• Journal of the Korea Society of Computer and Information
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• v.15 no.4
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• pp.19-25
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• 2010

In this paper, the performance of the DoS information security algorithm is evaluated to provide the multimedia traffic between the nodes using the multicasting services. The essence technology for information security to distribute the multimedia contents is presented. Under the multicasting services, a node participating new group needs a new address and the node compares the collision with the existing nodes, then DoS attack can be occurred between the nodes by a malicious node. Using the NS2 simulator, the number of DoS attacks, the average number of trials to generate new address, and the average time to create address are analyzed. From simulation results, the efficient algorithm with relevant random number design according to the DRM network is needed to provide secure multimedia contents distribution.

• Fire Science and Engineering
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• v.30 no.5
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• pp.87-92
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• 2016

Amid the growing number of high-rise complex buildings in Korea, efficient smoke prevention technology in a fire is required and as an alternative of a mechanical smoke control system in high-rise buildings, the use of a smoke control system using sandwich pressurization has been on the rise. In such a system, the appropriate pressure difference and the data for designing the air supply and exhaust flow rate are necessary to prevent the spread of smoke and offer a tenable evacuation environment. As part of such effort, this paper presents a field test process and result after testing a building where such a smoke control system using sandwich pressurization has been installed. A ventilation rate of 6 cycles per hour were applied to simulate the air exhaust flow rate on a fire floor and the air supply flow rate on the floors above and below the fire floor. As a result of the system operation, pressure difference of approximately 260 Pa between the 12th floor of a fire and the 13th floor was generated. The over pressure of the experiment has a serious effect on the evacuation or fire compartment so that it is necessary to examine the improvement.

• Resources Recycling
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• v.18 no.3
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• pp.62-68
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• 2009

Continuous operation for 24h was carried out to establish the optimum condition at the magnesium fused salt electrolysis using a self made 150 ampere mono-polar type cell. An electrolyte composition of $MgCl_2$ 25%, NaCl 55%, $CaCl_2$ 19%, $CaF_2$ 1% was electrolyzed with applied voltage 7V, cathode current density $0.7-0.75A/cm^2$, electrode distance 6cm at $720{\sim}740^{\circ}C$ for 24 hours. Changes of applied current, composition of the electrolyte, current efficiency were investigated. Through the experiments, there were not any operating troubles with the self-made electrolytic cell. Purity of the electrolyzed magnesium metal was above 99%, and 89% of current efficiency was achieved. Some basic data for scale-up of the magnesium electrolysis equipment which would be necessary for commercialization were obtained.

• Plant Journal
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• v.13 no.2
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• pp.39-45
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• 2017

This paper is a study on FEED validation model that can be used in the bidding stage of small utility equipment in offshore plant industry using system engineering technique. Currently, domestic marine plant equipment industry companies are faced with the financial risk of project execution as they enter marine plant. The major cause was the insufficient ability to verify the FEED output from the contractor (Engineering or Procurement and Construction) of the equipment manufacturer (COMPANY or EPC). Therefore, we propose FEED design verification method that simplifies the system engineering method that sequentially applies requirements analysis, function, performance analysis and physical architecture building process. Also, we verified the suitability of the developed model by comparing the results of applying the developed FEED verification model and the verification method that depends on the existing experience for the small utility equipment (Air Compressor).

• Korean Journal of Construction Engineering and Management
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• v.1 no.1 s.1
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• pp.80-86
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• 2000

The future costs of energy and the cost of the repair of apartment buildings are expected to rise continuously in proportion to the initial costs. Therefore it has become important for these increasing costs to be incorporated and reflected in the design of the building. Systems such as structure and services for the buildings remain constant, but a number of the walls and windows can vary and thus have a major influence on the total construction and running costs of a building. The critical factor in the apartment unit design for the optimization of life cycle cost (LCC) is the ratio of the x and y axis of the walls in the unit plan. This paper demonstrates how to achieve the optimal size and thus optimize the LCC of the building.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.23 no.12
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• pp.1373-1379
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• 2012

