• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.19 no.2
• /
• pp.15-20
• /
• 2018

The objective of this study is to numerically investigate the thermal characteristics of an automobile exhaust-based heat exchanger for automotive thermoelectric power generation with various exhaust gas mass flow rates and temperatures. The heat exchanger for automotive thermoelectric power generation has a square-type pin installed inside, so the maximum amount of heat can be transferred to the thermoelectric element from the heat energy coming from the automobile exhaust gas. The exhaust gas mass flow rate changed from 0.01, to 0.02, to 0.03 kg/s, and the exhaust gas temperature changed from 400, to 450, to 500, to 550, to $600^{\circ}C$, respectively. A numerical simulation was conducted by using the commercial program ANSYS CFX v17.0. Consequently, the exhaust gas pressure difference between the inlet and the outlet of the heat exchanger is determined according to the flow rate of the exhaust gas. When the mass flow rate of the exhaust gas increased, the pressure difference between the inlet and the outlet of the heat exchanger increased, but the exhaust gas pressure difference between the inlet of the heat exchanger and the outlet did not vary with the exhaust gas temperature. Therefore, in order to obtain the maximum surface temperature from the heat exchanger, the exhaust gas mass flow rate should be lower, and the exhaust gas temperature should be higher.

• Journal of Korean Society for Atmospheric Environment
• /
• v.20 no.4
• /
• pp.555-569
• /
• 2004

Size -segregated measurements of aerosol composition using 8-stage DRUM impactor are used to determine the transport of natural and anthropogenic aerosols at Gosan site from 29 March to 30 May in 2002. Separation of ambient aerosols by DRUM impactor offers many Advantages over other standard filtration techniques. Some of the most important advantages are the ability to segregate into details by particle tire, to better preserve chemical integrity since the air stream doesn＇t pars through the deposit, to collect samples as a function of time, and to have a wide variety of impaction surfaces available to match analytical needs. Although the transport of Yellow sand is a well-known phenomenon in springtime, the result of measurement shows that not only soil dust but also anthropogenic aerosols, including sulfur, enriched trace metals such as Pb, Ni, Zn. Cu, Cr, As, Se, Br, are transported to Gosan in springtime. This study combines the size- and time-resolved aerosol composition measurements with isentropic, backward air-mass trajectories in order to identify some potential source regions of anthropogenic aerosols. As a result, during the NYS period, the average concentration of PM$_{10}$ was 46$\mu\textrm{g}$/㎥, Si, Al. S, Fe, Cl, K, Ca were higher than 1,000 ng/㎥ and Ti was about 100 ng/㎥. The concentrations of Zn, Mn, Cu. Pb, Br, Rb, V, Cr, Ni. At, Se ranged between 1 and 70 ng/㎥. More than 50% typical soil elements, tuck as Al, Si, Fe, Cd. Ti, Cr, Cu, Br. were distributed in a coarse particle range(5.0-12${\mu}{\textrm}{m}$). In other hand, anthropogenic pollutants, luck as S, N, Vi, were mainly distributed in a fine particle range (0.09-0.56${\mu}{\textrm}{m}$). During the YS period, PM$_{10}$ increased about 8 times than NYS period, and main soil elements, such as Al, Si, S, K, V, Mn, Fe also doubled in coarse particle range (1.15-12${\mu}{\textrm}{m}$). But Zn, As, Pb, Cu and Se, which distributed in the time aerosols (0.09-0.56${\mu}{\textrm}{m}$), were on the same level with or decreased than NYS period. Finally. except the YS Period, coarse particles (2.5-12${\mu}{\textrm}{m}$) are inferred to be influenced by soil, coal combustion, waste incineration, ferrous and nonferrous sources through similar pathways with Yellow Sand. But fine particles have different sources, such as coal combustion, gasoline vehicle, biomass burning, oil or coal combustion, nonferrous and ferrous metal sources, which are transported from China, Korea peninsula and local sources.ces.

• Journal of Korean Society of Environmental Engineers
• /
• v.38 no.8
• /
• pp.459-467
• /
• 2016

In order to assess the pollution status and distribution characteristics of PM and PM-bound species, PM10 samples were collected using mini-volume air sampler at the subway cabin in Daejeon city. Measurements of about 24 elements including toxic metals (e.g., As, Cr, Mn, V, Zn) in PM10 were made by instrumental neutron activation analysis and X-ray fluorescence. The average PM10 concentration was $59.3{\pm}14.5{\mu}g/m^3$ in the subway cabin with a range of 42.2 to $97.4{\mu}g/m^3$, while the associated elemental concentrations were varied in the range of $10^{-3}$ to $10^5ng/m^3$. It was found that the concentration of Fe ($12.5{\mu}g/m^3$) was substantially higher than any other element. The Fe concentration was apportioned by about 20% of the PM10 concentration. The results of factor analysis indicate that there are no more than six sources in the cabin (e.g., brake-nonferrous metal particle, resuspended rail dust, fuel combustion, vehicle exhaust, black carbon, Cr-related).

