• Journal of the Korea Institute of Information and Communication Engineering
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• v.22 no.11
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• pp.1448-1454
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• 2018

In an optical observing system, three pairs of observations at equal time intervals are required for the orbit determination method to obtain orbital information of an unknown space objects. In this paper, we propose a method of estimating a streak for acquiring three pairs of observations using one streak image information. Satellite trajectory simulation data were generated for nine cases using the STK program in order to verify the characteristics of the orbit of space object and estimation performance. Simulation was performed by applying three approaches that can estimate the next streak position after a few seconds from one streak image information, and the estimation performance was evaluated. Linear vector method and Kalman Filter method based on the linear assumption tend to increase the estimation error in the region where the nonlinearity is large. However estimation method using the polynomial curve fitting based on the least square method showed smaller and uniform error result than the previous methods.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.17 no.7
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• pp.739-748
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• 1992

A CGM iterative systolic algorithm to solve large sparse linear systems of equations is presented. For implementation of the algorithm, a systolic array using the stripe structure is proposed. The matrix A is decomposed into a strictly lower triangular matrix, a diagonal matrix, and a strictly up-per triangular matrix, and the two formers and the tatter· are concurrently computed by different linear arrays. Hence, the execution time of this approach Is reduced to half of the execution time of the that a linear array is used. computation of the Irregularly distributed sparse matrix can be executed effectively by using the stripe structure.

• Journal of Industrial Convergence
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• v.17 no.4
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• pp.131-137
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• 2019

In infrastructure wireless mesh networks (WMNs), in order to improve mobile users' satisfaction for the given cache hit ratio, we investigate an User centric Cache Allocation (UCA) scheme while reducing cache cost in a mesh router (MR) and expected transmission time (ETT) for content search in cache. To minimize ETT values of mobile users, a genetic algorithm based UCA (GA-UCA) scheme is provided. The goal is to maximize mobile users' satisfaction via our well defined utility, which considers content popularity and the number of mobile users. Finally, through solving optimization problem we show the optimal cache can be allocated for UCA and GA-UCA. Besides, a WMN provider can find the optimal number of mobile users for user centric cache allocation in infrastructure WMNs.

• Proceedings of the Korea Technical Association of the Pulp and Paper Industry Conference
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• 2010.04a
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• pp.227-227
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• 2010

기존 도공지 생산 공정에서 널리 사용되던 블레이드 도공방식을 대체할 수 있을 것으로 기대되는 커튼코팅 방식은 스크래치, 스트릭, 미스팅, 블레이드의 마모등을 발생시키지 않고 고고형분 도공이 가능하며 우수한 커버리지를 갖는 도공층을 형성시킬 수 있다는 장점을 갖고 있다. 뿐만 아니라 하나의 코팅 유닛에서 여러개의 도공층을 한번에 형성시킬 수 있어 설비투자비용 및 건조에너지, 공간활용도 절감 측면에서도 한층 유리하다. 커튼 코팅 방식에서 도공액의 유동은 도공액이 필름 형태로 사출되는 sheet forming zone, 도공액 커튼이 낙하하는 curtain flow zone, 도공액 커튼이 원지와 접촉하는 impingement zone으로 나뉜다. 커튼 코팅이 이루어지기 위해서는 sheet forming zone과 curtain flow zone에서 도공액이 얇은 막 상태를 안정적으로 유지하고 impingement zone에서는 고속으로 이송되는 도공원지에 의한 급격한 신장 조건에서 도공액 필름이 끊어지지 않고 유지되어야 한다. 이를 위해 유화제를 통해 동적 표면 장력을 낮초고 rheology modifier를 통해 점도 및 신장점도를 조절해 도공액의 커튼 안정성을 부여하는 연구가 보고된 바 있다. 도공액 제조시 바인더로 널리 사용되는 S/B 라텍스는 입도, 유리전이온도, 표면전하 등 그 특성을 달리하여 제조할 수 있으며 이러한 특성에 따라 도공액의 점도와 같은 유변특성이 변화하여 도공액의 커튼 안정성에 영향할 것으로 예상된다. 따라서 본 연구에서는 입자경과 유리전이온도, 카르복실화 정도 등을 달리한 다양한 S/B 라텍스를 사용하여 유변특성을 달리한 도공액을 제조하고 커튼 안정성의 변화를 살펴보고자 하였다.

