• 한국환경과학회지
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• 제29권5호
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• pp.551-558
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• 2020

This study aims to increase the ability to adapt to the ecosystem and promote a sustainable use of the natural environment, by classifying the types of damaged lands according to various factors, such as the characteristics of the target area and form, cause, and impact of damage. Moreover, the study suggests the development of evaluation categories and criteria by each type. The results obtained are as follows: first, for the assessment of damaged lands, the changed areas were identified utilizing land cover maps. Video analysis was performed to increase the accuracy, and 88 sites were obtained. Second, the types of damage were classified into ecological infrastructure and ecological environment, and the sub-factors of the cause of damage were classified into 12 factors. Third, each evaluation system for the types of damage was composed of four steps, considering each type of damage and the level of evaluators being higher than paraprofessionals. To supplement this study, it will be necessary to utilize the database of damaged lands other than the Seoul Metropolitan Area and conduct an on-site survey for verification in the future.

• 한국철도학회논문집
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• 제9권2호
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• pp.169-173
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• 2006

The major objective of this study is to investigate the fatigue life evaluation of immovability crossing for railway turnout by the field test. In railway engineering, an appliance is necessary to allow a vehicle to move from one track to another. This appliance came to be known technically as turnout. So, turnout is required very complex railway technologies such as rolling stock, track. Due to the plan under the application of high speed train, turnout are needed more stable far fatigue behaviors. It analyzed the mechanical behaviors of turnout crossing with propose its advanced technical type on the field test and fatigue evaluation far the dynamic fatigue characteristics. As a result, the advanced type crossing are obviously effective for the fatigue damage ratio and dynamic response which is non-modified type. The analytical and experimental study are carried out to investigate the passing path of contact surface and fatigue damage trend decrease dynamic stresses and deflections on advanced crossing type, And the advanced type reduce dynamic fatigue damage ratio and increase fatigue life(about each 38%) more than non-modified type. From the field test results of the servicing turnout crossing, it is evaluated that the modification of contact angle, weight, material and sectional properties is very effective fur ensure against fatigue risks.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2006년도 추계학술대회 논문집
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• pp.447-453
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• 2006

The major objective of this study is to investigate the fatigue behavior evaluation of immovability crossing for railway turnout by the field test. In railway engineering, an appliance is necessary to allow a vehicle to move from one track to another. This appliance came to be known technically as turnout. So, turnout is required very complex railway technologies such as rolling stock, track. Due to the plan under the application of high speed train, turnout are needed more stable for fatigue behaviors. It analyzed the mechanical behaviors of turnout crossing with propose its advanced technical type on the field test and fatigue evaluation for the dynamic fatigue characteristics. As a result, the advanced type crossing are obviously effective for the fatigue damage ratio and dynamic response which is non-modified type. The analytical and experimental study are carried out to investigate the passing path of contact surface and fatigue damage trend decrease dynamic stresses and deflections on advanced crossing type. And the advanced type reduce dynamic fatigue damage ratio and increase fatigue life(about each 38%)more than non-modified type. From the field test results of the servicing turnout crossing, it is evaluated that the modification of contact angle, weight, material and sectional properties is very effective for ensure against fatigue risks.

• Structural Monitoring and Maintenance
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• 제1권4호
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• pp.411-425
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• 2014

A relatively low frequency Lamb wave-based damage identification method called damage imaging method for rectangular composite plate is presented. A damage index (DI) is generated from the delay matrix of the Lamb wave response signals, and it is used to indicate the location and approximate area of the damage. The viability of this method is demonstrated by analyzing the numerical and experimental Lamb wave response signals from rectangular composite plates. The technique only requires the response signals from the plate after damage, and it is capable of performing near real time damage identification. This study sheds some light on the application of Lamb wave-based damage detection algorithm for plate-type structures by using the relatively low frequency (e.g., in the neighborhood of 100 kHz, more suitable for the best capability of the existing fiber optic sensor interrogator system with the sampling frequency of 500 kHz) Lamb wave response and a reference-free damage detection technique.

