• 한국안전학회지
• /
• 제31권5호
• /
• pp.95-101
• /
• 2016

This study proposes a multi-scale dynamic system reliability analysis of control system as a method of quantitative evaluation of its performance in probabilistic terms. In this second paper, we discuss the control effect of the viscous damper on the seismic performance of the structure-level failure. Since the failure of one structural member does not necessarily cause the collapse of the structural system, we need to consider a set of failure scenarios of the structural system and compute the sum of the failure probabilities of the failure scenarios where the statistical dependence between the failure scenarios should be taken into account. Therefore, this computation requires additional system reliability analysis. As a result, the proposed approach takes a hierarchial framework where the failure probability of a structural member is computed using a lower-scale system reliability with the union set of time-sequential member failures and their statistical dependence, and the failure probability of the structural system is again computed using a higher-scale system reliability with the member failure probabilities obtained by the lower-scale system reliability and their statistical dependence. Numerical results demonstrate that the proposed approach can provide an accurate and stable reliability assessment of the control performance of the viscous damper system on the system failure. Also, the parametric study of damper capacity on the seismic performance has been performed to demonstrate the applicability of the proposed approach through the probabilistic assessment of the seismic performance improvement of the damper system.

• 보건교육건강증진학회지
• /
• 제27권4호
• /
• pp.91-103
• /
• 2010

Objectives: This study was designed to understand the association between sociodemographic characteristics, health behaviors and channels retrieved for health information. Methods: Questionnaire survey was performed from April 2007 to May 2007 through household visiting. Sample was selected according to gender, household income, and residence district. We got 1,009 respondents and subgroups were as follows; 508 people had health insurance, 250 people were medical indigent group, and 251 people were medicaid beneficiaries. Results: People seemed to be separated into subgroups by channels used for health information. One was active and the other was passive group. Characteristics of passive group were older age, worker or inoccupation, less income, subjective poverty, lower education, loss of spouse, medical indigent or medicaid group. They usually got health information through mass media like TV and radio or medical professionals. Characteristics of active group were younger age, professional, more income, subjective affluence, higher education, single or married, and member of health insurance. They mainly got health information through printed media like newspaper or the Internet. Conclusion: We suggest to provide health information through various channels customed to individual needs and literacy. Public health stakeholders seems better to focus on people with low education, insufficient health literacy, poor health status, and short information technology.

• 대한조선학회논문집
• /
• 제59권1호
• /
• pp.29-38
• /
• 2022

In offshore installations, fires cause the structure to lose its rigidity and it leads to structural integrity and stability problems. The Passive Fire Protection (PFP) system slows the transfer rate of fire heat and helps prevent the collapse of structures and fatality. Especially, intumescent epoxy coating is widely used in the offshore industry, and not only is the material cost expensive, but it also takes a lot of time and cost for construction. Several studies have been conducted on the efficient application and optimal design of the PFP system. However, the mechanical properties and the strength of the PFP material have not been considered. In addition, researches on the correlation between the thickness of PFP and the structural behavior were insufficient. Therefore, this study aims to analyze the thermal and mechanical effects of the PFP on the structure when it is applied to the structural member. In particular, it is intended to resolve the change in strength characteristics of the structural members as the thickness of the PFP increases.

• 한국소음진동공학회:학술대회논문집
• /
• 한국소음진동공학회 2002년도 추계학술대회논문집
• /
• pp.6-11
• /
• 2002

This paper is concerned with the development of the vibration isolation system using piezoelectric actuators and sensors. The active vibration absorber system consists of 4 pairs of PZT actuators bonded on aluminum plates. Hence, the active system is directly connected to the passive system. The rubber attached to the end of the beam is connected to the upper base as a structural member. It allows bending thus maximizing the vertical movement generated by the piezoceramic actuators. The piezoceramic sensors consists of 4 PZT sensors known to tilting, rolling and vertical movement. This paper also presents the development and the movement of the system.

