• Nuclear Engineering and Technology
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• v.52 no.12
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• pp.2949-2957
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• 2020

Fatigue crack growth model has been developed for dissimilar metal weld joints of a piping component under cyclic loading, where in the crack is located at the center of the weld in the circumferential direction. The fracture parameter, Stress Intensity Factor (SIF) has been computed by using principle of superposition as K_H + K_M. K_H is evaluated by assuming that, the complete specimen is made of the material containing the notch location. In second stage, the stress field ahead of the crack tip, accounting for the strength mismatch, the applied load and geometry has been characterized to evaluate SIF (K_M). For each incremental crack depth, stress field ahead of the crack tip has been quantified by using J-integral (elastic), mismatch ratio, plastic interaction factor and stress parallel to the crack surface. The associated constants for evaluation of K_M have been computed by using the quantified stress field with respect to the distance from the crack tip. Net SIF (K_H + K_M) computed, has been used for the crack growth analysis and remaining life prediction by Paris crack growth model. To validate the model, SIF and remaining life has been predicted for a pipe made up of (i) SA312 Type 304LN austenitic stainless steel and SA508 Gr. 3 Cl. 1. Low alloy carbon steel (ii) welded SA312 Type 304LN austenitic stainless-steel pipe. From the studies, it is observed that the model could predict the remaining life of DMWJ piping components with a maximum difference of 15% compared to experimental observations.

• Steel and Composite Structures
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• v.29 no.6
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• pp.717-734
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• 2018

This paper presents the flexural performance of steel beam-to-column joints composed of hollow structural section beams and columns. A finite element (FE) model was developed incorporating geometrical and material nonlinearities to evaluate the behaviour of joints subjected to bending moments. The numerical outcomes were validated with experimental results and compared with EN1993-1-8. The demountability of the structure was discussed based on the tested specimen. A parametric analysis was carried out to investigate the effects of steel yield strength, end-plate thickness, beam thickness, column wall thickness, bolt diameter, number of bolts and location. Consequently, an analytical model was derived based on the component method to predict the moment-rotation relationships for the sub-assemblies with extended end-plates. The accuracy of the proposed model was calibrated by the experimental and numerical results. It is found that the FE model is fairly reliable to predict the initial stiffness and moment capacity of the joints, while EN1993-1-8 overestimates the initial stiffness extensively. The beam-to-column joints are shown to be demountable and reusable with a moment up to 53% of the ultimate moment capacity. The end-plate thickness and column wall thickness have a significant influence on the joint behaviour, and the layout of double bolt-rows in tension is recommended for joints with extended end-plates. The derived analytical model is capable of predicting the moment-rotation relationship of the structure.

• Journal of the Korean Orthopaedic Association
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• v.54 no.5
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• pp.377-383
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• 2019

The biomechanics study of the hip is aims to understand and explore the dynamic principles of weight transfer through the hip joint. This basic science knowledge can be applied in a variety of areas, including degenerative joint diseases and hip replacement arthroplasty. In particular, understanding of the biomechanics of the hip has led to the development of materials, design and fixation of implants, and it can be applied in various areas, such as the selection of surgical methods and the location of the implant. Moreover, it is essential to have good knowledge of the biomechanics of the hip to achieve better clinical results for patients. Therefore, this paper introduces the basic knowledge and biomechanical characteristics of a normal hip and hip replacement arthroplasty, which are needed to approach the biomechanics of the hip.

• Journal of the Korean Society for Nondestructive Testing
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• v.35 no.3
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• pp.179-184
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• 2015

In this study, the flap fatigue test of a 48 m long wind turbine blade was performed for 1 million cycles to evaluate the characteristics of acoustic emission signals generated from fatigue damage of the wind blades. As the number of hits and total energy continued to increase during the first 0.6 million cycles, blade damage was constant. The rise-time result showed that the major aspects of damage were initiation and propagation of matrix cracks. In addition, the signal analysis of each channel showed that the most seriously damaged sections were the joint between the skin and spar, 20 m from the connection, and the spot of actual damage was observable by visual inspection. It turned out that the event source location was related to the change in each channel's total energy. It is expected that these findings will be useful for the optimal design of wind turbine blades.

