• The Korean Journal of Applied Statistics
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• v.31 no.2
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• pp.229-239
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• 2018

This paper introduces how to adopt the concept of temporal hierarchies to forecast time series data. Similarly as in hierarchical cross-sectional data, temporal hierarchies can be constructed for any time series data by means of non-overlapping temporal aggregation. Reconciliation forecasts with temporal hierarchies result in more accurate and robust forecasts when compared with the independent base and bottom-up forecasts. As an empirical example, we forecast traffic accident counts with temporal hierarchies and observe that reconciliation forecasts are superior to the base and bottom-up forecasts in terms of forecast accuracy.

• Journal of the Korean Solar Energy Society
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• v.32 no.1
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• pp.32-39
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• 2012

New and renewable energy systems(solar thermal system, photovoltaic system, geothermal system, wind power system) are environmentally friendly technologies and these in South Korea are very important measures to reduce greenhouse-gas(GHG) and to push ahead with Green Growth. The purpose of this paper is to analyze GHG mitigation potential by distribution of solar thermal system in housing sector with bottom-up model called 'Long-range Energy Alternative Planning system'. Business as usual(BAU) was based on energy consumption characteristic with the trend of social-economic prospects and the volume of housing. The total amount of GHG emission of BAU was expected to continuous increase from 66.0 million-ton $CO_{2e}$ in 2007 to 73.1 million-ton $CO_{2e}$ in 2030 because of the increase of energy consumption in housing. The alternative scenario, distribution of solar thermal system in housing sector had GHG mitigation potential 1.54 million-ton $CO_{2e}$ in 2030. The results of this study showed that new and renewable energy systems made a contribution of reducing the use of fossil fuel and the emission of greenhouse-gas in building.

• Spatial Information Research
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• v.17 no.1
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• pp.131-144
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• 2009

Recently, a lot of local autonomous entities are promoting Ubiquitous City(U-City) Construction by integrating Information Communication Technology(ICT) with city development, and also internationally, a lot of cities are making efforts to develop U-City to intensify a city's competitive strength and improve life quality of city dwellers. In keeping with such a stream of the times, each local autonomous entity and project developer are developing a lot of methodologies to establish optimal U-City in corresponding cities and also inquiring into a variety of development procedures, such as connecting existing urban development methods with information establishment methods. The method used usually is to establish Information strategy Plan(ISP) for a city which will be developed through consulting in the stage of city development planning. ISP is to establish vision & strategy for building the ubiquitous city and is a methodology including city vision, strategy, goal, and implementation method, etc. However, due to a lot of variables, such as a variety of city environment, establishment period, budget, information technology, and etc., it is difficult to contain establishment plans for every occasion in a similar method, in reality. Therefore, it is naturally necessary to suggest plans for city vision & strategy, and selection of element technology/service. Thus, this paper suggests models for vision & strategy establishment of U-City and suggests Top-Down Approach and Bottom-Up Approach method as a plan for U-City establishment. In addition, this paper analyzes general promotion methodologies for constructing U-City and analyzes how these two strategic methods [Top-Down Approach and Bottom-Up Approach] for city vision establishment are composed in such a methodology, to define and analyze its constituent plan.

• Journal of Korean Society of Transportation
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• v.17 no.1
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• pp.19-28
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• 1999

This study deals with developing Critical GaP Model and Merge Probability Model which describe traffic patterns in the microscopic view, for the Purpose of suggesting a proper design criteria within the climbing lane section. Minimum tolerance speeds at the end of the climbing lane are calculated 60km/hr for 2-lane freeway, and 75km/hr for 4-lane freeway. In case of 2-lane freeway, the result is same as existing design criteria. and a new value is 15km/hr higher than existing design criteria for 4-lane freeway. In addition, auxiliary length at the end of the climbing lane is needed about 200m for 4-lane freeway to adjust high minimum tolerance speed. Therefore we propose to increase minimum tolerance speed for 4-lane freeway.

