• KEPCO Journal on Electric Power and Energy
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• v.3 no.1
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• pp.65-72
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• 2017

This study analyzed causal relationship between electricity consumption and economic output (GDP) for Korea from 2001 to 2014 employing the vector error-correction model estimation by manufacturing sector. The results of unit-roots tests show that all sectoral GDP and electricity consumptions were not stationary. And cointegration tests show that processed foods, Wood Pulp Paper, electricity apparatus, Precision Medical sectors had a linear combinations in the long run between electricity consumptions and economic growth. With respect to the direction of causality, manufacturing sector has a uni-directional running from economic output (GDP) to electricity consumption in short term. The results of study show that sectoral causal relation were different each other in short term and long term. These findings imply that electricity demand management policy focusing on efficiency improvement is necessary to minimize negative impacts on economic growth and to adopt suitable structural policies can induce energy conservation.

• Journal of Korea Water Resources Association
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• v.49 no.12
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• pp.981-993
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• 2016

This study explains the GIS database of flood inundation area developed for Samsung-1 Drainage Sector, Seoul, Korea. The XP-SWMM dual drainage model was developed for the study area, and the time series observed at the watershed outlet was used to obtain the watershed time of concentration and to calibrate the XP-SWMM model. The rainfall scenario was developed by dividing the 40 minute watershed time of concentration into two 20-minute time steps and then applying the gradually increasing 5 mm/hr interval rainfall intensity to each of the time step up to 200 mm/hr, which is the probable maximum precipitation of the study area. The developed rainfall scenarios was used as the input of the XP-SWMM model to obtain the database of the flood inundation area. The analysis on the developed GIS database revealed that: (1) For the same increment of the rainfall, the increase of the flooded area can be different, and this was caused by topographic characteristics and spatial formation of pipe network of the study area; (2) For the same flooded area, the spatial extent can be significantly different depending on the temporal distribution of rainfall; and (3) For the same amount of the design rainfall, the flood inundation area and the extent can be significantly different depending on the temporal distribution of rainfall.

• Proceedings of the KOR-KST Conference
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• 1998.10a
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• pp.265-274
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• 1998

