• Journal of the Institute of Electronics Engineers of Korea CI
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• v.47 no.6
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• pp.19-27
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• 2010

Many security issues occur in cloud computing service environment such as authentication, access control, and so on. In this paper, we propose an effective authentication and access control model which provide integrated management and control when we access various resources in cloud computing environment. To address these problems, we suggest a context-aware single sign-on and access control system using context-awareness, integrated authentication, access control, and OSGi service platform in cloud computing environment. And we show design and implementation of context-aware single sign-on and access control system. Also we verified the flexibility and convenience of the proposed system through multi fact based integrated authentication in cloud computing environment. We could provide flexible and secure seamless security service by user context in cloud computing environment.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.15 no.7
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• pp.1501-1509
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• 2011

Current identity management 1.0 model, which is service provider-centric and isolated, has several problems such as low usability, high cost structure, difficulty in privacy protection, and lack of trust infrastructure. Though various SSO-based identity management 2.0 models including Passport/Live ID, Liberty Alliance/SAML, CardSpace, and OpenID have been recently developed in order to overcome those problems, they are not widely accepted in real Internet environment so as to replace the existing identity management 1.0 model. This paper firstly analyzes the widely-known identity 2.0 models in a comparative way, and then presents a perspective on the development direction of identity management 3.0 model for future Internet.

• Korean Journal of Radiology
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• v.20 no.5
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• pp.729-738
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• 2019

Objective: To assess the effects of iterative model reconstruction (IMR) on image quality for demonstrating non-calcific high-risk plaque characteristics of coronary arteries. Materials and Methods: This study included 66 patients (53 men and 13 women; aged 39-76 years; mean age, 55 ± 13 years) having single-vessel disease with predominantly non-calcified plaques evaluated using prospective electrocardiogram-gated 256-slice CT angiography. Paired image sets were created using two types of reconstruction: hybrid iterative reconstruction (HIR) and IMR. Plaque characteristics were compared using the two algorithms. The signal-to-noise ratio (SNR) and contrast-to-noise ratio (CNR) of the images and the CNR between the plaque and adjacent adipose tissue were also compared between the two reformatted methods. Results: Seventy-seven predominantly non-calcified plaques were detected. Forty plaques showed napkin-ring sign with the IMR reformatted method, while nineteen plaques demonstrated napkin-ring sign with HIR. There was no statistically significant difference in the presentation of positive remodeling, low attenuation plaque, and spotty calcification between the HIR and IMR reconstructed methods (all p > 0.5); however, there was a statistically significant difference in the ability to discern the napkin-ring sign between the two algorithms (χ² = 12.12, p < 0.001). The image noise of IMR was lower than that of HIR (10 ± 2 HU versus 12 ± 2 HU; p < 0.01), and the SNR and CNR of the images and the CNR between plaques and surrounding adipose tissues on IMR were better than those on HIR (p < 0.01). Conclusion: IMR can significantly improve image quality compared with HIR for the demonstration of coronary artery and atherosclerotic plaques using a 256-slice CT.

• Journal of Korean Medicine Rehabilitation
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• v.29 no.4
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• pp.101-108
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• 2019

Objectives The purpose of this study is to evaluate the safety of Gunghatang tablet in healthy male volunteers. Methods Single center pharmacokinetics study was carried out in healthy male volunteers. Through the laboratory test, vital sign and adverse event data, safety evaluation was conducted. Total 15 of 16 subjects who met the inclusion criteria were enrolled and three subjects were allocated to waiting group. 12 subjects were allocated by serial number according to registration order. Subjects took the maximum daily dose of the tablet on the second day of hospitalization. For the evaluation of safety, blood samples were collected and vital sign were checked 4 times (screening, before administration, after administration and follow up period) during the trial. All adverse events were recorded and summarized as frequency and percentage. All continuous data were summarized as mean and standard deviation. For comparison of variables between before administration and after administration, data were analyzed by paired T-test or Wilcoxon signed rank test (p<0.05). Results As a result of all data related to vital sign and laboratory test in both group, there were no significant differences associated with the clinical trial drug between pre and post administration. And there was no adverse event associated with the clinical trial drug. Conclusions Gunghatang tablet were found to be safe for healthy male volunteers.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.11 no.12
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• pp.6017-6037
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• 2017

In a multi-resolution image encoding system, the image is encoded into a single file as a layer of bit streams, and then it is transmitted layer by layer progressively to reduce the transmission time across a low bandwidth connection. This encoding scheme is also suitable for multiple decoders, each with different capabilities ranging from a handheld device to a PC. In our previous work, we proposed an edge adaptive hierarchical interpolation algorithm for multi-resolution image coding system. In this paper, we enhanced its compression efficiency by adding three major components. First, its prediction accuracy is improved using context adaptive error modeling as a feedback. Second, the conditional probability of prediction errors is sharpened by removing the sign redundancy among local prediction errors by applying sign flipping. Third, the conditional probability is sharpened further by reducing the number of distinct error symbols using error remapping function. Experimental results on benchmark data sets reveal that the enhanced algorithm achieves a better compression bit rate than our previous algorithm and other algorithms. It is shown that compression bit rate is much better for images that are rich in directional edges and textures. The enhanced algorithm also shows better rate-distortion performance and visual quality at the intermediate stages of progressive image transmission.

