• 한국컴퓨터정보학회논문지
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• 제13권6호
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• pp.137-145
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• 2008

대형 무선 센서 네트워크(WSNs)는 일반적으로 수백에서 수천 개의 센서 노드들로 구성되어 있다. 이러한 대형 WSNs는 비용 및 에너지를 고려한 에너지 효율성뿐만 아니라 네트워크의 유지 및 관리가 요구된다. 사용자는 효율적인 시스템을 통해서 사용자 수준의 센싱 서비스 품질을 제공받을 수 있어야 한다. 이 네트워크에서 사용자에게 제공되는 결과 데이터의 품질은 이벤트 검출에 관련된 센서들의 개수가 결정적인 역할을 한다. 그러므로 사용자 요구 품질에 적합한 QoS를 제공할 수 있는 네트워크 프로토콜은 일부 센서 노드들에서 에러가 발생하더라고 전체 시스템 성능에 영향을 주지 않으면서, 동시에 에너지 소비가 최소화되도록 설계되어야 한다. 본 논문에서 제안된 프로토콜은 LEACH(Low Energy Adaptive Clustering Hierarchy) 프로토콜을 기반으로 하며, 지속적인 감시가 요구되는 대형 네트워크에 적합한 역할 기반의 자가 구성 프로토콜을 제안하였다.

• 기본간호학회지
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• 제19권4호
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• pp.434-443
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• 2012

Purpose: This study was conducted to investigate sleep patterns in nursing students as measured by an automated wireless sleep tracker and self-reported sleep scales. Methods: Data were collected from October, 2011 to May, 2012. ZQ (a symbolic number that measures the quality and quantity of sleep) was calculated from the automated wireless sleep tracker. Pittsburgh Sleep Quality Index-Korean version, Sleep scale A, and sleep satisfaction were used as self-report sleep scales. Female nursing college students (n=37) were recruited by convenience sampling. Before going to bed, they were asked to put on a head-band type sleeping sensor and to move it the next morning. Every student slept 2~4 nights with the sleep tracker. Data were collected for 86 (91.4%) of 94 nights' sleep. The students were also requested to fill in the PSQI-K, sleep scale A, and sleep satisfaction. Results: The only statistically significant correlation was between ZQ and sleep satisfaction (r=.869, p=.026). The biggest obstacle in using this device was putting on the head-band type sensor. Conclusion: Validity of the wireless sleep tracker was verified in part. The usefulness of this device in nursing research and practice was identified. Further evaluation need to be conducted with various populations.

• Smart Structures and Systems
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• 제6권5_6호
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• pp.661-673
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• 2010

This paper presents recent developments in an extremely compact, wireless impedance sensor node (the WID3, $\underline{W}$ireless $\underline{I}$mpedance $\underline{D}$evice) for use in high-frequency impedance-based structural health monitoring (SHM), sensor diagnostics and validation, and low-frequency (< ~1 kHz) vibration data acquisition. The WID3 is equipped with an impedance chip that can resolve measurements up to 100 kHz, a frequency range ideal for many SHM applications. An integrated set of multiplexers allows the end user to monitor seven piezoelectric sensors from a single sensor node. The WID3 combines on-board processing using a microcontroller, data storage using flash memory, wireless communications capabilities, and a series of internal and external triggering options into a single package to realize a truly comprehensive, self-contained wireless active-sensor node for SHM applications. Furthermore, we recently extended the capability of this device by implementing low-frequency analog-to-digital and digital-to-analog converters so that the same device can measure structural vibration data. The compact sensor node collects relatively low-frequency acceleration measurements to estimate natural frequencies and operational deflection shapes, as well as relatively high-frequency impedance measurements to detect structural damage. Experimental results with application to SHM, sensor diagnostics and low-frequency vibration data acquisition are presented.