본 논문은 도로를 주행하는 차량의 지점속도에 대하여 단기간(short-term)으로 예측하는 네 가지의 모형들에 대한 개발 및 결과의 비교하고 평가했다. 사용된 기법들로는 다중회귀분석, 시계열분석(ARIMA), 인공 신경망, 칼만필터링 등이며, 모형의 구출을 위하여 다수의 독립변수 및 입력변수가 요구되는 다중회귀분석과 인공 신경망에서는 연속방정식에서 고려되는 변수들간의 단순상관계수 및 편상관계수의 계산을 통해서 입력변수가 설정이 되었으며, 시계열분석(ARIMA)과 칼만필터링 등 단일 입력 변수만을 요하는 모형에서는 바로 전 시간대와 현재시간대의간격동안 속도의 변화량을 입력변수로 설정하였다. 속도를 비롯해서 교통 데이터는 현장자료를 사용하였는데, 이는 서울의 한강 옆에 위치한 올림픽대로 중 한강대로에 위치한 검지기 3개를 통해서 천호동 방면으로 이동하는 교통류에 대해서 17시간 (00시~17시)동안 수집했다. 17시간 수집했는데 그중에 검지된 속도는 14km/h에서 98km/h까지 변하는 등, 수집된 자료에는 다양한 교통상태가 포함되어 있는데 이는 각 모형들의 정확한 예측력과 적응성을 평가하기 위함이었다. 각 모형은 예측하고자 하는 시점으로부터 1, 5, 10, 15분 후의 속도를 예측하는 것으로 총 4가지의 예측시간간격으로 각각 실험되었다. 결과는 전반적으로 신뢰성 있게 나왔으나 그중에서도 정확성면에서는 인공신경망과 칼만필터링이 우수했고 적응성면에서는 칼만필터리딩 탁월했다. 또한 1분 후의 속도를 예측하는 결과들은 모형들간에 거의 비슷한 정확도를 보여주었는데 이는 입력변수의 설정이 중요한 것임을 보여주는 것이라 판단된다. 있는 기법이다.적으로 세부적 차종분류로 접근한다.의 영향들을 고려함으로써 가로망 설계 과정에서 가로망의 상반된 역할인 이동성과 접근성의 비교가 가능한 보다 현실적인 가로망 설계 모형을 구축하고자 한다. 지금까지 소개된 가로망 설계모형들은 용량변화에 대한 설계변수의 형태에 따라 이산적 가로망 설계 모형과 연속적 가로망 설계모형으로 나뉘어지게 된다. 본 논문의 경우, 계산속도의 향상 측면에서는 연속적 가로망 설계 모형을 도입할 수 있지만, 이때 요구되는 도로용량이 이산적인 변수(차선 수)로 결정되어야만 신호제어 변수를 결정할 수 있기 때문에, 이산적 가로망 설계 모형이 사용된다. 하지만, 이산적 설계모형의 경우 조합최적화 문제이므로 정확한 최적해를 구하기 위해서는 상당한 시간이 소요되며, 경우에 따라서는 국부 최적해에 빠지게 된다. 이러한 문제를 극복하기 위해, 우선 이상적 모형의 근사화, 혹은 조합최적화문제를 위해 개발된 Simulated Annealing기법의 적용, 연속적 모형의 변수를 이산화하는 방법 등 다양한 모형들을 고려해 본 뒤, 적절한 모형을 적용할 것이다. 가로망 설계 모형에서 신호제어를 고려하기 위해서는 주어진 가로망에 대한 통행 배정과정에서 고려되는 통행시간을 링크통행시간과 교차로 지체시간을 동시에 고려해야 하는데, 이러한 문제의 해결을 위해서 최근 활발히 논의되고 있는 교차로에서의 신호제어에 대응하는 통행배정 모형을 도입하여 고려하고자 한다. 이를 위해서 지금까지 연구되어온 Global Solution Approach와 Iterative Approach를 비교, 검토한 뒤 모형에 보다 알맞은 방법을 선택한다. 차량의

• Journal of Korea Water Resources Association
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• v.41 no.4
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• pp.379-394
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• 2008

Recently, extreme precipitation events beyond design capacity of hydraulic system have been occurred and this is the causes of failure of hydraulic structure for flood prevention and of severe flood damage. Therefore it is very important to understand temporal and spatial characteristics of extreme precipitation events as well as expected changes in extreme precipitation events and distributional characteristics during design period under future climate change. In this paper, climate change scenarios were used to assess the impacts of future climate change on extreme precipitation. Furthermore, analysis of future extreme precipitation characteristics and I-D-F analysis were carried out. This study used SRES B2 greenhouse gas scenario and YONU CGCM to simulate climatic conditions from 2031 to 2050 and statistical downscaling method was applied to establish weather data from each of observation sites operated by the Korean Meteorological Administration. Then quantile mapping of bias correction methods was carried out by comparing the simulated data with observations for bias correction. In addition Modified Bartlett Lewis Rectangular Pulse(MBLRP) model (Onof and Wheater, 1993; Onof 2000) and adjust method were applied to transform daily precipitation time series data into hourly time series data. Finally, rainfall intensity, duration, and frequency were calculated to draw I-D-F curve. Although there are 66 observation sites in Korea, we consider here the results from only Seoul, Daegu, Jeonju, and Gwangju sites in this paper. From the results we found that the rainfall intensity will be increased and the bigger intensity will be occurred for longer rainfall duration when we compare the climate conditions of 2030s with present conditions.

