• 한국수산과학회지
• /
• 제42권5호
• /
• pp.494-502
• /
• 2009

A quantitative model was developed in order to estimate fishery production damage due to anthropogenically induced environmental changes. The model is described in the following equation, $Y_D=\frac{{\phi}_D}{{\phi}_G}[Y_0{\cdot}(t_p-t_0)-\frac{Y_0}{{\phi}_G}(1-e^{-{\phi}_G(t_p-t_0)})]$, where, $Y_D$ is annual amount of fishery production by nuclear power plant. ${\varphi}$ D and ${\varphi}$ G are instantaneous decreasing coefficient of fishery production by nuclear power plant and instantaneous decreasing coefficient of gross fishery production, respectively. $Y_0$ is annual mean fishery production without damages. $t_p$ is the present time, and $t_0$ is the starting time of damages. The model was applied to fishing grounds near a nuclear power plant on the east coast of Korea. Since fishery production damages have become bigger with increasing emission of thermal effluents from generators activities in the power plant, this factor has also been considered as, $\delta_{D_i}=\delta_D\({\sum}\limits_{i=0}^{n}\;W_i/W_T\)$, where, $\delta_{Di}$ is the cumulative damage rate in fishery production from generators, $\delta_D$ is the total cumulative damage rate in fishery production, $W_i$ is the emission amount of thermal effluents by generator i, and n is the number of generators in the nuclear power plant. This model can be used to conduct initial estimates of fishery production damages, before more detailed assessments are undertaken.

• 한국자동차공학회논문집
• /
• 제13권2호
• /
• pp.1-9
• /
• 2005

An end beam is one of the most important structural members supporting uncovered freight under in-service loading. In general, it needs to endure over 25 years. However fatigue fracture has occurred at dynamic stress concentration location of the end beam because user's specifications demanded high speed and vehicle manufacturer made the uncovered freight car with comparatively low strength and stiffness. For durability analysis, finite element analysis is performed to evaluate the problem of uncovered freight structure and local strain. The uncovered freight car was operated on actual problematic railroad line to measure dynamic stress versus time history on the critical part from which a crack is initiated often. Rainflow cycle counting method was used to estimate fatigue damage at dangerous area under operating condition. Therefore, this study shows that analytical fatigue life at the end beam can be predicted on the basis of S-N curve and structure analysis and has a fairly good correlation with experimental fatigue life.

• Steel and Composite Structures
• /
• 제20권2호
• /
• pp.317-335
• /
• 2016

Concentrically braced steel frames (CBFs) can be optimised during the seismic design process by using lateral loading distributions derived from the concept of uniform damage distribution. However, it is not known how such structures are affected by uncertainties. This study aims to quantify and manage the effects of structural and ground-motion uncertainty on the seismic performance of optimum and conventionally designed CBFs. Extensive nonlinear dynamic analyses are performed on 5, 10 and 15-storey frames to investigate the effects of storey shear-strength and damping ratio uncertainties by using the Monte Carlo simulation method. For typical uncertainties in conventional steel frames, optimum design frames always exhibit considerably less inter-storey drift and cumulative damage compared to frames designed based on IBC-2012. However, it is noted that optimum structures are in general more sensitive to the random variation of storey shear-strength. It is shown that up to 50% variation in damping ratio does not affect the seismic performance of the optimum design frames compared to their code-based counterparts. Finally, the results indicate that the ground-motion uncertainty can be efficiently managed by optimizing CBFs based on the average of a set of synthetic earthquakes representing a design spectrum. Compared to code-based design structures, CBFs designed with the proposed average patterns exhibit up to 54% less maximum inter-storey drift and 73% less cumulative damage under design earthquakes. It is concluded that the optimisation procedure presented is reliable and should improve the seismic performance of CBFs.

• 한국신뢰성학회지:신뢰성응용연구
• /
• 제13권2호
• /
• pp.129-140
• /
• 2013

As a fundamental experimental study for reliability improvement of lithium ion secondary battery, degradation mechanism was investigated by microscopic observation and acoustic emission monitoring. Microstructural observation of the decomposed battery after cycle test revealed mechanical and chemical damages such as interface delamination, microcrack of the electrodes, and solid electrolyte interphase (SEI). Acoustic emission (AE) signal was detected during charge and discharge of lithium ion battery to investigate relationships among cumulative count, discharge capacity, and microdamages. With increasing number of cycle, discharge capacity was decreased and AE cumulative count was observed to increase. Observed damages were attributed to sources of the detected AE signals.

