• Magazine of the Korea Concrete Institute
• /
• v.7 no.6
• /
• pp.186-196
• /
• 1995

In this study, parameters such as unit cement weight and placing temperature which influence on temperature rise and temperature rise velocity are investigated through adiabatic tests for the domestic ordinary portland cement(0PC). Adiabatic temperature rise suggested by Korean Concrete Spec. are compared with that from this experimental results. As a result of this study, adiabatic temperature rise of OPC suggested spec. is overestimated. Also it is shown that 2-parameter equation suggested in the spec. overestimate heat evolution at early age and reasonable prediction of heat evolution can be obtained by using 3-parameter equation. Results of numerical analysis by using the input data from this test and the suggested values from spec. shows similar temperatures. However thermal stresses pridicted using input value from spec. may result 20% more than that from this test in case of externally restricted state.

• Journal of the Korea Concrete Institute
• /
• v.16 no.3 s.81
• /
• pp.335-344
• /
• 2004

A general composite section of precast and cast-in-place concrete with prestressed and nonprestressed reinforcements was analyzed to calculate residual stresses and loss of prestressing force caused by internal constraints of concrete long-term deformation. From the analytical results, equations to design additional prestressing force and to evaluate resistant moment of the composite section were proposed. The equations shows that the additional prestressing force can be over-estimated if the loss rate of the first prestressing force is over-estimated from the lumped sum of a design code. The analytical procedure with the proposed equations has been applied to a composite section using the AASHTO Type 5 girder. The loss rates of the additional prestressing force appling to the precast concrete girder was less than those appling to the composite girder. However, the resistant moment of the additional prestressing force on the composite girder was much larger than that on the precast concrete girder. The additional prestressing force appling to the composite section was very effective for strengthening of the prestressed concrete composite girder.

• Journal of the Korean Geotechnical Society
• /
• v.15 no.5
• /
• pp.99-110
• /
• 1999

Settlement and consolidation time were predicted through systematic soil investigation at the delta of Nakdong river where the preloading method was applied. Field measurements were executed with well-selected instruments. As the results of the comparison, the predicted settlement on the sand layer of about 20m thick underestimated the observed one by 20%. This underestimation was due to the effects of vibration during installation of PBD, creep, the overestimated deformation modulus, and so on. For the clay layer of about 20m in thickness under the sand layer, an ID analysis for underconsolidated soil initially overestimated the observed settlement by 240%. However, when the laboratory compression curve was reconstructed and a conventional ID analysis for NC clay was applied, the re-calculated settlement of the clay layer was relatively similar with the observed one. And the predicted consolidation time was about 45% less than the observed one, because of different influencing factors.

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

• Journal of Digital Convergence
• /
• v.14 no.7
• /
• pp.485-496
• /
• 2016

The purpose of this study was to investigate relationships between the appraisal type of competency and aggression in elementary school students. Appraisal type was divided into inflated/deflated ratings. Appraisal type in competencies, and sex were independent variables, and aggression was dependent variables. SPPC, TRS and AS were administered to 419 students and 20 teachers. The major findings of this study were as follows: First, the correlation of child-teacher with perceived competence ratings was the highest in the scholastic competence. Second, frequency of deflated appraisal was the highest in the behavioral conduct. Third, physical aggression is differentiated by the sex. And physical aggression was high when athletic competence was deflated. Fourth, physical aggression, hostility and anger were high when physical appearance was deflated. Fifth, hostility is significantly different by the interaction effect between sex and appraisal type of behavioral conduct. The above findings imply that appraisal type in competencies does not always result in aggression and this study will provide a useful insight for aggression reduction in elementary school students.

• Proceedings of the Computational Structural Engineering Institute Conference
• /
• 2009.04a
• /
• pp.331-334
• /
• 2009

본 논문에서는 계측을 통한 초고층 무량판 구조물의 횡강성 산정식의 유효성을 검정하였다. 초고층 건축물의 풍진동은 건축물의 사용성 평가에 중요한 구조설계요인 중 하나이다. 신뢰성 있는 풍하중 및 풍진동을 얻기위해서는 정확한 고유주기의 예측이 중요하며 고유주기 예측에 오차가 있을 경우 하중을 지나치게 과대평가하게 되는 문제를 유발하게 된다. 본 논문에서는 최근들어 국내에서 본격적으로 증가하고 있는 초고층 무량판 구조시스템의 건축물에 대한 해석 모델링과 실측을 통하여 추정된 무량판 초고층 건물의 동적특성을 바탕으로 구조해석과 동적거동의 계측을 통하여 내풍설계를 위한 횡강성 및 주기를 산정하는 연구를 수행하였다.

