벨로우즈 신축이음관은 구조적 특성으로 인해 큰 변위 용량을 갖으며 과도한 상대변위에 의한 매립 배관 시스템의 손상을 저감시키기 위해 연결부로써 사용된다. 벨로우즈 신축이음관의 내진성능 평가를 위한 연구에서 한계상태는 변형률을 적용하였지만 변형률 기반 한계상태는 벨로우즈 신축이음관의 큰 변위용량을 고려할 수 없다. 또한 벨로우즈 신축이음관의 성능평가와 한계상태 분석을 위한 해석적 및 실험적 연구는 수행된 사례가 극히 적다. 따라서 본 연구는 단조 및 반복하중을 받는 벨로우즈 신축이 음관의 해석적 연구를 통해 벨로우즈 신축이음관의 한계상태를 분석하였다. 결과적으로 단조하중 보다 반복하중을 받는 벨로우즈 신축이음관은 더 낮은 변위에서 누출이 발생하였다. 반복하중으로 인한 피 로 및 라체팅 현상으로 인해 단조하중 보다 낮은 변위의 성능을 갖는 것으로 보여진다. 따라서 반복하 중에서 관측된 변위응답을 기반으로 벨로우즈 신축이음관의 내진성능 평가를 수행하는 것이 보수적일 것으로 판단된다.

우리나라에서 공용중인 시설물은 총 172,111개로 집계되고 있으며, 그 중 교량은 34,199개로 사회 기반시설 중 가장 많은 비중을 차지한다. 이러한 교량은 공용하중, 온도, 습도 등에 의해 거더간 신축 량이 발생하게 되고 신축량 발생으로 인한 유간거리에 대해 차량의 통행 안정성 및 주행성 확보를 위 한 신축이음장치를 설치하게 된다. 신축이음장치를 설치하여 차량의 통행 안정성 및 주행성을 확보할 수 있지만 누수 및 퇴적물 낙하 등을 직접적으로 방지하지 못하여 고무지수재를 별도로 설치하게 된 다. 하지만 이러한 고무지수재는 다양한 원인에 의해 쉽게 손상이 발생한다. 손상된 고무지수재를 통 해 거더의 부식, 교량하부 인명사고 등 다양한 2차 피해가 발생할 수 있다. 피해방지를 위한 교량의 유지관리를 지속적으로 수행하고 있지만 고무지수재 특성상 지속적인 교체가 불가피한 실정이다. 따라 서 본 연구에서는 기존 신축이음장치에 활용되는 고무지수재의 문제점을 해결하기 위하여 초탄성 형 상기억합금을 활용한 새로운 지수재 개발 연구를 수행하였다. 이에 대해 초탄성 형상기억합금 지수재 와 고무지수재에 대한 유한요소해석을 수행하고 비교 및 분석하였으며, 하중 제거 후 원형으로 복원되 는 효과를 통해 지속 사용 가능한 지수재 연구를 검증하였다.

The levels of Indoor radon can increase in newly built apartments that mainly use construction materials such as concrete. However, radon measurement in newly built buildings has only been implemented recently, and there is a lack of sufficient data for radon management purposes. This study aimed to determine the levels of indoor radon in newly built apartments by regions, sizes of household, and floor (lower, middle, upper floor), and to explore the trend of radon reduction by time according to ventilation methods. Indoor radon was measured in 48 households in four regions (Gyeonggi-do and Gangwon-do). Measurements were performed for 48 hours and 24 hours under closed and ventilated conditions using real-time measurement devices FRD400 and RAD7, respectively. To analyze changes in radon concentration by floors, data were collected by dividing households into lower, middle, and upper floors according to their vertical height. The concentrations of indoor radon ranged from 12.1 Bq/m3 to 559.0 Bq/m3 when windows were closed and 12.0 Bq/m3~500.0 Bq/m3 when ventilated (including both mechanical and natural ventilation). On average, the concentration of closed conditions of household when sealed (arithmetic average 185.3 Bq/m3) was 1.5 times higher than the concentration during ventilation (including mechanical and natural ventilation: 123.8 Bq/m3), and around three times higher than the average for mechanical ventilation (65.7 Bq/m3). It was found that the indoor radon concentration statistically increased as the height increased and the size of the house became smaller. Typically, it took 7 to 8 hours to exceed the standard of 148 Bq/m3 after windows were closed. It decreased to less than 148 Bq/m3 within 3 to 4 hours after operating the mechanical ventilation system. However, in the case of natural ventilation, it takes more than 24 hours to reach below the standard value, and the concentrations stagnated after 24 hours. In conclusion, radon concentration in narrow spaces can be relatively high if ventilation is not sufficient due to the nature of apartments with wall-type structures. Therefore, it is necessary to prepare various radon reduction measures according to floor, size, and ventilation methods.

