• Tribology and Lubricants
• /
• 제38권3호
• /
• pp.101-108
• /
• 2022

The structure and properties of tetrahedral amorphous carbon (ta-C) coatings depend on the main process parameters and bending angles of the magnetic field filter used in the filtered cathodic vacuum arc (FCVA). During the process, it is possible to effectively control the plasma flux of carbon ions incident on the substrate by controlling the arc discharge current, thereby influencing the mechanical properties of the coating film. Furthermore, we can control the size and amount of large particles mixed during carbon film formation while conforming with the bending angle of the mechanical filter mounted on the FCVA; therefore, it also influences the mechanical properties. In this study, we consider tribological characteristics for filtered bending angles of 45° and 90° as a function of arc discharge currents of 60 and 100 A, respectively. Experiment results indicate that the frictional behavior of the ta-C coating film is independent of the bending angle of the filter. However, its sliding wear behavior significantly changes according to the bending angle of the FCVA filter, unlike the effect of the discharge current. Further, upon changing the bending angle from 45° to 90°, abrasive wear gets accelerated, thereby changing the size and mixing amount of macro particles inside the coating film.

• Advances in concrete construction
• /
• 제10권5호
• /
• pp.455-462
• /
• 2020

This study investigated the effect of horizontal casting joints on the mechanical properties and structural behavior of sustainable self-compacting reinforced concrete beams (SCRCB). The experimental research consisted of two stages. The first stage used four types of concrete mixtures which were produced to indicate the effects of cement replaced with cement waste at 0%, 5%, 10%, and 15% by weight of cement content on fresh concrete properties of self-compacting concrete (SCC) such as, passing ability, filling ability, and segregation resistance. In addition, mechanical properties such as compressive, tensile, and flexural strength were also studied. The second stage selected the best mixture from the first stage and studied the effect of horizontal casting joints on the structural behavior of sustainable SCRCBs. The effect of horizontal casting joints on the mechanical properties and structural behavior were at the 25%, 50%, 75%, and 100% of sample height. Load deflection, failure mode, and theoretical analysis were studied. Results indicated that the incorporation of replacement with cement waste by 5% to 10% led to economic and environmental advantages, and the results were acceptable for fresh and mechanical properties. The results indicated that delaying the time for casting the second layer and increasing the cement waste in concrete mixtures had a great effect on the mechanical properties of SCC. The ultimate load capacity of horizontal casting joints reinforced concrete beams slightly decreased compared with the control beam. The maximum deflection of casting joint beams with 75% of samples height is similar with the control beam. The experimental results of reinforced concrete beams were substantially acceptable with the theoretical results. The failure modes obtained the best forced casting joint on the structural behavior at 50% height of casting in the beam.

• Corrosion Science and Technology
• /
• 제3권5호
• /
• pp.187-193
• /
• 2004

We have investigated the differences between the general corrosion and microbiologically influenced corrosion (MIC) of steels in terms of electrochemical behavior and surface phenomena. Corrosion potential of steels in the absence of SRB (sulfate-reducing bacteria) shifted to a low level and was maintained throughout the experimental period (40 days). The potential in the presence of SRB, however, shifted to a noble level after 20 days' incubation, indicating the growth of SRB biofilms on the test metal specimens and a formation of corrosion products. In addition, the color of medium inoculated with SRB changed from gray to black. The color change appeared to be caused by the formation of pyrites (FeS) as a corrosion product while no significant color change was observed in the medium without SRB inoculation. Moreover, corrosion rates of various steels tested for MIC were higher than those in the absence of SRB. This is probably because SRB were associated with the increasing corrosion rates through increasing cathodic reactions which caused reduction of sulfate to sulfide as well as formation of an oxygen concentration cell. The pitting corrosions were also observed in the SRB-inoculated medium.

• Asian Pacific Journal of Cancer Prevention
• /
• 제15권17호
• /
• pp.7309-7316
• /
• 2014

Background: While many researchers often use a theoretical framework for mammogram repeat interventions, it seems they do not apply an identified mediation analysis method. The aim of this study was to determine the mediators of mammogram replication behavior in two tailored interventions for non-adherent Iranian women. Materials and Methods: A sample population of 184 women over 50 years old in Sanandaj, Iran, was selected for an experiment. Participants were randomly allocated into one of the three conditions: 1) an intervention based on the Health Belief Model (HBM) 2) an intervention based on an integration of the HBM and selected constructs from the Theory of Planned Behavior (TPB), and 3) a control group. Constructs were measured before the intervention, and after a 6-month follow-up. Results: Perceived self-efficacy, behavioral control, and subjective norms were recognized as mediators in the HBM and selected constructs from the TPB intervention. Perceived susceptibility, severity, barriers, self-efficacy and behavioral control met the criteria for mediation in the HBM intervention. Conclusions: This study was successful in establishing mediation in a sample of women. Our findings enrich the literature on mammography repeat, indicating key intervention factors, and relegating redundant ones in the Iranian populations. The use of strategies to increase mammography repeat, such HBM and TPB constructs is suggested to be important for maintaining a screening behavior, once the behavior has been adopted.

