• 대한토목학회논문집
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• 제28권3D호
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• pp.363-369
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• 2008

건설공사의 특성상 공사중 설계변경이 불가피한 경우가 많다. 문제는 설계변경의 양과 정도에 따라 작업생산성 저하를 초래 할 수 있다는 것인데, 이를 설계변경의 파급효과(Ripple effect) 또는 누적영향(Cumulative impact)이라 한다. 미국과 달리 국내의 경우 설계변경의 영향에 대한 연구를 찾아보기 힘든 것이 사실이다. 본 연구는 공공공사 설계변경의 현황과 그 영향을 조사하기 위하여 1991년도부터 2004년도까지 수행된 14개 공공기관의 공사비 100억 이상 공사 1439건의 설계변경 데이터를 수집, 분석하였다. 국내 공공공사 설계변경의 특성을 파악하기 위하여 평균낙찰률, 설계변경규모, 설계변경횟수, 설계변경금액 등을 분석하였으며, 설계변경이 미치는 영향을 파악하기 위하여 변경률(%CO), 손실률(%Delta), 지연률(%T) 등의 개념을 정립하였다. 개발된 변경률, 손실률, 지연률 등의 개념을 수집된 설계변경 자료에 적용 사례조사를 하였으며, 이를 바탕으로 낙찰률과 설계변경량의 관계, 설계변경횟수와 공사지연간의 관계, 공기지연과 손실률간의 관계, 설계변경량과 손실률간의 관계를 도출하였다. 결과적으로 설계변경횟수가 많아질수록 공기가 더욱 지연될 수 있으며, 지연된 공기는 더 많은 손실을 발생시킬 수 있음이 증명 되였다. 또한 설계변경의 양이 많아질수록 손실량도 증가하며 서로간 강한 상관관계가 있음을 발견하였다. 본 연구에서 도출된 관계식들은 공사금액을 바탕으로 개발되었기에 프로젝트의 생산성손실 분석을 위한 직접적인 적용은 어렵다. 하지만 향후 국내 주요건설사들이 추진하고 있는 작업일보시스템에 작업시간(Man-hour)기반의 생산성 자료들이 축척되면 추후 그 데이터를 바탕으로 국내 환경에 적합한 생산성측정모델 구축이 가능하리라 판단된다. 아울러, 공사중 작업생산성 관련 자료의 관리를 선진화 하고, 그 신빙성을 높이는 일은 우리 건설계 모두의 노력이 필요하리라 사료된다.

• 한국해양공학회지
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• 제22권6호
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• pp.35-40
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• 2008

The effect of counterpart roughness on abrasive wear characteristics of side plate materials of FRP ship, which were composed of glass fiber and unsaturated polyester resin composites, were investigated at ambient temperature by pin-an-disc friction test. The friction coefficient, wear rate and cumulative wear volume of these materials against SiC abrasive paper were determined experimentally. The wear rate of these materials decreased rapidly with sliding distance and then maintained a constant value. It was increased as counterpart roughness was rougher in a wear test. The cumulative wear volume tended to increase nonlinearly with sliding distance and depended on applied load and sliding speed for these composites. It could be verified by SEM photograph of fracture surface that major failure mechanisms were overlapping layers, microcutting, deformation of resin, delamination, and cracking.

• Earthquakes and Structures
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• 제1권1호
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• pp.69-91
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• 2010

Current seismic design codes do not contemplate explicitly some variables that are relevant for the design of structures subjected to ground motions exhibiting large energy content. Particularly, the lack of explicit consideration of the cumulative plastic demands and of the degradation of the hysteretic cycle may result in a significant underestimation of the lateral strength of reinforced concrete structures built on soft soils. This paper introduces and illustrates the use of a numerical performance-based methodology for the predesign of standard-occupation reinforced concrete ductile structures. The methodology takes into account two limit states, the performance of the non-structural system, and in the case of the life safety limit state, the effect of cumulative plastic demands and of the degradation of the hysteretic cycle on the assessment of structural performance.

• 수산해양기술연구
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• 제44권3호
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• pp.250-256
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• 2008

Generally the side plate materials of FRP ship are composed of glass fiber and unsaturated polyester resin composites(GFRP composites). In this study, the effect of applied load and sliding speed on friction and wear characteristics of these materials were investigated at ambient temperature by pin-on-disc friction test. The cumulative wear volume, friction coefficient and wear rate of these materials for SiC abrasive paper were determined experimentally. The cumulative wear volume showed a tendency to increase nonlinearly with increase of sliding distance and was dependent on applied load and sliding speed for these composites. The friction coefficient of GFRP composites was increased as applied load increased at same sliding speed in wear test. It was verified by SEM photograph of worn surface that major failure mechanisms were microfracture, deformation of resin, cutting and cracking.

