• Journal of Communications and Networks
• /
• 제17권5호
• /
• pp.506-516
• /
• 2015

Wireless sensor networks (WSNs) are generally comprised of densely deployed sensor nodes, which results in highly redundant sensor data transmissions and energy waste. Since the sensor nodes depend on batteries for energy, previous studies have focused on designing energy-efficient medium access control (MAC) protocols to extend the network lifetime. However, the energy-efficient protocols induce an extra end-to-end delay, and therefore recent increase in focus on WSNs has led to timely and reliable communication protocols for mission-critical applications. In this paper, we propose an energy efficient and delay guaranteeing node scheduling scheme inspired by biological systems, which have gained considerable attention as a computing and problem solving technique.With the identification of analogies between cellular signaling systems and WSN systems, we formulate a new mathematical model that considers the networking challenges of WSNs. The proposed bio-inspired algorithm determines the state of the sensor node, as required by each application and as determined by the local environmental conditions and the states of the adjacent nodes. A control analysis shows that the proposed bio-inspired scheme guarantees the system stability by controlling the parameters of each node. Simulation results also indicate that the proposed scheme provides significant energy savings, as well as reliable delay guarantees by controlling the states of the sensor nodes.

• 한국학교보건학회지
• /
• 제21권2호
• /
• pp.23-33
• /
• 2008

Purpose: Internet is one of the essential tools in South Korean adolescent life. Recently, researchers suggest that Internet use is positively associated with teens' mental health problems such as depression and suicide. Thus, this study explored a relationship between Internet use and suicide ideation among South Korean adolescents. Methods:　Secondary data, the three-wave Korean Youth Panel Survey, were analyzed. First, in terms of the levels of Internet use and suicidal ideation, t-test was used for examining a gender difference, and Analysis of Variance were used for examining differences across three points in time(waves 2 - 4). Second, logistic analysis was performed to examine the significant association between Internet use and suicide ideation after controlling for the other factors' effects. In this analysis, Fixed Effect Regression Method(FERM) was incorporated as well. FERM was useful in adjusting for the effects of time-invariant factors even without measuring them. As a result, it was possible to obtain more accurate findings. Results: Adolescent depression was an important factor influencing the association between Internet use and suicide ideation. After controlling for the effect of depression, the relationship between Internet use and suicide ideation was no longer statistically significant. Conclusion:　As a proxy to identify teens who are obsessed with suicide ideation, levels of Internet use do not seem useful. Instead, it is necessary to examine teens' access to websites related to suicide.

• 한국정보통신학회논문지
• /
• 제9권5호
• /
• pp.1039-1044
• /
• 2005

원격 제어 모니터링 시스템을 위한 임베디드 리눅스 시스템의 다중 채널 직렬 장치를 설계하였다. 제안된 장치는 다중 채널 직렬 장치의 효과적인 데이터 처리를 위해 내부에 FIFO, Sate Machine, 인터럽트로 구성되어 있으며 임베디드 리눅스에서 효과적인 디바이스 프로그램을 가능하게 한다. 다중 채널 직렬 장치의 기존의 접근 방식은 개별 직렬 장치를 일일이 접근하고 있으나 본 장치에서는 다중 채널 직렬 장치를 한 개의 직렬 장치로 간주하여 접근하는 것과 같은 효과를 볼 수 있다. 본 장치는 다중 채널 직렬 입출력 구동에 효율적이며 기존의 다중 채널 직렬 장치 보다 접근 속도가 빠르다. 본 장치는 수질 측정과 같은 센서들 사이의 거리가 멀거나 센서와 모니터링 시스템의 사이의 거리가 먼 원격 제어 모니터링에 효과적이다.

