• Journal of the Mineralogical Society of Korea
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• v.24 no.1
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• pp.19-29
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• 2011

Clay mineral assemblages of core PC25A collected from the northern part of the Aleutian Basin in the Bering Sea were examined in order to investigate changes in sediment provenances and transport pathways. Ages of core PC25A were determined by both Last Appearance Datum of radiolaria (L. nipponica sakaii; $48.6{\pm}2\; ka$) and age control points obtained by the correlations of $a^{\ast},\; b^{\ast}$, and laminated sediment layers with the adjacent core PC23A, whose ages are well constrained. The corebottom age of core PC25A was calculated to be about 57,600 yr ago and core-top might be missing during coring execution. Average contents of smectite, illite, kaolinite, and chlorite during the last glacial period are 11% (5~24%), 47% (36~58%), 13% (9~19%), and 29% (21~40%), respectively. Clay mineral assemblages of the last glacial period are characterized by higher illite and lower smectite contents than those of core MC24 representing the modern values. Illite-rich clay sediments during the warm Early Holocene were transported from the northern part of Alaska continent (Province 1) through the ice-melt waters. During the deglacial period (B${\phi}$lling-All${\phi}$rod) of MIS 2, clay-sized particles seemed to be also transported by ice-melt waters mainly from Province 2 and Province 3 located farther south than Province 1. Higher smectite content during the Last Glacial Maximum is attributed to increased amounts of clay particles from the adjacent Alaska Peninsula (Province 4). From the early to the middle MIS 3, illite and smectite contents decreased, whereas chlorite content increased. With the low sea level standing during MIS 3 the supply of clay sediments from Province 2 and Province 3 was most likely intensified. Changes in clay mineral assemblages of core PC25A located in the northern part of the Aleutian Basin in the Bering Sea are closely related to the change of surface current system caused by sea level variation during the last glacial period.

• Journal of the Korean Society of Radiology
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• v.14 no.3
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• pp.279-287
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• 2020

Recently, interest in radiation protection is increasing because of the occurrence of accidents related to exposure dose. So, the nuclear safety act provides to install the shields to avoid exceeding the dose limit. In particular, when the worker conducts the non-destructive testing (NDT) without the fixed shielding structure, we should monitor the access to the workplace based on a constant dose rate. However, when we apply for permits for NDT work in these work environments, the consideration factors to the estimation of the distance and exposure dose are not legally specified. Therefore, we developed the excel model that automatically calculates the distance, exposure dose, and cost if we input the factors. We applied the assumption data to this model. As a result of the application, the distance change rate was low when the thickness of the lead blanket and collimator is above 25 mm, 21.5 mm, respectively. However, we didn't consider the scattering and build-up factor. And, we assumed the shape of the lead blanket and collimator. Therefore, if we make up for these limitations and use the actual data, we expect that we can build a database on the distance and exposure dose.

• Journal of Korea Water Resources Association
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• v.46 no.8
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• pp.821-831
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• 2013

Recently image velocimetries, including particle image velocimetry (PIV) and surface image velocimetry (SIV), are often used to measure flow velocities in laboratories and rivers. The most difficult point in using image velocimetries may be how to determine the sizes of the interrogation areas and the measurement uncertainties. Especially, it is a little hard for unskilled users to use these instruments, since any standardized measuring techniques or measurement uncertainties are not well evaluated. Sometimes the user's skill and understanding on the instruments may make a wide gap between velocity measurement results. The present study aims to evaluate image velocimetry's uncertainties due to the changes in the sizes of interrogation areas and searching areas with the error analyses. For the purpose, we generated 12 series of artificial images with known velocity fields and various numbers and sizes of particles. The analysis results showed that the accuracy of velocity measurements of the image velocimetry was significantly affected by the change of the size of interrogation area. Generally speaking, the error was reduced as the size of interrogation areas became small. For the same sizes of interrogation areas, the larger particle sizes and the larger number of particles resulted smaller errors. Especially, the errors of the image velocimetries were more affected by the number of particles rather than the sizes of them. As the sizes of interrogation areas were increased, the differences between the maximum and the minimum errors seemed to be reduced. For the size of the interrogation area whose average errors were less than 5%, the differences between the maximum and the minimum errors seemed a little large. For the case, in other words, the uncertainty of the velocity measurements of the image velocimetry was large. In the viewpoint of the particle density, the size of the interrogation area was small for large particle density cases. For the cases of large number of particle and small particle density, however, the minimum size of interrogation area became smaller.