Bellows expansion joints enhance the displacement performance of piping systems owing to their unique geometrical features. However, structural uncertainties such as wall thinning in convolutions, a byproduct of the manufacturing process, can impair their structural integrity. This study addresses such issues by conducting a global sensitivity analysis to assess the impact of these uncertainties on the performance of bellows expansion joints under monotonic loading. Global sensitivity analysis, which examines main and nth order interaction effects, is computationally expensive. To mitigate this, we employed a surrogate model-based approach using an artificial neural network. This model demonstrated robust prediction capabilities, as evidenced by metrics such as the coefficient of determination. The sensitivity indices of the main effect for the 2-ply and 3-ply bellows at the sixth convolution were 0.3340 and 0.3233, respectively. The sensitivity index of the sixth convolution was larger than that of other convolutions because the maximum deformation of the bellows expansion joint under monotonic bending load occurs around it. Interestingly, the sensitivity index for the interaction effect was negligible (0.01%) compared to the main effect, suggesting minimal activity between uncertainty factors across convolutions. Notably, bellows expansion joints under repetitive loading exhibit more complex behaviors, with the initial leakage typically occurring at the convolution. Therefore, future studies should focus on the structural uncertainties of bellows expansion joints under cyclic loading and employ a surrogate model for comprehensive global sensitivity analysis.

PURPOSES : With the recent enactment of the 「Framework Act on Sustainable Infrastructure Management」 in Korea, the establishment of mid- to long-term management plans for social infrastructure and the feasibility evaluation of maintenance projects have become mandatory. To this end, the life cycle cost analysis is essential. However, owing to the absence of a deterioration model, trials and errors are in progress. METHODS : In this study, a deterioration model was established for bridges, which are the representative social infrastructures of roads, particularly for expansion joints that can cause enormous damage to not only the superstructure but also the substructure. The deterioration model was classified into rubber and steel, based on the material of the expansion joint. The analysis used the inspection and climate data conducted in Korea over the last 12 years. The Bayesian Markov Hazard model was applied as the analysis technique. RESULTS : The average life expectancy by type of expansion joint was analyzed to be 8.9 and 6.6 years for rubber and steel, respectively. For probabilistic life cycle cost analysis, the probability distribution of the life expectancy, validity range by confidence level, and Markov transition probability matrix were presented. CONCLUSIONS : In this study, the basis for deterministic and probabilistic life cycle cost analysis of expansion joints was laid. In future studies, it will be necessary to establish a standardized deterioration model for all types of infrastructure, including all bridge elements.

대표적인 비구조요소인 배관의 지진에 의한 손상은 관성력과 두 지지점 사이의 위상차에 의해 작용하는 반복하중 그 리고 허용변형량을 초과하는 상대변위 등에 의해 발생할 수 있다. 특히 주요 손상모드는 큰 반복하중에 의한 저주기피로임이 많은 실험적 연구를 통하여 알려졌다. 따라서 과도한 지진변위에 의한 배관의 손상을 방지하기 위하여 지진상대변위가 발생할 수 있는 위치에 지진분리이음 또는 지진분리장치의 적용이 요구된다. 신축관이음 중 하나인 벨로우즈는 지진분리이음으로 적용 할 수 있다. 본 논문에서는 3ply 금속 벨로우즈 신축관이음의 온도차에 의한 내진성능의 변화를 분석하기 위한 실험적 연구를 수행하였다. 상온환경에서 점진증폭 반복하중재하실험을 수행하였으며, -20°C의 저온조건에서 동일한 실험을 수행하고 그 결과 를 비교하였다. 실험 결과로부터, -20°C의 저온환경에서 금속벨로우즈의 변위성능은 약 10% 저하될 수 있음을 확인하였다.