• Earthquakes and Structures
• /
• 제11권4호
• /
• pp.649-664
• /
• 2016

A seismic damaged bridge may be hit again by a strong aftershock or another earthquake in a short interval before the repair work has been done. However, discussions about the impact of the unrepaired damages on the residual earthquake resistance of a steel bridge are very scarce at present. In this paper, nonlinear time-history analysis of a steel arch bridge was performed using multi-scale hybrid model. Two strong historical records of main shock-aftershock sequences were taken as the input ground motions during the dynamic analysis. The strain response, local deformation and the accumulation of plasticity of the bridge with and without unrepaired seismic damage were compared. Moreover, the effect of earthquake sequence on crack initiation caused by low-cycle fatigue of the steel bridge was investigated. The results show that seismic damage has little impact on the overall structural displacement response during the aftershock. The residual local deformation, strain response and the cumulative equivalent plastic strain are affected to some extent by the unrepaired damage. Low-cycle fatigue of the steel arch bridge is not induced by the earthquake sequences. Damage indexes of low-cycle fatigue predicted based on different theories are not exactly the same.

• 한국구조물진단유지관리공학회 논문집
• /
• 제9권1호
• /
• pp.243-250
• /
• 2005

우리나라의 수로교는 구조검토결과 내력부족이 없고 시공결함이 없으며, 사용된 재료나 기술 및 시공된 후의 환경상태 등 모든 조건이 동일함에도 균열, 붕괴 등 구조안전을 위협하는 하자가 대부분 일정간격으로 반복되고 있다. 하자 보수 후 채 손상의 발생은 물론 보수 전 양호하였던 인접교각에까지 손상이 확대되어 감은 물론 보수를 하지 않고 장기간 방치된 경우에도 손상은 확대되었다. 또한 철거 후 재시공한 곳에서도 손상이 반복되는 양상을 보였다. 철근콘크리트조 수로교가 불과 수년경과 후 발생될 수밖에 없었던 손상은 구조적인 결함 때문이 아니라 받침장치의 부식 및 신축유격의 부족 등 기능장치의 결함으로 [대기온도변화에 의한 수로의 길이 방향 신 축 변형의 누적] 이라는 손상 메커니즘의 결과 때문이었다. 따라서 원인과는 무관한 통상적인 방법으로 이루어진 보수는 재 손상이나 이의 확산은 필연적이므로 손상 메커니즘이 형성되지 않도록 설계 및 시공되어야 수로교의 안전 및 내구성 확보가 가능하게 된다.

• 한국지진공학회논문집
• /
• 제23권2호
• /
• pp.131-140
• /
• 2019

Diagonally reinforced concrete coupling beams (DRCBs) have been widely adopted in reinforced concrete (RC) bearing wall systems. DRCBs are known to act as a fuse element dissipating most of seismic energies imparted to the bearing wall systems during earthquakes. Despite such importance of DRCBs, the damage estimation of such components and the corresponding consequences within the knowledge of performance based seismic design framework is not well understood. In this paper, drift-based fragility functions are developed for in-plane loaded DRCBs. Fragility functions are developed to predict the damage and to decide the repair method required for DRCBs subjected to earthquake loading. Thirty-seven experimental results are collected from seventeen published literatures for this effort. Drift-based fragility functions are developed for four damage states of DRCBs subjected to cyclic and monotonic loading associated with minor cracking, severe cracking, onset of strength loss, and significant strength loss. Damage states are defined in a consistent manner. Cumulative distribution functions are fit to the empirical data and evaluated using standard statistical methods.

• 농업과학연구
• /
• 제50권3호
• /
• pp.497-505
• /
• 2023

This study evaluated the impact of rain shelters made of plastic film on spring frost damage and fruit quality in Asian pears ('Niitaka') over two years. In 2021, during the coldest spring days (between 0:00 am and 7:00 am), temperatures dropped to -1.20 - 0.43℃ at 120 cm and -1.33 - 0.57℃ at 200 cm above ground level in the control. Conversely, the rain shelter treatment maintained higher temperatures, -0.40 - 0.87℃ at 120 cm and -0.43 - 0.77℃ at 200 cm. Flower damage was significantly lower in the rain-sheltered group, with incidences of 1.3 and 6.9% at 120 and 200 cm, respectively, compared with 18.1 and 22.6% in the control group. Visual observations verified the prevention of frost adhesion on flower organs in the sheltered group, compared with noticeable pistil death and petal browning in the control group. In 2022, when temperatures remained above 0℃, fruitlet stalk length was 5 - 6 mm longer in the sheltered group. The cumulative impact of rain shelters was evident in the improved fruit quality over the two years. This study suggests resilient cultivation strategies in the face of climate change to reduce frost damage, increase productivity, improve fruit quality, and potentially increase incomes of the farmers.

