• Economic and Environmental Geology
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• v.36 no.6
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• pp.511-525
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• 2003

The Okcheon Group in the southwestern part of the Okcheon Metamorphic Belt is subdivided into two distinct tectonostratigraphic units: the Boeun unit in the south and the Pibanryeong unit in the north. The Boeun unit consists of petites, psammites, carbonaceous petites, limestones and pebble-bearing quartzites. The Pibanryeong unit is composed of petites, well-sorted fine-grained psammites, carbonaceous psammites and quartzites. In order to outlining stratigraphy and depositional environments of the Okcheon Group, detailed stratigraphic sections were measured in three locations; one section(Gosan section) of the Boeun unit and two sections(Sorungjae and Hwangryeongzae sections) of the Pibanryeong unit. The Gosan section of the Boeun unit is interpreted to be deposited in the shallow marine environments, whereas the Sorungjae and Hwangryeonaiae sections of the Pibanryeong unit appear to be deposited in slope and deep basin environments. This result indicates rapid subsidence between deposition of the Boeun and Pibanryeong units in sedimentary environment. The trace of sedimentological environments in the Hwasan area was investigated by geochemical analysis of 109 metapelitic and psammitic rock samples. Distinct chemical variations of politic and psammitic rocks from the Boeun and Pibanryeong units in the study area are evident from plots of major elements and $A1_2O_3$/$SiO_2$ versus Basicity Index($Fe_2O_3{＋}MgO$)/($SiO_2{＋}K_2O{＋}Na_2O$). The rocks show a progressive chemical trend from the Boeun unit to the Pibanryeong unit on these diagrams. They in the southern sector of the Boeun unit display lower values and a comparatively wide range of $A1_2O_3$/$SiO_2$ and Basicity Index, as compared with those from the northern sector of the Boeun and Pibanryeong units. The southern sector of the Pibanryeong unit including narrow staurolite-bearing zone is characterized by values that are transitional between the Boeun and Pibanryeong units. These data, combined with depositional environment progressively deepened towards the northwest, support a half-graben model for the Okcheon basin, as proposed by Cluzel et al.(1990)

• Korean Journal of Heritage: History & Science
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• v.49 no.3
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• pp.78-103
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• 2016

This research is a study on the side framework structure of the hipped and gable roof of Muryangsujeon at Buseoksa Temple. There is a record that Muryangsujeon was deconstructed and repaired in the period of Japanese Occupancy, and its authenticity has continuously been called into question because the structure of the hipped and gable side roofs, and the bonding of the rafters and eaves were not in good order and very different from those of Joseon Dynasty. Scholars date it differently. It is either dated at 13th century or 12th century. This study compares the non-planar configuration of the middle and front proportions of Muryangsujeon's hipped-and-gable-roof framework with those of the Tang(唐) and Song(宋) Dynasties in China. It concludes that the hipped-and-gable-roof framework of those architecture were built with the same technique. The style of architecture that side rafters directly touch the internal security (梁), like in Muryangsujeon, is not usual even among the hipped and garble roofs of the Tang(唐) and Song(宋) Dynasties. The technique of constructing the hipped roofs developed much further after the Tang Dynasty because they began to use garble eaves to build the side structure. The technique seems to have developed greatly by the period of Ming and Qing Dynasties. It also seems that the parallel-flat (平行輻射椽) rafter, which is the form of rafters used between the parallelrafter period and the half-flat-rafter period is very similar to the construction style of the current rafters of Muryangsujeon. However, the Muryangsujeon's eaves do not touch the corner rafter from the middle part. This seems to be a unique style, which is not common in China. In conclusion, the style of the side roof framework of Muryangsujeon at Buseoksa Temple is not of the China's southern regions, but of the northern regions of Tang(唐), Song(宋) and Liao(遼) Dynasties. And when considering the construction year and proportions of the middle front and side front on the same flat, this must be an ancient technique of the northeastern regions of Asia. Since it is likely that the structure of the side roof framework of Muryangsujeon at Buseoksa Temple has not been altered but is a unique style of hipped and gable roofs, this roof can serve as a good guide to restoring the hipped and garble roofs of the pre-Goyreo Dynasty period.

