• 제어로봇시스템학회논문지
• /
• 제9권9호
• /
• pp.658-663
• /
• 2003

In deterministic design of feedback controllers for uncertain dynamic systems, the upper bound of the uncertainty is very important to guarantee the stability of the closed loop system. In this paper, we assume that the upper bound of the uncertainty is formulated using a Fredholm integral equation of the first kind, that is, an integral of the product of a predefined kernel with an unknown influence function. We propose an adaptation law that is capable of estimating this upper bound. Using this adaptive upper bound, we design an adaptive variable structure control (AVSC), which guarantees asymptotic stability/ultimate boundedness of uncertain dynamic systems. The illustrative example shows the proposed AVSC is effective for uncertain dynamic systems.

• 한국지능시스템학회:학술대회논문집
• /
• 한국퍼지및지능시스템학회 1998년도 춘계학술대회 학술발표 논문집
• /
• pp.39-42
• /
• 1998

This paper proposes an adaptive fuzzy control scheme for a class of continuous-time nonlinear dynamic systems for which an explicit linear parameterization of the uncertainty is either unknown or impossible. In order to improve robustness under approximation errors and disturbances the proposed scheme includes deadzone in adaptation laws which varies its size adaptively. The assumption of known bounds on the approximation errors and disturbances is not required since those are estimated using adaptation laws. The overall adaptive scheme is proven to guarantee uniform ultimate boundedness in the Lyapunov sense.

• ETRI Journal
• /
• 제39권5호
• /
• pp.695-706
• /
• 2017

This paper presents a caching algorithm that offers better reconstructed data quality to the requesters than a probabilistic caching scheme while maintaining comparable network performance. It decides whether an incoming data packet must be cached based on the dynamic caching probability, which is adjusted according to the priorities of content carried by the data packet, the uncertainty of content popularities, and the records of cache events in the router. The adaptation of caching probability depends on the priorities of content, the multiplication factor adaptation, and the addition factor adaptation. The multiplication factor adaptation is computed from an instantaneous cache-hit ratio, whereas the addition factor adaptation relies on a multiplication factor, popularities of requested contents, a cache-hit ratio, and a cache-miss ratio. We evaluate the performance of the caching algorithm by comparing it with previous caching schemes in network simulation. The simulation results indicate that our proposed caching algorithm surpasses previous schemes in terms of data quality and is comparable in terms of network performance.

• 한국수자원학회논문집
• /
• 제50권2호
• /
• pp.121-128
• /
• 2017

본 연구는 강건성 지수와 불확실성 분석기법을 활용하여 기후변화 취약성 평가과정에서 발생하는 불확실성을 정량화하였다. 본 연구는 우리나라의 6개 광역시(부산, 대구, 인천, 광주, 대전, 울산)를 대상으로 다기준 의사결정기법 중 하나인 TOPSIS 기법을 이용하여 용수공급 취약성 순위를 산정하였다. 강건성 지수는 두 대상 도시의 순위가 가중치의 변화로 인해 순위역전현상이 발생할 수 있는 가능성을 정량화하고 불확실성 분석 기법은 두 도시 사이에 순위역전이 발생할 수 있는 가중치의 최소 변화량을 산정한다. 그 결과 인천과 대구는 용수공급 측면에서 취약한 것으로 나타났으며, 대구와 부산은 용수공급 취약성에 민감한 것으로 나타났다. 따라서 대구는 다른 대안에 비해 상대적으로 용수공급이 취약한 지역으로 나타났으나, 취약성에 민감하기 때문에 기후변화 적응대책 수립 및 시행을 통해 취약성이 크게 향상될 수 있을 것으로 판단된다. 본 연구는 기후변화와 용수공급 측면에서의 적응전략을 계획하고 수립하는데 있어서 우선적으로 고려해야하는 방향을 제안하는 데 사용될 수 있다.

