• Title/Summary/Keyword: Concept net

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Development and Application of Water Balance Network Model in Agricultural Watershed (농업용수 유역 물수지 분석 모델 개발 및 적용)

  • Yoon, Dong-Hyun;Nam, Won-Ho;Koh, Bo-Sung;Kim, Kyung-Mo;Jo, Young-Jun;Park, Jin-Hyeon
    • Journal of The Korean Society of Agricultural Engineers
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    • v.66 no.3
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    • pp.39-51
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    • 2024
  • To effectively implement the integrated water management policy outlined in the National Water Management Act, it is essential to analyze agricultural water supply and demand at both basin and water district levels. Currently, agricultural water is primarily distributed through open canal systems and controlled by floodgates, yet the utilization-to-supply ratio remains at a mere 48%. In the case of agricultural water, when analyzing water balance through existing national basin water resource models (K-WEAP, K-MODISM), distortion of supply and regression occurs due to calculation of regression rate based on the concept of net water consumption. In addition, by simplifying the complex and diverse agricultural water supply system within the basin into a single virtual reservoir, it is difficult to analyze the surplus or shortage of agricultural water for each field within the basin. There are limitations in reflecting the characteristics and actual sites of rural water areas, such as inconsistencies with river and reservoir supply priority sites. This study focuses on the development of a model aimed at improving the deficiencies of current water balance analysis methods. The developed model aims to provide standardized water balance analysis nationwide, with initial application to the Anseo standard watershed. Utilizing data from 32 facilities within the standard watershed, the study conducted water balance analysis through watershed linkage, highlighting differences and improvements compared to existing methods.

Conceptual design and analysis of remote steering system for CFETR ECRH system

  • Chao Zhang;Xiaojie Wang;Dajun Wu;Yunying Tang;Hanlin Wang;Dingzhen Li;Fukun Liu;Muquan Wu;Peiguang Yan;Xiang Gao;Jiangang Li
    • Nuclear Engineering and Technology
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    • v.56 no.2
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    • pp.451-462
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    • 2024
  • In order to optimize the operational safety and reliability of the upper launcher for the CFETR ECRH system, a design of the launcher based on the remote steering concept is currently being carried out for comparison with the front steering equivalent. This paper presents the remote steering system's conceptual design and simulation analysis. A Square Corrugated Waveguide (SCW) of 65 × 65 mm has been designed with an optimized length of 9.35 m. By changing the relative length of the waveguide, the transmission efficiency of the SCW is optimized within the range of steering angles ±12°. Different error factors are investigated in detail, and corresponding acceptable error ranges are provided. Considering these error factors and ignoring ohmic losses and thermal effects, the relative transmission efficiency of the SCW is estimated to be >98 % within the steering angle range. A matching steering unit for the SCW is designed, which consists of an ellipsoidal focusing mirror and a steerable flat mirror. The detailed design of the steerable mirror motion trajectory is presented. Also, the influence of the possible beam incident errors caused by the steering unit on the transmission efficiency is analyzed in detail.

A Study on Port's Decarbonization Strategies : focusing on its Barriers and Solutions (항만의 탈탄소 전환에 관한 연구: 장애요인과 해결방안을 중심으로)

  • Han, Chul-Hwan
    • Journal of Korea Port Economic Association
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    • v.40 no.2
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    • pp.137-155
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    • 2024
  • To achieve the national goal of "2050 Carbon Neutrality" in the era of the climate crisis, it is important to support the decarbonization of ports, which are the vital node of the global supply chain. Following the establishment of the concept of port's decarbonzation, this study reviewed the obstacles and solutions to port decarbonization through literature research. Furthermore, the goals and strategies for decarbonization implementation of world major ports were examined through case analysis, and the level of decarbonization implementation of the five Korean major ports was quantitatively evaluated using a performance-based score measurement method. As a result of the analysis, the level of decarbonization of Korean ports is generally far behind that of advanced countries. In particular, measures for environment-friendly inland transportation, future alternative fuel bunkering facilities, and various market-based incentive policies are needed. As a policy task for the decarbonization of Korean ports, first, the necessity of establishing a emission inventory, monitoring, and reporting system and the disclosure of related information, second, the mixing strategy of various greenhouse gas reduction measures, and third, the increase in the proportion of renewable energy at ports were suggested.

