• The Journal of Korean Institute of Communications and Information Sciences
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• v.24 no.7B
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• pp.1322-1330
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• 1999

The major source of errors in high-speed networks such as Broadband ISDN(B-ISDN) is buffer overflow during congested conditions. These congestion errors are the dominant sources of errors in high-speed networks and result in cell losses. Conventional communication protocols use error detection and retransmission to deal with lost packets and transmission errors. As an alternative, we have presented a method to recover consecutive cell losses using forward error correction(FEC) in ATM(Asynchronous Transfer Mode) networks to reduce the problem. The method finds the lost cells by observing new cell sequence number($SN^{\ast}$). We have used the LI field together with SN and ST fields to consider the $SN^{\ast}$ which provides more correcting coverage than SN in ATM standards. The $SN^{\ast}$ based on the additive way such as the addition of LI capacity to original SN capacity is numbered a repeatedly 0-to-80 cycle. Another extension can be based on the multiplicative way such that LI capacity is multiplied by SN capacity. The multiplicative $SN^{\ast}$ is numbered in a repeatedly 0-to-1025 cycle.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.19 no.12
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• pp.2844-2851
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• 2015

How to recover from the multiple 2D images into 3D object has been widely studied in the field of computer vision. In order to improve the accuracy of the recovered 3D shape, it is more important that noise must be minimized and the number of image frames must be guaranteed. However, potential noise is implied when tracking feature points. And the number of image frames which is consisted of an observation matrix usually decrease because of tracking failure, occlusions, or low image resolution, and so on. Therefore, it is obviously essential that the number of image frames must be secured by recovering the missing feature points under noise. Thus, we propose the analytic approach which can control directly the error distance and orientation of missing feature point by the geometrical properties under noise distribution. The superiority of proposed method is demonstrated through experimental results for synthetic and real object.

• Archives of Plastic Surgery
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• v.38 no.6
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• pp.845-850
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• 2011

Purpose: In general, orientals including Korean, have a mesocephalic face whereas Caucasians, among the western, have a dolichocephalic face. Unlike the western, in orientals including Korean, prominent malar bones are recognized as stubborn and unattractive appearance. That is why reduction malarplasty is one of the most popular aesthetic surgical procedure in Korea. Many surgical methods to reposition prominent malar bones have been performed by means of a coronal incision or a combined incisions, using both the intraoral and the external incision. Bicoronal approach has advantage such as wide operative field, easy to maintain symmetry and possibility of combining facial lift but has shortcoming, such as external scars, long operative time, and the possibility of facial nerve or artery injury. Intraoral approach has advantages of short operative time, simplicity of procedure and no external scar. But this approach is associated with problems of cheek drooping, limited exposure and difficulty in making symmetry. Methods: During 8 years, we performed a reduction malarplasty without internal fixation through an minimal intraoral incision and dissection in 39 patients. Results: The patients were followed for 46 months, with satisfactory results and no cheek drooping. There was no patient who want to revise the inappropriate operative result such as asymmetry and incomplete correction. Conclusion: We conclude that minimal intraoral incision and dissection could acquire satisfactory result of reduction malarplasty along with prevention of cheek drooping.

• Journal of Electrical Engineering and Technology
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• v.13 no.6
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• pp.2292-2300
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• 2018

A field-circuit coupling model of a typical faulty generator is established to correct through-bolt end-region overheating and breakdown failure in a tubular hydro-generator. Using the model, eddy current loss and electromagnetic forces on through bolts under normal and failure conditions are analyzed and compared and the natural frequency of a through bolt is determined. Based on the analysis results, the causative mechanism of failure is revealed and targeted improvement design measures are proposed. The numerical results are found to be consistent with the actual fault characteristics, validating the design measure improvements. The results are useful in improving the design and manufacturing standards and enhancing the operational reliability of large tubular hydro-generators.

• Journal of Biosystems Engineering
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• v.43 no.2
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• pp.103-109
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• 2018

Purpose: This study has been conducted to develop a potato yield monitoring system, consisting of a segmentation algorithm to detect potatoes scattered on a soil surface and a counting system to count the number of potatoes and convert the data from two-dimensional images to masses. Methods: First, a segmentation algorithm was developed using top-hat filtering and processing a series of images, and its performance was evaluated in a stationary condition. Second, a counting system was developed to count the number of potatoes in a moving condition and calculate the mass of each using a mass estimation equation, where the volume of a potato was obtained from its two-dimensional image, and the potato density and a correction factor were obtained experimentally. Experiments were conducted to segment potatoes on a soil surface for different potato sizes. The counting system was tested 10 times for 20 randomly selected potatoes in a simulated field condition. Furthermore, the estimated total mass of the potatoes was compared with their actual mass. Results: For a $640{\times}480$ image size, it took 0.04 s for the segmentation algorithm to process one frame. The root mean squared deviation (RMSD) and average percentage error for the measured mass of potatoes using this counting system were 12.65 g and 7.13%, respectively, when the camera was stationary. The system performance while moving was the best in L1 (0.313 m/s), where the RMSD and percentage error were 6.92 g and 7.79%, respectively. For 20 newly prepared potatoes and 10 replication measurements, the counting system exhibited a percentage error in the mass estimation ranging from 10.17-13.24%. Conclusions: At a travel speed of 0.313 m/s, the average percentage error and standard deviation of the mass measurement using the counting system were 12.03% and 1.04%, respectively.

