• 대기
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• 제18권3호
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• pp.237-248
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• 2008

A thermal index which considers metabolic heat generation of human body is proposed for operational forecasting. The new thermal index, Perceived Temperature (PT), is forecasted using Weather Research and Forecasting (WRF) mesoscale model and validated. Forecasted PT shows the characteristics of diurnal variation and topographic and latitudinal effect. Statistical skill scores such as correlation, bias, and RMSE are employed for objective verification of PT and input meteorological variables which are used for calculating PT. Verification result indicates that the accuracy of air temperature and wind forecast is higher in the initial forecast time, while relative humidity is improved as the forecast time increases. The forecasted PT during 2007 summer is lower than PT calculated by observation data. The predicted PT has a minimum Root-Mean-Square-Error (RMSE) of $7-8^{\circ}C$ at 9-18 hour forecast. Spatial distribution of PT shows that it is overestimated in western region, while PT in middle-eastern region is underestimated due to strong wind and low temperature forecast. Underestimation of wind speed and overestimation of relative humidity have caused higher PT than observation in southern region. The predicted PT from the mesoscale model gives appropriate information as a thermal index forecast. This study suggests that forecasted PT is applicable to the prediction of health warning based on the relationship between PT and mortality.

• 대한환경공학회지
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• 제29권1호
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• pp.40-46
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• 2007

펄스 코로나 방전에 의한 페놀 수용액 처리 특성에 관해 실험실 규모 실험을 수행하였으며 페놀 전환에 미치는 인가전압, 유입 산소, 전극 구조의 영향을 관찰하였다. 액체상 내에서 일어나는 방전은 전류 흐름으로부터 용액으로의 열전달에 의해 용액의 온도를 상승시키고 페놀을 분해하여 각종 유기산을 생성시킴으로써 pH를 감소시키며, 하전입자의 생성과 유기산 생성으로 인해 용액의 전도도 값을 증가시키는 것으로 나타났다. 외부로부터 공급되는 산소는 용액 내에서 오존 생성과 용해를 통해 OH 라디칼을 생성시킴으로써 페놀의 분해속도를 증가시키는 것으로 나타났다. 방전이 액체상 및 기체상에서 동시에 발생하는 series type의 전극 구조를 사용하면 기체상에서 높은 농도의 오존을 생성시킬 수 있으므로 액체상에서만 방전이 발생하는 reference type의 전극 구조에서보다 높은 페놀 분해 속도와 TOC 제거 효율을 얻을 수 있는 것으로 나타났다.

• Environmental Analysis Health and Toxicology
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• 제30권
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• pp.12.1-12.7
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• 2015

Objectives In South Korea, health insurance data are used as material for the health insurance of national whole subject. In general, health insurance data could be useful for estimating prevalence or incidence rate that is representative of the actual value in a population. The purpose of this study was to apply the concept of episode of care (EoC) in the utilization of health insurance data in the field of environmental epidemiology and to propose an improved methodology through an uncertainty assessment of disease course and outcome. Methods In this study, we introduced the concept of EoC as a methodology to utilize health insurance data in the field of environmental epidemiology. The characterization analysis of the course and outcome of applying the EoC concept to health insurance data was performed through an uncertainty assessment. Results The EoC concept in this study was applied to heat stroke (International Classification of Disease, 10th revision, code T67). In the comparison of results between before and after applying the EoC concept, we observed a reduction in the deviation of daily claims after applying the EoC concept. After that, we categorized context, model, and input uncertainty and characterized these uncertainties in three dimensions by using uncertainty typology. Conclusions This study is the first to show the process of constructing episode data for environmental epidemiological studies by using health insurance data. Our results will help in obtaining representative results for the processing of health insurance data in environmental epidemiological research. Furthermore, these results could be used in the processing of health insurance data in the future.

