• Journal of Korean Tunnelling and Underground Space Association
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• v.21 no.5
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• pp.717-733
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• 2019

In this study, lining thickness distribution and its behind state (particularly, its void state) were analyzed using the GPR survey data performed on three currently operating NATM tunnels. Results of GPR analysis showed that void areas were mostly detected between concrete lining and primary support, particularly, near the crown of the tunnels. The lining thickness in the left-hand side of the tunnel was different from that of the right-hand side by 8.6~253.5 mm when measured in transverse direction. It was also found that longitudinal cracks were prevailed in the area lining thickness was sharply changed. Longitudinal thickness distribution at the crown was also studied and tested by performing 3 goodness-of-fit tests in order to find the most suitable thickness distribution. Normal distribution (or similar distribution) fit most suitably to the measured data if the measured average thickness was larger than designed one; Gamma and/or Inverse Gauss distribution fit to the measured data reasonably well if the measured average thickness was less than the designed value of thickness. Since actual lining thickness can be a potential index when assessing the state and safety of the unreinforced NATM tunnel lining, measuring of the lining thickness with GPR survey might be needed rather than assuming the thickness is always constant and same with the designed value.

• 열병합발전
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• s.50
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• pp.18-22
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• 2006

The tilting pad journal bearing has widely used to support high pressure/high rotating turbine rotors owing to their inherent dynamic stability characteristics. However, fatigue damages in the upper unlcaded pads and the break of locking pins etc. by pad spragging were continuously taken place in the actual steam turbines. The purpose of this paper is to develope a new bearing model that can prevent bearing damage problem effectively by pad spragging in a tilting pad journal bearing. A new bearing model which has a wedged groove is suggested from the studies of spragging mechanism performed by previously research works. The spragging characteristics of the upper unloaded pad are studied experimentally in order to verify the reliability of a new bearing model. It can be known that the phenomenon of pad spragging nearly does not occur in the new bearing model under the various experimental conditions. And it is observed that any kinds of bearing failures by pad spragging does not detect in the application of actual steam turbines.

• 한국정보디스플레이학회:학술대회논문집
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• 2004.08a
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• pp.1233-1235
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• 2004

We have designed High Performance Prism LGP in 17 inch TFT-LCD. In test result to embody high brightness BLU in case of LGP of base and upper surface with 17 inch, thickness 8mm adding prism construct, it is superior brightness improvement than previous that of printing form about some 20% and in this course to embody actual material it succeeded prism LGP production by 17 inch injection form process.

• The Transactions of the Korean Institute of Electrical Engineers P
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• v.61 no.2
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• pp.93-96
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• 2012

We have designed high performance prism light-guide plate (LGP) in 17 inch TFT-LCD. In test result to embody high brightness BLU in case of LGP of base and upper surface with 17 inch, thickness 8mm adding prism construct. Using optical simulation, we forecast the brightness and uniformity in LGP with prism structure. And we adopted novel injection mold method and Nickel stamper to make actual evolution sample. Novel injection mold process has steady heating time zone in heat cycle time of injection mold process. For this novel heat cycle control, we achieved above 90[%] height prism structure as our design. It is superior brightness improvement than previous that of printing form about some 20[%] and in this course to embody actual material it succeeded prism LGP production by 17 inch injection form process.

• Journal of Welding and Joining
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• v.20 no.4
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• pp.538-543
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• 2002

M/S TB(Mash Seam Tailored Blank) is a production method for blanks by welding together blanks of different material, thickness and coating, and is an attractive method for manufacturing car body because it makes parts lighter and can save the cost and time to manufacture. However, there have not been quantified criteria to evaluate the quality of TB weld. This study introduced FHR (failure height ratio) in order to assess formability or/and weldability of the M/S welds and the applicability of FHR was confirmed by actual auto body forming and FLD tests. Furthermore, a new parameter, HN(heat number) based on the heat input of "$Q=I^2Rt$" was proposed and assessed. It was found that the concept of HN could be utilized to evaluate the soundness of M/S welds without any destructive tests.ive tests.

