• 상하수도학회지
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• 제25권6호
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• pp.877-884
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• 2011

Although peak loading coefficient is one of critical design factors for sewer works, its detailed affecting factors were not analyzed because of limited data availability. This study analyzed the affecting factors on peak loading coefficient with plenty data obtained from several newly constructed sewer works. Simple and multiple regression analysis methods were adopted to analyze the relationships of each variable with or without data filtering. Drainage population, drainage area, population density, and daily sewage flow per person showed very weak relationships under diverse characteristics of cities. However, daily sewage flow per person showed stronger relationships with peak loading when daily sewage flow per person was splitted into two ranges. Population density (i.e., drainage population divided by drainage area) and daily sewage flow per person considerably were related with peak loading coefficient when daily sewage flow per person is less than about 400 Lpcd.

• 상하수도학회지
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• 제18권1호
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• pp.49-58
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• 2004

This study is to analyze the affecting factors to the peak factor in the drinking water supply Facilities. The peak factor is a very important element to determine the capacity of the water supply facllities. Several factors such as Population served, average day water demand, ratio of domestic water use, ratio of affairs & business water use and water use per capital per day were selected as the affecting factors in this study. In this study, peak factor characteristics for Korean facilities were compared with those for Japanese ones. As a result, non-exceedance probability was suggested as the designing method for the peak factor. Also, the 50% non-exceedance probability values and the 90% values based on the 1998-1999 data were suggested in this study.

• 한국산학기술학회논문지
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• 제14권2호
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• pp.786-792
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• 2013

본 연구는 조영제 peak time에 영향을 주는 주된 생체 요인를 분석하여 검사에 적용함으로써 추가적인 조영제 주입에 따른 부작용을 최소화 하고 고해상도의 혈관영상을 유지하는 방안을 모색하고자 하였다. 시험적조영제주입법을 이용한 48명의 환자를 대상으로, 검사 전과 검사 중 환자의 생체 요인을 측정한 후, 조영제 peak time과 상관관계를 알아보고, 회귀식을 이용해 산출한 조영제 peak time이 측정된 조영제 peak time과 일치하는지 Bland-Altman plot를 통해 평가하였다. 연구결과, 검사 시 최저혈압과 심박동수가 조영제 peak time과 유의한 음의 상관관계를 보였고, 1단계 증가할 때마다 평균적으로 조영제 peak time은 -0.018과 -0.159로 유의하게 감소하였으며, 일치도가 상당히 높아 두 방법의 차이가 없음을 알 수 있다. 결론적으로 본 연구의 회귀식을 이용하면 우수한 화질을 유지하면서 환자에게 투여되는 조영제 사용량을 줄일 수 있어 기존의 방법을 대체할 수 있으리라 사료된다.

• 한국ITS학회 논문지
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• 제15권3호
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• pp.12-22
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• 2016

보행은 일상생활에서 행해지는 가장 기본적인 이동수단으로 보행에 대한 관심과 이를 활성화시키고자 하는 노력이 지속적으로 증가하고 있다. 이에 본 연구에서는 구조방정식을 이용하여 보행량에 영향을 미치는 여러 요인들 간의 관계를 규명하고자 하였다. 본 연구에서는 하루 전체시간, 비첨두시간, 첨두시간으로 분류하여 시간대 별로 요인들이 보행량에 미치는 영향의 변화를 비교 분석하였다. 분석결과 상업 업무요인, 접근성요인, 보행환경요인이 보행량을 증가시키는 요인으로 작용하는 것으로 나타난 반면, 주거요인은 보행량을 증가시키는데 기여하지 못한다는 결과를 도출하였다. 또한 비첨두시간에는 하루 전체시간보다 상업 업무요인의 가중치가 증가한 반면 주거요인, 접근성요인, 보행환경요인의 가중치는 상대적으로 감소하였다. 첨두시간의 경우 비첨두시간과는 달리 하루 전체시간보다 상업 업무요인의 가중치가 감소하였으며 나머지 세 요인의 가중치는 증가한 것으로 나타났다.

