• The Transactions of the Korean Institute of Electrical Engineers P
• /
• v.58 no.4
• /
• pp.632-632
• /
• 2009

The purpose of this study is to present the range of defects mentioned in the Product Liability (PL) and to establish an objective basis and grounds for the analysis of accidents expected to happen by analyzing and presenting the external flame pattern and electrical characteristics of an LED streetlight lamp, a new lighting lamp. From the analysis of the cross-section of a cable carbonized by an external flame, it was observed that the wire's strand and insulation material had solidly adhered, and that greater voids were formed at the surface than at the center. Irregular carbide lumps were formed in the globe directly exposed to the flame, and the globe carbonized by the indirect flame showed characteristics that they had melted and flowed downward. It was found that the forward and backward resistances of the normal LED were approximately 1.74 [$M{\Omega}$] and 140 [$M{\Omega}$], respectively. The lamp burnt by the strong flame exhibited infinite forward and backward resistances and the LED did not emit light. The carbonized LED lamp was gray and exhibited fine delaminations. According to the Product Liability, a product defect signifies a simple product defect. Most of the defects were caused by the lack of stability, and the defect of the product itself occurred during the design and manufacture. The defects in warnings and markings include an insufficiency of handling manuals and warnings, expressive warranty violations, defective markings, etc. In order to prevent an accident resulting from a product, it is necessary to prepare safety warnings and documentation, establish clear-cut lines of liabilities, and subscribe insurances. However, it could be seen that important factors against the Product Liability were product improvement, response to compensation requests and law suits, credit restoration, etc.

• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.29 no.11B
• /
• pp.967-973
• /
• 2004

DOCSIS and IEEE 802.16 define the usage and element of a MAP which is uplink control message. Standards does not include the details of MAP size and the number of contention slots affecting the performance of MAC protocols for DOCSIS and IEEE 802.16. In this paper, we analyzed the performance of throughput and access delay according to the MAP size and contention slot size. Based on the analytical results, we found the optimal MAP size and the number of contention slots. We found that the protocol shows best performance when the MAP size is 2msec and the number of contention slots is 8. The simulation results can apply to the network system parameters. The simulator can be used to optimize the system parameters in cable network, BWA and WiBro.

• Journal of KIISE:Information Networking
• /
• v.37 no.3
• /
• pp.187-197
• /
• 2010

The fusion stream of recent broadcasting and communication make multimedia content served in the area of broadcasting into IPTV service which transmits it through high-speed internet, cable TV net and satellite net in realtime. However, as the digital broadcasting service is extended to various media, the security of IPTV service content provided to users by service provider is not fully supported by CAS(Conditional Access System) provided by existing broadcasting system. This paper proposes interactive certification protocol which can efficiently distinguish the receiving-qualification of user between Set-Top Box and Smart Card which are parts of configurations for IPTV system. The proposed protocol uses hash function to make Set-Top Box transmit receiving-qualification about the channel fee which user pays more properly than existing protocol. Also, the proposed protocol uses session key generated between receiver and smart card through inter certification process and encrypts EMM not the service to be used by anyone illegally.

• Journal of the Computational Structural Engineering Institute of Korea
• /
• v.30 no.1
• /
• pp.7-15
• /
• 2017

This paper presents the results of the parametric study to investigate the effects of several analysis modeling parameters such as support conditions, member connectivities and cable member stiffness on the main mode shapes and natural frequencies of a representative disaster resilient greenhouse structure. In addition, an ambient vibration test was performed on the representative greenhouse structure and its main mode shapes and natural frequencies were obtained. By comparing the experimental and analysis results, a proper analysis modeling method of the representative greenhouse structure was proposed.

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.17 no.2
• /
• pp.666-671
• /
• 2016

This paper introduces a device providing close local lighting to the affected part, where the operation-purpose astral lamp alone cannot shed light directly, in an operation room of hospitals or clinics, which helps clinical doctors perform safe treatment of the affected part deep inside a human body. This medical assisting lighting is a device necessary to prevent fatal operation failures, which can occur with minute operation processes, such as tumor removal or angiorrhaphy. The components, such as the light source and power supply were designed to be low power consuming and small in size, have a narrow angle lens was used to increase the light spreading effect and focused illumination. The end-caps of the light transmission device using an optical cable and the lighting device were designed in the waterproof type to enable disinfection of these devices after use for the next patients. According to the measurement of the light source properties made after development of the retractor lighting device, the illumination intensity was 490 lux, the brightness was $11,550cd/m^2$, general color rendering index was 78, color temperature was 11,000K, and the intensity distribution was even, which were confirmed to be adequate for medical assisting local lighting.

