• 제목/요약/키워드: Root finding

검색결과 180건 처리시간 0.028초

A Study on the Performance of Causal Links between Error Causes: Application to Railroad Accident Cases

  • Kim, Dong San;Yoon, Wan Chul
    • 대한인간공학회지
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    • 제32권6호
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    • pp.535-540
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    • 2013
  • Objective: The aim of this study is to evaluate the effectiveness and efficiency of causal links between various error causes in human error analysis. Background: As finding root causes of human error in safety-critical systems is often a cognitively demanding and time-consuming task, it is particularly necessary to develop a method for improving both the quality and efficiency of the task. Although a few methods such as CREAM have suggested causal linking between error causes as a means to enhance the quality and efficiency of human error analysis, no published research to date has evaluated the performance of the causal links. Method: The performance of the CREAM links between error causes were evaluated with 80 railway accident investigation reports from the UK. From each report, errorneous actions of operators were derived, and for each error, candidate causes were found by following the predefined links. Two measures, coverage and selectivity, were used to evaluate the effectiveness and efficiency of the links, respectively. Results: On average, 96% of error causes actually included in the accident reports were found by following the causal links, and among the total of 121 possible error causes, the number of error causes to be examined further was reduced to one-tenth on average. As an additional result of this work, frequent error causes and frequently used links are provided. Conclusion: This result implies that the predefined causal links between error causes can significantly reduce the time and effort required to find the multiple levels of error causes and their causal relations without losing the quality of the results. Application: The CREAM links can be applied to human error analysis in any industry with minor modifications.

다성분 탄화수소혼합물 포화물성해석 수렴도 향상 연구 (Study on the Convergency Improvement Method for the Saturation-Property Calculation of Multi-Component Hydrocarbon Systems)

  • 신창훈;안승희;이정환;성원모
    • 대한기계학회논문집B
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    • 제34권10호
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    • pp.947-955
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    • 2010
  • 대부분의 석유 가스전은 탄화수소혼합물과 일반기체 등 저류층 내부 유체의 성분조성에 따라 저류층내 상거동 특성이 매우 민감하게 변화한다. 석유 가스전의 평가와 개발 생산계획을 수립함에 있어, 이러한 상거동에 따른 기체와 액체의 성분비 결정과 석유와 가스의 이상유동 해석을 위한 저류유체의 PVT관계 및 포화물성의 규명은 필수적이다. 이중에서 특히, 포화물성의 계산은 수렴성이 나빠, 이상 유동의 해석적 연구에 있어서 많은 어려움을 초래하는 원인이 되고 있다. 이에 본 연구에서는 포화물성 의 계산에 있어서 수렴도 향상을 위한 새로운 초기값 추정 방법과 근 탐색 알고리듬을 제안하고, 성능비교 등을 통한 수렴도 영향인자에 대한 분석을 시도하였다. 결과적으로, 제안된 방법을 통해 포화물성 해석 수렴성을 개선하였고 GUI 기반의 새로운 다성분 다상거동해석 시뮬레이터의 개발에 적용하였다.

Glanzmann씨 혈소판무력증(Glanzmann's Thrombasthenia) 환자의 치주 치료 증례 (Periodontal treatment of a Glanzmann's thrombasthenia patient : A case report)

