• Journal of the Korean Society of Food Culture
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• 제22권5호
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• pp.597-602
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• 2007

For the hotel industry, the situations having difficulties in management are becoming we planed by the rises of the cost and labor costs, the imbalance between supply and demand, stiffening competitions between the hotels. Therefore, there has been a plan for a great change to attract customers, escaping from the existing form of management in order to secure competitive powers in the food and beverage field. For that purpose, we plan to investigate into the preference of buffet restaurants in ten 5star hotels in Seoul. By the analysis, we also plan to present the menu concepts that stand out and are preferred by the customers in managing semi-buffet restaurants. Therefore, the linear and planar coordinate values of the H Hotels and I Hotels came out both positive(+) as results of a similarity analysis using MOS, we can predict that they would be positioning on the same dimension. Furthermore we can predict that the menu of antipasto, sushi, sashimi and desserts would be positioning on the same dimension as a result of analysis of the most preferred menu by customers for each station in managing a semi-buffet restaurant. Based on these results, there must be continuous supervision over the menu of buffet restaurants.

• Journal of Wind Energy
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• 제13권3호
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• pp.33-42
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• 2022

In this paper, a semi-supervised machine learning technique applied to actual field vibration data acquired from Jeju-do wind turbines for predictive diagnosis of abnormal conditions of offshore wind turbines is introduced. Semi-supervised machine learning, which combines un-supervised learning with supervised learning, can be used to perform anomaly detection in situations where sufficient fault data cannot be obtained. The signal processing results using the spectrogram of the original signal were shown, and external data were used to overcome the problem that disturbance reactions easily occurred due to the imbalance between the number of normal and abnormal data. Out of distribution (OOD), which uses external data, is a technology that is regarded as abnormal data that is unlikely to occur in reality, but we were able to use it by expanding it. By rearranging the distribution of data in this way, classification can be performed more robustly. Specifically, by observing the trends of the abnormal score and the change in the feature of the representation layer, continuous learning was performed through a mixture of existing and new data.

• Korean Journal of Materials Research
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• 제10권2호
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• pp.117-123
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• 2000

In this study, to fabricate the semi-solid Al alloy, the 3phase-2poles electromagnetic stirring system was adopted. The changes of primary grain size, aspect ratio, standard deviation, hardness and the size morphology of eutectic Si with pouring temperatures and input voltages were investigated. At the same pouring temperature, with increasing input voltage, aspect ratio, standard deviation and primary grain size were decreased. The optimum condition for fabrication of semisolid Al alloys by EMS horizontal continuous casting process was determined that the input voltage was 220V and the pouring temperature was 68$0^{\circ}C$. At this optimum conditions the primary grain size was 54$\mu\textrm{m}$, the aspect ratio was 1.56 and the size of eutectic Si was 0.5$\mu\textrm{m}$. The micro-hardness of the Al alloy was 72.1 Hv. The semi-solid A356 Al alloy which has very low aspect ratio and standard deviation value could be fabricated by adopting the EMS horizontal continuous casting facility that was manufactured for this study.

• Journal of Microbiology and Biotechnology
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• 제20권3호
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• pp.609-614
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• 2010

The effluent from anaerobic digestion contains organic nitrogen and phosphorus, which are both required for growth of Spirulina platensis. Effluent (20%) from the upflow anaerobic sludge blanket (UASB) from a pig farm, supplemented with 4.5 g/l sodium bicarbonate ($NaHCO_3$) and 0.2 g/l urea fertilizer (46:0:0, N:P:K), was found to be not only a suitable medium for the growth of Spirulina platensis but also a low-cost alternative. Cost calculation showed that this medium is 4.4 times cheaper than modifized Zarrouk's medium. The average productivities of a semi-continuous culture grown under outdoor conditions in a 6-1 scale and a 100-1 pilot scale were 19.9 $g/m^2/d$ and 12 $g/m^2/d$, respectively. In addition, the biomass of organisms grown in UASB effluent contained approximately 57.9% protein, 1.12% $\gamma$-linolenic acid, and 19.5% phycocyanin. The average rates of bicarbonate, total nitrogen, and phosphorus removal were 380 mg/l/d, 34 mg/l/d, and 4 mg/l/d, respectively.

