• The Korean Journal of Pain
• /
• 제36권2호
• /
• pp.208-215
• /
• 2023

Background: To evaluate the feasibility, inter-reader reliability, and intra-reader reliability for various morphological features reported to be related to iliotibial band friction syndrome (ITBFS) on knee magnetic resonance imaging (MRI). Methods: A total of 145 patients with a clinical diagnosis and knee MRI findings consistent with ITBFS were included in the "study group" and 232 patients without knee pathology on both physical examination and MRI were included in the "control group". Various morphologic features on knee MRI were assessed including the patella shape, patella height, lateral epicondyle anterior-posterior (AP) width, lateral epicondyle height, ITB diameter (ITB-d), and ITB area (ITB-a). Results: Patients in the study group had significantly higher lateral epicondyle height (13.9 mm vs. 12.92 mm, P = 0.003), ITB-d (2.9 mm vs. 2.0 mm, P = 0.022), and ITB-a (38.5 mm² vs. 23.8 mm², P < 0.001) than the control group. ITB-a showed higher area under the curve index (0.849 with 74.1% sensitivity and 72.4% specificity at a 30.3 mm² cutoff) than ITB-d (0.710 with 70.8% sensitivity and 61.2% specificity at 2.4 mm cutoff) and lateral epicondyle height (0.776 with 72.4% sensitivity and 67.8% specificity at 13.4 mm cutoff). However, only the inter-reader agreement for ITB-a (intraclass correlation coefficient = 0.65) was moderate, while the agreements for other morphologic features were good or excellent. Conclusions: Lateral epicondyle height seems to be a reliable and feasible morphologic feature for diagnosis of ITBFS.

• 한국가스학회지
• /
• 제20권5호
• /
• pp.1-8
• /
• 2016

최소자연발화온도는 가연성물질이 주위의 열에 의해 스스로 발화하는 최저온도이다. 최소자연발화온도는 유기혼합물중 가연성 액체혼합물의 안전한 취급을 위해서 중요한 지표가 된다. 본 연구에서는 ASTM E659 장치를 이용하여 가연성 혼합물인 n-butanol+p-xylene 혼합물의 최소자연발화온도를 측정하였다. 2성분계를 구성하는 순수물질인 n-butanol과 p-xylene의 최소자연발화온도는 각 각 $340^{\circ}C$, $557^{\circ}C$로 측정되었다. 그리고 측정된 n-butanol+p-xylene 혼합물의 최소자연발화온도는 제시된 식에 의한 예측값과 적은 평균절대오차에서 일치하였다.

• Smart Structures and Systems
• /
• 제7권4호
• /
• pp.263-274
• /
• 2011

A reliability-based slope stability assessment method considering fluctuations in the monitored matric suction was proposed for real-time identification of slope risk. The assessment model was based on the limit equilibrium model for infinite slope failure. The first-order reliability method (FORM) was adopted to calculate the probability of slope failure, and results of the model were compared with Monte-Carlo Simulation (MCS) results to validate the accuracy and efficiency of the model. The analysis shows that a model based on Advanced First-Order Reliability Method (AFORM) generates results that are in relatively good agreement with those of the MCS, using a relatively small number of function calls. The contribution of random variables to the slope reliability index was also examined using sensitivity analysis. The results of sensitivity analysis indicate that the effective cohesion c' is a significant variable at low values of mean matric suction, whereas matric suction ($u_a-u_w$) is the most influential factor at high mean suction values. Finally, the reliability indices of an unsaturated model soil slope, which was monitored by a wireless matric suction measurement system, were illustrated as 2D images using the suggested probabilistic model.

• 대한기계학회논문집A
• /
• 제24권9호
• /
• pp.2361-2370
• /
• 2000

The introduction of inexpensive cylinder pressure sensors provides new opportunities for precise engine control. This paper presents a control strategy of spark advance based upon cylinder pressure of spark ignition engines. A location of peak pressure(LPP) is the major parameter for controlling the spark timing, and also the UP is estimated, using a multi-layer feedforward neural network, which needs only five pressure sensor output voltage samples at -40˚, -20˚, 0˚, 20˚, 40˚ after top dead center. The neural network plays an important role in mitigating the A/D conversion load of an electronic engine controller by increasing the sampling interval from 10 crank angle(CA) to 20˚ CA. A proposed control algorithm does not need a sensor calibration and pegging(bias calculation) procedure because the neural network estimates the UP from the raw sensor output voltage. The estimated LPP can be regarded as a good index for combustion phasing, and can also be used as an MBT control parameter. The feasibility of this methodology is closely examined through steady and transient engine operations to control individual cylinder spark advance. The experimental results have revealed a favorable agreement of individual cylinder optimal combustion phasing.

• 에너지공학
• /
• 제25권1호
• /
• pp.48-55
• /
• 2016

최소자연발화온도는 가연성물질이 주위의 열에 의해 스스로 발화하는 최저온도이다. 최소자연발화온도는 유기혼합물중 가연성 액체혼합물의 안전한 취급을 위해서 중요한 지표가 된다. 본 연구에서는 ASTM E659 장치를 이용하여 가연성 혼합물인 n-hexanol+p-xylene 계의 최소자연발화온도를 측정하였다. 2성분계를 구성하는 순수물질인 n-hexanol과 p-xylene의 최소자연발화온도는 각 각 $275^{\circ}C$, $557^{\circ}C$로 측정되었다. 그리고 측정된 n-hexanol+p-xylene 계의 최소자연발화온도는 제시된 식에 의한 예측값과 적은 평균절대오차에서 일치하였다.

