• Korea-Australia Rheology Journal
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• v.19 no.4
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• pp.191-199
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• 2007

Precision injection molding process is of great importance since precision optical products such as CD, DVD and various lens are manufactured by those process. In such products, birefringence affects the optical performance while residual stress that determines the geometric precision level. Therefore, it is needed to study residual stress and birefringence that affect deformation and optical quality, respectively in precision optical product. In the present study, we tried to predict residual stress, final shrinkage and birefringence in injection molded parts in a systematic way, and compared numerical results with the corresponding experimental data. Residual stress and birefringence can be divided into two parts, namely flow induced and thermally induced portions. Flow induced birefringence is dominant during the flow, whereas thermally induced stress is much higher than flow induced one when amorphous polymer undergoes rapid cooling across the glass transition region. A numerical system that is able to predict birefringence, residual stress and final shrinkage in injection molding process has been developed using hybrid finite element-difference method for a general three dimensional thin part geometry. The present modeling attempts to integrate the analysis of the entire process consistently by assuming polymeric materials as nonlinear viscoelastic fluids above a no-flow temperature and as linear viscoelastic solids below the no-flow temperature, while calculating residual stress, shrinkage and birefringence accordingly. Thus, for flow induced ones, the Leonov model and stress-optical law are adopted, while the linear viscoelastic model, photoviscoelastic model and free volume theory taking into account the density relaxation phenomena are employed to predict thermally induced ones. Special cares are taken of the modeling of the lateral boundary condition which can consider product geometry, histories of pressure and residual stress. Deformations at and after ejection have been considered using thin shell viscoelastic finite element method. There were good correspondences between numerical results and experimental data if final shrinkage, residual stress and birefringence were compared.

• Korean Journal of Veterinary Research
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• v.43 no.3
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• pp.393-398
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• 2003

Simple and rapid sample preparation method for trace elements in foods of animal origin using ultra high pressure microwave digestion system (UHP/MDS) and inductively coupled plasma atomic emission spectrometer (ICP/AES) were developed. 1. For the digestion of sample using UHP-MDS, 20% nitric acid (v/v) was the most suitable solvent for the determination of trace elements in foods of animal origin. 2. The optimal digestion conditions for UHP-MDS were as follows: final temperature $180^{\circ}C$, final pressure 400 PSI, and magnetic power 900 W in the solid sample. For the liquid sample final temperature $170^{\circ}C$, final pressure 300 PSI and magnetic power 700 W were optimal conditions. 3. As result of interlaboratory test, the average recovery rate of the for solid sample were 88.3~99.1% for As, 82.4~93.3% for Cd, 89.2~101.2% for Hg and 86.5~93.8% for Pb, respectively. In liquid sample, it were 87.0~96.8% for As, 80.9~96.6% for Cd, 87.5~91.2% for Hg and 91.4~95.5% for Pb, respectively. 4. The average coefficient variation rate were 3.3~15.9% for solid sample and 2.9~10.8% for liquid sample.

• Journal of the Korean Society of Safety
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• v.14 no.2
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• pp.62-69
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• 1999

The quantitative risk assessment and consequence analysis by accident scenario in the process of EPS(Expendable Poly Stylene) reaction process are conducted. And the decision making process is studied followed by selecting various alternatives to safety management and facility improvement. The result are as follows; 1) The object of decision making through comprehensive risk assessment are the scenario which can cause four major accident, which are made by process analysis, work analysis and hazard identification. 2) Frequency analysis of ETA, FTA, HRA and consequence analysis of accident to each have been conducted. The each frequency values are yielded $9.2{\times}10_{-5}/yr$ to scenarios $1, 8.2{\times}10^{-4}/yr$ to scenario 2, $4.5{\times}10^{-6}/yr$ scenario 3 and $1.8{\times}10^{-7}/yr$ to scenario 4. The each scenarios have been conducted consequence analysis. 3) The calculated values have been obtained 4.00 to scenario 1, 3.25 to scenario 2, 2.43 to scenario 3 and 1.34 to scenario 4, as the weight value had been applied to the quantitative and normalized criteria of all components. As a risk criteria, scenario 1 have been selected, which is the most dangerous scenario as a result of ranking the scenario. 4) According to the importance of FTA and contribute to scenario 1, the cost-benefit values are yielded $8.05\times10^5[￦/yr]$ to final alternative(Al), $1.55{\times}10^5[￦/yr]$ to final alternative(A2) and $2.32{\times}10^5[￦/yr]$ to final alternative(A3). As a result of final alternative(Al) has been selected, which is the most optimized alternative.

