• Proceedings of the Korean Institute of Surface Engineering Conference
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• 2011.05a
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• pp.80-80
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• 2011

세계 기후 변화와 불안정한 유가 변화에 대응하고 국내산업의 저탄소 녹색성장을 위해 신재생에너지 개발이 활발하게 이루어지고 있다. 해양에너지 중에서 조류발전은 대규모 댐을 건설할 필요가 없어 비용이 적게 소요되고 특히 날씨 변화나 계절에 관계가 없고, 발전량이 예측 가능하므로 신뢰성 있는 에너지원으로 적용이 가능하다. 조류발전기 블레이드에 폴리머계 복합재료와 스테인리스강이 대부분인데, 이 재료는 특정 회사에서만 제작 가능하며, 충격에 약하고, 균열전파 속도가 빠르며, 대단히 고가이며, 수입에 의존하고 있는 실정이다. 이러한 조류발전에 사용되는 블레이드는 가혹한 부식, 캐비테이션 그리고 침식환경에 노출되어 있어 내구성이 우수한 제품개발이 대단히 중요하며, 조류발전 블레이드를 동합금으로 제작시, 내식성이 뛰어나며 구리의 특성상 해양생물 서식을 방지할 수 있고, 내캐비테이션 특성, 내구성, 가공성 및 유지보수가 용이한 장점이 있다. 이러한 동합금에 WC-27NiCr와 WC-10Co4Cr를 초고속 화염용사(HVOF)를 이용하여 코팅층의 캐비테이션 특성 및 전기화학적 거동을 연구하였다. 본 연구에서는 조류발전용 블레이드의 재료로 사용하려는 동합금에 WC-27NiCr와 WC-10Co4Cr이 용사코팅된 시험편을 사용하였다. 다채널 부식시험기인 WonA-tech WMPG-1000을 이용하여, 자연전위를 측정하였으며, 분극실험은 자체 제작한 홀더를 사용하여 $0.3318cm^2$를 노출 시켜 실험하였다. 기준전극은 은/염화은 전극을, 대극은 백금 전극을 사용하였다. 양분극과 음분극 실험을 통해 개로전위에서의 부식거동을 확인하였고, 정전위 실험도 실시하였다. 실험 종료 후 3D현미경 및 전자주사현미경(SEM)을 사용하여 코팅층 표면의 손상거동을 관찰하였다. 캐비테이션 실험은 ASTM-G32 규정에 의거하여 압전효과를 용한 진동발생 장치(RB 111-CE)를 사용하였다. 수조는 전기화학적 부식의 영향을 고려하여 아크릴로 제작하였고, 시험편은 실험장비에 맞게 파인커팅머신을 이용하여 $20mm{\times}20mm$로 절단하여 사용하였으며 혼과 대향하도록 하여 1mm 간격을 두어 실험하였다. 실험 실시 전, 미소전자저울을 사용하여 무게감소량을 측정하였으며 표면관찰을 통하여 캐비테이션 거동을 관찰하였다.

• Journal of the Korean Society of Marine Environment & Safety
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• v.27 no.4
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• pp.521-528
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• 2021

In this study, to repair damaged economizer fin tubes on ships, sealing treatment was performed after applying arc thermal spray coating technology using Inconel 625. A solid particle erosion (SPE) experiment was conducted according to ASTM G76-05 to evaluate the durability of the substrate, thermal spray coating (TSC), and thermal spray coating+sealing treatment (TSC+Sealing) specimens. The surface damage shape was observed using a scanning electron microscope and 3D laser microscope, and the durability was evaluated through the weight loss and surface roughness analysis. Consequently, the durability of the substrate was superior to that of TSC and TSC+Sealing, which was believed to be owing to numerous pore defects in the TSC layer. In addition, the mechanism of solid particle erosion damage was accompanied by plastic deformation and fatigue, which were the characteristics of ductile materials in the case of the substrate, and the tendency of brittle fracture in the case of TSC and TSC+Sealing was confirmed.

• Journal of the Korea institute for structural maintenance and inspection
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• v.25 no.1
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• pp.103-111
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• 2021

Naju Seokdanggan, Treasure No. 49, was dismantled and reconstructed due to poor performance. During construction, the crack area was reinforced and the inclination was improved. It is necessary to analyze the stiffness changes before and after the reconstruction of these cultural properties, and to establish a database of related information. In addition, there is a need for research on a scientific non-destructive testing method capable of predicting or evaluating the reinforcing effect. In this study, a simple equation for estimating the overall stiffness of the structural system was derived from information on the elasticity coefficient and the natural frequency measured by vibration tests before and after reconstruction work, and the applicability of the equation was examined. If the stiffness of important cultural properties is regularly investigated by the suggested method, it is judged that it can be used as data to estimate the time when structural safety diagnosis is necessary or when repair or reinforcement is necessary.