• Journal of Microbiology and Biotechnology
• /
• 제28권9호
• /
• pp.1443-1446
• /
• 2018

In the present study, we examined whether Lactobacillus johnsonii CJLJ103 (LJ) could alleviate cholinergic memory impairment in mice. Oral administration of LJ alleviated scopolamine-induced memory impairment in passive avoidance and Y-maze tasks. Furthermore, LJ treatment increased scopolamine-suppressed BDNF expression and CREB phosphorylation in the hippocampi of the brain, as well as suppressed $TNF-{\alpha}$ expression and $NF-{\kappa}B$ activation. LJ also increased BDNF expression in corticosterone-stimulated SH-SY5Y cells and inhibited $NF-{\kappa}B$ activation in LPS-stimulated microglial BV2 cells. However, LJ did not inhibit acetylcholinesterase activity. These findings suggest that LJ, a member of human gut microbiota, may mitigate cholinergic memory impairment by increasing BDNF expression and inhibiting $NF-{\kappa}B$ activation.

• 아태비즈니스연구
• /
• 제6권2호
• /
• pp.97-114
• /
• 2015

This study classify and compare leisure activities migrants women multi-cultural family member includes husband and children. Their common leisure activities is normal daily activity life comparable non leisure daily activity life. Those of common leisure actives is watching type of leisure such as reading book, eat out, visit relatives which reflect passive and egocentric. Therefore need to ownself active, self creative, as well as its family harmony oriented is more signigicant. Future study will be find out the barrier of cultural activities and advanture activities leisure for multi-cultural family.

• Structural Engineering and Mechanics
• /
• 제30권6호
• /
• pp.713-732
• /
• 2008

Serviceability and durability of the concrete members can be seriously affected by the corrosion of steel rebar. Carbonation front and or chloride ingress can destroy the passive film on rebar and may set the corrosion (oxidation process). Depending on the level of oxidation (expansive corrosion products/rust) damage to the cover concrete takes place in the form of expansion, cracking and spalling or delamination. This makes the concrete unable to develop forces through bond and also become unprotected against further degradation from corrosion; and thus marks the end of service life for corrosion-affected structures. This paper presents an analytical model that predicts the weight loss of steel rebar and the corresponding time from onset of corrosion for the known corrosion rate and thus can be used for the determination of time to cover cracking in corrosion affected RC member. This model uses fully the thick-walled cylinder approach. The gradual crack propagation in radial directions (from inside) is considered when the circumferential tensile stresses at the inner surface of intact concrete have reached the tensile strength of concrete. The analysis is done separately with and without considering the stiffness of reinforcing steel and rust combine along with the assumption of zero residual strength of cracked concrete. The model accounts for the time required for corrosion products to fill a porous zone before they start inducing expansive pressure on the concrete surrounding the steel rebar. The capability of the model to produce the experimental trends is demonstrated by comparing the model's predictions with the results of experimental data published in the literature. The effect of considering the corroded reinforcing steel bar stiffness is demonstrated. A sensitivity analysis has also been carried out to show the influence of the various parameters. It has been found that material properties and their inter-relations significantly influence weight loss of rebar. Time to cover cracking from onset of corrosion for the same weight loss is influenced by corrosion rate and state of oxidation of corrosion product formed. Time to cover cracking from onset of corrosion is useful in making certain decisions pertaining to inspection, repair, rehabilitation, replacement and demolition of RC member/structure in corrosive environment.