• Structural Engineering and Mechanics
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• 제35권1호
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• pp.37-52
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• 2010

Special-shape arch bridge for self-balance (SBSSAB) in Zhongshan City is a kind of new fashioned spatial combined arch bridge composed of inclined steel arch ribs, curved steel box girder and inclined suspenders, and the mechanical behavior of the SBSSAB is particularly complicated. The SBSSAB is aesthetic in appearance, and design of the SBSSAB is artful and particular. In order to roundly investigate the mechanical behavior of the SBSSAB, 3-D finite element models for spatial member and shell were established to analyze the mechanical properties of the SBSSAB using ANSYS. Finite element analyses were conducted under several main loading cases, moreover deformation and strain values for control section of the SBSSAB under several main loading cases were proposed. To ensure the safety and rationality for optimal design of the SBSSAB and also to verify the reliability of its design and calculation theories, the 1/10 scale model tests were carried out. The measured results include the load checking calculation, lane loading and crowd load, and dead load. A good agreement is achieved between the experimental and analytical results. Both experimental and analytical results have shown that the SBSSAB is in the elastic state under the planned test loads, which indicates that the SBSSAB has an adequate load-capacity. The calibrated finite-element model that reflects the as-built conditions can be used as a baseline for health monitoring and future maintenance of the SBSSAB.

• Smart Structures and Systems
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• 제6권5_6호
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• pp.689-709
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• 2010

In this paper, a low cost, low power but multifunctional wireless sensor node is presented for the impedance-based SHM using piezoelectric sensors. Firstly, a miniaturized impedance measuring chip device is utilized for low cost and low power structural excitation/sensing. Then, structural damage detection/sensor self-diagnosis algorithms are embedded on the on-board microcontroller. This sensor node uses the power harvested from the solar energy to measure and analyze the impedance data. Simultaneously it monitors temperature on the structure near the piezoelectric sensor and battery power consumption. The wireless sensor node is based on the TinyOS platform for operation, and users can take MATLAB$^{(R)}$ interface for the control of the sensor node through serial communication. In order to validate the performance of this multifunctional wireless impedance sensor node, a series of experimental studies have been carried out for detecting loose bolts and crack damages on lab-scale steel structural members as well as on real steel bridge and building structures. It has been found that the proposed sensor nodes can be effectively used for local wireless health monitoring of structural components and for constructing a low-cost and multifunctional SHM system as "place and forget" wireless sensors.

• 디지털융복합연구
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• 제15권1호
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• pp.413-425
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• 2017

이 연구는 초등학교 고학년의 의지력 향상에 활용할 수 있는 자기조절 프로그램을 개발하는 데에 목적이 있다. 이를 위해서 관련문헌의 수집 분석과 초등학교 5,6학년 93명과 초등교사 32명을 자기조절 프로그램에 대한 기초 조사를 하였으며, 조사 내용은 프로그램의 내용 분석과 프로그램 진행에 필요한 요인 등이다. 8명의 전문가로부터 총2회에 걸쳐 프로그램의 구성과 내용에 대해 타당성 검증을 받았다. 프로그램 구성은 인성함양과 밀접한 관련이 있는 태도를 기르기 위해 아동으로 하여금 하나의 행동목표 성공이 의지력의 향상으로 귀결되는 효과를 초래하는 방식으로 하였다. 또한 의지력 향상을 위해 자기점검, 모니터링과 보상 등의 방법이 포함되었으며, 이를 통해 아동이 좋은 태도를 습관화하는 것이 목표이다.

• 한국지반공학회:학술대회논문집
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• 한국지반공학회 2007년 가을학술발표회
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• pp.665-678
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• 2007

It was applied the grouting method to fill densely the space between the bottom of the caisson and the ground with the grout mixture mixed with anti-washout admixture after locating accurately the precast caisson on three concrete landing pads but it is far different from a costly conventional method, which place concrete to build the foundation of reinforcement concrete on the spot after excavating inside of the temporary coffering wall for the bridge foundation in the sea. To verify the grouting method in advance, the full-scale trial test was performed twice on the land. After confirming the fluidity of material for the injection and some possible problems during construction and then enhancing the original design, the main process is ongoing and it has been finished 12 spots until now. The purpose of this study is to introduces for the first time in Korea the grouting method including the automatic and the manual monitoring process applied to, based on the main process of the caisson foundation finished already in the site. In a similar construction it is sincerely expected to be referred to in the future.

