• Geomechanics and Engineering
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• v.28 no.6
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• pp.613-624
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• 2022

A study of the evolution of overburden fractures under the solid-fluid coupling state was conducted based on the geological and mining characteristics of the coal seam depth, weak strata cementation, and high-intensity mining in the mining areas of West China. These mining characteristics are key to achieving water conservation during mining or establishing groundwater reservoirs in coal mines. Based on the engineering background of the Daliuta Coal Mine, a non-hydrophilic simulation material suitable for simulating the weakly cemented rock masses in this area was developed, and a physical simulation test was carried out using a water-sand gushing test system. The study explored the spatial distribution and dynamic evolution of the fractured zone in the mining overburden under the coupling of stress and seepage. The experimental results show that the mining overburden can be vertically divided into the overall migration zone, the fracture extension zone and the collapse zone; additionally, in the horizontal direction, the mining overburden can be divided into the primary fracture zone, periodic fracture zone, and stop-fracture zone. The scope of groundwater flow in the overburden gradually expands with the mining of coal seams. When a stable water inrush channel is formed, other areas no longer generate new channels, and the unstable water inrush channels gradually close. Finally, the primary fracture area becomes the main water inrush channel for coal mines. The numerical simulation results indicate that the overlying rock breaking above the middle of the mined-out area allows the formation of the water-conducting channel. The water body will flow into the fracture extension zone with the shortest path, resulting in the occurrence of water bursting accidents in the mining face. The experimental research results provide a theoretical basis for the implementation of water conservation mining or the establishment of groundwater reservoirs in western mining areas, and this theoretical basis has considerable application and promotion value.

• Journal of the Korean Society of Combustion
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• v.18 no.1
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• pp.1-6
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• 2013

Authors' previous works on thermoacoustic(TA) model development showed good results in predicting combustion instability characteristics in a gas turbine combustor. However, they also suggested there were some limitations in growth rate estimation, which might be related with over-simplification of flame structure. As a first trial for improving the model accuracy, the current paper introduces the modified TA model considering the actual flame location in the combustor. The combustor is divided into the unburned and the burned area before and after the flame location, and then acoustic equations are re-organized. The modified TA model results show a better accuracy in predicting the growth rate of instabilities comparing with the previous results. However, obtained results still overestimate the conditions where the combustor goes unstable. Further researches considering heat release distribution through flames are required.

• Proceedings of the KSME Conference
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• 2001.06d
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• pp.813-820
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• 2001

The Safety depressurization System(SDS) of KNGR prevents RCS from overpressurization by discharging high pressure and temperature coolant through the I-sparger into the IRWST during an accident. If IRWST water temperature rise locally, around the sparger, beyond $200_{\circ}$2000 F by the discharged coolant, unstable steam condensation can cause large pressure load on the IRWST wall. To investigate whether this condition can be avoided for the design basis event IOPOSRV(Inadvertent Opening of one Pilot Operated Safety Relief Valve), the flow and temperature distribution of water in the IRWST is calculated by using CFX 4.3 computational fluid dynamic code. According to the results, since pool water temperature does not exceeds temperature limit within 50 seconds after the opening of one POSRV, it can be assured that the integrity of IRWST wall is maintained.

• Journal of Korean Society for Atmospheric Environment
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• v.2 no.1
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• pp.23-31
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• 1986

Meteorological Measurement was performed for evaluation of the horizontal vertical standard deviation $(\sigma_y, \sigma_z)$, surface roughness length and stmospheric stability during the period of March to October 1985 The major results are as follows; 1) The average value of surface roughness length was 144cm at NEPI. 2) In frequency distribution of atmospheric stability, neutral state (D class) was dominent in Seoul (29%) and Pusan (30%). Unstable states (A. B. C. class) were 26% in Seoul and 24% in Pusan. Also, stable states (D. E. F class) were 74% in Seoul and 76% in Pusan. 3) Standard deviations of horizontal ad vertical direction were evaluated as a function of downwind distance and atmospheric stability at NEPI, Jamsil and Pujeondong (Pusan). Standard deviation of horizontal direction was largest at NEPI among 3 areas because of mechanical turbulence resulting from difference of surface roughness length.

• Proceedings of the Korean Society of Broadcast Engineers Conference
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• 2021.06a
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• pp.105-108
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• 2021

Generative adversarial networks (GANs) have reached a great result at creating the synthesis image, especially in the face generation task. Unlike other deep learning tasks, the input of GANs is usually the random vector sampled by a probability distribution, which leads to unstable training and unpredictable output. One way to solve those problems is to employ the label condition in both the generator and discriminator. CelebA and FFHQ are the two most famous datasets for face image generation. While CelebA contains attribute annotations for more than 200,000 images, FFHQ does not have attribute annotations. Thus, in this work, we introduce a method to learn the attributes from CelebA then predict both soft and hard labels for FFHQ. The evaluated result from our model achieves 0.7611 points of the metric is the area under the receiver operating characteristic curve.

• KIPS Transactions on Computer and Communication Systems
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• v.5 no.10
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• pp.373-378
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• 2016

Recently, IPS(Indoor Positioning System) Technology has been progressing study and research, It has been studied in the fingerprinting and trilateration continuously. however because Fingerprinting and Trilateration Technology use AP(Access Point) for Positioning Calculation, Fingerprinting and Trilateration are not never had a credit positioning accuracy by using unstable RSSI in large scale. in this paper, to improve the problem about precise positioning in wide area, we introduced a concept of Sector including Cell. Sectors are not involved in each other and only fingerprinting calculation is proceed in a sector. we suggest this fingerprinting system considering efficiency and accuracy and compared to conventional fingerprinting, we demonstrated our system efficiency by mathematical techniques.

