• Journal of Biomedical Engineering Research
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• v.20 no.2
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• pp.221-230
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• 1999

A new technique for the preparation of porous polyurethane vascular prostheses was investigated. Synthetic vascular grafts with porous wall have been widely proposed, claiming that strength, suture retention, kink resistance, and other handling properties are improved over those with nonporous solid wall. Related to these facts, the control of pores and compliance match have been very important and interesting issues. Two kinds of polymer sheets were compared. One was the porous PU-sheet made at room temerature by the solvent/non-solvent exchange. And the other was the porous PU-sheet fabricated by thermal phase transition and solvent/non-solvent exchange in the thermal controlled bath. According to the result of the above experiments, polyurethane solution was injected into a mold designed for U-type graft. After freezing at low temperature, solvent was dissolved out with alcohol at < $0^{\circ}C$ and water at room temperature to form porous vessels. The average pore size and pore occupation were easily changed by changing polyurethane concentration and freezing rate. This technique can give a proper pore size for tissue ingrowth, and suitable compliances for matching with arteries and veins. In addition, the fabrication of more complicated shaped vessels such as the U-type vascular grafts is easily controlled by using a mold. This method might give a desired compliact graft for artificial implantaion with the commercially available medical polymers.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.27 no.12
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• pp.1084-1096
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• 2016

This paper presents method of design and analysis of a high-speed serial interface connector with a data rate of 12.5 Gbps. A high-speed serial interface connector is composed of various material and complex structures. It is very difficult to match the impedance of each discontinuous portion of connector. Therefore, this paper proposes the structure of a connector line that be simplified a connector. In the structure of proposed connector line, this research presents a method for extracting R, L, C and G parameters, analyzing the differential mode impedance, and minimizing the impedance discontinuity using time domain transmissometry and time domain reflectometry. This paper applies the proposed methods in the connector line to the high-speed serial interface connector. The proposed high-speed serial interface connector, which consists of forty-four pins, is analyzed signal transmission characteristics by changing the width and spacing of the four pins. According to the analysis result, as the width of the ground pin increases, the impedance decreases slightly. And as the distance between the ground pin and the signal pin increases, the impedance increases. In addition, as the width of the signal pin increases, the impedance decreases. And as the distance between the signal pin and the signal pin increases, the impedance decreases. The impedance characteristic of initial connector presents ranges from 96 to $139{\Omega}$. Impedance characteristic after applying the structure of proposed connector is shown as a value between 92.6 to $107.5{\Omega}$. This value satisfies the design objective $100{\Omega}{\pm}10%$.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2008.06a
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• pp.169-169
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• 2008

To keep pace with scaling trends of CMOS technologies, high-k metal oxides are to be introduced. Due to their high permittivity, high-k materials can achieve the required capacitance with stacks of higher physical thickness to reduce the leakage current through the scaled gate oxide, which make it become much more promising materials to instead of $SiO_2$. As further studying on high-k, an understanding of the relation between the etch characteristics of high-k dielectric materials and plasma properties is required for the low damaged removal process to match standard processing procedure. There are some reports on the dry etching of different high-k materials in ICP and ECR plasma with various plasma parameters, such as different gas combinations ($Cl_2$, $Cl_2/BCl_3$, $Cl_2$/Ar, $SF_6$/Ar, and $CH_4/H_2$/Ar etc). Understanding of the complex behavior of particles at surfaces requires detailed knowledge of both macroscopic and microscopic processes that take place; also certain processes depend critically on temperature and gas pressure. The choice of $BCl_3$ as the chemically active gas results from the fact that it is widely used for the etching o the materials covered by the native oxides due to the effective extraction of oxygen in the form of $BCl_xO_y$ compounds. In this study, the surface reactions and the etch rate of $Al_2O_3$ films in $BCl_3/Cl_2$/Ar plasma were investigated in an inductively coupled plasma(ICP) reactor in terms of the gas mixing ratio, RF power, DC bias and chamber pressure. The variations of relative volume densities for the particles were measured with optical emission spectroscopy (OES). The surface imagination was measured by AFM and SEM. The chemical states of film was investigated using X-ray photoelectron spectroscopy (XPS), which confirmed the existence of nonvolatile etch byproducts.