국내에서 공용중인 교량은 33,177개로 사회기반시설 중 가장 많은 비중을 차지한다. 이러한 교량은 공용하중, 온도, 습도 등에 의해 거더에 신축량이 발생하게 되고, 거더간 유간거리에 대한 안정성을 확보하기 위해 신축이음장치를 설치한다. 신 축이음장치에는 교량의 누수 및 퇴적물 낙하 등을 방지하기 위해 고무지수재를 설치하는 것이 일반적이다. 하지만 이러한 고무 지수재는 다양한 원인에 의해 쉽게 손상이 발생하게 된다. 손상된 고무지수재를 통해 거더의 부식, 교량하부 인명사고 등 다양 한 2차 피해가 발생할 수 있다. 이러한 피해를 예방하기 위해 교량의 유지관리를 수행하고 있지만 고무지수재 특성상 지속적인 교체는 불가피한 실정이다. 따라서 본 연구에서는 기존 신축이음장치에 활용되는 고무지수재의 문제점을 해결하기 위하여 초탄 성 형상기억합금을 활용한 새로운 지수재 개발 연구를 수행하였다. 초탄성 형상기억합금 지수재에 대한 유한요소해석을 수행 및 분석하였으며, 복원 효과를 통해 지속 사용 가능한 지수재 연구를 검증하였다.

배관시스템은 대표적인 사회기반시설이다. 지진으로 인한 배관 손상은 심각한 피해를 초래할 수 있으므로 배관시스 템은 지진으로부터 반드시 보호되어야 할 필요가 있다. 지진은 설계기준을 초과하는 상대변위를 동반할 수 있다. 이러한 지진의 거동은 배관 이음부에 손상을 줄 수 있다. 배관시스템에서 과도한 변형이 발생할 수 있는 위치에 지진분리이음을 적용하면 내 진성능을 향상시킬 수 있다. 적층형 금속 벨로우즈는 지진과 같은 저주기 피로 하중에 대한 내구성이 우수하다. 따라서 다중 적층 형 금속 벨로우즈는 파이프의 면진 이음새로 사용할 수 있을 것으로 판단된다. 본 연구에서는 지진분리이음의 하나인 다중 적 층형 금속 벨로우즈에 대한 실험적 연구를 수행하였다. 2종류의 다중 적층형 벨로우즈 신축관이음에 대하여 단조하중 및 반복 하중재하시험을 수행하고 손상모드와 한계상태를 추정하였다. 그리고 단조재하시험과 반복재하시험의 결과를 비교 분석하였다.

The purpose of this study is to verify how similar the virtual fit pants are to the actual fit of stretchable pants. Data is produced using a virtual model to apply movements. The results show that in the upright position, the similarity between the appearance of the actual fit and the virtual fit is high. Results are 4.47, 4.13 and 4.33 out of 5 on the front, side, and back, respectively. The base line of the front and back, and the amount of allowance in each part were well reproduced by the model. The texture of the virtual fit was evaluated and found to be similar to the actual fabric. In terms of shape and number of wrinkles with the virtual fit pants, large wrinkles were better expressed than fine wrinkles. After applying movements to the virtual model, the front and side results were similar to the actual fit, but the back results were different. As a result of multiple comparisons, the greatest difference in similarity by movements is found in the center front line. The similarity difference was lower on the side than on the front. The only significant difference after applying movements is in the hip circumference margin. According to movements, the similarity of virtual fit is lower on the back than on the front and side, and the back also has the largest similarity differences to the movements type.

