• KSII Transactions on Internet and Information Systems (TIIS)
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• 제6권4호
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• pp.1076-1089
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• 2012

Home automation networks are good environments for merging sensor networks and consumer electronics technologies. It is very important to reduce the energy consumption of each sensor node because sensor nodes operate with limited power based on a battery that cannot be easily replaced. One of the primary mechanisms for achieving low energy operation in energy-constrained wireless sensor networks is the duty-cycle operation, but this operation has several problems. For example, unnecessary energy consumption occurs during synchronization between transmission schedules and sleep schedules. In addition, a low duty-cycle usually causes more performance degradation, if the network becomes congested. Therefore, an appropriate control scheme is required to solve these problems. In this paper, we propose UDC (Unsynchronized Duty-cycle Control), which prevents energy waste caused by unnecessary preamble transmission and avoids congestion using duty-cycle adjustment. In addition, the scheme adjusts the starting point of the duty-cycle in order to reduce sleep delay. Our simulation results show that UDC improves the reliability and energy efficiency while reducing the end-to-end delay of the unsynchronized duty-cycled MAC (Media Access Control) protocol in sensor-based home automation networks.

• 정보교육학회논문지
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• 제18권1호
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• pp.75-87
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• 2014

이 연구는 스마트러닝을 위한 교수학습 도구로서 스마트패드를 활용한 수업의 교육적 유용성, 운영상 문제점을 질적 분석을 통해 탐색하고자 하였다. 연구대상은 스마트 클래스가 구축된 수도권 D초등학교 4학년, 5학년 2개 학급이었으며, 이들을 대상으로 수업을 촬영한 뒤 수업활동을 분석하였고 수업에 참여한 교사 2명과 학생 6명을 대상으로 심층 인터뷰를 실시하였다. 관찰한 수업내용과 인터뷰 자료들은 근거이론에 기반한 코딩방법을 사용하여 범주화 과정을 거쳤으며, 자료분석 도구로는 Nvivo 8.0을 사용하였다. 연구 결과 스마트패드 활용수업은 협업과 상호작용 촉진, 다양한 자료와 SNS의 효과적 사용, 수업집중도 향상, 기기 대기시간 단축 등과 같은 유용성이 있는 반면, 학습지원도구의 부족 및 실천모형 부재로 인한 수업진행의 어려움, 기능숙달에 과다한 시간의 투입, 활동에 비해 낮은 학습효과, 수업몰입의 방해 등과 같은 문제점들이 있는 것으로 나타났다. 끝으로, 향후 스마트패드 활용수업의 효과적 활용을 위한 실천과제들이 제안되었다.

• 한국융합학회논문지
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• 제10권9호
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• pp.265-272
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• 2019

본 연구는 우리가 일상에서 생각하는 '빈곤'은 과연 무엇인가에서 출발하였다. 특히 본 연구는 개인적인 주관적 의견을 살펴보기 위하여 주관성연구방법인 'Q방법'을 활용하여 빈곤에 대한 인식을 유형화하였다. 분석결과 다음과 같이 4개의 유형으로 정의되었다. 은 "Retraction type"으로, 빈곤이란 'Retraction', 'Individual Effort Problem', 'Social Structure Problem', 'low status', 'Laziness' 등으로 '되물림의 문제'임을 강조하였다. 는 'Individual Effort Problem', 'Laziness', 'Incompetence', 'starvation' 등을 강조하고 있어, "Individual Problem type"으로 명명하였다. 은 'The food and shelter problem', 'starvation', 'Laziness', 'No Money' 등의 삶의 기본적인 요소인 의식주문제를 강조하고 있어, "Basic Problem type"으로 명명하였다. 는 "Resource Distribution Problem type"으로 사회의 구조적인 문제에 따른 '자원분배의 문제'를 강조하고 있는 것으로 나타났다. 본 연구는 주관성연구방법을 활용하여 21세기 빈곤에 대한 인식을 유형화하였으며, 이에 대한 일반화를 위해서 향후 본 연구에서 출발하여 실증연구로의 융합적 확장연구를 기대한다.