• 천문학논총
• /
• 제18권1호
• /
• pp.97-110
• /
• 2003

WRC-03 was held between 9 June and 4 July 2003 in Geneva, Switzerland. Over 2,200 delegates from 138 ITU Member States attended the Conference. The delegates considered some 2,500 proposals, and over 900 numbered documents related to 50 agenda items. The final output of the Conference consists of 527 pages of new and revised text of the Radio Regulations. This paper provides some details about the outcome of the radio astronomy related issues at the WRC-03 Conference. It is divided into two part: a) Agenda item1.8.2 and b) Agenda item 1.32, related to radio astronomy. Relevant extracts from the Final Acts of WRC-03 are given in the Appendix. Agenda item 1.8.2 was one of the most controversial Agenda Items at WRC-03. Studies were carried out within ITU-R TG 1/7 for the last three years; the results of these studies are summarized in Recommendation ITU-R SM.1633. The Conference adopted a new footnote (5.347A), that calls for the application of Resolution 739 (WRC-03) in the 1452-1492 MHz, 1525-1559 MHz, 1613.8-1626.5 MHz, 2655-2670 MHz, 2670-2690 MHz and 21.4-22.0 GHz bands. Agenda item 1.32 is to consider technical and reglatory provisions concerning the band 37.5-43.5 GHz, in accordance with Resolutions 128 (Rev.WRC-2000) and 84 (WRC-2000). WRC-03 reviewed and adjusted the New footnotes 5.551H and 5.551I cover the protection of radio astronomy observations in the 42.5-43.5 GHz band from unwanted emissions by non-geostationary (5.551H) and geostationary (5.551I) FSS and BSS systems, respectively.

• 한국구조물진단유지관리공학회 논문집
• /
• 제23권3호
• /
• pp.92-95
• /
• 2019

본 논문에서는 압분광법을 기반으로 강재에 작용하는 응력을 비파괴/비접촉식으로 측정할 수 있는 새로운 방법은 제안하고, 이에 대한 가능성을 실험적으로 검증하였다. 분광법은 일반적으로 대상물의 화학적 성분을 분석하는데 주로 사용되며, 토목분야에서는 강재의 부식을 판단하는데 일부 사용되고 있다. 압분광법은 대상물이 하중을 받을 때 측정된 스펙트럼이 하중이 없는 상태에서 측정된 스펙트럼으로부터 이동(Shift)되는 현상인, 압분광현상을 기반으로 응력을 측정하는 방법이다. 여기서, 응력-스펙트럼 이동 관계를 선형으로 가정하였을 때, 압분광 계수를 도출할 수 있으며, 이를 통하여 현재상태의 응력을 측정할 수 있다. 해당 기술은 레이저를 기반으로한 비접촉식 응력측정 기술로써, 최근에 철도 구조물에 대한 응력 측정을 시작으로 다양한 토목구조물의 응력측정에 대한 적용이 시도되고 있다. 본 연구에서는 이와 같은 압분광법 기술을 이용하여 강구조물의 응력을 측정할 수 있도록, 용사코팅을 이용하여 알루미나를 구조용 강재표면에 도포하고, 일축압축 하중시험을 수행하여 각 하중단계에서의 스펙트럼 이동(Shift)값을 확인하였다. 이를 통하여, 각 하중값과 스펙트럼 이동값이 선형관계임을 확인하였다. 따라서, 이와 같은 선형적인 관계로 부터, 1차 선형식의 상수값인 압분광 계수를 도출하고, 이를 통하여 강재에 작용하는 응력을 측정할 수 있을 것으로 기대된다.

• Earthquakes and Structures
• /
• 제11권4호
• /
• pp.701-721
• /
• 2016

Base isolation is a well-established passive strategy for seismic response control of buildings. In this paper, an efficient framework is proposed for reliability-based design optimization (RBDO) of isolated buildings subjected to uncertain earthquakes. The framework uses reduced function evaluations method, as an efficient tool for structural reliability analysis, and an efficient optimization algorithm for optimal structural design. The probability of failure is calculated considering excessive base displacement, superstructure inter-storey drifts, member stress ratios and absolute accelerations of floors of the isolated building as failure events. The behavior of rubber bearing isolators is modeled using nonlinear hysteretic model and the variability of future earthquakes is modeled by applying a probabilistic approach. The effects of pulse component of stochastic near-fault ground motions, fixity-factor of semi-rigid beam-to-column connections, values of isolator parameters, earthquake magnitude and epicentral distance on the performance and safety of semi-rigidly connected base-isolated steel framed buildings are studied. Suitable RBDO examples are solved to illustrate the results of investigations.