• Korean Journal of Heritage: History & Science
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• v.52 no.1
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• pp.64-81
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• 2019

Jeju Island is located at a strategic position, making it an important waypoint on the sea routes of East Asia. As a result, the island suffered many foreign invasions throughout history. Especially, it is widely known that Japanese pirates frequently invaded the island as the island was located on their way as they were sailing to China. Therefore, they built various defensive structures across the island. Fortresses, where a small number of defenders may fend off an enemy, were built in multiple places on the island. This was a strategy for the island to defend itself, as it was almost impossible to get prompt support in an emergency from the mainland due to the long distance. Fortresses, or walled cities, were the center of politics, culture, and economy of many areas. Therefore, they are a valuable resource to study the history and geographical characteristics of a place. For this reason, studies on fortresses started quite early on. However, studies on such relics in Jeju Island began very late. The research on fortresses was launched during the Japanese occupation for most mainland areas. However, studies on the relics on Jeju Island began as late as the 1970s. This was because scholars did not understand the importance of the city walls and fortresses on Jeju Island, and there were no researchers who specialized in city walls or fortresses on the island, as well. As archeological research on Jeju Island began to gain momentum, the studies on city walls and fortresses saw progress; however, these studies are still of an elementary level. In this study, the author summarized the status of studies on the city walls and fortress relics in Jeju Island and their preservation/maintenance status by era. According to the findings of this study, there were two Corean-era city wall/fortress relics and thirteen from the Chosun era., The researcher analyzed and presented the status of studies and the current condition of the relics. The status of attached structures was also documented.Furthermore, a short review of the maintenance work performed so far was provided. Also, the researcher mentioned the problems that accompanied the maintenance process of these relics, along with suggestions for improvement that could be referred to in future restoration/maintenance projects.

• Tunnel and Underground Space
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• v.32 no.6
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• pp.491-501
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• 2022

Bentonite has been proposed as a buffer and backfill material for high-level radioactive waste repository. Under such repository environment conditions, bentonite is subjected to combined thermal, hydrological, mechanical, and chemical processes. This study evaluates the feasibility of applying X-ray CT technology on the characterization of bentonite under hydration conditions using a newly developed testing cell. The cylindrical cell is made of platic material, with a removable cap to place the sample, enabling to apply vertical pressure on the sample and to measure swelling pressure. The hydration test was carried out with a sample made of Gyeonju bentonite, with a dry density of 1.4 g/cm³, and a water content of 20%. The sample had a diameter of 27.5 mm and a height of 34 mm. During the test, water was injected at a constant pressure of 0.207 MPa, and lasted for 7 days. After one day of hydration, bentonite swelled and filled out the space inside the cell. Moreover, CT histograms showed how the hydration process induced an initial increase and later progressive decrease on the density of the sample. Detailed profiles of the mean CT value, CT standard deviation, and CT gradient provided more details on the hydration process of the sample and showed how the bottom and top regions exhibited a decrease on density while the middle region showed an increase, especially during the first two days of hydration. Later, the differences in CT values with respect to the initial state decreased, and were small at the end of testing. The formation and later reduction of cracks was also characterized through CT scanning.

• Korean Journal of Environmental Agriculture
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• v.32 no.3
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• pp.214-223
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• 2013

BACKGROUND: This study focused on the development of an analytical method about dichlorprop (DCPP; 2-(2,4-dichlorophenoxy)propionic acid) which is a plant growth regulator, a synthetic auxin for agricultural commodities. DCPP prevents falling of fruits during their growth periods. However, the overdose of DCPP caused the unwanted maturing time and reduce the safe storage period. If we take fruits with exceeding maximum residue limits, it could be harmful. Therefore, this study presented the analytical method of DCPP in agricultural commodities for the nation-wide pesticide residues monitoring program of the Ministry of Food and Drug Safety. METHODS AND RESULTS: We adopted the analytical method for DCPP in agricultural commodities by gas chromatograph in cooperated with Electron Capture Detector(ECD). Sample extraction and purification by ion-associated partition method were applied, then quantitation was done by GC/ECD with DB-17, a moderate polarity column under the temperature-rising condition with nitrogen as a carrier gas and split-less mode. Standard calibration curve presented linearity with the correlation coefficient ($r^2$) > 0.9998, analysed from 0.1 to 2.0 mg/L concentration. Limit of quantitation in agricultural commodities represents 0.05 mg/kg, and average recoveries ranged from 78.8 to 102.2%. The repeatability of measurements expressed as coefficient of variation (CV %) was less than 9.5% in 0.05, 0.10, and 0.50 mg/kg. CONCLUSION(S): Our newly improved analytical method for DCPP residues in agricultural commodities was applicable to the nation-wide pesticide residues monitoring program with the acceptable level of sensitivity, repeatability and reproducibility.