Study on load tracking characteristics of closed Brayton conversion liquid metal cooled space nuclear power system

  • Li Ge;Huaqi Li;Jianqiang Shan
    • Nuclear Engineering and Technology
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    • v.56 no.5
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    • pp.1584-1602
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    • 2024
  • It is vital to output the required electrical power following various task requirements when the space reactor power supply is operating in orbit. The dynamic performance of the closed Brayton cycle thermoelectric conversion system is initially studied and analyzed. Based on this, a load tracking power regulation method is developed for the liquid metal cooled space reactor power system, which takes into account the inlet temperature of the lithium on the hot side of the intermediate heat exchanger, the filling quantity of helium and xenon, and the input amount of the heat pipe radiator module. After comparing several methods, a power regulation method with fast response speed and strong system stability is obtained. Under various changes in power output, the dynamic response characteristics of the ultra-small liquid metal lithium-cooled space reactor concept scheme are analyzed. The transient operation process of 70 % load power shows that core power variation is within 30 % and core coolant temperature can operate at the set safety temperature. The second loop's helium-xenon working fluid has a 65K temperature change range and a 25 % filling quantity. The lithium at the radiator loop outlet changes by less than ±7 K, and the system's main key parameters change as expected, indicating safety. The core system uses less power during 30 % load power transient operation. According to the response characteristics of various system parameters, under low power operation conditions, the lithium working fluid temperature of the radiator circuit and the high-temperature heat pipe operation temperature are limiting conditions for low-power operation, and multiple system parameters must be coordinated to ensure that the radiator system does not condense the lithium working fluid and the heat pipe.

Quasi-optical design and analysis of a remote steering launcher for CFETR ECRH system

  • Zhang Chao;Xiaojie Wang;Dajun Wu;Yunying Tang;Hanlin Wang;Dingzhen Li;Fukun Liu;Muquan Wu;Peiguang Yan;Xiang Gao;Jiangang Li
    • Nuclear Engineering and Technology
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    • v.56 no.5
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    • pp.1619-1626
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    • 2024
  • In order to optimize the operational safety and reliability of the upper launcher for the CFETR ECRH system, a design of the launcher for NTM control based on the remote steering concept is currently being carried out for comparison with the front steering equivalent. This paper presents the layout design and analysis of the quasi-optical system in the remote steering launcher. A 3D visual quasi-optical design tool has been developed for the quasi-optical system, which can parameterize modeling, perform general astigmatic beam calculation and show the accurate beam propagation path in the upper port. Three identical sets of quasi-optical modules are arranged in the launcher, and each one consists of two fixed double-curvature focusing mirrors, which focus and reflect the steering beams (- 12°-12°) from two square corrugated waveguides. The beam characteristics at the resonance layer are described, and the average beam radius is < 100 mm. The peak head loads on the surfaces of the two fixed mirrors are 1.63 MW/m2 and 1.52 MW/m2. The position and size of the beam channel in the blanket are obtained, and the opening apertures on the launcher-facing and plasma-facing sides of the blanket module are 0.54 m2 and 0.4 m2, respectively.

