• Earthquakes and Structures
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• 제7권6호
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• pp.1259-1281
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• 2014

This research has been conducted in order to investigate the effects of peak ground velocity (PGV) of near-field earthquakes on base-isolated structures mounted on Single Friction Pendulum (SFP), Double Concave Friction Pendulum (DCFP) and Triple Concave Friction Pendulum (TCFP) bearings. Seismic responses of base-isolated structures subjected to simplified near field pulses including the forward directivity and the fling step pulses are considered in this study. Behaviour of a two dimensional single story structure mounting on SFP, DCFP and TCFP isolators investigated employing a variety range of isolators and the velocity (PGV) of the forward directivity and the fling step pulses as the main variables of the near field earthquakes. The maximum isolator displacement and base shear are selected as main seismic responses. Peak seismic responses of different isolator types are compared to emphasize the efficiency of each one under near field earthquakes. It is demonstrated that rising the PGVs increases the isolator displacement and base shear of structure. The effects of the forward directivity are greater than the fling step pulses. Furthermore, TCFP isolator is more effective to control the near field effects than the other friction pendulum isolators are. This efficiency is more significant in pulses with longer period and greater PGVs.

• Smart Structures and Systems
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• 제6권4호
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• pp.363-372
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• 2010

Accurate peak response estimation of a seismically excited structure with frictional damping system (FDS) is very difficult since the structure with FDS shows nonlinear behavior dependent on the structural period, loading characteristics, and relative magnitude between the frictional force and the excitation load. Previous studies have estimated the peak response of the structure with FDS by replacing a nonlinear system with an equivalent linear one or by employing the response spectrum obtained based on nonlinear time history and statistical analysis. In case that earthquake excitation is defined probabilistically, corresponding response of the structure with FDS becomes to have probabilistic distribution. In this study, nonlinear time history analyses were performed for the structure with FDS subjected to artificial earthquake excitation generated using Kanai-Tajimi filter. An equation for the probability density function (PDF) of the displacement response is proposed by adapting the PDF of the normal distribution. Coefficients of the proposed PDF are obtained by regression of the statistical distribution of the time history responses. Finally, the correlation between the resulting PDFs and statistical response distribution is investigated.

• Asian Journal of Atmospheric Environment
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• 제2권1호
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• pp.47-53
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• 2008

In this study, we analyzed how ozone pollution could be differently measured and how these different measures varied year to year and across the ten most populated cities in the United States, from 1980 to 2000. Although peak values of ozone concentration have been significantly reduced in most polluted U.S. cities for the last 20 years, the annual average values of ozone concentration have not been lowered as much as peak values. Ozone concentration data for each city shows a unique pattern of distribution, central tendency, and also there is a wide variation among different ozone measures. Two different cities with the same annual mean concentration of ozone can experience very different distributions of ozone concentration within a year. Ozone measures also show a wide margin of variability as they are estimated from different ozone monitoring sites within each city. Ozone pollution statistics can be largely varied depending on the choice of measures, monitoring sites, and averaging time period. EPA's new ozone standard of 0.08 ppm averaged over an eight-hour appears to be more stringent than the current maximum ozone standard of 0.12 ppm averaged over one hour.

• KSBB Journal
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• 제9권1호
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• pp.26-34
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• 1994

