• Title/Summary/Keyword: 부식기간

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Estimation of Storm-centered Areal Reduction Factors by Durations and Return Periods Using Radar Rainfall (지속시간 및 재현기간에 따른 레이더 강우 호우중심형 ARF의 산정)

  • Kim, Eunji;Kang, Boosik
    • Proceedings of the Korea Water Resources Association Conference
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    • 2017.05a
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    • pp.163-163
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    • 2017
  • 설계홍수량은 수공구조물의 규모를 결정하는데 이용되며, 국내에서는 설계홍수량을 산정하기 위하여 지속시간과 재현기간에 따라 면적강우량을 추정한다. 지점강우량은 제한된 지역을 대표하는 값이므로 지점강우량을 기준면적에 대한 면적강우량으로 환산하기 위하여 면적우량환산계수(ARF, Areal Reduction Factor)를 적용한다. ARF를 산정하는 방법은 과거 관측자료를 활용하여 산정하는 경험적 방법(empirical method)이 주를 이루고 있으며, 경험적 방법은 크게 면적고정형(Fixedarea) 방법과 호우중심형(Storm-centered) 방법으로 분류된다. 면적고정형 방법은 국내 하천설계 기준에서 적용하고 있는 방법으로 면적강우 및 지점강우의 연 최대치를 독립적으로 빈도 해석하여 ARF를 산정하므로 실제 강우사상으로부터 산정된 값과 편차를 보인다. 반면 호우중심형 방법은 각각의 강우사상을 분석 대상 유역 중심에 공간 전이시켜 최대 강우량이 발생하도록 하는 방법으로, 레이더 강우를 활용하면 실제 강우사상의 공간분포 특성을 반영한 현실적인 ARF 산정이 가능하다. 본 연구에서는 국내 기상청에서 제공하는 홍수기(6-9월)의 10분 단위 단일편파 전국합성 레이더 자료를 활용하여 지속시간 1, 3, 6, 12, 24시간에 대한 호우중심형 ARF를 산정하였고, 면적강우 산정 시, 강우사상의 면적을 원형 또는 타원형으로 선정하여 강우의 형상 및 방향성을 고려하였다. 또한 레이더 강우의 중심강우를 지상강우 자료로 산정된 확률강우량 기준으로 분류하여 재현기간별 호우중심형 ARF를 산정하였으며, 이를 통해 기준면적, 지속시간, 재현기간에 따른 ARF의 특성을 분석하고자 하였다.

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강철도교의 부식 및 피로손상 사례조사

  • 채원규;홍성욱
    • Proceedings of the Korean Institute of Industrial Safety Conference
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    • 2003.05a
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    • pp.229-236
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    • 2003
  • 철도는 국가의 물류 및 인적자원을 수송하는 주요한 수송수단으로 1899년 9월 연장 33.2km의 경인선을 시작으로 선로가 지속적으로 증설되어 현재 총영업연장은 6,683km에 달하고 있다. 현재 국내에는 총 2,500여개소의 철도교가 있는데, 이 중에서 강교량에 대해서 연장이 차지하는 비율은 약 48%이고, 공용기간이 50년 이상인 강교량이 전체교량의 약 46%를 차지하고 있으므로 이들 강철도교는 노후화가 상당히 진행되고 있을 것으로 판단된다.(중략)

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손상된 파이프의 구조 안전성 평가

  • 박재학
    • Bulletin of the Korean Institute for Industrial Safety
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    • v.2 no.1
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    • pp.34-40
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    • 2002
  • 화학설비나 산업설비 또는 국가 기간 설비에서 파이프(pipe)는 중요한 위치를 차지하고 있으며 파이프의 파열은 그대로 대형 사고나 설비 가동의 중단으로 연결되는 경우가 많다. 따라서 파이프의 구조건전성을 유지하는 것은 안전의 확보와 생산 설비의 효율적 운용을 위하여 긴요하다. 파이프 재료 내부에는 재료 제작 시, 또는 파이프 제작 시 발생된 결함이나 사용 중 부식이나 피로 등의 영향으로 생성된 결함이 존재한다. 이러한 결함은 파이프의 강도를 낮추게 되고, 파이프의 잔류강도가 사용압력보다 낮아지게 되면 파이프가 파열하게 된다. 따라서 본 글에서는 파이프에 균열이 존재하거나 손상된 경우의 구조안전성 평가를 위하여 필요한 해석방법에 대하여 살펴본다.(중략)