Coupled 3D thermal-hydraulic code development for performance assessment of spent nuclear fuel disposal system

  • Samuel Park;Nakkyu Chae;Pilhyeon Ju;Seungjin Seo;Richard I. Foster;Sungyeol Choi
    • Nuclear Engineering and Technology
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    • v.56 no.9
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    • pp.3950-3960
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    • 2024
  • As a solution to the problem of spent nuclear fuels (SNFs), the disposal of SNF has gained attention from nations using nuclear energy because of hazards posed to the ecosystem. Among many proposed solutions, the most promising method is to dispose of SNF in a deep geological repository (DGR) which utilizes the multi-barrier concept developed by Finland and Sweden. Here, a new fully-coupled Thermal-Hydraulic (TH) code HADES (High-level rAdionuclide Disposal Evaluation Simulator) is developed using the MOOSE framework. This new code suggests basic numerical tools, such as a non-linear solver and finite element discretization, to assess the safety performance of disposal systems. The new TH code considered various TH behavior using Richards' flow approach, assuming gas pressure is constant. The HADES showed promising results when it was compared to various TH codes validated from DECOVAELX-THMC projects. When the single-canister model was utilized to estimate the TH behavior of the Korean Reference disposal System, although it showed significant saturation reduction due to the evaporation of water, the temperature was maintained under the thermal criteria limit, which is 100 ℃. In addition, the new code estimated temperature and degree of saturation of the multi-canisters model, considering two or three canisters, it showed a slightly lower temperature, 5 ℃, than the single-canister model. From these results, the following are concluded: (1) the new TH code contribute to an additional integrity by estimating TH behavior of KRS; (2) however, due to limitations in single-canister simulation, it is recommended to use multi-canisters simulation to estimate TH behavior accurately. Therefore, this model is anticipated not only to help licensing applications and estimation of various multi-physics phenomena and multi-canister at the disposal site.

A comprehensive examination of the linear and numerical stability aspects of the bubble collision model in the TRACE-1D two-fluid model applied to vertical disperse flow in a PWR core channel under loss of coolant accident conditions

  • Satya Prakash Saraswat;Yacine Addad
    • Nuclear Engineering and Technology
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    • v.56 no.8
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    • pp.2974-2989
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    • 2024
  • The one-dimensional Two-Fluid concept uses an area-average approach to simplify the time and phase-averaged Two-Fluid conservation equations, making it more suitable for addressing difficulties at an industrial scale. Nevertheless, the mathematical framework has inherent weaknesses due to the loss of details throughout the averaging procedures. This limitation makes the conventional model inappropriate for some flow regimes, where short-wavelength perturbations experience uncontrolled amplification, leading to solutions that need to be physically accurate. The critical factor in resolving this problem is the integration of closure relations. These relationships play a crucial function in reintroducing essential physical characteristics, thus correcting the loss that occurs during averaging and guaranteeing the stability of the model. To improve the accuracy of predictions, it is essential to assess the stability and grid dependence of one-dimensional formulations, which are particularly affected by closure relations and numerical schemes. The current research presented in the text focuses on improving the well-posedness of the TFM, specifically within the TRACE code, which is widely utilized for nuclear reactor safety assessments. Incorporating a bubble collision model in the momentum equations is demonstrated to enhance the TFM's resilience, especially in scenarios with high void fractions where conventional TFMs may face challenges. The analysis presents a linear stability analysis performed for the transient one-dimensional Two-Fluid Model of system code TRACE within the framework of vertically dispersed flows. The main emphasis is on evaluating the stability characteristics of the model while also acknowledging its susceptibility to closure relations and numerical techniques.

XSLT Stylesheet Design for Building Web Presentation Layer (웹 프리젠테이션 레이어 생성을 위한 XSLT 스타일쉬트 설계)

