• Transactions of the Korean hydrogen and new energy society
• /
• v.35 no.2
• /
• pp.121-128
• /
• 2024

In this study, a dynamic simulation model of a heavy-duty truck, equipped with a fuel cell power-train, has been developed and the dynamic behavior of the fuel cell stack has bee investigated using. Output change simulations were performed according to several drive cycle load change of a fuel cell truck. Mathworks' Simulink and Simscape program were used to develop the model. The model is comprised of fuel cell power train, power converter system and truck vehicle part. The vehicle runs at targeted speed of the truck, which is set as the load of the system. The dynamic behavior of the fuel cell stack according to the weight difference were analyzed, and based on this, the dynamic characteristics of the fuel cell output power and battery state with simple load was analyzed.

• Parasites, Hosts and Diseases
• /
• v.55 no.6
• /
• pp.607-611
• /
• 2017

Primary maternal infection with toxoplasmosis during pregnancy is frequently associated with transplacental transmission of the parasite to the fetus. This study was conducted to test the utility of PCR assay to detect recent infections with Toxoplasma in aborted women at various gestational ages who referred to Obstetrics and Gynecology Department of Alavi Hospital in Ardabil during 2014 and 2016. Two hundred women with a history of single or repeated abortion were investigated in this study. Blood samples were tested for specific anti-Toxoplasma IgM and IgG antibodies by ELISA. According to the results, 53.5% of the women under study were positive for anti-Toxoplasma antibodies: 4.0% of them had IgM, 43.0% had IgG, and 6.5% had both IgM and IgG. Subsequently, Nested-PCR analysis was used to detect T. gondii DNA in the placenta of subjects. In 10.5% of the women, the results were positive for 529 bp element of T. gondii. Among them, 5 (23.8%) cases were IgM positive, 1 (4.8%) case was IgG positive, and 11 (52.4%) were both IgM and IgG positive. In 4 (19.0%) patients, none of the antibodies were found to be positive. In total, 16 patients had positive results in both ELISA and PCR methods, and 174 cases had negative results for new infection. The findings of this study revealed that T. gondii might be one of the significant factors leading to abortion, and that the analysis of placenta can be important in order to achieve increased detection sensitivity.

• Korean Journal of Soil Science and Fertilizer
• /
• v.47 no.1
• /
• pp.16-22
• /
• 2014

This study was conducted to determine the changes in soil chemical properties and the growth of seedling according to the different dredged soil improving methods at slope of Saemangeum sea dike. Undersea dredged soil was improved by five different methods. Seedlings of Ulmus davidiana var. japonica, Chionanthus retusa, Celtis sinensis, and Pinus thunbergii were planted after 9 month of experience site installation, then soil pH, NaCl concentration in soil, soil organic matter (SOM), and survival rate and height of seedling was measured. Initial soil pH was highest in the control plot but it decreased to the similar level with other soil improving plots after 35 months. There were no differences in NaCl concentration between the control and soil improving plots, and it showed decreasing tendency during the study period. In the control plot, initial SOM was lowest among that of other plots during the study period. The survival rate of 36 months after planting of P. thunbergii was highest among the species. The gap of the tree growth of P. thunbergii between the control plot and the soil improving plots was small, however, other species showed relatively higher tree height in the soil improving plots than the control plots. Creation forest with P. thunbergii might be a cost effective afforestation in coastal reclaimed land since it rarely needs additional improvement of dredged soil.

• Journal of the Korean Society of Environmental Restoration Technology
• /
• v.18 no.1
• /
• pp.13-23
• /
• 2015

This study was performed to compare the effects of different drainage layers on tree growth at the exposed sites of Saemangeum sea dike. 4 types of drainage layers including control(dredged soil), specially prepared bark, gravel, and wood chip were set in 150~165cm depth of soil. Pinus thunbergii and Celtis sinensis were planted after 9 months of soil treatment. Electrical conductivity(EC) of soil in all treated plots were decreased under $4dS{\cdot}m^{-1}$, and NaCl(%) was decreased under 0.05% after 1 year from soil treatment. Soil moisture at the 120cm depth of the bark treated plot was higher than that of the 180cm soil depth, below the drainage layer. It is considered that vertical mobility of water was inhibited. Organic matter(OM) at the 120cm soil depth increased at bark and wood chip treated plots. Survival rates after 4 years of P. thunbergii and C. sinensis were 100% in all treatments. The height of P. thunbergii was not significantly different among the treatments while the height of C. sinensis was significantly different among the treatments and it was highest at the bark treated plot.