• Smart Structures and Systems
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• 제11권6호
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• pp.589-604
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• 2013

Identification of damage has become an evolving area of research over the last few decades with increasing the need of online health monitoring of the large structures. The visual damage detection can be impractical, expensive and ineffective in case of large structures, e.g., offshore platforms, offshore pipelines, multi-storied buildings and bridges. Damage in a system causes a change in the dynamic properties of the system. The structural damage is typically a local phenomenon, which tends to be captured by higher frequency signals. Most of vibration-based damage detection methods require modal properties that are obtained from measured signals through the system identification techniques. However, the modal properties such as natural frequencies and mode shapes are not such good sensitive indication of structural damage. Identification of damaged jacket type offshore platform members, based on wavelet packet transform is presented in this paper. The jacket platform is excited by simple wave load. Response of actual jacket needs to be measured. Dynamic signals are measured by finite element analysis result. It is assumed that this is actual response of the platform measured in the field. The dynamic signals first decomposed into wavelet packet components. Then eliminating some of the component signals (eliminate approximation component of wavelet packet decomposition), component energies of remained signal (detail components) are calculated and used for damage assessment. This method is called Detail Signal Energy Rate Index (DSERI). The results show that reduced wavelet packet component energies are good candidate indices which are sensitive to structural damage. These component energies can be used for damage assessment including identifying damage occurrence and are applicable for finding damages' location.

• 산업융합연구
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• 제21권2호
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• pp.93-101
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• 2023

본 연구에서는 칼과 가위 및 화학약품에 의한 물리·화학적 섬유 손상을 분석하여 손상의 원인 파악을 위한 기술 데이터 자료로써 활용하고자 하였다. 칼 4종류 및 가위 5종류와 4종류의 화학약품(황산, 염산, 수산화나트륨, 수산화칼륨)을 이용하여 면(Cotton), 울(Wool), 폴리에스터(Polyester), 레이온(Rayon), T/C(Polyester 50%, Cotton 50%), T/W(Polyester 50%, Wool 50%)에 물리·화학적 손상을 생성하여 공구와 화학약품에 따른 손상을 분석하였다. 칼과 가위에 의한 관통 손상은 칼의 날 부분이 관통한 경우 공통으로 "V" 유형의 손상이 나타났으며, 칼의 등 부분이 관통한 칼의 경우 "T", "ㅁ", 갈고리, "ㄷ" 유형의 손상이 나타났다. 또한, 가위의 경우 모두 "Y" 유형의 손상이 공통으로 나타났다. 화학약품에 의한 섬유 손상은 유류 흔적, 부식, 분해, 수축, 변색 등 다양한 손상이 나타났으며, 화학약품과 섬유의 종류에 따라 나타나는 손상에 차이를 보였다. 섬유의 물리적 손상은 공구의 형태적 특성에 따라 나타나는 특징에 차이를 보였으며, 화학적 손상은 화학약품과 섬유의 종류에 따른 특징 차이를 보임을 확인하였다.

• Journal of Nutrition and Health
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• 제50권1호
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• pp.10-24
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• 2017

