• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2003년도 춘계학술대회 논문집
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• pp.438-442
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• 2003

For an efficient sliding mode control system stability and chattering avoidance should be guaranteed. A continuation method using boundary layer is well known as one solution for this. However since not only model uncertainties and disturbances but also control task itself is variable. it is practically impossible to set controller parameters - control discontinuity, control bandwidth, boundary layer thickness - in advance. In this paper first an adaptation law of control discontinuity is introduced to assure system stability and then fuzzy logic based tuning algorithm of design parameters is applied based on monitored performance indices of tracking error, control chattering, and model precision. In the end maximum control bandwidth not exciting unmodeled dynamics and minimum control discontinuity, boundary layer thickness making system stable and free of chattering are found respectively. This eliminates control chattering and enhances control accuracy as much as possible under given control situation. In order to demonstrate the validity of the proposed algorithm safe headway maintenance control for autonomous transportation system is simulated. The control results show that the proposed algorithm guarantees system stability all the time and tunes control parameters consistently and in consequence implements an efficient control in terms of both accuracy and actuator chattering.

• International Journal of Fuzzy Logic and Intelligent Systems
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• 제13권2호
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• pp.91-99
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• 2013

An autonomous unmanned underwater vehicle is a type of marine self-propelled robot that executes some specific mission and returns to base on completion of the task. In order to successfully execute the requested operations, the vehicle must be guided by an effective navigation algorithm that enables it to avoid obstacles and follow the best path. Architectures and principles for intelligent dynamic systems are being developed, not only in the underwater arena but also in related areas where the work does not fully justify the name. The problem of increasing the capacity of systems management is highly relevant based on the development of new methods for dynamic analysis, pattern recognition, artificial intelligence, and adaptation. Among the large variety of navigation methods that presently exist, the dynamic window approach is worth noting. It was originally presented by Fox et al. and has been implemented in indoor office robots. In this paper, the dynamic window approach is applied to the marine world by developing and extending it to manipulate vehicles in 3D marine environments. This algorithm is provided to enable efficient avoidance of obstacles and attainment of targets. Experiments conducted using the algorithm in MATLAB indicate that it is an effective obstacle avoidance approach for marine vehicles.

• 대한간호학회지
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• 제30권2호
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• pp.293-306
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• 2000

Providing care to the dementia elderly with behavioral problem is a major issue in nursing homes today. This study was aimed to explore the nursing staffs′ response to aggressive dementia patients, and the effect that the aggressive behavior had on Nsgstaff. The interviews used a semi-structured questionnaire are were carried out from May to July, 1999. The subjects were 23 nursing personnel working in the nursing homes for dementia elderly. The result are as follows; 1. The types of aggressive behavior cited by the subjects was "physical", "linguistic", and "sexual". 2. The factors that caused the behavior were "symptoms of disease", "under- conditioning", "context of nursing care", "unsatisfied need", "relationship to other patients", "change of outer environment", and "invasion of one′s own privacy". 3. The response of the subjects were "unhappiness", "stress", "anger", "exaggeration", "anxiety", and "fear". 4. The management strategies listed by nursing personnel used to alleviate aggressive behavior were "ignorance" "patience" "leaving the area" "soothing sounds" "verbal punishment" "restriction and isolation" and "various management skill appliance" "adaptation". 5. The effect that aggressive behavior and were "disturbance of relationship to elderly" "decline in the amount and quality of nursing care" "interruption of task performance" "job exhaustion" "desire to leave the job" "physical impact" "stress on the cognition of others" "anxiety about health and one own future" "interference to family life′. The findings of this study will be useful in understanding the difficulties of nursing personnel when confronting the aggressive behavior of dementia partients. It also is useful as basic data in preparing efficient intervention program for these difficulties.

• 한국감성과학회:학술대회논문집
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• 한국감성과학회 1999년도 춘계학술발표논문집 논문집
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• pp.221-230
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• 1999

Automobile horn's psychoacoustic characteristic and significance as a anturalistic signal of danger makes it a valuable auditory stimulus to study such psychophysiological responses as startle, orienting and defense reactions. However, comparison and differentiation of physiological responses to commercially available horns is a complicated task due to small contrast of technical features of horns and influence of such processes as habituation on physiological outcome with increased number of auditory stimulation trials. In the study on 10 college students we performed comparative analysis of tonic and phasic reactivity of physiological responses mediated by autonomic nervous system in order to identify role of habituation and decrement of autonomic responsivity, as well as possibility o differentiate subjectively most and least preferred and subjectively more appropriate horns according to physiological manifestations. It was showed that electrodermal and cardiovascular reactivity have concurrent patterns of adaptation to repeated stimulation, namely skin conductance variables habituated, cardiac reactivity failed to show signs of habituation, while vascular component of response were facilitated demonstrating marked sensitization. Differentiation of Physiological responses to horns with respect to their subjective rating scores was possible, however electrodermal reactivity was effective only at the first block of trials, while phasic and tonic cardiovascular reactivity differentiate responses during whole course of experiment. There are discussed possible autonomic mechanisms involved in mediation of observed results.

