• Journal of the Korea Society of Computer and Information
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• v.3 no.4
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• pp.27-34
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• 1998

In this paper we present a method for automatic motion vector and brightness based video indexing and retrieval. We extract a representational frame from each shot and compute some motion vector and brightness based features. For each R-frame we compute the optical flow field; motion vector features are then derived from this flow field, BMA(block matching algorithm) is used to find motion vectors and Brightness features are related to the cut detection of method brightness histogram. A video database provided contents based access to video. This is achieved by organizing or indexing video data based on some set of features. In this paper the index of features is based on a B+ search tree. It consists of internal and leaf nodes stores in a direct access a storage device. This paper defines the problem of video indexing based on video data models.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• v.9 no.1
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• pp.462-466
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• 2005

Dynamic (On-line) signature verification system consists of preprocessing, feature extraction, comparison and decision process for internal processing, and registration and verification windows for the user interface. We describe an implementation and design for an advanced dynamic signature verification system. Also, we suggest the method of feature extraction, matching algorithm, efficient user interface and an objective criteria for evaluating the performance.

• Journal of Electrical Engineering and Technology
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• v.9 no.5
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• pp.1753-1761
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• 2014

Due to the inherent inhomogeneous and anisotropy nature of the composite materials, the detection of internal defects in these materials with non-destructive techniques is an important requirement both for quality checks during the production phase and in service inspection during maintenance operations. The estimation of the time-of-arrival (TOA) and/or time-of-flight (TOF) of the ultrasonic echoes is essential in ultrasonic non-destructive testing (NDT). In this paper, we used split-spectrum processing (SSP) combined with matching pursuit signal decomposition (MPSD) to develop a dedicated ultrasonic detection system. SSP algorithm is used for Signal-to-Noise Ratio (SNR) enhancement, and the MPSD algorithm is used to decompose backscattered signals into a linear expansion of chirplet echoes and estimate the chirplet parameters. Therefore, the combination of SSP and MPSD (SSP-MPSD) presents a powerful technique for ultrasonic NDT. The SSP algorithm is achieved by using Gaussian band pass filters. Then, MPSD algorithm uses the Maximum Likelihood Estimation. The good performance of the proposed method is experimentally verified using ultrasonic traces acquired from three specimens of carbon fibre reinforced polymer multi-layered composite materials (CFRP).

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.23 no.7
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• pp.662-668
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• 2013

In this paper, possibility of controlling motion of a floating structure using a tuned liquid damper (TLD) is numerically investigated. A TLD is a tank partially filled with liquid. Sloshing motion of liquid inside a tank is known to suppress movement of the tank subject to external excitations at specific frequency. The effects of sloshing phenomena inside a rectangular floating body on its surge motion are investigated by varying external excitation frequency. First, a grid-refinement study is carried out to ensure validity of grid independent numerical solutions using present numerical techniques. Then, surge motion of the floating body subjected to external wave is simulated for five different excitation frequencies of which the center frequency equals to the natural frequency of internal liquid sloshing. The normalized amplitudes of surge motion of the target floating body are compared according to the excitation frequency, for the cases with and without water inside the floating body. It is shown that the motion of the floating body can be minimized by matching the sloshing natural frequency to the excitation frequency.

• Journal of Korean Medicine for Obesity Research
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• v.2 no.1
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• pp.25-36
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• 2002

Objective: The purposes of this study are to know the relations of abdominal obesity and ischemic stroke and to know what index could represent the abdominal obesity appropriately. Methods. We have done case-control study and recruited 97 ischemic stroke patients and 117 controls. Case is matched by control by individual matching. All participants had questionnaire, interview and then were examined waist-hip ratio, waist circumference and body mass index. Results : WC, WHR and Hypertension history had differences in two groups, case and control groups. But BMI and other factors weren't significant. According to Quartile of Waist Circumference, the two groups had the differences in hypertension history, diabetes history, smoking status, WHR, BMI, and weight and in the Quartile of Waist-Hip Ratio Quartile, past history of hypertension and diabetes, WC, BMI and weight had the significances. Sex, Age Adjusted and Multivariate Odds Ratio (95% Confidence Interval) of WC Quartile are 2.083, 1.628, 4.491 and 4.418, 4.964, 12.306, and in WHR, the Ors are 2.252, 5.743, 15.776 and 2.632, 8.918, 23.596. Conclusions: We knew from these results that abdominal obesity is very important risk factor of ischemic stroke and WHR more than WC is a good indicator of abdominal obesity, so we should reduce the WHR to prevent of ischemic stroke.

