• International Journal of Concrete Structures and Materials
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• 제1권1호
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• pp.19-28
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• 2007

A dynamic constitutive damage model for reinforced concrete (RC) structures and formulations of blast loading for contact or near-contact charges are considered and adapted from literatures. The model and the formulations are applied to the input parameters needed in commercial finite element method (FEM) codes which is validated by the laboratory blast tests of RC slabs from literature. The results indicate that the dynamic constitutive damage model based on the damage mechanics and the blast loading formulations work well. The framework on the dynamic constitutive damage model and the blast loading equations can therefore be used for the simulation of failure of bridge components in engineering applications.

• 센서학회지
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• 제24권1호
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• pp.10-14
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• 2015

This paper reports the results of a study on the optimization of the etching profile, which is an important factor in deep-reactive-ion etching (DRIE), i.e., dry etching. Dry etching is the key processing step necessary for the development of the Internet of Things (IoT) and various microelectromechanical sensors (MEMS). Large-area etching (open area > 20%) under a high-frequency (HF) condition with nonoptimized processing parameters results in damage to the etched sidewall. Therefore, in this study, optimization was performed under a low-frequency (LF) condition. The HF method, which is typically used for through-silicon via (TSV) technology, applies a high etch rate and cannot be easily adapted to processes sensitive to sidewall damage. The optimal etching profile was determined by controlling various parameters for the DRIE of a large Si wafer area (open area > 20%). The optimal processing condition was derived after establishing the correlations of etch rate, uniformity, and sidewall damage on a 6-in Si wafer to the parameters of coil power, run pressure, platen power for passivation etching, and $SF_6$ gas flow rate. The processing-parameter-dependent results of the experiments performed for optimization of the etching profile in terms of etch rate, uniformity, and sidewall damage in the case of large Si area etching can be summarized as follows. When LF is applied, the platen power, coil power, and $SF_6$ should be low, whereas the run pressure has little effect on the etching performance. Under the optimal LF condition of 380 Hz, the platen power, coil power, and $SF_6$ were set at 115W, 3500W, and 700 sccm, respectively. In addition, the aforementioned standard recipe was applied as follows: run pressure of 4 Pa, $C_4F_8$ content of 400 sccm, and a gas exchange interval of $SF_6/C_4F_8=2s/3s$.

• 한국측량학회지
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• 제35권2호
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• pp.113-122
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• 2017

Natural disasters caused by climate change are increasing globally. There are few studies on the quantitative analysis methods for predicting damages in the island area due to sea level rise. Therefore, it is necessary to study the damage prediction analysis method using the GIS which can quantitatively analyze. In this paper, we analyze the cause and status of sea level rise, quantify the vulnerability index, establish an integrated terrestrial modeling method of the ocean and land, and establish a method of analyzing the damage area and damage scale due to sea level rise using GIS and the method of making the damage prediction figure was studied. In order to extract the other affected areas to sea level rise are apart of the terrain model is generated by one requires a terrain modeling of target areas are offshore and vertical reference system differences in land, found the need for correction by a tidal observations and geoid model there was. Grading of terrain, coastline erosion rate, coastal slope, sea level rise rate, and even average by vulnerable factors due to sea level rise indicates that quantitative damage prediction is possible due to sea level rise in the island area. In the case of vulnerable areas extracted by GIS, residential areas and living areas are concentrated on the coastal area due to the nature of the book area, and field survey shows that coastal changes and erosion are caused by sea level rise or tsunami.

