• 품질경영학회지
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• 제19권2호
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• pp.117-124
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• 1991

In this paper, it is assumed that a system is composed of an essential unit and a nonessential unit. During the running of the system, an essential unit is replaced at periodic replacement time T or at nth failure of essential unit whichever occurs first. Nonessential unit is replaced at its failure and at the replacement of essential unit. This paper derive optimal replacement period which minmises the total expected cost for replacement. The unimodality of totoal maintenance cost function is proved under the assumption that hazard rate of each component is continuous and monotone increasing failure rate(IFR). Based on this condition, it is shown that the optimal replacement period is finite and unique.

• 동의생리병리학회지
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• 제21권2호
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• pp.514-517
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• 2007

The radical scavenging activity of Artemisia vulgaris essential oil was evaluated by 1,1-diphenyl-2-picrylhydrazyl(DPPH) assay in this study. Essential oil exhibited a significant free radical scavenging activity, with the highest activity at 15 ${\mu}$L/mL concentration. The reaction rate was slow and concentration-dependent

• 한국가구학회지
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• 제16권2호
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• pp.77-83
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• 2005

The specific gravity of wood treated with the essential oil penetration was higher than that of untreated wood. However, in case of oven-dried wood the difference of treated and untreated products decreased, compared with air-dried wood. The shrinkage of treated wood showed no consistent trend and the difference was trivial. In addition, similar trend was shown in each direction. Compression strength parallel to grain of treated wood was somewhat higher than that of untreated wood and the difference was trivial. The difference in static bending strength was slight and showed no consistent trend. The stage of check for Pinus koraiensis and Populus tomentiglandulosa and Alnus hirsuta was 2 stage and 3 stage, respectively. Deformation stage with no relation to the essential oil treatment was 1 stage for Pinus koraiensis, 2 stage Populus tomentiglandulosa and 3 stage for Ainus hirsuta, respectively, and there was no difference in essential oil penetration.

• Food Science and Biotechnology
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• 제18권6호
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• pp.1371-1378
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• 2009

The aim of this study is to elucidate the anti-inflammatory activities of chopi (Zanthoxylum piperitum A.P. DC.) essential oil. Essential oil (EO) of chopi was extracted by steam distillation method, and its major constituents were limonene and geranyl acetate. Chopi-EO decreased approximately 38% of nitrite production, as compared to the lipopolysaccharde (LPS)-induced nitrite production. However, chopi-EO and its components did not quench nitric oxide (NO) chemically in cellfree system, and markedly inhibited approximately 40.4% of inducible nitric oxide synthase (iNOS) mRNA transcription. In addition, the inhibition of E-selectin gene transcription by chopi-EO caused the suppression of cellular adhesion. These results suggest that chopi-EO may exert potential anti-immunological inflammatory activity.

• 약학회지
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• 제46권3호
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• pp.203-207
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• 2002

The antifungal activities of the essential oils from Anthemis nobilis, Ciderus atlantica, Juniperus communis, Lavandula angustifolia, Pelargonium graveolens, Pogestemon patchouli, Rosmarinus officinalis, and Styrax tonkinensis which are recommended for the treatment of microbial infections in aromatherapy and complementary medicines were tested against Candida spp. The activities were measured by broth dilution method and disk diffusion assay. Most of the test oils inhibited growth of Candida albicans, C. utilis and C. tropicalis. Especially, the essential oil from Pelargonium graveolens and its main component, citronellol showed the strongest activity among the herbs except benzoic acid from Styrax tonkinensis which is well-known antimicrobial compound. As a result of checkerboard microtiter test. synergistic effect of citronellol, was shown when the component was combinated with ketoconazole, displaying a fractional inhibiting concentration (FIC) index of 0.37 against C. albicans.

