• Korean Journal of Radiology
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• v.24 no.12
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• pp.1241-1248
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• 2023

Objective: To evaluate the role of percutaneous pancreatic stent placement in postoperative pancreaticojejunostomy stenosis (PJS). Materials and Methods: This retrospective single-center study included seven procedures in five patients (four males and one female; median age, 63 years) who underwent percutaneous pancreatic stent placement for postoperative PJS between January 2005 and December 2021. The patients were referred to interventional radiology because of unfavorable anatomy or bowel abnormalities. The pancreatic duct was accessed under ultrasound and/or computed tomography guidance. A stent was placed after balloon dilatation of the PJS. Moreover, plastic stents were placed for the first two procedures, whereas bare-metal stents were used for the remaining five procedures. Technical success was defined as the successful placement of stents for the PJS, meanwhile, clinical success was defined as the normalization of pancreatic enzymes without recurrence of pancreatitis. Results: Pancreatic duct access and stent placement were successfully performed in all patients (technical success rate: 100%). All the procedures initially yielded clinical success. However, recurrence of pancreatitis was observed after two procedures that used plastic stents because of stent migration at 0.3 and 3 months after the procedure. In contrast, no instances of recurrent pancreatitis were noted after metal stent placement for a follow-up duration of 1-36 months. No serious procedure-related adverse events were observed. Conclusion: Percutaneous pancreatic stent placement may be a viable option for patients with postoperative PJS in whom an endoscopic approach is not feasible. Metal stents may be considered over plastic stents for the management of PJS, considering the possible lower stent migration and infeasibility of frequent endoscopic stent exchange due to the altered anatomy.

• Archives of Plastic Surgery
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• v.51 no.1
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• pp.30-35
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• 2024

Background Breast aesthetics evaluation often relies on subjective assessments, leading to the need for objective, automated tools. We developed the Seoul Breast Esthetic Scoring Tool (S-BEST), a photometric analysis software that utilizes a DenseNet-264 deep learning model to automatically evaluate breast landmarks and asymmetry indices. Methods S-BEST was trained on a dataset of frontal breast photographs annotated with 30 specific landmarks, divided into an 80-20 training-validation split. The software requires the distances of sternal notch to nipple or nipple-to-nipple as input and performs image preprocessing steps, including ratio correction and 8-bit normalization. Breast asymmetry indices and centimeter-based measurements are provided as the output. The accuracy of S-BEST was validated using a paired t-test and Bland-Altman plots, comparing its measurements to those obtained from physical examinations of 100 females diagnosed with breast cancer. Results S-BEST demonstrated high accuracy in automatic landmark localization, with most distances showing no statistically significant difference compared with physical measurements. However, the nipple to inframammary fold distance showed a significant bias, with a coefficient of determination ranging from 0.3787 to 0.4234 for the left and right sides, respectively. Conclusion S-BEST provides a fast, reliable, and automated approach for breast aesthetic evaluation based on 2D frontal photographs. While limited by its inability to capture volumetric attributes or multiple viewpoints, it serves as an accessible tool for both clinical and research applications.

• Maxillofacial Plastic and Reconstructive Surgery
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• v.15 no.4
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• pp.338-345
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• 1993

Mandibular discontinuity defect due to benign tumor, malignant tumor, infection, or truma results in major esthetic and biologic compromise. The primary goal of reconstruction is full restitution of function, which secondarily lead to normalization of the cosmetic deformity. The authors make a clinical study of 61 consecutive bone graft cases for mandibular reconstruction of discontinuity defect which were studied retrospectively using clinical data and radiographic findings. The cases were reviewed to evaluate the clinical success in the period from 1981 to 1990 in the Dept. of Oral & maxillofacial Surgery, Seoul National University Hospital. The criteria of the success in bone graft, are no residual infection, graft in with maintain its integrity, and remain over a half of its original size of graft in the radiographic features. The purpose of this clinical survey is to study of the mandibular discontinuity defects and success rate of free bone graft in mandibular defects. To summarize the clinical study of free bone graft, the main type of autogenous bone graft is iliac bone and corticocancellous type. Overall success rate is 80.3% in 61 followup cases over 6 months. Wire fixation and Extraoral approach has realtively better prognosis than other methods. It showed relatively poor prognosis in symphysis defects than other recipient site.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.39 no.3
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• pp.64-70
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• 2016

