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The extension of the railway noise barrier, the construction of which began in the mid-1980s, has currently reached a total of 800 km. As the aging rate is expected to increase rapidly, maintenance through reasonable performance evaluation is required. In this study, a technique for evaluating the durability of railway noise barriers is proposed, considering the dynamic effect of train wind, which is generated when trains pass through noise barriers. The proposed method is based on the equivalent static load for the dynamic effect acting on the noise barrier, as presented in EN 16727-2-2, which considers the train speed, number of passages, length, height, natural frequency of the noise barrier, and distance from the center of the track in reviewing the dynamic effect; moreover, it calculates the durability performance using a performance rating matrix based on the number of trains passing per day and dynamic effects. It is expected that the proposed technique can be used to evaluate the performance of railway noise barriers according to the Railway Construction Act.

With the rapid increase in automobiles, the importance of reducing low-frequency noise is being emphasized for a comfortable urban environment. Helmholtz resonators are widely used to attenuate low-frequency noise over a narrow range. In this study, a slit-type soundproof panel is designed to achieve low-frequency noise attenuation in the range of 500 Hz to 1000 Hz with the characteristics of a Helmholtz resonator and the ability to pass air through the slits on the panel surface for reducing wind load. The basic dimension of the soundproof panel is determined using the classical formula and numerical analysis using a commercial program, COMSOL Multiphysics, for transmission loss prediction. From the numerical study, it is identified that the transmission loss performance is improved compared to the basic design according to the shape change and configuration method of the Helmholtz resonator. Although the correlation according to the shape change and configuration method cannot be derived, it is confirmed that it can be used as an effective method for deriving a soundproof panel design that satisfies the basic performance.

In these days, closed form solutions to estimate the strength increment in the local buckling strength due to the rotational stiffness of the closed-section ribs have been proposed through theoretical approaches using the energy methods and parametric numerical analysis. In this paper, the correlations between the local buckling strength of longitudinally stiffened plates and the rotational restraint stiffness of closed-sections ribs were thoroughly investigated through numerical analyses. Three-dimensional finite element models of longitudinally stiffened plates were obtained using ABAQUS, and a series of comprehensive parametric numerical analyses were conducted in order to reveal the influential design parameters for required rotational stiffness of closed-section ribs for reaching converged buckling strengths. Then, a simplified design equation for the required rotational stiffness for the stiffened plate buckling strength has been proposed, which are applicable for both flat and curved plates to achieve optimum design sections. The comparative study and trend analysis showed that the proposed design methods have a good correlation with the numerical analysis results. Finally, a series of design examples demonstrate a design process of the longitudinally stiffened plates with closed-section ribs by using the proposed design equations.

For an open-deck steel plate girder railway bridge with rail joints, frequent damage to the bridge members and a high level of noise and vibration occur. By installing continuous welded rail (CWR) to the bridge, it is possible to reduce the noise and impact force of the bridge. However, current girder–sleeper fasteners have low lateral resistance in nature and track buckling can occur when CWR is used on such a bridge. Therefore, a new girder-sleeper fastener with proper lateral resistance to prevent CWR track buckling is needed. In this study, the lateral resistance requirements of a girder-sleeper fastener are investigated through a series of finite element (FE) analyses and parametric study. The effect of peak lateral resistance of the fastener, curve radius, girder length, and lateral displacement of girder are examined. From the analysis results, the peak lateral resistance criterion of the girder–sleeper fastener is proposed for the design of a new fastener for CWR tracks on an open-deck steel plate girder bridge.