• Journal of Korea Water Resources Association
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• v.41 no.9
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• pp.959-967
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• 2008

Disaggregation techniques are widely used to transform observed daily rainfall values into hourly ones, which serve as important inputs for flood forecasting purposes. However, an important limitation with most of the existing disaggregation techniques is that they treat the rainfall process as a realization of a stochastic process, thus raising questions on the lack of connection between the structure of the models on one hand and the underlying physics of the rainfall process on the other. The present study introduces a nonlinear deterministic (and specifically chaotic) framework to study the dynamic characteristics of rainfall distributions across different temporal scales (i.e. weights between scales), and thus the possibility of rainfall disaggregation. Rainfall data from the Seoul station (recorded by the Korea Meteorological Administration) are considered for the present investigation, and weights between only successively doubled resolutions (i.e., 24-hr to 12-hr, 12-hr to 6-hr, 6-hr to 3-hr) are analyzed. The correlation dimension method is employed to investigate the presence of chaotic behavior in the time series of weights, and a local approximation technique is employed for rainfall disaggregation. The results indicate the presence of chaotic behavior in the dynamics of weights between the successively doubled scales studied. The modeled (disaggregated) rainfall values are found to be in good agreement with the observed ones in their overall matching (e.g. correlation coefficient and low mean square error). While the general trend (rainfall amount and time of occurrence) is clearly captured, an underestimation of the maximum values are found.

• The Korean Journal of Financial Management
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• v.22 no.2
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• pp.189-212
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• 2005

This study examines the interactions between KTB spot and futures markets using the daily prices from March 4, 2002 to January 31, 2005. We use Granger causality test, impulse Response Analysis and Variance Decomposition through vector autoregressive analysis (VAR). However, considering the long-term relationships between the level variables of KTB spot and futures, we introduced Vector Error Correction Model. The main results are as follows. According to the results of Granger-causality test and impulse response analysis, we find that the yields of KTB forward have a great influence on the change of KTB spot but not vice versa. In terms of volatility analysis, there is no inter-dependence between KTB forward and spot markets. In the variance decomposition analysis we find that the short-term KTB forward has much more impact on the KTB spot market than the long-term KTB forward does. We think these results are meaningful for bond investors who are in charge of capital asset pricing valuation, risk management and international portfolio management.

• Journal of Hospice and Palliative Care
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• v.19 no.4
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• pp.296-302
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• 2016

Purpose: This study examined the effectiveness of a hand massage combined with analgesics on pain control in hospice patients with terminal cancer. Methods: This study is a quasi-experimental study with a single group time series design. The study included 25 terminal cancer patients who were admitted to a hospice ward. Each patient's pain level was measured after analgesics use only (control group). When patients complained of pain again, the pain level was assessed after administering a combination of hand massage and analgesics (experimental group). As for the experimental treatment, the participants were provided with oil hand massage on each hand for 5 minutes. Results: The experimental group and the control group showed no significant differences in the changes of pain score (F=0.74, P=0.3939). Conclusion: Although the pain level of the experimental group did not significantly improve compared with the control group, their pain levels tended to be low to begin with. Thus, a complementary utility value of hand massage cannot be completely excluded in terminal cancer patients. Since the pain level significantly changed according to the dosage of analgesic, nurses need more education and research on analgesic drug therapy for terminal cancer patients.

• Journal of Korea Port Economic Association
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• v.32 no.4
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• pp.165-182
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• 2016

This study examines the competitiveness and cooperativeness among the container ports in East Asia by analyzing their monthly dynamics in eight years (2008-2015). Time series data on container throughput divided into origin and destination (O/D), such as the top six Chinese ports and the transshipment (T/S) ports such as Hong Kong, Busan, and Singapore, are computed with two methods based on the Vector Error Correction Model (VECM). The first Granger causality test results show that Busan T/S has significant bilateral relations with three Chinese O/D ports; and significant unidirectional relations with three other O/D ports. Shenzhen port has significant bilateral relations with Singapore, and has a significant unidirectional relation with Hong Kong port. Co-integrating test results showed that Busan holds negative co-integration with all Chinese O/D ports. Impulse response function (IRF) results show an opposite direction between paired ports. The ratios of the impulse from T/S ports are significantly high to one another in the short-run, but its power declines as time passes. The ratio of the impulse from the Chinese ports to T/S ports is less significant in the short-run period, however, it becomes more significant as time passes. The significance of most shocks was high in the second period, but was diluted after the sixth period.