본 연구는 건강한 성인 남녀를 대상으로 glutathione S-transferase (GST)M1 및 T1 유전자 다형성에 따라 한식에서 주로 섭취하는 식물성 식품군과 한식 식단의 DNA 손상 감소효과를 측정하여 유전적 민감도가 어떻게 나타나는지를 알아보기 위해 수행되었다. 이를 위하여 건강한 성인 남녀 59명을 대상으로 혈액을 채취하여 GST genotype을 분류하였으며 그 중 17명을 선발하여 DNA 손상 감소효과를 Comet assay를 이용하여 측정하였고 DNA damage relative score로 나타냈다. 제 5기 2차년도 국민건강영양조사를 활용하여 한국인이 많이 섭취하는 식물성 식품을 10가지 식품군 (감자류, 견과류, 곡류, 과일류, 김치류, 두류, 버섯류, 오일류 채소류 해조류)으로 분류 후, 각 식품군별 총 섭취량의 1% 이상을 섭취한 84종의 식품을 한식 식물성 식품으로 최종 선정하였으며 한식 식단 (Korean diet)은 한국영양학회에서 발행한 [2010 한국인 영양섭취 기준]에 제시되어 있는 1주일 표준식단 (2,000 kcal/day)을 사용하였다. GSTM1 유전자 다형성에 따른 한식 식물성 식품군의 Tail moment로 본 DNA 손상 감소효과는 곡류와 오일류에서만 GSTM1 wild type보다 mutant type에서 유의하게 높았다. 이에 비해 DNA 손상 감소 효과를 % DNA in tail과 Tail moment로 본 결과, 견과류 과일류 채소류 버섯류 김치류 해조류에서 GSTT1 mutant type에 비해 wild type에서 유의하게 더 높게 나타났다. GSTM1과 GSTT1의 combined genotype에 따라 한식 식물성 식품의 DNA 손상 감소효과를 본 결과, 과일류, 김치류, 버섯류, 채소류, 해조류는 1군 (GSTM1+/GSTT1+) 및 3군 (GSTM1-/GSTT1+)에서, 오일류는 3군 (GSTM1-/GSTT1+)에서 DNA 손상 감소 효과가 유의하게 높았으며. 감자류, 견과류, 곡류, 두류, Total은 DNA 손상 감소 효과가 2군 (GSTM1+/GSTT1-) 및 3군 (GSTM1-/GSTT1+)에서 유의하게 높아 식품군에 따라 GST 유전자 다형성에 따른 DNA 손상 감소효과가 다르게 나타나는 것을 확인할 수 있었다. 한식 식단은 DNA 손상의 세 가지 지표인 % DNA in tail, Tail moment, Tail length로 측정해본 결과 GSTM1의 경우 wild type에서 mutant type보다 더 크게 나타났으며, GSTT1의 경우는 genotype에 따라 DNA 손상이 달라지는 경향은 있었지만 유의한 차이를 나타내지 않았다. 결론적으로 한식에서 주로 섭취하는 식물성 식품군에서는 식품에 따라 부분적으로 GSTM1은 mutant type에서, GSTT1은 wild type에서 DNA 손상 보호효과가 더 크게 나타났으며, GSTM1과 GSTT1의 combined genotype에 따른 DNA 손상 보호효과는 식품군에 따라 다르게 나타났다. 반면, 한식 식단에서는 DNA 손상 보호효과가 GSTM1 wild type에서 mutant type보다 더 크게 나타났으며, GSTT1 genotype에는 영향을 받지 않는 것으로 나타났다. 이와 같은 결과는 한식 식물성 식품군 및 식사패턴의 항산화 기능 우수성을 증명하는 기초자료가 될 것이며, 나아가 개인별 유전자에 따른 항산화 맞춤영양연구를 시작하는 시발점이 될 수 있을 것이다. 앞으로 GST 유전자 다형성에 따른 한식과 한식 식물성 식품군의 유전적 민감도를 더 명확하게 규명하기 위해서는 대상 인원을 늘려 수행하는 광범위한 연구가 필요할 것으로 보인다.

• 한국전산구조공학회논문집
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• 제20권3호
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• pp.229-237
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• 2007

본 논문에서는 보 구조물의 실시간 손상위치 경보를 위해 가속도 신호를 이용한 인공신경망기반 손상검색기법을 제안하였다. 이를 위해 먼저, 실시간 손상검색을 위해 가속도 응답신호만을 이용하는 새로운 인공신경망 알고리즘을 설계하였다. 구조물의 손상상태를 나타내는 특징으로 서로 다른 두 위치에서 측정된 가속도 신호의 교차공분산 값을 이용하였다. 다음으로 실제 하중조건을 모르는 상황을 고려하여 다양한 하중패턴에 따른 복수 신경망을 구성하였으며, 각각의 신경망 학습을 위한 손상시나리오를 선정하였다. 마지막으로 양단 자유보 모형실험을 통해 제안된 기법의 유용성과 적용성을 평가하였다.

