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Paul Reichle,Gerd Reichardt,Manuel Henn,Georg Umlauf,Jakob Barz,Kim Rouven Riedmüller,Mathias Liewald,Günter E. M. Tovar 한국정밀공학회 2023 International Journal of Precision Engineering and Vol.10 No.4
In order to reduce the use of classic lubricants such as synthetic or mineral oils, emulsions or waxes in the deep drawing process, a new tribological system based on volatile lubricants was investigated. In this system, a volatile medium is injected under high pressure through laser drilled micro holes directly into the contact zone between the tool and the sheet metal and serves as a temporary lubricant. In order to investigate this tribological system under realistic conditions, strip drawing experiments with different volatile lubricants (air, nitrogen, carbon dioxide and argon) were performed on galvanized sheets. Therefore, a new generation of strip drawing tools was designed and numerically calculated for low elastic deformations to ensure a uniform contact pressure distribution over the entire friction contact area. To obtain a homogeneous distribution of the volatile lubricants, a number of micro holes with a depth of several millimeters were drilled into the hardened strip drawing jaws using ultrashort pulsed laser radiation. Taking into account the capabilities of this laser drilling technique in terms of size and shape of the micro holes, computational fluid dynamics simulations were performed to predict the flow behavior of the lubricant within the micro hole as well as the contact zone and were compared with observable effects in outflow tests. The chemical composition of the acting tribological layers was characterized by means of X-ray photoelectron spectroscopy and their changes during the deep drawing process were correlated with the lubricants used as well as the measured wear and friction values.
Jakobs, G. 啓明大學校 社會科學硏究所 1992 한국사회과학연구 Vol.11 No.-
어떤 행위의 객관적 귀속가능성의 배제사유로는 다음을 들 수 있다. 첫째, 행위는 그 종류 및 정도에 따라 허용된 위험내의 것이 될 수 있다. 둘째, 그 행위는 아무런 해가 없으며, 또 다른 사람의 자의에 의해 범죄로 전환도니 것일 수도 있다. 셋째, 위험한 행위의 살상은 다른 사람의 몫일 수 있다. 넷째, 그 희생자가 자신의 행위 때문에 혹은 그가 불행을 감수해야만 하기 때문에 그 손해(결과)에 대한 관할을 지닐 수도 있다. 결론은 다음과 같다. 행위자가 적어도 실질적인 의미에서 피해의 회피를 위한 보증인일 때에만 그는 허용되지 않은 위험한 행위를 한 것이다. 사람들이 보증인 지위의 인정 여부를 위한 유형을 선택할 것인지는 더 이상 언급하지 않아도 되리라 본다. 사회적 세계의 다채로움은 전적으로 상이한 모습으로 나타난다. 물리적 사질로서의 인과성과 심리적 사실로서의 고의가 귀속을 결정하는 유일한 것이 아니라, 인과성을 다루는 것에 대한 사회적 기대의 실망도, 즉 행위의 의사소통상의 의미측면도 형법적으로 중요한 측면이라는 점을 인정하는 한, 객관적 귀속의 필수성에 대한 다음의 사항에는 견해가 일치한다. : 형법상의 귀속에서는 자연의 한 단면이 아니라, 사회의 한 단면이 문제되는 것이다.
Storz, Corinna,Kolb, Manuel,Kim, Jong Hyo,Weiss, Jakob,Kunz, Wolfgang G.,Nikolaou, Konstantin,Bamberg, Fabian,Othman, Ahmed E. Elsevier 2018 Academic radiology Vol.25 No.3
<P><B>Rationale and Objectives</B></P> <P>To determine the intraindividual impact of radiation dose reduction in abdominal computed tomography (CT) on diagnostic performance in patients with suspected appendicitis.</P> <P><B>Materials and Methods</B></P> <P>This study was approved by the institutional review board. Seventy-five patients who underwent standard contrast-enhanced abdominal CT for suspected appendicitis between 2004 and 2009 were retrospectively included. Low-dose CT reconstructions with 75%, 50%, and 25% of the original radiation dose level were generated by applying realistic reduced-dose simulation. Two blinded, independent readers assessed image quality, signal-to-noise ratio, and diagnostic confidence on each dataset. Diagnostic accuracy for detection of appendicitis and complications were calculated for each reader. Paired univariate tests were used to determine intraindividual differences.</P> <P><B>Results</B></P> <P>Among 75 subjects included in the analysis (57% female, mean age: 41 ± 18 years), the prevalence of histopathologically confirmed appendicitis was 59%. Signal-to-noise ratio and subjective image quality of 50% and 25% reduced-dose CTs were significantly lower than the reference datasets (all <I>P</I> < .005). Appendicitis was correctly identified in all reference and low-dose datasets (sensitivity: 100%, negative predictive value: 100%). Presence of complications was correctly detected in all reference, 75%, and 50% datasets, but was decreased in 25% datasets (sensitivity: 77.8% and negative predictive value: 97.4%). Diagnostic confidence was high for original and 75% datasets, but significantly lower for 50% and 25% datasets (<I>P</I> < .001).</P> <P><B>Conclusions</B></P> <P>Our results indicate that diagnostic accuracy in abdominal CT acquisitions acquired at 75% and 50% of radiation dose is maintained in patients with suspected appendicitis, whereas further reduction of radiation exposition is associated with decreased diagnostic performance.</P>