• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.34 no.1
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• pp.95-102
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• 2006

The PPT being currently developed for the flight model represents a significant leap in techniques and technology compared to the previous flight ones. The electrical energy to be charged in the pulsed plasma thruster (PPT) is a very important aspect to provide an uniform impulse bit ,, and a specific impulse ,, for satellite attitude control. In this paper, we propose a nonlinear control technique and a stability analysis based on the Lyapunov function for the pulsed plasma thruster. Specifically, the proposed control law guarantees to charge and discharge the electrical energy generated from the power processing unit (PPU) within the specified time.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.31 no.1
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• pp.42-48
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• 2003

To get a periodic trim solution from Level II helicopter flight dynamic equations, DAE based PPT A (partial Periodic Trimming Algorithm) has been proposed. Iterative update of state variables from PPT A can cause a numerical instability in DAE solver which needs compatible initial conditions. By simply adjusting the order of DAE solver a periodic trim can be obtained with good accuracy. Application for CBM (Common Baseline Model) helicopter showed the same trim result as harmonic balance method and the effective elimination of unrealistic initial responses at the start of flight simulation.

• Journal of Korean language education
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• v.29 no.4
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• pp.1-29
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• 2018

This study aims to develop the constructs for evaluating team presentations performed by undergraduate international students in Korea. To achieve the goal, this study reviews related research and sets the criteria to analyze the problems of team presentations performed in Korean by undergraduate international students. Through this analysis we got to know which problems they were making. They were failing to reorganize the resources they had referenced and to organize the contents into one. And errors or mistakes of grammar and spelling were found often in their PPT files, and the editing styles of the PPTs were not consistent. Moreover, their performances were not unlike their PPT files. One made a good presentation but the other students just recited the script without interaction with the audience. Moreover, they could not operate the Q&A part and lead the discussion well, and components for wrapping up the presentation also were omitted frequently. After the analysis, this study conducted a survey with 23 Korean language educators asking about the validity of the construct and description of the survey. Based on the collected feedback, the construct list has been modified primarily, and carried out a second survey with an expert group. Based on their opinion, the final construct list was fine-tuned.

• Journal of the korean society of oceanography
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• v.38 no.2
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• pp.80-86
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• 2003

The horizontal distributions of $^{224}Ra$ (half life=3.4 days) and $^{223}Ra$ (half life=11.3 days) were measured in surface seawaters of the Nakdong River estuary and the South Sea of Korea in April and October 2002. In order to determine these short-lived Ra isotopes, we used a delayed coincidence counter which is much more rapid and accurate than traditional methods. In an estuarine mixing zone (salinity, ~l6 ppt), the activities of $^{224}Ra\;and\;^{223}Ra$ were much greater than what would be expected from a mixture of freshwater and seawater in the Nakdong River estuary. This excess Ra may be a result of Ra desorption from fresh sediments originating from the river upstream. However, in the more open areas of the Nakdong River estuary (salinity>30 ppt) and the South Sea of Korea, $^{224}Ra\;and\;^{^{223}Ra$ activities decreased exponentially as a function of distance offshore. Using the decrease of $^{223}Ra$ with distance offshore in the South Sea of Korea, we estimated the apparent horizontal eddy diffusivities. The apparent eddy diffusion coefficients in South Sea of Korea are calculated to be approximately $3500-8000\;\textrm{m}^2/sec$.

• Proceedings of the KIPE Conference
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• 2000.07a
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• pp.472-475
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• 2000

An balanced tapped inductors using RPPT (Regulated Peak Power Tracking) system is proposed. In the series/parallel PPT system battery charger and discharger are operating complementary. So they both can be combined into a single hardware block. Battery charger and dis-charger share same magnetic cores thus can be reduced core weights.

• Journal of Plant Biotechnology
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• v.47 no.2
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• pp.164-171
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• 2020

Transgenic Alstroemeria plants resistant to Alstroemeria mosaic virus (AlMV) were generated through RNA-mediated resistance. To this end, the friable embryogenic callus (FEC) of Alstroemeria was induced from the leaf axil tissue and transformed with a DNA fragment containing the coat protein gene and 3'-nontranslated region of AlMV through an improved particle bombardment system. The bar gene was used as a selection marker. More than 300 independent transgenic FEC lines were obtained. Among these, 155 lines resistant to phosphinothricin (PPT) were selected under low stringent conditions. After increasing the stringency of PPT selection, 44 transgenic lines remained, and 710 somatic embryos from these lines germinated and developed into shoots. These transgenic shoots were then transferred to the greenhouse and challenged with AlMV. In total, 25 of the 44 lines showed some degree of resistance. PCR analysis confirmed the presence of the viral sequence. Virus resistance was observed at various levels. Establishment of an efficient transformation system for Alstroemeria will allow inserting transgenes into this plant to confer resistance to viral and fungal pathogens. Accordingly, this is the first report on the production of a transgenic virus-resistant Alstroemeria and lays the foundation for alternative management of viral diseases in this plant.