• Journal of Korean Society of Archives and Records Management
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• v.5 no.1
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• pp.79-105
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• 2005

This study is that the name from Tagjijunjeol is compared with the actual papers used in historical documents. I have selected the families having had influencing power in Gyungi-Do(京畿道), Gyungsang-Do(慶尙道), Jeonra-Do(全羅道), Chungcheung-Do(忠淸道), and analyzed 1504 articles of historical documents owned by those families. I checked up each papers used in historical documents in it's shape of screens, density, raw material. I cannot find the feature of it's region, but prominent feature according to the types and period of historical documents. At first, I have surveyed the impressions of screen marks in papers. The number of strips can be divided into two cases, around 10 and around 17. The case around 17 is similar to the number seen in the book paper of the early Joseon Dynasty, but the case around 10 is rare. Dard Hunter said in his book, published in 1933, that screens were made of Korean grass(Miscanthus sp.) at that time in Korea. I guess the impressions of screen marks of the case around 10 was made of Korean grass, Miscanthus sp.. The case around 10 and the case around 17 were not different in period, but the contemporary appearance. However, if we look into the change of strips' number, we can learn that it becomes more dense as time goes by. The intervals of hair stitch, contrary to book paper, have appeared irregularly and a short hair stitch was frequently found between long hair stitches. This was the result of fastening extra stitch to increase the firmness of strips, as the part of screens which was frequently touched by hands would wear out easily. Then, have look into the density. Each kinds of historical documents had a wide range of density. But the average have had relationship with the kinds of paper written in Tagjijunjeol. The historical documents having the same item of paper have kept similar densities. From the density variation of Gosingyoji(告身敎旨), the letter of appointment the official rank over 5 by king, based on time periods, we can see a great disparity between before and after Imjin-waeran war. Before Imjin-waeran war paper's quality was high, right after Imjin-waeran war went abruptly down, and went gradually up just from 1650's, but since 1700's quality has not risen more, kept the value. On the contrary, the density of Gyocheop(敎牒), the letter of appointment the official rank under 5 by the Ministry of Personnel and the Ministry of Military, have not had a great disparity according to time periods, but had a lower density than Gosingyoji. Joseon Dynasty has strictly divided Gosingyoji appointing the official rank over 5 from Gyocheop appointing the official rank under 5, it seems to distinguish the appointment by king from the appointment by Ijo(吏曹), the Ministry of Personnel and Byeongjo(兵曹), the Ministry of Military.

• Clean Technology
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• v.25 no.2
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• pp.107-113
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• 2019

Numerical model that considered the shrinking core model and elutriation and degradation of particles was developed to predict selective chlorination of ilmenite and carbo-chlorination of $TiO_2$ in a two stage fluidized bed chlorination furnace. It is possible to analyze the fluidized bed chlorination reaction to be able to reflect particle distribution for mass balances and the chlorination reaction. The numerical model showed an accuracy with error less than 6% compared with fluidized bed experiments. The chlorination degree with particle size change was greater with a smaller particle size, and there was a 100 min difference to obtain a chlorination degree of 1 between $75{\mu}m$ and $275{\mu}m$. This was not shown to such a great extent with variation of temperature ($800{\sim}1000^{\circ}C$), and there was only a 10 min difference to obtain a chlorination degree of 0.9. In the first selective chlorination process, the mass reduction rate approached to the theoretical value of 0.4735 after 180 min, and chlorination changed the Fe component into $FeCl_2$ or $FeCl_3$ and showed nearly 1. In the second carbo-chlorination process, the chlorination degree of $TiO_2$ approached 0.98 and the mass fraction reached 0.02 with conversion into $TiCl_4$. In the first selective chlorination process, 98% of $TiO_2$ was produced at 180 min, and this was changed into 99% of $TiCl_4$ after an additional 90 min. Also the mass reduction rate of $TiO_2$ was reduced to 99% in the second continuous carbo-chlorination process.