• Clinical and Experimental Pediatrics
• /
• 제46권9호
• /
• pp.876-882
• /
• 2003

목 적 : Doxorubicin에 의한 심근손상에 대한 cardioxane의 심근 예방효과를 관찰하고자 하였다. 방 법 : 몸무게 2.0-3.2 kg의 집토끼 20마리를 이용하였으며, 2마리는 광학 및 전자현미경 결과를 위한 대조 조직을 만드는데 이용되었고 나머지 18마리를 대상으로 group I은 doxorubicin을 단독 투여하였고 group II는 cardioxane으로 전처치한 후 doxorubicin을 투여하였다. Group I은 12마리의 가토를 대상으로 $30mg/m^2$의 doxorubicin을 가능한 한 매주 정맥 주사하였으며 group II는 6마리의 가토를 대상으로 cardioxane $600mg/m^2$으로 전처치한 후 약 20-30분 후에 doxorubicin을 투여하였고, 각각의 doxorubicin 축적총량이 210, 300, $360mg/m^2$이 되도록 하였다. 이상의 방법으로 doxorubicin의 총 투여량이 목표치에 도달한 후 6일 경과 시에 개흉하여 심근 조직을 확보하고 광학현미경 및 전자현미경으로 심근의 손상 정도를 관찰하였다. 결 과 : Doxorubicin의 총 투여량과는 무관하게 토끼 심장의 외견상 차이 및 양 심방과 심실의 크기나 두께에 있어서 큰 차이는 발견할 수 없었다. 광학 현미경상 doxorubicin의 총 투여량이 $210mg/m^2$까지는 정상 대조 가토와 비교시 조직학적으로 큰 차이는 발견할 수 없었고, 총 투여량 $240mg/m^2$에서는 심근섬유의 변성과 괴사 등을 볼 수 있었고 총 투여량 $300mg/m^2$에서는 국소적으로 그리고 미만성으로 심근 섬유의 심한 변성을 관찰할 수 있었다. 전자현미경하에서 소견상 group I에서 doxorubicin의 총 투여량이 $180mg/m^2$ 미만에서는 전자현미경 하에서 심장 조직의 변화를 관찰할 수 없었다. $210mg/m^2$을 투여했던 가토에서는 미토콘드리아 내에 능선(cristae)의 관강(lumen)이 약간 팽창된 소견을 보였고, $240mg/m^2$을 투여했던 토끼에서는 심근섬유의 변성을 관찰할 수 있었고 $300mg/m^2$을 투여했던 토끼에서는 전반적으로 심한 변성이 관찰되었다. 그러나 cardioxane 전처치군에서는 doxorubicin의 총 투여량이 $300mg/m^2$이하에서 광학현미경 및 전자현미경 소견상 조직학적으로 정상의 심장과 차이를 보이지 않았고, $360mg/m^2$에서는 전반적으로는 정상 심근의 소견과 차이는 발견할 수 없었고 국소적인 근세사의 성근 배열부가 발견되었으나 doxorubicin 투여결과에 의한 것인지는 명백하지 않았다. 결 론 : Cardioxane은 doxorubicin에 의한 심근 손상을 예방할 수 있는 훌륭한 약제로서 doxorubicin을 투여하는 모든 환자에게 안전하게 사용할 수 있을 것으로 사료된다.

• 한국수자원학회:학술대회논문집
• /
• 한국수자원학회 2020년도 학술발표회
• /
• pp.99-99
• /
• 2020

The frequency and scale of domestic flood damage continues to increase, but the criteria for responding to flood damage have not been established. To this end, research is underway to estimate the amount of rainfall in each region so that it can be used to respond to flood damage. The limit rainfall is defined as the cumulative maximum rainfall for each duration that causes flooding, and this research purpose to improve the threshold rainfall by estimating the damage based on the damage history in units of 5 years and analyzing changes over time. The limit rainfall based on the damage history was estimated by using the NDMS past damage history of the Ministry of the Interior and Safety and the rainfall minutes data of AWS and ASOS. The period for estimating the limit rainfall is 2013 ~ 2017, 2015 ~ 2019, and the limit rainfall is estimated by analyzing the relationship between the flood damage history and the rainfall event in each period. Considering changes in watershed characteristics and disaster prevention performance, the data were compared using 5-year data. As a result of the analysis, the limit rainfall based on the damage history could be estimated for less than about 10.0% of the administrative dongs nationwide. As a result of comparing the limit rainfall by period, it was confirmed that the area where the limit rainfall has increased or decreased This was analyzed as a change due to rainfall events or urbanization, and it is judged that it will be possible to improve the risk criteria of flooding.