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Basic concept and present condition of domestic market for dehumidifiers (제습의 기초 및 제습기의 국내 판매현황)

  • 문인호
    • The Magazine of the Society of Air-Conditioning and Refrigerating Engineers of Korea
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    • v.27 no.6
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    • pp.523-532
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    • 1998
  • 우리나라의 여름철 기후는 장마라는 일정기간의 우기와 더불어 고온 다습한 특성을 가지고 있다. 다습한 환경은 주거환경에서 곰팡이 균이 번식하는데 좋은 조건이 되며, 산업환경에서는 각종 기자재 및 원자재를 부식시키고, 일부 작업 공정을 어렵게 하는 문제점을 유발한다. 반면, 온도는 높지만, 습도가 낮은 중동 사막지역의 경우는 수 천년 동안 미이라가 훌륭하게 보존되어 왔다. 따라서 상대적으로 고습 기후 조건을 갖는 지역은 저습 기후 지역에 비하여 더 큰 습도제거 대책이 필요하게 되는 불리함이 있다.

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증기발생기 잠복 불순물 방출시험 데이타를 이용한 틈새 수질 상태 분석

  • 송택호;정일석;홍승열;나정원;이은희
    • Proceedings of the Korean Nuclear Society Conference
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    • 1996.11b
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    • pp.711-716
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    • 1996
  • 발전소 정상운전 및 정지기간 중 2차측 급수를 통하여 증기발생기 안으로 불순물이 유입되며, 운전중에 과열도가 높은 중기발생기 세관과 튜브쉬트등의 틈새에는 불순물의 농축도가 심해지며 이로인해 전열관이 부식손상을 입는다. 잠복불순물은 출력감발 및 정지기간 중에 증기발생기 급수의 냉각에 따라 불순물의 용해도차로 인해 재방출된다. 본 연구에선 89년부터 94년사이에 행하여진 원전 현장의 잠복불순물 방출시험자료를 이용하여 데이터베이스를 작성하였으며, 이중의 일부를 입력자료로 사용하여 Framona 전산코드작업을 수행한 결과 틈새의 pH 변화를 년도별로 비교할 수 있었다. 비교결과 년도가 지날 수록 증기발생기의 틈새에서의 pH는 낮아짐을 볼 수 있었으며 현장의 년도별 증기발생기 세관 관막 음수 증가 경향과 잘 일치하였다.

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Evaluation of Maturity Index for Garbage Composting Using the Sawdust as Bulking Agent (톱밥을 공극개량제로 사용한 음식쓰레기 퇴비화시 숙성도 지표의 적합성 평가)

  • Namkoong, Wan;Park, Sang-Hoo;In, Byung-Hoon;Park, Joon-Seok;Lee, Noh-Sup
    • Journal of the Korea Organic Resources Recycling Association
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    • v.8 no.3
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    • pp.73-80
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    • 2000
  • The objective of study was to evaluate the apropriate maturity indices for garbage composting using sawdust as bulking agent. Materials used in this study were the average composition garbage(G20) and garbage conditioned by sawdust(GS30, GS50) and cereals(GSC30). Indices for evaluating maturity were VS, water soluble TOC, polysaccharide, Humification Index(HI), and E4/E6. Experiment results showed that VS reduction was the most desirable index for evaluating compost maturity except for the GS50 which were conditioned with high sawdust Water soluble TOC decreased rapidly during the composting of first one month and then little changed. Therefore, water soluble TOC was recommended as maturity index. Polysaccharide was considered as a maturity index in case of garbage conditioned with sawdust and high cereals. Humification Index(HI) and E4/E6 were available as maturity indices in case of only some garbage composting so additional study was needed to confirm them as maturity indices for all garbage composting. Correlation analysis indicated that indices for evaluating maturity of garbage(about 30 C/N ratio) adding sawdust as bulking agent and high cereals, were VS reduction, water soluble TOC, polysaccharide, and E4/E6.