상⋅하수도 관로 시설은 대표적인 국가기반 시설물로서 국민생활에 있어서 매우 중요한 라이프 라인이다. 지진으로 인한 관로시설의 손상은 급수의 차단을 유발하여 심각한 피해를 초래할 가능성이 매우 크다. 그러므로 상⋅하수도 관로 시설은 지진으로부터 반듯이 안전하게 보호되어야 할 필요가 있다. 지진 및 지반침하로 인한 설계변위를 초과하는 상대변위는 구조물과 연결되는 배관의 이음부에서 손상을 발생시킨다. 벨로우즈형 신축이음관은 온도차에 의한 배관의 팽창 및 변형을 흡수하고 기계진동에 의한 배관의 손상을 막기 위한 장치이다. 본 연구에서는 매설된 상⋅하수도 관로를 보호하고자 지진변위와 지반침하 대응을 목적으로 벨로우즈를 적용하였다. 적층형 하이드로포밍 메탈 벨로우즈는 기존의 벨로우즈와 달리 지진과 같은 저주 기피로하중에 대한 내구성이 우수하다. 따라서 3ply 벨로우즈형 신축이음관을 대상으로 반복가력 굽힘시험을 수행하고 지진안전성과 내침하성능을 평가하였다. 그 결과, 3ply 벨로우즈형 신축이음관은 8.8°이상의 횡방향 변형각에 대응할 수 있는 것으로 나타났다.

배관 시스템은 다양한 산업영역에서 액체 및 기체로 이루어진 에너지를 수송을 담당하는 중요한 비구조요소로 지진과 같은 외부하중에 의해 손상될 경우 누수로 인한 홍수 및 가연성 가스 누출로 인한 화재 등의 2차피해가 발생할 수 있다. 배관 시스템은 구조물 내부에 설치되는 경우도 있으며 지반에 매립되어 설치되는 경우도 있다. 지반에 매립될 경우 지진으로 인한 과도한 상대변위에 의해 연결부의 손상을 초래할 수 있어 종종 벨로우즈 신축이음관을 적용하여 이러한 피해를 저감시킬 수 있다. 따라서 본 연구에서는 벨로우즈 신축이음관의 반복가력 실험을 기반으로 유한요소 모델을 구축 하여 내진성능을 검토하였다. 반복가력실험은 ±28mm 변위에서 최대 ±123.4mm까지 증가시켜 변위제어를 통해 수행되었으며 추가적으로 유한요소 모델의 신뢰성을 높이기 위해 벨로우즈 배관에 사용된 재료인 STS304의 재료 인장실험을 수행하여 탄성계수 및 항복응력을 결정하였다. 에너지 소산량과 등가 점성 감쇠를 비교하여 개발된 모델의 타당성을 검토하였으며 적용되는 변위가 커짐에 따라 최대 10% 미만의 오차가 발생하여 실험 및 해석결과가 잘 일치하는 것으로 나타났다.

Domestic dust remover began to be manufactured and installed in the late 1980s by introducing Japanese products and technologies. Currently, the design standards of dust remover are applied to Japan's design standards and partly sub-unit technology was developed for the domestic environment, but no technology was not developed. In addition, most of the manufacturers are small or small, so many of them have been installed and operated for 25 years because they develop small technologies such as parts deformation and functional addition rather than core technology development. Mechanical dust remover require about 70% of manufacturing costs compared to conventional hydraulic dust remover, which can reduce initial production costs, reduce maintenance costs due to low failure rates, and can be operated reliably. Existing hydraulic dust remover had a problem of contaminating rivers due to leakage of hydraulic oil, but mechanical dust remover have no factors that cause water pollution. Therefore, this study developed a rack-type operating structure for optimal and new construction by developing a multi-stage rack structure of mechanical decontamination components, which are substitutes of conventional rotary and hydraulic dust remover.