• Journal of Korea Foundry Society
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• v.28 no.4
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• pp.190-194
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• 2008

Thin-walled die casting of aluminum notebook computer housing with less than 1mm thickness was investigated by using computational solidification simulation and actual casting experiment. Three different types of gate design, finger, tangential and split type, were used and the results showed that sound thin-walled die casting was possible with tangential and split type gating design because those gates allowed aluminum melt flowed into the thin-wall cavity uniformly and split type gating system was preferable gating design than tangential type at the point of view of soundness of casting and distortion generated after solidification. Also, solidification simulation agreed well with the actual die-casting and the casting showed no casting defect and distortion.

• Transactions of Materials Processing
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• v.8 no.2
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• pp.200-207
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• 1999

To increase dimensional accuracy of strip width, model to compensate width spread during roughing mill has been developed. To measure the amount of width spread during the production rolling more precisely, special roughing rolling procedures for the horizontal rolling and dog-bone rolling were designed in the actual production mill. From the operational data analysis, it is known that the prime factors influencing on the width spread were strip width, strip thickness, edging amount, number of pass and type of edger roll etc., Based upon the statistical analysis of rolling data, new models which can predict width spread during horizontal rolling and dog-bone rolling were developed and tested on the actual processing conditions for the reliability. The application test showed that newly developed model gave fairly accurate predictions on the width spread during roughing passes.

• Steel and Composite Structures
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• v.13 no.3
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• pp.225-238
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• 2012

Steel structural elements with web-tapered I cross section, are usually made of welded thin plates. Due to the nonrectangular shape of the element, thin web section may be obtained at the maximum cross section height. The buckling strength is directly influenced by lateral restraining, end support and initial imperfections. If no lateral restraints, or when they are not effective enough, the global behaviour of the members is characterized by the lateral torsional mode and interaction with sectional buckling modes may occur. Actual design codes do not provide a practical design approach for this kind of elements. The paper summarizes an experimental study performed by the authors on a relevant number of elements of this type. The purpose of the work was to evaluate the actual behaviour of the web tapered beam-columns when applying different types of lateral restraints and different web thickness.

• Geomechanics and Engineering
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• v.13 no.6
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• pp.997-1010
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• 2017

The black box model is a relatively new option for nonlinear dynamic system identification. It can be used for prediction problems just based on analyzing the input and output data without considering the changes of the internal structure. In this paper, a black box model was presented to solve unconstrained overlying strata movement problems in coal mine production. Based on the black box theory, the overlying strata regional system was viewed as a "black box", and the black box model on overburden strata movement was established. Then, the rock mechanical properties and the mining thickness and mined-out section area were selected as the subject and object respectively, and the influences of coal mining on the overburden regional system were discussed. Finally, a corrected method for height prediction of the fractured zone was obtained. According to actual mine geological conditions, the measured geological data were introduced into the black box model of overlying strata movement for height calculation, and the fractured zone height was determined as 40.36 m, which was comparable to the actual height value (43.91 m) of the fractured zone detected by Double-block Leak Hunting in Drill. By comparing the calculation result and actual surface subsidence value, it can be concluded that the proposed model is adaptable for height prediction of the fractured zone.

• Transactions of the Korean Society of Automotive Engineers
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• v.7 no.9
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• pp.112-118
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• 1999

Shrinkage behavior was investigated to obtain more accurate dimensions of injected molding parts for free and restricted shrinkage conditions. various parameters for metal inserted injection process, such as thickness of resin, holding pressure and time, mo이 temperature and restriction condition of mold, were considered for the analysis of shrinkage phenomena. For numerical analysis, MOLDFLOW software was used to find the deterministic parameters of filling time, temperature, pressure and holding time. Also , experimental shrinkage effects were measured through actual injection molding process and the resin thickness was under controlled as 3 mm , 5 mm, and 7mm for the shapes of plastic gear made of Polymide(PA) and Polyxymethlene(POM). The main parameters of these injection processes were found to be holding pressure, holding time and mold temperature in the case of metal inserted molding.