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An Application of Solenoid Eddy Current Sensor for Nondestructively Inspecting Deterioration of Overhead Transmission Lines due to Forest Fires (산불에 의한 가공송전선의 열화특성을 비파괴적으로 검출하기 위한 솔레노이드 와류센서의 응용)

  • Kim, Sung-Duck;Kim, Young-Dal;Jeong, Dong-Hwa
    • Journal of Sensor Science and Technology
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    • v.9 no.6
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    • pp.404-415
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    • 2000
  • This paper describes several performances and nondestructive inspection for deterioration due to forest fires in overhead transmission lines. After discussing corrosion mechanism such as atmospheric and galvanic corrosion for aged ACSR conductors and its detection for them are presented. Through impedance analysis of a solenoid coil, it is shown that the eddy current sensor may be available to inspect severe fault or local corrosion. As the solenoid coil changes its impedance when the test conductor is inserted into the coil, it can be possible to measure deterioration degree caused by forest fires. Tensile strength, extension rate and sensor impedance are tested for some samples degraded by artificial fire. As increasing blazed period to some extent, the strength of aluminum strand begins to be reduced remarkably, while galvanized steel strand holds the similar strength to the initial value, despite of appearing a little loss of zinc layer. In general, it is shown that the sensor impedance would be increased while the tension load of conductor is reduced and the extension rate is contrarily increased. Therefore, the sensor output could exhibit the changes of mechanical performances, and would be used to detect such deterioration caused by forest fire in ACSR conductors built on the ridge of mountains. Finally, it was verified that the solenoid coil could be applicable to obtain any crucial inform for serious deterioration due to forest fires.

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Optimization for Inspecdtion Planning of Ship Structures Considering Corrosion Effects (부식효과를 고려한 선체구조 검사계획안의 최적화)

  • Sung-Chan Kim;Jang-Ho Yoon;Yukio Fujimoto
    • Journal of the Society of Naval Architects of Korea
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    • v.36 no.4
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    • pp.137-146
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    • 1999
  • Inspection becomes to be important in the safety of structure and economical viewpoint, because structural damage accompanies lots of economical cost and social problems. Especially ship structure is composed of a lot of members and it is impossible to inspect all members continuously. The purpose of this paper is to get optimal inspection plan containing inspection time and method. Crack is one of major modes on the structural failure and can lead to collapse of structure. In this paper, the deteriorating process, which contains inspection to detect the crack before the propagation to large crack, is idealized as Markov chain model. Genetic algorithm is also used to accomplish the optimization of inspection plan. Especially, the probabilistic characteristics of cracks are changed, because ship is operating in corrosive environments and the scantling of structural members is reduced due to corrosion. Non-stationary Markov chain model is used to represent the process of corrosion in structural members. In this paper, the characteristics of indivisual inspection plan are compared by numerical examples for the change of corrosion rate, the cost due to scheduled system down and target failure probability. From the numerical example, it can be seen that the improvement of fatigue life for the members with short fatigue life is the most effective way in order to reduce total maintenance cost.

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Clinical Study of Corrosive Esophagitis (부식성 식도염에 관한 임상적 고찰)