• Journal of Microbiology and Biotechnology
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• 제21권3호
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• pp.243-251
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• 2011

The gene bolA was discovered in the 80's, but unraveling its function in the cell has proven to be a complex task. The BolA protein has pleiotropic effects over cell physiology, altering growth and morphology, inducing biofilm formation, and regulating the balance of several membrane proteins. Recently, BolA was shown to be a transcription factor by repressing the expression of the mreB gene. The present report shows that BolA is a transcriptional regulator of the dacA and dacC genes, thus regulating both DD-carboxypeptidases PBP5 and PBP6 and thereby demonstrating the versatility of BolA as a cellular regulator. In this work, we also demonstrate that reduction of cell growth and survival can be connected to the overexpression of the bolA gene in different E. coli backgrounds, particularly in the exponential growth phase. The most interesting finding is that overproduction of BolA affects bacterial growth differently depending on whether the cells were inoculated directly from a plate culture or from an overnight batch culture. This strengthens the idea that BolA can be engaged in the coordination of genes that adapt the cell physiology in order to enhance cell adaptation and survival under stress conditions.

• 감성과학
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• 제15권3호
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• pp.381-388
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• 2012

The purpose of this study is to check if LED lighting can be used as general lighting and examine the color rendering property of full color RGB LED lighting. CRI is one of the important properties of evaluating lighting. However the present CRI does not fully evaluate LED lightings. Firstly, the performance of a simple task was compared other than comparing CRI values for different lighting. For experimental preparation three types of lightings were used; standard D65 fluorescent tube, general household fluorescent tube, and RGB LED lighting. All three lightings show high error for Purple-Red. All three lightings show similar error for all hues and prove that color discrimination is not affected by the lighting. This proves that LED could be used as general lighting. Secondly, problems of the conventional CIE CRI method are considered and new models are suggested for the new lighting source. Each of the models was evaluated with visual experiment results obtained by the white light matching experiment. The suggested model is based on the CIE CRI method but replaces the color space model by CIELAB, color difference model by CIEDE2000, and chromatic adaptation model by CAT02.

• The Journal of Asian Finance, Economics and Business
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• 제8권5호
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• pp.1019-1029
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• 2021

The study aims to investigate the impact of psychological climate, self-resilience, Organizational Citizenship Behaviour (OCB) and job stress on employee performance during Covid-19 pandemic. This paper also attempts to find out the mediating role of OCB and job stress in this context. A confirmatory survey was conducted on 316 employees of several institutions in Indonesia who worked from home during Covid-19 for a minimum period of 2 months. The research revealed that 1) PC has significant and positive influence on OCB and performance; 2) Self resilience have positive and significant influence on performance; 3) PC and self-resilience have a negative influence on job stress; 4) there are insignificant relationship between self-resilience on OCB; OCB and job stress on performance; 5) PC and self-resilience have no indirect influence on performance through OCB and job stress. The findings of this study reveal that organizations expected to have strategic approach in order to handle Covid-19 pandemic in different work patterns that are required to carry out routine office tasks from home, including handling stress as a fast adaptation for both employees and organizations that have a routine task from home.

• 대한안전경영과학회지
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• 제23권4호
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• pp.121-133
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• 2021

The composition of human resources in industrial sites is becoming global. In Korea, too, the proportion of foreign members in all industrial fields and production sites is increasing. This is the reason why an approach that reflects this reality is needed in the basic unit of competitive sources. Competitiveness starts with value creation, and this progresses through field innovation. Through empirical analysis of this study, it was analyzed that South Korea members showed active actions and attitudes in developing, promoting, and realizing ideas when they strongly recognized the real meaning of empowerment given by leaders. On the other hand, it was found that foreign members do not know the meaning of empowerment itself, so they are often unable to play an active role in the development, promotion, and realization of ideas. In fact, it was analyzed that foreign members generally did not experience positive interactions with LMX and were exposed to simple tasks and controls. In other words, they are being discriminated against in terms of communication problems, compensation system, and work environment. In particular, this phenomenon is exacerbated in the case of small and medium-sized enterprises (SMEs). Situational response to foreign workers through improvement of LMX and empowerment should be evaluated as a key management task in a situation where productivity improvement and job unit innovation are urgently needed.

