• Journal of the Korea Academia-Industrial cooperation Society
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• v.9 no.4
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• pp.929-935
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• 2008

As internet telephony services based on Session initiation Protocol (SIP) enter the spotlight as marketable technology, many products based on SIPs have been developed and utilized for home and office telephony services. The call connection of an internet phone is classified into specific call connections and group call connections. Group call connections have a forking function which delivers the message to all of the group members. This function requires excessive message control for a call connection and creates heavy traffic in the network. In the internet cail system model. most of the call-setup messages are directed to the proxy server during a short time period. This heavy message load brings an unwanted delay in message processing and. as a result, call setup can not be made. To solve the delay problem, we simplified the analysis of the call-setup message in the proxy server, and processed the forking function distributed for the group call-setup message. In this thesis, a new system model to minimize the load is proposed and the subsequent implementation of this model demonstrates the performance improvement.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.14 no.8
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• pp.3611-3616
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• 2013

Physical characteristics of a magneto-rheological(MR) fluid can be influenced by a magnetic field. In the present study, the behaviors of MR fluid are visualized and the shear stresses are measured under the magnetic field for density 1.3, 1.5 and 1.7 $g/cm^3$, and viscosity 100, 1000 and 10000cp. When the magnetic field is applied, particles of MR fluid are arranged along lines of magnetic field. It is observed that the flow pattern of MR fluid under the magnetic field is different from that of MR fluid without the magnetic field. Shear stress of MR fluids under the magnetic field changes significantly. Shear stress by the magnetic field increases the shape of a quadratic equation. When the density changes from $1300kg/m^3$ to $1700kg/m^3$ at 2.0A, the shear stress increases about 33%.

• Journal of Korean Neurosurgical Society
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• v.63 no.2
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• pp.210-217
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• 2020

Objective : To analyze the accuracy of iliac screws using freehand technique performed by the same surgeon. We also analyzed how the breach of iliac screws was related to the clinical symptoms resulting in revision surgery. Methods : From January 2009 to November 2015, 100 patients (193 iliac screws) were analyzed using postoperative computed tomography scans. The breaches were classified based on the superior, inferior, lateral, and medial iliac wall violation by the screw. According to the length of screw extrusion, the classification grades were as follows : grade 1, screw extrusion <1 cm; grade II, 1 cm ≤ screw extrusion <2 cm; grade III, 2 cm ≤ screw extrusion <3 cm; and grade IV, 3 cm ≤ screw extrusion. We also reviewed the revision surgery associated with iliac screw misplacement. Results : Of the 193 inserted screws, 169 were correctly located and 24 were misplaced screws. There were eight grade I, six grade II, six grade III, and four grade IV screw breaches, and 11, 8, 2, and 3 screws violated the medial, lateral, superior, and inferior walls, respectively. Four revision surgeries were performed for the grade III or IV iliac screw breaches in the lateral or inferior direction with respect to its related symptoms. Conclusion : In iliac screw placement, 12.4% breaches developed. Although most breaches were not problematic, symptomatic violations (2.1%) could result in revision surgery. Notably, the surgeon should keep in mind that lateral or inferior wall breaches longer than 2 cm can be risky and should be avoided.

• Journal of the Korean Applied Science and Technology
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• v.19 no.1
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• pp.10-18
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• 2002

In this study, it should be mentioned that Lipid-LCG can be prepared with the main compound of hydrogenated lecithin in oil-in water emulsion. The results of its physical property and stability are as follows. First, the best suitable compositions of Lipid-LCG are made from 4.0wt% of the hydrogenated lecithin, 4.0wt% of cetostearyl alcohol as emulsifier and gelling agent, 3.0wt% of butylene glycol and 2.0wt% glycerin as moisturizers, 3.0wt% of cyclomethicone, 3.0wt% of isononyl-isononanoate, 3.0wt% of capric/caprylic triglycerides, 3.0wt% of macadamia oil as emollients. Second, As the optimum conditions to form Lipid-LCG, which figured out 6.0 ${\pm}$ 1.0 for pH level, 32kg/mm, min for hardness to make a .essence to be formed the ternary phase of liquid crystal(multi-lamellar type). Third, as the analytical result of this system, it obtained that particle size is $1{\sim}8{\mu}m$ level, and is certified with it at 400 and 1,000 magnifications by microscope. The stability of Lipid-LCG is very stable on condition of a low temperature ($4^{\circ}C$), a room temperature ($25^{\circ}C$) and a high temperature ($40^{\circ}C$), which is not to be split in for a long time(for 3-month). We produced our own moisturizing essence, which has a good affinity to skin by means of this system.