  • 이학철;한수부;김우성;이혜자
    • Journal of Periodontal and Implant Science
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    • 제27권3호
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    • pp.597-602
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    • 1997
  • Glanzmann's thrombasthenia is a Qualitative platelet disorder characterized by a deficiency in the platelet membrane glycoproteins IIb/IIIa. It belongs to a group of hereditary platelet disorders typified by normal platelet numbers and a prolonged bleeding time. The severity of bleeding does not correlate with the severity of the platelet glycoprotein IIb/IIIa a abnormality. The present case report describes the periodontal treatment of a patient with Glanzmann's thrombasthenia. A 30-year-old female with a history of Glanzmann's thrombasthenia was referred for gingival bleeding on tooth brushing and discomforts in #38 area. The periodontal finding revealed a diagnosis of localized slight adult periodontitis. Root planing and extraction of #38 was performed under 12 pack of platelets transfusion and digital compression was done for hemostasis. The gingival bleeding ceased within a day in maxilla and 2 days later in mandible. 42 pack of platelets was administered for 3 days of post-treatment and for iron-deficiency anemia 3 pack of RBCs was transfused 2 days later. 1 week later the inflammation in gingiva disappeared and gingival stippling appeared. The clinical result we got was good and in such a medically compromised patient it is an ability to maintain a proper oral hygiene that is essential both for oral and systemic health.

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腋격의 病因.病機.治療에 對한 文獻的 考察 (A literature study on Bromidrosis)

  • 김종성;김경준
    • 한방안이비인후피부과학회지
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    • 제13권1호
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    • pp.157-184
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    • 2000
  • Bromidrosis is a disease which is also called huchou[호격] in the oriental medicine. This disease produces an odor and a small amount of sweat from the axillary area. Prognosis of the disease could possibly get better with age. This can be explained by the fact that its symptoms begin usually when a person reaches puberty and as the person gets old, the symptoms reduce or disappear even when specific treatments are not applied. Although the disease is not lethal, many patients have difficulties in leading a normal and comfortable life, physically and psychologically with this in mind and some osbservations gained from the literature studies on the causes,symptoms, and treatments, I embarked on a study aimed at finding out the therapies. My study on the literature has produced the following results ; 1. In the oriental medicine, hu-chou[호격] means the characteric smell or odor produced from the fox. 2. The literature studies point out two causes in the oriental medicine. One is natural. The other is acquired. Acquired cases have the following causes: shi-re-nei-yun[濕熱內蘊]. xie-뱌-bu-huo[血氣不和], gan-qi-yu-jie[肝氣鬱結]. 3 There are two therapies in the oriental medicine. One is internal and the other external. out of the two, external therapies were mainly used according to the literature studies that I have consulted. 4. According to my study, the most frequently used herbal medicine was Alunitum(明 礬)(45 times), followed by Minium(密陀僧)(39 times) and Moschus(?香)(21 times respectively). 5. My study also found that bian-zheng[辨證] was not .rarely listed on old literatures. Therefore, old literatures did not clearly show how to root out the disease. They only taught now to alleviate the symptoms and remove the characteric odor.

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한약재 보관중 발생하는 해충류 (Insect Pests Occurring in Storage Medicinal Plants)

  • 조형찬
    • 한국약용작물학회지
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    • 제15권6호
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    • pp.417-428
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    • 2007
  • 국내 유통 중인 한약재 대부분을 수입에 의존하고 있으나, 관리시설이 빈약하여 해충들에게 쉽게 노출될 수 있는 환경에 놓여 있다. 이 연구는 총 67과 134속 158종의 저장 한약재들을 대상으로 이들에서 발생하고 있는 저장물해충들을 조사하였다. 그 결과, Cassia 속의 육계, Juniperus 속의 자단향 그리고 Artemisia 속 애엽을 비롯한 44종의 한약재들에서는 곤충의 발생을 확인할 수 없었다. 한약재들에서 나타난 해충들의 발생빈도는 쌀머리대장 (A. advena) 12.3%, 권연벌레 (L. serricorne) 11.5%, 머리대장가는납작벌레 (O. surinamensis) 10.3%, 거짓쌀도둑거저리 (T. castaneum) 9.4%, 인삼벌레 (S. paniceum) 8.4% 그리고 화랑곡나방 (P. interpunctella) 7.9% 순이었다. 또한 이들 곤충들은 저장 중인 한약재들 중에서도 뿌리 또는 뿌리줄기 형태의 한약재들을 가장 선호한 것으로 보였다. 이 연구는 천연물 연구자들에게 곤충들이 발생하지 않았던 한약재들에 대한 기본 정보를 제공해줌으로써 향후 이들이 살충활성 또는 훈증활성물질을 탐색하는데 있어 이들 한약재들을 우선적으로 검토할 수 있는 유용한 자료로서 활용될 수 있을 것이다.

