• Proceedings of the Korean Magnestics Society Conference
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• 2000.09a
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• pp.5-32
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• 2000

MRAM, High performance MRAM using MTJS demostrated, fully integrated MTJ MRAM with CMOS circuits, write time ~2.3 nsec; read time ~3 nsec, Thermally stable up to ~350 C, Switching field distibution controlled by size & shape. Magnetic Tunnel Junction Properties, Magnetoresistance: ~50% at room temperature, enhanced by thermal treatment, Negative and Positive MR by interface modification, Spin Polarization: >55% at 0.25K, Insensitive ot FM composition, Resistance $\times$ Area product, ranging from ~20 to 10$^{9}$ $\Omega$(${\mu}{\textrm}{m}$)$^{2}$, Spin valve transistor, Tunnel injected spin polarization for "hot" electrons, Decrease of MTJMR at high bias originates from anode.

• Proceedings of the Korean Institute of Intelligent Systems Conference
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• 1993.06a
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• pp.1297-1300
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• 1993

Machine learning in an uncertain or unknown environment is of vital interest to those working with intelligent systems. The ability to garner new information, process it, and increase the understanding/ capability of the machine is crucial to the performance of autonomous systems. The field of artificial intelligence provides two major approaches to the problem of knowledge engineering-expert systems and neural networks. Harnessing the power of these two techniques in a hybrid, cooperating system holds great promise.

• Journal of Power Electronics
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• v.11 no.3
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• pp.381-388
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• 2011

This article presents the development of a model for SiC power diodes based on the physics of the semiconductor. The model is able to simulate the behavior of the dynamics of the charges in the N- region based on the stored charge inside the SiC power diode, depending on the working regime of the device (turn-on, on-state, and turn-off). The optimal individual calculation of the ambipolar diffusion length for every phase of commutation allows for solving the ambipolar diffusion equation (ADE) using a very simple approach. By means of this methodology development a set of differential equations that models the main physical phenomena associated with the semiconductor power device are obtained. The model is developed in Pspice with acceptable simulation times and without convergence problems during its implementation.

• The Plant Pathology Journal
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• v.37 no.5
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• pp.446-454
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• 2021

Plant-parasitic nematodes are not only an important constraint on agricultural crop production, but also cause both direct and indirect damage to turfgrass, which is a ground cover plant. However, studies on plant-parasitic nematodes of turfgrass in Korea are scarce. A survey for plant-parasitic nematodes was carried out on 13 golf courses in Korea. The results yielded 28 species/taxa belonging to 16 genera and 12 families of plant-parasitic nematodes. Among the isolated species, Helicotylenchus microlobus, Mesocriconema nebraskense, Tylenchorhynchus claytoni, Mesocriconema sp., and Meloidogyne graminicola were the most prevalent species in all management zones. Twelve species were new records of plant-parasitic nematodes in Korea. Highest maximum densities were showed by T. claytoni, Paratylenchus nanus, M. nebraskense, M. graminicola, and H. microlobus. Diversity (H'), was significantly higher in fairways compared to tees and greens, though species evenness (J') and dominance (D) showed no statistically significant differences. This information is crucial in nematode problem diagnosis, and the subsequent formulation of management strategies.

• The Plant Pathology Journal
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• v.38 no.2
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• pp.53-77
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• 2022

The global nematicides market is expected to continue growing. With an increasing demand for synthetic chemical-free organic foods, botanical nematicides are taking the lead as replacements. Consequently, in the recent years, there have been vigorous efforts towards identification of the active secondary metabolites from various plants. These include mostly glucosinolates and their hydrolysis products such as isothiocyanates; flavonoids, alkaloids, limonoids, quassinoids, saponins, and the more recently probed essential oils, among others. And despite their overwhelming potential, variabilities in quality, efficacy, potency and composition continue to persist, and commercialization of new botanical nematicides is still lagging. Herein, we have reviewed the history of botanical nematicides and regional progresses, the potency of the identified phytochemicals from the key important plant families, and deciphered some of the impediments involved in standardization of the active compounds in addition to the concerns over the safety of the purified compounds to non-target microbial communities.

• The Plant Pathology Journal
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• v.38 no.4
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• pp.323-333
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• 2022

Filenchus cylindricus (Thorne & Malek, 1968) Niblack & Bernard, 1985 was reported from the sandy rhizospheric soils of Poa pratensis and for the first time in Korea. Females and males are molecularly characterized and morphological and morphometric data supplied. Identification was made using an integrative approach considering morphological characteristics and inferences drawn from the analyses of the D2-D3 expansion segment of 28S rRNA and ITS1-5.8S-ITS2 of rRNA partial sequences. Females and males from Korea conform to the type descriptions and also to subsequent species descriptions from Iowa and Colorado USA, Sudan and Pakistan. Despite the close morphological and morphometric similarities with F. thornei (Andrássy, 1954) Andrássy, 1963, the two species can be adequately differentiated based on molecular data inference.

