• Journal of the Korean Geographical Society
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• v.39 no.5 s.104
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• pp.711-721
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• 2004

The aim of this study is to clarify whether frequency and/or severity of extreme climate events have changed significantly in Korea during recent years. Using the best available daily data, spatial and temporal aspects of ten climate change indicators are investigated on an annual and seasonal basis for the periods of 1954-1999. A systematic increase in the $90^{th}$ percentile of daily minimum temperatures at most of the analyzed areas has been observed. This increase is accompanied by a similar reduction in the number of frost days and a significant lengthening of the thermal growing season. Although the intra-annual extreme temperature range is based on only two observations, it provides a very robust and significant measure of declining extreme temperature variability. The five precipitation-related indicators show no distinct changing patterns for spatial and temporal distribution except for the regional series of maximum consecutive dry days. Interestingly, the regional series of consecutive dry days have increased significantly while the daily rainfall intensity index and the fraction of annual total precipitation due to events exceeding the $95^{th}$ percentile for 1901-1990 normals have insignificantly increased.

• Journal of Environmental Health Sciences
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• v.44 no.6
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• pp.556-562
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• 2018

Objectives: This study was conducted to investigate the boron concentrations in 30 slime products and estimate children's dermal exposure to boron. Methods: Thirty slime products from online and offline stores were purchased for boron analysis. The boron content of each slime sample was analyzed using ICP-OES. A nationwide survey was performed to determine use patterns of slimes by a home-visit survey of 10,000 children divided into three age groups: 0-2, 3-6, and 7-12 years. The dermal exposure to boron was calculated using an exposure algorithm for child slime users. Results: The proportion of the child population using slime was 45.8%, and the mean use frequency was $2.5{\pm}3.8$ per week (range: 0.08-35). Mean time spent playing with slime was $19.6{\pm}11.3min$ (range: 1-100). Twenty-five of the thirty slimes contained a boron concentration exceeding the EU limit for toys made with sticky material of 300 mg/kg. Dermal exposure ranged from $0.0008-13.78{\mu}g/kg/day$ with the maximum weight fractions of boron in the 30 products. The dermal exposure estimate was the highest in 7-12 years old group. Conclusion: Slime use among Korean children may cause high exposure to boron. Regulation is needed to minimize boron exposure from slime products.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.20 no.7
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• pp.651-657
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• 2010

Previous experimental results performed by many researchers for a couple of decades in South Korea have shown that an absorbing sheet inserted in a conventional floating slab system for thermal insulation or vibration absorption may amplify the vibration of the slab system at specific frequency ranges depending on the material properties of the sheet. The amplified vibration, consequently, results in the heavy weight floor impact noise exceeding the sound level limit for an apartment house, 50 dB. In this study, the amplification mechanism is examined through numerical analysis and a new slab system is proposed to reduce the amplification and control the noise. The new slab system consists of studs connecting the base slab and upper concrete finishing yielding the dramatically increased stiffness of the slab. The numerical simulation is performed to investigate the effect of the slab system with studs on the vibration and noise control. The results show that the performance of the slab is sensitive to the number and location of studs, and the heavy weight floor impact noise can be reduced up to 6~7 dB compared to the conventional slab system at the optimal stud location.

• Journal of the Korean Dietetic Association
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• v.13 no.2
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• pp.169-182
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• 2007

We investigated elementary school students' knowledge, behavior, experience and preference of education method related to food safety in order to provide basic information for food safety educational program. A survey study was conducted with 569, fourth and sixth grade students, from two schools in Seoul and Ulsan. Students were asked thirty-two questions regarding food safety knowledge, behavior and experiences as well as their attitude to food safety class and preference for teaching method. The data was analyzed for the frequency analysis, t-test, chi-square test, one-way ANOVA and Pearson correlation using the SPSS/Windows. Results indicated that 91.9 percent of the respondents did not know what unsanitary food is. 67 percent of the respondents did not know the proper method of hand washing. Although the students' level of knowledge and behavior associated with food safety was low, there was meaningful correlation(r =.184, p<.01) between knowledge and behavior. Surprisingly, students in higher grade did not demonstrate an exceeding food safety knowledge and behavior. More than 50 percent of the subjects did not have food safety education either at home or school. 60 percent of the respondents interested in food safety and the majority recognized that a food safety education is needed. Students want to learn about unsanitary food(34.1%), foodborne illness(29.7%), food selection and storage method(21.3%), and personal hygiene(11.2%) through game, role play, and practice in real situation. These results suggest that development of food safety education program is needed through the elementary school year and the education program must include fun activities in which students can participate.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.27 no.12
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• pp.1097-1104
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• 2016

The infrared camera is difficult to satisfy the RE-102 specification of Mil-Std-461. Especially, in the case of UAV electronics, shielded cable is not used, so it is difficult to meet the electromagnetic compatibility standard. In the RE-102 test of the IR camera for UAV, radiated noise exceeding 30 dBuV/m was observed in the range of 50 MHz to 200 MHz. As a result of pcb em scan, peak noise which caused by the harmonic frequency of the digital control signal clock was observed. Radiated noise was reduced by up to 22.9 dBuV/m by applying the spread spectrum clock generator(SSCG) with 3 % down spreading method to the camera control clock.