• Earthquakes and Structures
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• 제17권2호
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• pp.175-189
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• 2019

The aim of the study is to show the results of complex shaking table experimental investigation focused on the response of two models of cylindrical steel tanks under mining tremors and moderate earthquakes, including the aspects of diagnosis of structural damage. Firstly, the impact and the sweep-sine tests have been carried out, so as to determine the dynamic properties of models filled with different levels of liquid. Then, the models have been subjected to seismic and paraseismic excitations. Finally, one fully filled structure has been tested after introducing two different types of damages, so as to verify the method of damage diagnosis. The results of the impact and the sweep-sine tests show that filling the models with liquid leads to substantial reduction in natural frequencies, due to gradually increasing overall mass. Moreover, the results of sweep-sine tests clearly indicate that the increase in the liquid level results in significant increase in the damping structural ratio, which is the effect of damping properties of liquid due to its sloshing. The results of seismic and paraseismic tests indicate that filling the tank with liquid leads initially to considerable reduction in values of acceleration (damping effect of liquid sloshing); however, beyond a certain level of water filling, this regularity is inverted and acceleration values increase (effect of increasing total mass of the structure). Moreover, comparison of the responses under mining tremors and moderate earthquakes indicate that the power amplification factor of the mining tremors may be larger than the seismic power amplification factor. Finally, the results of damage diagnosis of fully filled steel tank model indicate that the forms of the Fourier spectra, together with the frequency and power spectral density values, can be directly related to the specific type of structural damage. They show a decrease in the natural frequencies for the model with unscrewed support bolts (global type of damage), while cutting the welds (local type of damage) has resulted in significant increase in values of the power spectral density for higher vibration modes.

• 운동영양학회지
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• 제17권2호
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• pp.25-34
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• 2013

This study was conducted to investigate the relationship between ACE gene polymorphism and muscle damage parameters after eccentric exercise. 80 collegiate males were instructed to take an eccentric exercise with the elbow flexor muscle through the modified preacher curl machine for 2 sets of 25 cycles (total 50 cycles). The maximal isometric strength, muscle soreness, creatine kinase (CK), and myoglobin (Mb) were measured before exercise, and 0, 24, 48, 72, and 96 hrs after exercise. The result showed that after the eccentric exercise, the maximal isometric strength significantly decreased by more than 50% (p < 0.001) and the muscle soreness, CK, and Mb significantly increased compared to those before the exercise (p < 0.001). The ACE gene polymorphism of the subjects was classified using real-time polymerase chain reaction (real-time PCR). The result showed that it consisted of 38 cases of type II (46.4%), 33 cases of type ID (43.4%), and 9 cases of type DD (10.2%). The Hardy-Weinberg equilibrium for ACE gene polymorphism was shown to have p = 0.653, which showed that each allele was evenly distributed. Although significant differences in the changes in the maximal isometric strength, muscle soreness, CK, and Mb were found according to time course (p < 0.001), no significant differences in the changes in the maximal isometric strength, muscle soreness, CK, and Mb were found according to ACE gene polymorphism. Furthermore, no significant difference in the changes in the muscle damage parameters was found according to interaction between ACE gene polymorphism and time course (p > 0.05). In conclusion, the level of the muscle damage parameters changed in the injured muscle after eccentric exercise, but these changes in the muscle damage parameters were not affected by ACE gene polymorphism. The result of this study indicates that ACE gene is not a candidate gene that explains muscle damage.