• Journal of the Korea Institute of Military Science and Technology
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• v.21 no.4
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• pp.529-540
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• 2018

As the equipment of the military has recently become more sophisticated and expensive, the cost of purchasing spare parts is also steadily increasing. Therefore, demand forecast accuracy is also becoming an issue for the effective execution of the spare parts budget. This study predicts the demand by using the data of spare parts consumption of the KF-16C fighter which is being operated in the Republic of Korea Air Force. In this paper, SARIMA(Seasonal Autoregressive Integrated Moving Average) is applied to seasonal data after dividing the spare parts consumptions into seasonal data and non-seasonal data. Proposing new methods, Majority Voting and Hybrid Method, to the non-seasonal data which consists of spare parts of low consumption with unclear pattern, We want to prove that the demand forecast accuracy of spare parts improves.

• Korean Journal of Biological Psychiatry
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• v.17 no.3
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• pp.153-160
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• 2010

Objectives : Recurrence of mood episodes associated with a specific season has been described in various mood disorders. Seasonal change in mood and behavior as a lifetime trait is also observed in healthy individuals. This study aimed at comparing the lifetime trait of seasonal variations of mood and behavior between bipolar disorder patients and controls as well as investigating associated factors of seasonality. Methods : Subjects were ninety-four clinically stable patients with bipolar disorder and 188 age- and sex-matched healthy controls. Seasonality of mood and behavior was assessed retrospectively on lifetime basis using Seasonal Pattern Assessment Questionnaire(SPAQ). Results : The patient group showed a higher median global seasonality score(GSS) of SPAQ and a higher rate of seasonal affective disorder(SAD) compared to the control group(p < 0.0001). For subjects showing prominent seasonality, the seasonal symptom profile and seasonal pattern was similar in both patient and control groups. In addition to the diagnosis, female gender was shown to be a predictor of seasonality in the multiple linear regression analysis(p = 0.045). Conclusion : This study suggests that lifetime trait of seasonality may be related to the susceptibility of bipolar disorder.

• Journal of Environmental Science International
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• v.21 no.3
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• pp.327-337
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• 2012

Air pollution inventories are aggregated around south-eastern part of the Korean Peninsular including Busan, Ulsan, and Changwon cities. Because densely populated cities are concentrated in this region, air pollutants emitted from one of these cities tend to be impacted on the air quality of other cities. In order to clarify the seasonal movement pattern of emitted particles, several numerical simulations using WRF/FLEXPART were carried out. Four cases were selected for each season. The Weather Research and Forecasting model (WRF) reproduced atmospheric flow fields with nested grids. The seasonal pattern of air mass of study area was determined by backward and forward trajectories. As a result, the air parcel moves from northwest to southeast due to northwesterly winds in spring and winter. Also air parcel transports from south to north in summer, and moves from west to east. Because the air mass moves differently in each season, these characteristics should be considered when performing air quality analysis.

• Journal of Environmental Science International
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• v.28 no.12
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• pp.1123-1131
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• 2019

In this study, we investigated the spatial range, distribution pattern, temporal appearance, sex ratio, seasonal pattern, and size of the population of Leptalina unicolor locally inhabiting the wetland protection area in the Jaeyaksan Mountain. We found that the butterfly was distributed across four areas at 750 m above sea level and in an area of 96,000 ㎡. in the southeastern slope of the mountain. The discontinuous distribution of the butterflies in the meadow. According to our survey conducted from 2012 to 2014, L. unicolor occurred in May (spring) and July (summer) each year, with the male population more than three times higher than that of the female population. The population size estimated using the mark and recapture method on the back of the hind wing in the two years was as follows: 877±502 and 1243±800 individuals in the spring and summer of 2012, respectively, and 783±429 and 506±365 individuals in the spring and summer of 2014, respectively, suggesting no specific seasonal pattern. The findings of this study are expected to be useful for the conservation of the populations and habitats of L. unicolor, which are currently distributed locally due to a decrease in population size.

