• Annual Conference of KIPS
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• 2005.05a
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• pp.1701-1704
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• 2005

이동 컴퓨팅 시스템의 결함 내성을 지원하기 위해 다양한 검사점 조정 기법과 메시지 로깅 기법들이 제시되어졌다. 그러나 이동 호스트의 이동성 때문에 이러한 기법들은 복잡하고 비효율적이 될 수 있다. 본 논문에서는 이동 에이전트 기반의 결함 내성 기법을 제안한다. 제안된 기법에서는 이동 호스트가 자신의 복구 정보를 일정한 거리 내에 두기위해 두 개의 이동 에이전트들과 고정 에이전트를 사용하며, 에이전트에 의한 복구 정보의 이동이 이동 호스트의 이동과 비동기적으로 이루어지므로, 이동 호스트의 핸드오프를 지연시키지 않는다.

• Proceedings of the Korean Information Science Society Conference
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• 2000.04a
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• pp.454-456
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• 2000

실시간의 특성을 가지는 데이터의 경우 네트워크상에서 분실된 패킷을 복구시키기 위해서 FEC 방법을 사용한다. FEC는 최소한의 지연만으로 손실 패킷의 복구를 효율적으로 할 수 있는 장점을 가지고 있으나 네트워크상에서의 패킷 손실 특성에 많이 의존되는 경향이 있다. ITU-T의 Study Group 16 에서의 Real-Time Transport Protocol(RTP)를 사용하여 네트워크에서 분실된 패킷을 복원시키는 방법으로 Media-independent error-correction scheme을 정하였다. 이 Scheme에 의해 만들어진 error-correction을 위한 신호화 media bitstream은 UDP 에 의해 encapsulation될 RTP에 실리게 된다. Scheme은 real-time이라는 환경에 유리하도록 bandwidth 와 latency 그리고 cost를 최소화하려고 했으며 이에 따라 네 가지 scheme을 정하였다. 네 가지의 Scheme은 오버헤드와 지연시간이 크기가 차별화를 두어 네트워크 환경의 변화에 적응하도록 하였다. 그러나 네트워크 환경에 보다 더 탄력적이며 효율적으로 적응하기 위해서 또 하나의 scheme을 제안한다. 새로 고안한 이 다섯 번째 scheme은 scheme 3 에 비해 작은 latency를 가지고 장점이 있는 반면 연속적으로 분실된 패킷에 대한 복원확률이 다소 떨어진다. 하지만 scheme 1과 2에 비해서는 연속적인 패킷 분실의 복원확률이 높아 네트워크환경에 따라 scheme 4를 사용하면 네 개의 scheme을 사용하여 분실패킷의 복원을 하는 경우보다 보다 효율적인 전송과 복원이 이루어질 것이다.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.62 no.1
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• pp.73-78
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• 2017

This study was conducted to elucidate the effects of mulching materials on root growth characteristics and weed occurrence of Platycodon grandiflorum transplants (3 years old) in organic farming. After transplanting, roots were mulched with one of three mulching materials (biodegradable film, sawdust, or rice husks) or a control (no mulching). The average root diameter of all mulching groups was 28.1 mm, which was 5.1 mm thicker than the no-mulching treatment. Roots with the biodegradable film treatment were the thickest at 30.9 mm. Root length was the shortest, 22.0 cm, with rice husk mulching. The number of rootlets was the highest with film mulching (36.0 rootlets/root) and the lowest with no mulching. For root fresh weight, which directly affects yield, the average of treated and untreated roots was 100 and 56 g/root, respectively. The highest fresh weight was in the biodegradable film plot (130 g/root). The mulching treatment groups showed a weed inhibition effect compared with the no-mulching treatment. The dominant weeds with the no-mulching treatment were Setaria viridis and Digitaria ciliaris, and that with the mulching treatment was Setaria viridis. Average annual weed occurrence across all treatments was 72%. Weed occurrence was the highest with the no-mulching treatment ($125weeds/m^2$), and there were no weeds with the biodegradable film treatment.

• Journal of KIISE:Computer Systems and Theory
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• v.32 no.6
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• pp.306-313
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• 2005

Conditional branch prediction is an important technique for improving processor performance. Branch mispredictions, however, waste a large number of cycles, inhibit out-of-order execution, and waste electric power on mis-speculated instructions. Hence, the branch predictor with higher accuracy is necessary for good processor performance. In global-history-based predictors like gshare and GAg, many mispredictions come from commit update of the history. Some works on this subject have discussed the need for speculative update of the history and recovery mechanisms for branch mispredictions. In this paper, we present a simple mechanism for recovering the branch history after a misprediction. The proposed mechanism adds an age_counter to the original predictor and doubles the size of the branch history register. The age_counter counts the number of outstanding branches and uses it to recover the branch history register. Simulation results on the Simplescalar 3.0/PISA tool set and the SPECINTgS benchmarks show that gshare and GAg with the proposed recovery mechanism improved the average prediction accuracy by 2.14$\%$ and 9.21$\%$, respectively and the average IPC by 8.75$\%$ and 18.08$\%$, respectively over the original predictor.

