• Title/Summary/Keyword: 손상 메커니즘

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Numerical Modelling of One Dimensional Gas Injection Experiment using Mechanical Damage Model: DECOVALEX-2019 Task A Stage 1A (역학손상모델을 이용한 1차원 기체 주입 시험 모델링: 국제공동연구 DECOVALEX-2019 Task A Stage 1A)

  • Lee, Jaewon;Lee, Changsoo;Kim, Geon Young
    • Tunnel and Underground Space
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    • v.29 no.4
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    • pp.262-279
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    • 2019
  • In the engineering barriers of high-level radioactive waste disposal, gases could be generated through a number of processes. If the gas production rate exceeds the gas diffusion rate, the pressure of the gas increases and gases could migrate through the bentonite buffer. Because people and the environment can be exposed to radioactivity, it is very important to clarify gas migration in terms of long-term integrity of the engineered barrier system. In particular, it is necessary to identify the hydro-mechanical mechanism for the dilation flow, which is a very important gas flow phenomenon only in medium containing large amounts of clay materials such as bentonite buffer, and to develop and validate new numerical approach for the quantitative evaluation of the gas migration phenomenon. Therefore, in this study, we developed a two-phase flow model considering the mechanical damage model in order to simulate the gas migration in the engineered barrier system, and validated with 1D gas flow modelling through saturated bentonite under constant volume boundary conditions. As a result of numerical analysis, the rapid increase in pore water pressure, stress, and gas outflow could be simulated when the dilation flow was occurred.

Treatment with Sparassis latifolia extract for repairing damaged hair (꽃송이버섯 추출물이 함유된 헤어 트리트먼트의 손상 모발 개선효과)

  • Hyun-A Choi;Yeo-Jin Lee;Moon-Hee Choi;Hyun-Jae Shin
    • Journal of Mushroom
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    • v.22 no.3
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    • pp.92-101
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    • 2024
  • Hair dyeing, hair perming, and daily hair dryer use can substantially damage hair. Consequently, the demand for products containing natural ingredients for the care of damaged hair is growing. Although polyphenols with antioxidant effects are often used for hair conditioning, few studies have focused on hair conditioning, and the potential of Sparassis latifolia mushroom extract for hair improvement has not been evaluated to date. In this study, the antioxidant activity of and polyphenol content in hot water, 70% and 100% ethanol (EtOH), n-hexane, ethyl acetate (EtOAc), and water extracts of S. latifolia were analyzed. A hair treatment containing S. latifolia extract was prepared, and its effect on damaged hair was evaluated. The highest antioxidant activity was observed in the hot water and EtOAc extracts. Moreover, polyphenol analysis using high-performance liquid chromatography and liquid chromatography-mass spectroscopy confirmed that the EtOAc fraction has relatively high contents of specific polyphenols beneficial for hair. Based on these results, a hair treatment containing S. latifolia extract was applied to damaged hair, and hair improvement was evaluated using hair thickness, tensile strength, and scanning electron microscopy. The hair treatment containing 70% EtOH extract effectively improved hair condition. We postulate that this improvement was caused by the high hydrophobic polyphenol content in the 70% EtOH extract.

Application of Risk-Informed Methods to In-Service Piping Inspection in Framatome Type Nuclear Power Plants (프라마톰형 원전의 배관 가동중검사에 리스크 정보를 활용한 기법 적용)

  • Kim, Jin-Hoi;Lee, Jeong-Seok;Yun, Eun-Sub
    • Journal of the Korean Society for Nondestructive Testing
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    • v.34 no.4
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    • pp.311-317
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    • 2014
  • The Pressurized water reactor owners group (PWROG) developed and applied a risk-informed in-service inspection (RI-ISI) program, as an alternative to the existing ASME Section XI' sampling inspection method. The RI-ISI programs enhance overall safety by focusing inspections of piping at high safety significance (HSS) locations where failure mechanisms are likely to be present. Additionally, the RI-ISI program can reduce nondestructive evaluation (NDE) exams, man-rem exposure for inspectors, and inspection time, among other benefits. The RI-ISI method of in-service piping inspection was applied to 3 units (KSNPs: Korea standard nuclear power plants) and is being deployed to the other units. In this paper, the results of RI-ISI for a Framatome type (France CPI) nuclear power plant are presented. It was concluded that application of RI-ISI to the plant could enhance and maintain plant safety, as well as provide the benefits of greater reliability.

한 인구학도의 회고

  • 김택일
    • Korea journal of population studies
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    • v.11 no.1
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    • pp.1-13
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    • 1988
  • This study examines the sampling bias that may have resulted from the large number of missing observations. Despite well-designed and reliable sampling procedures, the observed sample values in DSFH(Demographic Survey on Changes in Family and Household Structure, Japan) included many missing observations. The head administerd survey method of DSFH resulted in a large number of missing observations regarding characteristics of elderly non-head parents and their children. In addition, the response probability of a particular item in DSFH significantly differs by characteristics of elderly parents and their children. Furthermore, missing observations of many items occurred simultaneously. This complex pattern of missing observations critically limits the ability to produce an unbiased analysis. First, the large number of missing observations is likely to cause a misleading estimate of the standard error. Even worse, the possible dependency of missing observations on their latent values is likely to produce biased estimates of covariates. Two models are employed to solve the possible inference biases. First, EM algorithm is used to infer the missing values based on the knowledge of the association between the observed values and other covariates. Second, a selection model was employed given the suspicion that the probability of missing observations of proximity depends on its unobserved outcome.

