• Journal of Mechanical Science and Technology
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• 제17권5호
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• pp.776-783
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• 2003

A low speed wind tunnel test was conducted for full-scale model of an unmanned aerial vehicle (UAV) in Korea Aerospace Research Institute (KARI) Low Speed Wind Tunnel(LSWT). The purpose of the presented paper is to illustrate the general aerodynamic and performance characteristics of the UAV that was designed and fabricated in KARI. Since the testing conditions were represented minor portions of the load-range of the external balance system, the repeatability tests were performed at various model configurations to confirm the reliability of measurements. Variations of drag-polar by adding model components such as tails, landing gear and test boom are shown, and longitudinal and lateral aerodynamic characteristics after changing control surfaces such as aileron, flap, elevator and rudder are also presented. To explore aerodynamic characteristics of an UAV with model components build-up and control surface deflections, lift curve slope, pitching moment variation with lift coefficients and drag-polar are examined. The discussed results might be useful to understand the general aerodynamic characteristics and drag pattern for the given UAV configuration.

• Journal of Power Electronics
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• 제9권2호
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• pp.232-242
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• 2009

In this paper, a matrix converter with improved low frequency output performance is proposed by achieving a one-step commutation owing to a general commutation circuit applicable to n-phase to m-phase matrix converters. The commutation circuit consists of simple resister and capacitor components, leading to a very stable, reliable and robust operation. Also, it requires no extra sensing information to achieve commutation, allowing for a one-step commutation like a conventional dead time commutation. With the dead time commutation strategy applied, the distortion caused by commutation delay is analyzed and compensated, therefore leading to better output linear behavior. In this paper, detailed commutation procedures of the R-C commutation circuit are analyzed. A selection of specific semiconductor switches and commutation circuit components is also provided. Finally, the effectiveness of the proposed commutation method is verified through a two-phase to single-phase matrix converter and the feasibility of the compensation approach is shown by an open loop space vector modulated three-phase matrix converter with a passive load.

• International Journal of Computer Science & Network Security
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• 제21권5호
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• pp.222-230
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• 2021

The article reviews the issue of formation of information culture of social work bachelors in the process of their professional training. The main internal / external factors that determine the need for the information culture formation of social workers-to-be have been identified. To determine the levels of information culture formed in bachelors of social work criteria and their indicators have been substantiated. The model of information culture formation in BSW has been developed and implemented in Ukrainian universities under the following pedagogic conditions: organized informational environment; interconnection between general and professionally-directed courses; curriculum includes course directed on IC formation. The model contained interconnected components: aim - to achieve higher level of information culture formed; specific principles; content, interactive methods and forms of organization of educational process, methods of control and correction; components of information culture. The implemented mastered learning procedure has contributed to the leveling up of information culture formed in social work bachelors.

• 한국원자력학회:학술대회논문집
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• 한국원자력학회 1996년도 춘계학술발표회논문집(2)
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• pp.691-698
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• 1996

This paper propose a procedure to estimate the system lifetime distribution using simulation method in a parametric framework and also develop the criterion for terminating the simulation. We assume that a system is composed of many components whose lifetime and repair time distributions are general, and repair of each component is imperfect or not. General simulation algorithms can not be adopted for this case, due to the dependency of successive operating times and the discontinuity in base line intensity function of failure process. Then we propose algorithms for generating failure times subject to imperfect repair. We develop the event time tracking logic for identifying the system failure time, and also develop the criterion for terminating the simulation. Our procedure is composed of two phases. The first phase of the procedure is to generate the system failure times from the inputs. The second phase is to estimate the lifetime distribution of the system. The best model is selected by a fully automated procedure among well-known parametric families, and the required parameters are estimated. We give examples to show the accuracy of our procedure and the effect of repair effect of components to system MTTF(Mean Time To Failure).

• 대한약리학회지
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• 제10권2호
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• pp.13-23
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• 1974

Results of an experiment on the general behavior of rats in order to explore the possible pharmacological actions of Panax Ginseng upon the central nervous system can be summarized as follows: 1) The rats treated with Ginseng-saponin intraperitoneally with the doses of 50 or 100 mg/kg show the decreased sleeping component and increase in lying and grooming component and walking and rearing component of general behavior. 2) There are no difference between control group and saline treated group in pattern of general behavior components. 3) In the Ginseng-saponin treated groups, the amphetamine stimulated walking and rearing component of genenarl behavior are reduced but lying and grooming component are elevated. 4) Ginseng-saponin shows very low acute toxicity in mice. The $LD_{50}$ in mice of 24 hours after intraperitoneal injection was 795 mg/kg. From the above findings, it is to suggest that the Ginseng saponin might stimulate the central nervous system but its mode of action appears to be different from that of amphetamine. And the effects of Ginseng saponin may be varied depending on various experimental situation or condition of animals.