• Agribusiness and Information Management
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• 제9권1호
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• pp.7-17
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• 2017

Agricultural water management has gained enormous attention in the developing world to alleviate poverty, reduce hunger and conserve ecosystems in small-scale production systems of resource-poor farmers. The story of food security in the $21^{st}$ century in India is likely t o be closely linked to the story of water security. Today, the water resource is under severe threat. The past experiences in India in general and in Andhra Pradesh in particular, indicated inappropriate management of irrigation has led to severe problems like excessive water depletion, reduction in water quality, water logging, salinization, marked reduction in the annual discharge of some of the rivers, lowering of ground water tables due to pumping at unsustainable rates, intrusion of salt water in some coastal areas etc. Considering the importance of irrigation water resource efficiency, Krishna Western Delta (KWD) of Andhra Pradesh was purposively selected for this in depth study, as the farming community in this area are severely affected due to severe soil salinity and water logging problems and hence, adoption of different water saving crop production technologies deserve special mention. It is quite disappointing that, canals, tube wells and filter points and other wells could not contribute much to the irrigated area in KWD. Due to less contribution from these sources, the net area irrigated also showed declining growth at a rate of -6.15 per cent. Regarding paddy production, both SRI and semi-dry cultivation technologies involves less irrigation cost (Rs. 2475.21/ha and Rs. 3248.15/ha respectively) when compared to transplanted technology (Rs. 4321.58/ha). The share of irrigation cost in Total Operational Cost (TOC) was highest for transplanted technology of paddy (11.06%) followed by semi-dry technology (10.85%) and SRI technology (6.21%). The increased yield and declined cost of cultivation of paddy in SRI and semi-dry production technologies respectively were mainly responsible for the low cost of production of paddy in SRI (Rs. 495.22/qtl) and semi-dry (Rs. 532.81/qtl) technologies over transplanted technology (Rs. 574.93/qtl). This clearly indicates that, by less water usage, paddy returns can be boosted by adopting SRI and semi-dry production technologies. Both the system-level and field-level interventions should be addressed to solve the issues/problems of water management. The enabling environment, institutional roles and functions and management instruments are posing favourable picture for executing the water management interventions in the State of Andhra Pradesh in general and in KWD in particular. This facilitates the farming community to harvest good crop per unit of water resource used in the production programme. To achieve better results, the Farmers' Organizations, Water Users Associations, Department of Irrigation etc., will have to aim at improving productivity per unit of water drop used and this must be supported through system-wide enhancement of water delivery systems and decision support tools to assist farmers in optimizing the allocation of limited water among crops, selection of crops based on farming situations, and adoption of appropriate alternative crops in drought years.

• International Journal of Contents
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• 제2권1호
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• pp.39-44
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• 2006

Load sharing is a critical resource in computer system. In sender-initiated load sharing algorithms, the sender continues to send unnecessary request messages for load transfer until a receiver is found while the system load is heavy. Meanwhile, in the receiver initiated load sharing algorithms, the receiver continues to send an unnecessary request message for load acquisition until a sender is found while the system load is light. These unnecessary request messages result in inefficient communications, low CPU utilization, and low system throughput in distributed systems. To solve these problems, we propose a genetic algorithm based approach for improved sender-initiated and receiver-initiated load sharing in distributed systems. And we expand this algorithm to an adaptive load sharing algorithm. Compared with the conventional sender-initiated and receiver-initiated algorithms, the proposed algorithm decreases the response time and task processing time.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제9권10호
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• pp.3921-3944
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• 2015

Currently Energy-Saving (ES) methods in cellular networks could be improved, as compensation method for irregular Base Station (BS) deployment is not effective, most regional ES algorithm is complex, and performance decline caused by ES action is not evaluated well. To resolve above issues, a low-complexity energy efficient BS cooperation mechanism for Long Time Evolution (LTE) networks is proposed. The mechanism firstly models the ES optimization problem with coverage, resource, power and Quality of Service (QoS) constraints. To resolve the problem with low complexity, it is decomposed into two sub-problems: BS Mode Determination (BMD) problem and User Association Optimization (UAO) problem. To resolve BMD, regional dynamic multi-stage algorithms with BS cooperation pair taking account of load and geographic topology is analyzed. And then a distributed heuristic algorithm guaranteeing user QoS is adopted to resolve UAO. The mechanism is simulated under four LTE scenarios. Comparing to other algorithms, results show that the mechanism can obtain better energy efficiency with acceptable coverage, throughput, and QoS performance.

