• Korean Journal of Cognitive Science
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• v.10 no.3
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• pp.17-28
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• 1999

Systematic distortions in perceived 3-D shape were obtained for elliptical and parabolic stereoscopic surfaces viewed at different distances under full and reduced cue conditions. In both conditions of Experiments 1 and 3, elliptical hemi-cylinders a appeared near veridical at the 45 cm viewing distances and flattened up to 74% of veridical at 135 cm. In Experiment 2, under full cue conditions, parabolic hemi-cylinders a appeared stretched to 118% of veridical at 45 cm, near veridical at 90 cm, and flattened to 85% of veridical at 135 cm. Under reduced cue conditions parabolas appeared flatter overall: veridical curvature was obtained at 45 cm viewing distance with flatness increasing to 68% of veridical at 135 cm. Results support a scaling explanation of perceived 3-D shape from disparity and rule out the alternative hypothesis that disparity curvature, an optical invariant, provides information for the direct perception of 3-D s shape.

• The Korean Journal of Financial Studies
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• v.5 no.1
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• pp.19-47
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• 1999

본 연구는 기업가치 추정모형인 EVA모형과 FCFF모형의 적합성을 한국주식시장을 대상으로 검증하는데 목적을 두고 있다. 1992년$\sim$1996년의 5년간 상장기업을 대상으로 분석한 결과는 다음과 같다. 실제주가와 이론주가간에 음(-)의 괴리율을 갖는 집단의 누적평균초과수익률은 EVA 모형 기준인 경우 40일$\sim$60일간에 유의적으로 상승하고 있으며, FCFF모형의 경우 1일$\sim$20일간에 유의적으로 상승하고 있다. 그리고 실제주가와 이론주가간에 양(+)의 괴리율을 갖는 집단의 누적평균초과수익률은 EVA모형 기준인 경우 21일$\sim$40일간에 유의적으로 하락하고 있으며, FCFF모형 기준인 경우 1일$\sim$20일간에 유의적으로 하락하고 있다. 또한 EVA모형과 FCFF모형 모두에서 음(-)의 괴리율집단과 양(+)의 괴리율집단간의 누적평균초과수익률은 기준일 이후 유의적 차이를 보이고 있다. EVA모형과 FCFF모형으로 평가한 결과는 반영시점이 다소 차이가 난다는 점을 제외하고는 상대적으로 과소평가된 주식은 기준일 이후 가격이 상승하고 상대적으로 과대 평가된 주식은 기준일 이후 하락한다는 사실을 보여주고 있다. 이런 사실은 제한적이지만 절대가치평가모형이 한국주식시장에서 어느 정도 적합성을 가질 수 있는 가능성을 보여주고 있다.

• Proceedings of the Korean Nuclear Society Conference
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• 1998.05b
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• pp.612-617
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• 1998

폐부하량 측정에 사용되는 폐 카운터의 교정시 폐내 방사능의 균일분포 가정은 폐부하량 측정결과에 영향을 줄 것으로 예상된다. 따라서 본 연구에서는 균일분포 가정에 따른 측정오차를 평가하기 위해 몬데칼로시뮬레이션을 통해 분포패턴에 따른 계측효율을 구해 이률 비교·분석하였다. 그 결과 균일분포 패턴에 비해 17 keV에서 1.39배, 60 keV에서 1.14배, 185 keV에서 1.12배 까지 폐부하량이 과대평가되는 것으로 밝혀졌다 균일분포를 가정하더라도 문제가 될 정도로 과대평가가 되지 않음을 알 수 있었다. 반면, 과소평가는 17keV에서 50.2배, 60 keV에서 3.6배, 185 keV에서 2.7배 까지 나타나, 에너지가 작을수록 균일분포에 의한 교정에 문제의 심각성이 있는 것으로 보였다.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.40 no.10
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• pp.843-849
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• 2016

It has been shown that the adaptive grasp feature can be implemented by underactuated robotic hands with a minimal number of actuators. Following this approach, a new design of prosthetic hand is presented. A method is proposed for evaluating grasp performance using cylinders, spheres, and square bars of various sizes. The effects of the major design parameters were investigated experimentally and an improved design is proposed.