• Asian-Australasian Journal of Animal Sciences
• /
• 제14권4호
• /
• pp.467-473
• /
• 2001

The internal humoral factors in the central regulation of dry feed intake during water deprivation in sheep were investigated by measurement of cerebrospinal fluid (CSF) constituents. Five animals were fed dried alfalfa chaff for 2 hours once a day. Sheep in the water deprivation treatment were deprived of water for 28 hours, while the sheep in the control treatment were given free access to water. During the first hour of the 2 hour feeding period, a rapid reduction in blood volume occured in both treatments (water deprivation and free access to water). The CSF concentrations of Na, Cl and osmolality during the second hour of the 2 hour feeding period in both treatments were greater (p<0.01) than those during the first hour. The drinking behaviors in sheep were concentrated during the second hour of the 2 hour feeding period in periods of free access to water. Water intake during feeding in periods of free access to water was 1110 ml/2 h. The levels of increase in CSF osmolality with feeding during water deprivation were greater (p<0.01) than during periods of free access to water. The changes in CSF osmolality with feeding during water deprivation produced more vigorous thirst sensations in the brain compared to during periods of free access to water. The eating rates for the first hour of the allotted 2 hour feeding period were the same under both treatments. However, the eating rates for the second hour during water deprivation periods decreased significantly (p<0.05) compared to those during periods of free access to water. The decreased eating rates for the second hour during water deprivation may be due to the vigorous thirst sensations produced in the brain. The results suggest that the increase in CSF osmolality with feeding during water deprivation acts as a thirst and satiety factor in brain mechanisms controlling feeding to decrease dry feed intake in water-deprived sheep.

• 한국정밀공학회지
• /
• 제31권7호
• /
• pp.585-590
• /
• 2014

Recently, monitoring systems, such as POP, take a core role in scheduling or planning of manufacturing facilities for production, maintenance, and so on. Such monitoring systems require functionalities for real-time parameter monitoring and controlling to maximize efficiency of facilities. However, vendors usually do not provide internal communication protocols or interface to access the machine controller. Therefore, the values of parameters related to machine operations and controls cannot be easily accessed from external devices. In this paper, we propose an interface methodology for a real-time monitoring and controlling of injection molding machine parameters such as user input parameters, embedded sensor data and injection molding status information.

• 한국인터넷방송통신학회논문지
• /
• 제18권5호
• /
• pp.131-140
• /
• 2018

방송 스케줄링 기법은 데이터 방송 시스템의 성능을 향상시키기 위해서 필수적인 기술이다. 본 논문은 질의의 응답시간을 줄이기 위하여 다중 채널을 통한 데이터 방송의 문제를 연구하여 HDAMA로 명명된 새로운 하이브리드 데이터 방송 스케줄링 기법을 제안한다. 제안된 기법은 푸쉬기반 방송과 풀기반 방송의 장점을 결합하는 전략을 채택한다. HDAMA는 다중 데이터 질의의 특성을 반영하여 액세스 확률의 영향력을 적절하게 제어할 수 있고, 풀 데이터를 비교적 적시에 방송할 수 있기 때문에 질의 응답시간의 성능을 향상시킬 수 있다. 제안된 기법의 성능 평가를 위해 시뮬레이션이 수행되었다. 실험 결과에 따르면, 평균 응답시간의 성능에서 HDAMA는 다른 기법보다 우수한 성능을 보인다.

• 산업경영시스템학회지
• /
• 제38권4호
• /
• pp.212-225
• /
• 2015

UAV (Unmanned Aerial Vehicle), the pilotless plane or drone, draws researchers' attention at these days for its extended use to various area. The research was initiated for military use of the UAV, but the area of applicable field is extended to surveillance, communication, and even delivery for commercial use. As increasing the interest in UAV, the needs of research for operating the flying object which is not directly visible when it conducts a certain mission to remote place is obviously grown as much as developing high performance pilotless plane is required. One of the project supported by government is related to the use of UAV for logistics fields and controlling UAV to deliver the certain items to isolated or not-easy-to-access place is one of the important issues. At the initial stage of the project, the previous researches for controlling UAV need to be organized to understand current state of art in local researches. Thus, this study is one of the steps to develop the unmanned system for using in military or commercial. Specifically, we focused on reviewing the approaches of controlling UAV from origination to destination in previous in-country researches because the delivery involves the routing planning and the efficient and effective routing plan is critical to success to delivery mission using UAV. This routing plan includes the method to avoid the obstacles and reach the final destination without a crash. This research also present the classification and categorization of the papers and it could guide the researchers, who conduct researches and explore in comparable fields, to catch the current address of the research.

