• 한국화재소방학회논문지
• /
• 제21권4호
• /
• pp.59-64
• /
• 2007

본 논문은 전동기에 발생하는 화재에 대한 연구로서, 일반가전제품에 사용되고 있는 단상유도전동기에 과부하 및 외부화염을 가하여 그 변형 및 파손상태를 비교 분석하였다. 실험은 전동기의 구속을 통한 과부하 시험과 외부에서 화염을 가하는 실험으로 진행하였으며, 외부화염 시험의 경우 전압을 인가한 경우와 인가하지 않은 경우로 구분하였다. 실험결과 구속을 통한 과부하 시험의 경우 권선부분에서 층간 단락흔을 관찰할 수 있었고, 권선부분의 조직에서는 과부하에 의해 변형된 전선의 특징인 나무줄기 형상의 수지상 조직이 나타났다. 전압을 인가한 상태에서 외부화염을 가한 경우 고정자 권선부분의 코일이 원형을 유지하고 있는 것을 확인할 수 있었고, 권선주변의 색이 붉게 변색된 것을 볼 수 있었다. 전압을 인가하지 않고 외부화염을 가한 경우 고정자 권선부분의 코일이 원형에서 많이 변형된 것을 관찰할 수 있었고, 권선 주변의 색은 전압을 인가한 경우와 마찬가지로 붉게 변색된 것을 확인할 수 있었다.

• 대한조선학회논문집
• /
• 제58권3호
• /
• pp.158-166
• /
• 2021

In this paper, a numerical analysis technique using a body force model is investigated to estimate the available net thrust of multi-pod-driven ice-breaking vessels under bollard pull and overload conditions. To employ the body force model in present flow simulations, drag and thrust components acting on the pod unit are calculated by using Propeller Open Water (POW) test data. The available net thrusts according to the direction of operation are evaluated in both bollard pull and overload conditions under deep water. The simulation results are compared with the model test data. The available net thrusts, calculated by the present analysis for ahead operating modes at 3~6 knots which are typical speeds of the target vessel in arctic field, are agreed well with the model test results. It is also found that the present result for astern operating mode appears approximately 6 % larger than the model test result. In addition, the available net thrusts are calculated under the both operating conditions accompanied by shallow water effects, and the main cause of the difference is studied. Based on the result of the present study, it is confirmed that the body force model can be applied to the performance evaluation of multi-pod propulsion system and the main engine selection in early design stage of the vessel.

• 한국군사과학기술학회지
• /
• 제9권4호
• /
• pp.15-23
• /
• 2006

In this paper, full-scale airframe static test of 4-seater canard airplane(the Firefly) was explained. From the results of the structural analysis, 5 design limit loads test conditions and 11 design ultimate loads test conditions were selected. Test loads analysis was performed and test fixtures and load control system(LCS) were prepared to realize the test loads. To protect the test article during the test, the overload protection system was prepared. Strain and deflection values were acquired through the data acquisition system(DAS) to verify the structural analysis results.

• 대한임상검사과학회지
• /
• 제49권4호
• /
• pp.495-497
• /
• 2017

Thalassemia major is a genetic disorder with a defective synthesis of either the alpha or the beta chain of hemoglobin A. Blood transfusion is crucial for the survival in these patients. Unfortunately, endocrine dysfunction is a very common complication in these patients and is principally due to excessive iron overload as a result of frequent blood transfusions. Although regular blood transfusion may increase life expectancy, disturbances in growth and pubertal development, abnormal gonadal functions, impaired thyroid, parathyroid and adrenal functions, diabetes, and disorderly bone growth are common side effects. We hereby present a case of a 23-year-old, unmarried woman with beta thalassemia major presenting with primary amenorrhea, poor development of secondary sexual character, and short stature. Thorough history, clinical examination, and laboratory investigation, including dynamic function test (insulin tolerance test) were conducted. These tests confirmed that she had multiple endocrinopathies, including hypogonadotropic hypogonadism, growth hormone deficiency, and subclinical adrenal insufficiency, which were caused by iron overload. She required hormone replacement therapy. Early recognition of possible deficiencies in hypothalamo-pituitary-end organ hormones caused by iron overload in thalassemia patients that undergo frequent blood transfusion procedures is essential. Appropriate treatments, including transfusion regimen and chelation therapy, as well as specific treatment of each complication are the crucial for the successful management and improvement of quality of life these patients.

