• Journal of the Korean Society of Safety
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• v.30 no.5
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• pp.123-130
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• 2015

Wolsong Unit 2,3&4 has been performing a containment integrity test during power operation. This test could impact to the safe operation during test. If an accident occurs during pressure dropping phase, reactor trip can be delayed because of the increased pressure difference which causes a time delay to reach the trip set-point. On the contrary, if an accident occurs during pressure increasing phase, reactor trip could be accelerated because the pressure difference to the trip set-point decrease. Point Lepreau nuclear power plant, which installed GCLMS (Gross Containment Leakage Monitoring System) in 1990, has discontinued the test since 1992 due to these adverse effects. Therefore, we evaluated the risk to obviate the GCLMS test based on PWR's ILRT (Integrated Leak Rate Test) extension methodologies. The results demonstrate that risk increase rate is not high in case of performing only ILRT test at every 5 years instead of doing GCLMS test at every 1.5 years. In addition, the result shows that GCLMS test can be removed on a risk-informed perspective since risk increasement is in acceptable area of regulatory acceptance criteria.

• The KIPS Transactions:PartC
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• v.13C no.2 s.105
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• pp.171-176
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• 2006

Bandwidth is an extremely valuable and scarce resource in a wireless network. Therefore, efficient bandwidth management is necessary in order to provide high qualify service to users with different requirements in a multimedia wireless/mobile network. In this paper, we propose an on-line bandwidth reservation algorithm that adjusts bandwidth reservations adaptively based on existing network conditions. The most important contribution of our work is an adaptive algorithm that is able to resolve conflicting performance criteria - bandwidth utilization, call dropping and call blocking probabilities. Our algorithm is quite flexible, is responsive to current traffic conditions in cellular networks, and tries to strike the appropriate performance balance between contradictory requirements for QoS sensitive multimedia services.

• Journal of Forest and Environmental Science
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• v.34 no.2
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• pp.180-183
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• 2018

Fecal sites of the Siberian flying squirrel Pteromys volans were found in the 16 tree species, and 11 species (46.4%) of them were used as fecal sites in winter and only 3 tree species (5.6%) were used for their fecal dropping in summer. In winter and spring, 11 and 10 tree species were used as fecal sites, respectively, indicating that various species of trees are used in those seasons for food sources or resting sites of the flying squirrels. Of total 16 species, the flying squirrels' fecal sites were most frequently found in Quercus mongolica (46.4%) and then followed by Prunus sargentii (25.6%). In winter, Prunus sargentii was preferred more than Quercus mongolica, although trees of Prunus sargentii are less distributed compared with those of various trees of the genus Quercus. In summer and autumn, high productivity of trees makes the flying squirrels use only one or two species they prefer. In winter and spring, however, they should extend their food source to various tree species because of low productivity and less food sources.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.14 no.1
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• pp.63-69
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• 2015

Recently, research and interests in pilotless and radio-controlled quadcopters have increased due to military, hobby, and air-photo applications. However, quadcopters are fragile and can very easily to break when they crash. Therefore, it is necessary to create a protective device such that these devices can protect the main board, motor, and propellers from outside impacts. In this paper, a protective device for a quadcopter is designed in the form of a circle to disperse shock. Also, a dropping and impact simulation was performed to verify that the quadcopter can be efficiently protected when using the proposed device, created with the commercial finite element software Solidworks.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.14 no.1
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• pp.122-128
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• 2010

RFID is method used on wireless system. However, this mechanism is not used for authentication and security. Therefore, it is very vulnerable to attacks such as dropping attacks and traffic attacks. the RFID Tags are of the limited nature due to environment factors and there is greater constraints in designing authentication protocol. If we do not RFID to secure corporate information and product all the information will be exposed. The attacker will break into the RFID system and stop the distribution system. So, this paper proposes a new authentication protocol which provides not only unlimited access to Tag and Reader of mobile and connection between Tag and Reader bet also provides authentication mechanism by defining the key distribution.

