• Journal of IKEEE
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• v.9 no.2 s.17
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• pp.123-135
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• 2005

3GPP RLC protocol specification adopted a window-controlled selective-repeat ARQ scheme for provisioning reliable data transmission. Inevitably, the re-ordering issue arises in the 3GPP's ARQ since it belongs to the selective-repeat ARQ clan. A long re-ordering time results in the degradation of throughput and delay performance, and may invoke the overflow of the re-ordering buffer. Also, the re-ordering time must be regulated to meet the requirements of some services which are both loss-sensitive and delay-sensitive. In the 3GPP's ARQ, we may deflate the occupancy of the re-ordering buffer by reducing the window size and/or length of the status report period. Such a decrease, however, deteriorates the throughput and delay performance and encroaches the resource of the reverse channel. Aiming at reducing the occupancy at the re-ordering buffer while suppressing the degradation of throughput and delay performance, we propose threshold-dependent occupancy control schemes, identified as post-threshold and pre-threshold schemes, as supplements to the 3GPP's ARQ. For judging the effectiveness of the proposed schemes, we investigate peak occupancy, maximum throughput and average delay in the practical environment involving fading channels. From the simulation results, we observe that the proposed schemes invoke the performance trade-off between occupancy and throughput in general. Also, we reveal that the post-threshold scheme is able to improve the throughput and delay performance of the ordinary 3GPP's ARQ without inflating the occupancy of the re-ordering buffer.

• Journal of the Korea institute for structural maintenance and inspection
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• v.21 no.2
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• pp.78-86
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• 2017

As the amount of slag generated annually increases, attempts to recycle slag as high value products are underway in order to develop an efficient resource recycling industry based on slag and derive economic benefits as well. However, the application of electric arc furnace (EOS) slag as construction material is practically limited because of the unstable substances included in it, such as free CaO.(EOS contains a small amount of free CaO, but several limitations still exist. Slag is stored for more than 3 months depending on the quantity of slag, which leads to additional economic loss. In this study, the amount of free CaO present in EOS is quantitatively evaluated to examine its qualities as a potential construction material and verify its application as concrete material. The quantitative analysis of free CaO present in EOS is performed using ethylene glycol. The free CaO contents of EOS samples were found to be below 0.5%. This satisfies the criteria specified in KS F 4571, which states that the CaO content should be below 40% and $CaO/SiO_2$ ratio should be below 2.0. In addition, it was confirmed that free CaO content difference appears to be dependent on the aging period and storage position.

• Journal of the Korea Society of Computer and Information
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• v.20 no.3
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• pp.19-27
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• 2015

Technologies of wind power generation for development of alternative energy technology have been accumulated over the past 20 years. Wind power generation is environmentally friendly and economical because it uses the wind blowing in nature as energy resource. In order to operate wind power generation efficiently, it is necessary to accurately predict wind speed changing every moment in nature. It is important not only averagely how well to predict wind speed but also to minimize the largest absolute error between real value and prediction value of wind speed. In terms of generation operating plan, minimizing the largest absolute error plays an important role for building flexible generation operating plan because the difference between predicting power and real power causes economic loss. In this paper, we propose a method of wind speed prediction using numeric prediction algorithm-based wind speed forecast model made to analyze the wind speed forecast given by the Meteorological Administration and pattern value for considering seasonal property of wind speed as well as changing trend of past wind speed. The wind speed forecast given by the Meteorological Administration is the forecast in respect to comparatively wide area including wind generation farm. But it contributes considerably to make accuracy of wind speed prediction high. Also, the experimental results demonstrate that as the rate of wind is analyzed in more detail, the greater accuracy will be obtained.