• Journal of Korean Neurosurgical Society
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• v.38 no.4
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• pp.273-280
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• 2005

Objective : There is no acceptable indication and treatment of choice for infantile and child subdural hygroma and there are only a few reports about that in Korea. So the authors studied the clinical findings of infantile and child patients with subdural hygroma to improve the understanding and to suggest a standard treatment method. Methods : The authors retrospectively evaluated the causes, preoperative symptoms, radiological thicknesses, and postoperative results of 25patients with subdural hygroma who received surgical therapy. Results : There were 16boys and 9girls whose median age was 6months[range $2{\sim}120months$]. The main clinical manifestations were seizures, increased intracranial pressure, macrocrania and alteration of consciousness. Radiological thicknesses of the subdural hygroma varied from 7mm to 42mm and postoperative changes of thickness[y] could be expressed with the factor of month[x]: $y\;=\;-1.32\;{\times}\;+11.8$ in subdural drainage, and $y\;=\;-1.52\;{\times}\;+14.9$ in subduroperitoneal shunts. Of the 25patients, 2 [50%] were successfully treated by aspiration, 13 [59%] by subdural drainage, and 9 [69%] by subduroperitoneal shunt. Conclusion : It is suggested that the diagnosis and treatment of subdural hygroma in infants and children should be carefully addressed because of its high prevalence in children, and especially in infants. It is also suggested that the subdural drainage could be primary initial treatment method because it is simpler than a shunt, and since our data show that there is no statistical difference in postoperative recovery duration between the two operative methods.

• Journal of Korean Neurosurgical Society
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• v.49 no.3
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• pp.153-156
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• 2011

Objective : This prospective, non-randomized study compared the safety and efficacy of the Angio-$Seal^{TM}$ $Evolution^{TM}$ to that of manual compression for common femoral artery punctures in neurovascular diagnostic angiography. Methods : From June 2009 to September 2009, we performed 169 diagnostic trans-femoral cerebral angiographies, using either the Angio-$Seal^{TM}$ $Evolution^{TM}$ or manual compression to achieve hemostasis. We included 60 patients in this study, 30 in each group. We defined minor complications as those requiring no further treatment such as hematoma size less than 6 cm and bruise size less than 25 cm. Major complications were those requiring surgery of the femoral artery pseudoaneurysm and/or the second line increase of hospital stay even without further treatment. Results : Mean time to hemostasis was $0.42{\pm}0.04$ minutes for the angioseal and $15.83{\pm}1.63$ minutes for manual compression (p<0.001). Overall complication rate did not differ between the 2 groups. After the patients were fully mobile, at 24 hours, the rate of onset of new complication differed significantly between the 2 groups (p=0.032). In the angioseal group, 5 (16.7%) of the 30 patients experienced the onset of a new complication after 24 hours, including 3 (60.0%) of the 5 who experienced major complications. Conclusion : The Angio-$Seal^{TM}$ $Evolution^{TM}$ is effective at decreasing mean time to hemostasis, like other closing devices. However, it may not be effective at producing early ambulation and discharge, compared to manual compression, because delayed complications may occur significantly after 24 hours.