• Annual Conference on Human and Language Technology
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• 2023.10a
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• pp.382-387
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• 2023

현재 GPT-4와 같은 거대한 언어 모델이 기계 번역, 요약 및 대화와 같은 다양한 작업에서 압도적인 성능을 보이고 있다. 그러나 이러한 거대 언어 모델은 학습 및 적용에 상당한 계산 리소스와 도메인 특화 미세 조정이 어려운 등 몇 가지 문제를 가지고 있다. In-Context learning은 데이터셋에서 추출한 컨택스트의 정보만으로 효과적으로 작동할 수 있는 효율성을 제공하여 앞선 문제를 일부 해결했지만, 컨텍스트의 샷 개수와 순서에 민감한 문제가 존재한다. 이러한 도전 과제를 해결하기 위해, 우리는 Super In-Context Learning (SuperICL)을 활용한 새로운 방법론을 제안한다. 기존의 SuperICL은 적용한 플러그인 모델의 출력 정보를 이용하여 문맥을 새로 구성하고 이를 활용하여 거대 언어 모델이 더욱 잘 분류할 수 있도록 한다. Super In-Context Learning for Generation은 다양한 자연어 생성 작업에 효과적으로 최적화하는 방법을 제공한다. 실험을 통해 플러그인 모델을 교체하여 다양한 작업에 적응하는 가능성을 확인하고, 자연어 생성 작업에서 우수한 성능을 보여준다. BLEU 및 ROUGE 메트릭을 포함한 평가 결과에서도 성능 향상을 보여주며, 선호도 평가를 통해 모델의 효과성을 확인했다.

• Composites Research
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• v.37 no.1
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• pp.21-31
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• 2024

This review paper investigates the use of shockwave attenuating materials within composite structures to enhance personnel protection against blast-induced traumatic brain injury (bTBI). This paper also introduces experimental methodologies exploited in the generation and measurement of shockwaves to evaluate the performance of the shock dissipating composites. The generation of shockwaves is elucidated through diverse approaches such as high-energy explosives, shock tubes, lasers, and laser-flyer techniques. Evaluation of shockwave propagation and attenuation involves the utilization of cutting-edge techniques, including piezoelectric, interferometer, electromagnetic induction, and streak camera methods. This paper investigates phase-separated materials, including polyurea and ionic liquids, and provides insight into composite structures in the quest for shockwave pressure attenuation. By synthesizing and analyzing the findings from these experimental approaches, this review aims to contribute valuable insights to the advancement of protective measures against blast-induced traumatic brain injuries.

• Journal of Bio-Environment Control
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• v.23 no.4
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• pp.329-336
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• 2014

As an abiotic stress, chilling stress is one of the major factors limiting plant growth and increasing susceptibility to pathogens. Therefore, enhancing stress tolerance in plants is an important strategy for their survival under unfavorable environmental conditions. The objective of this study was to determine the effects of the exogenous application of salicylic acid (SA) or nitric oxide (NO) on chilling tolerance in pepper seedlings. Pepper (Capsicum annuum L. 'kidaemanbal') seedlings were grown under normal growing conditions ($20/25^{\circ}C$, 15 hours photoperiod, $145{\pm}5{\mu}mol{\cdot}m^{-2}{\cdot}s^{-1}$, fluorescence lamps) for 23 days after transplanting. The solution (3 mL) of 1 mM SA and 0.3 mM NO with surfactant triton 0.1% were sprayed two times a week, respectively. Right after the completion of chemical application, seedlings were subjected to chilling condition at $4^{\circ}C$ for 6 hours under dark condition and then the seedlings were recovered at the normal growing conditions for 2 days. In order to assess plant tolerance against chilling stress, growth characteristics, chlorophyll fluorescence (Fv/Fm), and membrane permeability were determined after chilling stress imposition. Total phenolic concentration and antioxidant capacity were measured during the whole experimental period. Disease incidence for pepper bacterial spot and wilt was also analyzed. Pepper seedlings treated with SA or NO were maintained similar dry mass ratio, while the value in control increased caused by chilling stress suggesting relatively more water loss in control plants. Electrolyte leakage of pepper seedlings treated with SA or NO was lower than that of control 2 days after chilling treatment. Fv/Fm rapidly decreased after chilling stress in control while the value of SA or NO was maintained about 0.8. SA increased higher total phenolic concentration and antioxidant capacity than NO and control during chemical treatment. In addition, increase in total phenolic concentration was observed after chilling stress in control and NO treatment. SA had an effect on the reduction of bacterial wilt in pepper seedlings. The results from this study revealed that pre-treatment with SA or NO using foliar spray was effective in chilling tolerance and the reduction of disease incidence in pepper seedlings.

