Earticle

The rapid urbanization and industrial growth have increased the demand in construction, maintenance, and infrastructure, leading to significant advancements in aerial work vehicle technology. This study focuses on the structural performance of ultra-high-strength steel plates of varying thicknesses used in telescopic booms, which is a critical component of aerial work vehicles. This study aims to address the cost issues associated with the previously used 5mm thick plates by evaluating the structural integrity of thinner plates. Using finite element analysis (FEA), the study analyzes stress and displacement for different thicknesses, specifically targeting the first boom segment, which bears the most load. The results indicate that while 3mm and 3.2mm thick plates are unsuitable due to buckling, the 4mm thick plate meets safety criteria with a safety factor of 2.51 and reduces costs by over 20%. By using 4mm thick ultra-high-strength steel for the first boom segment is cost-effective, providing structural integrity and an applicable solution for aerial work vehicle manufacturers.

The objective of this study is to evaluate the mechanical behaviors and structural integrity of the weldment of high strength steel by using an acoustic emission (AE) techniques. Monotonic simple tension and AE tests were conducted against the 3 kinds of welded specimen. In order to analysis the effectiveness of weldability, joinability and structural integrity, we used K-means clustering method as a unsupervised learning pattern recognition algorithm for obtained multi-variate AE main data sets, such as AE counts, energy, amplitude, hits, risetime, duration, counts to peak and rms signals. Through the experimental results, the effectiveness of the proposed method is discussed.

The objective of this study is to evaluate the mechanical behaviors and structural integrity of the weldment of high strength steel by using an acoustic emission (AE) techniques. Simple tension and AE tests were conducted against the 3 kind of welding test specimens. In order to analysis the effectiveness of weldability, joinability and structural integrity, we used K-means clustering method as a unsupervised learning pattern recognition algorithm for obtained multivariate AE main data sets, such as AE counts, energy, amplitude, hits, risetime, duration, counts to peak and rms signals. Through the experimental results, the effectiveness of the proposed method is discussed.

With the rapid expansion of Personal Air Vehicle (PAV) and Urban Air Mobility (UAM) markets, there is a growing need for efficient maintenance approaches to ensure the structural safety of small-scale aircraft. In this study, finite element analysis was conducted on a small aircraft fuselage structure to identify its dynamic characteristics and potential resonance regions, and to evaluate its structural integrity. Frequency response analysis showed an increase in structural response around 78.29Hz, where the structure exhibited a vertical bending deformation pattern. In addition, stress distribution analysis indicated that relatively higher stress concentration occurred at specific locations. The corresponding frequency was converted to engine rotational speed and compared with actual operating conditions, confirming a sufficient separation margin from the response-increase region. These results provide fundamental data for structural integrity assessment, vibration-based condition monitoring, and maintenance planning of small aircraft structures.

To ensure the safety and functionality of a railroad bridge, maintaining the integrity of the bridge via continuous structural health monitoring is important. However, most structural integrity monitoring methods proposed to date are based on modal responses which require the extracting process and have limited availability. In this paper, the applicability of the existing damage identification method based on free-vibration reponses to time-domain deflection shapes due to moving train load is investigated. Since the proposed method directly utilizes the time-domain responses of the structure due to the moving vehicles, the extracting process for modal responses can be avoided, and the applicability of structural health evaluation can be enhanced. The feasibility of the presented method is verified via a numerical example of a simple plate girder bridge.

