• Food Science and Preservation
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• v.10 no.4
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• pp.447-453
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• 2003

Causal factors related to the skin disorder such as black stains during cold storage of 'Niitaka' pear fruit are of great importance to solve the postharvest disorder problems. The morphological and biochemical changes observe of pear skin affected by different harvest times and storage environments. Occurrence rate of black stain in 'Niitaka' pear fruit was the highest in newspaper bagging with 75% among various bagging materials at harvest time because of the high relative humidity within the double layer paper bags. During cold storage, the rate was 54～100% in 30 $\mu\textrm{m}$ polyethylene (PE) film packaging. As the harvest time was postponed, the rate increasedduring cold stoinge. The into was 1.5 to 2.4 times higher in pears harvested in late September than in those harvested in early and mid October. There was no significant difference in occurrence of black stain fruit between the 30 and 50 $\mu\textrm{m}$ PE film bags. The causal fungus of the black stain pear was assumed as Gloeodes pomigena (Schweintz, 1920). The treatment of 0.1～0.5 ppm ozone gas prevented the occurrence of the pear fruit black stain until 180 days after cold storage. The ozone treatment on the affected fruit was also effective in preventing the progress of the black stain.

• Convergence Security Journal
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• v.19 no.3
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• pp.13-19
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• 2019

MANET has many security vulnerabilities because it consists of only mobile nodes using wireless. In particular, it is a very important factor determining network performance that excludes the participation of malicious nodes through accurate reliability measurements and authentication of nodes participating in the network. In this paper, we proposed a technique applied with blockchain technology in order to prevent forgery of authentication information for nodes participating in the network. And, an area-based hierarchical structure was applied to increase the efficiency of authentication for nodes and apply the optimal technique of block generation and exchange protocol. In addition, four data payloads were added to the block header in order to add authentication information for nodes in block. To improve the reliability by applying the blockchain technique to the hop-by-hop data transfer method between mobile nodes, blockchain exchange protocol through transaction creation, block packaging and verification processes were implemented. We performed the comparative experiment with the existing methods to evaluate the performance of the proposed method and confirmed the excellent performance by the experiment results.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.31 no.11A
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• pp.1053-1058
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• 2006

In this paper, We proposed a efficient OSA(Optical Sub-Assembly) packaging method in use 1.31/1.49um bi-directional hybrid-integrated PLC chip for low-cost OSA in optical access network system applications as GE-PON in FTTH. Fabricated OSA with passive optical fiber alignment and nonhermetic plastic package method and measured optical coupling efficiency and electric-optical characteristics. Its performance is feasible to satisfy the GE-PON ONU specifications with the results as less than 0.5dB coupling losses within 40um alignment of z-axis and less than -24dBm sensitivity. It also has good temperature characteristics to sustain optical output power more than 1.5mW and 10dB extinction ratio, less than 0.3dB tracking error.

• Journal of electromagnetic engineering and science
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• v.14 no.3
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• pp.284-292
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• 2014

This paper presents a characteristic evaluation of commercial gallium nitride (GaN) transistors having two different gate-lengths of $0.4-{\mu}m$ and $0.25-{\mu}m$ in the design of a class-S power amplifier (PA). Class-S PA is operated by a random pulse-width input signal from band-pass delta-sigma modulation and has to deal with harmonics that consider quantization noise. Although a transistor having a short gate-length has an advantage of efficient operation at higher frequency for harmonics of the pulse signal, several problems can arise, such as the cost and export license of a $0.25-{\mu}m$ transistor. The possibility of using a $0.4-{\mu}m$ transistor on a class-S PA at 955 MHz is evaluated by comparing the frequency characteristics of GaN transistors having two different gate-lengths and extracting the intrinsic parameters as a shape of the simplified switch-based model. In addition, the effectiveness of the switch model is evaluated by currentmode class-D (CMCD) simulation. Finally, device characteristics are compared in terms of current-mode class-S PA. The analyses of the CMCD PA reveal that although the efficiency of $0.4-{\mu}m$ transistor decreases more as the operating frequency increases from 955 MHz to 3,500 MHz due to the efficiency limitation at the higher frequency region, it shows similar power and efficiency of 41.6 dBm and 49%, respectively, at 955 MHz when compared to the $0.25-{\mu}m$ transistor.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.10 no.6
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• pp.1003-1010
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• 2006

The usage increase of digital contents required solution for protection technology and interoperability of system. MPEG(Moving Picture Experts Group) proposed MPEG-21 Multimedia Frameworks. MPEG-21 IPMP is standard that provides the means to enable digital item and rights information to be persistently managed and protected across networks and devices. In this paper, MPEG-21 IPMP based system to protect digital contents designed by four structures of license server, production server, consumption server, tool server. License server create rights information document using the XML-based REL about multimedia contents of users. Production server makes a digital item by packaging multimedia resource and metadata, which is combined by REL information and IPMP information of multimedia resource. Consumption server takes care of the functions of players that use digital item, and tool server was implement to transmit for missing tool that might occur in all procedures.