• The Journal of Engineering Geology
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• v.7 no.3
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• pp.191-205
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• 1997

Measurements on subsurface movement of the Songsanri tomb site including the Muryong royal tomb was conducted using a tiltmeter system for the period of 15 months form July 7, 1996 to September 30, 1997. Two coordinate tilt monitoring data shows the biggest movement rate of 2.3mm/m/yr toward south in the frontal wall(N-S tilt) of the Muryong royal tomb. Southward tilting of bricks above the southern fire place in the western wall of the Muryong royal tomb is a proof of southward tilting of the royal tomb since its excavation in 1971. The eastern wall of the Muryong royal tomb is also tilting toward inside the tomb with the rate of 1.523mm/m/yr. Furthermore, tilting rate of wall increases twice in rainy season. It is interpreted tbat infiltration of water into the tomb and nearby ground in rainy season results in dangerous status for the safety of tomb structure. On the whole, normal component tilting of the walls of the 5th tomb is large than its shear component. It shows a small displacement toward one direction without no abrupt change in its direction and amount of tilting. The tilting rate of walls of the 6th tomb is about 8.8mm/m/yr in the dry season which is much bigger than those of other tombs in rainy season. Deformation events of walls of the tombs are closely related to amount of precipitation and variation of temperature. In comparison with different weather conditions, tilting is much bigger during the period of rainy weather than sunny weather. It is interpreted that rainwater flew into the turm through faults and nearby ground. High water content in nearby ground resulted strength of ground. The tilting event of walls shows a hysterisis phenomenon in analysis of temperature effect on tilting event. The walls tilt rapidly with steep rising of temperature, but the tilted walls do not come back to original position with temperature falling. Therefore, a factor of steep increase of the temperature must be removed. It means the tomb have to be kept with constant temperature. The observation of groundwater level using three boreholes located in construction site and original ground represented that groundwater level in construction site is higher than that of original ground during the rainy season from the end of June to August. It means that the drainage system of the Muryong royal tomb is worse than original ground, and it is interpreted that the poor drainage system is related to safety of tomb structure. As above mentioned, it is interpreted that artificial changes of the tomb environment since the excavation, infiltration of rainwater and groundwater into the tomb site and poor drainage system had resulted in dangerous situation for the tomb structure. According to the result of the long period observation for the tomb site, it is interpreted that protection of the tomb site from high water content should be carried out at first, and the rise of temperature by means of the dehumidifier inside the tomb must be removed.

• Progress in Medical Physics
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• v.3 no.2
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• pp.1-12
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• 1992

For intraoperative radiation therapy using electron beams, a cone system to deliver a large dose to the tumor during surgical operation and to save the surrounding normal tissue should be developed and dosimetry for the cone system is necessary to find proper X-ray collimator setting as well as to get useful data for clinical use. We developed a docking type of a cone system consisting of two parts made of aluminum: holder and cone. The cones which range from 4cm to 9cm with 1cm step at 100cm SSD of photon beam are 28cm long circular tubular cylinders. The system has two 26cm long holders: one for the cones larger than or equal to 7cm diamter and another for the smaller ones than 7cm. On the side of the holder is an aperture for insertion of a lamp and mirror to observe treatment field. Depth dose curve. dose profile and output factor at dept of dose maximum. and dose distribution in water for each cone size were measured with a p-type silicone detector controlled by a linear scanner for several extra opening of X-ray collimators. For a combination of electron energy and cone size, the opening of the X-ray collimator was caused to the surface dose, depths of dose maximum and 80%, dose profile and output factor. The variation of the output factor was the most remarkable. The output factors of 9MeV electron, as an example, range from 0.637 to 1.549. The opening of X-ray collimators would cause the quantity of scattered electrons coming to the IORT cone system. which in turn would change the dose distribution as well as the output factor. Dosimetry for an IORT cone system is inevitable to minimize uncertainty in the clinical use.

