• 한국방재학회 논문집
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• 제10권3호
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• pp.39-43
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• 2010

본 연구의 주목적은 아스팔트 혼합물의 피로균열에 대한 예측모델을 개발하는 것이다. 아스팔트 혼합물의 피로균열 시험을 위하여 응력제어 간접인장피로 시험이 수행되었다. 피로균열에 대한 예측모델 개발을 위하여 내적손상비 증가 개념이 도입되었다. 내적손상비증가 개념에서는 방출에너지 개념을 주로 사용하였으며 기준인장변형율 및 변형율 추이 요소 등이 추가로 사용되었다. 피로시험에서 나타난 방출에너지의 원인은 아스팔트 콘크리트 시료 내부의 손상증가와 재료 자체가 갖고 있는 고유의 점탄성 특성에 기인하는 것으로 판단된다. 방출에너지는 하중재하 횟수가 증가함에 따라 점차 증가함을 보였다.

• Structural Monitoring and Maintenance
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• 제10권2호
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• pp.107-116
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• 2023

The health condition of of deep water high pile foundation is vital to the safe operation of bridges. However, pier foundations are vulnerable to damage in deep water due to exposure to sea torrents and corrosive environments over an extended period. In this paper, combined with aninvestigation and analysis of the typical damage characteristics of main pier group pile foundations, we study the safety monitoring and real-time early warning technology of the deep water high pile foundations, we propose an early warning index item and early warning threshold of deep water high pile foundation by utilizing a numerical simulation analysis and referring to domestic and foreign standards and literature. First, we combine the characteristics of structures and draw on more mature evaluation theories and experience in civil engineering-related fields such as dam and bridge engineering. Then, we establish a scheme consisting of a Early Warning Index Systemand evaluation model based on the analytic hierarchy process and constant weight evaluation method and apply the research results to a project based on the Jiashao bridge in Zhejiang province, China. Finally, we verify the rationality and reliability of the Early Warning Index Systemof the Deep Water High Pile Foundations.

• Toxicological Research
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• 제34권4호
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• pp.281-290
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• 2018

Exposure to chemical agents is an inevitable consequence of modern society; some of these agents are hazardous to human health. The effects of chemical carcinogens are of great concern in many countries, and international organizations, such as the World Health Organization, have established guidelines for the regulation of these chemicals. Carcinogens are currently categorized into two classes, genotoxic and non-genotoxic carcinogens, which are subject to different regulatory policies. Genotoxic carcinogens are chemicals that exert carcinogenicity via the induction of mutations. Owing to their DNA interaction properties, there is thought to be no safe exposure threshold or dose. Genotoxic carcinogens are regulated under the assumption that they pose a cancer risk for humans, even at very low doses. In contrast, non-genotoxic carcinogens, which induce cancer through mechanisms other than mutations, such as hormonal effects, cytotoxicity, cell proliferation, or epigenetic changes, are thought to have a safe exposure threshold or dose; thus, their use in society is permitted unless the exposure or intake level would exceed the threshold. Genotoxicity assays are an important method to distinguish the two classes of carcinogens. However, some carcinogens have negative results in in vitro bacterial mutation assays, but yield positive results in the in vivo transgenic rodent gene mutation assay. Non-DNA damage, such as spindle poison or topoisomerase inhibition, often leads to positive results in cytogenetic genotoxicity assays such as the chromosome aberration assay or the micronucleus assay. Therefore, mechanistic considerations of tumor induction, based on the results of the genotoxicity assays, are necessary to distinguish genotoxic and non-genotoxic carcinogens. In this review, the concept of threshold of toxicological concern is introduced and the potential risk from multiple exposures to low doses of genotoxic carcinogens is also discussed.

