• Journal of Electrical Engineering and Technology
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• 제11권4호
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• pp.839-847
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• 2016

Energy recovery battery testing systems (ERBTS) have been widely used in battery manufactures. All the ERBTS are connected in parallel which forms a special and complicated micro-grid system, which has the shortcomings of low energy recovery efficiency, complex grid-connected control algorithms issues for islanded detection, and complicated power circuit topology issues. To solve those shortcomings, a DC micro-grid system is proposed, the released testing energy has the priority to be reutilized between various testing system within the local grid, Compared to conventional scheme, the proposed system has the merits of a simplified power circuit topology, no needs for synchronous control, and much higher testing efficiency. The testing energy can be cycle-used inside the local micro-grid. The additional energy can be recovered to AC-grid. Numerous experimental comparison results between conventional and proposed scheme are provided to demonstrate the validity and effectiveness of the proposed technique.

• Journal of Multimedia Information System
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• 제6권3호
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• pp.131-138
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• 2019

With the rapid evolution of communication technology, it became possible to overcome the spatial and temporal limitations faced by humans to some extent. Furthermore, the quality of personal life was revolutionized with the emergence of the personal communication device commonly known as the smart phone. In terms of defense networks, however, due to restrictions from the military and security perspectives, the use of smart phones has been prohibited and controlled in the army; thus, they are not being used for any defense strategy purposes as yet. Despite the current consideration of smart phones for military communication, due to the difficulties of network configuration and the high cost of the necessary communication devices, the main tools of communication between soldiers are limited to the use of flag, voice or hand signals, which are all very primitive. Although these primitive tools can be very effective in certain cases, they cannot overcome temporal and spatial limitations. Likewise, depending on the level of the communication skills of each individual, communication efficiency can vary significantly. As the term of military service continues to be shortened, however, types of communication of varying efficiency depending on the levels of skills of each individual newly added to the military is not desirable at all. To address this problem, it is essential to prepare an intuitive network configuration that facilitates use by soldiers in a short period of time by easily configuring the strategy network at a low cost while maintaining its security. Therefore, in this article, the author proposes a Zigbee-based local strategic network by using Opnet and performs a simulation accordingly.

• The Journal of Asian Finance, Economics and Business
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• 제8권4호
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• pp.33-42
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• 2021

This study aims to investigate the relationship between foreign direct investment (FDI) and economic growth at the provincial level by using time-series data in Binh Dinh from 1997 to 2019. We applied the quantitative approaches Vector Autoregression (VAR) and Autoregressive Distributed Lags (ARDL) in the model, which includes economic growth, real foreign direct investment capital, ratio of trained workers, and infrastructure. The results show that all these variables are stationary at the first difference. In ARDL analysis, we found that the economic growth positively affects FDI attraction. However, there is no evidence of the effect of FDI on economic growth in the condition of low capital implemented. Moreover, findings also show that the impact of FDI on economic growth is influenced by two factors: infrastructure and human capital. The lack of human capital, which is trained personnel and infrastructure, is the main barrier hindering and inhibiting FDI's contribution to local economic growth. In order to improve the efficiency of FDI on economic growth in the future, it is suggested that the Binh Dinh government should have proper policies in terms of the infrastructure, the human capital investment. They would allow Binh Dinh to enhance the capital absorptive capacity and capital efficiency.

• 인터넷정보학회논문지
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• 제13권4호
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• pp.83-93
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• 2012

HTML5는 특정 브라우저에 종속되지 않으며 상호 운용성을 고려하는 동시에 기존 HTML과도 하위 호환성을 갖도록 개발되어 현재 표준화 작업이 진행 중인 새로운 웹 표준이다. 이는 최근 스마트폰 시장의 활성화와 함께 모바일 웹 환경에서 다양한 플랫폼에 공통적으로 적용될 수 있다는 특징으로 인해 관심을 모으고 있다. 특히 HTML5에서 새롭게 추가되는 기능들 중 하나인 Local Storage는 인터넷 접속이 끊긴 상태에서도 웹 어플리케이션의 동작을 가능하게 하는 오프라인 기능을 지원하며 이는 서버와 독립적인 웹 어플리케이션 개발이 가능하게 한다. 그러나 현재 Local Storage는 평문의 데이터를 Client-side에 아무런 보안조치 없이 저장하기 때문에 쿠키와 같은 기존의 클라이언트 측 저장소가 갖는 보안 위협에 그대로 노출되어 보안상 안전하지 않다. 본 연구에서는 Local Storage에 데이터를 저장할 때 성능부하를 최소화 하면서 데이터의 안전한 저장 및 사용을 가능하게 하는 방법을 제안한다. 제안하는 방법은 기존 Local Storage 표준 API와 암호 기능을 제공하는 모듈을 이용하여 안전한 사용자 정보 저장을 지원한다. 또한 제안하는 방법을 실제 구현코드를 바탕으로 성능을 측정하여 효율성을 입증한다.

