• Proceedings of the Korean Nuclear Society Conference
• /
• 1996.11a
• /
• pp.230-235
• /
• 1996

The new concept of dry area formation based on Poisson distribution of active nucleation sites and the concept of the critical active site density is presented. A simple statistical model is developed to predict the change of slope of the boiling curve up to critical heat flux (CHF) quantitatively. The predictions by the present model are in good agreement with the experimental data. Also it turns out that the present model well explains the mechanism on how the surface wettability influences CHF.

• Journal of the Korean Statistical Society
• /
• v.29 no.4
• /
• pp.385-394
• /
• 2000

Jackknife variance estimation based on adjusted imputed values when nonresponse is nonrandom and follow-up data are available for a subsample of nonrespondents is provided. Both hot-deck and ratio imputation method are considered as imputation method. The performance of the proposed variance estimator under nonrandom response mechanism is investigated through numerical simulation.

• Journal of the Korean Statistical Society
• /
• v.28 no.2
• /
• pp.195-210
• /
• 1999

We consider a large class of exponential regression models with censored data and propose two modified Fisher scoring methods with corresponding algorithms. These proposed methods improve the Newton-Raphson method in estimating the model parameters. The simulated and real examples are illustrated in aspect of convergence.

• Journal of the Korean Statistical Society
• /
• v.32 no.1
• /
• pp.25-32
• /
• 2003

In this paper, we define the mean life process for the right censored data and show the asymptotic equivalence between two kinds of the mean life processes. We use the Kaplan-Meier and Susarla-Van Ryzin estimates as the estimates of survival function for the construction of the mean life processes. Also we show the asymptotic equivalence between two mean residual life processes as an application and finally discuss some difficulties caused by the censoring mechanism.

• Journal of Biosystems Engineering
• /
• v.22 no.2
• /
• pp.177-188
• /
• 1997

A pepper harvester using a pair of counter rotating helically wound cylinders as a pepper removal mechanism has been developed. Pepper harvesting by machines under the customary cultivation practice was expected to lower land productivity, that most farmers were concerned about. As one way to compensate for loss in land productivity by machine harvest, experts on pepper cultivation suggested change of both varieties and plant density per area. From the view of machine design, their suggestion implied that distance between rows should be narrower and height of the pepper removal mechanism could be shorter. Experiments to improve perfect pepper recovery ratio and to reduce size of the pepper removal mechanism was accomplished. In order to be a economically feasible harvester, minimum pepper recovery ratio was required to be greater or equal to 80%. The research goal was achieved by both reducing the diameter of the wire-helices from 30 cm to 18 cm and increasing rotational speed of the wire-helices up to 425 rpm. The best perfect pepper recovery ratio was 82.3%. Validity of experiment design and interpretation on statistical analysis were discussed. To understand the pepper removal mechanism properly, a pepper removal theory based physics was judged to be necessary.

• Communications for Statistical Applications and Methods
• /
• v.13 no.1
• /
• pp.73-88
• /
• 2006

In this paper, we construct data-base for fetal heart rate (FHR) data and develop the FHR Monitering system to diagnose fetus, HYFM-III. For diagnostic system, a few statistical decision making mechanism are adopted, such as approximate entropy, neural networks, and logistic discrimination. Since FHR data is very chaotic, we mostly adopt nonlinear statistical methods. On the basis of this system, we expect to develop expert system for early detection of abnormal fetus.