• Communications for Statistical Applications and Methods
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• v.16 no.2
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• pp.335-348
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• 2009

Fuzzy regression is used as a complement or an alternative to represent the relation between variables among the forecasting models especially when the data is insufficient to evaluate the relation. Such phenomenon often occurs in seasonal time series data which require large amount of data to describe the underlying pattern. Semiparametric model is useful tool in the case where domain knowledge exists about the function to be estimated or emphasis is put onto understandability of the model. In this paper we propose fuzzy semiparametric support vector regression so that it can provide good performance on forecasting of the seasonal time series by incorporating into fuzzy support vector regression the basis functions which indicate the seasonal variation of time series. In order to indicate the performance of this method, we present two examples of predicting the seasonal time series. Experimental results show that the proposed method is very attractive for the seasonal time series in fuzzy environments.

• The Korean Journal of Ecology
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• v.11 no.2
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• pp.77-82
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• 1988

2, 300 specimens of Cobitis taenia lutheri were collected at the Samchon stream, Kui-myon, Wanju-gun, Chollabuk-do province from December, 1984 to November, 1985. Sex ratio and specific lateral color pattern of this subspecies were investigated. During the spawning season, May to Augustm sex dimorphisms in lateral color pattern were remarkable, that is the striped type appeared in most of males and the spotted type largely in femals. Besides the spwaning season both male and female showed the spotted type. These seasonal varaitions of the lateral color pattern were considered to be a significant biological characteristics in this taxon.

• Journal of Environmental Science International
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• v.9 no.6
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• pp.483-488
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• 2000

In this study, the distribution characteristics of volatile organic compounds (VOCs) were investigated on the seasonal basis across spring, summer, and fall during the year of 1998. According to this analysis, most VOC species investigated exhibited strong temporal trends. Over diurnal scale, there distribution characteristics were affected by seasonal factors strongly. While they showed high day/night ratio pattern during spring, the pattern was reversed during fall. When the seasonal mean values were compared between the two seasons, the spring values were systematically higher than their counterparts in most cases. In addition when our VOC measurement date were compared with those reported from elsewhere, we were able to conclude that the VOC levels in the study area are comparable to the level weakly impacted by the regional emissions of VOCs. Although our data are not sufficient enough to systematically explain the atmospheric distribution and behavior of VOCs, the findings of strong correlations among some of VOC species suggests strong need for investigating their interactions in the earth\`s atmosphere.

• The Korean Journal of Zoology
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• v.39 no.3
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• pp.325-336
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• 1996

Community organization of the drosophilid flies was investigated with respect to the seasonal variation in species abundance and vertical microdistribution on the basis of the trapped collections in the two natural forests on Cheju-do from May to October 1994. The dominant species were Drosophila bizonata, D. curviceps, D. lutescens, D. angu leris, D. tsigana and D. immigrans in the annual collections. The pattern in seasonal changes of the dominant species was similar at the two survey sites. Seasonal fluctuation in the species diversity was more affected by evenness than by species richness (number of species). The seasonal variation of abundance showed an unimodal pattern in all of the dominant species. The seasonal patterns of vertical microdistribution revealed difference in some of the dominant species between the two survey sites. These results suggest that the predominant species in the forest avoid niche overlap by means of seasonal separation of breedings and that the vertical microdistribution is strongly affected by factors associated with season and vertical site in the deep wooded forests.

• Proceedings of the Korean Society of Life Science Conference
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• 2008.10a
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• pp.45.2-45.2
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• 2008

• Proceedings of the KIEE Conference
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• 2003.11a
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• pp.450-453
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• 2003

This paper presents the estimation on Load Characteristic Factor(k) which is considered to load pattern and seasonal characteristic of consumer. We can calculate the loss of distribution networks through the equation composing of Load Factor(LF), Loss Load Factor(LLF) and load characteristic factor(k). This equation is similar to the method of Regulator-General Victoria, Australia. Generally, the conventional method for calculating the distribution losses uses k with a constant value from 0.1 to 0.3. However, the k which is a relationship between LF and LLF can be varied by load pattern and seasonal characteristics. It is necessary to estimate the k according to load characteristics. This paper shows the result for recalculating k using the KEPCO's SOMAS data measured in distribution networks.