• The Transactions of the Korean Institute of Electrical Engineers D
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• v.54 no.8
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• pp.504-509
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• 2005

This paper presents a new method for obtaining the noninvasive and unrestrained blood pressure readings noninvasively and unrestrainedly using based on reflected wave arrival time(RAT) in the volume of pulse. Since this new method employs only volume pulse, is more rapider and simpler than the method using pulse transit time(PTT) because it only employs the volume of pulse. Blood pressure, PTT and RAT were acquired from 15 healthy subjects. Each subjects were performed forty trials of each measurement. As a result of those trials, the mean error between oscillometric and RAT measurements for systolic blood pressure was $4.55\pm5.64mmHg$. This result showed quite equal with the mean error between oscillometric and PPT measurf:ments, $4.22\pm5.30mmHg$, However, it was not obtained a satisfactory result in the relativity of oscillometric to both RAT and PPT measurements for diastolic blood pressure because of personal difference. To conclude, the method of systolic blood pressure estimation noninvasively and unrestrainedly using by RAT may be used as the method by PTT. Nevertheless, additional studies would be necessary for the RAT/PTT estimation of diastolic blood Pressure measurement.

• Proceedings of the Ginseng society Conference
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• 1998.06a
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• pp.216-223
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• 1998

Cyclic nucleotide phosphodiesterases (PDEs) represent the unique enzymatic system degrddinf cAMP and cGMP which play a major role in the regulation of cell physiology. To investigate a possible molecular mechanism of ginsenosides, their activities were evaluated on PDEs which are recently described is new therapeutic targets. PDEs are classified into 7 families according to their genes (PDEI to PDE7) and are differently distributed in tissues. The IC50 values of ginsenosides were determined on PDEI to PDE 5 chromatographically isolatetl from bovine aorta. The results show that total ginseng saponin extract preferentially inhibits PDE 1 and PDE4 at concentrations nearby 200 ug/ml. Protopanaxadiol (PPD) fraction acts preferentially on PDE4 with and IC50 value of 100 nlml and inhibits also PDEI and PDE5 at 14 to 2 fold higher concentrations, respectively. Protopanaxatriol (PPT) fraction preferentially inhibits PDE 1 with and IC50 value of 170 ug/ml. Compound Rgl, originated from PPT fraction, and RC3 (5) represent the most active compounds towards PDE 1 with IC50 values around 80 UM. However Rg3 (R), epimer of Rgl (5) has no effect on the various PDEs tested, excepted on PDE3 rich is sligthly sensitive Compound Rbl, originated from PPD, acts on both PDEI and PDE4. It if two fold less active than Rgl and Rg3 (5) on PDEI. Taken together, these results mainly suggest that PDEI and PDE4 inhibitions could be a molecular mechanism which would participate in ginsenoside mechanisms, especially the effect of PPD on blood vessel and on CNS.

• Journal of Engineering Education Research
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• v.25 no.5
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• pp.94-103
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• 2022

In this study, we examined the cases of online video classes conducted under the COVID-19 situation for 46 first-year students majoring in electrical engineering at a 3-year college in Gyeongnam. The research was carried out according to the course development process so that classes could be conducted efficiently, focusing on electromagnetism(1) course in the second semester of the first year. The online class consisted of uploading PPT recorded videos and lecture materials to the LMS and giving assignments. The contents of the study were in the scope of examining learners' perceptions through online learning contents, assignment submission, mutual feedback between instructors and learners, university-level lecture evaluation, and free opinions on online video-based electromagnetism(1) classes. As a result of the study, it was confirmed that online lecture review and problem-solving are particularly important for understanding lecture materials, and also given the nature of engineering subjects that require plenty of mathematical expressions, the detailed and immediate feedback provided by instructor enhances learners' class satisfaction and understanding. Based on these, the direction of online classes to be developed after the COVID-19 pandemic and teaching and learning methods suitable for the characteristics of subjects were discussed.

• Koreanishche Zeitschrift fur Deutsche Sprachwissenschaft
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• v.2
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• pp.343-370
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• 2000

Im Rahmen der Prinzipien- und Parametertheorie (PPT) stellt man sich vor, $da\ss$ dem Menschen die Universalgrammatik (UG) angeboren ist, die aus einer kleinen Anzahl sprachuniversieller Prinzipien und je nach der Sprache unterschiedlich zu belegender offener Parameter besteht. Die UG Prinzipien $m\"{u}ssen$ demnach nicht gelemt werden; sie bilden von vomherein eine invariante Komponente des sprachlichen Wissens. $Demgegen\"{u}ber$ sollen die jeweilige Parameter der UG im Verlauf des Spracherwerbs aufgrund des sprachlichen Inputs mit Werten der Zielsprache belegt werden. Nach dieser Ansicht ist der Spracherwerb im Grunde als $Proze{\ss}$ der 'Parameterbelegungen' aufzufassen. In der vorliegenden Arbeit ist demonstriert worden, $da{\ss}$ die PPT eine vielversprechende Grundlage fur die empirische Untersuchung zum Erwerb des Deutschen bietet. Bisherige Ergebnisse aus Untersuchungen zum Erwerb der Reflexiv-Bindung beim Erst- sowie Zweitspracherwerb wurden vorgestellt und im Hinblick auf die $M\"{o}glichkeit$ der weiteren Untersuchung zum Zweitspracherwerb des Deutschen durch Koreaner diskutiert. Der Schwerpunkt der Diskussion wurde auf die Frage gelegt, wie die Theorie des Parameters mit Ergebnissen aus Untersuchungen zur Parameterbelegung beim Spracherwerb interagiert. Auf psychologisch bzw. kognitionswissenschaftlich orientierte $Ans\"{a}tze$ zum Spracherwerb konnte in der vorliegenden Arbeit nicht eingagangen werden. Durch die $Mitber\"{u}cksichtigung\;beider\;Ans\"{a}tze\;w\"{u}rde$ jedoch das Thema 'der Erwerb des Deutschen' die Angewandte Deutsche Sprachwissenschaft in Korea noch mehr anreichern.