• 한국소음진동공학회논문집
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• 제21권10호
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• pp.883-889
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• 2011

The brand sound of vehicle diesel engine is recently one of the important advantage strategies in the automotive company. Because various noise components masked under high frequency level can be audible in quieter driving situation. Many researches have been carried out for subjective and objective assessments on vehicle sounds and noises. In particular, the interior sound quality has been one of research fields that can give high quality feature to vehicle products. Vehicle interior noise above 500 Hz is usually controlled by sound package parts. The materials and geometries of sound package parts directly affect on this high frequency noise. This paper describes the sound quality evaluation method for the vehicle diesel engine noise to establish objective criteria for sound quality assessment. Considering the sensitivity of human hearing to impulsive sounds such as diesel noise, the human auditory mechanism was simulated by introducing temporal masking in the time domain. Furthermore, each of the human auditory organs was simulated by computer codes, providing reasonable analytical explanations of typical human hearing responses to diesel noise. This method finally provides the sound quality index of vehicle diesel engine noise that includes high frequency intermittent offensive sounds caused by impacting excitations of combustion and piston slap.

• Smart Structures and Systems
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• 제16권3호
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• pp.521-535
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• 2015

Vibration-based monitoring is one approach used to perform structural condition assessment. By measuring structural response, such as displacement, dynamic characteristics of a structure may be estimated. Often, the primary dynamic responses in civil structures are below 5 Hz, making accurate low frequency measurement critical for successful dynamic characterization. In addition, static deflection measurements are useful for structural capacity and load rating assessments. This paper presents a DC coupled continuous wave radar to accurately detect both dynamic and static displacement. This low-cost radar sensor provides displacement measurements within a compact, wireless unit appropriate for a range of structural monitoring applications. The hardware components and operating mechanism of the radar are introduced and a series of laboratory experiments are presented to assess the performance characteristics of the radar. The laboratory and field experiments investigate the effect of factors such as target distance, motion amplitude, and motion frequency on the radar's measurement accuracy. The results demonstrate that the radar is capable of both static and dynamic displacement measurements with sub-millimeter accuracy, making it a promising technology for structural health monitoring.

• Journal of the Korean Academy of Child and Adolescent Psychiatry
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• 제26권1호
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• pp.45-51
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• 2015

Objectives : Children with attention-deficit hyperactivity disorder (ADHD) have been shown to display more inhibitory deficits and executive function deficits. This study investigated the treatment effects of neurofeedback (NF) training on executive function by comparing the results of neuropsychological tests of the trained children at pre- and post-training. Methods : Fifteen children with ADHD, aged 6 to 14 years, participated in the study. The NF treatment consisted of slow cortical potential (SCP) training and these sessions took place once a week. The ADHD children performed 20 sessions of NF training within 6 months. Pre-training and post-training assessments encompassed Continuous Performance Test (CPT), Stroop Test, Children's Color Trails Test I&II (CCTT) and Wisconsin Card Sorting Test (WCST). Results : Patients receiving NF training showed significant improvement in visual commission error and standard deviation of auditory response time on CPT ; and total errors on WCST. But there was no significant improvement in the Stroop test and CCTT. Conclusion : SCP training using NF improves the self-regulatory capacities and impulsivity in ADHD patient, especially impulsivity in visual stimulation tasks. This study showed evidence of clinical efficacy of NF on executive function in ADHD.

• Advances in aircraft and spacecraft science
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• 제3권2호
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• pp.197-209
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• 2016

The Spacecraft (S/C) numerical sine test-predictions are usually performed through Finite Element Method (FEM) Frequency Response Analysis (FRA), that is the hypothesis of steady-state responses to harmonic excitation to the S/C base is made. In the test practice, the responses are transient and may be significantly different from those predicted through FRA. One of the most significant causes of discrepancy between prediction and test consists in the beating phenomena. After a brief overview of the topic, the typical causes of beating are described in the first part of the paper. Subsequently, focus is made on the sine sweep rate effect, which often leads to have beatings after the resonance of weakly damped modes. In this work, the approach illustrated in the literature for calculating the sine sweep rate effect in the case of Single-Degree-Of-Freedom (SDOF) oscillators is extended to Multi-Degrees-Of-Freedom (MDOF) systems, with the aim of increasing the accuracy of the numerical sine test-predictions. Assumptions and limitations of the proposed methodology are detailed along the paper. Several assessments with test results are discussed and commented.