  • 이원상;정승규;최홍식;김상기;김광문;홍원표
    • Proceedings of the KOR-BRONCHOESO Conference
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    • 1981.05a
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    • pp.6-7
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    • 1981
  • With the improvement of living standard and educational level of the people, there is an increasing awareness about the dangers of toxic substances and lethal drugs. In addition to the above, the governmental control of these substances has led to a progressive decrease in the accidents with corrosive substances. However there are still sporadic incidences of suicidal attempts with the substances due to the unbalance between the cultural development in society and individual emotion. The problem is explained by the fact that there is a variety of corrosive agents easily available to the people due to the considerable industrial development and industrialization. Salzen(1920), Bokey(1924) were pioneers on the subject of the corrosive esophagitis and esophageal stenosis by dilatation method. Since then there had been a continuing improvement on the subject with researches on various acid(Pitkin, 1935, Carmody, 1936) and alkali (Tree, 1942, Tucker, 1951) corrosive agents, and the use of steroid (Spain, 1950) and antibiotics. Recently, early esophagoscopic examination is emphasized on the purpose of determining the way of the treatment in corrosive esophagitis patients. In order to find the effective treatment of such patients in future, the authors selected 96 corrosive esophagitis patients who were admitted and treated at the ENT department of Severance hospital from 1971 to March, 1981 to attempt a clinical study. 1. Sex incidence……male: female=1 : 1.7, Age incidence……21-30 years age group; 38 cases (39.6%). 2. Suicidal attempt……80 cases(83.3%), Accidental ingestion……16 cases (16.7%). Among those who ingested the substance accidentally, children below ten years were most numerous with nine patients. 3. Incidence acetic acid……41 cases(41.8%), lye…20 cases (20.4%), HCI……17 cases (17.3%). There was a trend of rapid rise in the incidence of acidic corrosive agents especially acetic acid. 4. Lavage……57 cases (81.1%). 5. Nasogastric tube insertion……80 cases (83.3%), No insertion……16 cases(16.7%), late admittance……10 cases, failure…4 cases, other……2 cases. 6. Tracheostomy……17 cases(17.7%), respiratory problems(75.0%), mental problems (25.0%). 7. Early endoscopy……11 cases(11.5%), within 48 hours……6 cases (54.4%). Endoscopic results; moderate mucosal ulceration…8 cases (72.7%), mild mucosal erythema……2 cases (18.2%), severe mucosal ulceration……1 cases (9.1%) and among those who took early endoscopic examination; 6 patients were confirmed mild lesion and so they were discharged after endoscopy. Average period of admittance in the cases of nasogastric tube insertion was 4 weeks. 8. Nasogastric tube indwelling period……average 11.6 days, recently our treatment trend in the corrosive esophagitis patients with nasogastric tube indwelling is determined according to the finding of early endoscopy. 9. The No. of patients who didn't given and delayed administration of steroid……7 cases(48.9%): causes; kind of drug(acid, unknown)……12 cases, late admittance……11 cases, mild case…9 cases, contraindication……7 cases, other …8 cases. 10. Management of stricture; bougienage……7 cases, feeding gastrostomy……6 cases, other surgical management……4 cases. 11. Complication……27 cases(28.1%); cardio-pulmonary……10 cases, visceral rupture……8 cases, massive bleeding……6 cases, renal failure……4 cases, other…2 cases, expire and moribund discharge…8 cases. 12. No. of follow-up case……23 cases; esophageal stricture……13 cases and site of stricture; hypopharynx……1 case, mid third of esophagus…5 cases, upper third of esophagus…3 cases, lower third of esophagus……3 cases pylorus……1 case, diffuse esophageal stenosis……1 case.

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Significance of Early Esophagoscopy in Corrosive Esophagitis (부식성 식도염에서의 조기 식도경술의 의의)

  • 임병석;봉정표;박순일;문태용;윤강묵
    • Proceedings of the KOR-BRONCHOESO Conference
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    • 1983.05a
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    • pp.12.2-13
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    • 1983
  • Corrosive injuries of the esophagus by accident or suicidal attempt, though decreasing in number, still represent an important problem of our national pathology. One of the most difficult problems facing any physician is the diagnosis and management of caustic ingestion. In order to determine the extent of esophageal bums, to prevent the potential complication, to increase the therapeutic effect, the use of esophagoscopy is an essential step, and it has lessened an unnecessary admission and treatment. The authors have found the value of early esophagoscopy in selected 41 corrosive esophagitis patient who were admitted to Dept. of ENT, Wonju medical college, Yonsei university between 1980. 1-1982. 12

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