• 한국안전학회지
• /
• 제19권3호
• /
• pp.78-83
• /
• 2004

The channel-type lining board that partial welded on many partition frames is used to normal servicing lining board type. On this study is to investigate existing channel-type lining board's capacity by using the static loading test. From this study, to develop new-type lining board which reflect well cross section area and sectional modulus of existing channel-type lining board. Six types FEM model are adopted. The accumulated test results of stress conditions and deflections by section shapes will be used to analyzed the relation between the capacity and the section shape. With the comparing the results of static loading test and FEM analysis.

• 상하수도학회지
• /
• 제18권2호
• /
• pp.137-144
• /
• 2004

In this study, several series of experiments were conducted to investigate the phosphorus (P) removal process in slag-containing solution using furnace and converter slags. High amount of $OH^-$, $Ca^{2+}$ and alkalinity were discharged from the slags and hydroxyapatites [$Ca_5(PO_4)_3(OH)$] were kept accumulated on the surface of slag. P removal capacity of the slag decreased with the increase of slag dosage. The maximum capacity was found to be 11.25 mg/g at the converter slag. Converter slag adsorbed P more than furnace slag(about four times in average). An experimental study on the effect of pH shows that the percentage removal of P increased upto 30% at the pH range of 56 than that of above pH 8. Langmuir isotherm constants gave a better correlation than Freundlich ones. P removal amount in the presence of $NH^+_4$ was less compared to the one in the absence of $NH^+_4$. Maximum percentage reduction was 23%.

• 동력기계공학회지
• /
• 제10권1호
• /
• pp.34-40
• /
• 2006

The snow melting system by electric heating wires which is adopted in this study is a part of road facilities to keep surface temperature of the road higher than freezing point of water for melting the snow accumulated on it. The system is designed to increase traffic safety and capacity. The electric heating wires are buried under paved road at a certain depth and operated automatically and manually. Design theory, amount of heating, and installation standard vary according to economic situation, weather condition, and installation place where the system applies. It is tried to figure out that the appropriate range of required heat capacity and installation depth and intervals for solving snowdrifts and freezing problems with the minimum electric power consumption. The most important factors to design the system are calculation of heating capacity depending on weather condition and depth and interval of the electric heating wires depending on air condition respectively. The study were performed under the range of the air temperatures($-2^{\circ}C,\;-5^{\circ}C,\;-8^{\circ}C$), the intervals of the electric heating wires(70mm, 100mm, 125mm), and the installation depths(50mm, 70mm, 100mm). The ready made commercial program package was used to verify the experimental results.

• Structural Engineering and Mechanics
• /
• 제71권4호
• /
• pp.417-432
• /
• 2019

Seismic performance analysis of steel-brace reinforced concrete (RC) frame using topology optimization in highly seismic region was discussed in this research. Topology optimization based on truss-like material model was used, which was to minimum volume in full-stress method. Optimized bracing systems of low-rise, mid-rise and high-rise RC frames were established, and optimized bracing systems of substructure were also gained under different constraint conditions. Thereafter, different structure models based on optimized bracing systems were proposed and applied. Last, structural strength, structural stiffness, structural ductility, collapse resistant capacity, collapse probability and demolition probability were studied. Moreover, the brace buckling was discussed. The results show that bracing system of RC frame could be derived using topology optimization, and bracing system based on truss-like model could help to resolve numerical instabilities. Bracing system of topology optimization was more effective to enhance structural stiffness and strength, especially in mid-rise and high-rise frames. Moreover, bracing system of topology optimization contributes to increase collapse resistant capacity, as well as reduces collapse probability and accumulated demolition probability. However, brace buckling might weaken beneficial effects.

• Journal of Preventive Medicine and Public Health
• /
• 제46권sup1호
• /
• pp.3-11
• /
• 2013

Over the last two decades, significant research attention has been given to the acute effect of a single bout of exercise on postprandial lipaemia. A large body of evidence supports the notion that an acute bout of aerobic exercise can reduce postprandial triacylglycerol (TAG) concentrations. However, this effect is short-lived emphasising the important role of regular physical activity for lowering TAG concentrations through an active lifestyle. In 1995, the concept of accumulating physical activity was introduced in expert recommendations with the advice that activity can be performed in several short bouts throughout the day with a minimum duration of 10 minutes per activity bout. Although the concept of accumulation has been widely publicised, there is still limited scientific evidence to support it but several studies have investigated the effects of accumulated activity on health-related outcomes to support the recommendations in physical activity guidelines. One area, which is the focus of this review, is the effect of accumulating exercise on postprandial lipaemia. We propose that accumulating exercise will provide additional physical activity options for lowering postprandial TAG concentrations relevant to individuals with limited time or exercise capacity to engage in more structured forms of exercise, or longer bouts of physical activity. The benefits of accumulated physical activity might translate to a reduced risk of cardiovascular disease in the long-term.

• International Journal of Contents
• /
• 제15권3호
• /
• pp.32-38
• /
• 2019

We usually suffer from difficulties in treating or managing Big Data generated from various digital media and/or sensors using traditional mining techniques. Additionally, there are many problems relative to the lack of memory and the burden of the learning curve, etc. in an increasing capacity of large volumes of text when new data are continuously accumulated because we ineffectively analyze total data including data previously analyzed and collected. In this paper, we propose a general-purpose classifier and its structure to solve these problems. We depart from the current feature-reduction methods and introduce a new scheme that only adopts changed elements when new features are partially accumulated in this free-style learning environment. The incremental learning module built from a gradually progressive formation learns only changed parts of data without any re-processing of current accumulations while traditional methods re-learn total data for every adding or changing of data. Additionally, users can freely merge new data with previous data throughout the resource management procedure whenever re-learning is needed. At the end of this paper, we confirm a good performance of this method in data processing based on the Big Data environment throughout an analysis because of its learning efficiency. Also, comparing this algorithm with those of NB and SVM, we can achieve an accuracy of approximately 95% in all three models. We expect that our method will be a viable substitute for high performance and accuracy relative to large computing systems for Big Data analysis using a PC cluster environment.

