• Journal of Digital Contents Society
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• v.19 no.2
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• pp.371-376
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• 2018

In the system security technology, the information hiding field is developed as technologies for embedding information, which are generally used as contents media. The proposed technique is a technical steganography technique which uses a technique of concealing certain information through physical / statistical change of signal values of contents. Recently, there have been various studies based on histogram shifting in reversible data concealment. In multi - peak histogram shifting, the capacity of data concealment gradually increased by applying multiple peak histogram method. In this paper, we analyze the effect of concealment in terms of adopting the histogram shift method including skipping. In addition, we propose multi - branch data concealment as a general method to improve concealment capacity. The above proposal has proved to be an example using mathematical expressions, and further improvement measures could be derived.

• Journal of the Korean Society for Railway
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• v.16 no.4
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• pp.286-297
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• 2013

In this paper we evaluated dynamic stability, considering the effects of modeling and analysis methods on moving load analysis, for which a sophisticated 3 dimensional model of a PSC-I type girder bridge was used. For this purpose, we suggested a reasonable modeling method and the physical properties of the concrete and ballasted track system involved. We also analyzed the response characteristics according to: 1) the type of track system; 2) whether or not the track was modeled; 3) whether or not the distance between the girder center and the bearing were considered; 4) the analysis method (i.e., direct integral and modal analysis); 5) whether or not the frequency was filtered.

• Journal of the Korean Solar Energy Society
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• v.22 no.3
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• pp.1-10
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• 2002

Relatively being economical in installation and easy in operation, hot-air heating system has been generally used in greenhouse for heating system regardless of high cost in maintenance and uneven distribution of air temperature. Therefore to overcome the disadvantages in maintenance and in distribution of air temperature and to improve efficiency of heating system, this experimental study is performed. This experimental study aims to improve the character of uneven temperature distribution in vertical direction and to reduce energy consumption for heating in a greenhouse. The experiment had been performed to investigate change of thermal environment and effects on reducing energy consumption for heating in greenhouse by additional surface insulation and reduction of indoor-air volume that come by installing transparent vinyl membranes with different height in each house. The results show that there is a wide difference in oil-energy consumption between houses according to condition of surface insulation and change of indoor-air volume. Furthermore, the results show that the efficiency of dual surface is higher than that of change of indoor-air volume in terms of energy saving.

• Korean Journal of Construction Engineering and Management
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• v.5 no.5 s.21
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• pp.65-75
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• 2004

Labor management has been considered as an important task in construction industry. However, labor management has not yet been systematically performed because of the wide variety of factors of construction industry such as the field work, the complexity of the work process, the daily employment. Most of the present labor managements are performed to collect the information of the number of labors input during the work period, and to calculate labor cost. The information of activities performed by labors can be effectively used to analyze project status related to schedule, cost and productivity, but the present labor management systems are not based on the activities. The main objective of this research is to develop a labor information management system using IT tools in order to measure the number of labors input on the activities, and to convert the labor information into productivity data. It is anticipated that the effective use of the developed system would be able to effectively assist the scheduling and cost management of a project.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.30 no.2A
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• pp.1-11
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• 2005

S-CDMA is the advanced physical layer modulation techniques of DOCSIS 2.0 specification. S-DMT is another challenging modulation technique for cable modem upstream channel due to the intrinsic robustness for fading and impulse noise. The BER performance of S-DMT and S-CDMA over the mixed channel model of AWGN and impulse noise were evaluated in comparison with TDMA. The mathematical BER derivation and the comparison of those three types of technique were performed based on the ${\varepsilon}-mixture$ non-Gaussian impulse noise model. The results of simulation show good compliance with those of analytic BER derivation. By the results of comparisons, it was verified that the performance of S-CDMA and S-DMT is almost the same, but the performance of S-DMT is far superior to that of TDMA at typical BER range of the practical data communications.

• Journal of Korea Game Society
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• v.13 no.2
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• pp.71-80
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• 2013

The purpose of this paper is to analyze the results & performance of the optimized human resource development program, which was progressed by Gachon University in the past three years. Gachon University since 2009, with the support of the government, has launched a "Game Project Track" and also has carried out curriculum development and student education with cooperative companies in the field of game industry. Furthermore, Game Project Track, with companies, has pursued special lecture & intern training during vacation in order to strengthen students' ability to adapt on-site. As a results of co-education, 25 students have received the award in the external competitions, and also 39 students(97.5%) of 40 graduated from this course have been employed by cooperative companies.

• Journal of the Korean Institute of Gas
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• v.8 no.4 s.25
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• pp.55-61
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• 2004

This paper provided a counter measures against the troubles and accidents that are likely to take place in the power plant using hydrogen gas as a coolant for the cooling system of the generator. Because of the extremely wide flammability limits of hydrogen in comparison to the other flammable gases, the safety measures against the hydrogen accidents is very important to ensure the normal operation of electric-power facility. This study's purpose was a presentation of standard model of safety management of hydrogen equipments in the coal firing power plant such as following items: 1) providing the technical prevention manual of the hydrogen explosions and hydrogen fires occurring in the cooling system of power generator; 2) the selection of explosion-proof equipments in terms of the risk level of operating environment; 3) the establishment of regulations and counter measures, such as the incorporation of gas leakage alarm device, for preventing the accidents from arising, 4) the establishment of safety management system to ensure the normal operation of the power plant.

• The Transactions of the Korean Institute of Power Electronics
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• v.14 no.1
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• pp.72-81
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• 2009

This paper presents quasi-resonant type high power factor ac power supply for atmospheric pressure plasma cleaning system adopting three phase PFC boost converter and it's control method. The presented ac power supply consists of single phase H-bridge inverter, step-up transformer for generating high voltage and three phase PFC boost converter for high power factor on source utility. Unlikely to the traditional LC resonant converter, the propose one has an inductor inside only. A single resonant takes place through the inside inductor and the capacitor from the plasma load modeled into two series capacitor and one resistance. The quasi-resonant can be achieved by cutting the switching signal when the load current decrease to zero. To obtain power control ability, the propose converter controlled by two control schemes. One is the changing output pulse period scheme in the manner of PFM(Pulse Frequency Modulation) control. On the other, to provide more higher power to load, the DC rail voltage is directly controlled by the 3-phase PFC boost converter. The significant merits of the proposed converter are the uniform power providing capability for high quality plasma generation and low reactive power in AC and DC side. The proposed work is verified through digital simulation and experimental implementation.

• Journal of Korea Port Economic Association
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• v.25 no.2
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• pp.201-230
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• 2009

There are few studies on the human resource development and management of container terminal in Korea. In this situation, we try to analyze the training and education of Busan port container terminals. This study took a close look at present condition of training and education of container terminals in Busan and compared it with foreign advanced port. And conducted a questionnaire survey on the actural condition and system of it. Based on the survey result, we examine the problems and suggest an alternative plan to improve the training and edcation of Busna Port container terminals.

• The Journal of the Acoustical Society of Korea
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• v.38 no.1
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• pp.51-55
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• 2019

This paper proposes a speech enhancement method utilizing the feature compensation gain for robust speech recognition performances in noisy environments. In this paper we propose a speech enhancement method utilizing the feature compensation gain which is obtained from the PCGMM (Parallel Combined Gaussian Mixture Model)-based feature compensation method employing variational model composition. The experimental results show that the proposed method significantly outperforms the conventional front-end algorithms and our previous research over various background noise types and SNR (Signal to Noise Ratio) conditions in mismatched ASR (Automatic Speech Recognition) system condition. The computation complexity is significantly reduced by employing the noise model selection technique with maintaining the speech recognition performance at a similar level.