• Journal of Computing Science and Engineering
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• v.4 no.2
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• pp.173-187
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• 2010

Recent technological advances in mobile communication systems have made explosive growth in the number of mobile device users worldwide. One of the most important issues in designing a mobile computing system is location management of users. The hierarchical systems had been proposed to solve the scalability problem in location management. The scalability problem occurs when there are too many users for a mobile system to handle, as the system is likely to react slow or even get down due to late updates of the location databases. In this paper, we propose a top-down clustering algorithm for hierarchical location database systems in a wireless network. A hierarchical location database system employs a tree structure. The proposed algorithm uses a top-down approach and utilizes the number of visits to each cell made by the users along with the movement information between a pair of adjacent cells. We then present a modified algorithm by incorporating the exhaustive method when there remain a few levels of the tree to be processed. We also propose a capacity constraint top-down clustering algorithm for more realistic environments where a database has a capacity limit. By the capacity of a database we mean the maximum number of mobile device users in the cells that can be handled by the database. This algorithm reduces a number of databases used for the system and improves the update performance. The experimental results show that the proposed, top-down, modified top-down, and capacity constraint top-down clustering algorithms reduce the update cost by 17.0%, 18.0%, 24.1%, the update time by about 43.0%, 39.0%, 42.3%, respectively. The capacity constraint algorithm reduces the average number of databases used for the system by 23.9% over other algorithms.

• Journal of Positioning, Navigation, and Timing
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• v.7 no.2
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• pp.53-59
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• 2018

This paper proposes a pseudo-random beamforming technique for time-synchronized mobile base stations (BSs) for multi-cell downlink networks which have mobility. The base stations equipped with multi-antennas and mobile stations (MSs) are time-synchronized based on global positioning system (GPS) signals and generate a number of transmit beamforming matrix candidates according to the predetermined pseudo-random pattern. In addition, MSs generate receive beamforming vectors that correspond to the beam index number based on the minimum mean square error (MMSE) using transmit beamforming vectors that make up a number of transmit beamforming matrices and wireless channel matrices from BSs estimated via the reference signals (RS). Afterward, values of received signal-to-interference-plus-noise ratio (SINR) with regard to all transmit beamforming vectors are calculated, and the resulting values are then feedbacked to the BS of the same cells along with the beam index number. Each of the BSs calculates each of the sum-rates of the transmit beamforming matrix candidates based on the feedback information and then transmits the calculated results to the BS coordinator. After this, optimum transmit beamforming matrices, which can maximize a sum-rate of the entire cells, are selected at the BS coordinator and informed to the BSs. Finally, data signals are transmitted using them. The simulation results verified that a sum-rate of the entire cells was improved as the number of transmit beamforming matrix candidates increased. It was also found that if the received SINR values and beam index numbers are feedbacked opportunistically from each of the MSs to the BSs, not only nearly the same performance in sum-rate with that of applying existing feedback techniques could be achieved but also an amount of feedback was significantly reduced.

• The Korean Journal of Malacology
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• v.26 no.3
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• pp.245-254
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• 2010

For the studies of germ cell development and maturation in the ovary, the gametogenic cycle and the number of spawning seasons per year in female Ruditapes philippinarum were investigated by quantitative statistical analysis using an Image Analyzer System. Compared with the results by qualitative and quantitative analyses, monthly variations in female gonad indice by qualitative histological analysis showed a pattern similar to that of the female gametogenic cycle calculated by quantitative statistical analysis. The number of spawning seasons occurred once per year, from June to October. In quantitative statistical analysis using an image analyzer system, monthly changes in the portions (%) of the ovary area to total tissue areas in females increased in March and reached a maximum in May, and then showed a rapid decrease from June to October when spawning occurred. And also monthly changes in portions (%) of follicle areas to the ovary area and in portions of oocyte areas to ovarian tissue areas in females began to increase in March and reached a maximum in May, and then. rapidly dropped from June to October when spawnig occurred. From these data, it is apparent that the number of spawning seasons occurred once per year, from June to October. Monthly changes in the number of the oocyte per $mm^2$ and in mean diameter of the oocyte in captured image which were calculated for each female slide showed a maximum in May and reached the minimum from December to February. Therefore, female R. philippinarum showed a unimodal gametogenic cycle during the year.

