• 수산경영론집
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• 제51권2호
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• pp.51-69
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• 2020

The purpose of this study is to construct an outlook model that is consistent with the "Fisheries Outlook" monthly published by the Fisheries Outlook Center of the Korea Maritime Institute(KMI). In particular, it was designed as a partial equilibrium model limited to abalone items, but a model was constructed with a dynamic ecological equation model(DEEM) system taking into account biological breeding and shipping time. The results of this study are significant in that they can be used as basic data for model development of various items in the future. In this study, due to the limitation of monthly data, the market equilibrium price was calculated by using the recursive model construction method to be calculated directly as an inverse demand. A model was built in the form of a structural equation model that can explain economic causality rather than a conventional time series analysis model. The research results and implications are as follows. As a result of the estimation of the amount of young seashells planting, it was estimated that the coefficient of the amount of young seashells planting from the previous year was estimated to be 0.82 so that there was no significant difference in the amount of young seashells planting this year and last year. It is also meant to be nurtured for a long time after aquaculture license and limited aquaculture area(edge style) and implantation. The economic factor, the coefficient of price from last year was estimated at 0.47. In the case of breeding quantity, it was estimated that the longer the breeding period, the larger the coefficient of breeding quantity in the previous period. It was analyzed that the impact of shipments on the breeding volume increased. In the case of shipments, the coefficient of production price was estimated unelastically. As the period of rearing increased, the estimation coefficient decreased. Such result indicates that the expected price, which is an economic factor variable and that had less influence on the intention to shipments. In addition, the elasticity of the breeding quantity was estimated more unelastically as the breeding period increased. This is also correlated with the relative coefficient size of the expected price. The abalone supply and demand forecast model developed in this study is significant in that it reduces the prediction error than the existing model using the ecological equation modeling system and the economic causal model. However, there are limitations in establishing a system of simultaneous equations that can be linked to production and consumption between industries and items. This is left as a future research project.

• 대한교통학회지
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• 제26권5호
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• pp.81-90
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• 2008

버스노선개편 및 환승요금무료와 같은 대중교통체계개편을 실시함에 따라 시내버스 이용자들이 개편된 노선에 익숙히 대처하기 위해서는 일정기간이 소요된다. 따라서 본 연구는 시내버스 승객수요의 월별 특성에 대해 분석하고, 시계열분석을 실시함으로써 버스노선개편 이후에 변화하는 시내버스 승객수요가 다시 안정된 월별특성을 나타내기까지의 기간에 관하여 연구하고자 한다. 먼저 여러 도시들의 시내버스 승객수요가 공통된 월별 특성을 나타내는지 분석하기 위해 켄달의 일치계수검정을 실시하였다. 또한 노선개편으로 인해 변화된 승객수요가 일정한 패턴을 보이는 기간을 분석하기 위해 시계열분석으로 예측된 2006년의 시내버스 월별 승객수와 실제 집계된 시내버스 월별 승객수를 비교하였다. 이에 따라 각 도시들은 공통된 월별 특성을 보이는 것으로 분석되었고, 대구광역시는 약 6개월 뒤에 예측값과 실제값이 같은 패턴으로 변화하는 것으로 분석되었다. 본 연구는 타도시에서도 적용이 가능하며 시내버스 승객수요의 미시적인 예측과 평가에 활용될 것으로 기대된다.

• 대한원격탐사학회지
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• 제40권1호
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• pp.81-91
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• 2024

전기 에너지는 현대 문명의 핵심 에너지원으로 발전량, 전력 소모량의 변화 추이는 산업 및 생활 전반과 밀접한 관계가 존재한다. 본 연구에서는 남한 지역의 발전량과 야간광 값 사이의 상관관계를 파악하고 이를 이용하여 북한 지역의 월간 발전량 추이를 예측하였다. 연구 결과 서울시의 경우 야간광과 발전량 사이에는 0.34의 낮은 피어슨(Pearson) 상관계수를 보였으나 월 평균 기온을 이용하여 서울시의 가중치가 적용된 야간광 값과 발전량 사이에는 0.79의 높은 피어슨 상관계수를 보였다. 평양시의 월 평균 기온을 이용한 서울시의 가중치가 적용된 야간광 값을 이용하여 북한 지역의 월간 발전량 추이를 예측한 결과 2020년, 2021년 12월의 전월 대비 발전량 상승폭보다 2022년 12월의 전월 대비 발전량 상승폭이 약 60% 높은 것으로 나타났다. 본 연구의 결과는 월간 발전량 자료가 존재하지 않아 기민한 산업 동향 등의 파악이 힘든 지역의 월간 발전량의 추이를 예측하는데 도움이 될 것으로 기대된다.

