• Elastomers and Composites
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• v.46 no.4
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• pp.277-283
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• 2011

In this study, engineering grade and high intensity reflective sheets were prepared with glass beads and their reflection performance and physical properties were investigated. The reflective sheets prepared by using glass beads are divided into enclosed or encapsulated lens type, depending on whether the glass beads are open in air or not. Because of an extra layer on the glass bead surface, the enclosed lens type reflective sheets show very little change in the properties by bad weather conditions, compared to encapsulated lens type reflective sheets. Optimization of the amount of glass beads on the surface was carried out, which determines the retroreflective properties. Enclosed and encapsulated lens type reflective sheets with various colors were prepared and their coefficients of retroreflection were determined. The encapsulated type reflective sheet with white color shows a coefficient of retroreflection of $210.4cd/1x{\cdot}m^2$, which is higher than the enclosed type ($74cd/1x{\cdot}m^2$). Effect of washing on the reflective property and adhesive power of the reflective sheets was investigated, and it is found that the number of glass beads decreased with washing and the aluminum layer deposited was damaged extensively in the encapsulated lens type reflective sheets.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.68 no.4
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• pp.236-245
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• 2023

We investigated the basic vegetative phase (BVP), photoperiod-sensitivity (PS), and thermo-sensitivity (TS) of 40 rice varieties to characterize their heading ecology that is adaptable to North Korean rice production areas. The ranges were 12 - 43 days for BVP, 0 - 74 days for PS, and 15 - 33 days for TS, depending on the variety. The number of days from transplanting to the heading stage (DTH) was significantly correlated with PS in the 13 major rice production regions where all 40 varieties (including early-, middle-, and mid-late-maturing varieties) were tested. DTH was significantly correlated with BVP and TS but not with PS in the 10 low-temperature regions where only 28 early-maturing varieties were tested. The heading ecology of the adaptable varieties for each region could be characterized by an exponential equation between the BVP and PS of varieties that headed at the border of the safe marginal heading date (SMHD) for each of the seven regional environments (Kaesong, Haeju, Yongyon, Singye, Sariwon, Nampo, and Pyongyang). A PS of 25 - 30 days or less was an additional adaptive trait in the Sariwon and Pyongyang environments. The varieties that reached the heading stage not later than the SMHD in six regional environments (Anju, Kusong, Sinuiju, Changjon, Wonsan, and Supung) and those that reached the heading stage not later than the late marginal heading date (LMHD) in four regional environments (Hamhung, Pyonggang, Huichon, and Kanggye) had both a PS of 26 days or less and a BVP of 25 - 28 days or less. In the Yangdok, Sinpo, and Chunggang environments, varieties that reached the heading stage not later than the LMHD for each region had a BVP of 15 - 20 days or less. The results suggested that a shortened BVP trait should be introduced to existing early-maturing rice varieties to reduce the duration of growth period to reach the heading stage.

• Journal of The Korean Association For Science Education
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• v.37 no.1
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• pp.49-61
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• 2017

This study seeks to explore high school students' changing attitudes toward science-related career choices with focus on the scientific career cultural capital perspective. We developed a questionnaire and surveyed female high school students. We used the survey results to explore the scientific career cultural capital factors and characteristics of the students who have chosen a science-related career. We selected twelve participants through science-related career choice type and then conducted in-depth interviews with them. Through the in-depth interviews, we explored how the factors of scientific career cultural capital affect the students' career choices. The result shows that the students developed internal resources through norms of obligation and reciprocity within the structure (family, school, community) based on external resources. The internal resources affected their science-related career choice. In elementary school, the students' interests in science and science-related occupations are the most influential in their choice of career directions. In high school, however, the students also considered career cognition, aptitude cognition, and career-value factors in their career choices. The interests in science were formed mainly due to education activity and daily-life activity. Over time, education activity's effect increased. The interests in science-related occupations were formed mainly due to daily-life activity during elementary school. In high school, the interests in science-related occupations formed due to diverse internal and external resources. Students who maintained a science-related career attracted external resources. Furthermore, they reinforced internal resources through interacting with various external resources. This study has implications for science education concerning students' science-related career choices.