• 한국재난정보학회 논문집
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• 제15권1호
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• pp.20-27
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• 2019

연구목적: 본 연구에서는 국내 자동차 관련 화재발생 현황 및 위험성을 평가하고 초기 소화기구의 사용에 따른 피해저감 효과에 대해 평가하였다. 연구방법: 국내 자동차 화재의 발생 빈도에 대한 위험성 분석과 화재발생시 자동차에 비치되어 있는 소화기를 사용하여 초기 소화에 적용한 사용에 따른 인적 및 재산피해를 분석하였다. 연구결과: 국내 자동차 화재 발생에 따른 건당피해액은 연평균 증감률이 4.74%이고 매년 증가하는 것으로 나타났다. 자동차 화재현황 중 승용자동차에서 발생한 인명피해를 연도별 화재발생 건당 인명피해로 분석한 결과, 화재발생 100건당 재산피해액은 424.65만원에서 473.06만원으로 과거 5년간(2012년~2016년) 지속적으로 증가하는 추세를 보이고 있다. 결론: 승용자동차 화재시 소화기를 사용한 경우에는 화재발생 1건당 평균 재산피해액은 약 307.5만으로 산정되어 초기 자동차 화재에 차내에 비치된 소화기를 사용한 초기소화의 중요성과 필요성이 요구된다.

• Smart Structures and Systems
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• 제32권3호
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• pp.153-166
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• 2023

Health monitoring of civil infrastructures, in particular, old bridges that are still in service, has become more than necessary, given the risk that a possible degradation or failure of these infrastructures can induce on the safety of users in addition to the resulting commercial and economic impact. Bridge integrity assessment has attracted significant research efforts over the past forty years with the aim of developing new damage identification methods applicable to real structures. The bridge of Ouled Mimoun (Tlemcen, Algeria) is one of the oldest railway structure in the country. It was built in 1889. This bridge, which is too low with respect to the level of the road, has suffered multiple shocks from various machines that caused considerable damage to its central part. The present work aims to analyze the stability of this bridge by identifying damages and evaluating the damage rate in different parts of the structure on the basis of a finite element model. The applied method is based on an inverse analysis of the normal stress responses that were calculated from the corresponding recorded strains, during the passage of a real train, by means of a set of strain gauges placed on certain elements of the bridge. The results obtained from the inverse analysis made it possible to successfully locate areas that were really damaged and to estimate the damage rate. These results were also used to detect an excessive rigidity in certain elements due to the presence of plates, which were neglected in the numerical reference model. In the case of the continuous bridge monitoring, this developed method will be a very powerful tool as a smart health monitoring system, allowing engineers to take in time decisions in the event of bridge damage.

• 환경영향평가
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• 제17권6호
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• pp.381-391
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• 2008

The instances of the damage to livestock are increasing with frequent environmental disputes on the noise and vibration. This study analyzed 134 open cases dealing with the environmental disputes on livestock damaged by noise and vibration, and being intervened by National Environmental Dispute Resolution Commission. The environmental disputes on the noise and vibration account for 86% of all the disputes, and cases of the consequent damages to livestock have increased. As shown in the 134 cases, pig is the most lethal livestock attacked by the noise and vibration. During last 10 years, 89% of the noise damages hurting the livestock resulted from the noises pertaining to construction and 58% was due to the noise damages from the road constructions. The noise levels in the range of 70~80 dB(A) and the vibration levels of 70~75 dB(V) caused most of the disputes. The average rate of reimbursement for the livestock damages for the last 10 years was higher than the average rate of reimbursement of the total disputes intervened by National Dispute Resolution Commission.

• 한국군사과학기술학회지
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• 제5권4호
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• pp.67-77
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• 2002

This paper introduces the calibration results of the fatigue crack growth models for damage tolerance analysis of the aircraft structures. Generalized Willenborg model and Wheeler model are calibrated with experimental data tested under the load spectrum of a trainer. The retardation factors such as, shut-off ratio in Generalized Willenborg model and shaping exponent in Wheeler model, are evaluated for aluminum alloys AL2024-T3511, AL7050-T7451 and AL7075-T73511. It is shown that the retardation effect of the crack growth rate depends on the yield strength of material and the maximum stress in the load spectrum. Generalized Willenborg model and Wheeler model give satisfactory prediction of crack growth life but the calibration of the experimental parameters with test is required.