• Journal of the Korean Geosynthetics Society
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• v.14 no.4
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• pp.79-86
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• 2015

Korean territories has formed about 70% of mountainous areas that have acidified serious level to average pH 4-5. There are a number of abandoned metal mines about 1,000 in Korea. However, mine tailings and waste rock included heavy metals are exposed to long-term environment without prevention facility or treatment system. Thus, ongoing management and monitoring of soil environment are required. Most of abandoned mine scattered in forest areas of slopes. Soil erosion due to continuous rainfall in the slopy areas can cause the secondary pollution by the influence eutrophication of water system and the productivity loss of the plant. Therefore, this study would like to estimate pH leaching rate by artificial rainfall using waste neutralization-agent in lysimeter. Moreover, the potentially of secondary pollution related to precipitation is figured out through the experiments, and the optimal planting methods would examinate after neutralizing treatment in soil. Experiments composed three kinds of lysimeter; lysimeter 1 had filled only acidic soil, lysimeter 2 had neutralized soil, and lysimeter 3 had planting plants after neutralized soil. In the results, lysimeter 2 showed the lowest pH leaching, and there is not specific relativity with pH leaching of the seasonal characteristics.

• Asian-Australasian Journal of Animal Sciences
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• v.26 no.7
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• pp.995-1002
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• 2013

The effect of conjugated linoleic acid (CLA) feeding on growth performance and fatty acid profiles in thigh meat of broiler chicken was investigated using meta-analysis with a total of 9 studies. Overall effects were calculated by standardized mean differences between treatment (CLA fed) and control using Hedges's adjusted g from fixed and random effect models. Meta-regression was conducted to evaluate the effect of CLA levels. Subgroups in the same study were designated according to used levels of CLA, CP levels or substituted oils in diets. The effects on final body weight, weight gain, feed intake and feed conversion ratio were investigated as growth parameters. Total saturated and unsaturated fatty acid concentrations and C16:0, C18:0, C18:2 and C18:3 concentrations in thigh meat of broiler chicken were used as fatty acid profile parameters. The overall effect of CLA feeding on final weight was negative and it was only significant in fixed effect model (p<0.01). Significantly lower weight gain, feed intake and higher feed conversion ratio compared to control were found (p<0.05). CLA feeding on the overall increased total saturated fatty acid concentration in broilers compared to the control diet (p<0.01). Total unsaturated fatty acid concentration was significantly decreased by CLA feeding (p<0.01). As for individual fatty acid profiles, C16:0, C18:0 and C18:3 were increased and C18:2 was significantly decreased by CLA feeding (p<0.01). In conclusion, CLA was proved not to be beneficial for improving growth performance, whereas it might be supposed that CLA is effective modulating n-6/n-3 fatty acids ratio in thigh meat. However, the economical compensation of the loss from suppressed growth performance and increased saturated fatty acids with the benefit from enhanced n-6/n-3 ratio should be investigated in further studies in order to propose an appropriate use of dietary CLA in the broiler industry.

• Journal of Broadcast Engineering
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• v.14 no.5
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• pp.573-588
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• 2009

In this paper, we propose a novel video quality degradation monitoring scheme titled VR-VQMS(Visual Rhythm based Video Quality Monitoring Scheme) over an IPTV service prone to packet losses during network transmission. Proposed scheme quantifies the amount of quality degradation due to packet losses, and can be classified into a RR(reduced-reference) based quality measurement scheme exploiting visual rhythm data of H.264-encoded video frames at a media server and reconstructed ones at an Set-top Box as feature information. Two scenarios, On-line and Off-line VR-VQMS, are proposed as the practical solutions. We define the NPSNR(Networked Peak-to-peak Signal-to-Noise Ratio) modified by the well-known PSNR as a new objective quality metric, and several additional objective and subjective metrics based on it to obtain the statistics on timing, duration, occurrence, and amount of quality degradation. Simulation results show that the proposed method closely approximates the results from 2D video frames and gives good estimation of subjective quality(i.e.,MOS(mean opinion score)) performed by 10 test observers. We expect that the proposed scheme can play a role as a practical solution to monitor the video quality experienced by individual customers in a commercial IPTV service, and be implemented as a small and light agent program running on a resource-limited set-top box.

• Journal of Korea Society of Industrial Information Systems
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• v.19 no.1
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• pp.13-18
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• 2014

Sensor nodes are used for monitoring and collecting the environmental data via wireless sensor network. The wireless sensor network with various sensor nodes draws attention as a key technology in ubiquitous computing. Sensor nodes has very small memory capacity and limited power resource. Thus, it is essential to have energy efficient strategy for the sensor nodes. Since the sensor nodes are operating on the same frequency bands with ISM frequency bands, the interference by the devices operating on the ISM band degrades the quality of communication integrity. In this paper, the convolutional code is proposed instead of ARQ for the error control for the sensor network. The proposed convolutional code was implemented and the BER performance is measured. For the fixed transmitting powers of -19.2 dBm and -25dBm, the BER with various communication distances are measured. The packet loss rate and the retransmission rate are calculated from the measured BER. It is shown that the porposed method obtained about 9~12% and 12-19% reduction in retransmission rate for -19.2 dBm and -25 dBm respectively.

