• Proceedings of the KSME Conference
• /
• 2007.05a
• /
• pp.372-377
• /
• 2007

For more than 2,500 years, surgical teaching has been based on the so called "see one, do one, teach one" paradigm, in which the surgical trainee learns by operating on patients under close supervision of peers and superiors. However, higher demands on the quality of patient care and rising malpractice costs have made it increasingly risky to train on patients. Minimally invasive surgery, in particular, has made it more difficult for an instructor to demonstrate the required manual skills. It has been recognized that, similar to flight simulators for pilots, virtual reality (VR) based surgical simulators promise a safer and more comprehensive way to train manual skills of medical personnel in general and surgeons in particular. One of the major challenges in the development of VR-based surgical trainers is the real-time and realistic simulation of interactions between surgical instruments and biological tissues. It involves multi-disciplinary research areas including soft tissue mechanical behavior, tool-tissue contact mechanics, computer haptics, computer graphics and robotics integrated into VR-based training systems. The research described in this paper addresses the problem of characterizing soft tissue properties for medical virtual environments. A system to measure in vivo mechanical properties of soft tissues was designed, and eleven sets of animal experiments were performed to measure in vivo and in vitro biomechanical properties of porcine intra-abdominal organs. Viscoelastic tissue parameters were then extracted by matching finite element model predictions with the empirical data. Finally, the tissue parameters were combined with geometric organ models segmented from the Visible Human Dataset and integrated into a minimally invasive surgical simulation system consisting of haptic interface devices and a graphic display.

• Journal of Korean Society of Steel Construction
• /
• v.29 no.6
• /
• pp.435-442
• /
• 2017

A lateral load resisting system is a necessary structural element for the mid- to high-rise modular buildings and concrete cores are known as the most typical lateral load resisting systems in 10- to 20-story modular buildings. It is difficult to construct a concrete core simultaneously with the installation and finishing work of modular units because concrete placed using wet methods might contaminate or destroy the modular unit. Therefore, we have developed a hybrid PC (precast concrete) panel construction method that can construct a concrete core together with the installation of modular units. The hybrid PC panel is a load-bearing element in which a pair of C-shaped beams are combined at the top and bottom of a concrete wall. Concrete cores can be constructed by dry method to connect the hybrid PC panels with bolts. In this study, the details and connection of hybrid PC panels are improved to have the lateral performance comparable to reinforced concrete structural walls and are verified through FE analysis.

• Journal of Chest Surgery
• /
• v.21 no.3
• /
• pp.497-509
• /
• 1988

Current therapy of aortic dissections remains unstandardized because of the relative rarity of these catastrophic events and conflicting reported results of various therapeutic strategies. Hence, we reviewed our current results and planned to purify our method of interpretation of results and so, to standardize therapeutic managements. This study comprised unselected, consecutive 27 patients with aortic dissections who were operated at Seoul National University Hospital from Jan 1983 to March 1988. The results from analysis of their preoperative, operative and postoperative finding were as follows: 1] 7 patients had acute type A, 14 had chronic type A, 4 had acute type B, and 2 had chronic type B. 2] The causes of dissections were unclear, but 8 patients had Marfan`s syndromes, 2 had previous operative histories on cardiovascular systems and 2 had congenital heart diseases. 3] Multiple preoperative variables were found to correlate significantly with operative mortality and complications. The prevalences of such preoperative major complicating factors were significantly more frequent in acute than chronic [P < 0.05] and type A than type B [P < 0.01]. 4] Operations were performed according to the type of the dissections and whether it was acute or chronic. Usually dacron tube graft replacements were performed[25/26]. Intraluminal sutureless graft replacement was performed in 11 patients. Of the 14 patients with combined aortic regurgitation, concomitant aortic valve resuspension in 4, seperative aortic valve replacement in 1, and aortic valve replacement with coronary reimplantation were performed in 9 patients. 2 patients had concomitant arch vessel managements. 5] Over-all operative mortality rate was 33% and 54% for acute type A, 25% for acute type B, 29% for chronic type A, 0% for chronic type B respectively. The main causes of operative mortality were cardiovascular complications [mainly CPB-weaning failure] in acute cases and hemorrhagic complications in chronic cases.