• International Journal of Air-Conditioning and Refrigeration
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• 제7권
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• pp.101-111
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• 1999

The effect of various conditions of frosting and defrosting on the defrosting behavior of a fin-tube heat exchanger has been examined experimentally. An electric heater is used for defrosting in a fin-tube heat exchanger. There are several local maxima in the water draining rate. The amount of residual water on the heat exchanger after completion of defrosting is kept constant due to surface tension on the heat exchanger. Without considering degradation of the thermal performance due to the frosting, the defrosting efficiency is improved with increasing amount of frost irrespective of the frosting condition. The defrosting behavior is affected by frosting density as well as frost accumulation, both of which vary with the experimental operating conditions. The heat loss to the surrounding air decreases, and melting and defrosting efficiencies show high values with decreasing heat input.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제10권3호
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• pp.996-1015
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• 2016

A common concern regarding cooperative spectrum sensing (CSS) schemes is the occupied bandwidth and the energy consumption during the transmissions of sensing information to the fusion center over the reporting control channels. This concern is intensified if the number of cooperating secondary users in the network is large. This article presents a new fusion strategy for a CSS scheme, aiming at increasing the energy efficiency of a recently proposed bandwidth-efficient fusion scheme. Analytical results and computational simulations unveil a high increase in energy efficiency when compared with the original approach, yet achieving better performances in some situations, and lower implementation complexity.

• Journal of Communications and Networks
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• 제18권6호
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• pp.873-883
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• 2016

In this paper, we focus on maximizing weighted sum energy efficiency (EE) for a multi-cell multi-user channel. In order to solve this non-convex problem, we first decompose the original problem into a sequence of parallel subproblems which can optimized separately. For each subproblem, a base station employs dirty paper coding to maximize the EE for users within a cell while regulating interference induced to other cells. Since each subproblem can be transformed to a convex multiple-access channel problem, the proposed method provides a closed-form solution for power allocation. Then, based on the derived optimal covariance matrix for each subproblem, a local optimal solution is obtained to maximize the sum EE. Finally, simulation results show that our algorithm based on non-linear precoding achieves about 20 percent performance gains over the conventional linear precoding method.

• 한국도서관정보학회지
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• 제40권2호
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• pp.491-514
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• 2009

최근 문화서비스에 대한 수요 확대와 지역 문화 활성화를 위해 공공도서관을 확충할 계획이다. 하지만 대규모 투자비의 비가역성과 한정된 자원의 효율적 배분과 활용을 위해 현재 운영 중인 도서관에 대한 체계적이고 과학적인 효율성 분석이 선행되어야 한다. 따라서 본 연구는 Clustering DEA/AHP모형을 활용하여 전국 공공도서관 565곳의 상대적 효율성을 분석하였다. 분석 결과, 전국 공공도서관은 세 그룹으로 분류되었으며, 대형 도서관이 속한 Group 1의 평균 효율성은 0.89, 중형도서관이 속한 Group 2의 평균 효율성은 0.72, 소형도서관이 속한 Group 3의 평균 효율성은 0.60으로 평가되었다.

• 한국환경복원기술학회지
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• 제9권5호
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• pp.1-9
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• 2006

The purpose of this study is to make a design guideline in designing constructed wetland which can treat water quality both of point and nonpoint source water pollution. It focuses on structural aspects of two case studies of constructed wetland applying SSB(Sustainable Structured wetland Biotope) system in Korea. The constructed wetland of Lake Ju-am which was constructed in 2002 by Environmental Management Corporation, was designed by applying SSB system. It shows higher removal efficiency than expected - 56% of BOD removal efficiency, 60% of T-N removal, and 76% of T-P removal efficiency. In two cases, total wetland areal extents were calculated referred to treatment efficiency. The system is consist of micro-cell structures : inflow channel, forebay, multiple wetland cells and micro-pool. When designing constructed wetland appropriate in local area, the total organic system of vertical and horizontal structure : geology, hydrology, land use, and ecological surroundings of the sites should be considered totally.

• The Journal of Asian Finance, Economics and Business
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• 제10권2호
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• pp.333-341
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• 2023

This study investigates the impact of capital adequacy and operating efficiency on the performance of Saudi banks. In the first part, the study includes a brief introduction focused on the impact of capital adequacy and operating efficiency on the performance of banks. In the second part, a literature review examined various studies on the impact of capital adequacy and operating efficiency on banks' performance. The study methodology was presented in the third part, based on a sample that included all local Saudi banks from 2010 to 2021, using a study model to answer the study hypotheses. The results of the panel data regression indicated that CAR had a negative and significant effect on ROA and ROE but a negative and non-significant effect on NIM. CIR has a negative and significant effect on ROA, ROE, and NIM, while SIZE, LTD, and MS have a positive and significant effect on ROA, ROE, and NIM. Elimination of defects has no significant effect on return on assets, return on equity, and the NIF. But CR has no significant effect on ROA and ROE but has a positive and significant effect on NIM.