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EPMA quantification on the chemical composition of retained austenite in a Fe-Mn-Si-C-based multi-phase steel

  • Yoon‑Uk Heo;Chang‑Gon Jeong;Soo‑Hyun Kim;Gun‑Young Yoon;T. T. T. Trang;Youngyun Woo;Eun Yoo Yoon;Young‑Seon Lee
    • Applied Microscopy
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    • v.52
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    • pp.14.1-14.10
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    • 2022
  • An electron probe X-ray microanalyzer (EPMA) is an essential tool for studying chemical composition distribution in the microstructure. Quantifying chemical composition using standard specimens is commonly used to determine the composition of individual phases. However, the local difference in chemical composition in the standard specimens brings the deviation of the quantified composition from the actual one. This study introduces how to overcome the error of quantification in EPMA in the practical aspect. The obtained results are applied to evaluate the chemical com position of retained austenite in multi-phase steel. Film-type austenite shows higher carbon content than blocky-type one. The measured carbon contents of the retained austenite show good coherency with the calculated value from the X-ray diffraction.

A Study on the Increase of Dental Technicians in Korea and the Regional Distribution of the Korea Dental Technician Association Members (우리나라 치과기공사의 증가현황 및 협회원의 지역별 분포현황 연구)

  • Kwon, Soon-Seog
    • Journal of Technologic Dentistry
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    • v.26 no.1
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    • pp.9-34
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    • 2004
  • The present study reviews the license registration status of dental technicians and dentists from 1970 to 2002, the number of technician members of The Korea Dental Technician Association from 1990 to 2003, and the number of dentist members in 2003. It also considers the yearly membership fluctuations, its growth rates, yearly increase/decrease, the rate of dentist to dental technician, regional distribution of association members, regional yearly increase/decrease of the members, and the regional distribution of dentists and dental technicians. The purpose is to identify and predict the problems in the demand/supply of dental technicians and the regional imbalance of manpower distribution. By doing so, this study attempts to propose the appropriate standard for the supply of dental technicians and point out the necessity of making mid- or long-term plans for ensuring the efficiency of manpower supply and balanced regional distribution. The result is as follows: 1. The number of dental technicians and dentists in 2002 has grown 36.79 and 9.27 times from 1970, and 2.20 and 2.05 times from 1990, respectively. It tool 11 years for the twofold increase of dental technicians from 1990, one year faster than the same increase of dentists. The number of dental technicians per a dentist was the lowest in 1972 (0.21 person), and the highest in 2002 (0.86 person). Specifically, the fastest growth was observed for a year from 1983 (0.47 technician per a dentist) to 1984 (0.6). From 1984 to 1986, the ratio grew by 0.1 every year. Summing up the numbers of dentists and dental technicians who passed the national certification examination, this study predicted the number of dental technicians per a dentist to be 0.88 in 2003, and 0.90 in 2004. 2. From 1990 to 2003, the average distribution of dental technician was 71.76% in the metropolitan areas and 28.24% in other smaller regions. The proportion of dental technicians working in the three major cities (Seoul, Busan, and Daegu) was the lowest in 2001 (52.39%) and the highest in 1996 (62.66%). The majority number of dental technicians who practiced in the metropolitan areas (about 70% of the entire population) were in service in the three major cities. 3. Compared with 1990, the number of dental technicians in 2003 grew 2.28 times in the large cities, and 2.05 times in other smaller regions. The yearly growth rate was the highest in 1994 over the previous year: 26.06% in large cities and 17.86% in the other regions. In the large metropolitan cities, the growth rate was the highest in Incheon (5.8 times for 5 years from 1998 to 2003), In the rest of the regions, the increase of dental technicians was the highest in Gyeonggi (6.5 times from 1990 to 2003). 4. In 2003, as much as 73.40% of all the members of the Korea Dental Technician Association were distributed in the large metropolitan cities, and the rest 26.60% were in other smaller regions. Meanwhile, 54.35% of the dentists practiced in the metropolitan cities, and the rest 45.65% were in service at other regions. This result indicates that more dental technicians than dentists are concentrated in large cities. More than half of all the technician members of the Association are distributed in the three major cities (i.e. Seoul, Busan, Daegu). On the other hand, 42.03% of dentist members are in these three cities and 53.97% of them practice in Seoul, Gyeonggi, and Busan. In 2003, the ratio of dentist to dental technician is 1:0.43 in general, while the ratio is 1:0.58 in the metropolitan cities, and 1:0.43 in other regions. In 2003, 33.30% of all the certified dental technicians are the member of the Korea Dental Technician Association, while 66.82% of all the licensed dentists are its members.