• International Journal of Aeronautical and Space Sciences
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• 제18권2호
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• pp.206-214
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• 2017

In this study, measurement of thermophysical properties of materials at high temperatures was performed. This experiment employed a heater device to heat the material to a high temperature. The images of the specimen surface due to thermal load at various temperatures were recorded using charge-coupled device (CCD) cameras. Afterwards, the full-field thermal deformation of the specimen was determined using the digital image correlation (DIC) method. The capability and accuracy of the proposed technique are verified by two experiments: (1) thermal deformation and strain measurement of a stainless steel specimen that was heated to $590^{\circ}C$ and (2) thermal expansion and thermal contraction measurements of specimen in the process of heating and cooling. This research focused on two goals: first, obtaining the temperature dependence of the coefficient of thermal expansion, which can be used as data input for finite element simulation; and second, investigating the capability of the DIC method in measuring full-field thermal deformation and strain. The results of the measured coefficient of thermal expansion were close to the values available in the handbook. The measurement results were in good agreement with finite element method simulation results. The results reveal that DIC is an effective and accurate technique for measuring full-field high-temperature thermal strain in engineering fields such as aerospace engineering.

• 한국태양에너지학회:학술대회논문집
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• 한국태양에너지학회 2009년도 춘계학술발표대회 논문집
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• pp.184-189
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• 2009

In order to improve the operation of energy systems, it is necessary for the urban communities to have reliable optimization routines, both computerized and manual, implemented in their organizations. However, before a production plan for the energy system units can be constructed, a prediction of the energy systems first needs to be determined. So, several methodologies have been proposed for energy demand prediction, but due to uncertainties in urban community, many of them will fail in practice. The main topic of this paper has been the development of a method for energy demand prediction at urban community. Energy demand prediction is important input parameters to plan for the energy planing. This paper presents a energy demand prediction method which estimates heat and electricity for various building categories. The method has been based on artificial neural networks(ANN). The advantage of ANN with respect to the other method is their ability of modeling a multivariable problem given by the complex relationships between the variables. Also, the ANN can extract the relationships among these variables by means of learning with training data. In this paper, the ANN have been applied in oder to correlate weather conditions, calendar data, schedules, etc. Space heating, cooling, hot water and HVAC electricity can be predicted using this method. This method can produce 10% of errors hourly load profile from individual building to urban community.

• Journal of Welding and Joining
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• 제20권2호
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• pp.82-89
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• 2002

In order to clarify hot cracking phenomena occurred in Inconel 690 welds and it's prevention, in this study, the cracking behavior and the influence of welding variables on cracking in Inconel 690 overlay welds on Mn-Ni-Cr-Mo steel(SA 508 cl.3) for pressure vessel were investigated by using mock-up test. The main results are as follows: The cracks in Inconel 690 overlay welds were mainly generated near the start and the end part of welding beads adjacent to STS 309L welded outside of Inconel 690 welds. Most of the cracks showed typical solidification crack, and also it was assumed that there was possibility of liquation cracking in HAZ. The existence of Nb constituents or concentration of Nb was recognized on the fracture facets of the solidification cracks in the welds by SMAW. Therefore Nb was considered to be the main factor of the solidification cracking. As the weld heat input was more increased and the weld bead length was longer, the extent of cracking was more increased. Moreover the extent of cracking was considerably decreased by changing of welding sequence to the start and the end part of welds. Hot cracking in welds by GTAW was considerably decreased as compared with that of SMAW. And cracks were well generated in the Inconel 690 overlay welds adjacent to 575 309L welds. This means that the hot cracking susceptibility of Inconel 690 welds was largely varied by chemical components and/or compositions of filter metals, base metals and neighboring welds.

