• The KIPS Transactions:PartC
• /
• v.11C no.1
• /
• pp.47-54
• /
• 2004

The growth of computer resource and network speed has increased requests for the use of remotely located computer systems by connecting through computer networks. This phenomenon has hoisted research activities for application service provision that uses server-based remote computing paradigm. The server-based remote computing paradigm has been developed as the ASP (Application Service Provision) model, which provides remote users through application sharing protocol to application programs. Security requirement such as confidentiality, availability, integrity should be satisfied to provide ASP service using centralized computing system. Existing Telnet or FTP service for a remote computing systems have satisfied security requirement by a simple access control to files and/or data. But windows-based centralized computing system is vulnerable to confidentiality, availability, integrity where many users use the same application program installed in the same computer. In other words, the computing system needs detailed security level for each user different from others, such that only authorized user or group of users can run some specific functional commands for the program. In this paper, we propose windows based centralized computing system that sets security policies for each user for the use of instructions of the application programs, and performs access control to the instructions based on the security policies. The system monitors all user messages which are executed through graphical user interface by the users connecting to the system. Ail Instructions, i.e. messages, for the application program are now passed to authorization process that decides if an Instruction is delivered to the application program based on the pre-defined security polices. This system can be used as security clearance for each user for the shared computing resource as well as shared application programs.

• Journal of KIISE:Databases
• /
• v.29 no.3
• /
• pp.230-245
• /
• 2002

Database systems for real-time applications must satisfy timing constraints associated with transactions. Typically, a timing constraint is expressed in the form of a deadline and is represented as a priority to be used by schedulers. Recently, security has become another important issue in many real-time applications. In many systems, sensitive information is shared by multiple users with different levees of security clearance. As more advanced database systems are being used in applications that need to support timeliness while managing sensitive information, there is an urgent need to develop concurrency control protocols in transaction management that satisfy both timing and security requirements. In this paper, we propose two concurrence control protocols that ensure both security and real-time requirements. The proposed protocols are primarily based on multiversion locking. However, in order to satisfy timing constraint and security requirements, a new method, called the FREEZE, is proposed. In addition, we show that our protocols work correctly and they provide a higher degree of concurrency than existing multiversion protocols. We Present several examples to illustrate the behavior of our protocols, along with performance comparisons with other protocols. The simulation results show that the proposed protocols can achieve significant performance improvement.

• Journal of Pharmaceutical Investigation
• /
• v.38 no.1
• /
• pp.15-21
• /
• 2008

Liposomes as one of the efficient drug carriers have some shortcomings such as their short circulation time, fast clearance from human body by reticuloendothelial system (RES) and limited intracellular uptake to target cell. In this study, polyethylenglycol (PEG)-incorporated cationic liposomes were prepared by ionic complexation of positively charged liposomes with carboxylated polyethyleneglycol (mPEG-COOH). The cationic liposomes had approximately $98.6{\pm}1.0nm$ of mean particle diameter and $42.8{\pm}0.8mV$ of zeta potential value. The PEG-incorporated cationic liposomes had $110.1{\pm}1.2nm$ of mean particle diameter with an increase of about 10 nm compared to the cationic liposomes. Zeta potential value of them was $12.9{\pm}0.6mV$ indicating 30mV decrease of cationic charge compared to the cationic liposomes. The amount of PEG which was incorporated onto the cationic liposomes was assayed by using picrate assay method and the incorporation efficiency was $58.4{\pm}1.1%$. Loading efficiency of model drug, doxorubicin, into cationic liposomes or PEG-incorporated cationic liposomes was about $96.0{\pm}0.7%$. Results of intracellular uptake which were evaluated by flow cytometry analysis of doxorubicin loaded liposomes showed that intracellular uptake of PEG-incorporated cationic liposomes was higher than the cationic liposomes or DSPE-mPEG liposomes. In addition, cytotoxicity of PEG-incorporated cationic liposomes was comparable to cationic liposomes. Consequently, the PEG-incorporated cationic liposomes of which surface was incorporated with PEG by ionic complex may be applicable as anticancer drug carriers that can increase therapeutic efficacy.

• Journal of the Korea Concrete Institute
• /
• v.18 no.4 s.94
• /
• pp.527-534
• /
• 2006

This paper outlines a new strengthening technique for concrete beams using externally unbended high-strength bars. The advantages of proposed method lie in speed and simplicity of construction compared to the alternative strengthening method. Externally unbended reinforcement retains many of the advantages over external unbended prestressed tendons. It eliminates time consuming stressing operations. Clearance requirements around anchorages are reduced as access is not required for prestressing jacks. Test results of eight specimens on reinforced concrete beams using different reinforcement materials such as carbon fiber sheet, steel plate and high-tension bar are reported. The beam strengthened by carbon fiber sheet showed a brittle failure mode due to the separation of fiber. As a result of draped profile of external bar, the maximum strength of the beam were increased by up to 212 percent and the deflections were reduced by up to 65 percent. Test results show that the beams reinforced with high-tension bar are superior to reference specimens, especially for the strength and deformation capacity.

