• Environmental and Resource Economics Review
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• v.16 no.3
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• pp.511-544
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• 2007

He purpose of this paper is to estimate environmental efficiency and grasp the relationship between trade and environmental efficiency for 61 countries. Furthermore, we examine the environmental Kuznets relationship between environmental efficiency and GDP per capita and 'pollution haven hypothesis' as well. This paper implies that trade-related variables such as trade composition, the share of polluting exports and openness of a country are important determinants of environmental efficiency and especially, we confirmed existence of 'environmental Kuznets curve' but could not accept 'pollution haven hypothesis' in that 'foreign direct investment (FDI)' improves the environmental performance of pensioner nations.

• The KIPS Transactions:PartB
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• v.10B no.3
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• pp.297-304
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• 2003

Nowdays, with the explosive growth of the web information, web users Increase requests of systems which collect and analyze web pages that are relevant. The systems which were develop to solve the request were used clustering methods to improve the duality of information. Clustering is defining inter relationship of unordered data and grouping data systematically. The systems using clustering provide the grouped information to the users. So, they understand the information efficiently. We proposed a hybrid clustering method to cluster a large quantity of data efficiently. By that method, We generate initial clusters using COBWEB Algorithm and refine them using Ezioni Algorithm. This paper adds two ideas in prior hybrid clustering method to increment accuracy and efficiency of clusters. Firstly, we propose the clustering method considering weight of attributes of data. Second, we redefine evaluation functions which generate initial clusters to increase efficiency in clustering. Clustering method proposed in this paper processes a large quantity of data and diminish of dependancy on sequence of input of data. So the clusters are useful to make user profiles in high quality. Ultimately, we will show that the proposed clustering method outperforms the pervious clustering method in the aspect of precision and execution speed.

• Journal of the Korean Society for Library and Information Science
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• v.49 no.3
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• pp.437-456
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• 2015

This study aims to compare the retention efficiency of library materials of Automated Storage and Retrieval System(AS/RS) revealed by the literature review to other types of book stacks. Domestic and foreign academic libraries adopted AS/RS as part of a plan to improve the retention efficiency. Literature review reveals that in general, AS/RS is better in the retention efficiency in compare to other types of book stacks. This study compared the amount of library materials stored by the AS/RS of S University Library to the general book stack and the fixed-type and the mobile rack-type of virtual book stacks. The study reveals that AS/RS is up to 6 times more efficient than general book stacks, up to 3.61 times more efficient than fixed-type book stacks and up to 1.45 times more efficient than mobile rack-type book stacks. However, the study claims that the retention efficiency of library materials of AS/RS is lower than what is known.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.18 no.6A
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• pp.3-15
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• 2008

In this paper we study exponentiation in finite fields $F{_p}{^{k}}$(k is odd) with very special exponents such as they occur in algorithms for computing square roots. Our algorithmic approach improves the corresponding exponentiation independent of the characteristic of $F{_p}{^{k}}$. To the best of our knowledge, it is the first major improvement to the Tonelli-Shanks algorithm, for example, the number of multiplications can be reduced to at least 60% on average when $p{\equiv}1$ (mod 16). Several numerical examples are given that show the speed-up of the proposed methods.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.35 no.5
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• pp.267-275
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• 2022

Using a nonconforming mesh in enrichment methods results in several numerical issues induced by discontinuities and singularities found within the solution spaces, including the computational overhead during integration. In this study, we present a novel enrichment technique based on the selective expansion technique of moment fitting (Düster and Allix, 2020). In particular, two modifications are proposed to address the inefficiency during the integration process. First, a feedforward artificial neural network is introduced to correlate the implicit functions and integration moments. Through numerical examples, it is shown that the efficiency of the method is greatly improved when compared with existing expansion techniques, whereas the solution accuracy is maintained. Additionally, the finite element and domain representation grids are separated, which in turn improves the solution accuracy even for coarse mesh conditions.

• Proceedings of the Korea Water Resources Association Conference
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• 2020.06a
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• pp.241-241
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• 2020