• 한국공작기계학회논문집
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• 제10권4호
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• pp.14-21
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• 2001

To estimate crack growth rate and cycle ratio uniquely, many investigators have developed various kinds of mechanical parameters and theories. But, thes have produced local solution space through single parameter. Neural Networks can perform patten classification using several input and output parameters. Fatigue damage model by neural networks was used to recognize the relation between da/dN/N/N(sub)f, and half-value breadth ratio B/Bo, fractal dimension D(sub)f, and fracture mechanical parameters in 2024-T3 aluminium alloy. Learned neural networks has ability to predict both crack growth rate da/dN and cycly ratio /N/N(sub)f within engineering estimated mean error(5%).

• 한국재료학회지
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• 제3권5호
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• pp.482-496
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• 1993

Radiation damage and contamination of silicons etched in the $CF_4+H_2$ and $CHF_3$ magnetron discharges have been characterized using Schottky diode characteristics, TEM, AES, and SIMS as a function of applied magnetic field strength. It turned out that, as the magnetic field strength increased, the radiation damage measured by cross sectional TEM and by leakage current of Schottky diodes decreased colse to that of wet dtched samples especially for $CF_4$ plasma etched samples, For $CF_4+H_2$and $CHF_3$ etched samples, hydrogen from the plasmas introduced extended defects to the silicon and this caused increased leakage current to the samples etched at low magnetic field strength conditions by hydrogen passivation. The thickness of polymer with the increasing magnetic field strength and showed the minimum polymer residue thickness near the 100Gauss where the silicon etch rate was maximum. Also, other contaminants such as target material were found to be minimum on the etched silicon surface near the highest etch rate condition.

• 한국가금학회지
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• 제43권3호
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• pp.177-189
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• 2016

본 연구는 닭의 개체 별 스트레스 연관 표지의 발현도와 이들의 생산능력 간의 연관성을 살펴보기 위한 것으로 토종종계 25계통을 대상으로 텔로미어 함량, 열 스트레스 단백질(HSPs) 유전자 발현율 및 DNA 손상율을 분석하고, 동일 개체들의 생존율, 성장능력 및 산란능력을 조사하여 이들 간의 상관관계를 분석 고찰하였다. 분석 결과, 생산능력 및 스트레스 표지 값들 간에 계통별로 유의한 차이가 나타났는데, 대체적으로 고체중 순계들의 스트레스 지표가 상대적으로 높았으며, 저체중 교잡계들의 스트레스 지표가 낮게 나타났다. 텔로미어 함량과 생산능력 간의 상관성은 20주령 이후부터 유의한 상관관계를 보였는데, 성장능력과는 약한 부(-)의 상관 양상을, 산란능력 및 생존율과는 약한 정(+)의 상관관계를 나타내었다. HSPs 유전자 발현율과 생산능력과의 상관에서 생존율 및 산란지수와는 저도 및 중도의 부의 상관을 보였고, 체중과는 약한 정의 상관관계를 나타내었다. DNA 손상율 분석 또한 체중과는 약한 정의 상관을, 산란지수 및 생존율과는 중도 및 저도의 부의 상관관계를 나타내었다. 이는 체중이 증가할수록 HSPs 유전자 발현율, DNA 손상율 및 텔로미어 감축량이 증가함을 의미하고, 반면 산란능력 및 생존율이 높을수록 HSPs 유전자 발현율과 DNA 손상율은 낮아지고, 텔로미어 함량은 상대적으로 높다는 것을 시사한다. 스트레스 표지 인자들 간의 상호 관계에서 모든 표지 값 간에 유의한 상관관계가 나타났는데, HSPs 발현값과 텔로미어 함량과는 부의 상관을, DNA 손상율과는 정의 상관을 보이고, 텔로미어 함량과 DNA 손상율과는 높은 부의 상관을 나타내었다. 이상의 스트레스 표지 값과 생산능력 간의 상관분석 결과에 따라 닭에 있어 HSPs 및 DNA 손상율의 증가는 텔로미어 감축을 촉진하고, 이에 따라 개체의 항병성 및 강건성을 저하시켜 산란능력과 생존율에 나쁜 영향을 미치는 것으로 판단된다.