• Journal of Ecology and Environment
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• v.35 no.4
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• pp.323-329
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• 2012

The Standardized Precipitation Index (SPI) is a widely used drought index to provide good estimations of the intensity, magnitude and spatial extent of droughts. The objective of this study was to analyze the spatial pattern of drought by SPI index. In this paper, the patterns of drought hazard in Iran are evaluated according to the data of 40 weather stations during 1967-2009. The influenced zone of each station was specified by the Thiessen method. It was attempted to make a new model of drought hazard using GIS. Three criteria for drought were studied and considered to define areas of vulnerability. Drought hazard criteria used in the present model included: maximum severity of drought in the period, trend of drought, and the maximum number of sequential arid years. Each of the vulnerability indicators were mapped and these as well as a final hazard map were classified into 5 hazard classes of drought: one, slight, moderate, severe and very severe. The final drought vulnerability map was prepared by overlaying three criteria maps in a GIS, and the final hazard classes were defined on the basis of hazard scores, which were determined according to the means of the main indicators. The final vulnerability map shows that severe hazard areas (43% of the country) which are observed in the west and eastern parts of country are much more widespread than areas under other hazard classes. Overall, approximately half of the country was determined to be under severe and very severe hazard classes for drought.

• Journal of Korea Soil Environment Society
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• v.3 no.3
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• pp.75-86
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• 1998

This paper is going to show the way we can sample the landfill gases flowing out to the air through final cover soil by using an closed chamber in the field for a short time. In addition, we came to the following results through the application of model with actual measurements. 1) Analyzing changes of concentration in the chamber(H: 10-30cm) every 5 minutes, considering analysis time of gas chromatograph for an half hour. 2) The proportion of $CE_4$to $CO_2$changes rapidly near the surface of final cover soil by the influence of methane oxidation reaction. 3) When flux of landfill gas is F=$10^{-5}$mol/$\textrm{m}^2$.s), methane oxidation reaction has an influence on composition of gases, however there is little influence when F=$10^{-6}$ mol/($\textrm{m}^2$.s).

• Proceedings of the Plant Resources Society of Korea Conference
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• 2003.10b
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• pp.43-43
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• 2003

Multiple regression equations (Rehman et al. 2000) have been developed to predict the salinity tolerance of Acacia seeds, expressed as the I$\sub$50/ (the concentration of NaCl required to reduce final germination to 50% of the control value in DW). Accurate predictions can be made using one or more chemical and biological seed parameters. In this study the theoretical effect of varying final germination percentage in distilled water, germination rate in distilled water. (Rate), Ca$\^$2+/ or K$\^$+/ contents and their ratios, as independent factors or related factors, on the predicted salinity tolerance (I$\sub$50/) of Acacia species was investigated. Simulation of the effects of changing final germination, rate, calcium and potassium suggest the possibility of practical application of these results to modify the salinity tolerance of seeds. The predicted I$\sub$50/ increased with increasing final germination. Similarly, the higher the rate of germination, the higher the predicted salt tolerance of Acacia species. The Ca$\^$2+/ content of seeds was found to be positively correlated with I$\sub$50/. Species with higher Ca$\^$2+/ contents had a higher I$\sub$50/. This suggests that I$\sub$50/ might be increased by increasing the Ca$\^$2+/ contents of seeds by pretreatment with calcium salts or by supplying these to the mother plants.

• Journal of Environmental Science International
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• v.29 no.8
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• pp.857-870
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• 2020

In this study, the antibiotic components in the final effluent from the 12 wastewater treatment facilities located in the Nakdong River basin were investigated, and the correlation between organic matters, nutrients and antibiotics was analyzed. In the final effluent of the wastewater treatment facilities, three sulfonamides antibiotics (sulfamethazine, sulfathiazole, sulfachlorpyridazine) and tetracyclines antibiotics (oxytetracycline, doxycycline) were detected. Sulfamethazine were detected at all points and ranged from 10.398 to 278.784 ng/L. Sulfathiazole were detected at 6 points (Andong, Gumi, Hapcheon, Miryang, Uiryeong, Haman), and ranged from 23.773 to 144.468 ng/L. The correlation coefficients between sulfathiazole and TSS, COD, TOC, NH₃-N, NO₂-N, and T-N components were high in the range of 0.73 to 0.92. The correlation coefficient between sulfamethazine and T-N was 0.48, and the correlation with the rest of the water quality components was low. The correlation coefficient between sulfamethazine and sulfathiazole was 0.78. Through this study, it was confirmed that the concentration of sulfonamides antibiotics was higher than the concentration of tetracyclines antibiotics in the final effluent of 12 wastewater treatment facilities in the Nakdong River basin, and the concentration of sulfathiazole increased with organic matters and nutrients.