• Journal of the Korean association of regional geographers
• /
• v.14 no.6
• /
• pp.718-735
• /
• 2008

Park-and- Rides are intermodal transfer facilities providing a staging location for travellers to transfer between transportation modes. They are an alternative to alleviate transportation problems such as traffic congestion and air pollution in metropolitan areas. Siting Park-and-Ride facilities belongs to a kind of multi-criteria spatial decision making problems being associated with a combination of various location factors. The purpose of this paper is to provide a method and procedure to evaluate the location suitability of Park-and-Ride facilities using GIS(Geographic Information Systems). Using GIS-based suitability analysis, land value, landuse, road accessibility, public transportation accessibility, possibility to intercept automobile trips, distance to activity center and competition with existing facilities were evaluated as location factors. The suitabilities of individual factors were combined to produce a composite map with a specific weight scheme. Then a given number of sites with high suitability score were selected as potential facility locations and their demand were evaluated based on a commutershed with parabolic shape. The suggested method and procedure will provide useful information in determining Park-and-Ride sites and designing their structure.

• Ecology and Resilient Infrastructure
• /
• v.2 no.4
• /
• pp.296-304
• /
• 2015

The rapid increase in the number of climate disasters combined with the scale of change and the diversification of natural disasters require a radical solution. In particular, the urban space is more complex, therefore we need to establish measures for disaster response and how to react to damaged infrastructure based on the phenomenon of an increase in the urban population and the impermeable layer being extended. The social problems related to the economic burden of land purchase and the securing of a disaster prevention system can be solved simultaneously by introducing the park system for disaster reduction into the public land of the green space in the city. The local government has recently adapted diverse systems of disaster mitigation and carried out pioneer projects according to the guidelines for the construction of the urban park for disaster prevention published by the Ministry of Land, Infrastructure and Transport. The purpose of this study is to propose a composition model for neighborhood parks to prevent disaster through urban green spaces which has the functions of water management and biotope conservation. The result of this study will contribute to utilize the climate change adaptation model for living area neighborhood parks in the existing urban structure.

• Korean Journal of Clinical Laboratory Science
• /
• v.39 no.3
• /
• pp.217-222
• /
• 2007

In the last 5 years the Epidermal Growth Factor Receptor (EGFR) has emerged as one of the most important targets for drug development in oncology. Monoclonal antibodies targeting the external domain of EGFR have been shown to have clinical benefits in colorectal and head and neck cancer when combined with chemotherapy and/or radiation. Also the targeting of the epithelial growth factor receptor (EGFR) kinase domain using the closely related inhibitors gefitinib and erlotinib has generally been ineffective against solid tumors, many of which over express the receptor. We found that there were some differential expressions according to primary antibodies of the EGFR protein which being used as one of the histological tumor markers for non-small cell lung cancer (NSCLC). We also found that there are some differential expressions according to antibodies, the pH of the antigen retrieval (AR) buffer solutions and kinds of enzymes. There were some differential expressions according to the secondary antibodies and the detection systems. We analyzed the correlations between the immunohistochemical expressions of the EGFR protein and the gene mutations of the EGFR. The differences between automatic stainers and manual staining methods were also evaluated.

• Journal of Intelligence and Information Systems
• /
• v.10 no.2
• /
• pp.39-51
• /
• 2004

Product factory is a real-time financial product design system for the Internet customers. The hybrid product is a product taking combined characteristics of two different products. Hybrid product factory is a product factory that designs hybrid products from two different products based on both business rules and customer requirements. Though the importance of product factory is emphasized in the industry, there has not been much research peformed regarding product factory. In this research, we developed a product factory system that designs hybrid products. To design a hybrid product, it is necessary to have a method to combine attributes and values of two different products, and a method to control the combining operations to properly reflect business requirements. In this research, we developed low different combining operators and business rule representations. rn addition, to prove the effectiveness of this methods, we implemented a prototypical system and demonstrated on cases regarding financial loan products.