• 천문학회보
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• 제42권1호
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• pp.28.3-29
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• 2017

We present the results of very long baseline interferometry (VLBI) observations of gamma-ray bright blazar S5 0716+714 using the Korean VLBI Network (KVN) at the 22, 43, 86, and 129 GHz bands, which are part of the KVN key science program known as the Interferometric Monitoring of Gamma-ray Bright AGNs (iMOGABA). Multi-frequency VLBI observations were conducted in 29 sessions from January 16, 2013 to March 1, 2016. The source was detected and imaged in all available frequency bands. For all observed epochs, the source is compact on the milliarcsecond (mas) scale, yielding a compact VLBI core dominating the synchrotron emission on the mas scale. Based on the multi-wavelength data at 15 and 230 GHz, we found that the source shows multiple prominent enhancements of the flux density at the centimeter (cm) and millimeter (mm) wavelengths, with mm enhancements leading cm enhancements with a time lag of $18{\pm}5$ days. Turnover frequency is found to vary over our observations between 22 to 69GHz. Taking into account the synchrotron self-absorption model of the relativistic jet in S5 0716+714, we estimated the magnetic field strength in the mas emission region to be 0.4-66 mG during the observing period, finding that the magnetic field strength is strongly correlated with the turnover frequency and the relatively strong magnetic field (e.g., B > 40 mG) is correlated with flux enhancements at mm wavelengths (e.g., 86 GHz).

• 지역사회간호학회지
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• 제26권4호
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• pp.405-414
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• 2015

Purpose: The purposes of this study were to examine the effects of home visit healthcare using a complex program on community-dwelling frail elders' physical strength, frailty, and depression and to compare the effects among three regions. Methods: This study was conducted as a quasi-experimental study using one-group pretest-posttest design. A total of 86 subjects were sampled from three regions (metropolis, small city, and rural area). The program was applied for 14 weeks. This program consisted of disease management by a visiting nurse, exercise with a visiting nurse, self exercise, telephone monitoring, health education, counseling, providing handbook, and incentive. Physical strength was measured by balance, upper-limb, and lower-limb muscle strength. Frailty was measured by the Korean Frail Scale and depression was measured by the Geriatric Depression Scale. Paired t-test and ANCOVA were used to analyze the effects. Results: Physical strength, frailty, and depression were significantly improved after applying the complex program. There were not differences among the regions. Conclusion: Home visit healthcare using a complex program was effective in improving frail elders' physical strength, frailty, and depression. There were not differences among the regions. Therefore, home visit healthcare using a complex program needs to be expanded to other regions.

• Environmental Analysis Health and Toxicology
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• 제31권
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• pp.18.1-18.8
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• 2016

Objectives This study aimed to evaluate the risk factors associated with depression and suicidal ideation in a rural population. Methods A survey was conducted with 543 farmers from Chungcheongnam-do Province using the Center for Epidemiologic Studies Depression Scale (CES-D) for depression, Lubben Social Network Scale (LSNS) for social support, Swedish Q16 for neurotoxicity symptoms and a survey tool for farmer's syndrome. Results After adjusting for socioeconomic factors using logistic regression analysis, poor self-rated health, low social support and neurotoxicity were positively associated with the risk of depression (odds ratio [OR], 15.96; 95% confidence interval [CI], 3.11 to 81.97; OR, 3.14; 95% CI, 1.26 to 7.82; and OR, 3.68; 95% CI, 1.08 to 12.57, respectively). The risk of suicidal ideation significantly increased with low social support, neurotoxicity and farmer's syndrome (OR, 2.28; 95% CI, 1.18 to 4.40; OR, 6.17; 95% CI, 2.85 to 13.34; and OR, 3.70; 95% CI, 1.51 to 9.07, respectively). Conclusions Given the overall results of this study, there is a need to establish programs which can improve the health and social relationships of farmers. Also, when farmers have neurological symptoms from pesticide exposure and characteristic symptoms of farmer's syndrome, a monitoring system for depression and suicide must be made available.