• The Journal of Korean Institute of Communications and Information Sciences
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• v.34 no.10B
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• pp.981-987
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• 2009

Recently, the study on wireless body area network for providing ubiquitous healthcare services has been actively done, including the standardization of the IEEE and others. Wireless body area network is usually configured in tree format using multi-hop communication mode due to the power limitation and the characteristics of human body. In this case, differently from existing sensor network, the wireless body area network tends to be disconnected due to the frequent movement of human body. The number of connections which can be supported at each node has some limitations due to the constraint imposed on power consumption. In this paper, we have proposed a heuristic algorithm for optimal selection of parent node with guaranteed QoS for a disconnected node, which considers the priority on packet transmission. Simulation has been performed to evaluate the performance of the proposed algorithm.

• The Korean Journal of Applied Statistics
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• v.10 no.1
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• pp.85-104
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• 1997

Proportional hazards model has been widely used for analyzing survival data. This article reviews some well-known goodness-of-fit tests for proportional hazards model. Simulation studies also provide some insights into the properties of these test statistics across several types of survival distributions and degerees of censorship.

• Journal of Veterinary Clinics
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• v.32 no.1
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• pp.45-48
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• 2015

The purpose of this study was to select high-quality boar semen after the glass wool filtration of extended boar semen. After collecting boar semen, its concentration, morphology, viability, and motility were examined according the glass wool's height and time. After glass wool filtration, the sperm concentration decreased, but the proportion of normal sperms and the sperm viability increased. Nevertheless, the sperm motility showed no changes. The above results showed that the glass wool filtration of boar semen is a method of obtaining sperms with relatively low abnormal rates and high viabilities.

• Journal of fish pathology
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• v.13 no.1
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• pp.15-20
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• 2000

Infection rates with white spot baculovirus(WSBV) in wild-caught shrimp spawners appeared to be 52% in Penaeus chinensis and 20% in Penaeus japonicus when diagnosed by polymerase chain reaction (PCR). Infection rates of WSBV from inhabitant organisms in shrimp farm showed 37% in Upogebia major and 29% in Calliamassa japonica. The viruses maintained their survivorship in seawater at $4^{\circ}C$, but lost it at $25^{\circ}C$.

• Journal of the Korean Data and Information Science Society
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• v.9 no.1
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• pp.37-45
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• 1998

We consider the problem of obtaining the confidence bands for the survival function with incomplete data. It is a rather simple procedure for constructing confidence bands of survival function. This method uses the weak convergence of normalized cumulative hazard estimator to a mean zero Gaussian process whose distribution can be easily approximated through simulation. Finally, we compare the performance of the proposed confidence bands through Monte Carlo simulation and we applied to construct the proposed bands with the Leukemia patient data.

• Journal of the Korean Data and Information Science Society
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• v.2
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• pp.45-62
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• 1991

In this paper we propose new nonparametric estimators of the survival function using spline function under the progressively random censoring scheme. This sampling scheme is applied in many practical situations such as clinical trials or the life testing problems. We also investigate the behaviors for some estimators in the proposed class and the performance of progressively random censoring scheme through the numerical examples and Monte Carlo simulation.

• Proceedings of the Korean Society of Computer Information Conference
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• 2020.01a
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• pp.147-148
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• 2020

본 논문에서는 가상현실(Virtual Reality)을 구현할 수 있는 개발도구인 Unreal Engine4를 사용하여 객체지향 설계도구인 블루 프린트(Blue Print)로 좀비 슈팅 게임을 개발하였다. 본 게임콘텐츠는 1인칭 시점의 주인공 캐릭터가 게임 인공지능으로 공격하는 좀비로부터 공격을 당하지 않고 무사히 살아남는 생존을 목표로 하는 콘텐츠이다. 게임 조작 방법은 컨트롤러(Controller)로 가상 슈팅 무기를 이용하여 제한시간 동안 공격하는 좀비들을 물리치고 가상공간에서 생존해야 한다.