• Korean Journal of Environmental Agriculture
• /
• v.33 no.1
• /
• pp.1-8
• /
• 2014

BACKGROUND: Recent studies using many amendments for heavy metal stabilization in soil were conducted in order to find out new materials. But, the studies accounting for the use of appropriate amendments considering soil pH remain incomplete. The aim of this study was to investigate the effects of initial soil pH on the efficiency of various amendments. METHODS AND RESULTS: Acid soil and alkali soil contaminated with heavy metals were collected from the agricultural soils affected by the abandoned mine sites nearby. Three different types of amendments were selected with hypothesis being different in stabilization mechanisms; organic matter, lime stone and iron, and added with different combination. For determining the changes in the extractable heavy metals, water soluble, Mehlich-3, Toxicity Characteristic Leaching Procedure, Simple Bioavailability Extraction Test method were applied as chemical assessments for metal stabilization. For biological assessments, soil respiration and root elongation of bok choy (Brassica campestris ssp. Chinensis Jusl.) were determined. CONCLUSION: It was revealed that lime stone reduced heavy metal mobility in acid soil by increasing soil pH and iron was good at stabilizing heavy metals by supplying adsorption sites in alkali soil. Organic matter was a good source in terms of supplying nutrients, but it was concerning when accounting for increasing metal availability.

• Korean Journal of Agricultural Science
• /
• v.51 no.1
• /
• pp.25-39
• /
• 2024

This study aimed to determine a method for restoring grasslands to forests in mountainous areas. The study was conducted in an area damaged by trampling due to construction activity and herding. Additionally, there were concerns of hindered tree growth due to the alpine region climate, characterized by the low temperatures, drying, and strong winds. Therefore, forest restoration treatments such as tillage, furrow, and shading were performed to improve growth conditions. From July 2021 to April 2023, soil temperature and moisture were monitored for each treatment plot, and changes in the initial growth and survival rate of Abies holophylla were investigated. Both soil temperature and soil moisture showed significantly higher values during the four seasons in the grassland-furrow treatment plot (p < 0.05). Compared to the grassland-control plot, the average soil temperature in winter was as high as 1.1℃, and the soil moisture in summer was as high as 20.3%. Additionally, the survival rate and relative growth rate were the largest in the grassland-furrow treatment plot. The survival rate was 87.5%, the relative growth rate in terms of height was 0.013, and the relative growth rate in terms of diameter at root collar was 0.023, indicating that furrow treatment had a positive effect on the initial survival and growth of seedlings. These results suggest that furrow treatment may be an appropriate restoration method when implementing forest restoration projects in areas where tree growth is challenged.

• The Journal of Korean Philosophical History
• /
• no.54
• /
• pp.9-42
• /
• 2017

It is as necessary as ever to make constant efforts to overcome the regional strife between the eastern and western parts of Korea and come to a mutual understanding. To achieve this, we must endeavor to correct Korean people's distorted understanding of the history of Korean philosophical thoughts. Ordinary Koreans commonly and mistakenly associate the academic circles of Korean Neo-Confucianism with certain regions by which to divide them into Giho School and Yongnam School and then go as far as associating the schools and parties and pegging them 'Namin'(南人) to refer to as the followers of Yongnam School and 'Seoin'(西人) as the followers of Giho School. Such false notions must be corrected. During the reign of King Seonjo, political factions of Joseon were split into Yongnam and Giho, or East and West. At the time, the two cardinal directions East and West were only used to refer to the eastern and western parts of Seoul, and not Yeongnam(East) and Giho(West) of the Korean Peninsula. Therefore, the factional split at the time has nothing to do with regional cleavages. In fact, a majority of scholars representing Korean Neo-Confucianism maintained a friendly relationship regardless of the school, party, and region. Many leading scholars in the middle of the Joseon Dynasty namely Jo Sik(曺植)/Seong Woon(成運), Lee Hwang(李滉)/Ki DeaSeung(奇大升), Lee Hwang(李滉)/Lee Yi(李珥), Noh Susin (盧守愼)/Lee Yi, the ones in the late Joseon Dynasty -Jeong Gyeong Se(鄭經 世)/Kim Jang-Saeng(金長生), Jeong Gyeong Se(鄭經世)/Song Joon Gil(宋浚吉), and also those at the end of the Joseon Dynasty such as Kwak JongSeok(郭鍾錫) and Kim BokHan(金福漢) deeply respected each other and had a close friendship rooted in their academic commitment. The friendship between the leaders of Giho and Yongnam is a testimony to the high level of their character, academic achievement, and intellect. More than ever, such intangible intellectual and cultural resources drawn from Korean tradition must be utilized to the fullest. From this point on, we need to further promote the friendship and mutual understanding the scholars of Yongnam(Gyeongsang-do), Gyeonggi, Honam (Jeolla-do), and Hoseo(Chungcheong-do) enjoyed, and use them as a cognitive basis for harmony between the eastern and western parts of the country. These invaluable assets can be specifically used in the promotion of exchange between the local autonomous governments of the regions where above-mentioned scholars built an amicable relationship, joint commemorative events, exchange between families of the scholars of both regions, opening of special exhibitions dedicated to the harmony between Yongnam and Giho at museums in the two regions, co-organization of local festivals, joint operation of culture programs, and relationship and exchange between the 'seowons' in both regions, through which to promote the long history of exchange between the scholars of the past and utilize it in joint projects.