• Journal of the Korea Institute of Building Construction
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• v.21 no.4
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• pp.257-268
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• 2021

This study analyzed the major issues of 24 defect litigation precedents before and after 2013, based on 2013, when defect litigation in relation to the rapidly increasing defect disputes in apartment houses. The amount of defect removal per household is 2,572 thousand won per household, which is about 5% less than before 2013 from 2013, but the judgment amount per household has rather increased by about 19%, showing 1,916 thousand won per household after 2013. By type of construction, defects on cracks accounted for the largest proportion before and after 2013. Before 2013, equipment, tiles, and windows appeared in the order, and after 2013, landscaping, tiles, insulation and window work were in the order. In order to prevent such defect disputes, efforts to prevent defect disputes will be needed in the design stage, construction stage, and maintenance stage.

• The Journal of the Convergence on Culture Technology
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• v.7 no.4
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• pp.727-734
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• 2021

The purpose of this study is to analyze the perception of the residents of the new city by examining the consciousness of the occupants to understand the characteristics of the residents of the city of Bundang. As a result of evaluating and analyzing the durability by visual inspection and some equipment tests at the site of the on-site investigation, it was found that there is a problem with the quality, and continuous maintenance is required to improve the durability and usability of the apartment house. In particular, many cracks appearing in the rapidly deteriorated part should be repaired promptly, and a systematic plan should be formulated and carried out. In the apartment housing perception survey of Bundang new city residents, about 93.4% showed above-average satisfaction, and 43.4% showed a favorable preference toward the residential area.

• Journal of Korea Entertainment Industry Association
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• v.15 no.8
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• pp.75-89
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• 2021

In this paper, the results of analyzing the meaning of laughter in comedy movies of the late 1960s, focusing on comedians, Hee-Gap Kim, Bong-Seo Koo and Young-Chun Seo, are as follows. First, the narrative laughter of the comedians represents the generational conflict between the lower class and the upper class, the gender conflict between men and women, and the frustration of reality. Second the mechanism of creating laughter of the comedians shows ridicule of the conservative older generation, revelation of the immoral upper class, and caricature of the frustrated lower class. Third, the practical aspect of the comedians' laughter reveals cracks in tradition and modern, gaps in economic inequality, and expression of prohibited desires. Therefore, comedians Hee-Gap Kim, Bong-Seo Koo and Young-Chun Seo in comedy movies of the late 1960s show the semantic effect of laughter of internal/external boundaries and optimistic world views through the closed opening of informal culture and the conflict of characters/performers.

• Proceedings of the Korea Water Resources Association Conference
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• 2023.05a
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• pp.482-482
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• 2023

상수도관은 사용년수가 경과함에 따라 노후화가 진행되며, 노후화된 상수관은 내부적으로 부식, 이물질 퇴적, 균열 등의 현상이 발생하게 되고, 이는 결국 수질문제로 연결되어, 탁수사고 발생 확률증가의 주요 원인이 되고 있다. 국내 상수도관의 경우 매설년수의 증가로 인해 내구연한이 도래한 상수관망의 비중이 점차 증가하고 있으며, 2019년 서울시 문래동 수질사고, 2019년 인천 붉은 수돗물 사고, 2022년 안양 동안구 탁수사고, 2022년 여수시 웅천 탁수사고 등 관의 노후화로인한 탁수 사고가 빈번하게 발생되고 있어 수도 사용자에게 불편함을 끼치고 있다. 현재 정수장 및 상수관망에 설치된 탁도계를 통해 수질에 대한 감시를 진행하고 있지만, 경제적인 문제로 인해 모든 상수도관에 탁도계를 설치하기에는 현실적으로 불가능하며, 제한적인 탁도계의 개수를 통해 수질에 대한 감시 및 관리를 진행하고 있는 실정이다. 이러한 상황으로 인해 탁수사고 발생 시 발생 원인분석 및 최초 발생위치 결정이 쉽지 않으며, 보수 보강을 통한 상수도관의 정상화까지 오랜 시간이 걸리게 된다. 이에 본 연구에서는 상수관망에서 탁수 발생 시 최초 발생 위치를 결정할 수 있는 기법을 개발하였으며, 이를 실제 상수도관망에 적용하여 탁수발생 파이프를 탐지하였다. 탁수사고 발생 시 실측된 수질 데이터의 부족으로 인해 임의의 파이프에서 탁수가 발생하였다고 가상의 탁수 발생시나리오를 가정하였으며, 완전혼합농도식을 통해 관망에 설치된 탁도계의 NTU(Nethelometric Paultity Unit) 농도를 계산하여 가상의 탁수발생 시나리오를 상수도관망에 적용하였다. 이후, 역추적 계산기법을 통해 파이프의 초기 NTU 농도를 변화시켜주며 관망내 설치된 탁도계의 NTU 농도를 계산하였으며, 가상 시나리오를 적용하여 계산된 탁도계의 NTU 농도와 역추적 계산법을 적용하여 계산된 탁도계의 NTU 농도의 Percentage Error를 비교/분석하여 탁수 발생 파이프를 탐지하였다. 분석결과, 가상 시나리오의 최초 탁수발생 파이프와 역추적 계산법을 적용하여 탐지한 최초 탁수발생 파이프의 위치가 일치하는 것으로 나타났다. 본 연구에서 개발된 역추적계산을 통한 탁수발생 파이프 탐지기법을 실제 관로 교체사업에 활용한다면 파이프의 개선 우선순위를 보다 명확하게 판단할 수 있으며, 더 나아가 상수도 관망의 유지관리에 활용하여 경제적이고 효율적인 상수관망 시스템관리를 할 수 있을 것으로 판단된다.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.44 no.2
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• pp.237-244
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• 2024

