• Journal of Welding and Joining
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• 제31권5호
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• pp.15-19
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• 2013

In order to reduce a grand compute time in prediction of welding distortion and residual stress by 3D thermal elastic plastic analysis, idealization of welding that is methods to heat input simultaneously in all weld metal on the same welding direction is carried out on two weld joints(butt welding and fillet welding). Then, the accuracy of acquired results is investigated through the comparison of the high accuracy prediction results. The thermal conduction analysis results by idealization of welding, the temperature is raised accompany with beginning of heat input because all of weld metal is heated input at the same time. On the other side, the temperature witch predicted with high accuracy is raised at the moment heating source passes the measuring points. So, there is difference of time between idealization of welding and considering of moving heat source faithfully. However, temperature history by idealization of welding is well simulated a high accuracy prediction results.

• 대한자원환경지질학회:학술대회논문집
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• 대한자원환경지질학회 2005년도 춘계 학술발표회 논문집
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• pp.148-151
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• 2005

Field-scale DNAPL dissolution is controlled by the topology of DNAPL distributions with respect to the velocity field. A high resolution percolation model was developed and employed to simulate the distribution of DNAPL within source zones. Statistically anisotropic permeability values and capillary parameters were generated for 10${\times}$10${\times}$10 m domains at a resolution of 0.05 to 0.1 m for various statistical properties. TCE leakage was simulated at various rates and the distribution of residual DNAPL in 'fingers' and 'lenses' was computed. Variations in finger and lens geometries, frequencies, average DNAPL saturations, and overall source topology were predicted to be strongly influenced by statistical properties of the medium as well as by injection rate and fluid properties. Model results were found to be consistent with observations from controlled DNAPL release experiments reported in the literature. The computed distributions of aquifer properties and DNAPL were utilized to perform high-resolution numerical simulations of groundwater flow and dissolved transport. Simulations were performed to assess the effect of grout or foam injection in bore holes within the source zone and of shallow point-releases of fluids with various properties on dissolution in DNAPL dissolution rate, even for widely spaced injection points. The results indicate that measures that induced partial flow reductions through DNAPL source zones can significantly decrease dissolution rates from residual DNAPL. The benefit from induced partial flow reductions is two-fold: 1) local flow reduction in DNAPL contaminated zones reduces mass transfer rates, and 2) contaminant flux reductions occur due to the decrease in groundwater velocity

• 대한치과보철학회지
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• 제23권1호
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• pp.97-112
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• 1985

The purpose of this study was to evaluate the stress patterns developed in supporting structures by removable partial denture with attachment retainers. The attachments tested were Dalbo(miniature) attachment, resilient Ceka attachment, rigid Ceka attachment, precision and sleeve attachment, and R.P.I. clasp as a contrast. 3-dimensional photoelastic stress analysis was used to record the isochromatic and isoclinic fringe patterns and to calculate principal stress components at measuring points. The results showed that: 1. The maximum compressive stress on residual ridge was produced under the loading point with Dalbo and resilient Ceka attachment, distal to the loading point with rigid Ceka and precision and sleeve attachment, and mesial to the loading point with R.P.I. clasp. 2. The Dalbo attachment produced the most stress on residual ridge, and the least stress on abutment teeth. and resilient Ceka attachment showed favorable stress distribution. 3. Rigid Ceka attachment produced higher compressive stress on buccal. alveolar crest, and precision and sleeve attachment produced higher compressive stress on distal alvelolar crest and mesial surface of the root apex in abutment teeth. 4. R.P.I. clasp produced higher compressive stress on mesial alveolar crest.

• 한국해양공학회지
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• 제21권3호
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• pp.71-76
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• 2007

Recently, many industries have been employing the application of laser beam welding, due to the resulting high welding quality, such as smaller width of melting and heat affective zone, smaller welding deformation, and fine grains of weldment, compared to arc welding. However, in order to appropriately utilize this welding process with steel structure, the characteristics of welding residual stresses and fracture toughness in welded joints are to be investigated for reliability. Therefore, in this study, the mechanical properties of weldments by arc and laser welding are investigated using FEM to confirm the weldability of laser welding to the general structural steel (HT50). The Charpy impact test and 3-points bending CTOD test are carried out in the range of temperatures between $-60^{\circ}C\;and\;20^{\circ}C$, in order to understand the effect on the fracture toughness of weldments. From the research results, it has been found that the maximum residual stress appears at the center of plate thickness, and that the fracture toughness is influenced by strength mis-match.

• 한국인터넷방송통신학회논문지
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• 제16권5호
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• pp.91-97
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• 2016

본 논문에서는 통신 채널에서 발생되는 찌그러짐에 의한 부호간 간섭을 보상하기 위한 FC-MMA (Fast Convergence-Multiple Modulus Algorithm)과 RMMA (Region based Multiple Modulus Algorithm) 등화 알고리즘의 성능을 평가하였다. 적응 등화를 위한 오차 신호를 얻기 위하여 FC-MMA 는 신호 심볼의 레벨수를 고려한 수정된 dispersion constant를 이용하지만, RMMA에서는 모든 신호점들이 존재하는 지역을 4개로 분할한 후 이를 기반으로 신호점을 축소한다. 이와 같이 오차 신호를 얻는 상이한 원리를 적용하여 적응 등화기의 탭 계수 갱신을 수행하게 되지만 이들은 각기 다른 등화 성능을 갖게 되므로, 논문에서는 이들의 성능을 컴퓨터 시뮬레이션을 통해 확인한다. 성능 비교를 위한 지수로는 등화기 출력 신호 성상도, 수렴 특성을 나타내는 잔류 isi, 최대 찌그러짐 및 채널의 신호대 잡음비에 따른 SER을 사용하였으며, 시뮬레이션 결과 RMMA는 정상 상태 이후 출력 신호 성상도와 잔류 isi 및 최대 찌그러짐과 SER 성능이 FC-MMA보다 우월하지만, 정상 상태에 도달하기 위한 수렴 속도에서는 FC-MMA가 빠름을 확인하였다.