• Archives of Plastic Surgery
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• v.32 no.4
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• pp.447-453
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• 2005

The coverage of soft tissue defects around the knee joint or upper one third of lower leg presents a difficult challenge to the reconstructive surgeon. Various reconstructive choices are available depending on the location, size and depth of the defect. The authors present their clinical application of a medial sural artery perforator island flap as a useful alternative method for upper one third of lower leg and knee reconstruction. From 2002 to 2004, we operated total 4 patients (total 4 flaps) using the medial sural artey perforator island flap for coverage of the defect on upper one third of lower leg and knee, of 4 patients, 3 patients was men and one was woman. Average patient age was 54.6 years. The largest flap obtained was 10x8cm2. Postoperative follow up of the patients ranged from two to 33 months. In two cases, defects was located on upper one third of lower leg and in other two cases, defects were on the knee. All four cases had bone exposure open wound. In angiography, 2 cases had injured in the anterior tibial artery, 1 case had injured in the posterior tibial artery. There were no diabetes or other vascular disease. All 4 flaps were survived completely, without minor complications such as venous congestion and hematoma. Donor morbidity was restricted substantially to the donor linear scar. There were no functional impairment. As the main advantages of the medial sural perforator island flap, it ensures constant location and reliable blood supply without sacrificing any main source artery or damaging underlying muscle. This procedure is valuable extension of local flap for defect coverage with minimal functional deficit donor site and good aesthetic result on the defect. We consider it as one of the useful methods of the upper one third of lower leg and knee reconstruction.

• Journal of the Korea Institute of Military Science and Technology
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• v.21 no.4
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• pp.447-455
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• 2018

If a hidden enemy is shooting, there is a threat against soldiers in recent conflicts. This paper aims to improve the localization of a muzzle using microphone array. Gunshot noise can provide information about the location of muzzle with two signals, the muzzle blast from the gun barrel and the projectile sound from the bullet. Two signals arrive to the microphone array with different arrival time and angle. If the arrival angles of the two signals are estimated, distance between sniper location and the microphone array can be calculated by using geometric principles. This method was established in 2003 by Pare. But this method has a limitation that it cannot calculate the distance when the arrival angles of the two signals are same. Also it has an error when the angle difference of arrival is small. In order to overcome this limitation, a new method is proposed that uses the change of characteristic of the projectile sound with respect to vertical distance from the trajectory. The proposed method estimates the distance correctly when the arrival angle of two signals are same, and when the angle difference between two signals is increased, the estimation error increases with respect to the angle. Therefore these two methods can be selected according to the angle difference between two signals to estimate the distance of the muzzle. Below the threshold of the angle difference, the proposed method can be used to estimate distance with smaller error than the existing method. This was demonstrated by shooting tests using actual sniper rifles.

• Journal of the Korea Computer Graphics Society
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• v.26 no.4
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• pp.1-8
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• 2020

Motion synthesis using physics-based controllers can generate a character animation that interacts naturally with the given environment and other characters. Recently, various methods using deep neural networks have improved the quality of motions generated by physics-based controllers. In this paper, we present a control policy learned by deep reinforcement learning (DRL) that enables Luxo, the mascot character of Pixar animation studio, to run towards a random goal location while imitating a reference motion and maintaining its balance. Instead of directly training our DRL network to make Luxo reach a goal location, we use a reference motion that is generated to keep Luxo animation's jumping style. The reference motion is generated by linearly interpolating predetermined poses, which are defined with Luxo character's each joint angle. By applying our method, we could confirm a better Luxo policy compared to the one without any reference motions.