챙파홍섬무우의 모상근 배양에서 몇 가지 외재 호르몬에 대한 반응을 조사하였던 바, auxins중의 2, 4-D는 안토시아닌의 생성을 촉진하였으며 동시에 뿌리의 탈분화를 유도하였다. Cytokinins은 이식 초기의 비교적 소량의 색소능 촉진효과를 나타내었으며, ABA는 색소의 발현억제 효과를 보이고 GA3 는 색소 생성에 별다른 영향을 마치지 않았다. 1mg/l의 농도에서 2, 4-D 이외의 호르몬은 모상근의 탈분화를 유도하지 않았으며, 모상근의 생장을 대조구 이하로 억제하였다. 2, 4-D와 kinetin를 처리하여 시간경과에 따른 안토시아닌 함량의 변화와 PAL, CHS의 활성변화를 조사하였다. 색소능의 변화를 볼 때, 대조구는 6일 에서 kinetin은 6-9일의 이식초기에 일시적인 색소의 증가를 보였으며, 2, 4-D 처리구는 9엘부터 증가하여 18일경에 peak를 보이며 가장 높은 색소 생성을 나타내었다. PAL의 활성 변화에 있어서는, 대조구에 비하여 kinetin, 2, 4-D처리구 둘 다 활성의 증가를 보이고 kinetin은 6 일에 서 2, 4-D는 9 일에 셔 각각 활성의 peak를 나다내였으며, 특히 2, 4$\longrightarrow$D 의 경우는 18일에서 또 한번의 약한 활성 증가를 보였다. CHS는, 대조구에서는 이식 후 3일에 활성의 일시적인 증가가 있었을 뿐 이후 계속 낮은 상태를 유지하였고 Kinetin 처리구는 6일에서 활성이 증가하여 9일에 최대활성을 보이고 이후 감소하게 된다. 2,4-D 처리구는 9일부터 활성이 증가하여 18일경 최대활성을 나타내고 이후 비교적 높은 활성수준에서 유지되였다. 이외에 이식 후 hormone free 배지 에서 2주간의 전배양 후 kinetin의 처리는 색소축적에 별다른 영향을 미치지 않았다. 이러한 결과에 따라, 2, 4-D, kinetin에 의한 안토시아닌 생성의 촉진효과는 PAL, CHS의 활성 증 가와 유의적인 연관을 나타내였으며, 특히 시간경과 에 따른 CHS의 활성 변화와 색소의 축적은 비례하여 색소 생성에 있어 CHS의 rate-limiting 역할을 제시하였다. Kinetin를 포함하는 cytokinins은 뿌리의 상처에 의한 “wound-response"에 따른 배양초기의 색소 발현을 촉진하는 작용을 하는 것으로 사료되었다. 2, 4-D와 kinetin에 의해 발현되는 PAL, CHS의 활성증감의 정도는 물론 peak를 보이는 경과시간에서의 차이는 각기 다른 조절기작을 갖는 Isozyme의 존재에 의한 것으로 추정되었다.정되었다.

• Earthquakes and Structures
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• 제2권2호
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• pp.171-187
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• 2011

Rational scaling of design earthquake ground motions for tall buildings is essential for safer, risk-based design of tall buildings. This paper provides the structural designers with an insight for more rational scaling based on drift and input energy demands. Since a resonant sinusoidal motion can be an approximate critical excitation to elastic and inelastic structures under the constraint of acceleration or velocity power, a resonant sinusoidal motion with variable period and duration is used as an input wave of the near-field and far-field ground motions. This enables one to understand clearly the relation of the intensity normalization index of ground motion (maximum acceleration, maximum velocity, acceleration power, velocity power) with the response performance (peak interstory drift, total input energy). It is proved that, when the maximum ground velocity is adopted as the normalization index, the maximum interstory drift exhibits a stable property irrespective of the number of stories. It is further shown that, when the velocity power is adopted as the normalization index, the total input energy exhibits a stable property irrespective of the number of stories. It is finally concluded that the former property on peak drift can hold for the practical design response spectrum-compatible ground motions.

• 대한방사선기술학회지:방사선기술과학
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• 제42권6호
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• pp.413-422
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• 2019

Heavy ion particle, represented carbon ion, radiotherapy is currently most advanced radiation therapy technique. Conventional radiation therapy has made remarkable changes over a relatively short period of time and leading various developments such as intensity modulated radiation therapy, 4D radiation therapy, image guided radiation therapy, and high precisional therapy. However, the biological and physical superiority of particle radiation, represented by Bragg peak, can give the maximum dose to tumor and minimal dose to surrounding normal tissues in the treatment of cancers in various areas surrounded by radiation-sensitive normal tissues. However, despite these advantages, there are some limitations and factors to consider. First, there is not enough evidence, such as large-scale randomized, prospective phase III trials, for the clinical application. Secondly, additional studies are needed to establish a very limited number of treatment facilities, uncertainty about the demand for heavy particle treatment, parallel with convetional radiotherapy or indications. In addition, Bragg peak of the heavy particles can greatly reduce the dose to the normal tissues front and behind the tumor compared to the photon or protons. High precision and accuracy are needed for treatment planning and treatment, especially for lungs or livers with large respiratory movements. Currently, the introduction of the heavy particle therapy device is in progress, and therefore, it is expected that more research will be active.