• Advances in aircraft and spacecraft science
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• 제2권3호
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• pp.275-302
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• 2015

Theoretical and numerical assessments of approximate evaluations and simplified analyses of piezoelectric structures transverse shear modal effective electromechanical coupling coefficient (EMCC) are presented. Therefore, the latter is first introduced theoretically and its approximate evaluations are reviewed; then, three-dimensional (3D) and simplified two-dimensional (2D) plane-strain (PStrain) and plane-stress (PStress) piezoelectric constitutive behaviors of electroded shear piezoceramic patches are derived and corresponding expected short-circuit (SC) and open-circuit (OC) frequencies and resulting EMCC are discussed; next, using a piezoceramic shear sandwich beam cantilever typical benchmark, a 3D finite element (FE) assessment of different evaluation techniques of the shear modal effective EMCC is conducted, including the equipotential (EP) constraints effect; finally, 2D PStrain and PStress FE modal analyses under SC and OC electric conditions, are conducted and corresponding results (SC/OC frequencies and resulting effective EMCC) are compared to 3D ones. It is found that: (i) physical EP constraints reduce drastically the shear modal effective EMCC; (ii) PStress and PStrain results depend strongly on the filling foam stiffness, rendering inadequate the use of popular equivalent single layer models for the transverse shear-mode sandwich configuration; (iii) in contrary to results of piezoelectric shunted damping and energy harvesting popular single-degree-of-freedom-based models, transverse shear modal effective EMCC values are very small in particular for the first mode which is the common target of these applications.

• Nuclear Engineering and Technology
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• 제50권6호
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• pp.860-868
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• 2018

This article presents a new design of earthquake instrumentation that is suitable for quick decision-making after the seismic event at the nuclear power plant (NPP). The main objective of this work is to ensure more availability of the NPP by expediting walk-down period when the seismic wave is incident. In general, the decision-making to restart the NPP after the seismic event requires more than 1 month if an earthquake exceeds operating basis earthquake level. It affects to the plant availability significantly. Unnecessary shutdown can be skipped through quick assessments of operating basis earthquake, safe shutdown earthquake events, and damage status to structure, system, and components. Multidecision parameters such as cumulative absolute velocity, peak ground acceleration, Modified Mercalli Intensity Scale, floor response spectrum, and cumulative fatigue are discussed. The implementation scope on the field-programmable gate array platform of this work is limited to cumulative absolute velocity, peak ground acceleration, and Modified Mercalli Intensity. It can ensure better availability of the plant through integrated decision-making process by automatic assessment of NPP structure, system, and components.

• 의학교육논단
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• 제23권3호
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• pp.154-159
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• 2021

The coronavirus disease 2019 (COVID-19) pandemic has profoundly impacted all aspects of undergraduate, postgraduate, and continuing medical education. Only the focus of medical education-care for patients and communities-has remained an integral part of all of the above sectors. Several challenges have been experienced by learners and educators as the education and training of future doctors has continued in the midst of this crisis, including the cancellation of face-to-face classes and training, reduced patient encounter opportunities, fairness issues in online assessments, disruption of patient interview-based exams, reflections on the role of doctors in society, and mental health-related problems linked to isolation and concerns about infection. In response to these disruptions, educators and institutions have rapidly deployed educational innovations. Schools have adopted educational strategies to overcome these challenges by implementing novel education delivery methods in an online format, providing clinical experiences through simulation or telehealth methods, introducing online assessment tools with formative purposes, encouraging learners' involvement in nonclinical activities such as community service, and making available resources and programs to sustain learners' mental health and wellness. During the COVID-19 pandemic, educators and institutions have faced drastic changes in medical education worldwide. At the same time, the quantitative expansion of online education has caused other problems, such as the lack of human collaboration. The long-term effects of the COVID-19 pandemic on medical education need to be studied further.

• Geomechanics and Engineering
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• 제34권4호
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• pp.341-380
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• 2023

This study evaluates the seismic fragilities in fill slopes in South Korea through parametric finite element analyses that have been barely investigated thus far. We consider three slope geometries for a slope of height 10 m and three slope angles, and two soil types, namely frictional and frictionless, associated with two soil states, loose and dense for frictional soils and soft and stiff for frictionless soils. The input ground motions accounting for four site conditions in South Korea are obtained from one-dimensional site response analyses. By comparing the numerical modeling of slopes using PLAXIS^2D against the previous studies, we compiled suites of the maximum permanent slope displacement (D_max) against two ground motion parameters, namely, peak ground acceleration (PGA) and Arias Intensity (I_A). A probabilistic seismic demand model is adopted to compute the probabilities of exceeding three limit states (minor, moderate, and extensive). We propose multiple seismic fragility curves as functions of a single ground motion parameter and numerous seismic fragility surfaces as functions of two ground motion parameters. The results show that soil type, slope angle, and input ground motion influence these probabilities, and are expected to help regional authorities and engineers assess the seismic fragility of fill slopes in the road systems in South Korea.

