Determination of Ratio of Wood Deterioration Using NDT Technique

Jun Jae Lee,Mun Sung Bae 한국목재공학회 2004 목재공학 Vol.32 No.3

배수관 내시경 조사를 통한 간접적인 관 노후도 평가방법의 적정성 연구

최태호,강신재,최재호,구자용 대한상하수도학회 2012 상하수도학회지 Vol.26 No.5

The water supply pipes are buried across wide range of areas, so it is hard to spot them using excavation and takes a large amount of expense. Thus, there is a high risk for direct research and application, accompanying many difficulties in implementation of them. Therefore, it is more economical and convenient to use indirect evaluation variables than direct evaluation of the buried pipes in assessing the degree of pipe deterioration. To assess the degree of pipe deterioration using the indirect evaluation variables, it should be done first to identify how and to what extent they affect the degree of deterioration. This study measured the evaluation variables for pipe deterioration using the pipe endoscope and analyzed the measurement results and the degree of impact on the pipes. In addition, this study attempted to evaluate the adequateness of the pipe deterioration evaluation using the indirect variables based on the analysis results. The evaluation variables measured through the pipe endoscope were the thickness of sediments, size of scale, degree of desquamation and condition of connections. For the indirect evaluation variables, the data such as the property data from GIS pipe network map as well as the material, diameter, age and pipe lining material of the pipe, road type, leakage frequency, average water velocity and water pressure using the leakage repair records was collected. Using the collected data, this study comparatively analyzed the indirect evaluation variables for the degree of pipe deterioration and the results from the pipe endoscope to choose appropriate variables for pipe deterioration evaluation and calculated the weights of the indirect variables on the degree of deterioration. The results showed that the order of the impact of indirect variables on deterioration was pipe age > pipe lining material > road type > leakage frequency > average water velocity with their weights of 0.45, 0.20, 0.15, 0.10, and 0.10, respectively. Conclusively, the results suggest that the measures of sediment thickness, scale size, degree of desquamation and condition of connections are appropriate for the evaluation of pipe deterioration and sufficient for the analysis of the impact of the indirect variables on deterioration. The water supply pipes are buried across wide range of areas, so it is hard to spot them using excavation and takes a large amount of expense. Thus, there is a high risk for direct research and application, accompanying many difficulties in implementation of them. Therefore, it is more economical and convenient to use indirect evaluation variables than direct evaluation of the buried pipes in assessing the degree of pipe deterioration. To assess the degree of pipe deterioration using the indirect evaluation variables, it should be done first to identify how and to what extent they affect the degree of deterioration. This study measured the evaluation variables for pipe deterioration using the pipe endoscope and analyzed the measurement results and the degree of impact on the pipes. In addition, this study attempted to evaluate the adequateness of the pipe deterioration evaluation using the indirect variables based on the analysis results. The evaluation variables measured through the pipe endoscope were the thickness of sediments, size of scale, degree of desquamation and condition of connections. For the indirect evaluation variables, the data such as the property data from GIS pipe network map as well as the material, diameter, age and pipe lining material of the pipe, road type, leakage frequency, average water velocity and water pressure using the leakage repair records was collected. Using the collected data, this study comparatively analyzed the indirect evaluation variables for the degree of pipe deterioration and the results from the pipe endoscope to choose appropriate variables for pipe deterioration evaluation and calculated the weights of the indirect variables on the degree of deterioration. The results showed that the order of the impact of indirect variables on deterioration was pipe age > pipe lining material > road type > leakage frequency > average water velocity with their weights of 0.45, 0.20, 0.15, 0.10, and 0.10, respectively. Conclusively, the results suggest that the measures of sediment thickness, scale size, degree of desquamation and condition of connections are appropriate for the evaluation of pipe deterioration and sufficient for the analysis of the impact of the indirect variables on deterioration.

Original Article:Prevalence and Spatial Concordance of Visual Field Deterioration in Fellow Eyes of Glaucoma Patients

( Min Kyo Kim ),( Jun Mo Lee ),( Esteban Morales ),( Joseph Caprioli ) 대한안과학회 2014 Korean Journal of Ophthalmology Vol.28 No.6