• Journal of the Computational Structural Engineering Institute of Korea
• /
• v.27 no.5
• /
• pp.337-343
• /
• 2014

This paper presents a continuum-based shape design sensitivity analysis(DSA) method for crack propagation problems using a reproducing kernel method(RKM), which facilitates the remeshing problem required for finite element analysis(FEA) and provides the higher order shape functions by increasing the continuity of the kernel functions. A linear elasticity is considered to obtain the required stress field around the crack tip for the evaluation of J-integral. The sensitivity of displacement field and stress intensity factor(SIF) with respect to shape design variables are derived using a material derivative approach. For efficient computation of design sensitivity, an adjoint variable method is employed tather than the direct differentiation method. Through numerical examples, The mesh-free and the DSA methods show excellent agreement with finite difference results. The DSA results are further extended to a shape optimization of crack propagation problems to control the propagation path.

• Journal of the Korean Society of Radiology
• /
• v.6 no.4
• /
• pp.291-298
• /
• 2012

Department of radiology implements the hospital-based clinical training to accept medical treatment techniques and to adapt experiences for students. However, it might cause negative effects to training education, leading to doubt about major and pressure about training as lots of students experience clinical treatment and complex stress in unfamiliar environment. Regarding this, pressure element that students can experience and diverse variables of training were compared and analyzed. With students in department of radiology for 6 colleges and universities, from September 15th to October 25th in 2011. The degree of stress for students in training was shown high in the fields of cost(3.06) and trainers(3.02). Value and ideal(2.94), role and experiment(2.93), training environment(2.74) and relationships among trainees(2.64) were followed in the order. Except expense regarding stress from clinical training, but in all factors, women showed higher pressure level than men(P<.05) and in stress range according to BEPSI-K, a meaningful difference was shown in fields of training environment, relationships among trainees and role and experiment(P<.01, P<.001, P<.05). Therefore, It has been confirmed that there is correlation between stress of students and satisfaction for clinical training with each other closely.

• Pediatric Gastroenterology, Hepatology & Nutrition
• /
• v.11 no.sup1
• /
• pp.102-108
• /
• 2008

More children today are overweight or obese than ever before. childhood obesity results from an imbalance between the amount of energy consumed and the amount of energy expended. Whether child want to lose weight or maintain a healthy weight, it's important to balance between the calories body takes in and uses. Obesity treatment programs for children and adolescents is to slow or halt weight gain so the child will grow into his or her body weight over a period of months to years. Fasting or extreme caloric restriction is not advisable for children. More physical activity is a key element in the prevention and treatment of obesity. Children can't change their exercise and eating habits by themselves. They need the help and support of their families and parents. Children and adolescents who are just beginning to be physically active should start out slowly and gradually build to higher levels in order to prevent the risk of injury or feel defeated from unrealistic goals. It is important that children and adolescents are encouraged to be physically active by doing things that interest them. FUN physical activities that kids choose to do on their own are often best. Kids need about 60 minutes of physical activity a day, but this does not have to happen all at once. Several short 10- or even 5-minute periods of activity throughout the day are just as good. FUN physical activities will help them establish an active lifestyle early on. Obese people need care not for a short period, but throughout their lives.

• Journal of Families and Better Life
• /
• v.28 no.1
• /
• pp.145-157
• /
• 2010

This is a study that explores the influence of self-differentiation and acculturation among married immigrant women on their feelings of marriage satisfaction by residential area. The aim was to verify the level of self-differentiation and acculturation that married immigrant women secure from multicultural marriage. To achieve this objective, the study widely distributed a questionnaire that targeted women who were participating in education and other services at health and family support centers, multi-cultural family support centers, general social welfare centers, immigrant women shelters, and Korean language classrooms which are located in Seoul, Gyeonggi, Chungcheong, Jeolla, and Gyeongsang. Data analysis involved frequency analysis, descriptive statistics, one-way-Anova, and multiple regression analysis. Based on the results of descriptive statistics, two factors, namely, (1)interpersonal-relation differentiation, a sub-scale of self-differentiation, and (2)marginalization, a sub-scale of acculturation, had the lowest average. In verifying its various hypotheses, the study achieved the following results. Firstly, among demographic characteristics, there was difference of the mean in the marriage period, average monthly income, the frequency of meetings with the married woman´s parents-in-law and her own parents, and the average cost of supporting the woman's parents-in-law and her own parents. Secondly, among demographic characteristics, the variable of influencing marriage satisfaction showed negative influence in the case of women dwelling in farming and fishing villages. This shows that women residing in cities whether small, medium or large have higher marriage satisfaction. Also, as a result of verifying whether self-differentiation has influence on marriage satisfaction, the element of interpersonal-relations differentiation had a negative influence on marriage satisfaction. Thirdly, as for influence of acculturation upon marriage satisfaction, the study showed that just integration, which is a sub-scale of acculturation had positive effect on marriage satisfaction. In other words, the study showed that the interpersonal-relation differentiation among the sub-scales of self-differentiation among married immigrant women had a negative influence, and that integration among the sub-scales in acculturation had a positive influence on marriage satisfaction. Based on these results, in order to increase interpersonal-relation differentiation, as well as marriage satisfaction among immigrant women, the study suggests the integration of the women's families with the nuclear and extended families in the communities where the women reside.

