• 대한기계학회논문집A
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• 제28권10호
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• pp.1451-1457
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• 2004

Bone density parameters of children, unlike that of adult, might reflect growth effect along longitudinal direction as well as bone mass. The clinical test was performed for 859 male/female children with age 6-16 years. Ultrasonic imaging system was used to measure bone density, and relationship of bone density to age was evaluated. The bone quality index appeared to be highly correlated with age for male/female children. It was found that bone quality index rose rapidly in the first growth period. The bone quality index was then kept almost unchanged in the period of puberty, and slowly rose after puberty. It was also found that growth of female stopped earlier than that of male. Also, if more clinical examinations are performed by applying various sizes of region of interest, relationship between bone density and age is expected to be more reliable.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2001년도 봄 학술발표회 논문집
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• pp.81-86
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• 2001

The concrete bridge decks are in need of replacement and rehabilitation due to decreasing load carrying capacity. In this study, to propose a strengthening technique that improves usability and structural performance of the bridge deck and to propose an efficient strengthening design technique which satisfies both the strength End serviceability of the bridge deck, this paper shows the failure characteristics of the strengthened bridge decks and proposes an empirical yield criterion. Therefore, strengthening efficiency was proposed based on the experiment and yield line analysis result. The yield line theory which adopts the modified criteria of Johansen is considered to predict the ultimate strength about all strengthening material(Carbon Fiber Sheet, Carbon Fiber Rod, Grid Type Carbon Fiber).

• 대한인간공학회:학술대회논문집
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• 대한인간공학회 1995년도 추계학술대회논문집
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• pp.41-45
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• 1995

Menu-driven interfaces are frequently employed for user -system interfaces on many electronic products. Due to the space and budget constraint, a single or multi-line display is used to show menu items. Single or Multi-line display present 8 .approx. 21 characters on an LCD screen and users select items using a series of button pushes. Multi-line displays are different from the single-line ones in the following aspects. First, they can present multiple menu items at the same time. Second, they can present menu items in a various way, for example, same-depth presentation, sub-depth presentation, previous selection, etc. In this study, a human factors experiment is being conducted to examine the effects of three independent variables on the design of a multi-line display. Factors investigated include menu structure, number of lines on the display, item presentation methodl. Usability of the multi-line display is being measured quantitatively in terms of four different aspects: task completion time, accuracy, inefficiency, user preference. A set of design guidelines will be drawn from this study which can be applied to usef-system interfaces of a various types of consumer products.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2001년도 가을 학술발표회 논문집
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• pp.59-64
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• 2001

The concrete bridge decks are in need of replacement and rehabilitation due to decreasing load carrying capacity. In this study, to extend life cycle of the concrete bridge decks which are reinforced with the glass fiber sheets, the concrete bridge decks are examined on the strengthen effect and the fatigue behavior. The behavior of strengthened slabs is represented by load-displacement relationship, variation of compliance and total released energy. Owing to result of that, the strengthened slabs is modified the elasticity, the compliance and represents to control the crack elongation, to elevate the total released energy, to modify the fatigue life. When the concrete bridge deck is strengthened, the crack propagation nay be controled efficiently.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2002년도 봄 학술발표회 논문집
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• pp.393-398
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• 2002

This study shows the fatigue test results of experiment on the strengthened slabs, the probability analysis of the fatigue behavior is also presented. Static und fatigue tests were performed on bridge decks strengthened with fiber plastics(Carbon Fiber Sheet, Glass Fiber Sheet, Grid Type Carbon Fiber). In this study, to analyze the probabilistic distribution of the fatigue life, the Weibull distribution was adopted. The Weibull distribution coefficient is inferred from the S-N diagram and the number of repeated load. As the result analysis, as the stress level is higher, the fatigue limit of the strengthened bridge deck are similarly discovered but in the range of the fatigue limit, CG specimen that was strengthened with Grid Type Carbon was proved most effective of reinforcement.