Purpose: To examine the prevalence of visual field deterioration in contralateral eyes of patients with worsening open-angle glaucoma and to evaluate the spatial concordance of visual field deterioration between both eyes. Methods: One hundred sixteen open-angle glaucoma patients who underwent 8 or more visual field examinations over ≥6 years of follow-up were included. The rates of the fast and slow components of visual field decay for each of 52 visual field test locations were calculated with point-wise exponential regression analysis. The spatial concordance of visual field deterioration in contralateral eyes was evaluated with a concordance ratio (calculated as the number of overlapping locations divided by the total number of deteriorating locations) and by comparing the rate of decay in corresponding modified glaucoma hemifield test clusters. Results: The average visual field mean deviation (±standard deviation [SD]) was -8.5 (±6.4) dB and the mean (±SD) follow-up time was 9.0 (±1.6) years. Sixty-three patients had mild damage, 23 had moderate damage, and 30 had severe damage. The mean concordance ratio (±SD) was 0.46 (±0.32) for the mild group, 0.33 (±0.27) for the moderate group, and 0.35 (±0.21) for the severe group. Thirty-one patients (27%) had deterioration in concordant locations (p < 0.05). Visual field deterioration was greater in the superior hemifield than the inferior hemifield (p < 0.05) when evaluated with both the concordance ratio and modified glaucoma hemifield test cluster analysis methods. Conclusions: There is only fair spatial concordance with regard to visual field deterioration between the both eyes of an individual. We conclude that testing algorithms taking advantage of inter-eye spatial concordance would not be particularly advantageous in the early detection of glaucomatous deterioration.

Characterization of culturable yeast species associating with whole crop corn and total mixed ration silage

Huili Wang,Wei Hao,Tingting Ning,Mingli Zheng,C.C. Xu 아세아·태평양축산학회 2018 Animal Bioscience Vol.31 No.2

Objective: This study investigated the association of yeast species with improved aerobic stability of total mixed ration (TMR) silages with prolonged ensiling, and clarified the characteristics of yeast species and their role during aerobic deterioration. Methods: Whole crop corn (WCC) silages and TMR silages formulated with WCC were ensiled for 7, 14, 28, and 56 d and used for an aerobic stability test. Predominant yeast species were isolated from different periods and identified by sequencing analyses of the 26S rRNA gene D1/D2 domain. Characteristics (assimilation and tolerance) of the yeast species and their role during aerobic deterioration were investigated. Results: In addition to species of Candida glabrata and Pichia kudriavzevii (P. kudriavzevii) previously isolated in WCC and TMR, Pichia manshurica (P. manshurica), Candida ethanolica (C. ethanolica), and Zygosaccharomyces bailii (Z. bailii) isolated at great frequency during deterioration, were capable of assimilating lactic or acetic acid and tolerant to acetic acid and might function more in deteriorating TMR silages at early fermentation (7 d and 14 d). With ensiling prolonged to 28 d, silages became more (p<0.01) stable when exposed to air, coinciding with the inhibition of yeast to below the detection limit. Species of P. manshurica that were predominant in deteriorating WCC silages were not detectable in TMR silages. In addition, the predominant yeast species of Z. bailii in deteriorating TMR silages at later fermentation (28 d and 56 d) were not observed in both WCC and WCC silages. Conclusion: The inhibition of yeasts, particularly P. kudriavzevii, probably account for the improved aerobic stability of TMR silages at later fermentation. Fewer species seemed to be involved in aerobic deterioration of silages at later fermentation and Z. bailii was most likely to initiate the aerobic deterioration of TMR silages at later fermentation. The use of WCC in TMR might not influence the predominant yeast species during aerobic deterioration of TMR silages.

뇌미세혈관병증 3가지 표식과 열공뇌경색 초기 신경학적 악화와의 관련성

문장섭,김나영,강지훈,양미화,장명숙,한문구,배희준 대한신경과학회 2012 대한신경과학회지 Vol.30 No.4

Background: Neurological deterioration following acute lacunar infarction is not uncommon. Its association with poor clinical outcome is well-known, but little is known about what causes it. This study aimed to elucidate whether 3 stigmas of cerebral microangiopathy, a pathogenesis of lacunar infarction, are associated with neurological deterioration in patients with acute lacunar infarction. Methods: Patients with acute lacunar infarction who were admitted within 24 hours of onset were identified using a prospective stroke registry. Patients who presented neurological deterioration within 7 days of hospitalization (progressive lacune group) were matched to 4 controls (non-progressive lacune group) for ‘onset to arrival time’. Three stigmas of cerebral microangiopathy (leukoaraiosis, cerebral microbleeds, and silent lacunes) were measured using initial brain MRI, and their associations with neurological deterioration were analyzed. Results: During 45 months, a total of 23 patients were identified and matched to 80 controls. Simple comparison of 2groups showed that those 3 stigmas of cerebral microangiopathy were not significantly associated with neurological deterioration. Hyperlipidemia (p=0.18), history of transient ischemic attack or stroke (p=0.01), initial NIH stroke scale (p=0.07), white blood cell counts (p=0.16), and lesion volume (p=0.03) were possibly different (p’s<0.2) between 2 groups. Multivariable logistic regression analysis did not reveal any significant association of those 3 stigmas with neurological deterioration, too (all p values>0.5). Conclusions: This study did not find a relationship between cerebral microangiopathy and neurological deterioration following acute lacunar infarction. The possibility of inadequate power should be noted.

