• 대한기계학회논문집A
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• 제40권8호
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• pp.721-724
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• 2016

실제 사용되는 기계 구조물의 수명 예측은 공정산포, 미래의 하중조건, 손상 모델의 불완전성 등으로 인하여 실험실에서 얻은 결과와 차이를 보일 수 밖에 없다. 본 연구에서는 이러한 불확실성이 내포된 기계 구조물의 피로파괴를 사전에 예지하기 위해 이중센서를 개발하고, 상온에서 단축 피로 하중을 받는 구조물에 적용하여 실증하였다. 이중 센서는 피로하중을 받는 대상 구조물보다 약간 더 큰 응력이 인가되도록 고안된 감지 구조물에 변형률 게이지를 부착한 형태이며, 균열이 센서자체에 먼저 발생함으로써 피로파괴를 예지하며, 쌍으로 제작된 감지부의 변형률 차를 이용하여 변동하중 하에서도 정상상태와 고장상태를 구분이 가능하다.

• Asian Pacific Journal of Cancer Prevention
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• 제16권3호
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• pp.1129-1133
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• 2015

Background: The tissue microarray (TMA) is widely accepted as a fast and cost-effective research tool for in situ tissue analysis in modern pathology. However, the current automated and manual TMA techniques have some drawbacks restricting their productivity. Our study aimed to introduce an improved manual tissue miniarray (TmA) technique that is simple and readily applicable to a broad range of tissue samples. Materials and Methods: In this study, a conventional TV/radio telescopic antenna was used to punch tissue cores manually from donor paraffin embedded tissue blocks which were pre-incubated at $40^{\circ}C$. The cores were manually transferred, organized and attached to a standard block mould, and filled with liquid paraffin to construct TmA blocks without any use of recipient paraffin blocks. Results: By using a conventional TV/radio antenna, it was possible to construct TmA paraffin blocks with variable formats of array size and number ($2-mm{\times}42$, $2.5-mm{\times}30$, $3-mm{\times}24$, $4-mm{\times}20$ and $5-mm{\times}12$ cores). Up to $2-mm{\times}84$ cores could be mounted and stained on a standard microscopic slide by cutting two sections from two different blocks and mounting them beside each other. The technique was simple and caused minimal damage to the donor blocks. H&E and immunostained slides showed well-defined tissue morphology and array configuration. Conclusions: This technique is easy to reproduce, quick, inexpensive and creates uniform blocks with abundant tissues without specialized equipment. It was found to improve the stability of the cores within the paraffin block and facilitated no losses during cutting and immunostaining.

• 한국소음진동공학회논문집
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• 제19권3호
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• pp.313-319
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• 2009

The blasting has a lot of economic efficiency and speediness but it can damage to a neighbor structure, a domestic animal and a cultured fish due to the blasting vibration, then the public grievance is increased. Therefore, we need to manage the blasting vibration efficiently. The prediction of the correct vibration velocity is not easy because there are lots of different kinds of the scale of blasting vibration and it has a number of a variable effect. So we figure the optimum line through the least-squares regression by using the vibration data measured in hard rock blasting and compared with the design vibration prediction equation. As a result, we confirm that the vibration estimated in this paper is bigger than the design vibration prediction equation in the same charge and distance. If there is a Gaussian normal distribution data on the left-right side of the least squares regression, then we can estimate the vibration prediction equation on reliability 50%(${\beta}=0$), 90%(${\beta}=1.28$), 95%(${\beta}=1.64$). 99.9%(${\beta}=3.09$). As a result, it appears to be suitable that the reliability is 99% at the transverse component, the reliability 95% is at the vertical component, the reliability 90% is at the longitudinal component and the reliability is 95% at the peak vector sum component.

• 한국강구조학회 논문집
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• 제19권3호
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• pp.271-280
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• 2007

본 연구에서는 단재하경로 구조로 인식되는 2-거더교에서 한 개 거더의 손상 시 여유도를 평가하기 위한 실험적 연구를 수행하였다. 실험변수는 하부 수평브레이싱으로 하여 하부 수평브레이싱이 설치된 경우와 설치되지 않은 경우의 단경간 1/5 모형 시험체 2개를 제작하였다. 먼저 균열이 없는 정상상태 시험체에 대해서 탄성범위 내에서 재하실험을 수행하였으며, 이후 지간 중앙부의 한 개 거더에 인위적인 손상을 가한 후 종국상태에 이르기까지 재하 실험을 수행하였다. 실험으로부터 정상상태의 교량에서도 수평브레이싱은 하중 재분배 역할을 수행하였으며, 한 개 거더에 심각한 손상이 발생한 경우에는 가로보와 바닥판이 비균열 거더 측으로 하중 재분배 기능을 일부 수행하였으나, 특히 하부 수평브레이싱은 2-거더교의 손상 시 여유도 향상에 매우 중요한 기능을 하는 것으로 나타났다.