The recent development of modern weapon system by SOS (System of System) has required users to have more exact decision making. It is possible to achieve the control of complex weapon system more efficiently and effectively by increasing usability. Accordingly, many studies on graphical display have been conducted for several years in the field of HCI (Human Computer Interaction) and GUI (Graphic User Interface), starting from its design stage. Therefore, this paper focuses on evaluating the system GUI usability and analyzing several important points based on performance model, which is a tool for the evaluation and the improvement of service quality. Performance Model, the main focus of this study, reflects user expectations (which is defined as user importance in this paper). The study consists of four steps. First, 34 checklists are drawn from the existing studies related to GUI usability evaluation by using a heuristic method, and then the checklists are matched with 11 weapon system design factors. Next, the study evaluates the importance of GUI element and the usability of weapon system "A" with the checklists twice respectively. Third, the performance of user importance ($P_i$) and the performance of usability ($P_u$) are calculated by modifying a numerical formula for normalization in this step. Finally, the study compares the approach it takes and the existing usability evaluation method, demonstrating that there is a significant difference between the two methods as a result. In addition, 4 improvement factors are suggested for weapon system "A" as "Shortcut" and "Description of Abbreviation," and so on. Although it is necessary to conduct more studies for higher reliability and validity of the results, this study is meaningful considering it takes a new point of view.

• Korea and Global Affairs
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• v.2 no.2
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• pp.89-130
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• 2018

This paper is to analyse the development of the U.S.-China relationship and pending issues and implications. To this end the paper is composed of 6 chapters titled instruction; the relationship between the US and China in the early and hostile confrontation period; the relationship of US-Chinese approach/normalization period and the relationship in the 1980s and 1990s; the relationship by mid-2010 since the opening of the G2 era; the US-China relations and major pending issues and implications in the era of Trump-Xi Jinping; and conclusion. The rapid growth of China over the past three decades has changed the existing US-centered international order and has triggered competition between the two countries. The United States and China have become the only countries that regularly hold strategic and economic dialogue, and the topic has also developed into a country that discusses not only bilateral relations but also global issues. The issues of US-China cooperation and conflicts encompass global issues as well as bilateral relations issues. For example, the South China Sea, the North Korean nuclear issue and the THAAD, the economic and financial order, and the Taiwan issue. It is not a matter of another country, but a problem that directly or indirectly leads to Korea's diplomacy, security and economy. In order to prevent 'Korea passing' in the US-China relationship, we need a hedging strategy that maintains and strengthens the strong ROK-US security cooperation and harmonious promotion of ROK-China economic cooperation.

• The Journal of the Acoustical Society of Korea
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• v.39 no.2
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• pp.120-130
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• 2020

This paper solves the problem in underdetermined convolutive mixture by improving the disadvantages of the multichannel nonnegative matrix factorization technique widely used in blind source separation. In conventional researches based on Spatial Covariance Matrix (SCM), each element composed of values such as power gain of single channel and correlation tends to degrade the quality of the separated sources due to high variance. In this paper, level and frequency normalization is performed to effectively cluster the estimated sources. Therefore, we propose a novel SCM and an effective distance function for cluster pairs. In this paper, the proposed SCM is used for the initialization of the spatial model and used for hierarchical agglomerative clustering in the bottom-up approach. The proposed algorithm was experimented using the 'Signal Separation Evaluation Campaign 2008 development dataset'. As a result, the improvement in most of the performance indicators was confirmed by utilizing the 'Blind Source Separation Eval toolbox', an objective source separation quality verification tool, and especially the performance superiority of the typical SDR of 1 dB to 3.5 dB was verified.

• The Transactions of the Korea Information Processing Society
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• v.4 no.2
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• pp.465-482
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• 1997

In this paper, we have studied on cinstructing code-recognition shstem by neural network according to a image process taking the DOT classification code stamped on tire surface.It happened to a few problems that characters distorted in edge by diffused reflection and two adjacent characters take the same label,even very sen- sitive to illumination ofr recognition the stamped them on tire.Thus,this paper would propose the algorithm for tire code under being cinscious of these properties and prove the algorithm drrciency with a simulation.Also,we have suggerted the MCBP network composing of multi-linked recognizers of dffcient identify the DOT code being tire classification code.The MCBP network extracts the projection balue for classifying each character's rdgion after taking out the prjection of each chracter's region on X,Y axis,processes each chracters by taking 7$\times$8 normalization.We have improved error rate 3% through the MCBP network and post-process comparing the DOT code Database. This approach has a accomplished that learming time get's improvenent at 60% and recognition rate has become to 95% from 90% than BckPropagation with including post- processing it has attained greate rates of entire of tire recoggnition at 98%.