조절내사시에서 대상부전의 발생빈도 및 위험요소

김관수,최철영,장혜란,Kwan Soo Kim,M,D,Chul Young Choi,M,D,Hae Ran Chang,M,D 대한안과학회 2008 대한안과학회지 Vol.49 No.12

Purpose: A number of patients with accommodative esotropia who were initially well controlled with their optical correction will deteriorate. This study aims to examine the cautious clinical features of patients with accommodative esotropia during follow-up period by obtaining the prevalence and the predictive factors of deterioration in accommodative esotropia. Methods: The records of 89 patients with accommodative esotropia whose eyes were aligned with optical correction (including bifocals) to 8 prism diopters (PD) of esotropia or less were reviewed. All patients were followed for a period of at least 2 years. The patients whose alignment was increased to 10PD of esotropia or greater during the follow-up period were included into the deteriorated group. We obtained the rate of deterioration and compared the clinical features of the deteriorated and controlled group. Results: The mean follow-up period was 64.1±29.3 months. Seven (7.8%) of 89 patients was deteriorated. The mean interval of deterioration after initial optical correction was 41.8±26.9 months. The stereopsis was significantly worse in the deteriorated group p=0.024). The frequency of high AC/A ratio was also significantly higher in the deteriorated group (p=0.003). Conclusions: This study indicates that accommodative esotropia with high AC/A ratio or worse sensory status has an increased likelihood of deterioration.

교량 콘크리트 바닥판 열화 매커니즘과 유형에 따른 보수방안

정유석(Yoseok Jeong),이일근(Ilkeun Lee),민근형(Geunhyeong Min),김우석(WooSeok Kim) 한국콘크리트학회 2024 콘크리트학회논문집 Vol.36 No.4

최근 교량 바닥판 유지관리 실패로 인해 관련 사고가 빈번하게 발생하고 있어 체계적인 바닥판 유지관리 전략 수립이 필요한 시점이다. 이를 위해 본 연구에서는 바닥판 열화메커니즘 규명 및 바닥판 열화유형을 제안하고 그에 따른 보수보강 방안 및 선정방법을 제시하고자 한다. 콘크리트 바닥판의 열화 메커니즘은 상면에서 초기 결함, 미세균열, 중차량 피로로 인해 열화가 시작되고, 이 부위에 수분 및 염화물 침투, 동결융해, 중차량 피로에 의해 손상 면적과 깊이가 확대된다. 콘크리트 바닥판 보수공사는 열화깊이에 따라 교면재포장(TYPE A), 바닥판 부분단면복구공사(TYPE B), 바닥판 전단면복구공사(TYPE C)로 구분할 수 있다. 적정보수공법을 선정하기 위해 육안조사 및 상세조사를 통해 바닥판의 열화 정도(면적과 깊이)를 고려하여 바닥판보수공사(TYPE A, B, C) 선정절차를 제안하였다. It is imperative to propose effective maintenance strategies for deteriorated bridge concrete deck, given the increasing cases of maintenance failures. This study aims to elucidate the deterioration mechanism and patterns of bridge concrete deck degradation. Additionally, it presents various repair methods and flowcharts for determining the most suitable repair method for each type of deterioration. The deterioration mechanisms include initial defects, cracks, heavy vehicle loads, and the infiltration of water and deicing chemicals through cracks. These factors lead to the expansion and deepening of deterioration, exacerbated by freeze-thaw cycles and heavy vehicles. Repair methods are categorized into concrete overlay repair (Type A), partial-depth deck repair (Type B), and full-depth deck repair (Type C). The study also proposes flowcharts for determining the appropriate repair method based on results obtained from visual and in-depth inspections of deteriorated concrete decks. By following this structured approach, the maintenance and rehabilitation of bridge decks can be conducted more efficiently, reducing long-term costs and enhancing the resilience of bridge infrastructure.