• Journal of the Korean Society for Nondestructive Testing
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• v.20 no.6
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• pp.511-520
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• 2000

Ultrasonic pulse echo method comes to be difficult to apply to the multi-layered structure with very thin layer, because the echoes from the top and the bottom of the layer are superimposed. We can easily meet this problem when the silicon chip layer in the semiconductor is inspected by a SAM equipment using fairly low frequency lower than 20MHz by which severe attenuation in the epoxy mold compound of packaging material can be overcome. Conventionally, deconvolution technique has been used for the decomposition of superimposed UT signals, however it has disabilities when the waveform of the transmitted signal is distorted according to the propagation. In this paper, the wavelet transform based deconvolution(WTBD) technique is proposed as a new signal processing method that can decompose the superimposed echo signals with superior performances compared to the conventional deconvolution technique. WTBD method uses the wavelet transform in the pre-stage of deconvolution to extract out the common waveform from the transmitted and received signal with distortion. Performances of the proposed method we shown by through computer simulations using model signal with noise and we demonstrated by through experiments for the fabricated semiconductor sample with partial delamination at the top of silicon chip layer.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2009.10a
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• pp.827-830
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• 2009

Feature of current IPTV services is that the IPTV Provider buys the rights of contents from contents author and provides consumers monopolistically with those. In this environment, IPTV is indistinguishable from the way of existing broadcasting services. To shift away from this structure, it is necessary to guarantee the common user's participation and provide the Open IPTV services for customers to be allowed to have be defined for more opportunities to select the contents. However, there are some problems to conduct Open IPTV service due to a variety of rights protection solutions designed by previous digital broadcast providers. Therefore, a new framework is needed to overall Open IPTV environment. This paper provides the design can packaging contents authoring and consuming tool for IPTV application service based on Open IPTV.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.20 no.1
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• pp.170-178
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• 2019

Recently, as the interest in energy savings has increased, there has been increasing use of LED lighting, which is an eco-friendly device that replaces high energy consuming fluorescent lamps and incandescent lamps. In the case of a high output LED, however, the life time is shortened due to deterioration caused by heat generation. As a solution to this problem, this paper evaluated the LED life extension effect by increasing the convective heat transfer coefficient of the heat sink surface for LED packaging. A roughing process was carried out using sandpaper and sand blasting. The changes in surface roughness and surface area after each surface treatment process were evaluated quantitatively and the convective heat transfer coefficient was measured. When sandblasting and sandpaper were used to roughen the aluminum surface, a higher convection heat transfer coefficient was obtained compared to the untreated case, and a high heat dissipation efficiency of 82.76% was obtained in the sandblast treatment. Therefore, it is expected that the application of heat dissipation to the heat sink will extend the lifetime of the LED significantly and economically by increasing the heat efficiency.

• Journal of the Korean Society of Systems Engineering
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• v.17 no.1
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• pp.76-84
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• 2021

Radioactive waste generated from nuclear power plant decommissioning shall be strictly managed so that radioactive materials above the allowable limit are not leaked into the environment. Radioactive wastes shall be classified and treated for management based on characteristics such as the type of waste, physicochemical properties, nuclide concentration and radioactivity. Waste characterization report shall be prepared and submitted to the disposal facility operator to ensure that the treated waste is suitable for disposal. The disposal facility operator shall review the waste Characterization report and visit the nuclear power plant decommissioning site to ensure that the wastes are processed step by step according to the plan. The waste Characterization report may be used as input data to evaluate disposal facility safety. Domestic and foreign data are collected and reviewed to confirm the entire processes from waste generation to delivery. This paper proposes the method to prepare the waste Characterization report which contains data and information on waste characteristics, treatment facilities & method and packaging method & container.

• The Journal of Korean Institute of Information Technology
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• v.17 no.6
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• pp.9-16
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• 2019

Companies that want to improve their manufacturing processes have recently introduced the smart factory, which is particularly noticeable. The ultimate goal is to maximize the area of the smart factory that performs the process of the production facility completely with minimal manual control and to minimize errors of reasoning. This research is a part of a project for unmanned production, management, packaging, and delivery management and the detection of the start point of rebars to perform the automatic calibration of the rollers through the tracking of the automated facilities of unmanned production. It must meet the requirement to accurately track the position from the start point to the end point. In order to improve the tracking performance, it is important to set the accurate start point. However, the probability of tracking errors is high depending on environments such as illumination and dust through the conventional time-based detection method. In this paper, we propose a starting point detection method using the average brightness change of high speed IR camera to reduce the errors according to the environments, As a result, its performance is improved by more than 15%.