• Journal of the Korean Applied Science and Technology
• /
• v.30 no.1
• /
• pp.71-77
• /
• 2013

Aluminium powder as reductant in aluminothermy process needs a fine particle size under 200 mesh, but it is not easy economically to make that because of its high ductility and powder production cost. In order to reduce the production cost of fine aluminum powder as reductant of $Mn_3O_4$ waste dust, therefore, the properties of aluminium alloy powder were investigated. Aluminium alloy ingot containing large amount of manganese can be crushed easily because of its intermetallic compounds having brittle properties. The manganese is also main element in ferro-manganese. We can obtain economically Al-15%Mn alloy powder by mechanical comminution process. And the result of thermite reaction using Al-15% Mn alloy powder instead of pure Al powder showed the fact that can be obtained the ferro-manganese which have a high purity in case of using pure aluminium powder as reductant. The recovery of manganese from $Mn_3O_4$ waste dust with Al-15%Mn alloy powder was higher level of about 70% than about 65% in case of using aluminium powder, that is due to lower spatter loss.

• Journal of the Korean association of regional geographers
• /
• v.16 no.6
• /
• pp.689-705
• /
• 2010

The purpose of this study is to examine the geographical distribution and the clustering characteristics as an industrial cluster in order to provide alternative fundamental data for the preparation of the policies to facilitate the development of the Green Energy Industry. The main source of the data in this study is the outcome of a survey conducted to the firms and environment specialist from June 21st, 2010 to July 23rd, 2010. The Green Energy related companies in Daegyeong region are clustered around Pohang and Gumi, Gyeongbuk, and Dalseo District of Daegu Metropolitan City. The core element of the sustainability of the Green Energy Industry in the region is the inducement of the large-scale corporate presence in the region as well as the technical and geographical proximity. That is, the fact that there are sister companies established by the large scale corporate Daegyeong region as they have chosen this field for their new drive for growth. The major location factors are proximity, higher quality expectations from the local demands, technical availability, and competition with other companies of the same industry in the region, rather than the availability of the raw material. And the choke points for these companies are the financial support of R&D and the policy support of specialist training. The policy to facilitate the development of the industry in question in Daegyeong region, therefore, should shift from its previous focuses on infrastructure building and taxation benefits to financial supports for the technical research, human resource development in response to the needs of the companies. Also, programs to support the proficiency training for the already-hired work forces and development of new policies for the Green Energy Industry are needed to be introduced for the development of the Green Energy Industry in Daegyeong region.

• Economic and Environmental Geology
• /
• v.25 no.3
• /
• pp.317-336
• /
• 1992

The garden soils, main road dusts, residential road dusts, and playground soils/dusts of Seoul, Geumsan, Onsan, and Taebaek areas were analyzed in order to investigate the level of heavy metal pollution by urbanization and industrialization. The soil pH is in the range of 5.48~8.40 and was generally neutral. The color of soils and dusts is mainly Raw Umber to dark greyish Raw Umber. Some samples from Taebaek city, a coal mining area, showed a deep black color due to contamination by coal dusts. Major minerals of the dusts and soils are quartz, feldspars, and micas, reflecting the composition of the parent rocks. However, pyrite was found as a major mineral in the samples of industrial road dusts of Onsan, a smelting area, and resicential road dusts of Taebaek. Thus, the high level of heavy metals in mining and smelting areas can be explained with the sulfide minerals. The mode of occurences of heavy metals in Seoul, a comprehensive urbanized area, were related to the metallic pollutants and organic materials through observation by scanning eletron microscopy. In main road and residential road dusts of Onsan area, Cd, Zn, and Cu were extremely high. Some industrial road and residential road dusts of Seoul area showed high Cu, Zn, and Pb contents, wereas some garden soils and residential road dusts of Taebaek area were high in As content. In general, the heavy metal contents in dust samples were two to three times higher than those in soil samples. Main road dust samples were the most reflective from the discriminant analysis of multi-element data. Cadmium, Sb, and Se in Onsan area, As in Taebaek area, Pb and Te in Seoul area were most characteristic in discriminating the studied areas. Therefore, Cd in smelting areas, As in coal mining areas, and Pb in metropolitan areas can be suggested as the characteristic elements of each pollution pattern. The dispersion of heavy metal elements in urban areas tends to orignate in main roads and deposit in garden soils through the atmosphere and residential roads. The heavy metal contamination in Seoul is characteristic in areas with high population, factory, road, and traffic decsities. Heavy metal contents are high in the vicinity of smelters in Onsan area and are decayed to background levels from one kilometer away from the smelters.