Pavement management systems (PMS) provide procedures to quantify road serviceability based on pavement conditions such as cracks and plastic deformation and suggest proper maintenance methods. The deterioration of the road pavement is relevant to the time although the quantifications on road serviceability in PMS present road surface conditions at the evaluation. More systematic evaluation on road serviceability may need time-dependent factors of road environments and that can improve PMS. Rainfall, temperature and vehicle loads can be environmental factors for road serviceability evaluation. As no data are avablie that can link between road conditions and environmental road factors, we conducted experiments to suggest economical devices and methods to obtain relevant data. We used temperature sensors and accelerometers with Arduino to measure road surface temperature and dynamic loads and provide data to improve pavement serviceability evaluation.

• Journal of the Korean Institute of Traditional Landscape Architecture
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• v.37 no.1
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• pp.1-11
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• 2019

This study was conducted to analyze the conservation status by diagnostical methology for the front wall of Jungjeongdang area of Dodong-Seowon. The study was carried out as photogrammetry and mapping - investigation of materials and conservation status - analysis and evaluation of conservation status. The results are as follows. First, in the case of photogrammetry, each photograph was took in superposition, and the distortions of the photographs were corrected and synthesized. Based on this, actual survey drawings of the wall were prepared. Second, in case of material and conservation status, the wall is in the form of Wapyeondam and the material of the head part are tile, mud and lime, and the material of the body part are mud and tile. The mud was mixed with gravel, sand and straw. At the base part, amorphous natural stones and mud were used. The remarkable damage that appears on the wall is erosion of the base part, and some disintegration appears in the body part. There is a biological patina on the head and the base, and vegetation such as lichen is concentrated on the partial body. There was superficial deposit in the head part, and some tiles were broken or lost. Deep fissures are intensively located in some part of the eastern wall. Third, in the case of analysis and evaluation of the conservation status, it is considered that by the erosion of the foundation part and the disintegration of the body part, there is a possibility that physical damage will continue to be applied to the wall, so immediate action is necessary. The distribution of biological patina and vegetation does not appear to cause great problems in the wall, but it is necessary to reduce it in view of aesthetic problems. A cracked or missing tile would need to be replaced, and deep cracks in the eastern wall appear to have been caused by subsidence, and reinforcement of the underground is necessary to prevent further damage.

• Journal of the Korea institute for structural maintenance and inspection
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• v.25 no.6
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• pp.245-253
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• 2021

RC slab bridges account for the largest portion of deteriorated bridges in Korea. However, most RC slabs are not included in the first and second classes of bridges, which are subject to bridge safety management and maintenance. The highest damaged components in highway bridges are the subsidiary facilities including expansion joints and bearings. In particular, leakage through expansion joints causes deterioration and cracks of concrete and exposure of reinforced bars. Therefore, this study analyzed the effect of adhesion damage at expansion joints on the response of the deck in RC slab bridges. When the spacing between the expansion joints at both ends was closely adhered, cracks occurred in the concrete at both ends of the deck due to the resistance rigidity at the expansion joints. Based on the response results, the correlation analysis between displacements in the longitudinal direction of the expansion joint and concrete stress at both ends of the deck for each damage scenario was performed to investigate the effect of the occurrence of damage on the bridge behavior. When expansion joint devices at both sides were damaged, the correlation between displacement and stress showed a low correlation of 0.18 when the vehicles proceeded along all the lanes. Compared with those in the intact state, the deflections of the deck in the damaged case at both sides showed a low correlation of 0.34 to 0.53 while the vehicle passed and 0.17 to 0.43 after the vehicle passed. This means that the occurrence of cracks in the ends of concrete changed the behavior of the deck. Therefore, data-deriven damage detection could be developed to manage the damage to expansion joints that cause damage and deterioration of the deck.