• Journal of Korea Society of Industrial Information Systems
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• v.15 no.1
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• pp.37-46
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• 2010

A Suffix Tree is an efficient data structure that exposes the internal structure of a string and allows efficient solutions to a wide range of complex string problems, in particular, in the area of computational biology. However, as the biological information explodes, it is impossible to construct the suffix trees in main memory. We should find an efficient technique to construct the trees in a secondary storage. In this paper, we present a method for constructing a suffix tree in a disk for large set of DNA strings using new index scheme. We also show a typical application example with a suffix tree in the disk.

• Journal of the Korean Regional Science Association
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• v.39 no.4
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• pp.111-125
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• 2023

China's rapid economic growth and accelerated urbanization have significantly increased labor force mobility. The choice of city residence and long-term residence intentions of migrants will have significant consequences on both economic output and societal dynamics. This paper investigates the impact of air quality on the long-term residence intention of migrants. By matching an individual-level survey on willingness to stay in the long run and the city-level air quality, represented by PM2.5, we find that the willingness to stay in the long run increases with better air quality. This implies that public policy to maintain good air quality is crucial in keeping those who moved to the city.

• Korean Circulation Journal
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• v.53 no.11
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• pp.775-786
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• 2023

Background and Objectives: Tricuspid valve (TV) repair techniques other than annuloplasty remain challenging and frequently end in tricuspid valve replacement (TVR) in complicated cases. However, the results of TVR are suboptimal compared with TV repair. This study aimed to evaluate the clinical effectiveness of TV edge-to-edge repair (E2E) compared to TVR for severe tricuspid regurgitation (TR). Methods: We retrospectively reviewed 230 patients with severe TR who underwent E2E (n=139) or TVR (n=91) from 2001 to 2020. Clinical and echocardiographic results were analyzed using inverse probability of treatment weighting analysis and propensity score matching. Results: The two groups showed no significant differences in early mortality and morbidities. During the mean follow-up of 106.2±68.8 months, late severe TR and TV reoperation rates were not significantly different between groups. E2E group, however, showed better outcomes in overall survival (p=0.023), freedom from significant tricuspid stenosis (TS) (trans-tricuspid pressure gradient ≥5 mmHg, p=0.021), and freedom from TV-related events (p<0.001). Matched analysis showed consistent results. Conclusions: E2E for severe TR presented more favorable clinical outcomes than TVR. Our study supports that E2E might be a valuable option in severe TR surgery, avoiding TVR.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.24 no.11
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• pp.1064-1073
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• 2013

In this paper, a compact 370 W high efficiency GaN(Gallium Nitride) HEMT(High Electron Mobility Transistor) power amplifier(PA) using internal harmonic manipulation circuits is presented for cellular and L-band. We employed a new circuit topology for simultaneous high efficiency matching at both fundamental and 2nd harmonic frequency. In order to minimize package size, new 41.8 mm GaN HEMT and two MOS(Metal Oxide Semiconductor) capacitors are internally matched and combined package size $10.16{\times}10.16{\times}1.5Tmm^3$ through package material changes and wire bonded in a new package to improve thermal resistance. When drain biased at 48 V, the developed GaN HEMT power amplifier has achieved over 80 % Drain Efficiency(DE) from 770~870 MHz and 75 % DE at 1,805~1,880 MHz with 370 W peak output power(Psat.). This is the state-of-the-art efficiency and output power of GaN HEMT power amplifier at cellular and L-band to the best of our knowledge.

• Journal of Gastric Cancer
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• v.18 no.1
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• pp.58-68
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• 2018

Purpose: Generally, adjuvant chemotherapy (AC) should be initiated as soon as possible after surgery to eradicate microscopic cancer cells. In this study, we investigated the effect of early AC on the survival of stage II/III gastric cancer patients. Materials and Methods: Four hundred sixty patients who received AC (S-1 or XELOX) for pathologic stage II/III gastric cancer at Seoul National University Bundang Hospital between January 2008 and December 2014 were included. Patients were divided into 2 groups: early AC administration (within 4 weeks) and late AC administration (more than 4 weeks). Patients in the early AC group (n=174) were matched 1:1 with patients in the late AC group (n=174) by propensity scoring to adjust for clinical differences. Three-year relapse-free survival (RFS) was evaluated according to the timing of AC. Results: Three-year RFS was 98.1% in stage IIA (n=109), 85.0% in stage IIB (n=83), 87.4% in stage IIIA (n=96), 83.5% in stage IIIB (n=91), and 62.5% in stage IIIC (n=81). After propensity score matching, RFS was similar between early and late AC groups (hazard ratio [HR],1.04; 95% confidence interval [CI], 0.62-1.74; P=0.889). Pathologic stage and histological type were independent prognostic factors of RFS (HR, 2.05; 95% CI, 1.06-3.96; P=0.033 and HR, 2.61; 95% CI, 1.42-4.80; P=0.002, respectively). Conclusions: Early initiation of AC within 4 weeks does not affect survival rates in stage II/III gastric cancer.