• 한국농공학회지
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• 제23권4호
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• pp.46-52
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• 1981

The aim at this study has the stochastic hydrological analysis for the annual mean discharge and monthly discharge which were observed at Lobith of River Rhine in the Netherlands from 1901 to 1972. After this study was analysed by computer IBM 370 and Hewlett Parkard 9800, the results were as follows; 1.When 72 data was divided into two groups of subsample data as 36 data, they do not have their properties to be non-homogeneous and inconsistent due to F-test and t-test. 2.The credit limits of the serial correlation coefficient was fluctuated $\pm$0. 231 which was shown in Fig. 3. at significant level 99% by Anderson's test. 3.The correlogram at short term was shown to be no short-term persistence as Fig. 3. 4.Since the correlogram at long term has displayed that Hurst's coefficient was 0.6144 between 0.6 and 0.7, it was to be no long-term persistence. 5.The stochastic model with annual discharge of this River Rhine was shown with $\chi$t=2195+483. 8 $\varepsilon$t as $\chi$t=$\mu$+oet and $\varepsilon$t=$_1$ø$\varepsilon$t-$_1$+ζt where t=1,2,3,..., ζt is an independent series with mean zero and variance (1-ø2), $\varepsilon$t is the dependent series, and 4' is the parameter of the model. 6.The serial correlation coefficient of monthly discharge was explained as $\chi$$_1$ = 0.34 . sin(6-$\pi$t+$\pi$) as Fig.4. and the River Rhine has no large fluctuation and smoothly changed during that time.

• Journal of Astronomy and Space Sciences
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• 제29권3호
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• pp.259-267
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• 2012

Polar cap potential has long been considered as an indicator for the amount of energy flowing in the magnetosphere-ionosphere system. Thus, the estimation of polar cap potential is important to understand the physical process of the magnetosphere. To estimate the polar cap potential in the Northern Hemisphere, merging electric field by Kan & Lee (1979) is adopted. Relationships between the PC index and calculated merging electric field ($E^*$) are examined during full-time and storm-time periods separately. For this purpose Dst, AL, and PC indices and solar wind data are utilized during the period from 1996-2003. From this linear relationship, polar cap potential (${\Phi}^*$) is estimated using the formula by Doyle & Burke (1983). The values are represented as $58.1{\pm}26.9$ kV for the full-time period and $123.7{\pm}84.1$ kV for a storm-time period separately. Considering that the average value of polar cap potential of Doyle & Burke (1983) is about 47 kV during moderately quiet intervals with the S3-2 measurements, these results are similar to such. The monthly averaged variation of Dst, AL, and PC indices are then compared. The Dst and AL indices show distinct characteristics with peaks during equinoctial season whereas the average PC index according to the month shows higher values in autumn than in spring. The monthly variations of the linear correlation coefficients between solar wind parameters and geomagnetic indices are also examined. The PC-AL linear correlation coefficient is highest, being 0.82 with peaks during the equinoctial season. As with the AL index, the PC index may also prove useful for predicting the intensity of an auroral substorm. Generally, the linear correlation coefficients are shown low in summer due to conductance differences and other factors. To assess the role of the PC index during the recovery phase of a storm, the relation between the cumulative PC index and the duration is examined. Although the correlation coefficient lowers with the storm size, it is clear that the average correlation coefficient is high. There is a tendency that duration of the recovery phase is longer as the PC index increases.

• 한국물환경학회지
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• 제25권1호
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• pp.7-17
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• 2009

Soil and Water Assessment Tool (SWAT) was used to assess the impact of potential future climate change on the water cycle and soil loss of the Daecheong reservoir watershed. A sensitivity analysis using influence coefficient method was conducted for two selected hydrological input parameters and three selected sediment input parameters to identify the most to the least sensitive parameters. A further detailed sensitivity analysis was performed for the parameters: Manning coefficient for channel (Cn), evaporation (ESCO), and sediment concentration in lateral (LAT_SED), support practice factor (USLA_P). Calibration and verification of SWAT were performed on monthly basis for 1993~2006 and 1977~1991, respectively. The model efficiency index (EI) and coefficient of determination ($R^2$) computed for the monthly comparisons of runoffs were 0.78 and 0.76 for the calibration period, and 0.58 and 0.65 for the verification period. The results showed that the hydrological cycle in the watershed is very sensitive to climate factors. A doubling of atmospheric $CO_2$ concentrations was predicted to result in an average annual flow increase of 27.9% and annual sediment yield increase of 23.3%. Essentially linear impacts were predicted between two precipitation change scenarios of -20, and 20%, which resulted in average annual flow and sediment yield changes at Okcheon of -53.8%, 63.0% and -55.3%, 65.8%, respectively. An average annual flow increase of 46.3% and annual sediment yield increase of 36.4% was estimated for a constant humidity increase 5%. An average annual flow decrease of 9.6% and annual sediment yield increase of 216.4% was estimated for a constant temperature increase $4^{\circ}C$.

