• 센서학회지
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• 제22권1호
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• pp.76-83
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• 2013

A real-time wireless monitoring and analysis methods using the wearable PPG sensor to estimate cardiovascular condition is studied for ubiquitous healthcare service. A small size and low-power consuming wearable photoplethysmogram (PPG) sensor is designed as a wrist type device and connected with the IP node assigned its own IPv6 address. The measured PPG waveform in the IP node is collected and transferred to a central server PC through the IP-enabled wireless network for storage and analysis purposes. A monitoring and analysis program is designed to process the accelerated plethysmogram (APG) waveform by applying the second order derivatives to analyze systolic waves as well as heart rate variability analysis from the measured PPG waveform. From our results, the features of cardiovascular condition from individual's PPG waveform and estimation of vascular compliance by the comparison of APG-aging index (AI) and ratio of LF/HF are demonstrated.

• 한국해양공학회지
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• 제7권2호
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• pp.57-67
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• 1993

The fracture behavior of plain woven glass/epoxy composite plates with a crack is investigated under static tensile loading. It is shown in this paper that the characteristic length associated with the point stress criterion depends on the crack length. To predict the not ched tensile strength, the point stress criterion proposed by Whitney and Nuismer are modified. An excellent agreement is found between the experimental results and the analytical prediction of the modified point stress criterion. The condition of unstable crack growth in the presence of a per-existing flaw(machined notch) is examined by means of the maximum stress intensity factor $K_max$ using maximumload P$_max$. The values of $K_max$ evaluated from energy release rate G$_max$(the compliance me thod) indicate a wide difference. Therefore in regard to anisotropy and heterogeneity of the composite materials studied, the modified shape correction factor f(a/W) is obtained. $K_max$evaluated by the compliance method a little or insignificantly depends on the initial crack length a, the specimen thickness B, the crack angle .theta. and the specimen geometry.

• 대한기계학회논문집
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• 제10권1호
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• pp.62-69
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• 1986

본 연구에서는 표면균열의 전파거동에 관한 연구의 일환으로 경량화재료 로서 항공기 구조용으로 널리 사용되고 있는 7075-T651 알루미늄합금을 준비하고 제하탄성 compliance법을 이용하여 표면 및 깊이 방향의 균열진전거동의 특성을 밝히고져 한다.

• 대한기계학회논문집A
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• 제23권11호
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• pp.1952-1959
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• 1999

The work factor approach, so-called single specimen technique could be used to determine energy release rate from a single test record for unidirectional CLS specimen. In the present study, the work factor approach was extended to determine the mixed-mode fracture toughness of multi-directional graphite/epoxy laminated composites. Multi-directional CLS specimens were used for fracture tests. The stacking sequences used for the lap and the strap were $[90_2/0_2]_s/[0_4/90_4]_s$ and $[0/\pm45/0]_s/[0_2/\pm45_2/0_2]_2$, respectively. For both cases, the fracture toughness determined from the work factor approach was compared with that determined from the compliance method. It was found that both methods produced fracture toughness within a maximum 15% difference for each stacking sequence. The fractography analysis also showed that the fiber bridging occurred for$[0/\pm45/0]_s/[0_2/\pm45_2/0_2]_2$ case while it did not occur for $[90_2/0_2]_s/[0_4/90_4]_s$ case.

• 한국안전학회지
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• 제33권4호
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• pp.72-77
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• 2018

There are various approaches to prevent industrial accidents, of which the focus on human factors is behavior based safety(BBS). The BBS provides positive feedback on safety behavior and corrective feedback on unsafe behavior. Determining the feedback ratio of positive and correct feedback is an important issue in BBS. The purpose of this study was to examine the effects of positive and corrective feedback ratio on safety performance and feedback acceptance. The participants of this study were sixty undergraduate and graduate students at C University in Seoul, Korea. Participants were asked to work on a simulated welding task. The independent variable of was different positive vs. corrective feedback ratio (1:1 and 1:4). The dependent variables were the amount and the number of correctly completed work tasks, compliance rate of safety behavior, and feedback acceptance. The experimental design of this study was 2 x 2 mixed design. The results showed that feedback, regardless of the ratio, increased both correctly completed work tasks and the compliance rate of safety behavior, while 1:1 positive vs. corrective feedback ratio was more effective than 1:4 ratio. In addition, 1:1 ratio produced higher level of feedback acceptance compared to 1:4 ratio.

• 기본간호학회지
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• 제23권2호
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• pp.194-203
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• 2016

Purpose: This study was conducted to test the effect of a scenario based hand hygiene education program on hand hygiene knowledge, hand hygiene perception, hand hygiene compliance and hand hygiene method in nursing students. Methods: A non-equivalent control group, non-synchronized quasi-experimental design was used. Forty five nursing students participated in the study with 22 in the experimental group and 23 in the control group. Data were analyzed using descriptive statistics, ${\chi}^2-test$, t-test, and repeated measures of ANOVA. Results: There were significant increases in hand hygiene knowledge (t=-4.28, p<.001) and accuracy of the hand hygiene method by week (F=7.33, p<.001). However, hand hygiene perception (t=-1.67, p=.102) and hand hygiene compliance rate (F=7.33, p=.405) were not significantly changed. Conclusion: The effects of the scenario based hand hygiene education program provided in this study were excellent, compared to the other hand hygiene education programs. Moreover, as a result of investigating the education effects through direct observation for 4 weeks, appropriate feedback was offered in the third week, and it was found that maintaining the effect was necessary. However, the current status of hand hygiene compliance and accuracy of methods for ensuring hand hygiene need to be studied further.

