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Life assessment predictions of reformer tubes of HP40Nb grade steel used in the petrochemical industry were investigated by quantitative metallographic evaluations of the area fractions of precipitated carbides. Correlations were established between the field-service periods and area fractions of the carbides via microstructural analysis. The microstructures of the virgin and other tubes were examined using optical microscopy (OM) for service periods of 1.8, 6.0, 7.2, 8.5, 9.7, and 16.2 years at 950 °C. The area fractions of the precipitates were measured by image analysis using ImageJ software. The results showed that increase in the area fractions of the precipitates was almost proportional to increase their service times. The relationships between area fractions of the precipitates and service times were also discussed for a 6-year cracked tube and a tube that had been in service for 11.5 years at another furnace. The obtained relationship can thus be used via the surface replication method for on-site residual life assessments.

This research purports to find out the factors that affect the level of emotional labor in dental hygienists. Data were collected from 204 dental hygienists working at 5 university hospitals and 55 dental clinics through self-administered questionnaire, and analyzed by statistical analysis using t-test, ANOVA, and regression analysis. The main findings of the study are as follows: First, the higher the educational level of dental hygienists, and the bigger the size of dental institutions they work, the higher the level of emotional labor of dental hygienists. Second, patient and environmental factors were found to have significant effects on the level of emotional labor. The above results imply that managers should try to make the workplace better environment which can secure appropriate workload and rewards, and support for work related education programs etc. It is also needed to educate the patients in order to prevent unnecessary conflicts between the patients and dental hygienists.

Energy industry facilities can cause fatal damage for internal industry employee as well as ex-ternal general people because handling various kinds of gas and harmful substance might be spread to large scale severe accident by fire, explosion, and toxic gas leakage. In order to prevent these accidents, quantifica-tion by damage effect on structure and human is tried by using quantitative risk assessment, but it is difficult to process instantly exceptional cases and requires knowledge of expert. This paper aims to minimize excep-tional cases and knowledge of expert, and present risk with human perceptible. So, we designed and developed zone-base risk analysis system that can compute risk of zone in real time at that point using database and in-cremental model. Key words : risk analysis, QRA, real-time analysis 1) I. 서 론 에너지 대규모 산업시설물에서는 다양한 종류의 가스나 유해물질을 다루고 있어 사고발생 시 대규모로 확대될 위험이 매우 커서 막대한 피해를 발생시킬 † Corresponding author:dbstar@kgs.or.kr Copyright ⓒ 2013 by The Korean Institute of Gas

This study evaluated comparison of the risk according to the type of fuel by three-dimensional simulation tool(FLACS). The consequence analysis of fire explosion and jet-fire was carried out in the layout of a typical high-pressure gas filling stations using CNG, hydrogen and 30%HCNG. Under the same con-ditions, hydrogen had a 30kPa maximum overpressure, CNG had a 0.4kPa and HCNG had a 3.5kPa. HCNG overpressure was 7.75 times higher than the CNG measurement, but HCNG overpressure was only 11.7% compared to hydrogen. In case of flame propagation, hydrogen had a very fast propagation characteristics. On the other hand, CNG and HCNG flame propagation velocity and distance tended to be relatively safe in com-parison to hydrogen. The estimated flame boundary distance by jet-fire of hydrogen was a 5.5m, CNG was a 3.4m and HCNG was a 3.9m.Key words : hydrogen blended natural gas(HCNG), consequence analysis, explosion, jet fire 1) I. 서 론 지구온난화로 인한 기상이변 등이 전 세계적으로 이슈가 되고 있고, 국제사회는 이에 대한 해법을 찾기 위해 환경규제를 더욱더 강화하는 기조로 기후변화협

It is more important to realize safety management, medium-large accident prevention and risk prediction as accident of industry facilities can generate enormous physical and human damage because most energy plant might handle toxic substance. Especially, atmospheric dispersion system, which is able to simu-late situation, have been used for release accident of toxic substance since the accident can show different of dispersion range and velocity according to release material, storage facility and atmospheric status. However those systems have been used generally in design step of industry facility and are difficult to deal with release accident quickly. Although some researches and cases have been studied for using real-tome atmospheric in-formation, there are insufficient system for processing quickly release accident. This paper aims to develop re-al-time smart atmospheric dispersion system that can deal with release accident quickly by enhancing distinct characteristics and efficiency of energy plant, and select release time and area using intelligent algorithm as ac-cident prevention type.Key words : mobile, AR(augmented reality), safety management

Background: It is well known that male-pattern baldness (MPB) is not started from occipital, but frontal or scalp of head. We can assume that distribution of androgenic steroids is different for each region of the head. Objective: We hypothesize that the levels of androgenic steroids are different not only between vertex hair with MPB and controls but also between occipital hair with MPB and controls. Moreover, we want to search for the biochemical indicator in plasma and hair sample (baldness: 22, non-baldness: 13) obtained from dermatology of medical center. After then, we desire to present fundamental data regarding diagnosis, medical cure, and prevention for premature MPB. Methods: After hair and plasma were hydrolyzed, and then extracted with organic solvent. To assess androgenic steroids levels, we used gas chromatography–mass spectrometry (GC–MS) system in selected ion monitoring mode. Results: The level of dihydrotestosterone (DHT) and the ratio of testosterone to epitestosterone (T/E ratio) in vertex hair from premature baldness subjects were higher than in the sample of non-baldness subjects (P

Database administrators should be aware of workload characteristics for managing database systems. Workload characteristics can be different depending on database application. In particular, identifying workloads in mixed database applications might be quite difficult. Therefore, a method is necessary for identifying workloads in the mixed database application. This paper aims to identify workloads in the mixed database application using data mining technologies. To construct the mixed database application, we use the TPC-C and TPC-W benchmark. We discriminate between train workloads (workloads using the TPC-C or TPC-W benchmarks) and test workloads (mixed workloads of both benchmarks), and modify the algorithm of k-NN (Nearest Neighbor) classifier in order to satisfy our objectives. The modified k-NN algorithm measures how close the test workloads are to the train workloads. The modified k-NN algorithm is better than others for identifying workloads because its results are lower than others in the oscillation depending on the k parameter and the error rate. This research contributes towards considering flexible tuning methods using workload identification information