• 한국지반공학회논문집
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• 제30권12호
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• pp.5-14
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• 2014

국내 대부분의 사면파괴는 6월~9월에 발생하며, 이러한 사면파괴는 사회적으로 큰 손실을 유발한다. 사면파괴의 주요 원인은 강우강도(Intensity, I)와 강우기간(Duration, D)이다. 본 연구에서는 강우강도-기간(I-D)을 고려한 사면파괴 유발 강우 한계선(rainfall threshold)을 제안하였다. 본 연구를 위해서 국립재난안전연구원과 다양한 보고서 및 매체 그리고 현장조사를 통해서 1999년부터 2012년까지 풍화토 지반에서 유발된 255개 재해이력 자료를 수집하였다. 그리고 기상청의 강우자료를 바탕으로 사면파괴가 발생한 시점의 전 후의 시간에 대한 강우량 데이터를 수집하였다. 수집된 재해이력과 강우량 데이터베이스를 바탕으로 사면파괴를 유형별(토석류, 얕은 사면파괴 등)로 분류하고, 통계적 기법인 분위수 회귀분석을 이용하여 강우강도 및 기간을 분석함으로써 강우 한계선을 제안하였다. 뿐만 아니라 2013년의 재해이력 자료를 통해 제안된 한계선의 검증을 수행하였다. 또한 국외의 한계선과 제안된 한계선을 비교 분석하였다. 본 연구에서 제안된 강우 한계선은 산사태 예 경보시스템을 구축할 때 기초자료로 사용될 수 있다고 판단된다.

• 한국콘텐츠학회논문지
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• 제4권4호
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• pp.33-43
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• 2004

본 논문에서는 기존 SNMP를 이용한 트래픽 분석 방법의 문제점을 개선시킨 SNMP 기반의 트래픽 추이 분석 알고리즘을 제안하였다. 기존 방법에서는 임계치를 적용함으로써 분석 시간이 많이 걸리며, 초기 공격 트래픽에 대해 탐지하지 못하는 취약점을 가지고 있었다. 본 논문에서는 임계치를 사용하지 않고 일주 트래픽 추이 분석, 프로토콜별 추이 분석 그리고 특정 MIB에서의 트래픽 발생 유무를 분석함으로써 기존 방법에서의 문제점을 해결할 수 있었다. 트래픽이 발생하게 되면 이 세 가지 분석 방법을 통해 이상 여부를 분석하고, 이상 트래픽이 중첩적으로 발생될 경우 현재 입력된 트래픽을 유해 트래픽으로 분석해 낼 수 있다. 제안한 알고리즘을 통해서 유해 트래픽을 빠르고 정확하게 분석해 낼 수 있으며, 이를 통해 트래픽 폭주 공격에 의한 피해를 줄일 수 있을 것이다.

• The Journal of Korean Physical Therapy
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• 제20권1호
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• pp.1-9
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• 2008

Purpose: This study examined the effects of pre-eccentric exercise to the quadriceps for the prevention of delayed onset muscle soreness (DOMS) and recovery of muscular function, depending on the training intensities. Methods: Subjects were divided into one of three groups that control group, a low intensity eccentric exercise group (LIEE group) and a high intensity eccentric exercise group (HIEE group). Subjects who underwent pre-eccentric exercise undertook exercise at an intensity of 25% and 75% of maximal voluntary contractions, respectively. After undertaking pre-eccentric exercise for eight weeks, eccentric exercise was applied again to induce DOMS. Measurements were conducted to examine pain and muscular function changes before, immediately after, after the induction of DOMS, and at the first, third, fifth and seventh days after the induction of DOMS. Results: Subjects who underwent pre-eccentric exercise showed a significant difference from the control group for the changes in the visual analogue scale (VAS) pain threshold, pressure pain threshold and muscle thickness by isometric contraction from measuring DOMS, and in particular, pain threshold by isometric contraction had remarkable effect in the LIEE group of subjects. For the change of the root mean square values using mechanomyography (MMG) as the measurement of muscular function recovery, subjects who had undertaken pre-eccentric exercise group showed a significant difference as compared to the control group. Conclusion: Pre-eccentric exercise was very effective in preventing and recovering delayed onset muscle soreness and was helpful to prevent and recover from decreased muscular function. The difference based on the intensity of exercise was not great, but it was more effective in the low intensity eccentric exercise group of subjects. Therefore, it can be considered that pre-eccentric exercise has a high application value as a physical therapy intervention for prevention and rehabilitation of sports injuries.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2006년도 춘계학술발표회 논문집(I)
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• pp.438-441
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• 2006

Since the behavior of structural members subjected to blast load shows different responses, the effect of impulse as well as peak load should be considered in the damage analysis. The threshold on P-I diagram that causes specific damage level divides the diagram into the failure zone and the non-failure zones. In this study, numerical analysis is performed based on single-degree-of-freedom (SDOF) techniques to generate rational P-I diagram considering material non-linearity and dual failure modes (flexure and direct shear) of RC beams. From the comparison with existing test results it is concluded that proposed numerical method is good to derive failure mode of RC beam under blast load.

