• 무역학회지
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• 제45권5호
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• pp.75-89
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• 2020

The purpose of this paper was to analyze the trend of container volume using the Seasonal Autoregressive Intergrated Moving Average (SARIMA) model. To this end, this paper used monthly time-series data of the East Sea Rim from 2001 to 2019. As a result, the SARIMA(2,1,1)12 model was identified as the most suitable model, and the superiority of the SARIMA model was demonstrated by comparative analysis with the ARIMA model. In addition, to confirmed forecasting accuracy of SARIMA model, this paper compares the volume of predict container to the actual volume. According to the forecast for 24 months from 2020 to 2021, the volume of containaer increased from 60,100,000Ton in 2020 to 64,900,000Ton in 2021

• Industrial Engineering and Management Systems
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• 제12권3호
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• pp.244-253
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• 2013

In industries, shipping is an important issue in improving the forecasting accuracy of sales. This paper introduces a hybrid method and plural methods are compared. Focusing the equation of exponential smoothing method (ESM) that is equivalent to (1, 1) order autoregressive-moving-average (ARMA) model equation, a new method of estimating the smoothing constant in ESM had been proposed previously by us which satisfies minimum variance of forecasting error. Generally, the smoothing constant is selected arbitrarily. However, this paper utilizes the above stated theoretical solution. Firstly, we make estimation of ARMA model parameter and then estimate the smoothing constant. Thus, theoretical solution is derived in a simple way and it may be utilized in various fields. Furthermore, combining the trend removing method with this method, we aim to improve forecasting accuracy. This method is executed in the following method. Trend removing by the combination of linear and 2nd order nonlinear function and 3rd order nonlinear function is executed to the original production data of two kinds of bread. Genetic algorithm is utilized to search the optimal weight for the weighting parameters of linear and nonlinear function. For comparison, the monthly trend is removed after that. Theoretical solution of smoothing constant of ESM is calculated for both of the monthly trend removing data and the non-monthly trend removing data. Then forecasting is executed on these data. The new method shows that it is useful for the time series that has various trend characteristics and has rather strong seasonal trend. The effectiveness of this method should be examined in various cases.

• Journal of Photoscience
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• 제9권2호
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• pp.154-157
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• 2002

Direct, continuous, and accurate measurements of solar ultraviolet irradiance (290-400 nm: UVR) have been carried out since 1990, by using both band-spectral ultraviolet-B (290-320 nm: UV-B) and ultraviolet-A (320-400 nm: UV-A) radiometers at Tokai University in Hiratsuka, Japan (35$^{\circ}$N, 139$^{\circ}$E). From our observations, the following findings are provided: 1) an increasing trend in solar UV -B from Oct. 1990 to Sept. 2000; 2) a regional comparison of solar UVR in Japan; 3) the distinct characteristics of UV-B and UV-A irradiance, such as diffuse property, daily and seasonal variation; and 4) human body protection against solar UVR. An increasing 10-year trend in global solar UV - B in Hiratsuka corresponded to a decrease in the total ozone amount measured at Tsukuba (36$^{\circ}$N, 140$^{\circ}$E), giving supportive evidence for a direct link between these two parameters. Furthermore, a strong correlation was found between solar UV-B and total ozone amount from results of UVR measurements at four Tokai University monitoring stations dispersed throughout Japan. Additional results revealed different diffuse properties in global solar UV and in global solar total (300-3000 nm: Total) irradiances. For example, in the global UVR, the diffuse component was dominant: about 80 % independent of weather, with more than 60 % of global UV-B, and more than 50% of global UV-A with even a cloudless clear sky. On the other hand, the portion of the diffuse in the global total irradiance was very low, less than 10 % on a cloudless clear day. Daily and seasonal variations of UV -B and UV -A irradiances were found to be quite different, because of the marked dependence of UV -B irradiance on the atmospheric ozone amount. Moreover, UV -B irradiance showed large daily and seasonal variations: the ratio between maximum and minimum irradiances was more than 5. In contrast, the variation in UV-A was small: the ratio between maximum and minimum was less than 2. Three important facts are proposed concerning solar UVR protection of the human body: 1) the personal minimal erythema dose (MED); 2) gender based difference in MED values; and 3) proper colors for UVR protective clothing.