본 연구는 부식 환경에 노출된 웰패드(Well-Pad) 설비의 장기 구조 건전성을 예측하기 위한 데이터 기반 모델을 제안한다. 이 모델은 한국건설기술연구원(KICT)의 초음파 두께 측정(UT) 데이터와 캐나다 앨버 타 지역의 장기 부식 데이터를 통합하여, 시간에 따른 부식 거동을 파워 법칙(Power-law) 모델로 추정한 다. 회귀분석 결과, 모든 측정 지점에서 시간 지수가 1보다 낮게 나타나 부식 속도가 시간이 지남에 따라 점차 감소하는 감속형 부식 경향을 보였다. 30년 기준으로 예측된 부식 깊이는 0.304mm에서 0.348mm 사이로, 실제 계측값과 높은 일치를 보였다. 또한, 압력과 온도와 같은 운전 변수는 Z-Score 통계 기법을 이용해 표준화하여 이상 상태를 탐지하였다. 이러한 운전 데이터와 부식 지표를 통합해 ‘사용성 성능 지수(Usability Performance Index, UPI)’를 제안하였으며, 이는 물리적 열화와 기능적 안정성 을 동시에 반영한다. 제안된 예측 프레임워크는 웰패드 설비의 실시간 건전성 평가에 활용 가능하며, 위험 기반 검사(RBI)와 예지보전(PdM) 전략에 효과적으로 적용될 수 있다.

This study presents a data-driven model to predict the long-term structural integrity of Well-Pad facilities operating in corrosive environments. It integrates ultrasonic thickness data from KICT with long-term corrosion data from Alberta, using a power-law model to estimate corrosion behavior over time. Regression results revealed a decelerating corrosion trend, as all time exponents were below one. The projected 30-year corrosion depths ranged between 0.304 and 0.348 mm, closely matching field observations. Pressure and temperature were standardized using Z-Score to detect operational anomalies. A combined index, called the Usability Performance Index (UPI), was developed by integrating these standardized operational variables with a corrosion index. This predictive framework supports real-time integrity monitoring and is well-suited for application in Risk-Based Inspection (RBI) and Predictive Maintenance (PdM) strategies for Well-Pad infrastructure.

본 연구의 목적은 주기적 모니터링을 통해 부유식 콘크리트 구조물의 구조 건전성을 평가하는 것이다. 실제 부유식 콘크리트 구조물을 대상으로 주기적 모니터링을 실시하여 동적 특성을 추출하였다. 추출된 동적 특성과 수치해석 모델을 이용하여 다음 두 가지 활동을 통해 구조 건전성을 평가하였다. 먼저, 비파괴 손상 평가기법을 이용하여 손상의 발생 및 진전을 평가하였으며, 균열도와의 비교를 통하여 그 결과의 신뢰성을 검증하였다. 다음으로, 구조계 추정기법을 이용하여 강성 저하 추이를 분석하였다. 그 결과로, 구조물의 요구 성능 확보여부를 판단할 수 있었다.

The objective of this study is to evaluate the structural integrity of the floating concrete structure through periodic monitoring. Dynamic characteristics of the actual floating concrete structure were extracted from the periodic monitoring. The structural integrity using the extracted dynamic characteristics and numerical model was evaluated by the following two activities. First, the structure damage was evaluated for occurrence and progress using the damage detection method. The reliability of the results was verified by comparison with the crack drawing. Second, the stiffness degradation trend was analyzed using the system identification method. As a result, the structural satisfy performance criteria and safety.

In this paper, as the transport cask was moved in the reactor, the structural integrity on the cask had to be evaluated in the normal transport condition. The drop height of the cask was determined by the weight of the cask in the normal transport condition by regulations about assessment test. It was determined that the drop height of the cask was 1.2 m by regulations. The velocity of the drop impact was calculated to perform the drop impact analysis by the principle of the conservation of energy. Using results of the simulation about the drop impact analysis, the structural integrity assessment on the transport cask was performed by ASME Boiler and Pressure Vessel Code.

