• 한국가스학회지
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• 제15권6호
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• pp.8-13
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• 2011

유해 위험 요인이 있는 시설물의 안전에 대한 의식을 고취시키기 위해서는 현장 종사자뿐만 아니라 관리자와 경영자도 해당 시설물에 대한 모니터링이 가능해야 한다. 그러나 우리나라에 있는 대부분의 CNG충전소는 로컬 형식의 모니터링 시스템이 사용되고 있으며 이러한 점을 고려하여 웹상에서 운용할 수 있는 충전소 관리 시스템을 개발 하였다. 개발된 시스템은 U-GSMS(Ubiquitous Gas Safety Management System)라고 명명 하였다. U-GSMS는 크게 프로그램 부분과 하드웨어 부분으로 나눌 수 있다. 프로그램 부분은 안전과 운영을 관리 할 수 있는 시스템으로 구성하였으며 하드웨어 부분은 가스시설물에 적용할 수 있는 센서, 센서간의 통신 그리고 센서와 기기 간의 통신을 위하여 USN(Ubiquitous Sensor Network)기술을 적용하여 무선 통신 시스템을 구축하였다. 이 논문에서는 주로 U-GSMS 중 프로그램에 관하여 기술하였다.

• 한국안전학회지
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• 제28권6호
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• pp.49-56
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• 2013

The statistics of recent accidents in warehouses show that a heavy toll of lives were produced by various accidents, e.g. collision, overturn, fall, slip, exposure to harmful substances or environments, etc. Of significant concern amongst them is the collision, especially the collision between forklift and storage rack structure. Accordingly, this study focuses on behavioral characteristics of rack structure subjected to dynamic impact loading of a forklift. For this purpose, time-domain response analysis has been performed on a standard 2-bay six-story rack structure consisting of columns, beams and bracing members with perforated open section. In order to investigate the most critical scenario, the impact loads are applied in both down-aisle and cross-aisle directions, and the impact locations are also varied along the shelves of the palettes. In order to deal with storage distributions, three types of rack structures are further taken into account: original empty rack structure with no storage, half-loaded rack structure and fully-loaded rack structure. The numerical simulation results demonstrate that the dynamic characteristics of the rack structure are significantly dependent on the distribution of the storage goods and its natural period varies from 0.24sec to 1.06sec, approximately 4.4 times. Further, the parametric studies show that the forklift impact is most critical to the safety of the rack structure when it collides either at the base or at the top of the rack structure.

• Journal of Ecology and Environment
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• 제34권2호
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• pp.203-214
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• 2011

The objectives of this research were to predict land-use/land-cover change at the Sakaerat Environmental Research Station (SERS) and to analyze its consequences on the distribution for Black-crested Bulbul (Pycnonotus melanicterus), which is a popular species for bird-watching activity. The Dyna-CLUE model was used to determine land-use allocation between 2008 and 2020 under two scenarios. Trend scenario was a continuation of recent land-use change (2002-2008), while the integrated land-use management scenario aimed to protect 45% of study area under intact forest, rehabilitated forest and reforestation for renewable energy. The maximum entropy model (Maxent), Geographic Information System (GIS) and FRAGSTATS package were used to predict bird occurrence and assess landscape fragmentation indices, respectively. The results revealed that parts of secondary growth, agriculture areas and dry dipterocarp forest close to road networks would be converted to other land use classes, especially eucalyptus plantation. Distance to dry evergreen forest, distance to secondary growth and distance to road were important factors for Black-crested Bulbul distribution because this species prefers to inhabit ecotones between dense forest and open woodland. The predicted for occurrence of Black-crested Bulbul in 2008 covers an area of 3,802 ha and relatively reduces to 3,342 ha in 2020 for trend scenario and to 3,627 ha for integrated-land use management scenario. However, intact habitats would be severely fragmented, which can be noticed by total habitat area, largest patch index and total core area indices, especially under the trend scenario. These consequences are likely to diminish the recreation and education values of the SERS to the public.