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Calculation of the Electromagnetic Fields Distribution around the Human Body and Study of Transmission Loss Related with the Human Body Communication (인체 통신에 따른 인체 주변에서의 전기장 분포 계산 및 전송 손실 연구)

  • Ju, Young-Jun;Gimm, Youn-Myoung
    • The Journal of Korean Institute of Electromagnetic Engineering and Science
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    • v.23 no.2
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    • pp.251-257
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    • 2012
  • Human body communication means transmitting and receiving data through human body medium or through free space along with the human body skin. Electric field distribution around the human body between the transmitter and the receiver were calculated at five different frequencies with 5 MHz interval between 10 MHz and 30 MHz. Commercial electromagnetic simulation tool was used for the calculation of E-field distributions applying the Korean standard male model including 29 different kinds of human tissues. After calculating specific absorption rate(SAR) values on back of the hand, it was compared with International Commission on Non-Ionizing Radiation Protection(ICNIRP) human protection guideline. While conductivities(${\sigma}$) and relative permittivities(${\varepsilon}_r$) of the human tissues for each frequency were input as the analyzing parameters, electric field intensities near both hands were integrated along the integral line between the nearby electrodes for the calculation of the transmitting and receiving voltages whose ratio was defined as channel loss. The calculated channel losses were about ($75{\pm}1$) dB and showed nearly flat response all through the evaluated frequencies.

Estimating the Spatial Distribution of Rumex acetosella L. on Hill Pasture using UAV Monitoring System and Digital Camera (무인기와 디지털카메라를 이용한 산지초지에서의 애기수영 분포도 제작)

  • Lee, Hyo-Jin;Lee, Hyowon;Go, Han Jong
    • Journal of The Korean Society of Grassland and Forage Science
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    • v.36 no.4
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    • pp.365-369
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    • 2016
  • Red sorrel (Rumex acetosella L.), as one of exotic weeds in Korea, was dominated in grassland and reduced the quality of forage. Improving current pasture productivity by precision management requires practical tools to collect site-specific pasture weed data. Recent development in unmanned aerial vehicle (UAV) technology has offered cost effective and real time applications for site-specific data collection. To map red sorrel on a hill pasture, we tested the potential use of an UAV system with digital cameras (visible and near-infrared (NIR) camera). Field measurements were conducted on grazing hill pasture at Hanwoo Improvement Office, Seosan City, Chungcheongnam-do Province, Korea on May 17, 2014. Plant samples were obtained at 20 sites. An UAV system was used to obtain aerial photos from a height of approximately 50 m (approximately 30 cm spatial resolution). Normalized digital number values of Red, Green, Blue, and NIR channels were extracted from aerial photos. Multiple linear regression analysis results showed that the correlation coefficient between Rumex content and 4 bands of UAV image was 0.96 with root mean square error of 9.3. Therefore, UAV monitoring system can be a quick and cost effective tool to obtain spatial distribution of red sorrel data for precision management of hilly grazing pasture.

A Study on the Analysis of the Error in Photometric Stereo Method Caused by the General-purpose Lighting Environment (測光立體視法에서 범용조명원에 기인한 오차 해석에 관한 연구)

  • Kim, Tae-Eun;Chang, Tae-Gyu;Choi, Jong-Soo
    • Journal of the Korean Institute of Telematics and Electronics B
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    • v.31B no.11
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    • pp.53-62
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    • 1994
  • This paper presents a new approach of analyzing errors resulting from nonideal general-purpose lighting environment when the Photometric Stereo Method (PSM) is applied to estimate the surface-orientation of a three-dimensional object. The approach introduces the explicit modeling of the lighting environment including a circular-disk type irradiance object plane and the direct simulation of the error distribution with the model. The light source is modeled as a point source that has a certain amount of beam angle, and the luminance distribution on the irradiance plane is modeled as a Gaussian function with different deviation values. A simulation algorithm is devised to estimate the light source orientation computing the average luminance intensities obtained from the irradiance object planes positioned in three different orientations. The effect of the nonideal lighting model is directly reflected in such simulation, because of the analogy between the PSM and the proposed algorithm. With an instrumental tool designed to provide arbitrary orientations of the object plane at the origin of the coordinate system, experiment can be performed in a systematic way for the error analysis and compensation. Simulations are performed to find out the error distribution by widely varying the light model and the orientation set of the object plane. The simulation results are compared with those of the experiment performed in the same way as the simulation. It is confirmed from the experiment that a fair amount of errors is due to the erroneous effect of the general-purpose lighting environment.

