• Journal of Korean Tunnelling and Underground Space Association
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• v.24 no.6
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• pp.451-464
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• 2022

The high-level nuclear waste repository is a deep geological disposal system exposed to complex environmental conditions such as high temperature, radiation, and ground-water due to handling spent nuclear fuel. Continuous exposure can lead to cracking and deterioration of the structure over time. On the other hand, the high-level nuclear waste repository requires an ultra-long life expectancy. Thus long-term structural health monitoring is essential. Various sensors such as an accelerometer, earth pressure gauge, and displacement meter can be used to monitor the health of a structure, and a piezoelectric sensor is generally used. Therefore, it is necessary to develop a highly durable sensor based on the durability assessment of the piezoelectric sensor. This study designed an accelerated life test for durability assessment and life prediction of the piezoelectric sensor. Based on the literature review, the number of accelerated stress levels for a single stress factor, and the number of samples for each level were selected. The failure mode and mechanism of the piezoelectric sensor that can occur in the environmental conditions of the high-level waste repository were analyzed. In addition, two methods were proposed to investigate the maximum harsh condition for the temperature stress factor. The reliable operating limit of the piezoelectric sensor was derived, and a reasonable accelerated stress level was set for the accelerated life test. The suggested methods contain economical and practical ideas and can be widely used in designing accelerated life tests of piezoelectric sensors.

• Journal of the Korean Society of Radiology
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• v.15 no.6
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• pp.781-788
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• 2021

Due to the high sensitivity to radiation, excessive exposure needs to be prevented by accurately measuring the dose irradiated to the skin during radiation therapy. Although clinical trials use dosimeters such as film, OSLD, TLD, glass dosimeter, etc. to measure skin dose, these dosimeters have difficulty in accurate dosimetry on skin curves. In this study, to solve these problems, we developed a skin dosimeter that can be attached according to human flexion and evaluated its response characteristics. For the manufacture of the dosimeter, lead oxide (PbO) with high atomic number (Z_Pb: 82, Z_O: 8) and density (9.53 g/cm³) and silicon binders that can bend according to human flexion were used. In the case of a dosimeter made of PbO material, the performance degradation has been prevented by using parylene and others due to the presence of degradation due to oxidation, but the previously used parylene is affected by bending, so a new form of passive layer was produced and applied to the skin dosimeter. The characteristic evaluation of the skin dosimeter was evaluated by analyzing SEM, reproducibility, and linearity. Through SEM analysis, bending was evaluated, reproducibility and linearity at 6 MeV energy were evaluated, and applicability was assessed with a skin dosimeter. As a result of observing the dosimeter surface through SEM analysis, the parylene passive layer PbO dosimeter with the positive layer raised to the parylene produced cracks on the surface when bent. On the other hand, no crack was observed in the silicon passive layer PbO dosimeter, which was raised to silicon passive layer. In the reproducibility measurement results, the RSD of the silicon passive layer PbO dosimeter was 1.47% which satisfied the evaluation criteria RSD 1.5% and the linearity evaluation results showed the R² value of 0.9990, which satisfied the evaluation criteria R² 9990. The silicon passive layer PbO dosimeter was evaluated to be applicable to skin dosimeters by demonstrating high signal stability, precision, and accuracy in reproducibility and linearity, without cracking due to bending.

• Conservation Science in Museum
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• v.24
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• pp.1-16
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• 2020

This paper presents the process of re-conservation and the results of research on the production method of the Iron Sword with Ring Pommel with Three-Pointed Leaf Decoration, one of the excavation findings from Tomb No. 55 in the Dalseong Ancient Tomb Complex in Daegu. This iron sword is a double weapon with two large swords housed within a single sheath. Four smaller swords are attached to the surface of the sheath, two on the upper portion and the other two below. It is the only such two-in-one weapon excavated intact thus far from an ancient Korean tomb. The records show that it underwent conservation treatment twice in the past. In this study, it was subjected to conservation treatment again to replace the stiffener in some cracking areas, and its material, composition, and production method were analyzed by CT, XRF analysis, and stereoscopic microscopy. The sword is mainly made of copper, but the golden component contains both gold and mercury, which suggests that the copper was plated in gold using mercury amalgamation. The examination of the production methods indicates that it was intended more to demonstrate the authority of its owner rather than to serve any practical use. The two upper small swords on the sheath were made in the same manner as the main swords, and the two small lower swords were cut from a single metal sheet. The sheath was made by cutting two metal sheets. Supports were used to attach the two small swords to the upper portion of the sheath, while the lower portion of the sheath was slit to allow the other two small swords to be inserted into it. The ring pommels of the main swords have a three-pointed leaf decoration. As for the other designs, the handle of the main sword features a series of semicircles, the decorative bands on the sheath have waves in dots, and the fish tail of the sheath shows diagonal lines of dots.

