• Journal of Korean language education
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• v.29 no.4
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• pp.65-92
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• 2018

This study explored how a particular social media can be used to supplement elementary-level Korean language course in the US public university. The researchers administered a survey measuring students' patterns and habits of social media use. Based on the survey results, researchers designed six different types of learning materials and uploaded them regularly to Instagram throughout the semester. At the end of the semester, a survey was conducted to find out students' satisfactory level. From the 44 students' responses, the study found out that using Instagram 1) is more accessible to students than any other learning management system, 2) is fun and students are willing to participate, 3) increased the target language exposure and authentic language use, 4) increased interaction between teachers, students and even other native speakers, and 5) is helpful to improve listening and other language skills. The study closes with the suggestion for further experimental studies.

• The Korean Journal of Mycology
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• v.47 no.4
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• pp.385-392
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• 2019

Currently, plastic bags are being used for sawdust cultivation of shiitake mushroom. However, due to serious environmental problems caused by the use of plastic bags, we studied the efficacy of bottle cultivation method to replace the sawdust bag method. Small detachable plastic bottles (400 g capacity) filled with Quercus spp. sawdust and wheat bran (4:1 w/w) media were incubated for 80 and 120 days. The weight loss (%) of the media was higher for the NIFoS 2464 strain at an approximate light intensity of 300 Lux than light intensity of 500 Lux; the light intensity was associated with the loss of sawdust medium-weight during the cultivation period. The highest yield was observed when the strain was cultivated for 80 days under dark conditions, 40 days under 500 Lux light, and air circulation fan speed of 30 rpm. When incubated for 120 days, mushroom yield in the bottle media was higher at 40 days of light exposure than 20 days of light exposure. In the bottle media incubated for 80 days under dark conditions, the mushrooms fruited due to repetitive water spraying on the top of the media and light stimulation during the fruiting period. The media could be separated from the bottles because the media shrank after the first harvest. These separated plastic bottles could be re-used for mushroom cultivation, thereby reducing the amount of plastic waste.

• Journal of the Optical Society of Korea
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• v.19 no.1
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• pp.29-37
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• 2015

The wavefront printer records a volume-reflection hologram as a two-dimensional array of elemental holograms from computer-generated holograms (CGHs) displayed on a spatial light modulator (SLM). The wavefront coming from the object is extracted by filtering in the spatial-frequency domain. This paper presents a method to improve color reproduction in a wavefront printer with spatial division of exposures at primary colors, by adaptive partitioning of the SLM in accordance with the color content encoded in the input CGHs, and by the controllable change of exposure times for the recording of primary colors. The method is verified with a color wavefront printer with demagnification of the object beam. The quality of reconstruction achieved by the proposed method proves its efficiency in eliminating the stripe artifacts that are superimposed on reconstructed images in conventional mosaic recording.

• Journal of Korea Society of Digital Industry and Information Management
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• v.15 no.4
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• pp.213-225
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• 2019

Privacy paradox is a paradoxical behavior that provides personal information even though you are concerned about privacy. Social media users are also often concerned about their personal information exposure. It is even reluctant to describe personal information in profile. However, some users describe their personal information in detail on their profile, provide it freely when others request it, or post their own personal information. The survey was conducted using Google Docs centered on Facebook users. Structural equation model analysis was used for hypothesis testing. As an independent variable, we use personal information infringement experiences. As a mediator, we use privacy indifference, privacy concern, and the relationship with the act of providing personal information. Social media users have become increasingly aware of the fact that they can not distinguish between the real world and online world by strengthening their image and enhancing their image in the process of strengthening ties, sharing lots of information and enjoying themselves through various relationships. Therefore, despite the high degree of privacy indifference and high degree of privacy concern, the phenomenon of privacy paradox is also present in social media.

• Journal of Digital Convergence
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• v.11 no.9
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• pp.95-102
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• 2013

The purpose of this study is to explain why the social phenomenon of the wisdom of the crowd does not empirically apply. The motivation of this study is to explain the Korean social issue: the Tablo incident. In this study, 50 university students participated in the experiments to assess the impact of social media on the wisdom of crowds effect. We find evidence of a positive wisdom of crowds effect, when respondents are less exposed to media. In contrast, the collective information seems to be negatively distorted by respondents highly exposed to media. This research has strong implication for education policy and theories of social interaction.

