• Journal of The Korean Astronomical Society
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• v.42 no.2
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• pp.27-32
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• 2009

Recently, we suggested a CME earthward direction parameter as an important geoeffective parameter that has been demonstrated by front-side halo CME data. In this study, we present the geometrical implication of this parameter by comparing with the parameters from a CME cone model. Major results from this study can be summarized as follows. First, we derive an analytic relationship between the cone model parameters(the half angular width of a cone and the angle between the cone axis and the plane of sky) and the earthward direction parameter. Second, we demonstrate a close relationship between the earthward direction parameter and the cone axis angle using 32 front-side full halo CMEs. Third, we found that there is noticeable inconsistency between the cone axis angles estimated from the cone model fitting to the CMEs and from their associated flare positions, implying that the flare position should not be considered as a good earthward direction parameter. Finally we present several advantages of our earthward direction parameter in terms of the forecast of a geomagnetic storm based on CME parameters.

• Journal of the Korean Society of Costume
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• v.27
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• pp.27-40
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• 1996

1.It was recorded at "Dong Gook Tong Gam" of King "Jang Soo" that "Sim-Eui" in Korea was first introduced from China at the reign of King, "Moon Ja"(491,A.D), Go Goo Ryo. 2."Sim-Eui" was worn as a mourning dress during the period of "Go Ryo" and as a concanical robe of Confucian, a ceremonial dress at home and for the rules of etiquettes during Cho Sun Dunasty. 3.Several theories about the construction and the using services of "Sim-Eui" are obseved and summerized. 4.Mr. Kyu-soo Park gives a definition to "Sim-Eui" as a Fortune of Heaven & Earth, the Constellation of the Cosmic Dual Forces, the Revolution of the Four Seasons, a dignified mien & the Way of a Man of Virtue and Virtue of the golden Mean. 5.I observed the concrete measurements of the each parts of "Sim-Eui" by the construction method of Kyu-Soo Park. 6.The Symbolic Meaning following the Idea of Mr. Chung, Hyun. describes well the line of thinking in our nation, and Idea of Loyalty & Filial Piety, a Man of Virtue and the Virtue of the Golden Mean. 7.As described above, I dare insist of the fact that the Construction Theory of "Sim-Eui" by Kyu-Soo Park during the letter period of Chosun Dynasty is full of our national manners and cus-toms with symbolizing meaning, construction's exquisiteness, clothes' materials and it's size most suitable to our people, to the exclusion of the defects in "Sim-Eui" of China and Japan.

• Journal of Power Electronics
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• v.9 no.2
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• pp.215-223
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• 2009

A design methodology for transformers including integrated and center-tapped structures for LLC resonant converters is proposed. In the LLC resonant converter, the resonant inductor in the primary side can be merged in the transformer as a leakage inductance. And, the absence of the secondary filter inductor creates low voltage stress on the secondary rectifiers and is cost-effective. A center-tapped structure of the transformer secondary side is widely used in commercial applications because of its higher efficiency and lower cost than full-bridge structures in the rectifying stages. However, this transformer structure has problems of resonance imbalance and transformer inefficiency caused by leakage inductance imbalance in the secondary side and the position of the air-gap in the transformer, respectively. In this paper, gain curves and soft-switching conditions are derived by first harmonic approximation (FHA) and operating circuit simulation. In addition, the effects of the transformer including integrated and center-tapped structures are analyzed by new FHA models and simulations to obtain an optimal design. Finally, the effects of the air-gap position are analyzed by an electromagnetic field simulator. The proposed analysis and design are verified by experimental results with a 385W LLC resonant converter.

• The Transactions of the Korean Institute of Power Electronics
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• v.23 no.1
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• pp.66-71
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• 2018

We propose an online parameter estimation method for surface-mounted permanent-magnet synchronous motor (SPMSM) using an affine projection algorithm (APA). The proposed method estimates parameters with two APAs based on the discrete-time model equation of SPMSM during motor operation. The first APA is designed to estimate inductance, and the second APA is designed to estimate resistance and flux linkage. However, in case when the d-axis current is controlled to 0A, the second APA cannot estimate resistance and flux linkage simultaneously because the matrix rank in APA becomes deficient. To overcome this problem, we temporarily inject a negative reference current input to the d-axis control loop, and the matrix in the APA then becomes full rank, which enables the simultaneous estimation of resistance and flux linkage. The proposed method is verified by PSIM simulation and an actual experiment, and the results reveal that SPMSM parameters can be estimated online during motor operation.

