• Journal of Korea Foundry Society
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• v.43 no.5
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• pp.230-240
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• 2023

The pitting corrosion behavior of 329LD cast lean duplex stainless steel and CF3M cast austenitic stainless steel was investigated in chloride environments. The pitting corrosion resistance of the 329LD alloy was superior to that of the CF3M alloy because the pitting potential, passive region, and critical pitting temperature of the low Ni-low Mo 329LD alloy were higher than those of the high Ni-medium Mo commercial CF3M alloy. There are two main reasons for the enhancement of the pitting corrosion resistance of high Cr-low Momedium N 329LD alloy compared to the low Cr-medium Mo CF3M alloy: First, the pitting resistance equivalent number (PREN_δ+γ) value of the 329LD alloy is higher than that of the CF3M alloy. Second, the passive region of the 329LD alloy is larger than that of the CF3M alloy. It indicates that the synergistic effect of the three elements by adding high Cr and low Mo-medium N to the 329LD alloy enhances the passivity of the passive film, thereby increasing the pitting corrosion resistance. It was verified that based on the PREN_γ of austenite (γ) and PREN_δ of ferrite (δ) values calculated using an N-factor of 16, the pitting corrosion of the 329LD alloy was selectively initiated at the γ-phases because PREN_γ value of austenite (γ) was smaller than that of ferrite (δ), and finally propagated from the γ-phase to the δ-phase.

• Journal of Nutrition and Health
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• v.47 no.1
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• pp.77-88
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• 2014

Purpose: This study analyzed the foodservice satisfaction and menu preference of 506 high school boarding students in Jeju surveyed from July 2-30, 2012 with the aim of providing basic data for improving the quality of boarding food-service management. Methods: The data were analyzed using descriptive analysis, t-test, and Pearson's correlation coefficients, using the SPSS Win program (version 12.0). Results: Regarding satisfaction with dormitory foodservice, the satisfaction scores for service and hygiene were 3.46 (out of 5 scales), whereas the score for menu quality was 3.26 points. In terms of satisfaction by meal, dinner showed the highest score, at 3.70 (out of 5 scales). The satisfaction scores for breakfast were significantly higher in girls (3.36) than boys (2.93). Regarding intake of meals provided, dinner showed the highest score, at 3.96 (out of 5 scales), whereas breakfast showed the lowest score, at 3.63 points. Intake of lunch and dinner was significantly higher in boys (4.12, 4.17, respectively) than girls (3.72, 3.76, respectively). Regarding the requirements of subjects for dormitory foodservice, 43.4% of subjects selected improvement of food taste and 36.6% of girls chose menu diversity. In terms of menu preferences for main dishes, the students preferred noodles (4.06) and one-dish cooked rice (3.92) to cooked rice (3.66). The subjects preferred beef rib soup (4.10) and Kimchi stew (3.99) in soups and stews. With regard to the menu preferences for side dishes, steamed foods showed the highest score, at 3.95 (out of 5 scales), whereas seasoned foods showed the lowest score, at 2.89 points. The students preferred beef, pork, and chicken to fish and vegetables. The students preferred dessert the most with fruit juices (4.52). Bread and rice cake were more favored by girls, showing significant differences between boys and girls (p < 0.05, p < 0.01, respectively). Conclusion: Development of a systematic nutrition education program that can encourage practice of proper eating habits is needed. In addition improvement of the quality of boarding school meals through the service of various menus is needed.

• Journal of the Mineralogical Society of Korea
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• v.18 no.4 s.46
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• pp.277-288
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• 2005

Perlite, a hydrated volcanic glass, occurs mainly as a bed-like body, and is distributed intermittently along the unconformity surface between the Beomgockri Group and its lower formations, viz. Janggi Group. The perlite is intimately associated with surrounding pumiceous welded tuff and rhyodacites in space and time. Compared to the typical perlite, the perlite is rather silica-poor and impure, and thus, includes lots of phenocrysts and rock fragments. Nearly the perlite is compositionally rather close to a pitchstone than a perlite in water contents. Petrographic comparison between perlite and associated volcanic to volcaniclastic rocks indicates that pumiceous welded tuff and rhyodacite seem to be Protolith of the Perlite. A Zr/$TiO_{2}$-Nb/Y diagram and field occurrence of perlite and their protolithic rocks also conforms the above interpretation. Kn addition, remnant vesicles in perlite strongly reflect that the precursor of perlitic glass appeared to be pumice fragment as well as volcanic glass. The perlite was diagenetically formed by way of a pervasive water-rock interaction at the deposition of the Manghaesan Formation in lacustrine environment. During perlitization, $SiO_{2}$ and alkali tend to be consistently depleted. Preexisting system of the Beomgockri Group based on the perlite formation should be corrected, because the perlite was formed diagenetically without lateral persistence in its occurrence.