• The korean journal of orthodontics
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• v.28 no.1 s.66
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• pp.43-49
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• 1998

The aim of this study were to measure and compare the stress level on three type brackets and each other material (stainless steel, ceramic) with tipping and torquing forces by using the finite element analysis and to design biomechanically favorable brackets. For this study, three kinds of brackets were selected(A:Transcend-RMO, B:Signature-Unitek, C:PAW: plain archwire appliance-applied for a patent in Yonsei Udiversity). The slot size of bracket was 0.022inch and the size of archwire was 0.0175x0.025inch and taper shaped archwire was used in PAW. Loading force in tipping was 4.27N and torquing force was 32.858N applied by archwire torsion with 19.7degree and 11.3 degree in C type bracket. The conclusions were that (1) The finite element method proved to be a useful tool in the stress analysis of orthodontic bracket subjected to various forces. (2) With tipping, the stresses were concentrated at the gingival wall of the wire slot where it meets the mesial bracket surface and the incisal wall of the wire slot where it meets the distal bracket surface and with torquing, the stresses were concentrated at the junction of the gingival or incisal wall and base of the slot. (3) The maximum stress value was higher in torquing force than tipping force and therefore it is desirable to design on the basis of torquing force. (4) It was considered that the change in material might be affect on the diminish of stress value in the place of stess concentration. (5) The maximum stress value was highest on PAW bracket when the tipping and torquing force was applied and therefore it would be desirable to use mechanically favorable material on PAW bracket.

• Journal of Soil and Groundwater Environment
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• v.13 no.6
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• pp.72-84
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• 2008

This study was carried out to provide proper management plans for small portable water supply system in the Nonsan area through water quality monitoring, hydrogeochemical investigation and multivariate statistical analyses. Nonsan area is a typical rural area heavily depending on small water supply system for portable usage. Geology of the area is composed of granite dominantly along with metasedimentary rocks, gneiss and volcanic rocks. The monitoring results of small portable water supply system showed that 13-21% of groundwaters have exceeded the groundwater standard for drinking water, which is 5 to 8 times higher than the results from the whole country survey (2.5% in average). The major components exceeding the standard limits are nitrate-nitrogen, turbidity, total coliform, bacteria, fluoride and arsenic. High nitrate contamination observed at southern and northern parts of the study area seems to be caused by cultivation practices such as greenhouses. Although Ca and $HCO_3$ are dominant species in groundwater, concentrations of Na, Cl and $NO_3$ have increased at the granitic area indicating anthropogenic contamination. The groundwaters are divided into 2 groups, granite and metasedimentary rock/gneiss areas, with the second principal component presenting anthropogenic pollution by cultivation and residence from the principal components analysis. The discriminant analysis, with an error of 5.56% between initial classification and prediction on geology, can explain more clearly the geochemical characteristics of groundwaters by geology than the principal components analysis. Based on the obtained results, it is considered that the multivariate statistical analysis can be used as an effective method to analyze the integrated hydrogeochemical characteristics and to clearly discriminate variations of the groundwater quality. The research results of small potable water supply system in the study area showed that the groundwater chemistry is determined by the mixed influence of land use, soil properties, and topography which are controlled by geology. To properly control and manage small water supply systems for central and local governments, it is recommended to construct a total database system for groundwater environment including geology, land use, and topography.

• Korean Journal of Agricultural and Forest Meteorology
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• v.20 no.2
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• pp.190-204
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• 2018

The probability of safe cropping and the major phenological stages in rice were assessed using daily mean temperature data from 1981 to 2016 at 27 sites in North Korea. The threshold temperatures for early marginal transplanting date (EMTD), marginal harvesting date (MHVD), safe marginal heading date (SMHD), and cumulative temperature-based heading date (CTHD) were set to be $14^{\circ}C$, $13^{\circ}C$, $22^{\circ}C$ for 40 days after heading, and cumulative temperature of $1200^{\circ}C$ to MHVD, respectively. The safe heading date (SHD) was assumed to be either SMHD or CTHD whichever was earlier. It was also assumed that the minimum requirement for the suitability of safe rice cropping was met when both SMHD and CTHD appeared along with the time period of 60 days or more from EMTD to SHD. It was analyzed that 17 sites (Kaesong, Haeju, Yongyon, Singye, Sariwon, Nampo, Pyongyang, Anju, Kusong, Sinuiju, Changjon, Wonsan, Hamhung, Pyonggang, Huichon, Supung, Kanggye) had 90% or higher probability, two sites (Yangdok, Sinpo) had 80-90% probability, and eight sites (Kimchaek, Chunggang, Chongjin, Sonbong, Changjin, Pungsan, Hyesan, Samjiyon) had less than 80% probability of the safe rice cropping. For each region, the representative EMTD, SHD, and MHVD were analyzed using the 80 percentile of total years tested. The ranges for EMTD, SHD, and MHVD were May 4 in Sariwon~May 24 in Sinpo, June 21 in Kanggye~August 11 in Haeju, and September 17 in Kanggye~October 16 in Haeju and Changjon, respectively. Time durations from EMTD to SHD and from SHD to MHVD were 67~97 days and 57~72 days, respectively, depending on the regions. This study would facilitate modeling efforts for rice yield simulation in future studies. Our results would also provide basic information for practical researches on the rice cropping system in North Korea.

