• 정보기술과데이타베이스저널
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• 제2권2호
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• pp.25-34
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• 1995

본 논문에서는 멀티미디어 처리를 제공하는 객체지향 데이타베이스 시스템에 관한 기능 시험도구의 설계 전략에 대하여 설명한다. 시험도구의 설계시 시험 데이터베이스의 스키마는 추상화, 상속, 집단화(aggregation) 등의 객체 지향적인 성질을 시험할 수 있도록 하며, 포함되는 인스턴스는 사용자의 이해를 돕기 위해 의미있는 값으로 인위적으로 구성한다. 기능 시험항목은 경계값 분석, 동치 분할 등의 기법을 이용한 블랙박스 시험방법으로 작성되며, 각 시험항목은 서로 독립적으로 구현되어 실행 순서에 영향받지 않도록 한다. 시험항목이 수행된 후에는 성공적인 수행, 제외된 기능, 올바르지 않은 수행 등의 시험결과에 대한 목록이 출력되도록 한다. 이러한 설계 전략에 의하여 UniSQL/X를 위한 기능 시험도구를 C++로 개발하였다. 시험도구의 수행은 스키마의 생성, 인스턴스 삽입, 시험프로그램의 컴파일과 링크, 시험프로그램 실행 및 결과확인, 시험 데이타베이스 제거 순으로 이루어진다. 본 시험도구는 UniSQL/C++의 멤버 함수에 대응하는 90여개의 시험프로그램을 이용하여 140여개의 시험항목을 제공한다.

• 품질경영학회지
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• 제46권2호
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• pp.283-300
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• 2018

Purpose: Since the servant leadership of project managers is seemingly related to the project performance by influencing project team members' positive attitude and behavior, this study attempts to provide empirical evidence for a link between servant leadership and project performance. In addition, the present study investigates the mediating effects of customer satisfaction on the servant leadership-project performance relations. Methods: The data of servant leadership and project performance were collected from 185 project team members of a company providing IT service, and customer satisfaction data were collected from 100 project clients served by the company. Before testing the hypotheses, we calculated aggregation statistics(e.g., $r_{wg}$, ICC(1), and ICC(2)) to ensure appropriate aggregation of servant leadership scores. The statistics confirmed the use of 67 team level servant leadership scores with project performance and customer satisfaction. Results: The results show that servant leadership is significantly related to three project performance measures(perceptions of performance contribution and sales contribution, and actual project profits) in the current team-level sample. Results also indicate that the clients' perception of customer satisfaction shows a mediating effect in the process of servant leadership affecting sales contribution of project performance. Conclusion: The present study empirically confirms that servant leadership plays a major role in enhancing project performance on team level analysis. The results suggest that servant leadership increases customer satisfaction since the project managers serve and care for their team members which translate into effective customer service. Theoretical and practical implications are reviewed, and limitations of the study and suggestions for future research are addressed.

• 한국정보통신학회논문지
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• 제20권11호
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• pp.2187-2192
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• 2016

무선 센서 네트워크의 생존시간을 증가시키기 위하여 중계노드에서의 데이터 병합을 고려한 데이터 중심 라우팅이 필요하다. 본 논문에서는 무선 센서 네트워크에서 센싱 정보의 수집 시간과 노드의 에너지 소비량 간의 트레이드 오프를 고려하여 에너지 소비를 최소화하면서도 빠른 시간 내에 센싱 정보를 수집하는 에너지 효율적인 데이터 중심 라우팅 알고리즘을 제안한다. 제안 하는 라우팅 방식은 먼저 전체 센서 노드 중에서 최대 거리가 최소화가 되도록 만드는 노드를 싱크 노드로 설정한다. 이후 빠른 정보 수집을 위하여 센서 노드와 싱크 노드 간 최대 거리의 증가를 최소화하면서 에너지 소비를 줄이기 위하여 노드간 연결 링크 비용을 최소화하는 방식으로 트리 구조를 확장해나간다. 시뮬레이션 결과, 제안하는 데이터 중심 라우팅 알고리즘은 짧은 정보 수집 시간과 낮은 에너지 소비량을 가지며, 이로 인하여 기존 라우팅 알고리즘 대비 높은 네트워크 에너지 효율을 달성한다.