• Journal of Nutrition and Health
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• v.8 no.4
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• pp.15-26
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• 1975

The purpose of this paper is to investigate the nutrients intake situation and the physical growth and development of junior high school girls in cheju island, the peculiar area in Korea, and to study every possible correlation ketween daily food intake and growth rate of them. Further, it made an attempt to research nutrition problems for them in this area and assist in their growth and development through proper nutritional marragement. The survey was conducted in seven sample schods selected randomly from all three districts -this is Bukcheju-gun, Namcheju-gun and cheju city-of cheju Island. Four hundred eighteen girls, aged thirteen years ald, in second year grade of junior high schools, were provided with prepared questionnaires. For six days, July $16{\sim}21$ in 1975, the respondents filled out the questionnaires. They were asked to keep record of what they ate each meat. Their mitrients intake were analyzed in accordance with their daily food intake records during a six day period. On the other side, including physical growth index calculated by means of weight and hight of the respondents, their school records were also investigated. Critical Ratio as well as percentage calculation were included for statistical analysis. The findings and results abtained are summarized as follows: (1) Living circumstance a) Average numbers of brother and sister in sampled pupils' family were five. b) Niety percent of the respondents were brought up by mother's milk at their infants and 45 percent of them were weaned at the age of 13 to 24 months. c) Fourty-six percent of them revealed irregulity in their meal time. d) The most favorite main dish was boiled rice mixed other cereals (34%), next bread (31%) and boiled noodle (26%), and kimchi was the most papular side dish (64%). (2) Nutrition survey a) The average calorie intake of a pupil per day was 1,783 cal. and the total calorie intake was composed of carbohydrate 73%, pratein 15%, fat 12% respectively. b) Carolie and nutrients were lower than the recommended level, except vitamins A,$B_1$ and Niacin, c) Average protein intake per day was 68g, which was relatively near to the recommended level, but in fact, most of them came from grain which is lacking in essential amino acids. The ratio of animal protein intake to tatal protein intake was 36%. d) Their average animal food intake was proportionated in 14% in their total food intake and the cereals consumed in the largest quantity at the level of 63% out of whole food groups. (3) The results of statistical analysis a) The correlation between the calorie intake and the physical growth index revealed statistical significancy at the level of P<.005. b) The correlation between the protein intake and the physical growth index revealed statistical significancy at the level of .01

• The Journal of Korean Academy of Prosthodontics
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• v.47 no.1
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• pp.61-69
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• 2009

Statement of problem: Porcelain veneers have become a popular treatment modality for aesthetic anterior prosthesis. Fitting porcelain veneers in the mouth usually involve a try-in appointment, which frequently results in salivary contamination of fitting surfaces. Purpose: An in vitro study was carried out to investigate the effect of silane treatment timing and saliva contamination on the resin bond strength to porcelain veneer surface. Material and methods: Cylindrical test specimens (n=360) and rectangular test specimens (n=5) were prepared for shear bond test and contact angle analysis. Whole cylindrical specimens divided into 20 groups, each of which received a different surface treatment and/or storage condition. The composite resin cement stubs were light-polymerized onto porcelain adherends. The shear bond strengths of cemented stubs were measured after dry storage and thermocycling (3,000 cycles) between 5 and $55^{\circ}C$. The silane and their reactions were chemically monitored by using Fourier Transform Infrared Spectroscopy analysis (FTIR) and contact angle analysis. One-way analysis of variance (ANOVA) and Dunnett's multiple comparison were used to analyze the data. Results: FT-IR analysis showed that salivary contamination and silane treatment timing did not affect the surface interactions of silane. Observed water contact angles were lower on the saliva contaminated porcelain surface and the addition of 37% phosphoric acid for 20 seconds on saliva contaminated porcelain increased the degree of contact angle. Silane applied to the porcelain, a few days before cementation, resulted in increasing the bond strength after thermocycling. Conclusion: Within the limitation of this study, it can be concluded that it would be better to protect porcelain prosthesis before saliva contamination with silane treatment and to clean the contaminated surface by use of phosphoric acid.