미취학 아동의 시력검진 실태와 시력저하 관련요인

이성화(Sunghwa Lee),이해정(Haejung Lee) 한국콘텐츠학회 2016 한국콘텐츠학회논문지 Vol.16 No.12

미취학아동의 시력검진실태와 시력저하 관련요인을 확인하기 위해 2015년 8월부터 2016년 1월까지 어린이집 및 유치원에 다니는 5세∼7세의 아동 172명과 그 부모 중 1인 172명을 대상으로, 보호자에게는 설문조사를, 아동에게는 시력측정을 실시하였다. 시력검진 실태는 평균, 표준편차, 백분율 등 서술적 방법으로 분석하였고, 시력저하 관련요인은 로지스틱 회귀분석으로 확인하였다. 전체 아동 172명 중 128명(74.4%)이 시력검진 경험이 있었으며, 77명(44.8%)이 시력저하로 나타났다. 7세 이후에 시력검진을 처음 수행한 경우(OR=7.43, CI=2.84-19.39), 눈 이상 증상이 있는 경우(OR=3.08, CI=1.20-7.91), 아동연령이 어릴수록(OR=10.34, CI=3.25-32.85) 시력저하 경향이 높았고, 단말기를 주로 아래에서 위로 올려다보는 아동인 경우(OR=.08, CI=.02-.26), 시력저하 경향이 낮았다. 미취학아동의 시력저하에는 유전적인 요소도 중요하지만, 눈 이상 증상, 눈검사 시기, 단말기 사용방법, 아동의 연령과 관련성이 있었다. 그러므로 아동양육기관과 보호자, 검진기관을 대상으로 아동의 눈 이상증상과 단말기 사용방법, 눈검사 시기에 대한 교육이 필요하며, 아동을 대상으로 한 시력저하예방을 위한 중재프로그램의 개발과 효과검증이 필요하다. The study aimed to examine the state of visual acuity tests in preschoolers and determine the factors affecting the deterioration of their vision. A total of 172 pair, child aged 5-7 years and either one of their parents, were recruited from childcare centers or kindergarten between August 2015 and January 2016. Questionnaires were administered to the parents, and the children’s visual acuities were measured. Using forward selection in logistics regression analysis, factors affecting vision deterioration were elucidated. Of 172 children, 128 (74.4%) had undergone a visual acuity test previously and 77 (44.8%) showed a deterioration in their vision. Children who had undergone their first visual acuity test after the age of 7 years (OR=7.425, CI=2.844- 19.385) and showed more abnormal eye symptoms, such as squinting or tilting the head to see or falling down frequently (OR=3.084, CI=1.202-7.914) and whose age was younger (OR=10.335, CI=3.252-32.848), were more likely to develop deterioration of vision. Children who had a posture such that they looked up at the computer monitor from below (OR=.075, CI=.022-.255), were less likely to show deterioration of vision. It can be inferred that early visual acuity tests is essential to detect deteriorated vision of preschoolers. Therefore, it is necessary to educate parents, personnels in day care center, and health clinics about the importance of early visual acuity tests and close observation of specific behaviors related to vision deterioration. Development of precautionary intervention program of vision deterioration in preschoolers and examination of its effects are needed.

접지시스템에 사용되는 접속요소의 열화특성 분석

길형준 ( Hyoung Jun Gil ),송길목 ( Kil Mok Shong ),김영석 ( Young Seok Kim ),김종민 ( Chong Min Kim ) 한국안전학회(구 한국산업안전학회) 2015 한국안전학회지 Vol.30 No.2

This paper describes the analysis of deterioration characteristics for connection factor used in grounding system. The connection method of grounding system is specified in IEC standard. In order to analyze the deterioration characteristics for connection factor, deterioration test was carried out when the connection factor was buried in salt water and underground. The test connection factors were C-type sleeve, clamp, and exothermic welding. As a consequence, most of the connection factor was corroded, and the electrical resistance decreased after deterioration. The analytical results can be used to establish the safety of grounding system.

터널 열화로 인한 콘크리트 라이닝의 거동에 관한 연구

한영철,정상섬 한국지반공학회 2014 한국지반공학회논문집 Vol.30 No.4

This paper studies the time-dependent behaviors of tunnel and surrounding ground due to tunnel deterioration. In thefirst part, the literature on deterioration characteristics of tunnels was reviewed. In the second part, a numerical analysiswas performed to investigate the behavior of concrete lining on the typical section of Korean high-speed rail tunnel(weathered rock) after determination of input variables related to deterioration impact. The result shows that the settlementat the crown of tunnel and surface ground increased up to 7.0% and 30.2% of the total settlements during constructionstage, respectively, and the internal convergence reduction of 9.0 mm for concrete linings was generated within 30 yearsafter completion of tunnel construction. Also the loosening height increased up to 2.55 times of tunnel height within50 years, which is higher than that of Terzaghi’s recommendation on ultimate state. Due to this process of extendingzones, it is found that additional loads were applied to concrete lining with the axial stress about 3.20~3.66 MPa,which accelerates tunnel deterioration. Finally the quantitative design approach to evaluate time-dependent behavior oflining and surrounding ground due to tunnel deterioration was proposed.