결과 내 재검색





        검색결과 41

        2023.08 KCI 등재 구독 인증기관 무료, 개인회원 유료
        In this study, non-destructive technologies that can be applied to evaluate the integrity of valve materials, safety against internal pressure caused by corrosion, and the blocking function of large-diameter water valves during operation without requiring specimen collection or manpower entering the inside of the valve were tested to assess the reliability of the technologies and their suitability for field application. The results showed that the condition of the graphite structure inside the valve body can be evaluated directly through the optical microscope in the field without specimen collection for large-diameter water butterfly valves, and the depth of corrosion inside the valve body can be determined by array ultrasound and the tensile strength can be measured by instrumented indentation test. The reliability of each of these non-destructive techniques is high, and they can be widely used to evaluate the condition of steel or cast iron pipes that are significantly smaller in thickness than valves. Evaluation of blocking function of the valves with mixed gas showed that it can be detected even when a very low flow rate of mixed gas passes through the disk along with the water flow. Finally, as a result of evaluating the field applicability of non-destructive technologies for three old butterfly valves installed in the US industrial water pipeline, it was found that it is possible to check the material and determine the suitability of large-diameter water valves without taking samples, and to determine the corrosion state and mechanical strength. In addition, it was possible to evaluate safety through the measurement results, and it is judged that the evaluation of the blocking function using mixed gas will help strengthen preventive response in the event of an accident.
        2019.12 KCI 등재 구독 인증기관 무료, 개인회원 유료
        본 연구에서는 방사선 촬영 기법을 사용하여 국내에 서식 하는 무미양서류인 청개구리 (Hyla japonica), 옴개구리 (Glandirana rugosa), 참개구리 (Pelophylax nigromaculatus), 황소개구리 (Lithobates catesbeianus)의 체성분과 골밀도를 분석하였다. 이중 엑스선 촬영 장치 (Dual-energy Xray absorptiometry)를 사용하여 체성분과 골밀도를 측정하 였으며 암수 간 차이와 종 간 차이를 파악하였다. 또한 방사선 촬영 기법을 사용한 신체 상태 평가 방법의 효용성을 확인하기 위해 무미양서류 4종의 먹이자원 가용성을 파악하고 신체상태와의 관계를 확인하였다. 신체를 구성하는 성분인 골, 지방, 제지방 비율과 골밀도는 암수 간 차이가 없었지만 무미양서류 4종 간 차이는 있었다. 골밀도와 먹이자원 가용성은 황소개구리가 가장 높았으며 청개구리가 가장 낮았다. 옴개구리와 참개구리의 먹이자원 가용성은 차이는 없었다. 골밀도와 먹이자원 가용성은 유의미한 상관관계를 가졌으며 먹이 상태를 나타내는 질소 안정동위원소비는 골밀도에 의해서만 변화하는 것을 확인하였다. 기회적 포식자인 무미양서류의 먹이 상태 혹은 자원 가용성이 체성분은 물론 골밀도에 영향을 미칠 수 있다. 개체의 신체 상태를 나타내는 체성분과 골밀도는 무미양서류에서 서식지의 안정성을 평가하는 생태지표로서 사용이 가능할 것으로 보인다.
        2018.04 구독 인증기관 무료, 개인회원 유료
        Due to the sewer induced ground subsidence, there is an increasing demand for the advanced visual inspection technique for the existing sewer pipe structures. This study aim to develop a new condition assessment method using visual inspection device with automatic crack extracting and real-time gas monitoring systems for large diameter glass-fiber reinforced plastic sewer pipes. In this paper, a high-precision image capturing system that automatically extracts cracks in the large-diameter sewer pipes and sewage culverts with a diameter of 1,000 mm or more, and a real-time gas detection sensor for investigator safety were considered. By analyzing the module technology of the visual inspection device, the test device and their software for system integration were developed. It is expected that the developed technique inspecting conditions of the GFRP sewer pipes using the proposed visual inspection device in this study can be effectively used for various types of underground structures in the future.