• Korean journal of applied entomology
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• v.22 no.4 s.57
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• pp.271-276
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• 1983

In field studies, the insecticides carbofuran(Furadan 3G) and diazion(3G) at the rate of 1,8 kg a.i./ha as a single side-furrowing treatment from March 13 to April 10(7 to 10 days intervals) were evaluated in terms of the control effects to the onion maggots(Hylemyia antique Meigen) and some phytotonic effects to the garlic plants. The treatments with carbofuran were significantly more effective in onion maggot control than the treatment with diazinon and untreated, and the earlier treatments the better control effects were obtained. Phytotonic effects only with carbofuran on garlic plants were of served as increases ranged $16.5\~23.2\%$ in plant heights, $22.0\~32.0\%$ in stem diameters and $15.5\~22.8\%$ in bulb diameters compared to the untreated. The greatest yield of garlics was resulted in the plots of Match-13 treatments with carbofuran, ca. 10,700kg/ha in the carbofuran treatment, ca. 5637kg/ha in the diazinon treatment and ca. 4728kg/ha in the untreated plots. The magnitude of yield increase of garlics in the plots treated with carbofuran was attributable to positively stimulate the growth response of garlic plants as well as the control effects to onion maggots.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.11 no.4
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• pp.147-156
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• 2011

Though a dozen of different software life cycle models are suggested, there is no universal model which can satisfy all the characteristics of software. Organizations mix and match different life cycle models to develop a model more tailored for their systems and capabilities. We suggest overlapped-concurrent development life cycle model that is more suitable in various software development environment. Firstly, we divided the development process into abstract and implementation stage. Abstract stage is from software concept phase to detailed design starting time, and implementation stage is from detailed design phase to system testing phase. Next, the abstract stage introduced the overlapped phase concept that begins the next phase when the step is completed 20% by applying pareto's law. In the implementation stage, we introduced the concurrent development which the several phases are performed some time as when one use-case (UC) is completed the next development phase is started immediately. The proposed model has an advantage that it can reduce the inefficiency of development resource greatly. This model can increase the customer satisfaction with a great product at a low cost and on a short schedule. Also, this model can contribute to increase the software development success rate.

• Journal of KIISE:Information Networking
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• v.29 no.1
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• pp.86-96
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• 2002

In video conferencing system using H.263 encoding and decoding time is as important as compression rate is. To reduce encoding time, a number of methods were proposed. We use a method of them that reduces the computational complexity in motion estimation. The complexity is determined by three factors, such as a cost function, a search range parameter, and a motion search algorithm. In fact, it takes a lot of time to encode the video data on account of the cost function factor. That's the reason that we use the factor to reduce encoding time. In this paper, we tried to reduce total encoding time by reducing the number of calling the cost function. In case of a little moving, our algorithm enabled faster motion searching than TSS(Three Step Search) and NTSS(New TSS). Here, we called the algorithm by an ITSS(Improved TSS) that improves a shortcoming of NTSS requiring more checkpoints than TSS. For an experimentation, our algorithm was compared to other algorithms using PSNR, file size and SAD call times.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.20 no.3
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• pp.16-22
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• 2019

Off-line programming and robot calibration through simulation are essential when setting up a robot in a robot automation production line. In this study, we developed a new robot calibration method to match the CAD data of the production line with the measurement data on the site using 3D scanner. The proposed method calibrates the robot using 3D point cloud data through Iterative Closest Point algorithm. Registration is performed in three steps. First, vertices connected by three planes are extracted from CAD data as feature points for registration. Three planes are reconstructed from the scan point data located around the extracted feature points to generate corresponding feature points. Finally, the transformation matrix is calculated by minimizing the distance between the feature points extracted through the ICP algorithm. As a result of applying the software to the automobile welding robot installation, the proposed method can calibrate the required accuracy to within 1.5mm and effectively shorten the set-up time, which took 5 hours per robot unit, to within 40 minutes. By using the developed system, it is possible to shorten the OLP working time of the car body assembly line, shorten the precision teaching time of the robot, improve the quality of the produced product and minimize the defect rate.

