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와이블 서비스시간을 갖는 M/G/1 대기모형의 오버슛과 근사법 제안
연미연 ( Miyeon Yeon ),배종호 ( Jongho Bae ) 충남대학교 기초과학연구원 2021 충남과학연구지 Vol.38 No.1
It is considered the M/G/1 queueing model with Weibull service time. We propose an approximation of the distribution of the overshoot of workload process in the model and verify the accuracy of the approximation. Then we compare our approximation with preceding research.
분말고속도공구강을 활용한 베어링 레이스 열간 단조 금형의 수명 및 기계적 특성
홍성연,배종수,Hong, Seong-Hyeon,Bae, Jong-Soo 한국분말야금학회 2007 한국분말재료학회지 (KPMI) Vol.14 No.6
P/M high speed steel (1.26% C, 4.42% Cr, 6.54% W, 4.92% Mo, 3.21 % V, 8.77% Co, bal. Fe) was applied to hot former die. It showed that the die life became 2.7 times higher than that of cast/wrought SKH 55 tool steel which is commercially used. The increase of die life was corresponding to the improved hardness and transverse rupture strength of PM high speed steel due to the finer grain and carbide as well as the uniform carbide distribution. The P/M high speed steel with the promoted die life could be an alternative to the conventional SKH55.
배종인(J. I. Bae),하헌영(H. Y. Ha),강전연(J. Y. Kang),황병철(B. Hwang),이태호(T. H. Lee) 한국소성가공학회 2012 한국소성가공학회 학술대회 논문집 Vol.2012 No.5
Duplex stainless steels (DSS) composed of ferrite and austenite have an attractive combination of mechanical and corrosion properties. Commercial DSS contain a considerable amount of Ni ranging from 4 to 7 wt.%. In recent years, efforts have been made to develop lean DSS with reduce Ni which can provide substantial economical savings and improve mechanical properties due to transformation-induced plasticity. In the present study, several kinds of lean DSS with unique chemical composition were fabricated, and the mechanical and corrosion properties were investigated with precipitation behavior. Based on the results, the lean DSS developed in KIMS showed an excellent combination of strength-elongation and good corrosion resistance.
박정임,박희순,배종일,김구연 한국하천호수학회 2023 생태와 환경 Vol.56 No.3
This study was conducted to investigate the current status of seagrass species in the Nakdong River estuary from May to June 2023. To survey the seagrass habitat area, the Nakdong River estuary was divided into seven zones. Aerial photography using drones was conducted to find seagrass areas, GPS tracking was carried out on foot in the intertidal zone and by boat and SCUBA diving in the subtidal zone. To analyze the seagrass status, we measured the morphological characteristics, shoot density, and biomass of representative seagrass species in each zone. Four seagrass species were found in this area: Zostera japonica, Z. marina, Ruppia maritima, and Phyllospadix japonicus. The distribution areas of each species was 338.2 ha, 92.9 ha, 0.9 ha, and 1.4 ha, respectively, with a total area of 432.5 ha. Z. japonica was widely distributed in most of the tidal flats and mudflats of the Nakdong River estuary, while Z. marina was restricted to Nulcha-do, Jinu-do, and Dadae-dong. R. maritima occurred within the habitat of Z. japonica in Eulsukdo and Myeongji mudflats, and P. japonicus inhabited rocky areas in Dadae-dong. The shoot density of each species was 4,575.8±338.3 shoots m-2,244.8±12.0 shoots m-2, 11,302.1±290.0 shoots m-2, and 2862.5±153.5 shoots m-2, respectively. The biomass of each species was 239.7±18.5 gDW m-2, 362.3±20.5 gDW m-2, 33.3±1.2 gDW m-2, and 1,290.0±37.0 gDW m-2, respectively. The results of this study revealed that Z. japonica was dominant in the Nakdong River estuary. In particular, Z. japonica habitats of Eulsukdo, Daema-deung, and Myeongji mudflats were identified as the largest in Korea. The Nakdong River estuary is an important site of ecological, environmental, and economic value, and will require continuous investigation and management of the native seagrasses.
정인성,김종환,최상국,배종연,이미영,Chung, In-Sung,Kim, Jong-Ghan,Choi, Sang-Kug,Bae, Jong-Youn,Lee, Mi-Young The Korean Society for Preventive Medicine 2006 예방의학회지 Vol.39 No.2
Objectives : The objective of this study is to assess the factors influencing biological monitoring of textile coating factory workers exposed to N,N-dimethylformamide(DMF). Methods : We studied 35 workers who were occupationally exposed to DMF from 9 textile coating factories. The study was carried out in two phases; summer and winter. While air concentration of DMF, temperature and humidity were assessed in order to monitor the atmospheric conditions, biological monitoring was done to determine the internal dose by analyzing the N-methylformamide(NMF) collected from urine at the beginning and end of the shift. Questionnaires and medical surveillance were also obtained during the two phases. Results : Median air concentrations of DMF in winter and summer were 1.85 ppm and 2.78 ppm respectively. Also the difference between the urinary NMF concentration at the beginning and end of the shift $({\Delta}NMF)$ was always significant in each season (P < 0.001). The correlations between log DMF in air, log end-of-shift urinary NMF (r=0.555, P < 0.001) and log ${\Delta}NMF$ (r = 0.444, P < 0.001) was statistically significant in summer. The temperature, humidity, a shift system and different styles of clothing worn were significantly different during the two phases. In a multivariate analysis, temperature and the concentration of DMF in the air were the main factors influencing biological monitoring of textile coating factory workers. Conclusions : Concerning more comprehensive prevention measures to reduce exposure for those workers occupationally exposed to DMF, dermal exposure conditions such as temperature and humidity together with the air concentration of DMF should be assessed and biological monitoring is necessary to reduce adverse health effects, especially during the summer.