• Korean Journal of Soil Science and Fertilizer
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• v.28 no.3
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• pp.233-240
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• 1995

Fick's diffusion equation was transformed into algebraic subsidiary equation with its initial and boundary conditions through Laplace transformation, and the subsidiary equation was transformed back on the basis of Burington's table of inverse transformations so that it became the solution of Fick's equation. The initial and boundary condition was for upward diffusion of salts into flooding water of constant depth from uniform polder soil of infinite depth containing constant concentration of salt. The derived solution was tested through comparison for its conformability with other solutions of simpler initial and boundary conditions. The importance of shallow transplanting of rice seedlings and salt removing by growing rice was mentioned on the basis of very slow desalting rate by diffusion calculated from the derived solutions.

• Journal of Climate Change Research
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• v.3 no.3
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• pp.183-193
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• 2012

In this study, the S University's energy usage, greenhouse gas emissions situation and potential reduction amount were analyzed using a long-term energy analysis model, LEAP. In accordance with the VISION 2020 and university's own improvement plans, S University plans to complete a second campus through expansion constructions by 2020 and by allocating the needed land. Accordingly, increases in energy usage and greenhouse gas emissions seem inevitable. Hence, in this study, the calculations of potential reduction amount by 2020 were attempted through the use of LEAP model by categorizing the energy used based on usage types and by proposing usage typebased reduction methods. There were a total of 4 scenarios: a standard scenario that predicted the energy usage without any additional energy reduction activity; energy reduction scenario using LED light replacement; energy reduction scenario using high efficiency building equipment; and a scenario that combines these two energy reduction scenarios. As scenario-based results, it was ascertained that, through the scenario that had two other energy reduction scenarios combined, the 2020 greenhouse gas emissions amount would be 14,916 tons of $CO_2eq$, an increase of 43.7% compared to the 2010 greenhouse gas emissions amount. Put differently, it was possible to derive a result of about 23.7% reduction of the greenhouse gas emissions amount for S University's greenhouse gas emissions amount through energy reduction activities. In terms of energy reduction methods, changing into ultra-high efficiency building equipment would deliver the most amount of reduction.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.20 no.12
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• pp.8-14
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• 2019

A drop structure, one of the representative river-crossing structures, is constructed to stabilize a riverbed. On the other hand, the structure interrupts the continuity of the river and causes the destruction of the hydro-ecological environment. Therefore, laboratory experiments of a natural type of drop structure with low differences were performed, and the empirical formula of a local scour hole is proposed. Four experimental flow rates were tested for various types of the drop structure models with 28 test cases. Based on the scour test, it was confirmed that the maximum scour depth occurs rather than the result of applying the previously proposed scour depth formulae. Correlation analysis of the major factors of scour hole at the downstream of the drop structure revealed a strong correlation between the upstream flow characteristics, drop structure height, and total crossing length of the drop model. In addition, the depth and length estimation formula of the maximum scour hole were proposed using the dimensionless variables and validated. In the future, it is also expected that more accurate scour prediction and calculation can be derived by conducting experimental studies and numerical analysis considering the various bed materials and flow conditions.

• Journal of Korean Society of Rural Planning
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• v.28 no.3
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• pp.49-59
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• 2022

Recently, Korea aimed to increase water use efficiency by implementing integrated management according to the water management unification policy. Considering the enormous use of water resources in the agricultural sector, it is necessary to efficiently conserve water in terms of demand management by intensifying the stakeholders' involvement and awareness campaigns. The existing agricultural water management system in Korea is based on a top-down approach by which the government agencies directly plan budgets and policies to be enforced on and implemented by farmers, with little to no involvement of farmers in the decision-making process. However, this process has hindered the desired water resources management and the water conservation goal at the field level. Moreover, the limited research on water governance operations focusing on agricultural water creates a knowledge gap, particularly in Korea. Thus, it is necessary to investigate water governance cases with successful implementations in agricultural and rural areas to identify the factors applicable to domestic governance in Korea. In addition, a more systematic governance model should be established by identifying the subjectivity of the stakeholders' involvement in agricultural water governance. Therefore, this study proposed a new bottom-up model for agricultural water governance, which aims to raise the problem of autonomous water governance while promoting stakeholders' voluntary participation in agricultural water management and reflecting farmers' involvement in the decision-making process. Moreover, if agricultural water governance is expanded nationwide by reflecting agricultural and water resource policies in the future, it is believed that positive effects can be achieved in increasing utilization efficiency and securing sustantiality through agricultural water saving.