• Journal of Biosystems Engineering
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• 제15권3호
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• pp.219-229
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• 1990

The compression creep behavior of grains when loaded depends not only on load but also on duration of load application. The most common methods of studying the load-time characteristics of agricultural products is by employing rheological models such as Burger's model. However it is sometimes not sufficient to describe the viscoelastic behavior of grains to be Burger's model. For this reason, this study was conducted to develop the rheological model which represented the creep compliance response of the rough rice kernel and was a function of initial stress applied and time. The effects of the initial stress applied and the moisture content on the compression creep behavior of the rough rice kernel were analyzed. The results were obtained from the study as follows: 1. Since the viscoelastic behavior of the rough rice kernel was nonlinear, the transient and steady state creep compliance was satisfactorily modelled as follows: $$J({\sigma},t)=A{\sigma}^B[C+Dt-exp(-Ft)]$$ But, for the every stress applied, the compression creep behavior of the samples tested can be well described by Burger's model respectively. 2. The creep compliance, the instantaneous elastic strain, the retarded elastic strain and the viscous strain of the sample tested generally increased in magnitude with increasing the applied initial stress and the moisture content used in the tests. At low moisture content, the creep compliance for the Japonica-type rough rice kernel Was a little higher than those for Indica-type and at high moisture content, vice versa at high moisture content. 3. The retardation times of the samples had not an uniform tendency by the initial stress and the moisture content. The retardation times ranged from 0.66 to 6.76 seconds, and the creep progressed from transient to steady state at a relatively high rate. 4. The less viscous strain than the instantaneous elastic strain for the samples tested indicated that rough rice kernel behaved as a viscoelastic body characterized by elasticity than viscosity.

• 청정기술
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• 제23권3호
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• pp.256-269
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• 2017

국내외 자원순환규제 대응 및 온실가스 저감을 위해 자동차산업에서는 부품의 소재 종류의 수를 줄여 재활용률 목표치를 달성하고, 폐기단계 또는 제조단계에서 발생하는 불량 및 스크랩을 순환자원으로 재활용하는 노력을 하고 있다. 또한 기존 제품의 성능은 유지하면서 온실가스 저감 목표치를 달성하기 위해 부품 경량화를 추진하고 있다. 기존제품의 폐기단계에서 100% 소각을 하던 제품을 개선제품에서는 제조전단계와 제조단계에서 발생하는 스크랩, 불량을 수거하여 90%의 재활용이 가능하도록 개선했다. 또한 기존제품 대비 56% 경량화를 통해 연비 개선효과를 나타냈다. 본 연구에서는 자동차 언더커버를 대상으로 유니소재화 제품 개발 적용가능성에 대한 사전평가를 실시하고, 개발된 시제품의 전과정평가를 통해 기존제품과 개발된 시제품의 환경영향값을 비교, 분석하고자 한다.

• 한국항행학회논문지
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• 제19권1호
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• pp.33-40
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• 2015

A-SMGCS는 모든 기상조건에서 공항 이동지역 내 요구되는 안전수준을 확보하는 동시에 정해진 지상이동률을 유지하기 위하여 항공기와 차량에게 경로, 안내, 감시, 통제기능을 제공하는 시스템이다. 본 연구에서는 A-SMGCS 적합성 검증방안을 개발하기 위해 시스템 엔지니어링을 도입하였다. A-SMGCS 운용개념을 통해 레벨 IV급 A-SMGCS에 대한 요구사항을 정의하였으며, 기능분석과 할당을 통해 시스템 아키텍처와 시스템 규격을 도출하였다. A-SMGCS 개발을 위한 WBS와 IMS를 수립하였으며, 마지막으로 시스템에 대한 확인 및 검증을 위한 CCL과 TEMP를 개발하였다.

• 지식경영연구
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• 제12권5호
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• pp.1-10
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• 2011

Forming a network, through Social Network Services (SNS), among a group of people who share the same hobby or interests could increase the information sharing among the members at an exponential rate. Moreover, SNS users' behavior extends beyond the traditional introverted consumption behavior to a proactive behavior by owning or actively sharing product information. For firms, such proactive consumer behavior translates into marketing effects such as the word of mouth (WOM) effect. Therefore, SNSs are accepted not only as a communications channel between firms and consumers but also as marketing channel, suggesting the possibility of a new revenue source. In this context, we will explore into the factors of SNS contents which conserve firms' image and product information, and effects of the factors on consumer attitude and WOM.