• 디지털융복합연구
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• 제12권12호
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• pp.323-328
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• 2014

융합망에 사용되는 D-MAC 프로토콜은 사물간 무선링크를 연결하기 위해 설계된 프로토콜이다. 이 프로토콜은 이웃 노드 가운데 로컬 데이터 교환과 수집을 위해 제공되고, 싱크로부터 센서 노드로 제어패킷과 관심 패킷이 분배된다. 본 논문에서는 융합망의 D-MAC 보안 인증 적용 여부에 따른 전력소모 효율성에 대해 분석하였다. 인증기법이 MAC 통신에 적용될 경우, 인증처리 유무에 따라 프리앰블의 에너지 소비 여부가 연관이 된다. 인증이 적용될 경우 서비스 공격에 대응하여 에너지 소비가 감소된다. 향후 보안 인증기법에 관련한 연구를 수행할 계획이다.

• Journal of Electrical Engineering and Technology
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• 제10권3호
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• pp.1319-1327
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• 2015

As wind power farm (WPF) installations continue to grow, monitoring and controlling large-scale WPFs presents new challenges. In this paper, a hierarchical network architecture is proposed in order to provide remote monitoring and control of large-scale WPFs. The network architecture consists of three levels, including the WPF comprised of wind turbines and meteorological towers, local control center (LCC) responsible for remote monitoring and control of wind turbines, and a central control center (CCC) that offers data collection and aggregation of many WPFs. Different scenarios are considered in order to evaluate the performance of the WPF communications network with its hierarchical architecture. The communications network within the WPF is regarded as the local area network (LAN) while the communication among the LCCs and the CCC happens through a wide area network (WAN). We develop a communications network model based on an OPNET modeler, and the network performance is evaluated with respect to the link bandwidth and the end-to-end delay measured for various applications. As a result, this work contributes to the design of communications networks for large-scale WPFs.

• 한국응용약물학회:학술대회논문집
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• 한국응용약물학회 2008년도 Proceedings of the Convention
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• pp.89-99
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• 2008

GPCRs are large families of cell surface receptors that transmit signals through conformational changes upon ligand activation and an interaction with the heterotrimeric G-proteins. GPCRs regulate the cell-signaling pathways and participate in the regulation of physiological processes through the G-proteins defined by their ${\alpha}$ subunits. A family of 20 G protein-coupled receptors (GPCRs) that provide a large class of tractable drug targets for new anti-inflammatory drugs and, in certain instances, for the treatment of the inflammatory indications such as atherosclerosis, rhinitis, asthma, pulmonary disease and arthritis. In view of the important findings showing that $G{\alpha}_{12}/G{\alpha}_{13}$ regulate the various cellular processes such as actin-stress fiber formation, neurite retraction, platelet aggregation, gene induction, and apoptosis, we became interested in whether, after coupling to the activated GPCRs, the G-proteins and their downstream molecules might be involved in the pathologic processes of chronic inflammatory diseases (e.g., liver fibrosis). In this symposium, the possible link of the G-proteins with the pathophysiology will be discussed with the aim of finding potential new drug targets.

• Journal of Communications and Networks
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• 제13권1호
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• pp.17-25
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• 2011