• Journal of the Korea Concrete Institute
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• v.22 no.4
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• pp.559-566
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• 2010

Fifteen lightweight concrete mixes were tested to evaluate the effect of maximum size of coarse aggregate and the replacement level of natural sand on the various properties of fresh lightweight concrete. The different properties, such as water absorption against the elapsed time, pore size distribution and micro-structure of lightweight aggregates used, influencing on the workability of fresh concrete were also measured. Test results showed that the initial slump of lightweight concrete decreased with the increase of the replacement level of natural sand. The slump of all-lightweight concrete sharply decreased by around 80% of the initial slump after 30~60 minutes. The air content and bleeding rate of lightweight concrete were significantly affected by the replacement level of natural sand as well as the maximum size of coarse aggregates. Empirical equations recommended in ACI 211 and Korea concrete standard specifications underestimated the air content of the lightweight concrete, indicating that the underestimation increases with the decrease of the replacement level of natural sand. In addition, equations to predict the air content and bleeding rate of lightweight concrete were proposed based on the test results.

• Journal of Korean Society of Forest Science
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• v.86 no.1
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• pp.25-34
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• 1997

The optimum global natural vegetation mapping(GNVM) system was selected as a series of the study to estimate potential forest area of the globe. To select the system, three types of GNVM systems which are simple system with Light Climatic Dataset(LCD), altitude-allowed system with LCD and altitude-allowed system with Heavy Climatic Dataset(HCD) were established and compared. The three GNVM systems spherically interpolate such spotty climate data as those observed at weather stations the world over onto $1^{\circ}{\times}1^{\circ}$ grid points, product vegetation type classification, and produce a potential natural vegetation(PNV) map and a PNV area. As a result of comparison with three GNVM systems, altitude-allowed LCD system represented natural vegetation distribution better than other versions. The difference between the simple system versus the one with altitude allowance indicated that the simple version tends to over-represent the warmer climate areas and under-represent cold and hostile climate areas. In the difference between altitude-allowed versions of LCD and HCD, HCD version tended to overestimate moist climate areas and to underestimate dry climate areas.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.26 no.4D
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• pp.593-600
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• 2006

Joint opening of jointed concrete pavement is caused by change in temperature and humidity of adjoined slab. The magnitude of joint opening influences on the load-transfer-efficiency and the behavior of sealant. If temperature or humidity decreases, joint opening increases. Generally maximum joint opening of a given joint is predicted by using AASHTO equation. While different magnitudes of joint opening at the individual joints have been observed in a given pavement section, AASHTO equation is limited to predict average joint opening in a given pavement section. Therefore the AASHTO equation may underestimate maximum joint for the half of joint in a given pavement section. Joints showing larger opening than the designed may experience early joint sealant failure, early faulting. Also unexpected spalling may be followed due to invasion of fine aggregate into the joints after sealant pop-off. In this study, the variation of the joint opening in a given pavement section was investigated based on the LTPP SMP data. Factors affecting on the variation are explored. Finally a probabilistic joint opening model is developed. This model can account for the reliability of the magnitude of joint opening so that the designer can select the ratio of underestimated joint opening.

• Computational Structural Engineering
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• v.5 no.3
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• pp.139-146
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• 1992

Vibrational behaviors of highway girder bridges due to heavy traffics are discussed, and empirical formulae for impact factors are suggested in this paper. Appropriate vehicle model for vibration analysis is found and impact factors are calculated with different surface roughnesses, vehicle speeds and span lengths. It is shown that the present codes tend to underestimate impact factors.

• Proceedings of the Korean Environmental Sciences Society Conference
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• 2008.11a
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• pp.79-81
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• 2008

동아시아 지역의 대기오염물질의 장거리 이동에 대한 한중일 3국의 모델링의 결과를 비교 분석한 결과, 일본의 경우 한국에서 사용한 모델링의 결과보다 SO$_2$와 SO$_4$ 농도장 모두 과소평가되어 나타남을 볼 수 있었다. 이는 각 나라마다 모델에 적용한 기상장이 다르고, 서로 다른 모델을 사용하였기 때문에 차이가 나는 것으로 판단된다. 추후 중국의 모델링 결과도 함께 분석하여 보다 정확한 모델의 검정을 할 것이며, 황의 침적량에 대한 영향도 분석할 예정이다.

• Proceedings of the Korean Institute of Industrial Safety Conference
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• 1997.05a
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• pp.91-94
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• 1997

반도체의 생산공정은 생산제품의 특성상 많은 종류의 위험물과 가스를 이용하는 것이 보통이지만, 자동화가 이루어진 대부분의 작업공정과는 달리, 작업자에 의해 직접 이루어지는 것이 보통이다. 이때 작업자의 사소한 실수나 과오로 인해 일단 누출등의 사고가 발생하면, 취급물질 자체의 위험성으로 인해 인명 피해, 화재 및 폭발 둥의 2차 대형재해를 초래할 수 있기 때문에, 반도체공장의 어느 누구도 그 위험성에 대해 과소평가하지 않는 것이 현실이다. (중략)