        2018.04 구독 인증기관·개인회원 무료
        Haemaphysalis longicornis (Acari: Ixodidae) is a medically important arthropod vector of tick-borne diseases, especially the severe fever with thrombocytopenia syndrome (SFTS). To establish a management strategy against tick-borne diseases, it is fundamental to understand the basic biology of vector species. Therefore under laboratory conditions, we evaluated the horizontal movement of adult and nymph stages of H. longicornis to better understand their dispersal behaviors. In the experiments, field populations were subjected to video recording of the horizontal movement of the ticks in a petri-dish arena for 3 hours. Our results indicate that nymphs showed a significantly higher mobility than adults, whereas there was no significant difference in angular velocity. Nymphs moved 3.74 ± 0.26 m at an angular velocity (AV) of 1.60 ± 0.07 deg/s. and adults moved 2.91 ± 0.26 m at an AV of 1.61 ± 0.14 deg/s.
        2018.02 KCI 등재 구독 인증기관 무료, 개인회원 유료
        금강의 하천관리의 실질적인 자료를 얻고자 본류와 미호천의 30지소에서 수변식생지수를 이용하여 건강성평가와 다변량식생분석을 하였다. 그 결과 금강본류와 미호천에서 출현한 식물군락은 54개이었고, 식물상은 75과 185속 243종 2아종 21변종 2품종 268분류군이었다. 수변식생지수는 평균 38.3(3.3;G-D1 ~ 66.7;G-U2, G-U4, G-M3)으로 이 지역의 하천의 건강성은 보통(C등급)으로 평가되었다. 하천의 건강성은 금강본류의 상류가 가장 높았고, 금강본류의 하류에서 가장 낮았다. 수변식생지수와 수질의 클로로필-a의 함량과의 관계는 관련성이 낮게 나타났다. 집락분석결과, 식생은 바랭이군락 그룹, 갯버들군락 그룹, 개망초군락 그룹, 환삼덩굴, 버드나무, 물억새 그리고 달뿌리풀 군락이 우점하는 그룹, 망초와 물피 군락이 우점하는 그룹 등의 5개 집단으로 나누어졌고, 지소들은 비슷한 건강상태를 갖는 것들끼리 가까이 나타났다. CCA분석결과, 식생의 분포에 영향을 주는 환경요인은 식생면적, 인공구조물 면적, 수로면적, 지점폭, 수로폭, 제방높이 등의 물리적인 조건과 생물학적 요인의 출현종수였다. 이상과 같이 하천의 건강성이 높은 지역은 모니터링을 통하여 하천 식생의 지속적인 유지관리가 필요하고 건강성이 낮은 지역은 생태복원과 같은 적극적인 시행이 필요하다고 판단된다.
        2017.10 구독 인증기관·개인회원 무료
        In order to get as ecological basic data for river management, We estimated health condition of Geum-river mainstream and Mihocheon using vegetation and investigated it for phytosociologic methods. Then, collected data was analysed. Appeared plants in study area were 268 species and the number of appeared plant colonies was 54. Riparian vegetation index(RVI), vegetation health condition assessment method, was evaluated as 38.3 ‘Normal(C)’. Geum-river mainstream's upper stream1(G-U1), upper stream4(G-U4) and mid stream3(G-M3) were highest as 66.7 and Geum-river mainstream's down stream1(G-D1) was lowest by 3.3.Riparian vegetation index under upper stream, middle stream, down stream in Geum-river mainstream and Mihocheon was highest in Geum-river mainstream's upper stream and lowest in Geum--river mainstream's down stream. Riparian vegetation index was negatively correlated with biological oxygen demand(BOD) and chlorophyll-a(Chl-a) in study sites.PCA using species cover degree data of belt transect in each study sites was separated by two groups. One group was consisted of ‘best(A grade)’ and ‘good(B grade)’, the other group was comprised of ’normal(C grade)‘ and ’bad(D grade)’. Cluster analysis was separated by 5 groups: Digitaria ciliaris Koel. community group, Salix gracilistyla Miq. community group, Erigeron annuus Pers. community group, Humulus japonicus Siebold & Zucc., Salix koreensis Andersson, Miscanthus sacchariflorus Benth., and Phragmites japonica Steud. community group, Conyza canadensis Cronquist and Echinochloa crusgalli var. echinata Honda community group. Study sites having similar health condition also was grouped in analysis. These result was similar in PCA. Dominance value of study sites was significantly correlated with vegetation area, structure area, waterway area, spot width, waterway width, bank height and number of species in CCA analysis. As a result, it means that the high health condition sites are dominated by Salix, Fraxinus and phragmites spp. increasing plant diversity and the low health condition sites have a wide structure area simplifing plant diversity by river maintenance work. Thus, the hight health condition area needs to maintain condition through continuous monitoring and the low health condition area needs to restore ecosystem services.