• Proceedings of the Korea Water Resources Association Conference
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• 2019.05a
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• pp.387-387
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• 2019

우리나라는 최근 10년간 자연재난 중 호우로 인해 인명피해 약 120명, 재산피해 약 1조 4천억원을 기록하였으며, 또한 기후변화로 인해 강한 국지성 집중호우의 발생빈도가 높아질 것으로 예상됨에 따라 호우에 의한 침수피해가 증가될 것으로 예상된다. 특히 본 연구 대상지역인 인천시의 경우 도시화로 인해 인구밀도 및 불투수지역이 증가함에 따라 침수피해가 대형화되고 있는 실정이다. 이에 본 연구에서는 인천시와 같은 도심지역에서의 침수발생을 사전에 예측하고 침수발생에 대한 대비 대응을 위해 하수관망 해석을 위한 SWMM 모델과 침수해석을 위한 2DIS 모델을 연계하여 인천시 침수심 생산체계를 구축하고자 한다. 본 연구에 적용한 침수심 생산과정은 크게 강우자료 생산, 유역 및 하수관망 해석, 침수 해석 등 총 3단계 과정으로 구성된다. 강우자료 생산과정에서는 유역 및 하수관망 해석과 침수 해석을 위한 10분 단위 유역평균 강우량자료를 생산한다. 유역 및 하수관망 해석과정에서는 지형자료 및 강우자료를 이용하여 SWMM 모델을 통해 맨홀에서의 월류량 자료를 생산한다. 마지막으로 침수해석과정에서는 지형자료와 함께 앞서 두 과정을 통해 생산된 강우 및 맨홀 월류량 자료를 입력자료로 하여 2DIS 모델을 통해 10분 단위의 시계열 침수심 정보 및 격자별 최대 침수심정보를 생산한다. 본 연구에서의 공간해상도는 도심지역의 도로단위 고해상도 침수심 정보 생산을 위해 6m 단위로 하였으며, 시간해상도는 단시간에 발생하는 도심지역의 침수특성 반영을 위해 10분으로 하였다. 또한, 침수발생 시 발생한 강우의 지표흐름 영향을 반영하기 위해 빗물받이효율 변화에 다른 침수심을 분석하였다. 본 연구를 통해 도출된 모의 침수심 결과를 실제 침수피해사례 및 풍수해저감종합계획 결과와 비교하였으며, 다수 지역에서 실제 침수발생지역과 동일하게 침수가 발생한 것으로 나타났다. 또한, 전체적인 침수 양상이 유사하게 발생함을 확인하였다. 향후 관측자료를 이용한 하수관망 및 침수해석 모델의 최적화, 하천유량 예측을 통한 하류 기점수위의 반영 등을 통해 정확도를 개선할 수 있을 것으로 판단되며, 이를 통해 인천시 침수발생을 사전에 예측하여 침수피해에 대비 및 대응과 침수피해 발생 시 정확하고 상세한 원인 분석 및 예측이 가능할 것으로 기대된다.

• Korean Journal of Remote Sensing
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• v.38 no.6_1
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• pp.991-1005
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• 2022

Satellite imaging is an effective supplementary data source for detecting and verifying nuclear activity. It is also highly beneficial in regions with limited access and information, such as nuclear installations. Time series analysis, in particular, can identify the process of preparing for the conduction of a nuclear experiment, such as relocating equipment or changing facilities. Differences in the semantic segmentation findings of time series photos were employed in this work to detect changes in meaningful items connected to nuclear activity. Building, road, and small object datasets made of KOMPSAT 3/3A photos given by AIHub were used to train deep learning models such as U-Net, PSPNet, and Attention U-Net. To pick relevant models for targets, many model parameters were adjusted. The final change detection was carried out by including object information into the first change detection, which was obtained as the difference in semantic segmentation findings. The experiment findings demonstrated that the suggested approach could effectively identify altered pixels. Although the suggested approach is dependent on the accuracy of semantic segmentation findings, it is envisaged that as the dataset for the region of interest grows in the future, so will the relevant scope of the proposed method.