• Journal of Chest Surgery
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• v.56 no.6
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• pp.403-411
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• 2023

Background: The concept of oligo-recurrence has not been generally applied in esophageal cancer. This study aimed to determine the prognostic significance of the number of recurrences in esophageal cancer. Methods: Patients with squamous cell carcinoma who underwent curative esophagectomy with R0 or R1 resection and who experienced a confirmed recurrence were included. The study included 321 eligible participants from March 2001 to December 2019. The relationship between the number of recurrences and post-recurrence survival was investigated. Results: The mean age was 63.8±8.1 years, and the majority of the participants (97.5%) were men. The median time to recurrence was 10.7 months, and the median survival time after recurrence was 8.8 months. Multiple recurrences with simultaneous local, regional, and distant locations were common (38%). In terms of the number of recurrences, single recurrences were the most common (38.3%) and had the best post-recurrence survival rate (median, 17.1 months; p<0.001). Patients with 2 or 3 recurrences showed equivalent survival to each other and longer survival than those with 4 or more (median, 9.4 months; p<0.001). In the multivariable analysis, the significant predictors of post-recurrence survival were body mass index, minimally invasive esophagectomy, N stage, R0 resection, post-recurrence treatment, and the number of recurrences (p<0.05). Conclusion: After esophagectomy, the number of recurrences was the most significant risk factor influencing post-recurrence survival in patients with esophageal cancer. In esophageal cancer, oligo-recurrence can be defined as a recurrence with three or fewer metastases. More intensive treatment might be recommended if oligo-recurrence occurs.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.42 no.8 s.338
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• pp.17-24
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• 2005

This paper proposes a Decision Feedback Equalizer (DFT) with an error feedback filter for blind channel equalization. The proposed equalizer uses Least Mean Square(LMS) Algorithm and Multi-Modulus Algorithm (MMA), and has been designed for 64/256 QAM constellations. The existing MMA equalizer uses either two transversal filters or feedforward and feedback filers, while the proposed equalizer uses feedforward, feedback and error feedback filters to improve the channel adaptive performance and to reduce the number of taps. The proposed equalizer has been simulated using the $SPW^{TM}$ tool and it shows performance improvement. It has been modeled by VHDL and logic synthesis has been performed using the $0.25\;\mu m$ Faraday CMOS standard cell library. The total number of gates is about 190,000 gates. The proposed equalizer operates at 15 MHz. In addition, FPGA vertification has been performed using FPGA emulation board.

• Structural Engineering and Mechanics
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• v.75 no.5
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• pp.621-631
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• 2020

A laboratory experiment is conducted is to investigate the behaviour of a low-mass-ratio and high aspect ratio flexible cylinder under vortex-induced vibration (VIV). A flexible cylinder with aspect ratio of 100 and mass ratio of 1.17 is towed horizontally to generate uniform flow profile. The range of Reynolds number is from 1380 to 13800. Vibration amplitude, in-line and cross-flow frequency response, amplitude trajectory, mean tension variation and hydrodynamic force coefficients are analyzed based on the measurement from strain gauges, load cell and CCD camera. Experimental results indicate that broad-banded lock-in region is found for the cylinder with a small Strouhal number. The frequency switches in the present study indicates the change of the VIV phenomenon. The hydrodynamic force responses provide more understanding on the VIV of a low mass ratio cylinder.