• The Journal of Engineering Geology
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• v.31 no.4
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• pp.621-630
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• 2021

This study evaluated cracks and climate monitoring in Ipseok-dae columnar joints and Jigong Neodeol rock blocks in Mudeungsan National Park. The rocks' state of cracking and their surface temperatures were measured alongside air temperature, relative humidity, and wind velocity. The maximum crack behavior in Ipseok-dae was 0.367 mm at one point, and showed a slight tendency at other points. One in Jigong Neodeol was within 0.15 mm and showed a stable state with little change. The surface temperature of the Ipseok-dae columnar joints was higher on the side exposed to sunlight than on the shaded side. All blocks of Jigong Neodeol rock showed similar temperatures. The air temperature showed a similar distribution for both rock types. The air temperature showed a similar distribution for both Ipseok-dae and Jigong Neodeol. The relative humidity was mostly between 20% and 60% in Ipseok-dae and was between 20 and 70% in Jigong Neodeol. Both areas had low wind speeds, with maxima of 5 m/s in Ipseok-dae and 3 m/s in Jigong Neodeol. As a result, it is evaluated that crack behavior in Ipseok-dae columnar joints and Jigong Neodeol rock blocks have maintained a very stable state so far. The surface temperature, temperature, relative humidity, and wind velocity of the two areas showed small difference depending on the season, indicating that they were affected to some extent by the season. From a long-term perspective, this can continuously affect the deformation of the Ipseok-dae columnar joints or Jigong Neodeol rock blocks. Therefore, in order to accurately evaluate their stability, it is considered that the current microscopic delamination and exfoliation or the propagation and expansion of cracks should be continuously measured.

• Korean Journal of Agricultural and Forest Meteorology
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• v.24 no.3
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• pp.145-154
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• 2022

Due to abnormal weather conditions caused by climate change, natural disasters and damages are gradually increasing around the world. Global climate change as accompanied by warming is projected to exert adverse impact on production of potato, which is known as cool season crop. Even though, role of potato as a food security crop is expected to increase in the future, the climate change impacts on potato and adaption strategies are not sufficiently established. Therefore, this study was conducted to analyze the damage pattern of potatoes due to high temperature treatment and to evaluate the response of cultivars. T he high temperature treatment (35~38℃) induced heat stress by sealing the plastic house in midsummer (July), and the quantity and quality characteristics of potatoes were compared with the control group. T otal yield, marketable yield (>80 g) and the number of tubers per plants decreased when heat treatment was performed, and statistical significance was evident. In the heat treatment, 'Jayoung' cultivar suffered a high heat damage with an 84% reduction in yield of >80 g compared to the control group. However, in Jopung cultivar, the decrease was relatively small at 26%. Tuber physiological disturbances (Secondary growth, Tuber cracking, Malformation) tended to increase in the heat stress. Under heat conditions, the tubers were elongated overall, which means that the marketability of potatoes was lowered. T he tuber firmness and dry matter content tended to decrease significantly in the heat-treated group. T herefore, the yield and quality of tubers were damaged when growing potatoes in heat conditions. T he cultivar with high heat adaptability was 'Jopung'. T his result can be used as basic data for potato growers and breeding of heat-resistant cultivars.

• Journal of Practical Agriculture & Fisheries Research
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• v.16 no.1
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• pp.55-66
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• 2014

This study has been conducted to investigate the treatment time and concentration of GA₃ solution dipping for labor saving in 'Campbell Early' grapevine. The rachis growth at harvest was reduced by GA₃ solution dipping before 5 days flowering, and increased significantly by GA₃ solution dipping treatment at full bloom and after 5 days full bloom. GA₃ 5, 10, 20 mg·L^-1 dipping treatment before 5 days flowering and GA₃ 20 mg·L^-1 treatment of full bloom and after 5 days full bloom showed a rachis twist phytotoxicity symptom. The optimum GA₃ concentrations for rachis growth promotion without phytotoxicity were 5 mg·L^-1 and 10 mg·L^-1. The degree of compact berry, bloom, skin color, SSC and acidity at harvest by GA₃ solution dipping treatment time between concentration were not different from those of control. But the fruit berry weight was decreased by before 5 days flowering treatment when compared with control. There were no differences in full bloom and after 5 days full bloom treatment. The occurrence percent of berry cracking at before 5 days flowering and after 5 days full bloom treatment were significantly increased by GA₃ treatment. The bitter rot occurrence of berry at harvest was not affected by GA₃ treatment. Total rachis length of fruit cluster was increased by full bloom and 5 days after full bloom treatment. The length of rachis increased without reference to them position at full bloom and 5 days after bloom treatment. Accordingly, GA₃ 5 mg·L^-1 solution dipping treatment at full bloom and 5 days after full bloom were can be effectively for rachis growth promotion.