• 한국강구조학회 논문집
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• 제9권1호통권30호
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• pp.95-105
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• 1997

Structures subjected to strong seismic excitation may undergo inelastic deformation cycles. The resulting cumulative fatigue damage process reduces the ability of structures and components to withstand seismic loads. Yet, the present earthquake resistance design methods focus mainly on the maximum displacement ductility, ignoring the effect of the cyclic responses. The damage parameters closely related to the cumulative damage need to be properly reflected on the aseismic design methods. In this study, two cumulative damage assessment methods derived from the plastic fatigue theory are investigated. The one is based on the hysteretic ductility amplitude, and the other is based on the dissipated hysteretic energy. Both methods can consider the maximum ductility and the cyclic behavior of structural response. The validity of two damage methods has been examined for single degree of freedom structures with various natural frequencies against two different earthquake excitations.

• 한국산학기술학회논문지
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• 제13권4호
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• pp.1640-1647
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• 2012

본 연구는 2007년 1월부터 2009년 12월까지 3년간 코스닥기업의 유상증자 형태 중 제3자 배정을 통해 대금을 납입한 81개 기업 197건에 대하여 사건연구를 통해 납입 전, 후의 주가반응을 비교분석하였고, 더 나아가 누적초과수익률에 영향을 미치는 요인이 무엇인지를 다중회귀분석을 통해 파악하였다 본 연구의 결과를 요약하면 다음과 같다. 첫째, (-5, +5) 초과수익률은 납입일 5일전부터 1일전까지 1% 수준에서 유의적인 정(+)의 초과수익률을 보이는 것으로 나타났고, 사건일인 납입 일에는 유의적인 초과수익률이 존재하지 않는 것으로 나타났다. 납입일 이후 5일 동안은 1% 유의수준에서 부(-)의 초과수익률을 보였다. 둘째, 납입일 전, 후 40일간(-40, +40)의 초과수익률은 납입일 전 40일 동안 1% 수준에서 유의적인 정(+)의 초과수익률을 나타냈으며, 납입일 이후 40일 동안 1% 수준에서 유의적인 부(-)의 초과수익률을 보였다. 셋째, 납입일 이후 1년간(0, 1년)의 초과수익률은 1% 수준에서 유의적인 부(-)의 초과수익률을 보였다. 넷째, (-5, +5)까지의 누적초과수익률에 영향을 미치는 요인은 기업규모로 정(+)의 영향을 미쳤으며, 10% 유의수준에서 유의적이었다. 유보율과 부채비율은 (-40, +40)의 누적초과수익률에 10% 유의수준에서 유의적으로 각각 정(+)과 부(-)의 영향을 미치는 것으로 나타났다. (0, 1년)의 누적초과수익률에 영향을 미치는 요인은 기업규모, 부채비율, 대주주지분율은 각각 1%, 5%, 10% 유의수준에서 유의적인 부(-)의 영향을, 유보율은 1% 유의수준에서 유의적으로 정(+)의 영향을 미치는 것으로 나타났다.

• The Korean Journal of Physiology and Pharmacology
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• 제4권6호
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• pp.479-486
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• 2000

The aim of this study was to clarify the mechanism of the inhibitory action of carbon monoxide (CO) on contraction, by measuring cytosolic $Ca^{2+}$ level $([Ca^{2+}]_i)$ and ionic currents in guinea-pig ileum. CO (10%) inhibited 40 mM KCl-induced contraction and this effect was blocked by ODQ $(1\;{\mu}M),$ a soluble guanylyl cyclase (sGC) inhibitor. CO inhibited the 40 mM KCl-induced contraction without changing $[Ca^{2+}]_i.$ Cumulative addition of KCl induced a graded increase in $[Ca^{2+}]_i$ and muscle tension. In the presence of CO, cumulative addition of KCl induced smaller contraction than in the absence of CO. On the other hand, the increase in $[Ca^{2+}]_i$ induced by cumulative addition of KCl was only slightly decreased in the presence of CO, and the $[Ca^{2+}]_i-tension$ relationship shifted downwards. Using the patch clamp technique with a holding potential of -60 mV, we found that CO had little effect on the peak Ba currents $(I_{Ba})$ when voltage was stepped from -60 mV to 0 mV. In addition, CO showed no effect on the depolarization-activated outward $K^+$ currents in the all potential ranges. We conclude that CO inhibits smooth muscle contraction mainly by decreasing the $Ca^{2+}$ sensitivity of contractile elements via a cGMP-dependent pathway, not by involving L-type $Ca^{2+}$ and outward-potassium currents in guinea-pig ileum.