• Proceedings of the Korean Geotechical Society Conference
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• 2004.03b
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• pp.659-666
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• 2004

Dynamic compaction has evolved as an acceptable method of site improvement by treating poor soils in situ. The method is often an economical alternative for utilizing shallow foundations and preparing subgrades for construction when compared with conventional solutions. In general, the installation purpose of dynamic compaction are to increase bearing capacity and decrease differential settlement within a specified depth of improvement. This method involves the s systematically dropping large weights onto the ground surface to compact the underlying ground. The weights used on dynamic compaction projects have been typically constructed of steel plates, sand or concrete filled steel shells, and reinforced concrete. Typically, weights range from 5-20 ton and base configurations are, circular or octagonal. In this study, the effective depth of improvement is evaluated based on the numerical analysis code, the dynamic analysis of FLAC-3D program, in order to analyze the influence parameters ; ground conditions, maximum applied load and the area of compaction plate.

• Proceedings of the Korean Geotechical Society Conference
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• 2004.03b
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• pp.722-729
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• 2004

The horizontal movement of sloping ground due to flow liquefaction has caused many pile foundations to fail, especially those in ports and harbor structures. In this study, a virtual case is assumed in which flow liquefaction is induced by earthquake loads in a fully saturated infinite sand slope with a single pile installation. Under the assumption that the movement of liquefied ground is viscous fluid flow, the influence of ground movement due to flow liquefaction on the pile behavior was analyzed. Since the liquefied soil is assumed as a viscous fluid, its viscosity must be evaluated, and the viscosity was estimated by the dropping ball method ,md the pulling bar method. Finally, the influence of the flow of liquefied soil on a single pile installed in an infinite slope was analyzed by a numerical method.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.34 no.4B
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• pp.338-348
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• 2009

The Wireless Sensor Network (WSN) has recently attracted considerable attention due to the low price and ease to deploy it. In particular, in a hostile or harsh regions where sensors cannot be deployed manually, WSNs can be established just by dropping sensors from the air. In this case, however, most likely sensors are not placed at optimal positions, although the location of sensors does have a drastic impact on the WSN performance. Moreover, randomized deployment algorithm can leave holes in terms of coverage in the sensing area. This paper proposes a sensor relocation scheme where mobile sensors move to patch up the holes by appropriate coverage. Simulation results show that the proposed algorithm outperforms prior existing schemes in terms of coverage and lifespan of WSNs.

• 전자공학회논문지 IE
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• v.46 no.3
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• pp.42-47
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• 2009

In CDMA system, the call admission control method using the variable effective bandwidth concept is employed in this paper. The bandwidth for a new call and a handoff call is allocated by considering the number of mobile station being served and dynamically assigned by taking account of the blocking rate of new calls and the dropping rate of handoff calls. There is reserved resource for handoff call. In the case radio resource is insufficient, a new call and a handoff call stand by in buffer for constant time. When radio resource come about, the waiting call is allocated the resource. I analyze the performance of system according to existence and nonexistence of buffer by a simulation study.

• Journal of the Korean Home Economics Association
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• v.18 no.4
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• pp.31-39
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• 1980

The basic pattern of skirt should be functional in addition to be fit the body. The author paid special attention to the expansion and contraction of the shell which were made the lower trunk and thigh caused by sitting motions. The replicas of the shell were taken by using a gypsum method on 1 female under 4 standardized motions; standing motion, (basic motion), sitting on the chair with flextion 90' at the hip and the knee joints sitting with dropping knees, and sitting with benting legs side wards. Those replicas obtained were developed to the patterns and changes in shape and area of those were measured. Typical displacement and transformation of the shell surface patterns were showed geographycally fig 5-1 to 5-4. mean values of expansion and constriction were obtained by measuring the shell surface on 60 female under the 4 motions. the mean values of it were showed numerically in Table 1-1 to 1-3. The following results were obtained; 1. Vertical constriction of front of the shell were observed near sulcus in guinalis, and vertical extension were near the knees. Horizontal extension were observed near the thighs and the knees. 2. Vertical constrictions of the back of the shell were observed near the knees. It seemed to be influnced the flexion angles of knee points. vertical extension were near gluteus and thighs. Horizontal constriction were small, and horizonlal extension were near gluteus. 3. The high rates of constriction and extension were found near sulcus in guinalis, glutes, and knees. 4. The rates of constriction and extension on the waist line were very low. 5. The highest values of constriction and extension were found in hip and knees.