Aircraft are among the most effective war weapon systems. There are many efforts to improve their service life and to ensure the safety of their structure. In the past, the deterministic approach, such as durability and damage tolerance, has been mainly used to predict the service life of an aircraft structure using fixed parameters (the initial flaw, material property, etc). The most important parameter, however, may not be the certain statistical factor for assessing the IFQ (Initial Fatigue Quality). Probabilistic analysis has recently been adopted by advanced countries as a new approach to enhancing flight safety in aerospace fields. Probabilistic analysis based on fracture mechanics can especially predict such service life and perform risk assessment using the probability of failure. In this paper, the paradigm of aircraft structural life management is reviewed and the parameter used in probabilistic fracture mechanics is analyzed. Furthermore, the new process of probabilistic risk assessment is proposed to evaluate the statistical factor. In the future, the proposed process can be used to establish aircraft maintenance policies such as RCM (Reliability-Centered Maintenance) and CBM (Condition-Based Maintenance). <Key Words> Aircraft structure, Service life, Fracture mechanics, Probability of failure, Probabilistic risk assessment

폴리머 시멘트 고화체는 일반 몰타르 내의 시멘트 수화물을 폴리머 개질제를 이용하여 부분적으로 대 체함으로써 그 기능을 강화시킨 복합재료로써, 특히 시멘트 몰타르에 폴리머를 첨가하는 것은 그 화학적 내구성을 향상시킨다고 알려져 있다. 따라서 본 연구에서는 고화재료로서의 폴리머 시멘트에 대한 낮은 침투성 및 낮은 이온 확산도 등과 같은 향상된 화학적 내구성을 확인하기 위하여 폴리머 시멘트 시편들을 제조하였다. 이때 폴리머의 함량은 0에서부터 30%까지 변화시켰으며, 물에 대한 시멘트 비(W/C)를 33%와 50%로 각각 유지 시켰다. 충분히 경화시킨 후에, 제조된 시편들에 대한 구조적 건전성을 압축강도와 수침법에 의한 공극도를 통하여 평가하였다. 그 결과, W/C 비가 33%이고, 폴리머 함량이 약 10%인 폴리 머 시멘트 시편에서 가장 향상된 개질변화를 얻을 수 있었다. 끝으로 이 최적의 조합비를 가지는 시편에 대하여 ANS 16.1에 따르는 침출시험을 수행하였으며, 그 결과를 일반 시멘트 고화체와 비교하였다.

Polymer-modified cement is the composite material made by partially replacing and strengthening the cement hydrate binders of conventional mortar with polymeric modifiers such as polymer latexes and redispersible polymeric modifiers. It is known that the addition of polymer to cement mortar leads to improved quality, which would be expected to have a high chemical resistance.Therefore, the purpose of this study is to identify the improved chemical resistance, such as low permeability and low ion diffusivity, of the polymermodified cement as a solidification agent for the radwaste. First, polymer-modified cement specimens by latex modification were prepared according to the polymer content from 0 % to 30 % to select the optimized polymer content. At those specimens, the water-to-cement (W/C) ratio was maintained to 33 % and 50 % respectively. After the much curing time, the structural integrity of specimens was evaluated through the compressive strength test and the porosity evaluation by the water immersion method. From the results, 10 % of the polymer content at 33 % of the W/C ratio was shown to have the most improved quality. Finally, the leaching test referredfrom ANS 16.1 for the specimens having the most improved quality was conducted. Dedicated specimens for the leaching test were then mixed with radioisotopes of Co-60 and Cs-137 at the specimen preparation.

본 논문의 목표는 자기충실성을 도덕적 덕 중 하나인 구조적 덕(structural virtue)으로 가정하는 애덤스의 견해를 비판하는 것이다. 애덤스는 다음과 같이 주장한다. 누군가가 어떤 목표가 악하다는 것을 알고 있음에도 불구하고 그 목표 달성을 이루기 위해 일관적으로 행동할 때, 그 일관성은 자기충실성이란 덕을 부여하는 근거가 될 수 있다. 논자는 우선 애덤스의 덕 이론 체계내에서 그가 어떻게 이와 같은 입장을 견지할 수 있는가에 대해 설명할 것이다. 그 이후 그 입장을 비판하는 근거들을 제시할 것이다. 그 근거들은 다음과 같다. 첫째, 우리는 나쁜 목적을 추구할 때 드러나는 일관성을 탁월하다고 생각하지 않는다. 애덤스에 따르면, 어떤 것이 탁월하지 않으면 그것은 덕이 될 수 없다. 둘째, 나쁜 목적을 일관적으로 추구하는 것을 위해 요구되는 조건들 몇 가지는 덕을 부여하는 것과 조화를 이루지 못한다. 나쁜 목적을 일관적으로 추구하는 것에는 나쁜 동기작용, 나쁜 목적에 대한 승인, 나쁜 것을 즐거워하는 마음 등이 연관된다. 이것들은 덕의 부여와 어울리지 않는다. 셋째, 나쁜 목적을일관적으로 추구하는 것은 과도한 자기관심으로 여겨질 수 있으며 이것은 애덤스 이론에서도 덕이 될 수 없다.