• 한국산학기술학회논문지
• /
• 제20권4호
• /
• pp.428-434
• /
• 2019

동물복지의 관심고조는 전 세계적인 동향이며 최근 국내 소비자들의 복지는 반려동물에서 경제동물인 가축으로 확산되고 있다. 환경보조물은 동물복지수준 강화에 유용한 수단으로 활용되고 있으나 임신돈에서는 관련 연구는 제한적이다. 따라서, 본 연구는 환경보조물이 임신모돈의 생산성 및 행동특성에 미치는 영향을 구명하고자 실시하였다. 시험동물은 30두의 임신돈(랜드레이스)를 준비하였고, 완전임의배치법에 의거하여 3개 처리구(대조구; T1, 플라스틱 소재 놀이기구; T2, 볏짚)에 처리구당 10두씩 배치하였다. 사양시험은 임신 28-105일령동안이며 볏짚과 놀이기구는 시험돈방($11.6{\times}6.0m$) 중앙에 배치하였다. 시험 종료일에 체중 및 등지방두께를 측정하였으며 혈중 코티졸 농도를 분석하였다. 행동특성 분석을 위해 임신 91일령에 행동패턴을 24시간 촬영하였고 행동특성을 분석하였다. 시작 및 종료체중은 대조구 및 처리구간 차이를 나타내지 않았다. 등지방두께는 대조구보다 T2에서 감소하였다(C, 16.56mm vs. T2, 15.73mm; p>0.05). 총산자수, 실산자수는 처리구간 차이가 없다. 사산수는 T1 및 T2에서 대조구보다 감소하였다(1.00 and 0.63 vs. 1.50두; p>0.05). 분만폐사율은 사산수와 유사한 경향을 보였다(C, 8.68%; T1, 6.86%; T2, 3.40%). 혈중 코티졸은 대조구 및 처리구간 차이가 없다. 섭취행동은 T2에서 대조구 및 T1 처리구보다 감소하였다(1.81 vs. 9.68 and 6.99%; p<0.05). 놀이 및 파헤치기 행동은 각각 T1와 T2 처리구에서만 확인되었다(p<0.05). 반면에 사육시설에 문지르기 행동은 대조구에서만 관촬되었다(p<0.05). 이러한 결과는 환경보조물 제공이 임신돈의 생산성에 부정적인 영향을 미치지 않으면서 돼지의 행동특성은 복지향상에 도움이 될 것으로 판단된다.

• 한국터널지하공간학회 논문집
• /
• 제17권4호
• /
• pp.441-455
• /
• 2015

본 연구에서는 터널 시공 중 굴진면에서의 붕괴 위험을 판단하여 작업자의 안전을 확보할 수 있는 굴진면 안전감시시스템을 개발하였다. 이 시스템은 실시간으로 측정되는 굴진면 변위를 x-MR 관리도기법으로 실시간 분석함으로써 굴진면의 이상 거동을 감시할 수 있다. 또한 관리 기준을 초과하는 측정치의 개수와 이동 범위 k를 비교하여 굴진면의 이상 거동과 작업 과정에서 발생하는 오류를 구분할 수 있도록 오경보 판단 알고리듬을 개발하였다. 본 연구결과는 위험지반 구간에서의 굴진면의 실시간 거동 감시에 적용되어 작업자의 피해를 최소화 할 수 있을 것으로 판단된다.