• Journal of Veterinary Clinics
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• v.19 no.1
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• pp.73-79
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• 2002

To investigate the usability of frozen canine embryos for embryo transfer in the dog, 19 donors, 3 recipients, and 6 male dogs were used for the experiment. Natural mating or artificial insemination was performed for breeding the bitches in natural estrus. Vaginal smear test along with progesterone titre test were performed to detect the appropriate mating time and the bitches were bred twice during 3-6days following LH surge. Embryo collection was done on 8, 9-11, 12-13 days after the second mating to collect morula and blastocyst. Embryos were frozen using a programmable freezer and preseued in LNE tank. Embryos were thawed in 37$^{\circ}C$ water for 15 seconds and transferred into each uterine horn within 30 minutes. Embryos were collected from 13 bitches of 19 donors(68.4%) and the collected embryos were from between 9 and 13 days after 2nd mating. Embryos were produced both by natural mating(60.0%, 9115) and AI with frozen semen(100.0%, 4/4). Embryos were collected from the donors weighed between 2.5 and 30 kg and their age was from 1.5 to 3 years. 52 embryos were collected from 13 donors and the mean number of embryos was four. The stage of embryos was from 2-cell to gastrula and morulae were colledted mostly from 10 to 11 days after 2nd mating. Embryos were collected evenly from each uterine horn and the rate of embryo collection for the number of corpus luteum was 83.9%. Embryos were transferred to 3 recipients(morula 8, blastocyst 1, gastrula 8), however, no offspring was produced.

• Anatomy and Cell Biology
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• v.56 no.4
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• pp.474-481
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• 2023

The dental characteristics created by acquired dental treatments can be used as age estimators. This pilot study aimed to analyze the correlation between the number of teeth observed for dental characteristics and chronological age and to develop new non-invasive age estimation models. Dental features on panoramic radiographs (420 radiographs of subjects aged 20-89 years) were classified and coded. The correlation between the number of teeth for each selected code (codes V, X, T, F, P, and L) and age was observed, and multiple regression was performed to analyze the relationship between them. Eleven regression models with various combinations of dental sextants were presented. The model with the data from both sides of the posterior teeth on both jaws showed the best performance (root mean square error of 14.78 years and an adjusted R² of 0.461). The model with all teeth was the second-best. Based on these results, we confirmed statistically significant correlations between certain dental features and chronological age. We also observed that some regression models performed sufficiently well to be used as adjunctive methods in forensic practice. These results provide valuable information for the design and performance of future full-scale studies.

• Proceedings of the IEEK Conference
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• 2000.06b
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• pp.238-241
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• 2000

This paper describes an equalizer using the DFE (Decision Feedback Equalizer) structure, CMA. (Constant Modulus Algorithm) and LMS (Least Mean Square) algorithms. We employ high speed multipliers, square logics and many CSAs (Carry Save Adder) for high speed operations. We have developed floating-point models and fixed-point models using the COSSAP$\^$TM/ CAD tool and developed VHDL models. We have peformed logic synthesis using the SYNOPSYS$\^$TM/ CAD tool and the SAMSUNG 0.5 $\mu\textrm{m}$ standard cell library (STD80). The total number of gates is about 130,000.

• Food Science and Biotechnology
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• v.16 no.3
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• pp.361-366
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• 2007

As the application of quantitative risk assessment (QRA) to food safety becomes widespread, it is now being questioned whether experimental results and simulated results coincide. Therefore, this paper comparatively analyzed experimental data and simulated data of the cross contamination, which needs summation of the simplest calculations in QRA, of chicken by Monte Carlo simulation and fuzzy math computation. In order to verify summation, the following basic operation was performed. For the experiment, thigh, breast, and a mixture of both parts were preserved for 24 hr at $20^{\circ}C$, and then the cell number of Salmonella spp. was measured. In order to examine the differences between experimental results and simulated results, we applied the descriptive statistics. The result was that mean value by fuzzy math computation was more similar to the experimental than that by Monte Carlo simulation, whereas other statistical descriptors by Monte Carlo simulation were more similar.