• Journal of Korea Society of Industrial Information Systems
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• v.22 no.1
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• pp.1-9
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• 2017

With the Development of Wireless Network Technology and Wireless Link Technology, Wireless Mesh Network (WMN) is Attracting Attention as a Key Technology to Construct the Wireless Transit Network. The WMN has been Studied for a Long Time in Various Fields, however there are still many Problems that have not been solved yet. One of them is the Routing Problem to find an Optimal path in a Multi-hop Network Composed of Wireless Links. In the Hybrid-WMN, which is one of the Three Types of WMN, Optimal Path Selection Requires Research on Path Search Protocols that Effectively use the Infrastructure Mesh as a Transit Network, Together with Research for a Routing Metric with Excellent Performance. Therefore, this Paper Proposes a Dual Mode-AODV(Ad hoc On-demand Distance Vector) for Hybrid-WMN. Simulation result shows that the Path Selection Delay was Reduced by 52% than AODV when the Proposed Dual Mode-AODV was applied.

• The KIPS Transactions:PartC
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• v.15C no.1
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• pp.45-50
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• 2008

Mobile ad hoc networks (MANETs) allow mobile nodes to communicate among themselves via wireless multiple hops without the help of the wired infrastructure. Therefore, in the MANET, a route setup mechanism that makes nodes not within each other's transmission range communicate is required and, for this, the Ad-hoc On-demand Distance Vector (AODV) was proposed as one of the reactive routing protocols well suited for the characteristics of the MANET. AODV uses the hop count as the routing metric and, as a result, a node selects the farthest neighbor node as its next hop on a route, which results in a problem of deteriorating the overall network throughput because of selecting a relatively low data rate route. In this paper, we propose an efficient reactive routing protocol based on the multi-rate aware MAC. Through the simulations, we analyze the performance of our proposed mechanism and, from the simulation results, we show that our proposed mechanism outperforms the existing mechanism.

• The Transactions of the Korea Information Processing Society
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• v.13 no.2
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• pp.48-59
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• 2024

As functions that support virtualization on their own in hardware are developed, user applications having various workloads are operating efficiently in the virtualization system. SR-IOV is a virtualization support function that takes direct access to PCI devices, thus giving a high I/O performance by minimizing the need for hypervisor or operating system interventions. With SR-IOV, network I/O acceleration can be realized in virtualization systems that have relatively long I/O paths compared to bare-metal systems and frequent context switches between the user area and kernel area. To take performance advantages of SR-IOV, network resource management policies that can derive optimal network performance when SR-IOV is applied to an instance such as a virtual machine(VM) or container are being actively studied.This paper evaluates and analyzes the network performance of SR-IOV implementing I/O acceleration is compared with Virtio in terms of 1) network delay, 2) network throughput, 3) network fairness, 4) performance interference, and 5) multi-network. The contributions of this paper are as follows. First, the network I/O process of Virtio and SR-IOV was clearly explained in the virtualization system, and second, the evaluation results of the network performance of Virtio and SR-IOV were analyzed based on various performance metrics. Third, the system overhead and the possibility of optimization for the SR-IOV network in a virtualization system with high VM density were experimentally confirmed. The experimental results and analysis of the paper are expected to be referenced in the network resource management policy for virtualization systems that operate network-intensive services such as smart factories, connected cars, deep learning inference models, and crowdsourcing.