• 한국화재소방학회논문지
• /
• 제26권3호
• /
• pp.85-90
• /
• 2012

최소자연발화온도는 가연성물질이 주위의 열에 의해 스스로 발화하는 최저온도이다. 최소자연발화온도는 유기혼합물 중 가연성 액체혼합물의 안전한 취급을 위해서 중요한 지표가 된다. 본 연구에서는 ASTM E659 장치를 이용하여 가연성 혼합물인 n-Decane+sec-Butanol 계의 최소자연발화온도를 측정하였다. 2성분계를 구성하는 순수물질인 n-Decane과 sec-Butanol의 최소자연발화온도는 각 각 $211^{\circ}C$, $447^{\circ}C$로 측정되었다. 그리고 측정된 n-Decane+sec-Butanol계의 최소자연발화온도는 제시된 식에 의한 예측값과 적은 평균절대오차에서 일치하였다.

• 한국화재소방학회논문지
• /
• 제28권4호
• /
• pp.44-49
• /
• 2014

혼합물의 최소자연발화온도는 가연성액체의 안전한 취급을 위해서 중요한 지표가 된다. 본 연구에서는 ASTM E659 장치를 이용하여 가연성 혼합물인 Propionic acid와 3-Hexanone 계의 최소자연발화온도와 발화지연시간을 측정하였다. 2성분계를 구성하는 순수물질인 Propionic acid와 3-Hexanone 계의 최소자연발화온도는 각 각 $511^{\circ}C$와 $425^{\circ}C$로 측정되었다. 그리고 측정된 Propionic acid와 3-Hexanone 혼합물의 최소자연발화온도 실험값은 제시된 식에 의한 예측값과 적은 평균절대오차에서 일치하였다. 그리고 Propionic acid와 3-Hexanone 계는 일부 혼합 조성에서 두 개의 순수물질 가운데 작은 AIT 보다 낮게 측정된 AIT를 보이는 최소자연발화온도거동(Minimum Autoignition Temperature Behavior, MAITB)을 보이고 있다.

• 한국화재소방학회논문지
• /
• 제26권5호
• /
• pp.48-53
• /
• 2012

최소자연발화온도는 가연성액체의 안전한 취급을 위해서 중요한 지표가 된다. 본 연구에서는 ASTM E659 장치를 이용하여 가연성 혼합물인 n-Butanol+sec-Butanol 계의 최소자연발화온도와 발화지연시간을 측정하였다. 2성분계를 구성하는 순수물질인 n-Butanol과 sec-Butanol의 최소자연발화온도는 각 각 $340^{\circ}C$, $447^{\circ}C$로 측정되었다. 그리고 측정된 n-Butanol+sec-Butanol 계의 최소자연발화온도는 제시된 식에 의한 예측값과 적은 평균절대오차에서 일치하였다.

• 한국화재소방학회논문지
• /
• 제27권1호
• /
• pp.8-13
• /
• 2013

최소자연발화온도는 가연성액체의 안전한 취급을 위해서 중요한 지표가 된다. 본 연구에서는 ASTM E659 장치를 이용하여 가연성 혼합물인 Benzene과 n-Hexane 계의 최소자연발화온도와 발화지연시간을 측정하였다. 2성분계를 구성하는 순수물질인 Benzene과 n-Hexane의 최소자연발화온도는 각 각 $583^{\circ}C$, $240^{\circ}C$로 측정되었다. 그리고 측정된 Benzene과 n-Hexane 계의 최소자연발화온도는 제시된 식에 의한 예측값과 적은 평균절대오차에서 일치하였다.

• Advances in concrete construction
• /
• 제9권5호
• /
• pp.511-527
• /
• 2020

The main aim of the current research is to investigate the flexural behavior of the reinforced concrete (RC) slabs strengthened with strain hardening cementitious composites (SHCC) experimentally and numerically. Seven RC slabs were prepared and tested under four-points loading test. One un-strengthened slab considered as control specimen while six RC slabs were strengthened with reinforced SHCC layers. The SHCC layers had different reinforcement ratios and different thicknesses. The results showed that the proposed strengthening techniques significantly increased the ultimate failure load and the ductility index up to 25% and 22%, respectively, compared to the control RC slab. Moreover, a three dimensional (3D) finite element model was proposed to analyze the strengthened RC slabs. It was found that the results of the proposed numerical model well agreed with the experimental responses. The validated numerical model used to study many parameters of the SHCC layer such as the reinforcement ratios and the different thicknesses. In addition, steel connectors were suggested to adjoin the concrete/SHCC interface to enhance the flexural performance of the strengthened RC slabs. It was noticed that using the SHCC layer with thickness over 40 mm changed the failure mode from the concrete cover separation to the SHCC layer debonding. Also, the steel connectors prevented the debonding failure pattern and enhanced both the ultimate failure load and the ductility index. Furthermore, a theoretical equation was proposed to predict the ultimate load of the tested RC slabs. The theoretical and experimental ultimate loads are seen to be in fairly good agreement.