A convergecast is a popular routing scheme in wireless sensor networks (WSNs) in which every sensor node periodically forwards measured data along configured routing paths to a base station (BS). Prolonging lifetimes in energy-limited WSNs is an important issue because the lifetime of a WSN influences on its quality and price. Low-energy adaptive clustering hierarchy (LEACH) was the first attempt at solving this lifetime problem in convergecast WSNs, and it was followed by other solutions including power efficient gathering in sensor information systems (PEGASIS) and power efficient data gathering and aggregation protocol (PEDAP). Our solution-chain routing with even energy consumption (CREEC)-solves this problem by achieving longer average lifetimes using two strategies: i) Maximizing the fairness of energy distribution at every sensor node and ii) running a feedback mechanism that utilizes a preliminary simulation of energy consumption to save energy for depleted Sensor nodes. Simulation results confirm that CREEC outperforms all previous solutions such as LEACH, PEGASIS, PEDAP, and PEDAP-power aware (PA) with respect to the first node death and the average lifetime. CREEC performs very well at all WSN sizes, BS distances and battery capacities with an increased convergecast delay.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제12권5호
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• pp.1973-1991
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• 2018

Multimedia applications over wireless networks have been evolving to augmented reality or virtual reality services. However, a rich data size compared to conventional multimedia services causes bandwidth bottlenecks over wireless networks, which is one of the main reasons why those applications are not used widely. To overcome this limitation, bandwidth aggregation techniques, which exploit a multi-path transmission, have been considered to maximize link utilization. Currently, most of the conventional researches have been focusing on the user end problems to improve the quality of service (QoS) through optimal load distribution. In this paper, we address the joint pricing and load distribution problem for multi-homing in heterogeneous wireless access networks (ANs), considering the interests of both the users and the service providers. Specifically, we consider profit from resource allocation and cost of power consumption expenditure for operation as an utility of each service provider. Here, users decide how much to request the resource and how to split the resource over heterogeneous wireless ANs to minimize their cost while supporting the required QoS. Then, service providers compete with each other by setting the price to maximize their utilities over user reactions. We study the behaviors of users and service providers by analyzing their hierarchical decision-making process as a multileader-, multifollower Stackelberg game. We show that both the user and service provider strategies are closed form solutions. Finally, we discuss how the proposed scheme is well converged to equilibrium points.

• Nuclear Engineering and Technology
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• 제53권6호
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• pp.1979-1990
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• 2021

Evacuation Time Estimate (ETE) can provide decision-makers with a likelihood to implement evacuation of a population with radiation exposure risk by a nuclear power plant. Thus, the ETE is essential for developing an emergency response preparedness. However, studies on ETE have not been conducted adequately in Korea to date. In this study, different cohorts were selected based on assumptions. Existing local data were collected to construct a multi-model network by TSIS-CORSIM code. Furthermore, several links were aggregated to make simple calculations, and post-processing was conducted for dealing with the stochastic property of TSIS-CORSIM. The average speed of each cohort was calculated by the link aggregation and post-processing, and the evacuation time was estimated. As a result, the average cohort-based evacuation time was estimated as 2.4-6.8 h, and the average clearance time from ten simulations in 26 km was calculated as 27.3 h. Through this study, uncertainty factors to ETE results, such as classifying cohorts, degree of model complexity, traffic volume outside of the network, were identified. Various studies related to these factors will be needed to improve ETE's methodology and obtain the reliability of ETE results.

• 대한교통학회지
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• 제34권6호
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• pp.570-579
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• 2016

Stepwise 환승계수(이하 STC)는 환승회수 증가에 따라 환승비용을 실제보다 많게 인식하도록 한다. 통행시간과 최소환승회수 정보를 제공하는 것은 이러한 경향을 감안하는 취지이다. STC가 포함된 경로탐색문제는 비가산성비용을 포함하며 최적조건의 비성립으로 경로열거가 요구된다. 따라서 대중교통망에서 STC를 고려하는 경로탐색에 대한 이론적 검토를 통해서 경로탐색의 실패를 우회하는 방안이 요구된다. 본 연구는 STC가 포함되는 대중교통망에서 확률적 통행배정모형에 대하여 검토한다. 비가산성 경로문제를 완화하는 방안으로 유입링크기반 전체경로삭제기법을 활용하는 방안을 제안한다. 전체경로삭제기법은 출발지에서 도착지까지 서로 상이한 경로의 구성된 가능경로집합을 구축하기 용이하다. STC를 반영한 경로기반 Logit 모형을 대중교통통행배정기법으로 구축한다.