• Transactions of the Korean Society of Mechanical Engineers A
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• v.36 no.12
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• pp.1653-1661
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• 2012

In this study, the pressure drop changes and structural characteristics of a SMART rod bundle under the effect of a coolant were investigated. The turbulence model of the BSL Reynolds stress model was used to model the coolant flow, and a fluid solid interaction simulation was conducted. First, fuel rod vibration analysis was performed to confirm the natural frequency of the fuel rod, which was supported by spacer grid assemblies, and this was compared with experimental results. From the experimental results, the natural frequency was found to be 48 Hz, and the error compared with the simulation results was 2%. The pressure drop at the rod bundle was calculated and compared with the experimental data; it showed an error of 8%, demonstrating the simulation accuracy. In the flow analysis, the flow velocity and secondary flow at different domains were calculated, and vortex generation was also observed. Finally, through the fluid solid interaction analysis, the fuel rod displacements caused by flow-induced vibrations were calculated. Then, calculated displacement PSD at maximum displacement happed point.

• Proceedings of the Korea Society for Industrial Systems Conference
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• 2008.10b
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• pp.575-582
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• 2008

본 논문은 시맨틱 웹 기술이 어떻게 국가 표준(KS) 정보 검색 서비스 내 정보들을 연계시키고 사용자 접근성을 향상시키는 데 도움을 줄 수 있는지를 실증적으로 보여준다. 기존 표준 정보 검색 서비스는 용어 검색의 유연성이 부족하여 표준 정보에서 사용된 용어와 사용자 용어 간의 괴리를 해소하지 못했으며 표준, 기관, 인력 등 상호 관련성을 가진 개체 정보들을 개별적으로 서비스하였다. 이러한 상황은 사용자의 표준 정보 검색 서비스 접근성을 떨어뜨리는 요인으로 작용한다. 본 연구에서는 유의어, 관련어를 중심으로 한 표준 용어 사전 구축을 통해 사용자 용어와 표준 정보 내 용어 간의 원활한 매칭을 지원하며, 표준 관련 개체들을 온톨로지와 추론을 통해 연계시키는 방안을 제시한다. 개선된 표준 정보 검색 서비스는 개선된 표준 정보 검색 서비스는 개체 중심적 통합 검색 결과 제공 방식으로 관련 정보들을 단일 웹 페이지 내에서 확인할 수 있도록 해준다. 예를 들어, 특정 KS 표준 검색 결과 페이지에서는 기존에 DB 접근이나 검색 엔진을 통해 바로 획득할 수 없었던 정부 표준들, 기관들의 해당 KS 표준 인용 현황, 해당 KS 표준 전문가들, 부합화를 위해 참조된 국제 표준들, 해당 KS 표준 전문가들, 부합화를 위해 참조된 국제 표준들, 해당 KS 표준 전문가 네트워크, 해당 KS 표준 내 표준 용어 사전 정보 등 다양한 관련 정보들을 조합하여 서비스한다. 본 연구를 위해 모델링된 온톨로지와 시맨틱 웹기반 서비스 프레임워크인 OntoFrame 상에서 추론 작업이 표준 정보 적재 시에 전방 추론 (Forward-chaining) 방식으로 수행되었으며, 표준 온톨로지 질의 언어인 SPARQL (SPARQL Protocol and RDF Query Language)을 이용해 일반 검색 서비스 수준의 속도로 서비스될 수 있었다.

• Journal of the Korean BIBLIA Society for library and Information Science
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• v.23 no.2
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• pp.5-25
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• 2012

The purpose of this study is to develop linked data of authority data in national archives of Korea as a cornerstone for linked data cloud of Korea. The study analyzed data structure of authority data as well as a retrieval system. It finally developed linked data based on RDF/OWL, Dublin Core, and SKOS. The study also employed TopBraid ComposerTM as a tool for ontology construction. The visualization of the tool provides users with flexible search and browsing between data as well as access of detail authority data. It complements the search of a current system in terms of flexible linking between records and authority data. The study also suggests future work to publish linked data of archival data set itself and make rich relationships among data in museums, libraries, and other archives.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2013.10a
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• pp.805-808
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• 2013

As the development type of domestic technology on information & communications have changed from following development to leading devalopment, developing new technology and creating new market through securing basic technology and IPR has been more essential than ever before. At the same time, it is required to increase the possibility of commercialization on developed technology. Therefore, it is necessary to formulate the consensus on the value and function of project at project planning phase for creative & innovative idea to be adopted into project and to be performed successfully. Accordingly, this paper proposes use case developing methodology adopted to creative & innovative project by analysing use case developing method in software engineering. Also, new methodology is appled to LASA display developing project to prove the reliability. Since the demands on new technology is henceforth expected to increase gradually, it is necessary to continue to study on the methodology of being more formal and logically related between phases as well as on that of analysing relationship among use cases and proving logical reliability of use case.

• Proceedings of the Korea Water Resources Association Conference
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• 2010.05a
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• pp.1079-1083
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• 2010

Due to summer rainfall is concentrated in the construction of the reservoir and the dam was inevitable. The character of these structures are different from the common rivers have been characterized. According to this problem, we need to adopt to this area with three dimensional model. Construction of dams for preservation of land, utilization of water resources, and exploitation of energy potential, which is a basic element of countries' development, is regarded as indispensable for peoples. In addtion, the development of the Nakdong River nutrient and pathogen Total Maximum Daily Loads (TMDL) required that the full range of pollutants, sources, and flow conditions, typical of heavily urbanized areas, be addressed for a single water body with 1-D simulation model (river) and 3-D simulation model (reservoir). The objective of this study is to simulate the applicability of reservoir with the coupling of 3-D hydrodynamic and water quality models to estimate water balance and pollutant loading in Namgang Dam(Jinyang reservoir).