• Journal of KIISE:Computing Practices and Letters
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• v.10 no.3
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• pp.259-272
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• 2004

This paper suggests a new security architecture for facilitating secure OSGi service platform environment. The security architecture includes 1) user authentication mechanism, 2) bundle authentication mechanism, 3) key sharing mechanism, and 4) authorization mechanism. The user authentication mechanism supplies SSO(single sign-on) functions which are useful for safe and easy user authentications. The bundle authentication mechanism utilizes both PKI-based and MAC-based digital signatures for efficiently authenticating service bundles. The key sharing mechanism, which is performed during bootstrapping phase of a service gateway, supplies a safe way for sharing secret keys that are required for authentication mechanisms. Finally, the authorization mechanism suggests distributed authorization among service providers and an operator by establishing their own security policies. The main contributions of the parer are twofold. First, we examine several security requirements of current OSGi specification when its security functions can be applied in real OSGi environments. Second, we describe the ways to resolve the problems by means of designing and implementing concrete security mechanisms.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.14 no.5
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• pp.11-21
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• 2004

To authorize IPSec-VPN Client in Client-to-Gateway type of the IPSec-VPN system, it can be normally used with ID/Password verification method or the implicit authorization method that regards implicitly IPSec-VPN gateway as authorized one in case that the IPSec-VPN client is authenticated. However, it is necessary for the Client-to-Gateway type of the IPSec-VPN system to have a more effective user authorization mechanism because the ID/Password verification method is not easy to transfer the ID/Password information and the implicit authorization method has the vulnerability of security. This paper proposes an effective user authorization mechanism using an attribute certificate and designs a user authorization engine. In addition, it is implemented in this study. The user authorization mechanism for the IPSec-VPN system proposed in this study is easy to implement the existing IPSec-VPN system. Moreover, it has merit to guarantee the interoperability with other IPSec-VPN systems. Furthermore, the user authorization engine designed and implemented in this paper will provide not only DAC(Discretional Access Control) and RBAC(Role-Based Access Control) using an attribute certificate, but also the function of SSO(Single-Sign-On).

• The Journal of Korean Medicine
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• v.35 no.2
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• pp.28-33
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• 2014

Background: Samul-tang (Si-Wu-Tang, SMT) is a traditional herbal formula, which has been widely used to treat various diseases such as menstrual irregularity, bleeding and leucorrhea. Although many studies have investigated the pharmacological properties of SMT, its toxicity information has not yet been fully elucidated. Methods: Five Sprague Dawley (SD) rats of each sex were given a single dose (5000 mg/kg) of SMT by gavage; control rats received the vehicle only. After the single administration, mortality, clinical signs, body weight changes and gross findings were monitored for 15 days in accordance with Good Laboratory Practice (GLP) principles. Results: In a single oral dose toxicity study, there was no adverse effect on mortality, clinical sign, body weight change or gross finding in any treatment group. Conclusions: The results indicate that SMT did not induce toxic effects at a dose level up to 5000 mg/kg in rats and its median lethal dose ($LD_{50}$) was considered to be over 5000 mg/kg/day body weight for both genders.

• Journal of Physiology & Pathology in Korean Medicine
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• v.22 no.2
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• pp.296-301
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• 2008

The purpose of this study was to examine to observe single and four weeks repeated toxicity in mice of Bangpung-galgeun-tang (BGT). We investigated to ascertain safety and toxicity of BGT, we divided into single and four weeks repeated administration test. In single test, three groups were administrated different dosages and routes (2 g/kg/i.p., 4 g/kg/i.p. and 15 g/kg/p.o.) of BGT, and in four weeks repeated test, 0.8 g/kg BGT was administrated. Control groups were administrated with only saline according to on Korean Food and Drug Administration, respectively. We observed attentively motality, abnormal clinical sign, body weight change, organ weight, AST and ALT of mice after BGT administration. During toxicity experiment period, there was no difference in body weight change, organ weight, AST and ALT among different dose groups. Death were found 3 mice from day 2 to day 3 in single test i.p. group. (2 g/kg, 4 g/kg). Several individuals of single test i.p. group were observed that decreased locomotor activity, exophthalmos, bloodshot eyes, loss of eyesight and so on in early period after administration. But there was no difference in clinical signs among p.o. group. These results indicate that BGT have inhibition effects on allergy and suggest that no observable effect level of the test orally administration was considered to be more than 2 g/kg in mice under the conditions employed in this study.

• Journal of Korea Foundry Society
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• v.7 no.2
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• pp.108-113
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• 1987

Al-Cr alloy with composition in the range from 1.5 wt% to 10 wt% Cr were rapidly solidified from the melt by the single roller method. The supersaturated solid solution was obtained up to 6 wt% Cr in Al-Cr alloy for $20{\mu}m$ thickness. Lattice parameter decreased with increasing Cr content at the rate of 0.00456A per wt% Cr up to 6 wt% Cr. Microhardness increased with increasing Cr content at the rate of $10\;Kg/mm^2$ per wt% Cr up to 6 wt% Cr. Microhardness measurements on the Al-6 wt% Cr supersaturated solid solution annealed isothermally showed no sign of age hardening. Decomposition temperature, determined by lattice parameter changes and microhardness changes, was $470^{\circ}C$ for Al-6 wt% Cr supersaturated solid solution. Transmission electron microscopy showed that decomposition within one hour below $400^{\circ}C$ occurred at grain boundaries only, and also the additional decomposition within grains being evident at $450^{\circ}C$ The coarse precipitate structure showed at $500^{\circ}C$ and $550^{\circ}C$, respectively. The coarse precipitate structure is considered $Al_7Cr$.