• Journal of the Korean Orthopaedic Association
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• v.52 no.1
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• pp.65-72
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• 2017

Purpose: The purpose of this study was to evaluate the radiologic features of juxtafacet cyst and determine the correlation between these features and clinical outcome. Materials and Methods: We analyzed a total of 23 patients. The degree of facet joint degeneration was classified using the Fujiwara method. The facet joint angles were measured with an magnetic resonance imaging to determine whether there was a difference between the cystic lesion that was occupied and the cystic lesion that was not occupied. Disc degeneration was measured by the Pfirrmann classification method. The clinical result was evaluated using the Oswestry disability index score and visual analogue scale. Results: The L4-5 level of juxtafacet cyst was mostly affected, as found in previous studies. Facet joint arthritis was more severe within the side with the cystic lesion. Significant correlation was found between disc degeneration and juxtafacet joint cyst. All patients underwent wide decompression and fusion. Clinical result was excellent. No patients had signs of recurrence during the follow-up periods. Conclusion: Juxtafacet cyst has a significant correlation with facet joint degeneration. Therefore, aggressive surgical treatment-not just simple cyst excision-should be considered as the treatment option for juxtafacet cyst associated with degenerative lumbar disease.

• Journal of the Korean Institute of Landscape Architecture
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• v.52 no.3
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• pp.76-88
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• 2024

A significant cause of fall or overturning accidents in the construction industry, including landscaping construction and management, is work at heights using portable ladders. Portable ladders are classified as A-type or triangular support ladders depending on the number of supporting leg and support conditions. The tripod mobile ladder, which supports itself with only three supporting legs, is unstable and more prone to overturning compared to the A type ladders. Therefore, using the specifications of the tripod mobile ladder and the stability regulations of EN131-Part 7, overturning and resistance moment calculation formulas were derived for all directions in which overturning could occur. The moments calculated using these equations, and the overturning stability in each direction were evaluated. According to the calculation results, although there are differences depending on the direction, most are unstable for overturning at 8 or more steps. Based on these results, this study proposed measures to increase the moment of resistance by changing the weight, depth, and width, and using outriggers to ensure stability against the overturning of ladder. However, when changing the specifications of these measures, the size increases are excessive and the applicability is insufficient. On the other hand, outriggers are an applicable measure as they can ensure stability against overturning with only a minimum expansion length.

• Journal of the Mineralogical Society of Korea
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• v.23 no.2
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• pp.117-124
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• 2010

The sorption of $AsO_4,\;SeO_3,\;CrO_4$ on schwertmannite and thermal analysis of sorbed samples were carried out. The results of sorption experiments showed that sorption characteristics of those three oxyanions on schwertmannite can be divided into two groups. The extent of sorption of $AsO_4$ and $SeO_3$ were 100% at up to 1 mM solution concentration, and they increased no more significantly. This can be interpreted as $AsO_4$ and $SeO_3$ substituting $SO_4$ in schwertmannite strucure by the ratio of 1 : 1. The extent of the sorption of $CrO_4$ was much lower than those of other two oxyanions. Thermal analysis was performed using two kinds of sorbed samples at 0.1 and 1.25 mM concentrations. The results of the thermal analysis showed that the samples sorbed by three different oxyanions have different thermal characteristics. The samples sorbed by $AsO_4$ showed smaller weight loss around $600^{\circ}C$ than the original loss of pure schwertmannite, and it is attributed to the substitution of $AsO_4$ for $SO_4$, which was caused by the loss of $SO_4$, than pure schwertmannite due to the substitution of $SO_4$ by $AsO_4$. It also showed additional weight loss around $600^{\circ}C$ due to the decomposition of $AsO_4$ at that temperature. The weight loss of samples sorbed by $SeO_3$ started at slightly lower temperature than that sorbed by $SO_4$ and kept that loss at wider temperature range, probably indicating that the decomposition of $SeO_3$ occurs at slightly lower temperature. However, for the samples sorbed by $CrO_4$, the weight loss caused by the decomposition of $SO_4$ was also smaller and there was no additional weight loss at higher temperature due to the thermal stability of $CrO_4$, indicating that $SO_4$ was also substituted by $CrO_4$ in schwertmannite. Sorption experiment and thermal analysis indicate that $CrO_4$ sorbs on schwertmannite by substiuting $SO_4$, but the affinity to $SO_4$ or instability of $CrO_4$ in scwertmannite structure probably prohibit perfect 1 : 1 substitution.

