• Journal of the Korean Society of Safety
• /
• v.27 no.1
• /
• pp.1-6
• /
• 2012

In crowded subway stations indoor air quality (IAQ) is a key factor for ensuring the safety and health of passengers. Since physical variables that describing IAQ such as the concentration of particulate, $CO_2$, VOCs and biological agents need to be closely monitored and controlled in multiple locations within subway stations and in remote sites, concept of web-based monitoring and control network using both wireless and wired media needs to be implemented. Connecting remote wireless sensor network and device (LonWorks) networks to the IP network based on the concept of VDN can provide a powerful, integrated, distributed monitoring and control performance. In this study, performance of wireless and wired network in VDN for monitoring and control of IAQ in subway stations is evaluated. Specifically, delay induced in wireless and wired networks, and data transmission rate are evaluated. A key parameter is identified in assuring safety and health of passengers in subway stations.

• Smart Structures and Systems
• /
• v.23 no.4
• /
• pp.359-371
• /
• 2019

As part of a structural health monitoring system, the relative geometric relationship between a ship and bridge has been recognized as important for bridge authorities and ship owners to avoid ship-bridge collision. This study proposes a novel computer vision method for the real-time geometric parameter identification of moving ships based on a single shot multibox detector (SSD) by using transfer learning techniques and monocular vision. The identification framework consists of ship detection (coarse scale) and geometric parameter calculation (fine scale) modules. For the ship detection, the SSD, which is a deep learning algorithm, was employed and fine-tuned by ship image samples downloaded from the Internet to obtain the rectangle regions of interest in the coarse scale. Subsequently, for the geometric parameter calculation, an accurate ship contour is created using morphological operations within the saturation channel in hue, saturation, and value color space. Furthermore, a local coordinate system was constructed using projective geometry transformation to calculate the geometric parameters of ships, such as width, length, height, localization, and velocity. The application of the proposed method to in situ video images, obtained from cameras set on the girder of the Wuhan Yangtze River Bridge above the shipping channel, confirmed the efficiency, accuracy, and effectiveness of the proposed method.

• Smart Structures and Systems
• /
• v.26 no.6
• /
• pp.735-751
• /
• 2020

Identification of structure parameters is crucial in Structural Health Monitoring (SHM) context for activities such as model validation, damage assessment and signal processing of structure response. In this paper, guided waves generated by piezoelectric transducers are used for in-situ and non-destructive structural parameter estimation based on Bayesian approach. As Bayesian approach needs iterative process, which is computationally expensive, this paper proposes a method in which an analytical model is selected and developed in order to decrease computational time and complexity of modeling. An experimental set-up is implemented to estimate three target elastic and geometrical parameters: Young's modulus, Poisson ratio and thickness of aluminum and steel plates. Experimental and simulated data are combined in a Bayesian framework for parameter identification. A significant accuracy is achieved regarding estimation of target parameters with maximum error of 8, 11 and 17 percent respectively. Moreover, the limitation of analytical model concerning boundary reflections is addressed and managed experimentally. Pulse excitation is selected as it can excite the structure in a wide frequency range contrary to conventional tone burst excitation. The results show that the proposed non-destructive method can be used in service for estimation of material and geometrical properties of structure in industrial applications.

• Environmental Analysis Health and Toxicology
• /
• v.23 no.4
• /
• pp.307-314
• /
• 2008

폐기물 매립지의 조기 안전화를 위해 여러 가지 Chemical Oxidation법이 개발되어 왔지만, 이 방법을 폐기물 매립지에 적용하고 난 후에 생성될 수 있는 부산물들이 주변 환경에 영향을 줄 가능성이 있다. 그래서, 이 방법을 실제 매립지에 적용하기 전에, 일본 키타큐슈에 있는 소각재가 묻혀 있는 모형 매립지에 다섯 가지 조건 -A, 콤포스트 추가; B, 과산화수소수 살수; 과산화수소수+공기주입; D, 공기주입; E, control- 을 적용하여 그 효능을 테스트하였고, 이 매립지에서 이 방법들의 적용 후에 생성되는 침출수의 급성 독성을 세 가지 microbiotests를 이용하여 monitoring하였다. 테스트 기간 중, 침출수의 수질은 개선되었고, 그 급성 독성은 점차적으로 감소하였다. 과산화수소수와 공기의 조합을 적용한 후 생성된 침출수의 급성 독성이 가장 빨리 감소하여 폐기물 매립지의 조기 안정화에 도움을 주었다. 이러한 독성 시험 결과는 몇 가지 화학적 parameters와 상관성이 있었고 여기에 사용된 급성 독성 테스트법은, 매립지 안정화를 위한 Chemical Oxidation법의 적용 후, 침출수 수질을 monitoring하는데 적절하였다. 그러므로 폐기물 매립지의 조기 폐지 기준에 독성 시험의 포함을 고려해 볼 필요가 있다고 생각한다.