• Proceedings of the SAREK Conference
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• 2006.06a
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• pp.95-98
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• 2006

Filtration by fibrous filter is one of the Principle methods used for removing pollutant particles in the liquid. Because of the increasing need to protect both human health and valuable devices from exposure to fine particles, filtration has become more important. Filters have been developed with modified surface charge characteristics to capture and adsorb particles by electrokinetic interaction between the filter surface and particles contained in water. The main purposes of this study are to develop and evaluate the performance evaluation of the apparatus for making a positively charged porous filter media and to analyze the surface characteristics of the filter media for capturing negavitely charged contaminants mainly bacteria and virus from water. The experimental apparatus consists of a mixing tank, a vacuum pumping system, a injection nozzle, a roller press and a controller. The filter media is composed of glass fiber(50-750 nm), cellulose($10-20{\mu}m$) and colloidal charge modifier. The characteristics of filter media is analyzed by SEM(Scanning Electron Microscopy), AFM(Atomic Force Microscopy) and quantified by measuring the zeta potential values.

• Journal of Korean Public Health Nursing
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• v.16 no.1
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• pp.45-63
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• 2002

The purpose of this study is to understand the current status of high school students' exposure to pornographic materials as well as to provide basic data to develop sex education programs. This study was conducted through a self-administered questionnaire survey of 774 students of six high schools in Seoul, three boys' and three girls' respectively, from August 22 to August 25, 2000. This study shows that high school students' exposure to pornographic materials such as CD-ROMs, internet, video tapes and adult movies has become very serious. The results of this study are as follows. 1. Among the students surveyed, $23.5\%$ of them currently has opposite-sex friends, while $42.2\%$ used to have and $34.2\%$ has never had opposite-sex friends. 2. $55.3\%$ of the students pick up their sexual knowledge from their friends, followed by mass media $(47.5\%),\;school (21.1\%),\;adult\; magazines (17.1\%)\;, internet (14.1\%)$, pornography visual $materials (11.5\%),\; sexual\; books (3.6\%)$ and pornography printed $materials (2.4\%).$ 3. Regarding the frequency of sexual education taken in school, $54.2\%$ of the students answered 'often', while $37.6\%$ answered 'almost none', 'several times' $(4.4\%)$, 'never' $(2.9\%)$ and 'frequently' $(0.9\%)$, respectively. Regarding sexual education at home, $42.2\%$ answered 'almost none', followed by 'never' $(36.3\%)$, 'often' $(16.3\%)$, 'several times' $(3.3\%)$ and 'frequently' $(1.8\%)$, respectively. 4. $68.2\%$ of the students have been exposed to adult movies, followed by pornography videos $(60.1\%)$, internet chatting $(50.2\%)$ and pornography computer diskettes $(38.0\%)$. 5. The degree of exposure to pornographic materials of boy students is much higher than that of girl students. 6. It appears that there is an interrelation between the kind of schools and the degree of the students' exposure to pornographic materials. 7. The higher the students' grade is. the more they have been exposed to pornographic materials. 8. It shows that there is an interrelation between the students' academic performance and the degree of their exposure to pornographic materials. 9. There is also an interrelation between the amount of students' pocket money and the degree of their exposure to pornographic materials. 10. There is an interrelation between the degree of their adaptation to school life and the degree of their exposure to pornographic materials. 11. It appears that there is an interrelation between their parents' relations with them and the degree of the students' exposure to pornographic materials. 12. There is a significant difference in the degree of their exposure to pornographic materials in accordance with their residential area. 13. There is also a significant difference in the degree of their exposure to pornographic materials in accordance with the average income of their families. 14. There is also a significant difference in the degree of their exposure to pornographic materials in accordance with the mean sexual education at home.