• Magazine of the Korea Concrete Institute
• /
• v.1 no.1
• /
• pp.67-74
• /
• 1989

건축물의 고충화, 대형화 및 특수화에 따른 콘크리트의 고강도화는 필수적이다. 그러나 고강도화는 높은 취성파괴 양성을 보여주며, 이들이 전단파괴의 병합될 때 구조체의 안전성에 큰 문제를 던져주고 있다. 본 연구는 고강도 콘크리트(f'c=800㎏/㎠)보가 전단보강이 되어있지 않은 경우 전단강도 및 파괴 양성을 조사하기 위하여 주요변수로서 전단스팬비(a/d)=3.0, 4.0, 6.0그리고 주근비 (ρt)=0.5ρb, 1.0ρb로 하였다. 실험결과, 현재의 건설부 극한강도 구조 규준식이나 ACI규준식은 주근량과 a/d의 효과를 과소평가하고, 콘크리트의 강도 증가에 따른 잇점은 과대평가하고 있는 것으로 판명되었다.

• 프린팅코리아
• /
• v.8 no.5
• /
• pp.76-81
• /
• 2009

지난 2008 한경광고대상 수상작들의 키워드는 '꿈과 희망'이었다. 외환위기 당시보다 더 강도 높은 불안이 밀려오고 있는 이때, 고객들이 가장 갈구하는 것은 '희망과 행복'의 메시지였다. 좋은 광고 역시 고객의 이 같은 마음을 읽어내고 이를 아름다운 화상으로 표현해 내는 것이다. 최근 인쇄광고에 견주어 영상광고의 효과를 과대평가하는 경향이 있다. 기억에 잘 남는 훌륭한 광고는 모두가 인쇄광고다. 그러나 인쇄매체는 영상매체보다 훨씬 힘들다. TV는 조명, 액션, 음악, 댄싱, 옵티칼효과 등 도움을 받을 수 있는 보조 요소가 한두 가지가 아니다. 그러나 인쇄매체보다 훨씬 힘들다. TV는 조명, 액션, 음악, 댄싱, 옵티칼효과 등 도움을 받을 수 있는 보조 요소가 한두 가지가 아니다. 그러나 인쇄매체의 경우에는 제품의 가장 강력한 셀링 포인트만을 찾아내야 한다. 이를 위해서 강력하면서도 재미있고, 또 독자를 끌어들이는 헤드라인을 써야 한다.

• Magazine of the Korea Concrete Institute
• /
• v.10 no.1
• /
• pp.109-118
• /
• 1998

전단거동에 의해 지배되는 고강도 철근콘크리트 춤이 큰 보의 전단역학적 거동 및 전단강도특성을 고려한 이론식을 제시하고자 소성이론에 근거한 극한해석에서 상계치정리를 이용하여 이론적 전개를 하였으며, 고강도 R/C춤이 큰 보의 전단응력에 영향을 미치는 콘크리트 압축강도, 수직전단보강근 및 수평잔단보강근의 보강효과를 고려한 이론식을 제시하였으며, 수평철근 즉 주인장철근 및 수평전단보강근의 장부작용을 고려하였다. 실험결과와 비교할 때 제안식은 수직잔단보강근의 전단보강효과를 과대평가하고있으며, 수평전단보강근의 효과를 적절하게 평가하고 있음을 나타내었다. 또 전단스팬비가 0.5, 0.85인 경우에는 제안식에 의한 값이 다소 낮게 나타내, 전단스팬비가 낮은 경우는 다소 과소평가하는 것으로 나타났다.

• Proceedings of the Korea Concrete Institute Conference
• /
• 2010.05a
• /
• pp.413-414
• /
• 2010

Many researchs shows that modulus of elasticity in manual overestimates real modulus of elasticity of concrete as strength gets higher. In 2007 KCI Manual, formula in modulus of elasticity has revised that it should be demonstrated. In this study, modulus of elasticity in high strength was estimated by experiment and experimental value was compared with manual value.