• 한국식품영양학회지
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• 제29권1호
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• pp.58-64
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• 2016

This study was conducted to investigate the health effects of the general components of acorns in animals. In Korea, acorns have been used as food material in the form of acorn starch. Acorns contain tannin, gallic acid, digallic acid, and gallotannin. Therefore, the health effects of acorns as functional food are actively being studied. The chemical composition of acorns may vary according to the harvest time, region, and breed. Acorns have excellent antioxidant properties and might be beneficial in controlling hyperlipidemia, obesity, cardiovascular disease, and dementia, as well as strengthening immune competence. Further study is necessary to better understand the benefits of acorns, as it is expected to represent a large part of the food industry.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1998년도 추계학술대회 논문집 학회본부A
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• pp.112-114
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• 1998

The passive system requires RF-DC converter. RF-DC converter, which is used in microwave region, is more affected by parasitic elements than used in low frequency region. So it is difficult to make the converter. RF-DC converter usually consists of resonator, shottky diode, capacitor, voltage regulator. In this study, we used the rechargeable battery instead of capacitor. If any passive transponder requires more power than general transponder, battery tech of this components is important to apply for the passive system. In this paper, passive transponder, which requires more power than general passive transponder, is presented and compared to general passive transponder.

• 한국초등과학교육학회지:초등과학교육
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• 제24권5호특별호
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• pp.595-601
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• 2005

In this study, the scientifically gifted students and the general students were compared in terms of the following components in cooperative teaming: whom they interacted with, to/from whom they gave/received help and why, and what kinds of the verbal interaction patterns they engaged in. The subjects were 4th graders. The data were collected through the investigation of the students' perception and videotaping of the small group interactions of each group. The results showed that the gifted students interacted with most students in their groups. They complemented each others' opinions and their discussion was enriched through their interactions. On the other hand, the interactions of the general students occurred mostly around a leader, and more teamed students explained the content to the less teamed students. Predominantly, the gifted students' most verbal behaviors were related with the teaming contents. Most frequent verbal behavior were a giving specific information and an explanation of their opinions. The general students, however, gave simple and short information, and more often they showed the management behaviors, such as encouraging participation and suggesting their directions.

• 한국도서관정보학회지
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• 제47권3호
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• pp.213-239
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• 2016

전 세계적으로 오픈 데이터가 강조되는 환경에서 데이터의 공유 및 재이용으로 인해 발생하는 문제점을 최소화하기 위한 정책적 논의도 함께 진행되고 있다. 본 연구에서는 연구데이터 레포지터리에서 데이터의 접근 및 이용을 통제하는 정책요소들을 조사하고 학문 분야별로 그러한 정책 요소들의 공통점과 차이점을 살펴보는 것을 목적으로 하였다. 이를 위해 해외 연구데이터 레포지터리 37곳을 대상으로 데이터 접근 및 이용 통제를 규정하고 있는 정책 요소를 분석하였다. 생명과학 및 보건과학분야 20개 레포지터리, 화학 지구환경과학 물리학 분야 10개 레포지터리, 사회과학 및 일반과학 분야 7개 레포지터리로 구분하여 분석을 실시한 결과 저작권 및 라이선스 규정, 데이터 인용, 면책조항 및 엠바고 적용 관련 규정이 공통적으로 제시되는 정책 요소인 것으로 나타났다. 그러나 분야별로 규정되고 있는 정책 요소의 다양성에는 차이가 있는 것으로 나타났으며 이는 분야별로 강조되는 데이터 접근 및 이용 통제 근거의 차이를 반영하는 것으로 볼 수 있다.

• 한국대기환경학회지
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• 제33권5호
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• pp.458-472
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• 2017

The optical properties and direct aerosol radiative forcing (DARF) of different aerosol components in $PM_{2.5}$ (water-soluble, insoluble, black carbon (BC), and sea-salt) were estimated using the hourly resolution data measured at Aewol intensive air monitoring site on Jeju Island during 2013, based on a modeling approach. In general, the water-soluble component was predominant over all other components with respect to its impact on the optical properties(except for absorbing BC) and DARF. The annual mean aerosol optical depth (AOD) at 500 nm for the water-soluble component was $0.14{\pm}0.14$ ($0.04{\pm}0.01$ for BC). The total DARF at the surface ($DARF_{SFC}$) and top of the atmosphere ($DARF_{TOA}$), and in the atmosphere ($DARF_{ATM}$) for most aerosol components(except for sea-salt) during the daytime were highest in spring and lowest in fall and/or summer. The maximum $DARF_{SFC}$ of most aerosol components occurred around noon (12:00~14:00 LST) during all seasons, while the maximum $DARF_{TOA}$ occurred in the afternoon (13:00~16:00 LST) during most seasons (except for spring). In addition, the estimated $DARF_{SFC}$ and $DARF_{ATM}$ of the water-soluble component were -20 to $-59W/m^2$ and +3.5 to $+14W/m^2$, respectively, while those of BC were -18 to $-29W/m^2$ and +23 to $+37W/m^2$, respectively.