• Proceedings of the Korean Association of Geographic Inforamtion Studies Conference
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• 1995.12a
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• pp.9-21
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• 1995

A planning support system enhances our ability to use water capacity expansion as an urban growth management strategy. This paper reports the development of capacity expansion modeling of water supply as part of the continuing development of such a planning support system (PEGASUS: Planning Environment for Generation and Analysis of Spatial Urban Systems) to incorporate water supply, This system is designed from the understanding that land use and development drive the demand for infrastructure and infrastructure can have a significant influence on the ways in which land is developed and used. Capacity expansion Problems of water supply can be solved in two ways: 1) optimal control theory, and 2) mixed integer nonlinear programming (MINLP). Each method has its strengths and weaknesses. In this study the MINLP approach is used because of its strength of determining expansion sizing and timing simultaneously. A dynamic network optimization model and a water-distribution network analysis model can address the dynamic interdependence between water planning and land use planning. While the water-distribution network analysis model evaluates the performance of generated networks over time, the dynamic optimization model chooses alternatives to meet expanding water needs. In addition, the user and capacity expansion modeling-to-generate-alternatives (MGA) can generate alternatives. A cost benefit analysis module using a normalization technique helps in choosing the most economical among those alternatives. GIS provide a tool for estimating the volume of demanded water and showing results of the capacity expansion model.

• Journal of Wetlands Research
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• v.15 no.3
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• pp.367-380
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• 2013

In this study, sub-indicators, and thematic mid-indexes to evaluate the water use characteristics were selected through historical data analysis and factor analysis, and consisted of the subject approach framework. And the integrated index was developed to evaluate water use characteristics of the watershed. Using developed index, the water use characteristics were assessed for 812 standard basins with the exception for North Korea using data of 1990 to 2007 from the relevant agencies. A sensitivity analysis is conducted for this study to determine the proper way through various normalization and weighting methods. To increase the objectivity of developed index, the history of the damage indicators are excluded in the analysis. In addition, in order to ensure its reliability, results from index with and without consideration of the damage history were compared. Also, the index is also applied to real data for 2008 Gangwon region to verify its field applicability. Through the validation process this index confirmed the adequacy for the indicators selection and calculation method. The results of this study were analyzed based on the spatial and time vulnerability of the basin's water use, which can be applied to various parts such as priority decision-making for water business or policy, mitigations for the vulnerable components of the basin, and supporting measures to establishment by providing relevant information about it.

• Geophysics and Geophysical Exploration
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• v.26 no.3
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• pp.114-125
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• 2023

The physics-informed neural network (PINN) has been proposed to overcome the limitations of various numerical methods used to solve partial differential equations (PDEs) and the drawbacks of purely data-driven machine learning. The PINN directly applies PDEs to the construction of the loss function, introducing physical constraints to machine learning training. This technique can also be applied to wave equation modeling. However, to solve the wave equation using the PINN, second-order differentiations with respect to input data must be performed during neural network training, and the resulting wavefields contain complex dynamical phenomena, requiring careful strategies. This tutorial elucidates the fundamental concepts of the PINN and discusses considerations for wave equation modeling using the PINN approach. These considerations include spatial coordinate normalization, the selection of activation functions, and strategies for incorporating physics loss. Our experimental results demonstrated that normalizing the spatial coordinates of the training data leads to a more accurate reflection of initial conditions in neural network training for wave equation modeling. Furthermore, the characteristics of various functions were compared to select an appropriate activation function for wavefield prediction using neural networks. These comparisons focused on their differentiation with respect to input data and their convergence properties. Finally, the results of two scenarios for incorporating physics loss into the loss function during neural network training were compared. Through numerical experiments, a curriculum-based learning strategy, applying physics loss after the initial training steps, was more effective than utilizing physics loss from the early training steps. In addition, the effectiveness of the PINN technique was confirmed by comparing these results with those of training without any use of physics loss.