With the advent of artificial intelligence, the research paradigm in natural language processing has been transitioned from statistical methods to machine learning-based approaches. One application is to develop a deep learning-based language model that helps software engineers write code faster. Although there have already been many attempts to develop code auto-completion functionality from different research groups, a need to establish an in-house code has been identified for the following reasons: (1) a security-sensitive company (e.g., Samsung Electronics) may not want to utilize commercial tools given that there is a risk of leaked source codes and (2) commercial tools may not be applicable to the specific domain (e.g., SSD firmware development) especially if one needs to predict unique code patterns and style. This research proposes a hybrid approach that harnesses the synergy between machine learning techniques and advanced design methods aiming to develop a code auto-completion framework that helps firmware developers write code in a more efficient manner. The sensitivity analysis results show that the deterministic design results in reducing prediction accuracy as it generates output in some unexpected ways, while the probabilistic design provides a list of reasonable next code elements in which one could select it manually to increase prediction accuracy.

The open-deck steel plate girder bridge in service has been an issue due to noise and vibration as well as its damage-prone structural characteristics of direct connection between a bridge beam and a track panel. Recently in Korea, to cope with the issue, a more economical method of installing CWR (Continuous Welded Rail) is being conducted using a stiffer sleeper-beam fastener installation, appropriate support arrangement and bridge substructure reinforcement. In this paper, using the finite element multibody dynamic analysis technology, running safety analysis is conducted considering track irregularities, and the appropriateness of the current track geometry standards is reviewed. The dynamic analysis is performed using commercial programs, ABAQUS and VI-Rail. A 30 m long open-deck plate girder bridge is utilized in the analysis. From the analysis, it is observed that the modification of the current geometry standard on track irregularities needs be considered.

The design and application of eddy current brakes (ECBs) should be simple; further, ECBs should be used semi-permanently. This study aimed to determine major parameters for designing an ECB that can be applied to a small-scale wind turbine generator. To this end, an ECB was developed that could actuate without additional power, thus improving the efficiency of the generator. A series of simulations were conducted for a parametric study to pre-design ECBs suitable for small wind turbines. The six parameters chosen were disk thickness, number of magnets, radial location of magnets from center of disk, magnet pole arrangement, magnetic flux density, and rotational speed. The simulations were conducted on COMSOL Multiphysics. The results indicated that the number of magnets and magnet pole arrangements can significantly affect the performance curve of ECBs. Moreover, the disk thickness and rotational speed are linearly proportional to the braking torque.

Recent studies have shown that the rotational stiffness of longitudinally installed closed-section ribs increases the local buckling strength of thin plates. Thus, in this study, the equations for the buckling strength of compressively loaded stiffened plates, which reasonably account for the partially restrained effect, were theoretically derived using the principle of minimum potential energy. Through three-dimensional refined finite element analysis performed using ABAQUS that appropriately simulates the buckling of plates stiffened with rotational rigidities along the sides, a series of parametric numerical analyses were conducted to examine the variation in buckling stresses based on the influential parameters revealed from the theoretical formulas. Further simplified and readily applicable formulas for the strength increment factor were derived from a series of rigorous regression analyses on the parametric analysis results. A comparative study of the suggested approximate solutions and the numerical analysis results was carried out to validate the proposed method.

The elevated railway station, above which a train is passing, is vulnerable to noise and vibration compared to other station types. To better identify the vibration characteristics of the elevated railway station, the transferred vibration from approach bridges should be analyzed. In this paper, through experiments and simulations, the transfer characteristics of the vibration from approach bridges is analyzed. The study structure is Geomgok station and the anaylses are conducted using ABAQUS three dimensional numerical model. To identify the change in the transfer characteristics for various bearing types, the analyses are performed considering mechanical properties of bearing for railway bridges. The measurement is performed using the accelerometers attached to the approach bridges and the station structure along the passing path of trains.