• 한국강구조학회 논문집
• /
• 제17권5호통권78호
• /
• pp.605-615
• /
• 2005

수평하중을 받는 콘크리트충전 각형강관 기둥의 축력과 변형능력의 관계를 조사하기 위하여 실험 및 해석적 연구를 수행하였다. 36개 기둥으로 구성된 실험 시리즈는 일정 축하중과 수평하중 하에서 반복실험을 실시하였다. 반복 수평하중을 받는 기둥이 저항할 수 있는 축하중을 보증내력 한계축력이라고 규정하였으며, 해석 모델은 수평하중을 받는 캔틸레버 기둥을 모델화하였다. 반복 횡하중을 받는 기둥의 축하중을 누적보증내력 한계축력이라고 정의하였다. 본 연구의 목적은 주어진 동일부재각에 부합하는 축력과 수평하중을 받는 콘크리트 충전강관 기둥의 보증내력 한계축력을 연구하기 위한 것이며, 두 번째는 콘크리트 충전강관 기둥의 누적보증내력 한계축력과 보증내력 한계축력의 비교가 본 연구의 목적이다.

• 한국철도학회논문집
• /
• 제11권3호
• /
• pp.317-325
• /
• 2008

최근 연구결과 레일연마 및 장대레일화로 누적통과톤수에 의한 레일교체기준의 연장이 가능한 것으로 보고되었다. 본 연구에서는 현재 도시철도에서 사용 중인 대표 궤도구조에 대해 실운행 열차하중에 의한 궤도의 동적 응답을 분석하여 현 궤도의 상태평가를 하였으며 궤도의 상태 변화에 따른 레일의 부담력을 검토하였다. 또한, 측정된 응력파형을 Rainflow Count Method를 이용하여 응력히스토그램을 작성하고 등가응력을 상정하여 신규 레일 용접부의 S-N 선도에 적용함으로써 노후레일의 누적피로손상도 및 휨 피로수명을 산정하였다. 최종적으로 본 연구에서는 궤도구조 및 상태를 고려한 레일교체기준의 개정을 제안하고자 하였다.

• 한국철도학회논문집
• /
• 제11권3호
• /
• pp.326-333
• /
• 2008

본 논문은 누적통과톤수에 의한 레일교체기준 개정을 위한 기초 데이터를 제시하는데 목적이 있다. 본 연구에서는 국외의 누적통과톤수에 의한 레일교체기준의 산정근거를 조사하였으며, 일본에서 조사된 레일용접부 결합유형 및 원인과 국내 철도운영기관인 서울메트로의 궤도유지관리이력을 조사하여 실제 레일절손과 누적통과톤수의 상관관계를 분석하였다. 또한, 누적통과톤수 기준치에 도래한 노후레일 용접부를 현장에서 발췌하여 레일용접부 휨시험을 수행하였다. 그 결과, 누적통과톤수와 레일절손간의 상관관계는 뚜렷하지 않았으며 레일용접부의 시공불량에 의한 절손사례가 많은 것으로 분석되었다. 또한, 노후레일휨시험 결과 신규레일용접부에 비해 파괴강도가 $17{\sim}18%$만이 저하된 것으로 나타나 레안교체기준에 도래한 노후레일은 사용성 측면에서 충분한 내구성 및 내하력을 확보하고 있는 것으로 분석되었다.

• 한국지하수토양환경학회지:지하수토양환경
• /
• 제15권3호
• /
• pp.61-68
• /
• 2010

Phytoextraction, one type of phytoremediation processes, has been widely used in the removal of heavy metals from polluted soil. This paper reviewed literature on metal uptake by plants and characterized the metal uptake by types of metals (Zn, Cu, Pb, Cd, and As), plant species, initial metal concentrations in soil and the distribution of metals in different parts of plants. The potential of metal accumulation and transport by plants was closely related to plants species, types of metals, and initial metal concentrations in soil. The plants belonging to Brassicaceae, Solanaceae, Poaceae, and Convolvulaceae families have shown the high potential capacity of Cd accumulation. The Gentianaceae, Euphorbiaceae, and Polygonaceae families have exhibited relatively high Pb uptake potential while the Pteridaceae and Cyperaceae families have shown relatively high Zn uptake potential. The Pteridaceae family could uptake a remarkably high amount of As compared with other plant families. The potential metal accumulation per plant biomass has increased with increasing initial metal concentration in soil up to a certain level and then decreased for Cd and Zn. For As, only Pteris vittata had a linear relationship between initial concentration in soil and potential of metal uptake. However, a meaningful relationship for Pb was not found in this study. Generally, the plants having high metal uptake potential for Cd or Pb mainly accumulated the metal in their roots. However, the Euphorbiaceae family has accumulated more than 80% of Pb in shoot. Zn has evenly accumulated in roots and stems except for the plants belonging to the Polygonaceae and Rosaceae families which accumulated Zn in their leaves. The Pteridaceae family has accumulated a higher amount of As in leaves than roots. The types of metals, plant species, and initial metal concentration in soil influence the metal uptake by plants. It is important to select site-specific plant species for effective removal of metals in soil. Therefore, this study may provide useful and beneficial information on metal accumulation by plants for the in situ phytoremediation.