• Wind and Structures
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• v.9 no.4
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• pp.255-270
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• 2006

Several analytical procedures available in literature, for the evaluation of wind induced fatigue damage of structures, either assume the wide band random stress variations as narrow band random process or use correction factors along with narrow band assumption. This paper compares the correction factors obtained using the Rainflow Cycle (RFC) counting of the measured stress time histories on a lamp mast and a lattice tower, with those evaluated using different frequency domain methods available in literature. A Bi-modal spectral method has been formulated by idealising the single spectral moment method into two modes of background and resonant components, as considered in the gust response factor, for the evaluation of fatigue of slender structures subjected to "along-wind vibrations". A closed form approximation for the effective frequency of the background component has been developed. The simplicity and the accuracy of the new method have been illustrated through a case study by simulating stress time histories at the base of an urban light pole for different mean wind speeds. The correction factors obtained by the Bi-modal spectral method have been compared with those obtained from the simulated stress time histories using RFC counting method. The developed Bi-modal method is observed to be a simple and easy to use alternative to detailed time and frequency domain fatigue analyses without considerable computational and experimental efforts.

• The Journal of Asian Finance, Economics and Business
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• v.7 no.12
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• pp.115-121
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• 2020

This study aims to investigate the effects of restrictions in economic activity on the spread of COVID-19 in the Philippines. This research employs daily time-series data of confirmed new COVID-19 cases, Apple mobility trends (i.e., use of public transport to destinations, volume of people driving, and amount of walking to destinations) and Google community mobility (i.e., visits to transit stations, visits to workplaces, and staying-at-home) indicators covering the period February 17 to September 11, 2020. The analysis starts by establishing the correlation pattern of new confirmed COVID-19 daily infections to each independent variable. The results show negative linear correlation of the number of new COVID-19 daily infections with less visit to transit station, increase stay-at-home, less use of public transport, and less amount of walking to destinations. Interestingly, the number of new COVID-19 daily infections indicates some form of positive linear correlation with visits to workplaces and volume of people driving. Moreover, employing robust least square regression via the method of MM-estimation, major findings reveal that across mobility measures, staying-at-home has the highest impact on reducing the spread of COVID-19, followed by visiting transit stations less, less use of public transport, less amount of walking, and less workplace visits.

• Korean Institute of Interior Design Journal
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• v.26 no.5
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• pp.16-24
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• 2017

This study examines Safdie's design philosophy: place, purpose, and process and design strategies found in museum buildings. Safdie, influenced by personal background as immigrant, education of McGil University in Canada, apprenticeship from Louis Kahn, is one of the most recognized architects who designed renowned public and cultural buildings after Habitat 67 in Montreal, Canada. In order to reveal design strategies his eight museum buildings has been selected and analyzed in terms of interpretation of context, program presented in floor plan and section design, and the process of integrity found in structure and material. The results of this paper can be summarized as follows: 1) Reflection of existing context and regeneration of the locality has been in a creative way to reinforce the sense of place. 2) The layout of major and gallery space is determined according to the Safdie's interpretation of the site context and this can be categorized into three types. 3) Integration of the innovative structural frame and material has been experimented by using tartan grid and toroid form in the major and gallery spaces. This study is intended to reevaluate the significance of Safdie's design approach to building uniqueness of the site, program and tectonic.

• The Korean Journal of Pesticide Science
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• v.20 no.4
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• pp.293-299
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• 2016

Effect of nematicidal compounds on hatchability of sugar beet cyst nematode, Heterodera schachtii and its infective juveniles was investigated. The sugar beet cyst nematode was isolated from Chinese cabbage field in Samcheok in Korea. Acute toxicity of nematicidal compounds against infective juveniles was also tested to find the $LC_{50}$ by exposing juveniles to given dilutions of each compound. Hatchability and mortality of infective juveniles of H. schachtii were influenced by nematicidal compounds (Fluopyram 40% SC, imicyafos 30% SC, fosthiazate 30% SC, abamectine 1.68% SC, terthiophene, and Eclipta prostrata extract). Fluopyram and imicyafos yielded the lowest rates of hatching. Total hatched infective juveniles were significantly different among nematicidal compounds. Positive correlation in percentage reduction of hatching was observed in fluopyram. Furthermore, the highest mortality was also observed in the treatments of fluopyram and imicyafos ($LC_{50}$ of 0.0543 and 0.0178 ppm respectively). The study, therefore, demonstrated available alternative nematicidal compounds which could be used in the control of H. schachtii.