        2017.04 구독 인증기관 무료, 개인회원 유료
        Due to the sewer induced ground subsidence, there is an increasing demand for the advanced visual inspection technique for the existing sewer pipe structures. This study aim to develop a visual inspection device and real-time transmission system of inspection data with precisely evaluated structural and operational conditions of underground sewer pipe structures. In this paper, a high-precision image capturing system that automatically extracts cracks in the large-diameter sewer pipes and sewage culverts with a diameter of 1,000 mm or more, a real-time gas detection sensor for investigator safety were studied. By analyzing the module technology of the visual inspection device, the concept design for system integration was derived, and the real time transmission system of the inspection result was developed to establish the technical basis for the commercialized device. Also the crack detection test using crack calibration was carried out for the proposed image capturing camera system, and the position accuracy using L1 grade GPS module was tested in this study. The inspection technique of the existing structure condition using the visual inspection device in this study can be effectively used for various structures types and advanced composite structures in the future.
        2016.10 KCI 등재 구독 인증기관 무료, 개인회원 유료
        PURPOSES : Road subsidence occurs owing to road cavities, which cause many social and environmental problems, especially in cities. Recently, road cavities were detected by various ground radars and repair works were carried out against the detected cavities. The condition assessments related to the road cavities are necessary to understand the potential risk of the cavities. Therefore, in this study, a numerical study was performed to assess the various conditions of road cavities. METHODS : The numerical method adopted in this study is the discrete element approach, and it is suitable for analyzing the condition because it can consider the movement of the soil particles in the surrounded cavity areas. In addition, the triaxial test was modeled and performed under various cavity conditions inside the specimens. RESULTS: The conditions of different cavity locations and shapes were analyzed to identify the effect of cavity state. Three general cases of particle size distributions were formulated to identify the effect of surrounding ground conditions. As a result, the degree of decrement and volumetric strain were varied depending on the locations and shapes of the cavity. Only minor changes were observed when the particle size distributions were altered. CONCLUSIONS: The strength reduction was higher when the cavity formed was larger and located in the upper zone. Similar to the cavity shape, strength reduction and volume deformation are more influenced by the width than the length of the cavities. There is an influence from ground conditions such as the particle size distribution, especially on the wide cavity.
        2015.08 KCI 등재 구독 인증기관 무료, 개인회원 유료
        본 연구는 주왕산국립공원의 주요 탐방로의 물리적 상태, 훼손 유형 및 환경피해도를 평가함으로써 탐방로의 유지관리와 복원을 위해 수행되었다. 주요 탐방로는 주봉 구간, 가메봉 구간, 장군봉~금은광이 구간, 월외 구간 등 4개 구간이다. 노선길이의 경우 주봉 구간 4.6㎞, 가메봉 구간 3.6㎞, 장군봉~금은광이 구간 5.6㎞, 월외 구간 5.9㎞이다. 물리적 상태의 경우 노폭은 주봉 구간이 가장 넓었고 장군봉~금은광이 구간이 가장 좁았다. 나지폭은 주봉 구간이 가장 넓었고 장군봉~금은광이 구간이 가장 좁았다. 침식깊이는 가메봉 구간이 가장 깊었고 월외 구간이 가장 얕았다. 경사는 장군봉~금은광이 구간이 가장 급했고 가메봉 구간이 가장 완만하였다. 토양경도는 가메봉 구간이 가장 높았고 월외 구간이 가장 낮았다. 훼손유형 출현 횟수의 경우 주봉 구간 71회, 가메봉 구간 62회, 장군봉~금은광이 구간 63회, 월외 구간 78회로 나타났다. 환경피해도의 경우 노면침식은 Ⅰ등급과 Ⅱ등급이 유사하였으며, 나머지는 Ⅰ등급이 대체적으로 많기 때문에 건전한 상태인 것으로 생각된다. 향후 탐방로의 지속적인 관리를 위해서는 다양한 환경요소를 고려한 종합적인 연구가 진행되어야 할 것이다. 그리고 훼손된 탐방로는 주변 환경과 생태계를 고려한 복원계획의 수립이 필요하다.
