• KSCE Journal of Civil and Environmental Engineering Research
• /
• v.13 no.3
• /
• pp.59-67
• /
• 1993

The variations of the natural frequencies and the peak response acceleration at the top of prestressed concrete reactor building due to random variability and/or model uncertainty of structural parameters are studied. The results may be used as essential input parameters in seismic probabilistic risk assessment or seismic margin assessment of the reactor building. The sensitivity test of each structural parameter is first performed to determine the most influential parameter upon the natural frequency of structure model. Then Monte Carlo simulation technique is applied to evaluate the effect of parameter variation on the natural frequencies and the peak response acceleration. The acceleration time history is obtained by direct integration scheme. As the study results, it is found that the fundamental natural frequency and the peak response acceleration at the top of the building are most strongly affected by Young's modulus among the structural parameters, in which the value of mean plus one standard deviation obtained by probabilistic approach deviates up to about (+)12% from the result of deterministic method. Considering the uncertainty of flexural rigidity, the structural responses vary in range of (-)4%~(+)14%.

• Journal of the Society of Disaster Information
• /
• v.16 no.1
• /
• pp.44-59
• /
• 2020

This study analyzed a gas explosion accident. A gas smell from a underground coffee shop in the two-story building was reported to 119. A fire brigade was turned out, turned off the main valve of LPG gas cylinder on the roof, and checked the turning off of middle valve in the coffee shop. The fire brigade required a gas supplier and gas installer who arrived at the spot to take safety actions. Gas explosion occurred seven minutes after the fire brigade was withdrawn and two people died and 21 people were injured. A court decided that because the causes for gas explosion were not found, compensation responsibility could not be charged with the gas supplier, the gas installer, or Korea Gas Safety Corporation. In this reason, the court judged that only the fire brigade who was withdrawn without taking safety actions shall compensate victims or bereaved families. Therefore, fire brigades who turn out after a 119 report of a gas leak should take safety actions such as escaping people or preventing people's access and ventilating and be withdrawn when there is no possibility of fire or explosion.

• Transactions of the Korean Society of Automotive Engineers
• /
• v.18 no.2
• /
• pp.1-6
• /
• 2010

This study presents the practical design modification to improve the retracting performance of the pyro-typed high power pretensioner. 3 components of the pretensioner are redesigned and the usefulness of the design modification is verified by the experiment. During the pretensioning process, the gas blast generated from the gunpowder is transferred to the rack-pinion gear through the manifold. The rack-pinion gear is connected with the spool where the webbing is rolled up. According to the rotation of the pinion, the spool is turned and the webbing is winded. To help the gas blast flow well, the shape of the inner cross section of the manifold is changed. The spur gear design program is developed and used to find the best combination of the rack-pinion gear pair to increase the power transmission efficiency. The pinion guide is installed on the spool to prevent the vibration of the pinion. As a result of the experiment, the amount of the web retraction length is increased when every single design modification is applied. Therefore, the retracting performance of the pretensioner is considered to be improved if the presented design modifications are applied.

• Journal of Environmental Impact Assessment
• /
• v.25 no.1
• /
• pp.51-62
• /
• 2016

Recently, soil has been recognized as a crucially important resource that even can change the quality of life. Also, recent studies have gradually mentioned the importance of assessing soil impact induced by development plans and projects. In this study, after detailed soil assessement items were selected from our national environmental policies and international agreements, they were tested for the long-term dam construction planning in order to ensure more suitable implementation of strategic environment assessment(SEA). We found that soil resources can be impacted by diverse factors such as soil erosion, soil organic matters, soil moving, soil biodiversity, and others. Such detailed factors are found to be overlapped with the pervious EIA factors. Accordingly, additional studies would be required for finding out more reasonable connection between assessment factors during any SEA progress.

• Journal of Environmental Impact Assessment
• /
• v.25 no.1
• /
• pp.41-50
• /
• 2016

Environmental impact assessment has been implemented for more than 30 years in Korea. During that period, various amendments were carried out about target plan and assessment factors. However, in current environmental impact assessment act, only a few factors has been considered for soil environment assessment. This study analyzes the national and foreign environmental impact assessment guidelines on soil related factors and figures out the problems and implications of Korean environmental impact assessment. In Korea, water quality, topography and geology, hydraulics and hydrology, and soil contamination were analyzed as a soil related factors. The main assessment targets were pollution related factors such as soil pollution levels, amount of rainfall runoff, and non-point sources. However, in the case of foreign guidelines, soil compaction, soil sealing, and soil salinization is being analyzed for evaluating function and quality of soil environment. The revision of soil-related factors are needed for sustainable development of Korea.

• Korean Journal of Remote Sensing
• /
• v.32 no.6
• /
• pp.657-672
• /
• 2016

Coastal erosion happens frequently in many different types. To control coastal erosion zone effectively and establish response plans, we need to accumulate data indicating topography changes through monitoring the erosion situation continuously. UAV photogrammetric systems, which can fly autonomously at a low altitude, are recommended as an economical and precision means to monitor the coastal zones. In this study, we aim to verify the accuracy of the generated orthoimages and DEM as a result of processing the UAV data of a coastal zone by comparing them with various reference data. We established a verification routine and examined the possibilities of applying the UAV photogrammetric systems to monitoring coastal erosion by checking the analyzed accuracy by the routine. As a result of verifying the generated the geospatial information from acquired data under various configurations, the horizontal and vertical accuracy (RMSE) were about 2.7 cm and 4.8 cm respectively, which satisfied 5 cm, the accuracy required for coastal erosion monitoring.