• Lingua Humanitatis
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• v.8
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• pp.313-329
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• 2006

In some American English dialects, the vowels /a:/ or /c:/ have been replaced with /a:/, as in caught /ka:t/ dog /da:g/ that were pronounced in /kc:t/, and /dc:g/ previously. General American does not have /a:/ in its vowel system. But in East American and Western Pensylvania, cot and caught are homophones, /ka:t/, and similarly with other pairs such as collar vs. caller, stock vs. stalk, don vs. down, knotty vs. naughty. The use of /a/ or /c/ is quite unstable, and is a well-known diagnostic for distinguishing the northern speech area of the United States from the midland and southern area. For an increasing number of Americans, however, entirely lack the opposition between /a/ and /c/, merging to /a/, referring to 'both' of the vowels of lot. This paper investigates the use of /b:/ in American dialects and its relationship with /a:/, /c:/ in AE, and with short /a/ in RP. Examining the isoglosses of the use of /a:/ in various databases of the phonological atlas of North America, this paper discusses the use, position, and trend of merger to /a:/ from the vowels of /a:/ and /c:/ in Current American English.

• Journal of The Korean Society of Integrative Medicine
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• v.10 no.4
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• pp.1-9
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• 2022

Purpose : The purpose of this research is to propose a more efficient exercising method by measuring and comparing the movement of center of pressure (COP) while hemiplegic stroke patients perform kneeling squat exercise and squat exercise. Methods : 17 hemiplegic stroke patients were instructed to perform kneeling squat exercises and squat exercises, and the research was designed as a cross-over study. For data collection, a pressure distribution measurement platform (PDM) was used to measure the movement area, length, speed, and distance from the center of the X-axis of center of pressure. The data was then analyzed through a paired t-test. Results : Kneeling squat exercises have been found to have a significantly smaller center of pressure movement area compared to that of squat exercise(p<.001), and the center of pressure movement length of kneeing squat exercise has also been found to be relatively shorter (p<.001). Moreover, kneeling squat exercises have been found to have a significantly slower center of pressure movement speed than squat exercise (p<.001), and kneeing squat exercise center of pressure movement distance from the center of the X-axis has been found to be significantly small (p<.001). Conclusion : Kneeling squat exercises have significantly decreased amounts of center of pressure movement area, distance, and speed compared to squat exercises. Also, the center of pressure movement distance from the center of the X-axis was relatively closer. This result seems to derive from patients performing their motions with wide base surfaces while being refrained from using unstable ankle joints during kneeing squat exercise. Therefore, it can be concluded that kneeing squat exercises show relatively balanced center of pressure movements between the paralyzed and non-paralyzed sides because kneeling squats show smaller shakes in the center of pressure.

• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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• v.19 no.4
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• pp.256-264
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• 2014

This study was carried out to estimate the benthic environments and polychaetous community in Garolim Bay, through five field surveys from April 2006 to April 2007. Garilim Bay is a semi-enclosed bay and composed of a biramous tidal channel and nearby wide tidal flats. Surface sediment in the inner bay was composed of fine grained particles whereas that in the mouth area of bay was of coarse grained ones. Benthic polychaete worms were the most dominant taxa occupying 65.1% of total benthic macrofauna. Species number was higher in the inner bay than mouth and outer area of bay, and in the bay higher on the tidal flat than channel area. Density was higher on the tidal flat than channel area. Dominant polychaetous species were Prionospio sp., Heteromastus filiformis, Lumbrineris longifolia and so on, which is known as opportunistic species. Prionospio sp. and H. filiformis inhabited mainly on the tidal flats in inner bay, while L. longifolia in the channel area and mouth of the bay. Cluster analysis and nMDS showed the typical inner-to-outward distribution of station groups, which indicated the sequential difference of the species composition of each station group. To assess the benthic healthiness of Garolim Bay by AMBI and BPI analysis, the benthic condition was analyzed from slightly polluted in the outer and mouth of the bay to moderately polluted in the inner bay. Assumed from dominant species composition and benthic healthiness condition, benthic environments of Garolim Bay was slightly unstable and disturbed and organic enrichment was currently underway by massed fisheries farms.

• 한국연소학회:학술대회논문집
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• 2005.10a
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• pp.231-237
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• 2005

Interruption of good fluidization in a fluidized bed ash cooler(FBAC) for discharging bed materials such as sand or coal ash particles from the CFB combustor is frequently happened because of agglomeration of the particles in the bed. This unstable operation may, in the worst case, result in an unscheduled boiler shut down. In this study, we examined the operation problems of the FBAC of Tonghae CFB boiler and studied and introduced the simple detection and solution techniques with analyzing the mixing property and the occurrence of defluidization in a simulated fluidized bed ash cooler system (0.5m-H x 0.5m-W x 1.0m-L). The bridge of the large particles at the bed surface could be observed, and this caused to form the defluidization area at the entrance of the FBAC. The defluidization was affected not only by airflow rates but also by the particles discharging rates as well as particle size distribution in the FBAC. The local defluidization could be detected by analysis of the accumulated standard deviation error at a given period of time. Also, the regulation of the overall or local airflow rate made clearing up the local defluidization possible.