선하역사 내부에 발생하는 소음을 저감하기 위해서는 진동의 감소가 필요하며, 보다 효 과적인 진동 저감 대책 수립을 위해서는 궤도-접속교량-구조물의 상호작용 특성을 감안 하여 열차 운행으로 발생하는 진동이 전달되는 경로 및 특성에 대한 명확한 이해가 필 요하다. 이 논문에서는 국내 선하역사 현황을 구조적으로 분류하고 대표 선하역사에 대 한 진동 측정을 통하여 역사에 발생하는 진동의 전달 특성을 분석하였다. 주파수응답을 통한 분석 결과 궤도의 진동이 역사로 전달되면서 고주파 성분이 큰 감소를 나타냈으 며, 일부 역사에서 저주파 대역 내 증폭 구간이 발견되었다. 플로팅궤도가 적용되거나 TPS 구조의 역사는 궤도로부터 전달되는 진동이 비교적 큰 감소를 나타냈다. 선하역사 진동전달 가속도 주파수영역 분석 c 2015 Koea Society of Diaster Information All rights reserved 철도 선하역사 진동 전달 특성의 실험적 분석 Experimental Analysis of Vibration Transfer Characteristics of an Elevated Railroad Station Sanghyun Choi, Yong Yoo, Jinho Kim, Segon Kwon a Department of Railroad Facility Engineering, Korea National University of Transportation, 157 Cheoldobangmulgwan-ro, Uiwang, Gyeonggi-do, 437-763, Republic of Korea b Korea Railroad Research Institute, 176 Cheoldobangmulgwan-ro, Uiwang, Gyeonggi-do, 437-757, Republic of Korea b Korail, 240 Joongang-ro, Dong=gu, Daejeon 300-720, Republic of Korea * Corresponding author. Tel. 82-31-460-5774. Fax. 82-31-460-5749. Email. ziminpa@krri.re.kr 1 Tel. 82-70-8855-1654. Email. schoi@ut.ac.kr ARTICLE HISTORY Recieved Feb. 23, 2015 Revised Mar. 05, 2015 Accepted Mar. 22, 2015 Journal of Korea Society of Disaster Information Vol.11 No.1 ❙ pp. 89 96 Available online at www.sodi.or.kr 1976-2208 c 2015 Korea Society of Disaster Information All rights reserved. http://dx.doi.org/10.15683/kosdi.2015.11.1.89 Journal of Korea Society of Disaster Information. Vol.11, No.1, pp.89 96

As the world energy consumption grows, the interest in marin energy resources is increasing. In excavating such resources, the marine riser which connects the floating structure and sea bed is an essential device. The riser system is often exposed to harsh ocean environment and thus vulnerable to damage. Since the failure of the riser system may cause serious economical loss as well as environmental problem, the structural integrity of the riser is very important. Generally, the riser is an extremely slender structure with a much smaller diameter than a length. Therefore, a structural integrity monitoring methodology for typical buildings and bridges may not be applicable. In this paper, the applicability of a damage identification method for a structure to a marine riser is examined via a numerical example. Also, recent research practices and findings for monitoring the behavior and the structural integrity of the marine riser are examined and summarized.

선하역사는 역사 건물의 상부에 위치한 노반구조물을 통하여 열차 운행으로 인한 진동이 직접 역사 구조물로 전달되므로 소음·진동에 취약한 구조이다. 선하역사 내부의 소음은 주 로 구조물의 진동으로 인하여 발생하는 고체소음이므로 보다 효율적인 진동 저감 대책의 수립을 위해서는 역사의 구조 형식, 부재 및 재료 등의 구성 요소에 따른 구조적 거동 및 감쇠 특성의 파악이 중요하다. 이 논문에서는 선하역사와 인접 교량과의 접속부의 역학적 특성에 따른 진동 특성 변화에 대한 검토 결과를 제시하였다. 해석 대상 역사는 대천역이 며, ABAQUS로 유한요소해석을 수행하였다. 접속부 특성은 접속 교량이 있는 경우와 없는 경우, 그리고 있는 경우 라멘식과 받침형식으로 구분하여 검토를 수행하였다. 선하역사 접속교량 받침 진동 상호작용 c 2014 Korea Society of Disaster Information All rights reserved 교량 접속부 특성을 고려한 선하역사의 진동 해석 Vibration Analysis of an Elevated Railroad Station Considering Station-Bridge Connection Characteristics Sanghyun Choi, Soonjung Kwon a Department of Railroad Facility Engineering, Korea National University of Transportation, 157 Cheoldobangmulgwan-ro, Uiwang, Gyeonggi-do, 437-763, Republic of Korea b Rairoad Convergence Technology Center, Korea National University of Transportation, 157 Cheoldobangmulgwan-ro, Uiwang, Gyeonggi-do, 437-763, Republic of Korea * Corresponding author. Tel. 82-70-8855-1654. Fax. 82-31-462-8205. Email. sjkwon21@hanmail.net 1 Tel. 82-70-8855-1654. Email. schoi@ut.ac.kr ARTICLE HISTORY Received Jun. 16, 2014 Revised Jun. 22, 2014 Accepted Jun. 30, 2014 Journal of Korea Society of Disaster Information Vol.10 No.2 ❙ pp. 274 281 Available online at www.kosdi.or.kr 1976-2208 c 2014 Korea Society of Disaster Information All rights reserved. S.H Choi et al. Journal of Korea Society of Diaster Information Vol.10 No.2 pp. 274 281, 2014

