• The Journal of Korean Institute of Communications and Information Sciences
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• v.34 no.4B
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• pp.349-359
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• 2009

In this paper, we propose a stereo-video transmission method for reduction of delay and maximization of 3D effect. Conventional multimedia synchronization algorithms were designed to achieve minimum delay and synchronize multiple video and audio streams, however, they could not be effective for 3D video transmission. In this paper, we proposed a synchronization algorithm by considering the minimum error of time difference between streams for 3D effect. The minimum error of time difference for 3D effect was derived based on a 3D subjective quality test. We compute display time of the delivered videos within the allowed time-difference and the video are displayed according to the display time. To evaluate the performance of the proposed algorithm, we implemented a real-time video communication system and subjective quality test has been conducted with the proposed system. We found that video quality displayed by the proposed system. We found that video quality displayed by the proposed algorithm ranks 'good' and 'excellent' in the DMOS (Differential Mean Opinion Score) scale, based on the MOS (Mean Opinion Score) test.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.24 no.12A
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• pp.1852-1861
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• 1999

In this paper, CDMA Reservation ALOHA scheme which can reduce multiple access interference and packet collision is proposed to support multi-traffic such as voice and random data with and without priority. In this scheme, the time slot is divided into two stage, access and transmission stage. Only packets with spreading codes assigned from base station in access stage can transmit their packets in transmission stage, so MAI can be reduced. To reduce packer collision in access stage, the code reservation and access permission probability are used. Code reservation is allowed for voice traffic and continuous traffic with priority using piggyback and access permission probability based on the estimation of the number of contending users in the steady-state is adaptively applied to each traffic terminal. Also, we analyzed and simulated the numerical performances required for each traffic using Markov chain modeling in a single cell environment.

• Journal of Energy Engineering
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• v.28 no.4
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• pp.29-34
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• 2019

In this study, a quantitative risk assessment was carried out for a hydrogen complex station. The complex fueling station to be evaluated was hydrogen-LPG, and the components of each station were analyzed and the risk was evaluated. The final risk is assessed by individual and societal risks, taking into account the impact of damage and the frequency of accidents. As a result of individual risk calculation for the hydrogen-LPG fueling station that is the subject of this study, the hydrogen-LPG type fueling station does not show the unacceptable hazardous area (> 1 × 10E-3) proposed by HSE. The level of individual risk for both the public and the worker is within acceptable limits. In societal risk assessment, the model to be interpreted shows the distribution of risks in an acceptable range(ALARP, As Low As Reasonably Practicable). To ensure improved safety, we recommend regular inspections and checks for high-risk hydrogen reservoirs, dispensers, tube trailer leaks, and LPG vapor recovery lines.

• Journal of Advanced Marine Engineering and Technology
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• v.40 no.9
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• pp.780-785
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• 2016

Heavy oil used as ship propulsion has a serious issue regarding exhaust emission of global warming. Recently, among large-scale merchant ships are using LNG as green ships so called ech-ships. In this study, an vaporizer and pipes under cryogenic and high pressure load were considered to evaluate structural integrity according to codes. Structural analysis of the vaporizer and pipes was performed using the commercial code, ANSYS. Integrity evaluation of the vaporizer based on von Mises stress was performed in accordance with allowable stress specified in ASME Boiler & Pressure Vesssel Section VIII Division 2. To assess structural integrity of the pipes, stress components were combined and compared with ASME B31.3. The calculated stresses for all load cases are lower than allowable stresses, therefore the structural integrity of equipments are verified.

• Journal of KIISE:Information Networking
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• v.30 no.1
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• pp.9-16
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• 2003

In this paper, we propose a method for supporting VCR operations in a patching based multicast VOD system. Random access, pause and resume operations are supported in our system, and the channel and session scheduling algorithms for the VCR operations are proposed. When it is necessary to join a sharable multicast channel in the admission control for the VCR operations, the patching technique, which shares an on-going regular channel and allocates a new patching channel for the missing data, is used. Therefore, unlike the previous approach that allocates an excessive number of I-channels, service latency is minimized and channel usage is optimized in our system. Moreover buffered data. which is saved in disk during patching, is reused to prevent unnecessary patching channel allocation. For this. the patching management information is extended and a buffed data management scheme is proposed. In our system, the First-Come-First-Served scheduling is used to inform clients the service latency for the VCR operations immediately.