• Asian-Australasian Journal of Animal Sciences
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• 제17권10호
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• pp.1438-1445
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• 2004

The objective of this study was to determine the effects of dietary Zn level on performance, serum Zn concentrations, alkaline phosphatase activity (ALP), and immune response of pigs inoculated with Porcine Reproductive and Respiratory Syndrome virus (PRRSv) and Mycoplasma hyopneumoniae. A $2{\times}4$ factorial arrangement of treatments was used in a randomized design. Factors included; 1) PRRSv and M. hyopneumoniae inoculation (n=36 pigs) or sham inoculation (n=36 pigs) with media when pigs entered the grower facility (d 0) at 9 weeks of age and 2) 10, 50, 150 ppm supplemental Zn sulfate (${ZnSO}_4$) from weaning until the completion of the study, or 2,000 ppm supplemental ${ZnSO}_4$for two weeks in the nursery and then supplementation with 150 ppm ${ZnSO}_4$for the remainder of the trial. The basal diet contained 34 ppm Zn. Pigs were weighed on d 0, 10, 17, 24 and 31 and blood samples were collected on d 0, 7, 14, 21 and 28. Pigs inoculated with PRRSv were serologically positive at d 28 and control pigs remained negative to PRRSv. In contrast, the M hyopneumoniae inoculation was inconsistent with 33.3% and 52.8% of pigs serologically positive at d 28 in the control and infected groups, respectively. A febrile response was observed for approximately one week after inoculation with PRRSv. Feed intake (p<0.01) and gain (p<0.1) were less in PRRSv infected pigs than control pigs for the 31 d study. However, performance did not differ among pigs in the four levels of ${ZnSO}_4$. Assessments of immune responses failed to provide unequivocal influence of either PRRSv inoculation or ${ZnSO}_4$level. These data suggest that PRRSv and M. hyopneumoniae act to produce some performance deficits and the influence of Zn supplementation of nursery age pigs does not have clear effect in grower pigs affected with disease.

• 한국안광학회지
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• 제20권2호
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• pp.117-124
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• 2015

목적: 모노비전, 변형된 모노비전 및 비구면 멀티포컬 소프트콘택트렌즈로 교정 시 20대 성인에서 근거리 작업 후 조절기능의 변화를 비교하였다. 방법: 30명의 젊은 성인($23.53{\pm}2.37$세)을 대상으로 모노비전, 단초점 콘택트렌즈와 낮은 가입도의 중심부-근용 비구면 다초점 콘택트렌즈를 활용한 변형된 모노비전, 멀티포컬 콘택트렌즈의 교정방법을 사용하여 양안에 착용시키고, 일주일의 적응기간이 경과한 후 조절기능을 검사하였다. 조절기능 평가는 콘택트렌즈를 착용하고 1시간 동안 동영상을 시청하여 조절 부담을 유도한 후 원/근거리의 100%와 10% 대비시력, 조절반응, 근거리 조절용이성, 양성/음성상대조절력 등을 평가하였다. 모든 검사는 양안으로 실행하였다. 결과: 원거리 10% 대비시력은 모노비전에서 가장 낮았다(p<0.005). 조절반응량은 검사거리 1 m(1.00 D)에서 모노비전이 변형된 모노비전보다 작았고, 검사거리 40 cm(2.50 D)에서는 모노비전이 변형된 모노비전, 멀티포컬 콘택트렌즈보다 작았다(p<0.05). 근거리 조절용이성, 양성/음성상대조절력은 콘택트렌즈 교정법 사이에 차이가 없었다. 결론: 20대 성인에서 낮은 가입도의 모노비전 처방은 단초점렌즈보다 근거리 조절반응을 줄여주지만 중심부-근용 멀티포컬 콘택트렌즈를 이용한 '변형된 모노비전'과 멀티포컬 콘택트렌즈 처방은 조절이완에 영향을 주지 않는 것으로 생각된다.