• Journal of Korean Society on Water Environment
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• 제23권6호
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• pp.927-933
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• 2007

Waste activated sludge (WAS) was thermally pretreated to enhance hydrolysis and ultimately methane yield. Batch and semi-continuous anaerobic digestion were conducted to evaluate the performance of methane fermentation of the hydrolyzed sludge and to investigate the kinetics of sludge fermentation. Thermal pretreatment remarkably enhanced digestion performances particularly the methane fermentation with three times more methane production than before the pretreatment. Gas production and kinetic parameters in the semi-continuous anaerobic digestion were estimated using Chen Hashimoto model. The model simulation fitted well the experimental results and the model was shown to be suitable for evaluating the effects of disintegration of WAS in anaerobic digestion. Three parameters ($B_o$, K, and ${\mu}_m$) determined by model simulation were $0.0807L-CH_4/g-VS$, 0.453 and $0.154d^{-1}$ for control sludge, and $0.253L-CH_4/g-VS$, 0.835 and $0.218d^{-1}$ for thermally pretreated sludge, respectively.

• Environmental Engineering Research
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• 제10권6호
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• pp.283-293
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• 2005

Characteristics of sulfur-based autotrophic denitrification in a semi-continuous type reactor and the kinetic parameters were studied. Enriched autotrophic denitrifying culture was used for the reactor operation. Biomass growth on sulfur particles and in the liquid medium was monitored using the DAPI staining method. From the result of ion concentration changes and the biomass growth, maximum specific growth rate, ${\mu}_{max}$, and the half velocity constant, $K_M$, were estimated as $0.61\;d^{-1}$ and 3.66 mg/L, respectively. Growth yield coefficient, Y values for electron acceptor and donor were found as 0.49 gVSS/g N and 0.16 gVSS/g S. The biomass showed specific denitrification rate, ranging 0.86-1.13 gN/g VSS-d. A half-order equation was found to best simulate the denitrification process in the packed bed reactor operated in the semi-continuous mode.

• Bulletin of the Korean Mathematical Society
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• 제45권4호
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• pp.763-780
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• 2008

An Ostrowski type inequality is developed for estimating the deviation of the integral mean of an absolutely continuous function, and the linear combination of its values at k + 1 partition points, on a segment of (real) linear spaces. Several particular cases are provided which recapture some earlier results, along with the results for trapezoidal type inequalities and the classical Ostrowski inequality. Some inequalities are obtained by applying these results for semi-inner products; and some of these inequalities are proven to be sharp.

• 한국전산유체공학회:학술대회논문집
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• 한국전산유체공학회 2007년도 추계 학술대회논문집
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• pp.243-248
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• 2007

A three-dimensional (3D) unstructured hydrodynamic solver for transient two-phase flows has been developed. A two-fluid three-field model was adopted for the two-phase flows. The three fields represent a continuous liquid, an entrained liquid, and a vapour field. The hydrodynamic solver is for the 3D component of a nuclear system code and the component-scale analysis tools for transient two-phase flows. The finite volume method and unstructured grid are adopted, which are useful for the flows in a complicated geometry. The semi-implicit ICE (Implicit Continuous-fluid Eulerian) numerical scheme has been adapted to the unstructured non-staggered grid. This paper presents the numerical method and the preliminary results of the calculations. The results show that the numerical scheme is robust and predicts the phase change and the flow transitions due to boiling and flashing problems well.

• Korean Journal of Child Studies
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• 제30권3호
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• pp.113-125
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• 2009

This study advances knowledge of developmental patterns in poverty and delinquency; data was obtained from waves 1-5 (2003-2007) of the Korea Youth Panel Survey. Semi-parametric group-based modeling (SGM) identified 4 trajectories of poverty from age 13 to 17 : non-poor, poverty increasing, low-level continuous poverty and chronic poverty groups and five developmental trajectories of delinquency : non-offending, late onset, low-level continuous, desisting, and chronic groups. A joint trajectory method predicted patterns of delinquency conditional on poverty trajectories. Chronic and low-level continuous poverty groups were more likely than others to follow chronic trajectories of delinquency; the non-poor group was more likely to be non-offending. Implications of this study for youth welfare were discussed to reduce risk for delinquency.

• Transactions of Materials Processing
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• 제23권3호
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• pp.178-183
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• 2014

Continuous casting is a process where molten metal is solidified into a semi-finished billet on a large scale with either a rectangular or round cross section for subsequent processing. The use of continuous casting provides an opportunity for producing material on a practical industrial scale with lower cost than conventional casting. In the current study, the material was fabricated by continuous casting and subsequent extrusion. Tensile tests were conducted on continuous cast ZK60A after extrusion over a range of strain rates at temperatures from 473K to 623K. The alloy exhibits a quasi-superplastic behavior with a maximum recorded elongation of ~250% at 523K when tested with an initial strain rate of $10^{-5}/s$. The experiments give a strain rate sensitivity exponent of 0.3~0.4 and an activation energy of 108 kJ/mol. From the current investigation, it was found that the high-temperature plastic flow of the ZK60A is controlled by a dislocation viscous glide mechanism.