• Journal of the Society of Naval Architects of Korea
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• v.47 no.6
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• pp.770-775
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• 2010

As considerable interests in noise emission from the ships have been increased, control of the propeller cavitation generating vibration and radiating noise is looming large. In general, the tip vortex cavitation is first produced in case of full scale propellers, and noise levels rise dramatically from that moment. In order to reduce induced noise from the tip vortex cavitation and hence increase the cavity inception speed, we propose the mass injection method. Water injected from the propeller tip decreases rotating speed of the tip flow, and it restrains growing the tip vortex cavity. Experimental investigations of the model tests carried out in a large cavitation tunnel show that the tip vortex cavitation is effectively controled by water injection from the propeller tip.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.26 no.10
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• pp.2026-2033
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• 2002

The purpose of this study is to investigate the effect of mechanical properties of the FREI using horizontal stiffness and vertical stiffness by experiments. Two kinds of FREI are designed and fabricated. The steel plates of SREI are replaced with fibers in order to reduce the cost of fabrication and installation. At first, the Nylon fiber is adopted as feasibility study of FREI. The experimental results of Nylon FREI and SREI show that the vertical stiffness of Nylon FREI is lower than SREI, and effective damping is two times higher than SREI. Carbon is adopted, by these rusults, as strong reinforcement than Nylon and full scale of carbon FREI was designed and fabricated. By the experimental test results, it is shown that the vertical stiffness of carbon FREI is three times higher than SREI, and two times higher in effective damping. As a result, the proposed FREI can replace the SREI as a seismic isolator.

• Journal of the Korean Society for Library and Information Science
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• v.43 no.3
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• pp.379-397
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• 2009

The purpose of this study is to analyze the development and features of the abridged DDC (Dewey Decimal Classification), one of the main factors for DDC's success. For the study, a comparison table including the publication years and the physical features has been presented based on the general relationship between the full edited DDC and the abridged DDC. In addition, the contents and features have been analyzed from the first to the latest (14th) edition. Lastly, the time of introduction of four supplementary tables used in the abridged DDC and its development have been investigated.

• Journal of Korean Academy of Fundamentals of Nursing
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• v.13 no.1
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• pp.6-14
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• 2006

Purpose: The purpose of this study was to investigate autonomy, teaching effectiveness, and clinical practice satisfaction for fundamentals nursing clinical practice in student nurses. Method: The participants were 244 sophomores, who had done the practice for 8 weeks from June 17 ${\sim}.33$ August 23, 2005. Autonomy the Caring Perspective(ACP) devised by Boughn(1995) was used to measure autonomy, Instrument to Measure Effectiveness of Clinical Instructor(IMECL) by Reeve(1994) for measuring teaching effectiveness, and an instrument by Moon(2002) for measuring satisfaction. Results: After practice, the role model was seen as rich in knowledge and experience(48.77%). Desirable categories for instructor were full-time professors with a practice background and head nurses(31.97%). Average score for autonomy was 3.71(${\pm}.33$), for teaching effectiveness, 3.67(${\pm}.48$) and for satisfaction 3.51(${\pm}.38$). Autonomy scores were high for students satisfied with their major(F=5.23, p=.006), and interested In practice(F=4.38, p=.014). Teaching effectiveness scores were high for students satisfied with practice (F=2.57, p=.038). Clinical practice satisfaction scores were high for students interested in practice(F=5.01, p=.007). Relationships between autonomy and teaching effectiveness (r=.174, p=.006), and between leaching effectiveness and satisfaction showed a positive correlation(r=.632, p=.000). Conclusion: Interest in clinical practice courses in first year affect autonomy, teaching effectiveness and satisfaction.

• Journal of ILASS-Korea
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• v.26 no.2
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• pp.96-103
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• 2021

In order to improve the overall efficiency and meet the emission regulations of boiler systems, the heat exchanging methods between inlet air and exhaust gas have been used in boiler systems, named as the waste-heat-recovery condensing boiler. Recently, to further improve the overall efficiency and to reduce the NOx emission simultaneously, the concept of the water injection into the inlet air is introduced. This study suggests the models for the optimized design parameters of water injection for waste-heat-recovery condensing boilers and performs the analysis regarding the water injection amount and droplet sizes for the optimized water injection. At first, the required amount of the water injection was estimated based on the 1^st law of thermodynamics under the assumption of complete evaporation of the injected water. The result showed that the higher the inlet air and exhaust gas temperature into the heat exchanger, the larger the amount of injected water is needed. Then two droplet evaporation models were proposed to analyze the required droplet size of water injection for full evaporation of injected water: one is the evaporation model of droplet in the inlet air and the other is that on the wall of heat exchanger. Based on the results of two models, the maximum allowable droplet sizes of water injection were estimated in various boiler operating conditions with respect to the residence time of the inlet air in the heat exchanger.

• Journal of the Korean Society of Food Culture
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• v.21 no.1
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• pp.1-7
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• 2006

The purpose of this study was to identify the perceptional patterns of Korean traditional food for China-Korean housewives in Yanbian area and to compare the preference for traditional food of Korean national holidays between the perceptional patterns. Data were collected from 261 China-Korean housewives in the Yanbian area and cluster analysis was used. The results revealed two different patterns, i.e., tradition-oriented vs. modem-oriented. Descriptive statistics showed that perceptional patterns were likely to vary depending on socio-demographic background. Also, perceptional patterns were significantly related with the preference of traditional food of national holidays i.e., new years day, first full moon of January, thanksgiving day, han-shik (the 105th day after the winter solstice), and dong-gi (the coldest winter solstice). Similarities and differences in perceptional patterns as well as preference of traditional food of national holidays were discussed, and future implications for food nutritionists and Asia marketers were provided.