• 한국응용곤충학회지
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• 제48권2호
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• pp.229-236
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• 2009

시설재배 가지 및 피망에서 꽃노랑총채벌레의 가해에 따른 피해양상과 방제수준 설정을 인위적인 충 접종과 케이지 실험을 통해 조사하였다. 2005년 가지 실험결과, 꽃노랑총채벌레 가해에 의한 직접적인 피해는 가지 과실에서 나타났고, 여러 개의 가는 선과 굵은 선을 동시에 갖거나 과실 표면이 일부 표백된 피해가 심한 과실은 상품성이 하락하였다. 꽃노랑총채벌레는 가지 꽃에서는 성충태가, 앞에서는 유충태가 주로 발견되었다. 꽃노랑총채벌레 밀도 수준에 따른 시험구간 수량차이는 발견되지 않았다. 시험구의 꽃노랑총채벌레 발생밀도(수확 2주전 일주일간 끈끈이트랩 밀도)와 각 수확시 비상품과율간에는 정의 상관 관계가 있었다. 황색 끈끈이트랩 이용시 방제수준을 피해과율 5%를 유발하는 총채벌레 밀도로 가정했을 때 가지 수확 2주전에 일주일간 성충 유살수가 10마리 되는 수준이었다. 2007년 피망 실험결과, 꽃노랑총채벌레에 의한 피해는 피망의 과실표면, 꽃받침에 뚜렷하게 나타났고, 과실에서 피해가 심할 경우 상품성이 하락되었다. 밀도가 높은 시험구들에서는 상품과의 수량에 유의한 감소가 있었다. 피망에서 꽃노랑총채벌레 밀도와 피해과율에는 높은 상관관계가 있었고, 피해과율 5%를 유발하는 꽃노랑 총채벌레 밀도수준은 수확2주전 끈끈이트랩 유살수의 경우 일주일간 채집된 개체수가 4.8마리, 꽃에서 발생밀도의 경우는 0.9마리 수준이었다.

• Structural Monitoring and Maintenance
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• 제3권4호
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• pp.315-333
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• 2016

This study aims to perform damage identification for Da-Sheng-Guan (DSG) high-speed railway truss arch bridge using fuzzy clustering analysis. Firstly, structural health monitoring (SHM) system is established for the DSG Bridge. Long-term field monitoring strain data in 8 different cases caused by high-speed trains are taken as classification reference for other unknown cases. And finite element model (FEM) of DSG Bridge is established to simulate damage cases of the bridge. Then, effectiveness of one fuzzy clustering analysis method named transitive closure method and FEM results are verified using the monitoring strain data. Three standardization methods at the first step of fuzzy clustering transitive closure method are compared: extreme difference method, maximum method and non-standard method. At last, the fuzzy clustering method is taken to identify damage with different degrees and different locations. The results show that: non-standard method is the best for the data with the same dimension at the first step of fuzzy clustering analysis. Clustering result is the best when 8 carriage and 16 carriage train in the same line are in a category. For DSG Bridge, the damage is identified when the strain mode change caused by damage is more significant than it caused by different carriages. The corresponding critical damage degree called damage threshold varies with damage location and reduces with the increase of damage locations.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 1997년도 춘계학술대회 논문집
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• pp.982-986
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• 1997

A method using cutting force signal and neural network for detection tool damage is proposed. Cutting force signal is gained by tool dynamometer and the signal is prepocessed to normalize. Cutting force signal is changed by tool state. When tool damage is occurred, cutting force signal goes up in comparison with that in normal state. However,the signal goes down in case of catastrophic fracture. These features are memorized in neural network through nomalizing couse. A new nomalizing method is introduced in this paper. Fist, cutting forces are sumed up except data smaller than threshold value, which is the cutting force during non-cutting action. After then, the average value is found by dividing by the number of data. With backpropagation training process, the neural network memorizes the feature difference of cutting force signal between with and without tool damage. As a result, the cutting force can be used in monitoring the condition of cutting tool and neural network can be used to classify the cutting force signal with and without tool damage.