• Journal of the Korea institute for structural maintenance and inspection
• /
• v.16 no.5
• /
• pp.29-39
• /
• 2012

The main objective is to predict the future degradation and maintenance budget for a suspension bridge system. Bayesian inference is applied to find the posterior probability density function of the source parameters (damage indices and serviceability), given ten years of maintenance data. The posterior distribution of the parameters is sampled using a Markov chain Monte Carlo method. The simulated risk prediction for decreased serviceability conditions are posterior distributions based on prior distribution and likelihood of data updated from annual maintenance tasks. Compared with conventional linear prediction model, the proposed quadratic model provides highly improved convergence and closeness to measured data in terms of serviceability, risky factors, and maintenance budget for bridge components, which allows forecasting a future performance and financial management of complex infrastructures based on the proposed quadratic stochastic regression model.

• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.36 no.12B
• /
• pp.1522-1536
• /
• 2011

Due to the advance of broadband communication networks including the Internet, the release of diverse media, and the busy life cycle of modern people, it became difficult to watch TV programs strictly according to the program schedule. Instead, demand to download and watch the programs at any time on TV is increasing. In order to meet the demand, terrestrial DTV broadcasters developed a TV service which provides various on-demand contents by integrating terrestrial DTV network and the Internet without enforcing viewers to subscribe broadcasting services such as IPTV or CableTV, and standardized it as OHTV(Open Hybrid TV). In this paper, we explain the current status of OHTV standard and worldwide hybrid TV services and their technical standards. We also provide a strategy for the next version of OHTV standard in order to enhance the value of OHTV.

• Solar Energy
• /
• v.15 no.3
• /
• pp.59-73
• /
• 1995

The thermal analysis is accomplished with the route for the underground power transmission system which adopts the water pipe cooling with trough in tunnel. As a result, in case of a cooling system based on a refrigerator, the optimum condition for the flow rate of cooling water and the air velocity are calculated as the $2{\sim}3{\ell}/s/pipe$ and $1{\sim}2m/s/fan$, respectively. On the other hand, in case of cooling tower the optimum condition for them are calculated as the $2{\sim}3{\ell}/s/pipe$ and 6 m/s/fan, respectively. But the cooling system based on a cooling tower has the problem of enlarging the size of cooling fan and suppressing the labor of operator in tunnel. Therefore, to meet all the cooling conditions for a given cooling section, the cooling system based on a refrigerator is more acceptable.

• Journal of Korea Technology Innovation Society
• /
• v.15 no.2
• /
• pp.461-479
• /
• 2012

In this study, new evaluation perspective and analysis methodology are suggested to assess the technological level of new product produced by national large R&D program and applied to case analysis of the superconducting cable technology. Logical Procedures for the assessment of the technological level include essential technology classification, analysis of evaluation factors, structure and content of assessment items, presentation method of the analysis result. Variable with technological properties are employed to analyze the relative competitiveness subjectively. The principal component analysis are applied to measure the relative competitiveness in terms of size and position. Finally the combined results of technology and right evaluation show that the technology level of DAPAS superconducting cables lies somewhere between 96.11% and 101.76% compared with a global leader in technology. The result provides sufficient evidences that it secures technological edges over other competitors. Therefore it can be called as a globally leading technology. New evaluation perspective and analysis methodology suggested can be applied usefully to assess the technology level of public large-scale R&D program.

• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.22 no.12
• /
• pp.2806-2818
• /
• 1997

It is generallyaccepted that broadband access technologies will play an important role in the National Information Infrastructure. However, the provision of direct fibers to residential and small business customers has always been considered a challenge. To accelerage the provision of Broadband Access Facilities, alternatibe paths could be identified and actaivated in parallel. In this paepr, we present an overview of the alternative access technologies focusing on xDSL, FTTx, HFC, HFR, and suggest the modeling of the access netetwork systems which is using of the technologies. Also to investigate the economics of each access systems, we derve the numerical equations which is summed up the al parameter including the labor cost of the model system. The proposed equation has a variable which is the cell size (or subsciber clusters) and calculate the real cost values which is normalized by the copper cable unit cost. From the numerical resutls, we conclude that the economic access method to provide these broadband capabilities is depended on the subscriber penetration, the patterns of subscriber distribution density and existing communication infrastructures. It can be expected that our analytical model and equations provides an elegant solution to choose the optimal broadband access technologies to residential and small business customers.