• Proceedings of the Korea Water Resources Association Conference
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• 2021.06a
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• pp.365-365
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• 2021

기후변화로 인하여 발생하는 자연재해는 수많은 인명 및 재산 피해를 일으키며, 그 중에서도 가뭄은 물과 식량의 안보를 위협하고 있다. 이에 OECD(2015)는 미래의 세계 인구 40%가 2050년까지 물이 부족한 강 유역에서 살 것이라 예측하고 있으며, 물의 다층적 거버넌스를 개발하여 물을 효과적으로 사용하기 위한 상향식 의사결정, 통합물관리 체제의 개념을 제시하기도 하였다. 우리나라 역시 가뭄으로 인한 피해발생이 빈번하고, 그 강도나 범위가 점차 증가하는 추세이다. 하지만 2000년부터 한국농어촌공사(출범은 '농업기반공사')가 농업용수를 관리해오고 있으며, 농업용 수리시설의 증축, 관리 등이 공적인 관리쳬계로 변화해오면서 자연스럽게 농업인의 물관리는 배제되었다. 또한, 농업용수는 무상·무제한 공공재라는 인식과 농업인 평균 연령이 높아짐에 따라 농업인의 물꼬관리 및 수로 훼손, 무단취수 행위 등에 대한 제제가 불가능한 실정이다. 본 연구에서 최근 농식품부의 「2019년 정부가뭄종합대책」에 포함되어 있는 물절약 거버넌스 구축 및 운영 내용을 바탕으로 농업용수 관리 및 사용구조를 고려하여 두 개 지역의 농어촌공사(여주이천지사, 경주지사) 주도 하에 거버넌스를 간담회 형식으로 운영하였다. 농업용수 물절약 거번넌스 이해관계자들은 각 지역별 공기업, 공무원, 농업인, 언론인, 학계 전문가 등이 참가하였으며, 거버넌스 운영 2회 및 설문조사를 실시하였다. 그 결과 각 이해관계자들은 농업용수 절약을 위한 현재 문제점 및 해결방안 등에 대한 의견을 제시하였으며, 설문조사를 통하여 농어촌공사의 신뢰도 및 중요도가 가장 높고, 높은 중요도에 비하여 농업인 및 지자체 등은 신뢰도가 낮은 것을 확인 할 수 있었다. 이러한 결과는 농업인이 농업용수에 대한 주인의식을 가지고, 적극적이고 자발적인 참여가 필요하다는 것을 보여주고 있으며, 본 연구를 통하여 이루어진 간담회 형식의 거버넌스보다 운영효과 및 지속성을 유지할 수 있는 형태의 거버넌스가 연구되어야한다. 향후 농촌형물 거버넌스 모형이 개발되기 위하여 본 연구는 기초자료로 활용할 수 있다.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.7 no.1
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• pp.11-22
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• 1987

A plane buoyant jet discharged vertically upward into a crossflow is analyzed by numerical solution of the governing equations of continuity, momentum and constituent transport. The turbulent transport is modelled by the Prandtl's mixing length theory. In the numerical solution procedure, the governing equations are transformed by stream function and vorticity transport, non-dimensionalyzed by discharge velocity, slot width, and parameters representing flow characteristics, and solved by Gauss-Seidel iteration method with successive underrelaxation. The numerical experiments were performed for the region of established flow of buoyant jet in the range of discharge densimetric Froude number of 4 to 32 and in the range of velocity ratio of 8 to 15, which is the ratio of discharge velocity to crossflow velocity. Variations of velocities and temperatures, flow patterns and vorticity patterns of receiving water due to buoyant jet were investigated. Also investigated are the effects of velocity ratio and discharge densimetric Froude number on the trajectories of buoyant jet. Computed are velocities, temperatures and local densimetric Froude numbers along the trajectory of the buoyant jet. Spreading rate and dispersion ratio were analyzed in terms of discharge densimetric Froude number, local densimetric Froude number and distance from the source along the jet trajectory. It was noted that the similarity law holds in both the profiles of velocity and temperatures across the jet trajectory and the integral type analysis of Gaussian distribution is applicable.