• Korean Journal of Community Nutrition
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• v.5 no.3
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• pp.502-512
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• 2000

A survey was conducted on 222 students in two elementary schools in rural areas, one was a rural small city and the other was in the countryside. By measuring their skin-foldness in 4 spots by caliper, the body fatness of 5 grades(BFGr) of the subjects was resulted as follows ; 28.0% of boys and 6.7% of girls were classified as obese the and 34.1% of boys and 31.1% of girls as overweight. Comparing by region, children in the small city seemed to be fatter than the ones in the countryside(21.7% vs. 17.2% as obesity). Comparing by gender, boys were fatter than girls(28.0% vs. 6.7% as obesity). When recategorizing body fatness from 5 grades(BFGr) into 3 groups(BFGp) as overweight group(obesity+overweight), normal and underweight group(underweight+severe-underweight), we observed no significant difference in childrens dietary habits and food intake frequencies by BFGp. Overweight and underweight groups enjoyed snacking before dinner more frequently than the normal group(42.1-59.3% vs. 31.5%). The subjects showed poor nutrition knowledge score with relatively high attitude score about weight control and dietary behavior score was a little lower than the attitude score. Nutrition education programs, like camps, should stress on childrens nutrition knowledge. BFGp related to obesity attitude positive, a very low level and the latter related to diet, exercise and fasting attitudes at positive levels. Therefore overweight children seemed to be motivated easily. Also the higher the in exercise-value score, the more increased was shown in exercise attitude at positive, very low level. Emphasizing exercise-value in camp programs might make childrens exercise attitude more positive. As strategies for a rural obesity camp program are being developed by obese and non-obese children. The camp would be held over summer vacation for 3 days(2 nights) at the participants expence not exceeding 50,000 won. Contents of the program cover nutrition knowledge, and exercise-value as well as cooking lessons, exercise practice, and self-esteem enhencement.

• The Journal of the Korea Contents Association
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• v.21 no.12
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• pp.132-139
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• 2021

This corpus-driven research expounded the compilation of the most frequently occurring academic words in the domain of syntax and compared the extracted wordlist with Academic Word List(AWL) of Coxhead(2000) and General Service List(GSL) of West(1953) to examine their distribution and coverage within the syntax corpus. A specialized 546,074 token corpus, composed of widely used must-read syntax textbooks for English education majors, was loaded into and analyzed with AntWordProfiler 1.4.1. Under the parameter of lexical frequency, the analysis identified 288(50.5%) AWL word forms, appeared 16 times or more, as well as 218(38.2%) AWL items, occurred not exceeding 15 times. The analysis also indicated that the coverage of AWL and GSL accounted for 9.19% and 78.92% respectively and the combination of GSL and AWL amounted to 88.11% of all tokens. Given that AWL can be instrumental in serving broad disciplinary needs, this study highlighted the necessity to compile the domain-specific AWL as a lexical repertoire to promote academic literacy and competence.

• Korean Journal of Microbiology
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• v.30 no.3
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• pp.154-159
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• 1992

Forniation ancl ~regcncration oi' conitlial pro1oplast of Pc, ti~i.rlli~in~~~ c~rr~~culo.hryupmel.- - czllulolytic Ihngus. were examined. By using Novozyme 134(1'!/0 w/c) as a cell wall lytic enzyme. the highest yield of protopl;~sts exceeding 501%, war obtained from the qwollen conidiosporcs preincubatrd in the minimal medium containing 2-tleoxy-D-glucose(2-UC;. 75 pglml) for 10-11 11. No protoplast were obtained horn dormant spores. The regeneration frequency of the protoplasts was 49.2'!11. which was higher than that of mycclium originated protoplast (4.6-17.X1X, . in 0.6 M MgS04. pH 5.6). 'l'lie best osmotic stahilizcr ror the isoaltion and regcueration of thc protoplast was 0.6 M iimmonium sulfatc and 0.6 M magnesiuni sulfhte. respectively. 'I'lie process of the protoplast isolaiton l'ro~n swollen cnnirliospore ancl regeneration ha\, ing two pattcrns from protoplast were obsen'etl through light microscope.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.23 no.7
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• pp.1807-1816
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• 1998

The interference probability between non-geostationary-statellite orbit mobile station is calculated when the two systems are sharing the frquency band below 1 GHz. The probability density function of a mobile earth station(MES) is calculated based on the established propagation model and then, a probability of exceeding the threshold level is derived. By changing the average transimission per unit time of total MSS(Moblie satellite service) area and the ratio of transmitters for specific area, we obtain the average transmission per unit time for the area under consideration. From this, the exceedance probability for the given pfd threshold level is evaluated. The exceedance probability is increased as the average transmissio per unit time and ratio become larger. Also the effect of filter isolation between channels is accounted for.

• Microbiology and Biotechnology Letters
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• v.16 no.2
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• pp.156-162
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• 1988

Optimal conditions for the formation and regeneration of protoplasts of the cellulolytic fungus Penicillium verruculosum were investigated. Among the various commercial cell wall lytic enzymes tested, 0.5%(w/ v) Novozym 234 was the most effective for protoplast formation. The highest yield of protoplast exceeding 4.5$\times$10$^6$/m$\ell$ obtained when 400mg of 20 hr-old mycelia was incubated with 0.5%(w/v) Novozym 234 at 3$0^{\circ}C$ for 1 hr. The best osmotic stabilizer for the isolation and re-generation of protoplasts was 0.7M sorbital (pH 5.6) and 0.6M MgSO$_4$(pH 5.6), respectively. When 0.6M MgSO$_4$was added as osmotic stabilizer to the complete medium, the maximum regeneration frequency obtained was 4.6-27.8%. Micromorphological change of giant protoplasts into hyphae was observed during incubation in the regeneration liquid medium.