• The Journal of the Korean bone and joint tumor society
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• v.3 no.1
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• pp.1-8
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• 1997

Osteosarcoma is the most common primary bony malignancy and its survivorship has been progressed markedly through refined chemotherapy and surgery. But still there are many non-responders and analysis of prognostic factors may be helpful for them. Two hundred and sixty-six patients were enlisted between Mar, 1985 and Sep. 1994. Among them our inclusion criteria were: 1)primary, nonmetastatic classical osteosarcoma 2)extremity in location 3)no prior treatment at other institute and completed neoadjuvant chemotherapy and surgery according to our protocol. One hundred and eleven cases were eligible. Analyzed factors were:age, sex, location, tumor size, and pathologic response. Statistical methods were log-rank test for univariate and Cox's test for multivariate analysis. Male to female ratio was 69:42 with an average age of 17.2 years. Locations of tumor were distal femur 59, proximal tibia 29, and proximal humerus 8. Tumor size were measured by its maximal diameter and 48 cases were above 10cm and 47 cases were below 10cm. For pathologic response, 57 cases showed more than 90% and 54 cases were less than that. Limb salvage procedure was 101 cases and amputation was 10 cases and their local recurrence rate were 3.6%. Average follow-up period was 24(9-78.2) months and their final status was CDF 86, AWD 8, NED 5, and DOD 12 cases. In univariate study: type of operation(p=0.005), tumor size(p=0.005), and pathologic response(p=0.02) were significant variables. Pathologic response(p=0.03) and type of operation(p=0.01) were meaningful prognostic factors on multivariate analysis. But the latter result was interpreted as a bias, so pathologic response remained as a sole meaningful prognostic factor. More aggressive chemotherapy will be needed to improve the survival.

• The Journal of the Korean bone and joint tumor society
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• v.3 no.2
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• pp.89-97
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• 1997

Twenty hundred and five out of 266 patients who were registered in Korea Cancer Center Hospital from Mar. 1985 to Jan. 1994, were analyzed in the aspect of survival and local recurrence. Fifty one patients were excluded due to inadequate data and follow up. Prognostic factors for survival were evaluated statistically. One hundred and four cases were male, 101 female. Average age was 39.7(range 1 to 77) year with a peak incidence around 4th decade. The most frequent diagnosis was malignant fibrous histiocytoma(MFH)(24.1%). Liposarcoma, synovial sarcoma, rhabdomyosarcoma, malignant peripheral nerve sheath tumor and fibrosarcoma were relatively common diagnostic entities, in decreasing order. In location, extremity was 179(87.3%) and trunk 26(12.7%). Average follow up period was 7.5 years(6 months to 10 years). Actuarial 5 years and 10 years survival rate were 64.0% and 40.8% respectively. In univariate analysis with log-lank test, significant differences in survival rate were noted in histopathological diagnosis, size(10 cm), stage and metastasis. Age, sex, tumor location, tumor depth and local recurrence didn't affect the survival rate. Adjuvant chemotherapy and/or radiotherapy did not affect overall survival rate, but lowered the local recurrence rate when compared with surgery only. Surgical margin did not affect the survival rate, but local recurrence rate was different according to each margin; 5.7% in more than wide; 39.5% in marginal; and 60.0% in intralesional excision. In multivariate analysis for results of univariate analysis with Cox's propotional model, metastasis was a meaningful factor for survival of soft tissue sarcoma.

• International Area Studies Review
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• v.15 no.2
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• pp.3-23
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• 2011

Existing studies have argued that, compared to the 1990s, the Japanese foreign direct investment (FDI) in the 2000s became multi-faceted in terms of investment motivation, ownership structure and entry mode, and diversification strategy. We have conducted a cross-sectional analysis and compared our results with the recent findings. We have found that the Japanese FDI in the mid 2000s became globally focused and regionally diversified. Ownership strategy and entry mode of the Japanese FDI in the Asian countries shows a remarkable shift from joint venture to wholly-owned subsidiary. In contrast, the preference of greenfield investments was observed consistently across regions. It seems that, after the Asian financial crisis, the Japanese firms began to re-optimize global FDI strategy and to regionally differentiate investments.