• Wind and Structures
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• 제30권3호
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• pp.219-229
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• 2020

Net pressures on roofs and walls of buildings are dependent on the internal and external pressure fluctuations. The variation of internal and external pressures are influenced by the size and location of the openings. The correlation of external and internal pressure influences the net pressures acting on cladding on different parts of the roof and walls. The peak internal and peak external pressures do not occur simultaneously, therefore, a reduction can be applied to the peak internal and external pressures to obtain a peak net pressure for cladding design. A 1:200 scale wind tunnel model study was conducted to determine the correlations of external and internal pressures and effective reduction to net pressures (i.e., net pressure factors, F_C) for roof and wall cladding. The results show that external and internal pressures on the windward roof and wall edges are well correlated. The largest ${\mathcal{C}}_{{\check{p},net}$, highest correlation coefficient and the highest F_C are obtained for different wind directions within 90° ≤ θ ≤ 135°, where the large openings are on the windward wall. The study also gives net pressure factors F_C for areas on the roof and wall cladding for nominally sealed buildings and the buildings with a large windward wall opening. These factors indicate that a 5% to 10% reduction to the action combination factor, K_C specified in AS/NZS 1170.2(2011) is possible for some critical design scenarios.

• Wind and Structures
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• 제23권4호
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• pp.275-300
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• 2016

Synchronous multi-pressure measurements were carried out with relatively long time duration for a double-layer reticulated shell roof model in the atmospheric boundary layer wind tunnel. Since the long roof is open at two ends for the storage of coal piles, three different testing cases were considered as the empty roof without coal piles (Case A), half coal piles inside (Case B) and full coal piles inside (Case C). Based on the wind tunnel test results, non-Gaussian time-dependent statistics of net wind pressure on the shell roof were quantified in terms of skewness and kurtosis. It was found that the direct statistical estimation of high-order moments and peak factors is quite sensitive to the duration of wind pressure time-history data. The maximum value of COVs (Coefficients of variations) of high-order moments is up to 1.05 for several measured pressure processes. The Mixture distribution models are proposed for better modeling the distribution of a parent pressure process. With the aid of mixture parent distribution models, the existing translated-peak-process (TPP) method has been revised and improved in the estimation of non-Gaussian peak factors. Finally, non-Gaussian peak factors of wind pressure, particularly for those observed hardening pressure process, were calculated by employing various state-of-the-art methods and compared to the direct statistical analysis of the measured long-duration wind pressure data. The estimated non-Gaussian peak factors for a hardening pressure process at the leading edge of the roof were varying from 3.6229, 3.3693 to 3.3416 corresponding to three different cases of A, B and C.

• 한국재난정보학회 논문집
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• 제20권2호
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• pp.440-447
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• 2024

연구목적: 국내의 차량 등록 대수는 계속 증가하고 있다. 삶의 질 향상으로 인한 교통량 또한 점진적으로 증가하므로 사고 심각도가 증가 및 혼잡문제 또한 야기될 것으로 예상된다. 따라서, 첨두 교통사고와 비첨두 교통사고의 사고 요인을 분석할 필요가 있다고 판단된다. 연구방법:인천광역시의 첨두 및 비첨두 교통사고의 심각도를 첨두와 비첨두로 나누어 분석하여 사고에 영향을 미치는 요인을 알아보고자 한다. XGBoost 머신러닝 기법을 적용하여 첨두 및 비첨두 교통사고 심각도를 분석하였으며 결과를 통하여 plot으로 시각화하였다. 연구결과:첨두시 피해운전자 차종_승합인 경우 등 비 첨두시는 피해운전자 차종_건설기계 등이 사고 심각도를 높이게 되는 변수인 것으로 분석되었다. 결론: 첨두와 비첨두 사고 심각도의 요인을 도출한 것에 의의가 있고 추후 첨두 및 비첨두시의 사고 심각도를 낮추고 국내 교통의 혼잡 요인을 분석하여 혼잡 비용을 줄일 수 있는 것에 활용되기를 바란다.