• Asian-Australasian Journal of Animal Sciences
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• 제18권2호
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• pp.185-191
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• 2005

An experiment was conducted to study the effect of feeding ammoniated wheat straw treated with HCl on blood biochemical profiles in growing male buffalo (Bubalus bubalis) calves. Twenty-four growing male buffalo calves (one year of age, 88.54${\pm}$3.81 kg average body weight) were divided into three groups in a completely randomized design on the basis of their body weight. Animals in all the three groups were fed on concentrate mixture. In addition, they were offered wheat straw, ammoniated wheat straw (4% urea at 50% moisture level) and HCI treated ammoniated wheat straw (4% urea at 50% moisture level and HCl added to trap 30% of the NH3 evolved) in groups I, II and III, respectively for a period of 180 days, as per Kearl (1982) for body weight gain of 500 g/d. In all diets, concentrate:roughage ratio was fixed at 50:50 and were made isonitrogenous by adjusting CP levels of conc. mixtures. Blood was collected from jugular vein of each buffalo calf at the beginning and subsequently at two months interval of experimental feeding. Due to urea-ammoniation, the CP content of wheat straw increased from 2.90 to 6.96% and addition of HCl along with urea further increased the CP content to 10.09%. In all the three groups, the mean values of plasma glucose (mg %) and serum globulin (g %), showed a decreasing trend, while the mean value of serum TP (g %), serum A:G ratio, serum urea (mg %), serum creatinine (mg %), serum ALP (KA units), SGOT (units/ml.), SGPT (units/ml), serum T$_3$ and T$_4$ (ng/ml) showed an increasing trend with the advancement of feeding period. The cumulative period mean values of serum TP (6.15 to 6.20 g %), serum albumin (3.07 to 3.18, g %), serum globulin (2.98 to 3.09, g %), serum A:G ratio (1.03 to 1.10), serum ALP (23.15 to 23.63, KA units), serum T$_3$ (1.20 to 1.23 ng/ml) and serum T$_4$ (21.33 to 21.88 ng/ml) were comparable among the groups. The cumulative period mean plasma glucose (mg %) in group III (57.28) was similar to groups I (55.31) and II (59.41), however, the cumulative period mean plasma glucose in group II was significantly (p<0.01) higher than group I. The cumulative period mean serum urea (mg %) in group III (47.34) was significantly (p<0.001) higher than group I (38.38) and II (42.24), which were statistically alike. However, the cumulative period mean serum creatinine values (mg %) in groups II (1.43) and III (1.52) were similar and were significantly (p<0.01) higher than group I (1.24). The cumulative period mean SGOT (units/ml) in groups I, II and III was 91.71, 96.04 and 96.64, respectively. Similarly the cumulative period mean SGPT (units/ml) was 19.00, 19.93 and 20.01 in groups I, II and III, respectively. The cumulative period mean values of SGOT (p<0.05) and SGPT (p<0.001) in groups II and III were similar and were significantly higher than group I. The cumulative period mean serum T$_3$ and T$_4$ values in groups I (1.21 and 21.81), II (1.23 and 21.42) and III (1.20 and 21.33) were comparable. From the present study it may be concluded that feeding of AWS treated with and without HCI to growing male buffalo calves for 180 days had no significant adverse effect on blood biochemical profile.

• Journal of Acupuncture Research
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• 제29권1호
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• pp.61-66
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• 2012

Objectives : The purpose of this study was to examine the duplicate effect of thread-embedding therapy against obesity. Methods : 5 women from 20 to 30 with obesity were treated with thread-embedding therapy and compared the results with physical measurement, body composition tests and fat thickness measured by ultrasound. Results : The thread-embedding therapy locally reduced body size and fat thickness and had a cumulative effect, but showed the greatest effect in the abdominal region. It didn't affect to the overall change of body composition. Conclusions : The duplicate procedure of thread-embedding therapy for obesity had a cumulative effect, but it depended on the treatment region.

• The Korean Journal of Ecology
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• 제8권2호
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• pp.61-68
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• 1985

The modeling of interception and absorption of light was studied in plant canopies at Mt. Kwanak. Followering results were obtained. Light intensity passing through the stacked leaves is attenuated exponentially. This phenomenon seems to be more clearly applied to the plant canopies, if they have large cumulative leaf area and are matured densely. Light interception and absorption are influenced by leaf thickness, shape pigments, and leaf area, and they have great effect on the maturation of canopies. It was confirmed that the light penetrating through the stratified canopies is decreased exponentially in dual pattern. The cumulative leaf area of a definite space in a certain plant canopy is the same as the growth of leaf area of the canopy at that time. A hypothetical model for calculating the light absorption in plant canopies, was established on the bases of phenomena that incident light is captured at the maximum level and light inerception effect is minimized by leaves.