• 대한토목학회논문집
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• 제13권4호
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• pp.163-176
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• 1993

영향계수(影響係數)를 이용한 QUAL2E 반응계수(反應係數)의 최적추정 방법을 수립하여 충주댐부터 남한강수계 하류단까지의 하천구간에 적용하였다. 댐유입량 및 방류량 자료를 이용한 물수지 분석으로부터 1990년 월별 지천유입량을 산정하여 월별 수질 측정자료와 함께 반응계수(反應係數)의 추정에 사용하였다. 모의 수질항목으로서 chl.a, 질소 및 인순환 요소들, BOD 및 DO 등을 포함하였다. 수질변화에 영향이 큰 반응계수(反應係數)들을 선정하기 위하여 민감도(敏感度) 분석을 실시하였으며, 그 결과로서 11개의 추정 반응계수(反應係數)를 선정하였다. QUAL2E 반응계수(反應係數)의 추정에 사용된 영향계수법(影響係數法)에 의한 최적 추정방법은 계수들이 최적치에 빨리 수렴하도록 하는 유용한 방법임이 입증되었다. 모든 추정계수들이 3번 이내의 반복추정으로 최적치에 수렴하였다.

• 수산해양기술연구
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• 제39권1호
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• pp.44-49
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• 2003

1995년부터 2002 년까지 마산만의 4개 정점에서 3-4개윌 간격으로 관측한 투명도 자료를 정리하여 다음과 같은 결과를 얻었다. 1) 4개 정점에서 각각 33회씩 관측한 자료에서 투명도의 범위는 0.2∼7.2m 이었고 , 평균은 2.4m이었으며 변동계수는 60%이었다. 평균은 만의 외해쪽으로 갈수록 증가하였고, 변동계수는 만의 안쪽으로 갈수록 큰 경향을 보였다. 2) 투명도의 월평균은 4월과 7 월에 비교적 낮고, 10 월 이후에 높게 나타났다. 3) 계절평균은 봄과 여름에 유사한 수준으로 낮고, 가을과 겨울에 높은 경향을 보였으며, 변동계수는 봄에 가장 크고 다음이 여름이며, 가을과 겨울은 같은 수준을 나타내었다. 4) 연평균은 4개의 정점에서 모두 1995년과 1998년에 낮은 값을 보였으며, 변동계수는 1996년과 1998년 및 2002년에 정점별 차이가 작게 나타났다. 5) 정점간의 상관성 검토에서 Sl 과 S4 정점의 투명도 변화가 다른 정점과 구별되었다. Sl 의 유별성은 지리적 특성에 기인하며, S4 의 유별성은 방류수와 관련이 있을 것으로 추정된다.

• 대한원격탐사학회:학술대회논문집
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• 대한원격탐사학회 1998년도 Proceedings of International Symposium on Remote Sensing
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• pp.20-25
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• 1998

Solar irradiation controls the exchange of heat energy between atmosphere and land or ocean, and becomes an important factors to the radiance flux at the surface and the biosphere. In order to estimate solar irradiance and earth albedo In Korea peninsula during 1996, GMS date and paramaterization model was combinationally used. In clear sky, the paramaterization model was used to estimate solar iradiance. Also in cloudy sky, the earth albedo was used to calculate the Interceptive effect of solar irradiance. The hourly solar irradiance [the hourly earth albedo] showed generally very low values with <1.00 MJ/m$^2$hr [high values with >0.65] on the middle part (36.00-36.50$^{\circ}$S) and the Southeastern part (near 34.50$^{\circ}$S) in Korea peninsula, respectively. Satellite estimates (GMS data) with pyramometer measurements (in-situ data) were compared for 21 observed stations. Totally, correlation coefficient showed high values with 0.85. In the monthly variation, correlation coefficient of the spring and summer with rms=about 0.42 MJ/m$^2$hr was better than the autumn and winter with rms >0.5 MJ/m$^2$hr. Generally monthly variations of correlation coefficient between satellite estimetes and pyranometer measurements showed r=0.936 in clear sky during 1 year except only May, June, July and August.

• 농업과학연구
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• 제48권4호
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• pp.815-829
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• 2021

The purpose of this study is to construct a flatfish outlook model that is consistent with the "Fisheries outlook" monthly publication of the fisheries outlook center of the Korea Maritime Institute (KMI). In particular, it was designed as a partial equilibrium model limited to flatfish items, but a model was constructed with a dynamic ecological equation model (DEEM) system, considering biological breeding and shipping times. Due to limited amounts of monthly data, the market equilibrium price was calculated using a recursive model method as the inverse demand. The main research results and implications are as follows. As a result of estimating young fish inventory levels, the coefficient of the young fish inventory in the previous period was estimated to be 0.03, which was not statistically significant. Because there is distinct seasonality, when estimating the breeding outcomes, the elasticity of breeding in the previous period was found to exceed 0.7, and it increased more as the weight of the fish increased, in addition, the shipment coefficient gradually increased as the weight increased, which means that as the fish weight increased, the shipment compared to the breeding volume increased. When estimating shipments, the elasticity of breeding in previous period was estimated to respond elastically as the weight increases. The price flexibility coefficient of the total supply was inelastically estimated to be -0.19. Finally, according to a model predictive power test, the Theil U1 was estimated to be very low for all of the predictors, indicating excellent predictive power.