• Journal of Korean Society of Forest Science
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• v.30 no.1
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• pp.19-29
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• 1976

The fiberboard and paper mills in this country are much affected by the price hikes and shortage of phenolic resins, since phenolic acid as a raw material depends on imported good. It is prerequisite to fiberboard industry to help replace with other sized and stabilize the prices and supply of them, improving the quality of boards. Thus, the present study was carried out to examine the effect of strength increasing sized such as urea formaldehyde resin (anion and cation type) and urea melamine copolymer resin, on the quality of the wet forming hardboard, and comparing them with two types of proprietary modified melamine resins, and ordinary size, phenol resin. The Asplund pulp was prepared from wood wastes mixed with 20 percent of lauan and 80 percent of pines as a fibrous material. After sizing agents were added at a pH of 4.5 for 10 minutes with alum in the beater, the stock was made in the form of wet sheet, prepared, and then performed by hot pressing cycle: $180^{\circ}C$, $50-6-5kg/cm^2$, 1-2-7 minutes. The properties of hardboard were examined after air conditioning. The results obtained are summarized as follows: 1. There is a significant difference in specific gravity among hardboards that were treated with strength increasing resins, but no difference is effected by the increase in the resin content. In the case of modified melamine resin, its specific gravity is highest. The middle group comprises cation type of urea resin, anion type of urea resin, and acid colloid of urea-melamine copolymer resin. The lowest is phenolic resin. 2. The difference of the moisture content of hardboard both by the resins and by the amount of each resin applied is significant. The moisture content of hardboard becomes lower along with the increase of each resin content, but there is no difference between 2 and 3 percent. 3. For water absorption, there is a significant difference both in the adhesives used and in the amount of paraffin wax emulsion. The water resistance becomes higher inn proportion to the content of the paraffin wax emulsion. To satisfy KS F standards of the water resistance, a proprietary modified melamine resin (p-6100) and modified cation type of urea resin (p-1500) do not require any paraffin wax emulsion, but in the case of anion type of urea resin, cation type of urea resin, and urea-melamine copolymer resin, 1 percent of paraffin wax emulsion is needed, and 2 percent of paraffin wax emulsion in the case of phenolic resin. 4. The difference of flexural strength of hardboard both by the resins and by the amount of each resin is significant. Modified melamine resin shows the highest degree of flexural strength. Among the middle group are urea-melamine copolymer resin, p-1500, anion type of urea resin, and cation type of urea resin. Phenolic resin is the lowest. The cause may be attributable to factors combined with the pressing temperature, sizing effect, and thermal efficiency of press platens heated electrically. 5. Considering the economic advantages and properties of hardboard, it is proposed that urea-melamine copolymer resin and cation type of urea resin be used for the development of the fiberboard industry. It is desirable to further develop the modified urea-melamine copolymer resin and cation type of urea resin through continuous study.

• Journal of Food Hygiene and Safety
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• v.27 no.1
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• pp.42-49
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• 2012

This study was carried out to investigate the toxicity of food Red No.2 in the Sprague-Dawley (SD) female rat for 4 weeks. SD rats were orally administered for 28 days, with dosage of 500, 1,000, 2,000 mg/kg/day. Animals treated with food Red No.2 did not cause any death and show any clinical signs. They did not show any significant changes of body weight, feed uptake and water consumption. There were not significantly different from the control group in urinalysis, hematological, serum biochemical value and histopathological examination. In conclusion, 4 weeks of the repetitive oral medication of food Red No.2 has resulted no alteration of toxicity according to the test materials in the group of female rats with injection of 2,000 mg/kg. Therefore, food Red No.2 was not indicated to have any toxic effect in the SD rats, when it was orally administered below the dosage 2,000 mg/kg/day for 4 weeks.

• Korean Journal of Heritage: History & Science
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• v.45 no.4
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• pp.54-73
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• 2012