• 한국항행학회논문지
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• 제22권5호
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• pp.375-383
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• 2018

정지한 객체의 측위에 사용되던 Network RTK (real time kinematics) 기술을 이동형 항체의 항법에 적용하기 위해서는 보정정보와 함께 사용자의 성능을 대표할 수 있는 지표가 함께 제공되어야 한다. 이를 위하여 본 논문에서는 I95 (ionospheric index 95) / G95 (geodetic index 95), SBI (semivariance based index), RIU (residual interpolation uncertainty) 등의 지표 도출 알고리즘을 분석하고 이를 국토지리정보원의 기준국 원시 데이터와 VRS (virtual reference station) 사용자에 적용함으로써 정밀 항법 성능 지표로의 활용 가능성을 타진하였다. 24시간 데이터를 처리한 결과 보정정보의 비선형성을 나타낼 수 있는 RIU 지표와 Network RTK 사용자의 위치 정확도와의 상관성이 0.52로 타 지표에 비해 훨씬 높은 것으로 나타났으므로 향후 이동 항체의 항법 성능 지표로 사용이 가능할 것으로 예상된다.

• Asian-Australasian Journal of Animal Sciences
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• 제3권4호
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• pp.263-267
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• 1990

The fat thicknesses of twenty-eight Japanese Black beef steers were measured with an ultrasonic device at eleven points on the cattle prior to slaughter and side dissection. The relation between live fat thickness and both weight and percentage of fat and lean in the carcass was examined. Fat thickness obtained from nine points of the chest, flank and rump regions was found to relate significantly (P<0.01) to both weight and percentage of fat. However, shoulder fat thickness measurements were not significantly related to the weight or percentage of fat or lean in the carcass. Addition of live fat thickness to animal age or live weight as an independent variable markedly improved the precision of multiple regression equations for predicting weight of fat and lean, and percentage of fat. In predicting the percentage of lean, both animal age and body weight were not employed in the multiple regression equation. The residual standard deviation for predicting percentage of fat and lean were 1.93 and 1.87, respectively. The ultrasonic measurement of fat thickness if supposed to be useful to the prediction of carcass composition of beef cattle.

• 한국화재소방학회논문지
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• 제17권2호
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• pp.1-5
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• 2003

현재 고감도의 누전차단기(RCD)와 배선용차단기(WCCB)및 퓨즈(Fuse)설치를 통하여 누전·단락사고와 과전류 발생시 차단기능을 부여함으로써, 전기화재의 발생을 억제하고 있으나, 매우 미흡한 실정이다. 특히 소손사고와 접속·접촉불량사고 및 순간단락사고 발생시는 구조적으로 차단이 불가능할 것으로 사료되며, 이에 대한 연구가 필요하다. 따라서 본 논문에서는 상기의 상황에 기초해서 가장 일반적으로 사용되고 있는 열동형 누전차단기(단락보호, 과부하 겸용)의 동작원리와 시험항목 및 기준분석을 통하여 문제점을 제시하고자 한다. 또한 저압 배선선로의 소손사고와 접속·접촉불량사고 및 순간단락사고 발생시 전등(R)부하 및 전동기(R-L)부하에 따른 누전차단기의 동작특성을 실제 실험을 통하여 검토하고자 한다.

• 한국측량학회:학술대회논문집
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• 한국측량학회 2006년도 춘계학술발표회 논문집
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• pp.181-185
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• 2006

Image co-registration is the process of overlaying two images of the same scene, one of which represents a reference image, while the other is geometrically transformed to the one. In order to improve efficiency and effectiveness of the co-registration approach, the author proposed a pre-qualified area matching algorithm which is composed of feature extraction with canny operator and area matching algorithm with cross correlation coefficient. For refining matching points, outlier detection using studentized residual was used and iteratively removes outliers at the level of three standard deviation. Throughout the pre-qualification and the refining processes, the computation time was significantly improved and the registration accuracy is enhanced. A prototype of the proposed algorithm was implemented and the performance test of 3 Landsat images of Korea showed: (1) average RMSE error of the approach was 0.436 Pixel (2) the average number of matching points was over 38,475 (3) the average processing time was 489 seconds per image with a regular workstation equipped with a 3 GHz Intel Pentium 4 CPU and 1 Gbytes Ram. The proposed approach achieved robustness, full automation, and time efficiency.

• Nuclear Engineering and Technology
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• 제54권8호
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• pp.3166-3175
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• 2022

The most numerical investigations of the thermal-hydraulic phenomena following the loss of the residual heat removal capability during the mid-loop operation of the pressurized water reactor were performed according to simplifications and are not sufficiently accurate. To perform more accurate and more reliable predictions of thermal-hydraulic accidents in a nuclear power plant using computational fluid dynamics codes, a more detailed methodology is needed. Modelling results identified that thermal stratification and natural convection are observed. Temperatures of lower monitoring points remain low, while temperatures of upper monitoring points increase over time. The water in the heated region, in the upper unheated region and the pipe region was well mixed due to natural convection, meanwhile, there is no natural convection in the lower unheated region. Water temperature in the pipe region increased after a certain time delay due to circulation of flow induced by natural convection in the heated and upper unheated regions. The modelling results correspond to the experimental data. The developed computational fluid dynamics methodology could be applied for modelling of two-component single/two-phase natural convection and thermal stratification phenomena during the mid-loop operation of the pressurized water reactor or other nuclear and non-nuclear installations at similar conditions.