• Journal of Energy Engineering
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• v.24 no.1
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• pp.123-131
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• 2015

This paper aims to identify and clarify the cyber security risks and their interaction with the power system in Smart Grid. The EMS and other communication networks interact with the power system on a real time basis, so it is important to understand the interaction between two layers to protect the power system from potential cyber threats. In this study, the optimal power flow(OPF) and Power Flow Tracing are used to assess the interaction between the EMS and the power system. Through OPF and Power Flow Tracing based analysis, the physical and economic impacts from potential cyber threats are assessed, and thereby the quantitative risks are measured in a monetary unit.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.37 no.2
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• pp.139-146
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• 2009

In this study, an assessment is made for the helicopter vibration reduction of composite rotor blades using an active twist control concept. The piezoceramic shear actuation mechanism along with elastic couplings of composite blades is used for vibration reduction. The rotor blades are modeled as composite box-beams with actuator layers bonded on the outer surfaces of the thin-walled section. The governing equations of motion for helicopter blades are obtained using Hamilton's principle. A time domain unsteady aerodynamic theory with free wake model is used to obtain the airloads. Various rotor configurations with different elastic couplings with appropriate actuator placement are used to investigate the hub vibration characteristics. Numerical results show that a substantial reduction of $N_b$/rev hub vibration can be achieved using the optimal control algorithm.

• Plant Journal
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• v.18 no.1
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• pp.43-49
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• 2022

In this study, the operational characteristics of the 7.48 MW fuel cell power plant consisting of 17 units of 440 kW Phosphoric Acid Fuel Cell (PAFC) in operation since its commercial operation in December 2017 were explained and the heat recovery process of the plat using Organic Rankine Cycle (ORC)was simulated. The fuel cell system performance improvement and economic assessment were analyzed by calculating the amount of heat recovery and electric power available when connecting a 125 kW XLT Model ORC for hot water heat sources with 105℃, 40.8 t/h. The result of the study shows that integrating the 125 kW ORC to PAFC power plant would improve generating efficiency by about 0.6% through annually 851,472 kWh of electricity produced by ORC, and fuel cell and ORC integrated systems were calculated to have a 0.35% higher Internal Return Ratio and more Net Present Value of 1,249 million KRW than not installing ORC despite installation costs.

• Journal of the Korean Geotechnical Society
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• v.38 no.9
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• pp.45-52
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• 2022

Because discontinuity in the rock mass and contact of soil-structure interaction exhibits coupled thermal-hydromechanical (THM) behavior, it is necessary to develop an interface element based on the full governing equations. In this study, we derive force equilibrium, fluid continuity, and energy equilibrium equations for the interface element. Additionally, we present a stiffness matrix of the elastoplastic mechanical model for the interface element. The developed interface element uses six nodes for displacement and four nodes for water pressure and temperature in a two-dimensional analysis. The fully coupled THM analysis for fluid injection into a fault can model the complicated evolution of injection pressure due to decreasing effective stress in the fault and thermal contraction of the surrounding rock mass. However, the result of hydromechanical analysis ignoring thermal phenomena overestimates hydromechanical variables.

• Proceedings of the Korea Water Resources Association Conference
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• 2023.05a
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• pp.281-281
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• 2023

최근 급격한 기후변화와 하천수 사용량의 증가로 수문학적 변동성이 증가하면서 지표수와 지하수의 통합 관리 필요성이 증대되고 있다. 이에 따라 SWAT-MODFLOW 모델은 지표수와 지하수 간의 수문학적 상호작용을 고려한 시공간적 지하수함양량의 분포와 하천과 대수층 간의 물 교환량, 장기 유출 및 수질 거동 해석 등에 널리 사용되고 있다. 그러나 이 모델은 국내 농업 유역 내 담수 논에서의 영농활동을 고려한 시단위 유출 및 수질 예측과 지표수-지하수 통합 해석에 어려움이 있다. 우리나라의 경우 전국 농지 면적 중 논이 약 50%를 차지하고 있음에도 불구하고 아직까지 국내 담수 논 특성을 고려하여 지표수-지하수 통합 해석이 가능한 수문 모델이 개발 된 바 없다. 이에 본 연구에서는 고해상도 시강우량에 따른 담수 논에서의 증발, 침투, 관개, 배수 등 모의가 가능한 Hourly SWAT-PADDY 모듈을 개발하고, SWAT-MODFLOW 모델의 수문 프로세스와의 연계를 통해 지표수-지하수 통합 해석이 가능한 Hourly SWAT-MODFLOW-PADDY 모델을 개발하였다. Hourly SWAT-MODFLOW-PADDY 모델은 사용자가 구축한 담수 논의 입력자료(담수, 관개, 낙수 일정 등)를 기준으로 논의 담수 및 비담수 시기에 따른 시단위 물수지 해석과 이를 고려한 유출량, 수질, 지하수함양량, 하천과 대수층 간의 물 교환량 산정이 가능하다. 본 연구에서 개발 된 Hourly SWAT-MODFLOW-PADDY 모델은 국내 농업 유역에서의 지표수-지하수 통합 관리 대책 수립 방향을 제시하기 위한 도구로 활용될 수 있을 것이다. 또한, 향후 논의 관개 용수 공급원 연계를 통한 모델의 고도화 방안과 최적의 논 영농 데이터베이스가 마련된다면 보다 정량적인 물수지 해석 기반의 지표수-지하수 통합 모델링이 가능할 것으로 보인다.