• KSII Transactions on Internet and Information Systems (TIIS)
• /
• 제6권2호
• /
• pp.498-514
• /
• 2012

Machine to machine (M2M) communications is the hottest issue in the standardization and industry area, it is also defined as machine-type communication (MTC) in release 10 of the 3rd Generation Partnership Project (3GPP). Recently, most research have focused on congestion control, sensing, computing, and controlling technologies and resource management etc., but there are few studies on security aspects. In this paper, we first introduce the threats that exist in M2M system and corresponding solutions according to 3GPP. In addition, we present several new security issues including group access authentication, multiparty authentication and data authentication, and propose corresponding solutions through modifying existing authentication protocols and cryptographic algorithms, such as group authentication and key agreement protocol used to solve group access authentication of M2M, proxy signature for M2M system to tackle authentication issue among multiple entities and aggregate signature used to resolve security of small data transmission in M2M communications.

• 환경생물
• /
• 제22권2호
• /
• pp.259-264
• /
• 2004

생물다양성협약에서 국가 생물유전자원의 주권을 인정함에 따라 국가별로 생물유전자원의 관리에 대한 법적인 체계를 갖추어야 할 시기가 도래하였다. 생물유전자원의 관리에 있어서 가장 중요한 단계가 접근과 생물자원에서 파생하는 이익공유이다. 제6차 생물다양성협약 당사국 회의에서 채택된 본 지침은 접근과 이익공유과정에서 필수적인 상호합의조건과 사전통보승인제도를 포함하고 있다. 상호합의조건은 원산국과 이용 실체간의 계약 협정이고 사전통보승인제도는 생물자원 접근 전에 승인하는 것과 관련된 생물유전자원 관련 특이 제도이다. 아울러 국가연락기관과 국가책임기관의 책임, 유인조치 등에 관한 내용을 포함하고 있다. 우리나라의 생물유전자원 접근 관련 법률을 분석해 볼 때, 생물유전자원에 대한 이익공유와 특허권 문제가 고려되어 있지 않다. 생물유전자원 접근규제와 체계적인 관리를 위해서 정보 유용화 및 공개, 지적재산권을 조절하는 기관과 기타 이해관계자의 조정을 위한 국가관할기관의 역할이 중요하다. 다만, 이런 국가적 접근규제가 생물다양성관련 연구를 저해하지 않아야 하고 생물다양성협약의 목적인 생물다양성의 보존과 지속 가능한 이용에 위배되어서는 안 될 것이다.

• 한국재료학회지
• /
• 제32권9호
• /
• pp.384-390
• /
• 2022

A spin coating process for RRAM, which is a TiN/TiO₂/FTO structure based on a PTC sol solution, was developed in this laboratory, a method which enables low-temperature and eco-friendly manufacturing. The RRAM corresponds to an OxRAM that operates through the formation and extinction of conductive filaments. Heat treatment was selected as a method of controlling oxygen vacancy (V_O), a major factor of the conductive filament. It was carried out at 100 ℃ under moisture removal conditions and at 300 ℃ and 500 ℃ for excellent phase stability. XRD analysis confirmed the anatase phase in the thin film increased as the heat treatment increased, and the Ti³⁺ and OH- groups were observed to decrease in the XPS analysis. In the I-V analysis, the device at 100 ℃ showed a low primary SET voltage of 5.1 V and a high ON/OFF ratio of 10⁴. The double-logarithmic plot of the I-V curve confirmed the device at 100 ℃ required a low operating voltage. As a result, the 100 ℃ heat treatment conditions were suitable for the low voltage driving and high ON/OFF ratio of TiN/TiO₂/FTO RRAM devices and these results suggest that the operating voltage and ON/OFF ratio required for OxRAM devices used in various fields under specific heat treatment conditions can be compromised.