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        검색결과 149

        23.
        2019.06 KCI 등재 SCOPUS 구독 인증기관 무료, 개인회원 유료
        We present an analysis of the chemical abundances and kinematics of six low-mass dwarf stars, previously claimed to be candidate hypervelocity stars (HVSs). We obtained moderate-resolution ($R\sim6000$) spectra of these stars to estimate the abundances of several chemical elements (Mg, Si, Ca, Ti, Cr, Fe, and Ni), and derived their space velocities and orbital parameters using proper motions from the \gaia\ Data Release 2. All six stars are shown to be bound to the Milky Way, and in fact are not even considered high-velocity stars with respect to the Galactic rest frame. Nevertheless, we attempt to characterize their parent Galactic stellar components by simultaneously comparing their element abundance patterns and orbital parameters with those expected from various Galactic stellar components. We find that two of our program stars are typical disk stars. For four stars, even though their kinematic probabilistic membership assignment suggests membership in the Galactic disk, based on their distinct orbit l properties and chemical characteristics, we cannot rule out exotic origins as follows. Two stars may be runaway stars from the Galactic disk. One star has possibly been accreted from a disrupted dwarf galaxy or dynamically heated from a birthplace in the Galactic bulge. The last object may be either a runaway disk star or has been dynamically heated. Spectroscopic follow-up observations with higher resolution for these curious objects will provide a better understanding of their origin.
        4,500원
        28.
        2018.12 KCI 등재 SCOPUS 구독 인증기관 무료, 개인회원 유료
        We present the analysis of KMT-2016-BLG-0212, a low flux-variation (Iflux−var ∼ 20 mag) microlensing event, which is in a high-cadence (Γ = 4hr −1) field of the three-telescope Korea Microlensing Telescope Network (KMTNet) survey. The event shows a short anomaly that is incompletely covered due to the brief visibility intervals that characterize the early microlensing season when the anomaly occurred. We show that the data are consistent with two classes of solutions, characterized respectively by low-mass brown-dwarf (q = 0.037) and sub-Neptune (q < 10−4) companions. Future high-resolution imaging should easily distinguish between these solutions.
        4,000원
        34.
        2018.07 구독 인증기관·개인회원 무료
        This paper’s aim is to provide an insight into when and for what type of innovation are different types of customers most effective participants in the NPD process (Gemser & Perks 2015). Most of prior research has not considered type of innovation or only focused on one stage of NPD process, although both innovation type and each NPD process are critical factors to the NPD performance in the customer co-development context (Chatterji & Fabrizio 2014). Even though some research has examined all stages of NPD process, they also did not specify users or innovation types to compare them. Thus, we will examine the effect of customer participation on NPD performance considering both innovation and user types in terms of each NPD process. The specific research questions are 1) In the NPD process, will the impact of customer participation on NPD performance differ by user-type (lead users vs. ordinary users)? And the NPD stage?, 2) If so, when we consider both user-type and NPD stage, will the impact of customer participation on NPD performance differ depending on the type of innovation (Incremental vs. radical)? The hypotheses are developed as a basis for the subsequent research. This research has several theoretical contributions. First, we discover more appropriate user type in each NPD stage in the customer participation process. Second, we also find more appropriate user characteristics depending on the type of innovation. Third, if lead users are involved rather than ordinary users, customer participation in the development stage can generate positive impact on NPD performance, which is the opposite result compared to previous research (e.g., Chang & Taylor 2016). Finally, we show practical implications and limitations.
        35.
        2018.04 구독 인증기관·개인회원 무료
        Edible biopolymer films were developed from the exopolysaccharides (EPS) extracted from Weissella confusa 113-2. The optimum composition for film formation was determined using the response surface analysis with the explanatory variables of the EPS (0.5-5.5%) and glycerol (0.5-5.5%) concentrations and the response variable of film elastic modulus (EM). The mass ratio of distilled water to solids was set constant (14:1). Tensile strength (TS), percentage elongation at break (%E), EM, water vapor permeability (WVP) of EPS films were evaluated. The glass transition temperatures of the films were also determined by a dynamic mechanical analysis. The optimum mass ratio of EPS to glycerol was 0.754:0.375. The WVP, TS, %E, and EM of the film under the optimal composition were 3.53±0.21 g·mm/kPa·h·m2, 7.03±0.49 MPa, 84.82±12.31%, and 62.03±6.93 MPa, respectively. The glass transition temperature varied from 54 to 83 °C. The EPS film has the potential to be applied to food products as an edible film with physical and barrier properties comparable to other biopolymer edible films.
        38.
        2017.12 KCI 등재 구독 인증기관 무료, 개인회원 유료
        We give a detailed description of the installation and operation of a double-station meteor detection system which formed part of a research & education project between Korea Astronomy Space Science Institute (KASI) and Daejeon Science Highschool. A similar system is currently not existing in South Korea. A total of six light-sensitive CCD cameras were installed with three cameras at SOAO and three cameras at BOAO observatory. A double-station observation of a meteor event enables the determination of the three-dimensional heliocentric orbit in space. This project was initiated in response to the Jinju reball event in March 2014. The cameras were installed in October/November 2014. The two stations are identical in hardware as well as software. Each station employes sensitive \Watec-902H2" cameras in combination with relatively fast f/1.2 lenses. Various elds of views were used for measuring di erences in detection rates of meteor events. We employed the SonotaCo UFO software suite for meteor detection and their subsequent analysis. The system setup as well as installation/operation experience is described and rst results are presented. We also give a brief overview of historic as well as recent meteor (fall) detections in South Korea. For more information please consult http://meteor.kasi.re.kr.
        6,300원
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