• 한국방재학회 논문집
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• 제4권2호
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• pp.61-69
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• 2004

가뭄은 주요 자연 재해 중의 하나이다. 가뭄 파악을 위하여 주로 강우량과 같은 기상자료를 주요 입력 자료로 활용하여 분석하고 있으나, 이러한 기상 자료는 한정된 기상 관측소로부터 얻어진 점자료에 해당된다. 따라서, 위성을 이용한 원격탐사 자료를 기상자료에서 포착할 수 없는 문제점을 보완하기 위한 자료로 활용할 수 있다는 확신 하에 본 연구를 진행하게 되었다. 본 연구에서는 NOAA 위성에 탑재되어 있는 AVHRR 센서로부터 얻어지는 자료를 이용하여 가뭄파악을 위한 분석을 실시하였다. NOAA/AVHRR로부터 얻어진 식생지수(NDVI)와 이로부터 얻을 수 있는 식생상태지수(VCI)를 이용하여 가뭄분석을 실시하였으며, 또한 광역적인 가뭄분석을 위해 위성자료를 이용하여 기후학적 물수지에 근거하는 간편한 방법을 제안하고 있다. 본 연구를 통하여 가뭄에 대한 시간적, 공간적 특성을 파악하는데 위성자료가 유용하게 이용될 수 있음을 알 수 있었으며, 습윤지표를 통하여 가뭄 지역도 작성이 가능함을 보여주고 있다.

• 한국수자원학회논문집
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• 제36권5호
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• pp.839-849
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• 2003

가뭄은 주요 자연 재해 중의 하나이다. 가뭄 파악을 위하여 주로 강우량과 같은 기상자료를 주요 입력 자료로 활용하여 분석하고 있으나 이러한 기상 자료는 한정된 기상 관측소로부터 얻어진 점자료에 해당된다. 따라서, 기상자료를 이용한 분석에서는 시간적 혹은 공간적으로 원하는 자료의 제공이 원활하게 이루어지지 않을 수 있다. 원격탐사 자료는 가뭄분석을 위하여 기상자료에서 포착할 수 없는 이러한 문제점을 보완하기 위한 자료로 활용될 수 있다. 따라서, 본 연구에서는NOAA 위성에 탑재되어 있는 AVHRR 센서로부터 얻어지는 자료를 이용하여 가뭄 파악을 위한 분석을 실시하였다. 특히 본 연구에서는 NOAA/AVHRR로부터 얻어진 식생지수(NDVI)와 이로부터 얻을 수 있는 식생상태지수(VCI)를 이용하여 가뭄 분석을 실시하였으며, 이들 지수는 가뭄으로부터 기인된 식생 스트레스를 파악하는데 유용하게 이용될 수 있음을 알 수 있었다. 본 연구를 통하여 가뭄에 대한 시간적, 공간적 특성을 파악하는데 위성자료가 유용하게 이용될 수 있음을 알 수 있었으며, VCI를 통하여 가뭄 지역도 작성이 가능함을 보여주고 있다.

• Journal of Advanced Marine Engineering and Technology
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• 제38권2호
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• pp.123-132
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• 2014

The maritime sector is advancing with dedicated endeavor to reduce greenhouse gas in addressing issues with regards to global warming. Since 01 January 2013, the International Maritime Organization (IMO) regulation mandatory requirement for Energy Efficiency Design Index (EEDI) has been in place and should be satisfied by newly-built ships of more than 400 gross tonnage and the Ship Energy Efficiency Management Plan (SEEMP) for all ships type. Therefore, compliance to this necessitates planning during the design stage whereas verification can be carried-out through an acceptable method during sea trial. The MEPC-approved 2013 guidance, ISO 15016 and ISO 19019 on EEDI serves the purpose for calculation and verification of attained EEDI value. Individual ships EEDI value should be lower than the required value set by these regulations. The key factors for EEDI verification are power and speed assessment and their synchronization. The shaft power can be measured by telemeter system using strain gage during sea trial. However, calibration of shaft power onboard condition is complicated. Hence, it relies only on proficient technology that operates within the permitted ISO allowance. On the other hand, the ship speed can be measured and calibrated by differential ground positioning system (DGPS). An actual test on a newly-built vessel was carried out to assess the correlation of power and speed. The Energy-efficiency Design Index or Operational Indicator Monitoring System (EDiMS) software developed by the Dynamics Laboratory-Mokpo Maritime University (DL-MMU) and Green Marine Equipment RIS Center (GMERC) of Mokpo Maritime University was utilized for this investigation. In addition, the software can continuously monitor air emission and is a useful tool for inventory and ship energy management plan. This paper introduces the synchronization and identification method between shaft power and ship speed for EEDI verification in accordance with the ISO guidance.