• Journal of the Korean Academy of Child and Adolescent Psychiatry
• /
• v.31 no.1
• /
• pp.5-25
• /
• 2020

Objectives: Adult attention-deficit/hyperactivity disorder (ADHD) is an important mental health problem that needs resolution, especially considering the high rates of ADHD continuation from childhood to adolescence/adulthood and the high prevalence of ADHD in adults. Adults with ADHD have lifelong negative impacts and require close monitoring with long-term follow-up. Hence, the establishment of a Korean practice parameter for adult ADHD is necessary to minimize discontinuation of treatment and enable information sharing among Korean mental health professionals. Methods: The Korean practice parameter was developed using an evidence-based approach consisting of expert consensus survey coupled with literature review. Results: According to the expert consensus survey, the most commonly used diagnostic methods were clinical psychiatric interview (20.66%) and self-report scales (19.25%) followed by attention (14.71%) and psychological tests (14.24%). Key evaluation instruments currently available in Korea are the World Health Organization Adult ADHD Self-Report Rating Scale, Korean Adult ADHD Rating Scale, Diagnostic Interview for ADHD in Adults, Barkley Deficits in Executive Functioning Scale for adults, Comprehensive Attention Test, Conners' Continuous Performance Test, and the subtests of Wechsler Adult Intelligence Scale, Digit Span and Letter-Number Sequencing. Although pharmacotherapy is recommended as the first-line of treatment for adult ADHD, we recommend that it be followed by a multimodal and multidisciplinary approach including psychoeducation, pharmacotherapy, cognitive behavior therapy and coaching. Conclusion: The Korean practice parameter introduces not only general information for the diagnosis and treatment of adult ADHD on a global scale, but also the process of diagnosis and treatment options tailored to the Korean population.

• Structural Monitoring and Maintenance
• /
• v.3 no.4
• /
• pp.395-406
• /
• 2016

Modal parameter identification has received much attention recently for their usefulness in earthquake engineering, damage detection and structural health monitoring. The identification method based on Matrix Pencil technique is adopted in this paper to identify structural modal parameters, such as natural frequencies, damping ratios and modal shapes using impulse vibration responses. This method can also be applied to dynamic responses induced by stationary and white-noise inputs since the auto- and cross-correlation function of the two outputs has the same form as the impulse response dynamic functions. Matrix Pencil method is very robust to noise contained in the measurement data. It has a lower variance of estimates of the parameters of interest than the Polynomial Method, and is also computationally more efficient. The numerical simulation results show that this technique can identify modal parameters accurately even if the noise level is high.

• Journal of the Optical Society of Korea
• /
• v.9 no.3
• /
• pp.107-110
• /
• 2005

An optical method of measuring hematocrit noninvasively is presented. An LED Light with multiple wavelengths was irradiated on fingernail and transmitted light from the finger was measured to predict hematocrit. A finger probe contained an LED array and detector. Our previous experience showed that prediction accuracy was sensitive to reliability of the finger probe hardware and we optimized the finger probe parameters such as the internal color, detector area and the emission area of a light source based on Design of Experiment. Using the optimized finger probe, we developed a hematocrit monitoring system and tested with 549 persons. For the calibration model with 368 persons, a regression coefficient of 0.74 and a standard deviation of 3.67 and the mean percent error of $8\%$ were obtained. Hematocrits for 181 persons were predicted. We achieved a mean percent error of $8.2\%$ where the regression coefficient was 0.68 and the standard deviation was 3.69.

• Structural Monitoring and Maintenance
• /
• v.9 no.2
• /
• pp.157-177
• /
• 2022

In this paper, an innovative finite element updating method is presented based on the variation wavelet transform coefficients of Auto/cross-correlations function (WTCF). The Quasi-linear sensitivity of the wavelet coefficients of the WTCF concerning the structural parameters is evaluated based on incomplete measured structural responses. The proposed algorithm is used to estimate the structural parameters of truss and plate models. By the solution of the sensitivity equation through the least-squares method, the finite element model of the structure is updated for estimation of the location and severity of structural damages simultaneously. Several damage scenarios have been considered for the studied structure. The parameter estimation results prove the high accuracy of the method considering measurement and mass modeling errors.

• Journal of Advanced Marine Engineering and Technology
• /
• v.10 no.3
• /
• pp.1-10
• /
• 1986

This paper describes a new, effective method developed at the National Research Council Canada for rolling element bearing incipient failure detection. This method can detect not only outer race damage, previously published, but also inner race damage with a 100% detection rate based on a sample size of 32. The prediction of the exact angular location of the damage spot along the raceway is illustrated and experimental confirmation is presented. For the first time, a statically measurable parameter for inner and outer race damage is introduced as a means of verifying other techniques which do not offer absolute proof, but resort only to "overwhelming evidence". A brief comparison with other methods such as Shock Pulse Method, Kurtosis Analysis and High Frequency Resonance Technique is presented. A computerized automatic monitoring system utilizing the new method is described and experimental results are presented.presented.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
• /
• 2008.10a
• /
• pp.265-269
• /
• 2008

Home health care with compact wearable units sounds to be a convenient solution for the elderly people living independently. This paper presents a method to detect fall from the other activities of daily living and also to classify those activities. This kind of ambulatory monitoring enables them to get an emergency help in the case of the fatal fall event and can provide their general health status by observing the activities being performed in daily life. A tri-axial accelerometer sensor is used to get the acceleration anomalies associated with the user's movements. The three axis acceleration data are transferred to the base station sensor node via an IEEE 802.15.4 compliant zigbee module. The base station sensor node sends the data to base station PC for an offline processing. This work shows the feature set preparation using the principal component analysis (PCA) for the designing of neural network. The work includes the most common activities of daily living (ADL) like Rest, Walk and Run along with the detection of fall events from ADL. The angle from the vertical is found to be the most significant feature parameter for classification of fall while mean, standard deviation and FFT coefficients were used as the feature parameter for classifying the other activities under consideration. The accuracy for detection of fall events is 86%. The overall accuracy for ADL and fall is 94%.