Nowadays, terms such as 'Smart Textile', 'Intelligent Textile' and 'Wearable Computing' are commonly used in everyday contexts. And radio-frequency identification (RFID) is the use of a wireless non-contact system that uses radio-frequency electromagnetic fields to transfer data from a tag attached to an object, for the purposes of automatic identification and tracking. These products are required technologies which are textile treatments, printing, ink, etc. Durability of textile substrates is an essential marker for conductive ink printing process. Especially, heat stability is important, since conductive ink should be processable (annealing, curing) at temperatures below 150 . This study was application of RFID

The importance of preserving the structural integrity of a containment can never be overemphasized. Currently the structural integrity of the containment is evaluated periodically via various nondestructive inspection methods. However, these methods can only provide local integrity data, and cannot deliver continuous monitoring information on overall structural integrity. In this paper, the result of a feasibility study on utilizing ambient vibration measurements to monitor the structural integrity of a containment is presented. The ambient vibration testing was selected, because it can avoid the interruption of normal operation of power plants. For the purpose of the study, the ambient vibration of four different containments in Korea, i.e. Ulchin Unit 5, Wolsong Unit 2, Ulchin Unit 1, and Yeonggwang Unit 4, was measured and modal parameters were extracted via frequency domain modal analysis techniques. The experimental modes were then compared to the analytical modes estimated using finite element analysis to examine the correlation, and highly correlated modes were adopted in identifying structural parameters using a system identification method. The structural parameter selected in this study was the elastic modulus of the concrete, and the identified moduli were compared to design values and inspection results. The result shows the ambient vibration can be utilized in monitoring the structural integrity of a containment, though further extensive study needs to be conducted to identify and exclude the effect of ambient conditions such as temperature and humidity on resonant frequencies.