• Journal of Biosystems Engineering
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• 제42권4호
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• pp.251-257
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• 2017

Purpose: A chisel mounted on working implement, such as agricultural machinery used in irregular farming conditions, is subjected to highly variable fatigue loading during work. To ensure the safety of the chisel on a working implement for the duration of its service life, fatigue testing must be performed with the proper fatigue test load conditions. In this study, working loads for a chisel were developed by reconstructing loads from strain gage data collected during field tests and used to conduct fatigue tests on the chisel component. Methods: FE analysis with nCode software was utilized to select the proper quantity and locations of strain gages for load measurements. A fatigue test was performed to experimentally verify the fatigue strength of the chisel and to evaluate the validity of the load history developed with the load reconstruction technique. Results: A strain history for the chisel was obtained from data collected during field tests. The data was filtered for the 14-16 km/h speed range, connected, and merged. The chisel load history was developed using the load reconstruction technique. The resulting load history was expressed as a load spectrum using the rain-flow counting method. Conclusions: A fatigue test was conducted on a chisel under a constant load condition with an equivalent load amplitude and number of cycles, as calculated by Miner's Rule for linear damage accumulation. During the fatigue test, there were no cracks at any position. It is concluded that the fatigue test method proposed in this study can be utilized successfully as a durability evaluation method for the chisel.

• 대한조선학회논문집
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• 제28권1호
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• pp.125-138
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• 1991

본 연구에서는 이상화구조요소법(理想化構造要素法)을 적용하여 좌초시(坐礁時) 이중저구조(二重底構造)의 손상(損傷) 및 강도(强度)를 효율적으로 해석할 수 있는 방법을 개발하였다. 또한 좌초사고(坐礁事故) 발생시에 이중저구조(二重底構造)의 내저판(內底板)이 손상을 받지 않기 위해 필요한 최소한도의 이중저높이, 즉 유효이중저(有效二重底) 높이의 결정법도 제안하였다. 이중저구조모델에 대한 기존의 실험(實驗) 및 탄소성대변형(彈塑性大變形) 유한요소해석(有限要素解析) 결과와 본해석법에 의한 해석결과를 비교하여 본해석법의 정도(精度)와 효율성(效率性)을 확인하였다. 다음으로, 본 해석법을 이중선각(二重船殼) 구조설계개념(構造設計槪念)을 바탕으로 설계된 4만톤급 정유운반성(精油運搬船)의 좌초문제(坐礁問題)에 적용하여 이중저구조의 수직부재(垂直部材) 간격 및 판두께와 이중저높이 등이 좌초시(坐礁時) 손상(損傷)에너지 흡수능력에 미치는 영향을 고찰하였으며, 또한 이들결과를 바탕으로 각 설계인자의 변화에 따른 최소이중저(最小二重底) 높이를 계산하였다.

• 한국철도학회논문집
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• 제19권1호
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• pp.97-108
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• 2016

국내 화물운송의 80% 이상을 분담하고 있는 공로중심의 내륙운송체계는 환경문제를 비롯한 다양한 사회적 비용을 야기시키고 있어 다른 운송수단으로의 화물전환이 요구되고 있다. 특히 변화하는 국제 물류환경을 고려해볼 때, 철도는 지속가능한 대안적 운송수단임에 분명하며, 도로화물을 철도로 전환시키고 새로운 수요를 창출하여 내륙철도의 경쟁력을 확보하는 일은 미래를 예측하고 대비하기 위한 필수적 선행과제가 되었다. 따라서 본 연구는 내륙철도 이용 확대를 위하여 컨테이너화주를 대상으로 컨테이너 화물을 철도로 유인하기 위한 핵심 요인을 밝히고자 설문조사를 실시하고 SmartPLS구조방정식모델링 분석기법을 통하여 결과를 도출하였다.