• Journal of Aquaculture
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• v.14 no.3
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• pp.165-171
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• 2001

Tolerance limits of the adult crab were determined by exposing them to different temperatures (5~2$0^{\circ}C$) and salinities(12~32$\textperthousand$). The tolerance limit for high temperature was determined at 14$^{\circ}C$ and 16$^{\circ}C$ for male and female snow crab, respectively and that for salinity was 21 $\textperthousand$ at 5 $^{\circ}C$. Osmolality concentration, Na$^{+}$ and $K^{+}$ ions in the haemolymph of especially, the females was positively related to the salinity changes. Increased water temperature resulted in a marked decreased in ionic and osmolality concentrations near the limit of tolerance in male, however, such a clear pattern was not apparent for the females. The concentration of glucose in the haemolymph was positively related to water temperature but negatively to salinity.ity.

• Journal of KIISE
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• v.42 no.12
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• pp.1495-1502
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• 2015

Data compression involves a trade-off between delay time and data size. Greater delay times require smaller data sizes and vice versa. There have been many studies performed in the field of wireless sensor networks on increasing network life cycle durations by reducing data size to minimize energy consumption; however, reductions in data size result in increases of delay time due to the added processing time required for data compression. Meanwhile, as energy generation occurs periodically in solar energy-based wireless sensor networks, redundant energy is often generated in amounts sufficient to run a node. In this study, this excess energy is used to reduce the delay time between nodes in a sensor network consisting of solar energy-based nodes. The energy threshold value is determined by a formula based on the residual energy and charging speed. Nodes with residual energy below the threshold transfer data compressed to reduce energy consumption, and nodes with residual energy above the threshold transfer data without compression to reduce the delay time between nodes. Simulation based performance verifications show that the technique proposed in this study exhibits optimal performance in terms of both energy and delay time compared with traditional methods.

• Radiation Oncology Journal
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• v.19 no.2
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• pp.163-170
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• 2001

Purpose : The measurement of radiation survival using a clonogenic assay, the established standard, can be difficult and time consuming. In this study, We have used the MTT assay, based on the reduction of a tetrazolium salt to a purple formazan precipitate by living cells, as a substitution for clonogenic assay and have examined the optimal condition for performing this assay in determination of radiation sensitivity. Materials and Methods : Four human cancer cell lines - PCI-1, SNU-1066, NCI-H630 and RKO cells have been used. For each cell line, a clonogenic assay and a MTT assay using Premix WST-1 solution, which is one of the tetrazolium salts and does not require washing or solubilization of the precipitate were carried out after irradiation of 0, 2, 4, 6, 8, 10 Gy. For clonogenic assay, cells in $25\;cm^2$ flasks were irradiated after overnight incubation and the resultant colonies containing more than 50 cells were scored after culturing the cells for $10\~14$ days. For MTT assay, the relationship between absorbance and cell number, optimal seeding cell number, and optimal timing of assay was determined. Then, MTT assay was performed when the irradiated cells had regained exponential growth or when the non-irradiated cells had undergone four or more doubling times. Results : There was minimal variation in the values gained from these two methods with the standard deviation generally less than $5\%$, and there were no statistically significant differences between two methods according to t-test in low radiation dose (below 6 Gy). The regression analyses showed high linear correlation with the $R^2$ value of $0.975\~0.992$ between data from the two different methods. The optimal cell numbers for MTT assay were found to be dependent on plating efficiency of used cell line. Less than 300 cells/well were appropriate for cells with high plating efficiency (more than $30\%$). For cells with low plating efficiency (less than $30\%$), 500 cells/well or more were appropriate for assay. The optimal time for MTT assay was after 6 doubling times for the results compatible with those of clonogenic assay, at least after 4 doubling times was required for valid results. In consideration of practical limits of assay (12 days, in this study) cells with doubling time more than 3 days were inappropriate for application. Conclusion : In conclusion, it is found that MTT assay can successfully replace clonogenic assay of tested cancer cell lines after irradiation only if MTT assay was undertaken with optimal assay conditions that included plating efficiency of each cell line and doubling time at least.