• The KIPS Transactions:PartC
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• v.16C no.2
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• pp.223-228
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• 2009

Efficient service discovery mechanism is a crucial feature for a hybrid ad-hoc network supporting extension of a wireless ad-hoc network to the Internet. We propose an efficient cross-layer service discovery mechanism using non-disjoint multi-path source routing protocol for hybrid ad-hoc networks. Our scheme has advantages of multi-path routing protocol and cross-layer service discovery. Intuitively, it is not difficult to imagine that the cross-layer service discovery mechanism could result in a decreased number of messages compared to the traditional approach for handling routing independently from service discovery. By simulation, we show that faster route recovery is possible by maintaining multiple routing paths in each node, and the route maintenance overhead can be reduced by limiting the number of multiple routing paths and by maintaining link/node non-disjoint multi-path.

• Journal of Food Hygiene and Safety
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• v.3 no.4
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• pp.193-202
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• 1988

A pesticide monitoring study was undertaken for the strawberry and cucumber samples collected from plastic film houses and additional strawberries from supermarkets located in Seoul city in 1983 to evaluate pesticide residues in these food commodities and also to give basic informations in establishing maximum residue limits. Organophosphorus insecticides were not detected in any cucumber samples except that diazinon found with low residue levels in two strawberry samples. Fungicide procymidone and chlorothalonil were detected with considerable high frequencies in these vegetables while their residue levels were fairly low. Even the maximum residue levels. they were much lower than maximum residue limits established in these vegetables in Environment Administration. Korea. Of the strawberries from supermarkets in Seoul city, procymidone, chlorthalonil and dichlofluanid fungicides were also detected with similar detection frequencies and residue levels to those from the plas tic film houses. By washing the strawberries with tap water, the residues were removed from 38% to 95% of the total residues. Presently, it is considered that pesticide residues in strawberry and cucumber may be no harmfullevels for food commodities.

• Journal of Aerospace System Engineering
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• v.13 no.5
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• pp.65-71
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• 2019

In this study, as a part of the aging aircraft performance improvement project for which no design information is provided, a new type of blade antenna is installed on the main part of the aging aircraft, and the method of proving the fatigue life of the main part of the aircraft is reviewed and summarized. There are various methods to prove fatigue life according to the manufacturer and aircraft design conditions. The fatigue life prediction and damage tolerance range of the relevant site were obtained through related regulations and industry examples. From these results, the fatigue life of newly installed antennas around the main parts of the aging aircraft was evaluated and the maintenance period and criteria were set according to the damage tolerance.

• The Journal of the Korea Contents Association
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• v.19 no.5
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• pp.472-483
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• 2019

This study purposed to analyze how teacher experience of instructional change (EIC), teacher morale (TM), and school climate (SC) mediate or moderate the relationship between teacher efforts on instructional improvement (EII) and teacher efficacy (TE). For the purpose, the 6th year data of Gyeonggi Education Panel Study (GEPS) which was administered in 2017 for the 9th grade students and their teachers from 197 middle schools in Gyeonggi Province was used. As results, the mediation effects of EIC on the link between EII and TE was found only under the innovative climate. The moderation effects of TM on the connection between EIC and TE were appeared in both of the permissive and the innovative climate. Finally, the moderated mediation effects of the TM in the innovative climate were bigger rather than in the permissive climate.

• Korean Journal of Culture and Social Issue
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• v.19 no.1
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• pp.45-68
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• 2013

In this study, We examined the dual path model in which entitlement rage and sexual dominance on the one of two pathway, sexual permissiveness and sexual objectification on another pathway mediated the relation between narcissism and sexual aggression. In addition, it was investigated whether alcohol use and rape myths acceptance have moderating effects in the pathways from sexual dominance and sexual objectification to sexual aggression on our path model. Data from 368 male college students in four university in Chungcheong province were analyzed using structural equation modeling. Results in structural equation modeling exhibited that narcissism affected sexual aggression through mediating effects of entitlement rage and sexual dominance, and through mediating effects of sexual permissiveness and sexual objectification. Furthermore, alcohol use and rape myths acceptance only moderated the relation between sexual dominance and sexual aggression on our model. We discussed the meaning of results and the implications for further study.