• KSII Transactions on Internet and Information Systems (TIIS)
• /
• v.13 no.11
• /
• pp.5276-5298
• /
• 2019

Internet of Things (IoT) based sensor networks have gained unprecedented popularity in recent years. With the exponential explosion of the objects (sensors and mobiles), the bandwidth and the speed of data transmission are dwarfed by the anticipated emergence of IoT. In this paper, we propose a novel heterogeneous IoT model integrated the power line communication (PLC) and WiFi network to increase the network capacity and cope with the rapid growth of the objects. We firstly propose the mean transmission delay calculation algorithm based the 3D Markov chain according to the multi-priority of the objects. Then, the attractor selection algorithm, which is based on the adaptive behavior of the biological system, is exploited. The combined the 3D Markov chain and the attractor selection model, named MASM, can select the optimal path adaptively in the heterogeneous IoT according to the environment. Furthermore, we verify that the MASM improves the transmission efficiency and reduce the transmission delay effectively. The simulation results show that the MASM is stable to changes in the environment and more applicable for the heterogeneous IoT, compared with the other algorithms.

• KSII Transactions on Internet and Information Systems (TIIS)
• /
• v.9 no.7
• /
• pp.2414-2434
• /
• 2015

Among numerous localization schemes proposed specifically for Wireless Sensor Network (WSN), the range-free localization algorithms based on the received signal strength indication (RSSI) have attracted considerable research interest for their simplicity and low cost. As a typical range-free algorithm, Approximate Point In Triangulation test (APIT) suffers from significant estimation errors due to its theoretical defects and RSSI inaccuracy. To address these problems, a novel localization method called FIAPIT, which is a combination of an improved APIT (IAPIT) and a fuzzy logic system, is proposed. The proposed IAPIT addresses the theoretical defects of APIT in near (it's defined as a point adjacent to a sensor is closer to three vertexes of a triangle area where the sensor resides simultaneously) and far (the opposite case of the near case) cases partly. To compensate for negative effects of RSSI inaccuracy, a fuzzy system, whose logic inference is based on IAPIT, is applied. Finally, the sensor's coordinates are estimated as the weighted average of centers of gravity (COGs) of triangles' intersection areas. Each COG has a different weight inferred by FIAPIT. Numerical simulations were performed to compare four algorithms with varying system parameters. The results show that IAPIT corrects the defects of APIT when adjacent nodes are enough, and FIAPIT is better than others when RSSI is inaccuracy.

• KSII Transactions on Internet and Information Systems (TIIS)
• /
• v.9 no.7
• /
• pp.2633-2648
• /
• 2015

The problem of visual words' synonymy and ambiguity always exist in the conventional bag of visual words (BoVW) model based object category methods. Besides, the noisy visual words, so-called "visual stop-words" will degrade the semantic resolution of visual dictionary. In view of this, a novel bag of visual words method based on PLSA and chi-square model for object category is proposed. Firstly, Probabilistic Latent Semantic Analysis (PLSA) is used to analyze the semantic co-occurrence probability of visual words, infer the latent semantic topics in images, and get the latent topic distributions induced by the words. Secondly, the KL divergence is adopt to measure the semantic distance between visual words, which can get semantically related homoionym. Then, adaptive soft-assignment strategy is combined to realize the soft mapping between SIFT features and some homoionym. Finally, the chi-square model is introduced to eliminate the "visual stop-words" and reconstruct the visual vocabulary histograms. Moreover, SVM (Support Vector Machine) is applied to accomplish object classification. Experimental results indicated that the synonymy and ambiguity problems of visual words can be overcome effectively. The distinguish ability of visual semantic resolution as well as the object classification performance are substantially boosted compared with the traditional methods.