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Impact of Changes in Maternal Age and Parity Distribution on Low Birth Weight Incidence Rate (모성연령과 출산순위의 변화가 저체중아 출생률에 미친 영향)

  • Kim, Young-Ae;Park, Jung-Han
    • Journal of Preventive Medicine and Public Health
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    • v.22 no.2 s.26
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    • pp.276-282
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    • 1989
  • The objective of this study was to examine the impact of changes in maternal age and parity distribution on birth weight. The study population included 7,786 single live births in 1977 and 8,671 single live births in 1987 delivered at 9 medical facilities in Pusan. Data were obtained from the delivery record. The proportion of infants born to the mothers of 25-29 years increased from 56.475 in 1977 to 65.1% in 1987 and the proportion to the mothers of 30-34 years increased from 18.8% in 1977 to 21.6% in 1987. In the same period, the proportions of 1st and 2nd birth order were increased from 56.9% and 28.8% to 59.9% and 36.8%, respectively. The proportion of infants born to the age group of ${\leq}24\;and\;35{\leq}$ years were decreased in 1987. The proportion of births of the third or higher birth order was decreased from 14.2% in 1977 to 3.3% in 1987. Low birth weight (<2500gm) incidence rate was 5.3% in 1977 and it was decreased to 4.0% in 1987. It was estimated that changes in maternal age-parity distribution accounted for 10.7% of the decreased in low birth weight incidence rate. Rest of the change (89.3%) was attributed to the reduction of age-parity specific low birth weight incidence rate. Application of the direct adjustment method was considered to be an adequate tool for evaluating the impact of family planning on neonatal health.

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Korean Customer Attitudes Towards SNS Shopping

  • Cho, Young-Sang;Heo, Jeong-Yoon;Youn, Myoung-Kil
    • Journal of Distribution Science
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    • v.10 no.8
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    • pp.7-14
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    • 2012
  • As a new format of retailing, social shopping on SNS has rapidly grown in recent. Although there is much literature associated with customer behaviours in the academic world, little attention has been paid to identifying the shopping patterns of SNS shoppers. This paper will, thus, identify how perceived value has an impact on the buying intention of SNS shoppers, after illustrating what kind of factor influences the formation process of perceived value in the Korean marketplace. Given that SNS shoppers are for the most part 20s as well as 30s, the authors handed out questionnaires to them. Furthermore, based on literature review results, the conceptualised research model was developed. Despite lack of literature, the authors developed five constructs like price reduction, quantity- and time-limited message, product ranges, information-sharing, and required number of shoppers. The researchers made a considerable effort to identify the relationship between research concepts and each variable, based on a few research analysis methods such as frequency analysis, the Varimax rotation technique used orthogonal rotation, Cronbach's Alpha, PCA (Principle Component Analysis), and the like. Amongst the 5 variables used to measure the degree of influences on the perceived value as a social shopping characteristic, it has been evident that price cut, required minimum shoppers, product variety, and information-sharing have a positive impact on the perceived value formation processes of SNS customers. Also, this research implies that SNS retailers can differentiate themselves from other retailers by differently using the above factors. From a practitioner's point of view, these factors should be strategically used to increase the social shopping opportunities of SNS users. It is, furthermore, evident that the perceived value formed by the above 4 factors have played an important role in the buying decision process of SNS customers. In a sense, whether customers are aware of higher price cut rates, information-sharing, required minimum shoppers, and product variety has a positive impact on making buying decisions. From a retailer's point of view, online shopping mall operators are able to use blog as well as twitter to improve the buying intention as a marketing tool of social network, because the business activities provided by social shopping retailers, like the rapid, accurate responses to customer requirements, the provision of a variety of information, and the communications between customers are closely related to buying intentions. There are a few research limitations to conduct this empirical research. It was not easy to review prior papers, due to its lack. In spite of the increasing number of SNS shoppers in Korea, little research attention has been paid to this kind of research topic by academicians, because buying products or services through SNS is in its infancy. With regard to research populations, it would be difficult to generalise the research findings in Korea, owing to unbalanced respondent distribution. Considering the above research limitations as well as the growth of social shopping, many authors should pay considerable attention to SNS-related issues in the future, and develop the more sophisticated criteria to measure the characteristics of SNS shoppers.