• Journal of The Korean Association For Science Education
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• v.9 no.1
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• pp.53-67
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• 1989

General Physics CAI Program was developed for university science and engineering student. The program was restricted in the field of mechanics and was mainly aimed for individual tutorial. This project was supported by Government. Department of Education, physics attending their general physics classes in university. The program was written in BASIC and constructed by frame, 4 professors and 6 graduate students were involved in the project. Summary of this study is as follows. 1. The theory of CAI was illuminated from a new point of view to enhance usefullness of CAI. Also the structure of frame type CAI was studied. 2. The program was developed as follows 1) The program consisted of main program, pretest routine, tutorial routine, final test routine, and several other routines for program control. Whole program was written in BASIC. 2) 20 problems for pretest, 90 problems and subsequent hints and solutions for tutorial, 20 problems for final test were developed. 3) According to student's pretest result, tutorial course was routed through several different courses which contain different number of problems 4) The expected rate of achievment for final test was set to 75%. 5) Data of students response to problems including number of tries and time used were recorded for the purpose of achievment analisys 3. 22 students went through whole course and the results were as follows. 1) Pretest marks were widly distributed from 20 points to 100. It means that achievement of high school physics course were not enough. 2) Throughout tutorial course, students who had got higher mark in pretest answered correctly in the first trial at a higher rate of 78 %. Overall rate of correct answer in the second trial was distributed appropriatly. 3) Average mark of final test was 78.8 points, rather a higher rate of achievement than expected. This means that the program was constructed well.

• Asian Pacific Journal of Cancer Prevention
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• v.17 no.9
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• pp.4463-4467
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• 2016

Purpose: To review the impact of using intra-operative ultrasound guided breast conserving surgery with frozen sections on final pathological margin outcome with the current guidelines set forth by the Society of Surgical Oncology (SSO) and the American Society of Surgical Oncology (ASTRO). Materials and Methods: A retrospective review including all cases of intra-operative ultrasound guided breast conserving surgery was performed at the National Cancer Institute Thailand between 2013 and 2016. Patient demographics, tumor variables, intraoperative frozen section and final pathological margin outcomes were collected. Factors for positive or close margins were analyzed. Results: A total of 86 patients aged between 27 and 75 years with intra-operative ultrasound guided breast conserving surgery were included. Three cases (3.5%) of positive margin were detected by intra-operative frozen section and 4 cases (4.7%) by final pathology reports. There were 18 cases (20.9%) with a close margin (<1 mm). Factors affecting this result comprised multi-foci, presence of invasive ductal carcinoma (IDC) combined with ductal carcinoma in situ (DCIS) and invasive lobular carcinoma (ILC). Conclusions: With the current SSO/ASTRO for adequate margin guidelines, using intra-operative ultrasound to locate the boundary for resection with breast conserving surgery provided a high success rate in obtaining final pathology free margin outcomes and minimizing re-operation risks especially when combined with intra-operative frozen section assessment. The chance of finding positive or close margins appears higher in cases of IDC combined with DCIS, ILC and with multi-foci cancers.

• 한국해양학회지
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• v.30 no.5
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• pp.436-441
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• 1995

Final biomass yields (peak optical density) and growth rates (divisions/day) of seven clones of Skeletonema costatum from Korean coastal waters were measured to understand their intraspecific variations in the light intensity niche component under 25$^{\circ}C$ condition. Daily growth rates of 6 out of 7 S. costatum clones were maximum at 6000 lux while that of YS4, a neritic clone, was maximum at 9000 lux. The final biomass yields of 4 out of the 7 s. costatum clones were maximum at the lowest light intensity of 2000 lux. Minimum final biomass yields were found at 9000 lux in all the S. costatum clones other than an estuarine clone, HDC9. The intraspecific variations of the mean growth rate and mean final biomass yield under each of the three different light intensities in terms of the coefficient of variation were not greater than 10% in any of the 7 S. costatum clones.