• Proceedings of the Korea Water Resources Association Conference
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• 2016.05a
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• pp.10-14
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• 2016

육상의 증발산량(evapotranspiration, ET)은 대기 중 수증기의 상변화를 통해 대기와 지표 사이의 물과 에너지 순환에 영향을 미치며, 강수량, 유출량과 함께 수자원에 영향을 미치는 주요 인자이다. 강수량과 유출량은 직접 관측이 가능한 반면, 증발산량은 숨어있는 잠열로서 관측하기 어렵다. 플럭스 타워나 라이지메타(Lysimeter) 등을 이용하여 증발산량을 직접 관측하고 있으나 이들 지상관측은 일부 지점(point)에서 제한적으로 이루어지고 있으며, 관측 지점의 수를 확대하게되면 관측 기기의 유지 보수 등의 많은 시간과 비용이 든다는 한계가 있다. 이러한 지상관측의 한계를 극복하고 넓은 영역의 증발산량 변화를 관측하기 위해 위성을 이용한 증발산량을 추정하는 연구가 활발히 진행되고 있다. 기상청 국가기상위성센터(National Meteorological Satellite Center, NMSC)에서는 우리나라 최초의 정지 기상 위성인 천리안 위성(Communication, Ocean and Meteorological Satellite, COMS) 자료를 지표 에너지 수지식(Surface Energy Budget Equation)에 적용하여 동아시아 지역의 지면과 식생 특성을 반영한 '일(daily) 증발산량 산출 알고리즘'을 개발하였다. 현열을 계산하기 위해 다양한 입력 변수가 사용되어지고 계산 과정이 복잡하기 때문에, 본 연구에서는 '반 경험적인 계수인 B 계수 모델'을 사용하여 현열 산출 기법을 단순화하였다. 본 알고리즘을 이용하여 2011년 4월부터 현재까지 동아시아(위도 $20{\sim}50^{\circ}N$, 경도 $100{\sim}145^{\circ}E$)의 해상도 1km의 일 증발산량을 산출하였고, 위성 증발산량의 검증을 위해 지면 특성이 다른 청미천(농경지), 설마천(혼효림) 지역의 플럭스 타워 증발산량 자료(유량조사사업단 제공)와 비교 분석하였다. 2011년 4월부터 2014년 12월까지 청미천 지역에서의 플럭스 타워 관측과 비교한 결과, 총 665개 자료에 대하여 RMSE는 2.82 mm/day, Bias는 2.56 mm/day의 결과를 보였다. 동일한 기간에 대하여 설마천 지역에서의 플럭스 타워 관측과 비교한 결과, 총 582개 자료에 대하여 RMSE는 1.92 mm/day, Bias는 1.45 mm/day의 결과를 보였다. 기상청 국가기상위성센터의 위성증발산량이 봄과 가을철에 다소 높게 산출되는 경향이 있었으나, 증발산량의 변화경향은 유사하게 나타났다. 이러한 결과를 바탕으로 동아시아 지역 위성 증발산량 변화를 감시하고 있으며 향후, 수문 및 기후 분야에서 가뭄 모니터링 등의 연구에도 활용할 수 있을 것이다.

• Proceedings of the Korea Water Resources Association Conference
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• 2016.05a
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• pp.65-65
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• 2016

Various types of flow conditions are developed in the region just downstream of hydraulic structures such as weir and drop structures. One of distinct flow conditions occurred downstream of drop structures is the wave type flow with undular hydraulic jump formation. We present three-dimensional numerical simulations of a wave type flow formed downstream of a stepped weir which were experimentally investigated by Kang et al. (2010). The turbulent flow over the weir structure is modeling using the unsteady Reynolds-averaged Navier-Stokes (URANS) simulation employing the Spalart-Allmaras one equation model and the detached eddy simulation. Numerical modeling and the performance of turbulence modeling approaches are evaluated by comparing with the experimental measurements in terms of the free surface variation, the shapes and sizes of undular wave, roller near at free surface, recirculation zone near the channel bottom downstream of the structures, and streamwise velocity profiles at selected longitudinal locations.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2011.04a
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• pp.439-444
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• 2011

Doosan Heavy Industries & Construction Co., Ltd. has been recently developing the gas turbine engine using the biogas as fuel. This paper describes the non-reacting and reacting flow analysis of the combustor which is one of the main components in gas turbine engine. Through CFD analysis, investigation has been performed to evaluate the primary factors for aerodynamic design and to predict combustor behaviors during operation with various fuel distribution ratios. The calculation results are compared with rig test data, which reveals that CFD predictions such as pressure loss, air distribution ratio, and recirculation flow are quite reliable. The trend of NO formation was similar with the test, except the low fuel distribution ratio.

• Journal of the Korean Society of Propulsion Engineers
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• v.21 no.1
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• pp.72-83
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• 2017

A thermo-fluid dynamic analysis was performed through the numerical simulation of a missile canister. Calculation was made in a fixed analytical volume and fully evaporated water was used as a coolant. To analyze the interaction among the hot gas, coolant, and mixture flow, Realizable $k-{\varepsilon}$ turbulence and VOF(Volume Of Fluid) model were chosen and parametric study was performed with the change of coolant flow rate. It could be found that the pressure on the canister top nonlinearly increased with the increase of coolant flow rate. Temperature and coolant distribution were closely related to the flow behavior in canister. Temperature on the canister bottom indicated a decrease being proportional to coolant flow rate in early times but after a specific time, the temperature increased with the tendency being reversed. In addition, the early part of temperature showed a fluctuating phenomenon because of the overall circulatory flow of mixture gas.