• Journal of Korean Society of Environmental Engineers
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• v.28 no.3
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• pp.231-239
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• 2006

In this study, we evaluated the efficiency of using sulfur-$CaCO_3$ complex pellet in the sulfur oxidizing autotrophic denitrification process for synthetic wastewater with high $CaCO_3$ concentration. The sulfur-$CaCO_3$ complex pellet was packed in reactor(R4). Influent ${NO_3}^--N$ loading rate was from 200 to $1,000g/m^3{\cdot}day$. During the operation, average denitrification efficiency of R4 was above 95%. Particularly, the denitrififation rate at $1,000g/m^3{\cdot}day$ loading was 98.96% for R4. High ${NO_3}^--N$ removal efficiency was determined in R4 compared with other reactors. Through $Ca^{2+}$ and alkalinity analyses, we calculated the supplied alkalinity from the packed $CaCO_3$ in the reactor. Sulfur-$CaCO_3$ complex pellet more effectively supplied alkalinity through the dissociation of $CaCO_3$ as compared with other media. Based on these results, sulfur-$CaCO_3$ complex pellet increased the pH buffering capacity while also providing the carbon source to the denitrifying bacteria. Denitrification efficiency of R4 was also higher than other reactors. ESEM pictures of sulfur-$CaCO_3$ complex pellet show higher porosity than that of the granular sulfur. Hence, more denitrifying bacteria attached on the sulfur-$CaCO_3$ complex pellet than on granular sulfur. It can be concluded that the sulfur-$CaCO_3$ complex pellet is a more suitable media for a sulfur oxidizing autotrophic denitrification process as it provides high denitrification efficiency.

• Journal of the Korean Society of Food Science and Nutrition
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• v.38 no.3
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• pp.396-400
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• 2009

Dodok (Codonopsis lanceolata Bench. et Hook) root contains abundant pharmaceutical substances and is widely used as a food and a medicinal herb. To identify the major components, fermented Codonopsis lanceolata was analyzed for its chemical compositions prior to their pharmaceutical substances, which were used as the fundamental data. The contents of carbohydrate, crude protein, crude lipid and ash are 79.3%, 13.0%, 2.40% and 5.3%, respectively. The calories of fermented Codonopsis lanceolata was 390.5 kcal. Total dietary fiber was 47.4% of total carbohydrates. The protein was composed of 18 different amino acids. The contents of essential and non-essential amino acids were 8,118.18 mg and 10,913.42 mg. The K was the largest mineral followed by P, Ca and Mg, which means fermented Codonopsis lanceolata is alkali material. The contents of saturated fatty acids, monounsaturated fatty acids and polyunsaturated fatty acids were 37.76%, 3.84%, and 35.64%, respectively. Therefore, the amount of the total unsaturated fatty acid was higher than that of any other plant. The content of crude saponin in fermented Codonopsis lanceolata was 60.1 mg/g. It is expected that a follow up study on fermented Codonopsis lanceolata through development and evaluation of processed foods for their functional properties would provide useful information as a source of medicinal foods.

