• 한국멀티미디어학회논문지
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• 제25권1호
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• pp.82-91
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• 2022

In this paper, time series prediction method of photovoltaic power is introduced using seasonal autoregressive integrated moving average (SARIMA). In order to obtain the best fitting model by a time series method in the absence of an environmental sensor, this research was used data below 50% of cloud cover. Three samples were extracted by time intervals from the raw data. After that, the best fitting models were derived from mean absolute percentage error (MAPE) with the minimum akaike information criterion (AIC) or beysian information criterion (BIC). They are SARIMA (1,0,0)(0,2,2)14, SARIMA (1,0,0)(0,2,2)28, SARIMA (2,0,3)(1,2,2)55. Generally parameter of model derived from BIC was lower than AIC. SARIMA (2,0,3)(1,2,2)55, unlike other models, was drawn by AIC. And the performance of models obtained by SARIMA was compared. MAPE value was affected by the seasonal period of the sample. It is estimated that long seasonal period samples include atmosphere irregularity. Consequently using 1 hour or 30 minutes interval sample is able to be helpful for prediction accuracy improvement.

• Journal of the Korean Statistical Society
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• 제23권2호
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• pp.325-340
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• 1994

Effects of temporal aggregation on estimation for ARMA models are studied by investigating the Hannan & Rissanen (1982)'s procedure. The temporal aggregation of autoregressive process has a representation of an autoregressive moving average. The characteristic polynomials associated with autoregressive part and moving average part tend to have roots close to zero or almost identical. This caused a numerical problem in the Hannan & Rissanen procedure for identifying and estimating the temporally aggregated autoregressive model. A Monte-Carlo simulation is conducted to show the effects of temporal aggregation in predicting one period ahead realization.

• KIEAE Journal
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• 제13권2호
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• pp.67-76
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• 2013

The purpose of this study is to analyze the accessibility to the place for outdoor exercise. For that, the departure (resident) location of the users of outdoor exercise equipment within 12 parks in Seoul have been investigated. A total of 1,733 people have been surveyed during the two-week period between Aug.2 and Aug. 15 and 815 cases were analyzed. We also investigated demographic characteristics, access method and related factors such as location, climate and visiting time. The results were coded through ArcGis program and the accessibility to each exercise location, difference in regional accessibility and accessibility characteristics in terms of climate and time have been analyzed. The results are as follows: First, visitors to the Han River start from the places further than the visitors to the streamlines. Second, the average moving distance is longer for the users aged under-60 than for the users aged 60 and over to reach the exercise place. And the average moving distance for visitors to the Han River destination is the longest with 748 meters, followed by 203 meters for general parks and 92 meters for streamline parks, respectively. Third, in each non-waterfront parks, the moving distance by users under-60 was longer by about 230 meters than that by users 60 and over. Fourth, exercisers in the weekend travel more by 244 meters than those during the midweek users to reach the exercise place. Fifth, the number of visitors to the Han River increased in the weekend while visitors to the streamlines decreased in the same period. Sixth, the traveling length for bicycle users is three times as much as that for pedestrian visitors. And the departure locations of bicycle users were more widely distributed.

• 한국가스학회지
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• 제18권1호
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• pp.8-16
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• 2014

본 연구에서는 국내에서 발생한 가스사고를 분석하여 가스사고의 건수예측모델에 대하여 제시하였다. 가스사고 건수를 예측하기 위하여 단순이동평균법(3,4,5기간), 가중이동평균법 및 지수평활법을 적용해 본 결과, 4기간 이동평균법과 가중이동평균법에 의한 모델의 평균오차제곱합이 44.4와 43으로 가장 정확성이 높은 것으로 나타났다. 가스사고 발생건수 예측시스템을 개발함으로서 가스사고 예방활동에 적극 활용할 수 있을 것이다.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제16권8호
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• pp.2606-2626
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• 2022

In this paper, a unmanned aerial vehicle (UAV) access deployment algorithm is proposed, which is based on an improved virtual force model to solve the poor coverage quality of UAVs caused by limited number of UAVs and random mobility of users in the deployment process of UAV base station. First, the UAV-adapted Harris Hawks optimization (U-AHHO) algorithm is proposed to maximize the coverage of users in a given hotspot. Then, a virtual force improvement model based on user perception (UP-VFIM) is constructed to sense the mobile trend of mobile users. Finally, a UAV motion algorithm based on multi-virtual force sharing (U-MVFS) is proposed to improve the ability of UAVs to perceive the moving trend of user equipments (UEs). The UAV independently controls its movement and provides follow-up services for mobile UEs in the hotspot by computing the virtual force it receives over a specific period. Simulation results show that compared with the greedy-grid algorithm with different spacing, the average service rate of UEs of the U-AHHO algorithm is increased by 2.6% to 35.3% on average. Compared with the baseline scheme, using UP-VFIM and U-MVFS algorithms at the same time increases the average of 34.5% to 67.9% and 9.82% to 43.62% under different UE numbers and moving speeds, respectively.

• 한국대기환경학회지
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• 제1권1호
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• pp.33-41
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• 1985

In order to investigate the Phenomenon of Acid Precipitation, pH value and Anions of Fluroide, chloride, nitrite, phosphate, bromide, nitrate and sulfate were measured from the acid precipitations sampled around 7 districts over seoul area during period of 9 months from January till September, in 1985. From the distribution of pH value gatnered, acid precipitations were noticed during period from January till Aprill, and from as of April 22nd, situation gradually recovered. The average pH value till April showed comparatively low, ranging 4.0-5.0. The pH value of 4.5-5.6 in average over whole year reaches to similar level of those in Japan. Anion analysis revealed that the main factor of pH value in Seoul district attribute mainly to the sulfate ion and nitrate ion. Moreover, these Phenomena of acid precipitation in Seoul area appeared to concentrate on certain districts, and they are slowly moving toward other directions due to such factors as wind-velocity and directions.