• Management Science and Financial Engineering
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• 제13권1호
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• pp.121-126
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• 2007

Among many graphs, directed acyclic graph(DAG) attracts many researchers due to its nice property of existence of topological sort. In some classic graph problems, it is known that, if we use the aforementioned property, then much efficient algorithms can be generated. So, in this paper, new algorithm for the all-pairs shortest path problem in a DAG is proposed. While the algorithm performing the iteration, it identifies the set of essential arcs which requires in a shortest path. So, the proposed algorithm has a running time of $O(m^*n+m)$, where m, n and $m^*$ denote the number of arcs, number of node, and the number of essential arcs in a DAG, respectively.

• 한국환경생태학회:학술대회논문집
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• 한국환경생태학회 2005년도 정기총회 및 학술대회
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• pp.3-14
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• 2005

To investigate phytotoxic substances in some donor plants and their biological activities, seed germination and seedling growth of receptor plants were examined at different concentrations of aqueous extracts and essential oils of the donor plants. Germination of some receptor species was inhibited by the extracts, while seedling growth was decreased to a lesser degree than in the germination test. Germination, seedling growth and dry weight growth of Achyranthes japonica grown in pot were proportionally inhibited by the extracts. Volatile substances emitted some donor plants caused inhibitory effects in the germination and seedling growth of the receptor species. Essential oil of the plants extracted by Karlsruker's apparatus Inhibited growth of microorganisms, callus growth and root hair development of receptor plants. The cortical cells at the root tips of Latuca sativa treated with essential oils showed contraction of the cytoplasm, resulting in plasma membranes becoming detached from the cell walls and the cells metamorphosing irregularity. Accumulation of lipid granules Inside contracted cytoplasm and degeneration of mitochondrial cristae were also observed. The GC/MS method was employed for analysis and identification of allelochemicals from donor plants. Sixty-one chemical substances such as camphene, cineole etc. were identified from essential oils of Artemisia argyi.

• ETRI Journal
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• 제42권5호
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• pp.734-747
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• 2020

Using 23 867 standard essential patents claimed for three different wireless telecommunication standards (GSM, WCDMA, and LTE), this research examined the difference in technological importance and breadth of patents between practicing and non-practicing entities. We discovered that compared to manufacturers and service providers, organizations who do not appropriate innovation-derived profits directly from product or service markets tended to have relatively low-quality but broadly scoped technologies for the claimed standard essential patents. These relationships between the characteristics of inventions and the organizational types were consistently held across different generations of wireless standards as indicated by regressions run for each sample split by generation. Furthermore, the theory and policy implications of our results and arguments are presented herein.

• 약학회지
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• 제58권1호
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• pp.58-61
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• 2014

The essential oil was extracted from the roots of Angelica dahurica Bentham et Hooker f. by steam distillation and its composition was analyzed by GC-MS. The antifungal activities were evaluated by micro-dilution method against five Aspergillus and three Trichophyton species. The most abundant component was ${\alpha}$-pinene (17.21%) among 40 compounds identified in this oil. The essential oil fraction of A. dahurica and ${\alpha}$-pinene exhibited marked inhibiting activities against the tested Aspergillus and Trichophyton species with MICs (minimum inhibitory concentrations) between 0.12 mg/ml and 8 mg/ml.

• Archives of Pharmacal Research
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• 제28권8호
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• pp.897-901
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• 2005

The in vitro inhibitory activities of essential oils from Thymus magnus and T. quinquecostatus as well as their main constituents were evaluated against susceptible and resistant species of Streptococcus pneumoniae, Staphylococcus aureus, Salmonella enteritidis, and Salmonella typhimurium. Notably, the essential oil fraction of T. magnus and its main components displayed significant inhibitory action against both antibiotic-susceptible and resistant strains of S. pneumoniae, S. aureus, and S. typhimurium with minimum inhibitory concentrations (MICs) ranging from 0.125 to 8 mg/mL. The differential MIC values imply that the oil fraction and its main components exhibit distinct patterns of activity against the tested bacterial species. Moreover, the disk diffusion test revealed that the inhibitory activities of oil fraction and components were dose-dependent. Data from the checkerboard titer test confirmed synergism between the antibiotic, norfloxacin, and T. magnus oil or thymol, particularly against the resistant strains of S. aureus.