In this article, we examined the patterns of activities of the Sarmathians though in a humble measure, with a focus on the regions where the Sarmathian sheaths spreaded. One of the main weapons the mounted nomads like the Scythias, the Sarmathians, and the Alans used at war was a spear. Though complementary, a sword was the most convenient and appropriate weapon when fighting at a near distance, fallen from the horse to the ground. The Sarmathian swords continued the tradition of the Akinakes which the Scythias or the Persians used, but those of the Sarmathians showed some advances in terms of the easiness with which a sword was drawn out from a sheath, and the way the sheaths were worn to parts of a human body. It turns out that the Sarmathian sheaths, which were designed for the people to draw swords easily, having the sheaths attached to thighs through 4 bumps, spread extensively from Pazyryk, Altai, to South Siberia, Bactria, Parthia and Rome. The most noteworthy out of all the Sarmathian sheaths were the ones that were excavated from the 4th tomb in Tillatepe, Afghanistan which belonged to the region of Bactria. The owner of the fourth tomb of Tilla-tepe whose region was under the control of Kushan Dynasty at that time, was buried wearing Sarmathian swords, and regarded as a big shot in the region of Bactria which was also under the governance of Kushan Dynasty. The fact that the owner of the tomb wore two swords suggests that there had been active exchange between Bactria and Sarmathia. It seemed that the reason why the Sarmathians could play an important role in the exchange between the East and the West might have something to do with their role of supplying Chinese goods to Silk Road. That's why we are interested in how the copper mirrors of Han Dynasty, decoration beads like melon-type beads, crystal beads and goldring articulated beads, and the artifacts of South China which produced silks were excavated in the northern steppe route where the Sarmathians actively worked. Our study have established that the eye beads discovered in Sarmathian tomb estimated to have been built around the 1st century B.C. were reprocessed in China, and then imported to Sarmathia again. We should note the Huns as a medium between the Sarmathians and the South China which were far apart from each other. Thus gold-ring articulated beads which were spread out mainly across the South China has been discovered in the Huns' remains. On the other hand, between 2nd century B.C. and 2nd century A.D. which were main periods of the Sarmathians, it was considered that the traffic route connecting the steppe route and the South China might be West-South silk road which started from Yunnan, passed through Myanmar, Pakistan, and Afghanistan, and then went into the east of India. The West-south Silk road is presumed to have been used by nomadic tribes who wanted to get the goods from South China before the Oasis route was activated by the Han Dynasty's policy of managing the countries bordering on Western China.

• Korean Journal of Soil Science and Fertilizer
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• v.26 no.2
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• pp.103-110
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• 1993

This study was made to evaluate the chemical properties of 481 farmers' orchard fields in An-Seong area. And the reasonable ferilizer rates were recommended utilizing the result of soil analysis. The results are summarized as follows : 1. As the soil fertility status of collected soil samples were evaluated on the basis of temporary optimal range for each soil chemical properties, 12.7 to 49.6% of the total 481 farmers' fields were range for soil improvement. 2. The contents of chemical component have a tendancy to decrease with depth gradually from surface to subsoil. 3. According to the relationship between the contents of soil component in subsoil and those in surface soil, the fertility condition of subsoil could be estimated on the basis of analysis data of surface soil. 4. The multiple regression equation for pear yield prediction to the organic matter and exchangable calcium contents in the soil were obtained. 5. Referring the average value, distribution ratio compared to the optimum level for each soil chemical properties and standard fertilizer rate, the soil fertility status could be categorized as "High" "Medium" and "Low". For each category, the recommended amounts for NPK and organic matter application were established. 6. The recommended rates through soul fertility diagnosis were less than farmer's dosage in the range 7.1~7.7 kg/10a for N, 0.8~11.5 kg/10a for $P_2O_5$, 7.1~19.9 kg/10a for $K_2O$ and 90~116 kg/10a for lime.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.26 no.5
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• pp.493-501
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• 1993

As the dispersants and the dispersant/oil mixtures are degraded naturally by the microorganisms in the seawater, the consumption of dissolved oxygen may cause marine organisms to be damaged especially in the waters where the dissolved oxygen level is low due to the pollution and the restriction of seawater flow. The biodegradation experiment, the TOD analysis and the element analysis for three dispersants(SG, GL and WC) and a nonionic surfactant(OA-5) were conducted for the purposes of evaluating the biodegradability of dispersants and studying the effect of dispersants on dissolved oxygen in the seawater. The results of biodegradation experiment showed 1mg of dispersants to be equivalent to $0.403{\sim}0.595mg$ of $BOD_5$ and to $0.703{\sim}0.855mg$ of $BOD_{20}$, and 1mg of nonionic surfactant to be equivalent to 0.50mg of $BOD_5$ and to 0.97mg of $BOD_{20}$ in the natural seawater. The results of TOD analysis showed 1mg of dispersants to be $2.37{\sim}2.80mg$ of TOD and 1mg of nonionic surfactant to be 2.45mg of TOD. The results of element analysis showed carbon content and hydrogen content to be $67.6{\sim}76.5\%$ and $10.2{\sim}12.2\%$ for dispersants, and $65.3\%$ and $10.3\%$ for nonionic surfactant, respectively. No nitrogen element was detected in dispersants and a nonionic surfactant. The biodegradability of dispersants shown as the ratio of $BOD_5/TOD$ was found to be in the range of $17{\sim}21\%$, and that of nonionic surfactant was found to be about $20\%$. This means that dispersants and nonionic surfactant belong in the organic matter group of middle-biodegradabilily. The deoxygenation rates($K_1$) and ultimate oxygen demands($L_o$) obtained through the biodegration experiment and Thomas slope method were found to be $0.121{\sim}0.171/day$ and $3.155{\sim}3.810mg/l$ for 4mg/l of dispersants and to be 0.181/day and 1.911mg/l for 2mg/l of nonionic surfactant in the seawater, respectively.