부식결함을 가진 배관의 파손확률 예측을 위한 단순화된 방법 (A Simplified Method for Predicting Failure Probability of Pipelines with Corrosion Defects)

  • 이진한;김영섭;김래현
    • 한국가스학회지
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    • 제14권4호
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    • pp.31-36
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    • 2010
  • 본 논문은 부식 배관의 파손 가능성에 대해 확률론적 분석방법을 설명하고, 이를 단순화하여 계산할 수 있는 방법을 제안하였다. 부식 배관의 파손은 운전압력이 부식 배관의 잔존강도를 초과할 때 발생하는데 이를 한계상태 함수로 설정하여 분석하면 부식이 진행됨에 따른 누출확률에 대한 불확실성을 예측할 수 있다. 이 한계상태 함수는 해석해가 존재하지 않으므로 전통적으로 불확실성을 예측하기 위해 Monete-Carlo Simulation (MCS)을 사용한다. 본 연구에서는 한계상태 함수의 해가 하나만 존재한다는 점에 착안하여 그 해를 수치적으로 찾는 방법을 제안하였다. 이 방법은 MCS를 이용한 결과와 비교할 때 오차가 적으면서도 매우 빠르게 계산할 수 있어 효율적인 방법이라 판단된다.

Anti-hyperlipidemic Effect of Insamsansa-eum in Mice

  • Jung, Sang-Hyun;Ko, Chang-Nam;Bae, Hyung-Sup;Kim, Young-Suk;Cho, Ki-Ho;Min, Sung-Won;Kim, Dong-Hyun
    • Natural Product Sciences
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    • 제14권4호
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    • pp.215-220
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    • 2008
  • Hypolipidemic effect of Insamsansa-eum (ISE, Ren-Shen-Shan-Zah-Yin in Chinese) consisted of Red ginseng (RG; the steamed root of Panax ginseng C.A. Meyer) and Crataegii fructus (CF, the fruit of Crataegus pinnatifida BGE) is used frequently in China and Korea as a herbal medicine to treat arteriosclerosis, was investigated. Treatment of ISE significantly reduced blood triglyceride (TG) and total cholesterol (TC) levels in Triton WR-1339-induced hyperlipidemic mice and serum TG levels in corn oil-induced hypertriglyceridemic mice. ISE significantly lowered the high blood TG and TC levels as well as body and epididymal mass weights in hyperlipidemic mice induced by long-term feeding of a high-fat diet and increased blood HDL cholesterol level. ISE and its ingredients, RG and CF, inhibited pancreatic lipase and HMG-CoA reductase activities. Of its ingredients, RG reduced the blood TC level and HMG-CoA reductase activity more than CF. CF reduced blood TG level and pancreatic lipase activity more than RG. These finding suggest that the antihyperlipidemic effect of ISE may be due to synergistic inhibition of HMG-CoA reductase and pancreatic lipase by RG and CF, and that ISE may be effective hypolipidemic agents.

해운 운임 간 인과관계에 관한 연구 (A Study on the Causal Relationship Between Shipping Freight Rates)