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Durability Test and Micro-Damage Formation of Rubber Hose for Automotive Hydraulic Brake (자동차 유압브레이크용 고무호스의 내구성 시험 및 미세손상에 관한 연구)

  • Kwak, Seung-Bum;Choi, Nak-Sam;Lim, Young-Han
    • Composites Research
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    • v.21 no.1
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    • pp.40-45
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    • 2008
  • Rubber hose assembly for automotive hydraulic brake during operation is subject to combined stresses of cyclic pressure, cyclic bending and torsion as well as thermal load. The rubber hose is composed of ethylene-propylene diene monomer(EPDM) rubber layers reinforced by polyvinyl acetate(PVA) braided fabrics. A durability tester with loading rigs for inducing the above cyclic stresses was used to investigate failure mechanisms in the rubber hose assembly. Failure examination was performed at every 100 thousands cycles of bending and torsion. Hose samples were sectioned with a diamond-wheel cutter and then polished. The polished surface was observed by optical microscope and scanning electron microscope (SEM). Some interfacial delamination with a length of about 1mm along the interface between EPDM rubber and PVA fabrics was shown at the test cycles of 400,000. The delamination induced some cracking into the outer rubber skin layer to leading the final rupture of the hose.

Characterization of Etching profile for $LiNbO_3$ Optical Waveguide by Using Neutral Loop Discharge Plasma Dry Etching (NLD Plasma 식각 공정을 이용한 $LiNbO_3$ 광 도파로의 식각 Profile의 특성)

  • 박우정;양우석;이승태;김우경;장현수;이한영;윤대호
    • Proceedings of the Materials Research Society of Korea Conference
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    • 2003.03a
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    • pp.138-138
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    • 2003
  • 광대역 LiNbO$_3$ 광변조기의 초고속 광 변조 구현을 위해서는 RF/ optical 속도 정합 및 임피던스 매칭 조건 하에서 낮은 구동전압을 얻을 수 있는 ridge 구조의 제작이 필수적이며 이런 구조 제작하기 위해서는 식각 속도와 식각면 거칠기 식각 profile 및 식각 과정에서의 반응물의 감소 등과 같은 개선을 위한 연구가 필요하다. 본 연구에서는 LiNbO$_3$ 기판 위에 메탈 마스크를 형성한 후 비등방성 (anisotropic) 건식 식각 방법인 NLD (Neutral Loop Discharge)로 플라즈마 식각을 하였다. NLD plasma 식각은 1Pa 이하의 압력에서 낮은 전자 온도를 갖는 고밀도 플라즈마를 생성하고 이온 플라즈마를 형성하여 LiNbO$_3$ 표면의 원자와 분자를 이온충돌효과를 이용하여 물리적인 식각과 discharge로 형성된 레디칼 (radical)과의 상호작용에 의한 화학적 식각 메커니즘에 의한 방법으로 plasma에 의한 시편의 손상이 적으며 식각 속도가 또한 높은 것이 특징이다. 본 논문에서는 안테나 파워와 가스의 유량에 따른 LiNbO$_3$ 식각 profile 특성에 관하여 연구 하고자 한다.

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이중 주파수를 사용하는 펄스 플라즈마 특성에 관한 연구

  • Choe, Sang-Uk;Seo, Jin-Seok;Kim, Tae-Hyeong;Kim, Gyeong-Nam;Yeom, Geun-Yeong
    • Proceedings of the Korean Vacuum Society Conference
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    • 2014.02a
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    • pp.219.1-219.1
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    • 2014
  • 전자소자 산업의 미세화 및 대형화에 따라 플라즈마 밀도, 전위, 온도, 균일도 등 과 같은 플라즈마 특성을 제어하는 것은 차세대 플라즈마 장치 개발에 있어 매우 중요한 요소라고 할 수 있다. 특히, 급격한 소자의 미세화에 따라 플라즈마 공정을 통해 발생할 수 있는 damage는 큰 issue가 되어 왔고, 많은 연구자들은 이를 해결하기 위해서 다각적인 노력을 진행해 왔다. 그중 높은 전자 온도는 높은 전자 에너지에 의해 공정 중 소자를 손상 시키는 주된 원인이라고 보고되고 있으며, 이에 대한 제어기술은 매우 중요하다고 할 수 있다. 본 연구에서는 서로 다른 두 개의 내/외측으로 나뉘어진 나선형 모양의 ICP 안테나를 이용 하여 연구를 진행하였다. 내측의 안테나에는 2 MHz를 연결 하였으며, 외측의 안테나에는 13.56 MHz를 연결 하였으며, 내/외측 안테나에 각각 pulse mode로 입력전력을 인가해 줌으로써 플라즈마의 특성을 관찰하였다. Pulse / CW (Continuous Wave) mode에 있어서 전자온도의 측정을 위해 emissive probe 를 이용하여 plasma potential과 floating potential을 측정하였으며, 이를 통하여 전자온도를 계산하여 구할 수 있었다. Duty ratio 및 pulsing frequency의 변화에 따른 전자온도의 변화를 확인 할 수 있었으며, 그에 따른 플라즈마 균일도를 ion saturation current를 측정함으로써 관찰할 수 있었다. 실제 식각 공정에 있어서 Pulsing 조건에 따른 식각 특성을 관찰하기 위해, SiO2, ACL (Amorphous Carbon Layer)에 대해 식각을 진행하였으며, 식각 메커니즘 분석을 위해 이온에너지 분포의 변화를 PSM (Plasma Sampling Mass-spectroscopy)을 이용하여 측정하였다.