• 한국항공우주학회지
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• 제36권9호
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• pp.884-890
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• 2008

본 논문에서는 원형 목표구역에 무인 비행체가 도달할 때 비행체의 지향각, 즉 속도 벡터의 방향과 비행체와 목표점과의 시선이 이루는 사이 각을 제어할 수 있는 일반화된 중기 유도법칙을 제안한다. 유도법칙의 도출을 위해 비행체의 운동을 비선형 미분 방정식으로 모델링하고 거리함수 가중치를 갖는 제어 에너지 최소화 문제로 접근하여 최적제어이론을 적용하였다. 결과적으로 원형 목표구역 도달 시 지향각 구속조건을 만족시킬 수 있는 최적 해를 도출한다. 해의 수렴성을 비롯하여 제안한 유도법칙의 특성에 대해 고찰한다. 수치적인 시뮬 레이션을 통해 전형적인 시나리오에 대해 제안한 유도법칙의 성능을 시범적으로 보인다.

• Asian Journal of Atmospheric Environment
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• 제11권4호
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• pp.330-343
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• 2017

Climate change is an important issue, with many researches examining not only future climatic conditions, but also the interaction of climate and air quality. In this study, a new version of the emissions processing software tool - Python-based PRocessing Operator for Climate and Emission Scenarios (PROCES) - was developed to support climate and atmospheric chemistry modeling studies. PROCES was designed to cover global and regional scale modeling domains, which correspond to GEOS-Chem and CMAQ/CAMx models, respectively. This tool comprises of one main system and two units of external software. One of the external software units for this processing system was developed using the GIS commercial program, which was used to create spatial allocation profiles as an auxiliary database. The SMOKE-Asia emissions modeling system was linked to the main system as an external software, to create model-ready emissions for regional scale air quality modeling. The main system was coded in Python version 2.7, which includes several functions allowing general emissions processing steps, such as emissions interpolation, spatial allocation and chemical speciation, to create model-ready emissions and auxiliary inputs of SMOKE-Asia, as well as user-friendly functions related to emissions analysis, such as verification and visualization. Due to its flexible software architecture, PROCES can be applied to any pregridded emission data, as well as regional inventories. The application results of our new tool for global and regional (East Asia) scale modeling domain under RCP scenario for the years 1995-2006, 2015-2025, and 2040-2055 was quantitatively in good agreement with the reference data of RCPs.

• Smart Structures and Systems
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• 제25권5호
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• pp.605-617
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• 2020

The existence of damages in structures causes changes in the physical properties by reducing the modal parameters. In this paper, we develop a two-stages approach based on normalized Modal Strain Energy Damage Indicator (nMSEDI) for quick applications to predict the location of damage. A two-dimensional IsoGeometric Analysis (2D-IGA), Machine Learning Algorithm (MLA) and optimization techniques are combined to create a new tool. In the first stage, we introduce a modified damage identification technique based on frequencies using nMSEDI to locate the potential of damaged elements. In the second stage, after eliminating the healthy elements, the damage index values from nMSEDI are considered as input in the damage quantification algorithm. The hybrid of Teaching-Learning-Based Optimization (TLBO) with Artificial Neural Network (ANN) and Particle Swarm Optimization (PSO) are used along with nMSEDI. The objective of TLBO is to estimate the parameters of PSO-ANN to find a good training based on actual damage and estimated damage. The IGA model is updated using experimental results based on stiffness and mass matrix using the difference between calculated and measured frequencies as objective function. The feasibility and efficiency of nMSEDI-PSO-ANN after finding the best parameters by TLBO are demonstrated through the comparison with nMSEDI-IGA for different scenarios. The result of the analyses indicates that the proposed approach can be used to determine correctly the severity of damage in beam structures.