• 한국광학회지
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• 제14권2호
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• pp.146-149
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• 2003

높은 출력의 peak 값을 갖는 광 펄스 신호를 얻기 위하여 2단 구조 EDFA를 구성하였다. EDFA의 첫 번째 단과 두 번째 단 사이에 대역통과 필터(band pass filter)를 삽입하여 소 신호 영역에서 높은 이득을 얻도록 하였다. 사용된 입력 펄스 신호는 100 $\mu\textrm{s}$의 주기, 10 ㎱ 펄스 폭과 1 ㎽의 peak값을 갖고, 평균 출력이 소 신호 영역에 해당하는 낮은 파워를 갖는다. 구성된 EDFA를 사용하여 83 W의 고 출력 펄스 신호를 얻었다.

• Nuclear Engineering and Technology
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• 제50권6호
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• pp.860-868
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• 2018

This article presents a new design of earthquake instrumentation that is suitable for quick decision-making after the seismic event at the nuclear power plant (NPP). The main objective of this work is to ensure more availability of the NPP by expediting walk-down period when the seismic wave is incident. In general, the decision-making to restart the NPP after the seismic event requires more than 1 month if an earthquake exceeds operating basis earthquake level. It affects to the plant availability significantly. Unnecessary shutdown can be skipped through quick assessments of operating basis earthquake, safe shutdown earthquake events, and damage status to structure, system, and components. Multidecision parameters such as cumulative absolute velocity, peak ground acceleration, Modified Mercalli Intensity Scale, floor response spectrum, and cumulative fatigue are discussed. The implementation scope on the field-programmable gate array platform of this work is limited to cumulative absolute velocity, peak ground acceleration, and Modified Mercalli Intensity. It can ensure better availability of the plant through integrated decision-making process by automatic assessment of NPP structure, system, and components.

• 한국항만학회지
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• 제13권1호
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• pp.113-122
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• 1999

Congestion and traffic accidents occur on the merge and diverge sections in the interchange of the freeway. Studies have been conducted to reduce the traffic delay and accidents on the merge section in the freeway since 1960s. but a study was not conducted to estimate the speed variation on the merge section construct models estimated for the speed variation and suggest the appropriate measures. The purpose of this study was to identify the traffic flow characteristics on the merge section in the freeway construct the models estimated for the speed variation on the merge section in the freeway and finally establish the appropriate measure for reduction of traffic delay and accidents on the merge section in the freeway. The following results were obtained: I) Speed variations in the urban freeway appeared to be about 3.2mph, 6.5mph and 7.4mph based on the morning peak period, afternoon peak period and 24-hours period but those in the suburban freeway appeared to be about 8.0mph, 11.1mph and 10.1mph based on the same periods respectively. So different speed reduction signs need be installed to reduce delay and accidents on the merge section in the freeway based on the areas and periods as the freeway traffic management system(FTMS). ii) These models estimated for speed variation need to be studied with the changeable message sign(CMS) technique based on the real-time data so that the traffic flow could be maximized and the traffic delay and accidents be on the merge section in the freeway as more efficient freeway traffic management system(FTMS) in the near future.

• 한국식품영양과학회지
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• 제26권3호
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• pp.480-487
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• 1997

The present study was designed to examine how Ca intake contributes to the increase of peak bone mass with growing female rats. Weaned rats were fed experimental diets consisting in five levels of Ca; very low(0.1%), low(0.2%), moderate(0.5%), high(1.0%) and very high(1.5%) for 4, 8 and 12 weeks. Bone growth, metabolism and Ca metabolism were determined. As for the rats fed for 4 weeks, the bone weight, length and breaking force and bone metabolism were not significantly affected by dietary Ca levels, whereas the current intakes of Ca were observed to have significantly affected the rats fed for 8 or 12 weeks with regard to the bone weight, length and breaking force and bone metabolism. The bone ash and Ca contents of the rats were affected by dietary Ca levels for the total period of feeding. It is suggested that dietary Ca itself affected the mineralization process either during the growth or later, although the resulting bone mass is not a linear function of dietary Ca content.