• Journal of Haehwa Medicine
• /
• v.25 no.1
• /
• pp.71-86
• /
• 2016

Objective : Hongyi (Formica yessensis) is the dried insect of fomicidae. In previous studies, it appeared possibilities on anti-thrombosis, preventing atherosclerosis, treating rheumatoid disease, and inhibiting hela cell. In this study, we investigated anti-inflammatory effects and mechanism of Hongyi. Methods : Hongyi A was extracted by water and made dried powder. Hongyi B was extracted by ethanol and made dried powder. We measured Nitric Oxide (NO) production on the mouse macrophages (RAW 264.7), mouse vascular endothelial cell (MOVAS) and human vascular endothelial cell (HUVEC) for anti-inflammatory effect. In addition, we conducted reverse transcription reaction (RT-PCR) for investigating the mechanism. Results : In RAW 264.7 macrophages stimulated by LPS, Hongyi A ($100{\mu}g/m{\ell}$) decreased NO production compared with LPS $2{\mu}g/ml$ control group with statistical significance (p<0.05). Hongyi A (50, $100{\mu}g/m{\ell}$) also decreased NO production compared with LPS $4{\mu}g/ml$ control group with statistical significance (p<0.01). Hongyi B (50, $100{\mu}g/m{\ell}$) decreased NO production compared with LPS $2{\mu}g/ml$ control group with statistical significance (p<0.01). Hongyi B (10, 50, $100{\mu}g/m{\ell}$) also decreased NO production compared with LPS $4{\mu}g/ml$ control group with statistical significance (p<0.01, p<0.001, p<0.001). In the MOVAS, Hongyi A and B increased NO production compared with control group. In the HUVEC, Hongyi B increased NO production compared with control group. The expression of NF-${\kappa}B$ in 12-hours MOVAS culture was decreased by Hongyi A and B (10, $50{\mu}g/ml$) compared with control group, but expression of $I{\kappa}B$ was increased. In the 24-hours MOVAS culture, expression of $I{\kappa}B$ was significantly increased. The expression of NF-${\kappa}B$ in 12-hours HUVEC culture was decreased by Hongyi A and B compared with control group, but expression of $I{\kappa}B$ was increased. Hongyi B also increased eNOS mRNA gene expression. Conclusions : Hongyi A and B showed anti-inflammatory effect in mouse macrophages with the activation of vascular endothelial cell through NO production in MOVAS and HUVEC repectively. Honyi B showed superior effect than Hongyi A, but additonal mechanism study should be conducted.

• Proceedings of the Korea Information Processing Society Conference
• /
• 2005.11a
• /
• pp.973-976
• /
• 2005

In IEEE 802.15.4 (Low-Rate Wireless Personal Area Network) specification, a successful reception and validation of a data or MAC command frame can be confirmed with an acknowledgment. However, the specification does not support security for acknowledgment frame; the lack of a MAC covering acknowledgments allows an adversary to forge an acknowledgment for any frame. This paper proposes an identity authentication mechanism at the link layer for acknowledgment frame in IEEE 802.15.4 network. With the proposed mechanism there is only three bits for authentication, which can greatly reduce overhead. The encrypted bit stream for identity authentication will be transmitted to device by coordinator within association process. Statistical method indicates that our mechanism is successful in handling MAC layer attack.

• KSII Transactions on Internet and Information Systems (TIIS)
• /
• v.12 no.7
• /
• pp.3497-3515
• /
• 2018

Differential privacy has broadly applied to statistical analysis, and its mainly objective is to ensure the tradeoff between the utility of noise data and the privacy preserving of individual's sensitive information. However, an individual could not achieve expected data utility under differential privacy mechanisms, since the adding noise is random. To this end, we proposed an adaptive Gaussian mechanism based on expected data utility under conditional filtering noise. Firstly, this paper made conditional filtering for Gaussian mechanism noise. Secondly, we defined the expected data utility according to the absolute value of relative error. Finally, we presented an adaptive Gaussian mechanism by combining expected data utility with conditional filtering noise. Through comparative analysis, the adaptive Gaussian mechanism satisfies differential privacy and achieves expected data utility for giving any privacy budget. Furthermore, our scheme is easy extend to engineering implementation.

• Journal of Trauma and Injury
• /
• v.27 no.2
• /
• pp.13-19
• /
• 2014

Purpose: In general, X-ray examinations are not recommended for radial head subluxation (pulled elbow) patients. The purpose of this study was to determine the frequency of X-ray examinations and to investigate the factors associated with the decision to perform an X-ray examination on a patient with a pulled elbow. Methods: Patients who visited the pediatric emergency department (ED) of one tertiary hospital from January 1, 2011, to December 31, 2012, with a diagnosis of radial head subluxation at discharge were enrolled in this study. Through retrospective chart reviews, factors that could have influenced the decision to perform an X-ray examination and their statistical relevance were analyzed. Results: A total 308 patients were enrolled, and 101 patients (32.8%) underwent X-ray examinations. Among the 252 patients with a typical pulled elbow, 65 underwent X-ray examination. This result showed statistical significance compared to atypical pull-elbow group (25.8% vs. 64.3%, p<0.001). Factors associated with the decision to perform an X-ray examination were analyzed using the Chi-square test and the Fisher's exact test. The mechanism of injury and consultation with an orthopedic surgeon (p=0.001) showed statistical significance. In the multivariable logistic regression, the odds ratio (OR) for the injury mechanism was 4.7 (95% CI: 1.8~8.8, p<0.001) and that for consultation with an orthopedic surgeon was 8.0 (95% CI: 1.6~40.7, p=0.004). Conclusion: One third of patients with a pulled elbow underwent X-ray examination, and patients with an atypical mechanism of injury underwent more frequent X-ray examinations than did patients with a typical mechanism of injury. The factors that could have influenced the decision to perform an X-ray examination were mechanism of injury and consultation with an orthopedic surgeon.