• Journal of the Korean association of regional geographers
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• v.11 no.1
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• pp.29-39
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• 2005

Silk Road is the term involving all traffic roads connecting the East to the West, and ancient Korean culture has became globalized through Silk Road. In this paper, natural environment of Silk Road is considered as fundamental data in order to understand the Western culture introduced through Silk Road. Silk Road region is classified into Loess Plateau district; arid basin district; and high mountains district; Hesi Corridor(河西回廊) is the transition zone that the southeastern part of $W{\breve{u}}w{\bar{e}}i$(武威) is Loess Plateau district; other northwestern part is arid basin district Loess Plateau district, composed of homogeneous fines, has experienced dramatic soil loss by bringing under cultivation. At recent times, reforestation and construction of check-dam have been in operation to cope with this problems, Arid basin district; although at midlatitude, is desert climate because it is far from the ocean and is surrounded by high mountains. Oasis of Hesi Corridor is continuous linearly, but that of arid basin district is sporadic. In $H{\bar{a}}mi$ and $T{\breve{u}}l{\breve{u}}f{\bar{a}}n$(吐魯番) fruit-growing using karez flourishes, And glacier of $Ti{\bar{a}}nshian$(天山) Mts. and $Q{\bar{i}}lian$(祁連) Mts. is very important to arid basin district because of supplying water resource. In the tundra zone surrounding alpine glacier, are distributed widely solifluction lobes and earth hummocks.

• The Transactions of the Korea Information Processing Society
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• v.5 no.6
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• pp.1610-1619
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• 1998

The ABR service class provides feedback based traffic control to transport bursty data traffic efficiently. Feedback based congestion control has first been studied to be applied to unicast connections. Recently. several congestion control algorithms for multicast connections have also been proposed as the number of ABR applications requiring multicast increases. With feedback based congestion control, the effectiveness of a traffic control scheme diminishes as propagation delay increases. Especially for a multicast connection, a remote destination may suffer unfair service compared to a local destination due to the delayed feedback. Amelioration of the disadvantages caused by feedback delay is therefore more important for remote destinations in multicast connections. This paper proposes a new switch behavior to provide effective feedback based mathc control for rentoh destinations. The proposed switches adjust the service rate dynamically in accordance woth the state of the downstream, that is, the congestion of the destinaion is immediately controlled by the nearest apstream switch before the source to ramp down the transmission rate of the connection. The proposed switch has an implementation overhead to have a separate buffer for each VC to adjust the service rate in accordance with a backward Rm cell of each VC. The buffer requirement id also increased at intermediate switches. Simulation results show that the proposed switch reduces the cell loss rate in both the local and the remote destinations and slso amelioratd the between the two destinations.

• Journal of Wetlands Research
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• v.19 no.4
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• pp.523-532
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• 2017

Environmental problems in urban spaces tend to result from excessive use of resources faster than the ecosystem can recover itself. In order to address this problem, city or municipal governments tend to devise plans and policies to lead development within their ecological carrying capacity. This study computes ecological capacity of Asan city, Province Chung Nam, South Korea through applying the concept of ecological footprint. This study finds ecological footprint and deficit of Asan city in 2015 were 5.12 and -4.99, respectively. From 2001 to 2015, Asan city experienced not only an 81% increase of ecological footprint, but also a 190% increase of ecological deficit. Such results suggest that Asan city has experienced a steady increase of resource consumption due to population increase and urban growth, indicating that loss of ecological spaces such as green space, farmland, wetland and so on restoring the ecosystem has been accelerated. Therefore, in order to promote sustainable development, Asan city should not only protect green space, farmland, wetland, and so on but also create urban growth plans and policies taking into account its environmental capacity of the city. This study provides suggestions for Asan city to lead urban growth within its environmental capacity by applying ecological deficit.