• 대한기계학회:학술대회논문집
• /
• 대한기계학회 2004년도 추계학술대회
• /
• pp.359-364
• /
• 2004

In this study, experiments were tried on the mixed-mode I+II single overloading model which changes the loading mode of overload and fatigue load. Aspects of deformation field in front of the crack which is formed by mixed-mode I+II single overloading were experimentally studied. Then the shape and size of mixed-mode plastic zone were approximately calculated. The propagation behavior of fatigue crack was examined under the test conditions combined by changing the loading mode. The behavior of fatigue cracks were greatly affected by shapes of plastic deformation field and applying mode of fatigue load. Accuracy of prediction and evaluation for fatigue life may be improved by considering all aspects of deformation and behavior of fatigue cracks.

• 한국전산구조공학회논문집
• /
• 제24권4호
• /
• pp.399-404
• /
• 2011

과적차량은 도로관련 사회간접자본과 국가 경제적 측면, 교통류, 도로안전 등 다양한 측면에서 악영향을 미치고 있다. 이에 따라, 본 논문에서는 지능형 과적차량 단속시스템 개발을 위하여 유비쿼터스 센서네트워크(USN) 시스템을 구성하였다. 그리고 WIM(Weight-in-motion) 시스템과 달리 도로자체의 변형을 측정하여 주행중인 차량의 축을 감지한 후, 도로 하면에 부착된 변형률센서를 통하여 얻은 신호와 해석방법을 이용하여 차량의 중량을 계산하는 방안을 제시하였다. 또한 유전자알고리즘 기법의 차량하중 분석방법을 위한 시뮬레이션 실험을 실시하였고, USN구성을 위한 센서의 무선화 테스트를 실시하였다.

• 한국기계가공학회지
• /
• 제16권2호
• /
• pp.1-6
• /
• 2017

In this paper, we present a study concerning the design of a 400 N class side thruster for small ships. The side thrusters used in Korea are imported from abroad. The performance and durability of the imported products employed in Korea are not adequate, therefore the side thrusters which will be suitable for Korean domestic needs to be re-designed. The strength calculation of the side thruster was performed by KS standard. Strength calculation and design were made to meet design requirements. Structural analysis and safety factor analysis were carried out to confirm the validity of strength calculations and design. After manufacturing the bevel gear, a back lash test was conducted. We also conducted a no-load test, a rated load, and an overload test for a performance test and a durability test of the design while satisfying the design conditions.

• 한국정밀공학회지
• /
• 제9권3호
• /
• pp.140-148
• /
• 1992

The effect of mechanical, properties in the plastic zone near the crack-tip was investigated, under various controlled loading conditions, i.e., ${\Delta}K$ increasing, ${\Delta}K$ decreasing, and single overload test. For both ${\Delta}K$ decreasing test and ${\Delta}K$ increasing test with constant stress ratio, it is found that the ratio of material constant m'( ${\Delta}K$ decreasing test) to material constant m( ${\Delta}K$ increasing test) is larger than 1 for n<0.1, and it is equal to 1 for 0.10.2. A modified crack growth rate equation based on Forman's equation which applied stable region of fatigue crack propagation in ${\Delta}K$ decreasing test is proposed. Within the limit of this single overload test, an empirical relation between among the retardation ratio (Nd/ $N^{*}$), the strain hardening exponent (n) and the percent peak load (%PL) has been established.established.