• Korean Journal of Soil Science and Fertilizer
• /
• v.45 no.6
• /
• pp.961-967
• /
• 2012

There have been many studies about efficiency of amendments for heavy metal stabilization through chemical assessment. The objective of this study was to evaluate the efficiency of several soil amendments (lime, agric-lime, dolomite, steel slag, fly ash and acid mine drainage sludge) on heavy metals stabilization through not only chemical but also biological assessments (phytotoxicity test) in abandoned mining area soil. In order to achieve the goal, we conducted preliminary screening experiment targeting 12 types of crop plants such as radish, young radish, chinese cabbage, winter grown cabbage, cabbage, bok choy, chicory, crown daisy, carrot, chives, spinach, and spring onion. The results of inhibition rates of early plant growth in metal-contaminated soil against non-contaminated soil and the correlations between inhibitions items showed that the bok choy was appropriate specie with respect to confirm the effect of several amendments. Several amendment treatments on contaminated soil brought about the changes in the root and shoot elongation of bok choy after 1 week. Agric-lime, dolomite and steel slag treatments showed the great efficiency of reducing on mobility of heavy metals using chemical assessment. But in contrary, these treatments resulted in the reduction of root and shoot elongation and only AMD sludge increased that of elongation, significantly. When considering both chemical and biological assessments, AMD sludge could be recommended the compatible amendment for target contaminated soil. In conclusion, biological assessment was also important aspect of decision of successful soil remediation.

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.14 no.8
• /
• pp.3777-3785
• /
• 2013

This study aimed to find out adolescents' media literacy in terms of reading, writing, and enjoying media or messages. For the purpose, we analyzed the data garnered from 1,036 students enrolled in 5 middle and 5 high schools, respectively. The analyses of the data are summarized as follows: First, mobile phone was most widely used among others, followed by TV, the Internet, mp3 player, computer or video game, radio, a video or DVD in the order. Second, a gender effect was significant in terms of the variety of activities with the Internet, mobile, and SNS: boys were more active in the use of the Internet while girls carried out more activities with a mobile phone and SNS media. Third, high school students showed more critical attitude towards information on the Website than did the middle school students. Fourth, Girls than boys, and high schoolers than middle schoolers, tended to be more active in the production of contents, self-expression, as well as participating in social and political issues online. Fifth, for the enjoyment experiences, time spent for games took up the most of the students' leisure activities, followed by watching TV and the use of the Internet. The findings of the study were discussed in light of media convergence, with implications for developing media literacy education for the youth.

• The Journal of the Korea Contents Association
• /
• v.14 no.10
• /
• pp.416-428
• /
• 2014

This study aimed to identify middle school students' perceptions and practices of handwriting, and factors affecting their attitudes towards handwriting. Data were collected by means of a survey targeting 346 students enrolled in 9 middle schools(Male=172, Female=172, Unknown=2, M=13.5 years old, SD= .94). Interviews, too, were conducted with 12 students in order to identify the students' perceptions of handwriting. The analyses of both survey and interview data revealed the following: (1) the majority of the interviewee students believed that handwriting is useful for memory and summarization so as to get a better school grade, including performance evaluations; (2) Many of the interviewee students were unsatisfied with their handwriting skills, giving higher scores to their peers' handwriting; (3) 45.7% of the students reported that mother was the one who taught them how to write for the first time; and 49.7% of them had no learning experience of taking notes; (4) Girls than boys and 1st graders than 2 or 3 graders showed more positive attitude towards handwriting; and (5) A multiple regression analysis showed that all the variables entered in the regression model, including sex, grade, affective attitude toward hands-on activities, physical abilities, time spent using a computer, and perceptions of Korean characters, had significant impacts on the students' attitudes towards handwriting.