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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• v.17 no.1
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• pp.21-32
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• 1999

Mapping and precise point determination by photogrammetry have been shown to be an economic solution. But control points are necessary to determine the exterior orientation parameters. Although the number of required control points has been reduced based on extended bundle adjustment and reinforced cross-strip, the ground survey is a significant factor of whole expenses in photogrammetry. The status of GPS-photogrammetry with kinematic DGPS-positioning to overcome this disadvantages, is now steadly progressive since the first possibility has been proved. The completed satellite configuration, powerful receiver function and upgraded software for kinematic DGPS-positioning have extensively improved the accuracy of combined bundle adjustment. So the research for the operational use of GPS-photogrammetry is absolutely necessary. The presented test field was designed for identification of subsidences in a coal mining area, flown with 60％ sidelap and cross strips. Just with 6 control points and combined block adjustment instead of the traditionally used 21 horizontal and 81 vertical control points the same ground accuracy has been reached. The accuracy of kinematic GPS-positioning and combined block adjustment was independent upon the distance of the ground reference station. It also has been showed that the special model for the systematic error correction in the combined block adjustment.

• Journal of the Korean Society of Marine Environment & Safety
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• v.13 no.4
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• pp.21-26
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• 2007

A study on analysis and application of ocean currents information extracted from SAR (Synthetic Aperture Radar) satellite image. The current information extracted from SAR satellite image is not real vector information but scalar information in normal direction of orbital path. To correct current information extracted from satellite image, observation of currents in the field is carried out at the same time and area as those of satellite image. In the analysis, current information extracted from satellite image is corrected by using observed ones. By this correction, the speed and the direction of current can be estimated. The extract current information seem to agree well with the observed ones.

• Journal of Korean Tunnelling and Underground Space Association
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• v.18 no.3
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• pp.331-339
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• 2016

Real time location (RTL) system which can control the safety of laborers in the underground space is developed in this study. This innovative system can monitor the location and history of movement of multiple laborers in real time. To accommodate constrains of the underground space, the system is portable and composed with low-battery mode. Since conventional method to detect the location of laborer with radio signal strength indicator (RSSI) contains high errors, new measurement system using accelerometers and correction method are suggested in this study. Field test is performed to validate the developed system. The error for moving laborer was 0.4 m and for non-moving laborers was 0.2 m. Thus, it is found that the new RTL system can be used to monitor the location of laborers in the underground construction space.

• Korean Journal of Psychosomatic Medicine
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• v.10 no.1
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• pp.55-60
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• 2002

Central pontine myelinolysis(CPM) and Extrapontine myelinolysis(EPM) are uncommon neurologic disorders associated with osmotic inequality between the extracellular fluid compartment and intracellular fluid compartment in the brain. Myelinolysis can occur in hyponatremia and after rapid correction of hyponatremia. It may be caused by various metabolic disturbances such as chronic alcoholism, malnourishment, cancer, chronic renal failure and organ transplantation. The authors reported a 43-year-old male patient who have received a kidney transplantation because of chronic renal failure due to diabetic nephropathy. The patient manifested psychotic symptoms such as delusion, loosened association, hallucination, inappropriate affect and aggressiveness as a sequele of CPM and EPM. He also showed neurocognitive impairment such as disorientation, memory impairment, decresed intelligence and aphasia. These manifestations are rare in CPM and EPM. We discuss the clinical features, diagnosis, course and management of the patient which may be clinically significant in the neuropsychiatric aspect especially at the consultation-liaison field.

• Steel and Composite Structures
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• v.34 no.5
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• pp.643-655
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• 2020

In the present work, the buckling behavior of a single-layered graphene sheet (SLGS) embedded in visco-Pasternak's medium is studied using nonlocal four-unknown integral model. This model has a displacement field with integral terms which includes the effect of transverse shear deformation without using shear correction factors. The visco-Pasternak's medium is introduced by considering the damping effect to the classical foundation model which modeled by the linear Winkler's coefficient and Pasternak's (shear) foundation coefficient. The SLGS under consideration is subjected to compressive in- plane edge loads per unit length. The influences of many parameters such as nonlocal parameter, geometric ratio, the visco-Pasternak's coefficients, damping parameter, and mode numbers on the buckling response of the SLGSs are studied and discussed.