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A Study on Particle Size Distribution at High Pressure (고압에서 입자크기 분포 연구)

  • Ku, Hee-Kwon;Park, Byung-Gi;Kim, Jong-Yung;Jeong, Eun-Sun
    • Proceedings of the KAIS Fall Conference
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    • 2008.11a
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    • pp.347-349
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    • 2008
  • 발전소 물/증기 순환계통의 주요 기기인 증기발생기/보일러는 금속산화물과 각종 불순물이 축적되면 전열관이 손상되므로, 증기발생기/보일러 내부로 최소의 슬러지가 유입되고, 증기발생기 내부에서 금속산화물 입자가 형성되는 것을 억제하기 위해 수질관리를 하고 있으며, 증기발생기 내부에 존재하는 슬러지를 배출하기 위해 Blowdown 및 Sludge Lancing 등의 물리적 방법을 이용하는 기술이 개발되어 있다. 그러나 이러한 관리에도 불구하고 슬러지 성분인 금속산화물 농도는 운전 조건에 따라 매우 다르며(불순물 잠복 및 방출 현상), 아직까지 잠복현상에 대한 기본적인 메커니즘은 완전히 규명되고 있지 않다. 본 연구에서는 물/증기 순환계통 부식생성물의 물성 평가를 하기 위해 순환계통 기기들과 배관 부식생성물의 대부분인 철분이 부식에 가장 큰 영향을 미치기 때문에, 수화학 조건 및 금속합금 종류에 따라 생성되는 부식생성물을 철분을 중심으로 하여 실험하였고, 또한 부식생성물은 온도에 의해서도 영향을 많이 받기 때문에 다양한 온도에서도 부식생성물 생성 실험을 하였다.

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Failure Mechanism of Bendable Embedded Electronic Module Under Various Environment Conditions (Bendable 임베디드 전자모듈의 손상 메커니즘)

  • Jo, Yun-Seong;Kim, A Young;Hong, Won Sik
    • Journal of Welding and Joining
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    • v.31 no.5
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    • pp.59-63
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    • 2013
  • A bendable electronic module has been developed for a mobile application by using a low-cost roll-to-roll manufacturing process. In flexible embedded electronic module, a thin silicon chip was embedded in a polymer-based encapsulating adhesive between flexible copper clad polyimide layers. To confirm reliability and durability of prototype bendable module, the following tests were conducted: Moisture sensitivity level, thermal shock test, high temperature & high humidity storage test, and pressure cooker tester. Those experiments to induce failure of the module due to temperature variations and moisture are the experiment to verify the reliability. Failure criterion was 20% increase in bump resistance from the initial value. The mechanism of the increase of the bump resistance was analyzed by using non-destructive X-ray analysis and scanning acoustic microscopy. During the pressure cooker test (PCT), delamination occurred at the various interfaces of the bendable embedded modules. To investigate the failure mechanism, moisture diffusion analysis was conducted to the pressure cooker's test. The hygroscopic characteristics of the encapsulating polymeric materials were experimentally determined. Analysis results have shown moisture saturation process of flexible module under high temperature/high humidity and high atmosphere conditions. Based on these results, stress factor and failure mechanism/mode of bendable embedded electronic module were obtained.

The Etiological Relationship between Autoimmune Diseases and HERVs (자가면역 질환과 HERV의 병인학적 관계)

  • 정아람;김희수
    • Journal of Life Science
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    • v.13 no.2
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    • pp.236-240
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    • 2003
  • Human immune system acts to protect the host from infectious agents (bacteria, viruses, fungi, parasites) and from other noxious insults. However, immune diseases are sometimes caused by the impairment of immune system leading to abnormal immune response. Especially, autoimmune diseases are very diverse and often bring serious damage Although many active investigations to reveal the etiological mechanisms concerning the autoimmune diseases, it still remains unclear. After proposing a HERV (human endogenous retrovirus) as a candidate autoimmune gene in type I diabetes, it is newly attracting our attention for demonstrating that an endogenous human retroviral superantigen can be transactivated by interferon-$\alpha$ (IFN- $\alpha$) or Epstein-Barr virus (EBV) infection. These might provide us with powerful clues to carry out further studies to overcome autoimmune diseases as the presentation of a relatively clear connection between endogenous superantigens and human diseases.