In this study, we have fabricated an RFID tag antenna of the sewing type, and not the embroidery type. Inaddition, we have measured its impedance, return loss, and reading range. The sewing patterns of two different den-sities are fabricated, and the properties of the RFID tag antenna have been measured. The measurement results showthat the two-layer sewing pattern RFID tag antennas are better than the one-layer sewing pattern antennas. Upon com-parison, with regard to the effect of the sewing density, it is found that a lower density is a better property. The max-imum reading ranges are 70, 49, 84, and 85 cm, which are sufficiently long.Keywords: RFID, UHF RFID tag, sewing type RFID tag antenna 1. 서 론 최근 기존 전통산업의 성장 잠재력의 한계를 극복하기위해 산업간 융합을 통한 새로운 산업 및 기술을 발굴하려는 다양한 노력들이 산업전반에서 전개되고 있는 실정이다.특히 의복형태의 컴퓨터로 대표되는 웨어러블 컴퓨터는 섬유 및 의류 기술과 IT 기술과의 산업적 융합의 대표적인분야라고 할 수 있다[1]. RFID(Radio Frequency IDentification)는 무선으로 사물을 인식하는 기술로 기존의 바코드 시스템을 대체할 수 있을 뿐만 아니라, 새로운 물류응용 분야에 적용할 수 있는신기술로 주목 받고 있다. RFID 기술은 각 사물에 태그를부착하여 그 태그의 고유 ID를 무선으로 인식하여 정보를수집, 저장, 추적 관리함으로써 사물의 관리 서비스를 제공하는 기술이다[2,3]. 현재 정보인식 기술로 대중화된 방식은 바코드(bar code)와 마그네틱 카드(magnetic card)이다.저렴한 단가에도 불구하고 바코드는 물에 젖거나 오염 물질이 묻어 바코드가 손상되면 정보를 제대로 전달할 수 없다. 뿐만 아니라, 바코드와 마그네틱 카드 모두 아주 가까운 거리에서 접촉을 시켜야 정보가 인식된다는 단점을 안고 있다. 반면 RFID는 전파를 이용해 다양한 정보를 전달하기 때문에 이런 한계로 부터 자유롭다. 게다가 바코드가일직선상에서만, 또 한번에 하나씩의 매우 제한된 용량의데이터만 인식할 수 있는 반면, RFID는 동시에 여러 개의대용량의 정보를, 상당히 먼 거리에서도 인식하고 기록, 저장할 수 있다.

Most damage evaluation methods for a structure developed to date utilizes modal responses extracted from acceleration measurements, which involve inevitable errors during the extraction process. Also, displacements, obtained by integrating acceleration measurements, may contain serious deviation due to such errors as in initial conditions. However so far no attempt has been made to identify the feasibility of applying jerks and snaps in damage evaluation. In this study, the applicability of jerks and snaps to damage evaluation for a structure is conducted. The mean strain energy theory in time domain based on displacement measurements is utilized for the purpose of the study, and the feasibility of isolating local damage is verified via a numerical example of a simple beam. From the study, it is found that, unlike snaps, jerks can be utilized directly in evaluating damage in a structure.

In this paper, the performance verification study on a recently developed vertical vibration isolator is presented. The vertical seismic isolation system consists of four wedge-shape steel parts which provide friction surface at their interfaces, a center and two side springs, and a lateral bar which functions as a guide to side springs. The theoretical model for the isolator derived from the force equilibrium relationship is verified via numerical analyses and prototype tests. The performance of the isolator is further verified using the shaking table test. The analytical and experimental studies show that the isolator can reduce the vertical vibration effectively.

In this article, a CMOS multistandard wireless direct-conversion receiver is designed. The receiver is composed of three components: low noise amplifier, voltage-controlled oscillator, and mixer. In details, the designed receiver adopts direct-conversion architecture and accommodates three standards: WCDMA, Wibro (or mobile WIMAX), and CDMA 2000 1×: 1.84–2.4 GHz. The designed mixer is a passive sub-harmonic doubly balanced structure, the VCO is a back-gate coupling quadrature VCO, and the LNA is a differential structure. Each component is designed with relevance to direct-conversion architecture. The designed mixer has no flicker noise theoretically because the mixing transistors operate in the triode region. Also, DC offset problem is avoided, because local oscillator frequency is half of RF frequency and the port isolation is improved by the innate characteristic of a balanced structure. The VCO generates a quadrature signal and the oscillation frequency is half of RF frequency to drive designed sub-harmonic mixer. No coupling transistors are needed due to the use of back-gate coupling to reduce flicker noise. Back-gate coupling means that the body of a transistor is used as another gate. The LNA, which adopts a well-known cascade structure, is designed as a differential structure to suppress common mode noise and to drive a doubly balanced mixer. All designed components are fabricated by the TSMC 0.18-μm RF CMOS process. © 2010 Wiley Periodicals, Inc. Microwave Opt Technol Lett 52: 718–721, 2010; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.24989