• Korean Journal of Heritage: History & Science
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• v.46 no.3
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• pp.78-93
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• 2013

The purpose of this study is to analyze college students' perception of national natural heritages, including natural monumentsand scenic sites, in comparison with the similar concepts of national parks and eco-landscape preservation areas, to suggest managerial implications to enhance competitiveness. The first objective of this study is to measure their attitude toward traveling each type of natural heritage and to rate the relative importance of the four types of heritages in terms of preservation. Natural monuments were perceived as the most strongly preserved type, while scenic sites were perceived as the least strongly preserved type. The second objective is to conduct a correspondence analysis to match the concepts of four types of natural heritages with 10 tourist attractions representing the types. It was found that college students have difficulty appropriately identifying the types of 10 tourist attractions. In addition, multi-dimensional scaling (MDS) was implemented to identify the similarities and differences of the four types of natural heritages and to produce a positioning map matching the four types of natural heritages with the six attributes representing each type as a tourist attraction. Natural monuments were perceived very differently from scenic sites and not very differently from eco-landscape preservation areas. There were a few associations between the four types of natural heritages and the six tourism attributes, implying that little effort is made to promote and position each type of natural heritage in terms of tourism. In conclusion, a public awareness program is required to enhance the brand image of natural monuments and scenic sites in comparison to national parks and eco-landscape preservation areas. In addition, local residents who live near the natural heritages should be bolstered to play a managerial role as supporters and contents providers for sustainability.

• Smart Structures and Systems
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• v.24 no.6
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• pp.769-781
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• 2019

Dynamic displacement response of civil structures is an important index for in-construction and in-service structural condition assessment. However, accurately measuring the displacement of large-scale civil structures such as high-rise buildings still remains as a challenging task. In order to cope with this problem, a vision-based system with the use of industrial digital camera and image processing has been developed for long-distance, remote, and real-time monitoring of dynamic displacement of supertall structures. Instead of acquiring image signals, the proposed system traces only the coordinates of the target points, therefore enabling real-time monitoring and display of displacement responses in a relatively high sampling rate. This study addresses the in-situ experimental verification of the developed vision-based system on the Canton Tower of 600 m high. To facilitate the verification, a GPS system is used to calibrate/verify the structural displacement responses measured by the vision-based system. Meanwhile, an accelerometer deployed in the vicinity of the target point also provides frequency-domain information for comparison. Special attention has been given on understanding the influence of the surrounding light on the monitoring results. For this purpose, the experimental tests are conducted in daytime and nighttime through placing the vision-based system outside the tower (in a brilliant environment) and inside the tower (in a dark environment), respectively. The results indicate that the displacement response time histories monitored by the vision-based system not only match well with those acquired by the GPS receiver, but also have higher fidelity and are less noise-corrupted. In addition, the low-order modal frequencies of the building identified with use of the data obtained from the vision-based system are all in good agreement with those obtained from the accelerometer, the GPS receiver and an elaborate finite element model. Especially, the vision-based system placed at the bottom of the enclosed elevator shaft offers better monitoring data compared with the system placed outside the tower. Based on a wavelet filtering technique, the displacement response time histories obtained by the vision-based system are easily decomposed into two parts: a quasi-static ingredient primarily resulting from temperature variation and a dynamic component mainly caused by fluctuating wind load.

• The Journal of Internal Korean Medicine
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• v.43 no.1
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• pp.1-21
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• 2022

Purpose: The standard tool for the pattern identification is used for identifying patterns in patients using a questionnaire. The purpose of this study is to reorganize the standard tool for the pattern identification of gastroesophageal reflux disease (GERD) developed in 2017 and to analyze the reliability and validity of the standard tool for pattern identification by applying it to GERD patients. Methods: To reorganize the standard tool for the pattern identification of GERD developed in the previous study, we searched the literature in the main databases, OASIS (Oriental Medicine Advanced Searching Integrated System) and CNKI (China National Knowledge Infrastructure). We added the search results to the data used in the previous study and went through the reorganizing courses, such as evaluating the validity of the translation, the Delphi technique, and a small survey. After reorganization, the patients who visited the Kyunghee University Korean Medicine Center for GERD symptoms were provided the questionnaire, including the reorganized standard tool for pattern identification. We analyzed the survey results to evaluate their reliability and validity. Results: Fifty patients completed the questionnaire. Reliability analysis results showed a pattern identification match rate of 86%, Cronbach's α coefficient of 0.834, and intraclass correlation coefficient of 0.907. The Mann - Whitney U test and logistic regression were implemented to check the relations between the survey questions and pattern identification results; the Pearson correlation, compared with other scales, showed a moderate score. Conclusion: We reorganized the standard tool for the pattern identification of GERD to be updated on current issues and so that it is easily used. The analysis results of the questionnaire showed that the reorganized standard tool had high reliability and moderate validity.