축산물의 수요가 증가함에 따라 가축의 사육규모 및 두수도 증가하여 가축분뇨의 발생량이 증가한다. 가축분뇨는 일반하수에 비해 고농도의 유기물, 질소, 인 등의 오염물질이 포함되어 있다. 적절한 처리 없이 하수처리장 및 수계로 유입될 경우 하수처리장 처리 효율에 영향을 미치거나 부영양화 등 다양한 문제를 야기 시킬 수 있다. 이러한 문제를 해결하기 위해 아질산화 반응을 이용하는 다양한 공정들이 연구되고 있다. 아질산화 반응은 완전 질산화 반응에 비해 질산화 단계에서 약 25%의 산소요구량이 절감되고, 탈질 단계에서 약 40%의 탄소원이 절감되는 경제적 장점이 있기 때문이다. 본 연구에서는 부피 8L의 실험실 규모 아질산화 반응조 원통형 아크릴로 제작되었고, 서울 A하수처리장 미생물을 채취하여 사용했다. 또한 SRT의 영향을 살펴보기 위하여 35℃ 동일 온도를 유지했다. 반응조 슬러지 반송 및 폐기가 없는 완전 혼합 반응조로 SRT와 HRT가 동일하게 운전하는 방법을 사용하여 SRT를 조절하는 방식으로 운전했다. SRT의 경우 8일, 6일, 4일, 2일의 변경조건을 통해서 차이를 살펴보았다. Ammonia Removal Rate(%)의 경우 각각 86%, 86%, 87%, 24%의 효율을 보였고, Nitrite Conversion Rate(%)의 경우 각각 10%, 45%, 80%, 41%의 효율을 보였다. 35℃ 실험실 규모 반응조에서 가축분뇨 유입 원수의 아질산화 반응을 유도하기 위해서는 SRT운전 조건은 4~8일, 고효율의 아질산화 반응을 유도하기 위해서는 SRT 4일 조건이 적합하다고 판단된다. 본 연구는 실제 가축분뇨 처리 효율 상승을 위해서 아질산화 공법을 도입할 경우 중요한 자료로 이용 가능할 것으로 판단된다.

• Journal of the Korea Society of Computer and Information
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• v.29 no.9
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• pp.169-177
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• 2024

Industrial Wireless Sensor Network (IWSN) is a key feature of Industrial IoT that enables industrial automation through process monitoring and control by connecting industrial equipment such as sensors, robots, and machines wirelessly, and must support the strict requirements of modern industrial environments such as real-time, reliability, and energy efficiency. To achieve these goals, IWSN uses reliable communication methods such as multipath routing, fixed redundant resource allocation, and non-contention-based scheduling. However, the issue of wasting redundant resources that are not utilized for communication degrades not only the efficiency of limited radio resources but also the energy efficiency. In this paper, we propose a scheme that utilizes reinforcement learning in communication scheduling to periodically identify unused wireless resources and reallocate them to save energy consumption of the entire industrial network. The experimental performance evaluation shows that the proposed approach achieves about 30% improvement of resource efficiency in scheduling compared to the existing method while supporting high reliability. In addition, the energy efficiency and latency are improbed by more than 21% and 38%, respectively, by reducing unnecessary communication.

• Journal of the Korean Institute of Gas
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• v.15 no.6
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• pp.1-7
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• 2011

The Measurement of risk parameter in city-gas equipments have been measured and confirmed by human, and evolved into remote monitoring system using wireless communication. Furthermore, domestic and international industry increase the efficiency of management, which can develop remote monitoring and control system using wireless communication. However, Those wireless system might be decrease the efficiency and ease because of connecting PDA and lap-top using wire-cable when data have checked immediately from outside. This paper is able to improve efficiency of safety management on city-gas equipments by developing mobile city-gas safety management system on AR.

• Proceedings of the Korean Information Science Society Conference
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• 2012.06a
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• pp.128-130
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• 2012

본 논문은 교육 현장의 전산 기자재 관리의 비효율성을 바꿔나가고 새로운 변화에 적응력을 키워나가는 취지에서 접근하였다. 현재 각 학교에는 교원 1인당 1 PC가 보급되어 있으며, 네트워크 환경도 잘 구성되어 있다. 이러한 환경을 기초로 본 논문에서는 학교에서 작성 되고 있는 관리 대장을 전자 문서화함으로써, 관리 대장의 검색, 생성, 삭제, 삽입, 변환 등에 따른 업무 비효율성을 최소화하였다. 본 연구에서는 전자 문서화 시스템의 서버 프로그램으로 RW-APM을 사용하였으며, 여러 가지 대화형 게시판과 SMS를 이용한 관리자 호출을 통해 관리자뿐 아니라 일반 사용자들도 시스템과 학교 장비의 문제점에 대해 의견을 나눌 수 있도록 하였다. 본 연구에서 개발된 전산 기자재 관리 대장 시스템은 여러 실무 담당자들의 의견을 수용함으로써 교육 현장에 최적화 된 환경을 제공하기 위해 노력하였다. 이러한 시스템을 확장하여 활용한다면 교육 지원 활동에 대한 효율성을 높일 수 있으며, 이는 교사와 학생들의 교육 활동에 긍정적인 효과를 줄 것으로 기대된다.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• 2010.10a
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• pp.110-111
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• 2010

Recently, container terminal managers make an experiment on the double cycle and dual cycle operation, which ship loading and unloading were carried out simultaneously, for increasing the productivity of quay side. However, if we make an experiment on dual cycle operation in a real job site, the efficiency is poor up to terminal operation method as YTs(Yard Tractors)' allocation method, QCs(Quay Cranes)' working speed, and position of export containers. So, this paper examine more efficient terminal operation method, when terminal uses dual cycle operation.