• 대한용접접합학회:학술대회논문집
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• 대한용접접합학회 2002년도 Proceedings of the International Welding/Joining Conference-Korea
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• pp.320-323
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• 2002

This paper presents a new generation of system for pressure vessel and shipbuilding. Typical pressure vessel and ship building weld joint preparations are either traditional V, butt, fillet grooves or have narrow or semi narrow gap profiles. The fillet and U groove are prevalently used in heavy industries and shipbuilding to melt and join the parts. Since the wall thickness can be up to 6" or greater, welds must be made in many layers, each layer containing several passes. However, the welding time for the conventional processes such as SAW(Submerged Arc Welding) and FCAW(Flux Cored Arc Welding) can be many hours. Although SAW and FCAW are normally a mechanized process, pressure vessel and ship structures welding up to now have usually been controlled by a full time operator. The operator has typically been responsible for positioning each individual weld run, for setting weld process parameters, for maintaining flux and wire levels, for removing slag and so on. The aim of the system is to develop a high speed welding system with multitorch for increasing the production speed on the line and to remove the need for the operator so that the system can run automatically for the complete multi-torch multi-layer weld. To achieve this, a laser vision sensor, a rotating torch and an image processing algorithm have been made. Also, the multitorch welding system can be applicable for the fine grained steel because of the high welding speed and lower heat input compare to a conventional welding process.

• 한국추진공학회지
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• 제21권5호
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• pp.46-53
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• 2017

본 논문은 "예혼합실+노즐+연소실"의 3단으로 구성된 예혼합 가스터빈 연소기의 열음향모델을 제시한다. 음향장의 동적특성은 화염섭동을 입력으로 화염면에서의 속도를 출력으로 하는 음향전달함수로 표현되었다. 음향전달함수의 극점들을 분석함으로서 음향장의 공진주파수는 각 단 사이의 면적비, 그리고 음향파가 각 단을 왕복 운동하는 3개 주파수들의 조합으로 주어짐을 보였다. 극점을 나타내는 함수의 형태를 분석하여 3단 연소기의 여러 파라미터가 변함에 따라서 공진주파수가 어떻게 변하는가에 대하여 해석적으로 분석하였고 문헌의 실험결과와 일치함을 확인하였다.

• Nuclear Engineering and Technology
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• 제52권8호
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• pp.1871-1880
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• 2020

Round robin analyses for vessel failure probabilities due to PTS events are proposed for plant-specific analyses of all types of reactors developed in Korea. Four organizations, that are responsible for regulation, operation, research and design of the nuclear power plant in Korea, participated in the round robin analysis. The vessel failure probabilities from the probabilistic fracture mechanics analyses are calculated to assure the structural integrity of the reactor pressure vessel during transients that are expected to initiate PTS events. The failure probabilities due to various parameters are compared with each other. All results are obtained based on several assumptions about material properties, flaw distribution data, and transient data such as pressure, temperature, and heat transfer coefficient. The realistic input data can be used to obtain more realistic failure probabilities. The various results presented in this study will be helpful not only for benchmark calculations, result comparisons, and verification of PFM codes developed but also as a contribution to knowledge management for the future generation.

• Korean Chemical Engineering Research
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• 제56권3호
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• pp.421-429
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• 2018

본 연구에서는 100 kW급 연료전지 시스템의 운영을 위한 공정 및 CFD 모델링을 진행하였다. 공정 모델링을 통해 연료전지 각 단위 공정에 유입되는 유량을 도출하였으며 수소로 전환되지 않는 디젤의 환류량을 도출하였다. 디젤의 환류를 고려한 새로운 유입 유량 조건을 이용해 CFD 해석을 진행한 결과, 환류 디젤이 없는 것으로 가정한 이전 연구결과에 비해 더 짧은 유입시간과 비슷한 시간의 처리시간을 가지는 이점이 있음을 확인하였다. 6기의 탈황 반응기를 이용해 100 kW급 연료전지를 가동시키는데 필요한 TSA 탈황 시스템 구성을 완료하였으며 전체 TSA 공정 운영을 위한 운용 방안을 도출하였다. 반응기 사이의 열 전달 해석을 통해 저온의 탈황공정과 고온의 재생공정 간의 열 간섭이 크지 않음을 확인하였다. 본 연구결과는 연료전지 시스템의 효율화에 기여할 것이며, 도출된 탈황모듈의 설계는 연료전지 시스템뿐만 아니라 청정 석유화학산업의 기초가 될 것으로 기대된다.