• Journal of the Korean Society of Propulsion Engineers
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• v.22 no.4
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• pp.44-54
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• 2018

In a spray experiment using a venturi mounted on a lean premixed LPP injector, droplets appear to have non-uniform distributions. To solve this problem, the exit angle of the venturi was changed to form a dump surface on the nozzle neck. The dump surface improved the atomization performance and minimized droplet loss while forming recirculation zone in the venturi exit. In order to solve the non-uniform spray of the injector, the flow characteristics inside the venturi and SMD of the spray are compared. Finally, an optimum venturi shape is selected to minimize the spray loss and improve the spray performance.

• 한국사회정책
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• v.25 no.1
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• pp.231-257
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• 2018

Japan has generally been considered as the developmentalist welfare state. However, Japan has recently been transformed into a social investment state. Although it still has a developmentalist characteristics with its institutional path dependence, the new social and economic challenges derived from the new social risks such as low birth rates and aging population forced Japan to adopt a new welfare state strategy. The paradigm shift in terms of welfare state strategy was launched by the Third Way positioning of the Democratic party government and succeed to the Second Stage of Abenomics under the Third Abe Cabinet. This paper argues that the welfare state paradigm shift towards a social investment state in Japan is not limited to the Japan's Plan for Dynamic Engagement of All Citizens for a virtuous cycle of growth and distribution, but expands its scope to include the work-family balance policies such as labor market activation for women and public caring for children.

• Journal of the Korean Society of Propulsion Engineers
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• v.25 no.2
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• pp.1-11
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• 2021

The cavity inside the combustor increases the mixing efficiency of fuel and air by inducing a oscillation of the flow and the recirculation area with a low speed, and enables continuous combustion by maintaining the flame. In this study, the characteristics of the internal flow by change in the shape parameters of the cavity were analyzed through experiments and two-dimensional computational analysis. It was observed that the flow in the supersonic combustor was greatly influenced by various shape parameters of cavity besides L/D. Even with the same L/D, it was confirmed that the flow type varies depending on the depth of the cavity, either open or closed type, and the aft ramp angle of the cavity and the height of the combustor also affect the flow characteristics. As a result, the change in the shape parameters of the cavity had a great influence on the total pressure loss.

• Journal of the Economic Geographical Society of Korea
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• v.25 no.1
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• pp.1-22
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• 2022

The purpose of this study is to analyze key concepts of Entrepreneurial Ecosystems and to suggest implications for economic geographical studies. The definition and concept of entrepreneurship as well as changes of its research trends were examined. By combining entrepreneurship and geography, Entrepreneurial Ecosystems, which have recently emerged as important concepts and theories, were examined with the focus on the key concepts such as 'actors and factors', 'productive' and 'territory'. It is important that the individual, organizational and institutional components such as entrepreneurs, start-ups, existing companies, institutions and cultural elements are interconnected to build communities through 'entrepreneurial recycling'. Entrepreneurial Ecosystems support to create innovative high-growth start-ups based on entrepreneurial culture in the local region. Despite conceptual limitations, theoretical and empirical analyses should be conducted from economic geographical perspectives in order to reveal the geographical and spatial processes of productive entrepreneurship and to suggest policy implications for region-based start-up ecosystems.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2022.05a
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• pp.355-357
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• 2022

In this paper, as a positioning technology for predicting the movement path of a moving object using a recurrent neural network (RNN) model, which is a deep learning network, in an indoor environment, continuous location information is used to predict the path of a moving vehicle within a local path. We propose a movement path generation technique that can reduce decision errors. In the case of an indoor environment where GPS information is not available, the data set must be continuous and sequential in order to apply the RNN model. However, Wi-Fi radio fingerprint data cannot be used as RNN data because continuity is not guaranteed as characteristic information about a specific location at the time of collection. Therefore, we propose a movement path generation technique for a vehicle moving a local path in an indoor environment by giving the necessary sequential location continuity to the RNN model.

• Korean Association of Arts Management
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• no.56
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• pp.217-242
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• 2020

At a moment in which the entire culture and arts field is in crisis due to the Covid-19 pandemic, the audience development strategies practiced by arts organizations require significant adaptation. In this paper we consider the theater for young audiences, Youngji, produced by the TYA(Theater for Young Audiences) Research Center(TYARC) of the National Theater Company of Korea (NTCK). We examine how an arts organization develops youth audiences and creates a participatory culture when normal non-face-to-face engagement is not possible. We applied an Action Research methodology to our research filed, which allowed us to track continuous change based on the evolving practices and contingencies of one arts sector organization. Using Brown and Novak-Leonard's (2011) audience involvement spectrum, Koste's (1995) concept of creative drama, and Moore's (1993) transactional distance theory, we explored the possibility of active audience development by analyzing the ways in which NTCK's arts education has adapted its approach to audience development. We find that, even in this non-face-to-face era, it is possible to effectively develop youth audiences through a dramatic play that continues from play to drama.