• Smart Structures and Systems
• /
• 제20권5호
• /
• pp.619-636
• /
• 2017

Magnetorheological (MR) damper is a type of controllable device widely used in vibration mitigation. This device is highly nonlinear, and exhibits strongly hysteretic behavior that is dependent on both the motion imposed on the device and the strength of the surrounding electromagnetic field. An accurate model for understanding and predicting the nonlinear damping force of the MR damper is crucial for its control applications. The MR damper models are often identified off-line by conducting regression analysis using data collected under constant voltage. In this study, a MR damper model is integrated with a model for the power supply unit (PSU) to consider the dynamic behavior of the PSU, and then a real-time nonlinear model updating technique is proposed to accurately identify this integrated MR damper model with the efficiency that cannot be offered by off-line methods. The unscented Kalman filter is implemented as the updating algorithm on a cyber-physical model updating platform. Using this platform, the experimental study is conducted to identify MR damper models in real-time, under in-service conditions with time-varying current levels. For comparison purposes, both off-line and real-time updating methods are applied in the experimental study. The results demonstrate that all the updated models can provide good identification accuracy, but the error comparison shows the real-time updated models yield smaller relative errors than the off-line updated model. In addition, the real-time state estimates obtained during the model updating can be used as feedback for potential nonlinear control design for MR dampers.

• 보건교육건강증진학회지
• /
• 제26권4호
• /
• pp.105-116
• /
• 2009

Objectives: In recent years, pregnancy rate among female adolescents has increased and caused a variety of physical and social problems. Therefore, this study aimed to investigate sexual behavior, delinquent behavior, and pregnancy rate among Korean female adolescents. Methods: In light of the growing interest in adolescent pregnancy, this study conducted a web-based survey, titled "The 2006 Youth Health Risk Behavior Survey." The Korean Center for Disease Control (KCDC) collected questionnaire responses from 34,200 young women. The collected data were analyzed through chi-square test and logistic regression using SPSS Win 14.0 version. Results: This study analyzed main factors, which can predict pregnant experience. The statistic results showed two types of the predicting factors: (1) personal factors: sexual relations after drinking (odds 25.1), Narcotic drug taking (odds 13.0), sexual violence act (odds 7.0), part-time job(odds 2.5), drinking, smoking ; and (2) environmental factors: stepfather(odds 4.2) and natural mother. Conclusion: The influential factor identification for predicting pregnancy rate is important to develop an effective education program for preventing the adolescent pregnancy. The education programs with referring to the identified factors can contribute to reducing the unwilling pregnancy rate of young woman.

• Journal of the Korean Wood Science and Technology
• /
• 제36권5호
• /
• pp.42-48
• /
• 2008

This study was conducted to discuss the effects of hardener and extender contents on peak temperature, reaction enthalpy (${\Delta}H$), gelation time, viscosity change, and pH value in three types of UMF (urea-melamine- formaldehyde) resin with the help of perpHecT LogR meter, differential scanning calorimetry (DSC), and advanced rheometric expansion system (ARES), The results indicated that the pH value of Control A steeply decreased to 5,2 in the early stage but relatively remained constant thereafter as in Synthesis 1 and Synthesis 2, The peak temperature and time decreased as well, whereas ${\Delta}H$ and viscosity increased with the increase of hardener content. On the other hand, ${\Delta}H$ was not changed up to the extender content of 5% and then decreased with its further addition, And the pH value and peak temperature showed no change with the increase of extender content at the hardener content of 5% in three types of UMF resin, The effect of hardener content in this experiment, however, appeared more conspicuous in Control A than in the other two types of Synthesis 1 and Synthesis 2, These results might be caused by higher molecular weight with longer chains of methylene ($-CH_2-$) and methylene ($-CH_2-O-CH_2-$) ether bridges or much more branched chains in Control A.

• 상하수도학회지
• /
• 제19권2호
• /
• pp.117-124
• /
• 2005

Appropriate removal of pollutants from combined sewer overflows(CSOs) and stormwater runoff is of primary concern to watershed managers trying to meet water quality standards even under a wet weather condition. Harmful substances associated with particles besides TSS and BOD are subjected to removal prior to discharge into the natural waters. Effectiveness of five major hydrodynamic separation technologies, Vortechs, Downstream Defender including Storm King for CSOs control, CDS, Stormceptor, and IHS, were evaluated in this study. There is not sufficient information for accurate evaluation of the removal efficiency for the pollutants from the stormwater runoff and CSOs. Based upon limited engineering data, however, all technologies were found to be effective in separation of heavy particles and floating solids. Technologies utilizing screens seem to have advantage in the treatment capacity than the other technologies relied fully on hydrodynamic behavior. The IHS system seems to have a strong potential in application for control of CSOs because of unique hydrodynamic behavior as well as a flexibility in opening size of the screens. Size of the particulate matter in the CSOs and stormwater runoff is found to be the most important parameter in selection of the type of the hydrodynamic separators. There exists an upper limit in the solids removal efficiency of a hydrodynamic separator, which is strongly dependent upon the particle size distribution of the CSOs and stormwater runoff.