• Journal of Korea Multimedia Society
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• v.9 no.3
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• pp.333-341
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• 2006

Recently, Random Constant worm is increasing The worm retards the availability of the overall network by exhausting resources such as CPU resource and network bandwidth, and damages to an uninfected system as well as an infected system. This paper analyzes the Power-Law network which possesses the preferential characteristics to restrain the worm from spreading. Moreover, this paper suggests the model which dynamically controls the spread of the worm using information about depth distribution of the delivery node which can be seen commonly in such network. It has also verified that the load for each node was minimized at the optimal depth to effectively restrain the spread of the worm by a simulation.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.4 no.4
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• pp.509-528
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• 2010

The random access systems, with retransmission diversity (RD) employment, over large random spreading code division multiple access (CDMA) channel subject to fading is investigated, under the assumption of infinite number of users and infinite spreading gain with their ratio converging to a constant. The low bound of the signal to interference and noise ratio (SINR) is shown to converge almost surely to a constant. The throughput, spectrum efficiency and energy efficiency in the dominating systems are obtained. The analytical results are confirmed by simulations. We find that in high traffic loads the throughput with fading is higher than that without. When the energy efficiency increases, the spectrum efficiency tends to two contrary values due to SNR increases or decreases. For the ordinary stable systems, the stability region is shown to shrink as the traffic increases and enlarge with RD employment.

• Journal of Information Processing Systems
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• v.5 no.1
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• pp.33-40
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• 2009

Ever since the network-based malicious code commonly known as a 'worm' surfaced in the early part of the 1980's, its prevalence has grown more and more. The RCS (Random Constant Spreading) worm has become a dominant, malicious virus in recent computer networking circles. The worm retards the availability of an overall network by exhausting resources such as CPU capacity, network peripherals and transfer bandwidth, causing damage to an uninfected system as well as an infected system. The generation and spreading cycle of these worms progress rapidly. The existing studies to counter malicious code have studied the Microscopic Model for detecting worm generation based on some specific pattern or sign of attack, thus preventing its spread by countering the worm directly on detection. However, due to zero-day threat actualization, rapid spreading of the RCS worm and reduction of survival time, securing a security model to ensure the survivability of the network became an urgent problem that the existing solution-oriented security measures did not address. This paper analyzes the recently studied efficient dynamic network. Essentially, this paper suggests a model that dynamically controls the RCS worm using the characteristics of Power-Law and depth distribution of the delivery node, which is commonly seen in preferential growth networks. Moreover, we suggest a model that dynamically controls the spread of the worm using information about the depth distribution of delivery. We also verified via simulation that the load for each node was minimized at an optimal depth to effectively restrain the spread of the worm.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.17 no.3
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• pp.43-53
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• 2007

Internet becomes more and more popular, and most companies and institutes use web services for e-business and many other purposes. With the explosion of Internet, the occurrence of cyber terrorism has grown very rapidly. Simulation is one of the most widely used method to study internet worms. But, it is quite challenging to simulate very large-scale worm attacks because of various reasons. In this paper, we propose a hybrid modeling method for RCS(Random Constant Spreading) worm simulation. The proposed hybrid model simulates worm attacks by synchronizing modeling network and packet network. So, this model will be both detailed enough to generate realistic packet traffic, and efficient enough to model a worm spreading through the Internet. Moreover, our model have the capability of dynamic updates of the modeling parameters. Finally, we simulate the hybrid model with the CodeRed worm to show validity of our proposed model for RCS worm simulation.

• Journal of Electrical Engineering and Technology
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• v.10 no.5
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• pp.2018-2030
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• 2015

A two stage ac drive configuration consisting of a single-phase line commutated rectifier and a three-phase voltage source inverter (VSI) is very common in low and medium power applications. The deterministic pulse width modulation (PWM) methods like sinusoidal PWM (SPWM) could not be considered as an ideal choice for modern drives since they result mechanical vibration and acoustic noise, and limit the application scope. This is due to the incapability of the deterministic PWM strategies in sprawling the harmonic power. The random PWM (RPWM) approaches could solve this issue by creating continuous harmonic profile instead of discrete clusters of dominant harmonics. Insufficient filtering at dc link results in the amplitude distortion of the input dc voltage to the VSI and has the most significant impact on the spectral errors (difference between theoretical and practical spectra). It is obvious that the sprawling effect of RPWM undoubtedly influenced by input fluctuation and the discrete harmonic clusters may reappear. The influence of dc link fluctuation on harmonics and their spreading effect in the VSI remains invalidated. A case study is done with four different filter capacitor values in this paper and results are compared with the constant dc input operation. This paper also proposes an ingenious RPWM, a ripple dosed sinusoidal reference-random carrier PWM (RDSRRCPWM), which has the innate capacity of suppressing the effect of input fluctuation in the output than the other modern PWM methods. MATLAB based simulation study reveals the fundamental component, total harmonic distortion (THD) and harmonic spread factor (HSF) for various modulation indices. The non-ideal dc link is managed well with the developed RDSRRCPWM applied to the VSI and tested in a proto type VSI using the field programmable gate array (FPGA).

• The Korean Journal of Community Living Science
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• v.21 no.1
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• pp.117-124
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• 2010

Recently, research on variables associated with hair styles are increasing with the spreading of total coordinated intention in the fields of clothing and cosmetology. In the present study, we focused on examining the skin temperature on the scalp(the vertex, temporal, and occiput), humidity on the occiput, skin temperatures (the forehead, back of ear, back of neck, upper back, abdomen, forearm, hand, thigh, calf, and foot), rectal temperature, total body mass loss by hair styles in a thermal neutral environment. Four young females participated as subjects. For a certain period, each subject had the five different hair styles in a random order: (1)Straight short hair(SS), (2)Perm waved short hair(PS), (3) Straight long hair(SL), (4)Perm waved long hair(PL), (5)Ponytail style(PT). Subjects wore briefs, bra, shirts with long sleeves, long legged training pants, and socks. The environmental variables of a climatic chamber were kept constant at $21{\pm}0.5^{\circ}C$ of air temperature and 55${\pm}$5%RH of air humidity. The results indicated the following: The skin temperature and humidity on the scalp did not show any significant differences among five different hair styles, but straight long hair style(SL)was the highest on the vertex, temporal, and occiput. The temporal skin temperature($29.8\sim30.8^{\circ}C$) was the highest, while the vertex skin temperature($28.7\sim30.1^{\circ}C$) was the lowest. Humidity on the occiput was the highest in the perm waved long hair style(PL). The back of ear skin temperature was significantly lower in the ponytail style(PT) than in the other four hair styles(p<.001). In the straight long hair style(SL), the skin temperature on the back of the neck and on the upper back were significantly higher than those of the other four hair styles(p<.01). Mean skin temperature and rectal temperature had no significant differences among hair styles. Total body mass was the highest in the perm waved long hair style(PL)(p<.05). We acquired fundamental data to enable the improvement of the current hair clinic system, wigs, functional hats, and helmets.