• Journal of Biosystems Engineering
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• 제40권1호
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• pp.78-88
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• 2015

Purpose: The objective of this study is to review researches regarding factors that potentially affect adolescent calcium (Ca) metabolism, and to suggest a potential modeling approach for optimizing gastrointestinal Ca absorption and peak bone mass. Background: Optimal gastrointestinal Ca absorption is a key to maximizing peak bone mass in adolescents. Urine Ca excretion in adolescents rises only after bone accretion is saturated, indicating that higher intestinal Ca absorption and bone retention is necessary to ensure maximum bone accretion. Hence, maximizing peak bone mass is possible by controlling the factors influencing gastrointestinal Ca absorption and bone accretion. However, a mechanism that explains the unique adolescent Ca metabolism has not yet been elucidated. Review: Dietary factors that enhance gastrointestinal Ca absorption may increase the available Ca pool usable for bone accretion, and a specific hormone may direct optimal Ca utilization to maximize peak bone mass. IGF-1 is an endocrine hormone whose levels peak during adolescence and increase fractional Ca absorption and bone Ca accretion. Prebiotics, generally obtained from dietary sources, have been reported to exert a beneficial effect on Ca absorption via microbiota activity. We selected and reviewed three candidates that could be used to propose a comprehensive Ca metabolic model for optimal Ca absorption and peak bone mass in adolescents. Modeling: Modeling has been used to investigate Ca metabolism and its regulators. Herein, we reviewed previous Ca modeling studies. Based on this review, we proposed a method for developing a comprehensive model that includes regulatory effectors of IGF-1 and prebiotics.

• Structural Engineering and Mechanics
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• 제74권3호
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• pp.351-363
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• 2020

Based on the dynamic tests of recycled aggregate concrete (RAC) short columns confined by the hoop reinforcement, the dynamic failure mechanism and the mechanical parameters related to the constitutive relation of confined recycled aggregate concrete (CRAC) were investigated thoroughly. The fracturing sections were relatively flat and smooth at higher strain rates rather than those at a quasi-static strain rate. With the increasing stirrup volume ratio, the crack mode is transited from splitting crack to slipping crack constrained with large transverse confinement. The compressive peak stress, peak strain, and ultimate strain increase with the increase of stirrup volume ratio, as well as the increasing strain rate. The dynamic confining increase factors of the compressive peak stress, peak strain, and ultimate strain increase by about 33%, 39%, and 103% when the volume ratio of hoop reinforcement is increased from 0 to 2%, but decrease by about 3.7%, 4.2%, and 9.1% when the stirrup spacing is increased from 20mm to 60mm, respectively. This sentence is rephrased as follows: When the stirrup volume ratios are up to 0.675%, and 2%, the contributions of the hoop confinement effect to the dynamic confining increase factors of the compressive peak strain and the compressive peak stress are greater than those of the strain rate effect, respectively. The dynamic confining increase factor (DCIF) models of the compressive peak stress, peak strain, and ultimate strain of CRAC are proposed in the paper. Through the confinement of the hoop reinforcement, the ductility of RAC, which is generally slightly lower than that of NAC, is significantly improved.

• 한국방재학회 논문집
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• 제11권1호
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• pp.7-13
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• 2011

지진에 대한 장대 교량의 정확한 반응 해석은 지진 방재에 있어서 중요한 역할을 한다. 본 논문은 비동기 다지지점 지진입력에 의한 교량의 반응을 진동수 영역방법과 시간 영역방법으로 해석하였으며 그 결과를 동기 입력 결과와 비교하였다. 시간영역방법에서는 선형모드 중첩 법으로 최대반응 값을 계산하였다. 진동수영역방법에서는 선형랜덤진동 이론을 사용하여 교량 성능에 영향을 미치는 모드와 다지지점 지진입력의 상호상관관계를 고려한 반응의 제곱평균근(RMS값)을 계산하였다. 교량 성능 반응 중, 변위 및 부재의 내력에 대한 시간 영역해석 결과와 진동수영역 해석 결과로부터 최대반응 값과 RMS값의 비로 정의된 최대반응 계수의 실용적인 값과 계산 방법을 요약하였다. 신뢰 있는 최대 반응계수가 있으면, 교량의 성능기반설계에서 구체적인 임의의 입력을 고려한 시간영역방법보다 결과의 일반성 및 수치적인 장점을 갖은 진동수영역방법이 더 효율적이다.