• 대한간호학회지
• /
• 제46권2호
• /
• pp.271-282
• /
• 2016

Purpose: This study was done to explore adaptation experience of living kidney donors after donation. Specific aims were to identify challenges donors face in the process of adaptation following surgery and how they interact with recipients and other people. Methods: Grounded theory methodology was utilized. Participants were 13 living kidney donors at six months or more after donation. Data were collected by in-depth interviews with individual participants. Data were analyzed using constants comparative method with theoretical saturation. Results: A core category emerged as 'keeping the fences of my family in spite of vulnerability'. The adaptation process after donation was manifested in four phases: exploration, balance, maintenance, and acclimatization. Phenomenon was perception of vulnerability. Strategies to manage the vulnerability were assessing changes of body awareness, tailoring regimen to one's own body condition, coping with health problems, keeping restoration of health, and ruminating on the meaning of one's kidney donation. Consequences were reestablishing family well-being, realizing the values of one's kidney donation, and living with uncertainty. Conclusion: Findings of the study indicate that there is a need for health professionals to understand the vulnerability of living kidney donors and help their family system maintain a healthy and productive life. The results of this study can be used to develop phase-specific, patient-centered, and tailored interventions for living kidney donors.

• 한국치위생학회지
• /
• 제10권4호
• /
• pp.735-744
• /
• 2010

Objectives : The purpose of this study was to examine the stressors and stress-adaptation patterns of students preparing for the national dental hygiene certification examination. Methods : The subjects in this study were dental hygiene juniors in four selected colleges located in the metropolitan area. After a survey was conducted, the collected data were analyzed. Results : 1. Concerning motivation of choosing the department of dental hygiene, the largest group that accounted for 72.2 percent chose it due to employment prospects. As to satisfaction level with the department, 40.4 percent were satisfied. In relation to employment prospects, 54.1 percent thought the prospects were bright. 2. They got a mean of 3.23 in stressors. To be specific, they felt the most stress due to test anxiety(3.70), followed by leisure insufficiency (3.21), the uncertainty of the future(3.18) and parental pressure(2.64). 3. They got a mean of 2.02 in stress-adaptation method. They got 2.31 and 1.72 in long-term and short-term adaptation respectively, which showed that long-term stress adaptation method were more prevailing than short-term ones. 4. As for the relationship of the stressors, there was positive correlation among all the test anxiety, future uncertainty, leisure insufficiency and parental pressure, and their correlation was statistically significant(p<0.000). 5. Regarding connections between general characteristics and the stressors, whether they spent two years or more for college admission, satisfaction level with the dental hygiene department, employment prospects and health status made significant differences to the stressors (p<0.05), and there were significant gaps in adaptation patterns according to academic standing, satisfaction level with the department and health state(p<0.05). Conclusions : The dental hygiene students were under great pressure since they had to prepare for the national dental hygiene certification examination to become a certified dental hygienist, one of professional health care workers. Therefore stress counseling programs and stress-coping programs should be developed to relieve the stress of dental hygiene students who are going to take the national dental hygiene certification examination. And they should be assisted to stay away from stress and to handle their stress in a more active manner.

• 한국환경복원기술학회지
• /
• 제18권2호
• /
• pp.79-88
• /
• 2015

Preparations need to be made for Korean pine(Pinus koraiensis) in anticipation of climate change because Korean pine is an endemic species of South Korea and the source of timber and pine nut. Therefore, climate change adaptation policy has been established to conduct an impact assessment on the distribution of Korean pine. Our objective was to predict the distribution of Korean pine while taking into account uncertainty and afforestation conditions. We used the 5th forest types map, a forest site map and BIOCLIM variables. The climate scenarios are RCP 4.5 and RCP 8.5 for uncertainty and the climate models are 5 regional climate models (HadGEM3RA, RegCM4, SNURCM, GRIMs, WRF). The base period for this study is 1971 to 2000. The target periods are the mid-21st century (2021-2050) and the end of the 21st century (2071-2100). This study used the MaxEnt model, and 50% of the presences were randomly set as training data. The remaining 50% were used as test data, and 10 cross-validated replicates were run. The selected variables were the annual mean temperature (Bio1), the precipitation of the wettest month (Bio13) and the precipitation of the driest month (Bio14). The test data's ROC curve of Korean pine was 0.689. The distribution of Korean pine in the mid-21st century decreased from 11.9% to 37.8% on RCP 4.5 and RCP 8.5. The area of Korean pine at an artificial plantation occupied from 32.1% to 45.4% on both RCPs. The areas at the end of the 21st century declined by 53.9% on RCP 4.5 and by 86.0% on RCP 8.5. The area of Korean pine at an artificial plantation occupied 23.8% on RCP 4.5 and 7.2% on RCP 8.5. Private forests showed more of a decrease than national forests for all subsequent periods. Our results may contribute to the establishment of climate change adaptation policies for considering various adaptation options.