• Korean Journal of Heritage: History & Science
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• v.56 no.4
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• pp.132-158
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• 2023

The five-story and seven-story stone pagodas at Cheongnyangsaji temple site in Gongju are located under the Sambulbong peak of Gyeryongsan mountain, and are known to have been built of the middle in Goryeo dynasty. As the two pagodas in which two types of Baekje stone pagoda coexist in one era, their historical and academic value are recognized. The seven-story pagoda was overturned by robbery in 1944, and as a result, the five-story pagoda was tilted. Although the two pagodas were restored in 1961, structural instability was continuously raised. In this study, measurement data accumulated from May 2021 to March 2022, and seasonal characteristics were reviewed, and the micro behavior of pagodas were analyzed according to temperature and precipitation during the same period. As a result, the micro thermoelastic behavior was repeated according to the daily temperature change in all sensors, and both the slope and the displacement showed microscale behavior. In the inclinometer, moisture containing the surface and inside of the stones repeated expansion and contraction due to temperature change, showing the micro movements. In particular, the upper part of the five-story pagoda moved up to 3.89° to the northwest, and the seven-story pagoda tilted up to 0.078° to the northeast. The maximum displacements were recorded as 0.127 and 0.149 mm in the five-story and the seven-story pagoda, respectively. These values tended to return to the original position at the end of the measurement, but did not recover completely, indicating a state requiring precise monitoring. The result obtained through the study can be used as basic data for the stable conservation of the two stone pagodas. Based on the behavioral characteristics considering various environmental factors should be analyzed, and the preventive conservation through the maintenance of measurement system built this time should be continued.

• Korean Journal of Food Science and Technology
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• v.32 no.5
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• pp.1002-1008
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• 2000

The purpose of this study was to provide the fundamental information for establishing the database needed to estimate total intakes of trans fatty acids in Korea. The amounts of trans fatty acids contained in 164 samples including 25 samples of margarines, 21 samples of shortenings, 19 samples of vegetable salad and cooking oils, 53 samples of confectionery products, 18 samples of bakery products, 19 samples of dairy products, and 9 samples of animal fats and meats were analyzed by capillary gas liquid chromatography. The average amounts of trans fatty acids in those foods were calculated and expressed as gram per one serving. Then, the average daily intakes of trans fatty acids per capita were estimated using the analyzed amounts of trans fatty acids and the amount of yearly production for those foods. The amounts of trans fatty acids per 100 g of lipids were $2.11{\sim}33.83%$ (14.66% on average) in margarines, $1.47{\sim}44.48%$ (14.21% on average) in shortenings, $0.18{\sim}3.82$ (1.54% on average) in vegetable salad and cooking oils, $0{\sim}45.81%$ (10.92% on average) in confectionery products, $0{\sim}18.32%$ (7.87% on average) in bakery products, $0.90{\sim}4.54%$ (2.27% on average) in dairy products, and $0.61{\sim}6.07%$ (2.24% on average) in animal fats and meats. Major isomers of trans fatty acid in the sample foods were $C_{18:1}$ and $C_{18:2}$. As a result, the korean average daily intake of trans fatty acids in korea was estimated to be 2.3 g per capita. The amounts of trans fatty acids consumed from each selected food were as follows: 0.35 g from margarines, 0.57 g from shortenings, 0.11 g from vegetable salad and cooking oils, 0.65 g from confectionery products, 0.07 g from bakery products, 0.14 g from dairy products and 0.21 g from animal fats and meats.

• Korean Journal of Optics and Photonics
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• v.27 no.1
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• pp.1-17
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• 2016

Over the past two decades, fiber-based lasers have made remarkable progress, now having reached power levels exceeding kilowatts and drawing a huge amount of attention from academy and industry as a replacement technology for bulk lasers. In this paper we review the significant factors that have led to the progress of fiber lasers, such as gain-fiber regimes based on ytterbium-doped silica, optical pumping schemes through the combination of laser diodes and double-clad fiber geometries, and tandem schemes for minimizing quantum defects. Furthermore, we discuss various power-limitation issues that are expected to incur with respect to the ultimate power scaling of fiber lasers, such as efficiency degradation, thermal hazard, and system-instability growth in fiber lasers, and various relevant methods to alleviate the aforementioned issues. This discussion includes fiber nonlinear effects, fiber damage, and modal-instability issues, which become more significant as the power level is scaled up. In addition, we also review beam-combining techniques, which are currently receiving a lot of attention as an alternative solution to the power-scaling limitation of high-power fiber lasers. In particular, we focus more on the discussion of the schematics of a spectral beam-combining system and their individual requirements. Finally, we discuss prospects for the future development of fiber laser technologies, for them to leap forward from where they are now, and to continue to advance in terms of their power scalability.