• 한국압력기기공학회 논문집
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• 제13권2호
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• pp.1-18
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• 2017

세계적으로 원자력발전소의 안정적 운영 및 안전성 확보를 위해 수명기간 중 주요 기기 및 배관의 실제 운전 과도상태를 체계적으로 관리하고, 피로 손상의 정량적 평가 및 관리를 위한 체계적인 시스템이 요구되고 있는 실정이다. 이에 본 논문에서는 원자력발전소의 안전등급 1 설비에 대한 피로 평가요건을 분석하였고, 피로 감시방법 및 절차와 웹 기반으로 개발된 피로 감시 시스템인 NuFMS 개발 및 검증 내용을 기술하였다. NuFMS는 설계 시 고려한 과도상태 발생 횟수 대 비발전소의 특정 운전 시점에서의 실제 발생 횟수를 비교하여 안전 여유도의 정량적 확인이 가능하며, 누적피로사용계수 도출을 통해 정확한 피로영향 분석뿐만 아니라 손상 관리가 가능하다. 이와 같이 NuFMS의 적용을 통해 원자력발전소 기기 및 배관의 피로 건전성을 확인하고 운영 신뢰도를 향상시킬 수 있으며, 발전소의 안전성 유지 및 운영비용 절감 등의 효과를 기대할 수 있다. 따라서 향후 국내 전 원전에 NuFMS를 확대 적용할 예정이며, 이러한 기술의 해외 수출을 적극 추진 중이다.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2011년도 춘계학술대회 논문집
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• pp.167-172
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• 2011

Generally, the analysis of railroad wear data is most effective method for the efficient railway maintenance. The wear of railway track affects loss of rough ride, noise or vibration of train and traveling safety. Moreover as the track is worn away, this promotes destruction of structural mechanism of rail track which can bring about increasing of rail track maintenance cost drastically. For this reason, it is very important and interested research subject to design railway track structure and to analyse train movement mechanism based on systematic analysis of the reasons causing rail wear possible in real field. In this research, for the efficient maintenance, Life Cycle Performance of rail track and maintenance characteristics are computed considering some track components such as track type, contracting type, sleeper type and roadbed type. Time - Wear probabilistic distribution relationship as well as multiple regression analysis based on time, curvature and wear data are computed to predict the service life remainder of railway track and to be adapted to safety assessment.

• 한국물환경학회지
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• 제26권2호
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• pp.243-251
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• 2010

Evapotranspiration and rainfall-runoff are the major components of hydrological cycle and thereby the changes of them can directly affect the wetness/dryness or runoff characteristics of basins. In this study the wetness/dryness in Geum river basin are classified by dint of cumulative probability density function of monthly moisture index and the long term changes of them are analyzed based on climatic water balance concept. The drought events in Geum river basin are selected through evaluation of monthly moisture index and the various hydrological properties of them are investigated in detail. Also the trends of time-series of climatic water balance components are examined by Seasonal Kendall test and the variability of hydrological cycle in Geum river basin during the recent decade is inquired. It is judged that the results of this study can be contributed to establishment of the counter plan against the future drought events as the fundamental information.

• 대한전기학회논문지:시스템및제어부문D
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• 제50권1호
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• pp.45-50
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• 2001

With increasing complexity of digital logic circuits, fast and accurate verification of functional behaviour becomes most critical bottleneck in meeting time-to-market requirement. This paper presents several techniques for accelerating a cycle-based logic simulation. The acceleration techniques include parallel pattern logic evaluation, circuit size reduction, and the partition of feedback loops in sequential circuits. Among all, the circuit size reduction plays a critical role in maximizing logic simulation speedup by reducing 50% of entire circuit nodes on the average. These techniques are incorporated into a levelized table-driven logic simulation system rather than a compiled-code simulation algorithm. Finally, experimental results are given to demonstrate the effectiveness of the proposed acceleration techniques. Experimental results show more than 27 times performance improvement over single pattern levelized logic simulation.

• 한국수자원학회:학술대회논문집
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• 한국수자원학회 2023년도 학술발표회
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• pp.183-183
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• 2023

Smart water cities (SWC) are urban municipalities that utilizes modern innovations in managing and preserving the urban water cycle in the city; with the purpose of securing sustainability and improving the quality of life of the urban population. Understanding the different urban water characteristics and management strategies of cities situate a baseline in the development of evaluation scheme in determining whether the city is smart and sustainable. This research herein aims to develop measurements and evaluation for SWC Key Performance Indicators (KPIs), and set up a unified global standard and certification scheme. The assessment for SWC is performed in technical, as well as governance and prospective aspects. KPI measurements under Technical Pillar assess the cities' use of technologies in providing sufficient water supply, monitoring water quality, strengthening disaster resilience, minimizing hazard vulnerability, and maintaining and protecting the urban water ecosystem. Governance and Prospective Pillar on the other hand, evaluates the social, economic and administrative systems set in place to manage the water resources, delivering water services to different levels of society. The performance assessment is composed of a variety of procedures performed in a quantitative and qualitative manner, such as computations through established equations, interviews with authorities in charge, field survey inspections, etc. The developed SWC KPI measurements are used to evaluate the urban water management practices for Busan Eco Delta city, a Semulmeori waterfront area in Gangseo district, Busan. The evaluation and scoring process was presented and established, serving as the basis for the application of the smart water city certification all over the world. The established guideline will be used to analyze future cities, providing integrated and comprehensive information on the status of their urban water cycle, gathering new techniques and proposing solutions for smarter measures.