• Journal of KIISE
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• v.43 no.12
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• pp.1420-1427
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• 2016

This paper proposes a method taking advantage of Fog computing and SDN in the connected vehicle environment which is having an unstable communication channel and a dynamic topology. For this purpose, the controller should understand the current state of the overall network by maintaining recent network topology, especially, the mobility information of mobile nodes. These are managed by the controller, and are important in unstable conditions in the mobile environment. The mobility levels are divided into 3 categories. We can efficiently exploit that information. By utilizing network state information, we suggest two outcomes. First, we reduce the control message overhead by adjusting the period of beacon messages. Second, we propose a recovery process to prepare the communication failure. We can efficiently recover connection failure through mobility information. Furthermore, we suggest a path recovery by decoupling the cloud level and the fog level in accordance with application data types. The simulation results show that the control message overhead and the connection failure time are decreased by approximately 55% and 5%, respectively in comparison to the existing method.

• Journal of the Korean Geosynthetics Society
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• v.17 no.1
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• pp.75-83
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• 2018

This paper described a results of dynamic stability by using wheel tracking test and unconfined compression test, in order to evaluate behavior characteristics on the developed pocketable expansion material for emergency restoration of ground cavity. The wheel tracking test result showed that the settlement increment ratio of the recovered ground by the expansion material was decreased compared to the sandy ground in high load condition. That is, it was confirmed that the expansion material was able to restrain the settlement due to the material stiffness, and the same results were obtained for the dynamic stability evaluation results. From the results of unconfined compression test, the pocketable expansion material was found to be able to fully support load on the restored cavity.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.35 no.4
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• pp.315-319
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• 1990

In order to determine the optimum sowing date of Cassia tora L., ecological characters, components and yield were investigated under vinyl-mulching and non-mulching condition. Emergence date and maturation date of vinyl-mulching condition were earlier than those of non-mulching condition. especially with maturation date being about 30 days earlier, Under vinyl-mulching condition, length of stem and pod were longer, number of branches, pods and seeds per plant were increased, stem diameter was thicker, and weight of 1000 grains was heavier. Seed yield per 10a under vinyl-mulching was twice as high as that of non-nulching condition. As sowing date was delayed, the maturation date was progressively delayed. At sowing date of April 10, plants showed the longest in length of stem and pod, the largest in number of pods per plant and number of grains per pod, and the highest in weight of 1000 grains and seed yield. Judging from the results, optimum sowing of Cassia tora L. appeared to be April 10.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.18 no.5
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• pp.162-168
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• 2004

Service restoration is an emergency control in distribution control centers to restore out-of-service area as soon as possible when a fault occurs in distribution networks. Therefore, it requires fast computation time and high quality solutions for load balancing. In this paper, a load balance index and heuristic guided best-first search are proposed for these problem. The proposed algorithm consists of two parts. One is to set up a decision tree to represent the various switching operations available. Another is to identify the most effective the set of switches using proposed search technique and a feeder load balance index. Test results on the KEPCO's 108 bus distribution system show that the performance is efficient and robust.

• Journal of the Korea Computer Graphics Society
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• v.22 no.5
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• pp.1-16
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• 2016

In this paper, we propose and efficient curve reconstruction method based on the classical least-square fitting scheme. Specifically, given planar sample points equipped with normals, we reconstruct the objective curve as the zero set of a hierarchical implicit ZP(Zwart-Powell)-spline that can recover large holes of dataset without loosing the fine details. As regularizers, we adopted two: a Tikhonov regularizer to reduce the singularity of the linear system and a discrete Laplacian operator to smooth out the isocurves. Benchmark tests with quantitative measurements are done and our method shows much better quality than polynomial methods. Compared with the hierarchical bi-quadratic spline for datasets with holes, our method results in compatible quality but with less than 90% computational overhead.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.34 no.2B
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• pp.151-161
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• 2009

The PULSE protocol can greatly reduce power consumption using a node's sleep state. But this protocol does not consider movement of a sink node in a sensor network. In the mobile sensor network a routing protocol must recover path error by movement of a sink node as quickly as possible. Therefore we have to achieve fast path recovery and power saving to support movement of a sink node in a sensor network. This paper proposes the Mobile PULSE protocol which is a improved routing protocol for a mobile sink node. And we evaluate Mobile PULSE and show that the Mobile PULSE reduces the recovery time about 40% compared with original PULSE protocol. Mobile PULSE increases energy consumption than PULSE as a maximum of 0.8%, which means Mobile PULSE is similar to PULSE in energy consumption. This paper shows mobile PULSE's capability in the mobile sensor network through evaluation of path recovery time and power consumption.