• Korean Journal of Agricultural and Forest Meteorology
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• v.16 no.3
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• pp.199-212
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• 2014

The physiological responses of three common temperate species, Pinus densiflora, Fraxinus rhynchophylla, Sorbus alnifolia to elevated $CO_2$ was investigated using open top chambers with different $CO_2$ concentrations. Morphological (stomatal size, density and area) and physiological characteristics (maximum rates of photosynthesis, carboxylation and electron transport) were compared among trees grown under ambient, ambient ${\times}1.4$ (~550 ppm) and ambient ${\times}1.8$ (~700 ppm) $CO_2$ concentrations for last four years. Morphological responses were different among species. F. rhynchophyllar increased their stomatal size and S. alnifolia had higher stomatal density under elevated $CO_2$ than ambient. Stomatal area decreased in P. densiflora, whereas it increased in S. alnifolia. However, the maximum photosynthesis rate increased in all species up to 43.5% by S. alnifolia under elevated $CO_2$ and the enhancement increased with time. Even with four years of exposure to elevated $CO_2$, there was no sign of acclimation in the maximum carboxylation rate and the maximum electron transport rates in all species. Especially, S. alnifolia even showed the temporary increase of photosynthetic capacities in spring, when leaf nitrogen concentration was high with new leaf development. There was no significant differences in diameter growth rate in any species due to high variation in their tree sizes, however accumulated diameter and biomass for four years showed significantly increment in all species under elevated $CO_2$. For example, S. alnifolia showed 59% increase in diameter at the ambient ${\times}1.8$ (~700 ppm) compared to ambient.

• Korean Journal of Ecology and Environment
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• v.49 no.4
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• pp.354-374
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• 2016

This study explored spatiotemporal variability of water quality in correspondence with hydrometeorological factors in the five stations of Paldang Reservoir located in the Han River during 4 years from May 2012 to December 2015. Variability of basic water quality factors were largely related with seasonal fluctuations of hydrology. Temperature stratification occurred in the deep dam station, and prolonged hypoxia was observed during the draught year. Nitrogen nutrients were increased with decreasing inflow in which changing pattern of $NH_4$ reversed to $NO_3$ by the effect of treated wastewater effluent. Phosphorus increase was manifest during the period of high inflow or severe drought. Chl-a variation was reversely related with both flow change and AGP(algal growth potential) variations. Our study demonstrated that water quality variability in Paldang Reservoir was largely attributed to both natural and operational changes of inflow and outflow (including water intake) based on major pollution source of the treated wastewater (total amount of $472{\times}10^3m^3d^{-1}$) entering to the water system from watershed. In the process of water quality variability, meteorological (e.g., flood, typhoon, abnormal rainfall, scorching heat of summer) and hydrological factors (inflow and discharge) were likely to work dynamically with nutrients pulse, dilution, absorption, concentration and sedimentation. We underline comprehensive limnological study related to hydro-meteorolology to understand short- and long-term water quality variability in river-type large reservoir and suggest the necessity of P-free wastewater treatment for the effective measure of reducing pollution level of Paldang drinking water resource.

• Journal of Nutrition and Health
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• v.23 no.3
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• pp.157-169
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• 1990

This study was designed to investigate the effect of supplementation of fish oil on serum apoprotein and platelet function in healthy young females. Eighteen female college students were divided into 3 groups. Each group fed a typical Korean diet supplemented with 15g, 12g, and 9g of fish oil respectively for 1-week. Blood samples were obtained 4 times, before supplementation, immediately after, 1-week after and 3-week after stopping supplementation. After 6-week break, the doses of fish oil were interchanged among 3 groups and the experiment was repeated to reduce interindividual variation. The concentration of apoprotein A, apoprotein B in the serum samples and the platelet adhesion, the platelet aggregation and bleeding time were determined immediately after supplementation of fish oil, 1-week after and 3-week after stopping supplementation and then the value compared with those of before supplementation period. The results obtained are summarized as follows: Serum apoprotein A levels decreased significantly(p<0.05), immediately after supplementation of fish oil in the 15g group. The serum apoprotein B levels did not show significant change. The platelet adhesion decreased significantly(p<0.05) 1-week after supplementation of fish oil in the 15g group. The platelet aggregation decreased significantly(p<0.01) immedeately after supplementation of fish oil in the 15g group.