• The Korean Journal of Pain
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• 제36권1호
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• pp.113-127
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• 2023

Background: Resting-state functional connectivity (rs-FC) may aid in understanding the link between painmodulating brain regions and the descending pain modulatory system (DPMS) in fibromyalgia (FM). This study investigated whether the differences in rs-FC of the primary somatosensory cortex in responders and non-responders to the conditioned pain modulation test (CPM-test) are related to pain, sleep quality, central sensitization, and the impact of FM on quality of life. Methods: This cross-sectional study included 33 females with FM. rs-FC was assessed by functional magnetic resonance imaging. Change in the numerical pain scale during the CPM-test assessed the DPMS function. Subjects were classified either as non-responders (i.e., DPMS dysfunction, n = 13) or responders (n = 20) to CPM-test. A generalized linear model (GLM) and a receiver operating characteristic (ROC) curve analysis were performed to check the accuracy of the rs-FC to differentiate each group. Results: Non-responders showed a decreased rs-FC between the left somatosensory cortex (S1) and the periaqueductal gray (PAG) (P < 0.001). The GLM analysis revealed that the S1-PAG rs-FC in the left-brain hemisphere was positively correlated with a central sensitization symptom and negatively correlated with sleep quality and pain scores. ROC curve analysis showed that left S1-PAG rs-FC offers a sensitivity and specificity of 85% or higher (area under the curve, 0.78, 95% confidence interval, 0.63-0.94) to discriminate who does/does not respond to the CPM-test. Conclusions: These results support using the rs-FC patterns in the left S1-PAG as a marker for predicting CPM-test response, which may aid in treatment individualization in FM patients.

• Structural Engineering and Mechanics
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• 제32권3호
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• pp.383-398
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• 2009

Applying nonlinear statistical analysis methods in estimating the performance of structures in earthquakes is strongly considered these days. This is due to the methods' simplicity, timely lower cost and reliable estimation in seismic responses in comparison with time-history nonlinear dynamic analysis. Among nonlinear methods, simplified to be incorporated in the future guidelines, Modal Pushover Analysis, known by the abbreviated name of MPA, simply models nonlinear behavior of structures; and presents a very proper estimation of nonlinear dynamic analysis using lateral load pattern appropriate to the mass. Mostly, two kinds of connecting joints, 'hinge' and 'rigid', are carried out in different type of steel structures. However, it should be highly considered that nominal hinge joints usually experience some percentages of fixity and nominal rigid connections do not employ totally rigid. Therefore, concerning the importance of these structures and the significant flexibility effect of connections on force distribution and elements deformation, these connections can be considered as semi-rigid with various percentages of fixity. Since it seems, the application and implementation of MPA method has not been studied on moment-resistant steel frames with semi rigid connections, this research focuses on this topic and issue. In this regard several rigid and semi-rigid steel bending frames with different percentages of fixity are selected. The structural design is performed based on weak beam and strong column. Followed by that, the MPA method is used as an approximated method and Nonlinear Response History Analysis (NL-RHA) as the exact one. Studying the performance of semi-rigid frames in height shows that MPA technique offers reasonably reliable results in these frames. The methods accuracy seems to decrease, when the number of stories increases and does decrease in correlation with the semi-rigidity percentages. This generally implies that the method can be used as a proper device in seismic estimation of different types of low and mid-rise buildings with semi-rigid connections.

• 대한토목학회논문집
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• 제14권1호
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• pp.171-178
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• 1994

본 연구에서는 연약지반에 시공한 단독말뚝에서 발생하는 주변마찰력과 이로 인해 유발되는 축하중 해석방법을 개발하고 해석결과를 유한요소해석 프로그램에 의한 예측결과 및 현장 실험값과 비교 분석하였다. 이때 말뚝과 지반의 접촉면에 국부파괴가 발생하는 경우(slip case)와 발생하지 않는 경우(no slip case)에 대해 고려하였다. 본 연구에서 말뚝의 지지층은 암반인 경우를 고려하였고 해석모형의 물성으로는 말뚝, 연약 지반, 암반층에 대하여 모두 일반적인 값들을 적용하였다. 해석결과를 유한요소해석 및 현장 실측값과 비교 분석한 결과, 말뚝에 발생하는 주면마찰력은 압밀도가 커짐에 따라 증가하며, 주면마찰력에 의해 유발되는 축하중은 압밀이 완료되는 시기에 최대의 값을 갖는다는 결론을 얻었다. 또한 복잡한 2차원 또는 3차원 비선형 거동 해석외에 간단한 1차원 압밀 이론을 적용한 해석 역시 비교적 정확한 결과를 얻을 수 있음을 알았다.