• 한국연소학회지
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• 제15권2호
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• pp.1-11
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• 2010

Power generation systems based on the oxy-coal combustion with carbon dioxide capture and storage (CCS) capability are being proposed and discussed lately. Although a large number of lab scale studies for oxy-coal power plant have been made, studies of pilot scale or commercial scale power plant are not enough. Only a few demonstration projects for oxy-coal power plant are publicized recently. The proposed systems are evolving and various alternatives are to be comparatively evaluated. This paper presents a proposed approach for performance evaluation of a commercial 100 MWe class power plant, which is currently being considered for 'retrofitting' for the demonstration of the concept. The system is configurated based on design and operating conditions with proper assumptions. System components to be included in the discussion are listed. Evaluation criteria in terms of performance are summarized based on the system heat and mass balance and simple performance parameters, such as the fuel to power efficiency and brief introduction of the second law analysis. Also, gas composition is identified for additional analysis to impurities in the system including the purity of oxygen and unwanted gaseous components of nitrogen, argon and oxygen in air separation unit and $CO_2$ processing unit.

• 콘크리트학회논문집
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• 제21권3호
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• pp.359-366
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• 2009

본 논문은 해양 RC 구조물의 새로운 생애주기비용 (LCC) 평가 모델을 제시한다. 이 모델 방법은, 기존의 LCC 평가 모델과 달리, 구조물을 설계하는 동안 추가적인 염화물 침투의 새로운 데이터가 있을 때 계속적으로 생애주기비용을 업데이트 할 수 있다. 이는 베이지안 기법을 통하여 이루어진다. 일반적인 중요 구조물에서는 각 부재에 대한 다양한 모니터링 시스템을 이용하기 때문에 어려움 없이 베이지안 기법에 필요한 데이터를 얻을 수 있다. 베이지안 기법을 사용하여 구조물의 생애유지 관리비용을 높은 정밀도로 예측할 수 있다.

• 한국지진공학회논문집
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• 제9권2호통권42호
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• pp.17-27
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• 2005

점탄성감쇠기가 설치된 구조물의 통합최적설계기법 및 비용효율성 평가기법을 제시하였다. 구조부재와 점탄성감쇠기의 사용량을 설계변수로 하여, 생애주기비용을 최소화하도록 최적화문제를 정식화하였으며, 유전자알고리즘을 적용하여 최적의 설계변수를 검색하였다. 수치예제에 대한 통합최적설계 수행 결과를 통해 지반운동 특성에 따른 점탄성감쇠기의 최적배치 및 각 층 강성의 최적분포 경향을 분석하였으며, 점탄성감쇠기가 설치되지 않은 구조시스템과의 생애주기비용 비교를 통하여 비용효율성을 평가하였다. 점탄성감쇠기는 특히 중약진지역에서 높은 비용효율성을 보이는 것으로 나타났다.

• 대한기계학회논문집A
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• 제21권2호
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• pp.199-208
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• 1997

A local strain approach was applied to an external single and double grooved C-shaped specimen in order to evaluate and predict the fatigue crack initiation life by using low cycle fatigue properties. The low cycle fatigue properties were determined from the strain-controlled fatigue tests using smooth cylindrical axial specimens. Fatigue crack initiation life was evaluated by a life prediction software, FALIPS, based on the local strain approach. The fatigue life was significantly influenced by the mean stress, and SWT parameter represented the fatigue life effectively. The predicted fatigue crack initiation life was then compared to the experimental fatigue life evaluated from the C-shaped fatigue test specimens. A good correlation was found between the experimental and predicted fatigue lives within factors of 2 and 4 for the single and double grooved C-shaped specimens respectively. Also, experimental fatigue life of the double grooved specimen was 10-12 times longer than that of the single grooved specimen.

• 한국지하수토양환경학회지:지하수토양환경
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• 제27권5호
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• pp.18-31
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• 2022

To evaluate the impact of drought on agriculture in N. Korea, SPI (standardized precipitation index) analysis was carried out by utilizing time-series precipitation data during 1996 - 2003 when severe drought occurred throughout the country. The SPI value was estimated to reach 12 in approximately 60% of the total period, indicating that agricultural productivity deteriorated rapidly due to the long-term drought. The national average drought cycle, based on SPI 12, was estimated as 32.5 months for the last 40 years. However, when examined on 20-year basis, the drought cycle was shortened by 10.6 months in last 20 years (30.3 months) as compared to previous 20 years (40.9 months). Annual crop production continued to increase mainly in rice and maize until the mid-1990s, but declined sharply thereafter due to the drought. After the drought period, the production of potatoes of which growth is more resistant to drought started to increase to the production level comparable to those of rice and soybean. It is expected that changes in the agricultural production environment in N. Korea will be inevitable due to the climate change. To this end, using the results of the drought cycle analysis, it is possible to analyze the changes in the agricultural production environment in N. Korea in the future.