technology
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• v.22 no.1
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• pp.27-34
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• 2019

This paper presents a chamber pressure model development of K2 rifle by applying Gaussian mixture model. In order to materialize a real recoil force of a virtual reality shooting rifle in military combat training, the chamber pressure which is one of major components of the recoil force needs to be investigated and modeled. Over 200,000 data of the chamber pressure were collected by implementing live fire experiments with both K100 and M193 of 5.56 mm bullets. Gaussian mixture method was also applied to create a mathematical model that satisfies nonlinear, asymmetry, and deviations of the chamber pressure which is caused by irregular characteristics of propellant combustion. In addition, Polynomial and Fourier Regression were used for comparison of results, and the sum of squared errors, the coefficient of determination and root-mean-square errors were analyzed for performance measurement.

• Bulletin of the Korean Mathematical Society
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• v.48 no.1
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• pp.115-127
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• 2011

We study the structure of the set of nilpotent elements in various kinds of ring and introduce the concept of NR ring as a generalization of Armendariz rings and NI rings. We determine the precise relationships between NR rings and related ring-theoretic conditions. The Kothe's conjecture is true for the class of NR rings. We examined whether several kinds of extensions preserve the NR condition. The classical right quotient ring of an NR ring is also studied under some conditions on the subset of nilpotent elements.

• The Korean Journal of Applied Statistics
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• v.25 no.1
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• pp.197-203
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• 2012

In fitting a regression model, we often encounter data sets which do not follow Gaussian distribution and/or do not have equal variance. In this case estimation of the conditional density of a response variable at a given design point is hardly solved by a standard least squares method. To solve this problem, we propose a simple method to estimate the distribution of the fitted vales under heteroscedasticity using the idea of quantile regression and the histogram techniques. Application of this method to a real data sets is given.

• Mycobiology
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• v.37 no.4
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• pp.310-312
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• 2009

A total of 82 isolates of Colletotrichum species were obtained from anthracnose symptoms of highbush blueberry trees grown in the Gochang area of Korea during a disease survey in 2008. Out of the isolates, 75 were identified as Colletotrichum gloeosporioides and the others as C. acutatum based on their morphological and cultural characteristics. Twenty six of C. gloeosporioides isolates produced their teleomorph Glomerella cingulata in PDA culture. Three isolates of each C. gloeosporioides and C. acutatum caused anthracnose symptoms on the leaves by artificial inoculation, which were similar to what was observed in the orchards. Previously in Korea, only C. gloeosporioides has been reported as causing anthracnose in blueberries. This is the first report that C. acutatum causes anthracnose in the highbush blueberry in Korea.

• Journal of the East Asian Society of Dietary Life
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• v.21 no.6
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• pp.918-923
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• 2011

This study was aimed to investigate the nutritional components such as proximate content, minerals, vitamins, and dietary fiber of Euonymus sieboldiana leaves. The leaf sample used was fresh material produced in April in the Republic of Korea. As a result, the fresh leaf sample contained 10.30% crude carbohydrates, 7.42% crude proteins, 0.69% crude fat, and 1.46% crude ash, including a high amount of potassium (0.73%). The total dietary fiber, insoluble dietary fiber, and soluble dietary fiber content was 8.77%, 7.60%, and 1.17%, respectively. Vitamin C was found to be 44.53 mg% using colorimetric analysis. We regarded E. sieboldiana as a potential health food material because of its abundant nutritional components like potassium, dietary fiber, and vitamin C.

• Korean Journal of Weed Science
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• v.31 no.3
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• pp.319-321
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• 2011