• 한국수산과학회지
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• 제5권4호
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• pp.108-114
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• 1972

한국 남해의 동물성 플랑크톤 현존량은 $1963\~1971$년간의 자료로 분석한 결과 63개월을 일주기로 주기 변동을 하고 있으며. 그 주기성은 자기 상관 계수 $\gamma_k$=0.86으로 강한 편이다. 계절 순환 변동은 4월과 10월을 극대기로 하는 쌍봉성 변동을 하며, 그 경향은 대단히 뚜렷한데, 이것은 이 해역에 있어서 식물성 플랑크톤의 양적 소장과 중요한 관련성을 가지는 것으로 고찰된다.

• 물과 미래
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• 제10권1호
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• pp.39-51
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• 1977

본 연구는 기왕의 국내 전강우량 자료를 대상으로 관측기간, 관측지점 및 결측치의 보완등을 조회하여 최근 수문학 이론에 입각한 분석방법으로 한국확률강우량도를 작도한 연구내용이다. 기왕의 자료를 조회하여 이동평균법에 의한 편차의 백분율이 5% 이하에서 통계년수가 설정되는 연우량 및 최대이우량에 대하여 자료보유지점수가 103개 지점 및 100개 지점에 이르렀으며, 확률강우량도의 작도가 가능하였다. 그러나 장단시간(18시간미만) 우량자료보유지점수는 12개 지점에 불과하므로 작도상 무리하리라고 판단된 바 향후 10여년이 경과되어야 가능할 것으로 생각한다. 본 연구를 통하여 얻은 성과는 아래와 같다. 1) 이동평균법을 적용하여 산정한 통계년수로서는 모평균치에 대한 이동평균치의 극치편차의 백분율이 5% 정도라면 20년, 2%∼3%이면 30년으로 밝혀졌다. 2) 연우량 및 최대일우량 자료집단에 대하여는 통계년수 30년으로 확률강우량도 작성이 가능하였으며 18시간 미만의 우량자료집단은 1990년대에 이르러서 가능할 것으로 사료된다. 3) 확룰강우량 산정방법으로서는 필자의 Y∼k법을 적용함이 국내우량자료집단 해석이 간편하고 계산량이 훨씬 감 소되므로 적당할 것으로 생각된다. 4) 확률강우량도의 실질적인 활용도를 높이기 위하여는 확대도면의 작성과 보다 세분된 등우량선이 기입되어야 할 것이고 하루 속히 단시간 확률강우량도가 완성되어야 하리라고 생각한다.

• 복식문화연구
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• 제23권4호
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• pp.604-615
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• 2015

The objectives of this study were to investigate whether heel height changes in the U.S. market occur in a cyclical pattern and heel heights show greater within-year variability over time. Heel height data from U.S. Vogue's spring and fall editions were analyzed over the time period 1950~2014. A total of 1581 pieces of data were measured in millimeter units using Adobe Illustrator and standardized by dividing the height of the heel by the shoe length through the curved sole line. To analyze the cycle pattern of heel heights, the yearly averages were standardized by using three-year moving average technique to average out the irregular components of time series data and give a better indication of the long-term fluctuation of heel height. To identify the degree of within-year variability of heel height, the standard deviation of the average measurements for a year was calculated, and then decade averages were drawn from the yearly averaged standard deviation. One-way ANOVA was conducted to compare the within-year variability of data in heel height over the time period studied by decade. The results showed: First, there was a trend toward higher heels from the early 1950s to 2011. Second, four cyclical movements of heel height were observed from 1950 to 2007, and heel heights gradually decreased after 2008. Third, the within-year variability significantly increased over time, especially after the 1980s.

• Journal of Biosystems Engineering
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• 제42권2호
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• pp.117-125
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• 2017

Purpose: Damage to pulse crops by wild birds is a serious problem. The damage is to such an extent that the rate of damage during the period between seeding and cotyledon stages reaches 54.6% on an average. In this study, a crop-position detection method was developed wherein infrared (IR) sensors were used to determine the cotyledon position under a vinyl mulch. Methods: IR sensors that helped measure the temperature were used to locate the cotyledons below the vinyl mulch. A single IR sensor module was installed at three locations of the crops (peanut, red lettuce, and crown daisy) in the cotyledon stage. The representative thermal response of a $16{\times}4$ pixel area was detected using this sensor in the case where the distance from the target was 25 cm. A spatial image was applied to the two-dimensional temperature distribution using a non-integral moving-average method. The collected data were first processed by taking the moving average via interpolation to determine the frame where the variance was the lowest for a resolution unit of 1.02 cm. Results: The temperature distribution was plotted corresponding to a distance of 10 cm between the crops. A clear leaf pattern of the crop was visually confirmed. However, the temperature distribution after the normalization was unclear. The image conversion and frequency-conversion graphs were obtained based on the moving average by averaging the points corresponding to a frequency of 40 Hz for 8 pixels. The most optimized resolutions at locations 1, 2, and 3 were found on 3.4, 4.1, and 5.6 Pixels, respectively. Conclusions: In this study, to solve the problem of damage caused by birds to crops in the cotyledon stage after seeding, the vinyl mulch is punched after seeding. The crops in the cotyledon stage could be accurately located using the proposed method. By conducting the experiments using the single IR sensor and a sliding mechanical device with the help of a non-integral interpolation method, the crops in the cotyledon stage could be precisely located.