The interaction of magnetic field in the frequency range of 9~150 kHz radiating from a railway system with wireless systems has been the cause of radio frequency interference. In this paper, the equivalent circuit model of the RFI noise is proposed through source and transfer path analysis, and it is confirmed that the switching noise of several kHz that occurs a vehicle traction drive system and a substation is radiated by forming the loop circuit with a feeder line by a rolling stock. And the validity of the proposed equivalent circuit model is verified by analyzing the effects of RC banks installed in the real railway between Guri and Guksu stations, the RFI noise can be effectively mitigated by loading suitable capacitance between rail and feeding line.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.18 no.3
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• pp.519-525
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• 2014

In this paper, we show a scheme to directly access DLNA network with the 3G/4G communication module of a smartphone in home or office environment. By exploiting this scheme, end users can use DLNA service more conveniently regardless of the type of activated communication module in a smartphone. For the implementation of this scheme, we use a femtocell that is a basestation with small coverage. A problem caused by the IP address hierarch discrepancy between the IP address of 3G/4G module of smartphone and those of local network nodes is resolved by deploying local IP address scheme. The processing of multicasting packet, that is required in DLNA service, is enabled by using IP tunneling scheme. As a result, end user can access DLNA network regardless of the type of activated wireless communication module. We validate the design result by implementing it on a commercial WCDMA femtocell.

• 한국방재학회:학술대회논문집
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• 2008.02a
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• pp.759-762
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• 2008

A wastewater treatment plant located in coastal areas should be built considering the discharge of rainwater and treated water into the sea. The current Hagik Wastewater Treatment Plant in Incheon City was designed in the surface discharge method, which refers to discharging treated water directly into the sea. This method may cause hydrodynamic issues in a wastewater treatment plant because seawater enters an outfall riser when the level of discharged water is lower than the tidal level on a shore with high tidal range. In this study, a method for installing a weir in the discharge manhole was proposed in order to prevent seawater from entering the outfall riser of a wastewater treatment plant. Its feasibility was reviewed by calculating the hydrodynamic that had occurred due to the installation of the weir. As a result, seawater did not enter in the discharge manhole. Thus, even if the coast of Incheon City reaches the highest tidal level, treated water will be able to be properly discharged.

• Journal of Korean Society of Steel Construction
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• v.15 no.6 s.67
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• pp.629-637
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• 2003

This s paper presented the results of the three phases of fatigue tests to determine the fatigue strength of in-plane welded gusset joints, which are the most common details inevitably existing in the region of high stress range. A total of 57 fatigue specimens with varying thickness and strengths were made and tensile fatigue tests performed. One full-scale beam fatigue test was also performed. The validity of the fatigue strength of those details in the specification was confirmed, with the effects of thickness of flanges and welded attachments, length of attachments, and strength of applied steel examined. The characteristics of crack initiation and propagation were also observed. The test result was evaluated by comparing it with other test data and fatigue criteria of other countries. To determine the degree of stress concentration in the weld toe depending on geometric configuration such as attachment length and transition radius, analyses were performed. Compared to the present specification, analytical results indicate the need to revise and subdivide the detail categories.

• Journal of the Korea institute for structural maintenance and inspection
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• v.14 no.1
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• pp.148-155
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• 2010

The purpose of this study is to propose and evaluate the continuous joint constructed with MRS system which is utilized for floor system in the parking structures or commercial retail buildings. Four specimens were fabricated and tested to examine the structural performance of the continuous joint with different joint detailing. Structural test for the specimens was undertaken to simulate the actual stress condition of the negative moment resisting connection in the prestressed precast concrete parking structures with 8m span. Based on the experimental results, the MRS system could be designed as the ductile continuous joint governed by flexural behavior. Therefore the MRS system developed in this study would provide a superior joint behavior to conventional double-tee system when constructing monolithic joint composed of simply supported precast members.