  • 전준우
    • 융합정보논문지
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    • 제9권12호
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    • pp.47-53
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    • 2019
  • 본 연구의 목적은 VECM 모형(Vector Error Correction Model)을 활용해 해운 운임 간 인과관계를 분석하는 것이다. 분석에 사용된 해운 운임은 BDI(Baltic Dry Index), HRCI(Howe Robinson Containership Index), WS(World Scale rate), SCFI(Shanghai Containerized Freight Index)다. 분석 기간은 2013년 8월 2일부터 2019년 9월 6일까지이며 주간 데이터를 활용했다. VECM 모형 분석 결과, BDI는 일주일 전의 BDI에 많은 영향을 받는 것으로 분석되었으며, WS의 1% 상승은 일주일 후의 HRCI를 0.022% 상승시키는 것으로 분석되었다. HRCI 1% 상승은 일주일 후의 SCFI를 0.77% 상승시키며, WS는 일주일 전의 WS에 많은 영향을 받는 것으로 나타났다. 본 연구의 분석 결과는 각 해운시장의 해운 운임 예측에 도움을 주며, 이를 활용하여 의사결정자들이 올바른 의사결정을 할 수 있게 도움을 줄 수 있다고 사료된다.

Toxicological Evaluation of Saposhnikoviae Radix Water Extract and its Antihyperuricemic Potential

  • Kim, Chang Won;Sung, Jae Hyuck;Kwon, Jeong Eun;Ryu, Hyeon Yeol;Song, Kyung Seuk;Lee, Jin Kyu;Lee, Sung Ryul;Kang, Se Chan
    • Toxicological Research
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    • 제35권4호
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    • pp.371-387
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    • 2019
  • Although the dried root of Saposhnikovia divaricata (Turcz.) Schischk. (Umbelliferae) is a popular medicinal plant in East Asia, there has been no systemic toxicological evaluation of a water extract of Saposhnikoviae Radix (SRE). In this experiment, an oral acute and 13-week subchronic toxicological evaluations of SRE (500-5,000 mg/kg body weight) were performed in both sexes of Crl:CD(SD) rats. Based on the results from mortality, clinical signs, effects on body weight and organ weight, clinical biochemistry, hematology, urinalysis, and histopathology, significant acute, 4-week repeated dose range finding (DRF) and 13-week subchronic toxicity of SRE was not observed in either sex of rats; thus, the no observed adverse effect level (NOAEL) was 5,000 mg (kg/day). To identify anti-hyperuricemia potential of SRE, the suppressive effect of SRE was determined in mice challenged with potassium oxonate (PO; 250 mg/kg) via intraperitoneal injection for 8 days (each group; n = 7). SRE supplementation suppressed the uric acid level in urine through significant xanthine oxidase (XO) inhibitory activity. Kidney dysfunctions were observed in PO-challenged mice as evidenced by an increase in serum creatinine level. Whereas, SRE supplementation suppressed it in a dose-dependent manner. Collectively, SRE was safe up to 5,000 mg (kg/day) based on NOAEL found from acute and 13-week subchronic toxicological evaluations. SRE had anti-hyperuricemia effect and lowered the excessive level of uric acid, a potential factor for gout and kidney failure.

국제해사기구 회원국감사(IMSAS) 주요 결과분석 및 종합 전략방안 연구 (A Study on the Major Results of the IMO Member State Audit Scheme (IMSAS) and the Comprehensive Strategic Plan)

  • 박혜리;박한선
    • 한국항해항만학회:학술대회논문집
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    • 한국항해항만학회 2019년도 춘계학술대회
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    • pp.242-243
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    • 2019
  • IMO는 2005년 자발적 회원국 감사제도(VIMSAS)를 도입하여 총 67개 회원국에 대한 감사를 시행하였으며, 2016년 강제화(IMSAS) 하였다. 현재 174개 회원국을 대상으로 매년 25개국씩 협약이행 의무에 대한 감사를 7년 주기로 시행하고 있으며, 우리나라는 2020년 7월 수감 받을 예정이다. 이에 2020년 우리나라 감사에 대비하여 회원국 감사 지적사항을 최소화하고, IMO 협약 이행 및 시행에 대한 모범사례를 제시하기 위해 철저한 사전대비 필요한 시점이다. 본 논문에서는 2016년 강제화 된 IMSAS 감사결과를 대상으로 주요 발견사항 및 관찰사항을 분석하고, 타 회원국 감사 분석결과를 기반으로 국내 감사 종합전략을 제시하였다.

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