• Advances in pediatric surgery
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• 제16권2호
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• pp.101-107
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• 2010

Herniorrhaphy of Indirect inguinal hernia (IIH) is one of the most frequently performed surgical procedures in children. The overall incidence of inguinal hernias in childhood ranges from 0.8 to 4.4 %. The incidence is up to 10 times higher in boys than girls, especially much higher in premature infants. IIHs in children are basically an arrest of embryologic development rather than an acquired weakness, which explains the increased incidence in premature infants. In normal development, the processus vaginalis closes, obliterating the peritoneal opening of the internal ring between 36th and 40th week of gestation. This process is often incomplete, leaving a small patent processus in many newborns. However, closure continues postnatally, and the rate of patency is inversely proportional to age of the child. The presence of a patent processus vaginalis is a necessary but not sufficient variable in developing a congenital IIH. In other words, all congenital IIHs are preceded by a patent processus vaginalis, but not all patent processus vaginalis go on to become IIHs. The overall incidence of IIH in population is approximately 1 to 2 % and the incidence of a processus vaginalis is approximately 12 to 14%, clinically appreciable IIH should develop in approximately 8 to 12 % of patients with a patent processus vaginalis. Although the classic open inguinal hernia repair remains the gold standard for most pediatric surgeons, laparoscopic repair is being performed in many centers. Like open technique, laparoscopic technique is fundamentally a high ligation of the indirect hernia sac with or without internal ring ligation. The advantages of laparoscopic approach include the ease of examining the contralateral internal ring, the avoidance of access damage to vas and vessels during mobilization of cord, decreased operative time, and an ability to identify unsuspected direct or femoral hernias. Almost all groin hernias in children are IIHs and occur as a result of incomplete closure of processus vaginalis. The treatment is repair by high ligation of hernia sac, which can be done by an open or laparoscopic technique. The contralateral side can be explored by laparoscopy or left alone, open exploration is no longer indicated due to potential risk of infertility.

• 한국공간구조학회논문집
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• 제9권3호
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• pp.93-100
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• 2009

최근 문화유산에 대한 관심이 고조 되면서 노후화된 건조물문화재의 보존에 대한 중요성이 대두되고 있다. 건조물문화재의 대부분이 목재를 주재료로 사용하였으며, 이들 건조물문화재의 노후화에 따른 부식 및 손상에 대한 보존수리는 부재자체의 문화재적 가치를 고려하여 원형유지를 기본원칙으로 한다. 이에 따라, 합성수지를 이용한 보존처리방법이 부각되고 있다. 이에 본 논문은 합성수지로 보강한 원형단면 목재의 압축보강 성능에 관한 실험적 연구로서 합성수지의 보강단면적비율, 단면의 보강방향, 보강길이, 합성수지강도를 변수로 하여 총 14개의 시험체를 제작하여 실험하였다. 실험결과 합성수지를 이용하여 적절하게 보강할 경우 신재이상의 보강효과가 있는 것으로 나타났으며 문화재의 보수 및 보강에서 가장 중요한 오센티시티(authenticity)를 확보할 수 있을 것이다.

• Restorative Dentistry and Endodontics
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• 제20권2호
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• pp.549-576
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• 1995

Bacteria are one of the most important causative agents of the pulpal and periapical diseases. Streptococci are one of the most frequently isolated facultative anarerobic bacteria in the infected root canals. Bacterial cell wall components have a direct effect in the pathogenesis of the pulpal and periapical infections. Hyaluronidase produced by bacteria has been implicated in dissemination of the diseases. The purpose of this study was to evaluate the effect of cell wall extract of streptococci on the L929 cells using inverted microscope and the transmission electron microscopy (TEM). Hyaluronidase production of streptococcal strains were investigated to determine the correlation between the severity of cell damage and the activity of enzymes. Bacterial cell wall extracts of S. sanguis, S. mitis and S. uberis isolated from infected root canals and ATCC type strains of S. mutans (ATCC 10449) and E. faecalis (ATCC 19433) were prepared by sonication and confirmed with SDS-PAGE. Silver stain of SDS-PAGE of sonic extract was efficient at $100{\mu}g$/ml concentration of cell wall protein, while Coomasie blue stain was efficient at $100{\mu}g$/ml concentration. Inverted microscope showed that sonic extract-treated L929 cells were round and detached from the substratum while others lost their fibroblastic shapes. Transmission electron microscopic examination revealed that streptococcal extracts induced death of L929 cells. Sonic extracts of streptococci had variable effect on microstructure of L929 cells. significant chromatin condensation was observed in the nucleus of the cells. Disappearance of cell surface microvilli and nuclear fragments with dense chromatin were observed. The cell nucleus had an irregular shape and numerous large vacuoles were seen in the cytoplasm and some breaks of the cell membrane could be seen. Cell organelles were in various stages of destruction and cristae of mitochondria were disoriented or disappeared. Eighteen strains of streptococci did not produce hyaluronidase.