  • 채정화;유철중;장옥배
    • Journal of KIISE:Software and Applications
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    • v.31 no.3
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    • pp.255-266
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    • 2004
  • In the Web-based information systems, separating the business process logic from the data and presentation logic brings about a wide range of advantages. However, this separation is not easily achieved; even the data logic may be not separated from the presentation layer. So, it requires to define an model for business processes, and then to map the model into the user's dynamic interface using the logic separating strategy. This paper presents a stylesheet method to recognize the process by extending XSLT (Extensible Stylesheet Language Transformations), in order to achieve the logic separation. To do this, it provides an specification of the business process, and a scheme that extracts business model factors and their interactions using a Petri-net notation to show the business model into the process point of view. This is an attempt to separate users' interaction from the business process, that is, dynamic components of interaction Web document from the process structure of Web applications. Our architecture consist mainly of an XSLT controller that is extended by a process control component. The XSLT controller is responsible for receiving the user requests and searching the relevant templet rule related to different user requests one by one. Separation of concerns facilities the development of service-oriented Web sites by making if modular. As a result, the development of service-oriented Web sites would be very easy, and can be changed without affecting the other modules, by virtue of the modularization concept. So, it is easy to develop and maintain the Web applications in independent manner.

A Colored Workflow Model for Business Process Analysis (비즈니스 프로세스 분석을 위한 색채형 워크플로우 모델)

  • Jeong, Woo-Jin;Kim, Kwang-Hoon
    • Journal of Internet Computing and Services
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    • v.10 no.3
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    • pp.113-129
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    • 2009
  • Abstract Corporate activities are composed of numerous working processes and during the working flow, various business processes are being created and completed simultaneously. Enterprise Resources Planning (ERP) makes the working process simple, yet creates more complicated work structure and therefore, there is an absolute need of efficient management for business processes. The workflow literature has been looking for efficient and effective ways of rediscovering and mining workflow intelligence and knowledge from their enactment histories and event logs. As part of studies to analyze and improve the process, the concepts of 'Process Mining', 'Process re-discovery', 'BPR (Business Process Reengineering)' have appeared and the studies for practical implementation are proactively being done. However, these studies normally follow the approach throughout data warehousing for log data of process instances. It is very hard for these approaches to reflect user's intention to the rediscovering and mining activities. The process instances designed based on the consideration of analysis can make groupings effectively and when the analysis demand of user changes within the analysis domain can also reduce the cost of analysis. Therefore, the thesis proposes a special type of workflow model, which is called a colored workflow model, that is extended from the ICN (information control net) modeling methodology by reinforcing the concept of colored token. The colored tokens represent the conceptual types of constraints and criteria that can be used to classifying and grouping the workflow intelligence and knowledge extracted from the corresponding workflow models' enactment histories and event logs. Through the runtime information of process instances, it makes possible to analyze proactive and user-oriented process with the goal of deriving business knowledge from the beginning of process definition.

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Evaluation of Virtual Water Calculation Method in Korea (우리나라 가상수량 산정방법의 적용성 평가)

  • Ahn, Jae-Hyun;Lee, Jae-Geun;Lee, Seung-Ho;Hong, Il-Pyo
    • Journal of Korea Water Resources Association
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    • v.43 no.6
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    • pp.583-595
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    • 2010
  • Virtual water is defined as the volume of water to produce commodities and provide services, which has been developed by Tony Allan since the early 1990s. This research aims to evaluate a volume of virtual water trade in Korea from 1998 to 2007 by applying the evaluation method of unit virtual water volume to agricultural, live stock and industrial products, which is developed by Chapagain and Hoekstra (2004). Also, the concept of water footprint is deployed to quantify the volume of virtual water trade between countries. The study attempts to assess the appropriateness of the evaluation method of unit virtual water volume by employing the method to calculate the total amount of agricultural products in Korea and comparing this with the amount of agricultural water demand in the Korea Water Vision 2006. The research outcome shows that Korea has a net virtual water import of 32 billion $m^3$ on average in the form of agricultural, live stock and industrial commodities whose volume gradually increases. The gap between the volume of virtual water import of agricultural and live stock commodities and the total volume of agricultural water use reaches approximately 600 million $m^3$. This figure can be negligible considering the total volume of water demand in Korea, around 16 billion $m^3$, which demonstrates the validity of the evaluation method in terms of analyzing water balance.