• International Union of Geodesy and Geophysics Korean Journal of Geophysical Research
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• 제23권1호
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• pp.39-51
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• 1995

Bidirectional transport trend using the sediment-transport path model was identified in the two areas, sand ridge area and tidal mudflat in Garolim Bay, which is located in the mid-western coast of Korean Peninsular. This model exhibits the two-dimensional view of clear sediment transport trend based on data of changes in sediment statistics such as mean, sorting, and skewness, Garolim Bay was selected to test for the sediment-transport path model developed by McLaren and Bowles [1985]. Line-S, a typical tidal mudflat and representative of the Garolim Bay tidal flats, is well tested by this model, showing a clear seasonal change and coarsening-trend seaward (case C). This indicates that strong ebb currents carried relatively coarser sediments seaward with respect to high energy regime. Seasonally, this energy regime slowly decreases toward the summer in contrast with an increase of energy regime of flood tides, carrying coarser sediments landward (case C) in the summer. However, the Line-D area does not show consistent transport trend with respect to time-series. Separated and scattered events show fining trend landward (case B) in the sand ridge itself. The finining-trend (case B) either seaward and landward is not chiefly important in both the entire Line-D area and sand ridge itself. Also, the coarsening-Trend (case C) landward is not significant in the sand ridge itself. Consequently, in reality, the selection of suitable and representative locations are very important to fit with this model.

• 한국해양학회지:바다
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• 제14권3호
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• pp.181-188
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• 2009

한반도서남해안의 고창군 명사십리 대조차조간대에서 계절에 따른 퇴적물 조직과 퇴적 환경 변화를 연구하였다. 표층 퇴적물은 연구지역 3개 측선(각 측선 당 15개) 45지점에서 겨울철(2월), 여름철(8월)에 채취하였다. 개방형 명사십리의 표층 퇴적물은 세립사와 중립사가 우세하며 해안선과 평행한 띠 모양으로 분포한다. 입도 분포 곡선은 복모드 분포를 보이며, 겨울철 조간대의 입도분포가 여름철에 비하여 조립하다. 겨울철에 중립사가 상부 조간대에 집중되고 세립사가 하부 조간대에 집중된다. 이는 겨울철 동안 조석작용보다 파랑 에너지가 크게 작용함을 의미한다. 겨울철과 비교하여 여름철에 상대적으로 세립한 평균입도와 조직변수들 간의 상관관계는 여름철에 조석 에너지의 영향이 상대적으로 크게 작용한다는 것을 의미한다. 명사십리 조간대에 대한 연구는 퇴적환경이 해안으로 불어오는 바람과 파랑 강도의 계절별 변화로 겨울철 파랑-우세 환경에서 여름철 조석-우세 환경으로 변화한다는 것을 보여준다.

• 한국수산과학회지
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• 제26권5호
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• pp.438-445
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• 1993

1991년 가을에는 1992년 여름 사이 아산만에서 otter trawl로 저어류 자료를 수집하여 저어류의 계절 및 정점간의 군집구조를 분석하였다. 출현한 34종 중, 참서대(Cynoglossus joyneri), 민태(Johnius belengeri), 곤어리(Thrissa koreana) 및 등가시치(Zoarces gillii)가 총 채집개체수의 $93\%$를 차지하였다. 위의 4종 중 부어류인 곤어리를 제외한 우점 3종은 저질이 세립질인 만 내부에서 생물량이 많았다. 각 계절 정점간 군집구조를 rank correlation을 이용하여 주성분 분석한 결과, 정점간에는 큰 차이가 없었고 계절에 따른 군집구조 변화는 뚜렷하였으며, 그 변화는 수온, 혹은 수온과 상관관계를 갖는 요인에 의하여 좌우됨을 알 수 있었다. 조사해역은 수온의 연교차가 크고, 조류에 의한 해수의 혼합이 활발하여 이에 적응한 소수종이 우점하고 이 우점저어류는 퇴적물의 입도에 따라 그 분포가 결정되지만, 출현 개체수가 적은 대부분의 종은 정점간에 큰 차이를 보이지 않고 계절에 따라 군집구조가 변하여 가는 것으로 보인다.