        2015.02 KCI 등재 구독 인증기관 무료, 개인회원 유료
        A CCTV inspection method has been widely used to assess sewer condition and performance, but Korea lacks a proper decision support system for prioritizing sewer repair and rehabilitation (R&R). The objective of this paper is to introduce the results that we have developed in the Sewer Condition Assessment and Rehabilitation Decision-making (SCARD) Program using MS-EXCEL. The SCARD-Program is based on a standardized defect score for sewer structural and hydraulic assessment. Priorities are ranked based on risk scores, which are calculated by multiplying the sewer severity scores by the environmental impacts. This program is composed of three parts, which are decision-making for sewer condition and performance assessment, decision-making for sewer R&R priority assessment, and decision-making for optimal budget allocation. The SCARD-Program is useful for decision-makers, as it enables them to assess the sewer condition and to prioritize sewer R&R within the limited annual budget. In the future, this program logic will applied to the GIS-based sewer asset management system in local governments.
        2004.06 KCI 등재 구독 인증기관 무료, 개인회원 유료
        본 연구에서는 보통의 조리조건과 위생적 조리조건에서 김밥을 조리하였을 때에, 각 조리조건하에서의 식자재(원재료),조리자의 손, 조리환경(조리기구 및 조리실),그리고 완성된 김밥의 미생물 품질을 살펴보고 이를 토대로 김밥조리과정 중의 중요관리점(CCPs)을 관찰하였다. 김밥과 그 원재료, 조리자의 손, 그리고 조리기구(칼, 도마 및 김발)의 표준평판균, 대장균군, 분변성대장균군, 대장균, 황색포도상구균, 살모넬라균 등의 미생물을 식품공전에 준하여 측정하였으며 조리실의 미생물 오염도를 평가하였다. 모든 시료에서 대장균, 황색포도상구균 및 살모넬라균은 검출되지 않았으며 표준평판균, 대장균군 및 분변성대장균군은 보통의 조리조건에서보다 위생적 조건에서 현저하게 낮았다. 김밥 원재료 중 비가열재료에서는 가열재료보다 표준평판균 및 대장균군수가 많이 검출되었다. 두 조건에서조리실의 공중낙하균은 모두 양호한 수준이었다. 위생적 조리조건에서 만든 김밥은 보통의 조리조건에서 만든 김밥에 비하여 표준평판균과 대장균군이 1/100수준이었으나 아직 분변성대장균군이 검출되었다. 따라서 비가열재료, 조리기구 및 조리자의 손의 미생물 오염, 그리고 조리 중의 교차오염이 김밥 미생물 오염의 주요 근원으로 지적되며, 비가열재료의 취급, 조리기구의 세척과 소독 및 조리자의 손씻기 단계가 CCPs로 제시된다.
        2019.10 서비스 종료(열람 제한)
        본 논문은 적재설비의 바닥 구속조건에 따른 안전성을 평가하고자 한다. 평가를 위해서 국내에서 일반적으로 사용하고 있는 파렛트랙을 대상구조물로 선정하여 진동대 실험을 진행하였다. 진동대 실험을 위한 적재설비의 바닥 구속조건을 총 4가 지(1 bolt, 2 bolts, 4 bolts, Fixed)로 구분하여 진행하였다. 실험은 인공지진파를 증가시켜가며 진행하였고, 각 층별에서의 변위응답과 영구변형을 비교하였다. 이에 따른 실험 결과, 지진 강도에 따라 기둥 바닥의 구속조건을 달리 적용하는 것이 필요하다.
        2018.04 서비스 종료(열람 제한)
        For quantitative assessment of flexural strength by crack condition of PSC sleeper, which is one of the main components of the ballasted track, 9 PSC sleepers used in Gyeongbu high speed railway line were sampled and static bending strength tests were conducted by EN 13230-2. The flexural strength of PSC sleepers with some mesh or longitudinal cracks was lower than that of new sleepers. In particular, the flexural strength of PSC sleepers with mesh-type cracks was less than 40% of the new sleepers’ flexural strength. The flexural strength of uncracked sleepers was similar to that of new sleepers
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