• Tribology and Lubricants
• /
• v.28 no.6
• /
• pp.265-271
• /
• 2012

In the preceding Part I study, for improving the unbalance response vibration of a large PRT motor-generator rotor fundamentally by design, a series of design analyses were carried out for bearing improvement by retrofitting from original plain partial journal bearings, applied for operation at a rated speed of 1,800 rpm, to final tilting pad journal bearings. To satisfy evenly key basic lubrication performances such as the minimum lift-off speed and maximum oil-film temperature, a design solution of 5-pad tilting pad journal bearings and maximizing the direct stiffness by about two times has been achieved. In this Part II study, a detailed rotordynamic analysis of the large PRT motor-generator rotor-bearing system will be performed, applying both the original plain partial journal bearings and the retrofitted tilting pad journal bearings, to confirm the effect of rotordynamic vibration improvement after retrofitting. The results show that the rotor unbalance response vibrations with the tilting pad journal bearings are greatly reduced by as much as about one ninth of those with the plain partial journal bearings. In addition, for the tilting pad journal bearings there exist no critical speed up to the rated speed and just one instance of a concerned critical speed around the rated speed, whereas for the plain partial journal bearings there exist one instance of a critical speed up to the rated speed and two instances of concerned critical speeds around the rated speed.

• The Journal of Internal Korean Medicine
• /
• v.27 no.4
• /
• pp.962-968
• /
• 2006

Background : Liver cirrhosis is a disease of the liver in which normal cells are replaced by scar tissue. This condition results in the failure of the liver to perform many of its usual functions. Liver cirrhosis includes ascites, jaundice, portal hypertension, varices etc. Objectives : This study was to see if there is a decrease in ascites of liver cirrhosis to under acupuncture and herbal treatment to test their validity. Methods : Measuring the response to treatment of ascites by giving pyengwie-san hap wieryungtang gamibang and treating the patient with acupuncture, these clinical symptoms were observed: weight, abdominal circumference, abdominal SONO, chest X-ray, and lab findings. Results : Over 18 days the daily average loss of weight and abdominal circumference 0.43kg and 0.56cm, respectively. Lab findings of liver functions showed improvement. Conclusions : This report shows a role for acupuncture and herbal treatment for treating ascites in liver cirrhosis.

• Korean Journal of Pharmacognosy
• /
• v.49 no.3
• /
• pp.270-277
• /
• 2018

Pyungwi-san has been used to treat the digestive system diseases, physconia, nausea, anorexia, and dyspepsia in Korea. In this study, an ultra-performance liquid chromatography-electrospray ionization-mass spectrometry (UPLC-ESI-MS/MS) method was optimized for simultaneous determination of the 14 marker components, spinosin, liquiritirn apioside, liquiritin, narirutin, 6'''-feruloylspinosin, hesperidin, liquiritigenin, glycyrrhizin, 6-gingerol, atractylenolide III, honokiol, atractylenolide II, magnolol, and atractylenolide I in Pyungwi-san extract. All analytes were separated on a Waters Acquity UPLC BEH $C_{18}$ analytical column ($2.1{\times}100mm$, $1.7{\mu}m$) with maintained at $45^{\circ}C$. The mobile phase consisted of 0.1% (v/v) aqueous formic acid and acetonitrile. The MS conditions were as follows: capillary voltage 3.3 kV, extractor voltage 3.0 V, RF lens voltage 0.3 V, source temperature $120^{\circ}C$, desolvation temperature $300^{\circ}C$, desolvation gas 600 L/h, cone gas 50 L/h and collision gas 0.14 mL/min. The coefficient of determination of 14 analytes was 0.9989-1.0000. The limits of detection and quantification values of the all analytes were 0.04-2.56 and 0.13-7.69 ng/mL, respectively. As a result of the analysis using the established LC-ESI-MS/MS method, the 5 components, spinosin, 6'''-feruloylspinosin, atractylenolide III, II, and I derived from Zizyphi Fructus and Atractylodis Rhizoma, were not detected in this extract. On the other hand, the 9 components except for the 5 components were 4.15-498.87 mg/kg in lyophilized Pyungwi-san extract. Among these components, glycyrrhizin, marker compound of Glycyrrhizae Radix et Rhizoma, was detected the most amount as a 498.87 mg/kg.

• Journal of the Korean Society of Manufacturing Technology Engineers
• /
• v.7 no.3
• /
• pp.99-103
• /
• 1998

The curved surface machined by plate end mill causes a excess non-cutting volume, in these cases ball end mill is used for the curved surfaces. This study is aimed to obtain the optimum cutting conditions of various cutting speed, table speed, tool diameter, radius of curvature roughness on the conditions of various cutting speed, tool diameter, radius of curvature when machining the curved surface using the ball end mill. After designing curve rates, obtaining NC data by CAD/CAM system through CC-Cartesian method and transferred the data through DNC system, we machined the specimens by the CNC machining center, The surface roughness of specimens was measured by surface roughness tester and CNC 3D coordinate measuring machine. The cutting condition were the same as follow velocity; 15, 20, 25 30m/min, feed rate;40, 60, 80, 100m/min and radius of curvature; 30,40,50,60mm, tool diameters; ø8, ø12, ø16, ø 20mm. Analizing the working results, we can acquire the optimum cutting condition of curved specimen at the cutting velocity of 20~25m/min and the feed rate of 80mm/min. As the same cutting condition the best surface roughness was showed at ø16mm of the tool diameter. But the tool diameter was smaller than ø8mm. we could improve for the surface roughness by controlling the cusp.