• Journal of Radiopharmaceuticals and Molecular Probes
• /
• v.1 no.1
• /
• pp.53-61
• /
• 2015

Lutetium-177 ($T_{1/2}=6.71day$) is an adequate radionuclide for therapy, which has both beta emission ($E_{max}=497keV$) for therapeutic effect and gamma emission (113 and 208 keV) for imaging. $^{177}Lu$ labeled ethylenediamine-N,N,N',N'-tetrakis (methylene phosphonic acid) (EDTMP) and 1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraaminomethylenephosphonate (DOTMP) have been proposed as radiopharmaceuticals for bone pain palliation. In this study, we compared radiochemistry and biodistribution of $^{177}Lu$-EDTMP and $^{177}Lu$-DOTMP. EDTMP and DOTMP were synthesized, and 1 mg of each was labeled with $^{177}Lu$ at pH 7~8 with high efficiency (>98%). For comparative biodistribution studies, $^{177}Lu$-EDTMP or $^{177}Lu$-DOTMP were injected into ICR-mice through tail vein, and then biodistribution data were obtained as percentages of injected dose per gram of tissue (% ID/g). Urine excretions of both agents in mice were checked for 7 days. Rat images were also obtained after injection of $^{177}Lu$-EDTMP or $^{177}Lu$-DOTMP. $^{177}Lu$-DOTMP (100% at 1 min) showed faster labeling than $^{177}Lu$-EDTMP (100% at 30 min). Both of them were stable at least for 21 days at room temperature. High bone uptakes were found for both $^{177}Lu$-EDTMP and $^{177}Lu$-DOTMP: 38.0 and 34.1% ID/g at 3 hr, respectively; and 33.2 and 18.8% ID/g at 7 day, respectively. Rapid excretions to urine were found for both agents ($^{177}Lu$-EDTMP: 56%, $^{177}Lu$-DOTMP: 63% at 1 day). Other organs showed very low uptakes. Rat images of both $^{177}Lu$-EDTMP and $^{177}Lu$-DOTMP showed high bone uptakes and low soft tissue uptakes. In conclusion, both $^{177}Lu$-EDTMP and $^{177}Lu$-DOTMP showed high potential as bone pain palliation agents. $^{177}Lu$-EDTMP showed higher bone uptake and slower bone clearance in mice than those of $^{177}Lu$-DOTMP.

• Journal of Korean Society of Steel Construction
• /
• v.9 no.4 s.33
• /
• pp.697-705
• /
• 1997

The conventional preflex beams are designed by the method of paritial prestressing and allow the tensile stresses at the lower concrete of beams. As a consequence, most of preflex beams experience the tensile cracks under the service loads. This study was conducted to develop the most effective preflex beams, which do not allow tensile stress under the service load, by introducing additional prestressing called 'represtressing' at the lower concrete of beams. The objective of the study was accomplished by developing a computer analysis and design program and conducting experiments. Using the developed computer program, standard sections of the represtressed preflex beams were determined by computer modeling. In the experiment, two actual size of represtressed beams were tested under the imitated service loads. The results of test have shown that the performance of the represtressed preflex beams is generally excellent. A remarkable improvement was made in the design of preflex composite beams. Since the represtressed preflex beams(RPF) do not experience the tensile cracks under the service loads, the use of this beam for the bridge structures will lead to easy bridge maintenance and management. Furthermore, due to the low beam depth, high clearance and economical design can be realized in the bridge design using RPF.

• Journal of Korean Society of Transportation
• /
• v.24 no.4 s.90
• /
• pp.93-101
• /
• 2006

The signalized intersections near highway-railroad grade crossing are operated without signal preemption in Korea when trains are approaching the crossing. This signal operation is very dangerous because queues from the intersection can extend back over the track, thereby creating the Potential for a serious vehicle-train accident. And the queues from the crossing can extend to the intersection with the normal signal operation while trains Pass the crossing. In this case the intersection is disrupted, and delay and the Potential for vehicle accident increase highly In order to improve the intersection performance and Protect the accident the crossings and intersections. signal Preemption designed to provide a special control mode should be implemented. In this study it was shown that intersection Performance near highway-railroad grade crossing improved using signal preemption. When signal Preemption is implemented at the test site, the delay was reduced by about 9sec/veh. Even though there were vehicle-train accidents at the crossing in all 30 simulations without signal preemption. there was no vehicle-train accidents at all when signal preemption is used.