• 한국항해항만학회:학술대회논문집
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• 한국항해항만학회 2007년도 추계학술대회 및 제23회 정기총회
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• pp.325-331
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• 2007

최근 LNG 선박에 승무할 인력의 심각한 부족이 예상되고 있는 가운데, 국내는 물론 국외에서도 인력양성을 위한 교육훈련센터의 개설 등 활발한 움직임이 보이고 있다. 그러나 이러한 LNG 교육훈련센터에서는 독자적으로 개발한 교육훈련 프로그램에 입각하여 교육생을 모집하고 있으며, 따라서 세계적으로 통일된 높은 수준의 교육훈련을 기대하기 어려운 실정이다. 이 발표에서는 국제해사대학연합의 LNG 활동의 일환으로 추진된 아시아 LNG 교육훈련센터의 개요와 센터에서 개발된 표준 교육 훈련 프로그램에 대하여 설명하고자 하며, 이러한 교육훈련과정이 향후 전 세계 LNG 교육훈련의 표준을 정립하는데 초석이 되도록 노력하고자 한다.

• 산업공학
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• 제17권3호
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• pp.375-383
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• 2004

The purpose of this study is to investigate the characteristics of vibration induced by the powered hand tools used in the automobile assembly lines, and estimate the prevalence of vibration syndrome. The acceleration levels of four major powered hand tools were measured using the ISO 5349 method along with the time of exposure to the vibration of the hand tools. Four-hour-energy-equivalent frequency-weighted accelerations ranged from $1.27m/s^2$ to $2.58m/s^2$, After exposure to vibration for 12.6 years, about 10% of the workers using impact ranches were expected to develop Raynaud's disease. For the workers using grinders, 16.6% of the workers were expected to develop Raynaud's disease. The results would be of help in developing the guidelines of local vibration control.

• 한국경영과학회:학술대회논문집
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• 대한산업공학회/한국경영과학회 2000년도 춘계공동학술대회 논문집
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• pp.613-616
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• 2000

This paper considers the problem of subway crew scheduling. Crew scheduling is concerned with finding a minimum number of assignments of crews to a given timetable satisfying various restrictions. Traditionally, crew scheduling problem has been formulated as a set covering or set partitioning problem possessing exponentially many variables, but even the LP relaxation of the problem is hard to solve due to the exponential number of variables. In this paper, we propose two basic techniques that solve the problem in a reasonable time, though the optimality of the solution is not guaranteed. To reduce the number of variables, we adopt column-generation technique. We could develop an algorithm that solves column-generation problem in polynomial time. In addition, the integrality of the solution is accomplished by variable-fixing technique. Computational results show column-generation makes the problem of treatable size, and variable fixing enables us to solve LP relaxation in shorter time without a considerable increase in the optimal value. Finally, we were able to obtain an integer optimal solution of a real instance within a reasonable time.

• 오토저널
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• 제3권2호
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• pp.34-42
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• 1981

The feasibility of using fluidic components for improving certain performance characteristics of the suspension systems for tracked vehicle is investigated. This study describes three variable damping systems for which the damping coefficients are function of relative velocity and absolute a of the vehicle body. Through the comparison analysis between constant damping coefficient damper and each of variable dampers. the followings were found: (1)Fluidic Diode Damper gave less accelerations, (2)Both Fluidic Diode Damper and Relative Velocity Damper gave the less time for which the wheel is off the ground, (3) At low vehicle velocity Fluidic Diode Damper gave low energy dissipation rate, while at high vehicle velocity Turbulence Accelerometer Damper gave low energy dissipation rate.

• 한국항공운항학회지
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• 제15권4호
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• pp.64-82
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• 2007

In this study, the work attitude of flight attendants who were performing emotional labor, had been explored. The organizational support system had been analysed to test its effect as a moderator on increasing positive job attitudes. It was found emotional labor had influence on work attitude of flight attendants. Emotional labor consisted in this study deep acting and surface acting. First, deep acting found positively related with job satisfaction and organizational commitment, negatively related with intention to leave. Second, surface acting negatively related with job satisfaction and positively related with intention to leave. This study put organizational support systems as moderator. First, Training has moderating effect on the relationship between deep acting. Organizational support has moderating effect on the relationship between deep acting, intention to leave. Counselling has moderating effect on the relationship between deep acting, job satisfaction. Peer support has same effect on the relationship between deep acting and intention to leave.