• Steel and Composite Structures
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• 제27권3호
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• pp.327-335
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• 2018

This paper presents structural assessment of a steel railway bridge for current condition using modal parameter to upgrade finite element modeling in order to gather accurate result. An adequate monitoring, such as acceleration, displacement, strain monitoring, is important tool to understand behavior and to assess structural performance of the structure under surround vibration by means of the dynamic analysis. Evaluation of conditions of an existing steel railway bridge consist of 4 decks, three of them are 14 m, one of them is 9.7 m, was performed with a numerical analysis and a series of dynamic tests. Numerical analysis was performed implementing finite element model of the bridge using SAP2000 software. Dynamic tests were performed by collecting acceleration data caused by surrounding vibrations and dynamic analysis is performed by Operational Modal Analysis (OMA) using collected acceleration data. The acceleration response of the steel bridge is assumed to be governing response quantity for structural assessment and provide valuable information about the current statute of the structure. Modal identification determined based on response of the structure play significant role for upgrading finite element model of the structure and helping structural evaluation. Numerical and experimental dynamic properties are compared and finite element model of the bridge is updated by changing of material properties to reduce the differences between the results. In this paper, an existing steel railway bridge with four spans is evaluated by finite element model improved using operational modal analysis. Structural analysis performed for the bridge both for original and calibrated models, and results are compared. It is demonstrated that differences in natural frequencies are reduced between 0.2% to 5% by calibrating finite element modeling and stiffness properties.

• 한국추진공학회:학술대회논문집
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• 한국추진공학회 2008년 영문 학술대회
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• pp.16-21
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• 2008

Aero-engine, as one kind of rotating machinery with complex structure and high rotating speed, has complicated vibration faults. Therefore, condition monitoring and fault diagnosis system is very important for airplane security. In this paper, a vibration data acquisition and intelligent fault diagnosis system is introduced. First, the vibration data acquisition part is described in detail. This part consists of hardware acquisition modules and software analysis modules which can realize real-time data acquisition and analysis, off-line data analysis, trend analysis, fault simulation and graphical result display. The acquisition vibration data are prepared for the following intelligent fault diagnosis. Secondly, two advanced artificial intelligent(AI) methods, mapping-based and rule-based, are discussed. One is artificial neural network(ANN) which is an ideal tool for aero-engine fault diagnosis and has strong ability to learn complex nonlinear functions. The other is data mining, another AI method, has advantages of discovering knowledge from massive data and automatically extracting diagnostic rules. Thirdly, lots of historical data are used for training the ANN and extracting rules by data mining. Then, real-time data are input into the trained ANN for mapping-based fault diagnosis. At the same time, extracted rules are revised by expert experience and used for rule-based fault diagnosis. From the results of the experiments, the conclusion is obvious that both the two AI methods are effective on aero-engine vibration fault diagnosis, while each of them has its individual quality. The whole system can be developed in local vibration monitoring and real-time fault diagnosis for aero-engine.

• 조명전기설비학회논문지
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• 제19권6호
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• pp.36-45
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• 2005

이 논문은 다른 종류의 유도전동기 구름베어링 손상을 유도전동기 고정자 전류신호해석을 통하여 검출하고 실시간으로 손상을 진단하는 알고리즘을 개발하였다. 유도전동기 구름베어링의 손상을 검출하기 위하여 정상적인 베어링을 갖는 유도전동기, 측정열에 불량을 가지고 있는 전동기와 베어링 외륜에 구멍을 가지고 있는 2가지 종류의 비정상 베어링을 갖는 유도전동기 3set를 실험시스템을 구축하였다. 또한 유도전동기의 구름베어링시스템의 비정상적인 상태에서 고정자전류을 검출하기 위하여 TMS320F2407 DSP 칩을 이용하여 데이터 획득보드를 개발하였다. 이 고정자전류신호를 해석을 통하여 베어링 손상을 검출하기 위한 방법으로 FFT, 웨이브렛 분석 및 내적에 의한 평균 신호패던에 의한 분석결과를 제시하였다. 특히 내적에 의한 신호분석 온 통하여 베어링 손상 여부를 실시간으로 진단할 수 있는 새로운 알고리즘과 분석방법을 제시하였다.