• 한국정보과학회논문지:정보통신
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• 제30권2호
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• pp.143-154
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• 2003

분산 이동 시스템은 단순한 통신 기능에서 작업 흐름 관리, 화상회의, 복제 데이터의 관리, 자원 할당 둥의 서비스를 제공하는 시스템으로 급속히 확대.발전하고 있으며, 이러한 서비스를 제공하는 어플리케이션들은 사용자의 요구를 반영하기 위해 메시지를 인과적 순서로 전달해야 한다. 인과적 메시지 전달을 제공하는 기존의 방법들은 많은 피기백(piggyback) 정보로 인한 통신 오버헤드 혹은 어플리케이션으로 전달하는 메시지의 지연, 이동 호스트의 증가에 대한 확장성, 이동 호스트가 계산의 대부분을 수행하는 둥의 문제점이 있다. 이 논문은 기지국과 이동 호스트 사이의 종속 정보 행렬을 기지국이 유지하며, 즉각 선행자 메시지(immediate predecessor message)에 대한 종속 정보만을 각 메시지에 피기백 하는 방법을 통해 기존 기법의 문제점을 해결하는 효율적인 인과적 메시지 전달 기법을 제안한다. 제안하는 알고리즘은 이전의 알고리즘들과 비교해서 낮은 메시지 오버헤드를 가지며, 메시지를 전달할 때 불필요한 지연(inhibition)을 발생시키지 않는다. 또한 기지국에서 알고리즘의 대부분을 수행하도록 함으로써 이동 호스트의 자원제약과 무선 통신의 낮은 대역폭을 고려하고, 이동 호스트 단위로 인과적 메시지 전달을 이행함으로써 발생하는 처리 지연(processing delay)을 줄여준다.

• 한국정보통신학회논문지
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• 제17권12호
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• pp.2769-2774
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• 2013

유비쿼터스 센서 네트워크(Ubiquitous Sensor Network) 기술의 핵심은 저전력 무선 통신기술과 효율적 라우팅을 위한 적절한 자원할당 기술이다. 센서 네트워크에서 효율적인 자원할당을 위해서는 서비스에 따른 차별화된 자원할당 방식이 필요하다. 이를 위하여, 본 논문에서는 유선망에 사용되는 PQ(Priority Queue)와 WRR의 단점을 보완하여 USN에 적용이 가능한 스케줄러 알고리즘을 제안한다. 제안된 알고리즘은 센서 네트워크에서 각 클래스의 큐 상태를 체크하여 퍼지 이론을 적용한 제어 정책에 따라 WRR 스케쥴러의 가중치를 동적으로 할당하였다. 시뮬레이션 결과 제안된 알고리즘은 EF 클래스의 패킷 손실률에서 WRR 스케쥴러 방식보다 평균 6.5% 향상되었으며, AF4 클래스에서는 PQ 방식보다 평균 45% 향상된 결과를 보였다.

• 가족자원경영과 정책
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• 제16권1호
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• pp.123-148
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• 2012

The main objective of this study was to investigate how people prepare for old age by looking at financial statements from single-person households in Gyeonggi province; the policy implications regarding low fertility and population aging are considered. The subjects were members of 600 households who were aged 26 to 44 years old and not married. The data were analyzed by t-test, ANOVA, and dichotomous logistic regression using SPSS WIN 12.0. Respondents pointed out that financial problems are the greatest challenges for those facing old age in single-person households; they said that a stable job is the most important factor for secure living. About 57% of household residents responded that they have prepared for retirement, and a majority of them said they hoped to spend their elderly years with a marriage partner. The financial statements from single-person households were inferior to those from other types of households. The assets of single-person household members were less than those of other households. Only 10.5% of respondents have owned homes. The study discusses policy implications for those who want marriage and for those who don't want it. For those who want marriage, job-seeking support was proposed, and for the others, tax deductions and family programs for single-person households were proposed.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제14권4호
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• pp.1520-1542
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• 2020

Traditional software testing typically uses many physical resources to manually build various test environments, resulting in high resource costs and long test time due to limited resources, especially for small enterprises. Cloud computing can provide sufficient low-cost virtual resources to alleviate these problems through the virtualization of physical resources. However, the provision of various test environments and services for implementing software testing rapidly and conveniently based on cloud computing is challenging. This paper proposes a multilayer cloud testing model based on cloud computing and implements a hybrid cloud testing system based on virtual machines (VMs) and networks. This system realizes the automatic and rapid creation of test environments and the remote use of test tools and test services. We conduct experiments on this system and evaluate its applicability in terms of the VM provision time, VM performance and virtual network performance. The experimental results demonstrate that the performance of the VMs and virtual networks is satisfactory and that this system can improve the test efficiency and reduce test costs through rapid virtual resource provision and convenient test services.