• Journal of Veterinary Clinics
• /
• v.23 no.2
• /
• pp.87-90
• /
• 2006

The aim of the present study was to investigate the disposition pharmacokinetics of roxithromycin in broilers. Roxithromycin was administered at a single dose of 20 mg/kg body weight by intravenous (i.v.) routes. Plasma concentrations of roxithromycin were determined by liquid chromatography/mass spectrometry. After a single i.v. dose plasma concentrations were best fitted to a two-compartment open model. The values of the pharmacokinetic parameters after i.v. administration were: elimination half-life = $5.83{\pm}1.79h$, mean residence time = $6.33{\pm}0.32h$, total body clearance = $0.55{\pm}0.15L/h/kg$, and volume of distribution at steady state = $3.47{\pm}0.84L/kg$. The pharmacokinetic interpretation of roxithromycin after i.v. administration revealed that the drug was well distributed throughout the body in broilers and slowly eliminated. More studies for the application of roxithromycin against poultry disease are needed to establish a suitable pharmaceutical formulation, propose optimum dosage regimens, investigate clinical efficacy and study the tolerability of repeated doses.

• Journal of Physiology & Pathology in Korean Medicine
• /
• v.17 no.2
• /
• pp.542-548
• /
• 2003

The present study was aimed to investigate whether glycyrrhizin, which is the major component of Glycyrrhiza uralensis, has an antioxidant effect and regulatory effect on Na,K-ATPase in gentamicin-induced acute renal failure (ARF) rats . It is well known that reactive oxygen species (ROS), such as superoxide anion and hydroxyl radical, are main pathophysiological factor in gentamicin-induced ARF. Glycyrrhizin showed potent in vitro antioxidant activity, especially superoxide scavenging activity, in a dose-dependent manner. Plasma lipid peroxide level was restored to normal level by oral administration of glycyrrhizin (200 mg/kg) in the gentamicin-induced ARF rats. The expression of Na,K-ATPase α1 subunit was restored in the gentamicin-induced ARF rats by administration of glycyrrhizin, whereas β1 subunit was not restored. The renal functional parameters including urine volume, cleatinine clearance, urine osmolality, solute-free water reabroption were also partially restored in gentamicin-ARF rats by administration of glycyrrhizin. Taken together, the amelioration of renal functions and the expression of sodium pump by administration of glycyrrhizin in the gentamicin-induced ARF was appear to be mediated by the scavenging of ROS.

• Journal of Physiology & Pathology in Korean Medicine
• /
• v.17 no.2
• /
• pp.316-325
• /
• 2003

In this paper, the effect of Ganopoly(extracts of Ganoderma lucidum) and Ganopoly/C+(70% Ganopoly + 30% chitosan) on cisplastin-induced nephrotoxicity was investigated in Sprague-Dawley rats. A single dose of cisplastin(5 ㎎/㎏) kg) was administered intraperitoneally after pretreatment of saline, Ganopoly and Ganopoly/C+ for 7 days. The nephrotoxicity and renal function were manifestated by the changes of body weight, blood pressure, biochemical changes and solute in urine and plasma. After the treatment of CDDP(cis-dichlorodiamineplatinum), a significant elevation of kidney weight, serum urea, cretinine, urine volume for 24 hours, urine magnesium, and a severe or significant decrease in body weight, blood pressure, creatinine clearance, urine osmolarity, serum albumin, etc. The nephrotoxicity was further confirmed by a significant decrease in glutathione S-transferase(GSH) in urine and kidney homogenate, GSH, glutathione peroxidase(GSH-Px) and catalase in kidney tissue. And also the lipid peroxidation was significantly increased in kidney homogenate. These signs of nephrotoxicity was ameliorated by the pretreatment and consecutive administration of Ganopoly and Ganopoly/C+ for 14 days after the Lp. injection of CDDP on 7th day after pretreatment of Ganopoly and Ganopoly/C+. The amelioration of nephrotoxicity was evidenced by significant reduction in serum urea and creatinine concentration, and improvement of other index of renal function. And The activity of antioxidant enzymes were partially recovered in kidney tissue of rats treated by CDDP and the administration of Ganopoly and Ganopoly/C+. These results indicate the cispastin induced nephrotoxicity is due to an impairment of tubular reabsorption systems enhanced by necrosis of proximal tubule, and the Ganopoly and Ganopoly/C+ has a partial protective effect on nephrotoxicity induced by CDDP. The polysacchride of Ganoderma lucidum may improve the therapeutic index of nephrotoxicity induced by CDDP. However, it is needed to elucidate the mechanism for confirming the therapeutic effect.