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Application of Indicator Geostatistics for Probabilistic Uncertainty and Risk Analyses of Geochemical Data (지화학 자료의 확률론적 불확실성 및 위험성 분석을 위한 지시자 지구통계학의 응용)

  • Park, No-Wook
    • Journal of the Korean earth science society
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    • v.31 no.4
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    • pp.301-312
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    • 2010
  • Geochemical data have been regarded as one of the important environmental variables in the environmental management. Since they are often sampled at sparse locations, it is important not only to predict attribute values at unsampled locations, but also to assess the uncertainty attached to the prediction for further analysis. The main objective of this paper is to exemplify how indicator geostatistics can be effectively applied to geochemical data processing for providing decision-supporting information as well as spatial distribution of the geochemical data. A whole geostatistical analysis framework, which includes probabilistic uncertainty modeling, classification and risk analysis, was illustrated through a case study of cadmium mapping. A conditional cumulative distribution function (ccdf) was first modeled by indicator kriging, and then e-type estimates and conditional variance were computed for spatial distribution of cadmium and quantitative uncertainty measures, respectively. Two different classification criteria such as a probability thresholding and an attribute thresholding were applied to delineate contaminated and safe areas. Finally, additional sampling locations were extracted from the coefficient of variation that accounts for both the conditional variance and the difference between attribute values and thresholding values. It is suggested that the indicator geostatistical framework illustrated in this study be a useful tool for analyzing any environmental variables including geochemical data for decision-making in the presence of uncertainty.

The Distribution and Characteristics of Geographical Names on 1:50,000 Topographic Map of the Korean Peninsula in the Early 20th Century ("오만분일지형도(五萬分一地形圖)"에 나타난 20세기 초 한반도의 지명 분포와 특성)

  • Kim, Sun-Hee
    • Journal of the Korean Geographical Society
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    • v.43 no.1
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    • pp.87-103
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    • 2008
  • The geographical name is an expression of human knowledge about living conditions and a basic tool for understanding about regional cultures and history as a result of spatiotemporal changes. This study aims to understand the historical and regional characteristics by analyzing the frequency and distribution of geographical names of 1:50,000 topographic map in the early 20th century and materializing on electronic cultural atlas. The result of this analysis is as follows. First, the aspect of distributed geographical names on the Korean Peninsula reflects a general trait of the country's natural and human environment included geographical features, population, arable land, the number of counties and villages, and functions of administration and military, etc. Second, through the frequency and weight of their names, the analysis shows not only the change of native names, but also the country's phase of the time by Japanese colonial policies such as exploitation of resources, the construction of railroads, and a desire to control of the border area with Manchuria. In addition, the study identified regional characteristics and differences in environmental perception and preferences, and naming basis and forms by the comparative analysis of each type of geographical names associated with village and ridge such as 'Chi' 'Ryung' 'Duk' 'Hang' 'Pyeong' 'Gok'. In particular, those characteristics were largely affected from environmental difference of each area.

Robust Design for Showerhead Thermal Deformation

  • Gong, Dae-Wi;Kim, Ho-Jun;Lee, Seung-Mu;Won, Je-Hyeong
    • Proceedings of the Korean Vacuum Society Conference
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    • 2014.02a
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    • pp.150.1-150.1
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    • 2014
  • Showerhead is used as a main part in the semiconductor equipment. The face plate flatness should remain constant and the cleaning performance must be gained to keep the uniformity level of etching or deposition in chemical vapor deposition process. High operating temperature or long period of thermal loading could lead the showerhead to be deformed thermally. In some case, the thermal deformation appears very sensitive to showerhead performance. This paper describes the methods for robust design using computational fluid dynamics. To reveal the influence of the post distribution on flow pattern in the showerhead cavity, numerical simulation was performed for several post distributions. The flow structure appears similar to an impinging flow near a centered baffle in showerhead cavity. We took the structure as an index to estimate diffusion path. A robust design to reduce the thermal deformation of showerhead can be achieved using post number increase without ill effect on flow. To prevent the showerhead deformation by heat loading, its face plate thickness was determined additionally using numerical simulation. The face plate has thousands of impinging holes. The design key is to keep pressure drop distribution on the showerhead face plate with the holes. This study reads the methodology to apply to a showerhead hole design. A Hagen-Poiseuille equation gives the pressure drop in a fluid flowing through such hole. The assumptions of the equation are the fluid is viscous-incompressible and the flow is laminar fully developed in a through hole. An equation can be expressed with radius R and length L related to the volume flow rate Q from the Hagen-Poiseuille equation, $Q={\pi}R4{\Delta}p/8{\mu}L$, where ${\mu}$ is the viscosity and ${\Delta}p$ is the pressure drop. In present case, each hole has steps at both the inlet and the outlet, and the fluid appears compressible. So we simplify the equation as $Q=C(R,L){\Delta}p$. A series of performance curves for a through hole with geometric parameters were obtained using two-dimensional numerical simulation. We obtained a relation between the hole diameter and hole length from the test cases to determine hole diameter at fixed hole length. A numerical simulation has been performed as a tool for enhancing showerhead robust design from flow structure. Geometric parameters for the design were post distribution and face plate thickness. The reinforced showerhead has been installed and its effective deposition profile is being shown in factory.

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