Indoor air environments for people are recently being observed because the time we spend inside the house or a building throughout the day has been extended during the present circumstances. This is why formaldehyde and volatile organic compounds (VOCs) are regulated, which can cause Sick Building Syndrome (SBS). There might be other VOCs not regulated by law in newly built collective housing, however, in order to compensate for the reduced concentration of regulated VOCs such as benzene, toluene, ethylbenzene, xylene, and styrene. In this study, the concentration of unregulated VOCs in newly built collective housing structures located in the Seoul Special City was researched to find potential indoor hazards for citizens and to prepare basic data for further research.

Pipe for water supply is one of the important parts that supply water to home, factory and so on. Water leakage in pipe for water supply due to deterioration, ground sinking and earthquake leads to enormous economical loss. Therefore, pipe for water supply should be designed to satisfy the requirement of, for instance, structural stability and fatigue durability. The purpose of this study was to investigate the fatigue durability of flexible joint for relaxing the impact due to earthquake and ground sinking. For this purpose, flexible joint was simulated using dynamic characteristics and fatigue life. As the results, the problem of fatigue durability may occur when flexible joint and pipe for water supply are treated as rigid body in simulation. Thus it means that the role of packing in flexible joint is very important and packing should be designed as optimal conditions that are considered fatigue durability as well as waterproof.

The pipe for water supply is essential part among SOC (Social Overhead Capital) fields. Pipe for water supply is mainly damaged by deterioration of pipe, earthquake, ground sinking and so on. The leakage of water have been led to enormous economical loss in our country. The purpose of this study was to investigate the structural stability of flexible joint for relaxing impact due to earthquake and ground sinking. For this purpose, flexible joint was simulated using tensile load and internal pressure. As the results, flexible joint for structural stability was needed the tensile load of below 3 ton and internal pressure of below 60 kgf/cm2. However, it is considered that real flexible joint should be applied more high safety factor than that of simulation result because of combined stress.

We report on stretchable electrochromic films of poly(3-hexylthiophene) (P3HT) fabricated on silver nanowire (AgNW) electrodes. AgNWs electrodes are prepared on polydimethylsiloxane (PDMS) substrates using a spray coater for stretchable electrochromic applications. On top of the AgNW electrode, poly(3,4-ethylenedioxythiophene):poly(styrene sulfonate) (PEDOT:PSS) is introduced to ensure a stable resistance over the electrode under broad strain range by effectively suppressing the protrusion of AgNWs from PDMS. This bilayer electrode exhibits a high performance as a stretchable substrate in terms of sheet resistance increment by a factor of 1.6, tensile strain change to 40%, and stretching cycles to 100 cycles. Furthermore, P3HT film spin-coated on the bilayer electrode shows a stable electrochromic coloration within an applied voltage, with a color contrast of 28.6%, response time of 4-5 sec, and a coloration efficiency of 91.0 cm2/C. These findings indicate that AgNWs/PEDOT:PSS bilayer on PDMS substrate electrode is highly suitable for transparent and stretchable electrochromic devices.

In 1961, the Republic of Korea’s first newly-constructed government building was completed. The government building, as ROK office, was erected as a twin with the USOM office in Sejong-ro. The reason why the ROK office and the USOM office were erected as a twin building is that the two offices were part of Foreign Operation Administration’s Seoul Buildings Project in 1954. Within the project, the FOA office and the ROK office were rarely separated, and naturally, the ROK office was built according to the US standards. The planning, design, and construction phases which led by the US government were involved in the US architecture, engineering-construction companies. Because those AEC companies were familiar with the US technology and standards. In the phase of construction, Korean companies took part in the process under the supervise of Vinnell Corporation. The US expected to transfer its ‘modern’ and ‘developed’ technology through this process. The completed ROK office was widely known as the ‘modern style (hyundae-sik)’ building, which was body forth as glasses and new facilities. These factors were what the US emphasized for exporting architecture. The modifier, ‘modern style (hyundae-sik)’, given to the ROK office in the 1950s was a synonym for any new feeling that had never been seen hitherto. The newness of the ROK office, the ‘modern style (hyundae-sik)’ building, was specified as materials and facilities that indicates modern technology while in the absence of adequate knowledge.