• 환경영향평가
• /
• 제28권1호
• /
• pp.1-22
• /
• 2019

본 연구에서는 국가 생태분야 기후변화 리스크 평가와 연계한 적응 정책 및 연구의 방향성에 대한 시사점을 마련하고자 하였다. 본 논문에서 검토한 적응 정책과 연구에 대한 해외 모범사례의 공통점은 국가 적응정책 수립 시 과학적 근거기반 구축 및 불확실성 저감을 목표로 국가단위에서 기후변화가 생물다양성과 생태계에 미치는 영향 연구를 강조한다는 점이다. 이에 비추어 추후 국가 정책 마련 시 기후변화 협약과 생물다양성 협약 등 효율적 통합적 준수를 위한 적응체계를 유도하고, 적응의 경제적 가치평가를 통한 정책 반영, 과학적 연구 프로그램 강화 및 기술 개발의 측면을 보강하여 보다 성공적인 국가적응 정책 구조를 정착해 갈 수 있어야 할 것이다. 특히 생태계 분야 적응방안이 보다 실효성 있게 실행되기 위해서는 우리나라 서식지 및 종의 기후변화 리스크 요소(위해, 노출, 취약성)에 대한 과학적 진단과 분석을 바탕으로 리스크를 평가하고 이에 대한 적응방안을 통합하여 고민하는 노력이 필요할 것이다.

• 한국산학기술학회논문지
• /
• 제17권12호
• /
• pp.381-393
• /
• 2016

본 연구는 근거이론 연구방법을 통해 섬유근통증후군 환자의 질병경험과 적응과정을 파악하고 이해하여 실체이론을 도출하고자 하였다. 본 연구의 참여자는 1개의 종합병원 류마티스 내과 외래에서 섬유근통증후군를 치료 중인 13명(여성 12명과 남성 1명)이다. 자료 수집은 2014년 1월부터 5월까지 개별 심층면담을 통해 이루어졌다. 이론적 표본추출법은 이론적 포화의 시점을 적용하였다. 필사된 면담의 내용은 Corbin과 Strauss (2008)의 근거이론방법으로 분석하였다. 연구결과 개방코딩을 통해 총 98개 개념과 26개 하위범주, 10개 범주가 도출되었다. 섬유근통증후군 환자의 질병 적응과정은 '불확실성과 한계상황인식'과 '자기통제 가능성 평가와 기대수준 결정', '적응전략 개발과 시도', '자기조절'의 4단계로 나타났다. 섬유근통증후군환자의 질병적응 유형은 확장형과 안정형, 표출형, 위축형의 4가지 유형으로 파악되었다. 또한 핵심범주인 '자기조절법 터득하기'로부터 '보호적 자기조절' 이론이 도출되었다. 본 연구결과 섬유근통증후군 환자들은 질병으로 인해 불확실한 상황에서 안정상태를 찾기 위해 자기조절을 반복적으로 활용하여 적응해가고 있음을 알 수 있었다. 따라서 본 연구결과를 근거로 대상자들의 질병 적응 유형에 따른 적합한 간호중재 및 가족을 포함하는 교육 프로그램의 개발이 필요할 것으로 사료된다.

• 제어로봇시스템학회논문지
• /
• 제12권11호
• /
• pp.1081-1087
• /
• 2006

Generally, biped walking is difficult to control because a biped robot is a nonlinear system with various uncertainties. In this paper, we propose a hybrid sliding-mode control method using a WNN uncertainty observer for stable walking of the 5-link biped robot with model uncertainties and the external disturbance. In our control system, the sliding mode control is used as main controller for the stable walking and a wavelet neural network(WNN) is used as an uncertainty observe. to estimate uncertainties of a biped robot model, and the error compensator is designed to compensate the reconstruction error of the WNN. The weights of WNN are trained by adaptation laws that are induced from the Lyapunov stability theorem. Finally, the effectiveness of the proposed control system is verified through computer simulations.