• Korean Journal of Heritage: History & Science
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• v.53 no.2
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• pp.180-203
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• 2020

In this study, the period before the Gwanbok of meritorious vassals' portraits was expressed in the acheongsaek-Heuk-Danryung was defined as the first period, and the costumes worn in portraits of meritorious vassals from Gaeguk (1392) in the early Joseon Dynasty to Jwali (1471) during the era of King Seongjong were reviewed. The portraits(1476) of Jeokgae meritorious vassals (1467) depicted as the Gwanbok of acheongsaek Heuk-Danryung were excluded. Among the copies that are currently considered to be portraits of meritorious vassals belonging to the first period, the portraits of Lee-je, Lee Cheon-woo, Ma Cheon-mok, Shin Suk-ju, Seol Gye-jo, and Lee Sung-won were selected, and the formative characteristics of Gwanbok components were examined. The Samo of Sam-Gongsin in the early Joseon Dynasty had a low height, a rounded end, and the side wings were narrow and short. However, since King Danjong, Jeongnan·Jwali meritorious vassals retained a higher form, and the side wings were twice as long. It was also confirmed that the pattern was not expressed in the side wings. The Danryung was expressed in light-colored Danryung without specific colors at the beginning of the country. After King Sejong, the Heuk-Danryung system for Yebok began, but it was not reflected in the Gwanbok of meritorious vassals' portraits, and was expressed as damhongsaek-Danryung after King Danjong. The pattern was not expressed on the exterior of the Danryung, and inner-wrinkled Mu was expressed on the side line. The Dapho and Cheolrik, the undergarments of the Danryung, were also confirmed as being blue (the Dapho) and green (the Cheolrik) after the Jeongnan meritorious vassals. The early Sam-Gongsin's Pumgye was expressed by rank belt, but as the system of rank badge was established after King Danjong, it began to express the Pumgye by rank badge and rank belt. Among the portraits of meritorious vassals, the rank badge was expressed only in the portrait of Sin Suk-ju, a Jeongnan meritorious vassal. As Hwaja worn on the Danryung, Heuk-hwa were confirmed in the Sam-Gongsin portraits of the early Joseon Dynasty. However, in the portraits of Jeongnan and Jwali meritorious vassals after King Danjong, the Baek-hwa was confirmed. In addition, in the seam parts of the Heuk-hwa and Baek-hwa identified in some portraits of meritorious vassals, Hwi decorated with yeongeumsa were identified, and it was found that the Hwaja decorated with Hwi were the Hyeopgeum-hwa worn by the 3rd rank and above.

• 한국노년학
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• v.37 no.1
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• pp.237-250
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• 2017

The purpose of this study is to analyze the effects of exercise program for prevention of falling on physical fitness, posture and fall prevention self-efficacy for elderly women. 30 females above the age of 65 were subjects for this study. Over an twelve week period, 14women in the experimental group performed exercise 2 times a week for 60 minutes per session. 16women in the control group didn't participate in the exercise program. The independent variable was a exercise program for prevention of falling. Dependent variables were physical fitness, posture and fall prevention self-efficacy. Prevention of falling exercise program is consisted of an elastic band using exercise and Korean dance movement exercise. Physical fitness consisted of grip strength, upper and lower body endurance, cardiovascular endurance, flexibility, balance, coordination. The posture was measured the static posture when standing, using a high-resolution camera, body style to automatically measure the distance and angle(M-zen, Korea). Posture was measured in both the coronal and sagittal plane via reference board. Fall prevention self-efficacy was measured via questionnaire using the Korea Falls Self-Efficacy Scale (FES-K). The physical fitness, posture and fall prevention self-efficacy were measured twice with pre and post exercise, and the difference between groups with Wilcox signed rank test, and the group-specific post verification was carried out with U-validated methods (Mann Whitney U test). Statistical significance level was verified by setting the p<.05. Lower body endurance, cardiovascular endurance, flexibility, balance and coordination significantly increased in the experimental group. The control group was no significant increase in physical fitness variables. shoulder slope angle, pelvic slope angle(coronal/sagittal), leg length difference, scapular inferior angle and left/right calcaneus angle significantly decreased in the experimental group. Both the experimental group and control group were no significant increase in fall prevention self efficacy. The prevention of falling exercise program for elderly women indicated the positive changes in physical fitness(except grip strength) and posture(except upper body slope). However, there are no significant differences of falling prevention self-efficacy between the both group. Thus, the prevention of falling exercise program for the elderly has been proved that it is highly efficient on improving physical fitness and posture proofreading. However, we still need to consider supplement exercise for grip strength and upper body slope.