• Economic and Environmental Geology
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• v.56 no.1
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• pp.103-114
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• 2023

The Christian Museum of Gongju Jeil Church was first built in 1931 and was largely damaged during the Korean War, but the walls and chimneys have been preserved. This building has a high architectural values in that the chapel was reconstructed in 1956, and maintains its original form through repair of damaged parts rather than new construction. The stained glass windows were as installed in 1979 and has a great significance in the Dalle de Verre method using lump glass. However, some of the stained glass damaged partially, such as various cracks and splits, and vertical and horizontal cracks in the joint fillers of supporting the colored glass. As the structural materials of the stained glass window, an iron frame and cement mortar filled with it were used, and corrosion of iron, cracking of mortar and granular decomposition appear partially due to weathering. In the joint fillers, the content of Ca and S is very high, indicating that gypsum were used as admixtures, and the gypsums grow in a rhombohedral and forms a bundle, which is investigated to have undergone recrystallization. As a result of modeling the ultrasonic velocity at the joint fillers, the left and right windows at the entrance show relatively weak in the range of 800 to 1,600m/s, and the lower right corner of the altar window and the upper left corner of the center window were also 1,000 to 1,800m/s, showing relatively low physical properties. And gypsums produced during the neutralization of lime mortar were detected in the joint fillers and contaminants on the surface. Such salts may cause damage to the joint material due to freezing and thawing, so appropriate preventive conservation is required. Also, since various damage types are complexly appearing in stained glass window and joint filler, customized conservation treatment should be reviewed through clinical tests.

• Korean Journal of Agricultural Science
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• v.3 no.1
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• pp.95-104
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• 1976

This study was conducted to test the harvesting operation of two kinds of rice varieties such as Milyang #15 and Tong-il with a imported two furrow Japanese combine and was performed to find out the operational accuracy of it, the adaptability of this machine, and the feasibility of supplying this machine to rural area in Korea. The results obtained in this study are summarized as follows; 1. The harvesting test of the Milyang #15 was carried out 5 times from the optimum harvesting operation was good regardless of its maturity. The field grain loss ratio and the rate of unthreshed paddy were all about 1 percent. 2. The field grain loss of Tong-il harvested was increased from 5.13% to 10.34% along its maturity as shown in Fig 1. In considering this, it was needed that the combine mechanism should be improved mechanically for harvesting of Tong-il rice variety. 3. The rate of unthreshed paddy of Tong-il rice variety of which stem was short was average 1.6 percent, because the sample combine used in this study was developed on basisof the long stem variety in Japan, therefore some ears owing to the uneven stem of Tong-il rice could nat reach the teeth of the threshing drum. 4. The cracking rates of brown rice depending mostly upon the revolution speed of the threshing drum(240-350 rpm) in harvesting of Tong-il and Milyang #15 were all below 1 percent, and there was no significance between two varieties. 5. Since the ears of Tong-il rice variety covered with its leaves, a lots of trashes was produced, especially when threshed in raw materials, and the cleaning and the trashout mechanisms were clogged with those trashes very often, and so these two mechanisms were needed for being improved. 6. The sample combine of which track pressure was $0.19kg/cm^2$ could drive on the soft ground of which sinking was even 25cm as shown in Fig 3. But in considering the reaping height adjustment, 5cm sinking may be afford to drive the combine on the irregular sinking level ground without any readjustment of the resaping height. 7. The harvesting expenses per ha. by the sample combine of which annual coverage area is 4.7 ha. under conditions that the yearly workable days is 40, percentage of days being good for harvesting operation is 60%, field efficiency is 56%, working speed is 0.273m/sec, and daily workable hours is 8 hrs is reasonable to spread this combine to rural area in Korea, comparing to the expenses by the conventional harvesting expenses, if mechanical improvement is supplemented so as to harvest Tong-il rice. 8. In order to harvest Tong-il rice, the two furrow combine should be needed some mechanical improvements that divider can control not to touch ears of paddy, the space between the feeding chain and the thrshing drum is reduced, trash treatment apparatus must be improved, fore and rear adjust-interval is enlarged, and width of track must be enlarged so as to drive on the soft ground.