• Korean Journal of Ecology and Environment
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• v.36 no.1 s.102
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• pp.83-94
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• 2003

Concentrated releases of zinc into water usually results from discharges associated with industrial purpose. The released zinc into soil is corroded and released into water. In aquatic environment, exess zinc is toxic to the organisms and causes the growth inhibition and malformation of them as a heavy metal. In this study, excess zinc toxicity was tested by FETAX (frog embryo teratogenetic assay with Xenopus)as in vivo system. Xenopus embryos at st.9 were exposed to $100{\sim}900\;{\mu}M$ of zinc for 7 days and 81% of individuals were survived in 100 ${\mu}M$, and 25% were survived in 1000M of zinc solution. In external malformations, swelled belly and intestinal dysplasia were common, and all of tested individuals showed these malformations in 200 ${\mu}M$ or higher concentration of zinc. In 400 ${\mu}M$ or higher concentration, all of tested tadpoles showed faded heart. Also, hypo-pigmentation, lens hernia and loose digestive track were very frequently found in 100 ${\mu}M$ of zinc. The histological study with paraffin section of zinc treated tadpoles showed following abnormalities; regeneration of photoreceptor on retina, reduced vitreous chamber in eye, reduction of red blood cells in heart, abnormal liver, swelling of pronephric cell, muscle dysplasia and palatal papilloma. These abnormalities may be caused by the degeneration of mitochondria, inhibition of cell adhesion, and the formation of leghemoglobin by zinc due to the substitution of $Ca^{2+}$ by $Zn^{2+}$. The body length was reduced due to the excess zinc. From a statistical result, body lengths of 300 ${\mu}M$ or higher concentrative g개ups was significantly reduced comparing that of control group. Recently, many spontaneous malformations and reduction of amphibians are reported, From the results of present study, excess zinc mi호t be a factor of amphibian reduction, and the control of zinc discharges is very important.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.46 no.12
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• pp.108-116
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• 2009

In this paper, we propose a Ethernet based audio distribution system with a new L1/L2 hybrid switching scheme, and evaluate its performance. The proposed scheme not only offers guaranteed low latency and jitter characteristics that are essentially required for the distribution of high-quality uncompressed audio traffic, and but also provide an efficient transmission of data traffic on the Ethernet environment. The audio distribution system with a proposed scheme consists of a master node and a number of relay nodes, and all nodes are mutually connected as a daisy-chain topology through up and downlinks. The master node generates an audio frame for each cycle of 125us, and the audio frame has 24 time slotted audio channels for carrying stereo 24 channels of 16-bit PCM sampled audio. On receiving the audio frame from its upstream node via the downlink, each intermediate node inserts its audio traffic to the reserved time slot for itself, then relays again to next node through its physical layer(L1) transmission - repeating. After reaching the end node, the audio frame is loopbacked through the uplink. On repeating through the uplink, each node makes a copy of audio slot that node has to receive, then play the audio. When the audio transmission is completed, each node works as a normal L2 switch, thus data frames are switched during the remaining period. For supporting this L1/L2 hybrid switching capability, we insert a glue logic for parsing and multiplexing audio and data frames at MII(Media Independent Interlace) between the physical and data link layers. The proposed scheme can provide a good delay performance and transmission efficiency than legacy Ethernet based audio distribution systems. For verifying the feasibility of the proposed L1/L2 hybrid switching scheme, we use OMNeT++ as a simulation tool with various parameters. From the simulation results, one can find that the proposed scheme can provides outstanding characteristics in terms of both jitter characteristic for audio traffic and transmission efficiency of data traffics.

• Korean Journal of Agricultural and Forest Meteorology
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• v.7 no.4
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• pp.274-281
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• 2005

The climate of the Uisong Area is wet in the heat of summer and cold and dry in winter, The climate is highly consistent. The typical forest soil of the Uisong Area has an acidity of pH 4.5-5.6. The thickness of soil A layers is thin to an average of 10-20 cm and is a typical brown forest soil type. The growth characteristic of this climate and soil environment is as follows. In the case of Larix leptolepis, it takes 5-9 years to reach 6 cm diameter, The annual growth rate falls off greatly at an age of 17-19 years. The change of annual rings is more apparent on the north slopes compared with the east and northeast slopes. Pinus rigida takes 7-9 years to reach a 6 cm diameter. Annual growth rates of Pinus rigida fall greatly when age reaches 19 years. The change of annual ring growth of Pinus rigida was most apparent in the west and northeast slopes compared with the south and east slopes. In the case of Pinus koraiensis, the change of the annual ring width according to the characteristics of the slope is not important. Pinus koraiensis takes 6 yearsto reach the 6cm diameter, and annual growth rate fell off at age 19 years. In the case of Quercus acutissima, the growth of the valley trees is more stable than for trees grown at the mountain base. Annual growth rate of Quercus autissima fell off 19 years after planting. Ring growth of Robinia pseudo-acasia on northeast slopes appears much like that on northwest slopes. In conclusion, the main silviculture species reaches a 6 cm diameter in 5-9 years of growth, and the annual growth rate begins to fall between years 13 and 19 in the Uisong Area.