• 터널과지하공간
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• 제27권2호
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• pp.89-99
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• 2017

이산화탄소 지중저장 사업의 성공적인 수행을 위해서는 저장시스템의 안정성을 확보할 수 있는 대상 지층을 선정하고 현장 지질조건에 최적화된 주입 조건을 설계해야 한다. 본 연구에서는 국내 실증실험 대상 예상후보지의 하나인 장기분지의 지질구조를 바탕으로 2차원 간략해석모델을 구축하고 TOUGH-FLAC 연계해석기법을 사용하여 초기응력조건과 주입량이 이산화탄소 격리저장시스템에 미치는 영향을 분석하였다. 기초해석 결과, 수직응력이 수평응력보다 우세한 정단층 응력조건에서 전단미끄러짐 가능성이 가장 높은 결과를 보였으며, 단위시간당 주입량을 달리하는 주입량 시나리오 해석에서는 주입량을 단계적으로 증가시켜 주입하는 경우가 공극압의 증가폭이 가장 크고 활동마찰계수를 이용한 전단미끄러짐 가능성 평가 결과에서도 가장 불리한 것으로 평가되었다.

• 전기학회논문지
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• 제65권6호
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• pp.962-968
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• 2016

The large scaled lead-acid battery is widely used for efficient operation of the photovoltaic system in many islands. However, lithium-ion battery is now being introduced to mitigate the fluctuation of wind power and to replace lead-acid battery. Therefore, hybrid ESS(Energy Storage system) that combines lithium-ion battery with lead-acid battery is being required because lithium-ion battery is costly in present stage. Under this circumstance, this paper presents the optimal algorithm to create composition rate of hybrid ESS by considering fixed and variable costs in order to maximize advantage of each battery. With minimization of total cost including fixed and variable costs, the optimal composition rate can be calculated based on the various scenarios such as load variation, life cycle and cost trend. From simulation results, it is confirmed that the proposed algorithms are an effective tool to produce a optimal composition rate.

• Earthquakes and Structures
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• 제11권6호
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• pp.1001-1025
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• 2016

Building structures generally have inherent low damping capability and hence are vulnerable to seismic excitations. Control devices therefore play a useful role in providing safety to building structures subject to seismic events. In recent years semi-active dampers have gained considerable attention as structural control devices in the building construction industry. Magneto-rheological (MR) damper, a type of semi-active damper has proven to be effective in seismic mitigation of building structures. MR dampers contain a controllable MR fluid whose rheological properties vary rapidly with the applied magnetic field. Although some research has been carried out on the use of MR dampers in building structures, optimal design of MR damper and combined use of MR and passive dampers for real scale buildings has hardly been investigated. This paper investigates the use of MR dampers and incorporating MR-passive damper combinations in building structures in order to achieve acceptable levels of seismic performance. In order to do so, it first develops the MR damper model by integrating control algorithms commonly used in MR damper modelling. The developed MR damper is then integrated in to the seismically excited structure as a time domain function. Linear and nonlinear structure models are evaluated in real time scenarios. Analyses are conducted to investigate the influence of location and number of devices on the seismic performance of the building structure. The findings of this paper provide information towards the design and construction of earthquake safe buildings with optimally employed MR dampers and MR-passive damper combinations.

• 한국철도학회논문집
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• 제11권3호
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• pp.300-310
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• 2008

본 논문에서는 국내철도차량안전기준의 충돌안전 요구사항을 만족하는 동력 분산형 고속전철의 충돌안전도 개념설계에 대하여 연구하였다. 국내안전기준에는 36km/h 열차 대 열차 충돌, 15ton 변형체 장애물과 110km/h 충돌 등 2가지 중충돌 사고에 대한 충돌안전성능을 요구한다. 한국형 분산형 차세대고속열차는 17ton 축중의 동력집중형 KTX와 달리 13ton 축중을 가지는 2TC-6M로 구성된다. 이론적 수치적 해석을 통하여 주요 압괴구조 및 부품의 평균압괴하중과 변형량을 에너지 흡수 관점에서 충돌안전도 개념설계안으로 도출하였다. 도출된 개념 설계안은 1차원 막대-스프링-댐퍼-질량 동역학 시뮬레이션 결과로부터 국내 충돌안전기준을 잘 만족시킬 수 있음을 보였다.