• 영재교육연구
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• 제24권2호
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• pp.289-312
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• 2014

본 연구의 목적은 영재 청소년의 학업탄력성 척도를 개발하는 것이다. 이를 위하여 158명의 과학영재교육원 학생들을 대상으로 개방형 질문과 선행연구 고찰로부터 101개의 기초 예비문항을 추출하였다. 이를 토대로 다시 240명의 과학영재학생들을 대상으로 문항분석 및 탐색적 요인분석을 실시하였다. 영재 청소년용 학업탄력성 척도 문항 개발을 위한 최종단계로 인천, 경기, 서울, 창원, 사천, 울산 지역의 영재교육원 및 지역영재학급 학생 444명을 대상으로 확인적 요인분석을 실시하였다. 그 결과 영재 청소년의 학업탄력성을 측정할 수 있는 11요인 42문항을 추출하였다. 하위요인은 '목표의식', '자기이해', '교육적 열망', '학업적 자기조절', '과제 집착력', '성공귀인(능력)', '성공귀인(노력)', '대인관계(친구)', '대인관계(부모)', '대인관계(교사)', '낙관성'으로 확인되었다. 척도의 타당도를 확보하기 위하여 확인적 요인분석 결과, 모든 경로계수가 유의하고, 개념신뢰도, 분산추출지수, 결정계수가 기준치 이상으로 나타났다. 또한 영재 청소년의 학업탄력성 척도가 학교적응, 회복탄력성, 학업소진 척도와 유의한 상관을 나타내고 있어 내적 외적 타당도를 확보할 수 있었다. 본 연구는 영재 청소년의 학업탄력성을 측정할 수 있는 도구를 개발하였다는 데 그 의의가 있다.

• 한국안광학회지
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• 제15권3호
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• pp.263-268
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• 2010

목적: 안구운동과 주시 능력은 독서 시 외적 정보를 얻기 위한 주요한 과정이며 명료한 시생활 조건의 주요한 매개변수로 작용한다. 본 연구는 주시 거리와 노안교정 방법의 다양한 조건에 의한 읽기능력과 주시 능력을 평가하기 위하여 시행하였다. 방법: 평균 $48.1{\pm}4.2$세의 22명이 참여 하였으며, 각 피실험자는 실험에 적합한 선별검사를 실시하여 안질환이 없으며 이전에 콘택트렌즈 사용 경험이 없고 단초점 근용안경을 제외한 어떠한 형태의 노안교정 경험이 없는 대상자로 선별하였다. 읽기시간과 주시 횟수는 단초점렌즈(SV), 이중초점렌즈(BIF), 누진렌즈(PAL) 그리고 모노비젼(MV)를 한 상태에서 안구추적 시스템(Eye Tracking System, ASL Mobile Eye)을 사용하여 측정하였다. 읽기능력의 평가를 위한 원근 주시 거리는 2m, 40 cm에서 각각 시행하였다. 결과: 근거리 읽기능력의 평가에 있어서 읽기시간과 주시 횟수는 본 연구에 사용된 단초점렌즈와 노안교정안경과 모노비젼 사이에 유의한 차이를 보였으나(p<0.001), 특히나 단초점렌즈를 착용하였을 경우, 이중초점, 누진렌즈 그리고 모노비젼을 착용하였을 경우에 비해 읽기시간과 주시시간이 증가하였다. 하지만 원거리 읽기능력의 평가에서는 모든 조건에서 유사한 결과를 보였으며, 통계적으로 유의한 차이를 보이지 않았다. 결론: 원거리와 근거리 시력의 교정을 목적으로 안경렌즈나 콘택트렌즈와 같은 노안교정방법의 사용은 근업시 읽기와 주시 능력에 도움이 될 수 있으나, 노안자에게 있어서 근거리 교정이 없는 단초점렌즈의 사용은 근거리에 대한 조절력 부족으로 인해 읽기시간의 증가와 주시 횟수 또한 증가함을 보였다. 추후 연구에는 본 연구에서는 노안교정의 무경험자를 대상으로 측정했으나 적응 능력을 고려한 노안교정 유경험자에 대한 연구를 기대할 수 있을 것이다.