• The Journal of the Petrological Society of Korea
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• v.9 no.1
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• pp.13-28
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• 2000

Chojeong area is mainly composed of the Ogcheon Group which consists of regionally metamorphosed, age-unknown sedimentary rocks. In the northwestern parts, the Group is intruded by the Jurassic Daebo granite and Cretaceous felsic and mafic dykes. The lowermost, Midongsan Formation which consists of milky white impure quartzite, crops out along the anticline axes with N40E trend. Ungyori quartzite Formation is intercalated with quartzite and slate. Miwon Formation is most widely exposed in the area and consists mainly of phyllitic sandy rocks with a thin crystalline limestone bed. Hwajeonri Formation is divided into two parts, pelitic lower and calcareous upper parts, composed with phyllite and slate. Changri and Hwanggangri Formations are typical members of Ogcheon Group, the former bearing coally graphite seams consists mainly of black slate and phyllite with intercalated greenish grey phyllite, the latter is pebble bearing phyllite formation of which matrix and pebbles are variable in compositions and size. Biotite granite, porphyritic granite and two mica granite belong to Jurassic so-called Dabo granite. They intruded the Ogcheon Group forming vast contact metarnophic zone. Quartz porphyry, mafic dyke and felsite intruded along the marginal zone of porphyritic granite batholith and fracture of NS trend. Main structural lineaments in Ogcheon Group shows N25-45E, NS and N30-45W trends. The N25-45E trends are mainly from general ductile deformation during regional metamorphism, showing isoclinal folding, Fl foliations and lithological erosional characters. Some of these trends are due to normal faults. The NS and N30-45W trends represent brittle deformation including faults and joints. In the area of granitic batholith, NS to N30- 45 trends are from the direction of dykes. In the soils of the area, average contents of heavy metal elements such as Cd, Cr, Cu, Pb, and Zn are 0.2, 50.6, 35.5, 27.9, and 93.4 ppm respectively, which are not higher than the average values of natural soils, under the tolerable level. Enrichment Index does not show any heavy metal pollution in the area. Average depths of weathering(5m vs. 2m), porosities(43.94 vs. 51.80), densities(l.29 vs. 1.15), and permeabilities(2.52 vs. 8.07) are comparable in granite areas and in the phyllite areas of Ogcheon Group.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.43 no.1
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• pp.43-54
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• 2023

Due to climate change, drought and flood occurrences have been increasing. Accurate projections of watershed discharges are imperative to effectively manage natural disasters caused by climate change. However, climate change and hydrological model uncertainty can lead to imprecise analysis. To address this issues, we used two lumped models, IHACRES and GR4J, to compare and analyze the changes in discharges under climate stress scenarios. The Hapcheon and Seomjingang dam basins were the study site, and the Nash-Sutcliffe efficiency (NSE) and the Kling-Gupta efficiency (KGE) were used for parameter optimizations. Twenty years of discharge, precipitation, and temperature (1995-2014) data were used and divided into training and testing data sets with a 70/30 split. The accuracies of the modeled results were relatively high during the training and testing periods (NSE>0.74, KGE>0.75), indicating that both models could reproduce the previously observed discharges. To explore the impacts of climate change on modeled discharges, we developed climate stress scenarios by changing precipitation from -50 % to +50 % by 1 % and temperature from 0 ℃ to 8 ℃ by 0.1 ℃ based on two decades of weather data, which resulted in 8,181 climate stress scenarios. We analyzed the yearly maximum, abundant, and ordinary discharges projected by the two lumped models. We found that the trends of the maximum and abundant discharges modeled by IHACRES and GR4J became pronounced as changes in precipitation and temperature increased. The opposite was true for the case of ordinary water levels. Our study demonstrated that the quantitative evaluations of the model uncertainty were important to reduce the impacts of climate change on water resources.