• Toxicological Research
• /
• 제31권4호
• /
• pp.347-354
• /
• 2015

Excess manganese (Mn) is neurotoxic. Increased manganese stores in the brain are associated with a number of behavioral problems, including motor dysfunction, memory loss and psychiatric disorders. We previously showed that the transport and neurotoxicity of manganese after intranasal instillation of the metal are altered in Hfe-deficient mice, a mouse model of the iron overload disorder hereditary hemochromatosis (HH). However, it is not fully understood whether loss of Hfe function modifies Mn neurotoxicity after ingestion. To investigate the role of Hfe in oral Mn toxicity, we exposed Hfe-knockout ($Hfe^{-/-}$) and their control wild-type ($Hfe^{+/+}$) mice to $MnCl_2$ in drinking water (5 mg/mL) for 5 weeks. Motor coordination and spatial memory capacity were determined by the rotarod test and the Barnes maze test, respectively. Brain and liver metal levels were analyzed by inductively coupled plasma mass spectrometry. Compared with the water-drinking group, mice drinking Mn significantly increased Mn concentrations in the liver and brain of both genotypes. Mn exposure decreased iron levels in the liver, but not in the brain. Neither Mn nor Hfe deficiency altered tissue concentrations of copper or zinc. The rotarod test showed that Mn exposure decreased motor skills in $Hfe^{+/+}$ mice, but not in $Hfe^{-/-}$ mice (p = 0.023). In the Barns maze test, latency to find the target hole was not altered in Mn-exposed $Hfe^{+/+}$ compared with water-drinking $Hfe^{+/+}$ mice. However, Mn-exposed $Hfe^{-/-}$ mice spent more time to find the target hole than Mn-drinking $Hfe^{+/+}$ mice (p = 0.028). These data indicate that loss of Hfe function impairs spatial memory upon Mn exposure in drinking water. Our results suggest that individuals with hemochromatosis could be more vulnerable to memory deficits induced by Mn ingestion from our environment. The pathophysiological role of HFE in manganese neurotoxicity should be carefully examined in patients with HFE-associated hemochromatosis and other iron overload disorders.

• 대한수혈학회지
• /
• 제29권3호
• /
• pp.273-281
• /
• 2018

배경: 만성 적혈구 수혈 환자에서 철과잉 여부를 알아보기 위해 페리틴 검사를 시행하는데, 페리틴은 체내 저장철의 양을 반영하지만, 염증, 감염 등에서도 비특이적으로 증가할 수 있다. 본 연구에서는 고페리틴혈증을 보이는 환자에서 페리틴이 증가한 원인을 분석하고 적혈구제제 수혈과의 연관성을 알아보고자 하였다. 방법: 2017년 1월부터 12월까지 본 의료기관에 내원하여 페리틴 검사를 시행한 환자들의 의무기록을 후향적으로 검토하였다. 시행한 페리틴 검사에서 1,000 ng/mL이상의 결과를 보인 경우를 고페리틴혈증으로 정의하고 연구대상으로 정하였다. 페리틴 검사와 함께 시행된 혈청 철, TIBC (Total iron bind capacity), CRP (C-reactive protein) 검사결과와 진단명 등 의무기록을 조사하여 고페리틴혈증의 원인을 분석하였다. 결과: 해당 기간 동안 고페리틴혈증 결과를 보인 건은 238명 환자에서 417건이었다. 질환별로는 혈액종양질환이 31명에서 125건(30.0%)으로 가장 많았으며, 감염질환이 두번째로 많았다. 철과잉이 의심되는 경우는 33명 환자에서 119건이었으며, 이 중 검사 시행 전 1년 동안 적혈구제제수혈이 8단위를 초과한 경우는 12명(76건)이었다. 결론: 고페리틴혈증을 보이는 환자에서 실제 철과잉으로 판단되는 경우, 기저질환의 영향이 있었고 만성 적혈구제제 수혈과도 연관이 있었다. 체내 철 저장 상태를 정확히 파악하기 위해서 페리틴 외에 CRP, 철 포화도를 함께 측정하는 것이 도움이 된다. 습관적인 철분제제 처방, 잦은 수혈 처방시에 철과잉 발생 여부에 주의를 기울여야 한다.