What I pursue in this paper is to argue against Adams’s position regarding the virtue of integrity. Adams’s position is this: manifesting consistency in acting for a bad end can be the basis for an ascription of integrity, even when one does so with the knowledge of the fact that the end is bad. In order to argue against this claim, I will first explain how Adams holds this position in his theory of virtue. And I will offer my arguments against this position. First, I will argue that we do not think that the traits that characterize integrity are excellent when they are manifested in the pursuit of a bad end. Second, I will argue that in the consistent pursuit of a bad end we can find a few conditions that do not go well with an ascription of virtue. The conditions are having bad motivations, making endorsement of a bad end, and having enjoyment in the pursuit of a bad end. Third, I will argue that the consistent pursuit of a bad end can be regarded as an excessive self-concern that Adams takes as a vice in his theory of virtue.

Nuclear fuel, including its fresh state, must be handled safely due to its critical and hazardous nature. Under normal transport conditions, several interactions take place among different components, such as transport cask used for loading the nuclear fuel and tie-down structure to attach with the vehicle. To ensure structural integrity of the nuclear fuel, vibrations and impacts transmitted from the vehicle must be sufficiently reduced. Therefore, in this study, we conducted two transportation tests from Daejeon to Kijang in Korea to verify the vehicle-induced vibrational characteristics of the KJRR-F fresh nuclear fuel when transported under normal transport conditions. The speed and location of the vehicle were obtained via GPS, and the accelerations between the vehicle and the KJRR-F fresh nuclear fuel were measured. Additionally, using the acceleration results, a structural analysis was conducted to confirm the structural integrity of the nuclear fuel under the most severe conditions during normal transport.

Welding is required for a connection between two different components in the nuclear fuel of a pressurized water reactor. This work relies on a mechanical experiment and analytic results to investigate the structural integrity of nuclear fuel in a situation where some components are not welded to each other. A series of lateral vibration tests are performed in a test facility, and the test structures are examined in terms of dynamic behavior. In the tests, the displacement signal at every grid structure that sustains fuel rods is measured and processed to identify the dynamic properties. The fluid-elastic stability of the structure is also analyzed to evaluate susceptibility to a cross flow with an assumed conservative cross flow distribution. The test and analysis results confirm that the structural integrity can be maintained even in the absence of some welding connections.

This study is concerned with structural integrity evaluations for the interference-fit flywheels in reactor coolant pumps (RCPs) of nuclear power plants. Stresses in the flywheel due to the shrinkage loads and centrifugal loads at the RCP normal operation speed, design overspeed and joint-release speed are obtained using the finite element method (FEM), where release of the deformation-controlled stresses as a result of structural interactions during rotation is considered. Fracture mechanics evaluations for a series of cracks assumed to exist in the flywheel are conducted, considering ductile (fatigue) and non-ductile fracture, and stress intensity factors are obtained for the cracks using the finite element alternating method (FEAM). From analysis results, it is found that fatigue crack growth rates calculated are negligible for smaller cracks. Meanwhile, the material resistance to non-ductile fracture in terms of the critical stress intensity factor (K$_{IC}$) and the nil-ductility transition reference temperature (RT$_{NDT}$) are governing factors for larger cracks.