• 한국환경과학회지
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• 제25권2호
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• pp.217-229
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• 2016

The government has conducted a plan of total maximum daily loads(TMDL), which divides with unit watershed, for management of stable water quality target by setting the permitted total amount of the pollutant. In this study, BOD concentration trends over the last 10 years from 2005 to 2014 were analyzed in the Geumho river. Improvement effect of water quality throughout the implementation period of TMDL was evaluated using the seasonal Mann-Kendall test and a LOWESS(locally weighted scatter plot smoother) smooth. As a study result of the seasonal Mann-Kendall test and the LOWESS smooth, BOD concentration in the Geumho river appeared to have been reduced or held at a constant. As a result of quantitatively analysis for BOD concentration with exploratory data analysis(EDA), the mean and the median of BOD concentration appeared in the order of GH8 > GH7 > GH6 > GH5 > GH4 > GH3 > GH2 > GH1. The monthly average concentration of BOD appeared in the order of Apr > Mar > Feb >May > Jun > Jul > Jan > Aug > Sep > Dec > Nov > Oct. As a result of the outlier, its value was the most frequent in February, which is estimated 1.5 times more than July, and was smallest frequent in July. The outlier in terms of water quality management is necessary in order to establish a management plan for the contaminants in watershed.

• 대한치과교정학회지
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• 제47권5호
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• pp.298-305
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• 2017

Objective: This paper describes changes in the characteristics of patients seeking orthodontic treatment over the past decade and the treatment they received, to identify any seasonal variations or trends. Methods: This single-center retrospective cohort study included all patients who presented to Seoul National University Dental Hospital for orthodontic diagnosis and treatment between January 1, 2005 and December 31, 2015. The study analyzed a set of heterogeneous variables grouped into the following categories: demographic (age, gender, and address), clinical (Angle Classification, anomaly, mode of orthodontic treatment, removable appliances for Phase 1 treatment, fixed appliances for Phase 2 treatment, orthognathic surgery, extraction, mini-plate, mini-implant, and patient transfer) and time-related variables (date of first visit and orthodontic treatment time). Time series analysis was applied to each variable. Results: The sample included 14,510 patients with a median age of 19.5 years. The number of patients and their ages demonstrated a clear seasonal variation, which peaked in the summer and winter. Increasing trends were observed for the proportion of male patients, use of non-extraction treatment modality, use of ceramic brackets, patients from provinces outside the Seoul region at large, patients transferred from private practitioners, and patients who underwent orthognathic surgery performed by university surgeons. Decreasing trends included the use of metal brackets and orthodontic treatment time. Conclusions: Time series analysis revealed a seasonal variation in some characteristics, and several variables showed changing trends over the past decade.

• 한국수산과학회지
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• 제36권3호
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• pp.298-305
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• 2003

Seasonal variation in species composition of fish in the estuary of Saemangeum water in the western coast of Korea was determined using seasonal samples collected by an otter trawl from April 2001 to February 2002. Species compositions did not differ significantly among the 4 stations (p>0.05, Wilcoxon signed-rank test). The cumulative number of species and species diversity (H') approached asymptote after four 30-min trawl hauls. Therefore 30-min trawl samples from each of the four stations were pooled to represent each season. A total of 45 species 2758 individuals and 30,346.8 g of fish were collected during the study period. Of the fish collected Leiognathus nuchalis, Synechogobius hasta, Neosalanx jordani, Konosirus punctatus and Chaeturichthys stigmatias predominated in abundance accounting for $68\%$ of the total number of individuals. Seasonal variation of fish abundance showed a similar trend to those of the other western coastal waters of Korea. The resident species were collected only in spring and autumn. Number of species and biomass were highest in summer due to the catch of many migrating species. In winter catch amount was low, and only 7 species were collected.. Brackish water fishes were more abundant in the study area, and Johnius grypotus and Cynoglossus joyneri were not premominated compared to the other coastal waters. This difference in species compositions may be related to the lower salinity in this estuarine habitat than in the other western coastal waters of Korea.

• 한국환경과학회지
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• 제26권8호
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• pp.993-998
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• 2017

De-icing salts applied to roads during winter enable safe driving conditions. However, these salts are eventually displaced to roadside areas at which they can negatively impact soil, vegetation, and water resources. This purpose of this study is to determine the relationship between foliar damage ratio (NY = 0-25%, SY = 26-50%, CY = 51-75%) on roadside trees (Ginko biloba) and seasonal impact of de-icing salts on soil and vegetation. Thirty roadside trees were selected at 8 m intervals between the Konkuk and Judeok intersections in Chung-ju city. The results reveal that seasonal soil acidity is relatively alkaline for foliar damage ratio of Ginko biloba was CY compared to NY. Also, electronic conductivity of each seasonal sampling was recorded as high in winter and spring, whereas the opposite trend is observed in summer. Various plants species were identified in abundance under roadside trees within NY roadside sections. These same species were observed in reduced numbers within CY sections. Strong negative correlations were identified between foliar damage ratio on roadside trees and vegetation. This relationship may be a method to use in predicting the accumulation of de-icing salt and visible injuries on roadside trees.