• 한국전산구조공학회논문집
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• 제24권6호
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• pp.655-662
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• 2011

본 논문에서는 다지점 가진 시 장대교량에 대한 지진응답해석을 수행하고 설계상의 다양한 요구에 유연하게 대처하기 위해서 다지점 가진 해석에 필요한 비선형시간이력해석 알고리즘(영향계수법)을 제안하고, 이를 신뢰성있는 비선형 유한요소해석 프로그램(RCAHEST)에 추가하였다. 동일한 유한요소모델에 대해 범용 유한요소해석 프로그램 SAP2000의 Multi-support Excitation 기능을 이용하여 연구에서의 결과에 대한 비교 검증을 수행하였다. 이 연구결과를 바탕으로 인천대교에 대해서 유한요소모델링을 실시하고 다지점 가진을 고려한 비선형시간이력해석을 수행하였다. 수평변위응답의 분석 결과 시간지연이 늘어날수록 최대 수평변위가 줄어드는 것을 확인할 수 있었다. 또한 입력지진파의 최대가속도를 단계적으로 증가시키며 극한해석을 수행하여 대상 교량의 사용성을 평가하였다.

• 한국음향학회지
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• 제39권3호
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• pp.216-225
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• 2020

본 논문은 음선 경로법에 기반한 광대역 수중음향 전달 채널을 모델링하는 방법을 다루었다. 수중음향 전달 채널은 종종 주파수 영역에서 시간 조화 함수로 취급되어, 광대역 시계열 신호 모의 시 활용이 어렵다. 따라서 수중 음파 전달 환경을 반영한 광대역 시간영역 모델링 기법이 요구되며, 본 논문에서는 이를 위해 시간영역에서 다중 경로의 도달 시간지연이 계산 가능한 고유 음선 분석 기법을 활용하였다. 또한 연속 시간의 파동방정식으로부터 산출된 고유 음선의 분석 결과를 컴퓨터 모의가 가능한 이산시간 시스템에 적용하기 위해, 음선의 위상, 주파수별 손실 및 도달 시간지연을 유한 임펄스 응답으로 근사하여, 광대역 수중음향 전달 채널을 모의하는 방법을 제안하였다.

• Advances in concrete construction
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• 제9권3호
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• pp.235-248
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• 2020

Progressive collapse in a structure occurs when load bearing members are failed and the adjoining structural elements cannot resist the redistributed forces and fails subsequently, that leads to complete collapse of structure. Recently, construction using precast concrete technology is adopted increasingly because it offers many advantages like faster construction, less requirement of skilled labours at site, reduced formwork and scaffolding, massive production with reduced amount of construction waste, better quality and better surface finishing as compared to conventional reinforced concrete construction. Connections are the critical elements for any precast structure, because in past, major collapse of precast structure took place because of connection failure. In this study, behavior of four different precast wet connections with U shaped reinforcement bars provided at different locations is evaluated. Reduced 1/3^rd scale precast beam column assemblies having two span beam and three columns with removed middle column are constructed and examined by performing experiments. The response of precast connections is compared with monolithic connection, under column removal scenario. The connection region of test specimens are filled by cast-in-place micro concrete with and without polypropylene fibers. Performance of specimen is evaluated on the basis of ultimate load carrying capacity, maximum deflection at the location of removed middle column, crack formation and failure propagation. Further, Finite element (FE) analysis is carried out for validation of experimental studies and understanding the performance of structural components. Monolithic and precast beam column assemblies are modeled using non-linear Finite Element (FE) analysis based software ABAQUS. Actual experimental conditions are simulated using appropriate boundary and loading conditions. Finite Element simulation results in terms of load versus deflection are compared with that of experimental study. The nonlinear FE analysis results shows good agreement with experimental results.

• 전기학회논문지
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• 제67권3호
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• pp.413-418
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• 2018

In this paper, we describe the development of a non-enzymatic glucose sensor based on copper nanocubes(Cu NCs) electroplated laser induced graphene(LIG) electrodes which can detect a certain range of glucose concentrations. $CO_2$ laser equipment was used to form LIG electrodes on the PI film. This fabrication method allows easy control of the LIG electrode size and shape. The Cu NCs were electrochemically deposited on the LIG electrodes to improve electron transfer rates and thus enhancing electrocatalytic reaction with glucose. The average sheet resistances before and after electroplating were $15.6{\Omega}/{\Box}$ and $19.6{\Omega}/{\Box}$, respectively, which confirmed that copper nanocubes were formed on the laser induced graphene electrodes. The prepared electrode was used to measure the current according to glucose concentration using an electrochemical method. The LIG electrodes with Cu NCs demonstrated a high degree of sensitivity ($1643.31{\mu}A/mM{\cdot}cm^2$), good stability with a linear response to glucose ranging from 0.05 mM to 1 mM concentration, and a limit of detection of 0.05 mM. In order to verify that these electrodes can be used as flexible devices, the electrodes were bent to $30^{\circ}$, $90^{\circ}$, and $180^{\circ}$ and cyclic voltammetry measurements were taken while the electrodes were bent. The measured data showed that the peak voltage was almost constant at 0.42 V and the signal was stable even in the flexed condition. Therefore, it is concluded that these electrodes can be used in flexible sensors for detecting glucose in the physiological sample like saliva, tear or sweat.