• Safety and Health at Work
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• 제14권3호
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• pp.317-324
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• 2023

Background: COVID-19 pandemic represented a unique stressful event that affected the physical health and psychological well-being (PWB) of individuals and communities. Monitoring PWB is essential not only to clarify the burden on mental health effects but also to define targeted psychological-supporting measures. This cross-sectional study evaluated the PWB of Italian firefighters during the pandemic. Methods: Firefighters recruited during the pandemic period filled out a self-administered questionnaire, the Psychological General Well-Being Index, during the health surveillance medical examination. This tool is usually used to assess the global PWB and explores six subdomains: anxiety, depressed mood, positive well-being, self-control, general health, and vitality. The influencing roles of age, gender, working activities, COVID-19, and pandemic restrictive measures were also explored. Results: A total of 742 firefighters completed the survey. The aggregate median PWB global score was in the 'no distress"" range (94.3 ± 10.3), which was higher than that observed in studies conducted using the same tool in the Italian general population during the same pandemic period. Similar findings were observed in the specific subdomains, thus suggesting that the investigated population was in good PWB condition. Interestingly, significantly better outcomes were detected in the younger firefighters. Conclusion: Our data showed a satisfactory PWB situation in firefighters that could be related to different professional factors such as work organization and mental and physical training. In particular, our results would suggest the hypothesis that in firefighters, maintaining a minimum/moderate level of physical activity (consisting of even just going to work) might have a profoundly positive impact on psychological health and well-being.

• 간호행정학회지
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• 제15권4호
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• pp.491-505
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• 2009

Purpose: This study was to develop an algorithm for emergency nursing care of dyspneic patients. Methods: This methodological study was done through reviews of medical records and literatures, checklists of emergency nursing care for dyspneic patients, interviews with nurses, and experts' validity. Results: Firstly, the initial assessment confirmed the identification of airway patency, accessory muscle usage, RR, $SpO_2$, v/s, skin color, and mental status. Immediate emergency care provided oxygen, checked ABG, EKG, and chest X-ray, established a semi-fowler position, maintained IV routes, administered medication orders, and conducted careful monitoring. Secondly, if the patient exhibited $SpO_2$ of less than 90%, the nurse considered the patient's condition to be aggravated. Thirdly, if the patient showed improvement of more than 90% $SpO_2$, the nurse administered secondary assessment and carried out specific nursing care. However, if the patient continuously showed $SpO_2$ of less than 80%, the nurse assisted the intubation and then executed ventilator therapy. Conclusions: This study suggests that the algorithm is an effective decision tool and utilizing the algorithm is expected to improve the emergency nursing care for dyspneic patients.

• 한국정밀공학회지
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• 제16권8호
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• pp.178-185
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• 1999

In tool condition monitoring systems, parameters should be set to a certain threshold. In many cases, however, the threshold is dependent on cutting conditions, especially the radial immersion ratio. In this presented is a method of on-line estimation of the radial immersion ratio in face milling. When a tooth finishes sweeping, a sudden drop of cutting force occurs. The force drop is equal to the cutting force that acting on a tooth at the swept angle of cut and can be acquired from cutting force signals in feed and cross-feed directions. Average cutting force per tooth period can also be calculated from cutting force signals in two directions. The ratio to cutting forces in two directions acting on a tooth at a certain swept angle of cut and the ratio of average cutting forces in two directions per tooth period are functions of the swept angle of cut and the ratio of radial to tangential cutting forces. Using these parameters, the radial immersion ratio is estimated. Various experiments are performed to verify the proposed method. The results show that the radial immersion ratio can be estimated by this method regardless of other cutting conditions.

• 상하수도학회지
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• 제25권2호
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• pp.177-184
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• 2011

Membrane fouling is an unavoidable phenomenon in operation of seawater reverse osmosis (SWRO) and major obstacle for economic and efficient operation. When fouling occurs on the membrane surface, the permeate flux is decreased, on the contrary, the trans-membrane pressure (TMP) is increased, therefore operation and maintaining costs and potential damage of membranes are able to the pivotal risks of the process. Chemical cleaning process is essential to prevent interruptions for effective RO membrane filtration process. This study focused on proper chemical cleaning condition for polyamide RO membranes of 4 companies. Several chemical agents were applied for chemical cleaning under numbers of operating conditions. Additionally, a monitoring tool of FEEM as autopsy analysis method is adapted for the prediction of organic bio-fouling.