• Journal of Environmental Science International
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• v.13 no.7
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• pp.627-635
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• 2004

Evaluated were household THMs exposure associated with the use of municipal tap water treated with chlorine and with ozone-chlorine. The current study measured the THMs concentrations in the tap water and indoor and outdoor air in the two types of household, along with an estimation of THMs exposure from water ingestion, showering, and the inhalation of indoor air. Chloroform was the most abundant THMs in all three media, yet no bromoform was detected in any sample. Contrary to previous findings, the fall water THMs concentrations exhibited no significant difference between the chlorine and ozone-chlorine treated water. However, the spring median chloroform concentration in the tap water treated with chlorine (17.6 ppb) was 1.3 times higher than that in the tap water treated with ozone-chlorine (13.4 ppb). It is suggested that the effects of the water parameters should be considered when evaluating the advantage of ozone-chlorine disinfection for THMs formation over chlorine disinfection. The indoor air THMs concentration trend was also consistent with the water concentration trend, yet the outdoor air THMs concentrations did not differ significantly between the two types of household. The indoor to outdoor air concentration ratios were comparable with previous studies. The THMs exposure estimates from water ingestion, showering, and the inhalation of indoor air suggested that, for the residents living in the surveyed households, their exposure to THMs in the home was mostly associated with their household water use, rather than the indoor air. The THMs exposure estimates from tap water ingestion were similar to those from showering.

• Journal of Embryo Transfer
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• v.12 no.2
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• pp.161-169
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• 1997

This study was conducted to compare the insemination time of bovine oocytes and determine the effects of glucose(1.5 mM) on the development of bovine embryos at early cleavage stage. Oocytes were matured for 24 h, followed by exposure to sperm and cultured in modified Tyrode's media drops or with bovine oviduct epithelial cell monolayer prepared in TCM199(BOECM). Insemination time and culture system were varied in each experiment. In experiment 1, to investigate the developmental capacity of bovine embryos after different time of exposure to sperm, bovine ova and sperm were co-incubated for 18, 30 or 54 h, respectively. The development to blastocysts of 30 and 54 h insemination groups were significantly higher(P<0.05) than 18 h group, and in case of blastocysts of cleaved embryos, 30 h group were significantly higher(P<0.05) than other groups. In experiment 2, we investigated the effect of glucose on early bovine embryos. After 18 h insemination, in vitro fertilized oocytes were separated following 3 groups ; G+0, C+24 and C+48. Oocytes of G+0 group were cultured in glucose added Tyrode's medium after fertilization, oocytes in C+24 and C+48 groups were cultured in glucose free Tyrode's medium after fertilization. After 24 h culture, G+24 group was moved to glucose added medium. All oocytes of 3 groups were moved to BOECM after 48 h culture. The rates of cleavage and development to blastocysts in G+0 group were significantly lower than other groups. In experiment 3, we determined the effects of glucose exposure from 8 to 20 h after insemination on the cleavage and development of oocytes. The oocytes in glucose added group had high capacity of cleavage and further development. This study shows that in bovine oocytes, the optimal exposure to sperm is 30 h and glucose exposure to bovine one-cell embryos is detrimental to their first cleavage and further development in vitro but there has no evidence of detrimental effect of glucose(1.5 mM) exposure to bovine embryos over the two-cell stage in vitro.

• Asian Pacific Journal of Cancer Prevention
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• v.17 no.1
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• pp.139-145
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• 2016

Environmental tobacco smoke (ETS) is a major public health problem for all ages. Despite the high prevalence of smoking among the Saudi population, there is limited information about levels of urinary cotinine in Saudi children exposed to SHS. The aim of the study was to assess the exposure of schoolchildren to ETS, and measure their urinary cotinine levels. Multistage cluster sampling was carried out, where schoolchildren from 4 schools were randomly chosen from primary schools in Taif city. A questionnaire including questions on SHS exposure and smoking rules in the residence were sent to students parents/guardians. Urine samples were taken and analyzed for total cotinine using chemiluminescent immunoassay. Of the studied children, 38.4% had a smoking father, 61.8%, 41.2% and 49.3% of them were exposed to ETS indoors, outdoors and both indoors and outdoors respectively. The mean urinary cotinine was significantly higher among children exposed to ETS compared to unexposed children. Urinary cotinine levels in children with both indoor and outdoor exposure was significantly higher compared with its level in children with single exposure. A significant positive correlation was found between urinary cotinine concentrations and the number of cigarette packs smoked by parents, and the number of smokers in the residence. The mean urinary cotinine level was significantly higher in children who reported no smoking rules at the residence.. The study revealed a high exposure of Saudi children to ETS. An antismoking media awareness campaign on the harmful effects of ETS should be carried out, in addition to family counseling programs targeted to parents to protect their children from ETS.