• Current Research on Agriculture and Life Sciences
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• v.25
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• pp.7-12
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• 2007

In order to investigate the availability of insect resources for agrobiotechnological or medical purposes, we examined antioxidant (DPPH and FRAP assay) and cell viability by oxidant stress and NO inhibition assay by treatment of the extracts of Statilia maculata Thunberg, Tenodera angustipennis Saussure and Tenodera aridifolia Stoll. We found that Tenodera angustipennis Saussure and Tenodera aridifolia Stoll extract (DW, etanol, methanol) had high levels of anti-oxidant activity, whereas Tenodera aridifolia Stoll extract showed increased cell viability by hydrogen peroxide and inhibition of NO production. These findings suggest that Statilia maculata Thunberg, Tenodera angustipennis Saussure and Tenodera aridifolia Stoll, extract have potentials to be developed for agrobiotechnology or medicinal use, indicating that mechanistic study including inhibition against molecular inflammation will show a possibility for the development of useful insect resources.

• Journal of the Korea Institute of Military Science and Technology
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• v.14 no.1
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• pp.132-138
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• 2011

A micromachined silicon accelerometer capable of surviving and detecting very high accelerations(up to 200,000 times the gravitational acceleration) is necessary for a high impact accelerometer for earth-penetration weapons applications. We adopted as a reference model a piezoresistive type silicon micromachined high-shock accelerometer with a bonded hinge structure and performed structural analyses such as stress, modal, and transient dynamic responses and sensor sensitivity simulation for the selected device using piezoresistive-structural coupled-field analysis. In addition, structural optimization was introduced to improve the performances of the accelerometer against the initial design of the reference model. The design objective here was to maximize the sensor sensitivity subject to a set of design constraints on the impact endurance of the structure, dynamic characteristics, the fundamental frequency and the transverse sensitivities by changing the dimensions of the width, sensing beams, and hinges which have significant effects on the performances. Through the optimization, we could increase the sensor sensitivity by more than 70% from the initial value of $0.267{\mu}V/G$ satisfying all the imposed design constraints. The suggested simulation and optimization have been proved very successful to design high impact microaccelerometers and therefore can be easily applied to develop and improve other piezoresistive type sensors and actuators.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2007.06a
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• pp.461-465
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• 2007

MANET(Mobile Ad hoc Networks) is free-mobility formation of mobile nodes in the wireless networks. Generally, wireless networks has two main type of structures which Tree and Mesh. These general structure is difficult to do which connectivity, redundancy transmit and network continuant. In this paper, we would suggest a new ODDMRP(Ontology Doppler effect-based Dynamic Multicast Routing Protocol) technology for effective MANET which Ontology Doppler effect-based. ODDMRP consist of the parameters for node entropy when using Doppler effect which moving position of round node, moving time, and distribution chart in velocity also it express distance of destination node and property structure organization. It would be used to provide improvement to keep the optimal communication routing and also could be improve network stabilization, and continuation durability of connectivity.

• Journal of Korean Society for Atmospheric Environment
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• v.27 no.1
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• pp.63-72
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• 2011

This study describes the impact of positive sampling artifact caused by a filter-based sampling in the determination of ambient organic carbon (OC). Three different sampling media combinations were employed for this investigation: (1) Quartz filter-alone (Q-alone), (2) quartz filter behind quartz-fiber filter (QBQ), and (3) quartz filter and quartz filter behind Teflon filter (Q-QBT). The measurement of ambient OC was carried out at a semi-urban site near oceanside at the end of November of 2008. It was found that Q-alone sampling configuration resulted in a higher OC than QBQ and Q-QBT by 14% and 28%, respectively due to no correction for positive artifact caused by adsorption of gas-phase OC onto the filter. A lower quantity of OC was collected from the backup quartz filter on QBQ than that from Q-QBT. A possible explanation is that the front quartz filter of QBQ was not fully saturated with gas-phase OC during the sampling period, allowing smaller amount of gas-phase OC to reach the backup quartz filter. The contribution of positive artifact to $PM_{2.5}$ mass was approximately 2.15 ${\mu}g/m^3$ which is equivalent to 6% in terms of Q-QBT sampling configuration. The positive artifact was found to be more dominated during summer than during winter, showing temperature dependence. It was concluded that Q-QBT sampling configuration offers less impact of positive artifact on ambient OC sampling than QBQ in quantification of OC.