• Asian-Australasian Journal of Animal Sciences
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• 제14권7호
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• pp.1019-1023
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• 2001

An on-farm trial was conducted in temperature-controlled lactation rooms at a commercial pig farm to investigate the efficacy of broadcasting sow suckling grunts from day 4 of lactation, on increasing piglet growth to weaning. In the Broadcast treatment, sows and litters were exposed to a 3-min broadcast from loud-speakers every 42 min. The Control treatment was not exposed to the broadcast. All sows and litters had similar husbandry and piglets were provided with creep feed on the floor twice daily. In each of the three replicates in time, the Broadcast and Control treatments were allocated to different lactation rooms at random and there were 12 sows and litters per treatment per replicate. A total of four identical lactation rooms were available for the trial, each containing 28 conventional sow and litter crates with piglet heater in the creep area. A non-trial room separated the two treatment rooms in each replicate to minimise the chance that the broadcast grunt stimulation was audible to the Control treatment litters. Five "normal and average-looking" piglets from the trial litters were weighed twice, 7 d apart. The cohort of five piglets was identified by ear-tags and formed the experimental unit for the statistical analysis. The average (${\pm}SD$) age of piglets at initial weighing was 7.7(${\pm}2.22$) days. For each litter, mean piglet live weight at day 14 of lactation was estimated by linear regression of the two weights recorded seven days apart, when on average, the Broadcast treatment had been exposed to the stimulation for 10 days. Piglets in the Broadcast treatment were heavier (p<0.01) at day 14 of lactation compared to Control treatment (4.24 and 3.92 kg, respectively) and tended to have a greater average daily weight gain over the 7-d period (245 and 228 g/day, respectively; p<0.08). The results suggest piglet growth was improved by about 8% in response to the regular, timed broadcast of sow suckling grunts in the lactation shed. The independent contributions of milk and creep feed to the improved growth remain to be determined.

• Smart Structures and Systems
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• 제16권4호
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• pp.579-591
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• 2015

This paper investigates a magnetoelectric (ME) vibration energy harvester that can scavenge energy in arbitrary directions in a plane as well as wide working bandwidth. In this harvester, a circular cross-section cantilever rod is adopted to extract the external vibration energy due to the capability of it's free end oscillating in arbitrary in-plane directions. And permanent magnets are fixed to the free end of the cantilever rod, causing it to experience a non-linear force as it moves with respect to stationary ME transducers and magnets. The magnetically coupled cantilever rod exhibits a nonlinear and two-mode motion, and responds to vibration over a much broader frequency range than a standard cantilever. The effects of the magnetic field distribution and the magnetic force on the harvester's voltage response are investigated with the aim to obtain the optimal vibration energy harvesting performances. A prototype harvester was fabricated and experimentally tested, and the experimental results verified that the harvester can extract energy from arbitrary in-plane directions, and had maximum bandwidth of 5.5 Hz, and output power of 0.13 mW at an acceleration of 0.6 g (with $g=9.8ms^{-2}$).

• 한국지반신소재학회논문집
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• 제14권4호
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• pp.129-137
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• 2015

최근 해상풍력발전 단지 조성은 많은 양의 에너지를 창출할 수 있어 그 기대는 점차적으로 증가하고 있다. 특히 제주도는 풍황이 우수하여 해상풍력발전 시스템 운영을 위한 최적의 대상지이기는 하나, 화산활동에 의해 형성된 지형으로 육지부와 달리 현무암층 사이에 연약층인 화산쇄설물 및 공동이 불규칙하게 발달된 층상구조로 이루어져 있다. 이에 본 연구에서는 프레셔미터 시험으로부터 제주 현무암에 근입된 수평재하말뚝의 p-y 곡선을 유도하기 위하여 프랑스석유협회(IFP, 1983)과 Briaud et al.(1983)의 방법을 이용하였다. 이들의 방법을 이용하여 유도된 p-y 곡선을 LPILE 프로그램에 입력하여 말뚝두부에서 하중-변위 관계를 분석한 후 재하시험으로 측정된 하중-변위 곡선과 비교하였다. 결과, pressuremeter test로부터 제주 현무암에 근입된 수평재하말뚝의 p-y 곡선을 유도할 때 IFP 방법은 매우 합리적인 결과를 도출할 수 있을 것으로 판단된다.